bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical and experimental study of the nonlinear ultrasonic field radiated from a conical focused PVDF transducer
Authors: Yu Jie  , Zhang Dong  , Liu Xiao-Zhou  , Gong Xiu-Fen  , Song Fu-Xian  ,   南京大学声学研究所，近代声学重点实验室，南京 210093
Published: December 2020

Conical transducer offers both good lateral resolution and large depth of detecting region for ultrasonic imaging. In this paper, the superposition of Gaussian beams is utilized to simulate the source distribution of the conical focused transducer. On the basis of the KZK equation, we obtain the analytical solution of the nonlinear sound field from the conical focused source. A conical focused PVDF transducer has been fabricated in our Lab and the sound field distributions of the fundamental and second harmonic components were experimentally measured. The measured results are in reasonably good agreement with the theoretical predictions.
M-ary chaotic spread spectrum Pattern time delay shift coding scheme for multichannel underwater acoustic communication
Authors: Yin Jing-Wei  , Hui Jun-Ying  , Wang Yi-Lin  , Hui Juan  ,   哈尔滨工程大学水声工程学院，哈尔滨 150001
Published: December 2020

Pattern time delay shift coding scheme uses the time delay shift values of the Pattern to code the information whose anti-ISI (intersymbol interference) ability is related to the kind and duration of the Pattern. Spread spectrum communications is competent for long-range underwater acoustic communications for its spread spectrum gain, but the low communications rate seriously restricts its application. The proposed new scheme is adapted to the underwater acoustic environment, which integrates the spread spectrum with Pattern time delay shift coding and works at M-ary mode spread spectrum and several communications channels. The scheme could achieve good performance of the spread spectrum and also improve the data transfer rate. The results of lake trial show that the M-ary chaotic spread spectrum Pattern time delay shift coding scheme is robust and feasible.
The characteristics of 20 μm-diameter single droplets
Authors: Li Han-Ming  , Liu Feng  , Li Ying-Jun  , Zhang Yi  , Zhang Zhe  , Bernhardt Jens  , Renaud Perez  , Cheng Tao  , Li Yu-Tong  , Zhang Jie  ,   (1)中国科学院物理研究所光物理实验室，北京 100080; (2)中国科学院物理研究所光物理实验室，北京 100080；中国矿业大学，北京 100083
Published: December 2020

As a prospective target material, micro-droplet is of great interest. In this paper, the characteristics of the 20μm-diameter singledroplets are measured by means of shadowgraphs. The detailed process of the droplet formation is observed. Meanwhile, the droplet parameter, backing pressure, modulation amplitude and frequency are optimized to attain the conditions to realize droplets with uniform spatial distribution.
The moments analysis of the pulse propagation through plasma medium and its applications
Authors: Zhang Min  , Wu Zhen-Sen  ,   西安电子科技大学理学院，西安 710071
Published: December 2020

Based on the theory of wave propagation and scattering in random medium, the analysis method of the pulse propagating in the plasma medium is presented. Under the condition of strong fluctuations, we have deduced the two-frequency second moment and fourth moment equations, and calculated the two-frequency intensity correlation function and scintillation index in terms of the different electron density spectra. The statistical parameters of the self-correlation function, the correlation bandwidth and time are obtained, in order to provide a basis for studing the characteristic of the pulse propagation in plasma medium.
Mechanism and numerical simulation of laser-target impulse coupling in vacuum
Authors: Yang Yan-Nan  , Yang Bo  , Zhu Jin-Rong  , Shen Zhong-Hua  , Lu Jian  , Ni Xiao-Wu  ,   (1)南京航空航天大学理学院，南京 210016；南京理工大学理学院，南京 210094; (2)南京理工大学理学院，南京 210094; (3)南京理工大学理学院，南京 210094；扬州大学物理科学与技术学院，扬州 225002
Published: December 2020

The impulses of vaporized target material with solid target are measured by using the intense pulse of Q-Nd:YAG laser irradiating the solid target in quasi-vacuum. Analyzing the interaction mechanism of laser with target and vaporized target material, numerical calculation of impulse acting on the target with different laser intensity is performed with fluid dynamics theory and three-dimensional difference scheme. The comparison and analysis are performed between numerical and experimental results. The experimental results are given a reasonable explanation further. It is shown from the consistency between numerical results and experimental results that the numerical calculation model used in this paper can represent the mechanical response of the target to the laser.
Analytic equations of state and thermo-physical properties for the α, β, and γ-Si3N4
Authors: Zhang Chao  , Sun Jiu-Xun  , Tian Rong-Gang  , Zou Shi-Yong  ,   电子科技大学物理电子学院，成都 610054
Published: December 2020

The Einstein model to consider thermal effect in universal equations of state is modified, and an approach to solve parameters at absolute zero temperature from experimental data at a reference temperature is proposed and applied to the Baonza equation. The thermal Baonza equation is applied to study thermo-physical properties of α, β and γ-Si3N4. Through analyzing experimental data in literature, the input data-set for the three phases are determined. The results calculated from the thermal Baonza equation is in agreement with available experimental data.
First-principles study of structural instability and polarization in BaTiO3/SrTiO3 superlattice
Authors: Zhu Zhen-Ye  , Wang Biao  , Zheng Yue  , Wang Hai  , Li Qing-Kun  , Li Chen-Liang  ,   (1)哈尔滨工业大学航天学院，哈尔滨 150001; (2)哈尔滨工业大学航天学院，哈尔滨 150001；中山大学理工学院光电材料和技术国家重点实验室，光电功能复合材料所，广州 510275
Published: December 2020

