bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular dynamics simulations of shock initiation of hexanitrohexaazaisowurtzitane/trinitrotoluene cocrystal
Authors: Liu Hai  , Li Qi-Kai  , He Yuan-Hang  ,   State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China;,   School of Materials Science and Engineering, Tsinghua University, Beijing 100086, China
Published: December 2020

Multiscale shock technique (MSST) has been shown to accurately reproduce the thermodynamic and chemical reaction paths throughout the shock wave fronts and reaction zone of shock initiation of energetic materials. A 1:1 cocrystal of hexanitrohexaazaisowurtzitane/trinitrotoluene (CL20/TNT) is shocked along the 110 orientations under the conditions of shock velocities lying in the range 610 kms-1 in ReaxFF molecular dynamics simulations. Products recognition analysis leads to reactions occurring with shock velocities of 7 kms-1 or stronger, and the shock initiation pressure is 24.56 GPa obtained from the conservation of Rankine-Hugoniot relation. Comparisons of the relationships are carried out between shock velocity and particle velocity, shock velocities and elastic-plastic transition. During shock initiation with the shock velocities lying in the range 78 kms-1, the shocked systems correspond to an elastic-plastic deformation, primary chemical reactions, and secondary chemical reactions. And the elastic-plastic transition coincides with the chemical reaction at higher shock velocity (9 kms-1), the cocrystal material response is over-driven, and all the thermodynamic properties show steep gradients, the compressed material by the shock wave steps into the plastic region, and a large number of carbon atoms appear in the early stage of over-driven shock initiation.
A method of adaptive pulse width modulation for multiple-valued data transmission
Authors: Sun Hua-Juan  , Yan Xiao-Hong  , Hao Xue-Yuan  ,   College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

The non-ideal characteristics such as dielectric loss and skin effect of coaxial cables etc can cause attenuation of the high-frequency component of the signals, making it difficult for the receiver to interpret the signal, thereby greatly reducing the data rate. Pulse width modulation (PWM) pre-emphasis technique, which has been very good to use in the binary signal, utilizes time-domain information processing to increase the data rate. We introduce the new adaptive PWM pre-emphasis method to further eliminate the data-dependent jitter, which can dynamically compensate for the transmission loss of multiple-valued data with strong or weak pre-emphasis. The results of eye diagrams show that this method can improve the quality of signal transmission.
Terahertz scattering property for the coated object of rough surface
Authors: Jiang Yue-Song  , Nie Meng-Yao  , Zhang Chong-Hui  , Xin Can-Wei  , Hua Hou-Qiang  ,   School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
Published: December 2020

The scattering of the radar signal by the coated target of a rough surface in the terahertz wave is studied. Considering the roughness of the surface, reflection coefficient is modified for the rough surface. The modified equivalent current can be obtained by using the reflection coefficient. Then using the modified equivalent current and the physical optics solution, the radar cross section of the coated object with the rough surface is obtained. And combining the graphical electromagnetic computing method, simulations to validate the formulation are performed. Numerical results for several coated bodies such as cylinder and cone-sphere geometry are given and discussed from different angles of incidence, different frequencies, different materials, different roughness values, and different coating thickness values.
Double cross-shape broadband low-loss and small units left-handed metamaterials based design and experimental verification
Authors: Dong Huai-Jing  , Geng You-Lin  ,   Institue of Antenna and Microwaves, Hangzhou Dianzi University, Hangzhou 310018, China
Published: December 2020

A method of designing a single side left-handed structure based on the integration of electric resonator and magnetic resonator is proposed in this paper. The left-handed units are composed of two cross types of metal mirrors that are parallel-placed on the same side of the substrate and then arranged into a periodic structure. The results of HFSS software simulation and a series of effective electromagnetic parameters extraction show that the left-handed structure exhibits negative effective permittivity and permeability simultaneously in a frequency range from 9.4 GHz to 16 GHz. Its relative passband reaches 52%, and the unit electrical length and loss are less than those of the same type of structures. The periodic structure is fabricated and tested using the waveguide method. The fine left-handed feature is proved again. This new structure lays a foundation for the wide applications of left-handed metamaterials.
Design and study of Fresnel lens for an antenna in indoor visible light communication system
Authors: Li Xiang  , Lan Tian  , Wang Yun  , Wang Long-Hui  ,   School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

Indoor visible light communication is a novel wireless communication based on white LED technology. For its application needs, equal-pitch flat Fresnel lens is designed. Compared with traditional lens, Fresnel lens has several advantages including strong focus ability, short focal length, thin thickness, light weight, low cost, etc. The optical concentration ratio, the optical efficiency and the spot size of these Fresnel lenses are analyzed respectively with different parameters by means of Trace pro. Furthermore, the concentration performance is discussed at different incident angles. The results indicate that this kind of Fresnel lens could be used as an antenna of high-gain and small field, and the optical efficiency could be obtained to be 92.1%.
Fingerprint data extraction from Chinese herbal medicines with terahertz spectrum based on second-order harmonic oscillator model
Authors: Zhao Feng  , Long Shu-Ming  , Zhang Yuan-Yuan  , Wang Xin-Ke  , Ye Jia-Sheng  , Zhang Yan  ,   School of Physics and Telecommunication Engineering, Shaanxi University of Technology, Hanzhong 723000, China;,   Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

