bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular dynamics simulation of the effect of incident energy on the growth of Au/Au (111) thin film
Authors: Yan Chao  , Huang Li-Li  , He Xing-Dao  ,   Key Laboratory of Nondestructive Testing of Ministry of Education, School of Measuring and Optical Engineering, Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

The low-energy bombardment on Au (111) surface by Au atoms is studied by molecular dynamics (MD) simulation. The atomic interaction potential of embedded atom method is used in the simulation. The incident-energy effects on the morphologies and the surface roughness values of the deposited films are observed and summarized. The incident energy (Ein) varies from 0.1 eV to 50 eV. The transition of incident energy dependence occurs when the energy value is about 25 eV. The incident energy of about 25 eV is the sputtering threshold of Au (111) substrate. When the incident energy is lower than 25 eV, no atoms can be implanted into the depth beyond the second layer and all atoms are in face-centered cubic (111) arrangement without dislocation. The surface roughness decreases with the increase of the incident energy. For the case of Ein≥25 eV, the deposited atoms reach the third layer. When the number of atoms deposited in a substrate layer reaches about half the total number of atoms in this layer, the deposited atoms could go throgh this laer and enter into a deeper layer in the substrate. Surface roughness increases with the increase of the incident energy, and the energetic deposition can produce defects in both substrate and film.
Surface absorptions of H2S, HS and S on Fe(111) investigated by density functional theory
Authors: Zhang Feng-Chun  , Li Chun-Fu  , Zhang Cong-Lei  , Ran Zeng-Ling  ,   State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China;,   Key Laboratory of Optical Fiber Sensing and Communication of the Ministry of Education, University of Electronics Science and Technology of China, Chengdu 611731, China
Published: December 2020

In this paper, the geometries and properties of H2S and its decomposition fragments adsorbed on Fe(111) surface are studied by means of the density functional theory based on generalized gradient approximation in wide ranges of coverage; the adsorption energy, work function, charge density difference, density of states, and charge population are calculated; the effect of coverage on surface adsorption is discussed; the adsorbability values of H2S, HS radical and S on Fe(111) are compared and analyzed. The results show that the force between absorbates and surface gradually weaken as the coverage increases, the interactions between the above-mentioned particles and Fe(111) are compared with each other: the magnitudes of their interactions are in the order of H2SxSy corrosion product films are easily formed, and the compactnesses of corrosion product films change with coverage variation. A study of the adsorbability values of various adsorbates in low index crystal plane indicates that the interactive force between adsorbates and Fe(111) surface is strongest, and that between the Fe(100) surface and Fe(110) is relatively weak, the difference in adsorption energy between them is not so much.
Exciton spin relaxation dynamics in CdTe quantum dots at room temperature
Authors: Zhu Meng-Long  , Dong Yu-Lan  , Zhong Hai-Zheng  , He Jun  ,   Hunan Key Laboratory for Super-Microstructure and Ultrafast Process, Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha 410083, China;,   School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

Size-dependent exciton spin relaxation dynamics in CdTe colloidal quantum dots is studied at room temperature with the cross-polarized heterodyne third-order nonlinear transient grating technique The CdTe exciton spin relaxation reveals a mono-exponential decay behavior with a time constant of 0.1-0.5 ps when the pump-probe photon energy is tuned to be in resonance with the lowest exciton absorption transition (1Se-1Sh). The exciton spin relaxation in quantum dot is mainly governed by the hole spin flip process and ascribed to the transitions between bright-dark exciton fine structure states, i.e. J= 1+2. This finding suggests that the exciton spin relaxation rate in CdTe quantum dot is inversely proportional to the fourth power of quantum dot size.
Simulation, design and fabrication of one-dimensional photonic crystal back reflector for silicon thin film solar cell
Authors: Chen Pei-Zhuan  , Hou Guo-Fu  , Suo Song  , Ni Jian  , Zhang Jian-Jun  , Zhang Xiao-Dan  , Zhao Ying  ,   Key Laboratory of Photo-Electronic Thin Film Devices and Technique of Tianjin, Key Laboratory of Photo-Electronic Information Science and Technology of Ministry of Education, Institute of Photo-Electronic Thin Film Devices and Technique, Nankai University, Tianjin 300071, China
Published: December 2020

A new type of high-performance back reflector based on one-dimensional photonic crystal (1D PC) is introduced in this paper. The 1D PC is designed by alternately depositing a-Si and a-SiOx layers. Firstly the influences of refractive index, layer-thickness and corresponding periodicity on the band-gap of 1D PC are simulated using the finite difference time domain method. Based on the simulation results 1D PCs with different bandgaps are experimentally deposited. Just by adjusting the a-Si layer thickness, the high-reflection bandgaps in ranges of 500-750 nm and 650-1100 nm are easily achieved. The reflectivity values of 96.4% and 99% in the above-mentioned bandgaps are obtained. Comparing with the cells without a back reflector, a relative enhancement of 18.3% and 15.2% can be achieved for the short circuit current densities of a-Si:H single-junction and a-Si:H/μc-Si:H tandem solar cells, respectively, by integrating the above optimized 1D PC in the back. Also the influences of incident angles of white light, TE waves and TM waves on the reflectivity of 1D PC are studied using a software to generate spectrophotometric and ellipsometric spectra of a thin film stack. It is found that the reflectivity of 1D PC in solar cell is less affected by the changes of incident angles from air.
Membrane-inspired quantum bee colony algorithm for multiobjective spectrum allocation
Authors: Gao Hong-Yuan  , Li Chen-Wan  ,   College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

