bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental progress of quasi-isentropic compression under drive condition of Shen Guang-Ⅲ prototype laser facility
Authors: Wang Feng  , Peng Xiao-Shi  , Shan Lian-Qiang  , Li Mu  , Xue Quan-Xi  , Xu Tao  , Wei Hui-Yue  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Laser indirect-drive has the potential to obtain ultra-high pressure which is very useful for shock physics. The isentropic compression can be obtained with reservoir target in laser indirect-drive experiment. The free surface velocity and interface velocity are the two important parameters in isentropic compression experiment. The efficiency with reservoir target is lower than that in the isentropic compression experiment with long pulse laser direct-drive. However, the isentropic compression experiment with long pulse in laser direct-drive is very sensitive to the laser intensity variation. In this paper, the isentropic compressions with reservoir target with indirect-drive and direct-drive on Shen Guang-Ⅲ prototype laser facility are investigated separately. And the important technique is introduced to provide the reference data in this field. And the isentropic compression with long pulse laser direct-drive is analyzed on Shen Guang-Ⅲ prototype laser facility. The interface velocity on Al/LiF is achieved with three steps. The blank effect is provided and analyzed. These data show that with long pulse in laser direct-drive, a pressure, which has been highest in China up to now, can be obtained. With these experiment data, the feasibility to do the isentropic compression experiment on Shen Guang-Ⅲ prototype laser facility has been approved.
Numerical investigation on high power microwave flashover and breakdown on inner and outer surface of output-window by EM-fluid simulation
Authors: Dong Ye  , Zhou Qian-Hong  , Yang Wen-Yuan  , Dong Zhi-Wei  , Zhou Hai-Jing  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

In this paper, an electromagnetic-field FDTD method coupled with plasma fluid model is put forward to investigate the different physical phenomena of high power microwave (HPM) flashover and breakdown on inner and outer surface of output-window. Based on the above theoretical models, a one-dimensional (1D) electromagnetic field and plasma interaction code is programmed by authors. By using the code, the HPM flashover and breakdown on inner and outer surface of output-window are simulated. The numerical results could be concluded as follows. For flashover and breakdown on outer surface, output microwave pulse is shortened without cut-off; there is a standing-wave distribution of electric field RMS (Root-Mean-Square) value before the window with fixed-positions of wave nodes and antinodes; there is a ultra-high-density (～1021 m-3) and ultra-thin (～mm) plasma shell with slow diffusion, microwave could penetrate the plasma-shell partly; the shortening of output microwave is caused by plasma absorption mostly. The output pulse of microwave could be lengthened by reducing the initial density or depth of plasmas; the other way is to shorten incident microwave pulse or reduce the value of incident microwave power. For flashover and breakdown on inner surface, there is also a standing-wave distribution of electric field RMS value before the window but the positions of wave nodes and antinodes vary with time; the plasma region moves toward the microwave source; with strong-outgassing, output microwave pulse is shortened without cut-off, there are “thread-like” ultra-high-density (～ 1021 m-3) and ultra-thin (～mm) plasma regions with slow diffusion, the distance between two “thread-like” regions is about a quarter of microwave wavelength, the shortening of output microwave is caused by plasma absorption mostly; with weak-outgassing and low electric field value, the output pulse of microwave is lengthened but cut-off finally, there are “belt-like” high-density (～ 1018 m-3) and thin (mm-cm) plasma regions with fast diffusion, the distance between two “belt-like” region is about a quarter of microwave wavelength, the shortening of output microwave is caused by plasma absorption mostly; with weak-outgassing and high electric field value, output pulse of microwave is cut-off quickly, “block-like” diffuse ultra-high-density (～1021 m-3) and deep (～ cm) plasma regions are formed with very fast diffusion, and the shortening of output microwave is caused by plasma reflection mostly.
Enhanced discharge of high power pulsed magnetron sputtering coupling with high voltage
Authors: Wu Zhong-Zhen  , Tian Xiu-Bo  , Pan Feng  , Ricky K. Y. Fu  , Paul K. Chu  ,   School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China;,   State Key Laboratory of Advanced Welding Production and Technology, Harbin Institute of Technology, Harbin 150001, China;,   Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
Published: December 2020

