bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy efficiency and performance characteristics of plasma synthetic jet
Authors: Wang Lin  , Luo Zhen-Bing  , Xia Zhi-Xun  , Liu Bing  ,   Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Based on the Joule heating effect of gas discharge in the working process of the plasma actuator, the plasma synthetic jet is simulated with a three-dimensional phenomenological model, under the assumption of local thermodynamic equilibrium plasma.The flow field evolution process of the plasma synthetic jet during a whole cycle is obtained. The results show that in the self-sustained periodical jet built by a single energy deposition, there is a maxium pulse frequency–saturated frequency which could relaize that the cavity is recovered sufficiently. Large energy deposition, small exit orifice diameter and high diameter-height ratio with the same cavity volume could induce higher speed jet, and the increase of the jet speed occurs concurrently with the decrease of the saturated frequency. During a saturated cycle, up to 16% of the mass in the cacity is expelled, but the recovery can only achieve about 90% of the initial mass in the cavity. Plasma synthetic jet actuator is supplied by a capacitive power supply at atmospheric pressure, the fractions of power that go into gas heating and jet kinetic energy are 5% and 1.6% respectively.
Electronic structures and optical properties of rare earth element (Yb) with different valences doped in ZnO
Authors: Liu Wei-Jie  , Sun Zheng-Hao  , Huang Yu-Xin  , Leng Jing  , Cui Hai-Ning  ,   School of Basic Sciences, Changchun University of Technology, Changchun 130012, China;,   Jilin University, Changchun 130012, China
Published: December 2020

The geometrical structures, electronic structures, densities of states and optical properties of undoped ZnO, and Yb2+- and Yb3+-doped ZnO are calculated based on the first-principles density function theory pseudopotential method. The calculated results show that the system exhibits lower energy and better stability after the ytterbium incorporation, and a new localized band appears between the valance and conduct. The ytterbium with different valences has different influences on the electronic structure and optical properties. The imaginary parts of dielectric function of Yb2+- and Yb3+-doped ZnO both exhibit a new peak of 0.46 eV compared with that of undoped ZnO, Their static dielectric constants increase obviously, the absorption band edges are shifted toward the longer wavelengths, and strong absorption peaks appear at 0.91 eV. The reason for the phenomena is also discussed in this paper.
Study on the atomic and electronic structures of BiOCl{001} surface using first principles
Authors: Li Guo-Qi  , Zhang Xiao-Chao  , Ding Guang-Yue  , Fan Cai-Mei  , Liang Zhen-Hai  , Han Pei-De  ,   College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China;,   College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

The surface relaxations, band structures, densities of states and surface energies of BiOCl{001} surfaces containing {001}-1Cl, {001}-BiO and {001}-2Cl are studied using first-principles based on density functional theory. The calculated results indicate that there exist obvious relaxations for the three types of {001} surfaces, especially for their double chlorine layers. The relaxation result of {001}-1Cl surface is the minimum one in the BiOCl{001} surfaces. Compared with the electronic structure of bulk BiOCl, BiOCl{001} surfaces exhibit the smaller band gap and stronger localized energy levels. Besides, both conduction and valence band of {001}-BiO shift towards the lower energy and there exist surface states at the bottom of conduction band. For {001}-2Cl, surface states are located at the top of valence band. The occurrences of these surface states can lead to the obvious reductions of band gaps for {001}-BiO and {001}-2Cl. Furthermore, the surface energy of BiOCl{001} is calculated and investigated. The analysis results show that surface energies of {001}-1Cl, {001}-BiO and {001}-2Cl are 0.09206 J·m-2, 2.392 J·m-2 and 2.461 J·m-2, respectively. Thus the {001}-1Cl possesses the minimum surface energy and the highest stability, while {001}-BiO and {001}-2Cl exhibit the higher reaction activities and are difficult to be exposed in the growth process of BiOCl crystal. Our obtained results provide the theoretical guidance for the further understanding of the facet-dependent photoreactivity of BiOCl, the fine manipulation of their photoreactivity, and the progress of actual application for BiOCl photocatalytic material.
Properties of MgB2 ultra-thin films fabricated on MgO(111) substrate by hybrid physical-chemical vapor deposition
Authors: Pan Jie-Yun  , Zhang Chen  , He Fa  , Feng Qing-Rong  ,   State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Application Superconductivity Research Center, School of Physics, Peking University, Beijing 100871, China;,   State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

