Variational method for estimating the effects of continuously varying lenses in HIFU, sonography, and sonography-based cross-correlation methods

2002 ◽  
Vol 111 (1) ◽  
pp. 468-474 ◽  
Author(s):  
Alex Alaniz ◽  
Faouzi Kallel ◽  
Ed Hungerford ◽  
Jonathan Ophir
Keyword(s):  
Variational Method ◽  
Cross Correlation ◽  
Correlation Methods

scholarly journals On BLR Size Estimates in Reverberation Models

2009 ◽  
Vol 5 (S267) ◽  
pp. 209-209
Author(s):  
Alexander V. Melnikov ◽  
Ivan I. Shevchenko
Keyword(s):  
Emission Line ◽  
Cross Correlation ◽  
Light Curves ◽  
Time Lags ◽  
Broad Line ◽  
Broad Line Region ◽  
Correlation Methods ◽  
Line Region ◽  
Size Estimates

Following the approach of Melnikov & Shevchenko (2008), we explore how the nonlinearity in the emission-line luminosity Ll of a broad-line region cloud, in its dependence on the ionizing continuum flux Fi incident on the cloud, affects estimates of the size of the broad-line region by means of cross-correlation methods. We show that the estimates obtained by straightforward cross-correlation of emission-line and continuum light curves can significantly underestimate the BLR size. We demonstrate examples of direct reverberation modelling of AGN emission-line light curves taking into account the nonlinearity of the “Ll–Fi” relation. This nonlinearity allows one to explain the differences in the time lags for different lines. Cross-correlation estimates of the BLR size turn out to be small in comparison to the estimates obtained by the direct reverberation modelling.

scholarly journals INTERPRETATION OF STALL PRECURSOR SIGNATURES

2021 ◽  
pp. 1-15
Author(s):  
Christoph Brandstetter ◽  
Xavier Ottavy ◽  
Benoit Paoletti ◽  
Sina C Stapelfeldt
Keyword(s):  
Cross Correlation ◽  
Sensor Placement ◽  
Experimental Studies ◽  
Measurement Data ◽  
Post Processing ◽  
Correlation Methods ◽  
Stall Precursor ◽  
Processing Techniques ◽  
Highly Loaded ◽  
Spectral Averaging

Abstract A specific phenomenon that has been observed in many experimental studies on turbomachinery compressors and fans is discussed under the term ‘rotating instabilities’. It is associated to a local aerodynamic phenomenon, typically occurring in the tip region at highly loaded near stall conditions and often linked to blade vibrations. Even though the effect has been discussed over more than two decades, a very ambiguous interpretation still prevails. A particular problem is that certain signatures in measurement data are often considered to characterize the phenomenon despite possible misinterpretations. The present paper illustrates that a specific image of a pulsating disturbance that has been established in the 1990s needs to be reconsidered. At the example of a recent investigation on a composite fan the difficulties concerning sensor placement and post-processing techniques is discussed with a focus on spectral averaging, isolation of non-synchronous phenomena and multi-sensor cross-correlation methods.

DISCUSSION OF THE CROSS-CORRELATION METHODS FOR PIV

1996 ◽  
Vol 3 (1) ◽  
pp. 65-78 ◽  
Author(s):  
Fujio Yamamoto ◽  
Ari-isa Wada ◽  
Manabu Iguchi ◽  
Masa-aki Ishikawa
Keyword(s):  
Cross Correlation ◽  
Correlation Methods ◽  
The Cross

Determination of thermodynamic properties with optical cross-correlation methods.

AIAA Journal ◽  
1969 ◽  
Vol 7 (4) ◽  
pp. 587-592 ◽  
Author(s):  
F. R. KRAUSE ◽  
W. O. DAVIES ◽  
M. W. P. CANN
Keyword(s):  
Thermodynamic Properties ◽  
Cross Correlation ◽  
Correlation Methods
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