<%BANNER%>

Remote Detection of Hydrogen Leaks Using Laser Induced Rayleigh/Mie Scattering

xml version 1.0 encoding UTF-8
REPORT xmlns http:www.fcla.edudlsmddaitss xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.fcla.edudlsmddaitssdaitssReport.xsd
INGEST IEID E20110321_AAAAAD INGEST_TIME 2011-03-21T04:06:15Z PACKAGE UFE0008972_00001
AGREEMENT_INFO ACCOUNT UF PROJECT UFDC
FILES
FILE SIZE 53065 DFID F20110321_AAAARZ ORIGIN DEPOSITOR PATH paranjpe_s_Page_42.jpg GLOBAL false PRESERVATION BIT MESSAGE_DIGEST ALGORITHM MD5
389a1e24f6481cd8a590e6cfa9de56e3
SHA-1
58d7f2991ce34f9bf8d99ec3c22dc80ab4baebed
791 F20110321_AAAAFH paranjpe_s_Page_10.txt
b2163080c9e51216516528e7c8b0928a
59b302278d2c398f833db23b12872ced14ce57a8
641 F20110321_AAAAPB paranjpe_s_Page_43.txt
faacc8ffe694346e5ef61932573051ff
8482c101a91634d55600a0ad9b453c62fe5ecd79
13513 F20110321_AAAAKE paranjpe_s_Page_61.QC.jpg
c66ad63033be8bbd4f875f133382b8a6
dde7309bc96441bc15b2cff79619294f60cc0ff4
818127 F20110321_AAAAFI paranjpe_s_Page_60.jp2
ab7cfacb3dd82761ce15a4cb72df48a5
d084153023358f3b6ddaf1dacb4bc9175e143d3c
1351 F20110321_AAAAPC paranjpe_s_Page_44.txt
a352e79a48d32dfedba4782bcc32c0fb
e3f95d225e3490d78ca44d09cba67bbfea9f4ede
1876 F20110321_AAAAKF paranjpe_s_Page_50.txt
50a30b8b2c150a2b361d0e7929e83893
cc6212c7f35416ab1d44d99a5ecef966d6f7a606
879223 F20110321_AAAAUA paranjpe_s_Page_41.jp2
b33cdf650835c15775213ad77e998175
c6bd7798664bb8cbc9aec679c6a99897fe0cd869
44139 F20110321_AAAAFJ paranjpe_s_Page_49.jpg
128f70766d594d526eb1430403e85e12
392240e7fafd02491878499135dde34a252ae978
1904 F20110321_AAAAPD paranjpe_s_Page_45.txt
48382ae2367e5ad9095ef533beeb43b2
ed8c10fd49faee5789f00330efbd0994270c29d5
103217 F20110321_AAAAKG paranjpe_s_Page_26.jp2
7222d734e0e5f22f4e126040e4032588
0f43ac521c9f77e7931c6f02c47105d26ac657ab
861079 F20110321_AAAAUB paranjpe_s_Page_45.jp2
848440d86e7fb295a18a73edf4355f42
f075e6e34127d3cbdfe71bc53ecad4ce87ce1931
1000971 F20110321_AAAAFK paranjpe_s_Page_68.jp2
a38f0050e40093ea489cd036d38b84cc
bf58005056d27cbec1fe93162a05bd4c70b40c36
2143 F20110321_AAAAPE paranjpe_s_Page_46.txt
8b02fc33e2165ad56c20d7c012d0c46c
c2ad8412e9909ac9800c77765f85adc5422b6314
1640 F20110321_AAAAKH paranjpe_s_Page_60.txt
0076b4401b01ea3a29755e0e1cebabe4
696c4d34bb260b1b0d456b3a3701945d33e8f8b5
587340 F20110321_AAAAUC paranjpe_s_Page_49.jp2
018fabc08641ce96511fe1294f57f119
1692a9281582610cb66e27054954f0e7d43536b9
31140 F20110321_AAAAFL paranjpe_s_Page_67.pro
425fee1f8e14f8159fc53abe9acef8e1
661f36ee2fec6d219c25ea2d5bbd24cb15ed1193
1509 F20110321_AAAAPF paranjpe_s_Page_51.txt
2d01851d802c40b39855e6def1aed003
90b352361ef672fca8369354397c54830411ca2b
57635 F20110321_AAAAKI paranjpe_s_Page_46.jpg
c645f11d853441a136ada5784c2c2e36
6f24fb56ef72d51db436237d437ae35dc2815afe
96823 F20110321_AAAAUD paranjpe_s_Page_50.jp2
3b2cdedbe939988becd136746cec8cb5
1065dc4af0c1b19adce4659d72a80c0f27ee639e
1822 F20110321_AAAAPG paranjpe_s_Page_56.txt
bce55124400c761ac49986775bb3c9d2
fc92ed985d9914dd7512962e22cf8571e1694131
5908 F20110321_AAAAKJ paranjpe_s_Page_35thm.jpg
c228078a628cc81c93e9cf42e10d4b3b
7c6e50577b6e1546919b7a86a4ac6bee19355189
805042 F20110321_AAAAUE paranjpe_s_Page_51.jp2
26dba86a9059c7218e69d14d9204b9d6
bf1847c88ed945206070304e8f448f88a23d9888
52944 F20110321_AAAAFM paranjpe_s_Page_23.jpg
1f741a7f985523c871b77978cb9c8ed7
7f05d78a281721fe5cf7375e8961740d7cd41729
1634 F20110321_AAAAPH paranjpe_s_Page_62.txt
593e8c61fa111cfb28df63838d8371e6
ba673f28457db73d59558d08f2fbaadb9ccf1cb0
38997 F20110321_AAAAKK paranjpe_s_Page_33.jpg
7c2d764dee795ba8e452375f003753e6
daaaea90f4dd0d39fdb548d641ae9c53fbac9839
639397 F20110321_AAAAUF paranjpe_s_Page_52.jp2
90cf902e33e9e448b245de5577e4fd63
5b6d64f57cc73eadf80f6c8c6bddf92249fa40d5
22101 F20110321_AAAAFN paranjpe_s_Page_09.pro
837b59c35b9453a37b3d88ac4cad8b52
8301d25a255754064d353250076b385d642e5722
1684 F20110321_AAAAPI paranjpe_s_Page_63.txt
39eca15cf84c6bbba297a990266ae595
534bbbf30d63e48299b634d9c9837ae9c49c507d
1053954 F20110321_AAAAKL paranjpe_s_Page_74.tif
df8104449807f3fc5033086288e72129
1d94b361a42f5c58e031128e97eda3a05c1bca0e
629521 F20110321_AAAAUG paranjpe_s_Page_64.jp2
ddeb8b8a29970dd95de7c0ac052c9feb
126876ad8f9fc11f8a4295a9a574d306d3dad10f
5618 F20110321_AAAAFO paranjpe_s_Page_30thm.jpg
c29a50ddac1f7c9b12e74f1e50c72811
84b1b4ea7f5e060002032b724dadd5f3b90b9486
1231 F20110321_AAAAPJ paranjpe_s_Page_66.txt
5d852574514ed6e26727e793c7add335
17bf511d1b8f8a00211b80304d28f844395a75a0
46593 F20110321_AAAAKM paranjpe_s_Page_32.pro
a94986c87ee191e5f28b96632a1ee786
66018283e0052ddb3f72bb4a60a56cddb2b378f0
738926 F20110321_AAAAUH paranjpe_s_Page_65.jp2
d6a5ddcb9da9512f8311d09a88109bce
7462089cdf60a73b7c596dde4d35a319303dfe6b
1370 F20110321_AAAAPK paranjpe_s_Page_67.txt
a8b7820b94d80e33baa3e34812890548
c8720c1eda369f0e620710f18279dd436a6e9b01
63396 F20110321_AAAAKN paranjpe_s_Page_53.jpg
17b32e5b2c7c3c1e05b3aacc5dc6d3ad
9f6984e6019b2d48e9ed0f2039e55a0109e30586
4546 F20110321_AAAAFP paranjpe_s_Page_44thm.jpg
9bf9ccb8bfb98ddaff8b66c3db953182
75e9c574b8d65781b4ac13c021cd197f50142b40
698871 F20110321_AAAAUI paranjpe_s_Page_66.jp2
f340cd719f795555d0740d2eeef20a1b
2fac8af415c3bafd070e6198227a73f2a46fbb94
805 F20110321_AAAAPL paranjpe_s_Page_69.txt
15038e403bdcac41b4f4e1cef12e2584
3b29c6273f91d4b1536d250c4601cb6a2cab066e
2083 F20110321_AAAAKO paranjpe_s_Page_72.txt
ad2172b4ffc0e400d898c1dcedda5906
ba5f710f5e433cb9fcc8b5931210f1584e284910
25271604 F20110321_AAAAFQ paranjpe_s_Page_08.tif
b5910050e8b2772883d6155505347da0
5dc6a4a55391e93aeed75974a4e36df20a6aeae9
787136 F20110321_AAAAUJ paranjpe_s_Page_67.jp2
a72a9223a8c6f8d149bb50031ccfcc1f
638e116fe0f32cd6ff1fd2594ab311f70326d415
1785 F20110321_AAAAPM paranjpe_s_Page_70.txt
b2a02d6bf968a0db72d3bb9b86cd5f02
6e297142a085d4d1191170736d8634ad23618d6b
F20110321_AAAAKP paranjpe_s_Page_42.tif
7866820226916189c97e4c6e858a8f19
a2ea9bf27f70236700c15b067d2426e8a483df54
F20110321_AAAAFR paranjpe_s_Page_67.tif
570ea0feeb2075adb514359e1a92f458
48dd04b85e7606ce93aa2384e7b98f32fcfcb631
55701 F20110321_AAAAUK paranjpe_s_Page_71.jp2
63ec0ad6a4e9ae073bab71a33fa2b9f2
57423bd528132943962db125a1df16a29bf2a850
1682 F20110321_AAAAPN paranjpe_s_Page_73.txt
e5ce88da4fcc2b072e38e08ab8edac76
30b0d3bd2f2d9bf35252382c52c7aebc09f36780
F20110321_AAAAKQ paranjpe_s_Page_62.tif
1871d72fbb3b26a22b9c80744d7b1b0e
92933bdda3cef7368cfdb68ae72990678cb001e2
F20110321_AAAAFS paranjpe_s_Page_31.tif
8e14b10c84733ba874b9397cd0307146
4095b3fa416e60a9ff1f4372e7f891e90d0c3209
107969 F20110321_AAAAUL paranjpe_s_Page_72.jp2
2b8cd7afabb2d3ddb63266a4105a9910
a9b412e34a2f8884c80da439abe62d85deaaccc3
1383 F20110321_AAAAPO paranjpe_s_Page_02.pro
d4916a348befb225d7d2f6410e1ee2a8
8afe97d3bf0693535ca82da8f6f421f725784d9f
F20110321_AAAAFT paranjpe_s_Page_24.tif
e07779d7b4d7905609193dc7f5e6fbb9
21778a6f3abe3355e1db77f6b5524a74774d5eb5
2378 F20110321_AAAAUM paranjpe_s_Page_01thm.jpg
0d2e94176d2718a5a948144a3c0033e5
4391eb33667291a37ed578ed4343eaf034088825
67377 F20110321_AAAAPP paranjpe_s_Page_04.pro
7bf3ac1e26f790722b3dc5ea94338ea7
f9031c88e38f6454a5e249e1455dfadb33470ca2
6630 F20110321_AAAAKR paranjpe_s_Page_58thm.jpg
e1ba5496ef68c922ce882dc4088e111c
f66e178cc331e36cfeae58ad7980d09032e5cdca
17679 F20110321_AAAAFU paranjpe_s_Page_65.QC.jpg
3a15f234fda69ce4d1b9dbb8b2de0bc7
3ea9b55eb894c2227da02ad8da0a58d1dbd324bc
1400 F20110321_AAAAUN paranjpe_s_Page_02thm.jpg
767cf4302f91077ed943bf35b5f42aa1
7dc785ed79f618fc44d117d2244a0420c5c5f399
15509 F20110321_AAAAPQ paranjpe_s_Page_12.pro
c8a873fb66ad17e08e21de46669e46d0
b0a1d0ed89dfed2e2a284ff426a404cc8d0d63b5
34683 F20110321_AAAAKS paranjpe_s_Page_24.pro
16af48509930ca13af491fff08f345eb
b31ed47e6952994149fd1e31f657e9b1d01a4b87
53664 F20110321_AAAAFV paranjpe_s_Page_25.jpg
3b7de2ed1a9f709932968bc67734fa31
a82337773943548b3a96ad8f0a6f9dc9bb608ecf
2159 F20110321_AAAAUO paranjpe_s_Page_03thm.jpg
8f387670891c8363772e2c4cae795ad7
17bc27563eae1c4cecd6321a2ee8cf2d7531f03a
45599 F20110321_AAAAPR paranjpe_s_Page_13.pro
fd4e8bfa124adeb5a760c7cc87d18c91
14c06502578e1f2df9fea0831ed084bbfcb525ba
49826 F20110321_AAAAKT paranjpe_s_Page_09.jp2
bcc45602efc8c303ea1b22f90dc577d9
b548db6c7209c1263ca2f2962ad30ca6f8b565ae
13344 F20110321_AAAAFW paranjpe_s_Page_36.pro
442bfede86ab9b7bdeb6e19cf51767ae
7a06fc77574c77ae98c50fb4b612da5b3d93d1fc
2850 F20110321_AAAAUP paranjpe_s_Page_06thm.jpg
8b5a76848adf65d1a3dd36fc55b1f8e0
9e0febb915a0e679299ed33647a31dd48a87a0ef
48011 F20110321_AAAAPS paranjpe_s_Page_14.pro
6d9412770a61ffb2968fffe68152e5c4
ca8640c4d1c28bfa31f134d7569b37e6efd05147
6778 F20110321_AAAAKU paranjpe_s_Page_15thm.jpg
42b4362712d85ff5be77001cc128caec
b3733b7a6f8a95eefc7839f8b7399f0fe0833599
18569 F20110321_AAAAFX paranjpe_s_Page_62.QC.jpg
aa7e53bb80d074dead6b53174241ebcc
79db234c42a3f75bc21ac8df70835570d04a98b5
5494 F20110321_AAAAUQ paranjpe_s_Page_07thm.jpg
6dbc27110ed77c55ddb5f991476c30e4
fd8835bc695331eb6866031b6f7280e2ba20afc7
54865 F20110321_AAAAPT paranjpe_s_Page_15.pro
d2fefcee68616da5ae4faa02d7151915
eab7b4006ce05c9a10dfe8e2f0580b1e5fff8d3d
23272 F20110321_AAAAKV paranjpe_s_Page_38.QC.jpg
9dc9b8a1cd292d5ce3c0380fcf174e93
c5998a94f926a8021beac219c301e7f989dbd249
10178 F20110321_AAAADA paranjpe_s_Page_06.QC.jpg
62799c7e08e0278b7a1f0823959673c9
a5c2f75a498ffc9cb8df47800d157aaa8c0468ad
1837 F20110321_AAAAFY paranjpe_s_Page_31.txt
61913802ecf951ebef9055def86a1d92
abd1f3885e0147fe076de2423e5306ee2593caac
5444 F20110321_AAAAUR paranjpe_s_Page_11thm.jpg
ef9af12af0b8991c2031dfc6d85993c7
ef4215cc2baeb91064bfa59710fae1602db2ef6d
10445 F20110321_AAAAPU paranjpe_s_Page_17.pro
50bef4865f521f31f367d55caa31cfdd
23468829f3d0310cd94f78cc390419d08e9a4bc0
21416 F20110321_AAAAKW paranjpe_s_Page_74.jp2
0cca68305bccb07d197ade6f43a52728
caa5132641e67572bd392b528e1d349de3cdffe0
58546 F20110321_AAAADB paranjpe_s_Page_62.jpg
ba223bad3ce213c3cce1bf2995fdae45
99e7265eef8067beb58c3d97f48fa33b66fb76f9
5956 F20110321_AAAAFZ paranjpe_s_Page_53thm.jpg
483ace7d9bcdfc6ab875991085345129
f40622bbf220775faa9f21e6a279e451e069f1a8
2899 F20110321_AAAAUS paranjpe_s_Page_12thm.jpg
998248622a87f5964d561e494bd53200
7b96475c6cb55672a6e5e21e1f50e01c1b01bb6c
48618 F20110321_AAAAPV paranjpe_s_Page_20.pro
36880093d72ccb26fd98f1b327121ee6
650d3f146cdde51a62f2d70b0b96295931c6ba81
2322 F20110321_AAAAKX paranjpe_s_Page_17thm.jpg
1d404120c534b25516a5870bb4351f7f
fe72f45b6d7efad6e0cea1ccaa2fb4bd6527ba5f
F20110321_AAAADC paranjpe_s_Page_26.tif
4acd6bc0f4b8cc0d9eb28fb029091d7a
b763f0b37f8c66c5a9eaf6482ad8983f6f31f196
6006 F20110321_AAAAUT paranjpe_s_Page_13thm.jpg
e528a4958fd6a6a0969b236591cebd1e
59d9d727bd34be8ed5bd7d8e9487c8d7a2b52f09
3733 F20110321_AAAAIA paranjpe_s_Page_37thm.jpg
d0d7a1018eb3acbc6603bc47ec0976c2
4b508af7b38b67050766110612b9b0fb3d8dc29d
1051985 F20110321_AAAAKY paranjpe_s_Page_08.jp2
9ad4f988922d3fb766d24fea4416671b
0edd084b3ca5bab9e9a60a32c7df2e25aec05fac
59242 F20110321_AAAADD paranjpe_s_Page_60.jpg
80a8d9be19742c484f206f0afacbdde5
9c02779f3677f65b74bdf994abad57dc6ec10a11
6353 F20110321_AAAAUU paranjpe_s_Page_14thm.jpg
b8e3d992943bee2ae5223c9757c4d912
9faf021c59b8d6c5535889c950011525113ac34a
33724 F20110321_AAAAPW paranjpe_s_Page_27.pro
8d5bd5462287723184e2f5de6afd7a0c
524a9b251c6d4a4d446ed89953a2f46c4798d65e
F20110321_AAAAIB paranjpe_s_Page_19.tif
496b8616aa4a4fc85ee57b185a693aff
005fc27594c6adbbcf49ab4ca13ec87404b8be51
42597 F20110321_AAAAKZ paranjpe_s_Page_46.pro
0a302ffa8b12a6c05a0134b2b51ed3f5
5f5dffd201dbd186a7bdf47d652afb509e6aaf9d
2033 F20110321_AAAADE paranjpe_s_Page_16.txt
4c2a34e369bd34a83fe224d28a524981
e00b78a172609685679f7a865658f2153e1c95be
5723 F20110321_AAAAUV paranjpe_s_Page_18thm.jpg
8b03b42e863998aee081d239e7fb5c23
762419b113f83bc90e5660876e65280391a27e4e
46460 F20110321_AAAAPX paranjpe_s_Page_29.pro
6670d66857253576c40b1d59d1eda92f
396cf6fd8cfdc81bbe71732788a0316ce8ef9afd
7804 F20110321_AAAAIC paranjpe_s_Page_01.pro
bcbb1929ad1ce9fac7b5f180c1bf76c9
acc79cc74154fe9b12f936b32d384412fc50cb6b
64574 F20110321_AAAADF paranjpe_s_Page_50.jpg
f6047714aa0c6f85d1b8e3270c516eb5
d8b3f8e8fd1809bb40be0dfb98808d746282b820
6559 F20110321_AAAAUW paranjpe_s_Page_19thm.jpg
1e1d968784c9c3bd656639b995975e52
a0531a3cc25c9f1162cca367750b9a9ebaafbd0e
5273 F20110321_AAAAID paranjpe_s_Page_65thm.jpg
04963d4d63892a4ebe5c4b106ae23fcc
45b829253bcdd3658e144d894907b2f8176b6095
2170 F20110321_AAAADG paranjpe_s_Page_58.txt
1cb54d2d1e2646531504ab46cdc464b4
02d670b254b5c7caa4a763132ee8b534476790c3
F20110321_AAAANA paranjpe_s_Page_09.tif
1891ae5412390b7befc955e59b526c1b
8704f803271925fa03a82e02cd4f7a802ebb253d
16373 F20110321_AAAAPY paranjpe_s_Page_33.pro
1bc1b173b3e13b9b5263ad74dbe340f5
fb8f26b0a3cd8f60416d34de52d18976c485f856
6442 F20110321_AAAAUX paranjpe_s_Page_20thm.jpg
1cf308d2cbc867a25922a1e7d1074dd8
bc0f49c54ad01528d281aadbfe6b577f73df6f98
91907 F20110321_AAAAIE paranjpe_s_Page_70.jp2
8053031cc9e312da8a1a69cfb031a675
797b3476d40c7303490e99d6aec67aa56804392b
53577 F20110321_AAAADH paranjpe_s_Page_58.pro
b376cdd416183ba6ca1adcf8850a14c5
bb87c1526d98201da772fa0fe53dfd65f5749b36
F20110321_AAAANB paranjpe_s_Page_11.tif
acc76a68a58f0d452085b28ea36ca6d7
9312a8ba9600bb83205388a72bdfba508877bdc1
12123 F20110321_AAAAPZ paranjpe_s_Page_37.pro
513330eed7a8189a091ed7eabb6e5180
d23859a01b300715304acd2b1e5b2d9fb26ca129
4957 F20110321_AAAAUY paranjpe_s_Page_23thm.jpg
dee8763e42049655b8868b31a9ca5a94
1f5525b680f41a4d017cff142ae31d00f48ee7f9
22313 F20110321_AAAAIF paranjpe_s_Page_49.pro
8e53f8b27d61787e0229be8bff3d8a68
c429cfb863ce7614ff62186c4176cdbff8fd8cc9
42688 F20110321_AAAADI paranjpe_s_Page_22.pro
7b85bdb452dee7543f1466e99136925a
8c526048c40bd7d2a12d8b766ff81efb159ced82
F20110321_AAAANC paranjpe_s_Page_12.tif
d860bf6ea7aa73291d4ee3e2c3f5fe58
660df34c46bf98016a6bd8736a2d9b64f4a478ab
5180 F20110321_AAAAUZ paranjpe_s_Page_25thm.jpg
e3fdced1cb8df062dcb39ecabbd4f967
22f01b6cce6dcbbb766b649004ba61f70af89df5
22138 F20110321_AAAASA paranjpe_s_Page_43.jpg
b6aab15450e7f68dd956d6ad27331915
79f88a79ae4c6b8bc26cc0f64a9cf57c8b8673ef
1738 F20110321_AAAAIG paranjpe_s_Page_11.txt
082c6786b92c6fe1e08b3032ba641c58
9f950341196aab119215f84affdce673a3578619
1122 F20110321_AAAADJ paranjpe_s_Page_61.txt
b0b902498c0a454db93a24cba727c5d5
5cf067bb7e4ae24e2b18867d2f6b85b87ad1068c
F20110321_AAAAND paranjpe_s_Page_13.tif
8ed1f5b4f73caa882720ed7ff5e2d5e7
77c96c53b4993ff59a1511a9906f541bd24b5d54
15692 F20110321_AAAASB paranjpe_s_Page_44.QC.jpg
03b2a7fe3c1717cae1e05f7034b89d28
e042ca0c2acc4091ea8480c3a0bb583c11873624
1386 F20110321_AAAAIH paranjpe_s_Page_65.txt
97b8cf322a2ff2165f3e026214f0a333
e475199fa0a70a98de095ee574dbe2f2dbc31bf9
F20110321_AAAANE paranjpe_s_Page_14.tif
ed1930fde69e06233ac60d0db21c91c2
023507cbf4973eaabcf86baf8776c2bb917c0e92
61130 F20110321_AAAASC paranjpe_s_Page_45.jpg
c07c0c7f5d8733c92fa1b4545381a83d
56330cef9eb2494a8bf6b1dc78c7523806e64a92
F20110321_AAAAII paranjpe_s_Page_20.tif
bac775be09b5e6d85e5d9ca4a69c33d7
0e3c0458dfc6cfa59b2a4bc409c96006d493c0de
1052 F20110321_AAAADK paranjpe_s_Page_71.txt
3b434deed2ac9c6173d234339cbf923e
19de4e6f3943d3fea4b40346f7e6cf643fe9b4bc
F20110321_AAAANF paranjpe_s_Page_15.tif
c13498ba4e677461ffdd3dfe40c3ac56
c93903f23733ee247270e25487f37deb68fd07a9
19267 F20110321_AAAASD paranjpe_s_Page_45.QC.jpg
9e275a98ce3f8e9db29a90e595683de6
a2b46a2ad1dcd7c6b94e6c4a70117f48fb4c4aaf
3397 F20110321_AAAAIJ paranjpe_s_Page_47thm.jpg
ae8f2d720f3081a5376c9c6c9314c649
cd24f04b091ba11b2e589285587a1cfe75a243cf
914217 F20110321_AAAADL paranjpe_s_Page_63.jp2
6a7906252b1aacc1e5952922cd8e5ecc
efb960b68e0f094e462477975987b3968c51e25a
F20110321_AAAANG paranjpe_s_Page_17.tif
03d9e9a3763d7d63878e68fecadb182d
3df411c892e2f9bf55a308eb60c5a08e8cf8d50c
32349 F20110321_AAAASE paranjpe_s_Page_47.jpg
a164383a4850ff6eb390e2c06014bc85
5298ad61021e437efdef90d96ae22977e9b08dce
20338 F20110321_AAAAIK paranjpe_s_Page_43.jp2
24bc9f0d664aa45c78203bf8170e7b54
aa180164fbb690ba42b061cb5c37158e2a5d7926
18955 F20110321_AAAADM paranjpe_s_Page_31.QC.jpg
9d2330758cc62f992bfdbb883edcd8e8
723158ed60b09e2b6d462644be2bcaebffb093b9
F20110321_AAAANH paranjpe_s_Page_18.tif
518573a07c4d789477354cf957a5a5f9
63122556ed35d3276832533b1675575894703900
10508 F20110321_AAAASF paranjpe_s_Page_47.QC.jpg
72c66fe602458589e6765623bbec6bd9
6a057f67debe6c9cb656ad6a7e901bd8e56f5d94
20547 F20110321_AAAAIL paranjpe_s_Page_64.pro
e27e6802c1604b7732a5c300f100a0f0
4d9812482dcc3eea223d7afd10e3f00f702f43e6
114251 F20110321_AAAADN paranjpe_s_Page_58.jp2
b7380f92f940e9292918b1f7378ad8e6
df5bea27f86da543ee774ef3d06ac271c2bff79b
F20110321_AAAANI paranjpe_s_Page_21.tif
11b8c158fd1fc82cdd850fe25c83f27a
6a59faaa2b6dafb0d1145714cb7216446f79336c
16028 F20110321_AAAASG paranjpe_s_Page_48.QC.jpg
a319ae6832ff9e94749532c21ac2b389
06981ff4eb114fc42465bf9a9de2484edff64fb8
66963 F20110321_AAAADO paranjpe_s_Page_05.jpg
1563aa3702b9177374aa935173c43fdf
a5deb9a926eda63b74f5d88e6bad2992ce04cf1e
F20110321_AAAANJ paranjpe_s_Page_22.tif
0dfd3c30cdad5b0d79cb0cccaca7b74c
2a31135cb0ec2fa039b3259bf846c39cf4f2e021
F20110321_AAAAIM paranjpe_s_Page_10.tif
0d51a2bf92e5d1e3d6a439eed22d5671
a5fccb93a3ff62094b23ffab81823e190c0c7a9b
21010 F20110321_AAAASH paranjpe_s_Page_50.QC.jpg
f8d461434e22e4dc573a2de022ae2f5e
28bee79791cfd8b308a36f708aa922e5859a2103
5764 F20110321_AAAADP paranjpe_s_Page_63thm.jpg
1234d4e48abafd062865448e3ea8ecf9
e00085911a16df6423c5707c38c3fe405c002f65
F20110321_AAAANK paranjpe_s_Page_23.tif
e36bcb3e014835ec4da2692abd825e71
8cbd03b7510b51c55c820bd35a58a9bcfdeec945
F20110321_AAAAIN paranjpe_s_Page_39.tif
1f4cb1a913c6987f3118c85a453dfb48
d99ee343a8d86a9263ffdd4676a42013c1489a72
57943 F20110321_AAAASI paranjpe_s_Page_51.jpg
ee324666cb89839364c11a76be534abf
6a81e6cb6f46967eff5d163f1ffa84514cc058a6
41451 F20110321_AAAADQ paranjpe_s_Page_69.jp2
89060cc05b2f5d0faf2021e9be447afe
6ec8ebd1e8677643d0043d0e12c1e8f45ca58845
F20110321_AAAANL paranjpe_s_Page_25.tif
5faa8942ccc2568462a4b40aabafe82b
bb40d70ceaf7d7b4c4cdbf39506960bfbc4126d9
F20110321_AAAAIO paranjpe_s_Page_70.tif
bef26086f9160b405225494a72e29e3f
1b61ee8ce0b19487c3fca3323eebda7d3a97466c
18817 F20110321_AAAASJ paranjpe_s_Page_51.QC.jpg
1c91782b939a8ca9c5426a908990a79a
f5b226d6d6d7758c8ef6e6c32945ff0e16a32687
12592 F20110321_AAAADR paranjpe_s_Page_71.QC.jpg
203137f65b907d98b6f47a55a625b023
267464f85cd740353fe7c70d1c069452147d4471
F20110321_AAAANM paranjpe_s_Page_28.tif
714620aa165597ecc3c4e55933c934b5
5ea772a6999f9d0df3cc0a4b0c40bdbfc930d480
15173 F20110321_AAAASK paranjpe_s_Page_52.QC.jpg
9642952b83aec10147b026fd250a6eb8
a4085cac814a50dddae38fef4acd96eeae9f9f21
1815 F20110321_AAAADS paranjpe_s_Page_22.txt
96fd800118604f78682dd3301f6335fe
361a5fee238ccced64a2b3a2cd3b18afd9e91741
F20110321_AAAANN paranjpe_s_Page_29.tif
28f736de0406ca9197a8383f7197359f
c090fb5247d9446433a30318c2fe477da144ee3a
1463 F20110321_AAAAIP paranjpe_s_Page_48.txt
467a7899ad8356b3dc1095e86e7bb9cb
274a130be991eebf3c73a64ee58658e5d6993402
61726 F20110321_AAAASL paranjpe_s_Page_54.jpg
8ce98f771ac34e5480559da3e0c6eb34
d18252f9838f16a5f77e5d05a8c06ca770ee5d59
105875 F20110321_AAAADT paranjpe_s_Page_20.jp2
359679fa48dca34fad5393eafd27ed1a
b480e5f168aa0e8e2988d53f6f868c654960de04
F20110321_AAAANO paranjpe_s_Page_30.tif
a7a93e980182459a084868301a63dc60
c5a976850ec5f540a0a1d8e626448662f8cbd3d8
6015 F20110321_AAAAIQ paranjpe_s_Page_03.QC.jpg
d03241fd304e15df6cd96f3d8b69ed45
d4f51418bb4d52d6e25d32783c1ca6b13daa9bfe
55102 F20110321_AAAASM paranjpe_s_Page_55.jpg
7140f82b1140e91172c90f923a613d9e
affc0ca085f6eb09fddec0c0f09a0a0dc9053931
20373 F20110321_AAAADU paranjpe_s_Page_53.QC.jpg
c01465e5704bd7943727d317206c264d
b5d84144608a3b777e4b29b4c3233bd99451e403
F20110321_AAAANP paranjpe_s_Page_33.tif
0e5351b306400ce77edfac4dad9feecc
62075f3a7776ef772b5cdf073062dfdd93b9f9c7
22668 F20110321_AAAAIR paranjpe_s_Page_01.jpg
e78e093ae0427add0c81ae469c5004fa
ac4228822b8389fe075821ae4719259f1a9887ae
18046 F20110321_AAAASN paranjpe_s_Page_55.QC.jpg
64f87fa1ec79d9b9e263250941dbe497
26a7141f17579db924ccf621729a398f9b28e7fe
F20110321_AAAADV paranjpe_s_Page_49.tif
2740fc1fba48a7c5e856ee8798c43a6e
293d1a771213444a80962a26e8f5c71c2ba0fe6b
F20110321_AAAANQ paranjpe_s_Page_35.tif
101cd506a25767e530d62917ae8a05fb
21f5c40ebff542da4844aad5bc656ec110523c09
781373 F20110321_AAAAIS paranjpe_s_Page_59.jp2
ae9c56c93a61ed309ffb58eaee27d20e
75df7f6bd5ad266ff7302ffb8295e4c14e111dd4
17137 F20110321_AAAASO paranjpe_s_Page_56.QC.jpg
9d463b91cd1ea8b5bfcd58b8d1ba4de2
1a3b361fac6d7b463a80a66e576a94cc60015bb2
32112 F20110321_AAAADW paranjpe_s_Page_62.pro
a19f347c2df47ee2b43923165e9809ac
3dc6b47749722f872879a81b2694af36de73f97b
F20110321_AAAANR paranjpe_s_Page_36.tif
5832d6d4c6f86a0440b9a7fc17f963f4
e9bf12f9c453588d639594754cef9c41f11d6f84
49260 F20110321_AAAAIT paranjpe_s_Page_26.pro
4800fda2a46f8b11562b3dbbe7283b1e
e54bc71481e015aec2c7069d16ffe3a19871712a
21566 F20110321_AAAASP paranjpe_s_Page_57.QC.jpg
d6c74674ed7ac9f32926db92b53ab525
104318c87179003082dba7e0c7ba55a752e22f59
43610 F20110321_AAAADX paranjpe_s_Page_18.pro
178b3175d0bb940a4d31883d388245d6
480cf1f3740263ece3e6371cfd3a45f09ca093ee
F20110321_AAAANS paranjpe_s_Page_38.tif