Plasma source ion implantation and deposition, as an effective technology to produce functional coatings with high adhesion and density, possesses the wide application prospect, especially in the deposition of coatings that work in high loading service conditions. The key component of this technology is the metal plasma source, which is now based on pulsed cathodic arc with complex source structure and magnetic filtration because of the macro-droplets in the ion flux. In this paper, we present another metal plasma source, high power pulsed magnetron sputtering (HPPMS), and investigate the discharge characteristics at different coupling high-voltages by optical emission spectroscopy. The results show that significant improvements are found in the discharge target current and main particles in the plasma. The improvement in gas discharge by the coupling high-voltage is greater than in metal discharge which could increase obviously in the self-sputtering stage with higher target voltage discharge. Last but not least, in this paper we discuss the discharge enhancing mechanism of coupling high-voltage. It is found that the self-excited glow discharge of coupling high-voltage, the hollow-cathodic effect induced by face-to-face negative voltages of HPPMS and coupling high-voltage, and the enhanced ambipolar diffusion of the coupling high-voltage can all play a considerable role in HPPMS discharge.
Dielectric layer equivalent capacitance and loading performance of a coaxial dielectric barrier discharge reactor
Authors: Zhao Kai  , Mu Zong-Xin  , Zhang Jia-Liang  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams of Ministry of Education, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China
Published: December 2020

Dielectric barrier discharge (DBD) can produce non-equilibrium plasma at atmospheric pressure, and it has become a hot point in recent years. For the DBD excited by pulsed or alternated currents, the effects of the loading performance of power supply, the matching between supply and discharge reactor and the discharge phenomena on its discharge are interesting issues. The studies of these issues are of great importance for understanding the DBD processes and improving the power supply efficiency. In this paper, the Lissajous figures of a DBD reactor with coaxial electrode configuration are measured. The loading performance of the DBD reactor and the dependences of excitation voltage and air flow rate on the dielectric layer equivalent capacitance are studied in atmospheric air. According to the experimental data and circuit modeling analysis, it is proved that the dielectric layer capacitance decreases with the increase of air flow rate, but increases with the increase of excitation voltage. The amplitude-frequency performance of the reactor reveals significant RLC circuit resonance. The resonance frequency of the reactor has the same behavior as its dielectric layer capacitance. Therefore it shows that the dielectric layer capacitance is the main factor for the resonance frequency evolution. A possible mechanism responsible for the dielectric layer capacitance is also presented.
Stacking effects in topological insulator Bi2Se3：a first-principles study
Authors: Chen Yan-Li  , Peng Xiang-Yang  , Yang Hong  , Chang Sheng-Li  , Zhang Kai-Wang  , Zhong Jian-Xin  ,   Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105, China;,   College of Physical Science and Mechanical Engineering, Jishou University, Jishou 416000, China;,   College of Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

By using first-principles method, we study the stacking effects on the electronic structure, topological phase and spin splitting in the bulk and film of topological insulator Bi2Se3. It is found that the different stackings can lead to different interlayer interactions and change the centrosymmetry of Bi2Se3. The centrosymmetric ABC and AAA stackings in bulk Bi2Se3 have similar band structures. ABA stacking breaks the centrosymmetry, giving rise to considerable changes of the band structure and large spin splitting. We further study the stacking effects in the film of Bi2Se3 and find that the non-centrosymmetric ABA stacking can induce large spin splitting in Bi2Se3 film. It is proposed and illustrated that the strain can tune the spin splitting effectively.
Transport properties in a gate controlled silicene quantum wire
Authors: An Xing-Tao  , Diao Shu-Meng  ,   School of Sciences, Hebei University of Science and Technology, Shijiazhuang 050018, China
Published: December 2020

Silicene is a two-dimensional honeycomb lattice formed by a monolayer of silicon atoms, which has similar electrical properties to those of graphene. Silicene attracts much attention due to its relatively large spin-orbit coupling. The transport properties through a silicene quantum wire controlled by a gate are studied by using the non-equilibrium Green function formalism. A pair of gapless and spin-polarized edge states appears only when the gate voltage is strong and the silicene quantum wire has perfect zigzag or armchair boundaries in which additional silicon atoms are absent. Moreover, the edge states controlled by gate are spin valley-polarized, that is, the directions of spins are opposite in different valleys, which is different from that of the edge state at the interface between the silicene and vacuum. These results can be helpful to design and fabricate the practical silicene nanostructure.
Study on ferroelectric behaviors and ferroelectric nanodomains of YMnO3 thin film
Authors: Zhang Run-Lan  , Xing Hui  , Chen Chang-Le  , Duan Meng-Meng  , Luo Bing-Cheng  , Jin Ke-Xin  ,   Shaanxi Key Laboratory of Condensed Matter Structures and Properties, Northwestern Polytechnical University, Xi'an 710072, China;,   College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an 710054, China
Published: December 2020

