bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature effects on structural order of all-trans-β-carotene
Authors: Qu Guan-Nan  , Li Shuo  , Sun Mei-Jiao  , Xu Sheng-Nan  , Liu Yu  , Sun Cheng-Lin  , Men Zhi-Wei  , Li Zuo-Wei  ,   State Key Laboratory of Superhard Materials, College of Physics, Changchun 130012, China;,   Second Hospital of Jilin University, Changchun 130041, China
Published: December 2020

The effects of temperature on the visible absorption and Raman spectra of all-trans-β-carotene dissolved in dimethyl sulfoxide at temperatures ranging from 81 ℃ to 18 ℃ were determined. The bands of the visible absorption and Raman spectra of all-trans-β-carotene showed red blue shifts. The bandwidth of the Raman spectra becomes narrow. Raman scattering cross-section increases as the temperature decreases. The red shift of the absorption spectrum is attributed to the thermal conformational change-induced decrease in the effective conjugation length in all-trans-β-carotene chains. The molecular structural order increases and the π-electron delocalization range is extended as the temperature decreases. The red shift in all-trans-β-carotene can be also attributed to the decrease in the liquid density, and the concomitant decrease in the refractive index is shown by the Lorentz-Lorenz relation. The apparent behavior of the temperature-induced band broadening of CC bonds can be associated with the decrease of difference in C-C and C=C bond lengths, and the shorter vibrational relaxation time. The shoulder observed below 1520 cm-1 shows a red shift. The enhancement of coherent weakly-damped CC stretching vibrations may increase the Raman scattering cross-section.
Physical design of the "Ying-Guang 1" device
Authors: Sun Qi-Zhi  , Fang Dong-Fan  , Liu Wei  , Qing Wei-Dong  , Jia Yue-Song  , Zhao Xiao-Ming  , Han Wen-Hui  ,   Institute of Fluid Physics, CAEP, Mianyang 621900, China
Published: December 2020

"Ying-Guang 1" is a multi-bank pulsed power device for investigating the formation, confinement and instability of the high temperature and high density field-reversed configuration (FRC) plasma injector for the magnetized target fusion (MTF). This paper described the physical design of the "Ying-Guang 1" device which will be constructed in 2013 at the Institute of Fluid Physics, CAEP. Theoretical results show that the peak reversed current and magnetic field of this device are 1.5 MA and 4 T respectively with the rise time of 3 μ s. Based on the semi-empirical formula developed by Tuszewski the magnetized plasma of equilibrium density 6.6×1016 cm-3 and temperature (Ti+Te) ～ 300 eV could be achieved on the "Ying-Guang 1" device when the initially filled D2 gas pressure is about 50 mTorr, and the length of the FRC separatrix is 17 cm with a radius of 2 cm. The average ratio of the thermal pressure to magnetic pressure β is about 0.95, and the magnetic field embedded in plasma is 0.5 T. From the adiabatic compression scaling laws and the corresponding ignition conditions, the formated FRC plasma target of the "Ying-Guang 1" device approaches the necessity of the MTF if the radius compression ratio of the solid metal liner were set to 10.
Effects of the radial temperature gradient and axial conduction of drilling fluid on the wellbore temperature distribution
Authors: Yang Mou  , Meng Ying-Feng  , Li Gao  , Deng Jian-Min  , Zhang Lin  , Tang Si-Hong  ,   State Key Laboratory of Oil and Gas Geology and Exploration.Southwest Petroleum University,Chengdu 610500, China;,   Engineering Technology Research Institute of Gas PetroChina.Southwest Oil &Gasfield Company, Guanghan 618300, China
Published: December 2020

Therefore, in this study, based on energy balance principle between wellbore and formation, a temperature model of drilling fluid layers was established under different grid units of wellbore condition. Meanwhile, the axial thermal conductivity temperature model of drilling fluid was established by introducing axial conduction items of drilling fluid, followed by using discrete and solving of implicit finite difference method to these mathematical models. The calculation results indicated that the error temperature of the radial and axial of drilling fluid wellbore temperature which was caused of radial temperature gradient were 0.15 and 0.2 ℃ respectively, whereas axis thermal conductivity of drilling fluid has little effect on wellbore temperature distribution. Therefore, the above results confirmed that it can ignore both of them to influence wellbore temperature distribution by established the wellbore-formation coupled transient heat transfer model. Moreover, it is the first proved the correctness of model assumptions from previous scholars based on the mathematical modeling methods, and then further provides the reliable theoretical basis for down-hole temperature distribution of oil and gas well and geothermal well.
Infrared characteristic radiation under first order phase transitions–melt crystallization and vapor condensation or deposition
Authors: Tatartchenko Vitali  , Liu Yi-Fan  , Wu Yong  , Zhou Jian-Jie  , Sun Dai-Wei  , Yuan Jun  , Zhu Zhi-Yong  , Smirnov Pavel  , Rusanov Artem  , Niu Shen-Jun  , Li Dong-Zhen  , Zong Zhi-Yuan  , Chen Xiao-Fei  ,   Shanghai CEC Zhenhua Crystal Technology Co., Ltd., Shanghai 201210, China
Published: December 2020

