bluuebunny/crossref_metadata_2025 huggingface dataset:
Extreme pH-induced lateral reorganization of supported lipid bilayer by fluorescence microscope
Authors: Sheng Jie  , Zhang Guo-Liang  , Li Yu-Qiang  , Zhu Tao  , Jiang Zhong-Ying  ,   Physics School of Nanjing University, Nanjing 210093, China;,   College of Electronic and Information Engineering, Yili Normal University, Yining 835000, China;,   Physical Science and Technology, Yili Normal University, Yining 835000, China
Published: December 2020

The extreme pH-induced lateral reorganization of supported lipid bilayer membranes are studied by fluorescence microscopy. The results show that the fluid dioleoyl-phosphatidylcholine bilayers in extreme acidic or basic solution presents a similar phenomenon to endocytosis and exocytosis, such as rupture, detachment, budding, formation of microtubules etc. In the view of the interaction of polar molecules with H+/H3O+ or OH ions, we conclude that the zwitterionic phospholipid headgroup as core adsorbs the H+/H3O+ or OH ions in electrolyte solution. The asymmetric charge adsorption quantity of the lipid headgroups leads to the effective area discrepancy between the outer and inner leaflets of lipid bilayers. The asymmetric membrane curvatures induce a variety of structures and dynamic responses. The present study helps explain lipid membranes reorganization under extreme pH conditions and provides some guidelines for deformation process of lipid membranes.
Two-dimensional device simulation and performance optimization of crystalline silicon selective-emitter solar cell
Authors: Jia Xiao-Jie  , Ai Bin  , Xu Xin-Xiang  , Yang Jiang-Hai  , Deng You-Jun  , Shen Hui  ,   Guangdong Provincial Key Laboratory of Photovoltaic Technologies, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510006, China;,   CSG R&D Center of Solar Energy Division, CSG Holding Co. Ltd, Dongguan 523141, China
Published: December 2020

In this paper, device simulation and parameter optimization on crystalline silicon (c-Si) selective-emitter (SE) solar cell are performed by using PC2D two-dimensional simulator. On the basis of achieving perfect fitting to the measured I-V curve of a typical c-Si SE solar cell fabricated by screen printing phosphoric paste method, the effects of physical parameters of gridlines, base, selective emitter and back surface field layer on the optoelectronic performance of the SE solar cell are comprehensively and systematically investigated. Simulation results show that the base minority carrier lifetime, the front surface recombination velocity and the back surface recombination velocity are the three largest efficiency-affecting parameters. In the studied parameter range, when the base minority carrier lifetime rises from 50 s to 600 s, the cell efficiency increaes from 18.53% to 19.27%. Low front surface recombination velocity is the premise of making the optimization of selective emitter sheet resistance meaningful. To obtain an ideal efficiency, the back surface recombination velocity should be controlled to be under 500 cm/s. In addition, under different front surface recombination velocities, the maximum of cell efficiency is always achieved in a range of 5090 / heavily doped region sheet resistance and 110180 / lightly doped region sheet resistance. For different numbers of gridlines, when the radio of heavily doped region width to the gridline pitch equals 32%, the solar cell has the highest efficiency. Moreover, under the condition of low area radio of bas bar, increasing bus bar number appropriately can improve the efficiency. The efficiency of p-type SE solar cell reaches 20.45% after optimization.
Evolution mechanism of node importance based on the information about cascading failures in complex networks
Authors: Duan Dong-Li  , Zhan Ren-Jun  ,   College of Equipment Engineering, Engineering University of Armed Police Force, Xi’an 710008, China
Published: December 2020

This paper mainly focuses on the evolution mechanism of node importance based on the information about cascading failures. Firstly, a novel node importance indicator is proposed according to the load turbulence of each node in the redistribution range based on a tunable load redistribution model. The indicator has two characteristics: one is that the failure consequence of the considered node can be clearly pointed out by its value, and the other is that the evolution mechanism of node importance can be analyzed with the factors of load redistribution rule, node capacity, and structural characteristics of the network. Then, an evaluation algorithm is presented. The indicator analytic formulas of Erdös-Rényi networks and Barabási-Albert networks are also presented respectively with the neighbor preferential and global preferential allocation rules. The experiments demonstrate the effectiveness and feasibility of the indicators and its algorithm, with which we also analyze the node importance evolution mechanism in-depth, namely how the not-so-great nodes in structure turns into the critical nodes to trigger cascading failure in complex networks.
Elastic wave propagation characteristics under anisotropic squirt-flow condition
Authors: Wang Ding  , Zhang Mei-Gen  ,   Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, the Chinese Academy of Sciences, Beijing 100029, China;,   University of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A theoretical model of elastic wave propagation in a cracked porous medium is developed in this paper. When elastic wave propagates through the cracked porous medium, the different physical properties and geometries in different pores structures lead to the fluid pressure gradient in cracks and between cracks and pores. The squirt-flow will take place in two mutually-perpendicular directions, thus, it has anisotropic characteristic. The wave respond contains the crack and background medium permeability information simultaneously. Owing to the fluid dynamic flow process, the effective elastic modulus is complex and frequency-dependent. When the wave frequencies are in high and low limit, the porous medium is elastic. The wave attenuation is obvious and the attenuation is frequency-dependent in the middle frequency region. The anisotropic permeability corresponding to anisotropic characteristic times in the cracked porous medium causes the wave propagation to be affected by the crack connectivity. There appears a second attenuation peak for larger thickness value of crack, meanwhile, and the peak of attenuation is influenced by the thickness value and radius of crack.
Test particle simulation of resonant interaction between energetic electrons in the magnetosphere and ELF/VLF waves generated by ionospheric modification
Authors: Chang Shan-Shan  , Ni Bin-Bin  , Zhao Zheng-Yu  , Wang Feng  , Li Jin-Xing  , Zhao Jing-Jing  , Gu Xu-Dong  , Zhou Chen  ,   Department of Space physics, School of Electronic Information, Wuhan University, Wuhan 430072, China;,   Department of Optoelectronic Information, School of Electronic and Electrical Engineering, Wuhan Textile University, Wuhan 430200, China;,   Institute of Space Physics and Applied Technology, Peking University, Beijing 100871, China
Published: December 2020

