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The origin of distorted intensity pattern sensed by a lens and antenna coupled AlGaN/GaN-HEMT terahertz detector

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Chinese Physics B 2019年第11期28卷 388-393页

作者： Xiang Li Jian-Dong Sun Hong-Juan Huang Zhi-Peng Zhang Lin Jin Yun-Fei Sun v v popov Hua Qin Key Laboratory of Nanodevices and Applications Suzhou Institute of Nano-tech and Nano-bionicsChinese Academy of SciencesSuzhou 215123China School of Nano Technology and Nano Bionics University of Science and Technology of ChinaHefei 230026China Nanofabrication Facility of the Suzhou Institute of Nano-tech and Nano-bionics Chinese Academy of SciencesSuzhou 215123China College of Electronic and Information Engineering Suzhou University of Sciences and TechnologySuzhou 215009China Kotelnikov Institute of Radio Engineering and Electronics Saratov BranchRussian Academy of SciencesSaratov 410019Russia

Antenna-coupled field-effect-transistors(FETs) offer high sensitivity for terahertz detection. Both the magnitude and the polarity of the response signal are sensitive to the localized terahertz field under the gate. The ability of accurate sensing the intensity pattern is required for terahertz imaging systems. Here, we report artefacts in the intensity pattern of a focused terahertz beam around 1 THz by scanning a silicon-lens and antenna coupled AlGaN/GaN high-electron-mobility-transistor(HEMT) detector. The origin of the image distortion is found to be connected with one of the antenna blocks by probing the localized photocurrents as a function of the beam location and the frequency. Although the exact distortion is found with our specific antenna design, we believe similar artefacts could be commonplace in antenna-coupled FET terahertz detectors when the beam spot becomes comparable with the antenna size. To eliminate such artefacts, new antenna designs are welcomed to achieve strong asymmetry in the terahertz field distribution under the gate while maintaining a more symmetric radiation pattern for the whole antenna.

关键词： terahertz detector self-mixing high electron mobility transistor local electrical field

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层状矿床的转变

地质科技通报 1990年第2期 58-58页

作者： Y.I.DEMIN ,v.v.popov ,G.F.YAKOvLEv ,余金杰

在调查层状矿床时,最重要的任务是确定变质作用对合矿建造的影响.苏联对不同地区层状硫化物矿床作了这方面的工作.硫化物矿石的变化过程,既可造成矿体的贫化,也可能使其富集.在重晶石-多金属硫化物矿床变质过程中,矿石贫化非常明显.在Ru... 详细信息

在调查层状矿床时,最重要的任务是确定变质作用对合矿建造的影响.苏联对不同地区层状硫化物矿床作了这方面的工作.硫化物矿石的变化过程,既可造成矿体的贫化,也可能使其富集.在重晶石-多金属硫化物矿床变质过程中,矿石贫化非常明显.在Rudnyi Altai(Altai地区含有矿石)大型矿床的基性岩墙和次火山流纹岩的接触带上,部分重晶石变成了钡长石.如果巨大花岗岩大面积侵入的内接触带受到了高温的变质溶液的影响,那么含重晶石的矿石发生一种基本蚀变作用.重晶石与低温硅酸盐反应生成了钡冰长石-钡长石系列的矿物.在这一过程中,高温含

关键词：矿石层状矿床硫化物硫化合物重晶石硫酸盐矿物

Reduction of friction by normal *** of contact stiffness

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Friction 2017年第1期5卷 45-55页

作者： M.popov v.L.popov N.v.popov Berlin University of Technology Berlin 10623 GermanyTomsk Polytechnic University Tomsk 634050 RussiaTomsk State University Tomsk 634050 Russia Berlin University of Technology Berlin 10623 Germany

The present paper is devoted to a theoretical analysis of sliding friction under the influence of oscillations perpendicular to the sliding *** contrast to previous works we analyze the influence of the stiffness of the tribological contact in detail and also consider the case of large oscillation amplitudes at which the contact is lost during a part of the oscillation period,so that the sample starts to 'jump'.It is shown that the macroscopic coefficient of friction is a function of only two dimensionless parameters-a dimensionless sliding velocity and dimensionless oscillation *** function in turn depends on the shape of the contacting *** the present paper,analysis is carried out for two shapes:a flat cylindrical punch and a parabolic *** we consider 'stiff systems',where the contact stiffness is small compared with the stiffness of the *** role of the system stiffness will be studied in more detail in a separate paper.

