bluuebunny/crossref_metadata_2025 huggingface dataset:
HPHT synthesis and magnetic property of -Fe2O3@C core-shell nanorods
Authors: Zhang Song-Bo  , Wang Fang-Biao  , Li Fa-Ming  , Wen Ge-Hui  ,   State Key Laboratory of Superhard Materials, Jilin University, Jilin 130012, China
Published: December 2020

-Fe2O3@C core-shell nanorods with average diameter of 20 nm and length of 150 nm are synthesized by transforming FeOOH@PVA nanorods under the condition of high pressure and high temperature (HPHT). The FeOOH@PVA nanorods are prepared via a hydrothermal route. The best synthesis condition for transforming FeOOH@PVA core-shell nanorods into -Fe2O3@C nanorods is 400 ℃ under 1 GPa. Owing to high aspect ratios, the -Fe2O3@C nanorods present a high coercivity of 330 Oe (10 Oe=79.5775 A/m). The possible mechanism for the synthesis of -Fe2O3@C nanorods is also discussed. The HTHP method can provide a new way for preparing of one-dimensional core-shell nanostructures.
Generalized gradient representation of holonomic mechanical systems
Authors: Ge Wei-Kuan  , Xue Yun  , Lou Zhi-Mei  ,   Department of Physics, Huzhou Teachers College, Huzhou 313000, China;,   School of Mechanical and Automation Engineering, Shanghai Institute of Technology, Shanghai 200235, China;,   Department of Physics, Shaoxing University, Shaoxing 312000, China
Published: December 2020

A gradient system is generalized to a system in which the time appears in the potential function, and the system is called generalized gradient system. The condition under which a holonomic mechanical system can be considered as a generalized gradient system is given. If the potential function of the system can be considered as a Lyapunov function, then the Lyapunov theorems can be used to study the stability of the system.
Approximate solution of solitary wave for nonlinear-disturbed time delay long-wave system
Authors: Wang Wei-Gang  , Lin Wan-Tao  , Shi Lan-Fang  , Mo Jia-Qi  ,   Tongcheng Teaching Department, Anqing Teacher's College, Tongcheng 231402, China;,   State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamic, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;,   College of Mathematics and Statistics, Nanjing University of information Science and Technology, Nanjing 210044, China;,   Department of Mathematics, Anhuii Normal University, Wuhu 241003, China
Published: December 2020

The solitary wave approximate solutions for a class of nonlinear-disturbed time delay long-wave system are considered. First, we introduce into exact solution of a non-disturbed typical long-wave system. Then, by using the homotopic mapping and an improved technique, the approximate expansions of the traveling wave solutions for the nonlinear-disturbed time delay long-wave systems are constructed.
Binomial theorems related to two-variable Hermite polynomials and its application in quantum optics
Authors: Fan Hong-Yi  , Lou Sen-Yue  , Pan Xiao-Yin  , Da Cheng  ,   Department of Physics, Ningbo University, Ningbo 315211, China;,   Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

We propose an operator Hermite polynomial method, namely, to replace the special functions' argument by quantum mechanical operator, and in this way we have derived two binomial theorems related to two-variable Hermite polynomials. This method is concise and may be of help in deducing many operator identities, which may become a new branch in mathematical physics theory.
Quantum teleportation in an XXZ spin chain system with three-site interaction
Authors: Xi Yu-Xing  , Shan Chuan-Jia  , Huang Yan-Xia  ,   College of Physics and Electronic Science, Hubei Normal University, Huangshi 435002, China
Published: December 2020

In this paper, we study carefully the quantum teleportation by means of a channel of a three-qubit Heisenberg XXZ ring, and calculate the fidelity of quantum teleportation. Comparing the four XXZ models: one without three-site interaction, one with XZX +YZY type three-site interaction, one with XZY-YZX type three-site interaction, one with both the two kinds of the three-site interaction, we find some ideal models by which the teleportation only needs a weakest magnetic field and a highest temperature to work successfully. The result could provide a theoretical basis for later experiments.
Temporal-asymmetric fractional Langevin-like ratchet
Authors: Zhou Xing-Wang  , Lin Li-Feng  , Ma Hong  , Luo Mao-Kang  ,   College of Mathematics, Sichuan University, Chengdu 610064, China;,   College of Computer and Information, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Published: December 2020

In this paper, a temporal-asymmetric fractional Langevin-like ratchet is constructed for the operation of a 1D linear molecular motor subjected to both spatial-symmetric periodic potential and temporal-asymmetric unbiased Langevin-like noise. In this ratchet, the Langevin-like noise is used to simulate the intracellular fluctuation induced by ATP hydrolysis. Then, for numerical study of this ratchet, the corresponding discrete mapping is derivated. Finally, as an example, the unidirectional transport of the ratchet driven by unbiased Langevin-like noise, generated by the Logistic mapping, is numerically studied. Negative transport of the ratchet indicates that without the spatial asymmetry of potential, the temporal asymmetry is enough for the presence of unidirectional transport. Since temporal asymmetry has to be regarded as a generic property of nonequilibrium system, this ratchet is expected to be resonably used for the operation of molecular motor.
Suppression of chaos and basin erosion in a nonlinear relative rotation system by delayed position feedback
Authors: Shang Hui-Lin  , Han Yuan-Bo  , Li Wei-Yang  ,   School of Mechanical Engineering, Shanghai Institute of Technology, Shanghai 200235, China
Published: December 2020

