bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and analytic potential energy function of the molecules TiO, O2 and TiO2
Authors: Chen Xiao-Hong  , Jiang Yan  , Liu Yi-Rong  , Wang Ling  , Du Quan  , Wang Hong-Yan  ,   Research Center for Advanced Computation, Xihua University, Chengdu 610039, China;,   School of Physics and Chemistry, Xihua University, Chengdu 610039, China;,   School of Physics, South-west Jiaotong University, Chengdu 610031, China
Published: December 2020

The molecular structures of ground state O2,TiO and TiO2 are calculated on the level of BP86/6-311++g(d, p) using density function theory method in Gaussian09 programs. The results show that the electron states of the ground states of the molecules respectively are O2(X3g),TiO(X3g) and TiO2(X1 A1).The stable structure of TiO2 molecule is of C2v symmetry. Each potential energy curve is obtained via scanning the single point energies of TiO and O2, which match well with those fitted with the four-parameter Murrell-Sorbie Function,according to which spectral data and force constants are deduced. The whole special analytical potential energy function of TiO2 is derived from the many-body expansion theory. And there exists a potential trap of 15.09 eV depth at 0.1652 nm (RTi-O) when the OTiO angle is fixed at 110.5, which suggests that a stable TiO2 molecule could be formed easily.
355 nm laser photoionization of formaldehyde time-of-flight mass spectroscopic study
Authors: Wang Yan  , Yao Zhi  , Feng Chun-Lei  , Liu Jia-Hong  , Ding Hong-Bin  ,   Key Laboratory of Materials Modification by Laser, Ion and Electron Beams Ministry of Education, Dalian University of Technology School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China;,   College of Science, Dalian Nationalities University, Dalian 116605, China
Published: December 2020

Multiphoton ionization of formaldehyde hydrated clusters is studied by time-of-flight mass spectrometry using 5 ns, 355 nm Nd: YAG laser beam with a power intensity of 10111012 W/cm2. The main products including protonated formaldehyde cluster series (CH2O)nH+(n=1-4), deprotonated formaldehyde clusters series (CH2O)nCHO+ (n=1-3, and two series based on molecules originating from H2CO ( the deprotonated and protonated forms ), H3CO+(H2O)n(n=1, 3, 5) and HCO+(H2O)n(n=1,3,5) are observed, and the simple structures are gave for some clusters. The transformation of formaldehyde mass peak is studied in different laser power density conditions. We find the ion peaks of formaldehyde monomer and water molecle ar a laser intensity of about 9.3 1011 W/cm2. Those mass peaks exist in envelope form and cannot be resolved under our experiment condition. The simple dynamic plasma sheath accelerating model is proposed to explain the physical mechanism of the envelope phenomenon.
Theory and simulation of the folded waveguide traveling-wave tube working in low voltage with changed period and big size
Authors: Hu Quan  ,   National Key Laboratory of Science and Technology on Vacuum Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The folded waveguide traveling-wave tube which works at 3 mm band and above the band is limited to machining accuracy and power capacity. So a slow-wave folded waveguide structure which has a finite number of cycles and whose period can be changed nonasymptotically is proposed. Firstly, the theory for effectively increasing the high-order space harmonic coupling impedance of the structure is given. And the expressions for dispersion and coupling impedance are derived. Then through the simulation, a set of optimized design parameters is achieved. Thus the operating point of the traveling-wave tube is determined. Finally, it is simulated by MAFIA. And an effective gain is obtained. The traveling-wave tube which works at low voltage, relatively large size and relatively large period, is designed.
Coherence collapse of the dual fiber Bragg grating external cavity semiconductor laser
Authors: Huang Yi-Ze  , Li Yi  , Wang Hai-Fang  , Yu Xiao-Jing  , Zhang Hu  , Zhang Wei  , Zhu Hui-Qun  , Sun Ruo-Xi  , Zhou Sheng  , Zhang Yu-Ming  ,   School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   Shanghai Key Laboratory of Modern Optical Systems, Shanghai 200093, China;,   Institute of Thin Films and Nanomaterials, Wuyi University, Jiangmen 529020, China
Published: December 2020

The preconditions and controlling factors of coherence collapse (CC) are analyzed by the rate equations and dual fiber Bragg grating (FBG) couple mode theory based on the physical process of dual FBG external cavity semiconductor lasers. A method of achieving and controlling CC multi-mode stable state is put forward for dual FBG external cavity semiconductor lasers. When the dual FBG external cavity semiconductor laser operates at the multi-mode stable state under the CC regime, the CC length reduces. The spectrum of the laser is relatively stable within the CC length. The experimental results show the output power of the laser is stable while the laser with the 3% external reflectivity is operating under the CC regime. The side mode suppression ratio is more than 45 dB. The full wave at half maximum broadens from 0.5 nm to 0.9 nm dramatically as soon as the laser operates from the incoherence collapse regime to the CC regime. The wavelength shift is less than 0.5 nm at the operating temperature of 0 ℃70 ℃. The minimum of the CC length is less than 0.5 m. The CC application of dual FBG external cavity semiconductor lasers is vital to improve the performance of optical fiber amplifiers and fiber lasers.
Experimental and theoretical study on the reconstruction of focused high order Bessel-Gauss beam
Authors: Wu Feng-Tie  , Ma Liang  , Zhang Qian-An  , Zheng Wei-Tao  , Pu Ji-Xiong  ,   College of Information Science and Engineering, Huaqiao University, Quanzhou 362021, China
Published: December 2020