We investigated structural instability and polarization of BaTiO3/SrTiO3 superlattice under stress by using first-principles calculation. Our results show that stress induces lattice distortion and charge transfer between Ti atom and O atom. With stress increasing，atomic displacement in BaTiO3/SrTiO3 superlattice grows gradually，resulting in the enhancement of polarization. Furthermore，polarization of superlattice BaTiO3/SrTiO3 can be controlled by changing the stress.
Effects of optimized contact scheme on the performance of high-power GaN-based light-emitting diodes
Authors: Zhang Jian-Ming  , Zou De-Shu  , Xu Chen  , Gu Xiao-Ling  , Shen Guang-Di  ,   北京工业大学北京市光电子技术实验室，北京 100022
Published: December 2020

Due to the lateral current transport in the mesa-structure GaN based LEDs，the resistance of the n-type material of the GaN and lower confinement layer is not negligible for large area and high applied current density applieations，which causes the current spreading nonuniformly along the lateral direction. With an optimized contact scheme to reduce the length for the lateral current transport，two different kinds of contact schemes of high-power GaN-based flip-chip LEDs (FCLEDs) are fabricated. It is shown that the forward voltage of this FCLED with interdigitated contact scheme is 3.35V at forward current 350mA，and exceeds that of FCLEDs with optimized ring-shaped interdigitated contact scheme by 0.15V. Although the light emitting area of FCLEDs with optimized ring-shaped interdigitated contact scheme is slightly smaller than that of FCLEDs with interdigitated contact scheme，it is found that the light output from the former is larger than that from the later at higher injection currents. Furthermore，the light output from the FCLEDs with optimized ring-shaped interdigitated contact scheme saturates slowly at higher injection currents as compared to the FCLEDs with interdigitated contact scheme，indicating that the saturation behavior of the FCLEDs with interdigitated contact scheme is more pronounced. It is confirmed that an optimized contact scheme，which leads to the more uniform current spreading，can decrease joule heat generated and considerably improve the electrical and optical characteristics of the FCLEDs.
The transport property of two dimensional electron gas in AlGaN/AlN/GaN structure
Authors: Zhou Zhong-Tang  , Guo Li-Wei  , Xing Zhi-Gang  , Ding Guo-Jian  , Tan Chang-Lin  , Lü Li  , Liu Jian  , Liu Xin-Yu  , Jia Hai-Qiang  , Chen Hong  , Zhou Jun-Ming  ,   (1)北京凝聚态物理国家实验室，中国科学院物理研究所表面物理国家重点实验室，北京 100080; (2)中国科学院微电子研究所化合物半导体器件实验室，北京 100029
Published: December 2020

Variable temperature Hall effect measurement was performed on the AlGaN/AlN/GaN structure with AlN interlayer grown on sapphire by metalorganic chemical vapor deposition. It was measured that the mobility and density of the two dimensionalelectron gas at the interface of AlN/GaN were 1.4×104cm2·V-1·s-1 and 9.3×1012cm-2 at 2K，respectively. Low temperature variable magnetic field measurement manifested that only a single type of carriers contributed to the conductivity in this structure. Quantum Hall effect was observed in field as low as 3T at 2K. The calculated quantum scattering time of 0.23ps is longer than that of AlGaN/GaN structure. This improvement is attributed to the AlN interlayer which effectively reduces the scattering. In addition，further analysis revealed that the small-angle scattering was important in this structure.
Transient photoresponse in Pr0.7Ca0.3MnO3 thin films at room temperature
Authors: Yan Zi-Jie  , Yuan Xiao  , Xu Ye-Bin  , Gao Guo-Mian  , Chen Chang-Le  ,   (1)华中科技大学光电子科学与工程学院,武汉 430074; (2)西北工业大学理学院,西安 710072
Published: December 2020

Photoresponse characteristics of Pr0.7Ca0.3MnO3 thin films were investigated under different applied voltages and excitation light energy densities at room temperature.The transient resistance change of 92.3% and response time of～36ns were observed under the excitation with a 532 nm laser pulse of 7ns duration at a light energy density of 275.16mJ/cm2.Both the resistance change and response time showed nonlinear behavior as a function of the light energy density, and the resistance and the response time were reduced when the intensity increased. However, the applied voltage had almost no effect on the photoresponse at room temperature. The phenomena are explained in terms of the photoinduced nonequilibrium insulator-to-metal transition in the film, which may have potential applications in optoelectronic devices.
Experimental study and analysis of energy evolution of liquid foam drainage in one dimension
Authors: Huang Jin  , Sun Qi-Cheng  ,   中国科学院过程工程研究所,北京 100080
Published: December 2020

Liquid foam is a dense packing of gas bubbles in a small amount of surfactant liquid, which has well-organized structure and behaves as typical soft condensed matter. Forced drainage is the flow of constantly input liquid through the network of interstitial channels between bubbles in foams under actions of gravity and capillarity, which is one of major mechanisms causing liquid foam evolution. Firstly in this paper, we improved the newly proposed method introduced by Hutzler et al. (2005) by considering the light transmission ratio to eliminate the incident light intensity discrepancy along the one dimensional foam formed within a slender Hele-Shaw silicon rectangular tube. After the film rupture and the bubble coarsening were carefully slowed down, forced foam drainages in one dimension were studied by using the improved light scattering technique. We found that the characteristic quantities, such as the drainage wave front velocity and liquid fraction evolution, are consistent with traditional foam drainage results based on Poiseuille-type flow assumption in Plateau borders. And the light transmission ratio is found not to be the reciprocal of the liquid fraction as similar with the transmission probability in diffuse-transmission spectroscopy technique, but prevails the relationship T=0.293+1.038e-29.39(0.01<0.13). We then deduced the viscous energy of foams based on Kelvin cell structure during forced drainage process and calculated the surface energy of foam using the software of Surface Evolver. The evolution of the two kinds of energy at local area of foam was predicted based on the quasi-static assumption of Kelvin cell structure evolution along with liquid fraction variation. The study of foam drainage from a view of energy will be useful in the further study on foam drainage and foam stability control in various applications.
Some new limiting vesicles and typical phase transforms and abruptions processes studied using the spontaneous-curvature model
Authors: Zhou Xiao-Hua  , Zhang Shao-Guang  , Yang Ji-Qing  , Qu Xue-Min  , Liu Yuan-Sheng  , Wang Si-Gang  ,   (1); (2)第四军医大学数理教研室，西安 710032
Published: December 2020

