bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation of Laguerre-Gaussian vortex beam
Authors: Ding Pan-Feng  , Pu Ji-Xiong  ,   College of Information Science and Engineering, Huaqiao University,Quanzhou 362021, China
Published: December 2020

For Laguerre Gaussian vortex beam, the analytical expression of the electric field is derived in the observation plane after propagation. Theoretical analysis shows that the definition of Gaussian beam is unsuitable to describing the size of the laguerre Gaussian vortex beam while propagation. It is more convenient that the radius of the point where intensity is maximum is used to define the vortex beam after propagation. Besides the beam broadening effect induced by diffraction, phase distribution exhibits special change in the observation plane. Isophase line changes from radial to arc. If the topological charge of the vortex beam is positive, the isophase line will bend clockwise after propagation; if the topological charge of the vortex beam is negative, the isophase line will bend anticlockwise.
A new method to acquire the half-wave voltage by the quantum bit error rate in the deterministic quantum key distribution system
Authors: Wei Zheng-Jun  , Wan Wei  , Wang Jin-Dong  , Liao Chang-Jun  , Liu Song-Hao  ,   (1)Guangdong Radio&TV University,Guangzhou 510091,China; (2)Laboratory of Photonic Information Technology SIPSE & LQIT, South China Normal University, Guangzhou 510006, China
Published: December 2020

The value of the half-wave voltage of the phase modulator must be measured with high accuracy to reduce the quantum bit error rate (QBER) in a quantum key distribution system based the phase-coding scheme. A new method to measure the half-wave voltage of the phase modulator in an accuracy of 2 mV by adjusting the quantum bit error rate (QBER) of the deterministic quantum key distribution is proposed experimentally to increase the accuracy of the half-wave voltage and reduce the error rate of the quantum key distribution system. The experimental results show that this method can be used to acquire efficiently the half-wave voltage of the phase modulator in a high accuracy which can make the error rate from adding the inaccurate voltage to the phase modulator decrease to the greatest extent.
Nonlinear simulation of a coaxial gyro-amplifier with external electrostatic voltage
Authors: Kong Yan-Yan  , Zhang Shi-Chang  ,   Institute of Photoelectronics, School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

A proposal is presented to enhance the saturation output power of a small-orbit coaxial gyro-amplifier by employing an external electrostatic voltage. Nonlinear simulations show that improved saturation output power increases 19 % for a transverse electric mode at a frequency of 0.14 THz. Both the ratio of the electron-beam transverse velocity to the axial velocity and the spread of transverse velocity do not cause obvious influence on the saturation power. Therefore the performance of gyro-amplifier is effectively improved.
Evolution of Ge/Si quantum dots self-assembledgrown by ion beam sputtering
Authors: Zhang Xue-Gui  , Wang Chong  , Lu Zhi-Quan  , Yang Jie  , Li Liang  , Yang Yu  ,   Institute of Optoelectronic Information Materials,Academy of Engineering and Technology, Yunnan University, Kunming 650091, China
Published: December 2020

A series of Ge quantum dot samples with different Ge thickness is grown on n-Si(100) substrates by ion beam sputtering. Their morphology and structure are characterizated using AFM and Raman spectra, in which the evolution of the morphology, density, dimension, crystalline, and composition of the Ge quantum dots are discussed in detail. The results show that after the growth mode transiting from 2-D to 3-D, the shape of the Ge quantum dot changes directly into a dome shape and no pyramid dots are observed. Besides, with the increase of the Ge deposition, the density of the quantum dots increases to a maximum and then decreases, the crystalline becomes better, but the Ge/Si alloying processing is enhanced and the Ge composition decreases in quantum dots at the same time.
Synthesis and photoluminescence of ZnO and Zn/ZnOnanoparticles prepared by liquid-phase pulsed laser ablation
Authors: Fang He  , Wang Shun-Li  , Li Li-Qun  , Li Pei-Gang  , Liu Ai-Ping  , Tang Wei-Hua  ,   Center for Optoelectronics Materials and Devices, Zhejiang Sci-tech University, Hangzhou 310018, China
Published: December 2020

ZnO nanoparticles and Zn/ZnO core/shell structured nanoparticles are synthesized by ablating zinc target in deionized water and sodium dodecyl sulfate (SDS) solutions, respectively, using pulsed laser ablation with 532 nm pulsed infrared laser. The microstructures and photoluminescence properties of the products are characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible and PL spectrophotometer. The formation mechanism of ZnO and Zn/ZnO nanoparticles is discussed. The results show that the mean diameters of ZnO nanoparticles are 43 nm and 19 nm, respectively, after ablating the zinc target for 2 and 4 hours in deionized water. The longer-time ablation may lead to the interaction of the ablating laser beam with the ZnO nanoparticles, resulting in the decrease of the mean diameter of ZnO. Zn/ZnO core/shell structured nanoparticles can be obtained in 0.005 mol/L SDS solution due to the enwrapping of SDS to the Zn nanoparticles. A blue photoluminescence at about 450 nm (2.76 eV) and a green one at about 558 nm (2.22 eV) are observed for the colloidal solutions of ZnO and Zn/ZnO nanoparticles.
Dislocation climb model based on coupling the diffusion theory ofpoint defects with discrete dislocation dynamics
Authors: Gao Yuan  , Liu Zhan-Li  , Zhao Xue-Chuan  , Zhang Zhao-Hui  , Zhuang Zhuo  , You Xiao-Chuan  ,   Applied Mechanics Laboratory, School of Aerospace, Tsinghua University, Beijing 100084, China
Published: December 2020

