bluuebunny/crossref_metadata_2025 huggingface dataset:
The multi-point X-ray source and phase contrast imaging used on implosion experiment
Authors: Yan Ji  , Zheng Jian-Hua  , Chen Li  , Hu Xin  , Huang Tian-Xuan  , Jiang Shao-En  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Traditional implosion backlight imaging experiment has disadvantages of nonuniform X-ray source, low contrast ablator interface and high requirement for diagnostic device tuning precision. A novel design of multi-point X-ray source combined with phase contrast imaging developed and optimized based on experimental research performed on Shenguang-II facility is presented. The novel design can obtain high-quality experimental result with uniform X-ray source, clear interface between ablator and inner DD gas and large image view. At the same time, the new design using diagnostic silt instead of diagnostic hole improves tuning precision. The experimental result proposes that novel design of laser driven plasma point x-ray source combined with phase contrast imaging has advantage of area X-ray source combined with absorb imaging and can be widely used in inertial confinement fusion and high energy density physics.
Study on gate capacitance-voltage characteristics of strained-SiGe pMOSFET
Authors: Wang Bin  , Zhang He-Ming  , Hu Hui-Yong  , Zhang Yu-Ming  , Song Jian-Jun  , Zhou Chun-Yu  , Li Yu-Chen  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

The gate capacitance-voltage (C-V) characteristic of strained SiGe pMOSFET is very different from that of bulk Si pMOSFET, and can be strongly affected by the channel doping. In this paper, we first study the formation mechanism of the "plateau" which can be observed in the gate C-V characteristics of strained SiGe pMOSFET, and then present a physics based analytical model to predict the gate C-V characteristic of strained SiGe pMOSFET. It is found that this plateau is channel doping dependent. The results from the model are compared with the experimental results and they are found to be in excellent agreement with each other, giving the evidence for its validity.
Surface-enhanced Raman scattering effects of gold nanorods prepared by polycarbonate membranes
Authors: Ye Tong  , Gao Yun  , Yin Yan  ,   Faculty Of Physics and Electronics, Hubei University, Wuhan 430086, China;,   Key Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China;,   Faculty of Materials Science and Engineering, Hubei University, Wuhan 430086, China
Published: December 2020

Using a polycarbonate membrane (PCM) as a template, and combining with the electrochemical deposition method, we prepare gold nanorods each with about 36 nm in diameter and 1 μrm in length. We measure transmission spectra, and find that the resonant absorption peak is at around 540 nm. Subsequently, the enhancement effects of the nanorods are investigated with 514 nm and 633 nm laser excitations. Comparing the spectra under resonant condition with those under non-resonant condition, we conclude that the field enhancement effect under the resonant excitation is more prominent than under the non-resonant excitation. The enhancement factor under the resonant excitation is increased to 7 times of the factor under the non-resonant excitation. Comparing with similar researches, we achieve the following two improvements: 1) with a resonant excitation, we significantly increase the enhancement factor of gold nanorods; 2) we eliminate the fluorescence of PCM molecules, thus make the template method more feasible for transparent surface-enhanced Raman scattering substrate applications.
A HSPICE model of carbon nanotube field effect transistor
Authors: Zhao Xiao-Hui  , Cai Li  , Zhang Peng  ,   The Sciences Institute, AFEU, Xian 710051, China;,   The Engineering Institute, AFEU, Xian 710038, China
Published: December 2020

In order to apply carbon nanotube field effect transistor (CNTFET) to circuit simulation, maintaining an acceptable accuracy while minimizing computation time is a major problem. To establish a simple and high accuracy CNTFET model in HSPICE, based on the semi-classical model of CNTFET, the relationship between self-consistent electric potential and carrier density is analyzed, linear approximation is used for curve fitting, and explicit expression of self-consistent electric potential is deduced, so that the iterative solution of an integral equation is avoided. Then the CNTFET model in HSPICE is built. Simulation demonstrates that the proposed model can maintain high accuracy, and the logic functions can be realized in corresponding logic gates built with the proposed model, while the computation time is significantly reduced.
Homoclinic orbits analysis of T chaotic system with periodic parametric perturbation
Authors: Xi Xiao-Jian  , Wang Zhen  , Sun Wei  ,   Department of Foundation, Xijing University, Xi'an 710123, China
Published: December 2020

Using Melnikov method we have analysed and calculated the homoclinic orbits of a slowly varying oscillator, derived from the T chaotic system with generalized Hamiltonian structure under periodic parametric perturbation. Also the parameter bifurcation conditions of homoclinic orbits are obtained. The simulation results demonstrate the feasibility of periodic parametric perturbation control technology, and the correctness of the discussion in this paper.
Line focusing characteristics of axicon illuminated by non-diffracting Bessel beam
Authors: Du Tuan-Jie  , Wang Tao  , Wu Feng-Tie  ,   College of Information Science and Engineering, Huaqiao University, Fujian Key Laboratory of Optical Beam Transmission and Transformation, Xiamen 361021, China
Published: December 2020

