scholarly journals Correlation analysis for the research of local characteristics of a turbulent flow

2021 ◽  
Vol 2057 (1) ◽  
pp. 012098
Author(s):  
P A Sardov ◽  
I A Belyaev ◽  
Ya I Listratov ◽  
N G Razuvanov

Abstract The paper describes the temperature-correlation velocimetry technique applied to the flow of water or liquid metal. The method allows simultaneous measurement of temperature signals and local values of a longitudinal velocity component in the flow. This approach is a simple and reliable method for measuring velocity in flows of optically impermeable fluids. At the same flow conditions, different coolants have different spatial-temporal characteristics that are processed using a temperature-correlation technique. This work is devoted to the development of an algorithm for formulating a set of practical recommendations for the use of this technique to measure velocity and to determine a metrological characteristic in various conditions. For calibration, water and mercury are used as model liquids. The data obtained are presented in the form of fields of temperature and intensity of temperature fluctuations. Autocorrelation and cross-correlation functions are compared for two investigated liquids under the same conditions.

2012 ◽  
Vol 8 (S295) ◽  
pp. 105-108
Author(s):  
William G. Hartley ◽  
Omar Almaini ◽  
Alice Mortlock ◽  
Chris Conselice ◽  

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.


1972 ◽  
Vol 5 (4) ◽  
pp. 142-146
Author(s):  
M S Beck ◽  
N E Gough ◽  
J N Smithies

A novel method of controlling the flow rates of fluids has been devised which is particularly suitable for highly erosive fluids and slurries. The width of pulses in a pulse train actuating an on-off valve is modulated according to the error between the desired and measured flow rates and thus the ratio of the total times the valve spends in its ‘on’ and ‘off’ states is varied. The method has been tested with an on-line computer which was used to measure the flow rate of water by a cross-correlation method to determine the transit time of temperature fluctuations between two thermocouples in the pipe, and to implement the pulse width modulation control. Satisfactory results have been obtained for start-up, set-point changes and load disturbances for flow rates in the turbulent region (Re > 3 600). Future development includes the use of a fluidic diverter as the on-off device.


2009 ◽  
Vol 63 (11) ◽  
pp. 1197-1203 ◽  
Author(s):  
E. D. Emmons ◽  
A. Tripathi ◽  
J. A. Guicheteau ◽  
S. D. Christesen ◽  
A. W. Fountain

Raman chemical imaging (RCI) has been used to detect and identify explosives in contaminated fingerprints. Bright-field imaging is used to identify regions of interest within a fingerprint, which can then be examined to determine their chemical composition using RCI and fluorescence imaging. Results are presented where explosives in contaminated fingerprints are identified and their spatial distributions are obtained. Identification of explosives is obtained using Pearson's cosine cross-correlation technique using the characteristic region (500–1850 cm−1) of the spectrum. This study shows the ability to identify explosives nondestructively so that the fingerprint remains intact for further biometric analysis. Prospects for forensic examination of contaminated fingerprints are discussed.


2021 ◽  
Author(s):  
Alexandre Allil ◽  
Fábio Dutra ◽  
Cesar Cosenza Carvalho ◽  
Alex Dante ◽  
Regina Allil ◽  
...  

2020 ◽  
Vol 495 (2) ◽  
pp. 1706-1723 ◽  
Author(s):  
Richard A Battye ◽  
Michael L Brown ◽  
Caitlin M Casey ◽  
Ian Harrison ◽  
Neal J Jackson ◽  
...  

ABSTRACT The SuperCLuster Assisted Shear Survey (SuperCLASS) is a legacy programme using the e-MERLIN interferometric array. The aim is to observe the sky at L-band (1.4 GHz) to a r.m.s. of $7\, \mu {\rm Jy}\,$beam−1 over an area of $\sim 1\, {\rm deg}^2$ centred on the Abell 981 supercluster. The main scientific objectives of the project are: (i) to detect the effects of weak lensing in the radio in preparation for similar measurements with the Square Kilometre Array (SKA); (ii) an extinction free census of star formation and AGN activity out to z ∼ 1. In this paper we give an overview of the project including the science goals and multiwavelength coverage before presenting the first data release. We have analysed around 400 h of e-MERLIN data allowing us to create a Data Release 1 (DR1) mosaic of $\sim 0.26\, {\rm deg}^2$ to the full depth. These observations have been supplemented with complementary radio observations from the Karl G. Jansky Very Large Array (VLA) and optical/near infrared observations taken with the Subaru, Canada-France-Hawaii, and Spitzer Telescopes. The main data product is a catalogue of 887 sources detected by the VLA, of which 395 are detected by e-MERLIN and 197 of these are resolved. We have investigated the size, flux, and spectral index properties of these sources finding them compatible with previous studies. Preliminary photometric redshifts, and an assessment of galaxy shapes measured in the radio data, combined with a radio-optical cross-correlation technique probing cosmic shear in a supercluster environment, are presented in companion papers.


2004 ◽  
Vol 193 ◽  
pp. 275-278
Author(s):  
Malcolm Cropp ◽  
Karen R. Pollard ◽  
Jovan Skuljan

AbstractFour δ Scuti stars were observed with the HERCULES fibrefed échelle spectrograph at Mount John University Observatory, New Zealand. These observations were analysed by looking at the radial velocity variations as given by a cross-correlation technique as well as spectral line moment variations. These results were compared to published photometric studies of these stars to see if the modes identified in the photometry were also present in the spectroscopic data obtained.


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