bluuebunny/crossref_metadata_2025 huggingface dataset:
A new characteristics matrix method based on conductivity and its application in the optical properties of graphene in THz frequency range
Authors: Deng Xin-Hua  , Liu Jiang-Tao  , Yuan Ji-Ren  , Wang Tong-Biao  ,   School of Science, Nanchang University, Nanchang 330031, China;,   State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

A new characteristics matrix method along with the formulas based on conductivity, which can be used to calculate the optical properties of an ultra-thin conductive composite multilayer dielectric structure, is derived for the first time as faras we know based on the electromagnetic boundary conditions Maxwell's equations required. It can be used to calculate the reflection, transmission, and absorption of light, provided that the conductivity of the conductive body is known, also it can overcom the shortcoming of the traditional transfer matrix method, i.e.it is necessary to know the permittivity and permeability of the material. By using the proposed method, the optical behavior of graphene and composite multilayer structures can be obtained in the THz frequency range.
Dynamic functional connectivity of electroencephalogram in the resting state
Authors: Yang Jian  , Chen Shu-Shen  , Huangfu Hao-Ran  , Liang Pei-Peng  , Zhong Ning  ,   Institute of International WIC, Beijing University of Technology, Beijing 100124, China;,   Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing 100124, China;,   Beijing International Collaboration Base on Brain Informatics, Wisdom, and Services Beijing 100124, China;,   Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
Published: December 2020

Assessment of resting-state functional connectivity (FC) has become an important tool in studying brain disease mechanisms. Conclusions from previous resting-state investigations were based upon the hypothesis which assumed that the FC was constant throughout a period of task-free time. However, emerging evidence suggests that it may change over time. Here we investigate the dynamic FC based on the 64 electrodes EEG (electroencephalogram) of 25 healthy subjects in eyes closed (EC) and eyes open (EO) resting-state. A data-driven approach based on independent component analysis, standardized low-resolution tomography analysis, sliding time window, and graph theory are employed. Dynamic changes of FC over time with EC and EO in the visual network, the default mode network etc. are discovered. And the principal component analysis is used to the concatenated dynamic FC matrixes for finding meaningful FC patterns. Our results have complemental the traditional stationary analyses, and revealed novel insights in choosing the type of resting condition in experimental design and EEG clinical research.
Simulation of electric activity of neuron by setting up a reliable neuronal circuit driven by electric autapse
Authors: Ren Guo-Dong  , Wu Gang  , Ma Jun  , Chen Yang  ,   Department of Physics, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

Transition of electric activity of neuron can be induced by electric autapse, and its action potential is much sensitive to the stimuli from the electric autapse. Generally, the effect of electric autapse on membrane potential of neuron is often described by using time-delayed feedback in closed loop. Based on Pspice software, a class of electric circuit is designed with the electric autapse being taken into consideration, and a time-delayed circuit is used to detect the adjusting action of electric autapse on the action potential. Results are found as follows: (1) The neuronal electric circuit can produce quiescent state, spiking, bursting state under an external force besides the electric autapse circuit. (2) The transition of electric activity occurs between four different atates (quiescent, spiking, bursting state) by imposing a time-varying forcing current; its potential mechanism is that the electric circuit is associated with the memory, and the neuron can give different types of response to the same external forcing current. (3)When a strong external force is imposed, the outputs can show different type of electric activities due to an electric autapse, that is to say, self-adaption of gain in the autapse is useful for the neuron and thus different type of electric activities occurs, whose potential mechanism may be due to the effective feedback in the loop; so it is helpful to understand the synaptic plasticity.
Microenvironment-enhanced invasive tumor growth via cellular automaton simulations
Authors: Liang Long  , Jiao Yang  ,   Department of Physics, Arizona State University, AZ 85287, USA;,   Materials Science and Engineering, Arizona State University, AZ 85287, USA
Published: December 2020