The line focusing characteristics of axicon illuminated by non-diffracting Bessel beam was analyzed in terms of Hankel theory and diffraction integral theory, and a new kind of method to generate periodic bottle beam was put forward, i.e. Talbot effect bottle beam was generated by axicon illuminated by non-diffracting Bessel beam. Intensity distributions along the propagation path and the intensity evolution of the bottle beams in a complete period after the axicon illuminated by non-diffracting Bessel beam were simulated numerically. An optical system was designed and Bessel-like beam was obtained by light wave emitted from He-Ne laser passing through axicon after the optical system, and then an axicon was used to focus the Bessel-like beam. Periodic bottle beam was then observed after the axicon, and the spot diagram of two periodics were taken by a CCD camera. Experimental results agree well with the theoretical analysis. This result has a practical significance in multi-plane micro-manipulation and may serve as a guideline in optical micro-control by periodic bottle beam.
Experimental investigations on coherent combination of high-power and high-intensity air-modulated speakers
Authors: Zhou Ze-Min  , Zeng Xin-Wu  , Gong Chang-Chao  , Zhao Yun  , Tian Zhang-Fu  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper, the experimental investigation of coherently combined air-modulated speakers is achieved. This paper addresses a basic architecture for coherent-combined air-modulated speakers by means of active phase control, and then the fundamental theory for coherent combination using stochastic parallel gradient descent algorithm is described. Numerical simulation on coherently combining sound sources with horn is carried out. Moreover, an experiment of far-field coherently combining two air-modulated speakers has been conducted, and the configuration scheme of parameters in practical terms is presented. Experimental results show that when the algorithm converges, the sound pressure level at the test spot is 4 dB higher than that of single source. A power spectrum analysis indicates that the sound power of coherently combining case is close to the sum of the sound powers between the coherently combining of the fundamental frequency components and the non-coherently combining of the other frequency components for all sound sources. Consequently, it is revealed that the acoustic wave phases for air-modulated speakers can be effectively controlled by the active phase control algorithm, and an evident coherent-combining effect is obtained.
Numerical studies on intense laser-generated relativistic high-energy electrons via a thin cone target
Authors: Mu Jie  , Sheng Zheng-Ming  , Zheng Jun  , Zhang Jie  ,   Key Laboratory for Laser Plasmas (MoE) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

It is proposed that with a mini-cone target, an enormous number of high-energy collimated electrons can be produced, which may be used for fast ignition research. The effect of different laser and cone target diameters on high-energy electrons are studied with two-dimensional particle-in-cell simulations. When the open angle of the mini-cone is 10 degree, the number of generated hot electrons is relatively larger. With the increase of the open angle, both the energy and number of hot electrons decrease. When preplasma is added to the cone surface, the amount of hot electrons increases, while the peak energy of the hot electrons decreases. With the increase of the laser pulse duration, the number of high-energy electrons increases linearly.
Raman spectra of monoand bi-layer graphenes with ion-induced defects-and its dispersive frequency on the excitation energy
Authors: Li Qiao-Qiao  , Han Wen-Peng  , Zhao Wei-Jie  , Lu Yan  , Zhang Xin  , Tan Ping-Heng  , Feng Zhi-Hong  , Li Jia  ,   State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Science and Technology on ASIC Lab., Hebei Semiconductor Research Institute, Shijiazhuang 050051, China
Published: December 2020

Raman spectroscopy has become a key way for characterizing and studying disorder in graphene, due to its nondestructive, rapid and sensitive technique. In this paper, ion implantation is used to produce the structural defects in single-layer graphene (SLG) and bi-layer graphene (BLG). The first- and second-order modes of ion-implanted SLG and BLG and their physical origins were studied by Raman spectroscopy. The dependence of dispersive frequency of first- and second-order modes in SLG and BLG on the excitation energy was discussed in detail. Results show that the ～2450 cm-1 peak is the combination mode of the D mode at ～1350 cm-1 and the D" mode at ～1150 cm-1.
The sliced trispectrum fluctuation characteristics and flow pattern representation of the nitrogen-water two-phase flow of small channel
Authors: Li Hong-Wei  , Zhou Yun-Long  , Wang Shi-Yong  , Sun Bin  ,   College of Energy Resource and Mechanical Engineering, Northeast Dianli University, Jilin 132012, China;,   Fushun Mining and China Sinogy Thermoelectric Co., Ltd, Fushun 113001, China
Published: December 2020