We fabricate MgB2 ultra-thin films via hybrid physics-chemical vapor deposition technique (HPCVD). Under the same background pressure, the same H2 flow rate and the same deposition time, by changing the B2H6 flow rate, we fabricate a series of ultra-thin films with thickness values ranging from 10 nm to 40 nm. These films grow on MgO(111) substrate, and are all c-axis epitaxial. These films show the good connectivity, a very high Tc(0) ≈ 35-38 K and a very low residual resistivity ρ(42 K) ≈ 1.8-20.3 μΩ·cm-1. As the thickness increases, critical transition temperature also increases and the residual resistivity decreases. The 20 nm film also shows an extremely high critical current density Jc (0 T, 5 K) ≈ 2.3×107 A/cm2, which indicates that the films fabricated by HPCVD are well qualified for device applications.
Research on optical absorption and distortion driving in multiferroic HoMnO3 from the first principles
Authors: Chen Qiang  , Zhong Chong-Gui  , Yuan Guo-Qiu  , Dong Zheng-Chao  , Fang Jing-Huai  ,   School of Sciences, Nantong University, Nantong 226007, China;,   Department of Basic Courses, Nantong Shipping College, Nantong 226010, China;,   School of Physical Sciences and Technology, Suzhou University, Suzhou 215006, China
Published: December 2020

The study on magnetoelectric effect in hexagonal perovskite structure HoMnO3 has become a very important aspect in the research of multiferroic materials. In this paper, using the first principles based on the generalized gradient approximation of density functional theory and considering the noncollinear magnetic structure calculation, the effects of the interation between on-site Coulomb of d electron and spin-orbit coupling on the electronic density of states and energy band structure of HoMnO3 are calculated and investigated. The calculations show that due to the on-site Coulomb interaction, the strong hybridization of Ho 5d with O(3, 4) 2p and Mn 3d with O(1, 2) 2p orbits are considered as the origin of driving force for the ferroelectric distortion. At the same time, the distributions of the energy gap and energy band provide a theoretical support for the explanation of strong optical absorption peak in experiment. In addition, the spin-orbit coupling makes the orbital hybridization of Mn 3d with O(3, 4) 2p within the ab plane strengthened, and the partial energy degeneracy in the ab plane is eliminated. The HoMnO3 is shown to possess the insulator characteristics of typical indirect energy gap.
Effect of carbon nanotubes on the properties of polymer MOPPV-PbSe quantum dot composites
Authors: Qu Jun-Rong  , Zheng Jian-Bang  , Wang Chun-Feng  , Wu Guang-Rong  , Wang Xue-Yan  ,   Shaanxi Key Laboratory of Optical Information Technology, Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

According to single-walled carbon nanotube good conductivity, baryon transmission performance, and high photoelectric conversion performance of quantum dot composite material, in this letter, we use in situ condensation method to prepare polymer/poly (2-methoxy, 5-oc-toxy)-1, 4-phenylenevinylene (MOPPV)-single walled carbon nanotubes/PbSe quantum dot composites and use X-ray diffraction, transmission electron microscope, UV-vis absorption spectroscopy to study their characteristics. The results indicate that MOPPV, SWNT and PbSe quantum dots can be effectively combined, especially the SWNT and MOPPV form a network structure in MOPPV matrix, and PbSe quantum dots, each with an average size of 5.75 nm, can be dispersed to form a coating or mosaic structure in the polymer substrate of MOPPV-SWNT, producing the light induced charge transfer phenomenon. The study of composite photoelectric performance shows that when the polymer MOPPV, SWNT, PbSe have their mass ratio of 1: 0.3: 1, the composite photoelectric performance is best: open circuit voltage is 0.556 V, short circuit current is 2.133 mA, fill factor is 34.48%, conversion efficiency is 0.452%. Compared with the polymer MOPPV-PbSe quantum dots composite materials, the optoelectronic properties are increased by 2-3 times.
Effect of various cathode modifying layers on the performances of SubPc/C60 based inverted organic solar cells
Authors: Li Qing  , Li Hai-Qiang  , Zhao Juan  , Huang Jiang  , Yu Jun-Sheng  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Organic solar cell (OSC) with an inverted structure based on subphthalocyanine (SubPc)/C60 is fabricated by using Cs2CO3, graphene:Cs2CO3 mixed system and ZnO nanoparticles as cathode modifying materials, and its influences on the performance and stability of OSC are investigated. The results show that the OSC with an appropriate thickness of cathode modifying layer exhibits higher performance and it is more stable than those unmodified ones. The power conversion efficiency (PCE) of the Cs2CO3 and graphene:Cs2CO3 mixed material modified device is enhanced by a factor of two. Meanwhile, the ZnO nanoparticle modified device shows a highest open-circuit voltage (VOC) of 0.89 V, and the PCE increases more than 4 times. Besides, the adoptions of different cathode modifying materials and the inverted structures can effectively prevent the series resistance of the device from increasing, thereby improving the stability of the device.
The dynamics of quantum correlation between two atoms in a damping Jaynes-Cummings model
Authors: Fan Kai-Ming  , Zhang Guo-Feng  ,   Department of Physics, School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China
Published: December 2020

The geometrical quantum discord (GQD) is an effective measure of quantum correlation in quantum systems. We investigate the dynamics of quantum correlation between two atoms in a damping Jaynes-Cummings (J-C) model according to the geometrical quantum discord. The evolutional characteristics of GQD are given for both the resonant and non-resonant cases; moreover, the effect of damping on GQD is revealed.
Error bases, group algebra and quantum codes
Authors: Li Zhuo  , Xing Li-Juan  ,   State Key Lab of Integrated Services Networks, Xidian University, Xi'an 710071, China
Published: December 2020

