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arXiv 2021年

作者： Peña, Francisco J. Negrete, Oscar Ma, Ning Vargas, Patricio Reis, Mario Lima, Leandro R.F. Departamento de Física Universidad Técnica Federico Santa María Casilla Valparaíso110-V2390123 Chile Centro para el Desarrollo de la Nanociencia y la Nanotecnología Santiago8320000 Chile Department of Physics College of Physics and Optoelectronic Engineering MOE Key Laboratory of Advanced Transducers Intelligent Control System Taiyuan University of Technology Taiyuan030024 China Institute of Physics Fluminense Federal University Av. Gal. Milton Tavares de Souza s/n Niteroi-RJ24210-346 Brazil Departamento de Física Instituto de Ciências Exatas Universidade Federal Rural do Rio de Janeiro Seropédica - RJ23897-000 Brazil

We theoretically study the thermoelectric transport properties of strained HgTe in the topological insulator phase. We developed a model for the system using a Dirac Hamiltonian including the effect of strain induced by the interface between HgTe and the CdTe substrate. The conductivity tensor was explored assuming the electrons are scattered by charge impurities, while the thermopower tensor was addressed using the Mott relation. Seebeck and Nernst responses exhibit remarkable enhancements in comparison with other two-dimensional Dirac materials, such as graphene, germanane, prosphorene and stanene. The intensity of these termoeletric responses, their dependencies with the external perpendicular magnetic field and temperature are also addressed. Copyright © 2021, The Authors. All rights reserved.

关键词： Cadmium telluride

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Performance Improvement of Raman Distributed Temperature system by Using Noise Suppression

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Photonic Sensors 2018年第2期8卷 103-113页

作者： Jian LI Yunting LI Mingjiang ZHANG Yi LIU Jianzhong ZHANG Baoqiang YAN Dong WANG Baoquan JIN Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education Taiyuan University of Technology Taiyuan 030024 China College of Physics and Optoelectronics Institute of Optoelectronic Engineering Taiyuan University of Technology Taiyuan 030024 China

In Raman distributed temperature system, the key factor for performance improvement is noise suppression, which seriously affects the sensing distance and temperature accuracy. Therefore, we propose and experimentally demonstrate dynamic noise difference algorithm and wavelet transform modulus maximum （WTMM） to de-noising Raman anti-Stokes signal. Experimental results show that the sensing distance can increase from 3 kin to 11.5 km and the temperature accuracy increases to 1.58 ℃ at the sensing distance of 10.4kin.

关键词： Optical fiber sensors Raman scattering noise suppression wavelet transform modulus maximum

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Evaluating entropy rate of laser chaos and shot noise

arXiv

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arXiv 2019年

作者： Guo, Xiaomin Liu, Tong Wang, Lijing Fang, Xin Zhao, Tong Virte, Martin Guo, Yanqiang Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan030024 China Vrije Universiteit Brussel Pleinlaan 2 Brussels1050 Belgium State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi University Taiyuan030006 China

Evaluating entropy rate of high-dimensional chaos and shot noise from analog raw signals remains elusive and important in information security. We experimentally present an accurate assessment of entropy rate for physical process randomness. The entropy generation of optical-feedback laser chaos and physical randomness limit from shot noise are quantified and unambiguously discriminated using the growth rate of average permutation entropy value in memory time. The permutation entropy difference of filtered laser chaos with varying embedding delay time is investigated experimentally and theoretically. High resolution maps of the entropy difference is observed over the range of the injection-feedback parameter space. We also clarify an inverse relationship between the entropy rate and time delay signature of laser chaos over a wide range of parameters. Compared to the original chaos, the time delay signature is suppressed up to 95% with the minimum of 0.015 via frequency-band extractor, and the experiment agrees well with the theory. Our system provides a commendable entropy evaluation and source for physical random number generation. Copyright © 2019, The Authors. All rights reserved.

关键词： Entropy

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High-Speed Physical key Distribution Based on Chaos Synchronization

High-Speed Physical Key Distribution Based on Chaos Synchron...

