bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and fabrication of cascaded X-ray planar parabolic compound refractive lens
Authors: Fu Ming-Lei  , Le Zi-Chun  , Zhou Han-Qing  , Zhang Ming  , Quan Bi-Sheng  , Wang Hua  , Mao Cheng-Wen  , Wang Chang-Hui  , Shen Xiao-Yan  ,   College of Science, Zhejiang University of Technology, Hangzhou 310023, China;,   Institute of Optical Engineering, Zhejiang University of Technology, Hangzhou 310023, China;,   Shanghai Institute of Applied Physics, Shanghai Synchrotron Radiation Facility, Chinese Academy of Sciences, Shanghai 201204, China
Published: December 2020

Due to its attractive features such as compact size, simple to align and wide working range of photon energy, the X-ray compound refractive lens (CRL) has gradually become one of the standard accessories to focus the X-ray beams from the synchrotron radiation light source. In this paper, a cascaded planar parabolic CRL is designed and fabricated. The novel CRL is composed of type Ⅰ and type Ⅱ refractive elements in order to achieve a small spot size while maintaining the transmission. In type I refractive element, the parabolic geometry aperture (R0) is large, while, in type Ⅱ refractive element, the radius of curvature (R) at the parabolic vertex is small. So N1 numbers of type I and N2 numbers of type Ⅱ refractive elements are cascaded to form a single-chip CRL. A cascaded X-ray planar parabolic CRL is constructed using PMMA material by means of LIGA techniques. The main structural parameters of type Ⅰ refractive elements are: N1=15, R1=200 μm, 2R01=564 μm. The main structural parameters of type Ⅱ refractive elements are: N2=20, R2=50 μm, 2R02=140 μm. The cascaded planar parabolic CRL is tested on the beam line whose original incident X-ray spot is 200 μm×100 μm at Shanghai synchrotron radiation facility. The measured lateral focusing spot size is 24.9 μm@8 keV, the transmission rate is 2.19% and the focal length is 1.052 m.
Measurement of the spectral properties of the coincident-frequency entangled biphoton state at optical communication wavelength
Authors: Wang Meng-Meng  , Quan Run-Ai  , Tai Zhao-Yang  , Hou Fei-Yan  , Liu Tao  , Zhang Shou-Gang  , Dong Rui-Fang  ,   Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The frequency entangled biphoton source generated via spontaneous parametric down-conversion (SPDC) process has found important applications in the fields of quantum clock synchronization, quantum communication, quantum information processing, etc. As quantum technologies evolve, quantitative characterization of the frequency entanglement becomes necessary and has been implemented by measuring the spectral properties of the biphoton state. However, due to the high dark rate and low quantum efficiency of the InGaAs single-photon detectors, direct measurement of the spectral properties of the biphoton state at optical communication wavelength is hard to implement. In this paper, we report the measurement of the spectral properties of a biphoton state at optical communication wavelength which is generated from periodically poled potassium titanyl phosphate (PPKTP) pumped by an ultra-short pulsed optical source at 787 nm. Based on the coincidence measurement setup together with two infrared spectrometers, the spectra of the signal and idler photons are obtained with their center wavelengths being 1574.4 nm and 1574.9 nm, while their 3-dB bandwidths being 35.3 nm and 37.6 nm respectively. The joint spectrum of the photon pair is observed as well and shows a coincident-frequency entanglement and a joint spectrum bandwidth of 3 nm. According to the ratio of the single-photon spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 12, denoting a relatively high quality of the entanglement.
Solitary waves and their existence conditions in microstructured solids
Authors: Naranmandula  ,   College of Physics and Electronic Information, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

By taking into account the macroscale nonlinear effect, quadratic and cubic microscale nonlinear effects, and microscale dispersion effect, a new model capable to describe the longitudinal wave propagation in one-dimensional microstructured solid is established based on the Mindlin theory. Using the qualitative analysis theory in the planar dynamical systems, we have analyzed the existence conditions and geometrical characteristics of solitary waves, and proved that the faces under the influence of quadratic microscale nonlinear effect, can form an asymmetric solitary wave in the microstructured solid; and under the influence of cubic microscale nonlinear effect, they can form a symmetric solitary wave in the microstructured solid, when the medium parameters and the propagation speeds of solitary waves satisfy certain appropriate conditions. Finally, the above results are further verified using a numerical method.
Theory and method for nonlinear acoustics detection based on hysteretic stress-strain relation
Authors: Zhang Shi-Gong  , Wu Xian-Mei  , Zhang Bi-Xing  ,   State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academic of Sciences, Beijing 100190, China
Published: December 2020