Ionospheric modulation can artificially trigger ELF/VLF whistler waves, which can leak into the inner magnetosphere and contribute to resonant interactions with energetic electrons. Combining the ray tracing method and test particle simulations, we investigate the propagation of these artificially generated ELF/VLF waves through the high ionosphere into the inner magnetosphere, and evaluate the subsequent effects of resonant scattering energetic electrons near the heart of the outer radiation belt. The results show that the artificially triggered ELF/VLF waves become highly oblique in the magnetosphere and their spatial extent of L shell and magnetic latitude can be significantly controlled by the initial launch latitude. Corresponding to the principal first-order resonance, the energetic electrons from ～ 100 keV to 3 MeV can resonate with the artificial VLF waves with frequency above 10 kHz in the inner radiation belt, while in the outer radiation belt these hazardous electrons can resonate with ELF waves from ～100 Hz to 1 kHz. At L=4.5 as the focus in this study, the artificial ELF waves can resonate with 1 MeV electron at the harmonics N=-1, 1, 2. In contrast, the Landau resonance rarely occurs for these energetic electrons. The results of test particle simulations indicate that while wave-induced changes in pitch angle and kinetic energy of a single electron are stochastic, the change averaged over all test electrons increases monotonically within the resonance timescale, which implies that resonant scattering is an overall characteristic of energetic electrons under the influence of the artificial whistler waves. Computed resonant scattering rates based on the test particle simulations indicate that aritificial ELF/VLF waves with an observable in situ wave amplitude of ～ 10 pT can drive efficient local pitch angle scattering of energetic electrons at the magnetic equator, thereby contributing considerably to their precipitation loss and magnetospheric electron dynamics. When the waves become highly oblique during the propagation, besides the fundamental first order resonance, higher order resonances can also drive efficient electron scattering. The results support the feasibility of generating artificially ELF/VLF whistler waves for controlled removal of energetic electrons in the Earth radiation belts.
Low light level image target detection based on texture saliency
Authors: Jin Zuo-Lun  , Han Jing  , Zhang Yi  , Bai Lian-Fa  ,   Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Owing to its low contrast, the target of low light level (LLL) image is not very salient, and it is difficult to detect automatically. Aimed at this problem, this paper proposes a noise robustness algorithm for computing the local texture coarseness (LTC) of textured images, and provides a texture saliency (TS) calculation method that is applicable to saliency analysis of LLL image. Firstly, we present a novel LTC algorithm, by which the LTC around a pixel using the best size of the pixel. Compared with coarseness measure based on local fractal dimension, the LTC algorithm shows much better noise robustness in the experiments of noised textured images. Then, a TS algorithm is given based on the extraction of texture coarseness feature map. Finally, we apply the TS algorithm to LLL image target detection, which is efficient proved by experimental results.
Damped brachistochrone problem and the relation between constraint and theorem of motion
Authors: Ding Guang-Tao  ,   College of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
Published: December 2020

The damped brachistochrone problem and that with non-zero initial velocity are studied. Based on the discussion of these problems, one may take theorems of motion as constraints for some systems, and whether the constraints are holonomic or nonholonomic is related to the fact that the differential theorems of motion are integrable or non-integrable.
Symplectic FDTD algorithm for the simulations of double dispersive materials
Authors: Wang Hui  , Huang Zhi-Xiang  , Wu Xian-Liang  , Ren Xin-Gang  , Wu Bo  ,   The Key Laboratory of Intelligent Computing and Signal Processing, Ministry of Education, Anhui University, Hefei 230039, China;,   Department of Physics and Engineering, Hefei Normal College, Hefei 230061, China;,   Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
Published: December 2020

