bluuebunny/crossref_metadata_2025 huggingface dataset:
High-density array of Au nanowires coupled by plasmon modes
Authors: Yan Hong-Dan  , Peter Lemmens  , Johannes Ahrens  , Martin Bröring  , Sven Burger  , Winfried Daum  , Gerhard Lilienkamp  , Sandra Korte  , Aidin Lak  , Meinhard Schilling  ,   Institute for Condensed Matter Physics, Technische Universität Carolo-Wilhelmina, Braunschweig, Germany 38106;,   International Graduate School of Metrology, Technische Universität Carolo-Wilhelmina, Braunschweig, Germany 38106;,   Institut für Anorganische und Analytische Chemie, Technische Universität Carolo-Wilhelmina, Braunschweig, Germany 38106;,   Konrad-Zuse-Zentrum für Informationstechnik, Berlin, Germany 14195;,   Institute of Energy Research and Physical Technologies, Technische Universität Clausthal, Clausthal-Zellerfeld, Germany 38678;,   Institute of Electrical Measurement and Fundamental Electrical Engineering, Technische Universität Carolo-Wilhelmina, Braunschweig, Germany 38106
Published: December 2020

Au nanowire arrays with high aspect ratios are prepared in anode aluminum oxide templates by electrochemical deposition. The obtained structures are investigated by scanning Auger microscopy. Surface plasmon resonances of Au nanowire arrays induce a transverse mode (T mode) and a longitudinal mode (L mode) in the optical absorption, which indicates the strong anisotropy of the Au nanowires. The L mode intensity is related to the angle and polarization of the incident light. The L mode position shows a shift with the increase of aspect ratio of the nanowires. The plasmon coupling between Au nanowires is compared with the H-aggregation of organic chromophores. The blue shift of the L mode in the arrays compared with a single nanowire is induced by multi-coupling of the electromagnetic field between neighbouring nanowires. A finite element method is used to simulate the electric field distributions of a single Au nanowire and an array of plasmonically coupled wires.
The analysis on the properties of light field distribution in one-dimensional photon crystals
Authors: Liu Xiao-Jing  , Zhang Bo-Jun  , Wang Jing  , Zhang Si-Qi  , Ba Nuo  , Li Hong  , Wu Xiang-Yao  , Guo Yi-Qing  ,   Institute of Physics, Jilin Normal University, Siping 136000, China;,   Institute of High Energy Physics, Chinese Academy of Siences, Beijing 100049, China
Published: December 2020

In this paper, we give the expressions of transmissivity, reflectivity and the distribution of election field in a photon crystal at an arbitrary incidence angle. We investigate the field intensity when angle frequency of incidence light is odd or even times the fundamental frequency in photon crystal. Besides, we study the effects of incidence angle, the incident direction of light and defect layer on election field distribution, and obtain some new and valuable results. We expect the research results to be helpful for designing photonic crystals.
Structure and optical properties of TeO2-Nb2O5-BaCl2 glass
Authors: Zhao Yue-Zhi  , Liao Gui-Hua  , Chen Wen-Juan  , Cao Qin-Cun  ,   Department of Material and Engineering, Luoyang Institude of Science and Technology, Luoyang 471023, China
Published: December 2020

Oxygen-chlorine tellurite glasses: (90-x)TeO2-10Nb2O5-xBaCl2 (x=10, 20, 30) are prepared using the conventional melting method. The influences of component on the density, structure, optical properties, refractive index and dispersion of the glasses are studied using density specific gravity balance, Raman spectroscopy, infrared-visible-UV spectrophotometer and Prism Coupler. The results show that the glass density first increases and then decreases with the increase of content of BaCl2. Furthermore, the structural units are converted from [TeO4] trigonal bipyramid into [TeO3] trigonal pyramid. Moreover, glass refractive index gradually decreases. In addition, new tellurite glass has high linear refractive index n (2.02259), nonlinear refractive index N2 (6.8× 10-12 esu) and third-order nonlinearpolarizability χ(3)(3.7× 10-13 esu). The new tellurite glass exhibits a high transmittance in the visible and infrared spectral region and possesses an cut-off edge in the near UV spectral region, and they each undergo an obvious blue shift with the increase of content of BaCl2. The direct and indirect transition optical band gaps of the samples are calculated according to the Tauc equation, and they increase with the content of BaCl2 increasing.
Studies on the composition of InGaN/AlN quantum dots grown by molecular beam epitaxy
Authors: Hu Yi-Bin  , Hao Zhi-Biao  , Hu Jian-Nan  , Niu Lang  , Wang Lai  , Luo Yi  ,   Tsinghua National Laboratory for Information Science and Technology Deptment of Electronic Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

In this article we report on the green-light wavelength InGaN/AlN quantum dots (QDs) grown by molecular beam epitaxy, and propose a method to determine the composition of the InGaN QDs by combining reflection high-energy electron diffraction in-situ measurement and photoluminescence measurement, in which the strain relaxation and the influences of strain and quantum-confined Stark effect on the exciton energy are taken into consideration.
Analysis of the near-field-far-field pattern of tilted planar antenna arrays
Authors: Liu Jun-Qun  ,   Nanjing Research Institute of Electronics Technology, Nanjing 210039, China
Published: December 2020