In this paper, PM (Preisach-Mayergoyz) model in one dimension is extended to two dimensions. Hysteretic stress-strain relation could be obtained when hysteretic mesoscopic elastic unit (HMEU) is considered.The sound field is calculated using a first-order finite difference equation, and the high-odd-order harmonic waves can be found apparently in the sound field. Then, the received full waves are filtered,amplified, time-reversed, and re-emitted through corresponding receiving transducers. The high-order harmonic waves focus on the micro-damage zone. So this method can be used to detect the micro-damages by nonlinear high-order harmony waves. Furthermore, it also provides a method of the early detection of fatigue damages.
Frequency domain response estimation of underwater acoustic channel and noise estimation for single-carrier frequency domain equalization
Authors: Zhang Xin  , Zhang Xiao-Ji  , Xing Xiao-Fei  , Jiang Li-Wei  ,   School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

Single-carrier frequency domain equalization (SC-FDE) has drawn increasing researches because of its lower computational complexity and better performance of mitigating intersymbol interference (ISI) as compared with the time domain equalization. The practical SC-FDE systems, however, require the knowledge of the channel frequency domain response and the noise power to calculate filter coefficients of the frequency domain equalizer. Improper channel and noise estimations have been shown to result in error floor at high signal-to-noise ratio (SNR), which may impede the utilization of SC-FDE in the high-rate underwater acoustic (UWA) communications. In this paper, we discuss the possible influence of inaccurate noise estimation on the error floor at high SNR, and propose a joint estimation scheme for the channel time domain and frequency domain responses and also the noise power based on Chu sequence. The channel energy concentration region is determined by the threshold and the sparse channel impulse response (CIR) of UWA channels, used in denoising process of the CIR and the noise power computation. The bite error ratio performance of the SC-FDE variation versus the threshold is simulated via the UWA models, and accurate noise power estimation is shown to be desirable to improve the SC-FDE performance. Numerical examples also indicate that our joint estimation scheme can eliminate the error floor and improve the performance of SC-FDE at high SNR.
Sound wave separation method based on spatial signals resampling with single layer microphone array
Authors: Song Yu-Lai  , Lu Huan-Cai  , Jin Jiang-Ming  ,   Key Laboratory of E&M, Ministry of Education & Zhejiang Province, Zhejiang University of Technology, Hangzhou 310014, China;,   Key Laboratory of Signal Processing of Zhejiang Province, Hangzhou 310014, China
Published: December 2020

In order to reconstruct the sound field of target sources in non-free sound field, a method of sound field separation and reconstruction is presented based on spatial resampling with single layer microphone array. In this method, the spherical harmonics are taken as the basis functions, and the spherical harmonics of different orders are added to describe the mathematical model of the sound field. On the basis of the nearfield acoustic holography, the coefficients of the basis functions can be obtained with two groups' sound pressures resampled from the microphone array, then the sound fields generated by the sound sources on both sides of the microphone array are separated. The mathematical model is validated against the benchmark values. A non-free sound field with a radially oscillating sphere and a transversely oscillating rigid sphere is built, and the impact of various parameters such as the signal to noise ratio, the geometric shape and area of the microphone array, location of target sound source, and frequency of signals on the accuracy of separation is examined. Finally, some suggestions are given for the industrial application of the above method.
Influence of inclusion in functionally graded materials on the surface temperature distributions
Authors: Ma Xiao-Bo  , Wang Fei  , Chen De-Zhen  ,   School of Mechanical Engineering, Tongji University, Shanghai 201804, China
Published: December 2020

In this paper, based on the hyperbolic equation of heat conduction, utilizing the image method and the wave function expansion method, the temperature distributions on the surface of a functionally graded material(FGM) containing a cylindrical inclusion are investigated. According to the model of thermal waves, a general solution of scattered fields of thermal waves is obtained. Effects of different physical parameters (such as the depth of buried inclusion, the thermal conductivity, the thermal diffusion length, the thermal diffusivity, and the thermal relaxation time) on the distribution of temperature are analyzed. The thermal waves are excited on the surface of the FGM by a periodically modulated laser. A cylindrical defect is taken as an inclusion under a thermal conduction condition. Results are expected to provide calculation methods and reference data for infrared thermal wave nondestructive evaluation of an FGM and the inverse problems in mathematical physics.
Research and design of thermal cloak with arbitrary shape based on Laplace’s equation
Authors: Qin Chun-Lei  , Yang Jing-Jing  , Huang Ming  , Hu Yi-Yao  ,   Wireless Innovation Lab, School of Information Science and Engineering of Yunnan University, Kunming 650091, China;,   School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

How to control and manipulate the heat flow in a flexible way is a hotspot of current research. Based on Laplace's equation, we propose a method to design thermal cloak of arbitrary shape. For a thermal cloak of regular shape, the thermal conductivity expression is derived by analytically solving the Laplace's equation under certain boundary conditions; for a thermal cloak of irregular shape, the distribution of thermal conductivity can also be obtained based on the numerical solution of Laplace's equation. Results of full wave simulation show that no heat fluxes emerge in the internal stealth area both for two-dimensional and three-dimensional thermal cloak of arbitrary shape. Meanwhile, the heat fluxes return to their original pathways, resulting in a perfect thermal invisible effect. This research provides a feasible method to design a thermal cloak of non-conformal cross section and has a guiding significance for the design and manufacturing of thermal cloak.
Effect of pulsation on thrombus studied by the lattice Boltzmann method
Authors: Zhou Jin-Yang  , Shi Juan  , Chen Jia-Min  , Li Hua-Bing  ,   School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China;,   School of Information and Communication Engineering, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