Hexagonal YMnO3 is a special kind of multiferroics which shows unique advantages in magneto-electric field due to its low permittivity and only c-axis polarization. However, its ferroelectric properties, especially domain structures, have not been intensively investigated. In this study, YMnO3 film about 270 nm in thickness is prepared on Si(100) substrate by sol-gel spin coating. Structure and morphology of the film are characterized by grazing incidence X-ray diffraction and atomic force microscopy. Domain structure and its reversal behavior on a nanoscale are examined by piezoresponse force microscopy (PFM). The leakage current and ferroelectric property are also investigated. The results show that the film displays a hexagonal perovskite structure with good crystallinity and has smooth surface with a root-mean-square roughness of 7.209 nm. PFM images and typical local piezoresponse loops reveal the good piezoelectric and ferroelectric properties of the YMnO3 film at room temperature. Meanwhile, the offsets of amplitude loop and phase loop are observed due to the internal electric field. Leakage current density of YMnO3 film is lower than 10-6 A·cm-2, so saturated hysteresis loop can be obtained.
Bidirectional reflectance of sandy land surface with different particle sizes
Authors: Zhao Zi-Jie  , Zhao Yun-Sheng  ,   School of Geographical Science, Northeast Normal University, Changchun 130024, China
Published: December 2020

The area of sandy land is extending in China because the natural environment suffers the destruction by the human activity. The estimation of the properties and area of sandy land is an important indicative information for improving the environment. Remote sensing technique can provide scientific and effective data sources using its unique advantage. In this study, we measure the bidirectional reflectance information from sandy land surfaces with different particle sizes and analyze the effect of particle size on the reflection characteristics. Then, a comparison is performed between the measured reflectance and the reflectance of sandy land surface with different particle sizes which is computed based on existing model. The results show that the effect of particle size on the bidirectional reflectance distribution is apparent We also find that the bidirectional reflectance of sandy land surface with different particle sizes can be computed using the bidirectional reflectance model when the difference between measured reflection information and modeled reflection information is small. This study not only defines the effect of particle size on the reflectance from sandy land surface, but also provides valuable reference for estimating the particle size from sandy land surface using remote sensing technique and studying the intrinsic optical property of land surface.
Experimental study on of dynamics of particles in the flow filed with intensive gradients
Authors: Chen Zhi  , Yi Shi-He  , Zhu Yang-Zhu  , He Lin  , Quan Peng-Cheng  ,   College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The dynamic response of particles in hyper/supersonic flow is one of the key points of techniques using tracer particles, such as particle image velocimetry (PIV). In the literature, it is validated by the single oblique shock response testing. However, particles suffer intensive variation of velocity, density and viscosity, when used to trace and measure the complex flow field in the high speed vehicle engine. To test and validate the dynamics of particles in such a flow field with intensive gradient, in this paper we conduct a series experiments dealing with this issue. The study includes the measurements on the velocity field at the exit of the wind tunnel nozzle to testify the performance of PIV system, the measurements on the oblique shock response of particles in Mach 4.2 and Mach 3.0 supersonic flows over a 10° wedge and a 15° wedge respectively, and measurements on the double oblique shock response of particles in the flow field which is designed to simulate the flow field inside the vehicle engine with gradients and without the influence of expansion wave. Based on the particle dynamic models, the relaxation time, relaxation distance, Stokes numbers of different cases can be gained. And the influence of unstable shock oscillation is analyzed and revised based on image method and statistic analysis. It can be found that the relaxation time and distance increase with the Mach number, given the same wedge degree. However, with the same incoming Mach number, the relaxation time and distance drop when the wedge degree increases. Due to the intensive variation of Reynolds number and viscosity, the results show that in a certain extent particles lose their following ability by 5.7%, while its Stokes number increases by 1%. In the flow condition herein, the Stokes number still meets the requirement of supersonic flow. However the decrease of particle following ability is worth being concerned, especially when using particles in the complex flow field with more intensive gradients.
The periodic problem of drift motion of the guidance center in the earth’s magnetosphere electromagnetic field
Authors: Chen Li-Juan  , Lu Shi-Ping  ,   School of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

Using Mawhin's continuation theorem, the existence of periodic solution for a class of nonlinear problem is discussed, and then by using it, the problem of periodic solution of drift motion of the guidance center in earth's magnetosphere electromagnetic field is investigated. A result on the existence of periodic solution to the model is obtained, and the feasibility of our result is explained.
Euler-Lagrange equation for general n-order character functional and unification of quantitative causal principle, principle of relativity and general Newton’s laws
Authors: Zhang Xin-You  , L. J. Li  , Huang Y. C.  ,   Institute of Theoretical Physics, Beijing University of Technology, Beijing 100124, China;,   Department of Physics, University of Naples, Via Cintia, 80126 Naples, Italy
Published: December 2020

This paper gives a general n-order character functional, and uses the quantitative causal principle to derive the general variational principle; furthermore the Euler-Lagrange equation and conservative quantities for a general n-order character functional are derived, and the link between the principle of relativity and the quantitative causal principle is revealed. Newton's first, second, and third laws are then derived, but the third laws is also regarded as a new law: it is a theorem that force is zero in translational invariance, and its general physical meaning in classic mechanics is revealed. The results obtained have been successful applied to the galaxy gravitational potential correction, molecular potential, quark confinement potential, etc., and the results are consistent with the physical experiments.
Quantum mechanics mixed state representation
Authors: Fan Hong-Yi  , Lou Sen-Yue  , Pan Xiao-Yin  , Da Cheng  ,   Department of Physics, Ningbo University, Ningbo 315211, China;,   Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