Dislocation climb plays a vital role in the plastic behavior of crystals at high temperatures. In order to reveal the intrinsic mechanism of climb and its effect on plasticity, a new dislocation climb model is first developed based on the combination of the diffusion theory with both bulk diffusion and pipe diffusion in a three-dimensional discrete dislocation dynamics (DDD) simulation, which is considered to be more physical and widely applicable. Using our model the shrinkage processes of a single prismatic loop group and prismatic loop group are simulated. It is concluded that the climb rate is not directly determined by mechanical climb force as believed in classical theories, but by the gradient of the vacancy concentration around (bulk diffusion) and along (pipe diffusion) the dislocation line. Loop coarsening process is also simulated, and the three pronounced evolving stages of the loop radii and the average vacancy concentrations in crystal are reproduced.
Degradation and dose rate effects of bipolar linearregulator on ionizing radiation
Authors: Wang Yi-Yuan  , Lu Wu  , Ren Di-Yuan  , Guo Qi  , Yu Xue-Feng  , He Cheng-Fa  , Gao Bo  ,   (1)Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011, China;Xinjiang Key Laboratory of Electronic Information Materials and Devices, Urumqi 830011, China; (2)Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011, China;Xinjiang Key Laboratory of Electronic Information Materials and Devices, Urumqi 830011, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In order to investigate the dose rate effects and the radiation response of the voltage regulator, a group of bipolar linear regulators are irradiated by60Co γ at high and low dose rate. The results show that many of the parameters of the regulator, such as the max drive current, the output voltage, the line regulation and the dropout voltage, are sensitive to ionizing irradiation. Compared the radiation responses of the devices between high and low dose rate, the dose-rate effect is found to be dependent on device. The reasons for the degradation are discussed by combining the radiation response of the transistor and the amplifier with the circuit characteristic of the linear regulator. The dose rate effects are also analyzed from the annealing characteristics. So this is not only useful for their applicalion in space, but also helpful for the design of radiation hardness device.
Phase transition and coalescence behavior of fcc Fe nanoparticles: a molecular dynamics study
Authors: Wang Zhi-Gang  , Wu Liang  , Zhang Yang  , Wen Yu-Hua  ,   (1)College of Physics and Electronic Engineering, Leshan Teachers’ College, Leshan 614004, China;Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005, China; (2)Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005, China
Published: December 2020

In this paper, we present a systematic investigation on phase transition and coalescence behavior of fcc Fe nanoparticles under heating by molecular dynamics approach with Finnis-Sinclair many-body potential. The simulation results show that for fcc Fe nanoparticles, the martensitic transformation from fcc to bcc phase occurs prior to the melting. Relative rotation occurs between two like nanoparticles, but it does not happen in two nanoparticles with different sizes. A small nanoparticle prfers to adhere to a large one and is melted with temperature increasing, resulting in the final formation of a larger particle.
Effect of precipitation on Portevin-Le Chateliereffect in Al-Mg alloys
Authors: Hu Qi  , Zhang Qing-Chuan  , Fu Shi-Hua  , Cao Peng-Tao  , Gong Ming  ,   Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China,Chinese Academy of Sciences, Hefei 230027, China
Published: December 2020

In the alloy with solute content higher than the limiting solubility, the solute atoms failing to dissolve will precipitate from the solid solution and form precipitations. In this study, the Portevin-Le Chatelier (P-LC) effects in annealed 5456 and 5052 aluminum alloys with different precipitation content are investigated under different applied strain rates respectively. The findings suggest that precipitations have a significant effect on the P-LC effect and different precipitation content has different effects. Furthermore, the solute diffusion is pipe diffusion in 5052 alloy with lower precipitation content. However, for 5456 alloy with higher precipitation content, the diffusion is no longer the case but more complex.
Investigation on trap by the gate fringecapacitance in GaN HEMT
Authors: Wang Xin-Hua  , Pang Lei  , Chen Xiao-Juan  , Yuan Ting-Ting  , Luo Wei-Jun  , Zheng Ying-Kui  , Wei Ke  , Liu Xin-Yu  ,   Key Laboratory of Microelectronics Device & Integrated Technology, Institute ofMicroelectronics of Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

