bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase diagrams of the crossroad traffic model with low velocity vehicles
Authors: Liu Mu-Ren  , Wang Bing-Hong  , Li Qi-Lang  , Sun Xiao-Yan  ,   (1)Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China; (2)Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China;Department of Mathematics and Physics,Anhui University of Architecture,Hefei 230601,China; (3)Guangxi Teachers Education University,Nanning 530001,China
Published: December 2020

This work studies the crossroad traffic model with low velocity vehicles,wherein the model consists of two one-lane roads. The parallel updating rule without traffic lights is obeyed by all the cars in our model. Based on the principle for constructing phase diagrams and the local occupation probability method,the phase diagrams are constructed,and in every phase diagram,the formulas of current in each region can be obtained. The deterministic FI model with the periodic boundary is applied in our numerical simulations. It turns out that the numerical results are in exact accordance with the theoretical analysis. Besides,the parallel updating rule is more common in the real crossroad traffic and thus our work may be helpful for the study of traffic management.
A droplet model in steam condensation with gas mixtures
Authors: Lan Zhong  , Wang Ai-Li  , Ma Xue-Hu  , Peng Ben-Li  , Song Tian-Yi  ,   Institute of Chemical Engineering,Dalian University of Technology,Dalian 116012,China
Published: December 2020

A physical and revised mathematical droplet model was proposed for condensation heat transfer process near the cooled solid surface,according to the micro-physical mechanism and thermodynamic characteristics in condensation phase change process. The heat transfer model considering the effect of interfacial effects was used to calculate the temperature of clusters. The mathematical model based on the refined DM homogeneous nucleation model,introducing the wall conditions and making some correlations,was used to calculate the size distribution of clusters,and also describe the effect of the presence of non-condensable gases on the distribution of clusters. The present model explains quantitatively the fact that the presence of small amount of non-condensable gases deteriorate condensation heat transfer performance significantly. The predicted results of the model agree with the experimental results reported in the literature.
Theoretical study of the dielectronic recombination process of Ni17+ ions
Authors: Li Chuan-Ying  , Liu Xiao-Ju  , Meng Guang-Wei  , Wang Jian-Guo  ,   (1)Institute of Applied Physics and Computational Mathematics,Beijing 100088, China; (2)Institute of Plasma Physics, Chinese Academy of Sciences,Hefei 230031, China
Published: December 2020

We studied the dielectronic recombination processe of Ni17+(3s) through the resonant doubly excited states Ni16+(3pnl,3dnl) (Δn=0) using the Flexible Atomic Code (FAC) which is based on a relativistic configuration interaction method. We obtained the cross sections and the rate coefficients and compared them with the experimental data and other theoretical results. The integrated cross sections through the resonant doubly excited states 3p3/210l and 3p1/211l are in a good agreement with the measurements within the experimental errors. In combination with quantum defect theory, we have found out that the radiative rates and the auger rates of the resonant doubly excited states involving high Rydberg states obey a good scaling law, by means of which we obtained the integrated cross sections and the rate coefficients of all the resonances close to the thresholds. A comparison of the series 3pnl and 3dnl indicates that the rate coefficients of the former are larger when the temperature is below ~100 eV, and are smaller when the temperature is higher.
X-ray spectrum emitted by the impact of 129Xeq+ on Mo surface
Authors: Liang Chang-Hui  , Zhang Xiao-An  , Li Yao-Zong  , Zhao Yong-Tao  , Xiao Guo-Qing  ,   (1)Department of Physics, Xianyang Normal College, Xianyang 712000, China; (2)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

We studied the characteristic X-ray spectra produced by the interaction of highly charged ions of 129Xeq+(q=25,26,27)with surface of metallic Mo. The experimental result shows that highly charged ions can excite the characteristic X-ray spectra of L-shell of Mo when the beam’s intensity is not more than 120 nA. The X-ray yield of single ion reaches a quantitative level of 10-8 and increases with the increment of the ion’s kinetic energy and ionic charge (potential energy). By measuring the X-ray spectra of Mo-Lα1, the M-level lifetime of Mo atom is estimated by using Heisenberg uncertainty relation.
Kβ/Kα ratios and energies of the K-shell X-ray of Ar17+ ion in the interaction with metals
Authors: Zou Xian-Rong  , Shao Jian-Xiong  , Chen Xi-Meng  , Cui Ying  ,   School of Nuclear Science and Technology, Lanzhou University,Lanzhou 730000, China
Published: December 2020

The K X-rays emitted from the incident slow highly charged Ar17+ ions are investigated in the interaction with various metal target such as Be, Al, Ni, Mo and Au. The Kβ/Kα ratios and the mean energies of the emitted X-rays are extracted and analyzed from our previous experimental results . It is found that the ratios and the energies are almost independent of the ion velocity and the target element. Meanwhile, a model based on the conductive-electron capture and the cascading de-excitation model is proposed to interpret the experiment. Excellent agreement is found between the theoretical results and the experimental data.
Derivation of three-dimensional axiolitic cloak and the invisibility verification
Authors: Wu Qun  , Zhang Kuang  , Meng Fan-Yi  , Li Le-Wei  ,   (1)Department of Electronic and Communications Engineering, Harbin Institute of Technology, Harbin 150001, China; (2)Department of Electronic and Communications Engineering, Harbin Institute of Technology, Harbin 150001, China;Department of Electrical and Computer Engineering, National University of Singapore, Singapore 119260, Singapore
Published: December 2020