Based on the principle of planar near-field measurement and theory on the spatial pattern of planar antenna arrays, a comprehensive investigation on the spatial pattern of planar antenna arrays tilting away from the planar near-field scanning plane is performed. An efficient computational algorithm on the near-field-far-field pattern in the plane determined by the rotation axis and normal line of the tilted array is developed. The parametric equations on the intersecting curve locus between the plane and unit directional sphere of the planar near-field scanning are thus derived. Consequently, the spatial pattern of the tilted antenna array based on the near-field data is calculated by fast Fourier transform technique, and at the same time a two-dimensional interpolating scheme to evaluate the pattern in the plane is developed. The capability, efficiency, and feasibility of this new algorithm are demonstrated by the good consistency of the calculated results with the numerical simulations and experimental measurements.
Quantum teleportation using superconducting charge qubits in thermal equilibrium
Authors: Qiao Pan-Pan  , Ahmad Abliz  , Cai Jiang-Tao  , Lu Jun-Zhe  , Maimaitiyiming Tusun  , Ribigu Maimaitiming  ,   School of Physics and Electronic Engineering, Xinjiang Normal University, Urumchi 830054, China;,   State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Is this paper we mainly investigate the effects of the temperature and Josephson energy on teleportation of one qubit state in both the standard and the non-standard protocols as well as the partial teleportation of an entangled state under the standard protocol via two identical superconducting charge qubits in thermal equilibrium as the teleportation channel, and give the analytical expression of the average fidelity. Our results show that the teleportation of one qubit state in non-standard protocol and the partial teleportation of entanglement in standard protocol can be almost perfect, indicating that quantum teleportation, with using superconducting charge qubits in thermal equilibrium as a quantum channel, is feasible in theory.
On the scheme of cavity photon elimination in multi-qubit circuit-quantum electrodynamics system
Authors: Meng Jian-Yu  , Wang Pei-Yue  , Feng Wei  , Yang Guo-Jian  , Li Xin-Qi  ,   Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

Solid-state superconducting circuit-quantum electrodynamics (QED) system is a promising candidate for quantum information processing and an ideal platform for quantum measurement and quantum control studies. As an extension to our previous simulation for single qubit circuit-QED, in this work we simulate the quantum measurement and control of multi-qubit system. Particularly, we consider the deterministic generation of a two-qubit Bell state. In this context we examine the validity conditions of two cavity-photon-elimination scheme. On the level of quantum trajectory simulation, we find that, owing to the qubit flip caused by feedback, the advanced polaron-transformation scheme is no longer applicable if the measurement is not weak, which also makes meaningless the elegant effective measurement operator.
Subcarrier multiplexing quantum key distribution based on polarization coding
Authors: Zhao Gu-Hao  , Zhao Shang-Hong  , Yao Zhou-Shi  , Meng Wen  , Wang Xiang  , Zhu Zhi-Hang  , Liu Feng  ,   The Telecommunication Engineering Institute, Air Force Engineering University, Xi'an 710077, China;,   Xi'an Branch of China Academy of Space Technology, Xi'an 710000, China
Published: December 2020

A subcarrier multiplexing quantum key distribution is based on phase modulation polarization coding scheme. The key could be shared by several parallel sideband channels, and each sideband has a random and independent polarization which is synthesized by controlling the phase difference of subcarriers in two electro-optical phase modulators. The key rate could be increased multiply. The simulation result shows that the scheme works well.
Modulation of nonlinear coupling on the synchronization induced by linear coupling
Authors: Li Fan  , Jin Wu-Yin  , Ma Jun  ,   Department of Physics, Lanzhou University of Technology, Lanzhou 730050, China;,   College of Mechano-Electronic Engineering, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

Based on the Lyapunov stability theory, the Lyapunov function in the form of exponential type is constructed. The four-variable Chen hyperchaotic model is investigated as an example. The reliability of a linear coupling-inudced synchronization of hyperchaotic system is proofed analytically. Furthermore, the modulation effect of nonlinear coupling on the synchronization induced by linear coupling is investigated. A statictical function is defined to evaulate the power consumption of controller according to the dimensionaless dynamical equations, the appropriate parameter region for synchronization due to the joint action of linear and nonlinear coupling, and the extensive numerical results confirm the correctress of the theoretical predication.
Experimental research on synchronous rhythms of biological network composed of heterogeneous cells
Authors: Jia Bing  , Gu Hua-Guang  ,   School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
Published: December 2020