In the previous studies and literatures, quantum mechanics representations are a pure state representation, while in this paper beginning with reasonable ordering of operators in quantum mechanics and the normal distribution thought in probability statistics, we propose the concept of quantum mechanics mixed state representation firstly,and prove its completeness and orthogonality. The advantages of mixed state representation is that it can reflect a variety of expression of quantum mechanics operators and the corresponding operators ordering rules.
Research on weighted scale-free topology with balancing energy consumption characteristics in wireless sensor networks
Authors: Liu Zhou-Zhou  , Wang Fu-Bao  ,   School of Electronics and Information, Northwest Polytechnical University, Xi'an 710076, China;,   Xi'an Aeronautical University, Xi'an 710077, China
Published: December 2020

Due to the energy limitation in nodes in the wireless sensor networks, the problem whether the node energy consumption is balanced becomes a primary one in the design of networks. Through building the node lifetime model, we conclude that the node lifetime is affected by the node residual energy and the communication distance. Additionally, both ends of the node lifetime are introduced as the influencing factors on edge weights. And then through the edge weight the node weight is controlled, so that the weighted scale-free topology with energy consumption balanced characteristics is obtained. Finally, theoretical proof shows that the distribution of the node weight, the edge weight, and the node degree all obey the power-law distribution. Simulation results show that this model has the good fault tolerance characteristics that the scale-free topology can have. And it also has obvious advantages in balancing the network energy consumption and prolonging the network lifetime.
Propagation characteristics of THz electromagnetic waves in time varying un-magnetized plasma
Authors: Chen Wen-Bo  , Gong Xue-Yu  , Deng Xian-Jun  , Feng Jun  , Huang Guo-Yu  ,   School of Electrical Engineering, University of South China, Hengyang, 421001, China
Published: December 2020

This paper has built the one-dimensional model of the time-varying un-magnetized plasma, and the finite different time domain (FDTD) algorithm is used to calculate the reflection and transmission coefficients, as well as the absorption rate of terahertz (THz) electromagnetic waves in time-varying plasma. The relation between the frequency of the THz wave and the propagation characteristic influenced by rise time, electron density, temperature, and depth of time-varying plasma plate is analyzed. Results demonstrate that the reflection coefficient is mainly influenced by plasma rise time and electron density. The absorption rate increases with decreasing rise time, increasing depth and electron density. Furthermore, the THz electromagnetic wave is an effective tool for the communication of reentry vehicle and high density plasma diagnosis because of its strong penetrability in high density plasma.
Ultra-wideband microwave robust Capon beamforming imaging system for early breast cancer detection
Authors: Xiao Xia  , Song Hang  , Wang Liang  , Wang Zong-Jie  , Lu Hong  ,   School of Electronic Information Engineering, Tianjin University, Tianjin 300072, China;,   Department of Radiology, Tianjin Medical University Cancer Institute and Hospital, Key Laboratory of Breast Cancer Prevention and Therapy of Ministry of Education, Tianjin 300060, China
Published: December 2020

An ultra-wideband (UWB) microwave robust Capon beamforming imaging system is presented based on a self-designed compact UWB antenna for early breast cancer detection. Simulation results show that the proposed detection system is sensitive to tumor response. Simulated tumor detection experiments are carried out in both simple planar breast model and magnetic resonance imagining (MRI)-derived model using the antenna array. Robust Capon beamforming algorithm is employed to reconstruct the breast image. Successful detection of 3-mm-diameter tumor is achieved in the planar model and the same detection result of 4-mm-diameter tumor is achieved in the MRI-derived model. The right information of the tumor can be obtained from the imaging results, which demonstrates the feasibility of the proposed system in early breast cancer detection.
Line-field parallel spectral domain optical coherence tomography and its application in defect inspection
Authors: Zhao Chen  , Chen Zhi-Yan  , Ding Zhi-Hua  , Li Peng  , Shen Yi  , Ni Yang  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

For the needs of online nondestructive testing method in glass industry, we have presented a large-range line-field parallel spectral domain optical coherence tomography system. Based on fast area scan CMOS camera, the whole cross-sectional image can be acquired by a single shot. Depth-resolved image at different lateral positions can be acquired simultaneously, without the lateral scanning mechanism. The axial resolution is 17.9 μm, the lateral resolutions in parallel direction and scanning direction are 55.7 μm and 24.8 μm, respectively. The system measurement range is 32 mm in lateral direction and 6 mm in axial direction. At 1 mm axial position, the system sensitivity can reach 62 dB at a rate of 128 000 A-scan/s. By using the present system, application in glass defect inspection has been investigated.
High accuracy phase reconstruction of digital hologram by Hilbert transform
Authors: Fan Feng  , Li Jun-Xiang  , Song Xiu-Fa  , Zu Qiao-Fen  , Wang Hua-Ying  ,   College of Science, Hebei University of Engineering, Handan 056038, China;,   College of Clinical Medicine, Hebei University of Engineering, Handan 056002, China
Published: December 2020

