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Probability Distribution Function of Passive Scalars in Shell Models

Communications in Theoretical physics 2008年第4期49卷 1033-1038页

作者： ZHANG Xiao-Qiang WANG Guang-Rui CHEN Shi-Gang Department of Physics Hebei Normal University Shijiazhuang 050016 China Graduate School of the China Academy of Engineering Physics P.O. Box 8009（28） Beijing 100088 China Center for Nonlinear Studies Institute of Applied Physics and Computational Mathematics Beijing 100088 China

A shell-model version of passive scalar problem is introduced, which is inspired by the model of K. Ohkitani and M. Yakhot [K. Ohkitani and M. Yakhot, Phys. Rev. Lett. 60 （1988） 983; K. Ohkitani and M. Yakhot, Prog. Theor. Phys. 81 （1988） 329]. As in the original problem, the prescribed random velocity field is Gaussian and 5 correlated in time. Deterministic differential equations are regarded as nonlinear Langevin equation. Then, the Fokker-Planck equations of PDF for passive scalars are obtained and solved numerically. In energy input range （n 〈 5, n is the shell number.）, the probability distribution function （PDF） of passive scalars is near the Gaussian distribution. In inertial range （5≤ n ≤ 16） and dissipation range （n ≥ 17）, the probability distribution function （PDF） of passive scalars has obvious intermittence. And the scaling power of passive scalar is anomalous. The results of numerical simulations are compared with experimental measurements.

关键词： shell model passive scalar distribution function

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Rayleigh-Taylor instability under multimode perturbation:Discrete Boltzmann modeling with tracers

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Communications in Theoretical physics 2022年第11期74卷 180-198页

作者： Hanwei Li Aiguo Xu Ge Zhang Yiming Shan Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China HEDPS Center for Applied Physics and TechnologyCollege of EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Energy Resources Engineering Department Stanford University367 Panama StStanfordCA 94305-2220United States of America

The two-dimensional Rayleigh-Taylor Instability(RTI)under multi-mode perturbation in compressible flow is probed via the Discrete Boltzmann Modeling(DBM)with *** distribution of tracers provides clear boundaries between light and heavy fluids in the position ***,the position-velocity phase space offers a new perspective for understanding the flow behavior of RTI with intuitive geometrical *** effects of viscosity,acceleration,compressibility,and Atwood number on the mixing of material and momentum and the mean nonequilibrium strength at the interfaces are investigated separately based on both the mixedness defined by the tracers and the non-equilibrium strength defined by the *** mixedness increases with viscosity during early stage but decreases with viscosity at the later ***,compressibility,and Atwood number show enhancement effects on mixing based on different *** the system relaxes from the initial state,the mean non-equilibrium strength at the interfaces presents an initially increasing and then declining trend,which is jointly determined by the interface length and the macroscopic physical quantity *** conclude that the four factors investigated all significantly affect early evolution behavior of an RTI system,such as the competition between interface length and macroscopic physical quantity *** results contribute to the understanding of the multi-mode RTI evolutionary mechanism and the accompanied kinetic effects.

关键词： Rayleigh-Taylor instability multi-mode perturbation Discrete Boltzmann modeling tracers non-equilibrium effects kinetic modeling

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A Pseudo-Spectral Scheme for Systems of Two-Point Boundary Value Problems with Left and Right Sided Fractional Derivatives and Related Integral Equations

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Computer Modeling in Engineering & Sciences 2021年第7期128卷 21-41页

作者： I.G.Ameen N.A.Elkot M.A.Zaky A.S.Hendy E.H.Doha Department of Mathematics Faculty of ScienceAl-Azhar UniversityCairoEgypt Department of Mathematics Faculty of ScienceCairo UniversityGiza12613Egypt Department of Applied Mathematics Physics DivisionNational Research CentreDokkiCairo12622Egypt Department of Computational Mathematics and Computer Science Institute of Natural Sciences and MathematicsUral Federal UniversityYekaterinburg620002Russia Department of Mathematics Faculty of ScienceBenha UniversityBenha13511Egypt