We find a new approach to study nice error bases and quantum error-correcting codes, namely the group algebra which gives us an algebraic notation for nice error bases and quantum codes. From this algebraic notation we establish a series of linear programming bounds on the most general quantum error-correcting codes.
Progress in the study on finite time thermodynamic optimization for direct and reverse two-heat-reservoir thermodynamic cycles
Authors: Li Jun  , Chen Lin-Gen  , Ge Yan-Lin  , Sun Feng-Rui  ,   Institute of Thermal Science and Power engineering, Naval University of engineering, Wuhan 430033, China;Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering, Wuhan 430033, China;College of Power Engineering, Naval University of Engineering, Wuhan 430033
Published: December 2020

The results obtained by using finite time thermodynamics (FTT) are universal and have become one of important foundations of thermo-physics. A large number of researches have been carried out in the performance optimizations and optimal configurations of single-and multi-stage two-heat-reservoir direct and inverse thermodynamic cycles by using FTT. The obtained new results have more important practical significance for engineering design and optimization than those obtained by using classical thermodynamics. This paper reviews the new advances of the optimal performances and optimal configurations of single and multi-stage two-heat-reservoir direct and inverse thermodynamic cycles following different heat transfer laws, including the new advances of the optimal performances of endoreversible and irreversible Carnot heat engine, Carnot refrigerator and Carnot heat pump cycles under different heat transfer laws, and the new advances of the optimal configurations of two-heat-reservoir heat engine, refrigerator and heat pump cycles, as well as multi-stage complex thermodynamic cycles with different heat transfer laws.
Non-inductive modular circuit of dislocated synchronization of fractional-order Chua's system and its application
Authors: Shao Shu-Yi  , Min Fu-Hong  , Ma Mei-Ling  , Wang En-Rong  ,   School of Electrical and Automation Engineering, Nanjing Normal University, Nanjing 210042, China
Published: December 2020

In this paper, from the stability theory of fractional-order chaotic system, a kind of dislocated projective synchronization for fractional-order Chua's system is successfully completed through a nonlinear controller. Meanwhile, the fractional-order unit circuit is designed, according to the series-parallel structure of resistor-capacitor and the approximate linear transfer function expression for the complex frequency domain. Thus, non-inductive modular circuit of dislocated projective synchronization of fractional-order Chua's system is realized. The circuit simulation results prove the feasibility of the scheme. Furthermore, the method can be applied in secure communication through the improved chaotic masking. The information signal can be concealed and recovered. Numerical simulation results show the effectiveness of the proposed method.
A probable explanation on nuclear shape phase transition SU(3)–U(5)–SU(3) of the yrast-band structure in 182Os nucleus by potential energy surface
Authors: Tong Hong  , Yang Ya-Bi  , Shi Zhu-Yi  , Wang Hong  ,   College of Sciences, Guizhou Minzu University, Guiyang 550025, China
Published: December 2020

Nuclear structure phase transitions SU(3)–U(5)–SU(3) of the yrast-band structure in 182Os nucleus are successfully described, based on the association of microscopic interacting Boson model (IBM) with the γ-ray energy on spin curves (E-GOS). It is very abstract because of lack of concrete facts. A probable explanation of these one after the other phase transitions are geometrically given, with a functional relation of microscopic parameters in microscopic sdIBM-Fmax approach and potential energy surface in Bohr collective model. It is expounded that at high angular momentum, in a well-deformed nucleus, a probable way to the γ-vibrational energy can become lower than the rotational energy bcause there are a number of degeneracy states formed by quantum effect between the highter and lower excition states so as to achieve SU(3)–U(5) structue phase transition.
Study on the sensitivity of laser-pumped cesium atomic magnetometer
Authors: Li Nan  , Huang Kai-Kai  , Lu Xuan-Hui  ,   Department of Physics, Zhejiang University, Hangzhou 310027, China
Published: December 2020

A cesium atomic magnetometer based on laser-pumped rf resonance has been investigated and demonstrated experimentally. Atoms are polarized and pumped to dark states by circularly polarized light. When there exists a magnetic field, the corresponding magnetization will be precessing around the magnetic field at Larmor frequency. By means of adding a resonant rf magnetic field, the atoms will be depolarized and absorb photons again. By detecting the spectrum of the transmitted light, one can obtain the information about the external magnetic field. We build an 894nm external cavity diode laser with a frequency stabilization device, and a low noise magnetic field measurement environment. After the optimization of the magnetometer parameter and closed-loop measurement, an ultimate sensitivity of 19 fT/Hz1/2 and an intrinsic sensitivity of 1.8 pT/Hz1/2 have been achieved with the spatial resolution smaller than 2 cm.
Site-preference of Mo/Ta/W alloying additions in NixAl1-x(x=0.25,0.5,0.75)
Authors: Wang Fang  , Zhang Jian-Min  , Xue Hong  ,   Department of Physics and Electric Engineering, Weinan Normal University, Weinan 714000, China;,   College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

