bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal analysis of serrated yielding in an Al-Mg alloy
Authors: Cao Peng-Tao  , Zhang Qing-Chuan  , Fu Shi-Hua  , Hu Qi  , Gao Yun  ,   中国科学技术大学，中科院材料力学行为和设计重点实验室，合肥  230027
Published: December 2020

The serrated yielding phenomenon is studied in an Al-Mg alloy during the tensile tests at ambient temperature and constant strain rate. The temperature field on the surface of the specimen changes with the increase of strain. An infrared camera is used to observe and record the temperature variations at very high time and space resolutions. According to these thermal data, the formation and propagation of the deformation bands (type A, B) are discussed and some characteristic parameters of the bands such as orientation, bandwidth, and apparent velocity are also obtained. Furthermore, the plastic deformation in the band is quantified from heat transfer equation. Both experimental and computational results show that elastic shrinkage deformation exists outside the band only during the formation of the type B band. Based on this, whether or not shrinkage deformation exists outside the band is proposed as a new standard to discriminate type A and B bands.
Design and experimental verification of a new type left-handed metamaterial structure
Authors: Sun Yong-Zhi  , Ran Li-Xin  , Wang Dong-Xing  , Wang Wei-Guang  , Chen Qiu-Lin  ,   No.8511 Research Institute of China Aerospace Science Industry Corporation, Nanjing 210007, China
Published: December 2020

The paper presents a single-sided double-S left-handed metamaterial structure in the X-band. The left-handed property of the new metamaterial has been verified by numerical simulation and experiment. Experimental results show the existence of the negative refraction within the same frequency band as indicated by the simulation. The proposed structure makes it easy to fabricate and feasible to make controllable metamaterial by incorporating itself with controllable elements.
A quick novel experimental method of metamaterial electromagnetic cloaking structure at microwave frequencies
Authors: Wen Ru-Ming  , Li Ling-Yun  , Han Ke-Wu  , Sun Xiao-Wei  ,   Radio Frequency and Energy Microsystem Technology Laboratory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
Published: December 2020

Based on Maxwell’s equations’ form-invariance to coordinate transformations, an electromagnetic cloaking structure at 10.14 GHz was designed by cylindrical coordinate transformation and made with metamaterial composed of split-ring resonators. A quick novel experiment method was used to measure the power level of the received microwave signal. The cloaking structure reduced scattering from the hidden object and meanwhile reduced its shadow effect, which was consistent with theoretical expectations. The experiment system reduced the complexity and shortened the time of measurement, which provided a new simple and effective experimental method in this field.
An optical system of scattered light digital color holography and its wave front reconstruction algorithm
Authors: Picart Pascal  , Tankam Patrice  , Peng Zu-Jie  , Li Jun-Chang  ,   (1)Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China; (2)Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China; LAUM,CNRS,Université du Maine,Av. O. Messiaen,72085 LE MANS,France; (3)LAUM,CNRS,Université du Maine,Av. O. Messiaen,72085 LE MANS,France; (4)LAUM,CNRS,Université du Maine,Av. O. Messiaen,72085 LE MANS,France; ENSIM-école Nationale Supérieure d'Ingénieurs du Mans,rue Aristote,72085 LE MANS,France
Published: December 2020

Assuming the object surface is a scattering plane and both the reference beam and the reconstructing beam are spherical waves, we study the light wave field of object beam field reconstructing plane of off-axis digital holography in detail. The object beam, the conjugate object beam and the distribution of zero-order diffraction beam as functions of the optical system parameters are obtained. According to the characteristics of digital color holography, an optical system design method for suppressing zero-order diffraction interference is proposed. Furthermore, an optimization study has also been conducted on the wave front reconstruction algorithm to avoid interpolation error. Finally, the corresponding experimental verifications are given.
Effect of the nanopariculate metal film on heat radiation
Authors: Han Yong  , Liu Yan-Wen  , Ding Yao-Gen  , Liu Pu-Kun  ,   (1)中国科学院电子学研究所，中国科学院高功率微波源与技术重点实验室，北京  100190; (2)中国科学院电子学研究所，中国科学院高功率微波源与技术重点实验室，北京  100190；中国科学院研究生院，北京  100049
Published: December 2020

The effect of the nanoparticulate metal film on the heat radiation performance has been studied by evaluating the thermal conduction of different helix slow-wave structures (SWS). The heat dissipation capabilities of the SWSs with normal barrel, with normal Ir film deposited barrel and nano-Ir deposited barrel have been analyzed and compared by experiments and simulations. With the measured data, the radiation emissivities of the employed materials have been estimated, and the accuracy has been verified by computer simulation. The experimental results and the simulation results make perfect agreement, suggesting that the nanoparticulate metal film gives much better heat radiation performance.
Dynamical simulation of pulsed chemical oxygen-iodine laser
Authors: Jin Yu-Qi  , Yu Hai-Jun  , Sang Feng-Ting  , Wang De-Zhen  , Duo Li-Ping  , Li Guo-Fu  ,   (1)Key Laboratory of Chemical Laser, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; (2)School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China; (3)School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China; Key Laboratory of Chemical Laser, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
Published: December 2020

