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Robust asymmetric Cherenkov radiation in tilted anisotropic medium

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 46-51页

作者： Shuwen Xue Yadong Xu Linkang Han Zhi Ning CHEN Qiaoliang Bao Shan Zhu Huanyang chen Institute of Electromagnetics and Acoustics and Department of Physics College of Physical Science and TechnologyJiujiang Research InstituteXiamen UniversityXiamen 361005China School of Physical Science and Technology Institute of Theoretical and Applied PhysicsSoochow UniversitySuzhou 215006China Department of Electrical and Computer Engineering National University of SingaporeSingapore 8117583Singapore Institute of Energy Materials Science(IEMS) University of Shanghai for Science and TechnologyShanghai 200093China

Cherenkov radiation(CR)is available for a wide variety of terahertz(THz)radiation sources,but its efficiency is deeply affected by intrinsic losses.We find that if the tilted angle(α)of anisotropic material and radiation angle(θ)meet the condition ofθ+α=π/2,the intensity of radiation fields for the charged particle bunch(CPB)moving from left to right cannot be influenced by intrinsic losses,which means long-distance radiation can be achieved.Furthermore,we observe an asymmetric CR when the CPB moves from the opposite direction.In addition,we select natural van der Waals(vd W)materialα-MoO3as an example,further confirming that the radiation field can reach the far field and the asymmetric CR radiation can also be observed.These wonderful properties with long-distance radiation will extend the application of CR to a certain extent for future design and fabrication.

关键词： asymmetric Cherenkov radiation intrinsic losses long-distance radiation

An Overview of Terahertz Antennas

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China Communications 2020年第7期17卷 124-165页

作者： Yejun He Yaling chen Long Zhang Sai-Wai Wong Zhi Ning CHEN Guangdong Engineering Research Center of Base Station Antennas and Propagation Shenzhen Key Laboratory of Antennas and PropagationCollege of Electronics and Information EngineeringShenzhen UniversityShenzhen 518060China Department of Electrical and Computer Engineering National University of Singapore117583Singapore

The terahertz(THz)antennas,which have features of small size,wide frequency bandwidth and high data rate,are important devices for transmitting and receiving THz electromagnetic waves in the emerging THz systems.However,most of THz antennas suffer from relatively high loss and low fabrication precision due to their small sizes in high frequency bands of THz waves.Therefore,this paper presents a detailed overview of the most recent research on the performance improvement of THz antennas.Firstly,the development of THz antennas is briefly reviewed and the basic design ideas of THz antennas are introduced.Then,THz antennas are categorized as metallic antennas,dielectric antennas and new material antennas.After that,the latest research progress in THz photoconductive antennas,THz horn antennas,THz lens antennas,THz microstrip antennas and THz on-chip antennas are discussed.In particular,the practical difficulties for the development of THz antennas are discussed with promising approaches.In addition,this paper also presents a short review of the process technology of THz antennas.Finally,the vital challenges and the future research directions for THz antennas are presented.

关键词： sizes directions dielectric

Metamaterials and Metamaterial-Based Antenna Technology

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上海大学学报（自然科学版） 2014年第5期20卷 531-540页

作者： chen zhi-ning Department of Electrical and Computer Engineering National University of Singapore Singapore117576 Singapore Institute for Infocomm Research Agency of Science Technology and Research Singapore 138632 Singapore

The study of metamaterials is among the most important and attractive topics of the electromagnetic field theory and applications in the past 15 years.Much effort has been devoted to scientific research into the new physical phenomena with great progress.This paper presents the thoughts about the applications of metamaterials in innovative antenna designs from an engineering perspective.The new understanding of metamaterials offers us great possibility to translate the physical concepts of metamaterials in laboratories to innovative antenna designs in practical engineering applications.The technologies have been successfully developed,significantly improving key performances of antennas at microwave and millimeter-wave bands.The recently invented metamaterial-based antennas demonstrate not only wide operating bandwidth,high antenna efficiency,high gain,but also significantly reduced volume with simple mechanical structures.

