bluuebunny/crossref_metadata_2025 huggingface dataset:
Radioisotope energy conversion using electrostatic vibrationto–to–electricity converters
Authors: Wang Xiang  , Zhang Qiang  , Chen Ran-Bin  , Deng Zhi-Qiang  , San Hai-Sheng  ,   Department of Mechanical and Electrical Engineering, School of Physical and Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005, China;,   Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen 361005, China
Published: December 2020

Wireless sensor nodes deployed at remote and inaccessible locations need long lifetime power sources to prevent cost prohibitive periodic replacement. In this work, we present a radioisotope 63Ni energy converter using radioisotope-powered electrostatic vibration-to-electricity conversion. Free damped vibration happening in a suspended parallel plate structure with a mass enables a variable capacitance, which can be used to realize the generation of electricity energy by an external circuit. The MATLAB/Simulink is used to simulate the vibration and output power, and the Ansys is used to optimize the structure design. The results show that the optimized design structure with a first-order natural frequency of 500 Hz, a plate gap of 75 μm, and an external resistance of 90 kΩ can generate an average output power of 0.416 μW and conversion efficiency of 8.25%.
New complex soliton-like solutions of combined KdV equation with variable coefficients and forced term
Authors: Yi Li-Na  , Taogetusang  ,   The College of Mathematical Science, Inner Mongolia Normal University, Huhhot 010022, China
Published: December 2020

The [G()]/[G()] expansion method is extensively studied to search for new infinite sequence of complex solutions to nonlinear evolution equations with variable coefficients. According to a function transformation, the solving of homogeneous linear ordinary differential equation with constant coefficients of second order can be changed into the solving of a one-unknown quadratic equation and the Riccati equation. Based on this, new infinite sequence complex solutions of homogeneous linear ordinary differential equation with constant coefficients of second order are obtained by the nonlinear superposition formula of the solutions to Riccati equation. By means of the new complex solutions, new infinite sequence complex soliton-like exact solutions to the combined KdV equation with variable coefficients and forced term are constructed with the help of symbolic computation system Mathematica.
A physical model for band gap of silicon-based photonic crystal of air hole at telecom wavelengths
Authors: Miao Xin-Jian  , Huang Wei-Qi  , Huang Zhong-Mei  , Zhou Nian-Jie  , Yin Jun  ,   Institute of Nanophotonic Physics, Key Laboratory of Photoelectron technology and application, Guizhou University, Guiyang 550025, China
Published: December 2020

Band structures of silicon photonic crystal (PC) with different lattices and shapes of air holes at telecom wavelengths were investigated by plane-wave expansion method, and the related physical models were proposed. Calculated results demonstrate that photonic band gap (PBG) can be effectively manipulated by photon confinement effect and lattice symmetry effect. With the increase of filling fraction, the ability with which photons are confined by PC is enhanced, PBG is opened and the central frequency undergoes a blue-shift. PBG is enlarged as the lattice symmetry increases. Shape and rotation of lattice element are also studied. Band gap with the rotation angle which follows periodicity and symmetry indicates its anisotropy. The optimal cavity structures for different lattices are also found.
Dynamically accessible variations for two-fluid plasma model
Authors: Zou Dan-Dan  , Yang Wei-Hong  ,   Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Dynamically accessible perturbation is a type of Lie perturbation for noncanonical Hamiltonian systems. Firstly, a set of first-order constraint variations that preserve all the Casimir functions is presented based on the two-fluid Poisson bracket. Then the equilibrium equations are given by minimizing the two-fluid Hamiltonian with these variations.
Cascading failure of scale-free networks based on a tunable load redistribution model
Authors: Duan Dong-Li  , Wu Xiao-Yue  ,   College of Equipment Engineering, Engineering University of Armed Police, Xi’an 710008, China;,   College of Information Systems and Management, National University of Defense Technology, Changsha 410073, China
Published: December 2020

To better explore the robustness against cascading failures on complex networks, according to the redistribution rule of the real networks always lie between global preferential rule and local preferential rule or between even shared rule and extremely heterogeneous rule. A new cascading model is proposed based on a tunable load redistribution model. It can tune the load redistribution range and the redistribution heterogeneity of extra load respectively by a redistribution range coefficient and a redistribution heterogeneity coefficient. With this model, we further investigate cascading failures on scale-free networks in terms of numerical simulation and theoretical analysis respectively. Numerical simulation and analytic results show that the model can achieve better robustness against cascading failure than the previous model by adjusting the redistribution range and heterogeneity.
Solution of the fractional-order chaotic system based on Adomian decomposition algorithm and its complexity analysis
Authors: He Shao-Bo  , Sun Ke-Hui  , Wang Hui-Hai  ,   School of Physics and Electronics, Central South University, Changsha 410083, China
Published: December 2020