The characteristic properties including equilibrium lattice constants, elastic constants, cohesive energies and alloy formation energies, of stoichiometric L12 type NiAl3, L12 type Ni3Al, L10 type NiAl and B2 type NiAl, are calculated using a constructed n-body potential model combined with molecular dynamics. Furthermore, the types of point defects in the ordered NixAl1-x (x=0.25, 0.5, 0.75) systems in the nonstoichiometric case are discussed, to validate the model. The present calculation shows that the point defects are the antisites. It is in good agreement with other investigations. Then the n-body potential calculations are performed to investigate the site preference of ternary elements Mo/Ta/W alloying additions in the NixAl1-x systems. The occupation site of the ternary elements are analyzed based on the occupational energy minimizing. And the results show obviously that the occupational sites of Mo/Ta/W are the Al site.
The equivalent diameter of conical nozzle in Hagena scaling laws
Authors: Chen Guang-Long  , Xu Hong-Xia  , Ren Li  , Wang Li-Li  , Cao Yun-Jiu  , Zhang Xiu-Li  , Ping Yun-Xia  , Dong Eon Kim  ,   School of fundamental studies, Shanghai University of Engineering Science, Shanghai 201620, China;,   Department of Physics & Center for Attosecond Science and Technology (CASTECH), Pohang University of Science and Technology (POTECH), Pohang, Kyungbuk 790-784, Korea;,   Max Planck Center for Attosecond Science, Pohang, Kyungbuk 790-784, Korea
Published: December 2020

The cluster size is an important parameter in the study on the interaction of intense laser pulse with cluster jet produced by the gas adiabatic expansion through a nozzle into vacuum. The Hagena scaling law is usually used to estimate the average cluster size. However, there is the deviation of average cluster size from the prediction by the scaling law in the case that the conical nozzle is used at the high gas backing pressure. In this work, firstly the equivalent diameter of conical nozzle is re-calculated in detail, and then the relation between deq and the radial dimension of the cluster jet is obtained. As an example, the images of Rayleigh scattering light by argon cluster jet at different backing pressures are recorded to investigate the dimensions of cluster jet. And then the corresponding theoretical dimensions based on the idealized straight streamline model in the scaling law are compared with the experimental dimensions. It is found that the experimental dimension is larger than the theoretical one, and is related to the gas backing pressure. This under-estimation of theoretical cluster jet dimension leads to the over-estimation of the equivalent diameter of conical nozzle which is responsible for the cluster size deviation in Hagena scaling laws.
Application of precise integration in waveguide discontinuities with anisotropic dielectric
Authors: Yang Hong-Wei  , Mu Zhen-Feng  , Wang Zhen  ,   College of Applied Sciences, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Waveguide discontinuities with anisotropic dielectric are simulated and analyzed by the precise integration method. The discrete coefficient matrices for the cross-section of the waveguide, which contains anisotropic dielectric, are deduced from the variational principle based on single variable corresponding to the vector wave equation. Introducing the dual-variables, the stiff matrices are calculated by using precise integration method in a Hamiltonion system. Then the problem is solved by assembling the finite elements. Numerical results show accuracy and good efficiency of the method. The influence of the components of permittivity and permeability on the waveguide transmission characteristic is also discussed.
Multiband and broadband metamterial absorbers
Authors: Liu Ya-Hong  , Fang Shi-Lei  , Gu Shuai  , Zhao Xiao-Peng  ,   School of Science, Chang'an Campus, Northwestern Polytechnical University, Xi'an 710129, China
Published: December 2020

Multiband and broadband metamaterial absorbers have been proposed in the paper. The proposed absorbers are composed of metallic copper patterns on both sides of a dielectric layer. One side consists of metallic circular patches and metallic annular patches, and the other side is of metallic ground plane. Each distinct metallic circular patch unit cell or annular patch unit cell has one distinct resonant peak in a very narrow band, and these unit cells are independent of one an other. Therefore, combining two different unit cells which resonates at different frequencies can obtain dual-band absorber. Based on the theory, combining three different unit cells can obtain tri-band absorber, and combining four different unit cells can obtain the absorber which resonates at four different frequencies. In addition, the electric field distribution verifies that each distinct unit cell resonates at a different frequency. Broadband metamaterial absorber can be obtained according to the optimized combination of the different unit cells. Increasing the number of different unit cells broadens the frequency range when their resonances are closely packed together, thereby resulting in a broadband resonance.
Phonon effect on the quantum phase of a radiation field interacting with a tunneling-coupled quantum-dot molecule
Authors: Zhou Qing-Chun  , Di Zun-Yan  ,   Department of Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Published: December 2020