In order to solve the problem of the multi-objective spectrum allocation on the joint optimization of maximal network utility and fairness of users in cognitive radio network, based on quantum bee colony theory and membrane computing, a novel multi-objective discrete combinatorial optimization algorithm, named membrane-inspired quantum bee optimization, is proposed. The global optimal solution of single objective can be searched in the elementary membranes, and Pareto front solutions which take account of network utility and fairness, can be obtained from skin membrane with the proposed method. The multi-objective optimization algorithm, which can solve both single objective and multi-objective optimization problems at the same time, is designed by the communication rules between membranes, the cooperative evolution of foraging behavior based on quantum state, and non-dominated sorting. Compared with classical color-sensitive graph coloring algorithm, genetic algorithm, quantum genetic algorithm, and particle swarm optimization under different objective functions, the proposed spectrum allocation method can search the global optimal solution of single objective as shown by the simulation results, and it is superior to classical spectrum allocation algorithms and existing intelligence spectrum allocation methods. The optimal Pareto front solutions of multi-objective spectrum allocation are also obtained.
The solitary traveling wave solution for a class of nonlinear evolution equations
Authors: Shi Lan-Fang  , Zhu Min  , Zhou Xian-Chun  , Wang Wei-Gang  , Mo Jia-Qi  ,   College of Mathematics and Statistics, Nanjing University of information Science and Technology, Nanjing 210044, China;,   Department of Mathematics Anhui Normal University, Wuhu 241003, China;,   College of Electronic and Information Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China;,   Jiangsu Technology and Engineering Center for Meteorological Sensor Network, Nanjing University of Information Science and Technology Nanjing 210044, China;,   Tongcheng Teaching Department Anqing Teacher's College, Tongcheng 231402, China
Published: December 2020

A class of nonlinear evolution equation is considered by taking a simple and valid technique. Using the method of undetermined functions, firstly we introduce the solitary traveling wave solutions to the corresponding non-disturbed equation. And then the solitary wave solutions to the nonlinear disturbed dispersive equation are obtained using the generalized variational iteration method.
Identification scheme based on quantum teleportation for wireless communication networks
Authors: Zhang Pei  , Zhou Xiao-Qing  , Li Zhi-Wei  ,   Department of Physics, Mechanical and Electrical Engineering, Jishou University, Jishou 416000, China
Published: December 2020

A concept of infrastructure quantum communication network is proposed, and an identification scheme for wireless communication networks is realized by combining classical certification and quantum teleportation.This identification scheme is discussed through the wireless LAN authentication and extended to the entire wireless communication network. In the wireless local area network, the information is transmitted between STA and AP who obtained the SK and EPR pair via quantum channel. Then AP will obtain the information through unitary transformation and calculate the fidelity with the original backup information, so as to determine whether the identification is successful or not.
Adaptive identification for hyperchaotic l system based on Weiner model
Authors: Zhao Yi-Bo  , Zhang Xiu-Zai  , Sun Xin-Yu  ,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science & Technology, Nanjing 210044, China
Published: December 2020

In order to be able to identify the hyper-chaotic l system with uncertain parameters effectively in real time, so that hyper-chaotic system control and synchronization tracking can be applied, this paper presents a system identification method for the hyper-chaotic system based on Wiener model. The linear part of the Wiener model consists of linear transversal filters, while the nonlinear part is represented approximately by piecewise linear filters. According to the minimum mean square error criterion, the filter parameter updated algorithm is derived, and the convergence condition is also obtained. Simulation results confirm the effectiveness of the adaptive filter for the identification of hyper-chaotic systems. The presented method not only overcomes the difficulty to identify a strongly nonlinear system only by adaptive linear filters, but also have a lower computational complexity compared with other non-linear adaptive filters.
A local least square support vector machine prediction algorithm of small scale network traffic based on correlation analysis
Authors: Tang Zhou-Jin  , Peng Tao  , Wang Wen-Bo  ,   School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

