bluuebunny/crossref_metadata_2025 huggingface dataset:
Shell model study of Gamow-Teller transitions of nuclei 13N
Authors: Zhi Qi-Jun  , Zheng Qiang  ,   School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001,China;,   School of mathematics and computer science, Guizhou Normal University, Guiyang 550001,China
Published: December 2020

Recent researches show that the beta decay of 13N can affect the electron abundance before the collapse of SNe Ia supernovae. Based on the shell model, the Gamow-Teller transition strengths from ground state to ground state and trom ground state to excited state of 13N are calculated and the results are compared with theoretical results and also with experimental data. The electron capture rates at different temperatures and densities are calculated and the effect of ground state on excited state transition is discussed. It is shown that due to the transition from ground state to excited state, the electron abundance of the SNe Ia supernovae decreases and the contributions are determined mainly by the low-lying excited states.
The study on structures and properties of Run and Run Au(n=112) clusters by density functional theory
Authors: Ge Gui-Xian  , Jing Qun  , Cao Hai-Bin  , Yang Zeng-Qiang  , Tang Guang-Hui  , Yan Hong-Xia  ,   Key Laboratory of Ecophysics and Department of Physics, School of Science, Shihezi University, Xinjiang 832003,China
Published: December 2020

The geometries, the stabilities, and the electronic properties of Run Au and Run (n=112) clusters are systematically investigated by the density functional theory. The results suggest that the lowest energy structures for Run Au clusters can be obtained by substituting one Ru atom in Run+1 clusters with Au atom. The geometries of Run Au clusters are similar to those of Run+1 clusters except local structural distortions. The second-order difference and fragmentation energy show that Ru5, Ru8, Ru5Au, and Ru8Au clusters are the most stable among these studied clusters, the doped Au atoms do not change the relative stabilities of Run clusters; the Au impurities increase the chemical activities of Run clusters, and the value of gap is determined mainly by the electron-pairing effect; the doped Au atoms increase the total magnetic moments of Run Au in most cases.
Theoretical study on (e,2e) process for helium in perpendicular geometry
Authors: Yang Huan  , Xing Ling-Ling  , Zhang Sui-Meng  , Wu Xing-Ju  ,   The Center of Basic Experiment, West Anhui University, Lu’an 237012, China;,   Institute of Atomic and Molecular Physics,School of Materials and Chemical Engineering, West Anhui University, Lu’an 237012, China;,   School of Mechanism and Electrical engineering, West Anhui University, Lu’an 237012, China
Published: December 2020

The triple differential cross section for electron impact ionization of helium in the perpendicular geometry is calculated by use of BBK model and modified BBK model. The results of the present work are compared with experimental data. The structure of the cross section is analysed and the exchange effects are discussed systematically.
Optical quality of high-power fiber laser beams propagating through collimating systems
Authors: Tao Ru-Mao  , Si Lei  , Ma Yan-Xing  , Zou Yong-Chao  , Zhou Pu  ,   College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Within the framework of the ray optics theory, the effects of heating effect and geometric aberration on optical quality of fiber laser beam are calculated and analyzed. An analytical expression for the beam quality parameter M2 of fiber laser beam propagating through a multilens optical system is derived as a function of the system parameter. The optical quality of high-power laser beam propagating through a collimating system is investigated. It is shown that a best optical quality can be found as the laser power increases and the corresponding laser power depends on the collimating system parameter. The investigation presents a reference for the design of high-energy fiber laser collimating systems.
Investigation of optical limiting based on the combination of stimulated Brillouin scattering and metal-phthalocyanine complexes
Authors: Hasi Wu-Li  , Geng Xi-Zhao  , Jin Chao-Ying  , Fan Rui-Qing  , Lin Dian-Yang  , He Wei-Ming  , Lü Zhi-Wei  ,   Institute of Opto-Electronics, Harbin Institute of Technology, Harbin 150080, China;National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150080, China
Published: December 2020

In order to improve the optical limiting performance based on stimulated Brillouin scattering (SBS), an optical limiter based on the combination of SBS and metal-phthalocyanine complexes (MPCs) is proposed in this paper. The output energy of the combination optical limiting designed based on SBS followed by MPCs shows flatter characteristic. The dependence of the output energy of optical limiting based on this combination approach on the input light intensity is numerically simulated, and validated in a continuum Nd:YAG seed-injected laser system. The theoretical and the experimental results indicate that the output energy based on this approach has a flatter characheristie than based on a single SBS.
Theoretical investigation on refractive index sensor basedon Bragg grating in micro/nanofiber
Authors: Liang Rui-Bing  , Sun Qi-Zhen  , Wo Jiang-Hai  , Liu De-Ming  ,   School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;,   National Engineering Laboratory for Next Generation Internet Access System, Wuhan 430074, China
Published: December 2020