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Asia Communications and Photonics Conference

作者： Anbang Wang Hua Gao Longsheng Wang Yuncai Wang School of Information Engineering Guangdong University of Technology Guangzhou 510006 China Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Taiyuan 030024 China College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan 030024 China

Physical key distribution is of vital importance to secure communication. We propose and experimentally demonstrate a high-speed physical key distribution scheme using chaos synchronization of multimode semiconductor ... 详细信息

ISBN: (纸本)9781943580705

关键词： Chaos Laser modes Lasers Multimode lasers Quantum key distribution Random number generation

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High-Speed Noise-Based Random Bit Generator by Removing 1/f Noise with Differential Comparison

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Journal of Beijing Institute of Technology 2018年第3期27卷 363-370页

作者： Jianzhong Zhang Xiaoyu Yu Mingjiang Zhang Yi Liu Zhuping Li Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi ProvinceInstitute of Optoelectronic EngineeringCollege of Physics & OptoelectronicsTaiyuan University of Technology

A design scheme of high-speed physical random bit generator is proposed by utilizing a wideband white noise as an entropy *** difference operation between the wideband noise signal and its delayed signal is done to produce a series of binary code by a differential *** D flipflop,which is triggered by a clock,samples the output of the comparator.A random bit sequence at rates of up to 720 Mbit/s is obtained after the exclusive-OR *** differential comparison on noise signals can effectively eliminate 1/f characteristics of the amplified noise,and correct the probability density distribution deviation of noise signal *** quality of the resulting random sequence is verified using common tests of statistical randomness.

关键词： differential comparison noise source 1/f noise random bit generator

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Omnidirectional Conformal Cloak Without Geometrical Dispersion

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Physical Review Applied 2019年第6期12卷 064009-064009页

作者： Yichao Liu Fei Sun Sailing He Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan 030024 China State Key Laboratory of Modern Optical Instrumentations Centre for Optical and Electromagnetic Research JORCEP East Building #5 Zijingang Campus Zhejiang University Hangzhou 310058 China Department of Electromagnetic Engineering School of Electrical Engineering Royal Institute of Technology (KTH) S-100 44 Stockholm Sweden

The phase delay problem of invisibility cloaks designed by optical conformal mapping is referred to the optical path difference between the waves in upper and lower Riemann sheets. As the frequency changes, the phase delay varies accordingly (here, we call it geometrical dispersion), which restricts the cloaks to working only at some discrete frequencies. Here, we solve the phase-delay problem by placing an optically null medium in the lower Riemann sheet. The conformal cloaks designed by using our method have many advantages, such as a continuous working band (no geometrical dispersion), omnidirectionality, robustness under frequency shifts, and no need for any complex materials that are both anisotropic and inhomogeneous. We also design metallic microchannels to realize our cloaks.

关键词： Optical cloaking Devices Optical materials & elements Optical conformal mapping

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Noninvasive super-resolution imaging through scattering media

arXiv

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arXiv 2019年

作者： Wang, Dong Sahoo, Sujit Kumar Dang, Cuong Nanyang Technological University Singapore 50 Nanyang Avenue 639798 Singapore Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan030024 China School of Electrical Sciences Indian Institute of Technology Goa Goa 403401 India

Super-resolution imaging with advanced optical systems has been revolutionizing technical analysis in various fields from biological to physical sciences. However, many objects are hidden by strongly scattering media such as rough wall corners or biological tissues that scramble light paths, create speckle patterns and hinder object’s visualization, let alone super-resolution imaging. Here, we realize a method to do non-invasive super-resolution imaging through scattering media based on stochastic optical scattering localization imaging (SOSLI) technique. Simply by capturing multiple speckle patterns of photo-switchable emitters in our demonstration, the stochastic approach utilizes the speckle correlation properties of scattering media to retrieve an image with more than five-fold resolution enhancement compared to the diffraction limit, while posing no fundamental limit in achieving higher spatial resolution. More importantly, we demonstrate our SOSLI to do non-invasive super-resolution imaging through not only optical diffusers, i.e. static scattering media, but also biological tissues, i.e. dynamic scattering media with decorrelation of up to 80%. Our approach paves the way to non-invasively visualize various samples behind scattering media at unprecedented levels of detail. Copyright © 2019, The Authors. All rights reserved.

关键词： Stochastic systems

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Efficiency enhancement of perovskite solar cells via electrospun CuO nanowires as buffer layers

Efficiency enhancement of perovskite solar cells via electro...