One-dimensional pre-mixed model for a pulsed chemical oxygen-iodine laser is presented according to the reaction mechanism in chemical oxygen-iodine laser. The dependence of species concentration and optical parameters on single pulse energy and pulse duration is studied. The dynamical process is analyzed while laser is running. Gain switching during lasing is discussed.These results can provide theoretical support for the optimization of pulsed chemical oxygen-iodine laser.
Long-distance optical fiber transmission system based on hybrid Raman amplification
Authors: Rao Yun-Jiang  , Li Li  , Jia Xin-Hong  , Ran Zeng-Ling  , Zhang Tian-Hu  ,   (1)Key Laboratory of Broadband Optical Fiber Transmission & Communication Networks of Ministry of Education, University of Electronic Science & Technology of China, Chengdu 610054, China; (2)Key Laboratory of Broadband Optical Fiber Transmission & Communication Networks of Ministry of Education, University of Electronic Science & Technology of China, Chengdu 610054, China; Key Laboratory of Opto-Electronic Technology & Systems of Ministry of
Published: December 2020

A novel modified method for realizing long-distance self-adaptive compensation optical fiber transmission is proposed. Based on the hybrid Raman amplification achieved by combining the original bi-directional Raman pump with a second Raman amplification generated by a fiber laser formed by a fiber Bragg grating pair with high reflectivity, the signal light is amplified effectively and the longest self-adaptive compensation optical fiber transmission distance of 125 km is achieved in experiment for the first time, to the best of our knowledge. In addition, the ON/OFF gain, amplified spontaneous emission noise, noise figure and the signal power distribution characteristics of the system are studied experimentally and theoretically. The experimental results are in good agreement with the theoretical analysis.
Analysis of pulse distortion in Brillouin slow light using broadband pump with rectangular spectrum
Authors: Zhang Zhi-Yao  , Zhou Xiao-Jun  , Shi Sheng-Hui  , Liang Rui  ,   (1)School of Opto-electronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China; (2)School of Opto-electronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China; Key Laboratory of Broadband Optical Fiber Transmission & Communication Networks of Ministry of Education, University of Electronic Scie
Published: December 2020

Assuming a Gaussian-shaped input signal pulse, we deduced the analytical expression of the output-pulse amplitude envelope in the Brillouin slow light system utilizing broadband pump with a rectangular spectrum under small-signal gain approximation. The expression is applicable in case that the pump spectrum has a sharp rising or trailing edge and a flat top. The influence of the fiber dispersion, the stimulated Brilouin scattering (SBS) gain non-uniformity and the SBS-gain-induced dispersion on the pulse distortion has also been quantitatively analyzed. The calculated results show that the analytical solution agrees well with the numerical one if the spectrum of the signal pulse lies in the pump spectrum. SBS-gain-induced third-order dispersion is the main physical factor responsible for the pulse distortion, which also limits the retardation increase of the short pulse in the cascaded Brillouin slow light system.
High efficiency pulse compression in tapered microstructure fibers in anomalous dispersion region
Authors: Ma Wen-Wen  , Li Shu-Guang  , Yin Guo-Bing  , Feng Rong-Pu  , Fu Bo  ,   State Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

A kind of linerly tapered microstructure fiber has been proposed in this paper. The central wavelength, which is located in the anomalous dispersion region, is 1550 nm. We use an adaptive split-step Fourier method to numerically study the propagation of 1 ps laser pulse in this microstructure optical fiber. For the tapered fiber under consideration, a compression factor of 56.9 and a quality factor of 27 can be achieved in a fiber 1 m long. With the pulse shape evolution in the fiber, we find that in anomalous dispersion region, the pulse can be highly efficiently compressed by the increasing of nonlinearity coefficient and the decreasing of dispersion coefficient. Compared with the normal photonic crystal fibers, the thicker end of the tapered fiber is apt to be coupled to the laser pulse which has a larger effective mode area.
Sensitivity analysis of refractive index measurement based on intermodal interference in photonic crystal fiber
Authors: Hou Jian-Ping  , Ning Tao  , Gai Shuang-Long  , Li Peng  , Hao Jian-Ping  , Zhao Jian-Lin  ,   Key Laboratory of Optical Information Technology of Shaanxi Province, Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, School of Science, Northwestern Polytechnical University, Xi' an 710072, China
Published: December 2020

The sensitivity of an interferometer based on intermodal interference in photonic crystal fiber (PCF) has been investigated theoretically and numerically. Using the intermodal interference theory and the normalized frequency of PCF, we have analyzed the principle of the method for measuring refractive index by PCF interferomter,and obtained a variation, δns, to show the sensitivity of the PCF interferometer. From the analysis of the underlying physics of δns, we find that air holes of the first layer play an important role on the sensitivity.Compared with the conventional PCF structure,the sensitivity can be improved remarkably via employing large air holes with the shape of a combination of half circle and half oval.
Quantitative relation between the viscosity coefficient of substances under shock compression and the disturbance damping of shock front
Authors: Ma Xiao-Juan  , Liu Fu-Sheng  , Li Yi-Lei  , Zhang Ming-Jian  , Li Yong-Hong  , Sun Yan-Yun  , Peng Xiao-Juan  , Jing Fu-Qian  ,   College of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