Real-time monitoring and forecasting technology for network traffic has played an important role in network management. Effective network traffic prediction could analyze and solve problems before overload occurs, which significantly improves network availability. In this paper, after the vulnerability of traditional nonlinear prediction method in forecasting modeling is analyzed, the relevant local (RL) forecast which is based on correlation analysis and the parameter optimization method based on pattern search (PS) is introduced. Using the correlation analysis, the optimal training subset is chosen from time-and distance-correlated training samples. On this basis, the prediction model is established by LSSVM. Finally network traffic dataset collected from wired campus networks is studied for our experiments. And the results show that the relevant local LSSVM prediction method whose training set and parameters have been automatically optimized can effectively predict the small scale traffic measurement data, and RL-LSSVM traffic forecasting algorithm exhibits significantly good prediction accuracy for the data set compared with previous algorithm.
Time delay estimation using Markov Chain Monte Carlo method
Authors: Li Jing  , Zhao Yong-Jun  , Li Dong-Hai  ,   The PLA Information Engineering University, Zhengzhou 450001, China
Published: December 2020

A novel maximum likelihood estimation model for time delay is constructed to estimate the passive time delay; the signal of emitter is unknown in this model. According to the model characteristics, the fast Fourier transformation (FFT) method is used to achieve time delay estimation (TDE). In order to improve the accuracy of estimator, the Markov Chain Monte Carlo (MCMC) sampling method is used to estimate the time delay value directly. Unlike traditional algorithms, MCMC method can obtain time delay without peak detection. Furthermore, the Cramer-Rao lower bound (CRLB) of this model is derived. Finally, simulations show that the proposed approach is suitable for both narrowband and broadband TDE, and the MCMC algorithm can achieve more precise time delay value with the same sample, and it has lower computational complexity than IS algorithm. The novel approach can estimate also the time delay of non-integer multiple of the sampling interval.
Microscopic characteristics mechanism of optical gas sensing material rutile titanium dioxide (110) surface adsorption of CO molecules
Authors: Zhu Hong-Qiang  , Feng Qing  ,   Chongqing Key Laboratory on Optoelectronic Functional Materials, Chongqing 401331, China;,   Key Laboratory of Optics and Engineering, Chongqing Normal University, Chongqing 400047, China
Published: December 2020

Using the optical gas sensing materials to adsorb gases can cause the changes of the optical properties of materials. This method can be used to measure the gas composition and is a hot topic of current research in the field of gas sensitive sensors. This paper studies the micro-characteristics of rutile TiO2 (110) surface adsorption of CO molecules. By using the first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory (DFT), the adsorption energy, electron density of states, optical properties and charge density of the surface are calculated. Results show that the TiO2 (110) surface terminating in two coordinated O atoms is the most stable surface, and the structure with C-terminal of CO molecules adsorbed on the surface is the most stable. The higher the oxygen vacancy concentration, the more helpful it is to the adsorption of surface CO molecules. This process is exothermic. When the oxygen vacancy concentration is 33%, the adsorption energy can reach 1.319 eV. After adsorption, the structure of the surface tends to be more stable. Oxygen vacancy oxidizing the CO molecule is the essence of the adsorption process, and the charge of a CO molecule is transferred to the material surface. The CO molecules adsorbed on TiO2 (110) surface containing oxygen vacancies can improve its optical properties in visible light range; moreover, the higher the concentration of oxygen vacancy, the more obvious the improvement of absorption, reflection ability and optical gas sensing performance.
Van der Waals interaction between high excited states
Authors: Zhao Jian-Dong  , Xin Jie  ,   College of Information and Communication Engineering, North University of China, Taiyuan 030051, China
Published: December 2020

The highly excited atoms have a strong Van der Waals interaction as compared with the ground-state atoms, which can block the excitation of neighboring atoms and forming the blockade effect. In this work, the interaction between highly excited atoms is calculated using the perturbation theory, the interaction of nS and nD pair states and the dispersion coefficients are obtained. This shows that the interactions of the SS for both Rb and Cs atoms are repulsive, whereas the interaction of DD states is repulsive for Cs and attractive for Rb.
Terahertz study of L-asparagine and its monohydrate
Authors: Yang Jing-Qi  , Li Shao-Xian  , Zhao Hong-Wei  , Zhang Jian-Bing  , Yang Na  , Jing Dan-Dan  , Wang Chen-Yang  , Han Jia-Guang  ,   Center for Terahertz waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, and the Key Laboratory of Optoelectronics Information and Technology (Ministry of Education), Tianjin 300072, China;,   Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Low-frequency collective vibrational modes of biomolecules which often lie in terahertz (THz) band, make the terahertz time-domain spectroscopy (THz-TDS) an important technique for molecular identification and medicine quality inspection. Distinctive THz spectra between L-asparagine and its monohydrate were observed and the dehydration process of L-asparagine monohydrate was tracked by THz-TDS. Experiments indicate that THz wave is sensitive to phase transitions in crystals, dehydration process, and weak molecular interactions. Multi-techniques including differential scanning calorimetry and thermogravimetry, Fourier transform infrared spectroscopy, and powder X-ray diffraction are performed to investigate the thermodynamic properties, intermolecular and intramolecular vibrations, and molecular packing patterns of L-asparagine and its monohydrate. These measurements support the reliability of THz spectroscopy. To simulate and analyse the vibration modes of L-asparagine monohydrate, density functional theory calculations are performed using a Perdew Burke and Ernzerhof generalized gradient approach; the results agree well with the experimental observations.
Mechanism of original damage of thin optical components induced by surface particle contamination
Authors: Sun Xiao-Yan  , Lei Ze-Min  , Lu Xing-Qiang  , Fan Dian-Yuan  ,   National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   School of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on the optical transmission theory, the reason why front-surface particle contamination may induce the original damage of thin optical components is considered, and a damage mechanism is put forward: The localized thermal deformation of an optical element induced by the thermal effect of particle contamination together with the shading effect of it can disturb the laser beams. Simulated results show that for a high power laser, the localized thermal deformation of thin optical components, which disturbs the laser beam, is an important cause to produce strong light intensity modulations. The surface shape, phase delay, and thermal diffusion length of a localized thermal deformation are constantly changing with the increase of laser pulse shot number, so the highest light intensity modulation will be produced at different positions in the thickness direction or the xy direction on the rear-surface of an optical element. This not only can easily induce some damages on the rear-surface of the optical element, but also cause the interior damages scattered in the thickness direction.
Study of electromagnetic scattering from two-dimensional rough sea surface based on improved Wen’s spectrum
Authors: Wu Geng-Kun  , Ji Guang-Rong  , Ji Ting-Ting  , Ren Hong-Xia  ,   School of science, Ocean University of China, QingDao 266100, China
Published: December 2020