A new method of nonlinear analysis is proposed by combining the sliced trispectrum method with the fluctuation characteristics, and the influences of the length of the time sequence and fast Fourier transform (FFT) on the fluctuation characteristic value of sliced trispectrum are discussed. It is found that in the absence of noise, the length of sequence and FFT are proportional to the vector distance value; in the presence of noise, it is approximate inversely related. In order to test the anti-noise ability and characterize complexity ability of the fluctuation characteristics method, the proposed method is applied to fractal sequence (Brown), chaotic sequence (Lorenz) and periodic sequence (sine signal). The results show that compared with other power spectral method, the method of the fluctuation characteristics has good noise immunity of fractal sequence, and the anti-noise ability is relatively weak with periodic sequence; but the fluctuation characteristic theory of sequence internal complexity representation has a good effectiveness. On this basis, the differential pressure signals of nitrogen-water two-phase flow in small rectangular channel (w×h=2 mm×0.81 mm) are studied. By analyzing the differential pressure sliced trispectrum of flow patterns, the secondary coupling phenomenon of main oscillation mode of different flow patterns is established. The fluctuation characteristic values of the sliced trispectrum of different flow patterns are extracted to accurately identify the typical flow patterns of small channel nitrogen-water two-phase flow. At the same time, the fluctuation characteristic theory can be used to provide a useful exploration for the further investigation of flowing mechanism of multi-phase flows.
Theoretical progress in designs of stable superhydrophobic surfaces
Authors: Wang Ben  , Nian Jing-Yan  , Tie Lu  , Zhang Ya-Bin  , Guo Zhi-Guang  ,   Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, China;,   State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

Controlling the wettability of solid surfaces is an important issue that has aroused the increasing interest from both fundamental and practical perspective by tailoring surface morphology and surface chemical compositions. The underlying theories for interpreting wetting phenomena still mainly focus on the Young's equation, the Wenzel equation, and the Cassie-Baxter equation, despite the fact that the wetting phenomena have been studied over the past decades. While there are a lot of experimental studies on wettability of surface roughness, there is still a lack of a thorough analysis of the contributions of micro and nano-scale roughness to wettability behavior despite interesting features these surfaces have. In this article, the basic theories and their applicabilities are addressed in detail, and the mutual transition between Wenzel state and Cassie-Baxter state is described from different viewpoints in general, and from single-scale and dual-scale point of view in particular. The design concept of geometrical model with stable superhydrophobicity is also described, which is based on the typical theories about wettability. Finally, some promising breakthroughs in the theoretical progress are proposed.
A method for magnetocardiograms filtering based on singular value decomposition and S-transform
Authors: Yin Bai-Qiang  , He Yi-Gang  , Wu Xian-Ming  ,   College of Electrical and Information Engineering, Hunan University, Changsha 410082, China;,   School of Electrical and Automation Engineering, Hefei University of Technology, Hefei 230009, China
Published: December 2020

In order to solve the problem of power line noise and environmental magnetic noise to magnetocardiogram, a filtering method based on singular value decomposition (SVD) and generalized S transform is proposed. On the basis of discrete condition, S transform and its inverse transform in matrix form are derived. The signal is first preprocessed using generalized S transform in order to get better time-frequency resolution, then the time-frequency domain is decomposed by SVD, and the valid time-frequency region is determined. Therefore, the adaptive filtering can be realized. Numerical simulation studies indicate that the method presented can achieve better performance than other methods with less singular values. Illustrative examples verify the effectiveness of the proposed method.
Compensation control on chaotic systems with uncertainties based on polynomial basisfunctions model
Authors: Zeng Zhe-Zhao  , Lei Ni  , Sheng Li-Zeng  ,   College of Electric and Information Engineering, Changsha University of Science and Technology, Changsha 410076, China
Published: December 2020

For the control of uncertainty chaos systems, a compensation control method using the polynomial-basis-functions model (PBFM) based on conjugate gradient algorithm (CGA) is studied. In the proposed method, dynamic properties of a chaotic system are first fitted by PBFM, and then feedforward compensation control for the uncertainty chaos system is implemented by using good fitting PBFM. The proposed approach can quickly track any given reference signal without the need of a mathematic model of chaos system. The numerical simulation results show that the proposed control method has not only the fast response speed and high control accuracy, but also a strong inhibitory ability to parameter perturbation and the anti-interference ability for the chaos system.
The chiral asymmetry of R-(-)1,3-butanediol as revealed by its Raman differential bond polarizabilities
Authors: Shen Hong-Xia  , Wu Guo-Zhen  , Wang Pei-Jie  ,   The College of Biology and Chemical Engineering, Jiaxing University, Jiaxing 314001, China;,   State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China;,   The Beijing Key Laboratory for Nano-Photonics and Nano-Structure, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