A full quantum theory is adopted to derive the differential equations satisfied by the state of a system that is composed of an electron tunneling-coupled quantum-dot molecule interacting with a single-mode radiation field. The phase of the field is calculated by the Pegg-Barnett quantum phase formalism under the initial condition of a coherent-state field and the tunneling excited state or ground state for the quantum-dot molecule. Phase distribution and fluctuation of the field are analyzed, the influence of interaction between phonons and the quantum-dot molecule on the Pegg-Barnett quantum phase is investigated, and the phase distribution is compared with the Husimi phase distribution of the field. Results indicate that temperature can have a marked impact on the phase evolution. The existence of phonons suppresses the field phase distribution and fluctuation in the case when the quantum dot molecule is initially in the tunneling-excited state, while it enhances the diffusion and fluctuation of the field phase in the case when the quantum dot molecule is initially in the ground state. The Husimi phase distribution and the Pegg-Barnett phase distribution agree with each other fairly well in our study.
Modified effective bandwidths of adaptive optical control systems for compensation in Kolmogorov turbulence
Authors: Guo You-Ming  , Ma Xiao-Yu  , Rao Chang-Hui  ,   Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China;,   The Key laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Based on the time serial signal generated by power spectrum density inversion, the closed-loop compensation residual variances of tracking loop and high-order error correction loop with finite error rejection -3 dB bandwidth and time delay are simulated. The data fitting results of relationships between residual variances and corresponding error rejection -3 dB bandwidths are obtained. The system effective bandwidths are modified so as to make the estimate of residual variances more precise.
Constructal entransy dissipation rate minimization of a disc on micro and nanoscales
Authors: Chen Lin-Gen  , Feng Hui-Jun  , Xie Zhi-Hui  , Sun Feng-Rui  ,   Institute of Thermal Science and Power Engineering, Naval University of Engineering; Military Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering; College of Power Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Based on constructal theory, the constructal optimization of a disc on micro and nanoscales is carried out by taking minimum entransy dissipation rate as optimization objective; and the optimal construction of the disc with minimum dimensionless equivalent thermal resistance is obtained. The result shows that the optimal construction of the disc when the size effectis taken into account is obviously different from that without considering the size effect. There exists an optimal dimensionless channel length of the high conductivity material which leads to the minimum dimensionless equivalent thermal resistance. With the increase in the number of the elemental sectors, the minimum dimensionless equivalent thermal resistance decreases first and then increases, and there exists an optimal number of the elemental sectors which leads to the double minimum dimensionless equivalent thermal resistance, which is different from the performance characteristic of the disc on a conventional scale. The entransy dissipation rate of the disc, based on the minimization of entransy dissipation rate, is reduced by 7.31% as compared with that based on maximum temperature difference, that is, the average heat transfer temperature difference of the disc is reduced by 7.31%. The optimal construction on micro and nanoscales, obtained based on minimum entransy dissipation rate, can reduce the average heat transfer temperature difference of a disc, and improves its global heat transfer performance simultaneously. The work in this paper can help to further extend the application range of the entransy dissipation extremum principle.
Constructal entransy dissipation rate minimization the problem of constracting “disc-point” cooling channels
Authors: Feng Hui-Jun  , Chen Lin-Gen  , Xie Zhi-Hui  , Sun Feng-Rui  ,   Institute of Thermal Science and Power Engineering, Naval University of Engineering; Millitary Key Laboratory for Naval Ship Power Engineering, Naval University of Engineering; College of Power Engineering, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

Based on configucation theory, the construction of a “disc-point” heat transfer with cooling channels can be optimized by taking minimum entransy dissipation rate. Thus an optimal construction of the disc-shaped assembly with cooling channels is obtained. The results show that there exists an optimal aspect ratio of the elemental sector which leads to the minimum dimensionless equivalent thermal resistance of the elemental sector at the fixed pumping power; there also exists an optimal width ratio of the elemental and first-order cooling channel to the optimal dimensionless radius of the elemental sector, which leads to the minimum dimensionless equivalent thermal resistance of the first-order branched-pattern disc at the fixed total pumping power. Moreover, the optimal width ratio of the elemental and first-order cooling channels is only relative to the number of elemental tributaries. When the radius of the central disc tends to zero, the branch-pattern disc is simplified into a radial-pattern disc, and the radius of the first-order branch-pattern disc becomes the critical radius at this point. When the radius of the branch-pattern disc is higher than the critical radius, the branch-pattern design should be adopted, otherwise the radial-pattern design should be adopted. There exists an optimal number of elemental tributaries which lead to the minimum dimensionless equivalent thermal resistance of the first-order branch-pattern disc, which is obviously different from the results of the “disc-point” heat conduction constructional optimization with high-conductivity channels. The optimal constructions of the first-order branch-pattern disc based on the minimizations of entransy dissipation rate and maximum temperature difference are different. The dimensionless equivalent thermal resistance of the disc with cooling channels based on the minimization of entransy dissipation rate is greatly reduced as compared with that based on the minimization of maximum temperature difference, and its global heat transfer performance is obviously improved simultaneously. Therefore, the combination of the entransy dissipation extremum principle and the heat convection constructional optimization further illustrates the advantages of minimization of entransy dissipation rate for heat transfer optimizations.
An experimental attempt to produce Thomson scattering with soft X-ray lasers
Authors: Wang Chen  , An Hong-Hai  , Qiao Xiu-Mei  , Fang Zhi-Heng  , Xiong Jun  , Wang Wei  , Sun Jin-Ren  , Zheng Wu-Di  ,   Shanghai Institute of Laser Plasma, Shanghai 201800, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

