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Interferometry can measure the shape or the material density of a system that could not be measured otherwise by recording the difference between the phase change of a signal and a reference phase. This difference is always between $-\pi$…

Plasma Physics · Physics 2022-10-20 Pierre-Alexandre Gourdain , Aidan Bachmann

We introduce a method for analyzing radio interferometry data which produces maps which are optimal in the Bayesian sense of maximum posterior probability density, given certain prior assumptions. It is similar to maximum entropy…

Astrophysics · Physics 2009-11-11 Edmund C. Sutton , Benjamin D. Wandelt

In this work, we present a novel approach for solving stochastic shape optimization problems. Our method is the extension of the classical stochastic gradient method to infinite-dimensional shape manifolds. We prove convergence of the…

Optimization and Control · Mathematics 2020-11-03 Caroline Geiersbach , Estefania Loayza-Romero , Kathrin Welker

Radio interferometers are phased arrays producing high-resolution images from the covariance matrix of measurements. Calibration of such instruments is necessary and is a critical task. This is how the estimation of instrumental errors is…

Instrumentation and Methods for Astrophysics · Physics 2023-09-26 Yassine Mhiri , Mohammed Nabil El Korso , Arnaud Breloy , Pascal Larzabal

Radio interferometers observe the Fourier space of the sky, at locations determined by the array geometry. Before a real space image is constructed by a Fourier transform, the data is weighted to improve the quality of reconstruction. Two…

Instrumentation and Methods for Astrophysics · Physics 2015-06-22 Sarod Yatawatta

The conventional beam management procedure mandates that the user equipment (UE) periodically measure the received signal reference power (RSRP) and transmit these measurements to the base station (BS). The challenge lies in balancing the…

Systems and Control · Electrical Eng. & Systems 2023-10-31 Junshuo Liu , Rujing Xiong , Jialong Lu , Tiebin Mi , Robert C. Qiu

The data reduction procedure for radio interferometers can be viewed as a combined calibration and imaging problem. We present an algorithm that unifies cross-calibration, self-calibration, and imaging. Being a Bayesian method, that…

Instrumentation and Methods for Astrophysics · Physics 2019-07-23 Philipp Arras , Philipp Frank , Reimar Leike , Rüdiger Westermann , Torsten Enßlin

The spatial-frequency coverage of a radio interferometer is increased by combining samples acquired at different times and observing frequencies. However, astrophysical sources often contain complicated spatial structure that varies within…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 U. Rau

We study the problem of actively imaging a range-limited far-field scene using an antenna array. We describe how the range limit imposes structure in the measurements across multiple wavelengths. This structure allows us to introduce a…

Signal Processing · Electrical Eng. & Systems 2019-02-04 Rakshith Sharma Srinivasa , Mark A. Davenport , Justin Romberg

Astronomers usually need the highest angular resolution possible, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely-separated…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 John D. Monnier , Ronald J. Allen

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 reconfigurable intelligent surface is a promising technology for the manipulation and control of wireless electromagnetic signals. In particular, it has the potential to provide significant performance improvements for wireless…

Signal Processing · Electrical Eng. & Systems 2022-09-14 Hamidreza Taghvaee , Akshay Jain , Sergi Abadal , Gabriele Gradoni , Eduard Alarcón , Albert Cabellos-Aparicio

We present a methodology for the design of optimal Raman beam-splitter pulses suitable for cold atom inertial sensors. The methodology, based on time-dependent perturbation theory, links optimal control and the sensitivity function…

Atomic Physics · Physics 2023-09-01 Nikolaos Dedes , Jack Saywell , Max Carey , Ilya Kuprov , Tim Freegarde

A major obstacle to attain the fundamental precision limit of the phase estimation in an interferometry is the identification and implementation of the optimal measurement. Here we demonstrate that this can be accomplished by the use of…

Quantum Physics · Physics 2017-05-10 Wei Zhong , Yixiao Huang , Xiaoguang Wang , Shi-Liang Zhu

A joint robust transmit/receive adaptive beamforming for multiple-input multipleoutput (MIMO) radar based on probability-constrained optimization approach is developed in the case of Gaussian and arbitrary distributed mismatch present in…

Information Theory · Computer Science 2016-03-03 Weiyu Zhang , Sergiy A. Vorobyov

Up to now, the completion of an ALMA interferometric observation is determined based on the achievement of a given shape and size of the synthesized beam and the noise RMS in the representative spectral range. This approach with respect to…

Instrumentation and Methods for Astrophysics · Physics 2020-12-17 Dirk Petry , María Díaz Trigo , Rüdiger Kneissl , Ignacio Toledo , Stefano Facchini

Finding a suitable very long baseline (VLBI) interferometer geometry is a key task in planning observations, especially imaging sessions. The main characteristic of the quality of VLBI imaging data is the (u, v)-coverage. In the case when…

Instrumentation and Methods for Astrophysics · Physics 2024-04-01 I. I. Bulygin , M. A. Shchurov , A. G. Rudnitskiy

Bayesian methods are developed for the multivariate nonparametric regression problem where the domain is taken to be a compact Riemannian manifold. In terms of the latter, the underlying geometry of the manifold induces certain symmetries…

Statistics Theory · Mathematics 2007-06-13 Jean-François Angers , Peter T. Kim

Controlling the radar beam-pattern by optimizing the transmit covariance matrix is a well-established approach for performance enhancement in multiple-input-multiple-output (MIMO) radars. In this paper, we investigate the joint optimization…

Signal Processing · Electrical Eng. & Systems 2022-08-10 Arindam Bose , Shahin Khobahi , Mojtaba Soltanalian

In radiation therapy, tumor tracking is a challenging task that allows a better dose delivery. One practice is to acquire X-ray images in real-time during treatment, that are used to estimate the tumor location. These informations are used…

Applications · Statistics 2019-03-22 Antoine Aspeel , Damien Dasnoy , Raphaël M. Jungers , Benoît Macq