Through building several multi-symmetric initial shapes in Surface Evolver software, after refining them and doing a long time of evolvement step by step, we obtained some new budding vesicles with small energy whose coefficients are consistent with the theoretical values. Through changing the coefficient and scanning the direction of different shapes, we found a discontinuous phase transition and a reversible continuous phase transition and two new stable shapes. Furthermore, we obtained two kinds of starfish shaped abruption processes which have been supported by experiment.
Numerical modeling of seismic wavefield in anisotropic viscoelastic porous medium with the pseudo-spectral method
Authors: Du Qi-Zhen  , Liu Lian-Lian  , Sun Jing-Bo  ,   中国石油大学(华东)地球资源与信息学院，东营 257061
Published: December 2020

In order to describe the reservoirs more accurately, the characteristics of the earth medium must be considered comprehensively, such as the anisotropy, viscoelasticity and pore, etc. Consequently, an anisotropic viscoelastic porous medium model is presented in this paper, and the elastic wave equation in this medium has been derived. The seismic wavefield numerical modeling was simulated by using the pseudo-spectral method. Synthetic seismograms are used to show the characteristics of the seismic wave in complex medium. The research work is useful to understanding seismic wave propagation in earth medium.
Analysis of the functional relationship between the large-scale circulations and meso-scale convective systems
Authors: Zhang Wen  , He Wen-Ping  , Zou Ming-Wei  , Feng Guo-Lin  ,   (1)兰州大学大气科学学院，兰州 730000；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京 100029; (2)扬州大学物理科学与技术学院，扬州 225009；兰州大学大气科学学院，兰州 730000; (3)扬州大学物理科学与技术学院，扬州 225009；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京 100029；国家气候中心，中国气象局气候研究开放实验室，北京 100081
Published: December 2020

The climate system is a chaotic, hierarchical open nonlinear system. The system of higher level dominates the behavior of the lower one and determines the basic configuration of climate change. Generally, what the observational data record is the output of lower layer system which necessarily contains the information of interaction between different levels. How to extract information of higher level system from observational data has been a hotspot in the research of nonlinear spatio-temporal distribution theory and methods of observational data processing. A unified form ulation of the climate system has not yet been established. For the convenience of study, in this paper we use a two-level model comprising the Logistic model and Lorenz model, and analyze the output of lower level system through power spectrum and wavelet analysis under different control parameter and obtain the scaling rules for extracting information of the higher level system.
New vortex solutions of Jackiw-Pi model
Authors: Li Yong-Qing  , Li Xi-Guo  , Liu Zi-Yu  , Luo Pei-Yan  , Zhang Peng-Ming  ,   (1)中国科学院近代物理研究所，兰州 730000；兰州重离子加速器国家实验室原子核理论中心，兰州 730000; (2)中国科学院近代物理研究所，兰州 730000；中国科学院研究生院，北京 100049
Published: December 2020

Based on current φ-mapping topological theory,　a kind of self-dual equations in Jackiw-Pi model are studied. We first obtain explicit, self-dual solutions that satisfy Liouville equation which contains δ-function. Then we get perfect vortex solutions which reflect the system's internal topological structure, and consequently the quantization of flux.
Mei conserved quantities for systems with unilateral non-Chetaev nonholonomic constraints in the event space
Authors: Jia Li-Qun  , Luo Shao-Kai  , Zhang Yao-Yu  ,   (1)江南大学理学院,无锡 214122; (2)平顶山学院电气信息工程学院,平顶山 467002; (3)浙江理工大学数学力学与数学物理研究所,杭州 310018
Published: December 2020

Mei symmetry and Mei conserved quantity for a system with unilateral non-Chetaev nonholonomic constraints in the event space are studied. The differential equations of motion of the system are established. The definition and the criteria of Mei symmetry, weakly Mei symmetry, strongly Mei symmetry for the system are given in this paper. The existence condition and the expression of Mei conserved quantity are deduced directly from Mei symmetry. An example is given to illustrate the application of the results.
Properties of geometric phase under Galilean transformation
Authors: Zheng Ying-Hong  , Chen Tong  , Wang Ping  , Chang Zhe  ,   中国科学院高能物理研究所，北京 100049
Published: December 2020

Properties of geometric phase under Galilean transformation are investigated within a general framework. We found that the geometric phase in the system commonly met with in the laboratory is Galilean invariant. However, this is not always true for general non-relativistic quantum systems. The physical origins of the frame dependence of geometric phase is discussed in detail. We emphasize that the change of geometric phase caused by Galilean boosts does not destroy the results of measurement for two-state interference. It is consistent with the general constraint of Galilean invariance on a non-relativistic quantum system.
Time-delayed feedback control of chaos in BOOST converter and its optimization
Authors: Lu Wei-Guo  , Zhou Luo-Wei  , Luo Quan-Ming  , Du Xiong  ,   重庆大学电气工程学院高电压与电工新技术教育部重点实验室，重庆 400044
Published: December 2020