To research the effect of pulsation flow on anti-thrombosis, the plasma is treated as water, and the red blood cells are regarded as suspended rigid particles having the same density as water. First, an appropriate embolism is formed in a tapered pipe under a certain hematocrit and differential pressure, and then a pulsating flow is exerted on the inlet of the tapered pipe to study the positive effect on anti-thrombosis of the pulsating flow.
Dynamics of the interaction between explosion bubble and free surface
Authors: Wang Shu-Shan  , Li Mei  , Ma Feng  ,   State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

A strong coupling effect between the bubble and water occurs when an explosive bubble expands and contracts near the water surface, leading to the complex changes of the flow field and various shapes of water plumes. An experimental system for small equivalent of charge RDX is designed to investigate the relations between the shapes of water plumes and the changes of the flow field. Two synchronized high speed cameras are used to record the changing process of the shapes of bubbles and water plume. Three typical shapes of bubble and six typical shapes of water plumes are observed. By theoretical analysis and direct observation of flow field changes among the bubble, the water surface, and the air, the evolution rule and formation mechanism of the six shapes of water plumes are allready revealed. Experimental results are also compared with that from the experiment of bubbles formed by electric spark. Through statistical analysis of bubble radius, expansion time, pulsation period, and bubble boundary movement, the dynamic process of bubble formation in near water surface explosion is clarified.
First principles calculation of occupancy, bonding characteristics and alloying effect of Cr, Mo, Ni in bulk α-Fe?
Authors: Wen Ping  , Li Chun-Fu  , Zhao Yi  , Zhang Feng-Chun  , Tong Li-Hua  ,   State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China;,   Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu 610213, China
Published: December 2020

Variations of electronic properties of bulk α-Fe(C) due to the addition of Cr, Mo, Ni are studied using the first principles method, which is based on the density functional theory (DFT). Lattice distortion, cohesive energy, density of states, Mulliken charge population, overlap population and charge density differences are calculated by the generalized gradient approximation (GGA)-PW91, and the occupancy, bonding characters and alloying effect of α-Fe(C) after mixing with alloy atoms are explained. Results show that Cr occupies perferentially the corner of α-Fe(C) unit cell, but Mo and Ni occupy the body-center position of the cell perferentially. The mixing with Cr produces the biggest cohesive energe, and that with Ni and Mo in turn produces lower cohensive energy. There coexist the metallic bond, covalent bond, and weaker ionic bond in the unit cell. The bonding orbitals are created by Cr3d with Fe3d, Mo4d with Fe3d, and Ni3d with Fe3d and C2p; the bonding force between Cr and other atoms in the bulk is powerful, and the stability of cell is good, so it helps improve the mechanical strength of steels. The bonding force between Ni and other atoms in the bulk is weaker, but it can also maintain the stability of the cell. Though the bonding force between Mo and other atoms in the bulk is powerful, but the antibonding is so strong, that the statility of the cell reduced greatly. This is harmful to the mechanical strength of steels.
Effects of V-heavy-doped ZnO on electric conductivity performance and absorption spectrum
Authors: Hou Qing-Yu  , Lü Zhi-Yuan  , Zhao Chun-Wang  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

Nowadays, in the reports of V-heavy-doped ZnO, when the doping moles of V in the range of 0.03125 to 0.04167, there is a current controversy between the two experimental results, i.e. the conductivity may be increased or decreased as the doping content increases. To solve this contradiction, the undoped and the two different concentrations of heavy-doped V atoms in Zn1-xVxO(x=0.03125, 0.04167) compounds have been set up based on the first-principles plane wave ultra-soft pseudo potential method of density functional theory in this paper, then all three compunds are geometrically optimized, and on this basis the GGA+U method is adopted to calculate the band structures, density of states, and the absorption spectrum. Results reveal that when the doping mole of V is in the range of 0.03125 to 0.04167, the volume doped system of the is increased as the total energy decreases; as the doping mole of V increases, the formation energy is reduced, the doping system is more stable, and the relative electronic concentration decreases, the migration rate and the conductivity are reduced; as the optical band gap is enlarged, the absorption spectrum blue shift is more significant. There are in agreement with the experimental results.
A model of hot carrier gate current for uniaxially strained Si NMOSFET
Authors: Lü Yi  , Zhang He-Ming  , Hu Hui-Yong  , Yang Jin-Yong  ,   Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an, 710071, China;,   Beijing Research Institute of Precise Mechatronic Controls, Beijing, 100076, China
Published: December 2020