To solve the method of measuring the viscosity of related substance at high pressures and high temperatures, Sakharov has proposed an experimental method of small disturbance in shock wave. However, the quantitative relation between the disturbance amplitude damping and viscosity in Sakharov flow field has not been given by theory. In this paper, the propagation of complex flow in Al, the development of relative disturbance amplitude on sinusoidal shock front, and the effect of viscosity on it are studied, and the relation between the relative distance of zero-point on the disturbance amplitude damping curve and viscosity is given. Compared with Zaidel’s uniform flow model and Millers’ nonuniform flow model, our Sakharov flow is close to real experiment. From our numerical analysis method, Sakharov small disturbance experiment can give a credible viscosity coefficient. We analyze the experimental data of Mineev again, and find the effective viscosity coefficient of Al at shock pressure 31 GPa and strain rate 2×106 s-1 should be modified by 1100 Pa·s, which is half of the former analytic result.
Preparation of one-dimensional Ni0.5Zn0.5Fe2O4/SiO2 composite nanostructures and their magnetic properties
Authors: Xiang Jun  , Song Fu-Zhan  , Shen Xiang-Qian  , Chu Yan-Qiu  ,   (1)School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China; (2)School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China; (3)School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China; School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

The Ni0.5Zn0.5Fe2O4/SiO2 composite nanofibers were prepared using sol-gel process combined with electrospinning. The thermal decomposition and phase inversion process of precursor nanofibers and the effects of calcination temperature and SiO2 content on the phase composition, microstructure, morphology and magnetic property of the resulting nanofibers were studied by means of thermogravimetric and differential thermal analysis, X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometer. The experimental results show that the cubic spinel structure is basically formed when the precursor nanofibers are calcined at 450 ℃ for 2 h. The average grain size of Ni0.5Zn0.5Fe2O4 contained in the composite nanofibers with 10 % SiO2 and their specific saturation magnetization and coercivity increase with increasing calcination temperature. Amorphous SiO2 additive can effectively restrain the growth of Ni0.5Zn0.5Fe2O4 nanocrystals. As a result, with SiO2 content increasing from 0 to 20 % , the average grain size of Ni0.5Zn0.5Fe2O4 in the prepared Ni0.5Zn0.5Fe2O4/SiO2 composite nanofibers calcined at 900 ℃ for 2 h decreases from 81.6 to 13.3 nm, and the specific saturation magnetization of these samples monotonically decreases, whereas the coercivity initially increases and then decreases due to the change of magnetic domain structure from multi-domain to single-domain along with the reduction in grain size. In addition, with the increase of SiO2 content, the diameter of the as-prepared Ni0.5Zn0.5Fe2O4/SiO2 composite nanofibers gradually increases and the surface becomes smooth.
Comparison of nucleation energy of nanoparticles Si formation in substrate heating and subsequent thermal annealing
Authors: Deng Ze-Chao  , Luo Qing-Shan  , Chu Li-Zhi  , Ding Xue-Cheng  , Liang Wei-Hua  , Fu Guang-Sheng  , Wang Ying-Long  ,   Key Laboratory of Photo-Electricity Information Materials of Hebei Province, College of Physics Science and Technology, Hebei University, Baoding 071002,China
Published: December 2020

In vacuum environment, the nano-crystalline silicon films were prepared by pulsed laser ablation at high temperature and room temperature respectively. The amorphous films prepared under normal temperature were thermal-annealed, which leads to crystallization. The morphology and compositon etc. of the samples were characterized by scanning electron microscopy, Raman scattering and X-ray diffraction. The results showed that the temperature threshold of Si nanoparticles formation was 700 ℃ and 850 ℃ respectively. The nucleation energy of the nanoparticles was obtained by quantitative calculation, and the reason of difference between the temperature threshold was discussed from the point of view of energy.
Raman investigation of ion-implanted ZnO films
Authors: Zang Hang  , Wang Zhi-Guang  , Pang Li-Long  , Wei Kong-Fang  , Yao Cun-Feng  , Shen Tie-Long  , Sun Jian-Rong  , Ma Yi-Zhun  , Gou Jie  , Sheng Yan-Bin  , Zhu Ya-Bin  ,   (1)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; (2)Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

ZnO thin films were implanted at room temperature with 80 keV N+ or 400 keV Xe+ ions. The implantation fluences of N+ and Xe+ ranged from 5.0×1014 to 1.0×1017/cm2, and from 2.0×1014 to 5.0×1015/cm2, respectively. The samples were analyzed using Raman spectroscopy and the Raman scattering modes of the N- and Xe-ion implanted samples varying with implantation fluences were investigated. It was found that Raman peaks (bands) at 130 and 578 cm-1 appeared in the spectra of ion-implanted ZnO samples, which are independent of the ion species, whereas a new peak at 274 cm-1 was found only in N-ion implanted samples, and Raman band at 470 cm-1 was found clearly in Xe-ion implanted samples. The relative intensity (peak area) increased with the increasing of the implantation fluences. From the comparison of the Raman spectra of N- and Xe-ion implanted ZnO samples and considering the damage induced by the ions, we analyzed the origin of the observed new Raman peaks (bands) and discussed the structure changes of ZnO films induced by N- and Xe-ion implantations.
An optimization model of wire size for multi-objective constraint
Authors: Zhu Zhang-Ming  , Wan Da-Jing  , Yang Yin-Tang  ,   School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