Reconstruction of focused high order Bessel-Gauss beam by using thin lens is proposed. Based on the diffraction theory, reconstruction behavior of focused high order Bessel-Gauss beam is analyzed. The three-dimensional optical intensity distribution and the cross-section optical intensity distribution of the high order Bessel-Gauss beam focused by first thin lens, and then reconstructed by the second thin lens are numerical simulated. Result shows that the high order Bessel-Gauss beam passing through the single thin lens can generate Bottle beam, and the bright ring is obtained at focus. To rectify the beam divergence after focus, another thin lens is introduced at suitable position. After that, the beam keeps the Bessel distribution. Experiment is conducted, and experimental results are in agrement with the theoretical analyses. Research result shows its significance in providing a guidance for optical tweezers, particle trapping and controlling.
Simulation and analysis of time lens using cross phase modulation and four-wave mixing
Authors: Li Bo  , Tan Zhong-Wei  , Zhang Xiao-Xing  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Cross phase modulation based time lens and four-wave mixing based time lens are realized by utilizing cross phase modulation effect and four-wave mixing effect in the high nonlinear fiber, respectively. The nonlinear process in the high nonlinear fiber of cross phase modulation based time lens is simulated and analyzed. The simulation and the analysis show that the main influence factors are dispersion, self phase modulation and four-wave mixing, which can be eliminated by using the high nonlinear fiber with a certain amount of dispersion slope. Besides, the zero-dispersion wavelength of the high nonlinear fiber should be around the centre between the signal pulse and pump pulse. Then, the nonlinear process in the high nonlinear fiber of four-wave mixing based time lens is simulated and analyzed. The simulation and the analysis show that the main influence factors are dispersion, self phase modulation and other four-wave mixing, which can be eliminated by using the signal pulse and pump pulse with a certain amount of power. Besides, the powers of the signal pulse and the pump pulse can be improved by using the high non-linear fiber with a certain amount of dispersion, then the power of the output pulse can be improved, too. Finally, two kinds of time lenes are compared with each other.
Standing wave in holographic lithography
Authors: Qiu Ke-Qiang  , Liu Zheng-Kun  , Xu Xiang-Dong  , Liu Ying  , Hong Yi-Lin  , Fu Shao-Jun  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

The distribution of intensity of incident irradiation in photo-resist during exposure is figured out, and it is shown that the pattern in photo-resist on surface with high reflectivity will suffer standing wave due to the fact that the incidence irradiation interferences with the reflective beam from the photo-resist-substrate interface. The higher the reflectivity, the worse the effect of standing wave is, and it is shown that the standing wave will have adverse effects on the profile and the duty cycle of photo-resist grating and restricts the most groove depth. Inserting a layer of anti-reflection coating (ARC) can minimize the effect of standing wave. Experimental results show that it is a good way to use ARC between photo-resist and substrate to attenuate standing wave.
Electromagnetically induced grating in a Λ-type three-level atomic system modulated by a microwave field
Authors: Qiu Tian-Hui  , Yang Guo-Jian  ,   Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

We investigate the electromagnetically induced grating in a Λ -type three-level atomic system with a microwave field coupling the two ground states. The results show that the intensity of diffraction, especially the first-order diffraction, is increased remarkably due to the modulation and gain of the microwave field. If the parameters of the system are chosen properly, the intensity of the first-order diffraction goes up exponentially as the microwave intensity increases.
Broad-bandwidth and ultrafast electromagnetic response of coupled bimetal nanoantennas in few-cycle laser applications
Authors: Yang Ying-Ying  , Zhang Yong-Liang  , Zhao Zhen-Sheng  , Duan Xuan-Ming  ,   Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry,linebreak Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy Sciences, Beijing 100190, China
Published: December 2020

We explore the field enhancement and temporal response of coupled bi-metal Ag/Au core-shell nanoparticle antennas. The bimetal antennas exhibit ultra-broadband resonances and allow exploiting the local field enhancement for few-cycle laser applications such as elements with an ultrafast response in nanoplasmonic device. We study dimer, trimer and heptamer arrangements and find that the Ag/Au core-shell trimer shows that a very high enhancement factor with an amplitude exceeds 120, but still facilitates an ultrafast response. Such systems may be ideal for the generation of attosecond light pulses based on high harmonic generation by employing nanoplasmonic field enhancement.
Design of ultrabroadband double-chirped mirror pairs for ultrafast lasers
Authors: Niu Hai-Liang  , Zhang Yue-Guang  , Shen Wei-Dong  , Yu Peng  , Li Yang-Hui  , Liu Xu  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