Emergence of invasive and metastatic behavior in malignant tumors can often lead to fatal outcomes for patients. The collective malignant tumor behavior resulting from the complex tumor-host interactions and the interactions between the tumor cells are currently poorly understood. Progress towards such an understanding necessarily requires an interdisciplinary and collaborative effort. In this paper, we review a state-of-art simulation technique, i.e., a cellular automaton (CA) model which has been developed by the authors over the past few years to investigate microenvironment-enhanced invasive growth of avascular solid tumors. This CA model incorporates a variety of microscopic-scale tumor-host interactions, including the degradation of the extracellular matrix by the malignant cells, nutrient-driven cell migration, pressure build-up due to the deformation of the microenvironment by the growing tumor and its effect on the local tumor-host interface stability. Moreover, the effects of cell-cell adhesion on tumor growth are also explicitly taken into account. A number of bench-mark collective invasion behaviors have been successfully reproduced via the CA model, including the emergence of elongated invasion branches characterized by homotype attraction and least resistance path, development of rough tumor surface in a high-pressure confined environment, as well as reduced invasion due to strong cell-cell adhesion. Such simulated bench-mark behaviors strongly indicate the validity and predictive power of the CA model. In addition, the CA model allows one to investigate the role of various different microenvironment factors in the progression of the neoplasm, in particular, the promotion and enhancement of tumor malignancy. As an example, a “phase diagram” that summarizes the dependency of tumor invasive behavior on extracellular matrix (ECM) rigidity (density) and strength of cell-cell adhesion is constructed based on comprehensive simulations. In this simple phase diagram, a clear transition from non-invasive to invasive behaviors of the tumor can be achieved by increasing ECM rigidity and/or decreasing the strength of cell-cell adhesion. This model, when properly combined with clinical data, in principle enables one to broaden the conclusions drawn from existing medical data, suggest new experiments, test hypotheses, predict behavior in experimentally unobservable situations, be employed for early detection and prognosis, and to suggest optimized treatment strategy for individual patient.
Application of physics in the study of cell polarity during tumor cell migration
Authors: Wang Jing  , Yang Gen  , Liu Feng  ,   State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China;,   Center for Quantitative Biology, Peking University, Beijing 100871, China
Published: December 2020

Investigation of tumors from a physics perspective has attracted more and more attention since the initiation, development, and metastasis of tumors are strongly influenced by the physical interactions between the tumor cells and their microenvironments. Since tumor metastasis accounts for more than 90% of cancer-associated death, one of the focuses is to understand its underlying mechanism, especially how tumor cells polarize during their migration. Cell polarization directs tumor-cell migration in response to a spatial stimulus, e.g., the gradient of chemokine or oxygen molecules. It forms the front and back edges of cells by estiblishing asymmetric distributions of cell polarity proteins such as the Rho family GTPases and organelles such as Golgi. This paper reviews how the experimental and theoretical studies combining physics with biology reveal the underlying mechanisms of cell migration and cell polarity. Experimental results demonstrate that the physics clues including extracellular matrix's mechanical properties, dimensionality, and topography are strongly coupled with the biochemical reactions to establish and maintain the cell polarity and direct cell migration. The cell migration mode in a more physiological three-dimensional (3D) matrix is different from that in a two-dimensional(2D) system. Moreover, the membrane tension is suggested to maitain cell polarity by inhibiting polarization processes outside the front edge. On the other hand, a series of reaction diffusion models have been developed to characterize cell polarity. Representative examples inculding Turing-type model, local-excitation and global-inhibition (LEGI) model, and wave-pinning model can capture certain features of cell polarization, however none of them takes the physical factors, such as the membrane tension, into account hence fails to explain previous published experimental results about the membrane tension with cell polarization. To further improve our understanding of the mechanism of cell polarity, in the future study it is experimentally important to estiblish 3D tumor systems and study the gene regulation network that can control cell polariztion by advanced microscope; theroetically it is of importance to build mathematical models for the chemical reaction diffusion systems coupled with the mechanical factors such as membarne tension. These studies will reveal the molecular mechanism of cell polarization and cell migration under a more physiological relevant condition. They may also help us understand how the higher deformation ability of cancer stem cells provides the higher migration capability compared with the normal cancer cells. Ultimately, they will facilitate developing new therapeutic strategy against tumor metastasis by targeting the signaling of tumor cells in response of physical stimuli.
Phase-field modeling of free dendritic growth of magnesium based alloy
Authors: Duan Pei-Pei  , Xing Hui  , Chen Zhi  , Hao Guan-Hua  , Wang Bi-Han  , Jin Ke-Xin  ,   Shaanxi Key Laboratory of Condensed Matter Structures and Properties, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

In this paper, the process of the free dendritic growth of Mg-0.5 wt.%Al alloy in the basal plane (0001) is simulated in two-dimensional system by using a quantitative phase-field model. A convergence study is carried out to choose the optimal coupling parameter λ and grid width Δx/W0 in simulation. Then we systematically discuss the effects of the anisotropic strength ε and the supersaturation Ω on dendritical tip growth velocity, radius, Péclet number, and stability parameter σ *. Results show that the stability parameter σ * defined by the theory of microscopic solvability is a function of the anisotropy strength ε, i.e., σ* ≅ ε1.81905, which is obviously closest to σ * (ε) ≅ ε 1.75 obtained from the analytical solution. Moreover, for Ω σ * is approximately a constant while it sharply and monotonically decreases with the augment of the value of ε for Ω > 0.6. This indicates that there is a transition from solute-controlled dendrite to kinetic dendrite as Ω increases. Furthermore, the transition of the growth pattern from the snow-like to the circle-like patterns occurs as Ω increases.
Blind angle elimination method in weak signal detection with Duffing oscillator and construction of detection statistics
Authors: Niu De-Zhi  , Chen Chang-Xing  , Ban Fei  , Xu Hao-Xiang  , Li Yong-Bin  , Wang Zhuo  , Ren Xiao-Yue  , Chen Qiang  ,   Air-Force Engineering University, Science College, Xi'an 710051, China;,   Xi'an Communication Institue, Xi'an, 710106, China;,   Air-Force Engineering University, Department of Scientific Research, Xi'an 710051, China;,   Air-Force Engineering University, Equipment Management and Safety Engineering College, Xi'an 710051, China
Published: December 2020