关键词：材料科技探究声明

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微波超天线技术的研究与发展

中国舰船研究 2022年第5期17卷 45-51页

作者：陈志宁新加坡国立大学电气与计算机工程系新加坡117583

天线技术的发展一直局限于其基本的物理特性。人造结构(即超构材料)的发展具备了独特的电特性,对现有天线设计的性能改善和引入新的功能带来了机会。首先简要介绍超构材料和超构表面的概念。以微波超透镜为例,详细介绍超构表面以及超构... 详细信息

天线技术的发展一直局限于其基本的物理特性。人造结构(即超构材料)的发展具备了独特的电特性,对现有天线设计的性能改善和引入新的功能带来了机会。首先简要介绍超构材料和超构表面的概念。以微波超透镜为例,详细介绍超构表面以及超构表面天线的设计。接着,简要概述微波超天线技术(即基于超构材料和超构表面的天线)的最新研究进展。最后,对微波超天线研究与开发的前景和重点课题进行展望。

关键词：微波超天线超构表面超构材料

Post-exascale supercomputing:research opportunities abound

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Frontiers of Information Technology & Electronic Engineering 2018年第10期19卷 1203-1208页

作者： Zuo-ning chen Jack DONGARRA zhi-wei XU Chinese Academy of Engineering Electrical Engineering and Computer Science Department University of Tennessee Institute of Computing Technology Chinese Academy of Sciences

Exascale supercomputing refers to the scientific research efforts and activities to build and use supercomputers that can perform scientific computing at the speed of exaflops,or 10^(18) floating-point(64-bit)operatio... 详细信息

关键词：计算研究机科学研究浮点操作

Small Extracellular Vesicles Secreted by Peri-urethral Tissues Regulate Fibroblast Function and Contribute to the Pathogenesis of Female Stress Urinary Incontinence

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当代医学科学(英文) 2023年第4期43卷 803-810页

作者： ning chen Xiao-yan SUN zhi-chen DING Jia-qi HU Wen-juan LI Li ZHAN Zhen-wei XIE Department of Gynecology Women's HospitalSchool of MedicineZhejiang UniversityHangzhou 310000China

Objective:This study aimed to explore the existence of small extracellular vesicles(sEVs)in peri-urethral tissues and the role of abnormal expression of sEVs in the pathogenesis of female stress urinary incontinence(SUI).Methods:sEVs were extracted from peri-urethral vaginal wall tissues using differential centrifugation and were observed by transmission electron microscopy(TEM).The number of sEVs and their protein contents were compared between SUI and control groups using nanoparticle tracking analysis(NTA)and bicinchoninic acid(BCA)protein assay.Fibroblasts were cultured separately with SUI(SsEVs group)and normal tissue sEVs(NsEVs group).Proliferation and migration of fibroblasts were compared between groups using CCK-8 and wound healing assays,respectively.Expression levels of collagenⅠandⅢwere compared among blank control(BC),NsEVs,and SsEVs groups using real-time PCR.Protein mass spectrometry was used to test the differentially expressed proteins contained in sEVs between groups.Results:sEVs were extracted and found under the electron microscope.There were significantly more sEVs extracted from the SUI group compared to the normal group.Fibroblasts showed increased proliferative and decreased migratory abilities,and expressed more collagen in the SsEVs group compared to the NsEVs and BC groups.Protein spectrum analysis demonstrated several differentially expressed targets,including components of microfibrils,elastin polymer,and anti-inflammatory factors.Conclusion:sEVs were detected in the peri-urethral tissues.SUI tissues expressed more sEVs than control.The abnormal expression of sEVs and their protein contents may contribute to the pathogenesis and progression of SUI.