Terahertz time-domain spectroscopy provides a new method of identifying and studying Chinese herbal medicines. We utilize a second-order terahertz filter to describe the samples of Chinese herbal medicines, and the behaviors of terahertz filter are characterized by a second-order differential equations with three parameters {α, β, γ} or the corresponding frequency domain system function H(f). The results of data analysis show that five kinds of Chinese herbal medicines which are used in the experiments have unique filter parameters. Thus, if these filter parameters are used as the fingerprint data of Chinese herbal medicines, we can effectively determine the types and origins of Chinese herbal medicines.
Multiple polarization switching in mutually coupled vertical-cavity surface emitting lasers
Authors: Zhou Zhen-Li  , Xia Guang-Qiong  , Deng Tao  , Zhao Mao-Rong  , Wu Zheng-Mao  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

Based on the spin-flip model, the characteristics of multiple polarization switching (PS) in mutually-coupled vertical-cavity surface emitting laser (VCSEL) are investigated by continuously changing some important parameters. The simulated results show that multiple PS can be generated through continuously varying the mutually-coupled strength, the oscillation frequency of one VCSEL or the oscillation frequencies of two VCSELs. The characteristics of multiple PS under the above three scenarios are analyzed, and the influence of the delay-coupled time on the performance of multiple PS is also discussed.
F-state based permanent optical data storage in bacteriorhodopsin film
Authors: Yu Xiang-Hua  , Yao Bao-Li  , Li Xin-Yu  , Liu Shi-Lei  , Lei Ming  , Li Run-Ze  , Liang Yan-Sheng  , Zhou Xing  , Wu Di  , Dan Dan  , Min Jun-Wei  , Yan Shao-Hui  ,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China;,   Security Printing Institute of People's Bank of China, Beijing 100070, China
Published: December 2020

Upon excitation of high intensity linearly polarized femtosecond laser, a blue-shifted two-photon induced photoproduct named F540 state with permanent photo-induced anisotropy is observed in bacteriorhodopsin (BR) films. Based on the F-state, permanent optical data storage can be realized with spatial field modulation of femtosecond laser. By using a phase-only spatial light modulator to modulate the spatial phase distribution of the incident femtosecond laser beam, we generate spot-patterns in the focal plane of the microscopic objective lens, and the patterns are recorded in the BR film. At the same time, by varying the polarization direction of the excitation laser beam, polarization-multiplexed optical data storage in the BR film is demonstrated, which is applicable to high-density optical data storage and optical information encryption.
A low radar cross-section artificial magnetic conductor reflection screen covering X and Ku band
Authors: Zheng Yue-Jun  , Gao Jun  , Cao Xiang-Yu  , Li Si-Jia  , Yang Huan-Huan  , Li Wen-Qiang  , Zhao Yi  , Liu Hong-Xi  ,   Information and Navigation College of Air Force Engineering University, Xi'an 710077, China
Published: December 2020

Based on the properties of the artificial magnetic conductor (AMC), a broadband low radar cross-section (RCS) reflection screen covering X and Ku band is designed and fabricated. The reflection screen is formed by combining two AMC cells, i.e., AMC1 with a dual band Jerusalem cross structure, and AMC2 with a wideband metal square patch structure. By optimizing the structures of these AMC cells, it is achieved that the frequency corresponding to the inversion point of the AMC1 reflection phase curve is equal or close to the frequency corresponding to the null point of the AMC2 reflection phase curve. Therefore, the valid reflection phase difference band is broadened and the RCS is reduced in a wider band. In addition, presented in this paper is a theoretical formula to calculate the reflection energy peak direction. When the incident angle, chessboard unit dimension and observed frequency are fixed, the reflection energy peak direction can be calculated by the formula. The calculation results from the theoretical formula are consistent with the HFSS simulation results, so the theoretical formula is valid. The simulation results indicate that, compared with the same-dimension metal RCS, the backscattering RCS is reduced by more than 10 dB in a frequency range of 7.4-17.0 GHz, except minority frequencies close to 9.8 GHz. The 10 dB-reducing RCS bandwidth covers the entire X band and most of Ku band, and the relative bandwidth is 78.7%. The largest reduction reaches 40.3 dB at 11.6 GHz. The simulations and the measurements are in good agreement. The results validate the broadband low RCS property of the reflection screen.
One-dimensional cellular automaton model of traffic flow considering dynamic headway
Authors: Zhang Ning-Xi  , Zhu Hui-Bing  , Lin Heng  , Huang Meng-Yuan  ,   Faculty of Architectural, Civil Engineering and Environment, Ningbo University, Ningbo 315211, China
Published: December 2020