We have studied the specimens made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by a gene and encoded in the genetic code. This can happen either before the protein is used in the cell, or as part of control mechanism. This paper considers a new physical phenomenon - infrared characteristic radiation (IRCR) at first order phase transitions (melt crystallization, and vapor condensation and/or deposition). Experimental results are analyzed in terms of their correspondence to the theoretical model. This model is based on the assertion that the particle's (atom's, molecule's, or cluster's) transition from a higher energetic level in a metastable or unstable phase (vapor or liquid) to a lower level in a stable phase (liquid or crystal) can emit one or more photons. The energy of these photons depends on the latent energy of the phase transition and the character of bonds formed by the particles in the new phase. For all investigated substances, this energy falls in the infrared range. This is a reason why the radiation is named as IRCR-infrared characteristic radiation. Many sources of the infrared radiation recorded in the atmosphere seem to be a result of crystallization, condensation and/or sublimation of water during fog and cloud formation. Thus, the effect under investigation must play a very important role in atmospheric phenomena: it is one of the sources of Earth's cooling; formation of hailstorm clouds is accompanied by intensive characteristic infrared radiation that could be used for process characterization and meteorological warnings. IRCR seems to explain red color of Jupiter. It can be used for atmospheric energy accumulation, and, thus, together with wind, falling water, solar and geothermal energies, IRCR makes available the fifth source of ecologically pure energy.
Weyl ordering expansion for optical field phase operator and inverse operators
Authors: Li Xue-Chao  , Yang Yang  , Fan Hong-Yi  ,   School of Science, Anhui University of Science and Technology, Huainan 232001, China;,   Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China;,   Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Using the technique of integration within an ordered product of operators, we derive Weyl ordered expansion for optical field phase operator and inverse of creation and annhilation operators. The results are used to obtain the classical correspondence, new generation function formula of some special functions and new integration formulas. In particular, for the first time we derive complex Gaussian integral formula when the integrand has negative power function.
Non-Markovian diffusion of the stochastic system with a biexponentical dissipative memory kernel
Authors: Xie Wen-Xian  , Xu Peng-Fei  , Cai Li  , Li Dong-Ping  ,   Department of Applied Mathematics, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

In this paper, second-moments of the responses are analytically solved by the Laplace transform in a coupling two-degree-of-freedom system with a biexponentical dissipative memory kernel function driven by a thermal broadband noise. The mean square displacement x2(t)> is different from anomalous diffusion (i.e. x2(t)> ∝ tα (0αα≠1)), which is produced by the single-degree-of-freedom generalized Langevin equation. The oscillation-diffusion of x2(t)> with the change of time and noise parameters is observed generally. According to our analysis, a particle confined by the harmonic potential can escape with the help of the coupling-damping factor B. The diffusion of x2(t)> aggravates with B increasing. However, x2(t)> tends to the stationary state with the increase of the friction coefficient Further, if the two thermal noises are in cross-correlation, smaller cross-correlation time has a deeper influence on second-moments. Meanwhile, the diffusion aggravates and the cross-correlation between two displacements strengthens markedly with cross-correlation strength increasing. It is consistent with physical intuition.
Theoretical study on the electronic structures and photophysical properties of carbon nanorings and their analogues
Authors: Xu Ying-Ying  , Kan Yu-He  , Wu Jie  , Tao Wei  , Su Zhong-Min  ,   Jiangsu Province Key Laboratory for Chemistry of Low-Dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin NormalUniversity, Huaian 223300, China;,   Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, China
Published: December 2020

Density functional theory (DFT) is used in a series of hexacene nanoring ([6]CA), its boron nitride analogue ([6]CA-BN) and lithium ion doping derivatives to obtain an insight into electronic structure, aromaticity property, energy gap, ionization potential, electron affinity and reorganization energy. DFT calculations of these nanorings indicate that the energy gaps of the carbon nanorings are smaller than those of the boron nitride nanorings. The lithium ion doping will remarkably reduce the HOMO and LUMO energy. The aromaticities of the rings are investigated though nucleus-independent chemical shift (NICS) values. The NICS scan suggests that the aromaticities of carbon nanoring systems are more than those of boron nitride analogues, the aromaticities of boron nitride compounds are very weak due to orbital localization. We also calculate the reorganization energy to investigate the charge transport properties. The results show that the carbon nanoring and their analogues could serve as bipolar carrier transport materials in photoelectric functional materials, and the lithium ion doping significantly improves the charge transport properties. The [6]CA-BN nanorings serve as better electron-transport materials. Furthermore, the lithium ion doping significantly affects the charge transfer property of [6]CA-BN nanoring, making it used as bipolar carrier transport materials. The time dependant DFT investigations show that the boron nitride substitution leads to an important change in absorption spectrum with blue-shift. And lithium ion doping has no obvious influence on absorption spectrum.
Study of Si K-shell X-ray emission induced by H+ and Ar11+ ions
Authors: Zhou Xian-Ming  , Zhao Yong-Tao  , Cheng Rui  , Wang Xing  , Lei Yu  , Sun Yuan-Bo  , Wang Yu-Yu  , Xu Ge  , Ren Jie-Ru  , Zhang Xiao-An  , Liang Chang-Hui  , Li Yao-Zong  , Mei Ce-Xiang  , Xiao Guo-Qing  ,   Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;,   School of Physics and Electronic Engineering, Normal College of Xianyang, Xianyang 712000, China
Published: December 2020