Hot carrier gate current is one of the factors that influence the power and reliability of metal-oxide-semiconductor field effect transistor (MOSFET). Based on the physical process of generation of the hot carrier effect, a model of hot carrier gate current for uniaxially strained Si NMOSFET is developed. With that model, the simulation results of hot carrier gate current against stress intensity, gate-source bias, channel doping concentration, and drain-source bias are obtained and analyzed. The relationship between life time of time-dependent dielectric break down (TDDB) and gate-source bias is simulated and analyzed. Results show that the uniaxially strained Si MOSFET not only has smaller hot carrier gate current, but also has more stable reliability as compared with the strainless bulk device. Meanwhile, the simulation results match the experimental results very well, which validates the accuracy of the model.
Analysis and simulation of semiconductor thermoelectric power generation process
Authors: Wang Chang-Hong  , Lin Tao  , Zeng Zhi-Huan  ,   Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China;,   State Power Generation Co., Ltd., Zhongshan 528437, China
Published: December 2020

This paper presents an improved model of thermoelectric power generation, taking into consideration the effect of air heat transfer in a closed cavity between the thermoelectric couples. We have used the ANSYS software, under the condition of different numbers of thermoelectric couples and different models, to simulate numerically and analyze the temperature field and, the voltage field of thermoelectric power generation. Results show that the energy conversion efficiency of 127 pairs of thermoelectric couples increases rapidly as the temperature gradient between the hot and cold ends increases as compared with 1 pair of thermoelectric units; it is enhanced from 0.39% to 5.16% at an average of 3.02% while the temperature gradient varies from 20℃ to 220℃. The output voltage of the chip, power, and energy conversion efficiency would increase as the cross-sectional area increases while the cold junction temperature stays at 305℃, and the cold arm galvanic greater the temperature difference across the greater the increase rate, and thermoelectric power generation chip resistance, along with the cross-sectional area of the galvanic arm decreases. The output power can be up to 28.9W as the temperature difference is 220℃.
Electrical characteristics of individual In-doped ZnO nanobelt field effect transistor
Authors: Tang Xin-Yue  , Gao Hong  , Pan Si-Ming  , Sun Jian-Bo  , Yao Xiu-Wei  , Zhang Xi-Tian  ,   Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China
Published: December 2020

Back-gate field effect transistors based on In-doped ZnO individual nanobelts have been fabricated using the low-cost microgrid template method. The output (Ids-Vds) and transfer (Ids-Vgs) characteristic curves for the transistors are measured, and the mobility is derived to be 622 cm2· V-1· s-1. This value is obviously superior to those for most of materials including pure ZnO in the literature, and possible influence factors have also been discussed.
Study on the hydrogenation properties and stability of LaFe11.5Si1.5 compound
Authors: Zhang Deng-Kui  , Zhao Jin-Liang  , Zhang Hong-Guo  , Yue Ming  ,   College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China;,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

We have studied systematically the effects of temperature, time, and pressure on the process of hydrogen absorption in LaFe11.5Si1.5 compound. Results show that hydrogen absorption can increase the lattice parameter of the compound without changing its crystal structure. The LaFe11.5Si1.5H1.6 compound can be prepared at a hydrogen pressure of 0.0987 MPa at 423 K with uniform distribution of hydrogen. Hydrogen absorption can also increase the Curie temperature obviously, decrease the thermal hysteresis and maintain the magnetic entropy change at a high standard. With prolonged exposure time in air, the variation of the Curie temperature and magnetic entropy change of LaFe11.5Si1.5H1.6 compound are very small, implying that the magnetic thermal performance of hydride alloy has a good time stability.
Preparation and luminescent properties of Ca2Si(O4-xNx)：Eu2+ green-emitting phosphors
Authors: Zhou Ren-Di  , Huang Xue-Fei  , Qi Zhi-Jian  , Huang Wei-Gang  ,   College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
Published: December 2020

A nitrogen-contained solid solution Ca2Si(O4-xNx):Eu2+ green phosphors was successfully synthesized using the method of mixing Ca-Si-O xerogel precursor with Si3N4 powders in a non-reducing atmosphere (pure nitrogen). The structure, morphology, and luminescent properties of the phosphors are characterized by X-ray diffraction (XRD), \text {scanning} electron microscopy (SEM) and photoluminescence (PL) spectra. Results show that the Ca2Si(O4-xNx):Eu2+ is obtained and especially the reduction of Eu3+ to Eu2+ occurs when the mixture of Si3N4 and precursor is calcined at 1100℃ in pure nitrogen atmosphere. XRD results show that the crystalline structure of N-contained solid solution Ca2Si(O4-xNx):Eu2+ is consistent with that of βup -Ca2SiO4 phase. The phosphors can be efficiently excited at a wavelength of 270–400 nm and shows a single intense broadband emission (450–600 nm). Significantly, the red-shift (501 nm to 504 nm) of emission peak occurs and the luminescent intensity is improved significantly with increasing N concentration. With increasing Eu2+ concentration, luminescent intensity of the phosphors increases continuously and reaches a maximum value at the concentration of 0.25 mol% Eu2+. Then the luminescent intensity decreases significantly and the concentration quenching effect appears when Eu2+ concentration is above 0.25 mol%.
Theoretical study of the dissociation of H2+ and the quantum control of dynamic process by an intense laser field
Authors: Yao Hong-Bin  , Zhang Ji  , Peng Min  , Li Wen-Liang  ,   Laboratory of new energy and materials, Xinjiang Institute of Engineering, Urumqi 830091, China
Published: December 2020