Based on the NaSch cellular automaton traffic model, a modified single lane traffic model is proposed by considering the dynamic headway of successive vehicles, in which the complex characteristic and driving behavior difference between drivers are taken into account. The relationship between the flow rate and the traffic density is obtained by the numerical simulation, and it shows a two-dimensional region in the flow density plane. The three traffic phases, i.e., free flow, synchronized flow, and wide moving jams, are exhibited. It indicates that the synchronized flow and traffic jams can appear even if there is no traffic bottleneck. Besides, the high speed car-following phenomenon is indicated when the traffic is in the synchronized flow. The rate of the high speed car-following is in good agreement with the measured result.
Stack-through silicon via dynamic power consumption optimization in three-dimensional integrated circuit
Authors: Dong Gang  , Wu Wen-Shan  , Yang Yin-Tang  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Microelectronics Institute, Xidian University, Xian 710071, China
Published: December 2020

Stack-through silicon via (TSV) used in three-dimensional integrated circuit has good temperature and heat transfer characteristics. A novel model for optimizing the dynamic power consumption based on stacked-TSV is proposed in this paper, in which delay, area and minimum aperture are comprehensively considered. After extracting single TSV parasitic electrical parameters, we analyze the influences of TSV size on multilayer TSV power consumption and delay performance, thereby building the hierarchical reduction TSV structure step by step. Moreover, the influences of TSV height and thickness of oxide layer are discussed. Results show that the model can significantly improve the dynamic power consumption at the expense of little delay. The power consumption optimization reduction is up to 19.52% with 5% delay penalty.
Method of identifying consitutive parameter in Tb0.3Dy0.7Fe2 Alloy
Authors: Yan Bai-Ping  , Zhang Cheng-Ming  , Li Li-Yi  , Tang Zhi-Feng  , Lü Fu-Zai  , Yang Ke-Ji  ,   Institute of Modern Manufacturing Technology, Zhejiang University, Hangzhou 310027, China;,   Institute of Electromagnetic and Electronic Technology, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In this paper, a simple consititutive parameter identification method for the application of domain model in Tb0.3Dy0.7Fe2 alloy is studied, the magnetization and hystersis characteristics are summarized. Targeting the problem of unclarity and difficulty in directly testing the constitutive parameters in Tb0.3Dy0.7Fe2 alloy, numerical calculation and experimental test are used to propose a parameter identification method. Coordinate transformation and graphic solution technique are used in this paper to simplify the minimization solutions of domain rotation in alloy. The dependence of parameters in magnetic rotation model is studied. On this basis, combined with simple experimental test, the method of indentifying Tb0.3Dy0.7Fe2 alloy is established, and the influences of anisotropy constants K1 and K2, energy distribution factor ω, axis orientation distribution in domain rotation are discussed. The method can simply and rapidly identify the constitutive parameters of Tb0.3Dy0.7Fe2 alloy in magnetic domain model, which is significant to improve the numerical calculation of domain rotation in magnetostrictive material. The above theoretical computations are significant for establishing magnetomechanical model of magnetostrictive material, and results are helpful for perfecting the identification of constitutive parameters.
Beamforming design based on energy harvesting proportional fairness in a simultaneous wireless information and power transfer system
Authors: Zhang Hai-Yang  , Huang Yong-Ming  , Yang Lü-Xi  ,   School of Information Science and Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

In this paper, we propose a beamforming design based on energy harvesting proportional fairness to overcome the unbalance of energy harvesting in a simultaneous wireless information and power transfer system. We aim at achieving the energy harvesting proportional fairness while guaranteeing the signal to interference plus noise ratio constraints at the information receivers and total power constraint at the transmitter by optimizing the beamforming vectors. This optimization problem is of non-convex and hence difficult to solve. In order to solve it, in this paper, we first use the semi-definite relaxation technique as a tool to transform it into a semi-definite program problem, and then propose an iterative algorithm based on bisection method to obtain the optimal beamforming vectors. Besides, we also extend our result to a robust case where the transmitter only knows a part of the channel state information and the bound of channel errors, and propose an iterative algorithm based on worst-case method to obtain the corresponding beamforming vectors. Finally, the simulation results show that the proposed algorithms can achieve both the energy harvesting proportional fairness and global optimum.
Dynamic behavior in firing rhythm transitions of neurons under electromagnetic radiation
Authors: Li Jia-Jia  , Wu Ying  , Du Meng-Meng  , Liu Wei-Ming  ,   State key Laboratory for strength and Vibration of Mechanical Structure, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