To improve the phase accuracy of the reconstructed image of the digital hologram, we investigate the theory and method of the phase reconstruction based on the Hilbert transform, then, verify it by the image plane digital holographic experiment, and finally, compare it with the conventional digital holographic reconstruction method. Results show that Hilbert transform itself posseses the effect of eliminating DC term, therefore the effect of the zero-order frequency spectrum of the hologram which is filtered by frequency domain can be completely eliminated by Hilbert transform. Compared with the conventional Fourier reconstruction mehtod, the accuracy of the phase image can be improved by the reconstruction method based on Hilbert transform, and the standard deviation of the phase image is reduced by 14% in the experiment of red blood cell. This result has an important guiding significance to improve the accuracy of the digital holographic phase reconstruction.
Study of the diffraction grating designed based on the Bragg reflection structure
Authors: Li Bao  , Zhu Jing-Ping  , Du Bing-Zheng  ,   Shanxi Key Laboratory of Information Photonic Technique, Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School ofElectronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Based on the fact that Bragg reflection grating (BRG) is a special case of one-dimensional photonic crystal, we may apply the one-dimensional photonic crystal band gap theory to design the BRG. OptiFDTD is used to simulate both the width error and tilt angle error in BRG. It turns out that the diffraction efficiency will stay high at the 10% width error or the 10° tilt angle error of the Bragg grating. These indicate that the BRG has a high fabrication tolerance. One model of a Bragg diffraction double-grating in the Rowland circle structure is proposed based on the one-dimensional photonic crystal band gap theory for achieving the two-band spectral diffraction. Result shows that the diffraction efficiency of the two incident bands can be as high as 70% when the first set of Bragg grating periods is 6 layers while the second is 10. It is significantly higher than the traditional deeply etched diffraction grating. This is the foundation of a new type of EDG-WDMer with its advantages being of small size and high diffraction efficiency. It may have great potentiality for developing high diffraction efficiency dense wavelength division multiplexer in the future.
Time-varying characteristics of the waveguide invariant under internal wave condition in the shallow water area
Authors: Song Wen-Hua  , Hu Tao  , Guo Sheng-Ming  , Ma Li  ,   Institute of Acoustic, Chinese Academy of Sciences, Beijing 100190, China;,   Key Laboratory of Underwater Acoustic Environment, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

To explain the change of the waveguide invariant β caused by the internal wave, the waveguide invariant is expressed as a stochastic distribution and the time-varying characteristics of β are analyzed; then the cause and principle of variation of β are discussed in terms of the normal modes theory of the acoustic field. It turns out that the waveguide invariant shows great frequency-dependent characteristics. And in the internal wave environment, when the sound is propagated parallel to the internal wave front, the sound field's composition of normal modes remains unchanged, but the turbulence in the group slowness and phase slowness of the main normal modes in the sound field may also change the distribution of β; when the sound is propagated perpendicular to the internal wave front, the coupling between acoustic normal modes might also cause obvious changes in the values of β.
Recent advances in hyper-velocity flyer launch experiments on PTS
Authors: Wang Gui-Lin  , Guo Shuai  , Shen Zhao-Wu  , Zhang Zhao-Hui  , Liu Cang-Li  , Li Jun  , Zhang Zheng-Wei  , Jia Yue-Song  , Zhao Xiao-Ming  , Chen Hong  , Feng Shu-Ping  , Ji Ce  , Xia Ming-He  , Wei Bing  , Tian Qing  , Li Yong  , Ding Yu  , Guo Fan  ,   Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China;,   Key laboratory of pulsed power, Institute of Fluid physics, CAEP, P. O. Box 919-108 Mianyang 621900, China
Published: December 2020