Combined with the Lossy Drude-Lorentz dispersive model, a symplectic finite-difference time-domain (SFDTD) algorithm is proposed to deal with the double dispersive model. Based on matrix splitting, symplectic integrator propagator and the auxiliary differential equation (ADE) technique, with the rigorous and artful formula derivation, the algorithm is constructed, and detailed formulations are provided. Excellent agreement is achieved between the SFDTD-calculated and exact theoretical results when transmittance coefficient in simulation of double dispersive film in one dimension is calculated. As to numerical results for a more realistic structure in three dimensions, the simulation of periodic arrays of silver split-ring resonators using the Drude dispersion model are also included. The transmittance, reflectance, and absorptance of the structure are presented to test the efficiency of the proposed method. Our method can be used as an efficiency simulation tool for checking the experimental data.
Spectrum calculation of chaotic SPWM signals based on double fourier series
Authors: Liu Yong-Di  , Li Hong  , Zhang Bo  , Zheng Qiong-Lin  , You Xiao-Jie  ,   School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China;,   School of Electric Power, South China University of Technology, Guangzhou 510640, China
Published: December 2020

Chaotic SPWM control has attracted much interests due to its effectiveness for EMI suppression in power converters. However, most researches focus on the simulation and experiment of power converter under chaotic SPWM control, which is lacking a quantitative method. Based on double Fourier series this paper provides a spectrum calculation method for multi-period SPWM or quasi-random SPWM signals firstly, and the related spectrum calculation and simulation for multi-period SPWM are given to verify the accuracy of the spectrum calculation method; then the calculation method is extended to the spectral analysis of chaotic SPWM signals. To observe the impact on the spectrum of chaotic SPWM signals generated by different mappings and in different variation ranges of carrier period, a spectrum comparison between the Tent and Chebyshev mappings is conducted, in which results indicate that the variation range of the carrier period and the selection of mappings have a great influence on spectrum distribution; in the long term, probability density distribution of chaotic mapping will certainly affect the spectrum, and in the short term the initial value of the mapping will also affect the spread spectrum distribution. In summary, the proposed spectrum calculation method in this paper provides a theoretical foundation for the spread spectrum principle of chaotic SPWM control and for the design reference in practical engineering application.
Thermal-sensitive superconducting coplanar waveguide resonator used for weak light detection
Authors: Zhou Pin-Jia  , Wang Yi-Wen  , Wei Lian-Fu  ,   Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031, China;,   State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
Published: December 2020

Since the last decades, superconducting single-photon technology has been extensively used in the quantum security communication and the linear-optic quantum computing fields. Especially, the device based on the coplanar waveguide resonator has attracted substantial interests due to its evident advantages, including the relatively simple structure, the sufficiently high detection efficiency, and the photon-resolving capability, etc. With the profound investigation in optimizing the depositing methods and the material selections, as well as the the development of the relevant theories, the technology of single photon detection based on the coplanar waveguide resonator has obtained a breakthrough. In this review paper we begin from the basic principle of the coplanar waveguide detector, then interpret the relevant theory and some design details of the devices. Finally, based on some of the recent experimental results measured with the low-temperature devices in our lab, we give a brief perspective on the future development of the superconducting coplanar waveguide single photon detectors.
A new method of background elimination and baseline correction for the first harmonic
Authors: Zhang Rui  , Zhao Xue-Hong  , Hu Ya-Jun  , Guo Yuan  , Wang Zhe  , Zhao Ying  , Li Zhi-Xiao  , Wang Yan  ,   College of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China;,   College of Electronic Information and Automation, Tianjin University of Science & Technology, Tianjin 300222, China
Published: December 2020

A new method of background elimination and baseline correction is proposed, since there are background signal and larger baseline signal in the first harmonic (1f) of the tunable diode laser absorption spectroscopy (TDLAS). The laser-associated intensity modulation signal, electronic noise, and optical interference fringes of the 1f background are analyzed. Harmonic detection in none absorption spectral region (HDINASR) is used to eliminate the background signal. Then the relationship curve between current and intensity is given in different operating temperatures to design a remaining baseline correction method after eliminating the background. The principle of background signal searching and the LabView software flow chart are also given. The TDLAS experimental system is designed to detect hydrogen fluoride (HF) gas. According to spectral line selection principle, the absorption line -1312.59 nm is selected, whose operating temperature is set at 27.0 ℃ and the background temperature is set at 30.2 ℃. After eliminating the background and correcting the baseline, signal distortion is significantly improved and baseline is corrected. Then it is verified that the method is valid at other operating temperature of the laser (26.7-27.2). And the improvement of HF gas concentration is quantitatively analyzed. It is convenient for the subsequent processing of 1f signal.
A block-based improved recursive moving-target-indication algorithm
Authors: Hou Wang  , Yu Qi-Feng  , Lei Zhi-Hui  , Liu Xiao-Chun  ,   College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A new block-based recursive moving-target indication algorithm in velocity domain is proposed to solve the problem which is the rapid detection of dim and small target for infrared search and tracking system. Firstly, the two-dimensional least mean square filter is adopted to filter the infrared image sequence, which extracts small targets and residual errors of image sequence. Then, block-based recursive moving-target indication algorithm is adopted to accumulate small target in image block sequence for the enhancement of small target velocity in velocity domain. Finally, resulting image is obtained by using classical recursive moving-target indication algorithm and target velocity for small target detection. Compared with classical method, the proposed method requires less running time, and can be used to detect dim small target image effectively as demonstrated by several groups of experimental results.
Calibration of D-RGB camera networks by skeleton-based viewpoint invariance transformation
Authors: Han Yun  , Chung Sheng-Luen  , Yeh Jeng-Sheng  , Chen Qi-Jun  ,   College of Electronics and Information Engineering, Tongji University, Shanghai 201804, China;,   Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei 10607, China;,   Department of Computer and Communication Engineering, Ming Chuan University, Taipei 150001, China
Published: December 2020