The evolution of the dynamic behaviors of beating rhythms from independent states to the formation of network is studied in biological experiment on two heterogeneous cells. The beating rhythms are independent and not synchronous when there is no coupling between two cells. With the enhancement of the coupling strength, the mean and maximum of absolute value of the phase difference drastically decrease in the beating rhythms of the two cells, from non-phase synchronization to phase synchronization, eventually not to full synchronization. Some of beatings become synchronous while others not synchronous for non-synchronization states while all beatings are synchronous for the phase synchronization state. With the increase of coupling strength, the times of synchronized beatings increases for the non-phase synchronization state, and time interval between the corresponding synchronous beatings of the two cells decreases to a low but non-zero value for the phase synchronization state. The results not only provide experimental demonstration of rhythm synchronization in a biological network, but also give changing regularity in the forming process of synchronous rhythm in the heterogeneous network.
Two-dimensional reconstructions of gas temperature and concentration in combustion based on tunable diode laser absorption spectroscopy
Authors: Song Jun-Ling  , Hong Yan-Ji  , Wang Guang-Yu  , Pan Hu  ,   State Key Laboratory of Laser Propulsion and Applications, Academy of Equipment, Beijing 101416, China
Published: December 2020

Based on the tunable diode laser absorption spectroscopy, the combustion gas concentration and temperature distribution are reconstructed using algebraic iterative reconstruction technique (ART). Time division multiplexing technology is adopted to scan two H2O absorption transitions (7205.25 cm-1 and 7416.05 cm-1) simultaneously at 1 kHz repetition rate. The influences of projected angle and the number of beams on the temperature and concentration field reconstruction are studied. Compared with the thermocouple readings, the temperature distribution reconstruction has a well agreement except a low temperature area in the middle of the combustion field. Aiming to achieve an optimal reconstruction with a limited number of beams, a few virtual beams are added to the ART method. Through this method, the effectivenesses of temperature and concentration field reconstructions increase, but there is not an obvious improvement when a large gradient of temperature exists between two lines.
A methode of estimating the reflectivity and refractive-index modulation of double-cladding large core fiber Bragg grating
Authors: Zhou Ren-Lai  , Ju You-Lun  , Yang Chao  , Wang Wei  , Wang Yue-Zhu  ,   National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, No. 2, Yikuang Street, Nangang District, Harbin 150080, China
Published: December 2020

A simple and practical method of estimating reflectivity and refractive-index modulation is reported when writing fiber Bragg grating (FBG) into silica fiber core based on 800 nm femtosecond laser pulses and a phase mask. By monitoring and recording the variation of the fiber laser output power, the reflectivity and refractive-index modulation are estimated theoretically and experimentally. The reflectivity of FBG is approximate 96.4%, and the refractive-index modulation is about 1.2×10-3. When the FBG is used as a linear cavity mirror, 15.5 W of output power is obtained under an incident pump power of 51.6 W, corresponding to a slop efficiency of 37.9%. A beam factor of M2=1.4 at an output power of 15 W is measured by using the knife-edge method.
The method of undetermined tensor for constructing Birkhoffian functions
Authors: Cui Jin-Chao  , Song Duan  , Guo Yong-Xin  ,   School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China;,   College of Physics, Liaoning University, Shenyang 110036, China;,   Physics of medical imaging department, Eastern Liaoning University, Dandong 118001, China
Published: December 2020

The method of constructing Birkhoffian and Birkhoffian funcations of mechanical system is studied. Based on the conditions of self-adjointness and integrability conditions of linear partial differential equations, a method of undetermined tensor for constructing Birkhoffian and Birkhoffian funcations of mechanical systems is given. Two examples are given to illustrate the application of the results.
Characteristic analysis of traffic flow in variable speed limit section of freeway based on cellular automaton model
Authors: Zhang Jing-Jing  , Pang Ming-Bao  , Ren Sha-Sha  ,   School of Civil Engineering, Hebei University of Technology, Tianjin 300401, China
Published: December 2020

Based on symmetric two-lane Nagel-Schreckenberg (STNS) model, a cellular automaton model of variable speed limit section in freeway is established with access to real-time traffic information of intelligent transportation system (ITS). The effects are discussed about how the different speed limit values, the lengths of speed limit section, and the different traffic states affect the traffic flow and the traffic volume via the simulation experiment of dynamic speed control. The effectual condition of speed limit is analyzed. The results of the examples show that speed limit can be used solely under some traffic states as an assistant traffic management strategy. The traffic jam phenomena can be suppressed and the goal of achieving a largest traffic flow and reducing the passing time of vehicles can be realized by using the dynamic speed control method with the different speed limit values and lengths under some traffic states.
Control of the spatiotemporal pattern with time delayed feedback in a gas discharge system
Authors: He Ya-Feng  , Feng Xiao-Min  , Zhang Liang  ,   Hebei Key Laboratory of Optic-electronic Information Materials, College of Physical Science and Technology, Hebei University, Baoding 071002, China;,   College of Career Technology, Hebei Normal University, Shijiazhuang 050024, China
Published: December 2020

