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MR image sparsity/compressibility has been widely exploited for imaging acceleration with the development of compressed sensing. A sparsity-based approach to rigid-body motion correction is presented for the first time in this paper. A…

Computer Vision and Pattern Recognition · Computer Science 2013-02-04 Zai Yang , Cishen Zhang , Lihua Xie

Within the framework of Quantum Reduced Loop Gravity we quantize the Hamiltonian for a gauge vector field. The regularization can be performed using tools analogous to the ones adopted in full Loop Quantum Gravity, while the matrix elements…

General Relativity and Quantum Cosmology · Physics 2017-06-07 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani , Pietro Donà , Antonino Marciano

First order rotational perturbations of the flat Friedmann-Robertson-Walker (FRW) metric are considered in the framework of four dimensional Neveu-Schwarz-Neveu-Schwarz (NS-NS) string cosmological models coupled with dilaton and axion…

High Energy Physics - Theory · Physics 2010-11-19 Chiang-Mei Chen , T. Harko , M. K. Mak

The gravitational field exterior respectively interior to an axially symmetric, metrically stationary, isolated spinning source made of perfect fluid is examined within the quasi-metric framework. (A metrically stationary system is defined…

General Relativity and Quantum Cosmology · Physics 2024-03-25 Dag Østvang

In this paper we the formulation of inverse problems as constrained minimization problems and their iterative solution by gradient or Newton type. We carry out a convergence analysis in the sense of regularization methods and discuss…

Numerical Analysis · Mathematics 2021-01-15 Barbara Kaltenbacher , Kha Van Huynh

We consider the equations for the coefficients of stationary rotating axisymmetric metrics governed by the Einstein-Euler equations, that is, the Einstein equations together with the energy-momentum tensor of a barotropic perfect fluid.…

Analysis of PDEs · Mathematics 2021-06-10 Tetu Makino

Matrix models play an important role in studies of quantum gravity, being candidates for a formulation of M-theory, but are notoriously difficult to solve. In this work, we present a fresh approach by introducing a novel exact model…

Quantum Physics · Physics 2015-11-23 R. Hübener , Y. Sekino , J. Eisert

In this paper, we consider very rough solutions to Cauchy problem for the Einstein vacuum equations in CMC spacial harmonic gauge, and obtain the local well-posedness result in $H^s, s>2$. The novelty of our approach lies in that, without…

Analysis of PDEs · Mathematics 2012-01-04 Qian Wang

A general form of a metric preserving all symmetries of a spherically symmetric gravitational field and angular momentum in spherical coordinates is obtained. Such metric may have $g_{01}(r)\neq 0$. The Newtonian limit uniquely defines…

General Physics · Physics 2019-12-18 Yaakov Friedman , Shmuel Stav

The Lorentz Integral Transform approach allows microscopic calculations of electromagnetic reaction cross sections without explicit knowledge of final state wave functions. The necessary inversion of the transform has to be treated with…

Nuclear Theory · Physics 2009-11-11 Diego Andreasi , Winfried Leidemann , Christoph Reiss , Michael Schwamb

In this paper, the metric approach of $f(R)$ theory of gravity is used to investigate the exact vacuum solutions of spatially homogeneous rotating spacetimes. For this purpose, R is replaced by f(R) in the standard Einstein-Hilbert action…

General Relativity and Quantum Cosmology · Physics 2015-06-18 M. Jamil Amir , Saima Naheed

This study proposes a cubic regularization of the Newton method for generating weakly efficient points of unconstrained vector optimization problems under no convexity assumption on the objective function. It is observed that at a given…

Optimization and Control · Mathematics 2025-05-20 Debdas Ghosh

In this paper, we propose a randomized accelerated method for the minimization of a strongly convex function under linear constraints. The method is of Kaczmarz-type, i.e. it only uses a single linear equation in each iteration. To obtain…

Optimization and Control · Mathematics 2025-04-03 Lionel Tondji , Dirk A. Lorenz , Ion Necoara

This work focuses on the problem of exact model reduction of positive linear systems, by leveraging minimal realization theory. While determining the existence of a positive reachable realization remains in general an open problem, we are…

Systems and Control · Electrical Eng. & Systems 2025-09-18 Marco Cortese , Tommaso Grigoletto , Francesco Ticozzi , Augusto Ferrante

A Lorentz and gauge symmetry preserving regularization method is discussed in four dimension based on momentum cutoff. We use the conditions of gauge invariance or equivalently the freedom of shift of the loop momentum to define the…

High Energy Physics - Phenomenology · Physics 2015-09-25 G. Cynolter , E. Lendvai

As a sequel to (Berman, 2008a), we show that the rotation of the Universe can be dealt by generalised Gaussian metrics, defined in this paper. Robertson-Walker's metric has been employed with proper-time, in its standard applications; the…

General Physics · Physics 2009-11-13 Marcelo Samuel Berman

This paper has taken into advantage the relationship between Fuzzy Relation Equations (FRE) and Concept Lattices in order to introduce a procedure to reduce a FRE, without losing information. Specifically, attribute reduction theory in…

Artificial Intelligence · Computer Science 2024-10-10 David Lobo , Víctor López-Marchante , Jesús Medina

The problem of compressing a real-valued sparse source using compressive sensing techniques is studied. The rate distortion optimality of a coding scheme in which compressively sensed signals are quantized and then reconstructed is…

Information Theory · Computer Science 2010-11-09 Rajiv Soundararajan , Sriram Vishwanath

The Extended Randomized Kaczmarz method is a well known iterative scheme which can find the Moore-Penrose inverse solution of a possibly inconsistent linear system and requires only one additional column of the system matrix in each…

Numerical Analysis · Mathematics 2022-07-21 Frank Schöpfer , Dirk A Lorenz , Lionel Tondji , Maximilian Winkler

In recent years, the fervent demand for computational power across various domains has prompted hardware manufacturers to introduce specialized computing hardware aimed at enhancing computational capabilities. Particularly, the utilization…

Numerical Analysis · Mathematics 2024-03-12 Hongyaoxing Gu
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