Subwavelength and nanometer diameter optical fibers have the optical property of enhanced evanescent fields, which makes them very sensitive to the index change of the ambient medium. In this paper, a novel refractometric sensor based on fiber Bragg grating in micro/nano-fiber (MNFBG) is proposed, integrating the enhanced evanescent fields of micro/nano-fiber (MNF) with wavelength choice feature of FBG, and the fabrication about MNFBG is discussed. Refractive index sensing characteristics is comprehensively investigated in theories, and the simulation of sensing the variation of ambient refractive index is performed by using the software of OptiGrating. Results show the sensitivity of the MNFBG is increasing with the decrease of the radium of the MNF. MNFBG with the radius of 400nm can achieve the sensitivity as high as 993nm/RIU. This value is enhanced by 170 times over that of the FBG with etched cladding, which demonstrates that MNFBG has great potential of application in miniaturized, high-sensitivity refractometric sensors.
Characteristic study of polymer electro-optic modulator based on extended wheeler's conforming mapping method
Authors: Wen Yue  , Zhang Xiao-Xia  , Huang Chun-Yang  , Shen Jie  ,   School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 641005,China
Published: December 2020

An extended Wheeler's conforming mapping method is proposed to analyze the characteristic parameters of the multilayer based on the simple Wheeler's transformation. The explicit expression between the microwave characteristic parameter and the each layer parameter is obtained. Compared with the results obtained by the quasi-static finite element method (QS-FEM), our results show that the present approach can not only accurately evaluate the characteristic parameters of the multilayer but also have a great computational efficiency. Based on this method, a modified structure of the typical electro-optic modulator is given. The velocity matching and the impedance matching can be achieved simultaneously by adding a compensation layer.
A density functional theory study of absorption behavior of CO on Au-doped single-walled carbon nanotubes
Authors: Zhang Jian-Dong  , Yang Chun  , Chen Yuan-Tao  , Zhang Bian-Xia  , Shao Wen-Ying  ,   College of Chemistry, Qinghai Normal University, Xining 810008, China;,   Visual Computing and Virtual Reality Key Laboratory of Sichuan Province,Sichuan Normal University, Chendu 610068, China;,   Liaoning Yu Cai High School, Zhuanghe 116400,China
Published: December 2020

The absorption behaviors of CO on the (8,0) semiconducting intrinsic and gold doped (Au-doped) single-walled carbon nanotubes (SWCNTs) are investigated by the density functional theory because superior sensitivity of carbon nanotube to many toxic gases becomes a field of growing interest. It is shown that CO molecules can be absorbed to Au atoms on the wall of Au-doped SWCNT with a bingding energy as high as 2.1eV,and can attract lager charge transfer 0.23. Compared with the intrinsic SWCNT, the Au-doped SWCNT presents a high sensitivity to CO in terms of the calculated geometrical structures and electronic properties, Furthermore, the calculated electron densities of two representative adsorption positions show that Au-doped SWCNT electron clouds overlap more on the top of carbon adsorbed CO. By comparison with the oxygen absorption on SWCNT, we infer that the molecular CO absorbed on Au-doped SWCNT can induce significant change in the conductivity of SWCNT. So Au-doped SWCNT is expected to be a potential candidate for detecting the presence of CO.
Comprehensive Survey for the Frontier Disciplines
Authors: Qin Jie-Ming  , Tian Li-Fei  , Zhao Dong-Xu  , Jiang Da-Yong  , Cao Jian-Ming  , Ding Meng  , Guo Zhen  ,   Institute of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China;,   College of Physics, Inner Mongolia University of the Nationalities, Tongliao 028000, China;,   Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Published: December 2020

Morphologies of one-dimensional ZnO nanostructures (nanowires, nanobelts, etc.) and their characteristics are introduced. Methods of growing one-dimensional ZnO nanostructures and the relevant devices are demonstrated comprehensively, e.g. hydrothermal and chemical vapor deposition and so on. Progress in applications including light-emitting diodes and nanogenerators is provided. Finally, the future developing trend of one-dimensional ZnO nanostructures is presented and some novel means, techniques, etc. are also proposed.
Effects of A-site equivalence and non-equivalence substitution on polarization properties of K0.5Na0.5NbO3 lead-free piezoelectric ceramics
Authors: Zhao Jing-Bo  , Du Hong-Liang  , Qu Shao-Bo  , Zhang Hong-Mei  , Xu Zhuo  ,   Science College, Air Force Engineering University, Xi’an 710051, China;,   State Key Laboratory of Electrical Insulation Power Equipment, Xi'an 710049, China;,   Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China;
Published: December 2020

The effects of A-site equivalence and non-equivalence substitution on polarization temperature and electric field of K0.5Na0.5NbO3 lead-free piezoelectric ceramics are studied, and the results show that the ceramics sample of A-site equivalence is independent of polarization temperature and electric field, which can improve the piezoelectric constant. On the contrary, the ceramics sample of A-site non-equivalence substitution is sensitive to polarization temperature and electric field, constraining the piezoelectric properties.
Magnetocapacitance effect of magnetoelectric laminated composite at resonant frequency
Authors: Wang Wei  , Luo Xiao-Bin  , Yang Li-Jie  , Zhang Ning  ,   Magnetoelectronic Lab, School of Physics and Technology, Nanjing Normal University, Nanjing 210046, China
Published: December 2020