Thomson scattering is one of the important methods of diagnosing parameters of the hot and dense plasma state that receive widespread attention. But the probe light wavelength for Thomson scattering is more limited to the visible or ultraviolet light, so the electron density that is copable to be diagnosed is much lower than the critical density of the driving laser. In comparison, soft X-ray laser as a probe is hopeful for diagnosing higher density of plasma. The experimental attempt of soft X-ray laser Thomson scattering has been carried out using Ne-like Ge soft X-ray laser generated on the SG-II high-power laser device. According to the scattering case, incoherent scattering and coherent scattering experiments were carried out, but it is unable to obtain the significant scattering spectrum. Theoretical analysis shows that the main reason may be the focusing power density of Ne-like Ge soft X-ray laser being not enough, in the experiments. By optimizing the experimental conditions, it is expected to obtain coherent Thomson scattering in the future.
Experimental study on asymmetrical period-one discharge in dielectric barrier discharge in helium at atmospheric pressure
Authors: Dai Dong  , Wang Qi-Ming  , Hao Yan-Peng  ,   School of Electric Power, South China University of Technology, Guangzhou 510641, China;,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Dielectric barrier discharge at atmospheric pressure not only behaves as a symmetrical period-one (SP1) discharge, but can also manifest itself as an asymmetrical period-one (AP1) discharge in certain ranges of parameters. In our study, a parallel electrode configuration is adopted and a series of discharge experiments are carried out in atmospheric helium at gap widths of 1, 4, 7 and 10 mm, respectively. The effects of gap width and driving voltage frequency on the symmetry of period-one discharge are investigated. Experimental results show that: AP1 discharge can be readily observed in a large range of parameters for the gap width and driving voltage frequency. AP1 discharge is prone to occur for a larger gap width; the critical value of the driving voltage frequency, beyond which the initial discharge is AP1 discharge, decreases as the gap width is increased. Results presented in this paper preliminarily verify the numerical simulations and the analysis which were previously reported in those papers studying the effect of gap width on AP1 discharge. Thus it can be conjectured that the AP1 discharge is not caused only by parameter asymmetry of discharge configuration, it can be also an intrinsic instability in terms of high frequency under certain parameters combination of gap width and driving voltage frequency.
First-priciples study on Mn-doped LiZnAs, a new diluted magnetic semiconductor
Authors: Wang Ai-Ling  , Wu Zhi-Min  , Wang Cong  , Hu Ai-Yuan  , Zhao Ruo-Yu  ,   College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, China
Published: December 2020

The electronic structures, half-metallic and optical properties, as well as formation energy of pure LiZnAs, Mn-doped LiZnAs and Mn-doped LiZnAs with excess and deficient of Li are geometrically optimized and calculated by using the first principle density functional theory based on the full potential linearized augumented plane wave method. Results show that in the systems of Li(Zn0.875Mn0.125)As, Li1.1(Zn0.875Mn0.125) As and Li0.9(Zn0.875Mn0.125)As a 100% spin injectors is revealed, and the materials exhibit half metallic. The half metallic materials with excess and deficient of Li are more stable than Mn-doped LiZnAs. Excess of Li could improve the Curie temperature and conductivity of the material, and cause the formation energy of the system decrease. So the separation of spin and charge injection mechanisms may be achieved in LiZnAs semiconductor, and the magnetic and electrical properties of diluted magnetic semiconductor may be regulated respectively by Mn doping and Li stoichiometry. In addition, the dielectric function and the complex refractive index function in the low-energy region are found to be influenced by the stoichiometry of Li.
The research of the perpendicular magnetic anisotropy in CoFeB/AlOx/Ta and AlOx/CoFeB/Ta structures
Authors: Chen Xi  , Liu Hou-Fang  , Han Xiu-Feng  , Ji Yang  ,   The State Key Laboratory~of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The perpendicular magnetic anisotropy (PMA) of the CoFeB/AlOx/Ta structure and the AlOx/CoFeB/Ta structure with different thicknesses of both CoFeB and AlOx is studied. Magnetization curves show that the CoFeB/AlOx/Ta structure has a clear perpendicular magnetic easy axis while the AlOx/CoFeB/Ta structure does not. The cause of the asymmetrical phenomenon in the symmetric structures is analyzed. Dependence of the perpendicular coercivities on the thicknesses of CoFeB and AlOx shows that both of them can affect the strength of the PMA originating from the interfacial interaction. This work will be meaningful for the fabrication of the AlOx-based perpendicular magnetic tunnel junctions.
Numerical optimization study of PIC/PSO for RBWO
Authors: Wang Hui-Hui  , Meng Lin  , Liu Da-Gang  , Liu La-Qun  , Yang Chao  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