The L-shell X-rays of Si, induced by 50-250 keV proton and 1.0-3.0 MeV Ar11+ ions impacting are measured. It is found that the X-ray induced by Ar11+ is about 36 eV higher than that induced by proton. That indicates that 3, 4 L-shell electrons of Si atom are multiply-ionized by Ar11+ ion impact. The X-ray production cross section is extracted from the yield data and compared with the results from the BEA, PWBA and ECPSSR models. With the same unit incident energy, the cross section induced by Ar11+ is about 3 orders of magnitude larger than that produced by proton. For proton impact, the ECPSSR model gives an accurate prediction to the cross section data. However, the BEA model, considering the change of fluorescence yield due to the multiple-ionization, presents the results that are in better agreement with the experimental results for Ar11+ ions.
Analysis on the cutoff frequency of high order harmonic generation in the crystal
Authors: Chen Gao  , Yang Yu-Jun  , Guo Fu-Ming  ,   College of Science, Changchun University of Science and Technology, Changchun 130022, China;,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
Published: December 2020

By numerically solving the time-dependent Schrödinger equation with the interaction between one-dimensional multi-well potential and the mid-infrared few-cycle femtosecond pulses, we theoretically investigate the high-order harmonic generation spectra in a crystal, further find the cutoff frequency formula under the new condition. Our results clearly show that the high order harmonic generation in the crystal is fundamentally different from that in the atomic case, owing to the high density and periodic structure. The harmonics spectrum shows a cutoff position that scales linearly with the peak amplitude of electric field of the drive laser and the lattice parameters. Based on the important role of the three-step model obtained by quasi-calssical mechanics method in gas harmonic generation, in this paper, this method is also well used to verify the cutoff position law in crystal harmonic generation.
Potential energy curves and vibrational levels of ground and excited states of LiAl
Authors: Chen Heng-Jie  ,   School of Mathematics and Physics, Chongqing University of Science and Technology, Chongqing 401331, China
Published: December 2020

The potential energy curves (PECs) for ground electronic state (X1∑+) and seven excited electronic states (a3∏, A1∏, b3∑+, c3∑+, B1∏, C1∑+, d3∏) of LiAl are obtained using the multi-configuration reference single and double excited configuration interaction method. Equilibrium bond length Re, adiabatic excited energy Te and vertical excited energy Tv are obtained. It is shown that c3∑+ is an unstable repulsive state, A1∏ is a weak bound state and the others are all bound states. Predissociation can be found between b3∑+ and c3∑+ states. Eight electronic states are dissociated along two channels, Li(2S)+Al(2P0) and Li(2P0)+Al(2P0). And then PECs are fitted to analytical Murrell-Sorbie (MS) potential function to deduce the spectroscopic parameters:the Re is 0.2863 nm, ωe is 316 cm-1 and De is 1.03 eV for the ground state; the values of Tv of excited states are 0.27, 0.83, 1.18, 1.14, 1.62, 1.81 and 2.00 eV; the values of De are 1.03, 0.82 and 0.26, repulsive state, 1.54, 1.10, 0.93 eV, and the values of corresponding frequency ωe are 339, 237, 394, repulsive state, 429, 192, 178 cm-1. By solving the radial Schrödinger equation of nuclear motion, the vibration levels, inertial rotation constants (J=0) are reported for the first time.
Si cluster based spintronics:a density functional theory study
Authors: Huang Yao-Qing  , Hao Cheng-Hong  , Zheng Ji-Ming  , Ren Zhao-Yu  ,   School of Science, Shanghai Institute of Technology, Shanghai 201418, China;,   Institute of Photonics and Photo-Technology, Northwest University, Xi'an 710069, China
Published: December 2020

A kind of spintronics is designed by doping the transition metal into Si clusters. Their spin-polarized electron transport properties are investigated by using the first principle analysis. Calculation shows that Fe, Cr and Mn atom doped clusters give the largest spin-polarized transmission coefficients in all the clusters. From Sc to Ni doped clusters, spin filter efficiencies of the systems increase gradually, and the maximal spin filter coefficiency appears in the Fe doped system. The ability to induce the spin-polarized electron transport of the cluster in junction is not cosistent with the magnetic moment of cluster under isolated states.
A new analysis of electromagnetic transmission characteristics of anisotropic honeycomb sandwiches
Authors: Tang Xing-Gang  , Zhang Wei-Hong  , Qiu Ke-Peng  ,   School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