According to the requirements for design and manufacture, we choose double-chirped method for designing the initial structure of the chirped coatings, and analyze the dependencs of reflectivity and group delay dispersion on the parameters of coatings such as the double-chirped modulation factor and the the proportion of double-chirped layers on the total thin film stack. Further more, we establish their optimal values. Based on the analysis, a chirped mirror pair, whose reflectivity is more than 99.5% and average group delay dispersion is -40 fs2 with a residual ripple of less than 20 fs2 in a wavelength range of 600 nm-1050 nm, is demonstrated, which is to be used in the Ti: Sapphire femtosecond laser system for dispersion compensation.
Unidirectional open-loop chaotic synchronization communication based on a semiconductor laser with double optical feedback
Authors: Ding Ling  , Wu Zheng-Mao  , Wu Jia-Gui  , Xia Guang-Qiong  ,   School of Physics, Southwest University, Chongqing 400715, China
Published: December 2020

Using a semiconductor laser with double optical feedback as a chaos transmitter, a unidirectional chaotic synchronization communication system is constructed, and the performances of such a system are investigated numerically. The results show that by selecting reasonable parameters, the time delay behaviour of chaotic carrier generated by the semiconductor laser with double optical feedback can be suppressed efficiently; through the strong injection from transmitter to receiver, the perfect synchronization between transmitter and receiver can be realized, and the synchronization quality has a high tolerance to frequency detuning between transmitted laser and received laser; under the additive chaos modulation encryption scheme, the 500 Mbits/s encoded message can be hidden efficiently in the chaotic carrier and successfully extracted at the receiver.
Dependence of slowing light in vertical-cavity surface-emitting laser on saturation effect
Authors: Ma Ya-Nan  , Luo Bin  , Pan Wei  , Yan Lian-Shan  , Zou Xi-Hua  , Yi An-Lin  , Ye Jia  , Wen Kun-Hua  , Zheng Di  ,   School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

The dependence of slowing light on the saturation effect in the vertical-cavity surface-emitting laser (VCSEL) is demonstrated. Combining the boundary conditions with the optical field distribution in VCSEL, the phase expression and the delay expression of the signal are derived. Based on these expressions and the rate equation, the relation between signal power and time delay is presented. Then the experimental demonstration shows the delays and the eye diagrams of a 2.5 Gbps pseudo-random binary sequence (PRBS) signal, when the VCSEL is working in the saturation condition. The theoretical and experimental results show that the high-power signal transmitted in the VCSEL could achieve better signal quality at the expense of the lower time delay. In order to obtain larger delay, on the one hand, the signal power should be controlled. On the other hand, the signal wavelength should be carefully adjusted to track the peak gain wavelength of the VCSEL caused by the saturation effect.
Radial density uniformity of dual frequency capacitively coupled plasma
Authors: Jiang Xiang-Zhan  , Liu Yong-Xin  , Bi Zhen-Hua  , Lu Wen-Qi  , Wang You-Nian  ,   School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China;,   Xinjiang Ploytechnical College, Urumqi 830091, China
Published: December 2020

The influences on dual frequency capacitively coupled plasma radial uniformity are studied with a newly developed complete floating double probe. It is found that low frequency power, discharge pressure and gap have significant effects on radial uniformity. The results show that a suitable low frequency power, discharge pressure and larger discharge gap can achieve more uniform plasma. Finally, the improved two-dimensional fluid model simulations are performed with the same discharge parameters in experiment. The radial ion density distributions are obtained for different discharge gaps. The results are almost consistent with each other.
Thermodynamic study and cellular automaton simulation of thermal stability of nanocrystalline SmCo7 alloy
Authors: Zhang Yang  , Song Xiao-Yan  , Xu Wen-Wu  , Zhang Zhe-Xu  ,   College of Materials Science and Engineering, Key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The accurate quantitative relationship between the excess volume at the grain boundary and the nanograin size in nanocrystalline alloy is deduced. The fundamental thermodynamic function of nanocrystalline alloy is derived as a function of nanograin size and temperature. By taking the SmCo7 alloy for example, the thermal stability of the nanocrystalline alloy, as well as its evolution characteristics, is studied based on the calculated excess Gibbs free energy of nanograin boundary. The results show that the nanostructure with grain size below a critical value that corresponds to the maximum excess Gibbs free energy can have higher thermal stability than a coarser nanograin structure. Once the grain size is larger than the critical value, the nanostructure may lose its stability and undergo discontinuous grain growth. By combining the nanothermodynamic model with the cellular automaton algorithm, the quantitative and visual simulations of nanograin growth in nanocrystalline SmCo7 alloy are performed. The nanograin growth behavior described by the two approaches are consistent with each other, which validates the conclusion of the thermal stability of nanocrystalline alloy, drawn from the present thermodynamic study.
Effect of copper precipitation on the formation of denuded zone in Czchralski silicon
Authors: Wang Yong-Zhi  , Xu Jin  , Wang Na-Ting  , Ji Chuan  , Zhang Guang-Chao  ,   College of Materials, Xiamen University, Xiamen 361005, China;,   State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China;,   Key Laboratory for Fire Retardant Materials of Fujian Province, Xiamen 361005, China
Published: December 2020