A sandwich-like laminated composite of TbxDy1-xFe2-y/Pb(Zr, Ti)O3/TbxDy1-xFe2-y is prepared with a bonding method. The experimental study shows that the capacitance of the sample has several resonant peaks in the range of the frequency manipulated, and the resonant points shifte with the increase of applied magnetic field. The impedance of the sample also varies from capacitive to inductive ones at about the resonant point by changing the magnetic field. Giant positive and negative magnetocapacitance effects are observed simultaneously near the resonant frequency. From the constitutive equations of magnet and piezoelectrics involved, the capacitances as functions of frequency and magnetic field were theoretically modeled respectively. The results show that the experimental results are in good agreement with the theoretical ones, suggesting that the magnetocapacitance effect of the layered composite of magnetostriction/ piezoelectric originates from the magnetic field-controlled compliance coefficient of the ferromagnetic phase in the sample.
Comprehensive Survey for the Frontier Disciplines
Authors: Qiao Jian-Liang  , Chang Ben-Kang  , Qian Yun-Sheng  , Gao Pin  , Wang Xiao-Hui  , Xu Yuan  ,   School of Electronic Engineering and Optoelectronic Techniques, Nanjing University of Science and Technology, Nanjing 210094, China;,   Department of Electronic and Electric Engineering, Nanyang Institute of Technology, Nanyang 473004, China
Published: December 2020

The present status of research on negative electron affinity (NEA) GaN vacuum surface electron source is discussed with considering the latest research conclusions from our country and foreign country. Some valuable results about GaN vacuum electron source have been obtained including the theory of photoemission, the surface depuration method, the activation technique for GaN photocathode, the measurement of spectral response, the characteristics of material etc. The mechanism of photoemission for NEA GaN vacuum electron source is studied preliminarily. The depuration method of obtaining the atom cleanness surface is given. The GaN material is effectively activated with Cs or Cs/O. The spectral response of GaN vacuum electron source material is measured. The material characteristics affecting the quantum efficiency of the electron source are analyzed. The next investigation is also mentioned.
Mean response time of FitzHugh-Nagumo model in the presence of non-Gaussian noise and a periodic signal
Authors: Xu Chao  , Kang Yan-Mei  ,   Department of Applied Mathematics, School of Science, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

The dynamics of the FitzHugh-Nagumo (FHN) model in the presence of non-Gaussian noise and a periodic signal is analyzed in this paper. We observe the resonant activation (RA) and the noise enhanced stability (NES) phenomena and analyze the effect of the non-Gaussian noise on the neuron dynamics by the mean response time (MRT) of the neuron. Some significant changes of the resonant activation (RA) and noise enhanced stability (NES) phenomena due to the correlation time of the noise are found. We observe that the NES effect is suppressed and RA phenomenon is unchanged, i.e., the non-Gaussian noise effectively enhances the efficiency of the neuronal response, for the case of strongly correlated noise. We report on the MRT as a function of q, and find that MRT is nonmonotonicaly dependent on q with a minimum at a finite q value which is smaller than 1. Finally we obtain that in certain situations, the non-Gaussian noise causes rescaling phenomenon, then the effect of non-Gaussian noise can be reproduced by a white noise.
Incremental regularized extreme learning machine based on Cholesky factorization and its application to time series prediction
Authors: Zhang Xian  , Wang Hong-Li  ,   Department of Automatic Control Engineering, The Second Artillery Engineering College, Xi'an 710025, China
Published: December 2020

In order to solve the hidden-layer neuron determination problem of regularized extreme learning machine (RELM) applied to chaotic time series prediction, a new algorithm based on Cholesky factorization is proposed. First, an RELM-based prediction model with one hidden-layer neuron is constructed and then a new hidden-layer neuron is added to the prediction model in each training step until the generalization performance of the prediction model reaches its peak value. Thus, the optimal network structure of the prediction model is determined. In the training procedure, Cholesky factorization is used to calculate the output weights of RELM. Experiments on chaotic time series prediction indicate that the algorithm can be effectively used to determine the optimal network strueture of RELM, and the prediction model trained by the algorithm has excellent performance in prediction accuracy and computational cost.
Study on bursting of pancreatic cells in codimension-2 bifurcation regions
Authors: Yang Zhuo-Qin  , Guan Ting-Ting  , Gan Chun-Biao  , Zhang Jiao-Ying  ,   Shcool of Mathematics and System Sciences and LMIB, Beihang University, Beijing 100083, China;,   Department of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Electrical activities of insulin secretion in pancreatic islets are characterized by bursts of action potentials. With a simple but representative Vries-Sherman model, we determine the regions of different types of bursting in two-parameter plane through the two-parameter bifurcation analysis of the fast subsystem. Moreover, fast/slow analysis is used to reveal topological types of bursting patterns for different values of the parameter Vm and transition mechanisms between them.
Study on fast synchronization of chaos
Authors: Zheng Hao-Zhou  , Hu Jin-Feng  , Liu Li-Dong  , He Zi-Shu  ,   School of Electronic Engineering, University of Electronic Science and Technology of China,Chengdu 611731, China
Published: December 2020