关键词： sliding friction out-of-plane oscillation contact stiffness coefficient of friction active control of friction

Simulation of detection and scattering of sound waves by the lateral line of a fish

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Chinese Physics B 2022年第2期31卷 398-404页

作者： v M Adamyan I Y popov I v Blinova v v Zavalniuk Odessa I.I.Mechnikov National University Dvoryanskaya Str.2Odesa65082Ukraine ITMO University Kronverkskiy49Saint Petersburg197101Russia Odessa Military Academy 10 Fontanska RoadOdesa 65009Ukraine

A solvable model of lateral line of a fish based on a wave equation with additional boundary conditions on a set of isolated points is *** the framework of this model it is shown that the ratio of pressures on lateral lines on different fish flanks,as well as the cross section of sound scattering on both the lines,strongly depends on angles of incidence of incoming sound *** strong angular dependence of the pressure ratio seems to be sufficient for the fish to determine the directions from which the sound is coming.

关键词： acoustic equation point self-adjoint perturbations of Laplace operator scattering lateral line

Active control of friction by transverse oscillations

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Friction 2019年第1期7卷 74-85页

作者： J.BENAD K.NAKANO v.L.popov M.popov Technische Universit?t Berlin Yokohama National University National Research Tomsk Polytechnic University National Research Tomsk State University

The present paper is devoted to a theoretical analysis of sliding friction under the influence of in-plane oscillations perpendicular to the sliding direction. Contrary to previous studies of this mode of active control of friction, we consider the influence of the stiffness of the tribological contact in detail and show that the contact stiffness plays a central role for small oscillation amplitudes. In the present paper we consider the case of a displacement-controlled system, where the contact stiffness is small compared to the stiffness of the measuring system. It is shown that in this case the macroscopic coefficient of friction is a function of two dimensionless parameters— a dimensionless sliding velocity and dimensionless oscillation amplitude. In the limit of very large oscillation amplitudes, known solutions previously reported in the literature are reproduced. The region of small amplitudes is described for the first time in this paper.

关键词： sliding friction in-plane oscillation contact stiffness coefficient of friction active control of friction

A Model of Irregular Impurity at the Surface of Nanoparticle and Catalytic Activity

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Communications in Theoretical Physics 2012年第7期58卷 55-58页

作者： I.v.Blinova v.v.Gusarov I.Yu.popov St.Petersburg National Research University of Information Technologies Mechanics and OpticsKronverkskiy49St.Petersburg 197101Russia St.Petersburg State Technological Institute (Technical University) Moskovskiy26St.Petersburg 190013Russia

A problem of nanocatalyst improvement is considered. The existence of irregularities at the surface of nanoparticle leads to the increasing of the surface/volume ratio and, correspondingly, to the improvement of the catalytic activity. But this impurity gives one an additional effect due to the change of the electronic density at the surface. We suggest simple model for the description of this effect. The model allows one to find the discrete spectrum of the Schrdinger operator for nanoparticle. Due to this impurity induced bound states the electron density increases near the surface. It leads to the increase of the catalytic activity of nanoparticles with surface impurities.