Arbitrary three-dimensional axiolitic cloaks are proposed and designed based on the coordinate transformation theory. The general expressions of constitutive tensors of the cloak are derived, and then some full-wave simulations of the cloaks based on the constitutive tensors that we derived are performed. The results of full-wave simulations validate the general expressions of constitutive tensors of the three-dimensional axiolitic cloaks.
Broadband lefthanded metamaterial absorber based on split ring resonator and wire array
Authors: Fan Jing  , Cai Guang-Yu  ,   (1)Department of Electronics and Electrical Engineering, Nanyang Institute of Technology, Nanyang 473004, China; (2)Department of Mechanical and Electrical Engineering, Nanyang Institute of Technology, Nanyang 473004, China
Published: December 2020

We studied the basic resonance structure of split ring resonator (SRR) and wire array at microwave X-band numerically. With proper design of parameters, this structure could achieve the absorptivity as high as 98% near the frequency of 10.91 GHz, and the FWHM of which is greater than 3.5 GHz. The scattering parameter retrieval method is employed to calculate the effective electromagnetic parameters. It is found that, close to the resonance frequency, the real components of the effective permittivity, permeability, and refractive index are all negative. However, the imaginary components of the electromagnetic parameters seem to be very large in the resonance region, which is the main reason of the high absorptivity. The broadband lefthanded metamaterial absorber presented in this paper has potential applications such as in electromagnetic heating and electromagnetic hiding.
A novel finite-difference time-domain scheme for electromagnetic scattering by stratified anisotropic plasma under oblique incidence condition
Authors: Yang Li-Xia  , Xie Ying-Tao  , Kong Wa  , Yu Ping-Ping  , Wang Gang  ,   (1)Department of Communication Engnerring, Jiangsu University, Zhenjiang 212013, China; (2)Department of Communication Engnerring, Jiangsu University, Zhenjiang 212013, China;State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
Published: December 2020

A novel finite-difference time-domain(FDTD) implementation, by which electromagnetic(EM) wave scattering characteristic can be analyzed for oblique incidence on stratified anisotropic plasma, is proposed. This method transforms two-dimensional electromagnetic wave scattering question to one-dimensional question, and avoids two-dimensional scattering problem by 2D FDTD method, by which the computational efficiency can be greatly improved. FDTD iterative formula of EM scattering by layered anisotropic plasma are deduced in the TEz and TMz wave oblique incidence situations, and the connection boundary(CB) and the absorbing boundary condition (ABC) in the oblique incidence situation are carried out the revision. The EM wave reflection coeffientes of the anisotropic plasma slab are calculated in the oblique incidence situation by the method. The computed results and the analytic solutions are in good agreement. The results show the accuracy and validity of the method. Finally, the algorithm is applied to calculate the reflection coefficients of the metal plate coated with the stratified anisotropic plasma under different incidence angles. The numerical results show the incidence angle have a great impact on the reflection coefficients.
A bottle beam generated by a ring obstacle-axicon
Authors: Lu Wen-He  , Wu Feng-Tie  , Ma Bao-Tian  ,   College of Information Science & Engineering, Huaqiao University, Quanzhou 362021, China
Published: December 2020

A new method of generating bottle beam was proposed for the first time, which is compriecs a traditional axicon with a ring obstacle at its underside. When a plane wave illuminates the bottom of axicon with ring obstacle, a bottle beam is generated within the maximum non-diffractional distance, and the beam keeps as non-diffractional Bessel beam in front and behind the bottle beam. Controlling the size of bottle beam is realized by changing the size of obstacle or cone angle of axicon. The principle of generating bottle beam when a plane wave illuminates the ring obstacle-axicon was described using the diffraction theory. The transverse intensity distribution of the bottle beam in propagation and the three-dimensional intensity distribution of the whole process were analyzed and simulated, and the experiment results were presented. The result shows significant guidance value for the practical application of the bottle beam.
The tunneling properties of the bilayer structure composed of single negative materials based on transmission lines
Authors: He Li  , Zhang Li-Wei  , Xu Jing-Ping  , Wang You-Zhen  ,   (1)Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092,China; (2)Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092,China;Academy of Opto-Electronics,Chinese Academy of Sciences, Beijing 100190,China; (3)School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000,China;Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092,China
Published: December 2020