In radar, communication and other engineering applications, fast synchronization is needed because of the limited time of transmitting signal. However, the convergence rate of conventional synchronization is slow. To resolve the problem, a fast synchronization algorithm is proposed. According to Taylor expansion, nonlinear controller is designed to make the control matrix of error equation satisfy critical conditions for synchronization and further to optimize the control matrix, so fast synchronization can be achieved with only one step operation. In addition, given the practical engineering launches only one state variable, in this paper are take the typical continuous Duffing system and discrete Logistic system as examples and design the fast synchronization driven by only one variable. Finally, simulation results show that compared with common single coupling and OPCL synchronization, the proposed algorithm has fast convergence rate, strong anti-noise cap ability, and strong engineering practice significance.
Reduction of 1/f noise in semiconductor devices based on wavelet transform and Wiener filter
Authors: Dai Yu  , Zhang Jian-Xun  ,   Institute of Robotics and Automatic Information System, Nankai University, Tianjin 300071,China
Published: December 2020

In order to reduce universal 1/f noise in semiconductor devices, a method with combining lifting wavelet transform and Wiener filter is presented. Firstly, the iteratively reweighted least square method is introduced to fit the power spectrum of 1/f noise and estimate its parameter, and then an appropriate wavelet can be selected. Secondly, the signal with 1/f noise is decomposed by lifting wavelet transform. Considering the fact that the wavelet transform whitens 1/f noise, Wiener filter is used to treat the wavelet coefficient of each layer. Allpass filter is optimized to adjust the phase frequency response of Wiener filter, and the phase of filtered wavelet coefficient is not changed. Finally, the useful signal embedded in 1/f noise is retrieved by the inverse lifting wavelet transform. Experimental study demonstrates the proposed procedure and verifies its effectiveness, and the experimental data are acquired from a force sensor developed for minimally invasive surgery robot. The results show that the method works very well in minimizing 1/f noise, and so the resolution of the sensor increases 25%.
Influence and simulated correction of tip/tilt phase error on fiber laser coherent beam combination
Authors: Geng Chao  , Li Xin-Yang  , Zhang Xiao-Jun  , Rao Chang-Hui  ,   The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Near-field models of coherent beam combination (CBC) with different beam channels and fill factors are employed, and the influences of tip/tilt phase errors on CBC are studied. The key device for tilt-error correction, named adaptive fiber optics collimator(AFOC), is introduced. A MOPA-configuration fiber laser CBC system compensating both piston and tip/tilt phase errors is designed. Then, the dynamic courses of tilt-error correction using stochastic parallel gradient descent (SPGD) algorithm in a seven-channel system are simulated, and the effects of CBC at different tilt-error amplitudes and frequencies are investigated. Experimental results show that the tilt-error should be corrected to improve CBC effects, and algorithm's control ability drops off when tilt-error amplitude and frequency increase. The results in this paper present a reference for multi-channel high power fiber laser CBC systems in real atmospheric environments.
Entropy exchange and entanglement of a moving atom with k-photon Jaynes-Cummings model
Authors: Wang Ji-Cheng  , Liao Qing-Hong  , Wang Yue-Yuan  , Wang Yue-Ke  , Liu Shu-Tian  ,   Department of Physics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

The entropy correlation and the entanglement of a moving atom interacting with k-photon Jaynes-Cummings model are investigated. Entropy exchange between atomic and field subsystems, which is a form of anti-correlated behavior, is explored. Analytical results show that atomic motion, transition number k of field and field-mode structure can influence the entropy exchange between atom and light field. Moreover, the relationship between entropy correlations and entanglement is also discussed.
Multi-wavelength ultraviolet terawatt-order CPA system
Authors: Ling Wei-Jun  , Zhang Shao-Gang  , Li Ke  , Zhang Ming-Xia  , Wang Yi-Shan  , Zhao Wei  , Wang Zhao-Hua  , Wei Zhi-Yi  ,   Depart of Physics, Tianshui Normal College, Tianshui 741000,China;,   State Key Laboratory of Transient Optics and Photonics, Xi'an 710119,China;,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We set up a multi-wavelength ultraviolet terawatt-order chirped pulse amplification(CPA) system according to the CPA technology and the frequency conversion technology. The system offers 1Hz, 5Hz and 10Hz high energy ultraviolet pulses by precise time synchronization among 5 repeat frequencies. The RMS of output energy fluctuation rate of CPA is less than 2% with using a pre-amplified system of energy fluctuation rate less than 0.3% RMS and a time synchronizer with time jitter less than 3 ns. The multi-wavelength high energy ultraviolet pulses with 64 mJ/400 nm,16 mJ/267 nm and 5 mJ/205 nm are obtained, and their corresponding peak powers reach the terawatt level.
Theoretical investigation of elastic, electronic, and optical properties of zinc-blende structure GaN under high pressure
Authors: Jiao Zhao-Yong  , Yang Ji-Fei  , Zhang Xian-Zhou  , Ma Shu-Hong  , Guo Yong-Liang  ,   College of Physics and information Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The elastic, electronic, and optical properties of zinc-blende structure GaN under high pressure are investigated by using a first-principles ultra-soft pseudo-potential approach of the plane wave based on the density functional theory. The calculated results show the dependences of the elastic constant, the bulk modulus, the young modulus, and the energy gap on the applied pressure, and the results are in good agreement with the experimental and theoretical values. Furthermore, the dielectric function, optical reflectivity, refractive index, absorption coefficient and energy-loss function of GaN are analyzed in terms of the accurately calculated band structure and density of state. The conclusions drawn from the calculations offer theoretical basis for the design and application of GaN.
Vibrational effect on external field control of charge transmission in molecular nano-junction
Authors: Li Jin-Hua  , Wang Lu-Xia  ,   Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing,Beijing 100083, China
Published: December 2020