bf3021225901b56504698f2a32943c26
d5183924c82274485e4d7d767817c79541b08011
6016 F20110321_AAAAIU paranjpe_s_Page_57thm.jpg
10e956c51d9ea82dd9beab34fa0d1b11
64643164bb5ea23646b222bc31f4c64cd3c33629
58095 F20110321_AAAASQ paranjpe_s_Page_59.jpg
d6d029d80fd8d1ad29bc258da5d25c03
d4691e0e14cf661227de6bd59e8eba0339da7eb3
51591 F20110321_AAAADY paranjpe_s_Page_16.pro
c381beee8c25d4872554b9763b2a9fa9
e63378dab692c3b1e7825b8df623c0feef8c6ed2
F20110321_AAAANT paranjpe_s_Page_40.tif
6ec486946d9367f8ebbd8651b751aa13
891186dba5659baf1f218287dc1b6eef36bdebfa
6443 F20110321_AAAAIV paranjpe_s_Page_16thm.jpg
8e56eb865462f164e28683325537ac6f
42f7f61312d636534eacb26497e3c94a19891e5f
18985 F20110321_AAAASR paranjpe_s_Page_60.QC.jpg
87fc66400bd3f3936fc78eb629ea11e7
a0d319ecc1d88d3b28f12faf8b7336ccecc7d530
36515 F20110321_AAAADZ paranjpe_s_Page_09.jpg
36463f03f6c510e747656e6f3bf44cc8
929346d4acf1de6ff1e4d377ca4751044d659e8b
F20110321_AAAAIW paranjpe_s_Page_59.tif
e1ea606e0ab743e002bfbb12d8601b05
ef4848ddc66db2dd171eba07da9b01e1f6cd97ac
40756 F20110321_AAAASS paranjpe_s_Page_61.jpg
7dd2b3ee1c45913f93a193b88bd2380e
94dcdbfbca7ee604a80a7a82cc7d74dbebafeb03
F20110321_AAAANU paranjpe_s_Page_45.tif
c560b77cd9435fc84ac666721641b9fc
22c9507b40f8b1c472ee286dd4f5274234367a00
4971 F20110321_AAAAIX paranjpe_s_Page_24thm.jpg
750092588843776eb7a4e6ae0547b153
132ec9f8f0b5231682d340dcb3c74f7207539ff4
20166 F20110321_AAAAST paranjpe_s_Page_63.QC.jpg
603674091a306a6b4e9332c1361061d9
586c8d106cae0592d75893f8f89734616a7595a9
F20110321_AAAANV paranjpe_s_Page_46.tif
2413cee1c47e9618d8d37a4cffb4d115
f088de255afdbd93850975e2bcda8ade50214f6b
41562 F20110321_AAAAGA paranjpe_s_Page_53.pro
9efd8a046954699a5e5a67b993388319
ec27d4a36ecace7684f3f8e04e825d8f953ae6fd
16145 F20110321_AAAAIY paranjpe_s_Page_04.QC.jpg
6cd0c400b70f5a6fe6456ec8a0fdc5fe
5506d98b489397b79a3cda0d08f57e895a9b5f33
16343 F20110321_AAAASU paranjpe_s_Page_64.QC.jpg
fd826a4c0755c78c075cb631b8758e8e
73fa4c0bfdf765f27f65c642155dd7a9825ed223
F20110321_AAAANW paranjpe_s_Page_47.tif
3f53facde6e12f2b92e8155127ba1a49
cf44139f13354ce06216da2109d3ddcee3bfa874
97772 F20110321_AAAAGB paranjpe_s_Page_57.jp2
7d83b3b69d590cbe7d048f8339745812
6dc8532bbf70db533c1b09dbcbfc731e0926bd96
5089 F20110321_AAAAIZ paranjpe_s_Page_39thm.jpg
c64a3d667782ddd5e97fe0059d4ad8e9
6ba4915394798b5aed101e02b6d7a7cf18403575
57047 F20110321_AAAASV paranjpe_s_Page_65.jpg
fd80412750780441ad650ee0f70c3ed2
d5bfdbec6c0cd59fec00510c784a613a30aa5d2e
F20110321_AAAANX paranjpe_s_Page_48.tif
eaca7901583cd42a9ab6a008f486d743
30938bf1aff0e7ac1c034294a591d85e478c876b
6582 F20110321_AAAAGC paranjpe_s_Page_38thm.jpg
671d15fdfbe55a27a92b8ede730f5ba3
47ede5805ca0ad604db8cc5484fb0df6aed11a59
50761 F20110321_AAAASW paranjpe_s_Page_66.jpg
2cbe4f71a756cc3382878e53f54e3441
036db30acfc38ba0808bb78d64235c80653165c4
790512 F20110321_AAAALA paranjpe_s_Page_56.jp2
b0f490accb46351a7ecb1824e72d3af0
5de28596b52523ef2a6cdd065da108bc67d41ee3
F20110321_AAAANY paranjpe_s_Page_50.tif
1c14e06aa9e7538fc7f34406a221cb98
acf10541c155e6e37b16fa1ce553cf3f9c81e453
20314 F20110321_AAAAGD paranjpe_s_Page_21.QC.jpg
ba0939513aaa6ef4ee4824f5d4afd31d
da097c16d656a71121fad59b62573c7f9e9083cb
19595 F20110321_AAAASX paranjpe_s_Page_67.QC.jpg
c3967b4cc4ea3a3652348fa7f0e8ae2a
85be1e748bfd263dd53119b56837da0d7a493556
48383 F20110321_AAAALB paranjpe_s_Page_44.jpg
57b6a8e05679f287355ceac57cdda4a9
4f658c1b696cee4a84a0ed2b6e9361f1da707da4
F20110321_AAAANZ paranjpe_s_Page_51.tif
8b76cb348c062eb446d7bb74de42d8ae
2bda3cdbde683a5196681e4d587212f1002fa077
85802 F20110321_AAAAGE paranjpe_s_Page_30.jp2
64a6bdb3ded45fdc371747100dc3bcaf
e915af64782d3b31591d2909579b8659e40f7fc7
69434 F20110321_AAAASY paranjpe_s_Page_68.jpg
01eea420cf072009d5f4520c5678c7f4
a1502cb58777ee0f9ca3108950957333cb5bb995
53709 F20110321_AAAALC paranjpe_s_Page_56.jpg
fde868e6fab5612d7bc04143f2d35de2
25028dbb2789909284bebdb1178600f4983380ce
F20110321_AAAAGF paranjpe_s_Page_04.tif
68bcb16df5f592ebbe06a672bb049f3c
065fa3f8e76ae2feb686ec1414f561812799058f
66096 F20110321_AAAALD paranjpe_s_Page_41.jpg
766fa81b7f8c6b7ec48ad17375ab75a6
16070a02bbc2c270ab3731e2bc44abd453088c4f
488401 F20110321_AAAAGG paranjpe_s_Page_61.jp2
28e8011ae475fc10ac556c7ef3eacfb0
60c208aaf13deeb0acb9c6ed2a154dd7396ecb9d
28778 F20110321_AAAAQA paranjpe_s_Page_39.pro
e3f06f7b5dd5b0e1d7b035bbee040ed6
0f533a1ebef168104bcc8403599dd82bb72ee827
21959 F20110321_AAAASZ paranjpe_s_Page_68.QC.jpg
cb300ef5cc490324317b75f138516942
053289109a4fed18441bf01de0f412d7fabfc771
2104 F20110321_AAAALE paranjpe_s_Page_74thm.jpg
36e7e6ed70aafcfa699b7a28afd60121
e63817d87a22516295e4763c77f79e67be473fe9
19589 F20110321_AAAAGH paranjpe_s_Page_74.jpg
1fbb60b6707949b273267ff94a17b395
6bd94b3ea6ca25b23fe6bf76b8e2cb4c1e71af47
40852 F20110321_AAAAQB paranjpe_s_Page_41.pro
a63679bd42e1b64900a0516331942846
d29edd4fdcb58d7414bbd9b8e5b31595cc2d5662
903 F20110321_AAAALF paranjpe_s_Page_09.txt
f61f2e9f76c62f05b1b815345c173bf4
ed41575587eff22e53772e003e8e21c408763160
5757 F20110321_AAAAGI paranjpe_s_Page_62thm.jpg
38bdd04e1f033693498a8f078c4db350
009e17113eabde43cb8c5ab1ef3fcb3f671466fb
29567 F20110321_AAAAQC paranjpe_s_Page_44.pro
34c35a635e3c166c11ddd3a0115e8d19
dc8deb65a666b5753137b86ae806868bf6299a00
6396 F20110321_AAAAVA paranjpe_s_Page_26thm.jpg
e94a641ac240ed9a799b9195fffbceea
63659b3d35a723a05a38dcad9ee2eb96ea92a28f
1908 F20110321_AAAALG paranjpe_s_Page_14.txt
d2006c3356716408c04cde039e7d2fd0
29948818b307da73b591c955469550e392ef7c92
556863 F20110321_AAAAGJ paranjpe_s_Page_37.jp2
9e3f7c07055b2b0e8fd10ac9ed30b59a
e904d3ab962fdc2891252c07979243587ad6e144
40161 F20110321_AAAAQD paranjpe_s_Page_45.pro
35aa59aab941588e6ea1b4035502fcb1
60eb3c18a269712b7fb984c3cb498d7944a3e297
3943 F20110321_AAAAVB paranjpe_s_Page_33thm.jpg
20b17782000f29272efcf7d91c98eb07
c8176c246b7643ac5c09eab2f4eda9f85dae67e0
1888 F20110321_AAAALH paranjpe_s_Page_29.txt
c0664660d037b79bbae7cd6bfd86da63
761ea51fc0535b10fcce8d1e69d7e42c86a96dc5
16609 F20110321_AAAAGK paranjpe_s_Page_42.QC.jpg
fcc856db80d8cefd484f0a356ed56598
e03810a888f4ba2870345345b6cbaa1ba1aeebfb
33577 F20110321_AAAAQE paranjpe_s_Page_51.pro
acdb7b73d5f9d46ae2c81f7ab7cc78ad
4eb1a519a7b747bb502d8198cb104e39a61f365d
4369 F20110321_AAAAVC paranjpe_s_Page_34thm.jpg
53b585f6370f2ce13992f7aea5068cdb
9c9590cc60de515d7f1ac94ad1a9fbc83dea9244
6212 F20110321_AAAAGL paranjpe_s_Page_50thm.jpg
a7417f2c75a2281dde0cbdc5518379d2
4c1f6570065c503752a4fcf62ef708f36d7bc589
34473 F20110321_AAAAQF paranjpe_s_Page_56.pro
2cde9d651eb71545a8c0e82b7277f18a
d8f9e92f928a890765682e630514b1486b7acea3
4851 F20110321_AAAALI paranjpe_s_Page_48thm.jpg
19eaf34551abe21b3d9b422b917a069f
976f62b40c9a2313b9e98a71e8e0d05c19820ff2
6305 F20110321_AAAAVD paranjpe_s_Page_40thm.jpg
ec717cd51e7a0ab192760e5b32615afb
64d299c7c88320a60e748e961c47d2cbccdbdd57
17012 F20110321_AAAAGM paranjpe_s_Page_27.QC.jpg
a64806d304cc460e52c7e4c25de8c3e0
74502c6c5fdc2c0098d90e75f2c65bdbd8b98068
35218 F20110321_AAAAQG paranjpe_s_Page_59.pro
500340bba32f89c7ff43d0415f771aa8
76e65d68767edc9617135ed850f56fa4a6b3daa2
1877 F20110321_AAAALJ paranjpe_s_Page_13.txt
53a4553e161b85d5f55b61b3d461ed07
70037caaa5b1f82249424c75928dfdff59dc0bb1
5380 F20110321_AAAAVE paranjpe_s_Page_46thm.jpg
12b87378648d09d4745fe7e93181964a
938c27158508181f02f7880a17675eed80541439
33125 F20110321_AAAAQH paranjpe_s_Page_60.pro
e124b8d58db81a4233de1695e21a526c
836a02b8dcff29ac0b01de7e1c61c3ca2eb78da4
19171 F20110321_AAAABP paranjpe_s_Page_30.QC.jpg
7f1f1fe6322f8abdbdcda7830b83a8e2
839b21e8924aeaf076a1ec4a7c27906ae0daff7c
7124 F20110321_AAAALK paranjpe_s_Page_43.pro
3217474ff375d3f9633bc9bd0e65f4fe
bd1fbae934ef1a6e345c17551fea34ff8c458fc5
4484 F20110321_AAAAVF paranjpe_s_Page_49thm.jpg
3526c37298821e54746e0d91cf7d89e5
acaa1a352f9644c3983b674686d54406a2ec2ad8
18831 F20110321_AAAAGN paranjpe_s_Page_46.QC.jpg
21d48f846f7d73942bb688b9eb162e33
a7056d96184059ffe4d414aebffd3f0461c2bdfb
32559 F20110321_AAAAQI paranjpe_s_Page_63.pro
6836a179a50691b0a27481d62bd01f39
dbbb1c856700a296cfcf70c4c1a81970d233e078
5528 F20110321_AAAABQ paranjpe_s_Page_54thm.jpg
99107300f0e047ba71245d2984deba8d
f655aafc96ddc74506bdc6ae01831168a52d7c61
5763 F20110321_AAAALL paranjpe_s_Page_21thm.jpg
c3daf8d4bad1d6363c797a57a9750222
725efe058226700e6d039918948bc0c14d9a66fc
4499 F20110321_AAAAVG paranjpe_s_Page_52thm.jpg
ed811877ca37154feb215751129ca01d
5cbc24b7ea472e63c7f91ce39dbcf6c05a7bc516
13886 F20110321_AAAAGO paranjpe_s_Page_49.QC.jpg
6f603d01b3c7d7dad1893596299d1da8
c988d8a32c2093085379480de2e4110c6f0ecc66
29316 F20110321_AAAAQJ paranjpe_s_Page_65.pro
6180982a4489a2ec26d9201ec2925610
c63a1d72f0aa8b7f46f1c1f3be2662e08b0d4c71
18559 F20110321_AAAABR paranjpe_s_Page_69.pro
4426e76a5cfb8c85cbb6fabbe65be6b3
acad92c138374cb570d69a0faa2bb2e37ac9b607
F20110321_AAAALM paranjpe_s_Page_66.tif
dcc5a632c371ce69b1f9bc3d17411504
96e329bc07a132fa1192e2abb304a04939c87db6
5341 F20110321_AAAAVH paranjpe_s_Page_56thm.jpg
59e76e9c9dfd20ac69c9edf2868af97c
2ff39b94f2e8742f5cbd7d64413d73333fe5fdac
5799 F20110321_AAAAGP paranjpe_s_Page_45thm.jpg
8979512b4f9cf384b5a5924018d176b2
fb087420838a9dc32783e06b096e2028622004e9
44174 F20110321_AAAAQK paranjpe_s_Page_68.pro
28b12d6d39dd1c9e18bd8f7a46c5c7f9
bc5148c68a3467a3112fc3a36e9bf98be979499f
537 F20110321_AAAABS paranjpe_s_Page_36.txt
9bdc43927c598e80cf8b80379cdbbda7
7952572fc3472b9e5533e512ffeb14891f9ee600
2304 F20110321_AAAALN paranjpe_s_Page_28.txt
8f34cb9d421aebce4f56a06be966b0f0
45ddda21eeb195bf158bfb8b336f6d18e5831f03
5879 F20110321_AAAAVI paranjpe_s_Page_59thm.jpg
8d04361cb695efe325806209534990bb
81e1ec8014cf1b8e72c755d9603077a8b6ee2949
63304 F20110321_AAAAGQ paranjpe_s_Page_08.jpg
5a703d9e4c04dca8d733fc4d34759e20
21d38cf2c9ea21f0a39f59236c9e60a637e6b824
24955 F20110321_AAAAQL paranjpe_s_Page_71.pro
6bc30963ea784c8b1f4c0a177f1d2723
05ff5198fc3c3e8ff8bb5a9cb07ad1b4362b42d4
5355 F20110321_AAAABT paranjpe_s_Page_55thm.jpg
086112c1e3f0547bc93724e585efb02d
277944c895b5a7b5f851e14ac3d782bd77f2871a
76745 F20110321_AAAALO paranjpe_s_Page_42.jp2
97afaf6ff6d5967d355a25e044f754c1
71e5650322c835b0b209a01fc36ae0518951caba
5546 F20110321_AAAAVJ paranjpe_s_Page_60thm.jpg
d5711555da95b0de53807a4fb0af8f3c
76b40ebf39d70a1a5ff01026488ef7be37f1026c
968 F20110321_AAAAGR paranjpe_s_Page_49.txt
e47917eda1b50227297635039e23a27d
b4b9453cee15d641a54175df0ad21b4f78cfc6f1
50623 F20110321_AAAAQM paranjpe_s_Page_72.pro
d8db021e55971343678fffcdfebf94a5
f5a5e4e1e80c6ea79de3fcb8c57f66d0652a2c5f
5178 F20110321_AAAABU paranjpe_s_Page_66thm.jpg
5321b52fc332549151cba76a0ee28a8a
bf29042a5b390ba599307b6a20810a36821cad44
23584 F20110321_AAAALP paranjpe_s_Page_16.QC.jpg
a4ae97dac458d35d6d7f015a5f6b54df
28d097faac7cec3deaa2758bb8fa47a79ffad73d
4708 F20110321_AAAAVK paranjpe_s_Page_61thm.jpg
3139b68541df9634d27e37cf7a4f7627
21dfc82c439712800723cd30b2e287d8fb1c3905
1051968 F20110321_AAAAGS paranjpe_s_Page_07.jp2
d8829ceaa7168c69fd932c1694eb9c46
633e5abc78d6f11e14386317f4a52881dfd6e53c
8173 F20110321_AAAAQN paranjpe_s_Page_74.pro
31319b05e7ab0d23f9840e3c14e2e023
fe1f758ae8a0e74d133fd430d4ca859095d97e81
F20110321_AAAABV paranjpe_s_Page_43.tif
eb41b7bd0f4321ae05f686f5106867ab
3cae91ea01958d77e584ac755bb7c00ceb798304
F20110321_AAAALQ paranjpe_s_Page_27.tif
a41b6c0f9a466a83753518804ef7dfc4
da840925c01b1d31863339c6eae3639a98a6679a
5936 F20110321_AAAAVL paranjpe_s_Page_67thm.jpg
acaca944bd29e9794fac1b57f25b2ace
d4845ae9cf88103327380efe01cfa780d9084f07
F20110321_AAAAGT paranjpe_s_Page_73.tif
eab482d5a947ccce89f8d6638f8142d0
a549ff40037c7975ab5cb97f24b55b17cf59d801
7268 F20110321_AAAAQO paranjpe_s_Page_01.QC.jpg
4e01ca77c5dc5b96795cb4d4422386f4
96ca555dab36bee12b56dd69328ac710ffbe522d
23861 F20110321_AAAABW paranjpe_s_Page_58.QC.jpg
d30dd4e57390b77729095faa1a2af1bb
5a66ccd34000179f0b7b13d44442b2af91fa1aa8
2180 F20110321_AAAALR paranjpe_s_Page_57.txt
8f3d28c63f02cdb5603ad5b942c7d373
23a27fbff0e60bbe5a715e2107f25f14a1a80327
6597 F20110321_AAAAVM paranjpe_s_Page_68thm.jpg
8dab1bf34b1a2af548cce6bec45a1de4
18ea2282742f909ca5fc001f5bdc51c877f87798
974312 F20110321_AAAAGU paranjpe_s_Page_73.jp2
c93d7b1484ffb657ec736cb8089c98a2
5957b259ad657601a3e54af1db32c058cef41e89
3413 F20110321_AAAAQP paranjpe_s_Page_02.QC.jpg
626a16b1aeec38b599674e93f550b216
2458d9a1a62648f4bd3f8b2f984d60ba4b66598a
58067 F20110321_AAAABX paranjpe_s_Page_30.jpg
af1c0c4a419705318740da64502d9df3
81a5b11727604cf398293741e3e2b45daa1b14b2
3218 F20110321_AAAAVN paranjpe_s_Page_69thm.jpg
d4504a028c732ac44d39bc71681a8869
d7120571134335375b5b436d47cac66d6ab7691c
F20110321_AAAAGV paranjpe_s_Page_41.tif
6b239d120ad32a9a992cc6d051eae2ec
e745b9961ccc0d7773eed0e7b5b0b31ec1d29372
20767 F20110321_AAAAQQ paranjpe_s_Page_07.QC.jpg
c1f612cc0bc61f36370b955bd85143f5
5a76a96c21a99e20de6708ceb1b2447c65061f0d
6062 F20110321_AAAABY paranjpe_s_Page_32thm.jpg
e7313e7c99a3b8b244c9f210751dc059
ea582fb12e9dcd74fbfbf47be5601e38171c9ae9
22116 F20110321_AAAALS paranjpe_s_Page_26.QC.jpg
35c050bb5248de07d939e8efd9af158b
70fe3ca0cd59cf9d6795bf32defd2b43d2c588e6
5715 F20110321_AAAAVO paranjpe_s_Page_70thm.jpg
4c1bc39d675c9a6bf4888c07e43b03a6
3cc74d49a17b20687ebc3e5849e85b10f5d489af
837317 F20110321_AAAAGW paranjpe_s_Page_62.jp2
1379396fb00614b8bb2bc31038009978
2f04f4d1465ffbc4712a38013c5f658d5a8690ea
18201 F20110321_AAAAQR paranjpe_s_Page_08.QC.jpg
1a06cca534b4d10a669a7e6e195da0e5
46dc23a6b734f4bff7a770d51a5787f86b6ddb35
6526 F20110321_AAAABZ paranjpe_s_Page_28thm.jpg
dc6bfb4c77a8f386134115e56a1e03f9
b0db9f1cc3d9dcc659156a22846dc887cfd0c27c
10682 F20110321_AAAALT paranjpe_s_Page_02.jpg
9dedf7040c0900375437e177c43993e3
1d0556d2e609d0bb427e870ad8d5a488616a8a6d
5334 F20110321_AAAAVP paranjpe_s_Page_73thm.jpg
a6c4bb4c45075c2d12a9893683d89c8c
6c46da79927d001e425444e4ebd8af81be167f74
F20110321_AAAAGX paranjpe_s_Page_63.tif
19aa1b5a8daedb1839992de1cfec3586
4452183fd9b1c8579d989394bb42732807828379
11963 F20110321_AAAAQS paranjpe_s_Page_09.QC.jpg
9cf25ea957488d90b7bb7b4e801a7789
bc962c16e79348a1583ee9decc898ea18823b0f3
1616 F20110321_AAAALU paranjpe_s_Page_55.txt
6834f85ef85607e021ffb4ca3dc3b172
61f994fbed5424385e6b4696b788d2b92ed56e79
794743 F20110321_AAAAVQ paranjpe_s.pdf
47f34378f328295fadf1b6e1048ea069
96e09a2754598538d485284f3a15c3f0f82f8f52
2637 F20110321_AAAAGY paranjpe_s_Page_43thm.jpg
d7f2a10d3badae66e2db795457e65ddd
61b64cfeb8782db97e6bed0bd4da13d888942081
10373 F20110321_AAAAQT paranjpe_s_Page_10.QC.jpg
f7a7855d0fcb5d20a6556fa370268738
a8a19bc38f07afea9252a75168fccc37db56785f
4002 F20110321_AAAALV paranjpe_s_Page_71thm.jpg
bc108b1456bd3e314e3bbc8928c7a1e3
dbde0977a886181f8f003e421ba5d588dd754143
4953 F20110321_AAAAEA paranjpe_s_Page_08thm.jpg
31e189a768ad64bc495db78e031f4382
26235eecb7feb1bb4b1dba9c247204c807fe8f1c
87664 F20110321_AAAAVR UFE0008972_00001.mets FULL
4f8ee1796569394985e508e7cca2284e
9f4a609e6bde196a0ba03f270eeabac843530630
1961 F20110321_AAAAGZ paranjpe_s_Page_53.txt
9cca5445acdbf1de4eb33c1ca7dbbca9
6e103af46bb32dd88b3a2c37b03c2f99264135fa
59047 F20110321_AAAAQU paranjpe_s_Page_11.jpg
30c4c23df4110bdadde530b2dae1a415
dfada677bb67ea231f3fe5e7fe29578e55de656c
70246 F20110321_AAAALW paranjpe_s_Page_20.jpg
5b617acfeb0ea88d11dece31d64c090f
7192c23145bee516fedf131a081587ac57da295d
21737 F20110321_AAAAEB paranjpe_s_Page_34.pro
5d0c9771cbe0edee383dd6dd0cce09f9
3a0c61cf64e384843415102e4c9a5df2201172f9
19082 F20110321_AAAAQV paranjpe_s_Page_11.QC.jpg
49b783f9ee42f7bd131d4bf356bbb534
f17ea9fac4931e9f688bdc6ec577c2aef52ed138
62044 F20110321_AAAALX paranjpe_s_Page_21.jpg
3986cbf258f2497ab4d0354864feb2a5
94d1005768e84c79eac4f7056fb0bc18cdd0debc
1178 F20110321_AAAAEC paranjpe_s_Page_23.txt
ff67d0d2a40ae860bb1f56e2286fb609
6cba0419a3113b0f8ff405c71d10faeb6728ff59
27814 F20110321_AAAAQW paranjpe_s_Page_12.jpg
2a9cf4fefe0045e1111f48c6ac733d20
1a35f7945760c8e3ffbddff029f37aed90f248a7
45743 F20110321_AAAAJA paranjpe_s_Page_50.pro
bc7fd3da0b405d90ca022388cdc2819c
ba8c14ef91e621228b74ed33046b61d1d7c9fe74
2822 F20110321_AAAALY paranjpe_s_Page_04.txt
82bc2169fac96178026d5cf1b1c3562e
4c329bd094140bf19bd69cbf259264b84335b73a
21230 F20110321_AAAAED paranjpe_s_Page_17.jpg
dc8b219bb52cfeaeaffeb0b3e5ee99a0
64e9ed61f33f82cd436d6fff35b4e3d75abfc7b6
366 F20110321_AAAAJB paranjpe_s_Page_74.txt
6bffe56ef80c128d95cbc537c5d6c163
cb98de0a241ea998724be87e0638f996f31155eb
52321 F20110321_AAAALZ paranjpe_s_Page_19.pro
2831dc6ba38ffa9a623bd1b117ac08a5
89b50245c43f8b03846237f07b972b145a6d4098
100138 F20110321_AAAAEE paranjpe_s_Page_29.jp2
c12b6436b68d9d647b1142861574fa47
496174999167e41b621f943e75a6fd1d18ca05cd
9404 F20110321_AAAAQX paranjpe_s_Page_12.QC.jpg
26c7c7dd01eaadc6e8ca7fe914024b05
59cb38a1b64a0b0cf372c4bafa686318b2471845
62492 F20110321_AAAAJC paranjpe_s_Page_04.jpg
b8d2767e566be88afbdf70425b8c7495
4bce3ab4fb92a97e686b681a83c63115018b8aff
1951 F20110321_AAAAEF paranjpe_s_Page_40.txt
a7d4eb3761e9fb29d48b2e1ff86d9cde
d4e308134510b01e5434902af4ccf4c51c9fd5be
8423998 F20110321_AAAAOA paranjpe_s_Page_52.tif
da9d6023783deda390555a3b1bcbd5c3
d63fad6d3575a4778daf84b9512bbf6399d664e2
64847 F20110321_AAAAQY paranjpe_s_Page_13.jpg
29c602e93364e57a4f5edeec9eeae85a
dd0ff9e229d7c25736fcd2098781b0ed4832b5cd
111676 F20110321_AAAAJD paranjpe_s_Page_19.jp2
beb187f8fb2a422544e30f782ac44b71
21cb3a16c1611e18fff68d8cdc8fdab3bdc71028
69499 F20110321_AAAAEG paranjpe_s_Page_26.jpg
88b6de7e76f6d813c447b3ed8eb81354
4b2b8b31072e755e88eac9a170540fd4157b1984
F20110321_AAAAOB paranjpe_s_Page_55.tif
13bc57ff1754514e4673adfea0437aa7
59ffd0cab391083f4aab8d55e06575a31efd0bc8
21282 F20110321_AAAAQZ paranjpe_s_Page_13.QC.jpg
5a16ae671bc783b43c9d4e672791a995
15570d39b47ef4c493e5347dd34df2ebeccf2874
67370 F20110321_AAAAJE paranjpe_s_Page_05.pro
b0738fa00c2d940f4ab1fbb63fa399f8
da7ff6bb8e27960829a9bf5292cb15712d8c0a63
81520 F20110321_AAAAEH paranjpe_s_Page_46.jp2
87cd8e0d6c5d46790a980083c73f06d4
ed4754d9051ae99cb1135b904f3a0a1d6bbf69bc
F20110321_AAAAOC paranjpe_s_Page_57.tif
ba4727ba122727f09c45e94d0977be4d
57ca37384a4b9860746af38c8bdba819d3f56c96
61295 F20110321_AAAAJF paranjpe_s_Page_22.jpg
6962c9a394d4ca8ccf64b2bc8c4d5fc8
de9ef1b4265e05750cf9bdf6393b1f1d7214f4ec
21420 F20110321_AAAAEI paranjpe_s_Page_06.pro
49dcb8518c3d0efde2e4ae4236682abc
41daba58d77d4cecedc7c0f414deed88f0df8872
9937 F20110321_AAAATA paranjpe_s_Page_69.QC.jpg
5ef552168c11a6bd82a6708b77f98dd8
fe3266b0052720ecb12e3346ee039ff42067cc23
F20110321_AAAAOD paranjpe_s_Page_58.tif
b80f3c5c449e94d808e05a36fb93265a
eeb731da2399e8f765f5997301f5db50657f5508
66891 F20110321_AAAAJG paranjpe_s_Page_57.jpg
3cb02ca8ca20d2f1639775c94a086dd5
6af5c424f2bfa21b5a418253b3e51f4f7a30a397
69667 F20110321_AAAAEJ paranjpe_s_Page_07.jpg
295842f3c75dba0513b2fadc2e09d236
070e7a12dd361110ab130f5247034c72aa81e1d0
61429 F20110321_AAAATB paranjpe_s_Page_70.jpg
530c3f61d9d61ee3592235c101b6a290
f966e7f76082608eaa5208d2fc49ebc1352138ec
49624 F20110321_AAAAJH paranjpe_s_Page_48.jpg
e9f2125e8df5baae60538387d421ae48
be6fd8fce70cbe1e2f8b6a3cc22db80c8580d979
1902 F20110321_AAAAEK paranjpe_s_Page_35.txt
a55e33edb5e7987d92bb6ecfc236ea4c
310b59ae08fd7da566861f394f93a31b762d6c35
F20110321_AAAAOE paranjpe_s_Page_61.tif
6cf2f3db35f91265a835bf577a70e938
92bf7455ef11c281d8d4257a4a0a0c8388160d0c
39503 F20110321_AAAATC paranjpe_s_Page_71.jpg
13d00a23a005fb81abb3e69b9352ec07
81e9b4f5f34ade6f36613a162274bb586fbef916
859141 F20110321_AAAAJI paranjpe_s_Page_54.jp2
d18c10ad4a911789d35eabeebd4c6836
2ca0cfcddbaba1c29537d08fd9b62286c0536162
F20110321_AAAAOF paranjpe_s_Page_64.tif
9d4d51dad32cbbb69751bda1cdbad19e
e6f52052a17a7b1b4085b0d429b14898b1f179dc
69826 F20110321_AAAATD paranjpe_s_Page_72.jpg
ccc383e39a3fb0b20d8a7c3ca69f7957
d8ec9e44ffc6e6eae15e30e3ae84257b73afb4fe
75025 F20110321_AAAAJJ paranjpe_s_Page_58.jpg
32cbe598f6dafe6aa960eb03ee6d8bd6
37f05c973524971236db2c261a817af3379cc8f9
1912 F20110321_AAAAEL paranjpe_s_Page_68.txt
97d84db0816a29498ab2a4b76d34eca8
7611c4812586f78b2d70902e66d88cfc7e4eb055
F20110321_AAAAOG paranjpe_s_Page_65.tif
4008409c948ced7daf462aec17e1ef5a
dd8fe0dc8cfef97ac3be07a2264142db508e8b9c
21597 F20110321_AAAATE paranjpe_s_Page_72.QC.jpg
d51c92dc0e52af6ab01a5520ed65b9f7
d2e2f456c7fb1b74fcf5b99723b9fd9b7a53fbc5
17042 F20110321_AAAAJK paranjpe_s_Page_23.QC.jpg
cb82a575ce831242f2047586b8de7e5d
7c0781040f701d9580f5e3d08fa42948db14e945
62534 F20110321_AAAAEM paranjpe_s_Page_63.jpg
053497da0006d5414fd9c1a2d7d001d9
80e328faf487dd971cb09cdba0ccb050dd3c517a
F20110321_AAAAOH paranjpe_s_Page_69.tif
4b93df3beeec2ac38d46101a51d6fe9b
17dfe655e47d3e7d9c481319140f77660fb1531f
19168 F20110321_AAAATF paranjpe_s_Page_73.QC.jpg
68853cd43881015d68721aa965258f9d
1f0af1e354278fafe965e3eefa29a031ff03c638
23773 F20110321_AAAAJL paranjpe_s_Page_66.pro
2f1a1d26c986f6fc71a0a1302991cd5f
29b784b62ef6581d2c9e821c3c7838a79a75cb44
75970 F20110321_AAAAEN paranjpe_s_Page_15.jpg
9b5876dfd2620547985962b8c1f8a6a5
243e15d7c11776d38160dbd8b829715fb9d79f45
F20110321_AAAAOI paranjpe_s_Page_71.tif
25e7beb53150f072b5b28b9899e0b42c
0ee962f0a214ef4b992a7c99ebb792063466aae9
6390 F20110321_AAAATG paranjpe_s_Page_74.QC.jpg
7f9de6d375fb8c5e472e7fa1454b5ff5
150cf56864ce9f7ba26af38e327c95684cb31208