The optimization of wire size has become a key technology for improving the chip system performance. Based on the influence of the wire size of interconnects on the delay, power, area and bandwidth, we propose an idea of optimal wire size based on multi-objective optimization method and obtain a multi-objective constrained analytical model by curve-fitting approach. The Hspice verification shows that the analytical model presented in this paper has a high precision and the average error is less than 5%. The algorithm is simple and can effectively compensate for deficiencies in application of quality factor approach and it can be applied to computer-aided design of nano-scale complementary metal-oxide semiconductor (CMOS) system chips.
Analysis of shearing failure mode for porous materials under compression
Authors: Liu Pei-Sheng  ,   Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
Published: December 2020

The compressive behavior is one of the most basic mechanical properties of engineering materials. With the simplified structural model, the compressive failure mode is analyzed for isotropic three-dimensional reticulated porous materials, and the mathematical relationships between nominal main stress and porosity are obtained for these materials at shearing failure under uniaxial compression, biaxial compression and triaxial compression, respectively. The results show that, the porous body of brittle material species shows the tensile fracture mode of pore struts, and the porous body of ductile material species may display the shearing fracture mode of pore struts. The correspondingly obtained criteria of strength design can be referred to in applications of these materials under respective loading failure modes.
Influence of phonon and magnetic field on property of polaron in quantum ring
Authors: Zhao Cui-Lan  , Gao Kuan-Yun  ,   College of Physics and Electronic Information, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

The influence of phonon and megnetic field on property of polaron in quantum ring was studied by solving precisely the energy eigen-equation, unitary transformation and variational method. The numerical calculation for KBr quantum ring showed that the ground state energy of electron or polaron increases with increasing frequency (or the averaging radius) of the quantum ring, the polaron energy shift decreases with increasing frequency (or decreasing averaging radius) of the quantum ring, and the mean phonon number increases with increasing frequency (or decreasing averaging radius) of the quantum ring. When a perpendicular magnetic field is present, the energy levels of the polaron may cross, the ground state changes from the state with m=0 to that with m=-1,-2,-3,…, and the ground state energy makes non-periodical oscillation with increasing magnetic field strength; the polaron energy shift decreases with increasing magnetic field strength (or absolute value of quantum number |m|).
Critical behavior of the quantum Heisenberg model on three-dimensional diamond-type hierarchical lattice
Authors: Zou Wei-Ke  , Kong Xiang-Mu  , Wang Chun-Yang  , Gao Zhong-Yang  ,   College of Physics and Engineering, Qufu Normal University, Qufu 273165, China
Published: December 2020

With a real-space renormalization-group method, the anisotropic quantum Heisenberg model on three-dimensional diamond-type hierarchical lattice is studied, and the phase diagram and critical properties are obtained. For the ferromagnetic system, it is shown that there is a finite-temperature phase transition for Δ=0 where Δ is the anisotropy parameter. The order parameter and critical exponents are also calculated. For the antiferromagnetic model, we find that the critical temperature is not equal to zero for Δ=0 and there is not reentrant behavior on the critical line.
Atomistic simulation of the bcc—hcp transition in iron driven by uniaxial strain
Authors: Shao Jian-Li  , He An-Min  , Duan Su-Qing  , Wang Pei  , Qin Cheng-Sen  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

The bcc—hcp structural transition in single crystal iron under 〈001〉 uniaxial strain has been investigated by molecular dynamics simulation. The reversibility and the morphological characteristics are discussed. The stress history indicates a super-elastic deformation in the sample, while the change of temperature shows the heat release during both hcp and bcc nucleation. A laminated structure of bcc and hcp along {011} planes is obtained, where the phase boundaries for the bcc to hcp and hcp to bcc transition are found along the same plane, implying the memory effect of morphology. Stacking faults (fcc) can be formed at the interface between hcp nuclei. For the bcc to hcp transition, we observed the mergence of the stacking faults in an hcp grain and the position adjustment between hcp grains. No migration of stacking fault is found during the hcp to bcc transition. In addition, the bcc—hcp transition structure is analyzed by the radial distribution function.
First-principles study of elastic and electronic properties of several ternary transition-metal carbides
Authors: Yang Tian-Xing  , Cheng Qiang  , Xu Hong-Bin  , Wang Yuan-Xu  ,   Institute of Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, China
Published: December 2020

With the first-principles density functional theory, based on ultra-soft psuedopotential method, the structure, elastic, and electronic structure properties of WC-type RexW1－xC(x=1, 0.25, 0.75, 0), Re0.5Os0.5C, and Os0.5W0.5C were studied. It was found that the shear modulus of Re0.25W0.75C is higher than that of all synthesized and theoretically predicted 5d transition metal carbides. An analysis of Mulliken population of the bond between transition metal and C atom shows that the large shear modulus of Re0.25W0.75C is mainly due to the strong covalent Re—C interaction. The low value of the density of states on the Fermi level indicates the high stability of Re0.25W0.75C. The excellent elastic property and high stability suggest that hexagonal Re0.5W0.5C can be an ultra-hard material. We hope our calculations can stimulate the experimental research to synthesize it.
Transport properties of boron-carbon and boron-nitride quantum dot device
Authors: Li Gui-Qin  ,   Department of Physics, Tsinghua University, Beijing 100084, China
Published: December 2020