Control of the spatiotemporal pattern with time delayed feedback in a gas discharge system is studied both analytically and numerically. The time delay in the semiphenomenological model is reduced as a perturbation. Based on the linear stability analysis, the effects of the time delay on the Turing and the Hopf modes near the Turing-Hopf codimension-two phase space are investigated. Then, the relations between the parameters of feedback and the oscillatory frequency, and the critical wavelength of the system are obtained. Results show that the transition between patterns can be controlled effectively by applying appropriate feedback even when the applied voltage keeps constant. The consequence of increasing the feedback intensity or the delayed time is equivalent to increasing the applied voltage. Furthermore, the analytical results are verified by two-dimensional numerical simulation. Our work proposes a way to control the pattern formation in a gas discharge system.
Thermal expansion behaviors and phase transitions of HMX polymorphs via ReaxFF molecular dynamics simulations
Authors: Zhou Ting-Ting  , Huang Feng-Lei  ,   State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, Chian
Published: December 2020

The response to temperature of HMX polymorph is important for understanding the sensitivity, stability, and phase transitions of energetic material. Using ReaxFF-lg with isothermal-isobaric molecular dynamics (NPT-MD) methods, the crystal and molecular structures of -, -, and -HMX crystals in a temperature range of 303-503 K and at atmospheric pressure are investigated. The calculated crystal structures and thermal expansion coefficients are in general agreements with experimental results, indicating that ReaxFF-lg potential can correctly describe the thermal expansion of HMX polymorph. The linear thermal expansion coefficients indicate that the thermal expansion of -HMX is anisotropic, the thermal expansion along c axis is slightly different from those for a and b axes for -HMX, and the thermal expansion along a, b, and c axes are almost the same for -HMX. The volume expansion coefficients for the three phases decrease in the following sequence: -HMX-HMXHMX, showing that -HMX is the most sensitive to temperature in the three crystals, which may be the reason for higher sensitivity of this phase. Sharp changes in lattice parameter and molecular conformation transformation from chair to boat-chair occur for HMX when temperature reaches 443 K. Helmholtz free energy derived from the two-phase thermodynamics (2PT) model suggests a phase transition for HMX at T=423-443 K. The , -, and -HMX crystals are stable in the temperature ranges of 303-423 K, 443-503 K, and 363-423 K, respectively.
Electronic structure and magnetic properties in C-doped BaTiO3: A first-principles calculations
Authors: Tan Xing-Yi  , Chen Chang-Le  , Jin Ke-Xin  , Gao Yan-Jun  ,   School of Science, Hubei University for Nationalities, Enshi 445000, China;,   Shannxi Key Laboratory of Condensed Matter Structures and Properties, School of Science, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

Based on density functional theory calculations, the electronic structure and magnetic properties of C-doped BaTiO3 are investigated. It is found that the BaTiO3 doped by a nonmagnetic 2p light element (C) is ferromagnetic. The local magnetic moment is mainly localized on doped C atoms for Csub, while ferromagnetism in Cins comes from precipitation of magnetic ions Ti3+. Our results indicate that the proposed C-doped BaTiO3 is a potential candidate for dilute magnetic semiconductor material and multiferroics material.
Fe3Si8M ternary alloy thin films prepared by magnetron sputtering
Authors: Li Xiao-Na  , Zheng Yue-Hong  , Li Sheng-Bin  , Dong Chuang  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beam, Ministry of Eduction, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
Published: December 2020

FeSi2 is a promising environment-friendly semiconductor material. However it is difficult to obtain pure phase for such a line compound. To investigate the solubilities for a third alloying elements, in this work Fe3Si8M (M=B, Cr, Ni, Co) ternary alloys are designed based on the cluster-plus-glue-atom-model. Thin films are then prepared using magnetron sputtering. The as-deposited films are all amorphous and become crystallized after annealing at 850 for 4 h. It is shown that samples alloyed with third components Cr and B can reach single phase easily. However, the main phase is phase and the films tend to exhibit metallic characteristics while alloyed with Co. Of these films, the Fe2.7Si8.4B0.9 film presents the most prominent semiconductor performance, and it has a resistivity of 0.17 cm, a sheet carrier concentration of 2.81020 cm-3, a mobility of 0.13 cm2=Vs and a band-gap width of 0.65 eV. It is confirmed that doping a proper third component can expand the phase zone, exhibiting a similar semiconductor property to that of binary -FeSi2.
Routing strategy for complex networks based on gravitation field theory
Authors: Liu Gang  , Li Yong-Shu  ,   Faculty of Geosciences and Environmental Engineering, Southwest JiaoTong University, Chengdu 610031, China
Published: December 2020