This paper presents the mathematical model of membrane current of neuron resulting from electromagnetic radiation based on the foundation of neuronal energy theory; and the effect of electromagnetic radiation on the dynamic behaviors of single neuron and the firing activities of two neurons coupled with gap connection are investigated. Results show that the neuronal firing rate is lowered as the radiation intensity increases, and finally reaches a stable value. As the radiation intensity increases, the periodical spiking of neuron is transformed into bursting firing, which is well explained based on the dynamic bifurcation theory. It turns out that the bursting firing induced by the electromagnetic radiation could spread out in neuronal network through an electrical gap junction.
Realization of periodical control and synchronization of single-mode laser Haken-Lorenz system with intermittent feedback
Authors: Li Chun-Lai  , Yang Ben-Shan  , Huang Le  , Feng Ting  , He Yao  , Zou Mao-Rong  ,   Innovation Training Center of Photoelectronic Technique and Applied Physics, College of Physics and Electronics, Hunan Institute of Science and Technology, Yueyang 414006, China
Published: December 2020

For the chaos existing in a single-mode Haken-Lorenz laser system, a scheme of intermittent feedback with one variable is proposed. Numerical simulation results show that with the increase of appropriate control intensity, the Haken-Lorenz chaotic system can be suppressed to period 1, period 2, period 4, period 6, and period 8. Meanwhile, the synchronization of Haken-Lorenz chaotic systems is achieved based on the scheme of intermittent feedback.
Chaotic characteristics analysis and prediction for short-term wind speed time series
Authors: Tian Zhong-Da  , Li Shu-Jiang  , Wang Yan-Hong  , Gao Xian-Wen  ,   College of Information Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;,   College of Information Science and Engineering, Northeastern University, Shenyang 110819, China
Published: December 2020

A short-term wind speed time series prediction is studied. First, 0-1 test method for chaos is used to identify the short-term wind speed time series that has chaotic characteristics. Through phase space reconstruction, the delay time is determined by using C-C algorithm; and the embedding dimension is determined by using G-P algorithm. Then a least square support vector machine with parameters online modified is proposed, so that an improved particle swarm optimization algorithm may be used for the prediction of parameters optimization. Simulation experiment shows that the present method for its prediction accuracy, prediction error, and prediction effect is better than other prediction methods. Thus the proposed prediction method is effective, and feasible.
Effect of oxygen vacancy on lattice and electronic properties of HfO2 by means of density function theory study
Authors: Dai Guang-Zhen  , Jiang Xian-Wei  , Xu Tai-Long  , Liu Qi  , Chen Jun-Ning  , Dai Yue-Hua  ,   Anhui Provincial Key Lab of Detection and Automation, School of Electrial Engineering, Anhui Polytechnic University, Wuhu 241000, China;,   Anhui Provincial Key Lab of Integrated Circuit Design, School of Electronics and Information Engineering, Anhui University, Hefei 230601, China;,   Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

HfO2, as a gate dielectric material for the charge trapping memory, has been studied extensively due to its merits such as high k value, good thermal stability, and conduction band offset relative to Si, etc.. In order to understand the reason why the charge trapping efficiency is improved by high k capture layer with respect to charge trapping type memory, the variation of HfO2 crystal texture induced by oxygen vacancy and the influences of it are investigated using the first principle calculation based on density functional theory. Results show that the distance of the nearest neighbor oxygen atom from oxygen vacancy is markedly reduced after optimization, whereas the decrease of distances between the next nearest neighbor oxygen atom from oxygen vacancy and hafnium is less. The change of local crystal lattice is caused by optimized oxygen vacancy for it significantly changes the local lattice, but rarely influences the far lattice. Deep energy level and density of electron states in conduction band are contributed by Hf atoms, while the density of electron states in valence band is contributed by O atoms. The local density of electron states in each element and the total density of electron states in the optimization system are all larger than those in the system without optimization, and the sum of the local densities of electron states is less than the total density of electron states. The trapped charges are moving mainly around the oxygen vacancy and the adjacent atoms of oxygen in the optimization system, but the charges are without optimization throughout the system. The local energy of charge is increased in optimized defect system, while the local energy of charge is conspicuously reduced in the system without optimization, i.e. lattice variation without saturation characteristic has a large effect on the local energy of charge. Results further prove that the change of crystal lattice induced by oxygen vacancy has strong ability to capture charge, which helps improve the features of memory.
Feature extraction and recognition of non-resolved space object from space-based spectral data
Authors: Sun Cheng-Ming  , Zhao Fei  , Yuan Yan  ,   Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100094, China;,   Key Laboratory of Precision Opto-mechatronics Technology, Ministry of Education, Beihang University, Beijing 100191, China
Published: December 2020

