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A radio interferometer indirectly measures the intensity distribution of the sky over the celestial sphere. Since measurements are made over an irregularly sampled Fourier plane, synthesising an intensity image from interferometric…

Instrumentation and Methods for Astrophysics · Physics 2014-03-18 Daniel Muscat

The high-frequency vibration of the imaging system degrades the quality of the reconstruction of ptychography by acting as a low-pass filter on ideal diffraction patterns. In this study, we demonstrate that by subtracting the deliberately…

Instrumentation and Detectors · Physics 2017-06-07 Yudong Yao , Cheng Liu , Jianqiang Zhu

Most existing MRI reconstruction methods perform tar-geted reconstruction of the entire MR image without tak-ing specific tissue regions into consideration. This may fail to emphasize the reconstruction accuracy on im-portant tissues for…

Image and Video Processing · Electrical Eng. & Systems 2023-09-06 Yu Guan , Chuanming Yu , Shiyu Lu , Zhuoxu Cui , Dong Liang , Qiegen Liu

Visibility-visibility correlation has been proposed as a technique for the estimation of power spectrum, and used extensively for small field of view observations, where the effect of $w-term$ is usually ignored. We consider power spectrum…

Instrumentation and Methods for Astrophysics · Physics 2015-05-14 Prasun Dutta , Tapomoy Guha Sarkar , S. Pratik Khastgir

In this study, we propose a wideband index modulation (IM) based on circularly-shifted chirps. To derive the proposed method, we first prove that a Golay complementary pair (GCP) can be constructed by linearly combining the Fourier series…

Signal Processing · Electrical Eng. & Systems 2020-10-27 Safi Shams Muhtasimul Hoque , Chao-Yu Chen , Alphan Sahin

Magnetic resonance fingerprinting (MRF) is able to estimate multiple quantitative tissue parameters from a relatively short acquisition. The main characteristic of an MRF sequence is the simultaneous application of (a) transient states…

Medical Physics · Physics 2019-02-26 Christiaan C. Stolk , Alessandro Sbrizzi

We report on a broader evaluation of statistical bootstrap resampling methods as a tool for pixel-level calibration and imaging fidelity assessment in radio interferometry. Pixel-level imaging fidelity assessment is a challenging problem,…

Instrumentation and Methods for Astrophysics · Physics 2015-05-14 Athol Kemball , Adam Martinsek , Modhurita Mitra , Hsin-Fang Chiang

The technique of non-redundant masking (NRM) transforms a conventional telescope into an interferometric array. In practice, this provides a much better constrained point spread function than a filled aperture and thus higher resolution…

Instrumentation and Methods for Astrophysics · Physics 2017-11-29 Steph Sallum , Josh Eisner

We present a mathematical analysis of propagation-induced distortions in the spectro-temporal properties of Fast Radio Bursts (FRBs). Within the Triggered Relativistic Dynamical Model, we derive a centroid-based formulation of the sub-burst…

High Energy Astrophysical Phenomena · Physics 2025-10-21 Aishwarya Kumar , Fereshteh Rajabi , Martin Houde

We present a study of the effects of dispersion on the properties of photon pairs generated by type-II, collinear spontaneous parametric downconversion. Specifically, we take into consideration the effects of a chirped pump, as well as of…

Quantum Physics · Physics 2009-04-27 Yasser Jeronimo-Moreno , Alfred B. U'Ren

Large-scale astronomical surveys can capture numerous images of celestial objects, including galaxies and nebulae. Analysing and processing these images can reveal intricate internal structures of these objects, allowing researchers to…

Instrumentation and Methods for Astrophysics · Physics 2023-11-02 Peng Jia , Jiameng Lv , Runyu Ning , Yu Song , Nan Li , Kaifan Ji , Chenzhou Cui , Shanshan Li

Previous studies of the modulation instability (MI) of continuous waves (CWs) in a two-core fiber (TCF) did not consider effects caused by co-propagation of the two polarized modes in a TCF that possesses birefringence, such as cross-phase…

Optics · Physics 2012-07-03 J. H. Li , K. S. Chiang , B. A. Malomed , K. W. Chow

In this study, we investigate the effects of chromatic dispersion on single-photon temporal wave functions (TWFs) in the context of quantum communications. Departing from classical beam analysis, we focus on the temporal shape of single…

Quantum Physics · Physics 2024-10-10 Artur Czerwinski , Xiangji Cai , Saeed Haddadi

Photonic crystal fibers are used in fiber amplifiers and lasers because of the flexibility in the design of mode area and dispersion. However, these quantities depend strongly on the wavelength. The wavelength dependence of gain,…

Optics · Physics 2009-11-11 A. Huttunen , P. Torma

This work investigates the temporal dispersion of a wireless terahertz communication signal caused by reflection from a rough (diffuse) surface, and its subsequent impact on symbol error rate versus data rate. Broadband measurements of…

Signal Processing · Electrical Eng. & Systems 2021-04-02 Russ Messenger , Karl Strecker , Sabit Ekin , John O'Hara

The reflection coefficient of bulk spin waves from multilayer ferromagnetic structure with periodically modulated parameters of exchange interaction, uniaxial and rhombic magnetic anisotropy and saturation magnetization is calculated with a…

Materials Science · Physics 2009-01-15 Sergey A Reshetnyak , Tat'yana A Homenko

Rotation measure synthesis allows the estimation of Faraday dispersion via a Fourier transform and is the primary tool to probe cosmic magnetic fields. We show this can be considered mathematically equivalent to the one dimensional…

Instrumentation and Methods for Astrophysics · Physics 2020-05-13 Luke Pratley , Melanie Johnston-Hollitt

Deconvolution of the telescope Point Spread Function (PSF) is necessary for even moderate dynamic range imaging with interferometric telescopes. The process of deconvolution can be treated as a search for a model image such that the…

Astrophysics · Physics 2009-11-10 S. Bhatnagar , T. J. Cornwell

We present an approach for improving spatial frequency sampling in active incoherent millimeter-wave (AIM) imaging systems using frequency diversity. AIM imaging relies on active transmission of spatio-temporally incoherent signals to…

Signal Processing · Electrical Eng. & Systems 2025-03-12 Jorge R. Colon-Berrios , Jeffrey A. Nanzer

Inadequacies in the knowledge of the primary beam response of current interferometric arrays often form a limitation to the image fidelity. We hope to overcome these limitations by constructing a frequency-resolved, full-polarization…

Astrophysics · Physics 2009-11-13 Attila Popping , Robert Braun