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A great challenge for 21 cm intensity mapping experiments is the strong foreground radiation which is orders of magnitude brighter than the 21cm signal. Removal of the foreground takes advantage of the fact that its frequency spectrum is…

Instrumentation and Methods for Astrophysics · Physics 2022-06-30 Shijie Sun , Jixia Li , Fengquan Wu , Peter Timbie , Reza Ansari , Jingchao Geng , Huli Shi , Albert Stebbins , Yougang Wang , Juyong Zhang , Xuelei Chen

A wide bandwidth, dual polarized, modified four-square antenna is presented as a feed antenna for radio astronomical measurements. A linear array of these antennas is used as a line-feed for cylindrical reflectors for Tianlai, a radio…

The Tianlai cylinder array is a pathfinder for developing and testing 21cm intensity mapping techniques. In this paper, we use numerical simulation to assess how its measurement is affected by thermal noise and the errors in calibration and…

Instrumentation and Methods for Astrophysics · Physics 2023-12-11 Kaifeng Yu , Fengquan Wu , Shifan Zuo , Jixia Li , Shijie Sun , Yougang Wang , Xuelei Chen

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

Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single,…

Mesoscale and Nanoscale Physics · Physics 2014-07-17 N. Ross , M. Kostylev , R. L. Stamps

We investigate the generation of standing waves in the model provided by the inhomogeneous telegraph equation under different forcing conditions. We show that sustained standing waves arise only for a specific forcing that is spatially…

Classical Physics · Physics 2026-04-21 José Francisco Pérez-Barragán

There is a growing interest in exploiting the terahertz frequency band for future communication systems that demand high data rates. Given the complex propagation behavior of this frequency band, various researchers have developed channel…

Signal Processing · Electrical Eng. & Systems 2022-10-17 Ha Tran , Thanh Le , Suresh Singh

The standing waves existed in radio telescope data are primarily due to reflections among the instruments, which significantly impact the spectrum quality of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Eliminating…

Instrumentation and Methods for Astrophysics · Physics 2025-01-09 Chen Xu , Jie Wang , Yingjie Jing , Fujia Li , Hengqian Gan , Ziming Liu , Tiantian Liang , Qingze Chen , Zerui Liu , Zhipeng Hou , Hao Hu , Huijie Hu , Shijie Huang , Peng Jiang , Chuan-Peng Zhang , Yan Zhu

Terahertz frequencies are an untapped resource for providing high-speed short-range communications. As a result, it is of interest to study the propagation characteristics of terahertz waves and to develop channel models. In previous work…

Signal Processing · Electrical Eng. & Systems 2022-10-17 Thanh Le , Ha Tran , Suresh Singh

The Tianlai Cylinder Pathfinder is a radio interferometer array designed to test techniques for 21 cm intensity mapping in the post-reionization Universe, with the ultimate aim of mapping the large scale structure and measuring cosmological…

We study the time delay of reflected and transmitted waves in 1D disordered media with high transmission. Highly transparent and translucent random media are found in nature or can be synthetically produced. We perform numerical simulations…

Disordered Systems and Neural Networks · Physics 2022-11-30 Luis A. Razo-López , J. A. Méndez-Bermúdez , Victor A. Gopar

In oscillatory reaction-diffusion systems, time-delay feedback can lead to the instability of uniform oscillations with respect to formation of standing waves. Here, we investigate how the presence of additive, Gaussian white noise can…

Statistical Mechanics · Physics 2016-08-17 Michael Stich , Amit K Chattopadhyay

Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase…

The Tianlai Dish Pathfinder array is a radio interferometer array consisting of 16 six meter dish antennas. The original digital backend integration time is at the seconds level, designed for HI intensity mapping experiment. A new digital…

Instrumentation and Methods for Astrophysics · Physics 2022-11-28 Zijie Yu , Furen Deng , Shijie Sun , Chenhui Niu , Jixia Li , Fengquan Wu , Wei-Yang Wang , Yougang Wang , Hui Feng , Lin Shu , Jie Hao , Reza Ansari , Albert Stebbins , Xuelei Chen

We have developed the extension of the exact x-ray resonant magnetic reflectivity theory taking into account the small value of the magnetic terms in the x-ray susceptibility tensor. We have shown that squared standing waves (forth powder…

Mesoscale and Nanoscale Physics · Physics 2018-04-17 Marina A. Andreeva , Poman A. Baulin , Yurii L. Repchenko

We observe intensity oscillations along coronal fan loops associated with the active region AR 11428. The intensity oscillations were triggered by blast waves which were generated due to X-class flares in the distant active region AR 11429.…

Solar and Stellar Astrophysics · Physics 2017-09-20 V. Pant , A. Tiwari , D. Yuan , D. Banerjee

We demonstrate the first successful non-invasive stabilisation of nonlinear travelling waves in a straight cylindrical pipe using time-delayed feedback control (TDF) working in various symmetry subspaces. By using an approximate linear…

Fluid Dynamics · Physics 2025-02-19 Tatsuya Yasuda , Dan Lucas

Time-reflection occurs when a wave is propagating in a medium undergoing a large and abrupt change in its properties: the original wave splits into a time-refracted wave and a time-reflected wave, each displaying different features. The…

We present the science case for surveys with the Tianlai dish array interferometer tuned to the $\left[ 1300, 1400 \right] \mathrm{MHz}$ frequency range. Starting from a realistic generation of mock visibility data according to the survey…

The Tianlai Dish Pathfinder Array is a radio interferometer designed to test techniques for 21~cm intensity mapping in the post-reionization universe as a means for measuring large-scale cosmic structure. It performs drift scans of the sky…

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