The location and intensity of non-resolved space object can be obtained in space-based surveillance, however, the material, size, and status of the object are lost. Spectrum represents the inherent property difference of the object, which can be used as an important means for feature extraction and recognition of non-resolved space object. According to the influence factors, including material, structure, background and orbit, a mathematical model for spectral properties of space object is established. Based on the model, inverse calculation method for feature extraction and recognition of space object is proposed. Taking the HuanJing-1 satellite scale model as an example, experimental verification for feature extraction and recognition of space object in typical parameters is made. Experimental results demonstrate the validity of the modeling method.
Manipulation of electromagnetic wavefront based on zero index magnetic metamaterial
Authors: Lin Hai-Xiao  , Yu Xin-Ning  , Liu Shi-Yang  ,   Institute of Information Optics, Zhejiang Normal University, Jinhua 321004, China;,   State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China
Published: December 2020

In this work, a zero index magnetic metamaterial (ZIMM) is designed based on the two-dimensional array of ferrite rods periodically arranged in the air. By calculating the photonic band structures within the framework of multiple scattering theory and retrieving the effective electric permittivity εeff and effective magnetic permeability μeff, the structure parameters can be optimized and then the effectively matched zero index with εeff = μeff = 0 is achieved. Within this matched ZIMM, electromagnetic (EM) wave can propagate without any phase delay, resulting in the manipulation of phase pattern in space. By simulating the electric field patterns of a Gaussian beam incident on ZIMM slabs with different thickness, zero phase delay inside the slab can be observed. By designing various outgoing interfaces a plane EM wavefront can be transformed into a cylindrical one, or even into a more general wavefront. In addition, the focusing and beam splitting effects are demonstrated as well. Besides, since the permeability of magnetic materials can be controlled by an external magnetic field or a temperature, the EM features of ZIMM can be flexibly tuned, enabling a promising prospect in designing EM devices and potential applications.
Control of topological structure in high-order optical vortices by use of noncanonical helical phase
Authors: Wang Ya-Dong  , Gan Xue-Tao  , Ju Pei  , Pang Yan  , Yuan Lin-Guang  , Zhao Jian-Lin  ,   Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

This paper proposes a method for controlling the topological structures in high-order optical vortices by employing a noncanonical phase structure. The control of the evolutions in high-order optical vortices by using a noncanonical phase structure with a nonuniform azimuthal gradient is studied numerically and experimentally. Results show that the propagation of high-order optical vortices along with a noncanonical phase structure becomes a decayed optical distribution with multiple one-charged singularities along a line. In addition, the control from the noncanonical phase structure can suppress random evolutions of topological structures resulted from the phase noise. These conclusions may indicate a new method to control the decay of high-order optical vortices, and promising potential applications in many fields, such as optical vortices-based optical communications and optical tweezers.
Analysis on the absorption curve asymmetry of electromagnetically induced transparency in Rb87 cold atoms
Authors: Bai Jin-Hai  , Lu Xiao-Gang  , Miao Xing-Xu  , Pei Li-Ya  , Wang Meng  , Gao Yan-Lei  , Wang Ru-Quan  , Wu Ling-An  , Fu Pan-Ming  , Zuo Zhan-Chun  ,   Institute of Physics, Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
Published: December 2020

The asymmetry of the absorption curve of electromagnetically induced transparency by a resonant coupling field in -type three-level systems for Rb87 cold atoms is investigated. We find that it is the other excited state, separated by an interval of 814 MHz, that induces this phenomenon. The primary cause of it is the stimulated Raman scattering. We also find that the ratio between the heights of the absorption peaks on the two sides of the transparency window is proportional to the intensity of the coupling beam. The theoretical result agrees well with the experimental data.
Study on characteristics of coherent population trapping spectral line for chip-scale atomic clock
Authors: Yin Yi  , Zhang Yi  , Tan Bo-Zhong  , Chen Jie-Hua  , Gu Si-Hong  ,   Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China;,   School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

To Obtain an appropriate coherent population trapping (CPT) signal through a miniature atomic vapor cell is one of the key steps to implement a chip-scale atomic clock (CSAC). In the present experiment, the high S/N differential CPT spectral line has been achieved with a miniature atomic vapor cell through modulating the laser and extracting 87Rb atom laser interacting signal using the phase sensitive demodulation technique. With the spectral line, the dependence of CPT signal on the working parameters and the dependence of frequency stability of CSAC on the quality of the CPT signal have been studied; the obtained experimental results agree well with the theoretical prediction, which can be used as the recommended working parameters for CSAC. The methods exploited in the experiment can be implemented in the resource of a CSAC, therefore this experiment explores for CSAC the practical approaches of performance optimization.
Effect of Raman gain on the state of polarization evolution in a low-birefringence fiber
Authors: Wang Mei-Jie  , Jia Wei-Guo  , Zhang Si-Yuan  , Menke Nei-Mu-Le  , Yang Jun  , Zhang Jun-Ping  ,   School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