The transport properties and I-V characteristics of boron-carbon and boron-nitride quantum dot devices are investigated by first principles method. The results of the B-C and B-N devices consisting of the same number of atoms have significant differences. There is large density of states near the Fermi energy for B-C device. A wide gap in the density of states of B-N device exists and the Fermi energy lies in the gap. The B-C device reveals metal property and the B-N devices appear as semiconductors.
Effects of electrode shape on the properties of GaN-based light-emitting diode
Authors: Song Xue-Yun  , Zhang Jun-Bing  , Zeng Xiang-Hua  , Dong Ya-Juan  ,   (1)College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China; (2)College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China; Jiangsu Research Center of Engineering and Technology for New Photosorce Solid-state Lighting, Yangzhou 225009, China
Published: December 2020

Using Crosslight APSYS software, we study the effect of the electrode shapes on the electrical and optical properties for the chip structures of p-GaN, InGaN/InGaN multiple quantum well, n-GaN and sapphire. Six kinds of optimized electrodes are presented. By optimzing the electrode shape, the current density distribution are more uniform, and the current crowding effects are reduced. And for the chips with optimized electrodes their electrical and optical properties are improved, and the light emission efficiencies and transferring efficiencies have been also improved.
Dual-gate-material-based device design for unipolar metal oxide semiconductor-like carbon nanotube field effect transistors
Authors: Zhou Hai-Liang  , Zhang Min-Xuan  , Fang Liang  ,   Key Laboratory of Parallel and Distribution Processing, School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Due to carrier band-to-band tunneling (BTBT) through channel-source/drain contacts, traditional MOS(metal oxide semiconductor)-like carbon nanotube field effect transistors (CNFETs) suffer from quasi-ambipolar transport property, leaving much negative impacts on device performance and its application in circuits. To suppress such quasi-ambipolar behavior, a novel device design based on dual-gate-material device structure is proposed. The modeling results show that, with proper choice of tuning gate material, this device design can increase the ON-OFF current ratio by 6—9 orders of magnitude, tune the threshold region effectively and keep the sub-threshold slope immune from it. In addition, the quasi-ambipolar transport characteristic of C-CNFETs can be suppressed effectively using such novel device design. Further study reveals that the performance of the proposed design depends highly on the choice of tuning gate material, and the quantum capacitance in CNFETs has great effect on not only its subthreshold slope but also its transport polarity.
Fabrication of single-domain GdBCO bulk superconductors using new liquid sources by the top seeded infiltration and growth technique
Authors: Li Guo-Zheng  , Yang Wan-Min  ,   College of Physics and Information Technology, Shanxi Normal University, Xi'an 710062, China
Published: December 2020

Three new kinds of liquid source were prepared by mixing R2O3 (here R is Gd,Y or Yb respectively),BaCuO2 and CuO powders. Single-domain Gd-Ba-Cu-O bulk superconductors have been fabricated using these liquid sources by the top seeded infiltration and growth technique. The growth characteristic and microstructure of the samples have also been investigated in detail. The results indicate that, employment of the new liquid sources not only can help us reduce the experimental period and improve the fabrication efficiency, but also can be used to fabricate well-textured single domains. Additionally, using the liquid source mixed by Y2O3 or Yb2O3 can raise the utilization rate of the liquid source powders, as well as contribute to the refinement of Gd-211 particles in the molten liquid.
Experimental study on the distribution of trap levels in dielectric by photo-stimulated discharge
Authors: Zhu Zhi-En  , Zhang Ye-Wen  , An Zhen-Lian  , Zheng Fei-Hu  ,   Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, China
Published: December 2020

The distribution of trap levels in the low density polyethylene (LDPE) was studied by means of photo-stimulated discharge (PSD). And two scanning modes, continuous scanning and step scanning, were discussed. It was pointed out that there may be some problems because of the incomplete detrapping of the trapping charges for the continuous scanning. The principle and the experimental process for the step scanning were presented. It is found that there is a linear relationship between the logarithm of PSD current produced under the irradiation of the monochromatic light and the time, which is in accordance with the theoretical analysis and indicates that the retrapping effect of the carriers can be neglected. The charges are trapped in the levels of 4.36—6.22 eV in LDPE, the main part of which were trapped in the energy levels of 4.78—5.18 eV.
Band gap characteristics of two-dimensional photonic crystals made of a triangular lattice of dielectric rods
Authors: Yang Yi-Biao  , Wang Shuan-Feng  , Li Xiu-Jie  , Wang Yun-Cai  , Liang Wei  ,   (1)College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (2)Department of Physics, College of Science, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Plane wave expansion method is applied to simulate the bandgap of two-dimensional photonic crystals made of a triangular lattice of dielectric rods(circular,hexagon,square cross sections) in air. Moreover, the effect on band gap of a triangular lattice of square dielectric rods in air is discussed as a function of the rotation angle, the refractive index and the filling fraction, respectively. In the low frequency region, the maximum complete photonic band gap appears when the rotation angle equals 17 degrees. the maximum complete photonic band gap can be attained steadily as the refractive index changes continuously. In the high frequency region, the maximum complete photonic band gap appears when the rotation angle equals 30 degrees. The complete photonic band gap is observed when the refractive index is greater than 2.2. The width of complete photonic band gap reaches the maximum when the dielectric refractive index is equal to 2.6.
Identification of synthetic colors using derivative fluorescence spectroscopy and probabilistic neural networks
Authors: Chen Guo-Qing  , Wu Ya-Min  , Wei Bai-Lin  , Liu Hui-Juan  , Gao Shu-Mei  , Kong Yan  , Zhu Tuo  ,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