Aiming at the blind angle in detecting weak signals of the same frequency by Duffing oscillator, a novel method of dephasing for the driving signals is proposed to eliminate the blind angle. According to the characteristic of weak signals, expression of blind angle is analyzed, and then the range of blind angle is found out, which corresponds to the amplitude of a new driven signal synthesized from the original driven signals and the unknown one. By making the original driven signal phase shift a degree of π, detection for the same frequency signal can be realized when the synthesized signal is located in the blind angle region, whose feasibility is proven by an experiment that it remains in chaotic status in the case of blind angle but becomes a great period status after the original driven signal's phase is dephased by π. To overcome the drawbacks of qualitative analysis and distinguish effectively different status in signal detection course, a detection statistics based on likelihood-Halmiton system is constructed. On the basis of it, a diagram of detection for any frequency signal is drawn. The key point is to make it as an unknown signal's frequency range where there are two adjacent frequency values whose corresponding detection statistics both located in the range of intermittent chaotic status, while one of them is just corresponding to the maximum value of the detection statistics. By simulations of different circumstances, detection statistics for numerical ranges of chaos, intermittent chaos, and great period is summarized. Furthermore, detection for any frequency signal may be realized by use of the numerical range. It is shown that the proposed method could not only provide quantitative judgment for the system status, but improve the signal detection performance. Also, it could be combined well with the traditional oscillator array method or adaptive step intermittent chaotic oscillator method, which further can improve some existing signal detection methods with Duffing oscillator.
Study on compensation method of beam deviation in division of time imaging polarimetry
Authors: Hou Jun-Feng  , Wu Tai-Xia  , Wang Dong-Guang  , Deng Yuan-Yong  , Zhang Zhi-Yong  , Sun Ying-Zi  ,   China Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China;,   Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China
Published: December 2020

In the division of time imaging polarimetry, polarization information of field under measurement (I, Q, U), is obtained by rotating the analyzer. In the process of measurement, the beam deviation caused by the wedge of the analyzer reduces the spatial resolution and polarization accuracy of imaging polarimetry. In this paper we present that the beam deviation above can be reduced or even compensated for by adjusting the tilt angle of analyzer with respect to the incident optical axis. Taking Glan prism as the analyzer, we establish the first-order approximate compensation model of beam deviation based on the theory of geometric optics, acquiring the function relation between the tilt angle and wedge of Glan prism, and verify the feasibility and effectiveness of the compensation method by simulation. The study shows that the first-order approximation error of beam deviation can be compensated for by adjusting the tilt angle of Glan prism if only Glan prism is placed in a convergent beam; the tilt angle is proportional to Glan prism wedge angle, refractive index, and distance to CCD, but inversely proportional to Glan prism thickness. The results provide a theoretical basis for developing the time division imaging polarimetry with high spatial resolution and polarization accuracy.
H + Li2: a typical exothermic reactive system and its time-dependent dynamics investigation
Authors: Zhang Jing  , Wei Wei  , Gao Shou-Bao  , Meng Qing-Tian  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

In this paper, the time-dependent wave-packet method is used to study the three-dimensional dynamical properties of the H+Li2 reactive system on its ground state potential energy surface. The reaction probabilities for J=0 with different vibrational quantum numbers v=0, 1, 2, 3 and for v=0 with different total rotational quantum numbers, integral cross sections and rate constants are calculated for collision energies in a range between 0 and 0.4 eV. The features of the reaction probabilities and reaction threshold energy are analyzed. The results show that the vibrational excitation has a certain inhibitory effect on the reaction process and the reaction threshold energy increases with the increase of J. These phenomena are associated with the type of the exothermic reaction of the reactive system. The influence of the collision energy on the integral cross sections and the effect of the temperature on reaction rate constants are also investigated.
Investigation of the isomerism of dichloroethylene in momentum space
Authors: Huang Yan-Ru  , Ren Huan  , Song Jian  ,   College of Science, Liaoning Shihua University, Fushun 113001, China
Published: December 2020