The influence of copper precipitation on the formation of denuded zone (DZ) in Czochralski silicon has been systematically investigated by means of optical microscopy. It was found that, for conventional furnace high-low-high annealing, the copper precipitates colonies generated along the whole crosssection in the specimens contaminated by copper impurity at the first step of the heat treatment, thus no DZ generated. While in other specimens, DZ formed. Additionally, it was found that the contamination temperature can influence significantly the thermodynamics and kinetic process of the formation of copper precipitates. The phenomena also occurred in the specimens underwent rapid thermal-low-high annealing. On the basis of the step by step investigation, it was revealed that the copper precipitates temperature and point defects type can influence the formation of DZ to a great extent.
Total ionizing dose effects on n-channel metal oxide semiconductor transistors with annular-gate and ring-gate layouts
Authors: Fan Xue  , Li Wei  , Li Ping  , Zhang Bin  , Xie Xiao-Dong  , Wang Gang  , Hu Bin  , Zhai Ya-Hong  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Two-edged-gate, annular-gate and ring-gate N-channel metal oxide semiconductor (NMOS) transistors with two different values of gate oxide thickness (tox) are fabricated in a commercial 0.35 m complementary metal oxide semiconductor (CMOS) process. The tests for the total ionizing dose (TID) effects of the transistors are carried out with a total dose up to 2000 Gy(Si). The results show that the dependence of radiation-induced threshold voltage shift on tox is larger than the power-law tox3. The TID tolerance of the low voltage NMOS (tox=11 nm) is improved from 300 Gy(Si) to over 2000 Gy(Si) by the annular-gate or ring-gate layout. For the high voltage NMOS (tox=26 nm), the annular-gate or ring-gate layout can only mitigate the growth of the off-state leakage current when the total dose is less than 1000 Gy(Si). As radiation hardening techniques, the annular-gate and ring-gate layouts have similar effects, but the annular-gate layout is slightly more effective in terms of the radiation-induced threshold voltage shift and off-state leakage current increase. The test results are theoretically explained by examining and analyzing the experimental data.
Experimental research of load effect on the anisotropic friction behaviors of gecko seta array
Authors: Wan Jin  , Tian Yu  , Zhou Ming  , Zhang Xiang-Jun  , Meng Yong-Gang  ,   State Key Laboratory of Tribology, Tsinghua University,Beijing 100084, China
Published: December 2020

The load effect on the anisotropic friction property of gecko seta arrays have been experimentally investigated on a homemade micro adhesive and friction force detect device with isolated seta arrays. The result shows that when sliding against the direction of the seta curvature to grip out, the friction force is proportional to the normal load with a friction coefficient of about 0.6. When sliding along the direction of the seta curvature to grip in, the normal preload force could be fully or partly transformed into adhesion force and repulsive force while friction force rapidly rose with the increment of the applied preload. Under the same normal preload, the lateral friction force in grip in is more than twice of that in grip out. These properties of anisotropy in friction and adhesion are determined by the micro and nano-structures of setae.
Theoretical calculations of high-pressure melting curves of five metals
Authors: Xin Jie  , Xiang Shi-Kai  , Cai Ling-Cang  ,   National Key Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Ab-initio calculation method is employed to determine the potential functions and the unknown parameters in pair-potential-based mean filed model for metals. Using the mean fields constructed from the potential functions, the vibration free volumes of atoms of metals Al, Cu, Ni, Na, and K at melting points are evaluated. The results indicate that the widely used hypothesis that the ratio of vibration free volume to the primitive cell volume of atoms in melting curve is a constant, is not correct. We provide a ratio model which can be usd to obtain much more accurate results of melting curve.
Comparison research for free diffusion and absorption status of H2
Authors: Dai Wei  , Xiao Ming  , Li Zhi-Hao  , Tang Yong-Jian  ,   Department of Physics and Electronics, Hubei University of Education, Wuhan 430205, China;,   Research Centre of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China;,   Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
Published: December 2020

The Monte Carlo method of grand canonical ensemble is used to simulate the adsorption process of hydrogen storage in carbon nanotube. Results show that the hydrogen storage capacity of (30,30) armchair carbon nanotubes is 3.74 wt% at 77 K and 2 MPa and at 77 K 7.4 wt% and 10 MPa. H2 molecules are distributed mainly at the surface of carbon nanotube.
Study of the grain size effects on electrical resistivity model for ultrathin (10-50 nm) Cu films
Authors: Wang Ning  , Dong Gang  , Yang Yin-Tang  , Chen Bin  , Wang Feng-Juan  , Zhang Yan  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Microelectronics Institute, Xidian University, Xian 710071, China
Published: December 2020