71926 F20110321_AAAAJM paranjpe_s_Page_38.jpg
273d6523bc6f44d98e2ae1eb9ceb0bbf
31a41e1c934db4b42ca1005b5e7f0416324b0705
F20110321_AAAAEO paranjpe_s_Page_54.tif
eb588e646a88a47ada910b1b67bc331d
4213b1ae792979cd8db111d7a4f698f6198e126d
F20110321_AAAAOJ paranjpe_s_Page_72.tif
aeba67551cf5848634f18d651b322cb9
5b041bb48458d4db017da7fc92747cf9b6d4803d
23464 F20110321_AAAATH paranjpe_s_Page_01.jp2
9f2ed21e522d38741a9b45a3abf4a7fa
5ab379f6be532fbf6c1e5bcefc35b7b386866e33
617 F20110321_AAAAJN paranjpe_s_Page_12.txt
cdd0ceab01f8d2204be0f0ce33f93a2c
9f93ff13a815817f8b5ad6de6655c27bf146e338
26312 F20110321_AAAAEP paranjpe_s_Page_52.pro
680021891215a4fe5cf5af96539e6def
7b467b20c3975bbbbd7fae9f269befa949a9a59f
354 F20110321_AAAAOK paranjpe_s_Page_03.txt
dd777e46cb59d07cb5d7d99abb605347
27d7b15a866d100df546cd2b1bba91dd84a2e991
19962 F20110321_AAAATI paranjpe_s_Page_03.jp2
04e0adac7f8f644f380f359cc4ba63d1
ace0f26710559d391050154dea9b1f6b5841684f
555724 F20110321_AAAAJO paranjpe_s_Page_36.jp2
4f57f71473437beeeff2d9ae452a8e64
987ba137d41e6a127a8ed67ecd7fc2d8eafe1c7d
453 F20110321_AAAAEQ paranjpe_s_Page_01.txt
65c8a6c43f2b195f75e656345f533e04
9aa69cefbf2690a85bbae62f3ae501a6b6b0f82c
2894 F20110321_AAAAOL paranjpe_s_Page_05.txt
2e0eba6885619b8c9f9f31b085add56c
65e1dd70fa5c6645a8b06cc291bba2107d3ca809
794207 F20110321_AAAATJ paranjpe_s_Page_06.jp2
50afa650c4c6b1ecc15846d01cf80914
32e65ebad7238f0ea43b91b4327dac014390db68
F20110321_AAAAJP paranjpe_s_Page_68.tif
8c10adc229b6b140ebf55d49f259c236
c6bf874bab52ded0c62d7e87947a9dce6828da3e
662072 F20110321_AAAAER paranjpe_s_Page_48.jp2
a0629c8418fdb14acbfc2aa446bbe29f
60b06439802fc081d1ade459b89cb7c5c31e39b3
919 F20110321_AAAAOM paranjpe_s_Page_06.txt
a8ffa5e5742766486935260b7943ccfe
1be70bddf1fd154619e6865a7635aa32eaaceddb
37548 F20110321_AAAATK paranjpe_s_Page_12.jp2
5d111e62fc8c5d9c30c6748ca9efd78d
6beb2f0772ad532d710f9358333cf0dc7b7318e8
7666 F20110321_AAAAES paranjpe_s_Page_43.QC.jpg
e5376b9a70d08752f5f64c7c753b1dcd
de292c365105a1069196f95a19ba79264d9b82f7
2188 F20110321_AAAAON paranjpe_s_Page_07.txt
656aa2a574cc9bc2eaeeef096bb1477c
277761d495749143af985bc42bd5843b3a1a9791
98886 F20110321_AAAATL paranjpe_s_Page_13.jp2
8a1091859fd484ef5dfe1ae9832ae372
cc8455da4f7b39f8b6d23886f8a35fb1a745cb6a
31898 F20110321_AAAAJQ paranjpe_s_Page_69.jpg
30e4b9fdfe754faf26f6b309a1fe445c
6c26adbd3e1cd9a1782c637167a10319ba432c54
1051981 F20110321_AAAAET paranjpe_s_Page_04.jp2
2a767aa298b172f1e39b254cc6ffc668
c66fb3f0d871eed28214473c3eba7eb923574d7b
1816 F20110321_AAAAOO paranjpe_s_Page_08.txt
cecc57003e2cbc8adca3a4cea2316ed3
b3728ff4f8c7ff6518eeb7e2716c384f396fd027
115599 F20110321_AAAATM paranjpe_s_Page_15.jp2
071158b493c66fa2f12aa540d8e0efd4
53fea7ae4d7c4a3fe1351d8030c411e639ea5b96
36075 F20110321_AAAAJR paranjpe_s_Page_54.pro
204f56dc122adbdc032372748336816c
438fdd891911ea11e89038d09feddf08d061cbda
F20110321_AAAAEU paranjpe_s_Page_56.tif
48030486c6c23a8e4bd655d4054e0f1d
cf9688f3e7d53a55ba60a6d0b44674afad20310b
1828 F20110321_AAAAOP paranjpe_s_Page_18.txt
0b6873102771d19646a12dc80d0237a3
e4b4ba773b6e163601ca5be531ebed9cca0b3abd
110437 F20110321_AAAATN paranjpe_s_Page_16.jp2
cd88f8be2bb6906f5644c73d09a270a9
0817bcd3d591a9787905ef01fd69c2a40ff7051a
866611 F20110321_AAAAJS paranjpe_s_Page_53.jp2
bb2a798c015a3f851e714ecd1ac858ec
67072971717ad2bae750515701149e1feba11f3c
21200 F20110321_AAAAEV paranjpe_s_Page_41.QC.jpg
ff36e05c4e25f6e9bf988fedac7bdc91
d4998b34d4011892ea3694115c1b785c19d1bb25
1914 F20110321_AAAAOQ paranjpe_s_Page_20.txt
297042a731d15b64c1b85ad03f33acd8
03e1bc816d3b73fe942b6f2c69d8d7b8082ef4dc
25469 F20110321_AAAATO paranjpe_s_Page_17.jp2
5e82ce2de0c3b92ecbaf6697fb3b61f2
d97dfcd3f377ca9498ef7a43ba78bbb9f2b1f4cc
44081 F20110321_AAAAJT paranjpe_s_Page_10.jp2
365e069266f8ce8b5ec126f70397d440
01f7d15ef9fd99be3476f6e1c7537e7bb59f4e2f
716358 F20110321_AAAAEW paranjpe_s_Page_23.jp2
a128d572dcea64b16b0ac8243fab2260
556ab2da5fa454f96bfb1d0c6d2662e30d5e8f54
1697 F20110321_AAAAOR paranjpe_s_Page_21.txt
06678ae4fd932f27b49d095d9d4f31b6
a95f562ec3c6dc08a4396bfac094233d6a4e6874
95358 F20110321_AAAATP paranjpe_s_Page_18.jp2
2eafaac162199aca7d733d115561bd15
4f5e4cce07ffe0f63166503bcb5f703048a3d6c8
800214 F20110321_AAAAJU paranjpe_s_Page_55.jp2
0db63e2489b0b020ac5d759f992b1988
2f313eeba7549502eae757238390a310ee3df381
19109 F20110321_AAAAEX paranjpe_s_Page_10.pro
a895f1b5a47dfc1ccaae5eef997fb540
b429da9c8d2cf1d625609a54935bd4d4cf4c70a3
1721 F20110321_AAAAOS paranjpe_s_Page_24.txt
8e80d755a883ed272ca45fb10973f2cb
4a2f862919beeaa1c4b6e9b9c88c85abacd43597
92902 F20110321_AAAATQ paranjpe_s_Page_21.jp2
a8baa13d40a4f83930c7299806d932c6
ba69915e6e58039f278216c7262c5aeeb2a093be
5155 F20110321_AAAAJV paranjpe_s_Page_27thm.jpg
8cbd73955338633947e54868a8e8f40b
693d342b0ccdb23c5075058ad690ab11f56a5ac2
424657 F20110321_AAAACA paranjpe_s_Page_47.jp2
fb74a3530a14a938251bc3ff383ecc6d
0c492b66789cd40803e4310029e5bd417e5e7f0c
2116 F20110321_AAAAEY paranjpe_s_Page_32.txt
6982656818be680d7a7dfa4179ea2fca
13a7271b00b890b7559e7d8f9d11b52434d5063b
1986 F20110321_AAAAOT paranjpe_s_Page_26.txt
1a2c5f4422f45751672abf0167345ee9
8f1e88482801ca588d21002eb93f5c6b1c9560a8
91533 F20110321_AAAATR paranjpe_s_Page_22.jp2
4c77386868c2ae854b6f7e263e552298
b2ed398f11748ba79adf247269503698bd114e48
50492 F20110321_AAAAJW paranjpe_s_Page_38.pro
4cdc8cb7324765842a722b2950bdb352
731780590dd0f8ada7637690f286ca3312502af9
F20110321_AAAACB paranjpe_s_Page_34.tif
1b08c4129ff1b9fb97b53c12593b2a71
bab2f9783fad87186298ea0f891cae6923ac43b5
F20110321_AAAAEZ paranjpe_s_Page_06.tif
231d9fc35c684e80eb6b675faa2719a6
6469e0164d7db8fe73f05798d8ee670152564f55
1906 F20110321_AAAAOU paranjpe_s_Page_30.txt
cca129bba3e52e803cd9b0190e2f1c46
27559f42ff9f48d621b4d8d392dfa65ee64cf65f
70157 F20110321_AAAATS paranjpe_s_Page_24.jp2
97e4ea9a9632b280c9445909fd71b74f
089fe91c4e9b0e2767522c6084cb83bdefb00008
47767 F20110321_AAAAJX paranjpe_s_Page_24.jpg
42727f04653af346f77c86ed61bbb7e3
8287db9bddbce896065424ae2e4a4fa24bcd5649
F20110321_AAAACC paranjpe_s_Page_44.tif
444b40dad6110ea51d2261d45f1cc048
e0a283be2051fdb273e4a635ffb350b80b255b11
80414 F20110321_AAAATT paranjpe_s_Page_25.jp2
881a1552d253ec05a69ddf0f1a463325
df5485e7f91029b49bb3257fa6ea9d10e191733c
32435 F20110321_AAAAJY paranjpe_s_Page_55.pro
09f6ea6cb8cd72f002a05012bce4c807
e250b76149fb0ab663f6f1a7e4a595abf619824b
20101 F20110321_AAAACD paranjpe_s_Page_70.QC.jpg
a466a2d4379c60fb42078dce70bccd3c
f6931d8d93a70cb358dcf7c870cad0d60fd0462f
724 F20110321_AAAAOV paranjpe_s_Page_33.txt
fac4c7f51fa8c016a8aa1fdec8348a15
637ee4a578f4c4d886017e556d0685b87fa6f9fb
457 F20110321_AAAAHA paranjpe_s_Page_17.txt
38bcef5fbb9ba42e676a326638d4b3e9
bd03170d343761bdeb5fab31eb42485e48778751
797892 F20110321_AAAATU paranjpe_s_Page_27.jp2
3dc406d16e356d7e6e2840026c50e13b
1b186d8f21787f18a846f8fb0483bfe55a926975
66399 F20110321_AAAAJZ paranjpe_s_Page_44.jp2
f6be81d16a70a686c9b7983f385b7153
1f50071ce459c17ad51ad3b2f8886e970f7c39f3
54441 F20110321_AAAACE paranjpe_s_Page_07.pro
ab6ff0ec92d4e8d84520f84f3f48d327
14013fc4c1be20658288fd740be508dfca5c859e
996 F20110321_AAAAOW paranjpe_s_Page_34.txt
ca5200c828dbb9faaa979e5ad8f642de
cb58de96363ff48f1293f8c71b3fef841fbc890b
F20110321_AAAAHB paranjpe_s_Page_37.tif
dd7b4490cf6596c484906e9900a085c2
a8144b94e1bdcadc1cbfaac9916e8ec671a4d155
86253 F20110321_AAAATV paranjpe_s_Page_31.jp2
5b114f2a33b3297994c44b618e4e44ff
1c72ee24a1e9e7c6d3a396fbadcd1dd9ba6e03db
5526 F20110321_AAAACF paranjpe_s_Page_31thm.jpg
f7fab40f6d3eacf8f349ac63b47d2f43
8efbd44ea40b6028746f65f6e9c7c07b67477bcf
497 F20110321_AAAAOX paranjpe_s_Page_37.txt
cfb356258efcda2b4e768d28d9bec208
8e740beddafd5f5369fb2d0b53ef9a63c4e988f0
7011 F20110321_AAAAHC paranjpe_s_Page_17.QC.jpg
480cc7719e648986991eca5b415f844b
69ecc0bced8e336ab1692b2df2df06ce3bd91460
597497 F20110321_AAAATW paranjpe_s_Page_33.jp2
1f5a609b1b3f5a4677897d89f9539afa
3fd7c5e853ee7157b20e866cadb6c5d310929449
F20110321_AAAACG paranjpe_s_Page_01.tif
a537181647d25180291bcc8fb72adfb1
25fe8d66bacd77d25904d283bc531ed2275b4a74
1673 F20110321_AAAAMA paranjpe_s_Page_59.txt
9e12245f57244496cee26774a222d944
ac08ac1dd1cd12562762676e4145ec736f3a3bfc
1990 F20110321_AAAAOY paranjpe_s_Page_38.txt
a7e9de6554882a38b5c45513bc117434
528491932ed83b62b7ddf8800d4c8ed788001175
F20110321_AAAAHD paranjpe_s_Page_60.tif
9487f7c2f459408bd0053fad54f0170d
5c202184dbf47751657e735e48eb74cb356d0cbb
97627 F20110321_AAAATX paranjpe_s_Page_35.jp2
7d50ee1af884adbbe77a988351b266de
4f64663c3085781ff08d73b762592ea620b64918
7627 F20110321_AAAACH paranjpe_s_Page_03.pro
a6fc69a7fc37dbb952d752ed5cacf0d8
8eb78b543266335f4b8a75b89fcc0a8a229b9bd2
103659 F20110321_AAAAMB paranjpe_s_Page_40.jp2
f9257fd00ddad8f3f9979b7c997c0dc9
edab91a31e63eea60af8fd8f33e2b7c5adb85378
1706 F20110321_AAAAOZ paranjpe_s_Page_41.txt
d1e95198701e66cba6c4e618fecbda72
586b5ea665cbf1cacafd2f56e0cdb05d9d0a31b6
5539 F20110321_AAAAHE paranjpe_s_Page_51thm.jpg
217fd6dcdb72643676af1dd8e74e2fcb
a6d0147efd17cd0e7370cc647f551c9c942a3c75
108273 F20110321_AAAATY paranjpe_s_Page_38.jp2
775f498977d3c6764439c2412e7f58b1
f8e9e0bd4a2ef6f8be82b2543233027dedb1f181
16702 F20110321_AAAACI paranjpe_s_Page_66.QC.jpg
823705439ae91b687858a670efc96d5a
f7acf94ebd6e4de3347209538502e08f4f77addd
37054 F20110321_AAAAMC paranjpe_s_Page_37.jpg
8817cb1213b5f60c0cbae2cb59ac8c6a
2ec4cdcbc5481b546676739b3d7d01c562d1a95c
45754 F20110321_AAAAHF paranjpe_s_Page_35.pro
8df2be3f0168bae0f2775385a041e2ca
0237979cfd9869809780977627911ffb010689a2
65887 F20110321_AAAATZ paranjpe_s_Page_39.jp2
00a17157b28900cb7635912d64b74bd9
6881bd5c1fe9c98f75ff38c838efbac60ff377db
45835 F20110321_AAAAMD paranjpe_s_Page_08.pro
233b519bb515dfd3d020a5132223fd03
825c1fa283e9b22aafa7655085e48fe022f7e877
66599 F20110321_AAAAHG paranjpe_s_Page_35.jpg
af9115442046d5f62af7db78ab695c0f
635582d3e91b95cf6df354356ef836169c3730b5
69006 F20110321_AAAARA paranjpe_s_Page_14.jpg
01a494440bb35223d8ea1036eadbd553
4cb0cd55fcdbd52eb0e6d64c89daa4388b318ec4
21882 F20110321_AAAARB paranjpe_s_Page_14.QC.jpg
3ed509ebb1d7e125f284c661f0a0de55
842f143020a020d370b5eeb65df08da7ba393c67
19197 F20110321_AAAACJ paranjpe_s_Page_03.jpg
8a9e0e2686f01db7cbd7f91ebfe9e9df
757631e5bbb6267d549876adeb57d0262d3b27a5
55420 F20110321_AAAAME paranjpe_s_Page_28.pro
161317e5406df0c65915c86500668d4a
78be0c5386c11932da0d29a0f35202bd4474c5a5
3735 F20110321_AAAAHH paranjpe_s_Page_09thm.jpg
24ea7015025aebde6b9ff1234c9ad5f8
77557bf0dc8369b4176d4e490d88893f92e88afa
72599 F20110321_AAAARC paranjpe_s_Page_16.jpg
3ab3cdd3c30fc08825840532b35848d3
b36cad22a9ab6b5e13e6395c29c9995db0e15dc0
70104 F20110321_AAAACK paranjpe_s_Page_40.jpg
5427d643802bb792eb71fc2e3bc00395
3fd62976974aa7e3b8cf7d32cf8dadf27c2fb727
48769 F20110321_AAAAMF paranjpe_s_Page_64.jpg
d68901b7eeae6e3f5844731d507f82c4
db6775c4b013e1f8bf8f8f5057a6a4fdc2b9abb9
41204 F20110321_AAAAHI paranjpe_s_Page_73.pro
3240020cb65b6f758dff573b0ac4b498
6e4216e719c391763eec8325ac51ec69520d2505
65006 F20110321_AAAARD paranjpe_s_Page_18.jpg
e481bb3de482d1350b94dc1976ebe18f
4b90ed8b91a45c0004d6c535f3e81478eaaebe68
42275 F20110321_AAAACL paranjpe_s_Page_31.pro
5ff08e9fffb6e2992b530f253f4bd03e
0c2a7cd78660866e2fd3015a464a77432fb7ee9b
47498 F20110321_AAAAMG paranjpe_s_Page_57.pro
65f57e5b70608298176ceba94bb17216
0e92f7f36f193390e225f7ecc56e77c7fbad0c80
F20110321_AAAAHJ paranjpe_s_Page_53.tif
05eb951fc701d96e24d7848ffeb7428b
e271d010cf5dd4f7d1ce7e17988d11eea1035fb3
20672 F20110321_AAAARE paranjpe_s_Page_18.QC.jpg
46e85b446c466792a8a2d7232faaf2a4
32ca119010042ef788291d181fcd610f72a8b456
88251 F20110321_AAAACM paranjpe_s_Page_11.jp2
bd1a27c869a819d8560f058e56c85fd1
374451f17f4e5f635f5b63dacc7703d9de3e9c1d
6291 F20110321_AAAAMH paranjpe_s_Page_02.jp2
ff25e97fb86de3a48b0810e4ad26bc8e
9ad95d7ddae8388e7f3b6bc894903fd438b2d02f
19445 F20110321_AAAAHK paranjpe_s_Page_54.QC.jpg
4c0e061f445ad2c1ccf4cd41db1d7651
b884d3ee6c7a41299671925b26693e733b16ed31
74056 F20110321_AAAARF paranjpe_s_Page_19.jpg
31f84b324e51195d479944ab2a4ce17c
db206336fa3103b10e7e47e82d47df9ebe8fd749
61321 F20110321_AAAACN paranjpe_s_Page_67.jpg
df60cafcd7c50e1aed433f2ff21413ac
cf358516a1913bc7185da650d3b93f7e80ad0522
21284 F20110321_AAAAMI paranjpe_s_Page_29.QC.jpg
78631ed7566a682a72ced5f629c40bea
77123d218d4945472f48e5a29f3d0bd4c9a65f2d
38484 F20110321_AAAAHL paranjpe_s_Page_25.pro
a3b44a231a9e962edf044bfd5c8cf287
5738d6f8080dbcd079db01b24a0f63aa3e812f89
24288 F20110321_AAAARG paranjpe_s_Page_19.QC.jpg
deedf384b3e4faab379218cfcb846d06
ba296cd69f69d64755c3326e96cfba2e01af0436
564904 F20110321_AAAACO paranjpe_s_Page_34.jp2
c1c947bc15833a0d21a0ea756a61640e
ab5eb1dec71e3815d3210d069ed800e691af28cc
6213 F20110321_AAAAMJ paranjpe_s_Page_29thm.jpg
827ccfc722200ea9b8f81fd0c5e07d0e
dd8c159d7cd26142284ef2e8e2ff020ab51b5704
14100 F20110321_AAAAHM paranjpe_s_Page_47.pro
bacc0f88aa981dd9e2f34533bd61b35b
956769aeba384a94f2ae1d6d542cb017040e5215
22680 F20110321_AAAARH paranjpe_s_Page_20.QC.jpg
82d13b17e320f234e1068a23098621c7
55df29612c8ef50a84c93eb064838aee559e936f
1349 F20110321_AAAACP paranjpe_s_Page_52.txt
d6eb83509b30f5ca38b8e60000eff8fd
3a24a243e3ac81cfd6d69624bb57ca1d86fbe9db
18656 F20110321_AAAAMK paranjpe_s_Page_59.QC.jpg
547b2225e59ded92da75b5503a0f4f7a
fde7c52675aa1342858cc373b9a457147e9d2d8b
12595 F20110321_AAAAHN paranjpe_s_Page_36.QC.jpg
078adf29dcd41441f5aa461b5e3a430d
4bee16c7ea57991e66b0651fb29c45d1cfc35481
15826 F20110321_AAAARI paranjpe_s_Page_24.QC.jpg
12dac92a393afba25796c4c2e6969365
5e3281769a3db5a1a44dee1d8d9d38844af11b5f
20042 F20110321_AAAACQ paranjpe_s_Page_22.QC.jpg
b7be3748a583e1aaaf4f83115499f00d
d22bf2a6819f3a70ff46a73fe0cf520d2aaa3e75
4263 F20110321_AAAAML paranjpe_s_Page_04thm.jpg
f524d0a59a3328cafe430d2b1dfa8eb0
53e935255dbe996bc282d85817c4bbe3789fe7ab
17395 F20110321_AAAARJ paranjpe_s_Page_25.QC.jpg
2db3aa44a3407843478305d6d4b15b33
a91208fbde9cde6f2b3ef658c8ad87f6caa31c1c
24866 F20110321_AAAACR paranjpe_s_Page_15.QC.jpg
d5380ef5f5e805363f564a5c9607d337
4cc36891c271ec96c6f36214aba9427f0d1fb9b7
30313 F20110321_AAAAMM paranjpe_s_Page_48.pro
e8fa0cadb1864801b652aec50bb5437b
db5ba2afa0dc0b8bc5c549ac92dab0034c21e1c7
2088 F20110321_AAAAHO paranjpe_s_Page_19.txt
a584db9029617ce5b404b3587fd68e21
8317aca8af3c8f35fef42c8824d772a1f5ecd0a6
56789 F20110321_AAAARK paranjpe_s_Page_27.jpg
825c6e63cfa0d49f6930b741ed96d06e
ea8819662e2f32da2c2cf59109c3776d7d4fc0ef
4325 F20110321_AAAACS paranjpe_s_Page_05thm.jpg
8ec11151261aee0c07f67ecc41b06d02
6d45f69477b2a22486e9cd770597434887f046bf
1666 F20110321_AAAAMN paranjpe_s_Page_54.txt
480507be6b6ab2e5cd8e998f28ff60aa
9f09221e5a46645fdf1a05d3cd6f2956c164056a
5934 F20110321_AAAAHP paranjpe_s_Page_41thm.jpg
aa5d8a3932253e14911dcab2298514fc
ddbfae22685a54cbd095a1a14a24336e465c296b
77181 F20110321_AAAARL paranjpe_s_Page_28.jpg
a232d4546538f4f9d0131277663e3abf
543a29c70aabbf136477f6ff6f64569428b65a18
6048 F20110321_AAAAMO paranjpe_s_Page_72thm.jpg
82d9e00b9ef6a1ce81ed8249ce2b3d86
6b41b4fe8fdf1a0dddb805cfc06f28ce5fcc5eba
16755 F20110321_AAAAHQ paranjpe_s_Page_05.QC.jpg
863dc23293ecdde86f502cee7e37ed10
ee5789762b2601a3ad9f7ca4a03117db8783f4c7
41725 F20110321_AAAACT paranjpe_s_Page_21.pro
414cc6dc42ba7708f7325c37f13025b4
0c66c0063d8ead5fe09e30933dc6934fe661b34c
24070 F20110321_AAAARM paranjpe_s_Page_28.QC.jpg
9fe261b47c3ea466ff5d37471f6e9213
d8cc1865a0becb50891af9b9b288555a5b120977
42892 F20110321_AAAAMP paranjpe_s_Page_70.pro
ae7d9241cc4132518c0fdaf2b2d61c41
bbbcd330a8d5cdd62e7bcb8b999274f456a808d4
39297 F20110321_AAAAHR paranjpe_s_Page_11.pro
ef9d2b392c82a1fb1fa188f8539a1598
54f3e58bd9f6b7966f937e8bf920bb89bd131f27
49125 F20110321_AAAACU paranjpe_s_Page_40.pro
392ce372710a720a0b34fa9ec2d6d307
a47c2609ce20f5894a8da1251341230e2a8fbf78
66102 F20110321_AAAARN paranjpe_s_Page_29.jpg
18433b5d8af98418a02f2ffdd40d2051
efbd3edb846e64df6bc15b7a3636f5047e1ca9e2
5113 F20110321_AAAAMQ paranjpe_s_Page_64thm.jpg
c6380d6411d787fa4473347b7184e1af
c4a0f8ed500deac984bf8747638b7402daaa004b
F20110321_AAAAHS paranjpe_s_Page_16.tif
597ee82f1855fd580fb5df295f608905
f5f03f3b1f64a0bb0ed03d950fbdcfbee3f78d82
33155 F20110321_AAAACV paranjpe_s_Page_06.jpg
380d31286c7fb5f383c298efe7a18cdf
dd19cda3abd068cd219357d2326e79e7a8b4dd2f
58687 F20110321_AAAARO paranjpe_s_Page_31.jpg
7f1eec1c6feb22afa64d690d3eab0ee0
107c86cc00430092f9246002a4fcb146e99c96da
48207 F20110321_AAAAMR paranjpe_s_Page_52.jpg
4e2fc2c1f961663c02ed14b323712fba
b8e1dfbcf8f9a5c5767e153d23d88ad8a464cf9b
3401 F20110321_AAAAHT paranjpe_s_Page_10thm.jpg
d9b681842df594c190e4b62edef33904
000a48a04ae78e747b177e2bebad4f6910d817f8
104597 F20110321_AAAACW paranjpe_s_Page_14.jp2
1f3ef75677629b1d6df9ec20821cef48
efa68f8649d697ec5d4ada119d9394bd8de6d7ab
20370 F20110321_AAAARP paranjpe_s_Page_32.QC.jpg
0507c5fa32d7de01134412b8bab9864e
2d0b649b0ef4660b3d45f83b69528f5833df782f
95855 F20110321_AAAAMS paranjpe_s_Page_32.jp2
be0802012af3dfbb1b6adc9d7b2303da
019da3ad46a776d785fdd3099d75781154090973
1780 F20110321_AAAAHU paranjpe_s_Page_25.txt
1517f07ae6b5a97ff838be1ccca69bcb
ddcf0f6806fbbb76a89387255884816ebfcefba8
F20110321_AAAACX paranjpe_s_Page_03.tif
cb27148b4145ddc79a69d48154aa1a05
31678c6a6ae914e6cde92ba336cc3d2cfa2aabe4
12483 F20110321_AAAARQ paranjpe_s_Page_33.QC.jpg
08beee66acd9420f4eb66a308064d4d5
598a716427d9dcf1c37d3ae1f182c6614ece238e
126 F20110321_AAAAHV paranjpe_s_Page_02.txt
53a11415a41746fc0aa0715783beb201
84eeb8873bc90a6e8d06e3f945190682319ce585
2173 F20110321_AAAACY paranjpe_s_Page_15.txt
81dbc931b04306f7d8def207f1ecb11c
b4ee8a6c3bc0288d5df133eac731fdaf2a8001ac
42403 F20110321_AAAARR paranjpe_s_Page_34.jpg
443a7c07db070a7a42c3650a86af4308
0211e7ac9e3480e71404a4ac91fc58c9c09faca7
1286 F20110321_AAAAMT paranjpe_s_Page_39.txt
fee09f29b408fbc5852c89fb407d971f
56a83ca9ebd724fca05646aed3a24ac43b46a775
F20110321_AAAAHW paranjpe_s_Page_32.tif
dd9766234a599134a28ebc6ea8ac804a
af166087ee12ff16cd7ef8321ef5902279aca602
863 F20110321_AAAACZ paranjpe_s_Page_47.txt
ea882fa37307722c4dfa1a347405b07a
42a26a10fe98363da980741dd213ccfb39647f9f
13984 F20110321_AAAARS paranjpe_s_Page_34.QC.jpg
bbf9aa5e6148c04dcdbbc0c6f8a72de8
0ecc492180853931b551801af5e8c05bb17d286b
121662 F20110321_AAAAMU UFE0008972_00001.xml
5d9e7c6762cee8dc9a32e35d9b825f0d
3265eee001765ed4a3374aeeff7a299e32a69af2
115412 F20110321_AAAAHX paranjpe_s_Page_28.jp2
99fde0c44c50fcea7b2cb845dad8f84c
d59a1d73af8d638e60bc4696afbe3b51952e7f78
21360 F20110321_AAAART paranjpe_s_Page_35.QC.jpg
85c33643cb6c30c891285b43f992a843
09923b8296d83be4b7e2301da88a21a6ee5c71e4
34265 F20110321_AAAAFA paranjpe_s_Page_42.pro
56a0e9f8ccf61c4b0fa872b400daed77
8193818030374c89395e538c1301155741c6bd7a
5014 F20110321_AAAAHY paranjpe_s_Page_42thm.jpg
cc78c542236edea4fe566ec9d33e9856
f30844583e19388030946666194852a45a560f51
39239 F20110321_AAAARU paranjpe_s_Page_36.jpg
fa8b214c5d36a4b6e1a8da0adf337ffa
4dfd6b6cfe8a2f14b25bf11975c43dfed7b98875
18602 F20110321_AAAAFB paranjpe_s_Page_61.pro
843a272b7488d1a12f490b1029e81ff9
56b3d84c2815a35f396124bc0183d80ae172a6d5
3870 F20110321_AAAAHZ paranjpe_s_Page_36thm.jpg
47c7ad857c7c61af846b0252ce3318f3
dd4e7d16bc5835dea1af65f2f1e6fa35a60a18b5
12344 F20110321_AAAARV paranjpe_s_Page_37.QC.jpg
388997928cd35491241ae7e8b5470275
3d4ed875239751e670ec3517e7a4b6e0a350175d
F20110321_AAAAMX paranjpe_s_Page_02.tif
6266ecd94d0d841a4377fbe51a2389dc
890da1e39c861adb5e5abb8a8fe514c0a7eca252
65396 F20110321_AAAAFC paranjpe_s_Page_32.jpg
0296ccfea7c58cc4f8f30ad39374dfa2
25c88f9e0996455e2f763c041754f963f6d90464
50422 F20110321_AAAARW paranjpe_s_Page_39.jpg
ac59589855abcbfb5194fef24eb4f74d
c8a57b487eab119a8c7fedfc4c16addda6654d15
F20110321_AAAAMY paranjpe_s_Page_05.tif
af9af374d8a3617f586b94e16ae66efa
ca9b3ae0c4509f305a092291e5dbaf3bde59d57b
1084 F20110321_AAAAFD paranjpe_s_Page_64.txt
ef1f07b1e2a37f7ae1fb875842c9fdc4
7ba140f8f01597dc11be82a98e2154332a8aaf7a
1763 F20110321_AAAAKA paranjpe_s_Page_27.txt
209c92fe2e10b10ebd108fc8ceff71f0
6335d6afb6c27b8c830903053a0ffc3d5587a9c5
16685 F20110321_AAAARX paranjpe_s_Page_39.QC.jpg
3d4409ba59f8d28d8552592d49ea29d2
508f6da118dc64c31bdaed00e6d4ecd5bc306657
F20110321_AAAAMZ paranjpe_s_Page_07.tif
bed1d019ccd5e72b245cc8f0d6a465b5
418d5ccac65fd81beb563d5b1201b1480f870836
1051970 F20110321_AAAAFE paranjpe_s_Page_05.jp2
9ff411994bbfb1d46012ce02d82d98e0
c47ab1e3c9db441b46ee8d8b4771dbf34cc7b060
66741 F20110321_AAAAKB paranjpe_s_Page_73.jpg
b2a6af4857cf5fcdf361c6d384ff7f7e
b25f94ca81464a7b3d08d3d07c529923d62e779e
5545 F20110321_AAAAFF paranjpe_s_Page_22thm.jpg
da2a37ef59531f8836b4ae7cbe18f134
9568493e25a6efa002d585d13df943896b530a18
28021 F20110321_AAAAKC paranjpe_s_Page_23.pro
0f472d07c191b8fec090c7862d216f79
5190bb26087c3d104410d2fe0a42d238c30e98e8
22710 F20110321_AAAARY paranjpe_s_Page_40.QC.jpg
04bf2ab35cf7bbf3d892516a9a15d763
c8d222fc9454eeb791ff334634c3b64de5235144
31850 F20110321_AAAAFG paranjpe_s_Page_10.jpg
9fafd7730efc57b0d3aee52bf67965dc
e2838320d6cdd0b97377432f421fbd810e21c3b6
1377 F20110321_AAAAPA paranjpe_s_Page_42.txt
674118e9f7c5b161c5ffbab48dd00918
0f066a4a6a5c7bd1e2297e539807a68753141638
41239 F20110321_AAAAKD paranjpe_s_Page_30.pro
4cce6846a9b2c93c9133072817dbc68e
bf4d3c3e623bc8895d3a2ac700de8a22a5b511fa



