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Autonomous orbit determination via integration of epoch-differenced gravity gradients and starlight refraction is proposed in this paper for low-Earth-orbiting satellites operating in GPS-denied environments. The starlight refrac-tion can…

Instrumentation and Methods for Astrophysics · Physics 2017-02-08 Pei Chen , Tengda Sun , Xiucong Sun

Interferometric calibration always yields non unique solutions. It is therefore essential to remove these ambiguities before the solutions could be used in any further modeling of the sky, the instrument or propagation effects such as the…

Instrumentation and Methods for Astrophysics · Physics 2013-07-19 Sarod Yatawatta

The (modern) arbitrary derivative (ADER) approach is a popular technique for the numerical solution of differential problems based on iteratively solving an implicit discretization of their weak formulation. In this work, focusing on an ODE…

Numerical Analysis · Mathematics 2024-01-15 Maria Han Veiga , Lorenzo Micalizzi , Davide Torlo

One of the biggest challenges in operating massive multiple-input multiple-output systems is the acquisition of accurate channel state information at the transmitter. To take up this challenge, time division duplex is more favorable thanks…

Information Theory · Computer Science 2024-10-30 Xiwen Jiang , Alexis Decurninge , Kalyana Gopala , Florian Kaltenberger , Maxime Guillaud , Dirk Slock , Luc Deneire

To provide rapid direction finding (DF) for unmanned aerial vehicle (UAV) emitter in future wireless networks, a low-complexity direction of arrival (DOA) estimation architecture for massive multiple input multiple output (MIMO) receiver…

Information Theory · Computer Science 2023-04-25 Yiwen Chen , Feng Shu , Qijuan Jie , Xichao Zhan , Xuehui Wang , Zhongwen Sun , Shihao Yan , Wenlong Cai , Peng Zhang , Peng Chen

Analyzing multi-way measurements with variations across one mode of the dataset is a challenge in various fields including data mining, neuroscience and chemometrics. For example, measurements may evolve over time or have unaligned time…

Machine Learning · Computer Science 2022-09-07 Marie Roald , Carla Schenker , Vince D. Calhoun , Tülay Adalı , Rasmus Bro , Jeremy E. Cohen , Evrim Acar

The localization of directional RF emitters presents significant challenges for electronic warfare applications. Traditional localization methods, designed for omnidirectional emitters, experience degraded performance when applied to…

Signal Processing · Electrical Eng. & Systems 2025-10-30 Fraser Williams , Akila Pemasiri , Dhammika Jayalath , Terry Martin , Clinton Fookes

The development of new phased array systems in radio astronomy, as the low frequency array (LOFAR) and the square kilometre array (SKA), formed of a large number of small and flexible elementary antennas, has led to significant challenges.…

Camera calibration is an essential process in photogrammetry, serving as a crucial link between the 2D image coordinate system and the 3D world coordinate system. However, when observations are conducted through refractive interfaces, the…

For radio interferometric arrays with a sufficient number of redundant spacings the multiplicity of measurements of the same sky visibility can be used to determine both the antenna gains as well as the true visibilities. Many of the…

Instrumentation and Methods for Astrophysics · Physics 2013-10-08 Visweshwar Ram Marthi , Jayaram Chengalur

The increased sensitivity of future radio telescopes will result in requirements for higher dynamic range within the image as well as better resolution and immunity to interference. In this paper we propose a new matrix formulation of the…

Astrophysics · Physics 2014-11-18 Chen Ben-David , Amir Leshem

The calibration of modern radio interferometers is a significant challenge, specifically at low frequencies. In this perspective, we propose a novel iterative calibration algorithm, which employs the popular sparse representation framework,…

Instrumentation and Methods for Astrophysics · Physics 2016-06-06 Martin Brossard , Mohamed Nabil El Korso , Marius Pesavento , Rémy Boyer , Pascal Larzabal

In this paper, we consider the initial boundary value problem of the two dimensional multi-term time fractional mixed diffusion and diffusion-wave equations. An alternating direction implicit (ADI) spectral method is developed based on…

Numerical Analysis · Mathematics 2018-09-03 Zeting Liu , Fawang Liu , Fanhai Zeng

Adaptive gradient methods have attracted much attention of machine learning communities due to the high efficiency. However their acceleration effect in practice, especially in neural network training, is hard to analyze, theoretically. The…

Optimization and Control · Mathematics 2020-06-15 Xunpeng Huang , Hao Zhou , Runxin Xu , Zhe Wang , Lei Li

In this article, we introduce a three-precision formulation of the General Alternating-Direction Implicit method (GADI) designed to accelerate the solution of large-scale sparse linear systems $Ax=b$. GADI is a framework that can represent…

Numerical Analysis · Mathematics 2026-01-01 Jifeng Ge , Bastien Vieublé , Juan Zhang

We derive the alternating-directions implicit (ADI) method based on a commuting operator split and apply the results in detail to the continuous time algebraic Lyapunov equation with low-rank constant term and approximate solution, giving…

Numerical Analysis · Mathematics 2025-01-24 Jonas Schulze , Jens Saak

For numerical simulations of highly relativistic and transversely accelerated charged particles including radiation fast algorithms are needed. While the radiation in particle accelerators has wavelengths in the order of 100 um the…

Computational Physics · Physics 2015-05-28 Christof Kraus , Andreas Adelmann , Peter Arbenz

Approximate computing has in recent times found significant applications towards lowering power, area, and time requirements for arithmetic operations. Several works done in recent years have furthered approximate computing along these…

Hardware Architecture · Computer Science 2020-09-01 Rajat Bhattacharjya , Vishesh Mishra , Saurabh Singh , Kaustav Goswami , Dip Sankar Banerjee

We describe and compare several post-correlation radio frequency interference classification methods. As data sizes of observations grow with new and improved telescopes, the need for completely automated, robust methods for radio frequency…

Instrumentation and Methods for Astrophysics · Physics 2010-07-14 A. R. Offringa , A. G. de Bruyn , M. Biehl , S. Zaroubi , G. Bernardi , V. N. Pandey

A new version of the alternating directions implicit (ADI) iteration for the solution of large-scale Lyapunov equations is introduced. It generalizes the hitherto existing iteration, by incorporating tangential directions in the way they…

Numerical Analysis · Mathematics 2013-12-05 Thomas Wolf , Heiko K. F. Panzer , Boris Lohmann