A typical relative rotation system is considered whose chaotic motion and basin erosion caused by external excitation is investigated in this paper. And a delayed position feedback control is applied in the system for suppressing the two types of complex dynamical behaviors. Firstly, the excitation amplitude threshold of chaotic motion and the basin erosion of an uncontrolled relative rotation system is obtained by the Melnikov method. Secondly, the condition of Hopf bifurcation of a delay controlled system is discussed so as to obtain the available ranges of control parameters in the Melnikov method. Then the necessary condition for the global bifurcation of a delay controlled system is obtained. Finally, the evolutions of the dynamical behavior of the delay controlled system together with its control parameters are presented numerically using the 4th Runge-Kutta method and the point-to-point mapping method, which confirm the validity of the theoretical prediction. It is found that the chaotic motion and basin erosion can be suppressed effectively by delayed position feedback control when the gain is positive and the time delay is short.
Study on stochastic perturbation strong tracking particle filter
Authors: Zhang Qi  , Qiao Yu-Kun  , Kong Xiang-Yu  , Si Xiao-Sheng  ,   The Second Artillery Engineering University, 302 Unit, Xi'an 710025, China;,   The Engineering University of Armed Police Force, Information Engineering Department, Xi'an 710078, China
Published: December 2020

To solve the degeneracy phenomenon and to improve the ability for tracking the breaking states are two difficult problems in the application of particle filter. Sequential important re-sampling can reduce orilliminate degeneracy, but the sample impoverishment is a secondary result. Extended particle filter can also reduce the degeneracy, but it cannot track the breaking states. The ability to track the breaking states can be improved by a strong tracking particle filter, but the degeneracy phenomenon will not be well solved still. A stochastic perturbation strong tracking particle filter is proposed for solving the above problems, in which a stochastically perturbative re-sampling is introduced into a strong tracking particle filter. Thus a stochastic perturbation is added to the particle with maximal weight to form some new particles, and the degenerative particles are displaced by the new particles to solve the degeneracy phenomenon and so the sample impoverishment improves the diversity of the samples. The ability of the proposed algorithm to track breaking states is also improved, and the feasibility and validity of the proposed algorithm are demonstrated by the simulation results of the standard validation model and the system with constants in different periods of time.
Nonlinear dynamics of stochastic resonance and its application in the method of weak signal detection
Authors: Fan Jian  , Zhao Wen-Li  , Zhang Ming-Lu  , Tan Run-Hua  , Wang Wan-Qiang  ,   School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, China;,   School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China;,   Department of Mechanical & Electrical Engineering, Taizhou University, Taizhou 318000, China
Published: December 2020

According to the exited stochastic resonance theory, we cannot obtain the dynamic behavior of a stochastic resonance (SR) system intuitively. In order to reveal the dynamic mechanism of SR, a kind of first-order Duffing equation attractor is analyzed at first, and then the property of nonlinear Duffing equation is studied, based on which the nonautonomous Duffing equation attractor curve is deduced. The output of SR system can be obtained by mapping the input signal on the attractor curve, and the dynamic mechanism of SR is explained by using the mapping method. Analysis of the result indicates that the intrinsic signal can push the system to move along the attractor curve, and the noise can evoke a transition response of the system under the given conditions. Some exited SR weak signal detection methods, such as the parameter-adjustment and damping-adjustment are extended by the proposed dynamic mechanism.
A 0.14 THz coaxial surface wave oscillator
Authors: Chen Zai-Gao  , Wang Jian-Guo  , Wang Guang-Qiang  , Li Shuang  , Wang Yue  , Zhang Dian-Hui  , Qiao Hai-Liang  ,   School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China;,   Northwest Institute of Nuclear Technology, P. O. Box 69-12, Xi'an, Shaanxi 710024, China
Published: December 2020