PAGE 1

REMOTE DETECTION OF HYDROGEN LEAKS USING LASER INDUCED RAYLEIGH/MIE SCATTERING By SAMEER PARANJPE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004

PAGE 2

Copyright 2004 by Sameer Subhash Paranjpe

PAGE 3

ACKNOWLEDGMENTS The author would like to thank Dr. Jill Peterson for her guidance and support. I would also like to thank my fellow students Raghuram Vempati, Philip Jackson, Murray Fisher, Matthew Gabriel and Ryan Ferguson for their assistance in various portions of the project. iii

PAGE 4

TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii LIST OF TABLES.............................................................................................................vi LIST OF FIGURES..........................................................................................................vii ABSTRACT.......................................................................................................................xi CHAPTER 1 INTRODUCTION........................................................................................................1 2 LITERATURE REVIEW.............................................................................................6 Mie Scattering...............................................................................................................6 Rayleigh Scattering.......................................................................................................7 Buoyant Jet Theory.......................................................................................................9 3 THEORETICAL FRAMEWORK..............................................................................10 Elastic and Inelastic Light Scattering.........................................................................10 Elastic Scattering Mechanism.....................................................................................10 Mie Theory..........................................................................................................11 Calculation of intensity distribution functions I1 and I2......................................14 Rayleigh Theory..................................................................................................15 Photon arrival rate calculations for Rayleigh and Mie theory.............................17 Scattering Cross Section Considerations.............................................................18 Buoyant Jet Theory.....................................................................................................18 Froude Number Calculation................................................................................19 Buoyant Jet Profiles and Concentration Variation..............................................20 4 EXPERIMENTAL SCHEME....................................................................................23 Collection at 90 and Backscatter...............................................................................23 Back Scatter Considerations................................................................................30 Data Recording Procedure...................................................................................30 iv

PAGE 5

5 RESULTS AND DISCUSSION.................................................................................32 Comparison of Theoretical and Experimental Photon Arrival Rate...........................32 Calculation of Theoretical Rayleigh Photon Arrival Rate..................................32 Calculation of Theoretical Mie Photon Arrival Rate..........................................33 Calculation of Total Theoretical Photon Arrival Rate........................................38 Calculation of Experimental Photon Arrival Rate...............................................38 Data Analysis Techniques..........................................................................................41 Integrated area method........................................................................................42 Peak Voltage Method..........................................................................................43 Analysis of Recorded Data.........................................................................................46 Case I: Argon-ion laser........................................................................................46 Peak voltage variation..................................................................................46 Normalized peak voltage variation..............................................................48 Standard deviation profiles...........................................................................48 Case II: Pulsed Nd:YAG laser ; pure helium......................................................50 Peak voltage variation..................................................................................50 Normalized Peak Voltage Variation............................................................51 Standard deviation profiles...........................................................................51 Case III: Pulsed Nd:YAG laser; 20%helium ,80% nitrogen...............................52 Peak voltage variation..................................................................................52 Normalized peak voltage variation..............................................................53 Standard Deviation Profiles.........................................................................54 Measurements in Backscatter.....................................................................................55 6 CONCLUSIONS........................................................................................................58 LIST OF REFERENCES...................................................................................................60 BIOGRAPHICAL SKETCH.............................................................................................62 v

PAGE 6

LIST OF TABLES Table page 3-1 Scattering cross section at a wavelength of 532 nm.................................................18 3-2 Froude number calculations show that the criteria for buoyant jet is met for all combinations of flow fluids, nozzle diameters and downstream distances..............20 5-1 Particle counter data show the particle distribution in the lab.................................34 5-2 Shows that average peak voltage recorded after 300 pulses in shear layer is a converged mean........................................................................................................45 5-3 Control volume to leak diamter ratio for all three cases shows that the ratio is far less for backscatter than 90 scattering...............................................................57 vi

PAGE 7

LIST OF FIGURES Figure page 3-1 Mie scattering geometry...........................................................................................11 3-2 I1 (perpendicular) and I2 (parallel) intensity distribution functions from the interactive webpage..................................................................................................15 3-3 I1 (perpendicular) and I2 (parallel) intensity distribution functions from McCartney.15 3-4 Instantaneous and time averaged profiles of a typical buoyant jet...........................21 3-5 Concentration variation with r for z = 2...................................................................22 4-1 Experimental scheme for collection of scattered light at 90...................................24 4-2 Experimental scheme for collection of scattered light at a 180 (back scatter).......25 4-3 Nozzle mounting showing three dimensional motion capability.............................27 4-3 Photomultiplier tube linearity tested as a function of flash lamp voltage................29 4-4 Calculation of nozzle traverse distances..................................................................31 5-1 Theoretical photon arrival rate calculations.............................................................33 5-2 Model M shows maritime distribution of aerosols (McCartney 1979, page 139)...35 5-3 Model M duplicated on a log-normal scale..............................................................36 5-4 Comparison of number density of maritime and lab aerosols..................................37 5-5 Effect of maritime and lab aerosol distribution on Mie scattered intensity.............37 5-6 Typical waveform of a burst seen on the oscilloscope.............................................39 5-7 Points in shear layer where measurements are made...............................................40 5-8 Comparison of experimental and theoretical photon arrival rates...........................41 5-9 Convergence studies of normalized area and averaged area....................................42 vii

PAGE 8

5-10 Waveform with varying glare at four downstream locations...................................43 5-11 All four waveforms normalized with their individual peaks....................................44 5-12 Voltage variation for Argon-Ion laser......................................................................47 5-13 Normalized peak voltage variation for argon-ion laser............................................48 5-14 Percent standard deviation variation for near field case..........................................49 5-15 Percent standard deviation for far field case............................................................49 5-16 Voltage variation for pulsed Nd:YAG laser.............................................................50 5-17 Normalized peak voltage variation for Nd:YAG laser.............................................51 5-18 Standard deviation variation for Nd:YAG laser for pure helium.............................52 5-19 Relative size of beam and leak diameter..................................................................52 5-20 Voltage variation for the pulsed Nd:YAG laser for the mixture..............................53 5-21 Normalized peak voltage variation for Nd:YAG laser for the mixture....................54 5-22 Percent standard deviation variation for Nd:YAG laser for the mixture of helium and nitrogen to simulate the optical properties of nitrogen......................................54 5-23 Schematic of backscatter on a time basis shows separation between beam dump glare and scattered signal from the nozzle...............................................................55 5-24 Normalized area variation shows a reduction in scattered intensity in presence of helium (backscatter); Nozzle diameter = ; Re =500; Fr = 290...........................56 viii

PAGE 9

NOMENCLATURE a = particle radius (m) C = concentration of the flow fluid (kg/m3) C* = dimensionless density CPMT = photomultiplier tube calibration constant D = diameter of the nozzle (m ; ) Ei = Electric vector of the incident wave (V/m) Fr = Froude number =Re/Gr2 G= gravitational acceleration (m/s2) Gr = Grashof number = g(a-o)D3/o Hi = Magnetic vector of the incident wave (N/Ampere-m) Io = Incident laser power (W; photons/pulse) 1 = length of control volume (m) m = mass flow rate (kg/s) n = gas index of refraction at known reference conditions n(r) = number density per radius interval (molecules/m3/micron) N = molecular number density (molecules/m3) Nd = number of data points. r = radial distance from jet centerline (m) rx-y = cross co-relation coefficient Re = Reynolds number = vD/ = 4m/ D ix

PAGE 10

v = velocity of buoyant jet (m/s) V= photomultiplier tube voltage (V) x = percent helium y = distance from jet centerline normal to beam z = downstream distance (mm) Greek Symbols = size parameter = 2a/ = spread angle = angle of observation measured from the forward to scattering directions. = scattering angle = wave function = optical efficiency of transmitting and collecting lenses = solid angle of the collection optics = wavelength of laser light (nm) = differential scattering cross section (m2/sr) = density of gas (kg/m3) = dynamic viscosity of gas (Pa-s) = dynamic viscosity of gas Subscripts a = ambient cl = centerline i = species m = mixture o = jet exit condition x

PAGE 11

Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science REMOTE DETECTION OF HYDROGEN LEAKS USING LASER INDUCED RAYLEIGH/MIE SCATTERING By Sameer Paranjpe December 2004 Chair: Jill Peterson Major Department: Mechanical and Aerospace Engineering The current study examines the use of laser induced Rayleigh/Mie scattering as a means of remotely detecting hydrogen leaks. An axisymmetric vertical buoyant jet at a Reynolds number of 500 was used to simulate the hydrogen leak and the scattered signal indicating hydrogen concentration was examined at different downstream locations. Helium was used as a substitute for hydrogen for safety reasons. The scattering cross section of hydrogen is 0.23 times the scattering cross section of air and the scattering cross section of helium is 0.015 times the scattering cross section of air. A mixture of 20% helium and 80% nitrogen was also used at the same Reynolds number of 500, since the scattering cross section of this mixture equals the scattering cross section of hydrogen. The principal challenges in RLS detection were electronic shot noise and Mie scattering. The electronic shot noise was found to induce less than 0.1% uncertainty for an averaging time of 1 second. A Nd:YAG pulse laser operating at a wavelength of 532 nm was used and the scattered signal from the helium leak was collected at 90 to the xi

PAGE 12

incident beam and focused onto a photomultiplier tube. The signal from the photomultiplier tube was read through a high speed digital oscilloscope. The repeatability and reproducible of the data was established using a set of convergence studies. It was found that the amplitude of the Rayleigh/Mie signal decreased by 25% and the standard deviation increased by 45% in the presence of helium. This increase in standard deviation is more than the established values of 305. Non dimensionalized profiles collapsed to a classic similar shape, further documenting experimental results. xii

PAGE 13

CHAPTER 1 INTRODUCTION Hydrogen is an attractive fuel source. However, leak detection is essential if it is to become a widespread, easily used and safe source of energy. It is relatively simple to determine whether a system is leaking hydrogen by identifying pressure drops. Finding the source of the leak however can be time consuming, costly and dangerous. The conventional method of leak detection involves the use of contact sensors. The following are the typical varieties of contact sensors commonly used for leak detection. Catalytic bead sensors. These sensors consist of two beads surrounding a wire operating at a temperature of around 450C. One of the beads is passivated. This ensures that it does not react with gas molecules. The other bead is coated with a catalyst to promote a reaction with the gas. The beads are generally placed on separate legs of a Wheatstone bridge circuit. When hydrogen is present, there is no measurable effect on the passivated bead, but there is a significant effect on the catalyzed bead. The increase in heat increases the resistance in that leg of the Wheatstone bridge circuit, which in turn changes the bridge balance signal, and this serves as the sensor signal. These sensors are usually used in the 1 to 5 % hydrogen range. The response time of the sensor varies, ranging from 10 to 30 seconds for full-scale response. Semiconductor sensors. These sensors use semiconducting oxides whose electrical resistance changes in the presence of hydrogen due to a reduction reaction. These sensors generally operate at temperatures above ambient. The disadvantage of these sensors is that the oxides change their resistance as the oxygen concentration in the 1

PAGE 14

2 environment changes, making these sensors unsuitable for such environments. They have a fast response time and detection limits of 0-1000 ppm hydrogen. Electrochemical sensors. Electrochemical sensors are composed of an anode and cathode sandwiching a chemically sensitive electrolyte. When hydrogen passes over the electrolyte, a reversible chemical reaction occurs. This generates a current proportional to the gas concentration. However, oxygen is required to ensure chemical reversibility. This implies that the sensor is not environmentally independent. Electrochemical sensors are typically used to detect hydrogen in the range of 100 to 1000 ppm. Response times can be as low as several seconds, although typically these sensors are specified at 30 to 50 seconds for full-scale response. Resistive palladium alloy sensors. The surface of palladium acts catalytically to break the H-H bond in diatomic hydrogen and allows the monatomic hydrogen to diffuse into the material. Palladium can dissolve more than 600 times its volume in hydrogen. The level of dissolved hydrogen proportionally changes the electrical resistivity of the metal. No other gases or environmental controls are necessary for these measurements. Hydrogen field effect transistor. By using palladium as the gate material for a standard field effect transistor, small changes in the resistivity of the palladium produce large changes in the current-voltage characteristics of the FET. This sensor technology works well in the range of 50 to 1000 ppm range of hydrogen. Although all these systems can effectively detect hydrogen leaks, the sensors are intrusive and have to be physically inserted into the suspect area. However due to the low combustion limits (4%) of hydrogen, for safety issues in most applications, it would be

PAGE 15

3 advantageous if the leak could be detected without actually inserting a probe in the suspected area. The current study explores a novel remote detection technique. Laser Induced Rayleigh/Mie Scattering This method uses a laser directed at a suspected leak source. As the laser pulse moves through air, the electromagnetic wave interacts with aerosols in the atmosphere and the molecules of the component gases. This causes some of the incident laser light to scatter in all directions, with varying intensities depending on the particle type and size. Substantial information can then be obtained by looking at the intensity of scattered light. The principal advantages of this technique are that it is non intrusive, it does not alter the flow pattern, and it has high spatial and temporal resolution. Almost 99% of the light scattered by atmospheric particles is elastically scattered. Rayleigh and Mie scattering are the two types of elastic light scattering theories. The mechanism of elastic light scattering and the quantification of the scattering cross section and scattered intensity terms are dealt in Chapter 3. Mie theory was developed by the German physicist G. Mie (1908). It is in terms of complex series solutions and is valid for particles of all sizes. If the particle size becomes very large, then Mie theory can be simplified using geometric optics. However, for particles with a diameter much less (approximately 0.06 times or less) than the wavelength of incident light, the Mie theory reduces to a single term simplification called the Rayleigh theory. The amount of light a particular particle can scatter can be defined in terms of its scattering cross section. Thus a particle with a higher scattering cross section would scatter more light than a particle with a lower scattering cross section. For Rayleigh/Mie scattering, the scattering cross section is a dominant function of the particle size, wavelength of incident light and refractive index of the particle. The scattering cross section of hydrogen is about 1/5th that

PAGE 16

4 of the surrounding air molecules. Hence the intensity of light scattered by hydrogen is expected to be less than the intensity of light scattered by the surrounding air molecules. In the absence of hydrogen, there would be a steady signal from the atmosphere that would consist of the Mie signal from the aerosols and Rayleigh signal from the air molecules. In the presence of hydrogen, we should expect this signal to fall. The primary objective of this study is to detect the fall in scattered intensity in the presence of hydrogen. Because of safety issues, helium, which has a scattering cross-section 0.015 times that of air is used for the experimentation. In order to match the scattering cross section of hydrogen, a mixture of 20% helium and 80% nitrogen is also used. The scattered intensity is directly proportional to the scattering cross section. The proportionality constant depends on the experimental conditions. For a fixed experimental set up, the scattered signal from a given control volume would be the same if the product of scattering cross section and number density of species in that control volume is identical. Hence, as seen in Chapter 3, the scattered signal from a mixture of 20% helium and 80% nitrogen and from pure hydrogen are the same. A second objective is to test the limits of detection. The measurements are taken at four different downstream locations for this purpose. Also measurements are taken in back scatter to test the feasibility of the technique for field measurements. Two nozzles with diameters of (6.3mm) and (12.6mm) are used for simulating the leak. A continuous wave low power argon ion laser is used with the nozzle and a high power pulsed Nd:YAG laser was used with the nozzle. For each nozzle diameter the data is recorded for the two cases of pure helium and the mixture of 20% helium and 80% nitrogen. The Reynolds number is fixed at 500 for each case and

PAGE 17

5 Froude numbers are calculated as discussed in Chapter 3. For all combinations of Reynolds and Froude numbers the leak is an axisymmetric vertical buoyant jet. The mean and fluctuating temperature and concentration profiles of a buoyant jet are well established. Since the leak is a buoyant jet it is expected that the variation of recorded scattered voltage would follow these profiles.

PAGE 18

CHAPTER 2 LITERATURE REVIEW Mie Scattering Mie theory is the general solution for scattering of a plane electromagnetic wave by a particle of arbitrary size. In 1908 Mie first derived the relations for calculating various scattering characteristics of electromagnetic radiation, by homogenous, absorbing spheres of any diameter. The Mie solution was obtained via the solution of the wave equation which originates from the more fundamental Maxwell relations. The details of the Mie solution from these basic equations have been dealt with in references such as Kerker (1969), and Bohren and Huffman (1983). The solution involves series expansions called the angular intensity distribution functions. These distribution functions are complex and involve the calculation of Legendre polynomials and Riccati-Bessel functions. Over the past 30 years numerous algorithms and subroutines have been developed mostly in FORTRAN and C to calculate these functions. The first subroutine for calculating the scattering functions was developed by Dave (1970) and incorporates the first 10 terms of the series expansion. Wiscombe (1980) developed algorithms for calculating the intensity distribution functions. These functions were plotted as a function of scattering angle and were robust for any given combination of particle size, incident wavelength and refractive index. An interactive webpage was developed by Prahl (2000) which allows the computation of the intensity distribution functions at any value of scattering angle for input values of incident wavelength, particle size and refractive index. This subroutine is used for the 6

PAGE 19

7 theoretical calculations of Mie scattered intensity in this study. The results of the subroutine are verified against published values of the angular intensity distribution functions in Kerker (1969) .The comparison is discussed in Chapter 3. McCartney (1976) lists standard aerosol distribution for continental and maritime distributions. Using these particle distributions, the number of particles of a particular size can be calculated as discussed in Chapter 5. Knowing the particle size distribution, the intensity distribution functions can be calculated using the subroutine by Prahl (2000). The details of these calculation are shown in Chapter 5. Mie scattering from particles has been used as a probe for monitoring concentration fluctuations. This technique called Marker nephelometry uses light scattered from seeded particles in a flow (Mie scatters) as a concentration probe. Since its introduction in 1961 by Rosenweig et al. (1961), this technique has proven to be a very useful probe for monitoring real time fluctuations manifested by seeded particles in the flow. Becker et al.(1967) and Shaughnessy and Morton (1977) have described the application of this technique. The same technique has been used for 2-D measurements by Long et al.(1981). These workers used a plane of light to illuminate particles in a flow field and used a television camera to get a digitized 2-D image of turbulent mixing. Rayleigh Scattering For particles smaller than the incident wavelength (diameter < 0.06 wavelength) only the first term of the Mie solution is needed to predict the intensity of scattered light. This single term simplification called the Rayleigh theory has been extensively discussed in literature notably by McCartney (1976) and Kerker (1969). Van de Hulst (1981) addressed the issue of assuming Rayleigh scattering to be single and independent of surrounding scatters. At 1 atm pressure and at a temperature of 300 K, air molecules are

PAGE 20

8 separated by distances over 600 radii. He estimated that 3 radii distance between surrounding scatters is sufficient separation to ensure independent scattering. This means that the assumption of no multiple scattering is valid for air molecules for pressures much higher than atmospheric pressures. Rayleigh light scattering is an ideal probe for gas temperature and concentration measurements since it is non-obtrusive, direct and has high spatial and temporal resolution. Using the Rayleigh scattered signal the number density of species under consideration can be calculated and since for an ideal gas at constant pressure, the number density is inversely proportional to temperature, the temperature can be known. Using this relation Muller-Dethelfs and Weinberg (1979) first used Rayleigh light scattering for temperature measurements in flame speed experiments. Dibble et al. (1980) used this technique to measure temperature fluctuations in premixed flames and also demonstrated that this technique could be extended to turbulent diffusion flames where the fuel and air have been carefully chosen to have identical Rayleigh scattering cross sections. Pitz et al. (1976) use RLS to measure temperature in a hydrogen-air flame. Horton and Peterson (1999) carried out transient temperature measurements in an ideal gas using laser induced RLS. Flow visualizations and transient temperature measurements were done in an axisymmetric impinging jet in a rapid thermal chemical vapor deposition reactor using RLS by Matthew and Peterson (2002). Robben (1975) evaluated the spectral broadening of Rayleigh scattered light to derive a temperature in turbulent flow measurements. Rayleigh light scattering has also been used for monitoring the concentration fluctuations which occur in isothermal turbulent flows by Graham et al.

PAGE 21

9 (1974) and Dyer (1979). Pitts and Kashiwagi (1983) used RLS for the study of turbulent mixing. Bryner and Pitts (1992) used RLS for combustion studies. One of the major disadvantages of RLS is background glare, which is at the same wavelength as that of the scattered beam and is impossible to filter from the signal. Glare minimization is possible by blackening the surfaces. Otugen (1993) used a dual line detection RLS technique for gas temperature measurements in which they eliminated surface scattered laser light from the Rayleigh signal by using two wavelengths. A primary assumption in this study was that the ratio of the surface reflection at two wavelengths is constant. The results indicated that accurate temperature measurements were possible even when the laser light background intensity was twice the Rayleigh signal. Buoyant Jet Theory As previously stated, in this study the leak is created using pure helium and a mixture of 20% helium and 80% nitrogen. The density of both pure helium and the mixture of helium and nitrogen is different from the surrounding fluid (air). The Reynolds number is set at 500. As discussed in Chapter 3 the leak for both cases could be assumed to be an axisymmetric vertical buoyant jet. The mean and fluctuating temperature and concentration profiles of a buoyant jet are well established in numerous references notably Rodi (1982), Chen and Rodi (1980) and Schlichting (1979). In this study, the recorded scattered voltage and standard deviation profiles were compared with these well established concentration profiles.

PAGE 22

CHAPTER 3 THEORETICAL FRAMEWORK Elastic and Inelastic Light Scattering There are two types of light scattering mechanisms: elastic scattering and inelastic scattering. In inelastic scattering there is a loss in energy of the incident wave and the scattered wave is emitted at a frequency different from the incident wave i.e hincident hscattered. One of the types of inelastic light scattering is termed as Raman scattering and it involves a change in either the vibrational or rotational quantum number of the constituent molecule. In elastic scattering of light, there is no loss of energy between the incident and the scattered wave. i.e hincident = hscattered. Elastic scattering is 2 to3 orders of magnitude greater than inelastic scattering. This is the primary reason for choosing elastic scattering as a measurement technique since the signal strength is expected to be 2 to 3 orders of magnitude higher than the inelastic signal making it more easily discernible. The mechanism of elastic scattering is discussed in detail in below. Elastic Scattering Mechanism Consider an electromagnetic wave traveling through atmosphere. Scattering occurs whenever it encounters an obstacle in its path. This obstacle could be a gas molecule, dust particle or aerosols. For simplification, the term molecule is used in this description of the mechanism of elastic scattering. A molecule can be considered a mechanical oscillator carrying unequal masses and opposite charges at the center and periphery. The elastic scattering theory assumes that the molecules are non polar. This means that the 10

PAGE 23

11 negative charge is uniformly distributed over the periphery and can be assumed to be at the center. Hence the electric dipole moment, which is the product of the charge and the separation distance, is zero in its stable state. In the presence of an electromagnetic wave the charges are forced apart due to the external electric field of the wave and an induced dipole moment is created. Since the field strength of the external electric field varies periodically, the induced dipole oscillates synchronously with the field. This oscillating dipole then emits a secondary wave at the same frequency as that of the primary wave. This secondary wave is the scattered wave. Mie Theory Figure 3-1 shows the scattering geometry for Mie scattering. Figure 3-1. Mie scattering geometry. The Mie theory describes the scattering of a plane electromagnetic wave by a particle of arbitrary size. The Mie theory originates from the exact solution of scattering of an electromagnetic wave equation (derived from the Maxwell relations) by a particle

PAGE 24

12 and has been discussed in detail by Kerker (1969). A scattered wave is generated whenever a plane wave is incident upon a particle possessing a discrete boundary and a refractive index different from the surrounding medium. In spherical co-ordinates the wave equation can be described as [ 1 r2 + 1 sin + 1 2 + k ] = 0 (3.1) r2 r r r2 sin r2 sin2 2 The solutions to this equation are the HertzDebye potentials which can be obtained by the method of separation of variables as follows: = R(r)()() (3.2) Each of these functions satisfies the following ordinary differential equations: d2rR(r) + [k2 n(n+1) ] rR(r) = 0 (3.3) dr2 r2 1 d (sin d() ) + [n(n+1) m2 ] () = 0 (3.4) sin d d sin2 d2() + m2() = 0 (3.5) d2 where n and m are integers. The solutions of equation 3.3 are the Riccati Bessel functions defined as n(kr) = (kr/2) Jn + (kr) (3.6) n(kr) = -(kr/2) Nn + (kr) where Jn + (kr) and Nn + (kr) are the half integer order Bessel and Neumann functions. The solutions of equation 3.4 are the associated Legendre polynomials given by = Pn(m)(cos) (3.7) The solutions to 3.5 are the sin(m) and cos(m).

PAGE 25

13 The general solution of the scalar wave equation (3.1) (the Hertz Debye potentials) can be obtained from a linear superposition of all of the particular solutions. The Hertz Debye potentials represent the solution for the incident wave, the scattered wave and the wave inside the particle. Only the Hertz Debye potentials for the scattered wave are discussed here. The Hertz Debye potentials for the scattered wave can be expressed in terms of an infinite series and are called the angular intensity distribution functions I1 and I2. I1 and I2 are proportional to the perpendicular polarized and parallel polarized components of the light scattered at an angle respectively. n= I1 = | 2n+1 (ann(cos) + bnn(cos))|2 (3.8) n=1 n+1 n= I2 = | 2n+1 (ann(cos) + bnn(cos))|2 (3.9) n=1 n+1 where n(cos) = P n (1)(cos) (3.10) sin and n(cos) = d P n (1)(cos) d The constants an and bn are obtained from the boundary conditions that the tangential components of the electric and magnetic field of the incident wave are continuous over the entire surface of the sphere. If the number density (N) of the particle is known then the Mie scattering cross section for a single particle size can be defined as Mie = 2 N(I1+I2) (3.11) 82 The Mie scattering cross section is an indication of the intensity of light that would be scattered from a particle of arbitrary size.

PAGE 26

14 Calculation of intensity distribution functions I1 and I2 From equations (3.8) and (3.9) it can be seen that the intensity distribution functions I1 and I2 are in terms of complex infinite series and involve the calculation of the Legendre polynomials for every value of n. Also the constants an and bn involve the calculation of Riccati Bessel functions for every value of n. As stated in Chapter 2, subroutines for the calculation of I1and I2 are available. In this study one such program developed by the Oregon Medical Laser Center is used. The input parameters are the incident wavelength, particle size and refractive index. McCartney (1979) states that the refractive index of crystalline haze aerosols can be assumed to have a value of 1.33. The aerosols are assumed to be dielectric. This value is used throughout this study. It is to be noted that the angular intensity distribution functions depend on the refractive index and the value of 1.33 imposes a limiting condition since it does not take into account dry particles like soot. The values of I1 and I2 obtained from this subroutine are compared with published values of I1 and I2 in McCartney (1979). The comparison is done for five combinations of incident wavelength, refractive index and particle size. A typical comparison is shown in figures 3-2 and 3-3. Size parameter gives the relation between the size of the particle and the wavelength of incident light and is defined as = 2 a (3.12) Figure 3-1 shows the values of I1 and I2 obtained as a function of scattering angle for a size parameter () of 0.5 (particle radius of 0.044 microns) and refractive index of sphere of 1.33. Using the program and figure 3-2 is obtained from McCartney for the same input parameters. The two figures are identical, establishing the accuracy of the subroutine.

PAGE 27

15 0.00E+002.00E-044.00E-046.00E-048.00E-04020406080100120140160180Observation angle (deg) perpendicular unpolarized parallel Figure 3-2. I1 (perpendicular) and I2 (parallel) intensity distribution functions for size parameter =5, and refractive index =1.33 obtained from the interactive webpage. Figure 3-3. I1 (perpendicular) and I2 (parallel) intensity distribution functions for size parameter =5, and refractive index =1.33 from McCartney. Rayleigh Theory The Mie solution is a complex mathematical solution. For particles of size much less than the wavelength of incident light, the Mie series solution converges in one term and is called the Rayleigh theory. The Rayleigh theory was originally put forth by Lord Rayleigh (J.W. Strutt, third Baron of Rayleigh) in 1871, long before the Mie solution was developed (1908). Later on it was proved that the Rayleigh theory is actually a single term simplification of the Mie theory. Lord Rayleigh put forth the Rayleigh theory principally to explain the blue color of the sky. He assumed that the particles were

PAGE 28

16 spherical, isotropic, much smaller than the wavelength of incident light and denser than the surrounding medium. Through straightforward dimensional reasoning he arrived at the conclusion that scattering varies directly with the square of the particle volume and inversely as the fourth power of the wavelength of incident light. The scattering by gas molecules is in the Rayleigh regime because of the small size of the molecules. McCartney (1976) gives a good physical description of Rayleigh scattering. He states that for the Rayleigh theory to be applicable, 1 or the particle radius should be at least 0.03 times less than the wavelength of incident light. The following are the assumptions about the molecules for Rayleigh scattering. 1. The molecules are non ionized implying that there is no overall charge over the entire molecule. This means that the molecule does not experience a net force in an electric field. 2. The molecules are non polar meaning that the electronic charge is uniformly distributed over the shell and could be treated to be at the center. Even though the polar assumption is made in the original theory, the Rayleigh theory is valid for non-polar particles as well. 3. The molecule is isotropic implying that the forces experienced within the molecule are balanced. 4. The molecule is linear which means that the binding forces within the molecule obey Hookes law. 5. The molecules are lightly damped meaning that the amplitude of oscillation does not become too large at frequencies near resonance. These assumptions are applicable to ordinary gas molecules like nitrogen and helium. Based on these assumptions McCartney (1976) derives the differential Rayleigh scattering cross section for perpendicular polarized scattered light as Rayleigh = 128 5a6n2 1 (3.13) 34 n2 + 2 As seen from equation (3.13) the Rayleigh scattering cross section is independent of the scattering angle and has an inverse fourth power dependence on the wavelength of incident light. It also depends on the refractive index (n) of the particle.