In this paper, based on the three-dimensional particle-in-cell (PIC) platform CHIPIC, a module of particle swarm optimization (PSO) is designed, and the code of PIC/PSO is developed. Then, the properties of multi-frequency output power are studied. Based on these properties, a class of optimization object functions is designed. With this PIC/PSO code and this class of object functions, single-frequency and dual-frequency RBWOs are optimized respectively. The optimization results show that both the single-and dual-frequency RBWOs can be optimized successfully with the corresponding object functions.
Theoretical research and experimental verification for ocean surface wind vector retrieval from airborne C-band fully polarimetric SAR
Authors: Zhao Xian-Bin  , Yan Wei  , Kong Yi  , Han Ding  , Liu Wen-Jun  ,   College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Ocean surface wind vector retrieval research on airborne fully polarimetric SAR (synthetic aperture radar) is of great significance for wind vector sounding under complex weather conditions near the coast. Starting from polarization scattering theory, we designed an ocean surface wind vector retrieval scheme for fully polarimetric SAR, by analyzing the relationship between fully polarimetric SAR sounding data and ocean surface wind vector. According to the high mobility and fully polarimetric two sounding characteristics of airborne SAR, firstly, we presented an ocean surface wind vector retrieval method based on maximum likelihood estimates for VV-polarized sounding data, and designed the flight experiment scheme. Secondly, we proposed an ocean surface wind vector retrieval method for VH-polarized sounding data, retrieved wind speed by VH-polarized ocean surface scattering model from optimum fitting with constraints, and calculated wind direction by CMOD5 geophysical model function. Using typhoon ''Haikui'' edge sounding data from airborne fully polarimetric SAR, we carried out the ocean surface wind vector retrieval experimental research. Results show that two wind vector retrieval methods can retrieve ocean surface wind vector under complex weather conditions without auxiliary information. Wind direction and wind speed retrieval root mean square errors of the former are 18.0°, 1.8 m/s, wind direction and wind speed retrieval root mean square errors of the latter are 9.3°, 1.2 m/s, and the accuracy of the latter is better than that of the former. The VH-polarized normalized radar cross section is more suitable for ocean surface wind vector retrieval under complex weather conditions, because it is independent of wind direction and radar incidence angle but has a linear relationship with respect to wind speed.
Improving the mobility of the amorphous silicon TFT with the new stratified structure by PECVD
Authors: Yu Yao  , Zhang Jing-Si  , Chen Dai-Dai  , Guo Rui-Qian  , Gu Zhi-Hua  ,   Flat Panel Display Center of Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China;,   CATIC display company, Shanghai 201100, China
Published: December 2020

The amorphous silicon TFT (α-Si thin film transistor) were fabricated in a new structure, in which the ohmic contact layer (n+ layer) and the nitride silicon insulating layer for grid (G-SiNx) were stratified. Various factors which affect the electron mobility of α-Si TFT are studied using orthogonal test. With the increase in the number of n+ layer, the electronic mobility also rises. Besides, G-SiNx should be stratified into a rapid deposition film (GH) and a low-speed growing film (GL). The thickness of GL should be increased, with the thickness of GH reduced accordingly to achieve the electron mobility gradually increasing. Finally, based on the experimental results in the orthogonal combination experiments, the α-Si TFT mobility can stably reach 0.66 cm2/V·s, much higher than the traditional volume production data (0.29 cm2/V·s).
Logarithmic minus peak second derivative time based depth prediction
Authors: Zeng Zhi  , Tao Ning  , Feng Li-Chun  , Zhang Cun-Lin  ,   College of Computer and Information Science, Chongqing Normal University, Chongqing 400047, China;,   Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

This paper proposes to use minus peak time of second derivative with respect to time on logarithmic curve of temperature versus time as a characteristic time for defect depth prediction in pulsed wave thermography. First, the paper introduces the basic principle of pulsed wave thermography, and constructs the theoretical relation between logarithmic minus peak second derivative time and the square of defect depth based on the solution of semi-infinite body. Then, two specimens of steel and aluminum were manufactured with flat-bottom holes to simulate defects. Thermographic image sequences of those two specimens were obtained by using pulsed wave thermography, and then the logarithmic minus peak second derivative time were extracted. The extracted characteristic time has a very good linearity relation with the square of defect depth, and this linearity could be used for defect depth prediction in practical applications. The advantages and disadvantages of the proposed method and the widely used logarithmic peak second derivative method are discussed.
Influence of Al doping on stability of Mg1-xTix and their hydrides
Authors: Xue Li  , Yi Lin  ,   Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Based on the density functional theory, influences of Al doping on stability and electronic structure of MgxTi1-x alloys and their hydrides were investigated. By calculating the formation energies of Mg-Ti-Al system, it is found that the best effect was obtained when the Ti-Al ratio was fixed at 1: 1, where the metal alloy was most stable, and was helpful to reversibly hydrogenate. Moreover, the partial substitution of Al for Ti atoms decreased the stability of the hydrides and improved the hydrogen storage properties. The analyses of the density of states, electron density and bond length showed that the improved properties of MgxTi1-x alloys and their hydrides with Al doping are due to the decrease in the number of bonding electrons and the weakening of Mg-H and Ti-H interactions in doped systems.
Calculation and simulation of optical fiber core and cladding mode effective refractive index
Authors: Li Li-Jun  , Lai Yong-Zheng  , Cao Mao-Yong  , Liu Chao  , Yuan Xue-Mei  , Zhang Xu  , Guan Jin-Peng  , Shi Jing  , Li Jing  ,   College of Information and Electrical Engineering, Shandong University of Science and Technology, Qingdao 266590, China
Published: December 2020