Based on the definitions of fractional-order differential and Adomian decomposition algorithm, the numerical solution of the fractional-order simplified Lorenz system is investigated. Results show that compared with the Adams-Bashforth-Moulton algorithm, Adomian decomposition algorithm yields more accurate results and needs less computing as well as memory resources. It is even more accurate than Runge-Kutta algorithm when solving the integer order system. The minimum order of the simplified Lorenz system solved by using Adomian decomposition algorithm is 1.35, which is much smaller than 2.79 achieved by the Adams-Bashforth-Moulton algorithm. Dynamical characteristics of the system are studied by the phase diagram, bifurcation analysis, and complexities are calculated by employing the spectral entropy (SE) algorithm and C0 algorithm. Complexity results are consistent with the bifurcation diagrams, for which mean complexity can also reflect the dynamic characteristics of a chaotic system. Complexity decreases with increasing order q, and there are little influences on complexity versus changes of parameter c when the system is chaotic. It provides a theoretical and experimental basis for the application of fractional-order chaotic system in the field of encryption and secure communication.
Study on cumulative fractional release of radionuclides in HTGR fuel particles
Authors: Yang Chen  , Fang Chao  , Zhang Jian  , Cao Jian-Zhu  ,   the State Key Laboratory of Low-Dimensional Quantum Physics, Beijing 100084, China;,   Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China;,   the Key Laboratory of Advanced Reactor Engineering and Safety, Ministry of Education, Beijing 100084, China
Published: December 2020

During high-temperature gas refrigeration reactor (HTGR) operation, SiC in the fuel particles is the key structure for stopping radionuclides diffusing from the particles. Researchers put forward the concept of breakthrough time, which is the time of a large amount of radionuclides released through SiC from the particles, for the consideration of HTGR safety. However, this concept is not so accurate. This paper gives a strict expression of cumulative fractional release interims of classic and improved methods, and also analyses the relevant physical content of breakthrough time in the use of Fick’s law of diffusion. By computing the cumulative fractional release of three kinds of important radionuclides 137Cs, 90Sr and 110mAg, and using the above two methods, we find that the traditional meaning of the physical quantity is not the time of radionuclides released from SiC. The improved method is more accurate for describing the release and transport condition of radionuclides in nuclear fuel particles.
Tunable three photonic band-gaps coherently induced in one-dimensional cold atomic lattices
Authors: Ba Nuo  , Wang Lei  , Zhang Yan  ,   Institute of Physics, Jilin Normal University, Siping 136000, China;,   College of Physics, Jilin University, Changchun 130012, China;,   School of Physics, Northeast Normal University, Changchun 130024, China
Published: December 2020

Using the technique of electromagnetically induced transparency, three photonic bandgaps can be established and manipulated at any time due to the refraction modulated periodically by the one-dimensional optical lattice in a tripod atomic system which is trapped in a one-dimensional optical lattice with a Gaussian density distribution. Using the density-matrix equations to describe the interaction between laser and atoms and the transfer-matrix equation to describe the scattering of light waves in periodic media, we can obtain the steady reflection and transmission spectra. It can be found that the position and width as well as the reflectivity of the photonic band-gap could be tuned by changing the detunings and intensities of the coupling fields and the geometric Bragg detuning.
Estimation of single hydrophone target motion parameter based on cepstrum analysis
Authors: Wang Yan  , Zou Nan  , Fu Jin  , Liang Guo-Long  ,   Science and Technology on Underwater Acoustic Laboratory, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Based on the multipath structure of shallow water ray acoustics, a new robust high-precision motion parameter estimation method using single hydrophone was proposed. Aiming at uniform linear motion target, colligating multipath delay difference and kinematic geometric relation, we have constructed a tridimensional multipath delay model. Then nonlinear time map can be obtained from motion parameters to delay difference, and the cepstrum expression of typical underwater acoustic channel can be studied. The delay difference is extracted from it, and the extraction strategy is put forward. Differential evolution algorithm is used to estimate motion parameters, and the robustness can be improved. Theoretical and simulation results show that the time resolution of cepstrum is not restricted by the bandwidth of signals, which depends mainly on the type of signals and the signal to noise ratio. The cepstrum of CW is not sensitive to Doppler effect. The precision of parameter estimation depends mainly on the accuracy of time delay estimation and the amount of information attached to the differential evolution algorithm. When the information includes recent data points, parameter estimation can be better. Pool test results further verify the correctness and validity of this method.
Influences of sound absorption material on acoustic characteristics of acoustic vector sensor installed on a small underwater carrier
Authors: Liang Guo-Long  , Pang Fu-Bin  , Zhang Guang-Pu  ,   Science and Technology on Underwater Acoustic Laboratory, Harbin Engineering University, Harbin 150001, China
Published: December 2020