A relation between grain size and metal film is given by combining the Marom model with experiment data. Based on available theory model, taking into account the surface scattering, boundary scattering and grain size effect, an analytical resistivity model is presented for the 1050 nm thick Cu films. In particular, within a range of 1020 nm, the findings show that the proposed model with consideration of grain size effects is in good agreement with experimental results. Compared with Lim, Wang and Marom' models, the proposed method can reduce the relative standard deviations by 74.24%, 54.85% and 78.29%, respectively.
Underlying strain-induced growth of the self-assembled Ge quantum-dots prepared by ion beam sputtering deposition
Authors: Yang Jie  , Wang Chong  , Jin Ying-Xia  , Li Liang  , Tao Dong-ping  , Yang Yu  ,   Institute of Optoelectronic Information Materials, Academy of Engineering and Technology, Yunnan University, Kunming 650091, China;,   Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

The quantum-dot samples with single Ge layer and twofold stacked Ge layers are prepared by ion beam sputtering deposition. The different sizes and morphologies of quantum-dots are characterized using atomic force microscope technique. The effects of strain from the capped Ge quantum-dots on the upper Ge wetting layer and the nucleation are also investigated by the buried strain model. The results show that the non-uniform strain in the Si spacing layer which caps the buried quantum-dot layer, leads to the decrease of Ge critical thickness in the upper layer, which increases the upper dot size. The strain intensity increases with the decrease of Si spacer thickness, which results in the changes of dot shape and size in the upper layer. Furthermore, the strain also modulates the distribution of upper quantum-dot layer.
Atomistic study of deposition process of Al thin film on Pb substrate
Authors: Huang Xiao-Yu  , Cheng Xin-Lu  , Xu Jia-Jing  , Wu Eei-Dong  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Centre of Laser Fusion Research, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The deposition processes for Al atoms on Pb (Al/Pb system) surface and Pb atoms on Al surface (Pb/Al system) are studied using molecular dynamic simulations. Under the same deposition conditions, the morphologies of the two systems are very different due to the difference in energy barrier between the interfaces. The substrate temperature, the atom incident energy, and the surface orientation are discussed in terms of their effects on the atom mixing between interfaces. The simulation results show that with the substrate temperature increasing, atomic mobility is enhanced and the degree of atoms mixing between interfaces becomes greater. However, the change of the atom incident energy has little effect on the atoms mixing between interfaces. The atoms mixing is obviously different due to the change of the surface orientation. The analysis on the pair correlation function g(r) indicates that the film formed with higher incident energy has a better quality. The radial distribution function in peak of the intermixing region reveals that a PbAl intermetallic compound may be formed at the interface between Pb and Al.
Formation and inhibition mechanisms of space charges in direct current polyethylene insulation explained by energy band theory
Authors: Tu De-Min  , Wang Xia  , Lü Ze-Peng  , Wu Kai  , Peng Zong-Ren  ,   State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The key factor for developing cable plastic cross-linked polyethylene cable is to eliminate space charge in the bulk. Nowadays, it is universally received that the suppression mechanism of charge accumulation in polyethylene/nano-particle composite is the formation of deep traps for trapping charges, which, in fact, is contrary to the principles of electrical field. So in this paper, the formation and the suppression mechanisms of space charge are elaborated by the energy band theory of polymeric dielectric. Then based on the first order trap model, the formation of space charge in polymeric dielectric is deduced by dynamical equation of the trapped and detraped charges. When the deep traps are introduced into polymeric dielectric, a displacement of Fermi energy level in dielectric occurs and the electric contact of interface between electrode and dielectric changes from ohmic contact to blocking contact. The width of the depletion region associated with blocking contact is less than 100 , due to huge density of traps existing in amorphous polyethylene (PE). The tunnel effect of electron makes the electrical contact of interface a neutral contact. The space charges cannot be formed in PE dielectric under electrical stress. Finally, the conductive current as a function of electrical stress and the space charge distribution are measured respectively on both PE samples, one is pure PE and the other is the nano-particle modified PE filled with deep traps. The test results are consistent with the theoretical results.
A space charge trapping model and its parameters in polymeric material
Authors: Liao Rui-Jin  , Zhou Tian-Chun  , George Chen  , Yang Li-Jun  ,   State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044, China;,   School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, United Kingdom
Published: December 2020

In this paper, characteristics of charge trapping and detrapping in low density polyethylene under dc electric field are investigated using the pulsed electroacoustic technique. It is found that the charge decay shows very different features for the samples with different periods of applied electric field. A simple trapping and detrapping model based on two trapping levels is proposed to qualitatively explain the observation. At the same time, numerical simulation based on the above model is carried out to extract parameters (trap depths and concentration) related to the material. It is found that the space charge decaying in the first few hundred seconds, corresponding to the fast changing part of the slope, is trapped in a shallow trap with a depth in a range between 0.77 and 0.81 eV, and the trapped charge density reaches (1.1681.553) 1019 m-3 in the sample volume measured. At the same time, the space charge that decays at longer time, corresponding to the slower part of the slope, is trapped in a deep trap with a depth in a range of 0.96 and 1.01 eV, and the trapped charge density is (1.1944.615) 1018 m-3. The trap depths and charge densities of both shallow and deep traps may increase with ageing, and the parameters of two energy wells can be used as an indication of the material aging.
Influence of structural phase transition on Ferromagnetism in Fe-doped TiO2 thin films
Authors: Gu Jian-Jun  , Sun Hui-Yuan  , Liu Li-Hu  , Qi Yun-Kai  , Xu Qin  ,   College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang 050016, China;,   Department of Physics, Hebei Normal University for Nationalities, Chengde 067000, China;,   Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016, China
Published: December 2020