The Raman optical activity (ROA) of (R)-(-)-1,3-butanediol was described through the analysis of bond polarizability and differential bond polarizability, which were elucidated by Raman and ROA spectral intensities, respectively. Analysis shows that during the Raman process, the charge flows from the (six) rings formed by H16 (or H15) O6C3C2C1O5 to the peripheral OH and CH bonds. The analysis also shows that the signs of differential bond polarizabilities associated with the rings inside and outside are opposite. This means that the chiral asymmetry of this molecule is fairly distinct.
Investigation of hundred-watt-level supercontinuum generation in photonic crystal fiber
Authors: Chen Hong-Wei  , Guo Liang  , Jin Ai-Jun  , Chen Sheng-Ping  , Hou Jing  , Lu Qi-Sheng  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A 101 W all-fiber supercontinuum soure is demonstrated by seeding a piece of photonic crystal fiber with a high-power pulse-repetition-rate-tuning picosecond fiber laser. By performing a series of comparative experiments, influences of the pump pulse repetition rate and the photonic crystal fiber length on the supercontinuum generation process are investigated in detail. How to improve the power level of the supercontinuum soure is analyzed and discussed. The research results will make a contribution to the further development of high-power supercontinuum soure.
Molecular dynamics simulation on the struatural stability of [0 1 1] tilt incoherent 3 gain boundaries in pure copper
Authors: Dong Lei  , Wang Wei-Guo  ,   School of Mechanical Engineering, Shandong University of Technology, Zibo 255049, China;,   Faculty of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350108, China
Published: December 2020

It has been reported that incoherent 3 boundaries play an important role in the evolution of grain boundary characteristic distribution in the low to medium stacking fault energy in face-centered cubic metals. In order to ascertain the characteristics of incoherent 3 boundaries with varied (h1k1l1)/(h2k2l2) interface matching, the structural stability of [0 1 1] tilt incoherent 3 grain boundaries in pure copper, at temperatures ranging from 700 to 1100 K and under the normal pressure, was studied by molecular dynamics (MD) simulations. Long-range empirical potential (LREP) was used in the simulation in which the time-step was chosen to be 5 10-15 s (5 fs). Simulation results show that the structural stabilities of [0 1 1] tilt incoherent 3 grain boundaries are different from one another. The general trend is that the larger the angle () by which the grain boundary plane deviates from the ideal (1 1 1)/(1 1 1) twin boundary plane, the smaller the grain boundary matching value and thus the more unstable the incoherent 3 boundary. With the smallest angle, (2 5 5)/(2 1 1) is stable and almost no structural change is observed during annealing processes. With increasing angle, the incoherent 3 boundaries will not be stable any longer. They are usually changed into the meta-stable step-like boundaries during annealing by the mechanisms in which every three atomic layers in the high Miller-index side will merge into one atomic layer, or each atomic layer in the low Miller-index side decomposes into three atomic layers. Some of the steps of these boundaries are located at the exact {111}/{111} planes. As the annealing temperature increases, such step-like boundaries will change completely into straight and stable {111}/{111} coherent twin boundaries.
Microstructure evolution of W(Mo)/Cu nanometer multilayer films under He+ ion irradiation
Authors: Zhi Chao-Hu  , Liu Bo  , Ren Ding  , Yang Bin  , Lin Li-Wei  ,   Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education; Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

W(Mo, 9.8 at.%)/Cu nanometer multilayer films of different individual layer thickness were prepared by RF magnetron sputtering, which were irradiated by 60 keV He+ ions at ion fluence from 0 to 51017 He+/cm2. Microstructures of nanometer multilayer W(Mo)/Cu films were investigated by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD) before and after irradiation. Experimental results indicate that: (1) The phase transformation of -W (A-15) into steady state -W can be attributed to the bombardment effect of energetic He ions on the surface of films, leading to phase-transition temperature during irradiation. (2) The irradiation tolerance of W(Mo)/Cu multilayer film was found to depend on the individual layer thickness. (3) At the fluence of 51017 He+/cm2, the HRTEM results reveal that the behavior of helium cluster/bubble in the W(Mo) film is obviously different from that in the Cu film. It is interesting that the distribution of helium cluster/bubble is related to the grain orientation of W(Mo) film and tends to distribute along W (211) plane. However, Cu film is completely amorphized and helium cluster/bubble is evenly distributed in it.
A miniaturized low-frequency polarization-insensitive metamaterial absorber based on broadside-coupled spiral structures
Authors: Lu Lei  , Qu Shao-Bo  , Shi Hong-Yu  , Zhang An-Xue  , Zhang Jie-Que  , Ma Hua  ,   Science College, Air Force Engineering University, Xi’an 710051, China;,   School of Electronics & Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

In this paper, we present the design, simulation, and experimental demonstration of a miniaturized low-frequency metamaterial absorber based on the broadside-coupled spiral structures. The tested results indicate that the metamaterial absorber can achieve a miniaturized narrowband absorption with a peak absorption of 98% at 1.39 GHz. Both of the unit cell size and the total thickness of the metamaterial absorber are 6.8 mm that is approximately 1/32 of the working wavelength. Since the spiral structures of the metamaterial absorber are arranged in rotational symmetry, the absorber is polarization-insensitive to the normal incident electromagnetic wave. Additionally, the metamaterial absorber can strongly absorb the obliquely incident electromagnetic wave for both transverse electric and transverse magnetic polarizations, even at 60° angle of incidence.
1DVAR retrieval method for GPS radio occultation measurements of atmospheric temperature and humidity profiles
Authors: Bi Yan-Meng  , Liao Mi  , Zhang Peng  , Ma Gang  ,   National Satellite Meteorological Center, Beijing 100081, China
Published: December 2020

