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Spectral enhancement -- which aims to undo spectral broadening -- leads to integral equations which are ill-posed and require special regularisation techniques for their solution. Even when an optimal regularisation technique is used,…

Numerical Analysis · Mathematics 2009-11-16 Markus Hegland

Dynamic metasurface antennas (DMAs) beamform through low-powered components that enable reconfiguration of each radiating element. Previous research on a single-user multiple-input-single-output (MISO) system with a dynamic metasurface…

Signal Processing · Electrical Eng. & Systems 2024-12-03 Nitish Vikas Deshpande , Joseph Carlson , Miguel R. Castellanos , Robert W. Heath

We describe and demonstrate a technique for correcting direction dependent artifacts due to asymmetries in antenna patterns and differences among antennas used in radio interoferometric imaging. The technique can correct images in all…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 W. D. Cotton , T. Mauch

Images obtained with single-conjugate adaptive optics (AO) show spatial variation of the point spread function (PSF) due to both atmospheric anisoplanatism and instrumental aberrations. The poor knowledge of the PSF across the field of view…

This paper presents the first detailed investigation of the characteristics of mm/submm phase fluctuation and phase correction methods obtained using ALMA with baseline lengths up to ~15 km. Most of the spatial structure functions (SSFs)…

Direction-dependent instrumental polarisation introduces wide-field polarimetric aberrations and limits the dynamic range of low-frequency interferometric images. We therefore provide a detailed two-dimensional analysis of the Giant…

Instrumentation and Methods for Astrophysics · Physics 2014-07-03 J. S. Farnes

Because of atmospheric turbulence, obtaining high angular resolution images with a high dynamic range is difficult even in the near infrared domain of wavelengths. We propose a novel technique to overcome this issue. The fundamental idea is…

Astrophysics · Physics 2009-11-11 G. Perrin , S. Lacour , J. Woillez , E. Thiebaut

We consider a constant $K$-user Gaussian interference channel with $M$ antennas at each transmitter and $N$ antennas at each receiver, denoted as a $(K,M,N)$ channel. Relying on a result on simultaneous Diophantine approximation, a real…

Information Theory · Computer Science 2013-01-29 Mahdi Zamanighomi , Zhengdao Wang

Recently, the generalization behavior of Convolutional Neural Networks (CNN) is gradually transparent through explanation techniques with the frequency components decomposition. However, the importance of the phase spectrum of the image for…

Computer Vision and Pattern Recognition · Computer Science 2021-08-20 Guangyao Chen , Peixi Peng , Li Ma , Jia Li , Lin Du , Yonghong Tian

Scale-ambiguity in 3D scene dimensions leads to magnitude-ambiguity of volumetric densities in neural radiance fields, i.e., the densities double when scene size is halved, and vice versa. We call this property alpha invariance. For NeRFs…

Computer Vision and Pattern Recognition · Computer Science 2024-04-18 Joshua Ahn , Haochen Wang , Raymond A. Yeh , Greg Shakhnarovich

Recovering images from optical interferometric observations is one of the major challenges in the field. Unlike the case of observations at radio wavelengths, in the optical the atmospheric turbulence changes the phases on a very short time…

The systematic evolution of the giant dipole resonance (GDR) width in the temperature region of 0.9 ~ 1.4 MeV has been measured experimentally for 119Sb using alpha induced fusion reaction and employing the LAMBDA high energy photon…

High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition…

Solar and Stellar Astrophysics · Physics 2017-09-20 S. Krishna Prasad , D. B. Jess , T. Van Doorsselaere , G. Verth , R. J. Morton , V. Fedun , R. Erdelyi , D. J. Christian

Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for monitoring surface deformation with high precision. However, low Signal-to-Noise Ratio (SNR) conditions, common in regions with low backscatter, can degrade phase…

Signal Processing · Electrical Eng. & Systems 2025-12-10 Emre Havazli , Shadi Oveisgharan , Michael Denbina , Brian Hawkins

In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a…

The Lyman Alpha damping wing is seen in absorption against the spectra of high-redshift galaxies. Modeling of this wing is a way to measure the volume neutral hydrogen fraction of the Universe, as well as to measure the strength of HI…

Astrophysics of Galaxies · Physics 2025-05-14 Mason Huberty , Claudia Scarlata , Matthew J. Hayes , Simon Gazagnes

Dispersion-based photonics-assisted microwave measurement systems provide immense potential for real-time analysis of wideband and dynamic signals. However, they face two critical challenges: a difficulty in achieving high frequency…

Optics · Physics 2026-02-13 Chi Jiang , Taixia Shi , Hang Yang , Lei Gao , Xianxin Zhang , Yiqing Liu , Yang Chen

Observation of multifrequency angular power spectrum of the redshifted 21-cm brightness temperature fluctuation from the neutral hydrogen holds the key to understand the structure formation and its evolution during the reionization and…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-28 Saikat Gayen , Jais Kumar , Prasun Dutta , Khandakar Md Asif Elahi , Samir Choudhuri , Nirupam Roy

Angle-resolved channel sounding using antenna arrays or mechanically steered high-gain antennas is widely employed at millimeter-wave and terahertz bands. To extract antenna-independent large-scale channel parameters such as path loss,…

Signal Processing · Electrical Eng. & Systems 2026-02-03 Minseok Kim , Masato Yomoda

In this paper, we present an effective data augmentation framework leveraging the Large Language Model (LLM) and Diffusion Model (DM) to tackle the challenges inherent in data-scarce scenarios. Recently, DMs have opened up the possibility…

Computer Vision and Pattern Recognition · Computer Science 2024-09-26 Kyuheon Jung , Yongdeuk Seo , Seongwoo Cho , Jaeyoung Kim , Hyun-seok Min , Sungchul Choi