Epsilon-negative (ENG) and mu-negative (MNG) materials are fabricated by using transmission line (TL) approach, the electromagnetic tunneling properties of the bilayer structures with ENG-MNG materials are experimentally investigated. The results indicate that the two kinds of single negative materials do not support electromagnetic propagation modes, whereas the completely tunneling phenomenon occurs in the ENG-MNG pairs under special conditions when the average permittivity or average permeability equals zero respectively. Furthermore, the tunneling modes are insensitive to the scale length. Exponential amplification of the evanescent wave is also experimentally observed by simulating and measuring the electric field distributions in ENG-MNG structures at the tunneling frequency.
Optimized two-step phase-shifting algorithm applied to image encryption
Authors: He Wen-Qi  , Qin Wan  , Peng Xiang  , Guo Ji-Ping  , Li A-Meng  , Cai Lü-Zhong  , Meng Xiang-Feng  ,   College of Optoelectronics Engineering, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China;,   Department of Optics, School of Information Science and Engineering, Shandong University, Jinan 250100, China;,   Department of Optics, School of Information Science and Engineering, Shandong University, Jinan 250100, China;College of Optoelectronics Engineering, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, She
Published: December 2020

The two-step phase-shifting algorithm proposed previously is optimized, the original object wave field can be reconstructed by only one phase shift value in (0, π) and two interferograms, with the removal (or suppression) of background intensity (or dc term), and the additional measurements such as the object wave intensity, reference wave intensity, etc., are no longer required. Together with double random phase encoding technique in the Fresnel domain, the optimized two-step phase-shifting algorithm is then applied to image encryption system. The feasibility of the proposed scheme is verified by computer simulation. Furthermore, the sensitivity of geometrical keys has also been tested and analyzed.
Investigation on all-optical regeneration of asynchronous dual-wavelength signals based on fiber-optic parametric amplification
Authors: Yu Jin-Long  , Luo Jun  , Han Bing-Chen  , Guo Jing-Zhong  , Wu Bo  , Wang Ju  , Zhang Xiao-Yuan  , Yang En-Ze  ,   (1)Optical Fiber Communication Laboratory, School of Electronic & Information Engineering, Tianjin University, Tianjin 300072, China; (2)Optical Fiber Communication Laboratory, School of Electronic & Information Engineering, Tianjin University, Tianjin 300072, China;School of Physics and Electronic Science, Shanxi Datong University, Datong 037009, China
Published: December 2020

With the continued development of the wavelength division multiplexing (WDM) network, there arises an urgent demand for the research of multi-wavelength all-optical 3R regeneration. In this paper, a novel multi-wavelength all-optical regeneration scheme has been proposed. Using phase clock in the fiber-optic parametric amplification and polarization multiplexing, all-optical regeneration of dual-wavelength signals generated by two independent WDM transmitter is realized. Theoretical analysis is carried out for the operation mechanism of the amplitude noise suppression using the gain saturation of the parametric amplification, and re-timing using phase modulation with cascading dispersion. Dual-wavelength 10 Gbit/s signal optical regeneration is demonstrated experimentally. Experimental results show that the inter-channel nonlinearities like four-wave mixing and cross phase modulation are effectively reduced. In the single and dual-wavelength cases, signal to noise ratio improvements of at least 6.5 dB and 4.5 dB have been achieved, respectively, after regeneration. Bit error rate test shows that about 2 dB power penalty improvement is obtained in both single- and dual-wavelength operations.
Nonclassical properties in the resonant interaction of a three level Λ-type atom with pair coherent states
Authors: Chen Zi-Hong  , Liao Chang-Geng  , Luo Cheng-Li  ,   College of Physics and Information Engineering, Fuzhou University, Fuzhou 350002, China
Published: December 2020

This paper is concentrated on the nonclassical properties of the pair coherent states during the interaction with a three-level Λ-type atom, such as antibunching effect, violation of Cauchy-Schwarz inequality and two-mode squeezing. Meanwhile, we find these nonclassical properties can be enhanced in the case that the atom is selectively measured.
Research of transmission characteristics of single-photon orbital angular momentum
Authors: Ke Xi-Zheng  , Nu Ning  , Yang Qin-Ling  ,   Faculty of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China
Published: December 2020

We describe the high order elliptic hermite gaussian beam and the average orbital angular momentum of single-photon, and analyze some situations of the change of orbital angular momentum, briefly by the simulation. Finally, the probability distribution and changes in the probability distribution within the range of space for the single-photon orbital angular momentum are analyzed. The results show that the change magnitude of the single-photons average orbital angular momentum varies with the material when the high order elliptic Hermite-Gaussian beam interacts with mater.
Influence of Kerr-effect on the quantum interference of the cavity field spectrum within two mode binomial initial field
Authors: Li Yue-Ke  , Zhang Gui-Ming  , Gao Yun-Feng  ,   School of Medium and Communications, Liaocheng University Liaocheng 252059,China
Published: December 2020