Combining depth information and color image, D-RGB cameras provide a ready detection of human and associated 3D skeleton joints data, facilitating, if not revolutionizing, conventional image centric researches in, among others, computer vision, surveillance, and human activity analysis. Applicability of a D-RBG camera, however, is restricted by its limited range of frustum of depth in the range of 0.8 to 4 meters. Although a D-RGB camera network, constructed by deployment of several D-RGB cameras at various locations, could extend the range of coverage, it requires precise localization of the camera network: relative location and orientation of neighboring cameras. By introducing a skeleton-based viewpoint invariant transformation (SVIT), which derives the relative location and orientation of a detected humans upper torso to a D-RGB camera, this paper presents a reliable automatic localization technique without the need for additional instrument or human intervention. By respectively applying SVIT to two neighboring D-RGB cameras on a commonly observed skeleton, the respective relative position and orientation of the detected humans skeleton for these two cameras can be obtained before being combined to yield the relative position and orientation of these two cameras, thus solving the localization problem. Experiments have been conducted in which two Kinects are situated with bearing differences of about 45 degrees and 90 degrees; the coverage can be extended by up to 70% with the installment of an additional Kinect. The same localization technique can be applied repeatedly to a larger number of D-RGB cameras, thus extending the applicability of D-RGB cameras to camera networks in making human behavior analysis and context-aware service in a larger surveillance area.
Bifurcation and chaos of some strongly nonlinear relative rotation system with time-varying clearance
Authors: Liu Bin  , Zhao Hong-Xu  , Hou Dong-Xiao  , Liu Hao-Ran  ,   College of Electrical Engineering, YanShan University, Qinhuangdao 066004, China;,   Department of Control Engineering Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
Published: December 2020

The dynamic equation for the relative rotation nonlinear dynamic system with time-varying clearance is investigated. Firstly, transformation parameter is deduced by using the method of MLP; the bifurcation response equations of 1/2 harmonic resonance then are generated by the method of multiple scales, while singularity analysis is employed to obtain the transition set of steady motion; further more the bifurcation characteristic and the bifurcation of the system under the situation of non-autonomy are analyzed. Finally, numerical simulation exhibits many different motions, such as periodic motion, period-doubling motion, and chaos. It is shown that the change of clearance and damp parameters may influence the motion state of the system.
Drag reduction on hydrophobic transverse grooved surface by underwater gas formed naturally
Authors: Wang Bao  , Wang Jia-Dao  , Chen Da-Rong  ,   State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Published: December 2020

Low fluid friction is difficult to obtain on super-hydrophobic surfaces for a large flow velocity, because the entrapped gas within the surface is weakened substantially. Once the gas removed, the friction of the fluid increases markedly due to its own surface roughness. In this study, a hydrophobic transverse microgrooved surface is designed to sustain the air pockets in the valleys for a long time. Direct optical measurements are conducted to observe the entrapped gas when water flows past the surface in the perpendicular direction of grating patterns. More importantly, this hydrophobic transverse micro-grooved surface has been determined to have the capability of automatic formation of gas. Some of the gas is continually carried away from the surface and new gas is continually generated to substitute the lost gas. And the stable slippages at the surface are achieved corresponding to the relative stable gas on this designed surface.
Investigation of electromagnetic hydrodynamics propulsion and vector control by surfaces based on a rotational navigation body
Authors: Liu Zong-Kai  , Gu Jin-Liang  , Zhou Ben-Mou  , Ji Yan-Liang  , Huang Ya-Dong  , Xu Chi  ,   Science and Technology on Transient Physics Laboratory, Nanjing University of Science and Technology, Nanjing 210094, China;,   Automation College, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Realization of electromagnetic hydrodynamics (MHD) propulsion by surfaces needs an electromagnetic body force generated in a conductive fluid (such as seawater and plasma, etc.) around the navigation body. Furthermore, the reaction force against the electromagnetic body force could be used to propel. Based on the basic control equations of electromagnetic field and fluid mechanics, the vector control effect has been analyzed by virtue of field intensity and force distribution characteristic on the rotational navigation body, under two different force action areas. Results show that the navigation attitude adjustment could be realized by this control method without changing attacks and propulsion directions. An upward force moment could be achieved by the control model A. Accordingly, both of the pitching moment and yaw moment could be changed by the control model B. Thus, as a new way of propulsion, the MHD propulsion by surfaces offers several advantages, such as high speed, high efficiency, easy operation, high payload etc. Additionally, in this paper, the vector propulsion has been proved to be one of the remarkable advantages for MHD propulsion by surface.
Characterization of thermal conductivity for GNR based on nonequilibrium molecular dynamics simulation combined with quantum correction
Authors: Zheng Bo-Yu  , Dong Hui-Long  , Chen Fei-Fan  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China
Published: December 2020