PAGE 29

17 Photon arrival rate calculations for Rayleigh and Mie theory Knowing the Rayleigh and Mie scattering cross sections the intensity of scattered light can be calculated for a given set of experimental constants. Both the Rayleigh and Mie scattering cross sections are applicable for an individual molecule and are not functions of the gas number density N assuming independent scattering. For a given volume of a gas the intensity of scattered light is linearly proportional to the gas number density. The scattering from multiple molecules in a given volume can be considered to be additive, independent and incoherent because of the random spacing and thermal motion of the gas molecules. Thus for an incident beam of energy I0 ,scattered from a control volume with molecular number density N, the intensity of the scattered beam is proportional to the scattering cross section of the molecule, the number density and the energy of incident beam Iscat = C(I0N) (3.14) The proportionality constant is defined by the scattering geometry, namely the solid angle of the collection optics (), control volume (dV) and optical efficiency of the collection optics (). In this study, the scattered beam was collected using a 60 mm diameter lens at a distance of 250 mm from the scattering volume which define the solid angle. The control volume depends on the angle at which the scattered beam is collected and is discussed in chapter 4. The optical efficiency was assumed to be 90% for each optical surface the scattered beam is passed through. Thus for Rayleigh scattering the intensity of scattered light from a control volume containing a mixture of gases is given by IRayleigh = (Io)()(dV)()(NRayleigh)i (3.15)

PAGE 30

18 And scattered intensity for Mie scattering is given by IMie = (Io)()(dV)()(NMie)i (3.16) Knowing the Rayleigh and Mie scattered intensities, the total scattered intensity received at the collection lens can be calculated as Itotal = IRayleigh + IMie (3.17) Scattering Cross Section Considerations In this study, pure helium and a mixture of 20% helium and 80% nitrogen are used. The scattering cross section of helium is 0.015 times the scattering cross section of air and the scattering cross section of pure hydrogen is 0.23 times the scattering cross section of air. In order to match the scattering cross section of hydrogen, a mixture of 20% helium and 80% nitrogen is used. The differential scattering cross sections of hydrogen, helium and nitrogen are listed at a wavelength of 532 nm in table 3-1. Table 3-1. Scattering cross section at a wavelength of 532 nm. Gas Scattering Cross Section () (m2/sr) Air (Nitrogen) 8.16E-32 Hydrogen 1.88E-32 Helium 1.22E-33 Knowing these values, the mixture concentration of 20% helium and 80% nitrogen are obtained using the following relation (x = % helium) hydrogen = x helium + (1-x) nitrogen. (3.18) Buoyant Jet Theory Buoyancy forces arise in a jet if the density of the flow fluid is different from the density of the surrounding fluid. In the absence of buoyancy forces the jet is called a non buoyant jet. In the other limiting case when the buoyancy force dominates the flow, the

PAGE 31

19 jet is called a plume. Thus the non buoyant jet has about the same density as the surrounding environment so that the buoyancy forces are absent, whereas a pure plume has no initial momentum. The densities of both flow fluids used for the experimentspure helium and the mixture of helium and nitrogen are different from the density of the surrounding fluid (ambient air). The Froude number is used to characterize whether a jet is a non buoyant jet, a buoyant jet or a plume-Chen and Rodi (1980). The Froude number is the ratio of inertial forces to buoyancy forces and is defined as Fr = Re/Gr2 (3.19) Reynolds number is the ratio of the inertial forces to the viscous forces and can be written as Re = vd (3.20) The Grashof number (G) is defined as g( a o )D 3 (3.21) o And it is the ratio of buoyant to viscous forces. In a non buoyant jet, only the Reynolds number is of influence (Fr=) whereas in pure plumes only the Grashof number is dominant (Fr=0). For an axisymmetric vertical jet, the limiting condition for a buoyant jet is defined in Chen and Rodi as follows 0.5 < Fr-1/2 (o/a)-1/4 (z/D) < 5 (3.22) Froude Number Calculation Two different nozzle diameters of and are used. Also two flow fluids (pure helium and mixture of 20% helium and 80% nitrogen) are used. Four different cases are considered: diameter nozzle with pure helium, diameter nozzle with a mixture of 20% helium and 80% nitrogen, diameter nozzle with pure helium and diameter

PAGE 32

20 nozzle for a mixture of 20% helium and 80% nitrogen. The measurements are taken for four downstream distances of 2, 4, 6, and 8 nozzle diameters. The Reynolds number is chosen as 500 for each case. The criterion for buoyant jet (equation 3.21) is tested for all four combinations of nozzle diameters and flow fluid and at all four downstream distances. Table 3-2 lists the values of Froude numbers for all four combinations of nozzle diameters and flow fluid and for the two limiting cases of 2 and 8 nozzle diameters downstream. Table 3-2. Froude number calculations show that the criteria for buoyant jet is met for all combinations of flow fluids, nozzle diameters and downstream distances 0.5 < Fr-1/2(o/a)-1/4z/D <5 Cases Reynolds Number(Re) Froude Number(Fr) 2 nozzle diameters 8 nozzle diameters 1. ; He 500 36.5 0.521 2.08 2. ; 20%He, 80%N2 500 64.5 0.54 2.16 3. ; He 500 292.5 0.88 3.52 4. ; 20%He, 80%N2 500 516.5 0.94 3.76 Buoyant Jet Profiles and Concentration Variation Figure 3-4 shows the instantaneous and time averaged profiles of a buoyant jet. The jet centerline is characterized by a potential core near the nozzle exit. Inside the potential core, the concentration of the flow fluid is 100%. The shear layers define the jet spread angle ().The edge of the shear layers mark the boundary of the time averaged profile. The concentration of the flow fluid varies from a 100% at the jet centerline to 0 % at the edge of the shear layers. Chen and Rodi (1980) have listed the spread angles of nonisothermal jets. In this study a spread angle of 13 is found for a vertical round buoyant jet.

PAGE 33

21 Chen and Rodi (1980) summarize empirical data predicting the axial spread of an axisymmetric vertical buoyant jet. The concentration at any point in the shear layer of a buoyant jet can be calculated using the following relation. CC a = exp [-Kc(r/z)2 ] (3.23) CclCa Time Averaged Profile z Instantaneous profile Shear layer Potential core Spread angle r Black cover Nozzle Figure 3-4. Instantaneous and time averaged profiles of a typical buoyant jet. The constant Kc is related to the jet spread angle as Kc = ln 2/ (tan/2) 2 (3.24) So, for a jet spread angle of 13 Kc = 53.4

PAGE 34

22 For a vertical buoyant jet, the centerline concentration (Ccl ) is found from the dimensionless density (C*) using the following equation C o C a = C* = 4.4Fr1/8(o/a) -7/16 (z/D)-5/4 (3.25) CclCa Using this value of Kc the concentration of the flow fluid at any point in the flow can be calculated using equation 3.22. For both the diameter nozzle and the diameter nozzle, CCa/CclCa is plotted as a function of radial distance (r) for a downstream distance (z) of 2 nozzle diameters for each case as seen in figure 3-5. 00.20.40.60.811.200.71.42.12.83.54.24.95.66.377.78.49.19.8r 1/4 inch nozzle 1/2 inch nozzle Figure 3-5. Concentration variation with r for z = 2 is Gaussian in nature for both nozzle diameters of and

PAGE 35

CHAPTER 4 EXPERIMENTAL SCHEME Collection at 90 and Backscatter The goal of the project is to detect the change in intensity of scattered light in the presence of hydrogen. Rayleigh scattering is independent of the angle at which the scattered light is collected but the Mie signal depends on the scattering angle. Initially, the collection optics were set at 90 to the incident beam and the measurements were focused on a single point of the beam as seen in figure 4-1. An advantage of this optical configuration is that the glare from the incident beam on the scattered signal is minimum at this angle since the minimum incident beam area is visible to the photomultiplier tube. For field measurements since the exact position of the leak could be at any distance from the laser, the drawback with a 90 scattering scheme would be that the collection optics consisting of the collecting, focusing lenses, filter, photomultiplier tube and the digital oscilloscope would have to be moved depending on the position of the suspected leak. It would be ideal to use a scheme in which the collection optics could be kept stationary. This can be done by using a backscatter scheme in which the incident light is passed between two 4 (101.6mm) square mirrors and the scattered light is collected at a 180 using the two mirrors. The mirrors are 90% reflective at a wavelength of 532 nm. The backscatter scheme is shown in figure 4-2. For the backscatter scheme, since the angle of observation is a 180, the control volume is defined by the beam area and the pulse width of 5 ns (1.5m). This leads to a fall in the signal to noise ratio as the leak occupies only 0.6% of the control volume as discussed in Chapter 5. 23

PAGE 36

24 N ozzle Lase r Beam dum p Scattered bea m Incident bea m Collectin g lens Focusin g lens Ban d p ass filte r O p tical sli t Photomultiplier tube High speed digital oscilloscope Figure 4-1. Experimental scheme for collection of scattered light at 90 The back scattering scheme uses the same set of collection optics as that for the 90 scattering scheme except that the 90 scheme uses a 60 mm collecting lens. From ray tracing it is found that the beam divergence angle of the scattered beam arriving at the

PAGE 37

25 mirrors was 0.4 and so the scattered rays reflected from the mirrors are effectively collimated and could be focused on the photomultiplier tube. Lase r Mirro r s Beam dum p N ozzle Scattered bea m Incident bea m Focusin g lens Ban d p ass filte r O p tical sli t Photomultiplier tube High speed digital oscilloscope Figure 4-2. Experimental scheme for collection of scattered light at a 180 (back scatter) The following components constitute the optical set up shown in figures 4.1 and 4.2.

PAGE 38

26 Laser. Initially the experimentation was done using an argon ion laser operated on the 488 nm wavelength. The laser power was set at 3 W and the beam diameter was 1mm with a beam divergence angle of 0.06. The argon ion laser is a continuous beam low power laser. In order to amplify the scattered signal and for higher temporal resolution a pulsed Nd:YAG laser was also used. The laser power is 200 mJ/pulse at a wavelength of 532 nm. The pulse width was 5 nanoseconds and the frequency is 10 Hz. The beam diameter is 6 mm with a beam divergence angle of 1.1. Since the beam diameter was larger than the Argon-Ion laser, the Nd:YAG laser defined a larger control volume than the Argon-Ion laser. Thus two different power lasers at two wavelengths are used for the experiments. Nozzle. The leak was simulated using a nozzle. The laser beam was passed directly over the nozzle. The nozzle is placed at a distance of 8 feet (20.32 cm) from the laser for the 90 scattering scheme. Using the beam divergence angle, the beam diameter over the nozzle was calculated to be 1.1 mm for the Argon ion laser and 8 mm for the pulsed Nd:YAG laser. In order to analyze the effect of the relative size of the beam and leak, two different nozzle diameters are used. For initial measurements using the argon ion laser a (12.6mm) nozzle was used. For the pulsed laser a (6.3mm) diameter nozzle was used. Thus for the argon ion laser, the beam diameter is 11.5 times less than the leak diameter whereas for the Nd:YAG laser the beam diameter is 1.25 times more than the leak diameter. The back scattering scheme uses the pulsed Nd:YAG laser with the diameter nozzle. The nozzle is placed at a distance of 20 feet (50.8 cm) from the laser and the beam diameter is 10 mm over the nozzle. The Reynolds number of the leak is set at 500 for both nozzle diameters and the Froude number was calculated as

PAGE 39

27 discussed in chapter 3 and presented in table 3.1. This combination of Reynolds and Froude number ensured that the leak is a buoyant jet. The nozzle is covered with a black felt drape to minimize glare. The mass flow rate of pure helium and the mixture of helium and nitrogen is monitored using mass flow controllers. Nozzle mounting. Three micrometer traverses are used for mounting the nozzle for three dimensional motion. Each traverse has a least count of 0.05 mm. Figure 4-3 shows the schematic of the mounting used. This allowed the measurements to be taken at different downstream locations. T T T y r N z y r z ozzle raverse 3 raverse 2 raverse 1 Figure 4-3. Nozzle mounting showing three dimensional motion capability. Beam dump. The incident laser beam was trapped using a beam dump. The beam dump was placed at a distance of 20 feet from the nozzle to minimize glare. Collection optics. The scattered beam was collected using a set of collection optics which consisted of a collecting lens, focusing lens, band pass filter and a

PAGE 40

28 photomultiplier tube. The collection optics were covered with a black felt drape in order to eliminate additional glare. Collecting lens. The collecting lens is a 60 mm diameter lens and has a focal length of 250 mm. As seen from figure 4-1 the focal point of the lens coincides with the nozzle position so that scattered light collected by the lens is collimated. As seen from figure 4-2 the collection lens was not used for the backscattering geometry because the scattered beam reflected from the two mirrors was collimated. Focusing lens. The focusing lens is a 60 mm diameter lens and had a focal length of 124 mm. The collimated beam from the collecting lens is focused on the Photomultiplier tube using the focusing lens. Band pass filter. For the Nd:YAG laser, the band pass filter is a 532 nm line filter that blocks background light at other wavelengths from reaching the photomultiplier tube. The band pass filter was kept at a distance of 3 mm from the Photomultiplier tube. Photomultiplier tube. The scattered beam is focused on the Photomultiplier tube. The Photomultiplier tube is a Hamammatsu model number HC 120-01 tube and has a built in amplifier with adjustable gain. It has a rise time of 2 ns and a bandwidth of 23 Khz. This means that the photomultiplier tube can distinguish between two signals that are 44 microseconds apart. Since the frequency of the pulse laser is 10 Hz the interval between two consecutive pulses is almost 1ms. Hence for a 90 scattering geometry, the photomultiplier tube can distinguish between two consecutive pulses. From the manufacturers specifications the calibration constant of the photomultiplier is found to be 121 V/nW which allows the conversion of the voltage recorded on the photomultiplier tube into power. The Photomultiplier tube has a 0.015 mm optical slit mounted on it to

PAGE 41

29 minimize the intensity of scattered light. The Photomultiplier tube converts the photonic signal to electrical voltage which is then sent to a high speed digital oscilloscope. It is important to note that even though the photomultipliers are considered to be highly linear devices, the linearity generally occurs over a lesser range for the pulsed Nd:YAG laser. ( = 532 nm) at varying flash lamp discharge voltage. Figure 4-4 displays the photomultiplier tube voltage as a function of varying flash lamp discharge voltage. R2 = 0.99315005205405605806006206406606800.911.11.21.31.4 Series1 Linear (Series1) Figure 4-3. Photomultiplier tube linearity tested as a function of flash lamp voltage High Speed Digital Oscilloscope. The photomultiplier tube signal is recorded on a high speed digital oscilloscope (LeCroy). It has two channel simultaneous data acquisition capabilities. It is triggered externally using the pulsed laser. The trigger time is 180 ns which means that the laser sends an electric signal to the oscilloscope exactly 180 ns before it fires the pulse so that the oscilloscope can be set to capture the scattered signal. The oscilloscope acquires data over a time period of 50 microseconds. The measurements are recorded and readout on a spreadsheet. Control Volume. For the 90 scheme, the control volume is defined by the beam diameter and the length of the control volume is defined by the width of the optical slit

PAGE 42

30 (150 microns). Back Scatter Considerations As previously stated the back scattering scheme is used to test the feasibility of the technique for field measurements. An important consideration for field measurements is the ability to detect the leak over longer distances. Hence the leak is created by placing the nozzle at a distance of 20 feet (50.8 cm) the laser beam. The beam dump is placed at a distance of 10 feet (25.4 cm) from the nozzle. The control volume is defined by the beam diameter and the length of the control volume for this case is defined by the pulse width (5nanoseconds =1.5m) Data Recording Procedure The measurements were done at four different downstream locations of 2, 4, 6 and 8 nozzle diameters for the pulsed Nd:YAG laser and two downstream locations of 2 and 6 nozzle diameters for the argon ion laser. For each downstream distance the nozzle was traversed along the direction of the beam using the micrometer traverse as shown in figure 4-3. The steps in which the nozzle was traversed was calculated from the spread angle of the jet as seen in figure 4-4. The distances 1a, 2b, 3c and 4d varied depending on the nozzle diameters ( or ). This was done so that the measurements done at all four downstream distances could be graphed on the same scale of r/z.

PAGE 43

31 z d 4 c 3 8d r b 2 6d y 4d a 1 2d 6.5 nozzle Figure 4-4. Calculation of nozzle traverse distances for downstream distances of 2, 4, 6 and 8 nozzle diameters using jet spread angle of 13.

PAGE 44

CHAPTER 5 RESULTS AND DISCUSSION Comparison of Theoretical and Experimental Photon Arrival Rate This section discusses how the theoretical and experimental photon arrival rates compare. In chapter 3 the equations for calculating the Rayleigh photon arrival rate (equation 3.15) and Mie photon arrival rate (equation 3.16) are presented. The total theoretical photon arrival rate is calculated as a sum of the Rayleigh and Mie photon arrival rates (equation 3.17). Calculation of Theoretical Rayleigh Photon Arrival Rate. In the presence of helium, the Rayleigh photon arrival rate can be calculated by modifying equation 3.15 as follows. The percent helium (x) was varied from 0 to 100 and the resulting photon arrival rate is shown in figure 5.1. IRayleigh = (I0)()(dV)()N(xHe + (1-x) air) (5.1) I0 = 7.07E+6mj/m2-pulse = 1.88E22 photons/ m2-pulse(Nd:YAG laser) ; 3.8E+6 W/ m2 (Argon-Ion laser) = (0.9)5 dV = 1.2 E-8m3 (90 scatter); 1.2E-4m3 (backscatter) = (60)2/(250) 2 sr (90 scatter); (2)(101.6)2/(12100) 2 sr (backscatter) N = 2.2E25 molecules/m3 He = 1.22E-33 m2/sr air = 8.16E -32 m2/sr 32

PAGE 45

33 2.00E+081.20E+092.20E+093.20E+094.20E+095.20E+096.20E+097.20E+098.20E+090102030405060708090100% Heliumphoton arrival rate(photons/pulse) Rayleigh photonarrival rate Mie photon arrivalrate total photon arrivalrate Figure 5-1. Theoretical photon arrival rate calculations show that Rayleigh signal is higher than Mie signal. Calculation of Theoretical Mie Photon Arrival Rate Equation 3.16 is used for the calculation of the Mie photon arrival rate. IMie = I0)()(dV)()(NMie)i (3.16) The two unknowns in this equation are Ni and (Mie)i The calculation of (Mie)i involves the use of the intensity distribution functions I1 and I2 If the particle size is known, these functions can be calculated for a give wavelength of incident light using the subroutine as discussed in Chapter 3. Two size distributions were used to determine the size of particles in the ambient air and also the number density of particles of a particular size. Distribution 1 uses the data from a LASAIR II particle counter. Table 5-1 shows a typical output of the particle counter data. The sampling is done in the laboratory for a sampling time of 1 minute and the volume of particles sampled over this period is 1 cubic feet. The particle size is given in column 1. Columns 2 and 3 give the lower and upper limits of the number of particles of

PAGE 46

34 the corresponding size. An average of columns 2 and 3 is taken. Thus using the LASAIR II data, the number density-particles per m3 (N i) of a particular size are known. For each particle of size of 0.3, 0.5, 1, 5, 10, 25 microns the Mie scattering subroutines are used to calculate I1 and I2 at a wavelength of 532 nm for the pulsed Nd:YAG laser. Knowing I1 and I2 ,Mie is calculated using equation 3.11 and the Mie scattered intensity using equation 3.16. To account for the presence of helium equation 3.16 was modified as IMie = I0lNMie(1-xHe) (5.2) Table 5-1. Particle counter data show the particle distribution in the lab. Particle size (microns) Number of particles/ft3 (lower limit) Number of particles/ft3 (upper limit) 0.3 25268 27272 0.5 7864 9222 1 1164 1298 5 100 104 10 12 12 25 1 1 For distribution 2 the typical maritime aerosol distribution in McCartney (1969) is used. Figure 5-2 shows particle distribution for stratospheric dust particles or hailstones (model H), continental aerosols (model L) and maritime aerosols (model M). The maritime aerosol distribution (model M) is chosen since it is appropriate for Cape Canaveral. The number density per radius interval n(r) for this distribution is calculated using the following fit (McCartney) n(r) = ar exp(-br) (5.3) Where the constants a, b ,, have the following empirically determined values a = 5333

PAGE 47

35 b = 8.9443 = 1 =1/2. Figure 5-2. Model M shows maritime distribution of aerosols which is used to calculate the particle size distribution.(McCartney 1979, page 139) Using the values of particle size (r) ranging from 0 to 25 microns, and the above values of the constants, the model M (log-log scale) was duplicated on a regular scale as shown in figure 5-3.

PAGE 48

36 0501001502002503003500.1110100particle sizeparticle concentration n(r) Model M Figure 5-3. Model M duplicated for calculating the number density using radius interval on a log-normal scale. The number density is calculated for the same particle radii as the LASAIR II data. (i = 0.3, 0.5, 1, 5, 10 and 25 microns) by integrating the area under the curve shown in figure 5-2 using following equation. The interval (i) to (i+1) represents the difference between the two consecutive particle radii i=6 Ni = 0.5(n(r)i + n(r)i+1)I (5.4) i=1 The values of number density -Ni (particles/m3) obtained from equation are compared with the values of Ni from the particle counter (Table 5.1). Figure 5-4 shows this comparison. As seen from the figure the particle distribution for maritime and lab aerosols is similar. For distribution 2 since the number density and the particle radius are known (equation 5.4) the Mie scattering cross section and the intensity of Mie scattered signal is calculated using the same approach as in distribution 1.

PAGE 49

37 01002003004005006007008000.1110100particle sizeNumber Density McCartney Lab Figure. 5-4. Comparison of number density of maritime and lab aerosols shows similarity Figure 5-5 shows the comparison between the Mie photon arrival rates for the two distributions. The value of I0 used is that for the pulsed Nd:YAG laser. 1.00E+086.00E+081.10E+091.60E+092.10E+09020406080100% HeliumMie photon arrival rate (photons/pulse) Maritime distribution lab data Figure 5-5. Effect of maritime and lab aerosol distribution on Mie scattered intensity shows that both signals are of the same order of magnitude. As seen from the graph, both signals are of the same order of magnitude. The maximum difference between the two signals (55%) is for the case of 0% helium since all

PAGE 50

38 Mie scattering particles have been displaced, and no ambient air is in the control volume. Both signals tend to zero as the helium concentration approaches 100%. This figure shows that the Mie signal would be of the same order and smaller for maritime field measurements as that for laboratory measurements. Calculation of Total Theoretical Photon Arrival Rate For the calculation of IMie the data from the particle counter is used since it represents aerosol distribution for the experimental conditions. Knowing IRayleigh and IMie, the total theoretical photon arrival rate is calculated using equation 3.17. Figure 5-1 shows the variation of Rayleigh, Mie and total photon arrival rate with percent helium. The value of I0 used here is for the pulsed Nd:YAG laser. An important result of the theoretical study is that the Mie scattered signal is lesser than the Rayleigh scattered signal. Initially it was reasoned that the Mie scatters would augment the scattered signal since in the presence of helium the total signal would fall due to reduction in Mie signal. This study shows that although this factor is present it influences the total scattered signal to a lesser degree. Calculation of Experimental Photon Arrival Rate The voltage as a function of time waveform obtained on the oscilloscope represents the total scattered intensity recorded at the photomultiplier tube per pulse. Figure 5-6 shows a typical waveform of a burst seen on the oscilloscope. The waveform is recorded at a downstream distance of 4 nozzle diameters with no flow fluid. Integrating this waveform using equation 5.5 gives the total scattered intensity per pulse (VPMT) i=100 VPMT = 0.5(Vi +Vi+1)(0.1) (5.5) i=0

PAGE 51

39 where (i) represents the time scale from 0 to 100 microseconds varied in steps of 0.1 each. -0.100.10.20.30.40.50.60.70102030405060708090time (microseconds)Raw voltage(V) waveform Figure 5-6. Typical waveform of a burst seen on the oscilloscope (Downstream distance of 4 nozzle diameters, no flow fluid) The Photomultiplier tube calibration constant (CPMT) at the wavelength of 532 nm is found to be 121 V/nW from the manufacturers specifications. The measurements are done using the pulsed ND:YAG laser at 6 different helium concentrations of 0, 20, 40, 60 80 and 100% using the diameter nozzle. As discussed in buoyant jet theory (Figure 3-5) the flow fluid (helium) concentration can be predicted in the shear layer for a combination of downstream distances and radial distance (r/z). The downstream distance (z) is fixed at 2 nozzle diameters. From equation 3.23 it is seen that for a fixed value of z, the radial distance (r) can be calculated if the concentration C is known since the centerline concentration of the flow fluid (Ccl) is known using equation 3.25 and the concentration of flow fluid (Ca) in the ambient is 0%. CC a = exp [-Kc(r/z)2 ] (3.23) CclCa

PAGE 52

40 Thus for 6 different values of C (0, 20, 40, 60, 80 and 100), the measurements are made for the corresponding values of radial distance(r) obtained from equation 3.23. Figure 5-7 shows the values of radial distance r where the measurements are made for each value of C. Concentration profile Point of measurement z=2 Shear layer r Figure 5-7. Figure shows points in shear layer where measurements are made corresponding to each value of C using pulsed Nd:YAG laser and nozzle at a downstream distance of 2 nozzle diameters. Re = 500; Fr = 290. For each measurement the integrated area under the voltagetime curve on the oscilloscope represents the total scattered signal per burst. Equation 5.6 is used to convert the voltage recorded for each measurement into scattered signal in photons per pulse. Iexperimental= VtPMT/CPMThc (5.6) Figure 5-8 shows the comparison of the experimental and theoretical photon arrival rates for varying percentages of helium.

PAGE 53

41 R2 = 0.99781.00E+092.00E+093.00E+094.00E+095.00E+096.00E+097.00E+098.00E+099.00E+090102030405060708090100% heliumphoton arrival rate(photons/pulse) theoretical photonarrival rate experimental photonarrival rate Linear (experimentalphoton arrival rate) Figure 5-8. Comparison of experimental and theoretical photon arrival rates. The experimental and theoretical photon arrival rates are of the same order of magnitude with a maximum error of 57.3% for the case of 100% helium and a minimum error of 11.3% for the case of 0% helium. A linear regression of the experimental photon arrival rate gives a coefficient of 0.99 indicating a constant additional factor(s) contributing to the error independent of percent helium. This constant error can be attributed to 1.Background glare, which is at the same wavelength as that of scattered signal. 2. Deviation of optical efficiency of each collection surface from the assumed value of 90%. 3. Ambient air in control volume at jet edges. Data Analysis Techniques As previously stated for each burst the scattered signal from the photomultiplier tube is recorded as a voltage-time curve on the oscilloscope. Two techniques of analyzing the recorded voltage are considered. The Nd:YAG pulse laser with the nozzle is used for both techniques and the flow fluid is pure helium for both cases.

PAGE 54

42 Integrated area method Initially a set of 1000 data points per burst are captured from the oscilloscope and the integrated area under the voltage as a function of time curve is computed. For the measurements, the downstream distance is 2 nozzle diameters, Reynolds number is 500 and Froude number is 290. The measurements are done in the shear layer of the leak at a radial position corresponding to 60% helium concentration as shown in figure 5-7. This is because the maximum variation of recorded voltage is expected to be in the shear layer edge since the intermittency of the turbulence is maximum. This procedure was repeated for a set of pulses at the same nozzle position shown in figure 5-7 until the areas converged. Figure 5-9 shows the convergence studies for the area. -4-3-2-1012312345678910pulse number normalizd runningaverage of area normalized inidvidualarea (ViVmean)/Vmean Figure 5-9. Convergence studies of normalized area and averaged area shows that the area converged in 10 pulses. Series 1 represents the running average of the integrated area normalized with respect to the mean of 10 pulses. As seen from the graph, for a measurement in the shear layer a set of 10 pulses are enough for convergence. The maximum percent variation of

PAGE 55

43 any individual area from the mean is 3% and the maximum percent variation of the running average of area from the mean is 2.6%. Peak Voltage Method Two studies are undertaken to validate the use of peak voltage rather than integrated area as a repeatable and reproducible data measurement technique. A convergence study is also done to determine the number of peaks required for data measurement. These studies are carried out using the pulsed Nd:YAG laser with the nozzle. Study 1. For four downstream positions (z) of 2, 4, 6, and 8 nozzle diameters the waveform is recorded along the jet centerline (r=0) as seen in Figure 5-10. -0.100.10.20.30.40.50.60.70.80102030405060708090time (microseconds)Raw voltage variation z/d=2 z/d=4 z/d=6 z/d=8 Figure 5-10. Waveform with varying glare at four downstream locations. All four measurements are done in room air with no helium flowing through the nozzle. In this case we expect that the Rayleigh and Mie scattering signals are constant and the only variable in each case was the glare from the nozzle.

PAGE 56

44 All four waveforms were normalized with the corresponding peak as shown in figure 5.11. It is seen that all four waveforms fall on top of each other and it is impossible to distinguish between them. A four way cross correlation analysis of the waveforms was done using the following relation _ rx-y = (x i x)(y i -y) (5.7) _ ((xx)/Nd)2) (( yy)/Nd)2) The cross correlation coefficient was 99.7%. The high cross correlation coefficient supports the hypothesis that the peak voltage contains sufficient information of each waveform. -0.200.20.40.60.811.20102030405060708090100time (microseconds)(Vi/Vmax) z/d=2 z/d=4 z/d=6 z/d=8 Figure 5-11. All four waveforms normalized with their individual peaks to remove glare, the waveforms are indistinguishable. Study 2. In this study, a correlation analysis of the peak voltage and the corresponding integrated area is done for 10 pulses at the same nozzle position in the shear layer as that used with the integrated area studies above (Figure 5.7). The flow fluid is 100% helium and the Reynolds and Froude numbers are 500 and 290 respectively and

PAGE 57

45 radial position corresponding to 60% helium concentration. The downstream distance is 2 nozzle diameters. The correlation coefficient is 99.3% which again supports the relation between peak and area for a given pulse. Peak Convergence Study. From the previous two studies it is established that the peak contains all necessary information about the waveform and the peak and area are related. The convergence study is undertaken to establish the number of pulses required for convergence. The downstream distance is 2 nozzle diameters and the Reynolds and Froude numbers are 500 and 290 respectively for 100% helium. The measurements are done in the same position in the shear layer of the leak as for the previous two cases of integrated area and comparison of integrated area and peak (Figure 5.7) (radial position corresponding to 60% helium concentration. The average peak voltage is recorded after the 1st, 100th, 200th, 300th, 400th and 500th pulse. Table 5.2 lists the voltage recorded after each measurement. Column 3 of the table gives percent variation between two consecutive values of recoded voltage. Table 5-2. Shows that average peak voltage recorded after 300 pulses in shear layer is a converged mean. Pulse Number Average peak voltage (Vi) (mV) (ViVi-1)/Vi 0 550 100 576 4.7% 200 564 2.1% 300 559 0.88% 400 563 0.76% 500 558 0.89% As seen from table 5.1 the variation between average peak voltage is less than 1% if the peak voltage was recorded after 300 pulses. Also these measurements are carried out in the edge of the shear layer of the jet where the fluctuations in the flow are

PAGE 58

46 maximum. Hence it is concluded that for any nozzle position, recording the average peak voltage after 300 pulses is a reliable data measurement technique. Analysis of Recorded Data Figure 5-6 shows the comparison between the predicted (theoretical) and the measured (experimental) photon arrival rates. As stated earlier these studies are carried out using the pulsed Nd:YAG laser with a diameter nozzle at a downstream distance of 2 nozzle diameters. This section discusses the variation of peak voltage and standard deviation of the recoded voltage for the following four cases: Argon-ion laser with a diameter nozzle at downstream distances of 2 and 4 nozzle diameters for pure helium for 90 scattering scheme. Pulsed Nd:YAG laser with a diameter nozzle at downstream distances of 2, 4, 6 and 8 nozzle diameters for pure helium for 90 scattering scheme. Pulsed Nd:YAG laser with a diameter nozzle at downstream distances of 2and 4 nozzle diameters for a mixture of 20% helium and 80% nitrogen for 90 scattering scheme. Pulsed Nd:YAG laser with a diameter nozzle at downstream distances of 2, 6, 10 and 16 nozzle diameters for pure helium in back scatter. The nozzle was traversed in the radial (r) direction as discussed in chapter 4 for the 90 scattering scheme and in the (y) direction for the back scatter scheme. Case I: Argon-ion laser Peak voltage variation Initially the measurements were carried out using the argon-ion laser ( =488 nm) at two downstream distances of 2 and 6 nozzle diameters. The nozzle diameter of is used with the argon-ion laser and the flow fluid is pure helium. The Reynolds number of the leak is 500 and the Froude number is 35. the nozzle traverse distance for each measurement at each downstream position were calculated as discussed in Chapter 3. Three sets of measurements were done at each downstream position. Figure 5-11 shows the average of the normalized peak for all 3 measurements. Also shown are the error bars

PAGE 59

47 at both downstream locations corresponding to the standard deviation of each measurement point. The xaxis is the nozzle traverse distance (r) in mm. As seen from the figure, the scattered voltage reaches a minimum value of zero at the jet centerline for both downstream distances. Also the voltage variation inside the shear layer is visible. Hence due to the presence of helium in the shear layer, there is a fall in voltage inside the shear layer. As the downstream distance increases, the jet spreads out and the fall occurs over a wider radius. 0.41-15-10-5051015 z/d=2 z/d=6 r (mm) Vi/Vmax Figure 5-12. Voltage variation for Argon-Ion laser shows that there is a fall in voltage in presence of helium; nozzle at two downstream distances; Re =500; Fr =35. As seen from figure 5-12, the fall in peak voltage at the jet centerline which corresponds to 100% helium. Also, the fall in voltage occurs only in the presence of helium. At the ambient where there is no effect of flow fluid on the recorded voltage, the voltage remains constant. The fall in voltage in presence of helium occurs because 1. Helium molecules have a scattering cross section which is 0.015 times the cross section

PAGE 60

48 of the surrounding air molecules. 2. Molecules of the flow fluid displace some aerosols in their path which are Mie scatters. Hence there is a fall in the intensity of scattered light Normalized peak voltage variation. The raw peak voltage was normalized with the centerline voltage (ViVa)/(Vcl Va) as shown in figure 5-13. The normalized concentration profile plotted in chapter 3 is also shown as a function of r/z From figure 5-13 it is seen that the voltage variation follows a similar Gaussian distribution as that of well established normalized concentration profile of a axisymmetric vertical buoyant jet. 01-2.0-1.00.01.02.0r/z z/d=2 z/d=6 normalizedconcentration (ViVa)/(Vcl-Va) Figure 5-13. Normalized peak voltage variation for argon-ion laser for pure helium; Re= 500; Fr=3.5; nozzle diameter = Standard deviation profiles Figure 5-14 shows the variation of the normalized standard deviation ratioed to the centerline voltage /(Vmax Vcl) for the downstream distance of 2 nozzle diameters The downstream distance of 2 nozzle diameter represents the near field regime of the buoyant jet. It is seen that inside the potential core, the standard deviation falls as expected.