Using the theory of gravitational field, we study the gravitational field induced by the node in the process of the network transmission, establish the gravitational filed equation, and define two parameters α and γ for adjusting the dependencs of transmission data on the unblocked degree of node, the transmission capacity of node and the path length. Based on the gravitational field of node, an efficient routing strategy is proposed, and the package will be transferred along the route with maximum gravitation. In order to characterize the efficiency of the method, we introduce an order parameter η to measure the throughput of the network by the critical value of phase transition from free state to jammed state, and use the node betweenness centrality B to test the transmission efficiency of network and the congestion distribution. We simulate the network transmission efficiencies under different values of α and γ. Simulation results show that compared with the traditional shortest routing strategy, our routing strategy improves the network capacity several times, and effectively balances the distribution of the betweenness centrality of nodes, and the average path length Lavg> shows a trend from ascent to descent with the increase of load amount R, and the change of the parameters α and γ nearly have no effect on the network transmission capacity, which suggests the efficiency of our routing strategy is independent of α and γ, the network capacities are approximately equal for any values of α and γ in the feasible region.
Modeling of carbon nanotube field effect transistor with phonon scattering
Authors: Zhao Xiao-Hui  , Cai Li  , Zhang Peng  ,   The Sciences Institute of Air Force Engineering University, Xi’an 710051, China;,   The Engineering Institute of Air Force Engineering University, Xi'an 710038, China
Published: December 2020

Phonon scattering has a non-negligible influence on the characteristics of carbon nanotube field effect transistor (CNTFET). Using the ballistic transport model, the device parameters under phonon scattering are analyzed, and then the CNTFET phonon scattering model is established. To reduce the complexity of this model so that simulation speed can be improved, the effects of phonon scattering is studied through analyzing chirality, temperature and energy, and therefore a new CNTFET phonon scattering model is established with linear approximation. By analyzing the scattering current changes, correctness and validity of the model are demonstrated. The proposed model is easier for calculation and has less computational complexity compared with semi-classical scattering model.
High-speed truly random number generator based on the random time distribution of single photons
Authors: Wang Long  , Ma Hai-Qiang  , Li Shen  , Wei Ke-Jin  ,   School of Sciences, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100876, China
Published: December 2020

In this paper, we present a high-speed physical quantum random number generator using analog/digital converter (ADC), which is based on the random time distribution of single photons emitted by the stongly attenuated pulsed laser diode. With this scheme, the generation rate of random numbers can increase more than tenfold. A preliminary experiment consists of the time amplitude converter and 16 bit ADC, and the data generated by the system pass the pseudo-random number test program test standards. The experimental setup is efficient and robust against mechanical and temperature disturbances.
Canonical quantization of dirac field in a finite volume
Authors: Wang Qing  , Long Zheng-Wen  , Luo Cui-Bai  ,   School of Physics Science and Technology, Xinjiang University, Xinjiang 830046, China;,   Department of Physics, Guizhou University, Guiyang 550025, China
Published: December 2020

The canonical quantization of Dirac field in a finite volume is studied. Following the idea of taking the boundary conditions as primary Dirac constraints, we propose a method to treat both the intrinsic constraints and boundary conditions equally. We shall work in the discrete version and quantize the model canonically. In order to verify our method to treat the intrinsic constraints and boundary conditions on the same footing, we obtain the same results by choosing two different subsets of constraints to construct the intermediate Dirac brackets.
Molecular dynamics simulation of surface energy of low miller index surfaces in UO2
Authors: Xiao Hong-Xing  , Long Chong-Sheng  ,   National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu 610041, China
Published: December 2020

Molecular dynamics simulation based on the rigid-ion potential is carried out to investigate the surface energies of low miller index crystallographic faces such as (100), (110) and (111) in UO2 in a temperature range of 300 K-1500 K. The results indicate that the surface energies of the three low miller index crystallographic faces decline gradually with temperature rising, and the variation of the surface energy with temperature is confirmed to be consistent with the experimental data. The (111) crystallographic face which is the closest surface has the lowest surface energy; the (100) crystallographic face has the biggest surface energy; the (100) crystallographic face has a surface energy in between them. The surface atoms have compressed towards the vertical line of surface with respect to the inside atoms layer obviously. The symmetry of surface atoms declines. Surface phenomena such as relaxation and reconstruction occur on the surface atoms and the relaxation effect extends to the five layers. The results presented in the study are useful for understanding the behaviors of fission gas bubbles growing up and cracking up due to the swelling in fuels under the irradiation.
Stationary phase method of calculating Čerenkov radiation spectrum of a charged particle moving in curved path
Authors: Li Yi-Ding  , Zhang Peng-Fei  , Zhang Hui  , Yu Miao  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China;,   CAS Key Laboratory of Basic Plasma Physics, Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Based on the general expression for spectral-angular distribution of the radiation emitted by a charged particle moving in exterior medium, the essential role of stationary phase points in Čerenkov effect is investigated. And the stationary phase method of calculating spectral-angular distribution of Čerenkov radiation from a charged particle moving in curved path is proposed. By the stationary phase method, the asymptotic form of spectral-angular distribution of synchrotron-Čerenkov radiation is calculated, and the result indicates that the spectrum of synchrotron-Čerenkov radiation near critical angle c is quite different from that near the plane of particle's orbit.
Theoretical analysis of constitutive parameters for the periodic magnetic resonator metamaterials
Authors: Xu Xin-He  , Xiao Shao-Qiu  , Gan Yue-Hong  , Wang Bing-Zhong  ,   Institute of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