By combining the improved Wen's spectrum with the classic Monte Carlo algorithm and Donelan's experimental conclusion, a two-dimensional sea surface model suitable for different depths and different stages of wave growth is proposed in this paper. Based on the classic two-scale method for the calculation of sea backscattering coefficient, and the introduction of the simulation results obtained by the SSA (small slope approximation) method, the electromagnetic scattering calculation method is modified. Compared with the fitting result based on the backscattering coefficient model of GIT, it proves that the improved Wen's spectrum is suitable for Chinese coastal waves, and the proposed electromagnetic scattering theory is accurate and efficient.
Semi-empirical analytical mode with highorder parameter of the biological tissue optical diffuse reflectance
Authors: Gao Zhen  , Ma Zhao  , Liu Ying  , Han Mei-Mei  , Wang Rui  ,   College of Science, Key Laboratory of Opto-electronics Information Technical Science, EMC Tianjin University, Tianjin 300072, China;,   College of Sciences, Shihezi University, Shihezi 832003, China
Published: December 2020

Optical diffuse spectroscopy is crucial in non-invasive measurements and quick analysis of biological tissues. However, the lack of exact analytical solution limits its application. In this paper, a semi-empirical formula for diffuse reflectance is elaborated on the basis of the photon migration theory and the second-order similarity relation, and the influence of second-order parameter γ on the semi-empirical formula is studied by use of Monte Carlo method. Results show that the diffuse reflectance changes with γ nonlinearly when a small aperture detector is used to collected diffuse light. Finally, the proposed semi-empirical formula is mathematically simple compared with the other theoretical mode used at present, and offers a new theoretical and technical support in the measurement of the tissue optical parameters and the application of diffuse reflectance spectroscopy.
Nonlinear acoustical response of multibubbles in elastic tube
Authors: Wang Cheng-Hui  , Cheng Jian-Chun  ,   Key Ultrasonic Laboratory of Shaanxi Provice, Shaanxi Normal University, Xi'an 710062, China;,   Institute of Acoustics, Nanjing University, Nanjing 210093, China
Published: December 2020

Based on the hypothesis that the wall of an elastic tube can be described as a membrane-type elastic structure, the coupled oscillation in a system of bubble clusters and local position of the elastic wall is explored, and the model of the nonlinear oscillation of bubbles is developed. According to the successive approximation method, the nonlinear resonance frequencies the and forced oscillation are analyzed theoretically. Results indicate that the resonance frequency of bubbles is mainly affected by the interaction of bubbles in clusters. Furthermore, there is a maximum frequency of ultrasound that will excite vibrations of the bubbles in clusters, and the response of multi-valued amplitudes exists in the region of high frequency.
Acoustic absorption mechanism and optimization of a rubber slab with cylindrical cavities
Authors: Zhao Hong-Gang  , Wen Ji-Hong  , Yang Hai-Bin  , Lü Lin-Mei  , Wen Xi-Sen  ,   Vibration and Acoustics Research Group, Science and Technology on Integrated Logistics Support Laboratory, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The finite element method is introduced to investigate the absorption of a rubber slab (20 mm thick) with one layer of cylindrical cavities. It has a lower frequency absorption peak than that with spherical cavity in the same size, which is determined by the monopole resonance of cavities. Analysis of partial wave scattering verifies that the absorption peak is induced by the monopole resonance. Power dissipation density and displacement pattern of one unit cell is used to clarify intuitively the absorption mechanism of the cavity. Then the effect of damping of transverse modulus on the absorption is investigated under the condition of a steel backing. Both the physical and structural parameters of the rubber slab are optimized by a genetic algorithm for favorable absorption from 1.5 to 10 kHz.
Velocity fluctuation and self diffusion character in a dense granular sheared flow studied by discrete element method
Authors: Meng Fan-Jing  , Liu Kun  ,   Institute of Tribology, Hefei University of Technology, Hefei 230009, China
Published: December 2020