Using the coupled nonlinear Schrödinger (CNLS) equation containing the Raman gain, the Duffing equation with Raman gain is derived, which is represented by the Stokes parameters, and then the elliptic integrals are used to compute the analytical solutions. This article focuses on the analysis of the Raman gain influence on the evolution of the polarization state when the optical waves are propagating in a low-birefringence fiber. Results show that the transmission cycle of the polarization evolution state can be changed due to Raman gain, if the input power and motion constants have a certain relationship.
Influence of deuteration degree on the transverse stimulated Raman scattering gain coefficient of DKDP crystal
Authors: Chai Xiang-Xu  , Li Fu-Quan  , Wang Sheng-Lai  , Feng Bin  , Zhu Qi-Hua  , Liu Bao-An  , Sun Xun  , Xu Xin-Guang  ,   State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

In this paper, the spontaneous Raman spectra of K(H1-xDx)2PO4 (DKDP) crystals with different deuteration degrees in the Z(XX)Y scattering geometry are measured. And the Raman spectroscopy parameters including Raman shift, full-width at half maximum, and scattering intensity, which are related to the transverse stimulated Raman scattering (TSRS) gain coefficients, are analyzed in detail. Using the Raman scattering from water as a reference, the TSRS gain coefficients of DKDP crystals with different deuteration degrees are derived. It is found that with increasing deuteration degree in DKDP crystal the TSRS gain coefficient first decreases to about 40.1% of the KDP crystal, then increases to about 68.9%. We regard the change of the full-width at half maximum as the main reason for the dependence of TSRS gain coefficient on the deuteration degree.
Research on the controllable nonlinear laser transmission properties of MoS2 nano-micron film
Authors: Wang Yuan-Qian  , Lin Cai-Fang  , Zhang Jing-Di  , He Jun  , Xiao Si  ,   Institute of Super-microstructure and Ultrafast Process in Advanced Materials, Department of Physics and Electronics, Central South University, Changsha 410083, China;,   Hunan Key Laboratory for Super-Microstructure and Ultrafast Process, Central South University, Changsha 410083, China
Published: December 2020

Ultrashort femtosecond pulse laser (pulse duration 2 nano-micron films (thickness 150–200 nm) are prepared by spin-coating method. Optical limiting test results show that for the ultrashort pulse laser, this film shows increasing transparency at low light intensity, while it shows decreasing transparency at a higher light intensity (optical limiting). It is capable of changing the optical limiting threshold by changing the incident wavelength which can be used for transparency enhancement and protection against damage of concentrator solar cells. Using this method to have a commercial GaAs solar cells coated found the conversion efficiency reduction 50%.
Study of near-infrared dispersion wave generation for microstructured fiber
Authors: Chen Qi-Jie  , Zhou Gui-Yao  , Shi Fu-Kun  , Li Duan-Ming  , Yuan Jin-Hui  , Xia Chang-Ming  , Ge Shu  ,   South China Normal University, GuangDong Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China
Published: December 2020

Properties of nonlinear microstructured fiber fabricated in our laboratory are theoretically analyzed using the finite element method. This fiber has a high nonlinearity and phase matching for the dispersion wave generation. To achieve all-fiber nonlinearity in microstructured fiber, the dependence of dispersion wave on the pump power is investigated. When changing the pump power at 1032 nm with a femtosecond fiber laser, the near-infrared dispersion waves cover a region from 753 to 789 nm. The central wavelength and bandwidths alter obviously, and the fiber length has a remarkable impact on pulse broadening and frequency spectrum. Results coincide with the analyses. These results could be a reference for all-fiber nonlinearity of microstructured fiber, and lay a foundation for biological and medical applications, especially some researches on the near-infrared source for nonlinear light microscopy.
Influence of background radiation on the precision of passive ranging
Authors: Zhang Yu  , Liu Bing-Qi  , Yan Zong-Qun  , Hua Wen-Shen  , Li Gang  ,   Department of Electronics and Optics Engineering, Ordnance Engineering College, Shijiazhuang 050003, China
Published: December 2020