With the weak-coupling approach in molecular vibrational normal coordinate, the charge transmission under external optical field through molecular nano-junction is studied. From the charging energy point of view, the sequential charge transmission is analyzed and the current-voltage characteristics under external optical field are studied. It is found that the vibrational effect of molecule is the key factor of the removal of Franck-Condon blockage under external optical field. Furthermore, the effects of charging energy and intra-molecular vibrational energy redistribution (IVR) in charge transmission under external optical field are studied in detail.
Influence of source gas flow ratio on the proteins adsorbability of F-DLC film
Authors: Dai Yong-Feng  , Jiang Mei-Fu  , Yang Yi-Shang  , Zhou Yang  ,   Department of Physics, Soochow University, Suzhou 215006, China
Published: December 2020

The fluorinated diamond-like carbon (F-DLC) films are prepared by reactive magnetron sputtering under different gas flow radios with trifluoromethane (CHF3 ) and argon (Ar) used as source gases and pure graphite as a target on the surface of 316L stainless steel (SU316L). Factors which influence the protein adsorbability are discussed by double-stilled water, BCA and FTIR spectra. The results show that the surface of SU316L coated with F-DLC film could obviously reduce the number of adherent platelets and dramatically relieves the deformation of platelets, leading to a ratio of higher albumin to fibrinogen adsorption higher than that with using the SU316L substrates, which indicates that the SU316L coated with F-DLC film can improve the blood compatibility. The film has the highest ratio of albumin to fibrinogen adsorption and the best hemocompatibility when the ratio of gas flow is 2 ∶1. Furthermore, the measurements of the contact angle, the surface energy of films and FTIR spectra show that the ratio of albumin to fibrinogen adsorption and the hemocompatibility of F-DLC coated SU316L depend on the surface energy (hydrophobic nature) of films and the quantity of -CFx bonds (the ratio of F/C) contained in film. The modulating of blood compatibility of the films can be realized by the control of the ratio of source gas flow.
Sprott system locked on chaos with constant Lyapunov exponent spectrum and its anti-synchronization
Authors: Li Chun-Biao  , Xu Ke-Sheng  , Hu Wen  ,   School of Information Science and Engineering, Southeast University, Nanjing 210096, China;,   School of Engineering Technology, Jiangsu Institute of Economic and Trade Technology, Nanjing 210007, China;,   School of Physical Science and Technology, Guangxi Normal University, Guilin 541004, China;,   College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

Chaos realization in Sprott system depends on the nonlinear function of single absolute term. Under this condition, the chaos in the system is locked with constant Lyapunov exponent spectrum by introducing new control parameters. So the amplitude and the phase of the signal output in the system can be controlled and modulated. Anti-synchronization system is constructed, and anti-synchronization is obtained by introducing only one control term in the response system based on Lyapunov potential function method.
The study of nonresonant Raman excited virtual state of carbazole molecule
Authors: Bo Li-Juan  , Chen Yan-Rong  , Wang Pei-Jie  , Fang Yan  ,   Key Laboratory for Nano-photonics and Nano-structure of Beijing, Department of Physics, Capital Normal University, Beijing 100048, China
Published: December 2020

According to the relationship between Raman intensity and the bond polarizability, we investigate the temporal bond polarizabilities of carbazole molecule from the Raman intensities. We obtain the bond polarizability of the final state and compare it with the electronic density of the ground state by the density functional theory method, then we discuss and analyze the characteristics of carbazole temporal bond polarizabilities. The results show that at the initial stage of exitation, the excited electrons tend to flow toward the bond that we called connecting bond, which connects the two six-member ring, but not toward the molecular periphery. The bond electronic density of the molecule ground state can be mapped out by the temporal bond polarizabilities at the final stage of relaxation, therefore we conclude that the excited electrons flow back to the skeleton bond. Furthermore, we find the relaxation characteristic time of connecting the bonds is longer than that of connecting the other bonds, this further confirms our observations mentioned above. These conclusions will improve our understanding of Raman excited virtual states of the molecule with the bridge bonds.
Density functional theory study on the structure and properties of (HMgN3)n(n=15) clusters
Authors: Zhang Zhi-Long  , Chen Yu-Hong  , Ren Bao-Xing  , Zhang Cai-Rong  , Du Rui  , Wang Wei-Chao  ,   Key Laboratory of Advanced Non-ferrous Metal Materials of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, China;,   School of Science, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