Magnetically driven loading technology is to load the large pulse current to the test area through the pulsed power, which forms a smooth magnetic pressure rising over time to achieve a quasi-isentropic compression of sample and hyper-velocity flyer launch. Based on the output characteristics and parameters of PTS accelerator, two types of hyper-velocity flyer launch experiments with different load configurations, such as the load, flyer plates size, current waveform and diagnostic systems etc, are designed and tested. LY12 aluminum flyer plates with dimensions of 10 mm0.725 mm was launched by single-sided stripline load configuration to 11.5 km/s while the magnetic drive load pressure is near 0.9 10^5 MPa. Simulation and experimental results agrees well with those of in the flyer launch process and the ultimate velocity. Further simulation shows that the launch velocity of aluminum flyer plates with dimensions of 8.5 mm1 mm is expected to exceed 15 km/s under the program of optimizing the structural parameters and regulation. The design and experiment technology of hyper-velocity flyer launch based on multi-branch pulsed power generator has been mastered during the designs and experiments.
Dynamical study on the stimulated absorption and emission in a coujugated polymer
Authors: Wang Wen-Jing  , Meng Rui-Xuan  , Li Yuan  , Gao Kun  ,   School of Physics and Electronic Engineering, Qilu Normal University, Jinan 250013, China;,   School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China;,   School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332, USA
Published: December 2020

By applying a femtosecond electric pump pulse to a poly(p-phenylene vinylene) (PPV) molecule, we theoretically investigate the dynamical processes for its stimulated absorption and emission. The simulations are performed within the framework of an extended version of one-dimensional Su-Schrieffer-Heeger tight-binding model combined with a nonadiabatic evolution method. Firstly, we set the molecule initially lying in the ground state, by which we give the relation between different stimulated transition modes and the photoexciting pulse. Analysis of the final states shows that we can only obtain some electron-hole binding states by an external photoexcitation for the molecule, which includes exciton, biexciton, and high-energy exciton. We have calculated their yields and find that they are determined by the photoexciting energy. In addition, based on the experimental observations, we separately investigate the effect of the photoexciting intensity on the yields of biexciton and high-energy exciton. The calculated results are consistent with the corresponding experimental speculations. Finally, by setting the molecule lying in an exciton or a biexciton, we focus on the stimulated emission process between their generated intragap states. Effects of the photoexciting energy and intensity on them are separately analyzed. These results might be of great importance for further improving the optical applications of polymers, especially for optimizing the polymer photovoltaic and laser properties.
Studies on synthesis of boron-doped Gem-diamond single crystals under high temperature and high presure
Authors: Xiao Hong-Yu  , Li Shang-Sheng  , Qin Yu-Kun  , Liang Zhong-Zhu  , Zhang Yong-Sheng  , Zhang Dong-Mei  , Zhang Yi-Shun  ,   School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;,   Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023, China;,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

In this paper, by choosing catalyst of FeNiMnCo alloy, boron-doped diamond single crystals are synthesized under 5.1–5.6 GPa and 1230–1600℃; the temperature field is studied by finite element method (FEM). First, the P-T phase diagram for diamond single crystal growth, in the synthesis system of FeNiMnCo-C-B, is obtained, and the lowest synthesis conditions of 5.1 GPa and 1230℃ is found in the studies. By simulation with FEM, it is found that the content of boron element should be less and less in the growth of diamond single crystal in the {111} sector, and the reason is that the growth speed is reduced in the sectors. By growing diamond crystals with {111} faces, it is also found that the content of boron element in {111} secondary sector is greater than that in {111} primary sector, which is duo to the rapid growth of {111} secondary sector. Compared with the synthesis of diamond single crystal by film growth method, the diamond crystals thus obtained has no pits, the doping content of boron can be greater, and the diamond can be synthesized by temperature gradient method.
Preparation and electrochemical properties of Co2SnO4/graphene composites
Authors: Chen Chang  , Ru Qiang  , Hu She-Jun  , An Bo-Nan  , Song Xiong  ,   Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China;Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education), Guangzhou 510006, China
Published: December 2020

Co2SnO4/graphene composite has been prepared by multi-step synthetic process. Firstly, the formation of Co2SnO4 and the reduction of graphene oxide (GO) occur simultaneously during the hydrothermal process and the Co2SnO4 particles are uniformly embedded in the film-like graphene to form a mosaic structure. To characterize the phase and morphology of the composite material, X-ray diffraction (XRD), scanning electron microscope (SEM) are used. The constant current charge and discharge (CC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are also used to test the electrochemical performance of Co2SnO4/graphene composite. Results show that graphene can effectively improve the electrochemical performance of Co2SnO4/graphene composite by its good dispersibility and high electrical conductivity. The composite material exhibits a first discharge specific capacity of 1415.2 mA·h/g with the specific capacity still higher than 469.7 mA·h/g after 50 cycles.
Frequency estimation of undersampled sinusoidal signal based on chinese remainder theorem
Authors: Huang Xiang-Dong  , Ding Dao-Xian  , Nan Nan  , Wang Zhao-Hua  ,   School of Electronic Information Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