The geometric parameters are optimized at the B3LYP and CI levels under the constraints of the C2v, C2v and C2h symmetry point groups for the three isomers of dichloroethylene. The theoretical two-dimensional electron momentum distributions and momentum profiles of four core orbitals for iso-dichloroethylene, cis-dichloroethylene and trans-dichloroethylene are calculated by non-relativistic density functional method. Comparing the electron distributions in position and momentum space of these orbitals, it is found that the interference effects, which do not exit in position space, appear and produce the evident periodical multipeaked momentum distributions in momentum space. The distances between atoms and the alignments of molecular axes for these three isomers can be obtained by computing their values of period and the axis directions of period, respectively.
Polarization and propagation characteristics of the azimuthally polarized non-diffracting beam
Authors: Liu Ji-Lin  , Chen Zi-Yang  , Zhang Lei  , Pu Ji-Xiong  ,   College of Information Science and Engineering, Fujian Provincal Key Laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China
Published: December 2020

In this paper, the characteristics of the azimuthally polarized non-diffracting beam (APB) propagating in the free space and obstruction space are investigated theoretically and experimentally. The variations in intensity distribution and polarization characteristics of the APB in propagation process are simulated. In the experiment, the APB is generated by using the polarization converter and axicon. And then, we investigate its transmission and analyze the intensity distribution of APB which is behind a sector-shaped opaque obstacle. We also discuss the influences of obstacles on the polarization and self-healing features of the APB. The results show that the light intensity in obstacle block area gradually restores along the z axis and the shadow area moves toward the direction opposite to the location of obstacle. The polarization of the light beam changes partly and the change relates to the obstacle location. Theoretical simulations accord well with experimental results.
Dark soliton in the system of electromagnetically induced transparency
Authors: Du Ying-Jie  , Xie Xiao-Tao  , Yang Zhan-Ying  , Bai Jin-Tao  ,   School of Physics, Northwest University, Xi'an 710068, China;,   Institute of Photonics and Photon-Technology, Northwest University, Xi'an 710069, China
Published: December 2020

The formation environment and the evolution of dark soliton with environment parameters are investigated by using the electromagnetically induced transparency effect produced high dispersion and nonlinearity. To improve the stability and operability, a dual-well semiconductor is used. Combining the quantum theory and the classical field theory, we derive the nonlinear Schrodinger equation to describe the formations and evolutions of wave and soliton. It is demonstrated that the dark soliton can form and propagate in the medium when the medium is anomalously dispersive and cross phase modulation is negative simultaneously, and that in the evolution of the soliton, the width, gray scale and phase are related to each other, the smaller the pulse duration, the bigger the gray scale is and the faster the growth is. In addition, the modulation instability of the nonlinear system is analyzed, and the gain spectrum of the nonlinear system is also discussed.
Refractive Index Measurement Research for Optical Fiber Based on Digital Hologram
Authors: Gu Ting-Ting  , Huang Su-Juan  , Yan Cheng  , Miao Zhuang  , Chang Zheng  , Wang Ting-Yun  ,   Key Laboratory of Special Fiber Optics and Optical Access Networks, School of Communication and Information Engineering, Shanghai University, Shanghai 200072, China
Published: December 2020

A test system including light path system and software system is built for measuring the refractive index of fiber by using the digital holographic tomography technology. Based on the phase distribution curve of object wave the optimal hologram is recorded. The spectral range corresponding to the object wave is selected accurately based on the optimization of the spectrum. The phase distribution information of object wave is extracted with the angular spectrum reconstraction. The accuracy of extracted phase information has been verified through the simulation holograms of optical fiber. Combined with the multilayers model of fiber, the refractive index distribution along the diameter direction of fiber tomogram is recovered from a single hologram. Single-mode and multi-mode optical fiber are tested as samples. The experiment results are consistent with the results of S14 refractive index profiler, the precision is 10-4. The compare result shows that our method is simple, fast and accurate for the measurement of the refractive index of fibers. We have also studied the measurement of the refractive index distribution of the special optical fiber.
Finite element analysis and design of few mode fiber with low differential mode delay
Authors: Jiang Shan-Shan  , Liu Yan  , Xing Er-Jun  ,   Key Laboratory of All Optical Network and Advanced Telecommunication Network of EMC, Institute of Lightwave Thecnology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Two different types of few mode fibers (FMFs) are considered: a graded-core with a cladding FMF and a multi-step-index FMF. The characteristics of mode field distribution and the effective index are analyzed based on Comsol software. Then differential mode delay is analyzed. The structure and profile parameters are optimized in order to achieve the lowest possible differential mode delay (DMD). Under the condition of supporting four modes, a graded-core with a cladding FMF is designed. The DMD absolute values of LP11, LP21, LP02 are all below 0.015 ps·m-1. Under the condition of supporting two modes, a multi-step-index FMF is designed. The DMD of LP11 is 0.185 ps·m-1. The designed fibers have low DMD, which is suitable for mode division multiplexing.
Quasi-crystal photonic fiber surface plasmon resonance sensor
Authors: Liao Wen-Ying  , Fan Wan-De  , Li Hai-Peng  , Sui Jia-Nan  , Cao Xue-Wei  ,   School of Physics, Nankai University, Tianjin 300071, China
Published: December 2020