Excited respectively by the light with wavelengths of 300, 400, 440 and 380 nm, the fluorescence spectra of synthetic food color ponceau 4R, amaranth, allurea red and industrial dye Sudan Ⅳ have been measured. For each sample, 60 emission wavelength values were selected. The fluorescence intensity corresponding to the selected wavelength was used as the network characteristic parameters, a probabilistic neural network for kind identification was trained and constructed. It was employed to identify the 32 kinds of color solution samples. Because the fluorescence spectra of these colors overlap, the identification rate is low. In order to solve this problem, a derivative fluorescence spectroscopy was introduced. The derivative fluorescence data was used as the network characteristic parameters, a probabilistic neural network was constructed and was employed to identify colors. The identification rate is up to 100%. Based on this, a new method is presented, which combines the derivative fluorescence spectroscopy and probabilistic neural network, and can identify synthetic colors easily, quickly and accurately. This method can provide support for food safety supervision and management.
Structure of FC(O)O2 and the mechanism of its reaction with NO
Authors: Zhou Xiang  , Zhang Xuan  , Liu Ai-Fen  , Zeng Xiang-Hua  ,   College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China
Published: December 2020

Density functional theory was performed to study the reaction mechanism of the reaction of FC(O)O2 with NO. The geometric configurations of reactants, intermediates, transition states and products were optimized by B3LYP method at 6-311G(d) level. The energies of stationary points along the pathway were also calculated. Intermediates and transition states were confirmed by the results of vibrational analysis. From the results of the mechanism of the reaction of FC(O)O2 with NO, we found that the reaction of FC(O)O2+NO has four pathways and several steps. Comparing the four pathways activation energies, we can find that the pathway FC(O)O2+NO→bM→bT→FC(O)O+NO2 is the main reaction pathway and the main products are FC(O)O radical and NO2, which is in good agreement with the result reported in the literature.
Antisite defect of LiFePO4: A first-principles study
Authors: Zhang Hua  , Tang Yuan-Hao  , Zhou Wei-Wei  , Li Pei-Juan  , Shi Si-Qi  ,   Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018, China
Published: December 2020

The antisite defect, electronic conductivity and ionic dynamic properties of LiFePO4 have been investigated using first-principles density functional theory taking into account the on-site Coulomb interaction within the GGA+U scheme. Results indicate the Li/Fe exchange defect is the most preferred to occur in LiFePO4, which causes the Fe—O bond length to change in the direction favoring the formation of Li+ diffusion channels, hence improving the ionic dynamic properties of the olivine LiFePO4.
Cardiorespiratory phase synchronization and coupling direction after exercise
Authors: Cao Yin-Wen  , Song Shen-Yi  , Xiao Jing-Hua  ,   School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The coupling relation between heartbeat and respiration for the youth after exercise is investigated. We use empirical mode decomposition method as a filter to analyze the data of heartbeat and respiration obtained. It is shown that the cardiorespiratory phase synchronization still exists after exercise. Moreover, the ratio of phase-locking is different for different people and changes along with time. We proposed a measure of coupling relation based on transfer entropy, and found the coupling effect of respiration on heart is relatively large.
Study of light efficiency and lifetime of LED with different surface structures
Authors: Chen Yi-Xin  , Shen Guang-Di  , Han Jin-Ru  , Li Jian-Jun  , Guo Wei-Ling  ,   北京工业大学光电子技术实验室，北京  100124
Published: December 2020

The main problem of GaAs based AlGaInP series LED is the low light extraction efficiency and heat generation inside, which have serious impact on the LED' lifetime. In this paper, we introduce a kind of LED with new surface structure formed of surface texture and light anti-reflecting layers through the post-epitaxial processing. In this new structure, the inside light transmission route has been changed and the current spreading is enhanced, which makes much more light emit outside. With the same injected current, the new LED' output light intensity is in average 15 times as the normal LED with the same epitaxial structure, and the ratio is larger than 15 as the injected current increases. The new LED's saturation current is as high as 125 mA because of the heat is decreased inside, the accelerated aging test shows that the new LED' lifetime is as long as 13×104 h for packaged ones and 19×104 h for unpackaged ones, which is suitable for working at large injected current especially.
The band structure of symmetrical structured one-dimensional photonic crystal with single-negative materials
Authors: Zhang Zheng-Ren  , Long Zheng-Wen  , Yuan Yu-Qun  , Diao Xin-Feng  ,   (1)贵州大学电子系，贵阳  550025; (2)贵州大学光电子技术及应用省级重点实验室，贵阳  550025；贵州大学物理系，贵阳  550025
Published: December 2020