The dissociation dynamics of hydrogen molecular ions in intense fields has been investigated by using an accurate three-dimensional (3D) time-dependent wave packet approach. Its dissociation mechanism and intensity dependence can be studied by analyzing the dissociation probability and kinetic energy resolved (KER) spectra of H2+. It is found that the dissociation of H2+ comes from ν=5–9 states at the laser intensity of I1= 5.0×1013 W/cm2. The dissociation process includes bond softening (BS), bond hardening (BH), and below threshold dissociation (BTD). As the laser intensity increases to I2=1.0×1014 W/cm2, the above threshold dissociation (ATD) from ν=3 and 4 states is predominant, and the contributions from the bond softening and bond hardening are reduced during the dissociation process. The above conclusions may provide scientific prediction and theoretical guidance for the experiment in the future.
Low-frequency oscillation of continuous conduction mode buck converter with pulse skipped modulation
Authors: Zhong Shu  , Sha Jin  , Xu Jian-Ping  , Xu Li-Jun  , Zhou Guo-Hua  ,   Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle Ministry of Education, School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

Low-frequency oscillation phenomenon in pulse skipped modulation (PSM) buck converter operating in continuous conduction mode (CCM) is reported in this paper. Energy transfer difference between the PSM-controlled buck converter operating in discontinuous conduction mode (DCM) and that in CCM is studied. The mechanism of low-frequency phenomenon in PSM-controlled CCM buck converter is revealed, and a discrete-time model of PSM-controlled buck converter operating in CCM is established. Based on this model, the border collision bifurcation with variations of the ESR is studied; meanwhile, the inhibition effect of output capacitor equivalent series resistance (ESR) on low-frequency oscillation is presented. Based on the above analysis, a capacitor current pulse skipped modulation (CC-PSM) technology is proposed; the energy transfer principle of CC-PSM controlled buck converter is analyzed. The control pulse of CC-PSM is generated by the comparison between the sampled capacitor current and preset peak reference current, and thus the range of inductor current ripple is limited. Results show that CC-PSM effectively eliminates the low-frequency oscillation in CCM buck converter under classical PSM when the ESR is low. Finally, the experimental results validate the correctness of theory and simulation analysis
Construction of a circulant compressive measurement matrix based on chaotic sequence and RIPless theory
Authors: Guo Jing-Bo  , Wang Ren  ,   State Key Lab, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Construction of a compressive measurement matrix is one of the key technologies of compressive sensing. A circulant matrix corresponds to the discrete convolutions with a high-speed algorithm, which has been widely used in compressive sensing. This paper combines the advantages of chaotic sequence with circulant matrix to propose a circulant compressive measurement matrix based on the chaotic sequence. The elements of a chaotic circulant measurement matrix are generated by taking advantage of the chaotic internal certainty, i.e. the independent identically distributed randomness sequence can be produced by the chaotic mapping formula using the initial value and a certain sampling distance. At the same time, the external randomness of chaotic sequence can satisfy the stochastic requirements of compressive measurement matrix. This paper presents the method of constructing chaotic circulant measurement matrix using a Cat chaotic map and the test method for RIPless property of the matrix. Measurement results of one-dimensional and two-dimensional signals using the chaotic circulant measurement matrix are studied and are compared with the results of conventional circulant measurement matrix. It can be shown that the chaotic circulant measurement matrix has good recovery results for both one-dimensional and two-dimensional signals. Moreover, it may get better results than the traditional matrix for the two-dimensional signal. From the point of view of phase diagram, the essential reason of chaotic circulant measurement matrix outperforms the conventional one is its integration of internal certainty with the external randomness of the chaotic sequence.
Influence of quantum wells on the quantum efficiency of GaAs solar cells
Authors: Ding Mei-Bin  , Lou Chao-Gang  , Wang Qi-Long  , Sun Qiang  ,   School of Electronic Science & Applied Physics, HeFei University of Technology, Hefei 230009, China;,   School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China;,   Tianjin Institute of Power Sources, Tianjin 300384, China
Published: December 2020