A nonequilibrium molecular dynamics model combined with quantum correction is presented for characterizing the thermal conductivity of graphene nanoribbons (GNR). Temperature effect on graphene nanoribbon thermal conductivity is revealed based on this model. It is shown that different from the decreasing dependence in classical nonequilibrium molecular dynamics simulations, an “anomaly” is revealed at low temperatures using quantum correction. Besides, the conductivity of GNR shows obvious edge and scale effects: The zigzag GNR have higher thermal conductivity than the zigzag GNR. The whole temperature range of thermal conductivity and the slope of thermal conductivity at low temperatures both show an increasing dependence of width. Boltzmann-Peierls phonon transport equation is used to explain the temperature and scale effects at low temperatures, indicating that the model constructed is suitable for a wide temperature range of accurate calculation for thermal conductivity of different chirality and width. Research provides a possible theoretical and computational basis for heat transfer and dissipation applications of GNR.
Theoretical analysis of carbon nanotube photomixer-generated terahertz power
Authors: Jia Wan-Li  , Zhao Li  , Hou Lei  , Ji Wei-Li  , Shi Wei  , Qu Guang-Hui  ,   College of science, Xi’an University of Technology, Xi’an 710054, China
Published: December 2020

On the basis of mixer circuit model of light, the terahertz power generated by the carbon nanotubes (CNT) photomixer is analyzed. By simulating mixer conductance, impedance of the antenna, and light plus paranoid voltage, it is shown that the improved mixer conductance, antenna impedance and light plus paranoid voltage can improve the output power of terahertz waves. The output power can reach dozens of microwatt level in the small-signal limit.
Transition metals encapsulated inside single wall carbon nanotubes：DFT calculations
Authors: Liu Man  , Yan Qiang  , Zhou Li-Ping  , Han Qin  ,   Department of Physics and Jiangsu Key Laboratory of thin films, Soochow University, Suzhou 215006, China
Published: December 2020

The transport properties of a single wall carbon tube with transition metal atoms embedded in it are studied by using the first principles method based on the density functional theory and the nonequilibrium Green’s function. Different transition metal atoms filled in the carbon tube are investigated, and the respective charge and spin transport properties are studied. The conductance of the nanotube is found to be distinctive for different metal elements encapsulated, and quantized reductions of conductance can be seen by a quantum unit (2e2/h). In particular, nanotubes with two iron atoms encapsulated in display different I-V curves when the spins of the two iron atoms are in parallel and antiparallel states respectively. These results can be explained by spin-dependent scattering and charge transfer. The encapsulation may tailor the doping and add magnetic behavior to the carbon nanotubes, which would provide a new and promising approach to detect nanoscale magnetic activity.
Luminescence property of Ce3+-Tb3+-Sm3+ co-doped borosilicate glass under various ultraviolet excitations
Authors: Chen Qiao-Qiao  , Dai Neng-Li  , Liu Zi-Jun  , Chu Ying-Bo  , Li Jin-Yan  , Yang Lü-Yun  ,   Wuhan National Laboratory for Optoelectronics, College of optical and electronic information, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Ce3+-Tb3+-Sm3+ co-doped white light emitting borosilicate glasses were fabricated by high-temperature melting technique. In this paper, the excitation spectra and the emission spectra of Ce3+, Tb3+ and Sm3+ ions-doped and co-doped samples were measured and the energy transfer mechanism of Ce3+, Tb3+, and Sm3+ were studied by analyzing the fluorescence lifetime of single-doped and co-doped samples. The color coordinate, rendering index, and color temperature of the emission spectra can be adjusted by changing the excitation wavelength of ultraviolet LED. Finally, we have obtained the white light which fits for life, study, and work.
Double-threshold cooperative spectrum sensing for cognitive radio based on trust
Authors: Zhang Xue-Jun  , Lu You  , Tian Feng  , Sun Zhi-Xin  , Cheng Xie-Feng  ,   Key Laboratory of Broadband Wireless Communication and Sensor Network Technology of Ministry of Education, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;,   School of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