The symmetrical structured one-dimensional photonic crystal in the form of (AB)N(BA)N, is prepared and studied by transfer matrix. The results show that this kind of symmetrical structured one-dimensional photonic crystal has a special photonic gap which is insensitive to the incident angle and the disorder of the lattice. Two tunneling modes appear in this gap which are also insensitive to the incident angle and the disorder of the lattice. But the energy bands and tunneling modes of the gap are sensitive to change in the scale length of crystal lattice and the number of periodicities. With the increasing of incident angle the tunneling modes on both sides of the gap tend to degenerate. This characteristic will have a certain reference value for designing a filter with this kind of structure.
The applications of ZnO nanorods in poly ［2-methoxy-5-(2-ethyl-hexyloxy)-1, 4-phenylene vinylene］solid state cathodoluminescence device
Authors: Kan Peng-Zhi  , Zhao Su-Ling  , Xu Zheng  , Kong Chao  , Wang Da-Wei  , Yan Yue  ,   北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京  100044
Published: December 2020

A solid state cathodoluminescence (SSCL) device in which ZnO nanorods act as the field emission electrode and SiO2 as the electronic accelerating layer and poly ［2-methoxy-5-(2-ethyl-hexyloxy)-1, 4-phenylene vinylene］ (MEH-PPV) polymer as the luminescent layer is first designed. Under AC bias, SSCL of MEH-PPV is realized. The luminescence peaks are located at 580 nm and 450 nm, respectively. Compared with the device without the accelerating layer, we find that mixed-excited mode device can achieve greater brightness at long wavelength.
Experimental investigation of transfer ionization mechanism in slow He2+-He collisions
Authors: Zhu Xiao-Long  , Ma Xin-Wen  , Li Bin  , Feng Wen-Tian  , Zhang Shao-Feng  , Liu Hui-Ping  , Qian Dong-Bin  , Zhang Da-Cheng  ,   (1)中国科学院近代物理研究所，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100049
Published: December 2020

The processes of transfer ionization in He2+-He collisions at energies ranging from 20 to 40 keV have been studied experimentally by means of cold target recoil ions momentum spectroscopy. From the longitudinal momentum spectra of recoil ions, different mechanisms of transfer ionization have been obtained. The results show that one of the electrons of helium atom being captured into the ground state of projectile ion He2+ and the other one emitted to the continuum state of projectile or target are the dominant mechanisms of transfer ionization. The autoionization cross section of projectile after two-electron capture into a double excited state is small. Transfer ionization for one target electron capture into ground state and the other one into the continuum of projectile mainly occurs at large impact parameter collisions.
Model for series resistance photovoltaic performance of large-scale dye-sensitized solar cells
Authors: Huang Yang  , Dai Song-Yuan  , Chen Shuang-Hong  , Hu Lin-Hua  , Kong Fan-Tai  , Kou Dong-Xing  , Jiang Nian-Quan  ,   (1)温州大学物理与电子信息学院,温州  325035; (2)中国科学院新型薄膜太阳电池重点实验室，合肥  230031；中国科学院等离子物理研究所,合肥  230031
Published: December 2020

The dependence of photocurrent and photovoltage of dye-sensitized solar cell on the incident light intensity were investigated based on the electron continuity diffusion equation. For the first time a model was presented for power loss of series resistance in dye-sensitized solar cell, and were simulated the influence of the active-area width of nanoporous film, the effect of special contact resistance on the photo-electric conversion efficiency, as well as the silver impedance in lager-scale solar cells with active area greater than 1 cm2 under different illuminations. It was found that the efficiency strongly depends on the width of active area and the silver impedance under strong illumination, nevertheless, this dependence is not obvious under poor illumination.
Monthly extreme high-temperature response to atmospheric oscillation in China
Authors: Wan Shi-Quan  , Gu Cheng-Hua  , Kang Jian-Peng  , Zou Jian-Xin  , Hu Yu-Ling  , Xu Sha-Sha  ,   (1)兰州大学大气科学学院，兰州  730000；扬州市气象局，扬州  225009; (2)扬州市气象局，扬州  225009
Published: December 2020

Based on monthly data from 1960 to 2007 of 740 stations in China, we investigate the response of monthly extreme high-temperature (MEHT) to atmospheric oscillation through spatial Generalized Pareto Distribution (GPD) model. Here we take different groupings of North Atlantic Oscillation (NAO) and Southern Oscillation (SO) as forcing parameters in the model and evaluate the response of MEHT to atmospheric oscillation in 9 different scenarios. Results show that the impact of NAO/SO on MEHT of China is significant and different responsen to different regions, i.e. the regions showing significant dependence of MEHT on atmospheric oscillation are Northeast China, the eastern part of the Tibetan Plateau, reaches of Yangtze and Yellow river and part of South China. To be specific, 1) MEHT obviously dependent on NAO is the north-east areas, followed by the eastern Tibet Plateau; MEHT obviously dependent on SO is mainly the Eastern Tibet Plateau and the Yangtze River and Yellow River and etc.; 2) Nonlinear addition effect of NAO and SO is not obvious, their impact on MEHT is mainly one-way, that is, both acting as forcing factors， most of the region forced by them is not significantly weakened or strengthened, and the reason may be related to differences in the atmosphere oscillation spatial and temporal distribution.
Influence of atmospheric turbulence on the spreading and directionality of radial Gaussian array beams
Authors: Ji Xiao-Ling  ,   四川师范大学物理学院，成都  610068
Published: December 2020