Honeycomb sandwiches are widely used as electromagnetic transparent materials for radomes. However, the electric anisotropy has a significant influence on the transmission performance. This work aims to investigate the electromagnetic transmission characteristics of the anisotropic sandwich panel. First, we deduce the effective permittivity of multilayered anisotropic sandwich material in the respect of the horizontal polarization and the perpendicular polarization components of the incident wave. Second, the transmission line network method related to the multilayered homogeneous medium is improved to simulate the electromagnetic transmission through honeycomb sandwiches and to calculate the transmission ratio. As the proposed method takes into account the three-dimensional anisotropy of each slab, it can simulate the transmission of plane wave with arbitrary incident direction in multilayered anisotropy sandwich panels, moreover, it can reveal the influence of material orientation on the transmission characteristics. Since the multilayer configuration is simulated by transmission line network, the proposed method is far more efficient than the finite element method. Numerical experiments indicate that the influence of the electric anisotropy on the transmission performance of honeycomb sandwich materials can be well revealed. In an incident angle range between 0 and 80 degrees, the simulation results fit well to the results obtained by the finite element method.
Research on the algorithm of multiple-image encryption based on the improved virtual optical imaging
Authors: Xu Ning  , Chen Xue-Lian  , Yang Geng  ,   College of Opto-Electronic Engineering, Nanjing University of Post and Telecommunications, Nanjing 210046, China;,   College of Computer, Nanjing University of Post and Telecommunications, Nanjing 210046, China
Published: December 2020

In this paper we propose an algorithm for multiple-image encryption based on the improved virtual optical imaging (VOI). The improved algorithm enhances the security by integrating several images into one as an encrypting object and increasing key space. It focuses on three issues. First, it encrypts the phase information, which can improve the performance of decryption effect of the system. Second, it combines random phase plate with a random amplitude board at the position of the random phase plate to increase the dimension of the key space and the ability to resist the attacks. Finally, it adds a random phase plate before the image place, which enhances the security of the system. It uses the peak signal-to-noise ratio to evaluate the performance of the proposed algorithm. Compared with the traditional VOI-based encryption method, the simulations show that the proposed method demonstrates a good performance in the sense of feasibility, robustness and security.
Colligated multiplexing approach to expanding the field of view in the recording process of digital holographic microscopy
Authors: Wu Yong-Li  , Yang Yong  , Zhai Hong-Chen  , Ma Zhong-Hong  , Gai Qi  , Deng Li-Jun  ,   Key Laboratory of Optical Information Science and Technology of the Education Ministry of China, Institute of Modern Optics,Nankai University, Tianjin 300071, China;,   College of Zhonghuan Information, Tianjin University of Technology, Tianjin 300071, China
Published: December 2020

We present a method to expand the record field of view in the recording process of digital holographic microscopy systems without loss of resolution. A series of incoherent sub-holograms covering different regions of sample can be recorded in a single frame of the CCD synchronously based on wavelength and polarization multiplexing. The reconstructed images can be obtained with information about different parts of the sample. Thus, the synthetic reconstructed image with a wider field can be achieved by image stitching and fusion technology without any form of scanning. Based on single-exposure working principle, this approach can be used for real-time recording of the dynamic samples without moving CCD, point source and tested samples. Experimental results show that the final synthetic image produced by the system in this paper can be achieved to be close to four times as large as the original record field of view with original resolution.
Locking the phase of balanced homodyne detection system for squeezed light
Authors: Zhang Yan  , Yu Xu-Dong  , Di Ke  , Li Wei  , Zhang Jing  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
Published: December 2020

The balanced homodyne detection technique is an important method to detect the quantum light field. The signal light injected into the phase sensitive optical parameter amplifier (OPA) is phase modulated. The output squeezed light of OPA is detected by the balanced homodyne detection system. When the phase sensitive OPA is operated at parametric amplification and deamplification respectively, we can judge which quadrature component of the quantum light field is measured by observing the modulation signal. We can demodulate the phase modulation signal to achieve the error signal, which is used to lock the relative phase of zero between the local and the quantum light fields (corresponding to the quadrature-amplitude of the unknown light field).
Shape and curved surface effect on silicon quantum dots
Authors: Huang Wei-Qi  , Zhou Nian-Jie  , Yin Jun  , Miao Xin-Jian  , Huang Zhong-Mei  , Chen Han-Qiong  , Su Qin  , Liu Shi-Rong  , Qin Chao-Jian  ,   Key Laboratory of Photoelectron Technology and Application, Institute of Nanophotonic Physics, Guizhou University, Guiyang 550025, China;,   State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003, China
Published: December 2020

Curviform surface breaks the symmetrical shape of silicon quantum dots on which some bonds can produce localized electronic states in band gap. The calculation results show that the bonding energy and electronic states of silicon quantum dots are different on various curved surfaces, for example, an Si–O–Si bridge bond on curved surface provides the localized levels in band gap and its bonding energy is shallower than that on facet. The red-shifting of PL spectrum on smaller silicon quantum dots can be explained by curved surface effect. Experiments demonstrate that silicon quantum dots are activated for emission due to the localized levels formed in the band gap.
Low-threshold electrically pumped ultraviolet random lasing from ZnO film prepared by pulsed laser deposition
Authors: Xu Yun  , Li Yun-Peng  , Jin Lu  , Ma Xiang-Yang  , Yang De-Ren  ,   State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China
Published: December 2020