The cavity field spectrum of the nondegenerate two-photon Jayners-Cummings model with an additional Kerr medium is investigated. The results for the initial fields in binomial states are presented. The influence of the Kerr effect on the quantum interference of the two mode cavity field spectra is discussed. It is found that the quantum interference item shows a periodical damped oscillation irregularly when the Kerr effect is increased. The amplitude of the oscillation relate to the difference of the two field frequencies intimately. When the Kerr coefficient χg (g is coupling coefficient between atom and the fields), the change of the quantum interference item is strong with χ. And when χ>g, it is weakly. The cavity field spectra usually take on a complex asymmetric structure with many peaks when Kerr coefficient is large.
Theoretical investigation of infrared generation mechanism by quantum coherence in low-dimensional semiconductor heterostructures
Authors: Sun Wei-Feng  , Li Mei-Cheng  , Zhao Lian-Cheng  ,   Department of Information Material Science and Technology, School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

We present an infrared generation mechanism without population inversion between subbands in quantum well and quantum dot lasers. The infrared generation scheme is based on the resonant nonlinear mixing of the two optical laser fields. These two optical fields come from two interband transitions in the same active region and serve as the coherent drive for infrared field. This mechanism of frequency down conversion should work efficiently at room temperature with injection current pumping, not relying on any ad hoc assumptions of long-lived coherence in the semiconductor active medium. Under optimized waveguide and cavity parameters, the intrinsic down-conversion efficiency can reach the limiting quantum value corresponding to one infrared photon generated by one optical photon. Because the proposed infrared generation is parametric, the proposed scheme without population inversion is especially promising for long-wavelength infrared operation.
Epitaxy structure of a 1.5 μm n-p-n InGaAsP-InP transistor laser
Authors: Duan Zi-Gang  , Huang Xiao-Dong  , Zhou Ning  , Xu Guang-Hui  , Chai Guang-Yue  ,   (1)Accelink Technologies Co. Ltd., Hongshan District, Wuhan 430074, China; (2)Key Laboratory of Optoelectronic Devices and Systems of the Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China
Published: December 2020

An InGaAsP-InP transistor laser (TL) working at 1.5 μm and its epitaxy structure with MQW active layer buried between unsymmetrical upper and lower waveguides in base region has been designed and modeled. The simulation result shows that the proposed TL has good optical and lateral electrical current confinement. The result of epitaxial experiment by metalorganic chemical vapor deposition (MOCVD) shows that the diffusion of doped Zn2+ from heavily doped base contactor layer to active waveguide can induce serious degradation of quantum wells. By modeling the Zn2+ diffusion from heavily doped base contactor layer, a gradient doping profile with an average doping density of 1 ( 1018 cm-3 in the base contact layer has been used in the epitaxy process to constrain the Zn2+ diffusion to quantum wells. The test result of the epitaxy material has demonstrated high PL intensity at 1.51 μm and clear satellite diffraction peaks in the XRD spectrum.
Nanosecond non-diffracting Bessel green beam generated directly from an unstable resonator by active method
Authors: Ma Bao-Tian  , Wu Feng-Tie  , Ma Liang  ,   College of Information Science and Engineering, Huaqiao University, Quanzhou 362021, China
Published: December 2020

An intracavity frequency-doubled Nd∶YAG nanosecond Bessel green laser is designed in an axicon-based Bessel and Bessel-Gaussian resonator. The unstable laser resonator is composed of a refraction axicon and a convex mirror. The gain medium Nd∶YAG rod is pumped by a single flash-lamp which is working in a pulsed mode and a KTP crystal is used for intracavity second-harmonic generation. Nanosecond Bessel green beam is generated directly from the laser by active method when pumping voltage is 350 V. The pulse with width of 55.1 ns, central wavelength at 532 nm, spectral line width of 0.8 nm and diameter of central spot of 192 μm is obtained. Fresnel-Kirchhoff diffraction integral and the Fox-Li algorithm is used to extract the dominant mode of the cavity and the experimental results are consistent with those of the numerical simulation.
Photon statistics of squeezed vacuum field from optical parametric oscillator far below the threshold
Authors: Zhao Dong-Mei  , Li Zhi-Gang  , Guo Yan-Qiang  , Li Gang  , Wang Jun-Min  , Zhang Tian-Cai  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
Published: December 2020

Photon statistics of the weak squeezed vacuum field from an optical parametric oscillatior (OPO) is investigated both in theory and by experiment . The strong photon bunching effect of weak squeezed vacuum field, which can be used as an important source in quantum optics and quantum measurement, was demonstrated. We have experimentally produced the weak squeezed vacuum at the center wavelength of D2 line of the cesium atom by the OPO operating far below the threshold . The second-order correlation function was measured based on the Hanbury-Brown-Twiss scheme, and the result is consistent with theoretical analysis.
Study on the focusing performance of the compound X-ray refractive lenses with fabrication errors
Authors: Le Zi-Chun  , Zhang Ming  , Dong Wen  , Quan Bi-Sheng  , Liu Wei  , Liu Kai  ,   Department of Applied Physics, College of Sciences, Zhejiang University of Technology, Hangzhou 310023, China
Published: December 2020