The analytical expressions for the mean-squared beam width and the far-field divergence angle of radial Gaussian array beams in atmospheric turbulence are derived. The influence of turbulence on the spreading and directionality is studied in detail. It is shown that for the coherent combination, the radial Gaussian array beams with smaller beam number N and larger radial radius r0 are less affected by the turbulence. The spreading of radial Gaussian array beams for the coherent combination is smaller than that for the incoherent case. However, the spreading of radial Gaussian array beams for the coherent combination is more affected by turbulence than that for the incoherent case. Specially, the mean-squared beam width in the far-field for the coherent combination is the same as that for the incoherent case when N is small enough or r0 is large enough. On the other hand, the condition under which radial Gaussian array beams for both coherent and incoherent combinations have the same far-field divergence angle as a single Gaussian beam is also given. The main results are interpreted physically.
A kind of singularity-free cosmology model
Authors: Wang Yong-Jiu  , Li Ai-Gen  , Gong Tian-Xi  , Chen Ju-Hua  ,   (1)湖南师范大学物理研究所，长沙  410081; (2)湖南师范大学物理研究所，长沙  410081；Department of Physics and Astronomy，University of Missouri，Columbia，MO  65211
Published: December 2020

According to Penrose-Hawkings theorem on the singularity of cosmology，the singularity exists in the case when the source havs no rotation or acceleration，and the energy density satisfies the condition ρ+3p≥0. In this paper we study some singularity-free cosmological models under the conditions that the source has rotation. Some cosmological solutions without singularity are obtained.
Noether symmetry and the Hojman conserved quantity of the Kepler equation
Authors: Gu Shu-Long  , Zhang Hong-Bin  ,   (1)巢湖学院科研处，巢湖  238000; (2)南京晓庄学院物理系，南京  211171；巢湖学院科研处，巢湖  238000
Published: December 2020

The Noether symmetry and the Hojman conserved quantities of the Kepler equation are studied. The determining equations of Noether symmetry for the system are given. A theorem asserting that the Noether symmetry for the system leads to the Hojman conserved quantity is presented.
Hojman conserved quantities of generalized linear nonholonomic mechanical systems
Authors: Dong Wen-Shan  , Fang Jian-Hui  , Huang Bao-Xin  ,   (1)潍坊学院物理与电子科学系，潍坊  261061; (2)中国石油大学应用物理系，东营  257061
Published: December 2020

We study the Lie symmetries and Hojman conserved quantities of generalized linear nonholonomic mechanical systems. Under special infinitesimal transformations in which the time is invariable，the determining equations，the constrained restriction equations and the additional restriction equations of the nonholonomic mechanical systems are obtained. The Hojman conserved quantity of the corresponding holonomic systems，the weakly Hojman conserved quantity and the strongly Hojman conserved quantity of the linear nonholonomic systems are obtained. An example to illustrate the application of the result is given.
Second-order solution for the bottom boundary-layer velocities in surface capillary-gravity short-crested waves
Authors: Deng Zheng-Zhi  , Huang Hu  ,   上海大学上海市应用数学和力学研究所，上海  200072
Published: December 2020

Based on a recently established third-order theory for surface capillary-gravity short-crested waves，a second-order solution for the bottom boundary-layer velocities in the waves is presented by solving the Prandtl boundary layer equations，which provids an essential theoretical basis in advance for determining the resulting mass transport.
A theoretical hierarchy of the mild-slope equations for wave-current interactions in coastal waters
Authors: Huang Hu  ,   上海大学上海市应用数学和力学研究所，上海  200072
Published: December 2020

Based on total investigation, analysis and judgment of one main class of coastal wave models, the mild-slope equations， an operator representing the wide wave-current interactions in coastal waters is introduced to develop a time-dependent theoretical hierarchy of the mild-slope equations for wave-current interactions by means of the universal Hamiltonian variational principle for water waves, which reaches a comparatively high degree of harmony and unity of form and content.
LS method and qualitative analysis of traveling wave solutions of Fisher equation
Authors: Li Xiang-Zheng  , Zhang Wei-Guo  , Yuan San-Ling  ,   (1)上海理工大学理学院，上海  200093; (2)上海理工大学理学院，上海  200093；河南科技大学理学院，洛阳  471003
Published: December 2020

LS method，a new method for solving nonlinear evolution equations，is proposed. It is based on the （G′/G）–expansion method and the extended hyperbolic tangent function method，and the Poincaré’s qualitative theory is also led in. Then Fisher equation is tested as an example. The properties of integral curves for traveling wave system of Fisher equation are obtained through qualitative analysis，and then a monotonically decreasing wave-front solution of Fisher equation as a dissipative system and a monotonically increasing wave-front solution of Fisher equation as an expansion system are obtained too. Some results agree with that of Ablowitz et al. and some new results for Fisher equation are also obtained as an expansion system. The LS method is used to look for the exact solutions under the condition that the property of solution curves have been obtained through the qualitative analysis，and the target is clear. The LS method also reveals that a linear system can also be used as auxiliary equations to solve nonlinear systems.