ZnO films on silicon substrates are prepared by reactive sputtering and pulsed laser deposition, respectively. Their crystallinities, surface morphologies and photoluminescence actions are characterized using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy correspondingly. Furthermore, the electrically pumped random laser actions of the two metal-insulator-semiconductor structured devices based on the sputtered and pulse laser deposition ZnO films respectively are comparatively investigated. It is found that the device fabricated using the pulse laser deposition ZnO film possesses a much lower threshold current for random lasing and higher output optical power. This is due to the fact that the pulse laser deposition ZnO film has much fewer defects, leading to remarkably lower optical loss during the multiple scattering within such a ZnO film.
Optical properties of terahertz dielectric microcavity
Authors: Lu Xiao-Ke  , Guo Mao-Tian  , Su Jian-Po  , Gong Qiao-Xia  , Wu Jin-Ke  , Liu Jian-Li  , Chen Ming  , Ma Feng-Ying  ,   School of Physical Engineering, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

In this paper, multilayer films Si/[TiO2/Al2O3]2TiO2 and Si/[TiO2/MgO]2/TiO2 with thickness values from microns to tens of microns are fabricated by spin-coating method. The transmission spectra of these films are obtained by terahertz time-domain transmission spectrum system (THz-TDS). The phase shifts of reflection and phase penetration depths of Si/[TiO2/Al2O3]2TiO2 and Si/[TiO2/MgO]2/TiO2 are simulated by the transfer matrix method. On this basis, two kinds of symmetrical THz microcavities each with a structure of DBR/LT-GaAs/DBR are designed and the radiation spectra are also simulated. The results show that the intensities of two microcavities are enhanced by 19 and 14 times at resonance wavelength, respectively. There are two resonance peaks in the emission spectrum of the structure Si/[TiO2/Al2O3]2TiO2/LT-GaAs (12 μm)/[TiO2/Al2O3]2TiO2, which are located at 208 μm and 248 μm, respectively. The reason is discussed based on the effective cavity length. The feasibility to regulate the emission properties of the THz source by introducing dielectric microcavities is discussed.
All-optical format conversion from non-return-to-zero to return-to-zero based on dual-pump four-wave mixing in photonic crystal fiber
Authors: Hui Zhan-Qiang  , Zhang Jian-Guo  ,   School of Electronic Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710121, China;,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
Published: December 2020

A novel all-optical format conversion scheme based on dual-pump four-wave-mixing (DP-FWM) in dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF) is proposed and experimentally demonstrated. The original non-return-to-zero (NRZ) format is converted into double return-to-zero (RZ) format by injecting NRZ signal and double synchronized clock signals into the DF-HNL-PCF. The DP-FWM effect generates two sideband components, which carry the same data information as the original NRZ signal with RZ format. The wavelength tunability and dynamic range of format converter are investigated. The optimum extinct ratio and Q factor of converted signals are 15 dB and 5.4, respectively. The advantages of this scheme are that the each wavelength of double channel multicasting signals is dependent and flexible. Moreover, the system is transparent to bit rate as well as modulation format, and achieves all-optical wavelength conversion and wavelength multicasting.
Transmission characteristics of bullet in Kummer-Gauss optical lattice
Authors: Zhou Bo-Zhen  , Xu Si-Liu  , Cheng Zheng-Ze  ,   School of Electronic and Information Engineering, Hubei Institute of Science and Technology, Xianning 437100, China
Published: December 2020

Based on the division Fourier algorithm and the rapid virtual time evolution (AITEM) iterative method, the transmission characteristics of bullet in linear and nonlinear scattering out of phase modulation Kummer-Gauss optical lattice are studied. The results show that the linear and nonlinear phase modulation significantly change the bullet shape and its range of stability, and the nonlinear modulation depth through the propagation constant controls the stability region width. It is shown that stable space-time soliton energy will grow with nonlinear modulation depth strengthening.
Theoretical research on terahertz wave generation based on cascaded parametric oscillation
Authors: Li Zhong-Yang  , Bing Pi-Bin  , Xu De-Gang  , Cao Xiao-Long  , Yao Jian-Quan  ,   North China University of Water Resources and Electric Power, Zhengzhou 450011, China;,   College of Precision Instrument and Opto-Electronics Engineering, Institute of Laser and Opto-Electronics, Tianjin University, Tianjin 300072, China
Published: December 2020

A novel mechanism of cascaded parametric oscillation is proposed in this paper to solve the problem of low-efficiency in terahertz (THz) parametric oscillation. The cascaded parametric oscillation is theoretically analyzed based on PPLN crystal as an example. The tuning characteristics of the THz wave, which are affected by the parameters of pump wavelength, poling period of PPLN and operating temperature, are investigated. The characteristics of THz gain and absorption are deduced in the case of collinear interaction of the three mixing waves. The results indicate that the THz conversion efficiency can be greatly enhanced and the widely tunable THz wave can be realized in cascaded parametric oscillation. The experiment on cascaded parametric oscillation generating high-efficiency, wide-tuning, narrow-linewidth, continuous THz wave is designed based on the analysis above.
Investigation of a new kind of high birefringence photonic crystal fiber
Authors: Cao Ye  , Li Rong-Min  , Tong Zheng-Rong  ,   Key Laboratory of Film Electronics and Communication Devices, Key Laboratory of Intelligent Computing and Novel Software Technology, School ofComputer and Communication Engineering, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