GPS radio occultation observed refractivity is a function of atmospheric temperature and humidity. One-dimensional variational (1DVAR) analysis can be used to retrieve temperature and humidity profiles simultaneously from refractivity data. Profiles derived from 1DVAR method with COSMIC 2011 data occurred in China area are compared with the collocated radiosondes. The background data are ECMWF profiles and the retrieval results show good agreement with radiosondes. The effect of non-ideal gas compressibility on temperature and humidity retrieval errors is focused on in the 1DVAR analysis. Results compared with different months data show that non-ideal gas compressibility has a systematic effect on radio occultation retrieved atmospheric profiles. Including non-ideal gas effect correction the temperature bias to radiosondes is around 0.1 K, while the specific humidity bias is 0.5%. Because radio occultation data can be assimilated into operational numerical weather prediction system without bias correction, taking into consideration non-ideal gas effect is clearly very important. In addition, including this effect in radio occultation retrieval has important impact on climate applications.
Spiral-wave dynamics in an excitable medium with many excitability obstacles
Authors: Yuan Guo-Yong  , Zhang Huan  , Wang Guang-Rui  ,   Department of Physics, Hebei Normal University, Shijiazhuang 050024, China;,   Hebei Advanced Thin Films Laboratory, Shijiazhuang 050024, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

Many real excitable systems can be descibed as inhomogeneous media, where the inhomogeneity is an important factor for the formation of spiral waves and the changing of their dynamics. In this paper, we investigate the effect of excitability obstacles on spiral-wave dynamics. For an excitability-reduced obstacle, the neighbor spiral tip is attracted into the obstacle. When more localized obstacles are placed, the attactive case depends on the distribution, size and excitability of the obstcales. On the basis of analyzing the small-value area of the inhibitor variable, we illustrate the mechanism of these behaviors occuring. For an excitability-enhanced obstacle, the nearby spiral tip is repelled. The tip motion after the repelsive effect depends on the type of the initial spiral wave, i.e. rigidily rotating spiral wave or meandering spiral wave. In the present of more localized obstacles, there exist different behaviors for different distributions, sizes and excitabilities of the obstcales, and different types of initial waves.
A design of liquid crystal lens with low voltage driving
Authors: Tang Xian-Zhu  , Chung Te-Chen  , Jen T’ing-Hsien  , Lu Jian-Gang  , Shieh Han-Ping  ,   National Engineering Laboratory of TFT-LCD Materials and Technologies, Displays and Lighting Center, Shanghai Jiaotong University, Shanghai 200240, China;,   Infovision Optoelectronics Co. Ltd., Kunshan 215301, China;,   Taiwan Chiao Tung University, Hsinchu, China
Published: December 2020

Design rules for liquid crystal (LC) lens with low driving voltage are studied in this paper. Many rules are obtained from simulations of five kinds of LC materials. If normalized Δneff of the LC material is less than 95%, the driving voltage of LC lens will be less than 10 V. On the premise that the performance of LC lens is satisfied and fabrication process is permitted, the smaller the normalized Δneff, the lower the driving voltage of the designed LC lensis. The results in can guide people in this paper designing and preparing the LC lens with high performance.
Perturbation to Noether symmetries and adiabatic invariants for nonconservative dynamic systems
Authors: Zhang Yi  ,   College of Civil Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
Published: December 2020

The problem of perturbation to Noether symmetry and adiabatic invariant for a nonconservative dynamic system is studied under a dynamic model presented by El-Nabulsi. First of all, the fractional action-like variational problem proposed by El-Nabulsi under the framework of the fractional calculus and based on the definition of the Riemann-Liouville fractional integral is introduced, and the Euler-Lagrange equations of the nonconservative system are given. Secondly, the definition and criterion of the Noether quasi-symmetric transformation are given, the relationship between the Noether symmetry and the invariant is established, and the exact invariant is obtained. Finally, the perturbation to the Noether symmetry of the system after the action of a small disturbance and corresponding adiabatic invariant are proposed and studied, the conditions for the existence of adiabatic invariant and the formulation are given. An example is given to illustrate the application of results.
Optimal design of high-power microwave source based on particle simulation and genetic algorithms
Authors: Chen Zai-Gao  , Wang Jian-Guo  , Wang Yue  , Qiao Hai-Liang  , Guo Wei-Jie  , Zhang Dian-Hui  ,   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