To increase the output power of the surface wave oscillator (SWO) at the terahertz band, this paper presents a new type of coaxial-structured SWO, and its dispersive curve of TM01 mode is calculated numerically. The working properties of this new device are numerically simulated by using the self-developed fully electromagnetic particle code UNIPIC. Numerical results show that the working frequency of the coaxial-structured SWO is identical to that of the cylindrical-structured SWO, and the output power from this new coaxial-structured SWO is 67.8% more than that from the cylindrical-structured SWO, and the output mode of the terahertz wave is the transverse electromagnetic mode.
The polarization-difference interference imaging spectrometer-Ⅱ. optical design and analysis
Authors: Mu Ting-Kui  , Zhang Chun-Min  , Li Qi-Wei  , Wei Yu-Tong  , Chen Qing-Ying  , Jia Chen-Ling  ,   Institute of Space Optics, Ministry of Education Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The static polarization-difference interference imaging spectrometer, based on the combination of Wollaston prism and Savart polariscope, can simultaneously acquire hyperspectral images for orthogonal polarization components. Optical specifications are determined according to the principle of interference spectroscopy and the technical parameters of an actual detector. A design scheme is demonstrated. The Savart polariscope, Wollaston prism and Glan-Taylor prism are designed according to the birefringent features of uniaxial crystal and the wave normal tracing. More emphasis is put on the influences of the dispersion of uniaxial crystal on the incident angle, thickness, and apex angle. This research can provide a theoretical guide in the engineering of the polarization-difference interference imaging spectrometer.
The base current broadening effect and charge separation method of gate-controlled lateral PNP bipolar transistors
Authors: Ma Wu-Ying  , Wang Zhi-Kuan  , Lu Wu  , Xi Shan-Bin  , Guo Qi  , He Cheng-Fa  , Wang Xin  , Liu Mo-Han  , Jiang Ke  ,   Key Laboratory of Functional Materials and Devices for Special Environments of CAS; Xinjiang Key Laboratory of Electronic Information Materials and Devices; Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   National Laboratory of Analog ICs; Sichuan Institute of Solid-State Circuits, CETC, Chongqing 400060, China
Published: December 2020

In order to study the total dose effect and hardness assurance technology for the bipolar devices, we have designed and fabricated different gate-controlled lateral PNP bipolar transistors by various technologies, and preformed 60Co-γ low-dose rate irradiation. The test results show that: 1) Irradiation characteristics of the gate-controlled bipolar transistor are strongly dependent on the fabrication technology, and the passivation layer has a great influence on the irradiation response of the device. The device with a passivation layer will have more interface traps in ionizing radiation environments, and its resistance to ionizing irradiation is greatly weakened. 2) A domestic gated-controlled lateral PNP transistor exhibited a peak current broadening effect at low-dose rate irradiation. In this paper, we analyze the mechanism of the broadening effect, and put forward a new separation method for reducing the base current broadening effect, which not only provides the basis for the design of hardened devices, but also a powerful tool for the study of the enhanced low-dose rate sensitivity of the bipolar device.
Atomic force microscopy studies on self-organized wrinkles in constrained metallic films deposited on silicone oil substrates
Authors: Yu Sen-Jiang  ,   School of Physics Science and Engineering, Tongji University, Shanghai 200092, China;,   Department of physics, China Jiliang University, Hangzhou 310018, China
Published: December 2020

Silicone oil droplets with varied sizes (micrometer to millimeter) were sprayed onto a clean glass slide and then Cr films were deposited on the droplets by DC-magnetron sputtering. Self-organized wrinkles induced by thermal stress have been investigated using atomic force microscope. It is found that the Cr films are limited by the droplet edges and thus possess constrained edges, which can well control the wrinkle morphologies: the wrinkles may exhibit radiated strips perpendicular to the edge. The wavelength and amplitude will decrease when approaching to the constrained edge. Morphologies of the wrinkles are closely related to the film thickness and oil drop size. As the film thickness increases, the wrinkles first form near the edge, and then propagate to the central region. The wavelength at the droplet center is almost unchanged for different oil sizes, but the amplitude first increases and then decreases with increasing film thickness. When the film thickness is fixed, the wavelength and amplitude may increase accordingly with increasing droplet size. Further studies show that the top surface of the silicone oil is modified to form a polymer layer during the deposition due to the bombardment from high-energy particles and heat radiation from the sputtering source. Morphologies of the wrinkles and amplitude evolutions are then explained in detail.
First principles study on molecule doping in MoS2 monolayer
Authors: Liu Jun  , Liang Pei  , Shu Hai-Bo  , Shen Tao  , Xing Song  , Wu Qiong  ,   College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China
Published: December 2020

The chemical doping of organic molecules adsorbed on MoS2 monolayers are systematically studied by using plane-wave pseudo-potential method based on the density functional theory. Our results indicate that the interaction between organic molecules and the MoS2 monolayer substrate is of van der Waals' type of force. Structure of monolayer MoS2 which adsorbs different organic molecules, exhibits indirect bandgap characteristics, and the energy band structure of monolayer MoS2 which adsorbs TTF molecules exhibits n-type conducting characteristics. However, the structures of monolayer MoS2 which adsorbs TCNQ or TCNE molecules would exhibit p-type conductivity characteristics. Thus, the results indicate that the doping type of molecules in monolayer MoS2 can be regulated by adsorbing different molecules. Results of this study may provide a theoretical basis for single-layer MoS2 transistor and guidance for it in the application.
Influence of edge reconstruction on the electron transport in zigzag graphene nanoribbon
Authors: Li Biao  , Xu Da-Hai  , Zeng Hui  ,   College of Physical Science and Technology, Yangtze University, Jingzhou 434023, China
Published: December 2020