In this paper the influences of viscoelastic absorption of materials on the directivity and DOA estimation of acoustic vector sensor installed on the carrier are investigated by virtue of theoretical analysis and experimental results. First, the mathematical model, consisting of absorption material and carrier structure, is established, and the acoustic characteristics of the composite materials in the case of sound propagation are analyzed. On that basis, the acoustic characteristics picked up by the vector sensor are studied by finite element method (FEM) coupling boundary element method (BEM) before and after the covering of absorption material. The influences of absorption material on the directivity of vector sensor are studied by theoretical calculation and numerical analysis, and the DOA estimation accuracy of the vector sensor before and after covering by sound absorption material is calculated. Results are proved to be valid by the experiment in the anechoic tank.
Defect state of the locally resonant phononic crystal
Authors: Hou Li-Na  , Hou Zhi-Lin  , Fu Xiu-Jun  ,   Department of Physics, South China University of Technology, Guangzhou 510640, China
Published: December 2020

By taking a two-dimensional solid local resonant phononic crystal as an example, we investigated the mechanism of the defect state on a subwavelength scale. It is well known that, when the working wavelength is much greater than the distance between resonators, the dispersion of the phononic crystal is insensitive to the lattice structure, and the whole structure can be described in terms of the effective medium theory. As a result, it is hard to introduce a defect state in the system by a local real-space disorder. It is shown in this paper that the dispersion of the local resonant phononic crystal can be understood from the long-range feature of the interaction between resonators, so the creation of a defect state in the system is in fact to break such a long-range interaction. Based on this understanding, the mechanisms of the recently reported methods, that are used to create defect states, are discussed. In addition, a waveguide structure that can guide the longitude or transverse waves separately is realized by introducing an anisotropic defect resonator.
Control of flow around hydrofoil using the Lorentz force
Authors: Chen Yao-Hui  , Dong Xiang-Rui  , Chen Zhi-Hua  , Zhang Hui  , Li Bao-Ming  , Fan Bao-Chun  ,   Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The Lorentz force can be used to control the boundary layer flow of low-conduction fluids; however, its lowest control efficiency has become the main bottleneck in its engineering application. In order to enhance the control efficiency of Lorentz force, we need to study its potential control mechanism. In the present paper, the flow around hydrofoil when using Lorentz force has been simulated numerically by use of dual-time-step Roe method as well as studied experimentally in a water tank. Results show that the hydrofoil drag decreases sharply first and reincreases later, showing that the control effect of the Lorentz force is reduced with the increase of stream velocity, as well as the amplitude-change of the lift and drag; however, the lift increases continuously. The basic mechanism of this phenomenon is that the Lorentz force can form Lorentz force thrust, which increases the wall friction and decreases the pressure on the hydrofoil surface; at the incipient stage of control, the Lorentz force thrust decreases the drag and increases the lift immensely, soon afterwards, due to the action of Lorentz force, the drag increases with the increase of wall shear force and the lift increases with the decrease of upper surface pressure, so that the thrust can increase both the drag and lift.
Non-equilibrium thermodynamic analysis of quasi-static granular flows
Authors: Liu Zhong-Miao  , Sun Qi-Cheng  , Song Shi-Xiong  , Shi Qing-Fan  ,   Department of Physics, Beijing Institute of technology, Beijing 100081, China;,   State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Granular flow is usually divided into three kinds of flow pattern, namely quasi static flow, slow flow, and rapid flow. The core issue of the research is the constitutive relation. A series of constitutive relations of application value have been received up to now, however, the study on principal theory is insufficient. Granular flow has an emergent mesoscopic structure, such as force chain network and vortex, involving complex irreversible processes. This paper studies its mesoscopic structure and principal characters, introduces the concept of two granular temperatures Tconf and Tkin of the granular flow to characterize the degree of chaotic motion and disordered configuration evolution, sets them as the non-equilibrium variables to constitute the thermodynamic state variables set for granular flow with the classical irreversible thermodynamic (CIT) variables, also determines the granular flow law of energy conversion and the entropy production rate, etc., and develops the two granular temperatures (TGT) model. Taking the simple shear quasi-static granular flow in a constant volume as example, and combining it with the discrete element method (DEM), this work confirms the material parameters needed for the TGT model, and analyzes the law of developing period and the effective coefficient of friction of steady period of granular flow.
A novel scheme of beam smoothing using multi-central frequency and multi-color smoothing by spectral dispersion
Authors: Zhong Zhe-Qiang  , Zhou Bing-Jie  , Ye Rong  , Zhang Bin  ,   College of Electronics and Information Engineering, Sichuan University, Chengdu 610065, China
Published: December 2020

In typical techniques of smoothing by spectral dispersion (SSD), illumination uniformity cannot be further improved by increasing the pulse bandwidth due to the limitation of high-efficiency frequency tripling. Combined with the analysis of the schemes of four-color beam smoothing and multi-frequency modulator SSD, a novel scheme of beam smoothing using multi-central frequency and multi-color smoothing by spectral dispersion has been proposed, which not only can achieve high-efficiency frequency tripling, but also can obtain laser beams with nearly continuous spectrum and exhibit some specific advantages in far-field smoothing. Results show that the focal spot will be enlarged slightly but obviously further smoothed by the use of the new scheme. Compared to the typical SSD technique, the new scheme can decrease hot spots effectively and achieve the best irradiation in less time. Moreover, with independent combination of dispersion directions in each quadrant of grating array, a multi-dimensional smoothing on focal spot can be realized.
Parametric excitation of axisymmetric toroidal electrostatic mode by drift wave turbulences
Authors: Zhang Yang-Zhong  , Xie Tao  ,   Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031, China;,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