The thin magnetic resonance dielectric plate is equivalent to a surface magnetic current. Using periodic boundary conditions, the exponential form of the surface magnetic current density is given. The dispersion relation and Bloch impedance of a periodic magnetic resonator metamaterial are derived by calculating the total electric and magnetic fields at the different positions excited by the infinite number of surface magnetic currents, and thus the theoretical formulas for Bloch constitutive parameters are obtained. Since the electric anti-resonance influence on the Bloch permittivity and permeability of magnetic resonator metamaterial is considered, thus the Bloch constitutive parameter difference between theoretical values and retrieval results based on simulations is very small, which shows that the Bloch constitutive parameter formula derived in the paper is very effective to describe the electromagnetic properties of the periodic magnetic resonant material. These theoretical formulas will provide important theoretical basis for the interpretation of the magnetic resonance phenomenon, the design and optimization of the periodic magnetic resonant material.
Phase retrieval of pure phase object based on compressed sensing
Authors: Yang Zhen-Ya  , Zheng Chu-Jun  ,   School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
Published: December 2020

Traditional phase retrieval algorithm, which iteratively reconstructs the phase from 2-intensity measurement or 1-intensity measurement, requires Shannon sampling theorem to be satisfied. This could lead to more requirements for data storage when high resolution imaging is concerned. In order to lower the sampling budget, in this paper we purpose a compressed sensing based phase retrieval algorithm. Through 1-intensity measurement in Fourier plane, our improved Hybrid I/O algorithm is used to reconstruct the exact phase retribution of pure phase object. The algorighm proposed in this paper can reconstruct piecewise regular phase distributed pure phase object from far less amplitude measurements than ones for which the sampling theorem requires to be satisfied. The simulated data indicate that the algorithm has a good converge performance.
Fast multipole boundary element method for diffuse optical tomography
Authors: Xu Jun  , Xie Wen-Hao  , Deng Yong  , Wang Kan  , Luo Zhao-Yang  , Gong Hui  ,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Britton Chance Center of Biomedical Photonics, Wuhan 430074, China
Published: December 2020

The forward problem of diffuse optical tomography (DOT) is commonly solved by the finite element method (FEM) currently. However, with the increase of the model scale, the computational complexity of FEM increases significantly; while the boundary element method (BEM) attracts much attention because of its reduction in calculated dimensions. In this paper, the fast multipole boundary element method (FMBEM) for DOT is studied using a model of highly scattering homogenous medium. In FMBEM, by the multipole expansions of kernel functions, the product of matrix coefficient and iterative vector can be equivalent to the recursion of a quadtree; and then a generalized minimal residual method is used to solve the BEM equation iteratively. The calculations of the FMBEM are compared with Monte Carlo simulations. The results show that the calculations of the FMBEM are in good agreement with Monte Carlo simulations. This demonstrates the feasibility of FMBEM in DOT and indicates that the FMBEM has a bright future for large-scale and real-time imaging.
Optical generation of tunable millimeter-wave based on dual-beam optical injection Locked 1550 nm vertical-cavity surface-emitting laser
Authors: Chen Yu-Lin  , Wu Zheng-Mao  , Tang Xi  , Lin Xiao-Dong  , Wei Yue  , Xia Guang-Qiong  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China;,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

Based on the spin-flip model, the nonlinear dynamics of a 1550 nm vertical-cavity surface-emitting laser (1550 nm-VCSEL) subject to dual-beam optically injection is investigated theoretically. The results show that a slave 1550 nm-VCSEL (S-VCSEL) under the injection of dual-beam output from two master VCSELs (M-VCSELs) can be driven to enter into an injection locking state under suitable injection parameters. In this case, the outputs of both X and Y polarization modes of the S-VCSEL exhibit periodic oscillation whose frequency is equal to the frequency detuning between the two M-VCSELs, and its optical spectrum contains only two main frequency components and possesses a single sideband spectrum structure. As a result, two mutually orthogonal optical millimeter-waves can be obtained based on the periodic oscillation in a VCSEL subject to dual-beam optically injected locking. Through adjusting the frequency detuning between the two M-VCSELs, the frequency of the millimeter-wave can be tuned continuously in a large range, while the power and modulation depth can also be controlled by adjusting the system parameters.
Temperature-dependent relation between junction temperature and 1/f noise in high power semiconductor laser
Authors: Chen Hai-Peng  , Cao Jun-Sheng  , Guo Shu-Xu  ,   State Key Laboratory of Integrate Optoelectronics, Jilin University, Changchun 130012, China;,   State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