Optimal design method of high-power microwave source based on particle simulation and parallel genetic algorithm is presented in this paper. The output power of the high-power microwave device, simulated by the fully electromagnetic particle simulation code UNIPIC, is given as a fitness function, and the float-encoding genetic algorithm is used to optimize the high-power microwave device. Using this method, we encode the position and height of the Bragg reflector of the relativistic backward wave oscillator (RBWO), and optimize the parameters for a massively parallel processor. Simulation results demonstrate that we can obtain the global optimal parameters of the Bragg reflector of the RBWO.
An efficient reconstruction algorithm for flat object based on backprojection filtration method in circular half-cover computed tomography
Authors: Zhang Feng  , Yan Bin  , Wang Xian-Chao  , Jiang Hua  , Wei Xing  ,   National Digital Switching System Engineering and Technological Research Center, Zhengzhou 450002, China
Published: December 2020

In circular full-cover cone-beam computed tomography (CT), the field-of-view (FOV) is limited by the width of planar detector, resulting in low imaging efficiency for large object. The FOV can be doubled by half-cover scanning, in which the back-projection filtration (BPF) algorithm based on the concept of PI-line is the best choice for image reconstruction. However, the integral intervals of different PI-lines are unequal in the BPF algorithm, leading to heavy communication consuming and calculation. As a result, the reconstruction efficiency by use of the BPF algorithm is low. In this paper, an efficient image reconstruction strategy based on the BPF algorithm for flat object is proposed. With the method, we demonstrate that the inequality of integral interval of PI-line can be ignored in the discrete implementation of the BPF algorithm when the thickness of flat object is less than 2Rsin(2π/Np) (R is the scanning radius and Np is the number of uniform sampled projections in a full circle). Compared with the original BPF algorithm for half-cover scanning, our method has two major advantages: the first one is that the outer loop is the sample angle while the inner loop is the PI-line, which reduces the communication consuming for computer significantly; the second one is that the derivative of projection, back-projection and inverse Hilbert transform along the PI-line can be computed using parallel computing techniques readily. The results of numerical simulation and real data experiment indicate that the computational efficiency of the proposed method is 5.6 times that for original BPF algorithm and the reconstruction errors of the two methods are comparable.
A detailed study of the effect of Schottky barrier on the dark current density-voltage characteristics of CdS/CdTe solar cells
Authors: Zhao Shou-Ren  , Huang Zhi-Peng  , Sun Lei  , Sun Peng-Chao  , Zhang Chuan-Jun  , Wu Yun-Hua  , Cao Hong  , Wang Shan-Li  , Chu Jun-Hao  ,   National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China;,   Shanghai Center for Photovoltaics, Shanghai 201201, China;,   Information Science and Technology College, East China Normal University, Shanghai 200241, China
Published: December 2020

Numerical modeling is used to obtain insight into the details of the effect of back contact barrier height (φb) on the dark current density-voltage characteristics of CdS/CdTe solar cell. And relation between the roll-over and the barrier height is obtained. Analytic simulations are fitted to the measured current density-voltage curve in a temperature range from 220 to 300 K. And the influence of barrier height on J-V of the CdS/CdTe thin film solar cell with Cu/Mo back contact fitted parameters is discussed. The equation between back contact barrier height (φb) and the reverse saturation current density (Jb0) is revised and the experimental data are consistent with the simulation results very well.
A model of quantum signaling repeater and its parameters simulation
Authors: Xue Le  , Nie Min  , Liu Xiao-Hui  ,   School of Communication and Information Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710061, China
Published: December 2020

In order to solve the damage problem during remote transmission of quantum signaling, a repeater model of signaling quantum is proposed. In this model, firstly purifying and distributing entanglement of the received signaling quantum state is carried out, to establish entangled channels between the signed sending and receiving. Secondly, through quantum entanglement swapping the quantum signaling is transmitted, for completing the quantum signaling relay. Simulation results show that the success rate of signaling relay can reach more than 97% under the condition that the fidelity is 0.98 and the entangled pairs successful establishing rate is 0.98; the throughput of quantum signaling relay is up to 183kbps when the probability of entanglement swapping, purification, and entangled pairs successful establishing is 0.98.
A modified feedback controlled car-following model considering the comprehensive information of the nearest-neighbor leading car
Authors: Sun Di-Hua  , Zhou Tong  , Liu Wei-Ning  , Zheng Lin-Jiang  ,   College of Automation, Chongqing University, Chongqing 400044, China;,   Key Laboratory of Dependable Service Computing in Cyber Physical Society of Ministry of Education, Chongqing University, Chongqing 400044, China
Published: December 2020

Congestion control is a process to achieve optimal decision-making and effective control of vehicles through the interaction of vehicular perception and control, it shows the typical characteristic of cyber physical systems. Based on the pioneer work of Konishi et al., we present a new feedback control scheme to suppress traffic jam in the coupled map car-following model under open boundary condition, which considers the effect of safe headway and optimal velocity difference on the traffic system from the perspective of tight conjoining between the transportation cyber system and the transportation physical system. According to the control theory, the condition under which traffic jam can be suppressed is analyzed. Both theoretical analyses and simulation results show that the suppression performance of our scheme is better than those of the previous schemes, although all the schemes can suppress traffic jam.
PSF estimation via gradient cepstrum analysis for single blurred image
Authors: Shi Ming-Zhu  , Xu Ting-Fa  , Liang Jiong  , Li Xiang-Min  ,   Key Laboratory of Photo electronic Imaging Technology and System, Ministry of Education of China, Beijing Institute of Technology, Beijing 100081, China; School of Optics and Electronics, Beijing Institute of Technology, Beijing 100081
Published: December 2020