The axisymmetric toroidal electrostatic mode discussed in this paper refers collectively to the nearly ideal electrostatic fluid mode with zero toroidal mode number in magnetically confined toroidal plasmas like tokamak, including geodesic acoustic mode, sound waves and the so-called nearly zero-frequency zonal flow. Use is made of cold ion fluid model in the toroidal coordinate system with a circular cross section to develop the theory of parametric excitation for the three above mentioned modes systematically to the first order of inverse large aspect ratio, which ends up with the four following observations: (1) The density zonal flow is only associated with the excitation of the first harmonic cosine sound wave and is independent of the potential zonal flow. (2) The geodesic acoustic mode is the high frequency branch of the dispersion in the form of coupling between the first harmonic sine sound wave and the nearly zero-frequency zonal flow due to geodesic curvature, while the low frequency branch of the same dispersion is identified to be the ‘toroidally modified nearly zero-frequency zonal flow’. (3) Only a weak coupling exists between the second harmonic sine sound wave and the nearly zero-frequency zonal flow. (4) All cosine sound waves and sine sound waves beyond the second harmonic are decoupled to the nearly zero-frequency zonal flow. A Gaussian type of drift wave energy spectrum with only a few parameters is introduced for calculation. Emphasis is laid on the effects resulting from the finite radial spectrum width such as double Landau-singularity, which reveal a significant modification to the δ -spectrum, thus resulting in serious restriction to the parametric excitation of geodesic acoustic mode and nearly zero-frequency zonal flow. Also discussed is the possibility of excitation of density zonal flow in the high q region. Numerical results are presented graphically and discussed in the reasonable physical regime. It is indicated that the geodesic acoustic mode and the nearly zero-frequency zonal flow cannot be parametrically excited at the same radii, and that if the geodesic acoustic mode is parametrically excited, the density zonal flow is expectedly to be observed.
Numerical study on the effects of magnetic field on helicon plasma waves and energy absorption
Authors: Cheng Yu-Guo  , Cheng Mou-Sen  , Wang Mo-Ge  , Li Xiao-Kang  ,   College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The propagation properties of electromagnetic waves excited by helicon antenna with a parabolic radial electron density distribution in an external magnetic field were studied. Maxwell equations are numerically solved using the linear disturbance wave assumption to obtain energy distribution, when the magnetic intensity changes from 80 to 800 G. The radial electromagnetic wave and energy deposition intensity distributions were obtained. Results show that when magnetic intensity grows, the helicon wave is little damped and it can propagate into the bulk plasma; Trivelpiece-Gould (TG) wave is heavily damped at plasma-vacuum interface; the main energy absorption region moves towards the boundary gradually. When the magnetic intensity is lower than 100 G, the TG wave can propagate into the bulk plasma, and the plasma radial energy distribution is relatively uniform.
Experimental investigations of tungsten X-pinches using the QiangGuang-1 facility
Authors: Wu Jian  , Wang Liang-Ping  , Li Mo  , Wu Gang  , Qiu Meng-Tong  , Yang Hai-Liang  , Li Xing-Wen  , Qiu Ai-Ci  ,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China;,   State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi’an 710024, China
Published: December 2020

In order to obtain a single brighter point X-ray source, tungsten X-pinch experiments were carried out on the QiangGuang-1 facility. The equilibrium radius of the bright spots was estimated based on the energy balance equation. X-pinch load test covered wire diameters from 25 to 100 μm, wire number from 2 to 48, and the load linear mass from 0.18 to 6.9 mg/cm. The load peak current was 1.0–1.4 MA and the rise time for 10%–90% was 60–70 ns. From the experiments, the matched load for “QiangGuang-1” facility was the 30 or 32 wire-25 μm X pinch with the load linear mass of 2.8–3.0 mg/cm, which can produce a single nanosecond X-ray pulse around current peak with a certain probability. A typical keV X-ray radiation had a pulse width of 1 ns, the radiation power from the bright spot being 35 GW, the radiation yield being 40 J, and the spot size being about 30 μm. Multiple bright spots and multiple X-ray bursts at the crossing were usually observed in the experiments. Multiple X-ray bursts were probably caused by secondary pinches or partial pinches, and multiple bright spots were caused by long wavelength perturbations or localized short wavelength perturbations along the “min Z-pinch” axis. Compared with hundreds of kilo-ampere devices, mega-ampere facilities produced greater X-ray radiation, but further improvements are needed to produce a single X-ray burst steadily.
Study on Grove model of the 4H-SiC homoepitaxial growth
Authors: Jia Ren-Xu  , Liu Si-Cheng  , Xu Han-Di  , Chen Zheng-Tao  , Tang Xiao-Yan  , Yang Fei  , Niu Ying-Xi  ,   School of Microelectronics, Xidian University, Xi’an 710071, China;,   State grid smart grid research institute, Beijing 100192, China
Published: December 2020