This paper presents a double-threshold cooperative spectrum sensing algorithm which is based on trust and satisfies both reliability and efficiency. The cognitive nodes that satisfy the request of double-threshold have the priority to participate in cooperative sensing and that satisfy the requirement of trust parameters may participate in cooperative sensing if only the number of the former is smaller than a preset value. The fusion center stores the sensing record of each cognitive node and sets the fusion weights according to the partial detected results. Theoretical analysis and simulation show that the bandwidth required for transmitting the sensing parameters decreases, and the detection performance improves because the unreliable users are reduced. Additionally, the algorithm can be made to adapt to different wireless service by adjusting the parameter nt.
An imaging algorithm for missile-borne SAR with downward movement based on variable decoupling
Authors: Jiang Huai  , Zhao Hui-Chang  , Han Min  , Zhang Shu-Ning  ,   School of Electronic & Optical, Nanjing University of Science&Technology, Nanjing 210094, China;,   Institute of information, Southeast China University, Nanjing 210094, China
Published: December 2020

The ordinary SAR imaging algorithms are inapplicable to missile-bo-rne SAR due to the high speed dive and high-squint of missile. Aiming at this problem, this paper firstly sets up the model of echo and analyses of two-dimensional spectrum. By using azimuth nonlinear chirp scaling (NLCS) based on variable decoupling, an imaging algorithm for missile-borne SAR is proposed.It can effectively compensate the scene with longitudinal and transverse Doppler shift and improve the focusing quality while it can also simplify the geometric image correction operation. Simulation results are provided to confirm the effectiveness of the proposed algorithm.
Response function of angle signal in two-dimensional grating imaging
Authors: Ju Zai-Qiang  , Wang Yan  , Bao Yuan  , Li Pan-Yun  , Zhu Zhong-Zhu  , Zhang Kai  , Huang Wan-Xia  , Yuan Qing-Xi  , Zhu Pei-Ping  , Wu Zi-Yu  ,   Institute of high energy physics, Beijing 100049, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

In this paper, we derive the response function of angle signal in a two-dimensional X-ray grating interferometry system under the condition of parallel coherent light, and depict the surface of the function with Matlab.Although there are four kinds of commonly used beam splitter gratings and three kinds of analyzer gratings, and there are still different compound modes between them, we may find that the ultimate surface of the response function of angle signal can only be of three kinds: the peak type, the valley type, and the peak-valley symmetry type of shifting surfaces. As there is a numerical complementary ralationship between the peak type and the valley type of shifting surfaces, we can take the two kinds as one; and finally we only need to consider two kinds of shifting surface.This conclusion simplies the common understanding of the two-dimensional X-ray grating interferometry method, and lays the foundation for the research of quantitatively extracting the two-demensional signal in the future.
Equivalent source reconstruction in inhomogeneous electromagnetic media
Authors: Zhao Chen  , Jiang Shi-Qin  , Shi Ming-Wei  , Zhu Jun-Jie  ,   School of Electronics and Information Engineering, Tongji University, Shanghai 201804, China
Published: December 2020

In this paper, a method that uses magnetic extreme signals for equivalent source reconstruction is presented. Through simulation of specific current dipoles given as the sources of magnetic field signals, the feasibility of a multi-chamber heart model is investigated and the accuracy analysis of equivalent source reconstruction in inhomogeneous media is conducted. The magnitude of the magnetic extreme signals is indicative of the influence of volume conductor on the cardiac magnetic field is analyzed. The method is compared with other four methods which are the method of magnetic gradient extreme signals, the Nelder-Mead algorithm, the trust region reflective algorithm, and the particle swarm optimization algorithm against the criteria in terms of accuracy of source reconstruction and computation time of the algorithm. Results show that the method is practically useful for solving inverse cardiac magnetic field problems.
Effects of NPB anode buffer layer on the performances of inverted bulk heterojunction polymer solar cells
Authors: Gong Wei  , Xu Zheng  , Zhao Su-Ling  , Liu Xiao-Dong  , Yang Qian-Qian  , Fan Xing  ,   Key Laboratory of Luminescence and Optical Information of Ministry of Education, Beijing Jiaotong University, Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Inverted configuration bulk heterojunction polymer solar cells based on ITO/ZnO/P3HT:PCBM/NPB/Ag were fabricated, with the donor material being poly(3-hexylthiophene)(P3HT), and the acceptor material being [6, 6]-phenyl-C60-butyric acid methyl ester(PCBM). N, N’-diphenyl-N, N’-bis(1-naphthyl)-1, 1’-biphenyl-4, 4’-diamine(NPB) thin anode buffer layers with different thicknesses, which were used to improve the performances of the devices; and the effects of NPB anode buffer were investigated. The insertion of 1 nm thick NPB improves charge collection of the device, both of the short circuit current and open circuit voltage are enhanced. When the thickness of NPB reaches 25 nm, the series resistances are significantly increased, leading to reduced device performances. Effects of different thicknesses of NPB on charge injection and collection are investigated by capacitance-voltage measurements. NPB with 1 nm thickness improves charge collection of the device but without improving charge injection, and the charge recombination mechanism is dominant if the NPB layer is too thick. NPB thin layer with appropriate thickness could be used to enhance the performances of bulk heterojunction polymer solar cells.
Research on non-linear beam-wave interaction of W-band Gyro-TWT with helical waveguide
Authors: Xue Zhi-Hao  , Liu Pu-Kun  , Du Chao-Hai  ,   th Institute of Chinese Electronics Technology Group, Shijiazhuang 050000, China;,   School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
Published: December 2020