The compound X-ray refractive lens is a kind of optical components for X-rays focusing and imaging. This paper reports the authors’ research on focusing performance of the compound X-ray refractive lens with fabrication errors. Firstly SEM measurements of the semi-cylindrical PMMA compound X-ray refractive lens fabricated by means of deep X-ray lithography are performed, and accordingly the fabrication errors are measured. Then the theoretical analysis and simulations are done for the focusing performance of the compound X-ray refractive lens with the fabrication errors. Finally, X-ray microbeam experimental system is built on the 4W1A beamline of Beijing Synchrotron Radiation Facility (BSRF) for measuring the focusing performance of the semi-cylindrical PMMA X-ray refractive lenses we fabricated. And the focusing performances of the semi-cylindrical PMMA compound X-ray refractive lenses with and without distinct fabrication errors are measured and analyzed under 8 keV monochromatic X-rays.
Experimental research on smoothing by spectral dispersion based on wave-guide phase modulator
Authors: Zhang Rui  , Wang Jian-Jun  , Su Jing-Qin  , Liu Lan-Qin  , Ding Lei  , Tang Jun  , Liu Hua  , Jing Feng  , Zhang Xiao-Min  ,   Research Center of Laser Fusion, CAEP, Mianyang 621900, China
Published: December 2020

Precise physical experiments place strict requirements on target illumination uniformity in inertial confinement fusion. Currently, the main stream of beam smoothing technology adopted in solid-state laser driver is smoothing by spectral dispersion (SSD). The SSD based on wave-guide phase modulator is experimentally studied here. The experimental results indicate that this phase modulator can easily broaden the narrow-band light generated from a DFB laser to 0.1 nm to 1.5 nm bandwidth. The far-field analysis indicates the experimental results are in good accordance with the simulation results. In the meantime, nearfield modulation around 100 μm after the dispersion grating could be smoothed significantly. The research lays experimental basis for the optimization of beam smoothing in high-power laser facility.
Analysis of earth-mine resonance model
Authors: Liang Guang-Qiang  , Wang Chi  , Yu Ying-Jie  , Li Xing-Fei  ,   (1)Arming Office, Tianjin University, Tianjin 300072, China; (2)Dept.of Precision Mechanical Engineering, Shanghai University, Shanghai 200072, China; (3)State Key Lab of Precision Measuring Technology & Instruments, Tianjin University, Tianjin 300072, China
Published: December 2020

Based on the earth-mine resonance model, a model combining resonance and anti-resonance was presented for acoustic mines detection. Considering the high compliance and low-frequency acoustics characters, a landmine and the earth on top of it were respectively equivalent to a spring and a mass, resulting in a mass-spring system. The model’s resonance and anti-resonance mechanisms were discussed by means of frequency response function. The experimental results showed that the vibration velocity ratios of the ground surface with and without mine buried under it show alternate maximum and minimum frequencies with the ratios greater than 1, and less than 1 respectively. The results consisted with the theoretical prediction and indicated that the earth-mine system’s resonance and anti-resonance mechanisms exist concurrently, which can be used to further study of the acoustic mine imaging.
Research on electronic process of impulse degradation of ZnO-based ceramics
Authors: Yin Gui-Lai  , Li Jian-Ying  , Yao Guang  , Cheng Peng-Fei  , Li Sheng-Tao  ,   (1)School Physics of Xi'an Polytechnic University ,Xi'an 710048, China; (2)State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The electrical and dielectric properties of a commercial ZnO-based varistor ceramics were measured in the process of 8/20 μs impulse current degradation up to 5000 times of impulses. The characteristics of U-I in the region of low current and the loss tangent were mainly investigated. It was found that the varistor voltage U1mA will first increase rapidly with impulse times increasing, and then remain stable and finally decrease sharply. Furthermore, a new loss peak emerges at -100℃ in the dielectric spectra after 600 times of impulse degradation, which suggests a new trapping behavior introduced in the degradation process. Activation energy of the new peak first decreases, then becomes independent on impulse times. It was also found that the non-linear coefficient was more sensitive to the degradation process than varistor voltage U1mA. These phenomena have not been reported before, which revealed that the variation of the neutral Fermi level between positive bias Schottky barrier region and reverse bias Schottky barrier region is the origin which leads to the degradation of electrical properties.
Simulation of microstructure of liquid-crystalline polymers in nonhomogenous shear flow by EFG method
Authors: Wang Xiao-Dong  , Ouyang Jie  , Su Jin  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xian 710129, China
Published: December 2020

Complex microstructures of liquid-crystalline polymers in nonhomogenous shear flow are studied by element free Galerkin (EFG) method based on the micro-macro dualscale model. The dualscale model combines the orientational diffusion equation in microscale with the flow governing equations in macroscale. The EFG method which has the merits of high accuracy and good stability can ensure the reliability of the simulation results. One simple and five composite structures of liquid-crystalline polymers in nonhomogenous shear flow are predicted by studying the influences of Deborah number on microstructures of liquid-crystalline polymers in plane Poiseuille flow. It shows that the instabilities in the transition region of the composite structures can cause some defects.
Experimental study on shock compression properties of polyethylene
Authors: Huang Xiu-Guang  , Fu Si-Zu  , Shu Hua  , Ye Jun-Jian  , Wu Jiang  , Xie Zhi-Yong  , Fang Zhi-Heng  , Jia Guo  , Luo Ping-Qing  , Long Tao  , He Ju-Hua  , Gu Yuan  , Wang Shi-Ji  ,   (1)Beijing Institute of Applied Physics and Computational Mathematics, Beijing 100088, China; (2)Shanghai Institute of Laser Plasma, Shanghai 201800, China
Published: December 2020