We optimize the possible geometrical cluster structures and predicte relative stability of (HMgN3)n(n=15) by using the hybrid density functional theory (B3LYP) with 6-311G* basis sets. And the most stable isomers of (HMgN3)n(n=15) clusters, the bond properties, charge distributions, vibrational properties, and stability are analyzed theoretically. The calculated results show that the most stable HMgN3 has a linear structure, the (HMgN)n(n=2,5) clusters have the most stable structures in which an N atom in a sub-system and metal atom in another sub-system constitute an MgNMg structure. And the most stable structures of (HMgN3)n(n=3,4) clusters are the chain structures in which the nitrogen cardinal extremity position N atom and the Mg atom form a ring structure; the metal Mg atoms in the most stable structure show charge positivity, and H atom show charge negativity. The middle N atoms of azido show charge positivity, the N atoms on both sides of azido show charge negativity; what's more, the N atoms influenced by Mg atoms directly show a more charge negativity. MgN bond and MgH bond are the typical ionic bond; the bond between N atoms in azido is the covalent bond. The infrared spectra of the most optimized (HMgN3)n(n=15) clusters have three vibrational sections, the strongest vibrational peak lies in 22582347 cm-1, and the vibrational mode is anti-symmetric stretching vibration of NN bonds in azido. Analysis of stability shows that (HMgN3)3 clusters are more stable than other clusters.
Impact energy model based research of nonlinear rub-impact assessment
Authors: Cong Fei-Yun  , Chen Jin  , Dong Guang-Ming  ,   State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

An impact energy model (IEM) is proposed for the research of nonlinear rub-impact assessment in this paper. According to the characteristic of the model, IEM index is given to evaluate the severity or probability of rub-impact fault. We investigate the trend of variation of IEM index response to the rotation speed ratio under the condition of different values of damping ratio , and then acquire a joint distribution of IEM response with the parameters of and . Combining the IEM model, a concept of sensitive area is proposed. The sensitive area provides an excellent reference for operating rotor system and a guidance and assessment for designing rotor system.
Effect of disturbance on spin polarized transport through an organic ferromagnetic device
Authors: Wang Hui  , Hu Gui-Chao  , Ren Jun-Feng  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

Based on the tight-binding model and the Greens function method, the effects of atomic disorder of lattice configuration and the orientation disorder of side radical spins on the spin polarized transport through a metal/organic-ferromagnet/metal structure are investigated. The results show that the atomic disorder reduces the threshold voltage of the device and suppresses the conducting current. The staircase structure of the current-voltage curve for a molecular device is eliminated when the disorder is enhanced. The current keeps a high spin polarization if the atomic disorder is not strong. The orientation disorder of side radical spins reduces the spin splitting of molecular energy levels, which increases the threshold voltage of the device. The current and its spin polarization are reduced apparently at a low bias when the strength of disorder is enhanced. We further simulate the effect of temperature on the spin polarized transport through the device by taking into account two kinds of disorders.
The structural stability and electronic properties of monolayer BC2N
Authors: Gao Tan-Hua  , Wu Shun-Qing  , Hu Chun-Hua  , Zhu Zi-Zhong  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China;,   Department of Physics, Xiamen University, Xiamen 361005, China;,   Key Laboratory of Theoretical and Computational Chemistry of Fujian Province, Xiamen University, Xiamen 361005, China
Published: December 2020