The analysis of the frequency dispersion characteristics of the gate-drain capacitance of GaN HEMT indicates that the gate fringe capacitance is responsible for the dispersion difference between the gate-drain capacitance and circle Schottky diode. By fitting the relationship between the additional capacitance of trap and frequency, we discover that the additional capacitance of trap can meet single energy level model only under small gate bias, and meet both single and consecutive energy level model under strong reverse gate bias. The gate fringe capacitance dispersion appears after SiN passivation. It suggests that the trap observed by fringe capacitance is introduced by passivation, which lies in the surface of the ungated region between source and drain. Finally, the low frequency noise technology is used to validate the feasibility of abstracting trap parameter by the gate fringe capacitance. The time constant of single energy level trap obtained by low frequency noise technology is consistent with the result obtained by the gate fringe capacitance under strong reverse gate bias.
Influence of the choice of zero electric potential energy on charge injection in theoretical calculation
Authors: Li Hai-Hong  , Liu Wen  , Liu De-Sheng  ,   (1)Department of Physics and Information Engineering, Jining University, Qufu 273155, China; (2)Department of Physics and Information Engineering, Jining University, Qufu 273155, China;School of Physics, Shandong University, Jinan 250100, China
Published: December 2020

Within the tightly-binding Su-Schrieffer-Heeger (SSH) model and a nonadiabatic dynamic evolution method, we study the influence of the choice of zero electric potential energy on the charge injection in a metal/polymer structure. Through the theoretical calculation, we find that the influence of the choice of zero electric potential energy increases with the electric field strength increasing.
A unified scattering theory model for current noise in nanoscale devices
Authors: Tang Dong-He  , Du Lei  , Wang Ting-Lan  , Chen Hua  , Jia Xiao-Fei  ,   School of Technical Physics, Xidian University, Xi’an 710071, China
Published: December 2020

In the study of the noise characteristics of devices by traditional scattering theory,the incoherent transport and the effect of Coulomb interaction on shot noise are not taken into account, which may not be ignored in real nanoscale devices. Based on the equivalent contact model of the scattering region, we derive a unified scattering theory model for current noise, including the effects mentioned above. Our model covers the whole range of transport regime from coherent transport to incoherent transport. Our model also includes the effects of Pauli exclusion and Coulomb interaction on shot noise. Then, a numerical simulation approach is presented for our model. The approach coincides with the equivalent contact model in the property of the scattering region.
S substituting for P point defect-induced laser damage in KDP crystals
Authors: Wang Kun-Peng  , Yan Shi  ,   National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083,China
Published: December 2020

In this paper, we present the ab initio calculations of S substituting for P point defects (Sp) in KDP crystal. The electronic structure and the relaxing configuration of Sp are studied. The properties of density of states and band structure of KDP with Sp are discussed. The Sp’s in neutral, ±1, and +2 charge states lead to the formation of an isolated SO4 in KDP and no defect state appearing in the energy gap. However, Sp in the -2 charge states induces defect states in the energy gap and therefore laser-induced damage threshold will be reduced.
AC magnetic properties of Fe15.38Co61.52Cu0.6Nb2.5Si11B9nanocrystalline soft magnetic alloy
Authors: Ding Yan-Hong  , Li Ming-Ji  , Yang Bao-He  , Ma Xu  ,   (1)School of Material Science and Engineering, Tianjin University of Technology, Tianjin 300384, China; (2)Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

In this paper, the influence of annealing temperature on AC magnetic property of Fe15.38Co61.52Cu0.6Nb2.5Si11B9 nanocrystalline alloy is investigated, and the possible reasons for better high-frequency soft magnetic properties are analyzed. The resistivity decreases as annealing temperature increases. The value of μ'f0 is not in direct proportion to saturation magnetization Ms because of irregular variation of the gyromagnetic ratio with annealing temperature. At annealing temperature Ta=873 K, the alloy has the largest quality factor and relaxation frequency, i.e., Q(1 MHz)=23.1 and f0=25.02 MHz.
First-principles calculations of electronic structure and magnetism of Ni4NdB
Authors: Li Kai  , Tang Yong-Jian  , Luo Jiang-Shan  , Yi Yong  , Ding Zhi-Jie  ,   (1)Research Center of Laser Fusion of CAEP, Sichuan Mianyang 621900, China; (2)State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Mianyang 621010, China;Research Center of Laser Fusion of CAEP, Sichuan Mianyang 621900, China
Published: December 2020

The geometry optimization, the electronic and magnetic properties of the compound Ni4NdB are studied by using first-principles within the local spin-density approximation (LSDA) and the LSDA+U approximation. The results indicate that the system is a metallic conductor with very small band gap, and that the total magnetic moment is provided by the local Nd magnetic moment. The system has very complex bonding, where Nd atoms and the neighboring Ni atoms form metal bonding, also Nd atoms and the neighboring B atoms form the strong ionic banding, besides Ni atoms and the neighboring Ni atoms forming an indirect exchange interaction. Under coulomb interaction, the system magnetic moment is consistent with that of the local Nd atom, and the collapse of magnetic ordering in 2.75 eV happens to the local Ni magnetic moment.
Study on thermochromic properties of VO2/ZnO nanocrystalline composite films
Authors: Li Yi  , Zhu Hui-Qun  , Zhou Sheng  , Huang Yi-Ze  , Tong Guo-Xiang  , Sun Ruo-Xi  , Zhang Yu-Ming  , Zheng Qiu-Xin  , Li Liu  , Shen Yu-Jian  , Fang Bao-Ying  ,   College of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   College of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;School of Applied Physics and Materials, Wuyi University, Jiangmen Guangdong 529020, China;,   College of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;Shanghai Key Laboratory of Modern Optical System, Shanghai 200093, China
Published: December 2020