A kind of highly birefringent and highly nonlinear photonic crystal fiber (PCF) is proposed. The fundamental mode field, birefrin-gence, nonlinear coefficient, effective mode area and dispersion characteristic of the fiber are studied by the full-vector finite elementmethod. Simulation results show that the birefringence becomes larger by reducing the air hole pitch, and the birefringence reachesup to 10-2 at a wavelength of 1550 nm, which is about two orders of magnitude higher than that of the regular elliptic polarizationmaintaining fiber. At the same time, a nonlinear coefficient of 42 W-1·km-1 is obtained. There are two zero dispersion wavelengthsin the visible and the near-infrared region respectively, and flattened chromatic dispersion from 800 nm to 2000 nm is obtained. Sucha design provides a new approach to obtaining highly birefringent and highly nonlinear PCF, and the fiber has a broad prospect ofapplication in the polarization control, nonlinear optics and dispersion control.
The implement and influence of different boundary conditions in direct simulation on particle sedimentation
Authors: Liu Han-Tao  , Chang Jian-Zhong  ,   School of Mechatronice Engineering of North University of China, Taiyuan 030051, China
Published: December 2020

In this paper, we present a direct numerical simulation of particle sedimentation in two-phase flow with four different boundary conditions. We demonstrate that different boundary conditions can result in quite different flow behaviors. Some interesting results are obtained. By redefining the computational domain at each time step according to the position of the particle, we construct an infinite channel, which can simulate the particle sedimentation accurately; the flow pattern of periodic boundary is quite different from the infinite channel because of the disturbed flow field; if the settlement is reached steadily before the closed bottom, the closed channel can also simulate the particle settled in the infinite channel; the fluidized condition slows down the particle sedimentation, which is very helpful for better using the boundary conditions.
Suppression of the spiral wave in cardiac tissue by using forcing currents with diversity
Authors: Wang Chun-Ni  , Ma Jun  ,   Department of Physics, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

Forcing currents are generated by using two types of constant currents to stimulate different areas of a medium. The external current is mapped into transmembrane current and stable gradient force is induced to drive the stable rotating spiral wave. The medium becomes homogeneous when the spiral wave is removed and the time series of sampled membrane potentials becomes stable value without considering noise. The scheme is confirmed to be effective in the presence of Gaussian white noise.
Detecting unstable periodic orbits from oil-gas-water three-phase slug flows
Authors: Zhao Jun-Ying  , Jin Ning-De  , Gao Zhong-Ke  ,   School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China
Published: December 2020

We use the close return method combined with adaptive threshold selection to detect the unstable periodic orbits from the signals measured from experimental oil-gas-water three-phase slug flows, and find that the period of the emulsion type slug flow is longer than that of oil in water type slug flow. Especially, the orbit of oil in water type slug flow is basically composed of one big loop and one small loop, and the emulsion type slug flow orbit is composed of two big smooth loops. In addition, we employ the method of adaptive optimal kernel time-frequency representation to investigate the flow behaviors of two typical oil-gas-water three-phase slug flows and indicate that the energy of the oil in water slug flow exhibits a dispersed distribution and its frequency spectrum consists of various components distributes in a wide range. In contrast, the energy of emulsion type slug flow is distributed in a rather concentrated region and the high frequency component in its frequency spectrum is much less than that of the oil in water slug flow. These results are well consistent with the detected structure of unstable periodic orbit, further suggesting that the fluid mechanism underlying oil in water type slug flow is more complicated than that of the emulsion type slug flow.
The lattice Boltzmann simulation of suspended particle movement in a tapered tube
Authors: Xue Ze  , Shi Juan  , Wang Li-Long  , Zhou Jin-Yang  , Tan Hui-Li  , Li Hua-Bing  ,   School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China;,   College of Physical Science and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

Based on the lattice Boltzmann method, the motion of single suspended particle in tapered tube is simulated numerically. The distributions of velocity and pressure in the flow field are obtained. The hydrodynamic force on the particle boundary is evaluated by conventional momentum exchange method (CME), lattice-type-dependent momentum-exchange method (LME) and stress tensor integral method (STI) separately. The variations of velocity and the trajectory of the particle which starts at different places are analyzed, the results evaluated by LME are in excellent agreement with those by STI and the results evaluated by CME are slightly different from those by the former two methods.
Large-eddy simulation and experimental study of deflecting oscillation of planar opposed jets
Authors: Tu Gong-Yi  , Li Wei-Feng  , Huang Guo-Feng  , Wang Fu-Chen  ,   Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology,Shanghai 200237, China
Published: December 2020