In this paper, A Grove model on the homoepitaxial growth of 4H-SiC is presented, based on the structure and growth conditions of CVD system. According to the model analysis, the growth rate of 4H-SiC is quiet influenced by carrier gas flow rate and temperature, which is verified by experiments. Growth rate along the substrate has a bowl-shaped distribution, and the growth rate on the center is slightly lower than on the edge. As the carrier gas flow rate increases, the growth rate controlled by the transport changes into the reaction rate control, the growth rate first increases and then decreases. The position of highest temperature in the actor will be drifted with the carrier gas flow increasing. The reaction rate and the mass transport coefficient increase with the rise of growth temperature, which can cause the increase of growth rate. But the effect of temperature on reaction rate is much greater than on the mass transport. When the temperature rises excessively, the epitaxial growth will be determined by the mass transport. But the high reaction temperature results in forming some particles at the edge of reactor, which can reduce the growth rate, and the particles will have a chance to fall on the epitaxial layer, thus seriously affecting the quality of the epitaxial layer. All the above shows that the growth rate and thickness uniformity can effectively controlled by adjusting the flow rate of hydrogen, the rotational speed of the substrate and the growth temperature.
Effect of thermal treatment on the structural phase transformation of the detonation-prepared TiO2 mixed crystal nanoparticles
Authors: Qu Yan-Dong  , Kong Xiang-Qing  , Li Xiao-Jie  , Yan Hong-Hao  ,   College of Civil Engineering and Architecture, Liaoning University of Technology, Jinzhou 121001, China;,   State Key Laboratory of Structural Analysis for Industrial Equipment; Dalian University of Technology, Dalian 116023, China
Published: December 2020

Nanopaticles of TiO2 mixed crystals (anatase phase and rutile phase) are prepared by detonation method. Morphologies and structural phase transformation behaviors of the as-prepared TiO2 nanopaticles are investigated for different annealing temperatures (600 ℃ and 720 ℃) and durations of annealing time (1, 2, 3.5, and 5 h). The structural phase transformation process and transformation mechanism are also discussed within the framework of the thermodynamic theory. Results show that with the increase of the annealing temperature and annealing time, the particle size of the detonation-prepared TiO2 nanoparticles increases gradually and the relative content of rutile phase in the TiO2 mixed crystal nanopaticles is improved. Compared with the TiO2 nanoparticles prepared by the conventional methods, the mean growth rate of rutile phase is obviously slower than that of anatase phase at the same annealing temperature and annealing time. It is obvious that the temperature at which the anatase phase completely changes into the rutile phase is lower than that of the TiO2 nanoparticles prepared by using other methods. These results are helpful for realizing the control of particle size and phase transformation of TiO2 nanoparticles. Meanwhile, the results can also provide us the theoretical and experimental bases for mass production of TiO2 nanoparticles in the future.
Investigation of carrier transport properties along the c-axis in K0.8Fe2Se2 superconducting crystals
Authors: Yan Qian  , Lu Cui-Min  , Feng Dian-Wen  , Yang Wei-Wei  , Zhao Jie  , Liu Qing-Suo  , Ma Yong-Chang  ,   School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China;,   Tianjin Key Lab for Photoelectric Materials and Devices, Tianjin 300384, China;,   Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin 300384, China
Published: December 2020

We have successfully prepared the iron-based superconductor K0.8Fe2Se2 crystals (Tc=27 K) and studied the carrier transport properties along the c-axis in detail. Samples are characterized by XRD, SEM and temperature-dependent resistivity. The result shows that there is “phase separation” in the samples. Based on the experimental results, the iron-based superconductor is not a simple two phases alternating along the c-axis, but the metal phases should have weak-link channels along the c-axis, forming a nearly 3D special net mode. Studies of the thermal conductivity and the complex impedance spectrum z(omega, T0) suggest that the superconducting crystals have a lot of grain boundaries along the c-axis direction, the bound polarization charges result in relative dielectric constant of about 106 in magnitude and negative phase characteristics in the vicinity of 10 MHz.
Electroluminescence from Si nanostructure-based silicon nitride light-emitting devices
Authors: Lin Zhen-Xu  , Lin Ze-Wen  , Zhang Yi  , Song Chao  , Guo Yan-Qing  , Wang Xiang  , Huang Xin-Tang  , Huang Rui  ,   Institute of Nanoscience and Nanotechnology, Central China Normal University, Wuhan 430079, China;,   Department of Physics and Electrical Engineering, Hanshan Normal University, Chaozhou 521041, China
Published: December 2020