Frequency estimation based on the reconstruction algorithm of the Chinese remainder theorem(CRT) is one of the frontier focuses in the fields of signal processing, electromagnetism, and optics etc. Howerver, the existing studies can only realize a rough frequency estimation of complex exponential signals. Hence this paper generalizes the CRT-based frequency reconstruction from a rough frequency estimation of complex exponential signals to the accurate frequency estimation of sinusoidal signals. The procedure of the proposed estimation scheme is as follows: (1) Detect zero crossing point on the original high-frequency sinusoidal waveform so as to determine the ideal phase information; (2) implement fast Fourier transform(FFT) to each path's undersampled signal, and then use Candan estimator to correct the frequencies at the peak FFT spectral bins so that the frequency biases can be extracted to realize phase correction; (3) use the proposed classification method based on phase features to screen the corrected remainders; (4)substitute the filtered frequency remainders into the closed-form robust Chinese remainder theorem to obtain the high-accuracy frequency estimation of the original signal. Additionally, this paper also deduces the theoretic expressions of the frequency estimation variance, which is also verified through numerical simulation. And the experimental results also reflect that the proposed scheme possesses high precision and high robustness to noise.
Study on the transmission system of high frame rate ultrasonic imaging based on the non-diffraction wave
Authors: Wei Yong-Mei  , Peng Hu  ,   Department of Physics and Electronic Information Science and Technology, Fuyang Teachers College, Fuyang 236041, China;,   Department of Medical Engineering, Hefei University of Technology, Heifei 230026, China
Published: December 2020

Array beam field is a necessary condition for high frame rate(HFR) ultrasonic imaging system according to the non-diffraction wave theory. However, the sine function characteristic of array beam waves makes it more difficult to weight the ultrasonic wave transmission signal so the transmission system is very complex. To solve this problem, this paper proposes an effective solution. Based on Fourier transform theory, the energy component of the square wave focuses mainly on the fundamental wave. In this paper a kind of square wave with a single value is utilized to weight the transmitted signals from an ultrasonic transducer. Thus only one power signal source and a very simple electronic switch system can be used to achieve this kind of transmission circuit in the HFR system. Experiments show that such an option has little impact on the image quality of the HFR, however it greatly simplifies the HFR ultrasound imaging system.
Extended complex autoregressive model of low-frequency rainfalls over the lower reaches of Yangtze river valley for extended range forecast in 2013
Authors: Yang Qiu-Ming  ,   Jiangsu Meteorological Institute, Nanjing 210009, China
Published: December 2020

Low-frequency rainfall over the lower reaches of Yangtze river valley (LYRV) and the principal component of the global 850 hPa meridional wind anomalies are adopted to construct an extended complex autoregressive (ECAR) model, which can be applied to the daily forecasting of the low-frequency rainfall component over LYRV in 2013 for the extended range forecast. Results show that this model for the forecasting of the 2030-day rainfalls over LYRV has a good predictive skill up to 43 days, which is able to well predict the nonlinear enhancement processes of low-frequency rainfall component associated with heavy rainstorm process. And the correlation skill of the extended range forecast produced form the ECAR model is superior to the autoregressive model (AR) forecast. This method, in which the complex autoregressive (CAR) models are set up via constructing the extended complex matrix (ECM) for the principal low-frequency time series, provides a new description for the emerging dynamic processes of the interactions between components in climate systems. Based on the development and evolution of the principal 2030-day oscillations of the global circulation, it is help for better forecast the process of heavy rainfall in the early October of 2013 over LYRV for times ahead of about 27 days. In these low-frequency variabilities, the 2030-day oscillation in extratropics over the Southern Hemisphere is one of the main factors causing the changes of the heavy rainfall over LYRV for the extended range during the summer and fall in 2013.
Exact solutions of Whitham-Broer-Kaup equations with variable coefficients
Authors: Liu Yong  , Liu Xi-Qiang  ,   School of Mathematical Sciences, Liaocheng University, Liaocheng 252059, China
Published: December 2020

An equivalence transformation of Whitham-Broer-Kaup equations with variable coefficients (VCWBK) is obtainedby using modified Clarkson-Kruskal direct method. Further, the relationship between the solutions of VCWBK equationsand ones of the corresponding WBK equations with constant coefficients is obtained. In addition, by applying directsymmetry method, some symmetries and similarity reductions of the corresponding WBK equations with constantcoefficients are derived. Using an auxiliary function to solve some special cases, we obtain some new exact solutionsof VCWBK equations, including rational solutions, hyperbolic function solutions, trigonometric function solutions, andJacobi elliptic function solutions.
Microwave and light wave radar cross section similitude with unequal electrical length
Authors: He Jing  , Miao Qiang  , Wu De-Wei  ,   Information and Navigation Institute, Air Force Engineering University, Xi'an 710077, China
Published: December 2020