关键词： semi-infinite crystal operator spectrum impurity catalytic activity nanoparticle

Coercivity kinetics upon step annealing of sintered Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets

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Journal of Rare Earths 2019年第10期37卷 1059-1065页

作者： A.G.popov O.A.Golovnia A.v.Protasov v.S.Gaviko D.A.Kolodkin R.Gopalan M.N.Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences Str.S.Kovalevskoy18Ekaterinburg620990Russia Institute of Natural Sciences and Mathematics Ural Federal Universitypr.MiraEkaterinburg19620002Russia International Advanced Research Centre for Powder Metallurgy and New Materials(ARCI) IITM Research ParkChennai 600113India

Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was *** is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 *** origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 *** enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.

关键词： Sm-Co-Fe-Cu-Zr Permanent magnet Sm2Co17 SmCo5 Coercivity kinetics

Multi-scale polarisation phenomena

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Light(Science & Applications) 2016年第1期5卷 810-818页

作者： vladimir Kalashnikov Sergey v Sergeyev Gunnar Jacobsen Sergei popov Sergei K Turitsyn AIPT Aston UniversityBirminghamWest Midlands B47ETUK Acreo Electrum 236SE-16440KistaSweden Royal Institute of Technology(KTH) SE-1640StockholmSweden

Multi-scale methods that separate different time or spatial scales are among the most powerful techniques in physics,especially in applications that study nonlinear systems with *** the time scales(noise and perturbation)are of the same order,the scales separation becomes ***,the multi-scale approach has to be modified to characterise a variety of noise-induced ***,based on stochastic modelling and analytical study,we demonstrate in terms of the fluctuation-induced phenomena and Hurst R/S analysis metrics that the matching scales of random birefringence and pump–signal states of polarisation interaction in a fibre Raman amplifier results in a new random birefringence-mediated phenomenon,which is similar to stochastic *** observed phenomenon,apart from the fundamental interest,provides a base for advancing multi-scale methods with application to different coupled nonlinear systems ranging from lasers(multimode,mode-locked,random,etc.)to nanostructures(light-mediated conformation of molecules and chemical reactions,Brownian motors,etc.).

关键词： fibre Raman amplifier multi-scale methods polarisation stochastic calculations

Structure,magnetic and adsorption properties of novel FePt/h-BN heteromaterials

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Nano Research 2023年第1期16卷 1473-1481页

作者： Anton S.Konopatsky vladislava v.Kalinina Alena S.Savchenko Denis.v.Leybo Ekaterina v.Sukhanova viktor S.Baidyshev Zakhar I.popov Andrey v.Bondarev Josef Polčák Dmitry v.Shtansky National University of Science and Technology(MISIS) Leninskiy prospect 4Moscow119049Russia Emanuel Institute of Biochemical Physics RAS Kosygina 4Moscow119334Russia Katanov Khakas State University 90 Lenin pr.655017 AbakanRussia Plekhanov Russian University of Economics 36 Stremyanny per.Moscow 117997Russia Department of Control Engineering Faculty of Electrical EngineeringCzech Technical University in PragueTechnicka 2Prague 16627Czech Republic CEITEC-Central European Institute of Technology Brno University of TechnologyPurkyňova 123Brno 61200 BrnoCzech Republic

Nanomaterials with high specific surface area and high absorption capacity are attracting increased interest aimed at imparting the desired magnetic *** work is devoted to the study of the effect of heat treatment in a hydrogen atmosphere on the microstructure,adsorption and magnetic properties of heterogeneous FePt/h-BN *** via the polyol process,FePt nanoparticles(NPs)had a sizever the surface of hexagonal boron nitride(h-BN)*** temperature-activated fcc→fct phase transformation in ultrafine FePt NPs has been well *** NPs act as active centers dissociating H2 molecules and transfer adsorbed hydrogen atoms to the *** functional theory(DFT)calculations also indicate that the h-BN substrate can absorb hydrogen adsorbed on the FePt *** hydrogen circulation in the FePt/h-BN system promoted the fcc→fct phase transformation and allowed to control the magnetic ***/h-BN nanomaterials also exhibited a high adsorption capacity with respect to various organic dyes.

关键词： FePt/h-BN nanomaterials polyol synthesis phase transformations magnetic properties adsorption