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第五届新型太阳能电池学术研讨会

作者： Qinjun Sun Shaolong Zhou Yuying Hao Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology

CuO nanowires（NWs） with the diameters range from 130 nm to 275 nm have been successfully prepared by electrospinning and calcination technique. Inverted planar heterojunction perovskite solar cells（PSCs） with the structure of ITO/CuO NWs/PEDOT:PSS/CHNHPbI/PCBM/Bphen/Ag were fabricated and a best power conversion efficiency（PCE） of 16.87% was obtained under standard AM 1.5 G simulated solar irradiation, with an average increase of about 21 % compared with that of the control PSCs without CuO NWs. By compared with ZnO NWs with the same diameters and quantitative analysis based on a simple model, we concluded that the improvement of PCE by about 13% can be ascribed to the increase of the PEDOT:PSS/CHNHPbI interface area, and the remaining increase of 8% attributed to the higher hole mobility of CuO NWs/PEDOT:PSS composite film.

关键词： perovskite solar cell CuO nanowires electrospin

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Combination Effect of Cation Vacancies and O2 Adsorption on Ferromagnetism of Na0.5Bi0.5TiO3（100） Surface:ab initio Study

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Chinese Journal of Chemical Physics 2018年第2期31卷 177-183,245页

作者： Lin Ju Ying Dai Tong-shuai Xu Yong-jia Zhang Li Sun School of Physics and Electric Engineering Anyang Normal University Anyang 455000 China School of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Taiyuan 030024 China

The combination effect of cation vacancies and O2 adsorption on ferromagnetism of Na0.5Bi0.5TiO3（100） surface is studied by using density functional theory. An ideal Na0.5Bi0.5TiO3（100） surface is non-magnetic and the cation vacancy could induce the magnetism. By comparing the formation energies for Na, Bi and Ti vacancy, the Na vacancy is more stable than the others. Therefore, we focus on the configuration and electric structure for the system of O2 molecule adsorption on the Na0.5Bi0.5TiO3（100） surface with a Na vacancy. Among the five physisorption configurations we considered, the most likely adsorption position is Na vacancy. The O2 adsorption enhances the magnetism of the system. The contribution of spin polarization is mainly from the O 2p orbitals. The characteristics of exchange coupling are also calculated, which show that the ferromagnetic coupling is favorable. Compared with the previous calculation results, our calculations could explain the room-temperature ferromagnetism of Na0.5Bi0.5TiO3 nanocrytalline powders more reasonably, because of taking into account adsorbed oxygen and cation vacancies. Moreover, our results also show that adsorption of O2 molecule as well as introduction of cation vacancies may be a promising approach to improve multiferroic materials.

关键词： O2 adsorption Cation vacancies Ferromagnetism First-principles calculation

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The distributed parameter model of hydraulic axial piston motor and its application in hydraulic excavator swing system

The distributed parameter model of hydraulic axial piston mo...

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作者： Gao, Youshan Huang, Weinan Quan, Long Lan, Yuan Huang, Jiahai Key Laboratory of Advance Transducers and Intelligent Control System Ministry of Education School of Mechanical Engineering Taiyuan University of Technology Taiyuan030024 China School of Mechanical Engineering Taiyuan University of Science and Technology Taiyuan China

Hydraulic axial piston motor is one of the fundamental components in hydraulic systems;it is widely used in engineered machine, especially in high-power drive or reciprocating motion, such as hydraulic excavator. For hydraulic axial piston motor efficient planning, in addition designing and controlling are required for system operating safety and efficiency. Simulation delivers an advantage over analytical approaches and allows better understanding of the motor performance. For multi-piston hydraulic motor, one of the simulation methods, distributed parameter model, could analyze the detailed performance in each piston chamber. Therefore, in this study, we investigate the characteristics of hydraulic axial piston motor by setting up a distributed parameter model based on physical prototype, which includes mechanical-hydraulics coupling process. The effects of the dynamic pressure inside the piston chamber, the fluidic compressibility and other related parameters are considered in the coupling process. At the same time, the distributed parameter model of hydraulic axial piston motor was used in the simulation model of hydraulic excavator. The results indicate that in two-way hydraulic axial piston motor, the valve plane should adopt symmetrical structure, and silencing groove set should be put on both ends of the valve plane slots, which could reduce pressure ripple and overshoot in the piston chamber. Furthermore, the torque characteristics are highly affected by the clearance between the piston and the cylinder bore. Through this research, we may have a better understanding about the mechanism of output torque fluctuation in hydraulic axial piston motor, and the pressure ripple and overshoot in the piston chamber due to through-flow area discontinuity between the silencing groove and the ends of the valve plane slots. The model is verified using a nine-piston hydraulic motor in hydraulic excavator. © Institution of Mechanical Engineers.

关键词： Pistons

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