Gyro-TWT is one of the most promising candidates for the transmitter microwave source of the next generation imaging radar; meanwhile, it plays an important role in national security. Gyro-TWT with helical waveguide is capable of generating broad-bandwidth radiation and highly stable. In this paper, we derive the dispersion equation of helical waveguide and the non-linear theory for calculating the beam-wave interaction. Numerical stimulations basically accord with the experimental results. We design a W-band Gyro-TWT operating with a 80 keV, 5 A electron beam, producing an output power of 142 kW with 3 dB bandwidth 4.5%, central frequency 95 GHz, and saturation gain 52 dB. In the end, we calculate the effects of the changes of voltage, current and input power on the output performance of Gyro-TWT.
Grid multi-scroll chaotic circuit based on the second generation current conveyers
Authors: Zuo Ting  , Sun Ke-Hui  , Ai Xing-Xing  , Wang Hui-Hai  ,   School of Physics and Electronics, Central South University, Changsha 410083, China;,   School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

A three-dimensional grid multi-scroll chaotic system is presented by simplifying a generalized Jerk system. The analog circuit system is designed and realized by using positive-type second generation current conveyers. Compared with the chaotic circuit realized by traditional op amp, the chaotic circuit based on current conveyers can generate grid multi-scroll attractors at high frequency, and also has the advantages of simple circuit structure, and few components. Finally, the grid multi-scroll chaotic attractor are observed through using an oscilloscope, and the physical realizability of chaotic circuit is verified by circuit experiment. The results of circuit experiments and numerical simulations are accordant.
Complex wave solutions and localized excitations of (2+1)-dimensional korteweg-de Vries system
Authors: Zhang Wen-Ling  , Ma Song-Hua  , Chen Jing-Jing  ,   College of Science, Lishui University, Lishui 323000, China
Published: December 2020

With the help of the symbolic computation system Maple and Riccati equation (ξ’=a0+a1ξ+a2ξ2) expansion method and a variable separation method, some complex wave solutions with q=C1x+C2y+C3t+R(x,y,t) of the (2+1)-dimensional Korteweg-de Vries system is derived. Based on the derived solitary wave solution, some novel complex wave localized excitations such as complex wave fusion and complex wave annihilation are investigated.
A cellular automata model of pedestrian evacuation in three-dimensional space
Authors: Hu Jun  , You Lei  ,   School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China;,   School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611130, China
Published: December 2020

In order to effectively depict the evacuation process in three-dimensional space, combining with the ladder factors, a novel three-dimensional cellular automata model is proposed. Based on the position attraction and collision possibility, the model presents a formula for calculating the transition probability, and expounds the evacuation strategy through defining the cellular evolutionary process. Meanwhile, experiments are conducted using the simulation platform to study the relationships between evacuation time, exit flow rate, exit width, original pedestrian density and system average velocity. The results show that evacuation time and exit flow rate have a positive correlation with original pedestrian density, and a negative correlation with exit width; in addition, concerning the optimum evacuation time, there exists a desirable threshold value for system average velocity and exit width.
Potential energy curves and spectroscopic properties of SnO (X1Σ+, a3Π and A1Π) molecule
Authors: Huang Duo-Hui  , Wang Fan-Hou  , Yang Jun-Sheng  , Wan Ming-Jie  , Cao Qi-Long  , Yang Ming-Chao  ,   Key Laboratory of Computational Physics of Sichuan Province, Yibin University, Yibin 644000, China
Published: December 2020

Potential energy curves (PECs) for the ground state and the second excited state (a3Π and A1Π) of SnO molecule are calculated by using the multi-reference configuration interaction method (MRCI) and also considering Davidson correction’ multi-reference configuration interaction method with aug-cc-pvTZ basis for O atom, aug-cc-pvTZ-PP basis for Sn atom, respectively. On the basis of the PECs, the Re, ωe, ωeχe, Be, Te and De are obtained. The symmetries and dissociation limits for these electronic states are determined by group theory. The results show that three electronic states are dissociated along the same channel, Sn (3P)+O (3P). And then the PECs are fitted by using level program. The spectroscopic constants are determined according to fitted results, which shows that MRCI results are in good agreement with the experimental values. By solving the radial Schrödinger equation of nuclear motion, the vibration levels can be obtained, molecular constant (Bv and Dv) are reported for the first time at J=0.
Study of dielectronic recombination and resonance transfer and excitation with X-ray emission for Fe24++H2 collision
Authors: Mu Zhi-Dong  , Wei Qi-Ying  ,   School of Science, China University of Mining Science and Technology, Xuzhou 221008, China
Published: December 2020