The accurate computation of effective refractive index of optical fiber core and the cladding mode are needed for the fiber structure design, mode dispersion analysis and fiber grating mode coupling research. In this paper, based on three layered optical fiber waveguide model and its accurate eigenvalue equation, by using the cut string algorithm the effective refractive index of core mode is solved. At the same time the computation results are verified by using COMSOL software. By using interval traversal algorithm the effective refractive index of cladding mode is computed. Compared with the existing algorithms, this method can avoid the loss of root during the calculation. It can also avoid the generation of odd point and can keep the normality of each mode. The simulation is based on Mathematica software. The curves relating effective refractive index of core and cladding mode to wavelength are obtained.
High order Hankel transform based on Dini expansion and its applications in beam propagation
Authors: You Kai-Ming  , Lin Yan-Ling  , Wang You-Wen  , Chen Lie-Zun  , Dai Zhi-Ping  , Lu Shi-Zhuan  ,   Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421002, China
Published: December 2020

Based on Dini series expansion, p(>0) order quasi discrete Hankel transform (pDQDHT) algorithm is deduced. The application of this algorithm in beam propagation is presented. pDQDHT algorithm is tested with various input functions and used in beam propagation through lens. Experimental results show that the pDQDHT algorithm possesses a high accuracy compared with existing Hankel transformation algorithms. The pDQDHT algorithm can be transformed forwardly and inversely and widely used in beam distribution of transmission. The implementing speed is comparable to that of general fast Hankel transform algorithm.
Vortex of an anomalous mode in Fermi gas near unitarity limit
Authors: Zhou Yu  , Zhou Qing-Chun  , Ma Xiao-Dong  ,   School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China;,   School of Physics and Electronic Engineering, Xinjiang Normal University, Urumuchi 830054, China
Published: December 2020

We investigate the dynamics of a quantized vortex in a trapped superfluid Fermi gas near the unitarity limit. By taking a trial wave function for the order-parameter of a condensate in a rotating axisymmetric trap confinement and using a time-dependent variational analysis we obtain the equations of motion and their solutions for anomalous mode. The results show that the critical rotating frequency of the trap increases when the system ranges from the left to the right side of the unitarity limit, while the period of the vortex decreases in this regime.
Application of force gradient symplectic integrators to the circular restricted three-body problem
Authors: Chen Yun-Long  , Wu Xin  ,   School of Science, Nanchang University, Nanchang 330031, Jiangxi
Published: December 2020

The kinetic energy of the circular restricted three-body problem in a rotating frame is no longer a standard positive quadratic function of moment, owing to the additional part in the non-inertial rotating frame, which leads to a difficulty in using force gradient symplectic integrators. To address this problem, we show through the calculation of Lie operators that the force gradient operator on the system is still related to the gradient of the gravitational forces from the two main objects rather than that of the resultant force of both the gravitational forces and the non-inertial force exerted by the rotating frame, just as the force gradient operator on the circular restricted three-body problem in an inertial frame. Therefore, it is reasonable to use the gradient symplectic integrators for integrating the circular restricted three-body problem in the rotating frame from a theoretical point of view. Numerical simulations describe that a fourth-order force gradient symplectic method is always greatly superior to the non-gradient Forest-Ruth algorithm in the numerical accuracy, and its optimized version is best. Because of this, the optimized gradient scheme is recommended for calculating chaos indicators, such as Lyapunov exponents of and fast Lyapunov indicators of two nearby trajectories, which is conductive to obtaining a true description of dynamically qualitative properties.
Study of an integrate-and-discharge model with symbolic dynamics
Authors: Chen Chong  , Ding Jiong  , Zhang Hong  , Chen Zhuo  ,   Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China;,   Department of Automation, Zhejiang University City College, Hangzhou 310015, China
Published: December 2020

An integrate-and-discharge model (IDM) is proposed on the basis of an integrate-and-fire model (IFM). Compared with the IFM, the IDM can obtain rich dynamic information including chaos, phase locking, etc., without using varying threshold modulation. The corresponding relation between output symbolic sequences and parameters (i.e., frequency, amplitude, resistance and capacity) of the IDM is established by using symbolic dynamics. Moreover, a method of obtaining symbolic sequence as well as an ordering rule is presented. Simulation and circuit experiment validate the correctness of the method and the rule. The results of circuit experiment show that the frequency resolution can reach up to 0.05 Hz in some frequency ranges and the amplitude resolution can reach up to 1 μA.