The structural stability and the electronic properties of two-dimensional monolayer BC2N are studied by employing the first principles method based on the density functional theory. 16 polymorphic structures of monolayer BC2N are calculated. Analysis of the 16 band structures suggests that the structure with the highest symmetry is of a semimetal which is the same as graphene. All the other structures are of semiconductors with different band gaps, of which the most stable structure is of semiconductor with a direct gap of 1.63 eV. Based on the deformation charge density and the Bader analysis, the bonds CC, CN, CB, and BN in the most stable monolayer BC2N are mainly covalent, however, they present also significant ionic behaviors. Exerting a stress on the monolayer BC2N sheet changes the band gap, showing that the band gap increases during the compression while decreases during the stretch, and the system keeps a direct semiconductor.
Numerical investigation on the gas-liquid severe slugging in a pipeline-riser system
Authors: Gao Song  , Li Wei  , You Yun-Xiang  , Hu Tian-Qun  ,   School of Naval Architecture, Ocean and Civil Engineering, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Based on the consistence principle for the severe slugging formation condition, a computational fluid dynamics (CFD) method is proposed for numerically simulating the gas-liquid severe slugging in a pipeline-riser system by converting the three-dimensional pipeline-riser system into a two-dimensional equivalent one. Numerical simulation is conducted for the gas-liquid flow patterns of the severe slugging in a declination pipeline-riser system according to the experimental cases presented in the reference, and variations of characteristics of the flow parameters with gas-liquid superficial velocity due to such a severe slugging are obtained, including period, pressure fluctuation and blowout time, the numerical results are in good agreement with the experimental results. Moreover, the theoretical methods are obtained of determining the gas superficial velocity at the riser inlet, the gas volume fraction in the riser and the average velocity at the riser outlet during the severe slugging blowout stage, and the variations of characteristics of these flow parameters with time are presented. Besides, a theoretical predicting method of determining the flow patterns in the riser during the severe slugging blowout stage is further proposed, and the theoretical results are consistent with the CFD numerical results. The CFD method could save much time and computing resource, and the theoretical methods could be used to predict the damage of severe slugging quickly.
The influence of anharmonicity on the surface effect in nanodiamond
Authors: Cheng Zheng-Fu  , Long Xiao-Xia  , Zheng Rui-Lun  ,   Department of Physics of Chongqing University of Arts and Sciences, Chongqing 402160, China
Published: December 2020

The influences of atomic number and shape on Debye temperature, surface energy, surface pressure and lattice are studied by means of Me-lennard jones potential, then the influences of anharmonicity and shape on surface character are discussed. The result shows that (1) the Debye temperature and surface energy increase as atomic number increases, and that of rod nanodiamond is lower than that of cubic one. (2) The surface pressure and the variation of lattice parameter at low temperature decrease with the atom number decreasing, and the rod sample change is more apparent. The harmonic atomic surface pressure is smaller than the anharmonic one. (3) The above case is obvious when less atom number is small.
Study of gate depletion effect in strained Si NMOSFET with polycrystalline silicon germanium gate
Authors: Hu Hui-Yong  , Lei Shuai  , Zhang He-Ming  , Song Jian-Jun  , Xuan Rong-Xi  , Shu Bin  , Wang Bin  ,   Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Based on the analysis of Poly-Si1-xGex gate work function and by solving Poisson equation, the models of vertical electric field and potential distribution in strained Si NMOSFET with Poly-Si1-xGex gate are obtained; threshold voltage model and the gate depletion thickness and it's normalization model are established in strained Si NMOSFET based on the above results, with the gate depletion effect of Poly-Si1-xGex taken into account. Then the influences of device geometrical and physical parameters of device especially the Ge fraction on Poly-Si1-xGex gate depletion thickness are investigated. Furthermore, the effect of gate depletion thickness on threshold voltage is analyzed. It shows that the poly depletion thickness decreases with the increases of Ge fraction and gate doping concentration, while it increases with the increase of substrate doping concentration. Furthermore, the threshold voltage increases with the increase of gate depletion thickness. The results can provide theoretical references to the design of strained Si devices.
The transmission properties in one-dimensional piezoelectric Fibonacci-class quasi-periodical phononic crystals
Authors: Yang Li-Feng  , Wang Ya-Fei  , Zhou Ying  ,   College of Opto-Electrical Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The transmission properties of phononic crystals in one-dimensional piezoelectric Fibonacci quasi-periodical superlattices are studied using the transfer matrix method. The transmission coefficients in piezoelectric Fibonacci quasi-periodical superlattices are compared with those of the phononic crystals with periodical structure and with non-piezoelectric Fibonacci quasi-periodical structure. The results show that the band gap can also be found in the phononic crystals with both piezoelectric and non-piezoelectric Fibonacci quasi-periodical superlattices, and the frequency range of the gap in piezoelectric Fibonacci quasi-periodical superlattices is larger than those of periodical structure and non-piezoelectric Fibonacci quasi-periodical structure. Furthermore, the transmission coefficients are studied as a function of the properties of the material and incidence angle of the wave. The results show that the transmission coefficients in piezoelectric Fibonacci quasi-periodical superlattices are correlated with incidence angle of the wave.
Research on characteristics degradation of n-metal-oxide-semiconductor field-effect transistor induced by hot carrier effect due to high power microwave
Authors: You Hai-Long  , Lan Jian-Chun  , Fan Ju-Ping  , Jia Xin-Zhang  , Zha Wei  ,   Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

High power microwave (HPM) can disrupt the normal work of electronic systems through the effect of HPM on semiconductor devices. In this paper, the physical process and the physical model of the characteristic degradation of n-metal-oxide-semiconductor field-effect transistor (nMOSFET) induced by HPM are introduced. In device simulation results, the output characteristic curve of nMOSFET shows that HPM can induce the degradation of the characteristics of device, including the forward drift of threshold voltage, and the reduction of saturation current and transconductance. Based on the process and the model introduced in this paper, the voltage pulse generated by HPM makes nMOSFET be in depletion status and hot carrier increase; then the effect of hot carrier results in the characteristic degradation of device. The experimental result of MOS injected HPM shows the changes of output characteristics and model parameters are consistent with the device simulation results, proving that the physical process and the physical model introduced in the paper are correct.
Experimental investigation on open-circuit voltage of InGaP/InGaAs/Ge triple-junction solar cell influenced by the vibration direction of the electric vector of linearly polarized light
Authors: Xiao Wen-Bo  , He Xing-Dao  , Gao Yi-Qing  ,   Key Laboratory of Nondestructive Testing of Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China
Published: December 2020