The junction temperature rise may not only affect its output power, slope efficiency, threshold current and lifetime, but also will cause the spectral broadening and wavelength shift in a high power semiconductor laser. Therefore, thermal management becomes one of the main problems in research and development of pump laser. In this paper the physical model of the noise power spectrum and junction temperature variation is first established; according to the compression sensing theory, and after sparsing the measured aliasing composite noise signal containing Gaussian white noise and 1/f noise, the basic pursuit denoising algorithm is used to do denoising; through changing the iterations times of the used algorithm and the size of measurement matrix, the curves of the ration between noise voltage power spectrum and junction temperature variation are obtained, thereby avoiding the complexity of direct measurement of the junction temperature. The numerical estimation results can better guid us in doing the thermal management work in high power semiconductor lasers.
All-normal-dispersion multi-wavelength mode-locked dissipative soliton Yb-doped fiber laser
Authors: Xu Zhong-Wei  , Zhang Zu-Xing  ,   Key Laboratory of Photoelectron and Communications of Jiangxi Province, College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: December 2020

An all-normal-dispersion multi-wavelength mode-locked dissipative soliton Yb-doped fiber laser with a periodic birefringence fiber filter is investigated in this paper. Numerical simulations show that multi-wavelength dissipative solitons can be generated by adding a filter into the fiber laser, and adjusting the bandwidth of filter can generate multi-wavelength dissipative solitons with different wavelength numbers and separations. Dissipative soliton molecules (DSM) can be observed in four- and five-wavelength dissipative solitons. Adjusting the parameters of the filter and saturation power can change the number and wavelength of DSM in the multi-wavelength pulses. This is the first time that multi-wavelength mode-locked dissipative solitons with DSM generated from mode-locked fiber laser have been observed, and that the dual-wavelength mode-locked disspative solitons have been obtained from an all-normal-dispersion Yb-doped fiber laser in experiment.
The sensitivity study of NO2 vertical profile retrieval by airborne platform
Authors: Xu Jin  , Xie Pin-Hua  , Si Fu-Qi  , Li Ang  , Zhou Hai-Jin  , Wu Feng-Cheng  , Wang Yang  , Liu Jian-Guo  , Liu Wen-Qing  ,   Centre of Enviromental Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

The retrieval sensitivity of NO2 profile based on airborne muti-axis observation is studied, and the influences of different wavelengths, different view angles, different surface albedos, different aerosol modes, and different altitude are evaluated by calculating the weighting function and average kernels. The results show that higher vertical resolution is obtained at 370 nm than at 500 nm for averaging kernels, more conducive to profile retrieval; not too much profile information is found in upper view angles, while more profile information is achieved in downward looking angles; surface albedos have no obvious influence on profile retrieval; high aerosol mode increases the sensitivity of profile retrieval; the averaging kernels at low flight attitude have no obvious differences in different altitudes, nor are they conducive to the profile retrieval.
Periodic linear chirped pulse generation based on direct phase modulation
Authors: Tian Xiao-Cheng  , Sui Zhan  , Huang Zhi-Hua  , Lin Hong-Huan  , Wang Jian-Jun  , Zhang Rui  , Xu Dang-Peng  , Zhang Yong-Liang  , Zhu Na  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China;,   Beijing Postgraduate Department, China Academy of Engineering Physics, Beijing 100088, China;,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

A new method of generating periodic linear chirped pulse is proposed, and a 0.52 nm bandwidth periodic chirped pulse is generated. Numerical simulation shows that the gain saturation, group velocity dispersion and synchronization jitter have great influences on chirped pulse; and self-phase modulation has little influence since the peak power stays at a low level. The experimental results indicate that the polarization mode dispersion will lead to a great intensity modulation, and the amplified spontaneous emission will break the light stability, which leads to the fewer round-trips of light. Research shows that the direct phase modulation is a novel method of generating periodic linear chirped pulse, which could be used for smoothing the spectral dispersion.
Simulation of characteristics of ZnO/diamond/Si structure surface acoustic wave
Authors: Zhou Zhen-Kai  , Wei Li-Ming  , Feng Jie  ,   Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Based on the recursive stiffness matrix method, the effective surface permittitivity model of multilayered surface acoustic wave structure is established. By this model, the frequency dispersive characteristic of phase velocity for the ZnO/Si layered structure is calculated. The calculation results are in agreement with the experimental results, which verifies the effectiveness and accuracy of the model. Furthermore, the model is also established for the determination of the phase velocity and electromechanical coupling coefficients of ZnO/Diamond/Si structure. The best combination of high velocity and high coupling coefficient of the structure is obtained, which provides a good reference for the design of a high-performance and high-capability surface acoustic wave device.
Experimental investigation on the evolution of dielectric barrier discharge plasma induced flow at different operating pressures
Authors: Cheng Yu-Feng  , Nie Wan-Sheng  , Che Xue-Ke  , Tian Xi-Hui  , Hou Zhi-Yong  , Zhou Peng-Hui  ,   Department of Postgraduate, Academy of Equipment, Beijing 101416, China;,   Department of Space Equipment, Academy of Equipment, Beijing 101416, China
Published: December 2020