The distribution of average velocities, fluctuation of velocities, regional definition, and granular self-diffusion characters in dense granular flows between sheared parallel plates are discussed. In order to study the above problems, we use computer-established discrete element model with an average solid fraction of 0.80. Theoretical results show that the average velocities decrease with increasing height, and are larger for the case of lower plate with greater velocity; the average velocities in y direction are close to 0 because there is no bulk motion in y direction. Flows of the lower plate with a greater velocity induce relatively greater fluctuation of velocities in the x and y directions, the fluctuation of velocities increases with the height and is larger in the area close to the upper plate. The flows consist of a “solid-like” area in the lower test region, but a “fluid-like” region in the upper, and an “oscillating” region in the middle of the channel. By tracking the movements of granules continually, variations of the mean-square self-diffusion relative displacements with square time are plotted, and the mean self-diffusion relative coefficients are determined. As the fluctuation and self-diffusion analysis directly reflect the macroscopic properties of granules and provide bases and references for researching the flow mechanisms of “dense granular sheared flows”.
Fine structures and the unsteadiness characteristics of supersonic flow over backward facing step via NPLS
Authors: Zhu Yang-Zhu  , Yi Shi-He  , Kong Xiao-Ping  , Quan Peng-Cheng  , Chen Zhi  , Tian Li-Feng  ,   College of Aerospace Science and Engineering, National University of Defense Technology Changsha 410073, China;,   Air Defense Forces Academy, Zhengzhou 450052, China
Published: December 2020

In a low-noise supersonic wind tunnel at a Mach number 3.4, visualization of flow structure around backward facing step (BFS) with a 3 mm high step is carried out via schlieren and nano-tracer-based planar laser scattering (NPLS) respectively. The time-averaged flow characteristic of the reattachment region and the rich instantaneous structures of the redeveloping boundary layer are both revealed. By contrasting the NPLS images at different times, the unsteady evolvement characteristic of the coherent vortices in the redeveloping boundary layer is discussed. And the results are compared with the schlieren of Mach 4.2 and the prior data published. Results indicate that with either of the two flow visualization ways, the shock waves and the expansion waves can be captured; however, the NPLS technique has the obvious advantages to reveal the instantaneous structures on a small scale in a certain section plane with a time resolution of 6 ns and spatial resolution about micron magnitude; under the flow condition in this contribution, the growth rate of redeveloping boundary layer is 0.07519; the characteristic time is around 10 μs of the hairpin vortex shedding. At the same expansion rate, the reattachment occurs later with increasing Mach numbers, while if the expansion rate increases, the reattachment occurs earlier, and the flow turn angle is larger.
Study on the effect of X-ray diffractometer inherent angle scale error on the precision of lattice parameter calculation
Authors: Xu Xiao-Ming  , Miao Wei  , Tao Kun  ,   Center for Testing and Analyzing of Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

This paper studies the effect of measuring angle error in X-ray powder diffractometer, which is caused by diffractometer inherent angle scale error resulting from mechanical manufacture, on the precision of calculated lattice parameter. It represents the theoretical limit of the consistency of the lattice parameters obtained by different diffractometers and laboratories. We use the calculated polysilicon diffraction patterns with random angle error to simulate the results measured by many sets of diffractometers of some manufacturing precision, then calculate and analyze the lattice parameters by three methods.
Effective potential model for the electrostatic correlation in charged fluids
Authors: Kang Yan-Shuang  , Sun Zong-Li  ,   College of Science, Agriculture University of Hebei, Baoding 071001, China;,   Science and Technology College, North China Electric Power University, Baoding 071051, China
Published: December 2020

Based on the Nordholm's concept of Coulomb repulsive hole for plasma, a model of effective Coulomb potential is proposed to describe the charged fluids. Employing the classical density functional theory, the equilibrium structures of charged fluids confined in nano-cavities are calculated. Through the comparison with the numerical results, the effect of Coulomb correlation on the structure and excess adsorption is studied. In addition, the influence of Coulomb correlation on the structure is also calculated and studied under the condition of larger confinement. It is shown that the effective pair potential proposed here can be successfully used to predict the effects of Coulomb correlation on the structure and other physical chemical properties. Results obtained can provide some useful clues to the understanding of the correlation in other complex model potential system.
Effect of single nanoparticle on the polymer crystallization behavior
Authors: Duan Fang-Li  , Wang Yuan  ,   State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400030, China
Published: December 2020