The output time-delayed feedback control (TDFC) was introduced into the control prototype of the current-mode BOOST converter. Firstly, the discrete iteration model of the controlled system was set up, and its Jacobian matrix was obtained. Based on the analysis of equilibrium point variance and Jacobian matrix eigenvalue trajectory, the range of TDFC feedback gain was determined. According to the convergence of the state variable and duty ratio, the steady-state and dynamic properties of the system were discussed, and the feedback gain of TDFC was optimized. The simulation results confirm that the proposed method is valid and the theoretical analysis holds true.
System size selected effects induced by clustering in two-dimensional coupled cell systems
Authors: Shen Chuan-Sheng  , Zhang Ji-Qian  , Chen Han-Shuang  ,   (1)安徽师范大学物理与电子信息学院,芜湖 241000; (2)安徽师范大学物理与电子信息学院,芜湖 241000；安庆师范学院教育技术系,安庆 246011
Published: December 2020

Using stochastic simulation and chemical Langevin methods, we numerically investigated the influence of clustering of cells on the system size effects in two-dimensional coupled internal noisy cell systems. It was found that, when the system works near the Hopf bifurcation, the systems' cells assemble to a team in forming, a cell cluster. Interestingly, the teamwork in clustering may significantly raise the system's working efficiency, leading to the system obtaining the best performance under external stimulus. Furthermore, for different coupling intensities the optimal cluster size varies in robustness to external stimuli, but the signal-to-noise ratio (SNR) shows an increscent tendency with the coupling intensity increasing. These phenomena illustrate that clustering of cells may greatly enhance the sensitivity of Ca2+ signal, by which the biologic systems would probably improve their capability to respond to external stimulation.
A weighted network model with accelerated evolution
Authors: Qin Sen  , Dai Guan-Zhong  , Wang Lin  , Fan Ming  ,   西北工业大学自动化学院，西安 710072
Published: December 2020

Using the dynamic method to evolve a weighted network, a new weighted network with accelerated attachment of newly added edges is proposed. At each time step, the number of newly added edges is proportional to the size of the network. The degree distribution of the network is discussed. The strength distribution is also obtained, and the analytical relation between the strength and the degrees of nodes is presented. The network shows scale-free property in both theoretical analysis and numerical simulations. In addition, regardless of degree preferential attachment or strength preferential attachment in the evolution process, as long as the weight of edge follows a certain probability distribution, the degree distribution always follows the power-law distribution and its exponent is not related with the attachment mechanism and the specific probability distribution.
Monte Carlo simulation of operating modes of semi-insulting GaAs photoconductive switches
Authors: Shi Wei  , Jia Wan-Li  , Ji Wei-Li  , Liu Kai  ,   (1)西安理工大学应用物理系，西安 710054; (2)西安理工大学应用物理系，西安 710054；中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室，上海 200050
Published: December 2020

An ensemble Monte Carlo simulation method has been employed to study the operating modes of semi-insulated GaAs (SI-GaAs) photoconductive semiconductor switches (PCSS) excited by a femtosecond laser pulse and biased in an electrical field. The results show that, under a bias field lower than the Gunn threshold field (which is 4.2kV/cm for GaAs), or the optical pulse energy is below the optical threshold, the time-resolved current in the switch operates in the linear mode. When the bias field and triggering optical energy are respectively greater than the electrical and optical thresholds, the PCSS operates in the nonlinear mode. The simulation shows that when triggered by laser pulse with higher photon energy, the switch has lower optical threshold in the nonlinear mode. The mechanism of the nonlinear mode for the switch is concluded to be due to the inter-valley scattering of the photo-generated carriers, leading to local high field in the switch.
Colorimetrical study of colloidal CdSe quantum dots
Authors: Chen Ding-An  , Shen Li  , Zhang Jia-Yu  , Cui Yi-Ping  ,   东南大学电子科学与工程学院，先进光子学中心，南京 210096
Published: December 2020

A series of colloidal CdSe quantum dots (QDs) were synthesized, and the photoluminescence (PL) quantum yield of CdSe nanocrystals was found to increase at first and then decrease with increasing size. The chromatic coordinates of samples with different size and different size distributions were calculated to see the influence of size distribution of CdSe QDs. And white QDs sample was prepared by mixing red and blue QDs. The experimental value of chromatic coordinates of the prepared sample coincide with that estimated according to the empirical formula.
Dynamic model of atomic force microscopy in tapping-mode
Authors: Fan Kang-Qi  , Jia Jian-Yuan  , Zhu Ying-Min  , Liu Xiao-Yuan  ,   西安电子科技大学机电工程学院，西安 710071
Published: December 2020

The theoretical model about energy dissipation of atomic force microscopy (AFM) in tapping-mode has great significance for the investigation of the dynamic response of AFM tip influenced by the adhesive force. Based on the Hamaker hypotheses and the Lennard-Jones potential and elastic theory, a novel elastic model is established for adhesive contact between a sphere and a plane. The model shows that the variation of the adhesive force with the distance in the loading process is different from that in the unloading process, i.e., an adhesive hysteresis, which is the indication of energy dissipation of AFM, is engendered in the tapping-mode. On the basis of the adhesive model, the dynamic model of AFM in tapping-mode is established to investigate the variations of the amplitude, phase shift and energy dissipation with the distance between AFM tip and the sample surface. The results obtained by the dynamic model are in agreement with the experimental results available.
Nonlinear spin waves in a Bose condensed atomic chain
Authors: Zhao Xing-Dong  , Xie Zheng-Wei  , Zhang Wei-Ping  ,   (1)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062; (2)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062；四川师范大学物理与电子工程学院，成都 610066
Published: December 2020

The modulational instability (MI) of nonlinear coherent spin waves in an atomic spin chain of spinor Bose-Einstein condensates confined in an optical lattice is studied. Analytically we obtained the criteria for the MI of nonlinear coherent spin waves and its relation with the long-range nonlinear spin coupling. We analysed the MI in the case of blue-detuned and red-detuned opctical lattice respectively. It was found that the long-range nonlinear spin coupling in the optical lattice is due to light-induced and static magnetic field-induced dipole-dipole interaction.
The entanglement states transfer and preservation in the process of two-level atoms interacting with multi-mode light fields
Authors: Wang Ju-Xia  , Yang Zhi-Yong  , An Yu-Ying  ,   (1)西安电子科技大学技术物理学院，西安 710071; (2)西安电子科技大学技术物理学院，西安 710071;渭南师范学院物理系，量子光学与光子学研究所，渭南 714000
Published: December 2020