Based on thermo-optical phase transition effect, VO2/ZnO nanostructure composite films are designed and successfully prepared by depositing ZnO films with high (002) orientation on soda-lime glass substrates first, and then the vanadium dioxide films are fabricated by depositing vanadium metal films on ZnO films at room temperature and thermal oxidation treatment. The thermochromic properties of VO2/ZnO nanocomposite films are measured and compared with the single-layer VO2 films on SiO2 glass substrates with the same thickness. The lattice distortion and bonding state of the VO2/ZnO nanocomposite films before and after phase transition are observed and analyzed by Raman spectroscopy at the different temperatures. The relations of infrared switching properties and phase transition temperature to nanostructure and film thickness are discussed. The results show that the thermochromic optical properties are improved significantly. VO2/ZnO nano-composite films have high (002) orientation so that the infrared transmittance before phase transition is more than twice as large as that after phase transition, and the width of thermal hysteresis is narrowed by about 5℃ and phase transition temperature is decreased about 8℃. It suggestes that the nano-composite films can significantly reduce the phase transition temperature and enhance the infrared light switch modulation capabilities of VO2 thin films.
Preparation and property of super-hydrophilic SiO2-TiO2 nano-particle layer
Authors: Ma Hai-Min  , Hong Liang  , Yin Yi  , Xu Jian  , Ye Hui  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 300127,China
Published: December 2020

TiO2 particle single layer and SiO2-TiO2 particle double layers on glass substrate are obtained by self-assembly technique. For SiO2-TiO2 particle double layers, SiO2 Particle layer is made by spin-coating with SiO2 particles closely packed,while TiO2 Particle layer is obtained through layer-by-layer method in both cases of TiO2 particle single layer and SiO2-TiO2 particle double layers, with TiO2 particles non- closely packed. The theoretical roughness of TiO2 particle single layer and SiO2-TiO2 particle double layers are analyzed. Microstructures of these two coatings are studied with scanning electron microscope. Water contact angles before and after exposure to UV light are measured by drop meter separately. Light catalytic ability of organics degradation is determined by spectrophotometer. The experimental results show that the water contact angles of the as-prepared particle films increase if these coatings are stored in dark for days till the contacts become stable, while if exposed to UV light, they become super-hydrophilic with contact angles approaching 0°,that the roughness greatly affects water contact angle, and that the catalytic ability of SiO2-TiO2 particle double layers is superior to TiO2 particle single layer.
The mechanism of directional cellular growth with shear flow
Authors: Wang Jian-Yuan  , Zhai Wei  , Jin Ke-Xin  , Chen Chang-Le  ,   School of Science, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The directional cellular growth of SCN-0.2%Salol transparent alloy in the presence of shear flow at the liquid-solid interface is in-situ observed, and the cellular spacing adjusting mechanism is carefully investigated. It is found that the cellular array deflects forward the incoming flow direction, and the stable cellular spacing decreases with the increase of the flow rate. This is due mainly to the reducing destabilization wavelength caused by shear flow. Instead of the double symmetric splitting mode under static condition, the splitting mechanism of cellular growth exhibits multiplicity, which is characterized mainly by (i) multi-splitting and asymmetric splitting, and (ii) secondary branches appearing on the upstream side whose growth direction subsequently shifts to ward the direction paralleled to the trunk to form new cells. Meanwhile, the selected mechanism transits from the weak cells eliminated by the relatively strong ones on both sides during static solidification to the growth of weak cells on the downstream side suppressed by the stronger cells at the upstream side when shear flow is applied.
Se ultrathin film growth on Si(100) substrate and its application in Ti/n-Si(100) ohmic contact
Authors: Pan Shu-Wan  , Qi Dong-Feng  , Chen Song-Yan  , Li Cheng  , Huang Wei  , Lai Hong-Kai  ,   Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China
Published: December 2020

We have investigated the growth of thin selenium layer on Si (100) substrate by molecular beam epitaxy (MBE). By controlling the temperatures of the silicon substrate and the selenium source during growth, an ultrathin film of Se is successfully grown on the Si (100) substrate. As the Si (100) surface is passivated by the ultrathin film of Se, the electrical property of the Ti/n-Si (100) contact is shown to be ideally ohmic, with low resistance and relatively high thermal stability.
Molecular alignment of nano-thin film using Raman spectroscopy
Authors: Zhang Hong-Yu  , Zhang Shao-Hua  , Liang He  , Liu Yu-Hong  , Luo Jian-Bin  ,   State Key Laboratory of Tribology,Department of Precision Instruments and Mechanology, Tsinghua University,Beijing 100084,China
Published: December 2020