Influences of InGaAs/GaAsP quantum wells on the quantum efficiency of GaAs solar cells are investigated. In addion of extending the absorption spectrum from 890 nm to 1000 nm, introduction of quantum wells has important effects on the quantum efficiency below 890 nm. In the range of shorter wavelengths(<680 nm), the GaAs control cells have higher quantum efficiencies, while in the longer wavelengths (680-890 nm), the quantum well solar cells have higher quantum efficiencies. This phenomenon can be explained by the difference in the absorption coefficients of quantum well structure and GaAs materials.
Effect of the structure and the arrangement of organic molecules on the atomic charge and electrostatic interaction
Authors: Zhang Zhao-Hui  , Li Hai-Peng  , Mao Shi-Chun  ,   The basic education department of SuQian College, SuQian 223800, P. R. China;,   College of Science, China University of Mining & Technology, Xuzhou 221008, P. R. China
Published: December 2020

The quantum computation method has been used to investigate the atomic charge and electrostatic interaction of five models: four of which are composed of two mirror-symmetrical long-chain organic molecules (CH3 (CH2)5–R (R=COOH, CH3, OH) and CH3(CH2)4COOH); and one is composed of two parallel CH3 (CH2)5 COOH molecules. Results show that: (1)The charge of the C atoms of the methylenes(–CH2–) in the molecules is different from each other; (2) the atomic charge is mainly determined by the chain-length and the functional group; meanwhile, it may change when the distance between molecules changes or the arrangement of the molecules changes. The atomic charge in the bimolecular models changes more than in the single molecule models; (3)the electrostatic interaction is mainly determined by the tail function groups: the interaction strength is –COOH>–OH>–CH3; while the other atoms have little contribution. Electrostatic interaction will decrease when the atomic charge of the tail functional groups decreases, which is caused by the increased chain-length.
Design and simulation of anodic aluminum oxide nanograting double light trapping structure for thin film silicon solar cells
Authors: Qin Fei-Fei  , Zhang Hai-Ming  , Wang Cai-Xia  , Guo Cong  , Zhang Jing-Jing  ,   School of Science, Tianjin Polytechnic University, Tianjin 300387, China
Published: December 2020

In this paper, we design a type of light trapping structure with an anodic aluminum oxide (AAO) nanograting on the surface and the backside of thin Si solar cells. Simulation of the influence of AAO's period, hole thickness, and duty cycle on thin Si solar cell's short current density are carried out by finite difference time domain method. Simulation results show that the optimum size for surface AAO is 0.5 for duty cycle, 75 nm for thickness, 440nm for period, and the optimum AAO size for rear AAO is 0.75 for duty cycle, 90nm for thickness, 380nm for period. The double AAO light trapping structure can increase the light absorption in the wavelength range from 280 to 1100nm，the absorption relative enhancement is 74.44%.
Effects of γ-radiation on Yb-doped fiber
Authors: Huang Hong-Qi  , Zhao Nan  , Chen Gui  , Liao Lei  , Liu Zi-Jun  , Peng Jing-Gang  , Dai Neng-Li  ,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Yb-doped double-clad fibers are prepared through a conventional modified chemical-vapor deposition technique and solution doping method: each fiber contains a core of around 10 μm in diameter. These fibers are divided into groups under 60Co γ radiations of different doses, and we investigate the fiber absorption spectra and laser spectral properties before and after irradiation. Experimental results show that with increasing the irradiation dose the absorption of the fiber after irradiation increases significantly in the visible region, we believe that the enhancement of optical fiber absorption in the visible region may be due to the color center defects existing already in the fiber (such ODC (Ⅱ)) and the color center defects produced by the irradiation (E'center, POR and Yb2+ions). We also analyze slope efficiencies, bare efficiencies, and transmission characteristics of the fiber before and after laser irradiation. Finally, we use the power-law to fit the radiation-induced losses of the fiber under different radiation doses, and the results obtained in this paper provide a theoretical basis for studying the anti-radiation of optical fibers.
The periodic solution problem of a relative rotation nonlinear system with nonlinear elastic force and generalized damping force
Authors: Li Xiao-Jing  , Yan Jing  , Chen Xuan-Qing  , Cao Yi  ,   College of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, China
Published: December 2020

The periodic solution problem of a relative rotation nonlinear system is considered. Firstly, the relative rotation nonlinear dynamic system is established, which contains nonlinear elastic force, commonly damped force and forcing periodic force. Secondly, the result about the nonexistence of periodic solution of the corresponding autonomous system is obtained, and some results about the existence of periodic solutions of the system are obtained by using the continuation theorem of coincidence degree theory. The significance is that we generalize the existing results of the literature. Finally an example is given to illustrate that our results are right.
Derivation of the probability hypothesis density filter via the physical-space approach
Authors: Zhai Dai-Liang  , Lei Hu-Min  , Li Hai-Ning  , Li Jiong  , Shao Lei  ,   School of Air and Missile Defense, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