Using the complete quantum theory，the process of M two-level atoms interacting with M multi-mode light fields with intensity-dependent coupling is studied. It is found that quantum entanglement information can be transferred back and forth or be preserved between the cavity fields and atoms under certain time conditions. The entanglement states of the atoms or the cavities can be transferred when t=π/(2λ). The results are verified by numerically computing the entanglement degree. And it was shown that the entanglement states of the atoms or the cavities can be preserved when t=π/λ.
Quantum key distribution using two-mode squeezd states
Authors: He Guang-Qiang  , Yi Zhi  , Zhu Jun  , Zeng Gui-Hua  ,   上海交通大学电子工程系区域光纤通信网与新型光通信系统国家重点实验室，上海 200240
Published: December 2020

A quantum key distribution scheme using two-mode squeezed states is proposed in this paper. The security of the proposed scheme against beam splitter attack is analyzed using Shannon information theory. The analytical expression of the secret information rate is given in terms of squeezed factor and channel parameters. The mode-mode correlation of two-mode squeezed states guarantees the security of the proposed scheme.
The transmission properties of resonant structure of one-dimension metamaterials
Authors: Li Hai-Yang  , Zhang Ye-Wen  , Wang Peng-Chun  , Li Gui-Quan  ,   (1)同济大学波耳固体物理研究所，上海 200092; (2)同济大学波耳固体物理研究所，上海 200092；同济大学电子与信息工程学院，上海 200092
Published: December 2020

The transmission properties of one-dimension metamaterials characterized by resonance were studied. With theoretic analysis it is shown that the transmission coefficient S21 has either one left-handed passband or two left-handed passbands under certain conditions. The experimental verification of the transmission properties has been realized by the composite right/left-handed transmission line used as a leaky-wave antenna.
Controllable preparation of SnO2 one-dimensional nanostructures by chemical vapor deposition
Authors: Zeng Chun-Lai  , Tang Dong-Sheng  , Liu Xing-Hui  , Hai Kuo  , Yang Yi  , Yuan Hua-Jun  , Xie Si-Shen  ,   (1)量子结构与调控教育部重点实验室，湖南师范大学物理与信息科学学院，长沙 410081; (2)中国科学院物理研究所，北京 100080
Published: December 2020

Using Sn and SnO powder as source material, SnO2 one-dimensional nanostructures (nanowires, nanorods, nanobelt and nanoneedles) with controllable diameters were successfully prepared by chemical vapor deposition. The nanostructure and morphology of the products depend strongly on the proportion of oxygen in the growth chamber, which can be altered by adjusting the proportion of SnO in the source material or the proportion of oxygen in the carrier gas. It is crucial to adjust the relative contents of Sn and O atoms in the region of high temperature growth of the Si wafer during controlled preparation of SnO2 one-dimensional nanostructures. We will also discuss the growth mechanism of SnO2 one-dimensional nanostructures under different growth conditions.
Characteristics of electrical parameters during microarc oxidation of titanium alloys
Authors: Wu Han-Hua  , Long Bei-Hong  , Long Bei-Yu  , Tang Yuan-Guang  , Chang Hong  , Bai Yi-Zhen  ,   (1)大连理工大学物理系，三束材料改性国家重点实验室，大连 116024; (2)吉林大学材料科学与工程学院，长春 130012; (3)吉林大学物理学院，长春 130023
Published: December 2020

The variation of electrical parameters during microarc oxidation (MAO) of titanium alloys at constant voltage has been studied by means of a laboratory-made data acquisition system. Experimental results show that the variation of the cathodic and anodic current amplitudes and effective working current in an electrical loop with the duration of treatment show obviously four stages, and the variation of the coating thickness with the treating time has obviously three stages, and the variations of dynamic forward and backward resistance as well as resistance rate of coatings also show different stages. During MAO process, the dynamic forward resistance is always different from the backward resistance, and the former is generally greater than the latter. Scanning electron microscopy shows that the surface morphology of MAO coatings is porous and varies with treatment time in steps.
Measurements of dimethyl phthalate series by the reed-vibration mechanical spectroscopy for liquids
Authors: Zhou Heng-Wei  , Zhang Jin-Lu  , Huang Yi-Neng  , Ying Xue-Nong  , Zhang Liang  , Wu Wen-Hui  , Shen Yi-Fan  ,   (1)南京大学物理系,固体微结构实验室,南京 210093; (2)新疆大学物理系,乌鲁木齐 830047; (3)伊犁师范学院物理与电子信息学院凝聚态物理与材料设计研究所,伊宁 835000; (4)伊犁师范学院物理与电子信息学院凝聚态物理与材料设计研究所,伊宁 835000；南京大学物理系,固体微结构实验室,南京 210093
Published: December 2020

Dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and dioctyl phthalate series samples were measured by the reed-vibration mechanical spectroscopy for liquids recently invented. The results indicate that the processes of dynamical glass transition, crystallization of the supercooled liquid, crystal-liquid phase transition, and gasification take place successively for the dimethyl phthalate sample in the measured temperature range on heating, but only the glass transition and the gasification appear in the other 3 samples. The above measurements and corresponding analysis show that the reed-vibration mechanical spectroscopy for liquids is a reliable and effective method for the investigation of physical processes in liquid state, so that it could provide physical information of soft condensed matter.
Phase transformations of monocrystalline silicon surface under nanoparticle collision
Authors: Duan Fang-Li  , Wang Jia-Xu  , Luo Jian-Bin  , Wen Shi-Zhu  ,   (1)清华大学摩擦学国家重点实验室，北京 100084; (2)重庆大学机械传动国家重点实验室，重庆 400030
Published: December 2020

