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Extraction of material parameters of a bi-layer structure using Terahertz time-domain spectroscopy

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Science China(Information Sciences) 2014年第8期57卷 238-247页

作者： JIN BiaoBing ZHANG CaiHong SHEN XiaoFang MA JinLong CHEN Jian shi shengcai WU PeiHeng Research Institute of Superconductor Electronics (RISE) School of Electronic Science and EngineeringNanjing University Purple Mountain Observatory Chinese Academy of Sciences Graduate School of Chinese Academy of Sciences Chinese Academy of Sciences

For a bi-layer structure consisting of a film deposited on a substrate,a new extraction method is proposed using which we can extract both the material parameters of the film and the thickness of the substrate from the measured Terahertz transmission through it,so long as the complex refractive index of the substrate is known *** method is applicable to a range of refractive indices of the film less than the refractive index of the substrate and a very wide range of layer thicknesses from 20μm to at least 200μ*** is very useful in some cases where the thickness of the substrate cannot be determined using conventional methods such as a Vernier caliper or micrometer screw.

关键词： material parameter Terahertz spectrum extraction method anti-reflection coating layer THztime-domain spectroscopy

4 K high frequency pulse tube cryocooler used for terahertz space application

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Chinese Science Bulletin 2014年第27期59卷 3490-3494页

作者： Jia Quan Yanjie Liu Dong Liu Kun Zhang Jingtao Liang Jing Li Qijun Yao shengcai shi Key Laboratory of Space Energy Conversion Technologies Technical Institute of Physics and Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences Key laboratory of Radio Astronomy Purple Mountain Observatory Chinese Academy of Sciences

Terahertz(THz) frequency region, defined from0.1 to 10 THz, is an important frequency band for radio astronomy and atmospheric science. As NbN Superconductor-Insulator-Superconductor(SIS) mixers used for terahertz detection, which are studied by the Purple Mountain Observatory(PMO), Chinese Academy of Sciences(CAS), work at 8–10 K, and require condition of micro vibrations, its astronomical observation in aerospace is limited by suitable refrigeration method. 4 K high frequency pulse tube cryocooler developed by Key Laboratory of Space Energy Conversion Technologies(SECT), Technical Institute of Physics and Chemistry(TIPC), CAS, offers an opportunity for the application of SIS mixers. This article introduces the progress of the two-stage high frequency pulse tube cryocooler researched by TIPC. The cryocooler has reached a no load temperature of 4.5 K which is the lowest temperature for this kind of cryocooler reported so far. The successful coupling between the THz component and the high frequency pulse tube cryocooler lays a solid foundation for space detection in the terahertz band.

关键词：脉冲管制冷机太赫兹高频空间应用紫金山天文台能源转换技术重点实验室大气科学

Terahertz atmospheric windows for high angular resolution terahertz astronomy from Dome A

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Advances in Polar Science 2019年第1期30卷 76-80页

作者： Hiroshi MATSUO shengcai shi Scott PAINE Qijun YAO Zhenhui LIN National Astronomical Observatory of Japan Purple Mountain Observatory Key Laboratory of Radio Astronomy Chinese Academy of Sciences Smithsonian Astrophysical Observatory

Atmospheric transmission from Dome A, Antarctica, presents new possibilities in the field of terahertz astronomy, where space telescopes have been the only observational tools until now. Using atmospheric transmission measurements from Dome A with a Fourier transform spectrometer, transmission spectra and long-term stabilities have been analyzed at 1.461 THz, 3.393 THz, 5.786 THz and 7.1 THz, which show that important atmospheric windows for terahertz astronomy open for a reasonable length of time in the winter season. With large aperture terahertz telescopes and interferometers at Dome A, high angular resolution terahertz observations are foreseen of atomic fine-structure lines from ionized gas and a water ice feature from protoplanetary disks.

关键词： terahertz astronomy atmospheric window Fourier transform spectroscopy terahertz telescope terahertz interferometry

超导隧道结在事件视界望远镜黑洞成像及射电天文中的应用

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科学通报 2019年第20期64卷 2067-2069页

作者：史生才李婧中国科学院紫金山天文台南京210034 中国科学院射电天文重点实验室南京210034

2019年4月10日,事件视界望远镜(Event Horizon Telescope,EHT)[1]发布了人类历史上第一张真实的黑洞照片.此次EHT观测集合了横跨四大洲的8台射电天文望远镜(包括JCMT(James Clerk Maxwell Telescope)等6台单天线望远镜和SMA(Submillimeter Array)与ALMA(Atacama Large Millimeter/submillimeter Array)两台干涉阵),观测波段在1.3 mm(即230 GHz频率).基于甚长基线干涉阵(very long baseline interferometer,VLBI)技术形成了一个口径相当于地球直径的单天线望远镜,使其空间分辨率达到天文观测前所未有的20微角秒.需要指出的是,具有最大口径和最高灵敏度的ALMA干涉阵在此次射电星系M87中心黑洞观测中发挥了决定性作用.

关键词：射电天文望远镜中心黑洞事件视界超导隧道结 Maxwell 天文观测应用成像

Development of superconducting mixers for THz astronomy

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Science China(Information Sciences) 2012年第1期55卷 120-126页

作者： shi shengcai1,2 1Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210008,China 2Key Laboratory of Radio Astronomy,Chinese Academy of Sciences,Nanjing 210008,China 1. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China2. Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing 210008 China

The terahertz(THz)regime,loosely defined as 0.1-10 THz,is the last frequency window to be fully explored in *** particular,it is a regime in which there are rich molecular rotation lines and atomic fine structure *** are very important tracers for studying the dynamics of astronomical objects such as stars and planetary *** those spectral lines usually makes use of coherent detectors(i.e.,heterodyne mixers).With sensitivity approaching the quantum limit,superconducting mixers have become the coherent detector of choice in THz *** this paper we mainly introduce the superconducting mixers developed at Purple Mountain Observatory and those for international collaborative projects.