Experimental program is designed to analyze the influence of background radiation on the accuracy of passive ranging based on oxygen spectral absorption; an acousto-optic tunable hyper spectral imaging spectrometer is used as the measuring device and a halogen light as the target. Firstly, the basic principles and experimental program of passive ranging technology based on oxygen absorption are introduced; then the halogen light spectral distribution at different distances during the night is collected using the acousto-optic tunable hyper spectral imaging spectrometer. Oxygen absorption rate is calculated and the relationship model between the oxygen absorption rate and the path is established according to the principle of oxygen spectrum absorption passive ranging. Then the oxygen absorption rate of the target is collected and calculated at the distance of 2360 m for different time. The measuring ranges during the day are solved by the model and the errors are analyzed, the influence of background radiation on the passive ranging is gained finally. Results show that according to the model, the maximum ranging error is 6.74% during the daytime, and the error becomes smaller with the elevation angle of the sun becoming smaller and the background darker. The results give 1.10% ranging error during the nighttime.
S-band microwave-Induced thermo-acoustic tomography system
Authors: Du Jin-Song  , Gao Yang  , Bi Xin  , Qi Wei-Zhi  , Huang Lin  , Rong Jian  ,   Shenyang Institute of Automation, Chinese Academy of Science Key Laboratory on Radar System Research and Application Technology of Liaoning Province, Shenyang 110079, China;,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The technology of microwave-induced thermo-acoustic tomography that transmits electromagnetic wave pulses to the object and makes it absorb energy, can cause a rapid temperature rise in it. At the same time, a pressure wave will be generated instantaneouly, corresponding to generating an ultrasonic signal which can be detected by an ultrasonic sensor. After the ultrasonic signal is sampled and an image reconstructed, the image can reflect the characteristics of the electromagnetic energy absorbed by the object. The method combines a microwave imaging of high contrast and high resolution ultrasound imaging characteristics, hence verifies theoretically the feasibility of the thermo-acoustic imaging techniques for early breast cancer detection. In this study, we use S-band microwave pulse radiation source to radiate the biological tissue, and also make use of the circling mechanical motion systems to scan the tissue. In order to verify the imaging performance of the simulation experiments, we use both tumors, body and actual biological tissue as the samples of the experiments. The imaging reconstruction and comparative analysis can verify that the experimental system detects and distinguishes the tumor phantoms and the real biological tissue effectively. Results of the performance of high-resolution images and high contrast by the methods can provide further theoretical support for early detecting of breast cancer.
Exact invariants and adiabatic invariants for nonholonomic systems in non-Chetaev's type based on El-Nabulsi dynamical models
Authors: Chen Ju  , Zhang Yi  ,   College of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China;,   College of Civil Engineering, Suzhou University of Science and Technology, Suzhou 215011, China
Published: December 2020

In this paper, the problem of exact invariants and adiabatic invariants for nonholonomic system in non-Chetaev's type based on the El-Nabulsi dynamical model is studied. First, the El-Nabulsi-d'Alembert-Lagrange principle is deduced and the differential equations of motion of the system are established. Then, the relation between the Noether symmetry and the exact invariant that is led directly by the symmetry for undisturbed nonholonomic system in non-Chetaev's type is given. Furthermore, by introducing the concept of high-order adiabatic invariant of a mechanical system, the conditions that the perturbation of symmetry leads to the adiabatic invariant and its formulation are studied for the nonholonomic system in non-Chetaev's type under the action of small disturbance. As a special case, the problem of the exact invariants and the adiabatic invariants for the nonholonomic system in Chetaev's type in El-Nabulsi model is discussed. At the end of the paper, two examples for the nonholonomic systems in non-Chetaev's type constraints and also the Chetaev's type constraints are given respectively to show the application of the methods and the results of this paper.
Discussion on the physical meaning of free surface velocity curve in ductile spallation
Authors: Pei Xiao-Yang  , Peng Hui  , He Hong-Liang  , Li Ping  ,   Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China;,   State Key Laboratory of Explosion and Technology, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The physical meaning of ductile spall fracture corresponding to the typical properties in free surface velocity curve has been discussed. A correlation between the macroscopic responses and the evolution of mic-damage is established; the pullback signal the found to correspond to the condition for nucleation of voids, and the rate at which the velocity rises to the first peak beyond the minima corresponds to the rate of damage evolution, and by using the velocity period after the the pullback signal we can distinguish the state of damage.
Constructal optimization of complex fin with convective heat transfer based on entransy dissipation rate minimization
Authors: Feng Hui-Jun  , Chen Lin-Gen  , Xie Zhi-Hui  , Sun Feng-Rui  ,   Institute of Thermal Science and Power Engineering, Naval University of Engineering, Wuhan 430033, China;,   Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering, Wuhan 430033, China;,   College of Power Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Based on the constructal theory, the constructal optimization of a complex fin is carried out by taking the minimum equivalent thermal resistance, which is defined according to entransy dissipation rate, as the optimization objective. Optimal constructal of the complex fin is obtained by tsking into consideration the entransy dissipation performance caused by heat conduction and heat convection. Comparisons between the optimal constructal with different shapes and optimization objectives of the fins are performed. Results show that there exist the optimal ratios of the height to the length of the elemental fin, central cavity and fin tip which lead to the triple minimum equivalent thermal resistance of the complex fin. By comparing the optimal constructal of the complex fin with that of the T-Y shaped fin, the structure of the complex fin will greatly improve its global heat transfer performance. When the heat transfer of the fin is two-dimensional and the root of the fin is broader, the more non-uniform the temperature at the fin root, the bigger difference of the optimal constructs the complex fin obtains, based on the minimizations of the equivalent thermal resistance and maximum thermal resistance. For the optimal design of the fin in pracuice, when the thermal safety of the fin is ensured, the constructal design scheme of the fin with minimum equivalent thermal resistance can be adopted to reduce temperature difference in the average heat transfer and improves the global heat transfer performance. This paper provides some guidelines for the optimal design of the complex fin from the point of view of heat transfer optimization.
Effect of ion-beam surface modification technology on the variation of surface texture
Authors: An Shu-Dong  , Wang Xiao-Yan  , Chen Xian  , Wang Yan-Wu  , Wang Xiao-Bo  , ZhaoYu-Qing  ,   Key Laboratory for Physical Electronics and Devices of Ministry of Education, School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Ion-beam surface bombardment modification technology is successfully used to manufacture different kinds of nano-textures on the surface of silicon substrate. Relationship between the morphology and arrangement patterns of nano-textures and the bombarding parameters is studied. Results show that the ion-beam bombardment has a significant impact on surface morphology. Different kinds of textures on silicon substrate can be formed according to the variation of bombardment time. The nanodot array texture is observed on the surface of silicon substrate when the duration of argon ion-beam bombardment is 15 minutes. Simultaneously, the tetrahedral amorphous carbon film is deposited on the silicon substrates that have different kinds of nano-texture. The microstructure of ta-C film deposited on unprocessed and nano-textured silicon substrate is analyzed by X-ray photoelectron spectroscopy. Results indicate that the content of sp3 bonds decreases with increasing bombardment time, and thereafter keeps a steady value. The ta-C films deposited on the nanodot-textured substrate shows the lowest sp3 fraction. It is also observed by friction and wear test that the wear time is enhanced from 10 to 70 min. The tribological properties is highly improved when the coating is deposited on the nano-textured substrate.
Recent progress in graphene and its derivatives as interfacial layers in organic solar cells
Authors: Huang Lin-Quan  , Zhou Ling-Yu  , Yu Wei  , Yang Dong  , Zhang Jian  , Li Can  ,   State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Dalian 116023, China;,   Department of Materials Science & Engineering, Guilin University of Electrical Technology, Guilin 541004, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