Edge reconstructions of graphene nanoribbons and their stable defective configurations were identified by experimental characterization. First principles calculations are performed to evaluate the effects of atomic edge arrangement on the electronic transport properties of zigzag graphene nanoribbons. It is found that these two defective edge structures affect effectively the high stable nanostructure configuration and give rise to pronounced modifications on electronic bands, leading to the shift of Fermi level as well as the occurrence of resonant energies. Both of these two atomic reconstructions would limit the electron transport around the Fermi level, and result in the complete resonant backscattering taking place at different locations. The suppression of conductance is not only related with increasing defect size, but more sensitive to the distribution of defect state, and the modifications on the electronic bands that are influenced by the edge reconstructions.
Effect of different ohmic contact pattern on GaN HEMT electrical properties
Authors: Zhu Yan-Xu  , Cao Wei-Wei  , Xu Chen  , Deng Ye  , Zou De-Shu  ,   Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

In this paper, the AlGaN/GaN HEMT (high electron mobility transistors) with different ohmic contact structures are fabricated, and the effect of different ohmic contact pattern on GaN HEMT electrical properties is studied. A conventional ohmic contact electrode structure and a new ohmic contact structure with a contact hole are fabricated and subjected to rapid thermal annealing (RTA) in flowing N2. After different structured AlGaN/GaN HEMTs are annealed at 750 ℃ for 30 seconds, in HEMTs with a conventional structure ohmic contact still does not form while in the device with ohmic contact holes a good ohmic contact is already formed. Then the surface morphology of different multilayer electrode structures is measured. Comparing Ti/Al/Ti/Au with Ti/Al/Ni/Au, we can conclude that the structure Ti/Al/Ni/Au has a more smooth surface after annealing. After testing the HEMT devices with different structures, higher transconductance and saturation current are found for the devices with ohmic contact holes. But a serious current collapse phenomenon has been observed when the gate voltage is set between 0.5 V and 2 V.
Study on electrical transport properties of strained Si nanowires by in situ transmission electron microscope
Authors: Wang Jiang-Jing  , Shao Rui-Wen  , Deng Qing-Song  , Zheng Kun  ,   Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Strain engineering in semiconductor nanostructure has been received great attention because their ultra-large elastic limit can induce a broad tuning range of the physical properties. Here, we report how the electrical transport properties of the p-type -oriented Si nanowires may be tuned by bending strain and affected by the plastic deformation in a transmission electron microscope. These freestanding nanowires were prepared from commercial silicon-on-insulator materials using the focusing ion beam technique. Results show that the conductivity of these Si nanowires is improved remarkably by bending strain when the strain is lower than 2%, while the improvement is nearly saturated when the strain approaches to 2%. The electric current will reduce a little sometimes when strain exceeds 3%, which may result from plastic events. Our experimental results may be helpful to Si strain engineering.
Studies on the kinetic theory of polymer dielectric breakdown due to partial discharge
Authors: Li Dan  , Hu Hai-Yun  ,   School of Physics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

With the improvement of voltage level of electrical equipment, the requirement for the reliability of polymer dielectric materials in electrical equipment is much more strict. However, there are inevitably some defects in the manufacturing process of polymer dielectric materials, such as bubbles, inclusions, and so on. Therefore the life of electrical equipment will be greatly decreased when partial discharge occurs in a high electric field. In order to prevent and reduce the accident caused by the aging of polymer dielectric material in the electrical equipment, electrical aging life needs to be reasonably estimated. Based on the microscopic mechanism of partial discharge aging model, this paper suggests a stochastic differential equation for the electrical crack growth by using a non-equilibrium statistical physics theory, and then functions of breakdown probability, reliability, and electrical aging life due to the application of electric field are derived. Finally, a detailed analysis for the polyetllyleneterephthalate (PET) film is carried out, and the theoretical life of electrical aging is compared with experimental data. Results show that the theoretical values are consistent with the experimental data. So the aging life equations of polymer dielectrics derived in this paper can be used effectively in the quantitative analysis and may be helpful for the estimation of electrical life.
Ferroelectric and antiferroelectric properties of Si-doped HfO2 thin films
Authors: Zhou Da-Yu  , Xu Jin  ,   School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;,   Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian 116023, China
Published: December 2020

Ferroelectric and antiferroelectric HfO2 nano-films were prepared by changing silicon doping concentration, and their basic properties conpared in terms of polarization hysteresis, capacitance-voltage and leakage-voltage behavior, as well as the effect of temperature on phase stability. Antiferroelectric thin film exhibits a higher dielectric constant than the ferroelectric film, and is characterized by the double polarization hysteresis loops due to reversible antiferroelectric-ferroelectric phase transition induced during loading and unloading processes of electric field. No antiferroelectric-paraelectric phase transition is observed at measuring temperatures up to 185 ℃. The negative differential resistivity effect observed in leakage measurements is attributed to the contributions from slow response mechanisms like polarization relaxation.
Transient photostriction and strain modulation in La, Nb-codoped BiFeO3 thin films
Authors: Xu Yue  , Zhang Ze-Yu  , Jin Zuan-Ming  , Pan Qun-Feng  , Lin Xian  , Ma Guo-Hong  , Cheng Zhen-Xiang  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   Institute for Superconductor and Electronic Materials, University of Wollongong, North Wollongong, NSW 2500, Australia
Published: December 2020