Molecular alignment of nano-thin liquid crystal 5CB film confined between highly polished steel ball and quartz disk under shear is studied using Raman spectroscopy. The results show that an acceptable signal-to-noise ratio as high as 20:1 can be obtained under certain experimental conditions. In addition, the intensity of the Raman spectrum reaches its peak (minimum) value when polarization of the laser is parallel (perpendicular) to the direction of shear motion. This indicates that the molecules of liquid crystal 5CB film are oriented along the direction of shear motion. Furthermore, the influence of shear speed on the intensity of Raman spectroscopy of nano-thin liquid crystal 5CB film was investigated, and its film thickness was analyzed based on a relative optical interference intensity technique.
Fabrication and characterization of Bi-Sb-Te based thin film thermoelectric generator prepared by ion beam sputtering deposition
Authors: Fan Ping  , Cai Zhao-Kun  , Zheng Zhuang-Hao  , Zhang Dong-Ping  , Cai Xing-Min  , Chen Tian-Bao  ,   College of Physical Science and Technology, Institute of Thin Film Physics and Applications, Shenzhen key laboratory of sensor technology, Shenzhen University, Shemzhen 518060, China
Published: December 2020

In this paper, N-type Bi2Te3 and p-type Sb2Te3 thermoelectric thin films are deposited by ion beam sputtering with Bi/Te and Sb/Te binary compound target. Sb2Te3 thin films and Bi2Te3 thin films are annealed at different annealing temperatures for 1 h and their thermoelectric properties are characterized. When the annealing temperature is 150 ℃, both the Seebeck coefficient and power factor of the Bi2Te3 thin films have maximal values of -148 μVK-1 and 0.893×10-3 Wm-1K-2 respectively. Sb2Te3 thermoelectric thin film has a seebeck coefficient of 117 μVK-1 and a maximal power factor of 0.797×10-3 Wm-1K-2 when the annealing temperature is 200 ℃. Therefore, Sb2Te3 thin films at the annealing temperature of 200 oC and Bi2Te3 thin films at the annealing temperature of 150 ℃ are selected to fabricate the single thin film thermoelectric generation. When the temperature difference between the cold side and the heat side is 50K, the output voltage of the single thin film thermoelectric generation is 15.26 mV and the maximal output power is 0.129 μW.
Threshold voltage degradation mechanism of SOI SONOS EEPROM under total-dose irradiation
Authors: Yu Zong-Guang  , Xiao Zhi-Qiang  , Zhou Xin-Jie  , Li Lei-Lei  ,   School of Electronic Science and Engineering, South-East University, Nanjing 210096, China;,   School of Microelectronics, Xidian University, Xi’an 710071, China;The 58th Research Institute of China Electronics Technology Group Corporation,Wuxi 214035, China;,   State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China;The 58th Research Institute of China Electronics Technology Group Corporation,Wuxi 214035, China
Published: December 2020

Threshold voltage drift is one of the most important characteristics of device degradation. Based on the research of threshold drifts of the front and the back gate of SOI SONOS EEPROM, device degradation is studied in irradiation environment. Physical mechanism of threshold drifts is analyzed through physical band and mobile carrier analysis. And measures to improve device performance are proposed.
Switching behavior of logic circuits by magnetic quantum cellular automata
Authors: Cai Li  , Zhao Xiao-Hui  , Yang Xiao-Kuo  , Bai Peng  , Feng Chao-Wen  , Zhang Li-Sen  , Kang Qiang  ,   (1)College of Science, Air Force Engineering University, Xi’an, Shaanxi 710051, China; (2)Department of Science Research, Air Force Engineering University, Xi’an 710051, China; (3)Research Center of synthetic Electronic Information System, Air Force Engineering University, Xi’an 710051, China
Published: December 2020

In this paper, switching behaviors of MQCA inverter and majority logic gate with various nanomagnet thicknesses and spacings are studied. Single domain approximation Landau-Lifshitz-Gilbert equation is employed to model and simulate the circuits. It is shown that thicker nanomagnet needs larger switching magnetic pulse and logic circuits comprised of thicker nanomagnet demonstrate slower switching; majority logic gate needs more time to switch than inverter when they have the same nanomagnet thicknesses and spacings. Moreover, it is also shown that nanomagnet spacing has a larger effect on switching behavior of inverter than on majority logic gate.
Action potential initial dynamical control and analysis of a minimum neuron model
Authors: Jin Qi-Tao  , Wang Jiang  , Wei Xi-Le  , Deng Bin  , Che Yan-Qiu  ,   School of Electrical and Automation Eng., Tianjin University, Tianjin 300072, China
Published: December 2020

Neuron is a basic unit of information transmission in the nervous system . Neuron encodes the information input from the dendrites by generating action potential sequences of different firing patterns. The different firing patterns result from different action potential initial dynamic mechanisms for neurons to generate spikes. The result of competition between neuron ion currents with different dynamic features in the sub threshold potential determines the action potential initial dynamic mechanism. In this paper, we adopt a minimum neuron model to design the wash-out filter from a physiological view for achieving the transition between different action potential initial dynamic mechanisms and for verifying that the wash-out filter control changes the action potential initial dynamic mechanism of neuron by affecting the result of competition between currents with different dynamic features in the sub-threshold potential.
A broadband low loss and high birefringence terahertz photonic bandgap photonic crystal fiber
Authors: Bai Jin-Jun  , Wang Chang-Hui  , Huo Bing-Zhong  , Wang Xiang-Hui  , Chang Sheng-Jiang  ,   Institute of Modern Optics, Nankai University, Tianjin 300071, China
Published: December 2020