PAGE 61

49 0510152025-1.40-1.12-0.84-0.56-0.280.000.280.560.84r/z z/d=2 ____ % (Vmax-Vcl) Figure 5-14. Percent standard deviation variation for near field case showing the reduced fluctuation in the potential core. Figure 5-15 shows the variation of the normalized standard deviation of the data radioed to the centerline standard deviation for the far field case after the shear layers have coalesced. 05101520253035404550-1.40-1.12-0.84-0.56-0.280.000.280.560.84r/z z/d=6 ____ % (Vmax-Vcl) Figure 5-15. Percent standard deviation for far field case after shear layers have coalesced.

PAGE 62

50 The percent standard deviation is above the typical maximum variation of 30%. A possible reason for this is there is an additional factor of Mie scattering contributing to the increased standard deviation of the recorded voltage. Case II: Pulsed Nd:YAG laser ; pure helium Peak voltage variation. Figure 5-16 shows the variation of raw peak voltage with respect to the nozzle position for pure helium for the downstream distances of 2, 4, 6 and 8 nozzle diameters for the pulsed Nd:YAG laser (=532 nm) using the nozzle. The Reynolds number is 500 and Froude number is 290. As seen from the graph, for each individual downstream distance the voltage tends to remain constant outside the shear layer (ambient) due to absence of helium. As observed with the argon-ion laser, the fall in voltage occurs over a wider radius as the jet spreads out. Also the minimum voltage is recorded at the jet centerline. 0.71-30-20-10010203040r (mm) z/d=2 z/d=4 z/d=6 z/d=8 Vi/Vmax Figure 5-16. Voltage variation for pulsed Nd:YAG laser shows a similar profile of fall in voltage in presence of helium; Re= 500; Fr=290; nozzle diameter =

PAGE 63

51 Normalized Peak Voltage Variation Figure 5-17 shows the variation of the normalized peak voltage for all four downstream distances for the pulsed Nd:YAG laser for the case of pure helium. Also shown is the theoretical normalized concentration profile plotted in chapter 3 as a function of r/z. 01-2-1012r/z z/d=2 z/d=4 z/d=6 z/d=8 normalizedconcentration (ViVa)/(Vcl-Va) Figure 5-17. Normalized peak voltage variation for Nd:YAG laser for pure helium; Re= 500; Fr=290; nozzle diameter = Standard deviation profiles Figure 5-18 shows the standard deviation profiles for all four downstream distances of 2, 4, 6 and 8 nozzle diameters. Comparing figure 5-18 with the standard deviation profiles for the Argon-ion laser (figures 5-14 and 5-15), it is seen that the standard deviation variation is less distinct for the Nd:YAG laser. A possible reason for this could be the effect of the relative size of beam and nozzle (leak) diameters. The beam diameter for the argon ion laser is 1/10th the diameter of the nozzle whereas for the pulsed laser it was 1.2 times the nozzle diameter (Figure 5-19). This factor was an additional variance for the pulsed laser.

PAGE 64

52 02468101214161820-1.47-1.10-0.74-0.370.000.370.741.101.47r/z z/d=2 z/d=4 z/d=6 z/d=8 ____ % (Vmax-Vcl) Figure 5-18. Standard deviation variation for Nd:YAG laser for pure helium; Re= 500; Fr=290; nozzle diameter = Laser beam 8mm 1.2mm beam Laser beam Nozzle Nozzle 12.6mm 6.3mm Nd:YAG laser Argon-ion laser Figure 5-19. Relative size of beam and leak diameter for the Argon-ion and pulsed Nd:YAG laser. Case III: Pulsed Nd:YAG laser; 20%helium ,80% nitrogen Peak Voltage Variation Figure 5-20 shows the variation of peak voltage for a mixture of 20% helium and

PAGE 65

53 80% nitrogen for a downstream distance of 2 and 4 nozzle diameters for the pulsed Nd:YAG laser. This mixture of helium and nitrogen matches the scattering cross section of hydrogen as discussed in Chapter 3 and hence the amount of light scattered by the mixture is expected to be identical to that of Hydrogen. The Reynolds and Froude number were 500 and 515 respectively. 0.921-15-10-505101520 z/d=2 z/d=4 Vi/Vmax Figure 5-20. Voltage variation for the pulsed Nd:YAG laser for the mixture of helium and nitrogen shows that there is a fall in voltage; nozzle diameter ;Re=500, Fr = 515. The fall in voltage from figure 5-20 is 30 mV (6%) for the downstream distance of 2 nozzle diameters. The fall in voltage for z/d=2 for the case of 100% helium is 155 mV (30 %) as seen in figure 5-16. Normalized peak voltage variation. Figure 5-21 shows the normalized peak variation for the mixture at the downstream distances of 2 and 4 nozzle diameters. A comparison with the normalized concentration shows that the two profiles are similar.

PAGE 66

54 00.20.40.60.811.2-2-10123r/z z/d=2 z/d=4 normalizedconcentration (ViVa)/(Vcl-Va) Figure 5-21. Normalized peak voltage variation for Nd:YAG laser ; Re= 500; Fr=515; nozzle diameter = for a mixture of helium and nitrogen to simulate the optical properties of nitrogen. Standard Deviation Profiles. 051015202530-1.47-1.10-0.74-0.370.000.370.741.101.47r/z z/d=2 z/d=4 ____ % (Vmax-Vcl) Figure 5-22. Percent standard deviation variation for Nd:YAG laser ; Re= 500; Fr=515; nozzle diameter = for a mixture of helium and nitrogen to simulate the optical properties of nitrogen The standard deviation profiles of the mixture for both downstream distances of 2 and 4 nozzle diameters are shown in figure 5-22. The standard deviation for the mixture

PAGE 67

55 is more than the standard deviation of pure helium for the two distances. The presence of two flow fluids (helium and nitrogen) shows in the increased standard deviation. Measurements in Backscatter The principal issue in backscatter is distinguishing between the scattered signal and beam dump glare. Figure 5-23 is a schematic of the backscatter geometry represented on a time scale. The time difference between the scattered beam from the nozzle and reflected beam from the beam dump is approximately 20ns. Thus the photomultiplier tube should be able to distinguish between the two signals 20 ns apart. The minimum bandwidth of the photomultiplier tube required is 5 MHz. It was impossible to distinguish between the two signals using the Hammamatsu tube. (Bandwidth 23 KHz). 30.4 ns 20.32 ns Beam dump Nd:YAG laser nozzle Photomultiplier Figure 5-23. Schematic of backscatter on a time basis shows separation between beam dump glare and scattered signal from the nozzle. The waveform seen on the oscilloscope contained both the beam dump glare and the scattered signal. In order to distinguish between the signal and glare the

PAGE 68

56 measurements with helium for a typical nozzle position was normalized with a measurement without helium for the same nozzle position. Since the measurements were done in backscatter, the nozzle was traversed in a direction perpendicular to that of the beam(y-direction). Figure 5-24 shows the data in backscatter. 0.750.80.850.90.9511.05-15-10-5051051015r/zArea (helium)/ Area (air) z/d=2 z/d=6 z/d=10 z/d=16 Figure 5-24. Normalized area variation shows a reduction in scattered intensity in presence of helium (backscatter); Nozzle diameter = ; Re =500; Fr = 290 There is a fall in the normalized area in the presence of helium near the jet centerline for all downstream distances. For the case of downstream distance of 2 nozzle diameters, the fall in normalized area is about 0.15 V (15%). For the 90 scattering scheme for the pulsed Nd:YAG laser, the fall in voltage is approximately 30% (Figure 5-16) and 50% for the Argon-Ion laser for the downstream case of 2 nozzle diameters for pure helium (Figure 5-12). The control volume for the backscatter geometry is defiend by the 6mm diameter beam and the pulse width of 5 ns (1.5m) (4.29E-5m3). For the 90 scattering scheme, the control volume is defined by the 6mm diameter beam and the 0.015mm optical slit (4.29E-m3) for the Nd:YAG laser, and 1mm diameter beam and the 0.15mm optical slit for the Argon-Ion laser. (7.05E-12m3). The leak diameter for the pulse laser is whereas for the Argon-Ion laser its Thus for the 90 scattering

PAGE 69

57 geometry for both Argon-Ion and Nd:YAG cases, the leak occupies 100% of the control volume whereas for the backscatter geometry the leak occupies only 0.6% of the control volume as seen from table 5-3. Table 5-3. Control volume to leak diameter ratio for all three cases shows that the ratio is far less for backscatter than 90 scattering. Geometry Nozzle Diameter (D) Control Volume(CV) CV/D (percent) Backscatter,Nd:YAG 6.35E-3 m 4.29E-5m3 0.6 90 Nd:YAG 6.35E-3 m 4.29E-5m3 100 90 Argon-Ion 12.7E-3 m 4.29E-5m3 100 This might have lead to the lesser fall in intensity of scattered light in the presence of helium for backscatter geometry.

PAGE 70

CHAPTER 6 CONCLUSIONS The primary objective of this study is to establish the feasibility of laser induced light scattering as a leak detection technique for hydrogen. There are two primary reasons that support this objective. 1. The fall in voltage at the centerline of the leak indicating reduced scattered intensity both in the presence of pure helium (Helium = 0.015 Air) and a mixture of 20% helium and 80% nitrogen (Mixture = Hydrogen = 0.23 Air) 2. Standard deviation in excess of 30% for pure helium (argon ion laser). Both of these were due to the reduced intensity of Rayleigh scattering by helium molecules. The theoretical studies of Mie scattered intensity show that the Mie signal is the same order of magnitude for the laboratory and maritime particle distributions. This result is important for field measurements as the effect of Mie scattering on the total signal would be approximately the same. Initially it was thought that the fall in voltage would be amplified due to the Mie scatters. However, from the theoretical study it was seen that Mie signal is less than the Rayleigh signal. Hence the lack of Mie scatters in the control volume reduces the fall in voltage in the presence of Rayleigh scattering due to helium and nitrogen molecules. Concentration measurements in the presence of Mie scattering have been successfully done in the lab environment.The backscattering scheme is used principally to test the feasibility of this technique for field measurements. Since for laboratory measurements the scattered signal from the photomultiplier tube and the reflection from 58

PAGE 71

59 the beam dump are only 40 ns apart, it was impossible to distinguish between the two signals for the photomultiplier tube used for the experiments. This lack of temporal discrimination severely limits the overall signal to noise ratio for this configuration. The signal to noise ratio can be improved with better overall temporal response devices. A fall in voltage at the centerline of the flow is observed for both pure helium and the mixture of 20% helium and 80% nitrogen for all four downstream distances. This indicates that a leak could be detected at downstream distances as low as 8 nozzle diameters. Also leak detection is feasible when taken in context of the overall full field concentration distribution. Future Work In order to determine the effect of background light, a dual line detection system should be used. A study to determine the polarization effect of the incident beam on the scattered signal should be done.

PAGE 72

LIST OF REFERENCES Becker H, Hottel H, Williams G, Light scatter technique for the study of turbulent mixing, Journal of Fluid Mechanics, Nov 1967, vol. 30 (2), pp 259-284 Bohren C, Huffman D, 1983, Absorption and scattering of light by small particles, Wiley, New York. Bryner N, Pitts W, A Rayleigh Light scattering technique for investigation of free jets and plumes, Review of Scientific Instruments, 1992, vol. 63 (7), pp 3629-2635 Chen C, Rodi W, 1980, HMT the science and applications of heat and mass transfer, vol. 4, Pergamon Press, Oxford. Dave J, 1970, Scattering of electromagnetic radiation by a large, absorbing sphere. IBM J. Res. Dev. 1969, vol. 13(3), pp 302-313. Dibble R, Hollenbach R, Rambach G, Temperature measurements in turbulent flames via Rayleigh scattering, 1980, American Chemical Society, pp 435-441. Dyer T, Rayleigh scattering measurements of time resolved concentration in a turbulent propane jet, 1979, AIAA Journal vol. 17(8), pp 912-914 Graham S, Grant A, Jones J, Transient molecular concentration measurements in turbulent flows using Rayleigh light scattering, 1974, AIAA Journal, vol. 12(8), pp 1140-1142 Horton J, Peterson J, Transient temperature measurements in an ideal gas by using laser induced Rayleigh light scattering, August 1999, Review of Scientific Instruments, vol. 70(8), pp 3222-3226. Kerker M,1969, The scattering of light and other electromagnetic radiation, Academic Press, New York. Long M, Chu B, Chang R, Instantaneous two dimensional gas concentration measurements by light scattering, AIAA Journal, September 1981, vol. 19(9), pp 1151-1157. Matthew A, Peterson J, Flow visualizations and transient temperature measurements in an axisymmetric impinging jet rapid thermal chemical vapor deposition reactor, June 2002, Journal of Heat Transfer, vol. 124, pp 564-570 McCartney E, 1976, Optics of the atmosphere, Wiley, New York. 60

PAGE 73

61 Muller-Dethlefs K, Weinberg F, Burning velocity measurements based on laser Rayleigh scattering ,1979, Seventeenth symposium on combustion, vol. 27(2), pp 985-992. Otugen M, 1997, Nd:YAG laser based dual line Rayleigh scattering system, AIAA Journal vol. 35(5), pp 776-780. Prahl S, http://omlc.ogi.edu/calc/mie_calc.html Last accessed :10/20/2004, Oregon Medical Laser Center. Pitts W, Kashiwagi, 1983, The application of laser induced Rayleigh light scattering to the study of turbulent mixing, Journal of Fluid Mechanics, vol. 141, pp 391-429. Pitz R, Cattolica R, Robben F, Talbot L, Temperature and Density in a Hydrogen Air Flame from Rayleigh scattering, 1976, Com. Flame, vol. 27(3), pp 313-320. Robben F, Comparison of density and temperature using Raman scattering and Rayleigh scattering using combustion measurements in jet propulsion systems,1975, Proceedings of a project SQUID workshop, Purdue University. pp 179-195. Rodi W, 1982, HMT the science and applications of heat and mass transfer, Pergamon Press, Oxford Rosenweig R, Hottel H, Williams G, Smoke scattered light measurements of turbulent concentration fluctuations, Chem. Eng. Science, 1961, vol. 15(1,2), pp 111-129. Schlichting H, 1979, Boundry layer theory, McGraw Hill Series in Mechanical Engineering, New York Shaughnessy E, Morton J, Laser light scattering measurements of particle concentration in a turbulent jet. Journal of Fluid Mechanics, April 1977, vol. 80(1), pp129-148. Wiscombe W, 1989, Improved Mie scattering algorithms, Applied Optics, 1980, vol. 19(9), 1505-1509

PAGE 74

BIOGRAPHICAL SKETCH Sameer Paranjpe finished his undergraduate degree in mechanical engineering from the University of Bombay in 2002. He is pursuing his masters degree in mechanical engineering at the University of Florida. He has been a research assistant under Dr. Jill Peterson since August 2002. 62


Permanent Link: http://ufdc.ufl.edu/UFE0008972/00001

Material Information

Title: Remote Detection of Hydrogen Leaks Using Laser Induced Rayleigh/Mie Scattering
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0008972:00001

Permanent Link: http://ufdc.ufl.edu/UFE0008972/00001

Material Information

Title: Remote Detection of Hydrogen Leaks Using Laser Induced Rayleigh/Mie Scattering
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0008972:00001


This item has the following downloads:


Full Text












REMOTE DETECTION OF HYDROGEN LEAKS USING LASER INDUCED
RAYLEIGH/MIE SCATTERING















By

SAMEER PARANJPE


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2004

































Copyright 2004

by

Sameer Subhash Paranjpe















ACKNOWLEDGMENTS

The author would like to thank Dr. Jill Peterson for her guidance and support. I

would also like to thank my fellow students Raghuram Vempati, Philip Jackson, Murray

Fisher, Matthew Gabriel and Ryan Ferguson for their assistance in various portions of the

project.















TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S ......... .................................................................................... iii

LIST OF TABLES ............. ............................... .......... .......... .. vi

LIST OF FIGURE S ......... ..................................... ........... vii

ABSTRACT .............. .................. .......... .............. xi

CHAPTER

1 INTRODUCTION ............... ................. ........... ................. ... .... 1

2 LITER A TU R E REV IEW ............................................................. ....................... 6

M ie Scattering .................................................................................................... ...... 6
R ayleigh Scattering ........... ..................................................................... ....... .. .
Buoyant Jet Theory ............... ................ ......... ......................... .9

3 THEORETICAL FRAM EW ORK .................................... ......................... .. ......... 10

Elastic and Inelastic Light Scattering .................................. .................................... 10
Elastic Scattering M echanism .......................................................... ............... 10
M ie T theory ................................... ............................11
Calculation of intensity distribution functions I1 and I2 ...................................14
R ayleigh Theory .................................................. ..... .................... .. ... 15
Photon arrival rate calculations for Rayleigh and Mie theory.............................17
Scattering Cross Section Considerations.........................................................18
Buoyant Jet Theory ................. ............................ ..... ...... 18
Froude N um ber C alculation .............. ................................. ............... ... 19
Buoyant Jet Profiles and Concentration Variation ...........................................20

4 EXPERIM ENTAL SCHEM E .............................................................................23

Collection at 900 and B ackscatter......................................... .......................... 23
B ack Scatter C onsiderations..................................................... ................... .30
D ata R recording Procedure.............................. ........................... ... .............30









5 RESULTS AND DISCU SSION ........................................... .......................... 32

Comparison of Theoretical and Experimental Photon Arrival Rate...........................32
Calculation of Theoretical Rayleigh Photon Arrival Rate. ................................32
Calculation of Theoretical Mie Photon Arrival Rate .......................................33
Calculation of Total Theoretical Photon Arrival Rate. .....................................38
Calculation of Experimental Photon Arrival Rate................... ..... ............38
D ata A analysis Techniques ................................................ .............................. 41
Integrated area m ethod. .............................................. ............................. 42
Peak V oltage M ethod. ............................................... .............................. 43
Analysis of Recorded Data .......... ........ ...................................... 46
C ase I: A rgon-ion laser............ .................................................... ........ 46
P eak voltage variation ............................................ ........... ............... 46
N orm alized peak voltage variation ................................... .................48
Standard deviation profiles...................................... ......................... 48
Case II: Pulsed Nd:YAG laser; pure helium ............................................... 50
P eak voltage variation .............................................. ......... ............... 50
N orm alized Peak Voltage Variation .................................... ............... 51
Standard deviation profiles...................... ........................... 51
Case III: Pulsed Nd:YAG laser; 20%helium ,80% nitrogen.............................52
P eak voltage variation ............................................ ........... ............... 52
Norm alized peak voltage variation. .................................. .................53
Standard D aviation Profiles. ............................................. ............... 54
M easurements in Backscatter ................................. ................................... 55

6 CON CLU SION S .................................... ... ........... .......... ........... 58

LIST OF REFEREN CES ................................................................... ............... 60

B IO G R A PH IC A L SK E TCH ..................................................................... ..................62






















v
















LIST OF TABLES


Table page

3-1 Scattering cross section at a wavelength of 532 nm............................................18

3-2 Froude number calculations show that the criteria for buoyant jet is met for all
combinations of flow fluids, nozzle diameters and downstream distances.............20

5-1 Particle counter data show the particle distribution in the lab ..............................34

5-2 Shows that average peak voltage recorded after 300 pulses in shear layer is a
conv erg ed m ean .................................................. ................. 4 5

5-3 Control volume to leak diameter ratio for all three cases shows that the ratio is
far less for backscatter than 900 scattering .................................... ............... 57
















LIST OF FIGURES


Figure page

3-1 M ie scattering geom etry ......... ......... ................ ........................ ............... 11

3-2 Ii (perpendicular) and I2 (parallel) intensity distribution functions from the
interactive w ebpage .................. ................................. ..... .. ........ .... 15

3-3 Ii (perpendicular) and I2 (parallel) intensity distribution functions from McCartney. 15

3-4 Instantaneous and time averaged profiles of a typical buoyant jet...........................21

3-5 Concentration variation with r for z = 2 ....................................... ............... 22

4-1 Experimental scheme for collection of scattered light at 90.............. ................24

4-2 Experimental scheme for collection of scattered light at a 1800 (back scatter) .......25

4-3 Nozzle mounting showing three dimensional motion capability...........................27

4-3 Photomultiplier tube linearity tested as a function of flash lamp voltage ..............29

4-4 Calculation of nozzle traverse distances ....................................... ..................... 31

5-1 Theoretical photon arrival rate calculations. ...................................................33

5-2 Model M shows maritime distribution of aerosols (McCartney 1979, page 139) ...35

5-3 M odel M duplicated on a log-normal scale................................... ............... 36

5-4 Comparison of number density of maritime and lab aerosols..............................37

5-5 Effect of maritime and lab aerosol distribution on Mie scattered intensity ............37

5-6 Typical waveform of a burst seen on the oscilloscope....................................39

5-7 Points in shear layer where measurements are made ............................................40

5-8 Comparison of experimental and theoretical photon arrival rates .........................41

5-9 Convergence studies of normalized area and averaged area...............................42









5-10 Waveform with varying glare at four downstream locations ...............................43

5-11 All four waveforms normalized with their individual peaks.................................44

5-12 Voltage variation for Argon-Ion laser. ............................... ............................... 47

5-13 Normalized peak voltage variation for argon-ion laser.........................................48

5-14 Percent standard deviation variation for near field case. .......................................49

5-15 Percent standard deviation for far field case .................................... .................49

5-16 Voltage variation for pulsed Nd:YAG laser.................................. ............... 50

5-17 Normalized peak voltage variation for Nd:YAG laser.................. ... ............ 51

5-18 Standard deviation variation for Nd:YAG laser for pure helium...........................52

5-19 Relative size of beam and leak diameter ........................................ .............52

5-20 Voltage variation for the pulsed Nd:YAG laser for the mixture.............................53

5-21 Normalized peak voltage variation for Nd:YAG laser for the mixture .................54

5-22 Percent standard deviation variation for Nd:YAG laser for the mixture of helium
and nitrogen to simulate the optical properties of nitrogen................. ......... 54

5-23 Schematic ofbackscatter on a time basis shows separation between beam dump
glare and scattered signal from the nozzle. ................................... ............... 55

5-24 Normalized area variation shows a reduction in scattered intensity in presence of
helium (backscatter); Nozzle diameter = 1/4" ; Re =500; Fr = 290 .........................56















NOMENCLATURE


a = particle radius (m)

C = concentration of the flow fluid (kg/m3)

C* = dimensionless density

CPMT = photomultiplier tube calibration constant

D = diameter of the nozzle (m ; ")

E' = Electric vector of the incident wave (V/m)

Fr = Froude number =Re/Gr2

G= gravitational acceleration (m/s2)

Gr = Grashof number = g(pa-po)D3/po"

H' = Magnetic vector of the incident wave (N/Ampere-m)

o = Incident laser power (W; photons/pulse)

1 = length of control volume (m)

m = mass flow rate (kg/s)

n = gas index of refraction at known reference conditions

n(r) = number density per radius interval (molecules/m3/micron)

N= molecular number density (molecules/m3)

Nd = number of data points.

r = radial distance from jet centerline (m)

rx-y= cross co-relation coefficient

Re = Reynolds number = pvD/ u = 4m/ 7tDg









v = velocity of buoyant jet (m/s)

V= photomultiplier tube voltage (V)

x = percent helium

y = distance from jet centerline normal to beam

z = downstream distance (mm)

Greek Symbols

a = size parameter = 27na/X

P = spread angle

0 = angle of observation measured from the forward to scattering directions.

p = scattering angle

y = wave function

rI = optical efficiency of transmitting and collecting lenses

Q = solid angle of the collection optics

X = wavelength of laser light (nm)

c = differential scattering cross section (m2/sr)

p = density of gas (kg/m3)

[ = dynamic viscosity of gas (Pa-s)

u = dynamic viscosity of gas

Subscripts

a = ambient

cl = centerline

i = species

m = mixture

o =jet exit condition














Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

REMOTE DETECTION OF HYDROGEN LEAKS USING LASER INDUCED
RAYLEIGH/MIE SCATTERING


By

Sameer Paranjpe

December 2004

Chair: Jill Peterson
Major Department: Mechanical and Aerospace Engineering

The current study examines the use of laser induced Rayleigh/Mie scattering as a

means of remotely detecting hydrogen leaks. An axisymmetric vertical buoyant jet at a

Reynolds number of 500 was used to simulate the hydrogen leak and the scattered signal

indicating hydrogen concentration was examined at different downstream locations.

Helium was used as a substitute for hydrogen for safety reasons. The scattering cross

section of hydrogen is 0.23 times the scattering cross section of air and the scattering

cross section of helium is 0.015 times the scattering cross section of air. A mixture of

20% helium and 80% nitrogen was also used at the same Reynolds number of 500, since

the scattering cross section of this mixture equals the scattering cross section of

hydrogen. The principal challenges in RLS detection were electronic shot noise and Mie

scattering. The electronic shot noise was found to induce less than 0.1% uncertainty for

an averaging time of 1 second. A Nd:YAG pulse laser operating at a wavelength of

532 nm was used and the scattered signal from the helium leak was collected at 90 to the









incident beam and focused onto a photomultiplier tube. The signal from the

photomultiplier tube was read through a high speed digital oscilloscope. The repeatability

and reproducible of the data was established using a set of convergence studies. It was

found that the amplitude of the Rayleigh/Mie signal decreased by 25% and the standard

deviation increased by 45% in the presence of helium. This increase in standard deviation

is more than the established values of 305. Non dimensionalized profiles collapsed to a

classic similar shape, further documenting experimental results.














CHAPTER 1
INTRODUCTION

Hydrogen is an attractive fuel source. However, leak detection is essential if it is to

become a widespread, easily used and safe source of energy. It is relatively simple to

determine whether a system is leaking hydrogen by identifying pressure drops. Finding

the source of the leak however can be time consuming, costly and dangerous. The

conventional method of leak detection involves the use of contact sensors. The following

are the typical varieties of contact sensors commonly used for leak detection.

Catalytic bead sensors. These sensors consist of two beads surrounding a wire

operating at a temperature of around 4500C. One of the beads is passivated. This ensures

that it does not react with gas molecules. The other bead is coated with a catalyst to

promote a reaction with the gas. The beads are generally placed on separate legs of a

Wheatstone bridge circuit. When hydrogen is present, there is no measurable effect on

the passivated bead, but there is a significant effect on the catalyzed bead. The increase in

heat increases the resistance in that leg of the Wheatstone bridge circuit, which in turn

changes the bridge balance signal, and this serves as the sensor signal. These sensors are

usually used in the 1 to 5 % hydrogen range. The response time of the sensor varies,

ranging from 10 to 30 seconds for full-scale response.

Semiconductor sensors. These sensors use semiconducting oxides whose

electrical resistance changes in the presence of hydrogen due to a reduction reaction.

These sensors generally operate at temperatures above ambient. The disadvantage of

these sensors is that the oxides change their resistance as the oxygen concentration in the









environment changes, making these sensors unsuitable for such environments. They have

a fast response time and detection limits of 0-1000 ppm hydrogen.

Electrochemical sensors. Electrochemical sensors are composed of an anode and

cathode sandwiching a chemically sensitive electrolyte. When hydrogen passes over the

electrolyte, a reversible chemical reaction occurs. This generates a current proportional to

the gas concentration. However, oxygen is required to ensure chemical reversibility. This

implies that the sensor is not environmentally independent. Electrochemical sensors are

typically used to detect hydrogen in the range of 100 to 1000 ppm. Response times can be

as low as several seconds, although typically these sensors are specified at 30 to 50

seconds for full-scale response.

Resistive palladium alloy sensors. The surface of palladium acts catalytically to

break the H-H bond in diatomic hydrogen and allows the monatomic hydrogen to diffuse

into the material. Palladium can dissolve more than 600 times its volume in hydrogen.

The level of dissolved hydrogen proportionally changes the electrical resistivity of the

metal. No other gases or environmental controls are necessary for these measurements.

Hydrogen field effect transistor. By using palladium as the gate material for a

standard field effect transistor, small changes in the resistivity of the palladium produce

large changes in the current-voltage characteristics of the FET. This sensor technology

works well in the range of 50 to 1000 ppm range of hydrogen.

Although all these systems can effectively detect hydrogen leaks, the sensors are

intrusive and have to be physically inserted into the suspect area. However due to the low

combustion limits (4%) of hydrogen, for safety issues in most applications, it would be









advantageous if the leak could be detected without actually inserting a probe in the

suspected area. The current study explores a novel remote detection technique.

Laser Induced Rayleigh/Mie Scattering

This method uses a laser directed at a suspected leak source. As the laser pulse

moves through air, the electromagnetic wave interacts with aerosols in the atmosphere

and the molecules of the component gases. This causes some of the incident laser light to

scatter in all directions, with varying intensities depending on the particle type and size.

Substantial information can then be obtained by looking at the intensity of scattered light.

The principal advantages of this technique are that it is non intrusive, it does not alter the

flow pattern, and it has high spatial and temporal resolution.

Almost 99% of the light scattered by atmospheric particles is elastically scattered.

Rayleigh and Mie scattering are the two types of elastic light scattering theories. The

mechanism of elastic light scattering and the quantification of the scattering cross section

and scattered intensity terms are dealt in Chapter 3. Mie theory was developed by the

German physicist G. Mie (1908). It is in terms of complex series solutions and is valid for

particles of all sizes. If the particle size becomes very large, then Mie theory can be

simplified using geometric optics. However, for particles with a diameter much less

(approximately 0.06 times or less) than the wavelength of incident light, the Mie theory

reduces to a single term simplification called the Rayleigh theory. The amount of light a

particular particle can scatter can be defined in terms of its scattering cross section. Thus

a particle with a higher scattering cross section would scatter more light than a particle

with a lower scattering cross section. For Rayleigh/Mie scattering, the scattering cross

section is a dominant function of the particle size, wavelength of incident light and

refractive index of the particle. The scattering cross section of hydrogen is about 1/5th that









of the surrounding air molecules. Hence the intensity of light scattered by hydrogen is

expected to be less than the intensity of light scattered by the surrounding air molecules.

In the absence of hydrogen, there would be a steady signal from the atmosphere that

would consist of the Mie signal from the aerosols and Rayleigh signal from the air

molecules. In the presence of hydrogen, we should expect this signal to fall.

The primary objective of this study is to detect the fall in scattered intensity in the

presence of hydrogen. Because of safety issues, helium, which has a scattering cross-

section 0.015 times that of air is used for the experimentation. In order to match the

scattering cross section of hydrogen, a mixture of 20% helium and 80% nitrogen is also

used. The scattered intensity is directly proportional to the scattering cross section. The

proportionality constant depends on the experimental conditions. For a fixed

experimental set up, the scattered signal from a given control volume would be the same

if the product of scattering cross section and number density of species in that control

volume is identical. Hence, as seen in Chapter 3, the scattered signal from a mixture of

20% helium and 80% nitrogen and from pure hydrogen are the same.

A second objective is to test the limits of detection. The measurements are taken at

four different downstream locations for this purpose. Also measurements are taken in

back scatter to test the feasibility of the technique for field measurements.

Two nozzles with diameters of 14" (6.3mm) and /2" (12.6mm) are used for

simulating the leak. A continuous wave low power argon ion laser is used with the 4"

nozzle and a high power pulsed Nd:YAG laser was used with the 12" nozzle. For each

nozzle diameter the data is recorded for the two cases of pure helium and the mixture of

20% helium and 80% nitrogen. The Reynolds number is fixed at 500 for each case and






5


Froude numbers are calculated as discussed in Chapter 3. For all combinations of

Reynolds and Froude numbers the leak is an axisymmetric vertical buoyant jet. The mean

and fluctuating temperature and concentration profiles of a buoyant jet are well

established. Since the leak is a buoyant jet it is expected that the variation of recorded

scattered voltage would follow these profiles.














CHAPTER 2
LITERATURE REVIEW

Mie Scattering

Mie theory is the general solution for scattering of a plane electromagnetic wave by

a particle of arbitrary size. In 1908 Mie first derived the relations for calculating various

scattering characteristics of electromagnetic radiation, by homogenous, absorbing spheres

of any diameter. The Mie solution was obtained via the solution of the wave equation

which originates from the more fundamental Maxwell relations. The details of the Mie

solution from these basic equations have been dealt with in references such as Kerker

(1969), and Bohren and Huffman (1983).