Fiber-optic surface plasmon resonance sensor (SPR) plays an important role in the fields of high sensitivity sensor and online real time monitor. We propose a novel six-fold symmetric photonic quasi-crystal fiber SPR sensor with two large semi circular channels. Its sensing properties and influence of fiber structure are simulated numerically by the finite element method. Numerical results demonstrate that its highest sensitivity can reach up to 26400 nmRIU-1, and the measuring range is 1.25-1.331. The novel quasi-crystal fiber SPR sensor, which has characteristics of large measuring range, high sensitivity, mode loss spectrum with less interference peak, design and optical path flexibility, are used widely for biochemical detection, public safety, environmental pollution monitoring and high sensitivity sensor.
Form invariance and Mei conserved quantity for generalized Hamilton systems after adding additional terms
Authors: Sun Xian-Ting  , Zhang Yao-Yu  , Xue Xi-Chang  , Jia Li-Qun  ,   School of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China;,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

Form invariance and Mei conserved quantity for generalized Hamilton systems after adding additional terms are studied. By introducing infinitesimal transformation group and its infinitesimal transformation vector of generators, the definition and determining equations of the Mei symmetry for generalized Hamilton systems after adding additional terms are provided. By means of the structure equation satisfied by the gauge function, the Mei conserved quantity corresponding to the form invariance for the system is derived. Finally an illustrative example is given to verify the results.
Martensitic transformation and magnetic features in Ni-Fe-Mn-In Heusler alloy
Authors: Zhang Yuan-Lei  , Li Zhe  , Xu Kun  , Jing Chao  ,   College of Physics and Electronic Engineering, Qujing Normal University, Qujing 655011, China;,   Key Laboratory for Advanced Functional and Low Dimensional Materials of Yunnan Higher Education Institute, Qujing Normal University, Qujing 655011, China;,   Department of Physics, Shanghai University, Shanghai 200444, China
Published: December 2020

The Ni50-xFexMn37In13(x=1, 3, 5) polycrystalline samples are prepared by arc melting method. The martensitic transformations and crystal structures for Ni50-xFexMn37In13(x=1, 3, 5) samples are systematically analyzed by measuring the structure and magnetism. The results show that the three samples present different structures at room temperature. In the mean time, with the increase of the content of Fe, the martensitic transformation temperature rapidly decreases, while the ferromagnetism is gradually enhanced for these alloys. Furthermore, both the magnetoresistance and the magnetocaloric effect are also investigated in Fe3 and Fe5 alloys. For an applied magnetic field of 3 T, it is found that the magnetoresistance effects of two samples are about -46% and -15%, while their isothermal entropy changes are about 6 J·kg-1 and 9.5 J·kg-1·K-1 during reverse martensitic transformation, respectively. Accompanied with the disappearing of a very wide transforming range and a slight magnetic hysteresis loss, the net refrigerating capacity of Fe3 sample reaches 96 J·kg-1 in the process of reverse martensitic transformation.
Microstructure changes of amorphous polymer film induced by friction
Authors: Duan Fang-Li  , Wang Ming  , Liu Jing  ,   State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400030, China
Published: December 2020

The sliding friction between a rigid tip and an amorphous polymer film is studied using large scale molecular dynamics simulation. We focus on the changes of surface microstructure on the polymer film caused by friction, and study the effects of the interaction between tip and substrate, the sliding speed and the molecular chain length on the change of surface microstructure. When there is an adhesive force between tip and substrate, the bond reorientation caused by friction occurs in the sliding region of polymer substrate, and radius of gyration of the molecular chains on the surface layer of polymer substrate elongates along the sliding direction. Moreover, the extent of surface microstructure changes increases with the decrease of sliding speed. During the process of microstructure changes caused by friction, the chain loops and chain ends make different contributions, leading to different deformation mechanisms of molecular chain. The drag action between the tip and chain end monomers plays a more important role in making molecular chains deformation, when the degree of entanglement of polymer substrate becomes greater or when the sliding speed of tip becomes lower. Our results also show that change of surface microstructure is a key mode of friction energy dissipation in this tip and polymer film tribology system.
Effects of uniform disorder on polaron dynamics in conjugated polymers
Authors: Yuan Xiao-Juan  , Yuan Hui-Min  , Zhang Cheng-Qiang  , Wang Wen-Jing  , Yu Yuan-Xun  , Liu De-Sheng  ,   College of Physics and Electronic Engineering, Qilu Normal University, Zhangqiu 250200, China;,   School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
Published: December 2020

Within the framework of the Su-Schrieffer-Heeger model modified to include uniform disorder and an external electric field, the polaron transport process in conjugated polymer material is simulated using a nonadiabatic evolution method. It is found that the polaron dynamic mechanism is determined by both the electric field and the uniform disorder. The effect of uniform disorder is not obvious and almost negligible in most cases, except for the case of very weak electric field. Compared with the effects of Gaussian disorder, the film morphology with uniform disorder is conductible to the polaron transport.
Design and study of frequency selective surface based on hybrid period metallic mesh
Authors: Zhang Jian  , Gao Jin-Song  , Xu Nian-Xi  , Yu Miao  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
Published: December 2020

