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Phase-gradient algorithm as an optimal estimator of the phase derivative
Optics Letters, 1989The phase-gradient algorithm represents a powerful new signal-processing technique with applications to aperture-synthesis imaging. These include, for example, synthetic-aperture-radar phase correction and stellar-image reconstruction. The algorithm combines redundant information present in the data to arrive at an estimate of the phase derivative.
P H, Eichel, C V, Jakowatz
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Ghost phase cancellation with phase‐encoding gradient modulation
Journal of Magnetic Resonance Imaging, 1993AbstractMotion artifacts are a dominant cause of magnetic resonance image quality degradation. Periodic or nearly periodic motion results in image replicates of the moving structures in spin‐warp Fourier imaging. The replicates, or ghosts, propagate in the image in the phase encoding, or y, direction.
R S, Hinks, Q S, Xiang, R M, Henkelman
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A Generalized Phase Gradient Autofocus Algorithm
IEEE Transactions on Computational Imaging, 2019The phase gradient autofocus (PGA) algorithm has seen widespread use and success within the synthetic aperture radar (SAR) imaging community. However, its use and success has largely been limited to collection geometries where either the polar format algorithm (PFA) or range migration algorithm is suitable for SAR image formation.
Aaron Evers, Julie Ann Jackson
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Reverberant shear wave phase gradients for elastography
Physics in Medicine & Biology, 2021Abstract 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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High quality factor phase gradient metasurfaces
Nature Nanotechnology, 2020Dielectric microcavities with quality factors (Q-factors) in the thousands to billions markedly enhance light-matter interactions, with applications spanning high-efficiency on-chip lasing, frequency comb generation and modulation and sensitive molecular detection.
Mark Lawrence +6 more
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Stripmap phase gradient autofocus
Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003Current sonar autofocus techniques for blur removal originate in the radar community but have not provided a complete solution for Synthetic Aperture Sonar (SAS) imagery. The wide-beam, wide-band nature of SAS imagery makes implementation of Synthetic Aperture Radar (SAR) autofocus techniques difficult.
H.J. Callow, M.P. Hayes, P.T. Gough
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Phase Behavior of Gradient Copolymers
Macromolecules, 2008A 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 +5 more
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Phase behavior of gradient copolymers
The Journal of Chemical Physics, 1999Phase 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, 2018Vapor-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 +4 more
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1989
The y gradient is applied in the direction perpendicular to the coronal plane. Now it would seem that we could be able to use frequency in this direction just as we did for the x axis. However, if we did that, then we would not be able to uniquely specify whether a given frequency belonged to the x or the y axis, and the computer would get confused and
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The y gradient is applied in the direction perpendicular to the coronal plane. Now it would seem that we could be able to use frequency in this direction just as we did for the x axis. However, if we did that, then we would not be able to uniquely specify whether a given frequency belonged to the x or the y axis, and the computer would get confused and
openaire +1 more source