According to small size and easy-to-realize features of visible light radiator, a new idea of adopting light wave produced by light radiator models to measure an object microwave radar cross section (RCS) at big scale factor is presented. The similitude of object RCS in inequal electrical length condition is discussed. The constrained condition and compensation process for such a model measurement are also provided.
Analysis and relief method of reentry aerodynamic load based on matched asymptotic expansions method
Authors: Du Xin  , Li Hai-Yang  ,   College of Aerospace Science and Engineering, National University of Denfense Techlonogy, Changsha 410073, China
Published: December 2020

Reentry velocity of lunar module reaches the second cosmic velocity, which could make the aerodynamic environment insupportable. So it is essential to analysis the reentry aerodynamic load. The equation of motion for reentry vehicle is a group of ordinary differential equations, and numerical methods are inadequate for online mission because their computation amount is too large. An analytical method of solving the reentry equation of motion is proposed in this paper to analyze the reentry aerodynamic load. First, matched asymptotic method is used to obtain solutions of longitudinal equation of motion in outer and inner region independently and combine them to obtain a unified closed-form solution. Reentry aerodynamic load has been analyzed in three fragments using the closed-form solution, and approximate solution of load is compared with the exact solution. Second, suppositional initial conditions are obtained by solving the closed-form solution using current state, then an analytical method of predicting the first load peak is proposed, and the relative prediction error is analyzed for different bank angles. Third, the load relief method based on load peak prediction is proposed, which can redistribute the total dissipated energy in the whole reentry process, and the validity of the method is verified by Monte Carlo simulation.
Multi-fractal detrended fluctuation analysis algorithm based identification method of scale-less range for multi-fractal charateristics of traffic flow
Authors: Xiong Jie  , Chen Shao-Kuan  , Wei Wei  , Liu Shuang  , Guan Wei  ,   MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Scale-less range is an interval of measurement of time series in which fractional self-similarity exists statistically. In order to solve the problem of the lack of necessary steps to calculate fractal range in multi-fractal detrended fluctuation analysis algorithm (MF-DFA) in traffic flow, a new scale-less identification method based on MF-DFA is proposed through analyzing the characteristics of the mutation point in logistic curve of traffic flow wave function in steps of MF-DFA and the principles of the traditional fractal scale-less range identification method. Beijing's road network is taken for example to investigate the fractal scale-less range. Analysis results show that the identification method based on MF-DFA algorithm is valid, automatic and steady in identifying the fractal scale-less range in Beijing's traffic flow. Further, the reason why the scale-less range in traffic is limited is that small traffic flow waves account for a bigger percentage in scale-less range while big wave is bigger so that it is out of the scale-less range.
Transformation of vector solitons in twospecies Bose-Einstein condensates
Authors: Zhang Wei-Xi  , Zhang Zhi-Qiang  , Ran Mao-Wu  , Ou Yong-Kang  , He Zhang-Ming  ,   Department of Physics and Application Science, Tongren University, Tongren 554300, China;,   Department of Basic Course, Zhengzhou College of Science and Technology, Zhengzhou 450064, China;,   College of Science, Hunan University of Technology, Zhuzhou 412007, China
Published: December 2020

Considering the interspecies and intraspecies interactions as being repulsive, we study the dynamic behaviors of the gray-gray and black-black solitons in two-species Bose-Einstein condensates trapped in the harmonic external potentials. The results show that in the absence of the axial trapping frequencies, both the gray-gray and black-black solitons can keep localization stable. In the presence of the axial trapping frequencies, the gray-gray can be converted into bright-bright solitons.
Research on charge trapping memory’s over erase
Authors: Wang Jia-Yu  , Dai Yue-Hua  , Zhao Yuan-Yang  , Xu Jian-Bin  , Yang Fei  , Dai Guang-Zhen  , Yang Jin  ,   School of Electronics and Information Engineering, Anhui University, Hefei 230601, China
Published: December 2020

In this paper, charge trapping memory (CTM) is studied for analyzing the over-erase phenomenon, based on the first principles and VASP package. The nitrogen vacancy (VN) in Si3N4 and the interstitial oxygen (IO) in HfO2 are selected as model, because of the formation energy. The result about trapping energy shows that the electrons are trapped more easily than holes in these models, so the electrons are selected as programming/erase object. The energy after programming/erase operation, Bader charge analysis, different charge densities, adsorption energy and density of states are all studied to explain the over-erase micro change. The energy and electron change show that HfO2 as trapping layer makes CTM more reliable than Si3N4 as trapping layer; and after a programming/erase cycle, electrons in Si3N4 are erased more than programming ones; and the result of adsorption energy shows that the electrons can exchange more easily in Si3N4 than in HfO2. Finally, the research on the density of states shows that Si3N4 has shallow trapping energy level, HfO2 has deep trapping energy level. In conclusion, the essence of the over-erase in Si3N4 is that the atoms near the defect have weaker localized action on the electrons, resulting in the instinct electrons that are erased in erase operation. The over-erase essence is revealed, which is of benefit to improving the reliability and retention.