Dense Si nanostructures embedded in silicon nitride prepared by plasma-enhanced chemical vapor deposition (PECVD) was used as luminescence active layer to fabricate light-emitting diodes based on p-Si/SiN-based emitter/AZO structure. Visible electroluminescence from the device was observed at room temperature. It is found that the electroluminescence intensity of the device can be further enhanced significantly by inserting an ultrathin nanocrystalline Si layer between the p-Si substrate and SiN-based emitter as a hole barrier layer. Moreover, the electroluminescence efficiency is increased by more than 80% as compared to the decice without the nc-Si barrier layer.
Fractional-order multiple RLαCβ circuit
Authors: Diao Li-Jie  , Zhang Xiao-Fei  , Chen Di-Yi  ,   Department of Electrical Engineering, Northwest A & F University University, Yangling 712100, China
Published: December 2020

Since the RLC circuit is a basic circuit, attention is directed to the generalization of the fundamentals of fractional multiple RLαCβ circuit. Compared with the conventional multiple RLC circuit, the effects of fractional orders, α and β, is the key factor for extra freedom, more flexibility and novelty. First, we study the basic features including the admittance and phase. Then, the conditions for fractional-order multiple RLαCβ circuit to act as pure imaginary impedances are derived, which are unrealizable in the conventional case. As a peculiar phenomenon–resonance, the relationships among resonance frequency, fractional order and LC are studied in detail. In addition, sensitivity analysis including some interesting rules is illustrated. Finally, numerical simulations are carried out to validate the above studies.
Numerical simulation of generation and radiation of super-radiation from relativistic backward wave oscillators
Authors: Chen Zai-Gao  , Wang Jian-Guo  , Wang Yue  , Zhu Xiang-Qin  , Zhang Dian-Hui  , Qiao Hai-Liang  ,   School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China;,   Northwest Institute of Nuclear Technology, Xi’an 710024, China
Published: December 2020

This paper studies the issues about the X-band super-radiance from a relativistic backward wave oscillator (RBWO) with the central frequency of 9.25 GHz, and the output port of the RBWO is directly connected to a vlasov antenna. The particle simulation code UNIPIC and the self-developed antenna simulation code are combined to simulate the full process of the generation and the radiation of the microwave pulse. Effects of natural gas at difference pressures and injected voltage pulse on the working characteristics of RBWO are simulated and discussed. Simulated results indicate that the peak value of the output power can achieve 3.68 GW, and the instantaneous efficiency can exceed 100%. When the tilted angle of vlasov antenna is 20 degrees, the gain of the antenna is 15.5 dB. The power density can reach 0.728 W/cm2 at the far distance of 1 km.
Complexity analysis of traffic flow based on multi-scale entropy
Authors: Xiang Zheng-Tao  , Chen Yu-Feng  , Li Yu-Jin  , Xiong Li  ,   School of Electrical and Information Engineering, Hubei University of Automotive Technology, Shiyan 442002, China;,   School of Management, Shanghai University, Shanghai 200444, China
Published: December 2020

Research on the complexity of traffic flow evolution is helpful to deeply understand the evolution rule of traffic flow system, which can provide the theoretical foundation for forecasting and controlling traffic flow. Multi-scale entropy (MSE) method is widely used in the analyses of time series of physiology and traffic of computer networks. Considering the similarity between the vehicle arrival in traffic flow system and the packet arrival in computer network, the complexity of the time headway in braking light model is analyzed to show the complexity of traffic flow evolution by using the MSE method. The analysis results show that the complexity of the time headway decreases with the increase of the time scale, which reflects that it is difficulty to predict the traffic flow in a shorttime. In addition, the difference in the complexity of the time headway between the phases of the free flow and synchronized flow is small when the time scale is small. However, with the increase of the time scale, the MSE of the time headway decreases rapidly for free flow, but rather slowly for synchronized flow. Such a difference can be used as a very important reference to distinguish the synchronized flow and the free flow. Research results in this paper can provide new ideas and methods for investigating the complexity of traffic flow evolution.
Bifurcation of proportion-integration-based voltage-mode Buck converter
Authors: Yang Yi-Wei  , Liu Jia-Lin  , Li Bin  ,   College of Electronic and Information Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

Based on the piecewise smooth model, the smooth model and the discrete iterative model of proportion-integration (PI)-based voltage-mode Buck converter are derived. In this paper, it is proved that the chaotic attractor moves on the load line and is controlled by duty cycle, and that the manifold of the model moves around the chaotic attractor accompanied by the occurrences of period 1, period 2 and chaos phenomenon. The linear relationship between output voltage of the PI-controller and output voltage of Buck converter is derived, and then reveals that the proportional factor is a dominant one in PI controller. The period-doubling bifurcation, border collision and chaos are analyzed, and the state transfer process is exhibited. Experimental results verify that the theoretical modeling analysis and the simulation are correct.
Conditional fluctuation characteristics of heart rate variability
Authors: Si Jun-Feng  , Huang Xiao-Lin  , Zhou Ling-Ling  , Liu Hong-Xing  ,   School of Electronic Science and Engineering, Institute for Biomedical Electronic Engineering, Nanjing University, Nanjing 210093, China;,   Institute of Pharmacology, Nanjing University of Chinese Medicine, Nanjing 210029, China
Published: December 2020