The deflecting oscillation of planar opposed jets is experimentally studied and numerically simulated by large-eddy simulation (LES) at 25 ≤ Re ≤ 10000 (Re= U0hρ/μ, where U0 is the bulk velocity of the jet at the nozzle exit, h is the height of the slit of the planar nozzle, and ρ and μ are the density and dynamic viscosity of fluid, respectively) and 4h≤ L ≤ 40h, where L is the nozzle separation. The numerical results are validated by comparing with the experimental results of planar opposed jets. Maps of parameter space describing the deflecting oscillation of planar opposed jets at various nozzle separations and exit Reynolds numbers are presented. And the variation features of deflecting oscillation periods and velocity-pressure of turbulent planar opposed jets are primarily investigated. The results of the study show that the LES can effectively predict the deflecting oscillation of planar opposed jets. The velocity and pressure at specific points vary periodically while the deflecting oscillation of planar opposed jets happens. Furthermore, the variation periods of velocity and pressure are in accordance with the periods of the deflecting oscillation. In essence, the deflecting oscillation of planar opposed jets is caused by periodical variation and transformation of the velocity and pressure.
Observation of encapsulated microbubble dynamics in ultrasound field
Authors: Liang Jin-Fu  , Chen Wei-Zhong  , Shao Wei-Hang  , Zhou Chao  , Du Lian-Fang  , Jin Li-Fang  ,   The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093, China;,   Department of Ultrasound, Shanghai First People's Hospital, Shanghai 200089, China
Published: December 2020

Using a long-distance microscope imaging system and a lock-in phase integrate technique, optical measurements demonstrate that the evolutional behaviors of a phospholipid-shelled micro-bubble, a kind of ultrasound contrast agent, under two ultrasound frequencies and different pressures. Dozens of frames of an oscillating microbubble for one acoustic cycle are captured. The experimental data of micro-bubble diameter are fit by the numerical calculations of the Hoff model and the Rayleigh-Plesset model, respectively. The results show the good agreement between experimental data and the theoretical calculation in the Hoff model. In addition, the spectral analysis based on the experimental data indicates that the relative intensity of the second harmonic increases with the driving pressure amplitude.
High-quality InGaN epilayers grown by PA-MBE and abnormal incorporation behavior of Indium into InGaN
Authors: Wu Yuan-Yuan  , Zheng Xin-He  , Wang Hai-Xiao  , Gan Xing-Yuan  , Wen Yu  , Wang Nai-Ming  , Wang Jian-Feng  , Yang Hui  ,   Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China;,   University of Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

Growth behaviors of InxGa1-xN (x ≤ 0.2) materials by plasma-assisted molecular beam epitaxy (PA-MBE) are investigated in detail. A precise control of the incorporation of indium into InxGa1-xN at a growth temperature of 580 ℃ is realized. The In0.19Ga0.81N shows a very narrow width of 587 arcsec for the (10.2) asymmetrical reflection from high-resolution X-ray diffraction and the background electronic concentration is 3.96× 1018 cm3. In the region of metal-rich growth, no negligible indium incorporation is observed even if the Ga beam flux is much larger than the equivalent N flux. This growth behavior might be ascribed to an incomplete Ga incorporation during InGaN growth. In addition, a slight increase of In flux results in crystalline quality degradation of InGaN epilayers.
First-principles caculation and experimental study of metal magnetic memory effects
Authors: Yang Li-Jian  , Liu Bin  , Gao Song-Wei  , Chen Li-Jia  ,   Institute of Information Science and Technology, Shenyang University of Technology, Shenyang 110870, China
Published: December 2020

In order to investigate the mechanism and regular pattern of metal magnetic memory (MMM) signal, from the angle of electron spin, the magnetomechanical model of MMM is set up, and the relationship between stress concentration state and self magnetic flux leakage (SMFL) signal is calculated by the plane wave and pseudo-potential method based on the density functional theory. The research results show that the fundamental reason for SMFL is lattice distortion induced by loads, and the theoretical calculations are in very good agreement with the experimental observations. The present work is helpful for testing the mechanism of MMM.
Photocatalysis property of V-N codoped wurtzite ZnO by first-principles study
Authors: Gui Qing-Feng  , Cui Lei  , Pan Jing  , Hu Jing-Guo  ,   College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China;,   Suqian College, Suqian 223800, China
Published: December 2020

Based on density functional theory of first-principle theory, we systematically investigate the electronic structure and optical property of V-, N- monodoping and V-N codopiong and compare with pure ZnO. The results show that the absorption in the visible light region is enhanced for the doped system, especially for V-N codoped ZnO. The calculated biding energy indicates that the V-N codoping is the most stable system, thus, V-N codoped ZnO is considered as an ideal photocatalyst. Moreover, the method of anion-cation codoping could be better used in photoelectrochemistry and also in the preparation of stable and high performance short wavelength photoelectron devices.
Model of secondary electron emission at high incident electron energy for metal
Authors: Yang Wen-Jin  , Li Yong-Dong  , Liu Chun-Liang  ,   Xi’an Jiaotong University, Electronic Physics and Devices Laboratory, Xi’an 710049, China
Published: December 2020