The solution involves series expansions called the angular intensity distribution

functions. These distribution functions are complex and involve the calculation of

Legendre polynomials and Riccati-Bessel functions. Over the past 30 years numerous

algorithms and subroutines have been developed mostly in FORTRAN and C to calculate

these functions. The first subroutine for calculating the scattering functions was

developed by Dave (1970) and incorporates the first 10 terms of the series expansion.

Wiscombe (1980) developed algorithms for calculating the intensity distribution

functions. These functions were plotted as a function of scattering angle and were robust

for any given combination of particle size, incident wavelength and refractive index. An

interactive webpage was developed by Prahl (2000) which allows the computation of the

intensity distribution functions at any value of scattering angle for input values of

incident wavelength, particle size and refractive index. This subroutine is used for the









theoretical calculations of Mie scattered intensity in this study. The results of the

subroutine are verified against published values of the angular intensity distribution

functions in Kerker (1969) .The comparison is discussed in Chapter 3. McCartney (1976)

lists standard aerosol distribution for continental and maritime distributions. Using these

particle distributions, the number of particles of a particular size can be calculated as

discussed in Chapter 5. Knowing the particle size distribution, the intensity distribution

functions can be calculated using the subroutine by Prahl (2000). The details of these

calculation are shown in Chapter 5.

Mie scattering from particles has been used as a probe for monitoring concentration

fluctuations. This technique called Marker nephelometry uses light scattered from seeded

particles in a flow (Mie scatters) as a concentration probe. Since its introduction in 1961

by Rosenweig et al. (1961), this technique has proven to be a very useful probe for

monitoring real time fluctuations manifested by seeded particles in the flow. Becker et

al.(1967) and Shaughnessy and Morton (1977) have described the application of this

technique. The same technique has been used for 2-D measurements by Long et

al.(1981). These workers used a plane of light to illuminate particles in a flow field and

used a television camera to get a digitized 2-D image of turbulent mixing.

Rayleigh Scattering

For particles smaller than the incident wavelength (diameter < 0.06 wavelength)

only the first term of the Mie solution is needed to predict the intensity of scattered light.

This single term simplification called the Rayleigh theory has been extensively discussed

in literature notably by McCartney (1976) and Kerker (1969). Van de Hulst (1981)

addressed the issue of assuming Rayleigh scattering to be single and independent of

surrounding scatters. At 1 atm pressure and at a temperature of 300 K, air molecules are









separated by distances over 600 radii. He estimated that 3 radii distance between

surrounding scatters is sufficient separation to ensure independent scattering. This means

that the assumption of no multiple scattering is valid for air molecules for pressures much

higher than atmospheric pressures.

Rayleigh light scattering is an ideal probe for gas temperature and concentration

measurements since it is non-obtrusive, direct and has high spatial and temporal

resolution. Using the Rayleigh scattered signal the number density of species under

consideration can be calculated and since for an ideal gas at constant pressure, the

number density is inversely proportional to temperature, the temperature can be known.

Using this relation Muller-Dethelfs and Weinberg (1979) first used Rayleigh light

scattering for temperature measurements in flame speed experiments. Dibble et al. (1980)

used this technique to measure temperature fluctuations in premixed flames and also

demonstrated that this technique could be extended to turbulent diffusion flames where

the fuel and air have been carefully chosen to have identical Rayleigh scattering cross

sections. Pitz et al. (1976) use RLS to measure temperature in a hydrogen-air flame.

Horton and Peterson (1999) carried out transient temperature measurements in an ideal

gas using laser induced RLS. Flow visualizations and transient temperature

measurements were done in an axisymmetric impinging jet in a rapid thermal chemical

vapor deposition reactor using RLS by Matthew and Peterson (2002). Robben (1975)

evaluated the spectral broadening of Rayleigh scattered light to derive a temperature in

turbulent flow measurements. Rayleigh light scattering has also been used for monitoring

the concentration fluctuations which occur in isothermal turbulent flows by Graham et al.









(1974) and Dyer (1979). Pitts and Kashiwagi (1983) used RLS for the study of turbulent

mixing. Bryner and Pitts (1992) used RLS for combustion studies.

One of the major disadvantages of RLS is background glare, which is at the same

wavelength as that of the scattered beam and is impossible to filter from the signal. Glare

minimization is possible by blackening the surfaces. Otugen (1993) used a dual line

detection RLS technique for gas temperature measurements in which they eliminated

surface scattered laser light from the Rayleigh signal by using two wavelengths. A

primary assumption in this study was that the ratio of the surface reflection at two

wavelengths is constant. The results indicated that accurate temperature measurements

were possible even when the laser light background intensity was twice the Rayleigh

signal.

Buoyant Jet Theory

As previously stated, in this study the leak is created using pure helium and a

mixture of 20% helium and 80% nitrogen. The density of both pure helium and the

mixture of helium and nitrogen is different from the surrounding fluid (air). The

Reynolds number is set at 500. As discussed in Chapter 3 the leak for both cases could be

assumed to be an axisymmetric vertical buoyant jet. The mean and fluctuating

temperature and concentration profiles of a buoyant jet are well established in numerous

references notably Rodi (1982), Chen and Rodi (1980) and Schlichting (1979). In this

study, the recorded scattered voltage and standard deviation profiles were compared with

these well established concentration profiles.














CHAPTER 3
THEORETICAL FRAMEWORK

Elastic and Inelastic Light Scattering

There are two types of light scattering mechanisms: elastic scattering and inelastic

scattering. In inelastic scattering there is a loss in energy of the incident wave and the

scattered wave is emitted at a frequency different from the incident wave i.e hVincident

hvscattered. One of the types of inelastic light scattering is termed as Raman scattering and

it involves a change in either the vibrational or rotational quantum number of the

constituent molecule.

In elastic scattering of light, there is no loss of energy between the incident and the

scattered wave. i.e hVincident= hVscattered. Elastic scattering is 2 to3 orders of magnitude

greater than inelastic scattering. This is the primary reason for choosing elastic scattering

as a measurement technique since the signal strength is expected to be 2 to 3 orders of

magnitude higher than the inelastic signal making it more easily discernible. The

mechanism of elastic scattering is discussed in detail in below.

Elastic Scattering Mechanism

Consider an electromagnetic wave traveling through atmosphere. Scattering occurs

whenever it encounters an obstacle in its path. This obstacle could be a gas molecule,

dust particle or aerosols. For simplification, the term molecule is used in this description

of the mechanism of elastic scattering. A molecule can be considered a mechanical

oscillator carrying unequal masses and opposite charges at the center and periphery. The

elastic scattering theory assumes that the molecules are non polar. This means that the









negative charge is uniformly distributed over the periphery and can be assumed to be at

the center. Hence the electric dipole moment, which is the product of the charge and the

separation distance, is zero in its stable state. In the presence of an electromagnetic wave

the charges are forced apart due to the external electric field of the wave and an induced

dipole moment is created. Since the field strength of the external electric field varies

periodically, the induced dipole oscillates synchronously with the field. This oscillating

dipole then emits a secondary wave at the same frequency as that of the primary wave.

This secondary wave is the scattered wave.

Mie Theory

Figure 3-1 shows the scattering geometry for Mie scattering.


2





















Figure 3-1. Mie scattering geometry.

The Mie theory describes the scattering of a plane electromagnetic wave by a

particle of arbitrary size. The Mie theory originates from the exact solution of scattering

of an electromagnetic wave equation (derived from the Maxwell relations) by a particle









and has been discussed in detail by Kerker (1969). A scattered wave is generated

whenever a plane wave is incident upon a particle possessing a discrete boundary and a

refractive index different from the surrounding medium.

In spherical co-ordinates the wave equation can be described as

[1 Or2 8 + 1 8 sinO 8 + 1 2 + k = 0 (3.1)
rr2r r r2 siniO 0 0 r2 sin2 O(p2

The solutions to this equation are the Hertz- Debye potentials which can be

obtained by the method of separation of variables as follows:

V = R(r)O(9)D((p) (3.2)

Each of these functions satisfies the following ordinary differential equations:

d2rR(r) + [k2 n(n+)] rR(r) =0 (3.3)
dr2 2

1 d (sinO d0(_)) + [n(n+l) m2 ] 0(0) = 0 (3.4)
sinO dO dO sin20

d2Dj() + m2((P) = 0 (3.5)
d(p2

where n and m are integers.

The solutions of equation 3.3 are the Riccati Bessel functions defined as

n(kr) = (tkr/2) 2 Jn +12 (kr) (3.6)

(kr) = -(tkr/2) / Nn + 1 (kr)

where Jn + 12 (kr) and Nn + 12 (kr) are the half integer order Bessel and Neumann functions.

The solutions of equation 3.4 are the associated Legendre polynomials given by

0 = Pn(m)(cos) (3.7)

The solutions to 3.5 are the sin(myp) and cos(mp).









The general solution of the scalar wave equation (3.1) (the Hertz -Debye

potentials) can be obtained from a linear superposition of all of the particular solutions.

The Hertz Debye potentials represent the solution for the incident wave, the scattered

wave and the wave inside the particle. Only the Hertz Debye potentials for the scattered

wave are discussed here. The Hertz Debye potentials for the scattered wave can be

expressed in terms of an infinite series and are called the angular intensity distribution

functions Ii and 12. I1 and 12 are proportional to the perpendicular polarized and parallel

polarized components of the light scattered at an angle 0 respectively.

n=oo
11 = I Z 2n+l (anrnC(cos0)+ bnTn(cos0))|2 (3.8)
n=l n+1

n=oo
12 = I Z 2n+l (anTn(cos0) + bn7n(cos0))|2 (3.9)
n=l n+1

where 7,(cos0) = PnlcosO) (3.10)
sinO

and n((cos0) = d P(l)(cos0)
dO

The constants an and bn are obtained from the boundary conditions that the tangential

components of the electric and magnetic field of the incident wave are continuous over

the entire surface of the sphere. If the number density (N) of the particle is known then

the Mie scattering cross section for a single particle size can be defined as

oMie = )2 N(11+I2) (3.11)
872

The Mie scattering cross section is an indication of the intensity of light that would be

scattered from a particle of arbitrary size.









Calculation of intensity distribution functions Ii and 12

From equations (3.8) and (3.9) it can be seen that the intensity distribution

functions Ii and I2 are in terms of complex infinite series and involve the calculation of

the Legendre polynomials for every value of n. Also the constants an and bn involve the

calculation ofRiccati Bessel functions for every value ofn. As stated in Chapter 2,

subroutines for the calculation of Iand 12 are available. In this study one such program

developed by the Oregon Medical Laser Center is used. The input parameters are the

incident wavelength, particle size and refractive index. McCartney (1979) states that the

refractive index of crystalline haze aerosols can be assumed to have a value of 1.33. The

aerosols are assumed to be dielectric. This value is used throughout this study. It is to be

noted that the angular intensity distribution functions depend on the refractive index and

the value of 1.33 imposes a limiting condition since it does not take into account dry

particles like soot. The values of I1 and I2 obtained from this subroutine are compared

with published values of I and I2 in McCartney (1979). The comparison is done for five

combinations of incident wavelength, refractive index and particle size. A typical

comparison is shown in figures 3-2 and 3-3. Size parameter gives the relation between

the size of the particle and the wavelength of incident light and is defined as

a = 27a (3.12)


Figure 3-1 shows the values of I and I2 obtained as a function of scattering angle

for a size parameter (a) of 0.5 (particle radius of 0.044 microns) and refractive index of

sphere of 1.33. Using the program and figure 3-2 is obtained from McCartney for the

same input parameters. The two figures are identical, establishing the accuracy of the

subroutine.











8.00E-04

6.00E-04 .
\\ / -- perpendicular
4.00E-04
--- unpolarized
2.00E-04 parallel
parallel
0.OOE+00
0000000000
Nl C CO C N T COO

Observation angle (deg)



Figure 3-2. Ii (perpendicular) and I2 (parallel) intensity distribution functions for size
parameter =5, and refractive index =1.33 obtained from the interactive
webpage.








S a 0.5
2 r = 0.044 nm


10-4 I l Il
0 20 40 60 80 100 120 140 160 180
Observation angle, 0 (deg)


Figure 3-3. Ii (perpendicular) and I2 (parallel) intensity distribution functions for size
parameter =5, and refractive index =1.33 from McCartney.

Rayleigh Theory

The Mie solution is a complex mathematical solution. For particles of size much

less than the wavelength of incident light, the Mie series solution converges in one term

and is called the Rayleigh theory. The Rayleigh theory was originally put forth by Lord

Rayleigh (J.W. Strutt, third Baron of Rayleigh) in 1871, long before the Mie solution was

developed (1908). Later on it was proved that the Rayleigh theory is actually a single

term simplification of the Mie theory. Lord Rayleigh put forth the Rayleigh theory

principally to explain the blue color of the sky. He assumed that the particles were









spherical, isotropic, much smaller than the wavelength of incident light and denser than

the surrounding medium. Through straightforward dimensional reasoning he arrived at

the conclusion that scattering varies directly with the square of the particle volume and

inversely as the fourth power of the wavelength of incident light.

The scattering by gas molecules is in the Rayleigh regime because of the small size of

the molecules. McCartney (1976) gives a good physical description of Rayleigh

scattering. He states that for the Rayleigh theory to be applicable, a 1 or the particle

radius should be at least 0.03 times less than the wavelength of incident light. The

following are the assumptions about the molecules for Rayleigh scattering.

1. The molecules are non ionized implying that there is no overall charge over the
entire molecule. This means that the molecule does not experience a net force in
an electric field.
2. The molecules are non polar meaning that the electronic charge is uniformly
distributed over the shell and could be treated to be at the center. Even though the
polar assumption is made in the original theory, the Rayleigh theory is valid for
non-polar particles as well.
3. The molecule is isotropic implying that the forces experienced within the
molecule are balanced.
4. The molecule is linear which means that the binding forces within the molecule
obey Hooke's law.
5. The molecules are lightly damped meaning that the amplitude of oscillation does
not become too large at frequencies near resonance.

These assumptions are applicable to ordinary gas molecules like nitrogen and helium.

Based on these assumptions McCartney (1976) derives the differential Rayleigh

scattering cross section for perpendicular polarized scattered light as

oRayleigh = 1285 a6 n2 1 (3.13)
34 n2 + 2

As seen from equation (3.13) the Rayleigh scattering cross section is independent of the

scattering angle and has an inverse fourth power dependence on the wavelength of

incident light. It also depends on the refractive index (n) of the particle.









Photon arrival rate calculations for Rayleigh and Mie theory

Knowing the Rayleigh and Mie scattering cross sections the intensity of scattered

light can be calculated for a given set of experimental constants. Both the Rayleigh and

Mie scattering cross sections are applicable for an individual molecule and are not

functions of the gas number density N assuming independent scattering. For a given

volume of a gas the intensity of scattered light is linearly proportional to the gas number

density. The scattering from multiple molecules in a given volume can be considered to

be additive, independent and incoherent because of the random spacing and thermal

motion of the gas molecules.

Thus for an incident beam of energy Io ,scattered from a control volume with

molecular number density N, the intensity of the scattered beam is proportional to the

scattering cross section of the molecule, the number density and the energy of incident

beam

Iscat = C(IooN) (3.14)

The proportionality constant is defined by the scattering geometry, namely the

solid angle of the collection optics (Q), control volume (dV) and optical efficiency of the

collection optics (r). In this study, the scattered beam was collected using a 60 mm

diameter lens at a distance of 250 mm from the scattering volume which define the solid

angle. The control volume depends on the angle at which the scattered beam is collected

and is discussed in chapter 4. The optical efficiency was assumed to be 90% for each

optical surface the scattered beam is passed through. Thus for Rayleigh scattering the

intensity of scattered light from a control volume containing a mixture of gases is given

by


IRayleigh (Io)(l)(dV)(Q)1(NGRayleigh)i


(3.15)









And scattered intensity for Mie scattering is given by

Imie = (Io)(rl)(dV)(Q)X(NGMie)i (3.16)

Knowing the Rayleigh and Mie scattered intensities, the total scattered intensity received

at the collection lens can be calculated as

Itotal = IRayleigh + IMie (3.17)

Scattering Cross Section Considerations

In this study, pure helium and a mixture of 20% helium and 80% nitrogen are

used. The scattering cross section of helium is 0.015 times the scattering cross section of

air and the scattering cross section of pure hydrogen is 0.23 times the scattering cross

section of air. In order to match the scattering cross section of hydrogen, a mixture of

20% helium and 80% nitrogen is used. The differential scattering cross sections of

hydrogen, helium and nitrogen are listed at a wavelength of 532 nm in table 3-1.

Table 3-1. Scattering cross section at a wavelength of 532 nm.
Gas Scattering Cross Section (a) (m2/sr)

Air (Nitrogen) 8.16E-32

Hydrogen 1.88E-32

Helium 1.22E-33


Knowing these values, the mixture concentration of 20% helium and 80% nitrogen are

obtained using the following relation (x = % helium)

Hydrogen = X Ghelium + (1-X) Gnitrogen. (3.18)

Buoyant Jet Theory

Buoyancy forces arise in a jet if the density of the flow fluid is different from the

density of the surrounding fluid. In the absence of buoyancy forces the jet is called a non

buoyant jet. In the other limiting case when the buoyancy force dominates the flow, the









jet is called a plume. Thus the non buoyant jet has about the same density as the

surrounding environment so that the buoyancy forces are absent, whereas a pure plume

has no initial momentum. The densities of both flow fluids used for the experiments- pure

helium and the mixture of helium and nitrogen are different from the density of the

surrounding fluid (ambient air). The Froude number is used to characterize whether a jet

is a non buoyant jet, a buoyant jet or a plume-Chen and Rodi (1980). The Froude number

is the ratio of inertial forces to buoyancy forces and is defined as

Fr = Re/Gr2 (3.19)

Reynolds number is the ratio of the inertial forces to the viscous forces and can be written

as

Re = vd (3.20)


The Grashof number (G) is defined as

g(f2ao)D3 (3.21)
po)

And it is the ratio of buoyant to viscous forces.

In a non buoyant jet, only the Reynolds number is of influence (Fr=oo) whereas in

pure plumes only the Grashof number is dominant (Fr=0). For an axisymmetric vertical

jet, the limiting condition for a buoyant jet is defined in Chen and Rodi as follows

0.5 < Fr-1/2 (po/pa-1/4 (z/D) < 5 (3.22)

Froude Number Calculation

Two different nozzle diameters of 1/4" and 1/2" are used. Also two flow fluids (pure

helium and mixture of 20% helium and 80% nitrogen) are used. Four different cases are

considered: 12" diameter nozzle with pure helium, 12" diameter nozzle with a mixture of

20% helium and 80% nitrogen, 14" diameter nozzle with pure helium and 14" diameter









nozzle for a mixture of 20% helium and 80% nitrogen. The measurements are taken for

four downstream distances of 2, 4, 6, and 8 nozzle diameters. The Reynolds number is

chosen as 500 for each case.

The criterion for buoyant jet (equation 3.21) is tested for all four combinations of

nozzle diameters and flow fluid and at all four downstream distances. Table 3-2 lists the

values of Froude numbers for all four combinations of nozzle diameters and flow fluid

and for the two limiting cases of 2 and 8 nozzle diameters downstream.

Table 3-2. Froude number calculations show that the criteria for buoyant jet is met for all
combinations of flow fluids, nozzle diameters and downstream distances
Cases Reynolds Froude 0.5 < Fr-1/2(o/a)-1/4z/D <5
Number(Re) Number(Fr) 2 nozzle 8 nozzle
2 nozzle 8 nozzle
diameters diameters
1. 1/2 "; He 500 36.5 0.521 2.08
2. 1/2"; 20%He, 500 64.5 0.54 2.16
80%N2
3. /4"; He 500 292.5 0.88 3.52
4. /4 "; 20%He, 500 516.5 0.94 3.76
80%N2

Buoyant Jet Profiles and Concentration Variation

Figure 3-4 shows the instantaneous and time averaged profiles of a buoyant jet.

The jet centerline is characterized by a potential core near the nozzle exit. Inside the

potential core, the concentration of the flow fluid is 100%. The shear layers define the jet

spread angle (P).The edge of the shear layers mark the boundary of the time averaged

profile. The concentration of the flow fluid varies from a 100% at the jet centerline to 0

% at the edge of the shear layers. Chen and Rodi (1980) have listed the spread angles of

non- isothermal jets. In this study a spread angle of 130 is found for a vertical round

buoyant jet.









Chen and Rodi (1980) summarize empirical data predicting the axial spread of an

axisymmetric vertical buoyant jet. The concentration at any point in the shear layer of a

buoyant jet can be calculated using the following relation.

C- Ca = exp [-Ko(r/z)2 ] (3.23)
Co- Ca


tme Averaged Profile

Shear layer


Instantaneous
profile




Potential
core


Black cover


Figure 3-4. Instantaneous and time averaged profiles of a typical buoyant jet.

The constant Kc is related to the jet spread angle 0 as

Kc = In 2/(tanp/2)2

So, for ajet spread angle of 130 Kc = 53.4


(3.24)










For a vertical buoyant jet, the centerline concentration (Cc ) is found from the

dimensionless density (C ) using the following equation

Co- Ca= C* = 4.4Fr l/(po/pa) -7/16 (z/D)-5/4
Cci- Ca


(3.25)


Using this value of Kc the concentration of the flow fluid at any point in the flow

can be calculated using equation 3.22.

For both the 1/2" diameter nozzle and the /4" diameter nozzle, C- Ca/Ccl- Ca is

plotted as a function of radial distance (r) for a downstream distance (z) of 2 nozzle

diameters for each case as seen in figure 3-5.


Figure 3-5. Concentration variation with r for z = 2 is Gaussian in nature for both nozzle
diameters of 14 and /2".


1.2

1

0.8

r 0.6

0.4

0.2

0


--1/4 inch nozzle
--1/2 inch nozzle


So r- q-t .- Wo LON C 0 o O I%- I- W- o
S.- ri Ci i 4 4 ..6 i 6 r
r














CHAPTER 4
EXPERIMENTAL SCHEME

Collection at 90 and Backscatter

The goal of the project is to detect the change in intensity of scattered light in the

presence of hydrogen. Rayleigh scattering is independent of the angle at which the

scattered light is collected but the Mie signal depends on the scattering angle. Initially,

the collection optics were set at 900 to the incident beam and the measurements were

focused on a single point of the beam as seen in figure 4-1. An advantage of this optical

configuration is that the glare from the incident beam on the scattered signal is minimum

at this angle since the minimum incident beam area is visible to the photomultiplier tube.

For field measurements since the exact position of the leak could be at any distance

from the laser, the drawback with a 900 scattering scheme would be that the collection

optics consisting of the collecting, focusing lenses, filter, photomultiplier tube and the

digital oscilloscope would have to be moved depending on the position of the suspected

leak. It would be ideal to use a scheme in which the collection optics could be kept

stationary. This can be done by using a backscatter scheme in which the incident light is

passed between two 4" (101.6mm) square mirrors and the scattered light is collected at a

1800 using the two mirrors. The mirrors are 90% reflective at a wavelength of 532 nm.

The backscatter scheme is shown in figure 4-2. For the backscatter scheme, since the

angle of observation is a 1800, the control volume is defined by the beam area and the

pulse width of 5 ns (1.5m). This leads to a fall in the signal to noise ratio as the leak

occupies only 0.6% of the control volume as discussed in Chapter 5.








Beam dump


---


40 4- Collecting lens


4- Focusing lens


I -Band pass filter

4- Photomultiplier tube


Figure 4-1. Experimental scheme for collection of scattered light at 900
The back scattering scheme uses the same set of collection optics as that for the 900

scattering scheme except that the 900 scheme uses a 60 mm collecting lens. From ray

tracing it is found that the beam divergence angle of the scattered beam arriving at the


Laser


Nozzle









mirrors was 0.40 and so the scattered rays reflected from the mirrors are effectively

collimated and could be focused on the photomultiplier tube.


I4-


F----


Beam dump


Nozzle


Focusing lens


Band pass filter


4- Photomultiplier tube


Figure 4-2. Experimental scheme for collection of scattered light at a 1800 (back scatter)

The following components constitute the optical set up shown in figures 4.1 and


Laser


Mirrors









Laser. Initially the experimentation was done using an argon ion laser operated

on the 488 nm wavelength. The laser power was set at 3 W and the beam diameter was

1mm with a beam divergence angle of 0.060. The argon ion laser is a continuous beam

low power laser. In order to amplify the scattered signal and for higher temporal

resolution a pulsed Nd:YAG laser was also used. The laser power is 200 mJ/pulse at a

wavelength of 532 nm. The pulse width was 5 nanoseconds and the frequency is 10 Hz.

The beam diameter is 6 mm with a beam divergence angle of 1.1. Since the beam

diameter was larger than the Argon-Ion laser, the Nd:YAG laser defined a larger control

volume than the Argon-Ion laser. Thus two different power lasers at two wavelengths are

used for the experiments.

Nozzle. The leak was simulated using a nozzle. The laser beam was passed

directly over the nozzle. The nozzle is placed at a distance of 8 feet (20.32 cm) from the

laser for the 900 scattering scheme. Using the beam divergence angle, the beam diameter

over the nozzle was calculated to be 1.1 mm for the Argon ion laser and 8 mm for the

pulsed Nd:YAG laser. In order to analyze the effect of the relative size of the beam and

leak, two different nozzle diameters are used. For initial measurements using the argon

ion laser a 1/2" (12.6mm) nozzle was used. For the pulsed laser a /4 (6.3mm) diameter

nozzle was used. Thus for the argon ion laser, the beam diameter is 11.5 times less than

the leak diameter whereas for the Nd:YAG laser the beam diameter is 1.25 times more

than the leak diameter. The back scattering scheme uses the pulsed Nd:YAG laser with

the 14 diameter nozzle. The nozzle is placed at a distance of 20 feet (50.8 cm) from the

laser and the beam diameter is 10 mm over the nozzle. The Reynolds number of the leak

is set at 500 for both nozzle diameters and the Froude number was calculated as









discussed in chapter 3 and presented in table 3.1. This combination of Reynolds and

Froude number ensured that the leak is a buoyant jet. The nozzle is covered with a black

felt drape to minimize glare. The mass flow rate of pure helium and the mixture of

helium and nitrogen is monitored using mass flow controllers.

Nozzle mounting. Three micrometer traverses are used for mounting the nozzle

for three dimensional motion. Each traverse has a least count of 0.05 mm. Figure 4-3

shows the schematic of the mounting used. This allowed the measurements to be taken at

different downstream locations.



-r Nozzle

y z








Traverse 3 Y


Traverse 2
Traverse 1



Figure 4-3. Nozzle mounting showing three dimensional motion capability.

Beam dump. The incident laser beam was trapped using a beam dump. The beam dump

was placed at a distance of 20 feet from the nozzle to minimize glare.

Collection optics. The scattered beam was collected using a set of collection

optics which consisted of a collecting lens, focusing lens, band pass filter and a









photomultiplier tube. The collection optics were covered with a black felt drape in order

to eliminate additional glare.

Collecting lens. The collecting lens is a 60 mm diameter lens and has a focal

length of 250 mm. As seen from figure 4-1 the focal point of the lens coincides with the

nozzle position so that scattered light collected by the lens is collimated. As seen from

figure 4-2 the collection lens was not used for the backscattering geometry because the

scattered beam reflected from the two mirrors was collimated.

Focusing lens. The focusing lens is a 60 mm diameter lens and had a focal length

of 124 mm. The collimated beam from the collecting lens is focused on the

Photomultiplier tube using the focusing lens.

Band pass filter. For the Nd:YAG laser, the band pass filter is a 532 nm line

filter that blocks background light at other wavelengths from reaching the photomultiplier

tube. The band pass filter was kept at a distance of 3 mm from the Photomultiplier tube.

Photomultiplier tube. The scattered beam is focused on the Photomultiplier tube.

The Photomultiplier tube is a Hamammatsu model number HC 120-01 tube and has a

built in amplifier with adjustable gain. It has a rise time of 2 ns and a bandwidth of 23

Khz. This means that the photomultiplier tube can distinguish between two signals that

are 44 microseconds apart. Since the frequency of the pulse laser is 10 Hz the interval

between two consecutive pulses is almost Ims. Hence for a 900 scattering geometry, the

photomultiplier tube can distinguish between two consecutive pulses. From the

manufacturer's specifications the calibration constant of the photomultiplier is found to

be 121 V/nW which allows the conversion of the voltage recorded on the photomultiplier

tube into power. The Photomultiplier tube has a 0.015 mm optical slit mounted on it to










minimize the intensity of scattered light. The Photomultiplier tube converts the photonic

signal to electrical voltage which is then sent to a high speed digital oscilloscope. It is

important to note that even though the photomultipliers are considered to be highly linear

devices, the linearity generally occurs over a lesser range for the pulsed Nd:YAG laser. (X

= 532 nm) at varying flash lamp discharge voltage. Figure 4-4 displays the

photomultiplier tube voltage as a function of varying flash lamp discharge voltage.


680
660
660 R2 =0.9931
640-
620
600 -* Series1
580- Linear (Series1)
560
540
520
500
0.9 1 1.1 1.2 1.3 1.4



Figure 4-3. Photomultiplier tube linearity tested as a function of flash lamp voltage

High Speed Digital Oscilloscope. The photomultiplier tube signal is recorded on a

high speed digital oscilloscope (LeCroy). It has two channel simultaneous data

acquisition capabilities. It is triggered externally using the pulsed laser. The trigger time

is 180 ns which means that the laser sends an electric signal to the oscilloscope exactly

180 ns before it fires the pulse so that the oscilloscope can be set to capture the scattered

signal. The oscilloscope acquires data over a time period of 50 microseconds. The

measurements are recorded and readout on a spreadsheet.

Control Volume. For the 900 scheme, the control volume is defined by the beam

diameter and the length of the control volume is defined by the width of the optical slit









(150 microns).

Back Scatter Considerations

As previously stated the back scattering scheme is used to test the feasibility of the

technique for field measurements. An important consideration for field measurements is

the ability to detect the leak over longer distances. Hence the leak is created by placing

the nozzle at a distance of 20 feet (50.8 cm) the laser beam. The beam dump is placed at a

distance of 10 feet (25.4 cm) from the nozzle. The control volume is defined by the beam

diameter and the length of the control volume for this case is defined by the pulse width

(5nanoseconds =1.5m)

Data Recording Procedure

The measurements were done at four different downstream locations of 2, 4, 6 and

8 nozzle diameters for the pulsed Nd:YAG laser and two downstream locations of 2 and

6 nozzle diameters for the argon ion laser. For each downstream distance the nozzle was

traversed along the direction of the beam using the micrometer traverse as shown in

figure 4-3. The steps in which the nozzle was traversed was calculated from the spread

angle of the jet as seen in figure 4-4. The distances la, 2b, 3c and 4d varied depending on

the nozzle diameters (1/4" or 1/2"). This was done so that the measurements done at all four

downstream distances could be graphed on the same scale of r/z.













d 4


c 3


b 2 8d r
1 6d y
4d
a 14
S2d
6.50



5 nozzle





Figure 4-4. Calculation of nozzle traverse distances for downstream distances of 2,
4, 6 and 8 nozzle diameters using jet spread angle of 130.














CHAPTER 5
RESULTS AND DISCUSSION

Comparison of Theoretical and Experimental Photon Arrival Rate

This section discusses how the theoretical and experimental photon arrival rates

compare. In chapter 3 the equations for calculating the Rayleigh photon arrival rate

(equation 3.15) and Mie photon arrival rate (equation 3.16) are presented. The total

theoretical photon arrival rate is calculated as a sum of the Rayleigh and Mie photon

arrival rates (equation 3.17).

Calculation of Theoretical Rayleigh Photon Arrival Rate.

In the presence of helium, the Rayleigh photon arrival rate can be calculated by

modifying equation 3.15 as follows. The percent helium (x) was varied from 0 to 100 and

the resulting photon arrival rate is shown in figure 5.1.

IRayleigh = (Io)(rl)(dV)(Q)N(xHe + (1-x) Gair) (5.1)

Io = 7.07E+6mj/m2-pulse = 1.88E22 photons/ m2-pulse(Nd:YAG laser);

3.8E+6 W/ m2 (Argon-Ion laser)

f = (0.9)5

dV = 1.2 E-8m3 (900 scatter); 1.2E-4m3 (backscatter)

Q = t(60)2/(250)2 sr (900 scatter); (2)(101.6)2/(12100)2 sr (backscatter)

N = 2.2E25 molecules/m3

OHe= 1.22E-33 m2/sr

Gair = 8.16E -32 m2/sr











-_ 8.20E+09
7.20E+09
S6.20E+09 Rayleigh photon
0 5.20E+09- arrival rate
S9 Mie photon arrival
S4.20E+09
IM rate
S3.20E+09 total photon arrival
rate
'I 2.20E+09 rate
| 1.20E+09
=. 2.00E+08
0 10 20 30 40 50 60 70 80 90 100
% Helium


Figure 5-1. Theoretical photon arrival rate calculations show that Rayleigh signal is
higher than Mie signal.

Calculation of Theoretical Mie Photon Arrival Rate

Equation 3.16 is used for the calculation of the Mie photon arrival rate.

IMie = Io)(l)(dV)(Q)1(N, Mie)i (3.16)

The two unknowns in this equation are Ni and (oMie)i

The calculation of (oMie)i involves the use of the intensity distribution functions II

and 12 If the particle size is known, these functions can be calculated for a give

wavelength of incident light using the subroutine as discussed in Chapter 3. Two size

distributions were used to determine the size of particles in the ambient air and also the

number density of particles of a particular size.