Coherent longitudinal acoustic phonons in Bi0.8La0.2Fe0.99Nb0.01O3 (BLFNO) films are photo-induced and detected by the femtosecond time-resolved reflectance spectroscopy. The generation mechanism of coherent longitudinal acoustic phonons is attributed to the transient photostriction effect. The strain modulation of the out-of-plane elastic properties C is realized in BLFNO films deposited on different substrates (ZrO2 and PbMg1/3Nb2/3-PbTiO3). Strain modulation of the thin film is demonstrated by applying an electromotive force on the piezoelectric substrate PbMg1/3Nb2/3-PbTiO3.
Scaling behaviours in the competing processes between aggregation and complete annihilation of two species of particles
Authors: Li Li  , Li Ping-Ping  , Ke Jian-Hong  , Xia Hai-Jiang  , Lin Zhen-Quan  ,   College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China
Published: December 2020

A two-species system is considered, in which irreversible aggregations occur between particles of the same species while irreversible complete annihilations occur between particles of different species. Such competing processes between aggregation and annihilation reactions are performed by Monte Carlo simulations under various parameter conditions, and the influences of aggregation rate, annihilation rate, and initial particle distribution on the dynamics of the system are analyzed in detail. Simulation results indicate that the particle size distributions always obey a certain scaling law. When the aggregation rates of the two kinds of particles are both twice as fast as the annihilation rate, the scaling exponents of the particle size distributions have relation with the initial particle distribution; while in the remaining cases, the scaling exponents depend crucially on the reaction rates. Moreover, when both aggregation rates are larger than or equal to the double of the annihilation rate, all particles will annihilate each other completely; while at least one of the aggregation rates is slower than the double of the annihilation rate, the species with slower aggregation rate could survive finally. Simulation results are in good agreement with the reported theoretical solutions.
Study on 220 GHz third harmonic photonic band gap cavity gyrotron oscillator
Authors: Huang Li-Ping  , Hong Bin-Bin  , Liu Chang  , Tang Chang-Jian  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;,   Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, China;,   Department of Foundation studies, Logisitics Engineering University, Chongqing 400016, China
Published: December 2020

A design of 220 GHz third harmonic photonic band gap cavity gyrotron oscillator is proposed. Higher photonic crystal band gap is used to ensure the interaction between the high order electromagnetic mode (TE63-like) and the third harmonic electron cyclotron mode in gyrotron. The weak mode competition between TE63-like and TE92-like mode is studied by using a nonlinear theory, and the working conditions that ensure the start-up of the gyrotron to work in the third harmonic mode, as well as the nonlinear characteristics during the start-up process, are achieved. These results are in good agreement with the PIC (particle-in-cell) simulation. Our study shows that by using the photonic crystal as the high-frequency structure of gyrotron, high-order electromagnetic modes can interact with harmonic electron cyclotron modes efficiently.
Solution-processed high performance HIZO thin film transistor with AZO gate dielectric
Authors: Gao Ya-Na  , Li Xi-Feng  , Zhang Jian-Hua  ,   Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China
Published: December 2020

Hafnium indium zinc oxide (HIZO) thin film transistors with zirconium aluminum oxide (AZO) gate dielectric were fabricated by solution-process. The HIZO and AZO oxide thin films have smooth surfaces with root-mean-square roughness of 0.62 nm and 0.35 nm respectively. The thin film transistor with channel length = 6 μm and the ratio of width/length =5 exhibits a high saturation field-effect mobility of 21.3 cm2/V·s, a low threshold voltage of 0.3 V, a high on-off ratio of 4.3×107 and a small subthreshold swing of 0.32 V/dec. And these properties of TFT may be impacted by highly-coherent and low trapping states interface between the AZO dielectric and HIZO semiconductors.
Delamination study of InSb infrared focal plane arrays using a cohesive zone model
Authors: Meng Qing-Duan  , Gui Lei  , Zhang Xiao-Ling  , Zhang Li-Wen  , Geng Dong-Feng  , Lü Yan-Qiu  ,   School of Electrical Engineering, Henan University of Science and Technology, Luoyang 471023, China;,   School of Information Engineering, Henan University of Science and Technology, Luoyang 471023, China;,   China Airborne Missile Academy, Luoyang 471009, China
Published: December 2020