Molecular dynamics simulation with a coarse grain model is performed to study the influence of single nanoparticle on the polymer crystallization behavior. By changing the mode of action of the polymer-nanoparticle (i.e. attraction or repulsion), the strength of the polymer-nanoparticle interactions, as well as the chain length of the polymer molecular, and by calculating the bond order parameter to characterize the influence in the cooling process, different effects of single nanoparticle on the polymer crystallization behavior are studied. This study has shown that the nanoparticle has no obvious effect on the whole polymer system composed of single nanoparticles. However, nanoparticles can promote the degree of order of polymer chains in crystallization process and enhance partially the polymer crystallization. Under the attraction and strong strength of the polymer-nanoparticle interaction, it is found that obviously the nanoparticle enhances the polymer crystallization partially. Furthermore, the chain length of the polymer molecular also shows some effect on the crystallization and the long-chain sample has a better enhancement for the polymer crystallization than the short-chain one under a strong attraction strength.
Thermal conductivity measurement on GeSbSe glasses：Raman scattering spectra method
Authors: Gan Yu-Lin  , Wang Li  , Su Xue-Qiong  , Xu Si-Wei  , Kong Le  , Shen Xiang  ,   College of Applied Sciences, Beijing University of technology, Beijing 100124, China;,   College of Information Science and Engineering, Ningbo University, Ningbo 315211, China
Published: December 2020

We have measured the temperature raised by laser irradiation on the basis of difference between Stokes and anti-Stokes Raman scattering cross-sections, and further estimated the thermal conductivity of the material. GeSbSe glasses with compositions of GexSb10Se90-x, GexSb15Se85-x, and GexSb20Se80-x are systematically studied with the aim of verifying the practicability of the new method and understanding the role of chemical composition in determining the structure and thermal conductivity of the glasses. All of the results are in agreement with those reported on thermal conductivity measured by different methods in the literature. It is indicated that Raman scattering method is convenient and efficient to measure thermal conductivity of the materials. For each group of glasses, it is found that the thermal conductivity increases with increasing Ge concentration up to a transition point corresponding to the glass with chemically stoichiometric composition. We ascribe the threshold behaviour of the thermal conductivity to the demixing of the structural units from glass network.
Influence of high dose As ion implantation on electrical properties of high resistivity silicon
Authors: Zhu He  , Zhang Bing-Po  , Wang Miao  , Hu Gu-Jin  , Dai Ning  , Wu Hui-Zhen  ,   Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China;,   Shanghai Institute of Technical Physics, Chinese Academy of Sciences, State Key Laboratory of Infrared Physics, Shanghai 200083, China
Published: December 2020

To achieve nanoscale infrared photodetector electrodes with low resistivity, ion-implantation is used to implant high dose of As ion into high-resistivity silicon, and followed by rapid thermal annealing (RTA). A 200 nm thick Si:As layer with resistivity of 10-4 Ω · cm is obtained. Characterization by atomic force microscopy shows that the surfaces of the ion-implanted samples are smooth with a root-mean-square (RMS) coarseness of 0.5 nm. Although introduction of As ions destroys the lattice structure of crystalline silicon and causes a plenty of defects, proper annealing can restore the crystal lattice, as evidenced by the HRTEM observation of the annealed sample prepared by using focused ion beam (FIB) technology. Besides, the measurements of hall effect and spreading resistance indicate that the Si:As layer has good electrical properties including high carrier concentrations 2.5 × 1020 cm-3, high electron mobilities 40 cm2/V · s, and high electrical conductivities. The low resistivity Si:As material obtained is suitable to be used as the back electrodes of silicon-based optoelectronic devices.
Structure and optical absorption of nc-Si：H/α-SiC：H multilayers
Authors: Ma Lei  , Jiang Bing  , Chen Yi-Hao  , Shen Bo  , Peng Ying-Cai  ,   College of Electronic and Informational Engineering, Hebei University, Baoding 071002, China;,   State Key Laboratory for Artificial Microstructure and Mesoscope Physics, Beijing University, Beijing 100871, China
Published: December 2020

Nanocrystalline silicon nc-Si:H/SiC:H multilayers were fabricated by thermal annealing of the hydrogenated amorphous Si α-Si:H/hydrogenated amorphous silicon carbide α-SiC:H stacked structures prepared by plasma enhanced chemical vapor deposition (PECVD) system at 900–1000℃. The microstructures of annealed samples were investigated by Raman scattering, cross-section transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. Results demonstrate that the size of Si grains formed can be controlled by the α-Si:H layer thickness and annealing temperature. Optical absorption measurements show that the optical bandgap of the multilayered structures increases and the absorption coefficient decreases with diminishing Si grain size. However, the absorption coefficient and the optical bandgap of the multilayers are not influenced by the α-SiC:H layer thickness when the size of Si grains is kept constant.
Finite-difference time domain method for the analysis of radar scattering characteristic of metal target coated with anisotropic ferrite
Authors: Liu Jian-Xiao  , Zhang Jun-Liang  , Su Ming-Min  ,   School of Electronics and Information Engineering, Hengshui University, Hengshui 053000, China
Published: December 2020