Frequency selective surface based on metallic mesh can realize the physical properties of both high infrared transmittance and millimeter-wave band-pass filter. In order to improve the optical transmittance, reduce surface resistance and suppress the effect of high order diffraction energy on the imaging quality of the optical system, a new design of frequency selective surface based on hybrid period metallic mesh is obtained. In this paper, the diffraction intensity distribution and surface current of frequency selective surface are analyzed based on metallic mesh. Simulation and experimental results show that frequency selective surface based on hybrid period metallic mesh realizes a stable millimeter-wave band-pass filter property, at the same time, it obtains 5% increase of infrared transmittance and 4 Ω reduce of surface resistance. New design of frequency selective surface based on hybrid period metallic mesh effectively suppresses the effect of high order diffraction energy on the imaging quality of the optical system.
Effect of different annealing treatment methods on the Ni/SiC contact interface properties
Authors: Lu Wu-Yue  , Zhang Yong-Ping  , Chen Zhi-Zhan  , Cheng Yue  , Tan Jia-Hui  , Shi Wang-Zhou  ,   Key Laboratory of Optoelectronic Material and Device, Shanghai Normal University, Shanghai 200234, China
Published: December 2020

Nickle ohmic contacts on the Si-face of n-type 4H-SiC are prepared by both rapid thermal annealing (RTA) and laser spark annealing (LSA). The effects of the different annealing procedures on the cathode surface morphology, cathode/substrate cross sectional morphology, element composition, microscopic structure of carbon clusters in the SiC substrate near surface, are characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), transmission electron microscopy (TEM), and Raman spectra, respectively. The tests and analyses show that both thermal treatments can help to form ohmic contacts. The specific contact resistances of RTA sample and LSA sample are measured to be 5.2× 10-4 Ω ·cm2 and 1.8× 10-4Ω·cm2 by transmission line model, respectively. The Ni film of RTA sample shrinks badly thus forms tiny islands on the surface, while the surface of LSA sample remains relatively smooth. The root-mean-square (RMS) values of surface roughness of the Ni films of as-deposited, RTA and LSA samples are 8.65 nm, 91.3 nm and 17.5 nm, respectively. The Ni/SiC interface of RTA sample corrodes badly, and Si can be found in the whole Ni film, indicating an overall consumption of Ni to react with Si forming NiSi compounds; C atoms, which do not react with Ni atoms，cluster to the average size of about 40 Å, and gather approximately as a layer located about 20-30 nm off the Ni/SiC interface. The Ni/SiC interface of LSA sample is relatively smooth, and a small quantity of Ni atoms diffuse into the SiC wafer, forming lots of ternary phase diffusion zones of about tens of nanometers deep into the SiC wafer, in which C, Si, Ni atoms are distributed uniformly; the average size of C clusters is smaller than that in RTA sample and no obvious C enriched zone was found, while neither Si atom nor C atom is found to diffuse into the Ni film.#br#The ohmic contacts prepared by LSA have obvious advantages compared with those by RTA in many aspects such as cathode surface morphology, interface morphology, uniformity of components in cathode films, etc. All the results mentioned above make LSA a promising method of thermal treatment in preparation of ohmic contacts.
New folding lateral double-diffused metal-oxide-semiconductor field effect transistor with the step oxide layer
Authors: Duan Bao-Xing  , Li Chun-Lai  , Ma Jian-Chong  , Yuan Song  , Yang Yin-Tang  ,   Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In order to design the power devices with the low loss required for the power integrated circuits (PIC), a new folded silicon LDMOS with the folding step oxide layer (SOFLDMOS) is proposed in this paper for the first time. In this structure, the step oxide layer is covered on the folded silicon surface with a periodic distribution. The surface electric field is optimized to be uniform by introducing a new electric field peak due to the electric field modulation effect by the step oxide layer. The breakdown voltage is improved to solve the breakdown voltage limitation problem in FALDMOS. Obtained in virtue of the ISE simulation are the results that the silicon limit is broken by applying the effects of the electric field modulation, accumulation of majority carriers, and conductive silicon region multiplier in the proposed SOFLDMOS. The saturation current of the drain electron is increased by about 3.4 times compared with that of the conventional LDMOS. When the breakdown voltage is 62 V, an ultra-low specific on-resistance of 0.74 mΩ·cm2 is obtained, which is far less than 2.0 mΩ·cm2 in the conventional LDMOS with the same breakdown voltage. The low loss requirements is achieved for the PIC with the low voltage region by the proposed SOFLDMOS.
The microstructure and optical properties of SiNx deposited by linear microwave chemical vapor deposition
Authors: Zhang Jian  , Ba De-Chun  , Zhao Chong-Ling  , Liu Kun  , Du Guang-Yu  ,   School of Machinery and Automation, Northeastern University, Shenyang 110004, China;,   SKY Technology Development Co., Ltd. Chinese Academy of Sciences, Shenyang 110179, China
Published: December 2020