Local interfacial delamination and cracking, appearing in the top surface of InSb infrared focal plane arrays (IRFPAs), are typical failure patterns observed in liquid nitrogen shock tests. In order to explore the delamination mechanism and cracking process, based on the thought of three-dimensional equivalent modeling, we employ the cohesive zone model (CZM) for the interface where delamination appears most easily, and create the structural model of 128×128 InSb IRFPAs. Simulation results contain all the deformation characteristics appearing in the typical optical fracture photographs. That is, firstly, in the photosensitive element array, the global square checkerboard buckling pattern reappears; secondly, in the negative electrode material, the InSb chip is gradually separated from the negative electrode, and the width of delamination is widened gradually; thirdly, on the periphery of InSb IRFPAs, the surface is flat. All these findings suggest that the model created in this paper is correct, and the parameters selected are suitable. Based on the delamination model, it is possible to find the initiation and propagation rule of cracks in the research that follows.
Segmentation of breast MR images based on multiresolution level set algorithm
Authors: Fan Hong  , Zhu Yan-Chun  , Wang Fang-Mei  , Zhang Xu-Mei  ,   School of Computer Science, Shaanxi Normal University, Xi'an 710062, China;,   Beijing Key Laboratory of Medical Physics and Engineering, School fo Physics, Peking University, Beijing 100871, China
Published: December 2020

This paper proposes a novel multiresolution level set algorithm to segment breast MR images, which have a large amount of information, intensity inhomogeneities, and weak boundary. The core of the algorithm is to get the coarse scale image by analyzing the image in multi-scale space with wavelet multiscale decomposition. Then, to segment the analysed results in terms of improved CV model. In order to deal with the effect of bias field on the global images, the algorithm introduces a local fitting term into the improved CV model and optimizes the coarse-scale segmentation result by using the Kernel function to further improve the CV model. Experimental results on both synthetic and real breast MR images demonstrate that the proposed algorithm can segment the images with intensity inhomogeneity effectively and efficiently, also it can segment the images far more accurately, computationally efficiently, and much less sensitively to the initial contour.
Gallium diffusion in CIGS thin films prepared by sequential sputtering/selenization technique
Authors: Mao Qi-Nan  , Zhang Xiao-Yong  , Li Xue-Geng  , He Jin-Xin  , Yu Ping-Rong  , Wang Dong  ,   College of Engineering, Peking University, Beijing 100871, China;,   Optony Inc., Hangzhou 310051, China
Published: December 2020

In the sequential sputtering/selenization process, Ga segregation at the back of Cu(In, Ga)Se2 (CIGS) absorber is frequently observed. In this paper, Ga diffusion in CIGS absorber is investigated during the sputtering and selenization process. Results show that Ga diffusion is closely related to Cu/(In+Ga) ratio in the metallic precursors and the selenization temperature, but barely influenced by Ga/(In+Ga) ratio in the metallic precursors. Based on Fick's second law, a simplified model is established to describe Ga diffusion from the back to the surface of CIGS absorber, which suggests that Ga diffusion coefficient is the dominant factor to constrain Ga content near the absorber surface. By process optimization, Ga/(In+Ga) ratio near the absorber surface is successfully increased. Accordingly, a CIGS solar cell device with efficiency of 12.42% has been obtained.
The analogy and predictability of the forecasting model error for the precipitation over the mid-lower reaches of the Yangtze River in summer
Authors: Wang Qi-Guang  , Su Hai-Jing  , Zhi Rong  , Feng Ai-Xia  ,   China Meteorological Administration Training Center, CMA, Beijing 100081, China;,   Laboratory for Climate Studies, National Climate Center, CMA, Beijing 100081, China;,   National Meteorological Information Center, CMA, Beijing 100081, China;,   Physical Science and Technology College of Yangzhou University, Yangzhou 225002, China
Published: December 2020

This paper reports an effective method to improve the forecasting level of the numerical model through analogue prediction of errors and correction of the results. The analogy of the precipitation model errors and its predictability are studied for the mid-lower reaches of the Yangtze River in summer time in the perspective of analogy, which exists in the error field in the forecasting numerical model. The content of the analogy is also investigated according to the historical data. It is found that the forecasting errors could be improved remarkably by analogue error prediction over the regions researched in summer time. The forecasting error field is decomposed by EOF, and then the geographic distribution and time coefficient evolution of the first three principal components are analyzed. The prediction of the precipitation could be simplified by analogue forecasting of the principal components separately, and it is more targeted to improve the potential forecasting level. On the basis of the analogy of the forecasting error field, its analogue predictability is defined to measure the predictability of the errors. The analogue predictability of the first three principal components is significantly higher than that of the original field. It has potential applications to precipitation predication by forecasting the error field principal components.
Application of compressed sensing theory in the method of moments
Authors: Wang Zhe  , Wang Bing-Zhong  ,   Institute of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Matrix filling and equation solving are the most computationally-expensive steps in the method of moments (MoM). Based on the compressed sensing (CS) theory, an improved method of MoM is proposed in this paper. Through introducing sparse transform matrix, the unknown response can be expressed sparsely, so we can construct and optimally solving underdetermined equation under the framework of CS. Numerical examples show that the proposed method can reduce the matrix filling cost dramatically, and also can improve the efficiency of equation solving effectively.
Chaotic characteristics of three-dimensional function determined by cross-section geometric shape
Authors: Yu Wan-Bo  ,   College of Information Engineering, Dalian University, Dalian 116622, China
Published: December 2020