Heart rate variability (HRV) has the characteristics of non stationary and transient fluctuation. In this paper, we propose using the autoregressive conditional heteroskedasticity (ARCH) to analyze such fluctuations. Analytical methods include using auto-regressive moving average model to eliminate sequence trends and correlativity, using the F-test method to determine whether there is ARCH effect in residual sequence, while giving an acceptance probability of ARCH effect. The fluctuations of HRV in congestive heart failure (CHF) patients and normal people are analyzed in this paper. The large difference in statistics value of acceptance probability between CHF patients and normal people indicates that the method can well distinguish between different groups. It provides a new method for the study of ECG information.
Analysis of time-varying channel effects on transmission performance of deep-sea abandoned measuring instrument
Authors: Zheng Yu  , Zhao Xuan  , Li Jing  , Fu Xiao-Hong  , Wang Jin-Hai  , Li Hong-Zhi  , Liu Ning  ,   School of Information and Electrical Engineering, Tianjin Polytechnic University, Tianjin 300387, China;,   National Ocean Technology Center, Tianjin 300112, China
Published: December 2020

Because of the environmental requirements, deep-sea abandoned measuring instrument mostly uses the cable channel. However, the stability of the channel transmission is seriously affected by length change in electrical impedance of the channel. In this paper, a new method is presented, which is used for dynamically analysing the effects of the cable channel on the amplitude and phase of the transmission signal by using XCTD (expendable conductivity, temperature and depth) profiler transmission channel. Firstly, regulations about the parameters of each circuit varying with the channel length is proposed. Meanwhile, the simplified transmission circuit model and its transfer function are established. Through qualitative analysis we can conclude that the transmission frequency, distributed capacitance and winding inductance have an influence on the signal phase. Finally, in this paper we analyse and discusse how the cable influences the transmission of signal, and present the reason of the influences with MATLAB, which can further guide the design of the XCTD measuring system and improve the accuracy of the measurements and the stability of signal transmission.
New exact solutions and complex wave excitations for the (2+1)-dimensional dispersive long wave equation
Authors: Lin Fu-Zhong  , Ma Song-Hua  ,   Department of Physics, Longyan University, Longyan 364012, China;,   Department of Physics, Lishui University, Lishui 323000, China
Published: December 2020

By the Riccati equation expansion method and a variable separation method, a series of variable separation solutions of the (2+1)-dimensional dispersive long wave equation is derived. According to the derived solitary wave solution, we obtain some nove complex wave localized structures and study the time evolutions of complex waves.
Wireless sensor network fault tolerant topology for lifetime optimization
Authors: Liu Hao-Ran  , Yin Wen-Xiao  , Han Tao  , Dong Ming-Ru  ,   Institute of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China;,   Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

Because of the limited energy of wireless sensor network, the optimization of network lifetime becomes a primary problem in the design of the network. Through analyzing the node residual energy and the load effect on the node lifetime, the fault tolerant topology evolution model in wireless sensor networks is put forward for extending lifetime. And the scope of load adjustment coefficient is obtained under the condition of network survival time. The simulation results show that the topological structure based on the evolution of the scale free network has the good fault tolerance characteristics. And it can also balance the network node energy consumption and the lifetime extension of the network.
Molecular structure and excited states for BN under strong electric field
Authors: Cao Xin-Wei  , Ren Yang  , Liu Hui  , Li Shu-Li  ,   School of Physics and Mechatronics Engineering, Xi'an University of Arts and Science, Xi'an 710065, China
Published: December 2020

The ground states of BN molecule under different strong electric fields ranging from -0.06 a.u. to 0.06 a.u. are optimized using density functional method B3LYP at 6-311++g(d.p) level. Optimized parameters, dipole moment, charge distribution. HOMO energy, LUMO energy, energy gaps, infrared spectrum are obtained. The result shows that with the increasing of the external electric field, the correlation between molecular structure parameters and the electric field intensity becomes obvious and presents the asymmetry. In addition, TDDFT method at the same level is used to study the influence of external electric field on BN molecular excitation energy and oscillator strength, and the result shows that the electron transition spectrum is blue-shifted with the increase of the external electric field, but the intensity of the vibrator has a more complicated change, showing that the spectral intensity is affected by the electric field.
Studies on the analytical curves of diatomic molecules using algebraic and energy-consistent method
Authors: Yuan Li  , Fan Qun-Chao  , Sun Wei-Guo  , Fan Zhi-Xiang  , Feng Hao  ,   Research Center for Advanced Computation, School of Physics and Chemistry, Xihua University, Chengdu 610039, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

The analytical potential energy curves of stable diatomic electronic states are investigated based on the algebraic method (AM) and energy consistent method (ECM). The AM-ECM method is applied to 4 electronic states of 7Li2-23∑g+, KH-X1∑+, NaLi-X1∑+ and NaLi-A1∑+. The results show that the AM-ECM potentials are superior to some other analytical potentials, and can generate accurate analytical potential expressions of these electronic states in the molecular asymptotic and dissociation region.
Squeezing properties of two-mode atom laser in a system of Ξ-type three-level atomic Bose-Einstein condensate interacting with single-mode light field
Authors: Nong Chun-Xuan  , Li Ming  , Chen Cui-Ling  ,   College of Science, Guilin University of Technology, Guilin 541004, China;,   College of Mathematics and Statistics, Guangxi Normal University, Guilin 541004, China
Published: December 2020