Since single image restoration algorithms using lots of priori information lead to high complexity and low computational efficiency, a gradient cepstrum analysis method is proposed to estimate the point spread function PSF for a single blurred image. Firstly, we present the basic principle of estimating PSF from gradient cepstrum of a single blurred image and use the phase retrieval algorithm to recover phase information of the two-dimensional PSF, which can obtain the estimated PSF rapidly, Secondly, to evaluate the accuracy of the proposed PSF estimation method, the total variation regularized image restoration model coupling with an image gradient fidelity term is established and an alternating direction method with rapid and stable convergence is adopted to optimize the energy function. Both synthetic and real blurred images are tested to verify the performance of our scheme. Results show that our scheme not only can estimate the PSF rapidly and accurately so that it overcomes shortcomings of traditional algorithm with slow convergence, but also suppresses ringing effects to preserve information in edges. These advantages provide theoretical and technical foundation of the real engineering requirement in single image deblurring, especially for large scale images.
Investigation on visible emission and n-type conductivity of ZnO thin films annealed at different temperatures
Authors: Nie Meng  , Zhao Yan  , Zeng Yong  , Jiang Yi-Jian  ,   Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

ZnO thin films with good visible emissions were deposited on Al2O3 substrates by pulsed laser deposition and subsequently annealed at different temperatures in oxygen ambient. The visible emission property of the films varied significantly with different annealing temperatures. The resistivity, carrier concentration and mobility of the films showed certain rules. From the results of X-ray diffraction, scanning electron microscope, photoluminescence and Hall measurements, the mechanism of visible emission and the reason of showing n-type conductivity in native ZnO thin films were analyzed in this paper.
Design of silicon based germanium metal-semiconductor-metal photodetector enhanced by surface plasmon resonance
Authors: Hong Xia  , Guo Xiong-Bin  , Fang Xu  , Li Kan  , Ye Hui  ,   Department of Optical Engineering, Zhejiang University, State Key Laboratory of Modern Optical Instrumentation, Hangzhou 310027, China;,   Research Institute of Energy and Nuclear Technology Application of Zhejiang Province, Hangzhou 310012, China
Published: December 2020

Surface plasmon excited by metallic grating integrated on metal-semiconductor-metal can greatly improve the absorption of devices. In order to deeply explore the excitation and resonant discipline of surface plasmon, a design of metal-semiconductor-metal based on ultra-thin germanium is proposed. By using finite difference time domain (FDTD) method, the effects of grating period, grating depth, grating space, and thickness of the active layer on the performance of surface plasmon resonance supported device are investigated in detail. The structure parameters of the device are optimized, and the mechanism of surface plasmon excited by each interface as well as spectrum absorption enhanced by surface plasmon resonance is analyzed in detail. Simulation results show that the germanium device with an ultra-thin active layer of 400 nm has a high absorption in the communication band, especially at the wavelength of 1550 nm the normalized spectral absorption can be as high as 53.77% with an enhancement factor of 7.22. Surface plasmon resonance can greatly improve the optical response of high-speed optoelectronic device, thus an efficient way is provided to solve the trade-off between photodetector responsivity and speed of the device.
Nonspecific adsorption of charged mesoporous nanoparticles on supported thiol/lipid hybrid bilayers
Authors: Lu Nai-Yan  , Yuan Bing  , Yang Kai  ,   National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China;,   Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
Published: December 2020

Mesoporous silica nanoparticles (MSN) with cationic and anionic surface charges were synthesized, Their adsorption behaviors to the supported lipid membranes at different pH values were also studied using QCM-D. We found that NH2-MSN could be adsorbed onto the membrane at pH values from 4 to 8, while the adsorption of COOH-MSN onto the membrane could not occur due to its charge being always the same as that of the membrane at any pH values. These results might provide the information for understanding and predicting the interactions between nanoparticles and cell membranes, and could be effectively used in drug delivery systems and disease treatment.
A new method of forecasting initial formation temperature during the whole drilling process based on proportional-integral control principle
Authors: Yang Mou  , Meng Ying-Feng  , Li Gao  , Deng Jian-Min  , Li Yong-Jie  , Zhou Yu-Liang  ,   State Key Laboratory of Oil and Gas Geology and Exploration. Southwest Petroleum University, Chengdu 610500, China;,   Postdoctoral Workstation of Ta Li-mu Oilfield Company, Kuer-le 841000, China
Published: December 2020