Distribution 1 uses the data from a LASAIR II particle counter. Table 5-1 shows a

typical output of the particle counter data.

The sampling is done in the laboratory for a sampling time of 1 minute and the

volume of particles sampled over this period is 1 cubic feet. The particle size is given in

column 1. Columns 2 and 3 give the lower and upper limits of the number of particles of









the corresponding size. An average of columns 2 and 3 is taken. Thus using the LASAIR

II data, the number density-particles per m3 (N i) of a particular size are known. For each

particle of size of 0.3, 0.5, 1, 5, 10, 25 microns the Mie scattering subroutines are used to

calculate II and 12 at a wavelength of 532 nm for the pulsed Nd:YAG laser. Knowing II

and 12 ,oMie is calculated using equation 3.11 and the Mie scattered intensity using

equation 3.16. To account for the presence of helium equation 3.16 was modified as

lMie= IoTllQNGMie(1-xHe) (5.2)

Table 5-1. Particle counter data show the particle distribution in the lab.

Number of particles/ft3 Number of particles/ft3
Particle size (microns) (lower limit) (upper limit)
(lower limit) (upper limit)
0.3 25268 27272
0.5 7864 9222
1 1164 1298
5 100 104
10 12 12
25 1 1


For distribution 2 the typical maritime aerosol distribution in McCartney (1969) is

used. Figure 5-2 shows particle distribution for stratospheric dust particles or hailstones

(model H), continental aerosols (model L) and maritime aerosols (model M). The

maritime aerosol distribution (model M) is chosen since it is appropriate for Cape

Canaveral.

The number density per radius interval n(r) for this distribution is calculated using

the following fit (McCartney)

n(r) = ar" exp(-br7) (5.3)

Where the constants a, b ,a, y have the following empirically determined values

a = 5333











b = 8.9443


a=l


y =1/2.


io3 ----------- --





102



2

















H L M -
102


(3.








1071 1






0.01 0.1 1.0
Particle radius (pm)


Figure 5-2. Model M shows maritime distribution of aerosols which is used to calculate
the particle size distribution.(McCartney 1979, page 139)



Using the values of particle size (r) ranging from 0 to 25 microns, and the above


values of the constants, the model M (log-log scale) was duplicated on a regular scale as


shown in figure 5-3.











350

300

o 250
200 -
S200 Model M
S150
o
2 100

M 50 -
0

0.1 1 10 100
particle size


Figure 5-3. Model M duplicated for calculating the number density using radius interval
on a log-normal scale.

The number density is calculated for the same particle radii as the LASAIR II data.

(i = 0.3, 0.5, 1, 5, 10 and 25 microns) by integrating the area under the curve shown in

figure 5-2 using following equation. The interval (i) to (i+1) represents the difference

between the two consecutive particle radii

i=6
Ni = 0.5(n(r)i + n(r)i+1)I (5.4)
i=l

The values of number density -Ni (particles/m3) obtained from equation are

compared with the values of Ni from the particle counter (Table 5.1). Figure 5-4 shows

this comparison. As seen from the figure the particle distribution for maritime and lab

aerosols is similar.

For distribution 2 since the number density and the particle radius are known

(equation 5.4) the Mie scattering cross section and the intensity of Mie scattered signal is

calculated using the same approach as in distribution 1.











800

700

600
= 500

S400

E 300

Z 200
100

0
0.1


--McCartney
* Lab


1 10
particle size


Figure. 5-4. Comparison of number density of maritime and lab aerosols shows similarity

Figure 5-5 shows the comparison between the Mie photon arrival rates for the two

distributions. The value of IO used is that for the pulsed Nd:YAG laser.


2.10E+09


1.60E+09


1.10E+09


6.00E+08


1.00E+08


- Maritime distribution
- lab data


20 40 60
% Helium


80 100


Figure 5-5. Effect of maritime and lab aerosol distribution on Mie scattered intensity
shows that both signals are of the same order of magnitude.


As seen from the graph, both signals are of the same order of magnitude. The

maximum difference between the two signals (55%) is for the case of 0% helium since all


"-
CL




o0
I









Mie scattering particles have been displaced, and no ambient air is in the control volume.

Both signals tend to zero as the helium concentration approaches 100%. This figure

shows that the Mie signal would be of the same order and smaller for maritime field

measurements as that for laboratory measurements.

Calculation of Total Theoretical Photon Arrival Rate

For the calculation of IMie the data from the particle counter is used since it

represents aerosol distribution for the experimental conditions. Knowing IRayleigh and

IMie, the total theoretical photon arrival rate is calculated using equation 3.17. Figure 5-1

shows the variation of Rayleigh, Mie and total photon arrival rate with percent helium.

The value of IO used here is for the pulsed Nd:YAG laser.

An important result of the theoretical study is that the Mie scattered signal is lesser

than the Rayleigh scattered signal. Initially it was reasoned that the Mie scatters would

augment the scattered signal since in the presence of helium the total signal would fall

due to reduction in Mie signal. This study shows that although this factor is present it

influences the total scattered signal to a lesser degree.

Calculation of Experimental Photon Arrival Rate

The voltage as a function of time waveform obtained on the oscilloscope represents

the total scattered intensity recorded at the photomultiplier tube per pulse.

Figure 5-6 shows a typical waveform of a burst seen on the oscilloscope. The

waveform is recorded at a downstream distance of 4 nozzle diameters with no flow fluid.

Integrating this waveform using equation 5.5 gives the total scattered intensity per

pulse (VPMT)

i=100
VPMT = 0.5(Vi +Vi+l)(0.1) (5.5)
i=0










where (i) represents the time scale from 0 to 100 microseconds varied in steps of 0.1

each.


0.7
0.6

0.5 I

0.4
0.3 -- waveform

S 0.2

0.1 -


0 10 20 30 40 50 60 70 80 90
-0.1
time microsecondss)



Figure 5-6. Typical waveform of a burst seen on the oscilloscope (Downstream distance
of 4 nozzle diameters, no flow fluid)

The Photomultiplier tube calibration constant (CPMT) at the wavelength of 532

nm is found to be 121 V/nW from the manufacturers specifications. The measurements

are done using the pulsed ND:YAG laser at 6 different helium concentrations of 0, 20,

40, 60 80 and 100% using the /4" diameter nozzle. As discussed in buoyant jet theory

(Figure 3-5) the flow fluid (helium) concentration can be predicted in the shear layer for a

combination of downstream distances and radial distance (r/z). The downstream distance

(z) is fixed at 2 nozzle diameters. From equation 3.23 it is seen that for a fixed value of z,

the radial distance (r) can be calculated if the concentration C is known since the

centerline concentration of the flow fluid (Ccl) is known using equation 3.25 and the

concentration of flow fluid (Ca) in the ambient is 0%.

C- Ca = exp [-Ko(r/z)2 ] (3.23)
Ccl- Ca









Thus for 6 different values of C (0, 20, 40, 60, 80 and 100), the measurements are

made for the corresponding values of radial distance(r) obtained from equation 3.23.

Figure 5-7 shows the values of radial distance r where the measurements are made for

each value of C.





Concentration
profile


Point of
measurement

z=2
Shear layer








Figure 5-7. Figure shows points in shear layer where measurements are made
corresponding to each value of C using pulsed Nd:YAG laser and /4" nozzle at a
downstream distance of 2 nozzle diameters. Re = 500; Fr = 290.

For each measurement the integrated area under the voltage- time curve on the

oscilloscope represents the total scattered signal per burst. Equation 5.6 is used to convert

the voltage recorded for each measurement into scattered signal in photons per pulse.

experimental= VtPMTX/CPMThc (5.6)

Figure 5-8 shows the comparison of the experimental and theoretical photon arrival

rates for varying percentages of helium.






41



@- 9.00E+09
8.00E+09
S8.E+09 R2 = 0.9978
a 7.00E+09 -
0 0 theoretical photon
6.00E+09 arrival rate
S5E9 experimental photon
5.00E+09 -
5 Arrival rate
F 4.00E+09 Linear (experimental
'E 3.E+09 photon arrival rate)
2.00E+09
=C 1.00E+09
1 .0 0 E + 0 9 . . ..----
0 10 20 30 40 50 60 70 80 90100
% helium


Figure 5-8. Comparison of experimental and theoretical photon arrival rates.

The experimental and theoretical photon arrival rates are of the same order of

magnitude with a maximum error of 57.3% for the case of 100% helium and a minimum

error of 11.3% for the case of 0% helium. A linear regression of the experimental photon

arrival rate gives a coefficient of 0.99 indicating a constant additional factors)

contributing to the error independent of percent helium. This constant error can be

attributed to 1.Background glare, which is at the same wavelength as that of scattered

signal. 2. Deviation of optical efficiency of each collection surface from the assumed

value of 90%. 3. Ambient air in control volume at jet edges.

Data Analysis Techniques

As previously stated for each burst the scattered signal from the photomultiplier

tube is recorded as a voltage-time curve on the oscilloscope. Two techniques of analyzing

the recorded voltage are considered. The Nd:YAG pulse laser with the 14" nozzle is used

for both techniques and the flow fluid is pure helium for both cases.










Integrated area method

Initially a set of 1000 data points per burst are captured from the oscilloscope and

the integrated area under the voltage as a function of time curve is computed. For the

measurements, the downstream distance is 2 nozzle diameters, Reynolds number is 500

and Froude number is 290. The measurements are done in the shear layer of the leak at a

radial position corresponding to 60% helium concentration as shown in figure 5-7. This is

because the maximum variation of recorded voltage is expected to be in the shear layer

edge since the intermittency of the turbulence is maximum.

This procedure was repeated for a set of pulses at the same nozzle position shown

in figure 5-7 until the areas converged. Figure 5-9 shows the convergence studies for the

area.


3 -
1
2-


> normalizd running
S0 average of area
S-1 6 7 8 normalized inidvidual
area
> -2-

-3

-4
pulse number



Figure 5-9. Convergence studies of normalized area and averaged area shows that the
area converged in 10 pulses.

Series 1 represents the running average of the integrated area normalized with

respect to the mean of 10 pulses. As seen from the graph, for a measurement in the shear

layer a set of 10 pulses are enough for convergence. The maximum percent variation of







43


any individual area from the mean is 3% and the maximum percent variation of the

running average of area from the mean is 2.6%.

Peak Voltage Method

Two studies are undertaken to validate the use of peak voltage rather than

integrated area as a repeatable and reproducible data measurement technique. A

convergence study is also done to determine the number of peaks required for data

measurement. These studies are carried out using the pulsed Nd:YAG laser with the /4"

nozzle.

Study 1. For four downstream positions (z) of 2, 4, 6, and 8 nozzle diameters the

waveform is recorded along the jet centerline (r=0) as seen in Figure 5-10.


0.8
0.7
0.6
.t
: 0.5 __ z/d=2
> 0.4 i z/d=4
0
| 0.3 i \ z/d=6
> 0.2 z/d=8

0.1 -


-0.1 10 20 30 40 50 60 70 80 90
time microsecondss)



Figure 5-10. Waveform with varying glare at four downstream locations.

All four measurements are done in room air with no helium flowing through the

nozzle. In this case we expect that the Rayleigh and Mie scattering signals are constant

and the only variable in each case was the glare from the nozzle.







44


All four waveforms were normalized with the corresponding peak as shown in

figure 5.11. It is seen that all four waveforms fall on top of each other and it is impossible

to distinguish between them. A four way cross correlation analysis of the waveforms was

done using the following relation


rx-y= Xi- x)(yi-y) (5.7)

4 ((x- x)Nd)2) y-Y)Nd)2)


The cross correlation coefficient was 99.7%. The high cross correlation coefficient

supports the hypothesis that the peak voltage contains sufficient information of each

waveform.


1.2

1 -

0.8 -
--z/d=2
m 0.6 z/d=4
> 0.4 z/d=6
S, z/d=8
0.2 -
0--
0 -........ ........ .. ..... .... ..
-0.2 10 20 30 40 50 60 70 80 90 100

time microsecondss)


Figure 5-11. All four waveforms normalized with their individual peaks to
remove glare, the waveforms are indistinguishable.

Study 2. In this study, a correlation analysis of the peak voltage and the

corresponding integrated area is done for 10 pulses at the same nozzle position in the

shear layer as that used with the integrated area studies above (Figure 5.7). The flow fluid

is 100% helium and the Reynolds and Froude numbers are 500 and 290 respectively and









radial position corresponding to 60% helium concentration. The downstream distance is 2

nozzle diameters. The correlation coefficient is 99.3% which again supports the relation

between peak and area for a given pulse.

Peak Convergence Study. From the previous two studies it is established that

the peak contains all necessary information about the waveform and the peak and area are

related. The convergence study is undertaken to establish the number of pulses required

for convergence. The downstream distance is 2 nozzle diameters and the Reynolds and

Froude numbers are 500 and 290 respectively for 100% helium. The measurements are

done in the same position in the shear layer of the leak as for the previous two cases of

integrated area and comparison of integrated area and peak (Figure 5.7) (radial position

corresponding to 60% helium concentration. The average peak voltage is recorded after

the 1st, 100th, 200th, 300th, 400th and 500th pulse. Table 5.2 lists the voltage recorded

after each measurement. Column 3 of the table gives percent variation between two

consecutive values of recorded voltage.

Table 5-2. Shows that average peak voltage recorded after 300 pulses in shear layer is a
converged mean.
Pulse Number Average peak voltage (Vi) (Vi Vi-)/V
Pulse Number (Vi- -1)
(mV)
0 550
100 576 4.7%
200 564 2.1%
300 559 0.88%
400 563 0.76%
500 558 0.89%

As seen from table 5.1 the variation between average peak voltage is less than 1%

if the peak voltage was recorded after 300 pulses. Also these measurements are carried

out in the edge of the shear layer of the jet where the fluctuations in the flow are









maximum. Hence it is concluded that for any nozzle position, recording the average peak

voltage after 300 pulses is a reliable data measurement technique.

Analysis of Recorded Data

Figure 5-6 shows the comparison between the predicted (theoretical) and the

measured (experimental) photon arrival rates. As stated earlier these studies are carried

out using the pulsed Nd:YAG laser with a /4" diameter nozzle at a downstream distance

of 2 nozzle diameters. This section discusses the variation of peak voltage and standard

deviation of the recorded voltage for the following four cases:

* Argon-ion laser with a 1/2" diameter nozzle at downstream distances of 2 and 4
nozzle diameters for pure helium for 900 scattering scheme.
* Pulsed Nd:YAG laser with a /4" diameter nozzle at downstream distances of 2, 4, 6
and 8 nozzle diameters for pure helium for 900 scattering scheme.
* Pulsed Nd:YAG laser with a /4" diameter nozzle at downstream distances of 2and 4
nozzle diameters for a mixture of 20% helium and 80% nitrogen for 900 scattering
scheme.
* Pulsed Nd:YAG laser with a /4" diameter nozzle at downstream distances of 2, 6,
10 and 16 nozzle diameters for pure helium in back scatter.

The nozzle was traversed in the radial (r) direction as discussed in chapter 4 for the

900 scattering scheme and in the (y) direction for the back scatter scheme.

Case I: Argon-ion laser

Peak voltage variation

Initially the measurements were carried out using the argon-ion laser (X =488 nm)

at two downstream distances of 2 and 6 nozzle diameters. The nozzle diameter of 12" is

used with the argon-ion laser and the flow fluid is pure helium. The Reynolds number of

the leak is 500 and the Froude number is 35. the nozzle traverse distance for each

measurement at each downstream position were calculated as discussed in Chapter 3.

Three sets of measurements were done at each downstream position. Figure 5-11 shows

the average of the normalized peak for all 3 measurements. Also shown are the error bars










at both downstream locations corresponding to the standard deviation of each

measurement point. The x- axis is the nozzle traverse distance (r) in mm. As seen from

the figure, the scattered voltage reaches a minimum value of zero at the jet centerline for

both downstream distances. Also the voltage variation inside the shear layer is visible.

Hence due to the presence of helium in the shear layer, there is a fall in voltage inside the

shear layer. As the downstream distance increases, the jet spreads out and the fall occurs

over a wider radius.





*"$ 1 11E K
x]E *F




E z/d=2
z/d=6



0 4
-15 -10 -5 0 5 10 15
r (mm)


Figure 5-12. Voltage variation for Argon-Ion laser shows that there is a fall in voltage in
presence of helium; 1/2" nozzle at two downstream distances; Re =500; Fr
=35.

As seen from figure 5-12, the fall in peak voltage at the jet centerline which

corresponds to 100% helium. Also, the fall in voltage occurs only in the presence of

helium. At the ambient where there is no effect of flow fluid on the recorded voltage, the

voltage remains constant. The fall in voltage in presence of helium occurs because 1.

Helium molecules have a scattering cross section which is 0.015 times the cross section









of the surrounding air molecules. 2. Molecules of the flow fluid displace some aerosols in

their path which are Mie scatters. Hence there is a fall in the intensity of scattered light

Normalized peak voltage variation.

The raw peak voltage was normalized with the centerline voltage (Vi- Va)/(Vcl -

Va) as shown in figure 5-13. The normalized concentration profile plotted in chapter 3 is

also shown as a function of r/z From figure 5-13 it is seen that the voltage variation

follows a similar Gaussian distribution as that of well established normalized

concentration profile of a axisymmetric vertical buoyant jet.





z/d=2

z/d=6

-- normalized
S / concentration



-2.0 -1.0 0.0 1.0 2.0
r/z


Figure 5-13. Normalized peak voltage variation for argon-ion laser for pure helium; Re=
500; Fr=3.5; nozzle diameter = 1/2

Standard deviation profiles

Figure 5-14 shows the variation of the normalized standard deviation ratioed to the

centerline voltage o/(Vmax Vcl) for the downstream distance of 2 nozzle diameters The

downstream distance of 2 nozzle diameter represents the near field regime of the buoyant

jet. It is seen that inside the potential core, the standard deviation falls as expected.











25 -


20 -


15 *


S 10 -


5-


0o----
-1.40 -1.12 -0.84 -0.56 -0.28 0.00 0.28 0.56 0.84
r/z



Figure 5-14. Percent standard deviation variation for near field case showing the reduced
fluctuation in the potential core.

Figure 5-15 shows the variation of the normalized standard deviation of the data

radioed to the centerline standard deviation for the far field case after the shear layers

have coalesced.


50 -
45 -
40 -
35
30 zd=6
25-

20-
S15 ***
10
5
0
-1.40 -1.12 -0.84 -0.56 -0.28 0.00 0.28 0.56 0.84
r/z


Figure 5-15. Percent standard deviation for far field case after shear layers have
coalesced.


ed.









The percent standard deviation is above the typical maximum variation of 30%. A

possible reason for this is there is an additional factor of Mie scattering contributing to

the increased standard deviation of the recorded voltage.

Case II: Pulsed Nd:YAG laser; pure helium

Peak voltage variation.

Figure 5-16 shows the variation of raw peak voltage with respect to the nozzle

position for pure helium for the downstream distances of 2, 4, 6 and 8 nozzle diameters

for the pulsed Nd:YAG laser (X=532 nm) using the 14 nozzle. The Reynolds number is

500 and Froude number is 290. As seen from the graph, for each individual downstream

distance the voltage tends to remain constant outside the shear layer (ambient) due to

absence of helium. As observed with the argon-ion laser, the fall in voltage occurs over a

wider radius as the jet spreads out. Also the minimum voltage is recorded at the jet

centerline.








i z/d=2
0 z/d=4
-" z/d=6
z/d=8



0.7
-30 -20 -10 0 10 20 30 40
r (mm)


Figure 5-16. Voltage variation for pulsed Nd:YAG laser shows a similar profile of fall in
voltage in presence of helium; Re= 500; Fr=290; nozzle diameter = 14 "










Normalized Peak Voltage Variation

Figure 5-17 shows the variation of the normalized peak voltage for all four

downstream distances for the pulsed Nd:YAG laser for the case of pure helium. Also

shown is the theoretical normalized concentration profile plotted in chapter 3 as a

function of r/z.



\ z/d=2

Sz/d=6

z/d=6

z/d=8

Normalized
concentration

-2 -1 0 1 2
r/z


Figure 5-17. Normalized peak voltage variation for Nd:YAG laser for pure helium; Re=
500; Fr=290; nozzle diameter = /4 "

Standard deviation profiles

Figure 5-18 shows the standard deviation profiles for all four downstream distances

of 2, 4, 6 and 8 nozzle diameters. Comparing figure 5-18 with the standard deviation

profiles for the Argon-ion laser (figures 5-14 and 5-15), it is seen that the standard

deviation variation is less distinct for the Nd:YAG laser. A possible reason for this could

be the effect of the relative size of beam and nozzle (leak) diameters. The beam diameter

for the argon ion laser is 1/10th the diameter of the nozzle whereas for the pulsed laser it

was 1.2 times the nozzle diameter (Figure 5-19). This factor was an additional variance

for the pulsed laser.











20
18 -x XXx
16 X X
14 XX x *z/d=2
12 *zld=4X g L M
8 gz/d=6
8-~d
S 6- X z/d=8
4-
2
0
-1.47 -1.10 -0.74 -0.37 0.00 0.37 0.74 1.10 1.47
r/z


Figure 5-18. Standard deviation variation for Nd:YAG laser for pure helium; Re= 500;
Fr=290; nozzle diameter = 1/4 "


Laser beam

1.2mm


Nozzle -


12.6mm


Nd:YAG laser


8mm

beam
Laser beam




-Nozzle




6.3mm

Argon-ion laser


Figure 5-19. Relative size of beam and leak diameter for the Argon-ion and pulsed
Nd:YAG laser.

Case III: Pulsed Nd:YAG laser; 20%helium ,80% nitrogen

Peak Voltage Variation

Figure 5-20 shows the variation of peak voltage for a mixture of 20% helium and









80% nitrogen for a downstream distance of 2 and 4 nozzle diameters for the pulsed

Nd:YAG laser. This mixture of helium and nitrogen matches the scattering cross section

of hydrogen as discussed in Chapter 3 and hence the amount of light scattered by the

mixture is expected to be identical to that of Hydrogen. The Reynolds and Froude

number were 500 and 515 respectively.








ii z/d=2
m z/d=4





0.92 .
-15 -10 -5 0 5 10 15 20


Figure 5-20. Voltage variation for the pulsed Nd:YAG laser for the mixture of helium
and nitrogen shows that there is a fall in voltage; nozzle diameter 1" ;Re=500,
Fr = 515.

The fall in voltage from figure 5-20 is 30 mV (6%) for the downstream distance of

2 nozzle diameters. The fall in voltage for z/d=2 for the case of 100% helium is 155 mV

(30 %) as seen in figure 5-16.

Normalized peak voltage variation.

Figure 5-21 shows the normalized peak variation for the mixture at the downstream

distances of 2 and 4 nozzle diameters.

A comparison with the normalized concentration shows that the two profiles are

similar.



























Figure 5-21. Normalized peak voltage variation for Nd:YAG laser; Re= 500; Fr=515;
nozzle diameter = 1/ for a mixture of helium and nitrogen to simulate the
optical properties of nitrogen.

Standard Deviation Profiles.


vi
5 *a
H imm
mmmmmg


;M.AMim...


-1.47 -1.10 -0.74 -0.37 0.00 0.37 0.74 1.10 1.47
r/z


Figure 5-22. Percent standard deviation variation for Nd:YAG laser; Re= 500; Fr=515;
nozzle diameter = 1/ for a mixture of helium and nitrogen to simulate the
optical properties of nitrogen

The standard deviation profiles of the mixture for both downstream distances of 2

and 4 nozzle diameters are shown in figure 5-22. The standard deviation for the mixture


Sz/d=2

m z/d=4

0 4 normalized
> / concentration



-2 -1 0 1 2 3


15

10


Sz/d=2
* z/d=4









is more than the standard deviation of pure helium for the two distances. The presence of

two flow fluids (helium and nitrogen) shows in the increased standard deviation.

Measurements in Backscatter

The principal issue in backscatter is distinguishing between the scattered signal and

beam dump glare. Figure 5-23 is a schematic of the backscatter geometry represented on

a time scale. The time difference between the scattered beam from the nozzle and

reflected beam from the beam dump is approximately 20ns. Thus the photomultiplier

tube should be able to distinguish between the two signals 20 ns apart. The minimum

bandwidth of the photomultiplier tube required is 5 VMHz. It was impossible to

distinguish between the two signals using the Hammamatsu tube. (Bandwidth 23 KHz).

30.4 ns




20.32 ns




Nd:YAG laser nozzle Beam dump





Photomultiplier



Figure 5-23. Schematic of backscatter on a time basis shows separation between beam
dump glare and scattered signal from the nozzle.

The waveform seen on the oscilloscope contained both the beam dump glare and

the scattered signal. In order to distinguish between the signal and glare the










measurements with helium for a typical nozzle position was normalized with a

measurement without helium for the same nozzle position. Since the measurements were

done in backscatter, the nozzle was traversed in a direction perpendicular to that of the

beam(y-direction). Figure 5-24 shows the data in backscatter.




1.05
c 1u 1 z/d=2
S0.95 E a z/d=6
E 0.9 z/d=10
S0.85 z/d=16
0.8
S0.75
-15 -10 -5 0 5 10 5 10 15
r/z


Figure 5-24. Normalized area variation shows a reduction in scattered intensity in
presence of helium (backscatter); Nozzle diameter = 4"; Re =500; Fr = 290

There is a fall in the normalized area in the presence of helium near the jet

centerline for all downstream distances. For the case of downstream distance of 2 nozzle

diameters, the fall in normalized area is about 0.15 V (15%). For the 900 scattering

scheme for the pulsed Nd:YAG laser, the fall in voltage is approximately 30% (Figure 5-

16) and 50% for the Argon-Ion laser for the downstream case of 2 nozzle diameters for

pure helium (Figure 5-12). The control volume for the backscatter geometry is defend by

the 6mm diameter beam and the pulse width of 5 ns (1.5m) (4.29E-5m3). For the 900

scattering scheme, the control volume is defined by the 6mm diameter beam and the

0.015mm optical slit (4.29E-m3) for the Nd:YAG laser, and 1mm diameter beam and the

0.15mm optical slit for the Argon-Ion laser. (7.05E-12m3). The leak diameter for the

pulse laser is /4"whereas for the Argon-Ion laser its /2" Thus for the 900 scattering











geometry for both Argon-Ion and Nd:YAG cases, the leak occupies 100% of the control

volume whereas for the backscatter geometry the leak occupies only 0.6% of the control

volume as seen from table 5-3.

Table 5-3. Control volume to leak diameter ratio for all three cases shows that the ratio is
far less for backscatter than 900 scattering.
Geometry Nozzle Diameter (D) Control Volume(CV) CV/D (percent)
Backscatter,Nd:YAG 6.35E-3 m 4.29E-5m3 0.6
90 Nd:YAG 6.35E-3 m 4.29E-5m3 100
90 Argon-Ion 12.7E-3 m 4.29E-5m3 100

This might have lead to the lesser fall in intensity of scattered light in the presence

of helium for backscatter geometry.














CHAPTER 6
CONCLUSIONS

The primary objective of this study is to establish the feasibility of laser induced

light scattering as a leak detection technique for hydrogen. There are two primary reasons

that support this objective.

1. The fall in voltage at the centerline of the leak indicating reduced scattered

intensity both in the presence of pure helium (oHelium = 0.015 GAir) and a mixture of 20%

helium and 80% nitrogen (GMixture = GHydrogen= 0.23 GAir) 2. Standard deviation in excess

of 30% for pure helium (argon ion laser). Both of these were due to the reduced intensity

of Rayleigh scattering by helium molecules.

The theoretical studies of Mie scattered intensity show that the Mie signal is the

same order of magnitude for the laboratory and maritime particle distributions. This

result is important for field measurements as the effect of Mie scattering on the total

signal would be approximately the same. Initially it was thought that the fall in voltage

would be amplified due to the Mie scatters. However, from the theoretical study it was

seen that Mie signal is less than the Rayleigh signal. Hence the lack of Mie scatters in the

control volume reduces the fall in voltage in the presence of Rayleigh scattering due to

helium and nitrogen molecules.

Concentration measurements in the presence of Mie scattering have been

successfully done in the lab environment.The backscattering scheme is used principally

to test the feasibility of this technique for field measurements. Since for laboratory

measurements the scattered signal from the photomultiplier tube and the reflection from









the beam dump are only 40 ns apart, it was impossible to distinguish between the two

signals for the photomultiplier tube used for the experiments. This lack of temporal

discrimination severely limits the overall signal to noise ratio for this configuration. The

signal to noise ratio can be improved with better overall temporal response devices.

A fall in voltage at the centerline of the flow is observed for both pure helium and

the mixture of 20% helium and 80% nitrogen for all four downstream distances. This

indicates that a leak could be detected at downstream distances as low as 8 nozzle

diameters. Also leak detection is feasible when taken in context of the overall full field

concentration distribution.

Future Work

* In order to determine the effect of background light, a dual line detection system
should be used.

* A study to determine the polarization effect of the incident beam on the scattered
signal should be done.















LIST OF REFERENCES

Becker H, Hottel H, Williams G, Light scatter technique for the study of turbulent
mixing, Journal of Fluid Mechanics, Nov 1967, vol. 30 (2), pp 259-284

Bohren C, Huffman D, 1983, Absorption and scattering of light by small particles, Wiley,
New York.

Bryner N, Pitts W, A Rayleigh Light scattering technique for investigation of free jets
and plumes, Review of Scientific Instruments, 1992, vol. 63 (7), pp 3629-2635

Chen C, Rodi W, 1980, HMT the science and applications of heat and mass transfer, vol.
4, Pergamon Press, Oxford.

Dave J, 1970, Scattering of electromagnetic radiation by a large, absorbing sphere. IBM
J. Res. Dev. 1969, vol. 13(3), pp 302-313.

Dibble R, Hollenbach R, Rambach G, Temperature measurements in turbulent flames via
Rayleigh scattering, 1980, American Chemical Society, pp 435-441.

Dyer T, Rayleigh scattering measurements of time resolved concentration in a turbulent
propane jet, 1979, AIAA Journal, vol. 17(8), pp 912-914

Graham S, Grant A, Jones J, Transient molecular concentration measurements in
turbulent flows using Rayleigh light scattering, 1974, AIAA Journal, vol. 12(8), pp
1140-1142

Horton J, Peterson J, Transient temperature measurements in an ideal gas by using laser
induced Rayleigh light scattering, August 1999, Review of Scientific Instruments,
vol. 70(8), pp 3222-3226.

Kerker M,1969, The scattering of light and other electromagnetic radiation, Academic
Press, New York.

Long M, Chu B, Chang R, Instantaneous two dimensional gas concentration
measurements by light scattering, AIAA Journal, September 1981, vol. 19(9), pp
1151-1157.

Matthew A, Peterson J, Flow visualizations and transient temperature measurements in
an axisymmetric impinging jet rapid thermal chemical vapor deposition reactor,
June 2002, Journal of Heat Transfer, vol. 124, pp 564-570

McCartney E, 1976, Optics of the atmosphere, Wiley, New York.









Muller-Dethlefs K, Weinberg F, Burning velocity measurements based on laser Rayleigh
scattering ,1979, Seventeenth symposium on combustion, vol. 27(2), pp 985-992.

Otugen M, 1997, Nd:YAG laser based dual line Rayleigh scattering system, AIAA
Journal vol. 35(5), pp 776-780.

Prahl S, http://omlc.ogi.edu/calc/mie_calc.html Last accessed :10/20/2004, Oregon
Medical Laser Center.

Pitts W, Kashiwagi, 1983, The application of laser induced Rayleigh light scattering to
the study of turbulent mixing, Journal of Fluid Mechanics, vol. 141, pp 391-429.

Pitz R, Cattolica R, Robben F, Talbot L, Temperature and Density in a Hydrogen Air
Flame from Rayleigh scattering, 1976, Com. Flame, vol. 27(3), pp 313-320.

Robben F, Comparison of density and temperature using Raman scattering and Rayleigh
scattering using combustion measurements in jet propulsion systems, 1975,
Proceedings of a project SQUID workshop, Purdue University. pp 179-195.

Rodi W, 1982, HMT the science and applications of heat and mass transfer, Pergamon
Press, Oxford

Rosenweig R, Hottel H, Williams G, Smoke scattered light measurements of turbulent
concentration fluctuations, Chem. Eng. Science, 1961, vol. 15(1,2), pp 111-129.

Schlichting H, 1979, Boundry layer theory, McGraw Hill Series in Mechanical
Engineering, New York

Shaughnessy E, Morton J, Laser light scattering measurements of particle concentration
in a turbulent jet. Journal of Fluid Mechanics, April 1977, vol. 80(1), pp129-148.

Wiscombe W, 1989, Improved Mie scattering algorithms, Applied Optics, 1980, vol.
19(9), 1505-1509











BIOGRAPHICAL SKETCH

Sameer Paranjpe finished his undergraduate degree in mechanical engineering from

the University of Bombay in 2002. He is pursuing his master's degree in mechanical

engineering at the University of Florida. He has been a research assistant under Dr. Jill

Peterson since August 2002.