A low loss and broadband photonic bandgap (PBG) terahertz photonic crystal fiber (PCF) with high birefingence is proposed. Terahertz wave is confined within the core surrounded by the cladding with triangular lattice arrangement of subwavelength air holes. The birefringence and the loss of the fiber are investigated by using a full-vectorial finite element method. The numercal simulation shows that within a broadband area of about 0.3THz, the loss of the near-rectangle core THz PBG photonic crystal fiber is less than 0.009cm-1, the phase birefringence is on the order of 10-3, and the group birefringence even can reach 10-2.
A new method to deal with biomacromolecularimage observed by atomic force microscopy
Authors: Ji Chao  , Zhang Ling-Yun  , Dou Shuo-Xing  , Wang Peng-Ye  ,   Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In this paper, we develop a new method to eliminate the background noise in the image of biomacromolecule with complex conformation in order to obtain highly effective and accurately quantitative information. By using this algorithm, we are able to deal with the atomic force microscopic imags of both linear DNA and branch DNA. Furthermore, our method can be extended to the study of the images in the other field.
Theoretical analysis and experimental study of optical loss of metal contacts of crystalline silicon solar cells
Authors: Song Yang  , Gao Zhi-Hua  , Li Tao  , Yang Hai-Feng  , Zhou Chun-Lan  , Liu Zhen-Gang  , Wang Wen-Jing  , Duan Ye  , Li You-Zhong  ,   (1)Chinalight Solar Co. Ltd., Beijing 101111, China; (2)Chinese Academy of Inspection and Quarantine, Beijing 100123, China; (3)The Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, CAS, Beijing 100190, China
Published: December 2020

One main factor of restricting industrial crystalline solar cell efficiency is the optical losses caused by the metal front side contacts, including the absorption loss and reflection loss. Based on screen-printed and screen-printed seed layers thickened by light-induced electroplating solar cells, in this paper various cases of optical losses due to the metal contacts are analyzed. Taking into account the reflections in the air-glass interface and the edge regions of metal contacts, the optical losses are simulated by assuming approximately half-oval cross-section of metal contacts. The results show that the effective width ratio is about 40% of the metal contact geometry width. By measuring and calculating the reflection spectra of different types of samples, the optical losses of the metal front side contacts of solar cells are obtained in theoretical simulation and experimental measurement. The corresponding theory and the experimental results are in good agreement with each other.
Tests and analysis of digital filter weak constrain in data assimilation
Authors: Li Yi  , Cao Xiao-Qun  , Wang Shu-Chang  , Zhang Wei-Min  , Zhao Jun  ,   (1)Institute of Meteorology, People’s Liberation Army University of Science and Technology, Nanjing 211101, China; (2)School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Variational data assimilation is an advanced technique to provide correct and high quality initial fields for the numerical model. Digital filter is not restricted to initialization; it may also be implemented as a weak constraint penalizing the analysis towards a balanced state in a preoperational 4D-Var system. The constraint is imposed only on the analysis increments to damp spurious fast oscillations associated with gravity–inertia waves. The influence of DFI as a weak constraint on 4D-Var forecast is assessed by assimilation experiments with the recently occurring severe snow weather. It is shown that the weak constraint imposed only on the increments manages to control efficiently the emergence of fast oscillations in the resulting forecast while maintaining a closer fitting to the observations.
Spatiotemporal analysis of information entropy of the global temperature
Authors: Wang Qi-Guang  , Feng Ai-Xia  , Gong Zhi-Qiang  , Huang Yan  ,   (1)Department of Atmospheric and Sciences Lanzhou University, Lanzhou 730000, China; (2)Department of Atmospheric and Sciences Lanzhou University, Lanzhou 730000, China;Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China; (3)Institute of Climate System, Chinese Academy of Meteorological Science, Beijing 100081, China; (4)Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, Chi
Published: December 2020

Based on the concept of entropy in information theory, the entropy of meteorological elements is determined and used to analyze the uncertainty of the global temperature field anomaly from the climate state (1971—2000) on different time and spatial scales. It is found that the temperature climate entropy (CE) possesses a zonal distribution, increases from tropics to mid-high latitudes and has an obvious difference between the ocean region and the continent, thereby being able to distinguish the climatic zones properly. The temperature CE in low-mid troposphere increases with altitude increasing, while in extratropical the situation retains above 300 hPa but below 300 hPa the situation is reversed, and this feature is more obvious in high latituderegions. On the whole, the temperature monthly entropy (ME) is obviously dependent on season change: it is smallest in summer and largest in winter. Besides, there exists a distinguishable interdecadal period. Different monthly ME values from low atmosphere to high atmosphere each have an obvious five -to-ten year quasi-period oscillation. All the spatiotemporal characteristics and their relationships with annual temperature range verify the usefulness of the entropy in meteorology, and it is an effective method to measure the uncertainty of the meteorological elements.
Layered optimization algorithm about a kind of nonlinear partial differential equation with initial-boundary value problem
Authors: Hou Xiang-Lin  , Zhai Zhong-Hai  , Zheng Li  , Liu Tie-Lin  ,   Shenyang Jianzhu University, School of Science, Shenyang 110168;,   Shenyang Jianzhu University, School of Civil Engineering, Shenyang 110168, China
Published: December 2020