The squeezing properties of the two-mode atom laser in a system of Ξ-type three-level atomic Bose-Einstein condensate interacting with single-mode squeezed coherent light field are studied. The results show that the two-mode atom laser can be squeezed periodically, and has two types of oscillations: quantum Rabi oscillation and collapse-revival oscillation. The maximum depth of squeezing and the collapse-revival frequency of the atom laser depend greatly on the interaction intensity between the light field and atoms, and the quantum Rabi frequency is largely determined by the frequency of the light field.
Analysis of high frequency characteristics of the sine waveguide
Authors: Xie Wen-Qiu  , Wang Zi-Cheng  , Luo Ji-Run  , Liu Qing-Lun  ,   Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A theoretical analysis of the high frequency characteristics for an all-metal slow-wave system (SWS), i.e., a sine waveguide, is performed in this paper. The continuous profile of the cosine groove is approximated by a series of connected rectangular steps, and the SWS is divided into several regions reasonably, then the expressions of the field in all the regions are given. The dispersion equation and coupling impedance formula of the SWS are obtained by using the field matching theory combined with the matching of the admittance. The high frequency characteristics for a sine waveguide used in a 220 GHz TWT are discussed, and the calculation results are in good agreement with those obtained from three-dimensional electromagnetic simulation software CST-MWS. The effects of the geometrical parameters on high frequency characteristic of the sine waveguide are also investigated in detail.
Enhancing microwave tomography in a circular metallic chamber by an inhomogeneous background
Authors: Ding Liang  , Liu Pei-Guo  , He Jian-Guo  , Amer Zakaria  , Joe LoVetri  ,   School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg MB R3T 5V6, Canada
Published: December 2020

Microwave tomography is enhanced by using an inhomogeneous background. In this paper, the measurement region is located in a circular perfect electrical conductor (PEC) chamber where a known object is placed inside the imaging domain as an inhomogeneous background. This can not only make use of the prior information about the background, but also increase the equivalent radiation source for the target detection. The Green function of a circular PEC chamber with inhomogeneous background is obtained using the method of moments. Based on the Green functions for both homogeneous and inhomogeneous background in circular PEC chamber, the properties of the radiation operators are analyzed by comparing the condition numbers and the singular value spectra. Simulations are carried out in homogeneous, lossless inhomogeneous and lossy inhomogeneous backgrounds respectively, and the relative errors are discussed. The results show that using inhomogeneous background can improve the convergence rate and accuracy, and the lossy inhomogeneous background produces better results than the lossless one. In addition, it can enhance the inversion results without changing the microwave tomography system, which can be used in the medical imaging and industrial nondestructive detection.
Characteristics of electromagnetic scattering from the vehicle-mounted ground penetrating radar in layered media
Authors: Li Xue-Ping  , Ji Yi-Cai  , Lu Wei  , Fang Guang-You  ,   Key Laboratory of Electromagnetic Radiation and Sensing Technology, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A physical model for the electromagnetic scattering of layered media is established. Radar equation and Snell's law are adopted to calculate the electromagnetic scattering field of multiple layer media. The effects of the electrical properties of the layer, i.e., permittivity and loss tangent on the detection range of the radar system and scattering field are studied. The vehicle-mounted ground penetrating radar (GPR) for the exploration of lunar subsurface is taken as the background. The finite difference time domain method is used to model and calculate the whole vehicle-mounted GPR, and the intensity of the scattering echoes is studied. The simulation results are compared with the theoretical results, and they are found to be in good agreement with each other. Finally some analyses of the results are presented.
Infrared image super-resolution via locality-constrained group sparse model
Authors: Deng Cheng-Zhi  , Tian Wei  , Chen Pan  , Wang Sheng-Qian  , Zhu Hua-Sheng  , Hu Sai-Feng  ,   Department of Information Engineering, Nanchang Institute of Technology, Nanchang 330099, China;,   Department of Communication and Electronic, Jiangxi Science and Technology Normal University, Nanchang 330013, China
Published: December 2020

Aiming at the problems of low-resolution and poor visual quality of infrared images, a locality-constrained group sparsity based infrared image super-resolution algorithm is proposed. Firstly with considering the texture self-similarity of infrared images and group structural sparsity of atom coefficients, a locality-constrained group sparse (LCGS) model is proposed. Secondly, under LCGS and K-singular value decomposition, a pair of group structural dictionaries is learned. The dictionary pair can well capture and preserve the intrinsic geometrical manifold of low and high resolution data. Finally, the high-resolution infrared images are recovered by the high-resolution dictionary and the corresponding low-resolution group sparse coefficients. Experimental results show that the proposed method obtains excellent performance in objective evaluation and subjective visual effect.