The phase transformation and the structure change of the silicon surface are investigated by molecular dynamics simulation of the incidence and recoil of a nanoparticle at the monocrystlline silicon surface. The simulation shows that during the collision process, the impacted region on the silicon surface transforms from diamond structure to a molten state, then goes through the state of supercooled liquid, and finally solidifies into an amorphous phase. Furthermore, the temperature of solidification transformation calculated from the simulation is very close to the glass transition temperature of silicon. The structure changes taking place during the nanoparticles recoiling process are also revealed. Beginning with an instantaneous, highly disordered, and badly depressed supercooled state, the impacted region evolves along the direction to a more ordered and lessdepressed state. These evolutional tendencies are determined by the cooling andunloading process the impacted region undergoes. The amorphous silicon formed after the collision has the average coordination of 5.27, and the fivefold and sixfold coordinated atoms accounts for 61.5% of the whole atoms in the impacted region.
The effects of static electric field on the time-frequency characteristics of high-order harmonic generation
Authors: Hong Wei-Yi  , Cao Wei  , Lan Peng-Fei  , Lu Pei-Xiang  ,   华中科技大学，武汉光电国家实验室，武汉 430074
Published: December 2020

The time-frequency properties of the high-order harmonic generation in the presence of a static electric field are investigated. It is found that an attosecond pulse train with one burst per optical cycle can be extracted by superposing the harmonics near the cutoff. This characteristic can be used to generate isolated attosecond pulse in multi-cycle regime. When the ratio of the laser field to the static field is 0.39, the harmonic spectrum is extended to Ip＋9.1Up, and the harmonics above Ip＋0.7Up are emitted almost in phase. The phase-locked harmonics covering a broad bandwidth are produced, and then a regular attosecond pulse train with the pulse duration less than 100 as is generated.
Comparison of measuring methods of sheet carrier density in AlGaN/GaN heterostructures
Authors: Ni Jin-Yu  , Zhang Jin-Cheng  , Hao Yue  , Yang Yan  , Chen Hai-Feng  , Gao Zhi-Yuan  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件教育部重点实验室，西安 710071
Published: December 2020

Hall measurement with Van der Pauw method and the Capacitance-Voltage(C-V) characteristics method are performed on AlGaN/GaN heterostructures with different Al contents grown on sapphire substrates by metalorganic chemical vapor deposition. It is found that the value of sheet carrier density obtained from Hall measurement is larger than that deduced from C-V carrier density profile, and both values, as well as the difference between them increase with increasing Al content. This result is ascribed to two reasons. On the one hand, Ni/Au Schottky contact deposited on AlGaN/GaN heterostructure changes the surface states of the AlGaN barrier layer. Some electrons in the two-dimensional electron gas (2DEG) are extracted to the void surface donor states, and consequently the 2DEG sheet carrier concentration is reduced. And with the Al content increasing, the more the surface states of the AlGaN layer, the more the electrons are extracted to the void surface donor states. On the other hand, the precision of C-V measurement is influenced by the series resistance, which causes underestimation of the magnitude of the depletion-layer capacitance and hence the carrier concentration.
Modeling analysis of radiation induced conductivity in electrical insulator
Authors: Quan Rong-Hui  , Han Jian-Wei  , Huang Jian-Guo  , Zhang Zhen-Long  ,   (1)中国科学院空间科学与应用研究中心，北京 100080; (2)中国科学院空间科学与应用研究中心，北京 100080；中国科学院研究生院，北京 100049
Published: December 2020

By introducing a new term into the traditional Rose-Fowler-Vaisberg model, The exponential relationship between radiation induced conductivity and dose rate is explained. The evolution of radiation induced conductivity under different radiation conditions are also analyzed. The result indicates that dose rate mainly changes the magnitude of radiation induced conductivity while the long-time decay of radiation induced conductivity is determined by carrier recombination rate of the material.
Band gap Narrowing in heavily B doped Si1－xGex strained layers
Authors: Yao Fei  , Xue Chun-Lai  , Cheng Bu-Wen  , Wang Qi-Ming  ,   中国科学院半导体研究所集成光电子国家重点实验室，北京 100083
Published: December 2020

This paper presents a comprehensive study of the effect of heavy B doping and strain in Si1-xGex strained layers. On the one hand, bandgap narrowing (BGN) will be generated due to the heavy doping, on the other hand, the dopant boron causes shrinkage in the lattice constant of SiGe materials, thus will compensate for part of the strain. Taking the strain compensation of B into account for the first time and uesing the with semi-empirical method, the Jain-Roulston model is modified. And the real BGN distributed between the conduction and valence bands is calculated, which is important for the accurate design of SiGe HBTs.
Analytical model for the surface electrical field distribution of double RESURF device with surface implanted P-top region
Authors: Li Qi  , Li Zhao-Ji  , Zhang Bo  ,   电子科技大学IC设计中心，成都 610054
Published: December 2020

An analytical model for the surface electrical field distributions of double RESURF devices with Gaussian-doped P-top region is presented. Based on solvisng the 2-D Poisson equation, the model gives the closed form solutions of the surface potential and electrical field distribution as functions of the structure parameters and drain bias. The dependence of breakdown voltage on drift region length and thickness is calculated. An effectual way to get the optimum high-voltage devices is also proposed. All analytical results are well verified by simulation results obtained by MEDICI and previous experimental data, showing the validity of the presented model.
The influence of distribution of Na+-dopant on the structure and dielectric properties of Ba0.25Sr0.75TiO3 thin film
Authors: Zhou Qi-Gang  , Zhai Ji-Wei  , Yao Xi  ,   (1)同济大学 功能材料研究所,上海 200092; (2)同济大学功能材料研究所,上海 200092；乐山师范学院物理与电子信息科学系,四川乐山 614004
Published: December 2020