Fe doped TiO2 films are deposited on glass substrates using dc magnetron sputtering. The crystal structures and the magnetic properties of these films are studied. Room temperature ferromagnetism is observed in each of all the Fe doped TiO2 films. The source of magnetism is related to an exchange interaction between the transition-metal (Fe) ions and localized strapped holes. The maximal magnetization is observed in a TiO2 film with Fe concentration 7%. With the increase of Fe concentration, the crystal structure of TiO2 film transforms gradually from anatase phase to rutile phases, and magnetism in the film weakened. The changes of crystal structure and crystallization in TiO2 film resulting from Fe doping affect the change of ferromagnetism in the film.
Measuring and analyzing the cooling dielectric spectra of the -relaxation in dimethyl phthalate series materials
Authors: Wei Lai  , Zhou Lan-Lan  , Lu Gui-Hua  , Zhang Wen  , Zhang Wu-Zhi  , Zhang Shang  , Feng Yong-Hong  , Zhou Heng-Wei  , Zhang Jin-Lu  , Huang Yi-Neng  ,   Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters, and College of Physical Science Technology, Ili Normal University, Yining 835000, China;,   Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
Published: December 2020

The cooling dielectric spectra of the -relaxation in dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and dioctyl phthalate series materials are measured, and the average relaxation time of the -relaxation a as a function of temperature T is obtained. By fitting the a data to the empirical Vogel-Fulcher-Tammann law a = 0 exp (A/(T-T0)), the values of 0, A and T0 of the series materials are obtained. The results of 0, A, T0 and Tg show some variation regularities with the carbon number n in the side-group of dimethyl phthalate series molecules. And specifically, with the increase of n, the internal degrees of freedoms of the molecules, A and Tg indicate almost the same tendencies, i.e. first coming down and then going up, while 1/0 and T0 have quite similar behaviors, i.e. first reducing rapidly and then keeping at near constant values.
Band shifts of Tm2O3 films epitaxially grown on Si substrates
Authors: Wang Jian-Jun  , Fang Ze-Bo  , Ji Ting  , Zhu Yan-Yan  , Ren Wei-Yi  , Zhang Zhi-Jiao  ,   College of Physics and Electronic Information, China West Normal University, Nanchong 637002, China;,   Department of Physics, Shaoxing University, Shaoxing 312000, China;,   Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, China
Published: December 2020

The single crystalline Tm2O3 films are deposited on Si(001) substrates by molecular beam epitaxy, by using x-ray photoelectron spectroscopy, the valence and the conduction-band shifts of Tm2O3 to Si are obtained to be 3.1 0.2 eV and 1.9 0.3 eV, respectively. The energy gap of Er2O3 is determined to be 6.1 0.2 eV. The results of the study show that the Tm2O3 could be a promising candidate for high-k gate dielectrics.
High-rate deposition of microcrystalline silicon thin film by multi-step method
Authors: Gao Hai-Bo  , Li Rui  , Lu Jing-Xiao  , Wang Guo  , Li Xin-Lin  , Jiao Yue-Chao  ,   Key Laboratory of Material Physics of Education Ministry, School of Physical Engineering, Zhengzhou University, Zhengzhou 450052, China;,   College of Science, Henan University of Technology, Zhengzhou 450002
Published: December 2020

To improve the uniformity of crystalline volume fraction (Xc) along the deposition direction in microcrystalline silicon films, very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD), combined with parameters smoothly changed two-step method, is adopted to prepare high-rate microcrystalline silicon films on glass subtrates. With a power density of 2.1 W/cm2, silane concentration between 6% and 9.6%, a difference between Xc measured in the film direction and that in the glass direction, is just 2 percent. With a silane concentration of 9.6%, Xc, measured in the film direction and the glass direction respectively reach 50% and 48%, close to 2 percent, relative difference just 4 percent, whereas the deposition rate reaches 3.43 nm/s. What is more, Xc difference can reduce to 1 percent by strictly controlling the transitional parameters. It shows that the new deposition method not only curb the incubation layers and improve the vertical structure, but also give a larger range for film optimizing in the future.
Eliminating the influence of attitude on brightness temperatures measurement for polarimetric microwave radiometer
Authors: Lu Wen  , Yan Wei  , Wang Rui  , Wang Ying-Qiang  ,   Institute of Meteorology, People's Liberation Army University of Science and Technology, Nanjing 211101, China
Published: December 2020