Shock compression properties of polyethylene (CH2) were studied at SG-Ⅱ laser facility. The experimental results show that the self-emission is high,which emits from the shock-front in polyethylene. And the shock-front propagates through the polyethylene step almost with constant velocity. The Hugoniot equation of state (EOS) of polyethylene was measured by using the impedance-matching method with aluminum as standard material. Pressures are high up to 0.54 TPa in polyethylene, and the relative expanded uncertainties of the measured shockwave velocity are about 2% (K=2). Moreover, the consistency of our data is good, and our data are also consistent with existing experimental data and EOS model.
Measurement of the electronic Grüneisen constant at room temperature
Authors: Zhang Zhong-Chao  , Zhu Peng-Fei  , Li Run-Ze  , Chen Long  , Sheng Zheng-Ming  , Zhang Jie  ,   (1)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; (2)Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China; (3)Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China;Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The electronic Grüneisen constant γe of Al is measured at room temperature using our homemade ultrafast electron diffraction (UED) equipment. The electronic contribution to the thermal expansion of solid is differentiated from the lattice contribution in the time domain when an Al film is heated rapidly by ultrashort laser pulse. By directly probing the associated thermal expansion in real time at room temperature, we differentiate the two in the time domain, and finally obtain the electronic Grüneisen constant γe. With this new method we overcome the restriction of the traditional low temperature methods in measuring the electronic Grüneisen constant γe of nonmagnetic metals.
Monte Carlo simulation of influence of inhomogeneous interaction energy on thin film growth
Authors: Liu Zu-Li  , Yuan Xin-Xi  , Wei He-Lin  , Yao Kai-Lun  ,   (1)School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China; (2)School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China;School of Maths and Physics, China University of Geosciences, Wuhan 430074, China
Published: December 2020

The influence of inhomogeneous interaction energy between deposited atoms and substrate atoms on island film growth is investigated by Monte Carlo simulation on a triangular lattice substrate. The Gaussian distribution is employed to describe the inhomogeneity of interaction energy. The results illustrate that the influence of inhomogeneous interaction energy on the growth of thin film is related to the degree of the inhomogeneity and the experimental conditions (such as substrate temperature).At medium temperature the inhomogeneity of interaction energy has notable influence on the island number and the island size. Increasing in temperature could counteract the influence of the inhomogeneity of interaction energy.
Electronic structure and magnetism of single-layer trigonal graphene quantum dots with zigzag edges
Authors: Wang Yong-Long  , Pan Hong-Zhe  , Xu Ming  , Chen Li  , Sun Yuan-Yuan  ,   (1)Institute of Solid State Physics & School of Physics and Electronic Engineering,Sichuan Normal University,Chengdu 610068,China; (2)School of Sciences,Linyi Normal University,Linyi 276005,China; (3)School of Sciences,Linyi Normal University,Linyi 276005,China;Institute of Solid State Physics & School of Physics and Electronic Engineering,Sichuan Normal University,Chengdu 610068,China
Published: December 2020

The geometry, spin multiplicity, magnetic moment, electronic density of states and the spin density of single-layer trigonal graphene quantum dots with zigzag edges have been systematically investigated using density functional theory with the generalized gradient approximation under different sizes. The calculated results such as lattice constants are in good agreement with experimental data and indicate that the system behaves like metal, while the electrons with up spins occupy the Fermi energy. The influence of quantum size effect is remarkable in the system of small size. It is also found that the sp2 hybridization and nonbonding electrons play an important part in the single-layer trigonal graphene quantum dots, just like in graphene. The spin multiplicity and magnetic moment of the system increase with the increase of the system size. Based on our calculation, the total magnetic moment of the system mainly comes from the nonbonding electrons on the 2p orbital of the zigzag boundary. Our calculation may be helpful in designing devices based on trigonal graphene quantum dots.
First-principles study of helium atom doped interstitial sites of Al
Authors: Liu Xian-Kun  , Liu Ying  , Qian Da-Zhi  , Zheng Zhou  ,   (1)College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China; (2)College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China;Institute of Nuclear Physics and Chemistry, China Academe of Engineering Physics, Mianyang 621900, China; (3)Institute of Nuclear Physics and Chemistry, China Academe of Engineering Physics, Mianyang 621900, China
Published: December 2020