Na+-doped and compositional graded doped Ba0.25Sr0.75TiO3 thin films were grown on Pt/Ti/SiO2/Si substrates by Sol-Gel technique. The dielectric properties of thin films were investigated as a function of Na+ doping level. It is revealed that with the increase of Na+ concentrations both the dielectric constant and the loss decrease continuously while the leakage current initially decreases (Na+< 2.5mol%) and then increases. The increase of leakage current may be caused by the formation of porous structure which was confirmed by field emission scanning microscopy (FE-SEM). The improvement of overall dielectric properties were achieved by using the compositional graded doping which results in a better microstructure in the film.
Fabrication and characteristics of long MgB2 wire with high superconducting properties
Authors: Yu Zheng-Guang  , Ma Yan-Wei  , Wang Dong-Liang  , Zhang Xian-Ping  , Gao Zhao-Shun  , Watanabe K.  , Huang Wei-Wen  ,   (1)日本东北大学金属材料研究所，仙台980-8577，日本; (2)中国科学院电工研究所应用超导实验室，北京 100080; (3)中国科学院物理研究所，北京 100080
Published: December 2020

Appling the in situ powder-in-tube method, 11 meter long Fe-sheath MgB2 superconducting wires with outer diameter 1.75mm were fabricated, using 99.5% Mg powder and 99.9% amorphous boron powder doped with 30 nm SiC powder as starting materials. This procedure begins with ball-milling of the mixture powder immersed in acetone solution in a jar and subsequently drying in vacuum. Then the iron tube loaded with the powder mixture was grooved, swaged and drawn to the final wire size. The transition temperature, microstructure, lattice constant and chemical element distribution were evaluated by SQUID, XRD, SEM and EDS, respectively. It was found that TC(onset) and ΔTC are 35.1K and 5.3K, respectively. All samples containing a small amount of MgO, exhibit rather uniform microstructure. Besides, by nano-SiC doping, the MgB2 lattice distortion due to substitution of boron by carbon, results in forming effective flux pining centers, which significantly improves the critical current, and the C element was uniformly distributed in the MgB2 matrix. The standard four_probe measurement shows that all the 10 sample points, which were evenly cut at 1 meter intervals of the 11 meter length wire, have good superconducting homogeneity with critical current values fluctuating within 10% under the applied fields vavying from 10 to 18 Tesla, and all Jc values are above 104A/cm2, with the highest value reaching 1.2×104A/cm2 at 4.2K and 10T.
Characteristics of luminescent nc-Si/SiO2 multilayers and the influence of annealing in hydrogen
Authors: Xia Zheng-Yue  , Han Pei-Gao  , Wei De-Yuan  , Chen De-Yuan  , Xu Jun  , Ma Zhong-Yuan  , Huang Xin-Fan  , Chen Kun-Ji  ,   南京大学物理系，固体微结构物理国家重点实验室，南京 210093
Published: December 2020

Plasma enhanced chemical vapor deposition (PECVD) was used to prepare a-Si:H/SiO2 multilayers. Two-step thermal annealing was then used to transform them into nc-Si/SiO2 multilayers. The size of formed nc-Si (about 4nm) can be controlled and room temperature visible photoluminescence was observed from the annealed samples with the peak located at 750nm. Moreover, we found that annealing in hydrogen can enhance the PL intensity of the materials. The electron paramagnetism resonance (EPR) suggested that annealing in hydrogen atmospheye effectively reduces the nonradiative recombination sites existing in the nc-Si and results in the enhancement of the luminescence efficiency.
Analysis of positron annihilation lifetime in single-walled carbon nanotube bundles
Authors: Chen Xiang-Lei  , Xi Chuan-Ying  , Ye Bang-Jiao  , Weng Hui-Min  ,   中国科学技术大学近代物理系，合肥 230026
Published: December 2020

Superposed-neutral-atom model and the finite-difference method (SNA-FD) is used to calculate the positron annihilation lifetime in single-walled carbon nanotube bundles with different diameters in a large range. We find that in single-walled carbon nanotube bundles，the main area where positron annihilation takes place，the main object that positron annihilates with, as well as the positron annihilation lifetime change regularly as the diameter of single-walled carbon nanotube bundles changes. The positron annihilation lifetime in single-walled carbon nanotube bundles with diameter between 0.8—1.6nm is calculated to be 332—470ps. It agrees well with the experimental result of 394ps.
The application of single-walled carbon nanotubes in field emission display
Authors: Ma Yan-Ping  , Shang Xue-Fu  , Gu Zhi-Qi  , Li Zhen-Hua  , Wang Miao  , Xu Ya-Bo  ,   (1)浙江大学力学系，杭州 310027; (2)浙江大学物理系，杭州 310027
Published: December 2020

Carbon nanotube field emission display has been regarded as one of the most promising flat panel displays due to its unique advantages. The morphology of the cathode material composed of the nanotubes will directly affect the field emission display properties. In this paper, we used single-walled carbon nanotubes synthesized by arc discharge method as the cathode material. This material was printed onto the conducting surface of the cathode plate using a screen-printing process. We studied the field emission properties of the cathode and the brightness of the green phosphor also screen printed on the anode. The display unit exhibited good field emission properties. The single-walled nanotube cathode was shown to have low turn-on voltage and high field emission current density.
Molecular dynamics simulation of methane hydrate dissociation by thermal stimulation in conjunction with chemical injection method
Authors: Yan Ke-Feng  , Li Xiao-Sen  , Chen Zhao-Yang  , Li Gang  , Li Zhi-Bao  ,   (1)中国科学院广州能源研究所,广州 510640; (2)中国科学院过程工程研究所,北京 100080
Published: December 2020