For non-linear partial differential equations with initial-boundary value problems, based on the difference method and the optimization method with dynamic design variables, using unknown function values on discrete node points on time layer as design variables, the difference equations sets of all the discrete node points are constructed as stylized objective function. A layered accurate optimization algorithm about computing unknown function value on discrete node point is proposed. Universal computing program is designed, and practical examples are analyzed. Through comparing computation results with exact results, the effectiveness and the feasibility of proposed method are verified. The method can provide the condition for engineering application.
Collective excitations of superfluid Fermi gas in an anharmonic potential
Authors: Yu Zi-Fa  , Wu Jian-Peng  , Wang Peng-Cheng  , Zhang Jiao-Jiao  , Tang Rong-An  , Xue Ju-Kui  ,   Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Published: December 2020

The collective excitations of a one-dimensional superfluid Fermi gas in an anharmonic trap are investigated. By using the variational approach, the frequency shifts about the dipole mode of the center-of-mass variations and the breathing mode of width variations are derived. It is found that the frequency shift in a unitary region is more significant. Under the excitations of different driving amplitudes, the two low-energy modes are coupled due to the contribution of the quartic item, and the quantum beating phenomenon comes into being. The frequency of beating increases with the driving amplitude. The dynamics of the width exhibits complex characteristics, especially, in the unitary region.
Short-term traffic flow prediction for multi traffic states on urban expressway network
Authors: Dong Chun-Jiao  , Shao Chun-Fu  , Zhuge Cheng-Xiang  ,   Key Laboratory for Urban Transportation Complex Systems Theory and Technology of Ministry of Education,linebreak Beijing Jiaotong University, Beijing 100044, China;,   Center for Transportation Research, University of Tennessee, Tennessee 37996, USA
Published: December 2020

Short-term traffic flow prediction for multi traffic states on urban expressway network is carried out in this paper. The model for multi traffic states is proposed by integrating the spatial and the temporal distribution characteristics of traffic flow parameters under free traffic, congested traffic and jam traffic respectively. Based on the classical traffic flow conservation equation, the ideology of spatial and temporal dispersions in partial differential equations is adopted to establish short-time traffic flow prediction model. Meanwhile, the impact factors, such as on and off ramp, lane change and road slope are considered, which convertes short-term traffic flow prediction model into short-time traffic flow prediction state space model. Finally, the short-term traffic flow prediction for multi traffic states on urban expressway network is realized. The empirical research shows that compared with the classic ARMA model, the proposed method can not only realize short-term traffic flow prediction for multi traffic states on urban expressway network but also achieve an accuracy of 90.23%. In the same condition, the accuracy of ARMA model is 81%.
Colored noise induced switch in the gene transcriptional regulatory system
Authors: Wang Can-Jun  ,   Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721007, China
Published: December 2020

The colored noise induced switch in the gene transcriptional regulatory system is investigated. The approximate Fokker-Planck equation is obtained based on the Novikov theorem and the Fox approach. The explicit expressions of the steady state probability distribution, the mean value, and the mean first passage time are derived. After the numerical computations, these results show that the TF-A monomer concentration switches from the off position to the on position with the self-correlation time of the multiplicative noise increasing. The TF-A monomer concentration switches from the on position to the off position with the self-correlation time of the additive noise increasing. With the two kinds of the self-correlation time increasing, the mean first passage time becomes large, namely, the TF-A monomer concentration switch becomes difficult. The theoretical predictions are found to be in basic agreement with numerical results.
Continuous-variable three-color tripartite entangled state generated by a non-degenerate optical parameter oscillator
Authors: Yan Zhi-Hui  , Jia Xiao-Jun  , Xie Chang-De  , Peng Kun-Chi  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
Published: December 2020

The quantum correlations between the output signal, the output idler and the reflected pump fields generated by non-degenerate optical parametric oscillator operating above the oscillation threshold are theoretically calculated with the semi-classical formulae. According to the multipartite entanglement criteria for the continuous variables, proposed by P. van Loock and A. Furusawa, the calculated results prove the existence of the quantum correlations between the amplitude and the phase quadrature for the three optical fields, i. e. they form a tripartite entangled state. We numerically calculate the dependence of the entanglement on the physical parameters of the optical oscillator and find the optimum operating conditions of the oscillator to produce the three-color tripartite entangled state, which provide the direct references for the design of the continuous variable multipartite entanglement generation systems.
Doppler cooling of a trapped ion with feedback
Authors: Jiang Zhi  , Chen Ping-Xing  ,   College of Science, National University of Defense Technology, Changsha 410072, China
Published: December 2020

Basing on the theory of quantum feedback by Steixner and his coworkers, we develop the master equation of Doppler cooling with feedback in an ion trap. The result of simulation shows the property of speedup the cooling,besides the influences of those arguments and whether we could realize it in experiment.
Experimental and theoretical analysis of the dispersion of laser-induced surface acoustic wave due to surface roughness
Authors: Yuan Ling  , Sun Kai-Hua  , Cui Yi-Ping  , Shen Zhong-Hua  , Ni Xiao-Wu  ,   Department of Electronic Science and Engineering, Southeast University, Nanjing 210096, China;,   Department of Information Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