The geometry structure, electronic structure, total energy, Mulliken changes of He atom in the Al octahedral site and tetrahedral site were studied by first-principle plane-wave pseudopotential method and GGA. The calculation results indicated that the crystal lattice of Al was changed when He atom enter to the interstitial of Al, but the total results are the change of crystal lattice in octahedral site smaller than tetrahedral site. For Al system, the impurity formation energies of helium atom are 1.3367 and 2.4411 eV in the octahedral site and tetrahedral site, respectively. It is found that for He atom the best stable state is octahedral of Al. At the same time, the site occupancy and its effect of He atom in crystal cell was analysis in this article, and the effects of helium atom in Al system on band structure and density of states and valence electron density are discussed.
First-principles study of Li-N acceptor pair codoped p-type ZnO
Authors: Yuan Di  , Huang Duo-Hui  , Luo Hua-Feng  , Wang Fan-Hou  ,   (1)Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007, China; (2)Computational Physics Key Laboratory of Sichuan Province, Yibin University, Yibin 644007, China;Department of Physics and Electronic Engineering, Yibin University, Yibin 644007,China
Published: December 2020

Based on the density functional theory,the structure of pure ZnO and N, Li, and Li-N codoped wurtzite ZnO has been investigated by using first-principle plane wave ultrasoft pseudopotential method. The band structure, total density of states, partial density of states, and the number of charge population of pure ZnO and N, Li, Li-N codoped wurtzite ZnO were studied. The calculated results show that Li-N codoped wurtzite ZnO is more in favor of the formation of p-type ZnO.
The structures and properties of Ge nanocrystals before and after Neutron transmutation doping
Authors: Chen Qing-Yun  , Xu Ming  , Lu Tie-Cheng  , Meng Chuan-Min  , Hu You-Wen  ,   Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, China;,   Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, China;Key Lab for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineer;,   Key Lab for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China;,   Laboratory for Low-dimensional Structure Physics, Institute of Solid State Physics School of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

The effects of vacant, O defects and As doping on the structures and properties of Ge nanocrystals (Ge-ncs) are investigated by using first-principles calculation based on the density functional theory (DFT). The calculation results indicate that the O defects induced by thermal annealing cannot compensate for the defects caused by neutron irradiation in Ge nanocrystals, while the introduction of As produced by neutron transmutation doping (NTD) will do the jop. We also show that the strong attraction between O and Ge atoms inhibits the formation of vacant defects in Ge nanocrystals, and further improve the luminescent property of Ge-SiO2 system. This suggests that it is necessary to perform thermal annealing for Ge-ncs structures before NTD. Our calculations well support our previous experimental results.
Theoretical study of local structure and ground-state splitting of Cs2NaMF6(M=Al, Ga):Cr3+ complex molecule systems
Authors: Wang Li-Xia  , Kuang Xiao-Yu  , Li Hui-Fang  , Chai Rui-Peng  , Wang Huai-Qian  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

Based on the two spin orbit coupling parameter model and the complete energy matrices for a d3 configuration ion in a trigonal ligand field, the local structure and the ground-state splitting of Cr3+ ion in Cs2NaMF6(M=Al, Ga):Cr3+ systems have been studied. By simulating the EPR parameter D and the optical spectra, the distorted angles of two inequivalent sites formed by Cr3+ replacing M3+ are determined and the obvious difference of the distorted angles Δθ calculated by using two spin orbit coupling parameter model and single spin orbit coupling parameter model is found. Our results indicate that the influence of ligand F- can not be ignored with respect to spin orbit coupling mechanism when the energy level fine structure and local structure distortion of fluoride complex molecules are studied. Meanwhile, the dependence of EPR parameter D on angle θ, average parameter ζ1 and divergent parameter ζ2 is discussed, respectively.
Thermal stability and charge dynamics of piezoelectrets with tailored micro-structure
Authors: Cao Gong-Xun  , Zhang Xiao-Qing  , Sun Zhuan-Lan  , Wang Xue-Wen  , Lou Ke-Xing  , Xia Zhong-Fu  ,   Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, China
Published: December 2020

The laminated fluoroethylenepropylene (FEP) and porous polytetrafluoroethylene (PTFE) films with regular void structure are prepared by using a rigid template with a periodic-structured surface. The porous PTFE film is firstly patterned with the rigid template surface by applying force on the stack of porous PTFE film and the template, then followed by the fusion bonding process to bond the FEP and patterned porous PTFE together. The corona charging technique is used to make the laminated film piezoelectric, i.e., to become piezoelectrets. The Young’s modulus of the laminated FEP/PTFE films is determined by dielectric resonance spectra. The thermal stability of the piezoelectric d33 coefficients are characterized by measuring the decay of d33 at elevated temperatures. The charge dynamics in such FEP/PTFE piezoelectrets is investigated by analying the thermally stimulated discharge current spectra in short circuit. The results show that laminated FEP/PTFE films with very regular void structure can be made by using rigid template and fusion bonding process. The Young's modulus of such films is about 0.53 MPa. The maximum quasi-static piezoelectric d33 coefficient up to 500 pC/N is achieved. The laminated FEP/PTFE films show improved thermal stability. For example, the remnant d33value is around 22% of the initial value for the sample annealed at 150 ℃ for 5000 min. For the samples after annealing treatment, the main drift path of the detrapped charges is through the solid dielectric layer.
Study of interaction of surface plasmon resonance sensor with nano-gold
Authors: Hao Peng  , Wu Yi-Hui  , Zhang Ping  ,   National Key Lab of Applied Optics, Changchun Institute of Optics,Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