The characteristics of methane hydrate dissociation in the presence of thermal stimulation, chemical injection, and thermal stimulation in conjunction with chemical injection method were investigated by molecular dynamics simulation. The effect of the injection of liquid water (WTR) and 30wt% ethylene glycol (EG) solution at 277K and 340K on methane hydrate dissociation was studied. The results showed the hydrogen bonds between WTR molecules and the water molecules on the hydrate surface were formed，which destroyed the original hydrogen bond balance of the hydrate. Therefore, the clathrate structure of hydrate collapsed, and the hydrate dissociated. The hydrogen bonds was formed obviously between hydroxyl groups of EG molecules and the water molecules on the hydrate surface; this caused the original stable clathrate structure of the hydrate to be destroyed and collapse, and, furthermore, promoted the dissociation of the methane hydrate and the release of methane gas. Compared with the effects of injecting WTR and 30wt% EG solution at 277K and 340K on the dissociation of methane hydrate, the effectivences was found to be: EG(340K)> WTR(340K)>EG(277K)>WTR(277K). The thermal stimulation in conjunction with chemical injection method can more effectively promote the dissociation of hydrate.
Physical modeling of broadband pulsed laser amplification process based on hybrid-widened linewidth
Authors: Liu Lan-Qin  , Su Jing-Qin  , Luo Bin  , Wang Wen-Yi  , Jing Feng  , Wei Xiao-Feng  ,   (1)西南交通大学计算机与通信工程学院,成都 610031; (2)中国工程物理研究院激光聚变研究中心,绵阳 621900
Published: December 2020

Physical model was established to describe the broadband pulsed laser amplification processes. In this model, Cross relaxation was introduced to study the transformation of homogeneous and inhomogeneous population inversion after laser passage. Hybrid-widened linewidth, homogeneity and inhomogeneity were emphatically considered, which were had not been take into account in other models. Based on the physical model, computer simulation software CPAP for broadband pulse laser amplification process was developed. At last, we discussed the possibility that this broadband physical model can be transfered to the narrow_band physical model under certain conditions.
A study of cognitive radio decision engine based on quantum genetic algorithm
Authors: Zhao Zhi-Jin  , Zheng Shi-Lian  , Shang Jun-Na  , Kong Xian-Zheng  ,   杭州电子科技大学通信工程学院,杭州 310018
Published: December 2020

One of the basic capabilities of cognitive radio is to adapt the radio parameters according to the changing environment and user needs. A cognitive radio decision engine based on quantum genetic algorithm is proposed, in which the radio parameters are adapted and optimized by quantum genetic algorithm. The multiple objective functions are designed and multi-carrier system is used for performance analysis. Experimental results show that the proposed method has better convergence, precision and stability than the classic genetic algorithm, and the good performance of the proposed method in small population size illustrates that it is suitable for hardware implementation. Simulation results under different weighting scenarios illustrate the trade-off between multiple objective functions and that the adapted parameter configuration is consistent with the weights of the objective functions.
Thermodynamics of Gibbons-Maeda dilaton black hole and Garfinkle-Horowitz-Strominger dilaton black hole in noncommutative space-time
Authors: Zhou Shi-Wei  , Liu Wen-Biao  ,   北京师范大学物理学系,北京师范大学理论物理研究所,北京 100875
Published: December 2020

Considering a Gibbons-Maeda dilaton black hole and a Garfinkle-Horowitz-Strominger dilaton black hole, the effect of space noncommutativity on black hole thermodynamics is investigated. By comparing the Gibbons-Maeda dilaton black hole in commutative space with the Garfinkle-Horowitz-Strominger dilaton black hole in noncommutative space, it has been concluded that the noncommutativity of the space has an effect on Garfinkle-Horowitz-Strominger dilaton black hole similar as has the electric or magnetic charge in Gibbons-Maeda dilaton black hole.
The relation between force-law and radius in bubble raft
Authors: Guo Ping-Bo  , Wang Shao-Feng  , Wu Xiao-Zhi  , Zhang Fu-Zhou  , Ye Jin-Qin  , Wang Rui  ,   重庆大学结构与功能研究所，重庆  400044
Published: December 2020

Based on the interaction acting among the bubbles, the relation between the restoring force and the relative displacement is calculated explicitly for the bubble raft. The results indicate that the force-law of the bubble raft strongly depends on the radius. A new form of force-law is proposed to describe the dependence on the bubble radius.
The equal probability comparison method of determining the equivalent-electron Young basis
Authors: Hu Kun-Ming  ,   商丘师范学院物理与信息工程系，商丘  476000
Published: December 2020

The concepts of the basic symmetric operator and complete symmetric operator of the equivalent-electron regular Young tableau T［λ］ig are presented, and the concepts of the root state and generative state generated by these symmetric operators acting on each Slater function i are also given. Based on the establishment rules of the vertical permutation operator A［λ］ig of the orthogonal normalization Young tableau T［λ］ie, the symmetric operators in A［λ］ie and the equiprobability comparison method for solving T［λ］ie are presented, which can avoid the complicated algebra involving many operators. Finally, a new method for sloving the Young basis of the electron system with a large N is presented.
Time-delayed Logistic system driven by correlated Gaussian white noises
Authors: Guo Yong-Feng  , Xu Wei  ,   西北工业大学应用数学系，西安  710072
Published: December 2020

Time-delayed Logistic system driven by correlated Gaussian white noises could be a more true reflection of the growth of tumor cell population. In this paper, we study the Logistic system through the small time delay approximation to obtain the probability density of the system in its steady state, and further analyze the influences of the additive and multiplicative noise intensity, the noise-correlated time and the time delay on the steady-state probability density. The non-equilibrium phase transition phenomena induced by the noises is also studied.