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In this work we present a method to adaptively compensate for scale factor errors in both rotational velocity and seeker angle measurements. The adaptation scheme estimates the scale factor errors using a predictive coding model implemented…

Systems and Control · Electrical Eng. & Systems 2020-09-16 Brian Gaudet

Nullifying the servo bandwidth errors improves the strehl ratio by a substantial quantity in adaptive optics systems. An effective method for predicting atmospheric turbulence to reduce servo bandwidth errors in real time closed loop…

Instrumentation and Methods for Astrophysics · Physics 2011-09-14 Akondi Vyas , M B Roopashree , B Raghavendra Prasad

RIS-assisted communication has recently attracted significant attention for enhancing wireless performance in challenging environments, making accurate error analysis under practical hardware constraints crucial for future multi-antenna…

Signal Processing · Electrical Eng. & Systems 2025-08-27 Tayfun Yilmaz , Haci Ilhan , Ibrahim Hokelek

Many adaptive optics systems operate by measuring the distortion of the wavefront in one wavelength range and performing the scientific observations in a second, different wavelength range. One common technique is to measure wavefront…

Astrophysics · Physics 2009-11-07 Henry G. Roe

With its high sensitivity, the Pyramid wavefront sensor (PyWFS) is becoming an advantageous sensor for astronomical adaptive optics (AO) systems. However, this sensor exhibits significant non-linear behaviours leading to challenging AO…

Instrumentation and Methods for Astrophysics · Physics 2021-05-12 Vincent Chambouleyron , Olivier Fauvarque , Jean-François Sauvage , Benoît Neichel , Thierry Fusco

In typical adaptive optics applications, the atmospheric residual turbulence affects the wavefront sensor response decreasing its sensitivity. On the other hand, wavefront sensors are generally calibrated in diffraction limited condition,…

Instrumentation and Methods for Astrophysics · Physics 2023-10-10 Guido Agapito , Carmelo Arcidiacono , Simone Esposito

We study the role of numerical quadrature in residual-minimisation methods for neural network approximation of partial differential equations. We first present an abstract error framework that separates approximation, quadrature and…

Numerical Analysis · Mathematics 2026-05-04 Santiago Badia , Kishore Nori

Disturbances such as atmospheric turbulence and aero-optic effects lead to wavefront aberrations, which degrade performance in imaging and laser propagation applications. Adaptive optics (AO) provide a method to mitigate these effects by…

Signal Processing · Electrical Eng. & Systems 2024-10-17 Jeffrey Utley , Gregery Buzzard , Charles Bouman , Matthew Kemnetz

Precise lens structure segmentation is essential for the design of intraocular lenses (IOLs) in cataract surgery. Existing deep segmentation networks typically weight all pixels equally under cross-entropy (CE) loss, overlooking the fact…

Computer Vision and Pattern Recognition · Computer Science 2025-08-13 Zunjie Xiao , Xiao Wu , Tianhang Liu , Lingxi Hu , Yinling Zhang , Xiaoqing Zhang , Risa Higashita , Jiang Liu

The convergence analysis for least-squares finite element methods led to various adaptive mesh-refinement strategies: Collective marking algorithms driven by the built-in a posteriori error estimator or an alternative explicit…

Numerical Analysis · Mathematics 2023-09-18 Philipp Bringmann

Modern optical flow methods make use of salient scene feature points detected and matched within the scene as a basis for sparse-to-dense optical flow estimation. Current feature detectors however either give sparse, non uniform point…

Computer Vision and Pattern Recognition · Computer Science 2019-05-21 Felix Stephenson , Toby Breckon , Ioannis Katramados

The optics of any camera degrades the sharpness of photographs, which is a key visual quality criterion. This degradation is characterized by the point-spread function (PSF), which depends on the wavelengths of light and is variable across…

Image and Video Processing · Electrical Eng. & Systems 2022-08-02 Thomas Eboli , Jean-Michel Morel , Gabriele Facciolo

For adaptive mixed finite element methods (AMFEM), we first introduce the data oscillation to analyze, without the restriction that the inverse of the coefficient matrix of the partial differential equations (PDEs) is a piecewise polynomial…

Numerical Analysis · Mathematics 2011-01-07 Shaohong Du , Xiaoping Xie

Purpose: To propose an alternating learning approach to learn the sampling pattern (SP) and the parameters of variational networks (VN) in accelerated parallel magnetic resonance imaging (MRI). Methods: The approach alternates between…

Image and Video Processing · Electrical Eng. & Systems 2021-10-29 Marcelo V. W. Zibetti , Florian Knoll , Ravinder R. Regatte

Performances of an adaptive optics (AO) system are directly linked with the quality of its alignment. During the instrument calibration, having open loop fast tools with a large capture range are necessary to quickly assess the system…

In reconfigurable intelligent surface (RIS) aided millimeter-wave (mmWave) communication systems, in order to overcome the limitation of the conventional channel state information (CSI) acquisition techniques, this paper proposes a location…

Information Theory · Computer Science 2024-10-28 Zhe Xing , Rui Wang , Xiaojun Yuan , Jun Wu

An adaptive refinement strategy, based on an equilibrated flux a posteriori error estimator, is proposed in the context of defeaturing problems. Defeaturing consists of removing features from complex domains to simplify mesh generation and…

Numerical Analysis · Mathematics 2026-03-04 Annalisa Buffa , Denise Grappein , Rafael Vázquez

The use of laser guide stars in astronomical adaptive optics results in elongated Shack-Hartmann wavefront sensor image patterns. Image correlation techniques can be used to determine local wavefront slope by correlating each sub-aperture…

Instrumentation and Methods for Astrophysics · Physics 2014-03-05 Alastair Basden

Finite difference method as a popular numerical method has been widely used to solve fractional diffusion equations. In the general spatial error analyses, an assumption $u\in C^{4}(\bar{\Omega})$ is needed to preserve $\mathcal{O}(h^{2})$…

Numerical Analysis · Mathematics 2023-02-07 Daxin Nie , Jing Sun , Weihua Deng

We propose an adaptive training scheme for unsupervised medical image registration. Existing methods rely on image reconstruction as the primary supervision signal. However, nuisance variables (e.g. noise and covisibility), violation of the…

Image and Video Processing · Electrical Eng. & Systems 2024-07-19 Xiaoran Zhang , John C. Stendahl , Lawrence Staib , Albert J. Sinusas , Alex Wong , James S. Duncan
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