For a quantitative analysis of the detection performance of wavelength surface plasmon resonance sensor after the introduction of absorbing thin films, a mathematical model was established for the wavelength SPR biosensor. Based on absorption theory of dispersive media, the distribution of electromagnetic field in each film outside the prism is calculated. The results show that, after introducing the absorbing thin films, electromagnetic field energy distribution in each layer out of the prism surfaces was changed, the metal film contribution on the resonance absorption was reduced, which increases the half wave width of SPR curve and the minimum reflection coefficient, so the optimal film thickness of metal film was also changed. Then the effect of colloidal gold and immunogold on SPR biosensor has been theoretically and experimentally verified. The result shows that, compared with the 48 nm gold film SPR sensor, the sensitivity increases 1.5 times when 45nm gold film is surface-modified with 10nm nano-gold.
Model of electronical conductivity effective mass of strained Si
Authors: Zhao Li-Xia  , Zhang He-Ming  , Hu Hui-Yong  , Dai Xian-Ying  , Xuan Rong-Xi  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Strained Si CMOS technology is one of the most advanced technologies in present day microelectronics. Electronical conductivity effective mass of strained Si is a key parameter to study electron mobility enhancement. Using K ·P method with the help of perturbation theory, dispersion relation near conduction band valley was determined, including the longitudinal and transverse masses. And then, electronical conductivity effective masses of strained Si on (001),(101) and (111) planes were obtained with respect to stress, splitting energy and directions. It was found that both the [100]and [010]directional electronical conductivity effective masses of strained Si/(001)Si1-xGex and the [010]directional one of strained Si/(101)Si1-xGex decrease with increasing Ge fraction or stress, and both values tend to be constant. The results provide valuable reference to the conduction channel design related to stress and orientation in the strained Si nMOS devices.
The microstructures of the diamond (100) surfaces with different density of hydrogen adsorption
Authors: Liu Feng-Bin  , Wang Jia-Dao  , Chen Da-Rong  , Zhao Ming  , He Guang-Ping  ,   (1)College of Mechanical and Electric Engineering, North China University of Technology, Beijing 100144, China; (2)State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Published: December 2020

By means of density functional theory on the basis of generalized gradient approximation, the equilibrium geometries and electronic properties of different hydrogenated diamond (100) surfaces were calculated. The results indicate that in the case of 2×1 reconstruction structure, the relaxation occurs along directions parallel and vertical to the surface. However, the relaxation does not appear in the direction parallel to the surface in the case of 1×1 structure. In addition, for the clean surfaces with C(100)-2×1, C(100)-2×1 ∶0.5H and C(100)-1×1 ∶1.5H structures, empty surface states exist in their band gaps. But with regard to the C(100)-1×1 ∶2H and C(100)-2×1 ∶H surface structures, which are configurations with full hydrogen coverage, the empty surface states shift upwards into the conduction band. With the help of analysis of charge density distribution, the inducing mechanisms of surface states were investigated.
Study of structural and electrical properties of phase-change materials Ge1Sb2Te4 and Ge2Sb2Te5 thin films
Authors: Liao Yuan-Bao  , Xu Ling  , Yang Fei  , Liu Wen-Qiang  , Liu Dong  , Xu Jun  , Ma Zhong-Yuan  , Chen Kun-Ji  ,   Nanjing National Laboratory of Microstructures, Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Department of Physics, Nanjing University, Nanjing 210093, China
Published: December 2020

The Ge1Sb2Te4 and Ge2Sb2Te5 thin films were deposited on quartz and silicon substrates by radio frequency magnetron sputtering from Ge1Sb2Te4 and Ge2Sb2Te5alloy targets. Structure properties and electrical transport characteristics of Ge1Sb2Te4 and Ge2Sb2Te5 thin films were studied and compared. X-ray diffraction spectra and atomic force microscopic images were used to characterize the structure of Ge1Sb2Te4 and Ge2Sb2Te5before and after thermal annealing. With increasing annealing temperature, Ge1Sb2Te4crystallized gradually and transformed to polycrystalline state from the amorphous state. Surface of Ge1Sb2Te4 thin films was uniform nanoparticles with roughness less than 10 nm. After thermal annealing, Ge2Sb2Te5 also transformed to polycrystalline state from amorphous state, but its surface morphology did not change significantly compared with the as-deposited film. Results of Hall effect measurement indicated the carrier concentrations of both the as-deposited and annealed films of Ge1Sb2Te4 were three orders of magnitude larger than those of Ge2Sb2Te5. From the above results, we conclude that Ge1Sb2Te4 tends to be more conductive than Ge2Sb2Te5 owing to the larger carrier concentration. Results of resistance versus time measurements under isothermal condition suggested Ge2Sb2Te5is more thermally stable and better fit for data storage than Ge1Sb2Te4.