Results 301 to 310 of about 1,799,934 (343)

Phase estimation using phase gradients obtained through Hilbert transform

Journal of the Optical Society of America A, 2016
An algorithm to extract phase in its unwrapped form from an interferogram having perturbed straight line fringes is proposed and studied. Phase gradients are extracted from an interferogram using the Hilbert transform, and the phase is then estimated from their gradients using the method of least squares for the Hudgin geometry.
P A, Ameen Yasir, J, Solomon Ivan
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Reverberant shear wave phase gradients for elastography

Physics in Medicine & Biology, 2021
Abstract Reverberant shear wave fields are produced when multiple sources and multiple reflections establish a complex three-dimensional wave field within an organ. The expected values are assumed to be isotropic across all directions and the autocorrelation functions for velocity are expressed in terms of ...
J Ormachea, K J Parker
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Phase unwrapping fitting local planes to phase gradient

SPIE Proceedings, 2012
Phase wrapping is an intermediate step ffor interferometry analysis. When phase is smooth, its unwrapping can be carried out fitting local planes with finite extension at each point of the phase gradient. We propose a method easy to implement that spends the same computation time than those techniques based on basis functions.
E. Gonzalez-Ramirez, E. de la Rosa Miranda, L. R. Berriel-Valdos, Tonatiuh Saucedo Anaya, Ismael de la Rosa Vargas, Ma Auxiliadora Araiza Esquivel   +5 more
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Two-dimensional phase gradient autofocus

SPIE Proceedings, 2000
ABSTRACT ! ! ! " " ! autofocus ! # $ ! #$ % & ! ! ' ( ! " )*+ ! ,-#./ ! " , ! 01 & 01 ! ! #$ * ! 2 01 ! 3 ! " Keywords: ! #$ )*+ ,-#./ " 1. INTRODUCTION "
Douglas W. Warner, Dennis C. Ghiglia, Alan Fitzgerrell, John Beaver   +3 more
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Phase Behavior of Gradient Copolymers

Macromolecules, 2008
A multiblock model is developed for the study of the phase behavior of gradient copolymers. The model is able to describe gradient copolymer chains with arbitrary composition profiles. The validity of the multiblock model of gradient copolymers is established by good agreement between RPA (random phase approximation) results for a continuous ...
Run Jiang, Qinghua Jin, Baohui Li, Datong Ding, Robert A. Wickham, An-Chang Shi   +5 more
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Phase-gradient stellar image reconstruction

Optics Communications, 1986
Abstract An algorithm is presented for the direct measurement of the phase gradient of an object's spatial-frequency spectrum from stellar speckle images. The process is based on the differentiation properties of Fourier transforms. Bias terms inherent to the process at low light levels depend on object asymmetry and can be expected to be less ...
G.J.M. Aitken, R. Johnson, R. Houtman
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Phase behavior of gradient copolymers

The Journal of Chemical Physics, 1999
Phase properties of gradient AB copolymer melts which consist of chains with the specified chemical distribution of A and B monomers have been studied within the Landau–Ginzburg model. All the melts with the linear distribution of the monomers exhibit only a direct continuous phase transition from disordered to the lamellar phase.
Aleksij Aksimentiev, Robert Hołyst
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Vapor-Phase Plotting of Organosilane Chemical Gradients

Langmuir, 2018
Vapor-phase plotting of organosilane-based self-assembled monolayer (SAM) gradients is demonstrated for the first time. Patterned SAMs are formed by delivering gas-phase organotrichlorosilane precursors to a reactive silica surface using a heated glass capillary.
Judith Bautista-Gomez, Anna V. Forzano, Joshua M. Austin, Maryanne M. Collinson, Daniel A. Higgins   +4 more
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Measurement of phase gradients in the EEG

Journal of Neuroscience Methods, 2006
Previous research has shown that spatio-temporal waves in the EEG are generally of long spatial wavelength and form smooth patterns of phase gradients at particular time-samples. This paper describes a method to measure smooth phase gradients of long spatial wavelength in the EEG.
D M, Alexander, C, Trengove, J J, Wright, P R, Boord, E, Gordon   +4 more
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Peak compression in reversed-phase gradient elution

Journal of Chromatography A, 2006
Previous reports suggest that peak widths in linear gradient elution are consistently larger than predicted by theory; however, if gradient compression is ignored, experiment and theory are in reasonable agreement. This suggests that gradient compression might represent an incorrect or poorly understood concept.
Uwe D, Neue, Daniel H, Marchand, Lloyd R, Snyder   +2 more
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