In the process of producing materials, the surface roughness always exists. And it can change the velocity of surface acoustic wave (SAW) which propagates in the material. To assess the properties of materials by laser induced SAW, an inverse method based on the wide-band velocity dispersion characteristic of laser-induced SAW is most commonly used. To study whether the surface roughness can be one of the inversion characteristic parameters, an experimental apparatus is constructed in this article. In the apparatus, the SAW is induced in the surface roughness sample by laser, and it is received by a polyvinylidene fluoride transducer with wide frequency band. Using this apparatus, we study the influences of different surface roughnesses on SAW velocity. In the paper a physical model of laser-induced SAW propagating in roughness surface is established theoretically. The time domain characteristic of SAW is obtained by the finite element method, and then the velocity dispersion curve of SAW is achieved. It is concluded that the theoretical result and the experimental result are in good agreement with each other. The studies in this article form theoretical and experimental bases for assessing surface roughness by means of laser-induced SAW technique.
Generation of 190 fs optical pulses from a mode-locked Yb, Na: CaF2 laser
Authors: Ge Wen-Qi  , Chai Lu  , Hu Ming-Lie  , Wang Qing-Yue  , Su Liang-Bi  , Li Hong-Jun  , Zheng Li-He  , Xu Jun  ,   School of Precision Instruments and Optoelectronics Engineering, Key Laboratory of Opto-Electronic Information Technology of Ministry of Education, Tianjin University, Tianjin 300072, China;,   Key Laboratory of Transparent Opto-functional Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), Shanghai 200050, China
Published: December 2020

In the paper, the demonstration of a high-power LD-pumped Yb, Na:CaF2 femtosecond laser is presented, which the cavity is optimized concerning the numerical simulation for the thermal lens effect. With a 2% output coupler, a continuous-wave mode-locked pulse train with a pulsewidth of 190 fs, the average output power of 503 mW, the center wavelength at 1034 nm and a repetition frequency of 82.4 MHz is obtained under the absorbed pump power of 7.8 W. If other forms of output are recorded, such as the reflection of the crystal surface, the total output power is 905 mW.
Fabrication and spectra-measurement of high Q photonic crystal cavity on silicon slabs
Authors: Zhou Chang-Zhu  , Wang Chen  , Li Zhi-Yuan  ,   Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We fabricate a high Q photonic crystal cavity on the top of SOI (silicon on insulator) with EBL (electron beam lithography) and ICP (inductively coupled plasma). The value of Q can reach 7 104. It provides basic condition for the following experiments, for example for the study of interaction between light and substance. The high Q cavity also provides good circumstance for the quantum information. The theoretical result of the value of Q is 1.2105 from FDTD (finite difference time domain) simulation.
A vibration detection system based on two-stage polarization maintaining fiber Sagnac loop fiber laser
Authors: Zhou Rui  , Zhang Jing  , Hu Man-Li  , Feng Zhong-Yao  , Gao Hong  , Yang Yang  , Zhang Jing-Hua  , Qiao Xue-Guang  ,   Department of Physies, Northwest University, Xi'an 710069, China;,   Ministry of Education Key Laboratory of Photoelectricity Gas-oil Logging and Detecting, Xi'an Shiyou University, Xi'an 710065, China
Published: December 2020

A novel fiber grating sensing technique utilized for vibration detection is proposed and experimentally demonstrated. A single wavelength laser is formed by polarization controllers and polarization maintaining fiber (PMF) to construct the high birefringence (Hi-Bi) Sagnac loop, PMF combined with erbium-doped fiber, single mode fiber and polarizer. The cantilever glued to an FBG is used as a sensor probe, and the linear edge of Sagnac ring laser are used to demodulate fiber optic seismic vibration signal. Sagnac ring theory and its edge effects are described in detail, and numerical simulation and experiment show that the vibration signal detection system is adjusted periodically in a range from L1 to L1 + L2, sensitivity goes up to 38.2 W/nm of discrimination, the linearity is 0.9996, and the dynamic range is 4070 dB, these meeting the requirements for vibration detection technical parameters.
Review on forced convection heat transfer in porous media
Authors: Zheng Kun-Can  , Wen Zhi  , Wang Zhan-Sheng  , Lou Guo-Feng  , Liu Xun-Liang  , Wu Wen-Fei  ,   School of Mechanic Engineering, University of Scitech of Beijing, Beijing 100083, China;,   School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China;,   Baotou Beifang Chuangye co., ltd, Baotou 014010, China
Published: December 2020

Forced convection heat transfer in porous medium is involved mainly with the seepage, convection heat transfer, thermal dispersion and thermal radiation. Their research statuses and development trends are reviewed in this paper. The primary theoretical models, experimental research and empirical correlations were systemized and their features, application range and limitation were summarized too. Furthermore, the future research area and the difficulty are presented on the convection heat transfer of porous medium according to the comparative analysis of the past research results. In addition, when the radiation heat transfer can be considered in the cooling process of high temperature porous medium is determined by the simplifing calculation. All of these will be helpful to the theoretic research and engineering application of the porous medium.