关键词： collagen female stress urinary incontinence fibroblasts small extracellular vesicles

Sliding Mode Control of Hydraulic Pressure in Electro-Hydraulic Brake System Based on the Linearization of Higher-Order Model

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Fluid Dynamics & Materials Processing 2020年第3期16卷 513-524页

作者： Qiping chen Haoyu Sun ning Wang zhi Niu Rui Wan Key Laboratory of Conveyance and Equipment Ministry of Education East China Jiaotong UniversityNanchang330013China

The possibility to enhance the stability and robustness of electrohydraulic brake(EHB)systems is considered a subject of great importance in the automotive field.In such a context,the present study focuses on an actuator with a four-way sliding valve and a hydraulic cylinder.A 4-order nonlinear mathematical model is introduced accordingly.Through the linearization of the feedback law of the high order EHB model,a sliding mode control method is proposed for the hydraulic pressure.The hydraulic pressure tracking controls are simulated and analyzed by MATLAB/Simulink soft considering separately different conditions,i.e.,a sine wave,a square wave and a square wave with superimposed sine disturbance.The results show that the proposed strategy can track the target within 0.25 s,and the mean observed error is less than 1.2 bar.Moreover,with such a strategy,faster response and less overshoot are possible,which should be regarded as significant advantages.

关键词： EHB hydraulic pressure feedback linearization sliding mode control

Corrosion Behavior of Fe–Al Coatings Fabricated by Pack Aluminizing Method

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Acta Metallurgica Sinica(English Letters) 2016年第9期29卷 813-819页

作者： ning-ning Li Min-zhi Wang Yong-Sheng Li Guang chen Pei Li Engineering Research Center of Materials Behavior and Design Ministry of Education Nanjing University of Science and Technology

In this study, the two kinds of Fe-Al coatings were fabricated by pack aluminizing on low-carbon steel at different temperatures. The corrosion behavior of the Fe-Al coatings in artificial seawater was investigated by the electrochemical and weight loss techniques. Results show that the thickness of coating layer increases with increasing aluminizing temperature. The coatings exhibit high micro-hardness and good metallurgical bonding with the substrate. In comparison with the steel substrate, the corrosion current density Ico^r of the Fe-AI coatings is always lower than that of substrate, about 1/38 or 1/33 after 2 h immersion, and 1/3 or 1/6 for 720 h immersion. As can be seen from the weight loss curve, the Fe-AI coatings show less loss than that of the substrate within 30-day immersion. The corrosion products formed on the surface of the coatings include oxides of Al, Mg, Fe and Ca, and pitting defect has also been found. The Fe-Al coating with higher content of Fe2Al5 has better corrosion resistance.

关键词： Fe-Al coatin2s： Corrosion： Pack aluminizing： X-rav diffraction

Colorimetric Sensing of Hydrogen Peroxide Based on the Wavelength-Shift of CsPbBr_(3) Perovskite Nanocrystals on Water-Oil Interface

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Journal of Analysis and Testing 2023年第1期7卷 1-7页

作者： Heng-Gan Li Yi-Men Zhu Xue-Lian Liu zhi-Yong Guo Ya-ning Huang Xi chen Department of Civil Engineering and Architecture Wuyi UniversityWuyishan 354300China State Key Laboratory of Marine Environmental Science Xiamen UniversityXiamen 361005China Institute of Analytical Technology and Smart Instruments and College of Environment and Public Healthy Xiamen Huaxia UniversityXiamen 361024China Information Center Xiamen Huaxia UniversityXiamen 361024China

In this study,the halogen exchange reactions are investigated between KI or methylamine iodide in aqueous solution and CsPbBr_(3)NCs in toluene.The mass transfer process on the interface between water and toluene affects the halogen exchange time and e fficiency.Stirring and heating can effectively improve the halogen exchange e fficiency and increases the sensing sensitivity.The photoluminescence wavelength shift of CsPbBr_(3)NCs shows good linear relationship with the concentration of I-in the range from 0 to 20 nmol/L with the detection limit of 0.2 nmol/L I^(-).Taking H_(2)O_(2)as a typical water-soluble oxide,the method is applied to the colorimetric sensing of H_(2)O_(2)in water solution.After the optimization of sensing conditions,the obvious wavelength shift could be observed with the different concentration range of H_(2)O_(2).A good linear relationship between the wavelength shift and the H_(2)O_(2)concentration from 0 to 1.0 mmol/L with the detection limit of 0.05 mmol/L H_(2)O_(2)could be found.

关键词： Halogen exchange Interface reaction CsPbBr_(3)perovskite nanocrystals Photoluminescence wavelength shift Colorimetric sensing