In order to well understand the probability hypothesis density, according to the physical-space model given by Ozgur Erdin, we deduce the probability hypothesis density filter function with the Bayes theorem and the total probability theorem. The derivation result is identical to the result in the literature, and the derivation process is described in detail. The results in this paper will provide a theoretical basis for solving the target-death problem.
Tripartite quantum correlations of polar molecules in pendular states
Authors: Li Yan-Jie  , Liu Jin-Ming  ,   State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
Published: December 2020

Cold polar molecules have long coherence time and strong dipole-dipole interaction and thus are regarded as a promising quantum carrier for quantum information processing. In this paper, by employing the pendular states of polar molecules as qubit, we investigate the properties of three types of tripartite quantum correlations for three linear polar molecules and numerically analyze the relations of tripartite negativity, measurement-induced disturbance (MID), and tripartite quantum discord (TQD) to three dimensionless reduced variables that relate to external field strength, dipole moment, rotational constant, dipole-dipole coupling, and temperature. The result shows that if the values of the other parameters are fixed, the three quantum correlations decrease with the increase of the field strength, and the three quantum correlations first increase to their respective maxima and then diminish gradually as the dipole-dipole coupling becomes larger. Moreover, as the temperature increases, both tripartite negativity and TQD become small, but with the variation of temperature there exhibit different evolution tendencies for MID between the influence of the electric field strength and that of the dipole-dipole coupling. In addition, the three quantum correlations of polar molecules in pendular state can be manipulated by tuning the external electric field strength, dipole-dipole coupling, and temperature.
Measurement-device-independent quantum key distribution with odd coherent state
Authors: Dong Chen  , Zhao Shang-Hong  , Zhang Ning  , Dong Yi  , Zhao Wei-Hu  , Liu Yun  ,   School of Information and Navigation, Air Force Engineering University, Xi'an 710077, China;,   Department of Information Security, Xi'an Communication College, Xi'an 710006, China;,   711 Department, Kashi 844000, China
Published: December 2020

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all the detection attacks, thus when it is combined with the decoy state method, the final key is unconditionally safe. In this paper, we propose to perform MDI-QKD with odd coherent state (OCS) and compare the results with weak coherent source scenario. Our simulation indicates that both the secure key rate and transmission distance can be improved evidently with OCS owing to the lower probability of multi-photon events of the OCS. Furthermore, we apply the finite key analysis to the decoy state MDI-QKD with OCS and obtain a practical key rate.
Non-linear control for the fractional boost converter in pseudo continuous conduction mode
Authors: Tan Cheng  , Liang Zhi-Shan  , Zhang Ju-Qiu  ,   College of Geophysics and Information Engineering, China University of Petroleum (Beijing), Beijing 102249, China
Published: December 2020

Based on the fact that the inductor and the capacitor are of fractional order in nature, the mathematical model of the fractional order boost converter in pseudo continuous conduction mode is established by using the fractional order calculus theory. Due to the affine non-linear nature in this mathematical model and a similar Lyapunov stability theorem of the fractional order system, a fractional order non-linear controller is designed. On the basis of chain fractance and the improved Oustaloup algorithm, the circuit model of fractional order inductor and capacitor are built. The fractional order controller is verified by the Matlab/Simulink software. Simulation results show that the controller enhances the dynamic and steady-state performance, so as to realize the stability and achieve good dynamic performance of the fractional order system during large fluctuation of power supply and load disturbance.
Equivalent circuit in function and topology to Chua’s circuit and the design methods of these circuits
Authors: Zhang Xin-Guo  , Sun Hong-Tao  , Zhao Jin-Lan  , Liu Ji-Zhao  , Ma Yi-De  , Han Ting-Wu  ,   Department of Information Engineering, Shandong Foreign Language Vocational College, Rizhao 276826, China;,   School of Information Science and Engineeing, Lanzhou University, Lanzhou 730000, China;,   College of Science, Shandong Univertity of Science and Technology, Qingdao 266590, China
Published: December 2020