In order to meet the requirement of accurate detection for polarimetric microwave radiometer, in this paper, we study on the influence of attitude on brightness temperatures received by the radiometer. Correction for brightness temperatures errors is also analyzed. The relationship between the misspecification of the attitude and the incidence angle together with polarization rotation angle is established. The variation of brightness temperatures with the change of incidence angle and polarization rotation angle is simulated. We simulate the original observational brightness temperatures of the radiometer. A method based on the radiative transfer model for compensating attitude offset to correct brightness temperatures errors is presented. Taking vertical brightness temperature and the third Stokes parameter brightness temperature for example, our method can eliminate the influence of attitude offset on the observation of brightness temperatures effectively, the result can satisfy the accuracy requirement of data preprocessing for polarimetric microwave radiometer.
High stability and linear tuning wavelength tunable resonant cavity enhanced photo-detector grown on GaAs
Authors: Wang Jie  , Han Qin  , Yang Xiao-Hong  , Ni Hai-Qiao  , He Ji-Fang  , Wang Xiu-Ping  ,   State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;,   State Key Laboratory for Superlattices and microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

A wavelength tunable resonant cavity enhanced photo-detector grown on GaAs is fabricated. The quantum wells of In0.25Ga0.75As/GaAs in the active region are grown by molecular beam epitaxy. The peak of the response spectrum at 0 work bias is located at 1071 nm. When the tuning voltage rises from 0 V to 21 V, the peak shows a blue shift of 23 nm, reaching 1048 nm. Statistical results show that there is a stable accurate corresponding relation between the tuning voltage and the response peak. The relation is approximately linear when the tuning voltage is greater than 5 V. Some theoretical analysis is performed on the test results.
High performance resonant cavity light emitting diode with dielectric distributed Bragg reflectors
Authors: Tang Yi-Dan  , Shen Guang-Di  , Guo Xia  , Guan Bao-Lu  , Jiang Wen-Jing  , Han Jin-Ru  ,   Key Laboratory of Opto-electronics Technology, Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Dielectric distributed Bragg reflectors (DDBRs) with SiO2/Si3N4 are grown by PECVD alternately. For the etching of DDBR, dry and wet etching methods are both used. The reflectivity of DDBR is calculated by transfer matrix method, and the high performance DDBR structure is fabricated to obtain optimal reliability, we find that the enhancement factor along the cavity axis and the integrated emission enhancement factor of RCLED with 1.5 RC DDBR are 1.058 and 1.5 respectively, a full width at half maximum is 10.5 nm by PL analysis. Then, high performance RCLEDs are fabricated by using an optimal DDBR structure. The devices with DDBR show many advantages: a lower turn-on voltage of 1.78 V, under 20 mA injection current, the output power and the luminous efficiency of the device with/without DDBR gain the improvements of 27.7% and 26.8% respectively, under 0-100 mA injection current, the output power has unconspicuous downtrend, better characteristic saturation of optical power and temperature stability.
X-ray photon counting detector for x-ray pulsar-based navigation
Authors: Hu Hui-Jun  , Zhao Bao-Sheng  , Sheng Li-Zhi  , Sai Xiao-Feng  , Yan Qiu-Rong  , Chen Bao-Mei  , Wang Peng  ,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A prototype of x-ray photon counting detector is proposed for x-ray pulsar navigation. The detector consists of CsI photocathode, micro-channel plate (MCP) electron multiplier, collect anode and electronic readout. The sensitivity, the temporal resolution, and the dead time are tested, and the results show that the sensitivity of the detector is 5.2× 103 A/W at 5 keV, the temporal resolution is 1.1 ns, and dead time is 100 ns.
Variational iteration solution method of soliton for a class of nonlinear disturbed Burgers equation
Authors: Wu Qin-Kuan  ,   Dept. of Basic Courses, Nanjing Institute of Technology, Nanjing 211167, China
Published: December 2020

The problem of solving a class of nonlinear disturbed Burgers equation is studied. Using the variational iteration method, a functional is introduced, then its variational is computed, and the iteration expansion is constructed. The soliton solutions of the approximate expansion are obtained from the corresponding equation.
Numerical simulation of temperature field of DE-GMAW and its comparison with experimental measurements
Authors: Shi Yu  , Han Ri-Hong  , Huang Jian-Kang  , Fan Ding  ,   State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China;,   Key Laboratory of Non-ferrous Metal Alloys and processing, The Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

Based on the features of DE-GMAW (double electrode gas metal arc welding), a new hybrid heat-source model that is suited for the DE-GMAW is established. Using this heat-source model, the temperature fields of DE-GMAW wtih different welding parameters are simulated. According to the simulation results with different welding parameters, in this article we analyze the influence of welding parameters on the heat input of base metal in DE-GMAW. To verify the rationality of the hybrid heat-source model of DE-GMAW, the simulation results of the temperature field are compared with the results obtained from the experiment that is carried out under the same condition. The research results indicate that under the same total current, the heat input of base metal decreases gradually with the increase of by-pass current. Moreover, the closer to the welding line the greater the decrease rate of the heat input of base metal is. The study and the comparison of the thermal cycle curve of measured points show that the simulation results are in good agreement with the experimental results. These results indicate that the temperature field model is accurate and the hybrid heat-source model is reasonable.
Nonlinear waves in an inhomogeneous quantum plasma
Authors: Mao Jie-Jian  , Yang Jian-Rong  , Li Chao-Ying  ,   Department of Physics and Electronics, Shangrao Normal University, Shangrao 334001, China;,   Department of Physics, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