A metal cylinder coated with anisotropic ferrite material is analyzed using the finite-difference time-domain method (FDTD) in this paper, and the bistatic radar cross-section (RCS) is obtained. The new method of electromagnetic scattering by magnetized ferrite medium is analyzed in detail based on the FDTD. To exemplify the availability of the algorithm, bistatic RCS of a magnetized ferrite cylinder is computed, and the numerical results are the same as the shift operator FDTD (SO-FDTD), which shows that the proposed FDTD method is correct and efficient.
Effects of controlled surface states on the photoluminescence emission of GaN film
Authors: Zhou Nan  , Zheng Qiang  , Hu Bei-Chen  , Shi De-Quan  , Miao Chun-Yu  , Ma Chun-Yu  , Liang Hong-Wei  , Hao Sheng-Zhi  , Zhang Qing-Yu  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Opto-electronic Technology, Dalian University of Technology, Dalian 116024, China
Published: December 2020

Hot phosphor acid (H3 PO4) etching and/or SiOxNy surface passivation are used to change the surface states of high-resistance intrinsic GaN films. The films are investigated to reveal the influence of controlled surface states on photoluminescence (PL) emission. It is found that H3 PO4 etching cannot improve the ultraviolet (UV) PL emission obviously, but the PL spectrum in the range of visible light is considerably enhanced. After passivation with SiOxNy film, the quantum efficiency of UV PL is increased by a factor of 12-13. Meanwhile, the visible PL is significantly enhanced. By analyzing the PL spectra of the etched and passivated samples obtained at room temperature and low temperatures, we discuss the role of surface states in PL emission in the range of UV, blue and yellow bands, and the related physical mechanisms.
Wideband and large incident angle wave transparent material based on frequency selective surface with miniaturized elements
Authors: Wang Cong-Yi  , Xu Cheng  , Wu Rui-Xin  ,   School of Electronic Science & Engineering, Nanjing University, Nanjing 210093, China
Published: December 2020

Different from the traditional frequency selective surface, the working frequency of a frequency selective surface with miniaturized elements (mFSS) is based on the intrinsic capacitance and inductance of its unit cell, but not the structure resonance. Focusing on the application of mFSS in wave transparent material (WTM), we have designed a band-pass WTM with unit cell of metal patch and wire, analyzed their intrinsic capacitance and inductance, and explored the parameters of the mFSS unit and its equivalent circuit on the performances of WTM. A bandpass WTM sample working at 10 GHz is designed and fabricated. Measurements demonstrate that the sample is wideband, insensitive to the incident angle, and polarization independent; the -1 dB bandwidth is over 40% at normal incidence and up to 20% even at large incident angles 60°. Experimental results are in good agreements with the calculations. The advantages of mFSS based WTM can expand its applications in microwave engineering, especially the radomes.
Study on electrical performance of metal copper films deposited by magnetron sputtering on polyimide flexible substrates
Authors: Peng Jin  , Chen Guang-Qi  , Song Yi-Chi  , Gu Kun-Ming  , Tang Jiao-Ning  ,   Shenzhen Engineering Laboratory for Advanced Technology of Ceramics, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China;,   Aeronautical Engineering, Imperial College London, London SW75EL, England
Published: December 2020

For preparing flexible copper clad laminate, copper films are deposited by magnetron sputtering on polyimide substrates. During the experiment, the prepared copper films show good conductivity while changing the technological parameter like preparation temperature, substrate bias, preparation time, and so on. The composition, structure, and surface morphology of the thin film are investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The stylus profilometer and four-point probe resistance measuring instrument are used to examine the thickness and resistance of the thin films, and the resistivity of the film is calculated. Finally, the optimum processing conditions for the copper films are obtained according to the standard of industrial application: the preparation temperature is 100℃, the DC substrate bias is 50 V, with no pulsed substrate bias.
Study on the optimal design of frequency selective surfaces based on the discrete particle swarm optimization
Authors: Xu Nian-Xi  , Gao Jin-Song  , Feng Xiao-Guo  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

The requirements of frequency-selective surface (FSS) between high transparency in pass band and high reflectance in stop band are contradictory, when they have loaded medium on one side and receive a large range of illumination. In order to solve the contradiction, this paper employs a discrete particle swarm optimization approach (hereafter referred to as a DPSO). In order to seek a balanced FSS with high transparency in pass band and high reflectance in stop band, the periodic intervals and geometrical dimensions of FSS-structures are optimized and designed by using the DPSO method. Simulation and test results indicate that the FSS of super dense Y loop elements in a half-loaded medium structure is presented in this paper: the transparency in pass band and stop band are 80% and 30% respectively. The DPSO method will offer an excellent FSS for the radome which receives a large range of illumination, and on the other hand, it provides a theoretical guidance for the requirements of FSS between high transparency in pass band and high reflectance in stop band.
A simple model for probabilistic interval forecasts of wind power chaotic time series
Authors: Zhang Guo-Yong  , Wu Yong-Gang  , Zhang Yang  , Dai Xian-Liang  ,   College of Hydroelectricity and Digitalization Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;,   School of Electrical, electronic and computer engineering, University of Western Australia, WA 6009, Australia
Published: December 2020