SiNx films are synthesized on Si substrates in a home-made linear microwave plasma enhanced chemical vapor deposition system at different microwave powers, duty cycles, substrate temperatures, and ratios of silane (SiH4) flow to ammonia (NH3) gas flow. The effects of technological parameters on morphology of film surface, stoichiometric proportion, refractive index and deposition rate of SiNx film are characterized by scanning electron microscopy (SEM) and elliptical polarization instrument, and the relationships among stoichiometric proportion, refractive index and deposition rate are investigated. The results from SEM analysis indicate that the surfaces are smooth and the elements are homogeneously distributed in the films obtained under different deposition parameters. The ratio of SiH4 flow to NH3 gas flow and the duty cycle are the most critical factors determining the refractive index which can be changed from 1.92 to 2.33. The thickness measurements show that the deposition rate of SiNx film is affected by microwave power, duty cycle, substrate temperature and flow ratio. The maximum deposition rate achieved in the paper is 135 nm·min-1.
Influences of medium and temperature on the shear thickening behavior of nano fumed silica colloids
Authors: Shan Lei  , Tian Yu  , Meng Yong-Gang  , Zhang Xiang-Jun  ,   State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Published: December 2020

The influences of medium and temperature on the shear thickening behavior of silica colloids are investigated. The nano fumed silica colloids in four media (ethylene glycol, polyethylene glycol 400, propylene glycol, and polypropylene glycol 400) exhibit continuous or discontinuous shear thickening behaviors. With the increase of temperature, the medium viscosity decreases, thus the apparent viscosity of colloids decreases. The relationship between the critical viscosity of shear thickening and temperature is well described by the Arrhenius equation. The ratio of viscosity of colloids to medium visocosity is used to scale the steady-shear rheological curves of the colloids under various temperatures. In the shear thinning regime at low shear rate, the form of rheological curve is independent of medium viscosity but correlates with the chemical properties of dispersing medium. In the shear thickening regime at high shear rate, a higher medium viscosity results in stronger shear thickening behavior.
Influence of time delay on the memory in a gene regulatory circuit
Authors: Yu Wen-Ting  , Tang Jun  , Luo Jin-Ming  ,   College of Science China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

Biological memory is a ubiquitous phenomenon, which could be found in a variety of biological subsystems. Based on a model of dual feedback gene regulatory circuit, in this paper we investigate the influence of time delay on memory time. The results show that the memory time is enhanced dramatically due to the existence of time delay, and the memory time increases linearly with increase of time delay. This enhancement pattern is completely different from that induced by noise. The raising of biological memory by time delay and noise can be controlled and reinforced mutually without affecting the reinforcement mode of opposite side.
Progress of application research on Cu2ZnSnS4 thin film and its device
Authors: Liu Hao  , Xue Yu-Ming  , Qiao Zai-Xiang  , Li Wei  , Zhang Chao  , Yin Fu-Hong  , Feng Shao-Jun  ,   School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384, China;,   Tianjin Institute of Power Sources, Tianjin 300384, China
Published: December 2020

Recently, Cu2ZnSnS4 (CZTS) has emerged as one of the most promising thin film materials due to its being environment friendly, abundant in storage and low cost. To date, solar cell with up to 12.6% efficiency have been reached with using Cu2ZnSn(S, Se)4 (CZTSSe) absorber by hydrazine solution method. In this paper, the structural, optical, electrical, interface layer properties of CZTS thin films are introduced and the effect of sodium diffusion on the CZTS thin film is also discussed. Furthermore, different methods to fabricate CZTS thin films and the corresponding device performances are discussed. Finally, the existing problems and future researches are summarized.
A finite volume method for pricing the American lookback option
Authors: Zhang Qi  , Zhang Ran  , Song Hai-Ming  ,   Department of Mathematics, Jilin University, Changchun 130012, China
Published: December 2020