The characteristics of classical Chua's circuit variables proposed by Leon O. Chua are the voltage on capacitor, the current in inductor and its normalized equation of state. Based on these characteristics, in this paper, three optimized and scaled circuit design methods are proposed. One is the Chua's circuit with five operational amplifiers used for limiting power amplitude for integration. The other two are Chua's function equivalent circuits with nonlinear diode for cellular neural network system integration. At the same time, an optimized cubic form of Chua's diffeomorphism circuit is given. The methods of designing these circuits are applicable to the cubic random circuits dominated by three broken lines. The universality and practical application of design method are demonstrated in the experiment on chaos secure communication.
Vibration data recovery based on compressed sensing
Authors: Zhang Xin-Peng  , Hu Niao-Qing  , Cheng Zhe  , Zhong Hua  ,   Science and Technology on Integrated Logistics Support Laboratory, College of Mechatronics and Automation, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A missing data recovery method based on compressed sensing is proposed for vibration data of rotating machinery. Firstly, the incomplete signal is transformed into lossy signal by setting the data values corresponding to the time without input as zeros. According to the indices of zero elements in lossy signal, the observation matrix in the frame of compressed sensing is constructed based on identity matrix. Secondly, the dictionary matrix with which the vibration signal can be represented sparsely is chosen or constructed according to the signal needed to be recovered and other prior knowledge. Finally, the original complete signal is recovered based on the lossy signal, observation matrix and dictionary matrix by using an effective and steady pursuit algorithm. The efficiency of the proposed method is validated with simulation data and practical bearing vibration data. Recovery results are discussed by comparing the characteristic values corresponding to the complete signal, lossy signal and recovered signal in time domain and frequency domain. The test results show that the proposed method can well achieve the missing data recovery, and from the view of statistical characteristics, the recovery signal can describe the complete vibration signal more accurately than the lossy signal.
Molecular dynamics simulation of average velocity of lithium iron across the end of carbon nanotube
Authors: Yang Cheng-Bing  , Xie Hui  , Liu Chao  ,   Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education, College of Power Engineering, Chongqing University, Chongqing 400030, China
Published: December 2020

The velocity of lithium iron across the entrance of carbon nanotube VLi is an important factor for the charge performance of lithium iron battery. The molecular dynamics simulation is adopted to evaluate the effects of control factors which include electric strength, functional group type, the diameter of carbon nanotube and temperature. By the L16(45) orthogonal array method, the simulations are carried out. The order of influences of control factors is electric filed intensity > functional group > diameter > temperature. Within the ranges of the control factors studied in this work, VLi increases with increasing the diameter of carbon nanotube and electric field strength. VLi decreases with successively modifying the functional groups at the end of carbon nanotube into -H, -OH, -NH2 and -COOH. With the increasing of temperature, VLi first increases then decreases, but on the whole its change is not big.
Influence of static vacuum on the preparation of cluster of supersonic gas jet
Authors: Wang Long  , Guo Er-Fu  , Han Ji-Feng  , Liu Jian-Bo  , Li Yong-Qing  , Zhou Rong  , Yang Chao-Wen  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;,   Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China;,   Key Laboratory of Radiation Physics and Technology, Ministry of Education, Chengdu 610064, China
Published: December 2020

The influence of static vacuum on the cluster size and density of the supersonic gas jet is studied by Raleigh scattering method. It is found that in a range from 3×10-4 Pa to 9.9×104 Pa, the static vacuum has very little influence on the cluster size and desnity. The self-limiting effect which was found for hydrogen cluster at liquid nitrogen temperature is also found for argon cluster at positions far from the nozzle, and it is found to play an important role in the cluster generation and transporation. The result is very valuable for the construction of the desktop neutron source based on laser fusion method, since the pumps and device to supply the vacuum can be reduced and simplified.
Photon frequency shift based on electro-optic effect
Authors: Zhou Fei  , Cao Yuan  , Yong Hai-Lin  , Peng Cheng-Zhi  , Wang Xiang-Bin  ,   State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics Tsinghua University, Beijing 100084, China;,   National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science, Technology of China, Hefei 230026, China
Published: December 2020

Through the electro-optic modulation on photons with different polarization modes from quantum dot entanglement sources, the way to eliminate the photon frequency difference is analyzed systematically. We design an electro-optic modulation scheme with Pockels cell, to which a rising or falling voltage of 8 V·ns-1 is applied, thereby realizing a photon frequency shift with a bandwidth of 18 MHz. Simply increasing the modulation voltage slope would realize over 1 GHz frequency shift effectively, which provides a practical basis for realizing the future quantum dot entanglement sources with a perfect certainty.
Composite absorber of broadband and high attenuation with spiral frequency selective surfaces
Authors: Xu Yong-Shun  , Bie Shao-Wei  , Jiang Jian-Jun  , Xu Hai-Bing  , Wan Dong  , Zhou Jie  ,   School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

In this paper, a three-layer composite absorber with a split-spiral frequency selective surface layer clamped by two traditional absorber layers, is designed. The 1.4, 1.7 and 2.0 mm thick composites reach, respectively, the bandwidth values of 9.29, 6.69 and 7.11 GHz at a reflectivity lower than the -10 dB level, whose operating bandwidths are increased by 159.5%, 69.3% and 129.4% compared with those of the traditional absorbing sheet without frequency selective surface (under otherwise identical parameters). Further, the paper shows that the thinner composite sheet can have more excellent performance in reflection than the absorb sheets. The split-spiral frequency selective surfaces generated multiple resonance can be used to generate additional absorption band. The simulation results show that the embedded frequency selective surface improves an impedance matching between absorber with the free space, which changes the reflection of the absorbing sheet.