This review surveys the application of graphene and its derivatives in organic solar cells, used as interfacial layers: including anode interfacial layers, cathode interfacial layers, and intermediate layers in a tandem device. Research work has be done for increasing the electroconductivity by reducing the oxide to partially oxidized graphene, as well as chemically modifying or making composite interfacial layer. Additionally, the researches on graphene derivatives and combined interfacial layers used as a cathode interfacial layer or an intermediate layer in the tandem device are discussed. Finally, this review suggests that graphene and its derivatives are potential to be used in perovskite solar cells.
Cellular method combined with Monte Carlo method to simulate the thin film growth processes
Authors: Ruan Cong  , Sun Xiao-Min  , Song Yi-Xu  ,   State Key Laboratory on Intelligent Technology and Systems, Tsinghua National Laboratory for Information Science and Technology, Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China
Published: December 2020

Study on simulation method for the thin film growth processes on atomic scale is currently a hot research field. The simulation method mainly aiming at nanometer scale model demands huge computational cost and memory cost. In order to solve the problem, a cellular method combined with Monte Carlo method is presented in this article to simulate the growth processes of thin film on micron scale. Based on cellular method for model representation and evolutionary computation, we greatly reduce the memory requirements and improve the efficiency of computation, and the Monte Carlo method is used to determine the particle migration. Moreover, specific research on the growth process of silicon nitride thin film is implemented, and the simulation results are compared with the experimental data and the molecular dynamics simulation results of the surface morphology and composition, so as to verify the effectiveness of this method.
Key issues in highly efficient perovskite solar cells
Authors: Yang Xu-Dong  , Chen Han  , Bi En-Bing  , Han Li-Yuan  ,   State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Preparation of Perovskite solar cell, an emerging low-cost photovoltaic technology in rapid development, has provided a ray of hope to solve the energy problem. However, its low reproducibility and stability limit the wide application of this potential technology. In this review, we summarize the recent progress with a focused discussion on some key issues in the development of perovskite solar cells. Starting from the analysis of basic structure and working principles, we first discuss the perovskite-based light harvesting layer and the general strategy to control its spectrum response. We also demonstrate the effect of film morphology on the device performance and the reproducibility which requires very uniform thin films. Then we discuss the major function of electron transporting layer and hole blocking layer, and point out the importance of compact hole blocking layer with less nano-scaled pinholes. For the hole transporting layer, we focus the discussion on the stability problem induced by widely used dopants that can improve the hole conductivity in the hole transporting layer while the dopants' deliquescent behavior also can induce the decomposition of perovskite-based light harvesting layer with a rapid degradation of the whole device. The potential approaches to solve this stability problem, such as using a dopant-free hole transporting material or making device without any hole transporting materials, are also discussed. Finally, we are in prospect of overcoming the main challenges in the future research for high performance perovskite solar cells.