Integration of wind power into grids requires accurate forecasting, however, traditional wind power point forecast errors are unavoidable and they cannot be eliminated due to the highly volatile and uncertain in the chaotic time series of wind power. Unlike point prediction, which conveys no information about the prediction accuracy, probabilistic interval forecasts can provide a range, within which the target will lie with a certain probability, for estimating the potential impacts and risks facing the system operation. Most existing prediction interval (PI) construction methods are often placed after a deterministic forecasting model with or without prior assumptions, this paper propose a novel lower-upper bound estimation approach using extreme learning machine to directly construct PIs for wind power series. Based on the analysis of the interval forecasting error information in training dataset, a new problem formulation is developed in this method to get better PIs. In addition, in order to obtain the global optimal solution of the above model, a quantum bacterial foraging optimization algorithm is proposed by introducing the theory of quantum mechanics into bacteria foraging behavior. The testing results from two real wind farms with different confidence probability and optimization criterion demonstrate the excellent quality of PIs in terms of both reliability and sharpness, which provide a support for the steady operation of power system with wind power integration.
Predictive controller for networked multi-agent systems with communication delay and packet loss
Authors: An Bao-Ran  , Liu Guo-Ping  ,   School of Astronautics, Harbin Institute of Technology, Harbin 150080, China;,   School of Engineering, University of South Wales, Pontypridd CF37 1DL, U.K.
Published: December 2020

Communication delay and packet loss highly degrade the control performances of networked multi-agent systems (NMAS). This paper addresses the problem by presenting a novel predictive control technique using a time-delay and packet-loss compensation scheme. The principle of the time-delay and packet-loss compensation scheme is employed to remove the effects of network delay and packet loss. Furthermore, another key part of this paper is to analyse the stability and consensusability of close-loop NMAS on the basis of the designed predictive controller. Finally, simulation results illustrate the efficacy of the proposed method.
Second-order Stokes wave solutions for gravity capillary water waves in three-layer dendity-stratified fluid
Authors: Cui Wei  , Yan Zai-Zai  , Mu Ren  ,   College of Science, Inner Mongolia University of Technology, Hohhot 010051, China;,   Management College, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

In this paper, gravity-capillary water waves in a three-layer stratified fluid are investigated by using a perturbation method, and the second-order asymptotic solutions of the velocity potentials and the second-order Stokes solutions of the associated elevations of the gravity-capillary water waves are presented based on the small amplitude wave theory. As expected, both the first-order and second-order solutions derived depend on not only the depth and density of the three-layer fluid but also the surface tension.
Optimization of the projected entangled pair state algorithm for quantum systems
Authors: Li Sheng-Hao  , Wu Xiao-Bing  , Huang Chong-Fu  , Wang Hong-Lei  ,   Chongqing Institute of Engineering, Chongqing 400037, China;,   Faculty of Basic Medical Science, Chongqing Medical University, Chongqing 400016, China
Published: December 2020

In the numerical calculation, the projected entangled pair state (PEPS) algorithm is the most important tensor network algorithm for two-dimensional strongly correlated electron quantum lattice system. In this paper, the optimization of PEPS for two-dimensional quantum system is discussed. An optimization connection between how to update the PEPS tensor and how to calculate the physical observable is investigated, for the tensor network algorithm based on the PEPS representation, which can greatly improve the utilization of computing resources. In this case, optimized PEPS algorithm, as a powerful tool, can be used to study quantum phase transitions and quantum critical phenomena in the thermodynamic limit of the two-dimensional strongly correlated electron quantum lattice system. Of course, optimization of PEPS algorithm program has many other applications, such as adding U(1) and SO(2) symmetry in PEPS algorithm, etc.
Chimera states in a globally coupled discontinuous map lattices
Authors: Cheng Xing-Chao  , Yang Ke-Li  , Qu Shi-Xian  ,   Institute of Theoretical and Computational Physics, School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China;,   Institute of Nonlinear research, Department of Physics and Information Technology, Baoji University of Arts and Sciences, Baoji 721016, China
Published: December 2020

The chimera states and cluster chimera states in a globally coupled both discontinuous-and-non-invertible-map lattices are studied using the order parameters and spatial-time-amplitude patterns. The result show that chimera states and cluster chimera states are sensitive depends on the choice of the coupling strength, and they are induced by the interaction between the discontinuity and the non-invertibility in coupled system. We also discuss the conditions for the chimera states existing in this system.