A strategy based on proportional-integral feedback control was applied to gradually feedback the error between simulation of transient heat transfer model and logged date to forecast initial formation temperature. In this study, based on the each control unit of mass, momentum and energy conservation principles in a wellbore, the transient heat transfer model was developed between circulation and shut-in stages under real casing program and drilling string assembly condition, which were solved by full implicit finite difference method. Meanwhile, the proportional-integral control principle was introduced to compare the error range between measured temperature and prediction temperature, which can precisely and quickly obtain initial formation temperature. Combined with a deep well basic data, the results show that the heat exchange efficiency of wellbore and formation was changed by the casing pipe depth, thus affecting formation temperature distribution of the near-well zone. What’s more, the initial and boundary conditions of each control unit in the down-hole was also changed by circulation and shut-in operating time during the drilling process, leading to the variation of distribution distance of the initial formation temperature of the near-well zone. Development of the numerical models and the research methods can provide accurately, economically and quickly to obtain theoretical basis for oil drilling, geothermal well exploiting and the initial formation temperature information.
Quantum correlation dynamics of two two-level atoms in common environment
Authors: He Zhi  , Li Long-Wu  ,   College of Physics and Electronics, Hunan University of Arts and Science, Changde 415000, China;,   School of Physics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

By exactly solving the model of two two-level atoms with dipole-dipole interaction, interacting with a common environment, quantum entanglement and quantum discord of two atoms are obtained. In this paper, the influences of the non-Markovian effect of environment, the dipole-dipole interaction of two atoms and the detunings of the central frequency of the cavity and the transition frequency of the atoms on quantum entanglement and quantum discord dynamics of two atoms are comprehensively considered. The study shows that in the non-Markovian regime and the resonant case, if two atoms are initially in the entangled state, the damping of quantum entanglement and quantum discord will be remarkably suppressed. More specially, in the off-resonant case, the disentanglement time of the two atoms can be considerably prolonged. On the other hand, if two atoms are initially in the separable state, the dipole-dipole interaction can enhance the amplitude of oscillations of quantum entanglement and quantum discord in a short time, but the steady values of quantum entanglement and quantum discord cannot be changed by the dipole-dipole interaction in the long-time limit. Finally, the different influences of the dipole-dipole interaction on quantum entanglement and quantum discord also are discussed.
Multi-scale analysis of nanoscale contact process between spherical indenter and single crystal aluminium
Authors: Yang Xiao-Jing  , Fang Cong-Cong  ,   Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500, China;,   Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China
Published: December 2020

Based on the quasicontinuum method and repulsive force-field approach, a muti-scale modeling of nano-contact process between rigid spherical indenter and surface of single crystal aluminium is established. The corresponding load-depth, graph of atomic state, and moire pattern of displacement are obtained, from which the arrangement of atoms and the effects of the shape of indenter on the nucleation and emission of dislocations in the contact process are studied. Therefore micro-mechanisms of deformation are analyzed. The result shows that due to the fact that the direction of force on atoms that contact the indenter is constantly changing with the increase of contact depth, the corresponding load-depth shows that step increases which is different from that of the square indenter with the response of the underlying crystal. Due to the indenter geometry, the close packed planes under both sides of indenter slip partially lead to Shockley partial dislocations. In the process of disengagement, the elastic recovery is accomplished as the atoms move up with indenter. The residual depth is 0.3 nm, which is close to the magnitude of the Burgers vector, 0.285 nm.
Effect of uniaxial stress on photon localization of one-dimensional photonic crystal with a mirror symmetry
Authors: Li Qian-Li  , Wen Ting-Dun  , Xu Li-Ping  , Wang Zhi-Bin  ,   Department of physics, North University of China, Taiyuan 030051, China;,   The Center of Micro/Nano Technology, North University of China, Taiyuan 030051, China;,   MOE Key Laboratory of Instrumentation Science and Dynamic Measurement, North University of China, Taiyuan 030051, China;,   National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan 030051, China;,   Engineering Technology Research Center of Shanxi Province for Opto-Electronic Information and Instrument, North University of China, Taiyuan 030051, China
Published: December 2020

In this paper, the transfer matrix method is used to study the characteristics of the photon localization in the mirror heterogeneous structure which has three periods and one-dimensional photonic crystal in uniaxial stress change. In a mirror structure triply-periodic photonic crystal system, its mirror structure destroys the orderliness of the photonic crystal and produces a defect state, so the transmission peaks of a photon localization appear in the photonic band gap wider center. The study shows that when a uniaxial stress is exerted on the mirror structure with three-periodic photonic crystal, the photon localization transmittance peak dramatically changes with the stress. When a weak external mechanical stress is applied to the photonic crystal, photonic crystal forms a tensile strain which induces the change in the photonic crystal structure and significantly affects the rate of the transmittance peak transmittance of photon localization. The results show that the transmission peak transmittance is significantly influenced by the uniaxial stress. These features provide a theoretical reference for the design of ultra-high-sensitivity pressure sensor with the photonic crystal structure.