Based on the theory of Hartree-Fock with relativistic correction, the theoretical study is carried out on the resonance strength of dielectronic recombination (DR) of the resonance double-excited states (i.e., KLL, KLM, KLN, KLO, KLP) of Fe24+. The resonance strength and colliding cross section of KLL are investigated. By using the experimental results of Compton profiles for H2, the resonance transfer and excitation with X-ray emission cross sections during collision between Fe24+ and target molecule H2 in an energy range of 300-800 MeV are studied. Our results are compared with the recent experimental and theoretical studies. It is found that for the double-excited states of Fe24+, the Kα decay tunnel is the major decay tunnel, and the wavelengths of X-ray in this process range from 1.850 to 1.880 Å. For other decay tunnels, the wavelengths of decay wave range from 1.460 to 1.601 Å. There is no overlap between the wavelengths for two cases. Our results are in reasonable agreement with the experimental results within an estimated uncertainty.
Design of a novel elliptical complementary invisible cloak
Authors: Luo Xiao-Yang  , Liu Dao-Ya  , Yao Li-Fang  , Dong Jian-Feng  ,   College of Information Science and Engineering, Ningbo University, Ningbo 315211, China
Published: December 2020

A novel elliptical complementary invisible cloak is designed based on the transformation optics and the complementary media theory. The constitutive parameter tensor expressions have been obtained. The results of full-wave simulations by using finite-element software confirm the validity of the constitutive parameter tensor expressions. This invisible cloak can not only hide the objects inside the cloak, but also permit the electromagnetic wave penetrate into the cloak and communicate with the outside world.
Coherence properties of supercontinuum generated by a picosecond pulse in normal dispersion region of highly nonlinear fiber
Authors: Jia Nan  , Li Tang-Jun  , Sun Jian  , Zhong Kang-Ping  , Wang Mu-Guang  ,   Institute of Lightwave Technology, Key Laboratory of All Optical Network and Advanced Telecommunication Network, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

The coherence properties of the supercontinuum generated by a picosecond pulse in normal dispersion region of highly nonlinear fiber are numerically calculated and analyzed at different input noise powers by introducing the definition of the complex degree of mutual coherence. The results show that the coherence of the generated supercontinuum is affected by the noise ratio of the picosecond pulse. The coherence of the spectrum sidelobes generated by optical wave breaking is lower than that of the center part of the spectrum. The chirp of pulse and shape of pulse do not have an obvious effect on the coherence of the broaden spectrum. Low noise power input is required to obtain high coherent supercontinuum, and the pump power and waveshape should be optimized to obtain the wide bandwidth and high coherent supercontinuum.
A fast and more universal algorithm for an uncertain acoustic filed in shallow-water
Authors: Cheng Guang-Li  , Zhang Ming-Min  , Hu Jin-Hua  ,   College of Electronic Engineering, Navy University of Engineering, Wuhan 430033, China
Published: December 2020

Non-intrusive polynomial chaos expansion (NPCE) method is a fast algorithm with the best performances for an uncertain acoustic filed currently, in which the selection of collocation points is an important factor for the computational accuracy, and some special processing methods such as piecewise probabilistic collocation method, should be adopted when the outputs of acoustic field vary severely with uncertain ocean environmental parameters. A new fast algorithm for uncertain acoustic filed in shallow-water is proposed based on Kriging model. The theoretical description of the new algorithm is given, and numerical simulations are conducted to verify the performances of the proposed algorithm. The physical interpretations are given in detail. The results demonstrate that the proposed algorithm is more accurate than the NPCE method under the same conditions, and any special processing method does not need to be adopted when the outputs of acoustic field vary severely with the uncertain ocean environmental parameters. The weakness of NPCE method can be overcome by the proposed algorithm, which is that the computational cost increases with the stochastic polynomial expanding to a higher order for enhancing the computational accuracy. The selection of sample point of the proposed algorithm is simpler and easier than that of NPCE method, and the calculation errors can be given directly. Thus, the proposed algorithm is more universal than NPCE method.
Theoretical analysis of effects of viscosity, surface tension, and magnetic field on the bubble evolution of Rayleigh-Taylor instability
Authors: Li Yuan  , Luo Xi-Sheng  ,   Advanced Propulsion Laboratory, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

The evolution of bubble in Rayleigh-Taylor (RT) instability for non-ideal hydromagnetic fluid is investigated theoretically in this study. In a plane perpendicular to the magnetic field, the general governing equation describing the bubble evolution is derived by considering the influences of viscousity, surface tension and magnetic field. The numerical and asymptotic solutions of the bubble velocity in two-dimensional planar geometry are obtained under different conditions and the effects of fluid viscosity, surface tension and magnetic field on the bubble growth are then analyzed in detail. It is found that the bubble velocity is reduced by viscosity and surface tension, which indicates that viscosity and surface tension can suppress the RT instability. It is also observed that the influence of magnetic field on the RT instability is caused by its nonlinear part, and whether the RT instability can be suppressed or enhanced depends on the direction of the nonlinear part of magnetic field.