The models of the true secondary electron emission and backscattered electron emission for metal are provided, based on the physical process of secondary electron emission from metal at high incident electron energy. The formula for the true secondary electron yield at high incident electron energy is derived with the Bethe equation known to provide accurate and simple analytical expressions for the stopping power and the probability that a secondary electron produced in a material reaches the surface and is emitted into the vacuum. The formula for the backscattered electron yield at high incident electron energy is derived with the absorbing rule for the incident electron in the material. All the above results lead to a new model for secondary electron emission from metal at high incident electron energy. The secondary electron yields of Au, Ag, Cu and Al derived with the new model are in good agreement with the results obtained from the scatters process simulation code-Casino.
Influence of gradient doping on photoelectric conversion efficiency of organic photovoltaic devices
Authors: Wang Peng  , Guo Run-Da  , Chen Yu  , Yue Shou-Zhen  , Zhao Yi  , Liu Shi-Yong  ,   State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
Published: December 2020

On the basis of the traditional bulk heterojunction structure, we introduce a method of gradient doping in the mixing layer to improve photoelectric conversion efficiency (ηp) of organic photovoltaic device (OPV). One of the devices with the structure of ITO/CuPc (10 nm)/CuPc:C60 (2:1) (4 nm)/CuPc:C60 (1.5:1) (4 nm)/CuPc:C60 (1:1) (4 nm)/CuPc:C60 (1:1.5) (4 nm)/CuPc:C60 (1:2) (4 nm)/C60 (30 nm)/Bphen (8 nm)/Al (100 nm) show the improvement on performance:short-circuit current JSC = 9.18 mA/cm2, photoelectric conversion efficiency ηp = 1.35% under AM1.5 solar illumination. Compared with ηp of the traditional bulk heterojunction OPV ITO/CuPc(10 nm)/CuPc:C60 (1:1) (20 nm)/C60(30 nm)/Bphen(8 nm)/Al(100 nm), the ηp of the present structure is improved by 25%, which is attributed to the improvement on percolating paths of donor and acceptor molecules across the entire mixing layer, thus increasing the charge collection efficiency. Consequently, the overall device series resistance is reduced and the photoelectric conversion efficiency is enhanced.
The periodic orbits of sport model of plasmas particle in the process of magnetosphere-ionosphere coupling
Authors: Chen Li-Juan  , Lu Shi-Ping  , Mo Jia-Qi  ,   School of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

Using Mawhin's continuation theorem, we discussed the existence of periodic solution for a class of nonlinear problem, and then investigated the problem of periodic solution of sport model of plasmas particle in the process of magnetosphere-ionosphere coupling. A result on the existence of periodic solution to the model is obtained.
The periodic solution problem of a relative rotation nonlinear dynamic system with time-varying stiffness
Authors: Li Xiao-Jing  , Chen Xuan-Qing  , Yan Jing  ,   College of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, China
Published: December 2020

Firstly, the relative rotation nonlinear dynamic system is established, which contains time-varying stiffness, commonly damping force and compulsive periodic force. Secondly, some results of the existence and uniqueness of periodic solutions of the system are obtained by using the continuation theorem of coincidence degree theory. The significance is that we generalize the results published in the literature. Furthermore, an example is given to illustrate that our results are new.
Investigation of the stability of time-domain magnetic field integral equations based on marching on-in time algorithm
Authors: Li Jin-Yan  , Nie Zai-Ping  , Zhao Yan-Wen  ,   School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

A sufficient stability condition for time-domain magnetic field integral equations (TDMFIE) based on marching on-in time (MOT) algorithm is obtained through theoretical derivation using the norm. If the condition is satisfied, it can be ensured that the computational results will always be stable in late-time no matter what kind of incident wave is. Moreover, a factor expressing the recursive relationship of the currents is obtained, which can represent the constringency of the currents. Finally, the sufficient stability condition is validated by numerical results. Meanwhile, the numerical results also verify that the factor can be used to represent the stability of the currents.
Effects of initial states on continuous-time quantum walk in the optical waveguide array
Authors: Ren Chun-Nian  , Shi Peng  , Liu Kai  , Li Wen-Dong  , Zhao Jie  , Gu Yong-Jian  ,   College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China;,   College of Information Science and Technology, Qingdao University of Science and Technology, Qingdao 266042, China
Published: December 2020

Continuous-time quantum random walk is constructed when photons propagate passing the branches of the waveguide array. It is possible to make quantum simulator, based on the quantum walk in waveguides, on a commercial scale firstly, but there are still some problems such as input state, the structure and boundary of the waveguides that should be treated at present. A nearest-neighbor coupling model is used to deal with the question of coupled waveguides and an explicit analytical solution can be derived. Using the analytical solution, we analyze the effects of input state on particle number probability distribution function and the second-order coherence degree of the quantum walk process in periodic waveguides. The results show that the symmetry properties of the input state would influence the distribution of second-order coherence degree, but have little effect on the probability distribution function.