In this paper, it is investigated experimentally that the open-circuit voltage of InGaP/InGaAs/Ge triple-junction solar cell is influenced by the vibration direction of the electric vector of linearly polarized light. The results show that those voltages are subjected to periodic changes with the vibration direction of the electric vector, and the magnitude of change is about 1%4%. It is due to the effect of anisotropy of band structure in the three-junction solar cell,which is confirmed by theoretical analysis. In addition, through combining the experimental study with theoretical analysis, the relationship between open-circuit voltage and illumination, is studied, showing that they are related to each other logarithmically, which is different from characteristics of a single-junction solar cell. From fitting results, it is indicated that the triple-junction solar cells may be regarded as three diodes connected in series, of which the ideality factor is close to 6. This is due to many defects in three-junction solar cells.
Study on the congestion phenomena in complex network based on gravity constraint
Authors: Liu Gang  , Li Yong-Shu  ,   Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

How to guarantee the transport efficiency of the network and how to improve the network capacity are the main subject of the study presently. We investigate the gravity of the nodes to the transfer of data packets, and propose a routing method based on gravity constraint. In order to characterize the efficiency of the method, we introduce an order parameter H to measure the throughput of the network by a critical value of phase transition from free state to jammed state, and use the maximum travel time 〈Tmax〉 and the average travel time 〈Tavg〉 to test the transmission efficiency of the network. We simulate the network capacity under three different gravity constraints. Simulation results show that when only considering the path with shortest length, the network capacity is very small and the distribution of flow is extremely uneven; when only considering minimum waiting time, the excessive circuitous transfer of data packets occurs and most of the nodes will be in congestion state; when considering the gravity of path length and waiting time simultaneously and choosing a node with reasonable gravity, the network capacity will be improved greatly and the congestion level will be relieved to some extent.
The first-order approximate Lie symmetries and approximate conserved quantities of the weak nonlinear coupled two-dimensional anisotropic harmonic oscillator
Authors: Lou Zhi-Mei  , Mei Feng-Xiang  , Chen Zi-Dong  ,   Department of Physics, Shaoxing University, Shaoxing 312000, China;,   Department of Mechanics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The first-order approximate Lie symmetries and approximate conserved quantities of the weak nonlinear coupled two-dimensional anisotropic harmonic oscillator are studied. When the 1/2 is equal to 2/1, the system possesses six first-order approximate Lie symmetries and approximate conserved quantities, one of them is an exact conserved quantity, four of them are trivial conserved quantities, only one of them is a stable conserved quantity.
Monte Carlo simulations for non-line-of-sight ultraviolet scattering coverage area
Authors: Zhao Tai-Fei  , Ke Xi-Zheng  ,   Faculty of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China
Published: December 2020

In this paper, the Monte Carlo method is employed to simulate the ultraviolet light scattering transmission. The three modes of ultraviolet (UV) no-line-of-sight (NLOS) communication are analyzed. The UV NLOS transmission model based on the Monte Carlo method is proposed. The path losses of single and multiple scatterings and the coverage area of three UV NLOS modes are simulated by using the Monte Carlo method. Finally, we obtain the conclusion that multiple scattering and single scattering basically have the same path loss. The coverage of NLOS (a) is smallest, but omni-direction is good. The coverage of NLOS (b) is larger, but it is directional. The coverage of NLOS (c) is largest, but it is strongly directional.
The three-photon resonant nondegenerate six-wave mixing via quantum interference in the middle level
Authors: Sun Jiang  , Sun Juan  , Wang Ying  , Su Hong-Xin  , Cao Jin-Feng  ,   College of Physical Science and Technology, Hebei University, Baoding 071002, China;,   College of Mathematics and Computer Science, Hebei University, Baoding, 071002, China
Published: December 2020

We study the quantum interference in three-photon resonant nondegenerate six-wave mixing (NSWM) of a five-level system in which the middle level of six-wave mixing and other levels are coupled by a strong laser field. The coupling field-dependence of the NSWM signal intensity, and the spectrum of the NSWM with a coupling field, are discussed. We find that in the presence of a strong coupling field, the three-photon resonant NSWM spectrum exhibits Autler-Townes splitting, which reflects the levels of the dressed states. It also leads to either suppression or enhancement of the NSWM signal. Due to the enhancement of NSWM signal caused by quantum interference, the dressed state created by a coupling field can replace the atom intrinsic level and serve as the middle level of three-photon resonance. Thus the middle level of three-photon resonance can be controlled by a coupling field.