Simulation on using cross-correlation technique for two-phase liquid/gas flow measurement for Ultrasonic Transmission Tomography

2010 ◽  
Author(s):  
N M N Ayob ◽  
S Yaacob ◽  
Z Zakaria ◽  
M H F Rahiman ◽  
R A Rahim
Keyword(s):  
Flow Measurement ◽  
Gas Flow ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Two Phase ◽  
Transmission Tomography ◽  
Phase Liquid ◽  
Cross Correlation Technique

Simulative Study On Liquid/Gas Two–Phase Flow Measurement For Dual–Plane Ultrasonic Transmission–Mode Tomography

2012 ◽  
Author(s):  
Nor Muzakkir Nor Ayob ◽  
Mohd Hafiz Fazalul Rahiman ◽  
Zulkarnay Zakaria ◽  
Sazali Yaacob ◽  
Ruzairi Abdul Rahim ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Cross Correlation ◽  
Two Phase Flow ◽  
Separation Distance ◽  
Correlation Technique ◽  
Phase Flow ◽  
Two Phase ◽  
Transmission Tomography ◽  
Single Plane ◽  
Dual Plane

Kajian simulatif telah dijalankan mengenai penggunaan teknik korelasi–silang untuk ultrasonik transmisi tomografi satah berganda. Teknik ini digunakan untuk membandingkan isyarat dari setiap satah yang masing–masing dinamakan satah–bawah dan satah–atas. Pemisahan jarak antara kedua–dua satah adalah tetap. Hasil dari perbandingan isyarat satah berganda, digabungkan dengan jarak pemisahan yang telah diketahui termasuk kelajuan sistem memproses maklumat, boleh digunakan untuk menganggarkan kelajuan aliran di dalam paip pemprosesan yang hendak diteliti. Penggabungan Ultrasonik Transmisi Tomografi (UTT) dengan teknik pengukuran korelasi–silang dapat memberikan maklumat yang lebih lanjut mengenai aliran jika dibandingkan dengan sistem UTT bersatah tunggal. Diskusi dalam artikel ini lebih memfokuskan kepada nilai min setiap gambar dan pekali korelasi 2D yang akan digunakan untuk mengkorelasikan gambar tomogram antara satah–bawah dan satah–atas. Prinsip pengukuran kelajuan pergerakan gas didalam keadaan gas dan cecair yg bergelembung berdasarkan pada korelasi–silang antara kedua–dua satah juga dijelaskan. Keputusan awal eksperimen menggambarkan kesesuaian kaedah yang dibentangkan di sini. Kata kunci: Korelasi–silang; corak beku; korelasi min; simulasi satah berganda; tomografi transmisi ultrasonik Simulative studies are done on the use of cross–correlation technique based on a dual–plane ultrasonic transmission tomography for liquid and gas two–phase flow measurement. This technique is used to correlate the signals from each sensing area namely downstream plane and upstream plane. Separation distance between both sensing areas is fixed. The result from cross correlating the dual–plane signals, combined with the known separation distance and the system’s acquisition rate is used to estimate the velocity of the flow inside the investigated process column. Combining Ultrasonic Transmission Tomography (UTT) with the cross–correlation flow measurement technique can provide more information on the flow than a single–plane UTT system. This paper focuses on the mean value of the images and the 2D correlation coefficient that is used to cross–correlate the tomogram images between the downstream and upstream plane of the simulated dual–plane ultrasonic transmission tomography system. The principle of measurement for local gas velocity distribution in a bubbly gas/liquid pipe flow based on crosscorrelation of two plane images is also described. Initial experimental results illustrate the feasibility of the method presented here. Key words: Cross–correlation; frozen pattern; mean correlation; dual–plane simulation; ultrasonic transmission tomography

scholarly journals The emergence of the red sequence at z~2 seen through galaxy clustering in the UKIDSS UDS

2012 ◽  
Vol 8 (S295) ◽  
pp. 105-108
Author(s):  
William G. Hartley ◽  
Omar Almaini ◽  
Alice Mortlock ◽  
Chris Conselice ◽  
Keyword(s):  
Dark Matter ◽  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Dark Matter Halos ◽  
Star Forming ◽  
Deep Survey ◽  
Cross Correlation Technique ◽  
Infrared Survey

AbstractWe use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the clustering for passive galaxies at z > 2, which we achieve using a cross-correlation technique. We find that passive galaxies are the most strongly clustered, typically hosted by massive dark matter halos with Mhalo > 1013 M⊙ irrespective of redshift or stellar mass. Our findings are consistent with models in which a critical halo mass determines the transition from star-forming to passive galaxies.

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