关键词： terahertz detection superconducting mixer quantum limit

Development of series SQUID array with on-chip filter for TES detector

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Chinese Physics B 2022年第2期31卷 665-670页

作者： Wentao Wu Zhirong Lin Zhi Ni Peizhan Li Tiantian Liang Guofeng Zhang Yongliang Wang Liliang Ying Wei Peng Wen Zhang shengcai shi Lixing You Zhen Wang State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology(SIMIT)Chinese Academy of Sciences(CAS)Shanghai 200050China CAS Center for Excellence in Superconducting Electronics(CENSE) Shanghai 200050China University of Chinese Academy of Sciences Beijing 100049China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China University of Science and Technology of China Hefei 230026China

A cold preamplifier based on superconducting quantum interference devices(SQUIDs)is currently the preferred readout technology for the low-noise transition edge sensor(TES).In this work,we have designed and fabricated a series SQUID array(SSA)amplifier for the TES detector readout *** this SSA amplifier,each SQUID cell is composed of a first-order gradiometer formed using two equally large square washers,and an on-chip low pass filter(LPF)as a radiofrequency(RF)choke has been developed to reduce the Josephson oscillation interference between individual SQUID *** addition,a highly symmetric layout has been designed carefully to provide a fully consistent embedded electromagnetic environment and achieve coherent flux *** measured results show smooth V-Φcharacteristics and a swing voltage that increases linearly with increasing SQUID cell number N.A white flux noise level as low as 0.28μφ;/Hz;is achieved at 0.1 K,corresponding to a low current noise level of 7 pA/Hz;.We analyze the measured noise contribution at mK-scale temperatures and find that the dominant noise derives from a combination of the SSA intrinsic noise and the equivalent current noise of the room temperature electronics.

关键词： SSA amplifier TES detectors on-chip low pass filter(LPF) noise contribution

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小华煤矿主排水控制系统改造设计

煤矿机电 2017年第4期38卷 104-106页

作者：施生才福建省永安煤业有限责任公司小华煤矿福建三明366103

针对小华煤矿+580 m主排水系统采用人工手动控制方式存在技术落后、可靠性差及效率低等问题,提出了主排水采用S7-300 PLC自动控制系统的改造方案。重点介绍了该系统的总体方案、工作原理和控制流程。实际应用表明,该改造方案取得了较好... 详细信息

针对小华煤矿+580 m主排水系统采用人工手动控制方式存在技术落后、可靠性差及效率低等问题,提出了主排水采用S7-300 PLC自动控制系统的改造方案。重点介绍了该系统的总体方案、工作原理和控制流程。实际应用表明,该改造方案取得了较好的经济效益。

关键词：主排水泵自动化改造可编程控制系统(PLC) 通信系统

An uncertainty investigation for liner impedance eduction methods

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Chinese Journal of Aeronautics 2024年第3期37卷 49-59页

作者： Weihao shi Xiaodong JING School of Energy and Power Engineering Beihang UniversityBeijing 100191China

Impedance eduction methods have been developed for decades to meet the increasing need for high-quality impedance data in the design and optimization of acoustic *** this end,it is important to fully investigate the uncertainty problem,to which only limited attention has been devoted so *** paper considers the possibility of acoustically-induced structural vibration as a nonnegligible uncertainty or error source in impedance eduction *** the frequency moves away from the resonant frequency,with the increase in the value of cavity reactance,the acoustic particle velocity inside liner orifices possibly decreases to the extent comparable to the vibration velocity of liner facing ***,the acoustically-induced vibration,although generally being weak except at the inherent structural frequencies,may considerably affect the impedance eduction results near the anti-resonant frequency where the liner has poor *** demonstrate the effect of structural vibration,the vibration velocity of liner facing sheet is estimated from the experimentally educed admittance of the liner samples whose orifices are sealed with ***,a three-dimensional numerical model is set up,in which normal particle velocity is introduced over the solid portion of liner facing sheet to imitate structural vibration,rather than directly solving the acoustic-structural coupling *** shown by the results,the vibration of liner facing sheet,whose velocity is as small as estimated by the experiment,can result in anomalous deviation of the educed impedance from the impedance model near the anti-resonant *** trend that the anomalous deviation varies with frequency is numerically captured.

关键词： Impedance eduction Uncertainty analysis Acoustically-induced structural vibration Anti-resonant frequency Perforated liner

No Reference Image Sharpness Assessment Based on Global Color Difference Variation

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Chinese Journal of Electronics 2024年第1期33卷 293-302页

作者： Chenyang shi Yandan LIN School of Artificial Intelligence Anhui Polytechnic University School of Mechanical Engineering Anhui Polytechnic University Department of Light Sources and Illuminating Engineering Fudan University Academy for Engineering & Technology Fudan University

Image quality assessment(IQA) model is designed to measure the image quality in consistent with subjective ratings by computational models. In this research, a valid no reference IQA(NR-IQA) model for color image sharpness assessment is proposed based on local color difference map in a color space. In the proposed model, the absolute color difference variation and relative color difference variation are combined to evaluate sharpness in YIQ color space(a color coordinate system for the development of the United States color television system). The difference between sharpest and blurriest spot of an image is represented by the absolute color difference variation, and relative color difference variation expresses the variation in the image content. Extensive experiments are performed on five publicly available benchmark synthetic blur databases and two real blur databases, and the results prove that the proposed model work better than the other state-of-the-art and latest NR-IQA models for the prediction accuracy on blurry images. Besides, the model maintains the lowest computational complexity.

关键词： Image quality TV Image color analysis Databases Computational modeling Color Predictive models