Due to the characteristic of risk aversion, option has become one of the most fashionable derivatives in the financial field. More and more investigators are attracted to devote themselves to exploring the option pricing problem. In this paper, we are concerned with the valuation of American lookback options in terms of the Black-Scholes model. It is well known that the American lookback option satisfies a two-dimensional nonlinear partial differential equation in an unbounded domain, which couldn't be numerically solved directly. Based on the analysis of the issues for solving this problem, this paper introduces an approach to settle it. First, we transform the problem into a one-dimensional form by the numeraire transformation. And then, the Landau's transformation is applied to normalize the defined domain. For the nonlinear feature of the resulting problem, we propose a finite volume method coupled with Newton iterative method to obtain the optional value and the optimal exercise boundary simultaneously. We also give a proof on the nonnegativity of the numerical solutions under some appropriate assumptions. Finally, some numerical simulations are presented using the proposed method in this paper. Comparing with the binomial method, we can conclude that the proposed method is an effective one, which provides a theoretical basis for practical applications.
Deterministic directional transport of asymmetrically coupled nonlinear oscillators in a ratchet potential
Authors: Ji Yuan-Dong  , Tu Zhe  , Lai Li  , Luo Mao-Kang  ,   College of Mathematics, Sichuan University, Chengdu 610065, China;,   School of Aeronautics and Astronautics, Sichuan University, Chengdu 610065, China
Published: December 2020

In the absence of external force and noise, a deterministic transport model for asymmetrically coupled nonlinear oscillators in a ratchet potential is established. By numerical simulation, both directed current and reversely directed current can be obtained by selecting appropriate parameters. The complex dependences of current velocity on the model parameters are discussed. It is observed that the average velocity of the particle chain varies non-monotonically with coupling strength and potential height, indicating a generalized resonance phenomenon. When the other parameters are fixed, the speed curve which is dependent on spring free length has a roughly inverse symmetry, and there also exists a generalized multi-peak resonance.
Infrared absorption characteristics of solid nitrogen at near-triple point temperatures
Authors: Cao Shan  , Liu Jiang-Ping  , Li Jun  , Wang Kai  , Lin Wei  , Lei Hai-Le  ,   Department of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China;,   Research Centre of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The smooth, uniform, and transparent solid nitrogen-molecular film was grown by applying the slow thermal cycles near the triple-point temperature to the growth process in our home-made liquid/solid preparation apparatus. The infrared absorption spectra of solid nitrogen at near-triple point temperature are measured by the infrared spectroscopy system. A broad absorption band can be observed from 2222 to 2439 cm-1 with the strongest peak at 2288 cm-1. This has been well explained theoretically on the basis of the ground-state vibration and the coupling between the ground-state vibration and rotation at low temperatures within the framework of anharmonic approximation.
Terahertz spectrum and simulation of the phase transformation of FOX-7
Authors: Meng Zeng-Rui  , Zhang Wei-Bin  , Du Yu  , Shang Li-Ping  , Deng Hu  ,   Institute of Chemical Materials, CAEP, Mianyang 621900, China;,   School of Information Engineering, Southwest University of Science and Technology, Mianyang 621010, China;,   Terahertz Research Center, CAEP, Mianyang 621900, China;,   Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010, China
Published: December 2020

1, 1-diamino-2, 2-dintroethylene (FOX-7) is a novel explosive of high energy and low sensibility. In order to study the effect of temperature changes on the molecular structural characteristics of the explosive, its absorption spectra in the frequency range of 0.2–2.5 THz at a constant rate of heating from 298 K to 393 K are detected by terahertz time-domain spectroscopy (THz-TDS). Results show that a number of characteristic absorption peaks with different intensities appear at 1.59–2.13 THz when the temperature is 298 K, while the absorption spectra change with the increase of temperature of the explosive sample; a new characteristic absorption peak located at 1.12 THz appears at 384 K, and its absorption peak intensity gradually increases, but disappears when the temperature drops to 298 K. The absorption spectra of FOX-7 molecular crystal at 298 and 393 K within the 0.2–2.5 THz region based on density functional theory (DFT) are also simulated by using Materials Studio 6.0 software in this article, and the simulated results agree well with the experimental data. In addition, the vibrational modes of the characteristic peaks of two kinds of crystalline in the experimental absorption spectra are analyzed and identified, showing that the formation of the characteristic absorption peaks is closely related to the molecular vibration, and the molecular structure may change under the influence of temperature, and the tautomeric polymorphism of the crystalline has different vibrational modes. This article indicates that the process of phase transformation of FOX-7 starts from 384 K, and this process is reversible; the characteristic absorption peak at 1.12 THz is composed of two kinds of vibrations (the swinging and torsional vibrations of the nitro and amido groups).
A passive source ranging method using the waveguide-invariant-warping operator
Authors: Qi Yu-Bo  , Zhou Shi-Hong  , Zhang Ren-He  , Ren Yun  ,   State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China;,   College of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on the relationship between the horizontal wavenumber difference of two modes and the waveguide invariant in a range-independent shallow water waveguide, a frequency-warping operator is proposed for the autocorrelation function of the received signal. This operator can transform the cross-correlation functions of two different modes in the signal autocorrelation function into separable impulsive sequences. With a guide source providing the dispersive characteristics of the waveguide, the source range can be extracted from the relative delay time of the impulsive sequence using a single hydrophone. The availability of the waveguide-invariant-warping operator in the passive source range estimation is verified by simulated and experimental data.