The calculation and simulation results show that f(x,y,z)=sin(k(x2+y2+z2)), f(x,y,z)=k(1-(x2+y2+z2))e(-(x+y+z+u)2), f(x,y,z)=k((x2+y2+z2)/3)(1-(x2+y2+z2)/3) can easily constructe a three-dimensional (3D) discrete dynamic system by combining other two polynomial functions generated randomly. Through calculating Lyapunov exponent and drawing the bifurcation diagram, the characteristics of chaos of the function are confirmed, and according to the bifurcation diagram of parameters and the Lyapunov exponent curve more chaotic mapping functions are found. Analysis shows that the cross-section geometric shape can determine the chaotic characteristics of 3D function, and the cross-sections are all the median convex or middle concave surfaces, which can constructe chaotic dynamic systems easily. In the future, the mathematical description model and some basic theorems are to be further investigated and their results will be used to solve practical problems such as turbulence.
Directional transport of fractional asymmetric coupling system in symmetric periodic potential
Authors: Tu Zhe  , Lai Li  , Luo Mao-Kang  ,   College of Mathematics, Sichuan University, Chengdu 610065, China;,   College of Aerospace Science and Engineering, Sichuan University, Chengdu 610065, China
Published: December 2020

Based on the fractional calculus theory, in the absence of external driving force, the fractional transport model of asymmetric coupling particle chain in symmetric periodic potential is established. Using the method of fractional difference, the model is solved numerically and the influences of the various system parameters on directional transport velocity are discussed. Numerical results show that in the case without external force and noise-driven, the fractional asymmetric coupling system can still generate directional transport, and the transport velocity increases as fractional order increases. When the fractional order is fixed, the average velocity of the particle chain varies non-monotonically with coupling strength and barrier height. In the case with noise, the generalized stochastic resonance phenomenon occurs. Besides, we can make the noise not affect the system or even promote directional transport by adjusting other parameters.
Stability of a weakly interacting Fermi gas in a strong magnetic field
Authors: Men Fu-Dian  , Tian Qing-Song  , Chen Xin-Long  ,   College of Science, China University of Petroleum (East China), Qingdao 266555, China
Published: December 2020

Using the quantum statistical theory, the stability of a weakly interacting Fermi gas trapped in a strong magnetic field is investigated, the expression of stability condition is given, and the mechanisms of influences of interparticle interaction and magnetic field on the stability are analyzed. The results show that repulsive interaction will increase both the chemical potential and the space domain needed for system stability. But, the increasing of magnetic field strength will reduce the space domain needed for the system stability, and lower the stability of the particle number density distribution.
Design of the matched chaotic stimulation for fault detection of the single input single output system
Authors: Yang Dong-Dong  , Ma Hong-Guang  , Xu Dong-Hui  , Feng Xiao-Wei  ,   The Second Artillery Engineering University, Xi'an 710025, China
Published: December 2020

In this paper, for the fault detection of a single-input single-output (SISO) system, we define a concept of matching chaotic stimulation with a measured system, establish a criterion of matching chaotic stimulation with a measured system, and propose a method of adjusting the matching of chaotic stimulation with a measured system. Finally, the improved prediction error is used to detect faults in the SISO system. The simulation results show that matched chaotic stimulation can be used to detect faults effectively, while unmatched ones can add uncertainty into the fault detection.
Design and application of multi-scroll chaotic attractors based on simplified Lorenz system
Authors: Ai Xing-Xing  , Sun Ke-Hui  , He Shao-Bo  , Wang Hui-Hai  ,   School of Physics and Electronics, Central South University, Changsha 410083, China;,   School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

Two linear systems are obtained by employing linearization technique in a simplified Lorenz system, and a two-scroll chaotic attractor is generated via the control method. Multi-scroll chaotic attractors are generated by extending the saddle-focus equilibrium points with index 2. Dynamic characteristics of the multi-scroll chaotic system are analyzed by observing the phase diagrams, bifurcation diagrams, Poincaré sections and calculating the largest Lyapunov exponent. A circuit for the multi-scroll attractor is designed and simulated. The numerical simulation result and the circuit simulation result are consistent with each other. To apply the multi-scroll chaotic systems to image encryption, an improved hybrid encryption algorithm is designed based on the multi-scroll chaotic system and advanced encryption standard (AES), and its encryption performances are analyzed. The results show that the improved hybrid encryption has a higher security.
First principles study on influence of oxygen vacancy in HfO2 on charge trapping memory
Authors: Dai Guang-Zhen  , Dai Yue-Hua  , Xu Tai-Long  , Wang Jia-Yu  , Zhao Yuan-Yang  , Chen Jun-Ning  , Liu Qi  ,   Key Laboratory of Detection and Automation of Anhui Province, School of Electrial Engineering, Anhui Polytechnic University, Wuhu 241000, China;,   Key Laboratory of Integrated Circuit Design of Anhui Province, School of Electronics and Information Engineering, Anhui University, Hefei 230601, China;,   Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