For an inhomogeneous quantum magnetoplasma system with density and temperature gradients, a two-dimensional nonlinear fluid dynamic equation is derived in the case where the collision frequency between ions and neutrals is minor. The shock, explosion and vortex solutions of the potential for this system are obtained. The changes of the potential in the dense astrophysical environment are discussed. It is shown that the strength of the shock and the width of the explosion are both enhanced with the density increasing (equivalently, the normalized quantum parameter decreasing), but with the drift velocity decreasing (equivalently, the density and temperature gradients decreasing); the potential always tends to a stable value with the spatiotemporal phase increasing, and the system approaches finally to a stable state. Besides, the temporal and spatial distributions of the vortex potential display a stable and period vortex street.
Data link layer of selective repeat protocol based on quantum teleportation
Authors: Yang Xiao-Lin  , Zhou Xiao-Qing  , Zhao Han  , Wang Peng-Peng  ,   College of Physics Science and Information Engineering, Jishou University, Jishou 416000, China
Published: December 2020

In this paper we study the quantum selective repeat protocol of data link layer based on quantum teleportation. When two sites are communicating in the physical layer, the sender divides a series of qubits intom frames by adding auxiliary qubits. After continuously transmitting m quantum frames, the receiver judges whether he receives the correct quantum frame according to the classical information provided by the sender. If the receiver receives the correct quantum frames, he returns confirmed frames using the quantum channel. If the correct quantum frames are not received, the receiver does not return denial frames. The sender judges quantum frames which he must resend according to the received confirm frames in setting time. Because the sender resends only the quantum frames which are lost or mistaken, this protocol reduces the transmission delay and improves communication efficiency. In the entire course of communications, the classical channel is used only to transmit the survey information, thus its burden is reduced.
Limit induced bifurcation due to converter transformer tap and DC controller limit
Authors: Tan Tao-Liang  , Zhang Yao  , Zhong Qing  ,   Yangjiang Power Supply Bureau, Yangjiang 529500, China;,   School of Electric Power, South China University of Technology, Guangzhou 510640, China
Published: December 2020

The limit induced bifurcation (LIB) in AC/DC power system caused by converter transformer tap and extinction angle limit under the control mode of constant current in rectifier and constant voltage in inverter is studied in this paper. The reason why the singularity induced bifurcation does not occur while the hard limit encounters is analyzed. The transformer ratio should be larger than a critical value while LIB occurs and the formulas for critical value of LIB in defferent types are derived in this paper. The sensitivities of critical value to parameters are calcaulated, from which some bifurcation points are eliminated and the stable region is augmented. And, the effects of field voltage limit on critical value and stable region are discussed. Finally, a mechanism of limit induced bifurcation is proposed. The increase of reactive power consumed in converter transformer and the decrease of the reactive power compensation in converter AC bus and the transform of control mode result in the system destabilization due to the lack of reactive power.
The dynamics of spiral waves in three-layer excitable medium with circular feedback coupling
Authors: Li Guang-Zhao  , Chen Yong-Qi  , Tang Guo-Ning  ,   College of Physics and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

The dynamics of spiral wave in a three-layer excitable medium with circular feedback coupling is studied, based on the Bär model. The numerical results show that the drifting or meandering of spiral waves in the subsystems can be observed when the coupling strength is small. When the coupling strength is slightly big, the interaction between subsystems may cause spiral waves in some subsystems to move out of the boundaries of the subsystems. The subsystems return to rest state. In addition, the interaction may generate the transition from spiral wave state to target wave or turbulence states in some subsystems. The phenomenon that the asymptotic state of a subsystem depends on the initiation condition is observed. With the further increase of the coupling strength, the approximate generalized synchronization of the spiral waves in three subsystems is established. When the coupling strength is bigger, the spiral waves evolve into turbulence.
New equivalence method of integrated three-phase AC-DC system based on differential homology and chaotic analysis
Authors: Zha Xiao-Ming  , Zhang Yang  , Sun Jian-Jun  , Fan You-Ping  ,   School of Electric Engineering, Wuhan University, Wuhan 430072, China
Published: December 2020

Integrated three-phase AC-DC system is widely used in modern society with series of base units. In this paper we deduce a general equation of the system in an affine coordination in order to use the differential geometry. Firstly, a new approximate equivalence method is presented by differential homology, including the judgment criterion and the main parameters of the equivalent model. Besides, the chaotic analysis relates different parameters to different situations which can accurately be simulated by PSCAD/EMTDC. And then calculation of eigenvalue indicates that the equivalence method is useful and simple. Finally, a simulation shows the accuracy and the applicability of the method.