The evolutions of dielectric barrier discharge (DBD) plasma induced starting vortex and the transformation of the DBD plasma induced flow field at different operating pressures are obtained by particle image velocimetry. The results show that the starting vortex will diffuse to the embedded electrode side and then disappear, and the diffusivity will decrease as the time goes on at high operating pressure. But the starting vortex will not change in location, and it will not disappear at low operating pressure. As the operating pressure decreases, the starting time of plasma induced flow field decreases, the ordinate orientation of the induced flowfield increases, and the landscape orientation of the induced flowfield decreases. The form of the induced streamline will come through L→U→V as the pressure decreases. There is no induced vortex in the form of L. There are two induced vortexes in the form of U which lay in the middle and on the right hand of the form U respectively, and there is one induced vortex in the form of V which lays in the middle of form V.
Study on micro sliding friction of randomly nanorough surface
Authors: Wang Ya-Zhen  , Huang Ping  ,   School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

As is well known, the surface topography strongly determines the tribological performance and all practical surfaces are rough. Since the actual friction process has apparently random characteristics, in order to obtain the friction suitable to the rough surface, it is necessary to set up a random friction model. In the present paper, the friction between a randomly roughness surface and an atomic-level smooth rigid plane is studied based on the Lennard-Jones potential model. A micro friction model is proposed. In the model, the potential energy between interfaces is determined by the normal load and the balanced spacing. With the numerical technique, the frictional force is calculated and the relationship between the frictional force and the normal load is analyzed as well. The results show that the friction force increases with the normal load increasing, but it increases nonlinearly. The results also show that the interfacial potential may be an essential origin of micro friction.
Temperature dependence of fatigue properties of ultrathin copper films: molecular dynamics simulations
Authors: Guo Qiao-Neng  , Cao Yi-Gang  , Sun Qiang  , Liu Zhong-Xia  , Jia Yu  , Huo Yu-Ping  ,   School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

The molecular dynamics simulations are performed with single-crystal copper thin films under cyclic loading to investigate temperature effects on the mechanical responses. First, the method to determine the number of cycles to failure is reported: the total energy-the number of cycles curve and the stress-the number of cycles curve for nanoscale copper film are obtained; using the two curves and an additional quantitative expression, we obtain the additional quantity-the number of cycles curve, from which fatigue life of copper film is obtained. Next, under cyclic loading, with temperature rising, the number of cycles to failure of copper films increases in different manners at different temperatures: when the temperature is above about 370 K, the number of cycles to failure goes up quickly with temperature; when below about 370 K, the number of cycles rises slowly. Finally, the mechanisms of the strange temperature dependence of cyclic deformation can be explained by our developed model based on the evolutionary features of dislocation.
A new car-following model considering lateral separation and overtaking expectation
Authors: He Zhao-Cheng  , Sun Wen-Bo  ,   Research Center of Intelligent Transportation System, Sun Yat-sen University, Guangzhou 510275, China
Published: December 2020

In order to depict the real car-following behaviors better, in this paper we present a new car-following model by introducing the effect parameter of lateral separation distance and proposing the concepts of overtaking expectation and virtual front car based on OV model. The stability condition of the model is obtained by using the linear stability theory. It is found that with the increase of lateral separation and overtaking expectation, the stability region of traffic flow increases at a low density while it decreases at a high density. The results of numerical simulation verify the analytic results. Thus, in some places like traffic bottlenecks, which usually have a high traffic density, it is necessary to restrict the lateral movement and overtaking behavior of vehicles for suppressing the traffic jam.
Error correction on summer model precipitation of China based on the singular value decomposition
Authors: Su Hai-Jing  , Wang Qi-Guang  , Yang Jie  , Qian Zhong-Hua  ,   Physical Science and Technology College of Yangzhou University, Yangzhou 225002, China;,   Chinese Academy of Meteorological Cadre Training Colleges, Beijing 100081, China;,   College of Atmospheric Scicences, Lanzhou University, Lanzhou 730000, China
Published: December 2020

In this paper, singular value decomposition (SVD) is used to correct the National Climate Center business model CGCM, thus improving the forecast results. By performing the SVD decomposition using field coupling between the summer rainfall patterns forecasted in 1983-2011 and actual rainfall values, by selecting the mode forecast and 3-7 modals that are best correlated with the live precipitation, and comparing these revised results of the different numbers of modal number, and by selecting the number of modals with the best correction effect in the China region, the revised results are obtained from the model predictions. The 2004-2009 cross hindcast experiments and the return results tested by using the anomaly correlation coefficient and the root mean square error as evaluation criterion show that the best corrections are obtained by taking the first five modals in 2004-2009 as the number of modal revised in the year. The examinations of 2004-2009 mode and actual precipitation data demonstrate the correction effect obtained by the five modals is indeed best. A comparison between the result and the systematic errors shows that the Dhamma revised results are better than the systematic errors. Taking the year of 2010 as the forecast year, using the results of the cross-examination of 27 years 1983-2009 to determine the number of modals, and analyzing the forecast results by the determined number of modals constitute a method that has a potential business value.