With the further scaling down of device dimensions, charge trapping memory with high k materials HfO2 serving as capture layer shows good endurance and high storage capacity. Its relatively simple process and complete compatibility with the conventional semiconductor process furthermore make it widely studied. The oxygen vacancies in HfO2 are studied using the first-principles calculation in order to learn their influence on the storage properties of charge trapping memory. Write and erase operations of memory devices are simulated via changing the number of electrons in the super cell with defects. The results show that basically the distance between oxygen vacancies has no effect on charge trapping, but the number of oxygen vacancies does affect it. The more the number of oxygen vacancies, the stronger the electron capture ability is. Moreover, four-fold coordinated oxygen vacancy (Vo4) has lager capability for trapping charge than three-fold coordinated oxygen vacancy (Vo3). The analysis of density of states shows that Vo4 induces a large number of quantum states with deep energy levels which is little affected by distance and has large possibility of trapping charges. The results show that oxygen vacancy defects in HfO2 tetravalent coordination are conducive to improving the storage characteristics of charge trapping memory.
Design and measurement of a magnetic field for precision spectroscopy of helium
Authors: Feng Gao-Ping  , Sun Yu  , Zheng Xin  , Hu Shui-Ming  ,   Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Systematic error caused by stray magnetic fields is often one of the major sources of the uncertainties in many precision measurements. It is necessary to accurately control the magnetic fields in these measurements. The spectrum of the fine structure of helium can be used to determine the fine structure constant, and also to test the quantum electrodynamic theory of multi-electron systems. In this work, we present a magnetic shield that can eliminate stray magnetic fields and a cosine coil that generates a uniform magnetic field. The central magnetic strength produced by the coil is measured through the spectrum of a 4He metastable atomic beam. The magnetic shield reduces the strength of the external magnetic field down to less than 0.8 mGs. The variation of the magnetic strength in the spectrum region is less than 10 mGs at a magnetic strength up to 20 Gs. In this case, the uncertainty introduced by the magnetic field will be less than in the spectrum of helium fine structure.
Evolution of entanglement between a two-level atom and spontaneous emission field in structured reservoir
Authors: Li Hao-Zhen  , Xie Shuang-Yuan  , Xu Jing-Ping  , Yang Ya-Ping  ,   Key Laboratory of Advanced Micro-Structured Materials of Ministry of Education, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
Published: December 2020

The time evolutions of the entanglement between a two-level atom and its spontaneous emission field in free space, cavity, isotropic and anisotropic photonic crystal are studied by using quantum entropy. It is found that the evolution properties of the atom-field entanglement are directly related to the nature of the structured reservoir,specifically, to the distribution of the density of modes. In free space and cavity, as the density of the modes varies smoothly with frequency, the atom-field entanglement decays to zero in a finite time. However in an isotropic and anisotropic photonic crystal, the atom-field entanglement can keep steady due to the existence of a photonic band gap in the density of the modes. Thus, we can control the time evolution of the entanglement between the atom and its spontaneous emission field by changing the density of the modes of the structured reservoirs.
Simulation of Z-pinch Al plasma radiation and correction with considering superposition effect
Authors: Gao Qi  , Zhang Chuan-Fei  , Zhou Lin  , Li Zheng-Hong  , Wu Ze-Qing  , Lei Yu  , Zhang Chun-Lai  , Zu Xiao-Tao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

In this article, the X ray special line radiation from Z-pinch Al plasma is calculated by using non-local-thermodynamic-equilibrium model (NLTE) based on digital energy level. The electron density of Z-pinch plasma at centre is obtained. The single plasma state parameter cannot well describe the special line radiation. In the next step, the Z-pinch plasma is divided into two parts: high electron temperature plasma at centre and low electron temperature plasma. The superposition of radiations from two parts is analyzed, and modified calculation result is presented. The calculation results are significantly improved after the superposition of radiations from two parts has been taken into account.
A collisional-radiative model for the helium plasma in the sino-united spherical tokamak and its application to the line intensity ratio diagnostic
Authors: Xie Hui-Qiao  , Tan Yi  , Liu Yang-Qing  , Wang Wen-Hao  , Gao Zhe  ,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

The collisional-radiative model, that has been constructed for the helium plasma in the Sino-United Spherical Tokamak is introduced. The result of the 447.1nm (23P-43S)/492.2nm(21P-41D) and 492.2nm/504.8nm(21P-41S) line ratios is given. The line ratio method that is used for measuring electron temperature Te and density Ne parameters is described. The result from the line ratio method is consistent with the measurement of the 94 GHz interferometer. The method is also validated by comparing the relative population densities of the excited states which are deduced from the CR model and the measured intensity data of helium lines. The factors that brings errors into the diagnostic result are discussed, including the error from the measurements, and those from the uncertainties of the rate coefficients that are used in the CR model and the viewing chord integration characteristic of the optical emission measurement.