We target here to solve numerically a class of nonlinear fractional two-point boundary value problems involving left-and right-sided fractional *** main ingredient of the proposed method is to recast the problem into an equivalent system of weakly singular integral ***,a Legendre-based spectral collocation method is developed for solving the transformed ***,we can make good use of the advantages of the Gauss quadrature *** present the construction and analysis of the collocation *** results can be indirectly applied to solve fractional optimal control problems by considering the corresponding Euler–Lagrange *** numerical examples are given to confirm the convergence analysis and robustness of the scheme.

关键词： Spectral collocation method weakly singular integral equations two-point boundary value problems convergence analysis

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Dielectronic recombination and resonant transfer excitation processes for helium-like krypton

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Chinese physics B 2012年第10期21卷 224-230页

作者：胡骁骊屈一至张松斌张宇 College of Material Sciences and Optoelectronic Technology Graduate University of the Chinese Academy of Sciences P.O.Box 4588Beijing 100049China Department of Chemistry Texas A & M UniversityCollege StationTX 77842USA The Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O.Box 8009Beijing 100088China

The relativistic configuration interaction method is employed to calculate the dielectronic recombination(DR) cross sections of helium-like krypton via the 1s2lnl ’(n = 2,3,...,15) ***,the resonant transfer excitation(RTE) processes of Kr 34+ colliding with H,He,H 2,and CH x(x = 0-4) targets are investigated under the impulse *** needed Compton profiles of targets are obtained from the Hartree-Fock wave *** RTE cross sections are strongly dependent on DR resonant energies and strengths,and the electron momentum distributions of the *** H 2 and H targets,the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l ’ to 1.88 for other resonances,which demonstrates the weak molecular effects on the Compton profiles of H *** CH x(x = 0-4) targets,the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons;as the number of hydrogen increases in CH x,the RTE cross section almost increases by the same value,displaying the strong separate atom character for the ***,further comparison of the individual orbital contributions of C(2p,2s,1s) and CH 4(1t 2,2a 1,1a 1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%,19.9%,and 0.2% between 2p-1t 2,2s-2a 1,and 1s-1a 1 orbitals,respectively.

关键词： dielectronic recombination Compton profile resonant transfer excitation

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Photoresponse Characteristics of Quantum Ratchet Detectors Grown by MOCVD 5th

Photoresponse Characteristics of Quantum Ratchet Detectors G...

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5th China and International Young Scientist Terahertz Conference, YTHZ 2024

作者： Wang, Yi Bai, Peng Yang, Ning Chu, Weidong Xie, Yan Wang, Yingxin Chen, Meng Zhao, Ziran Institute of Applied Physics and Computational Mathematics Beijing100088 China National Key Laboratory of Computational Physics Beijing100088 China Department of Engineering Physics Tsinghua University Beijing100084 China

ISBN: (纸本)9789819737857

Terahertz detection has important application in space exploration, biomedicine, and national defense security. At present, although terahertz thermal detectors can operate at room temperature, their response speed is relatively slow, and the detection band coverage is narrow. Photon-type terahertz detectors have the potential for high-speed response, and the response band is flexible and adjustable, but their operating temperature is generally low (all working in the liquid helium temperature range). Developing a terahertz detection device with high speed, high sensitivity, high temperature operation, wide band response, simple fabrication process, and relatively low cost has become a focus and frontier issue in terahertz technology research. The quantum ratchet detector proposed by us is expected to achieve high-temperature, high-speed, and broadband terahertz detection. In this paper, we use MOCVD technology for material epitaxial growth and fabricate quantum ratchet detectors. We studied their photoresponse characteristics and ratchet characteristics, and discussed the possibility of high-temperature operation. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： High temperature operations

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Taenia solium taeniasis and cysticercosis:extinction or outbreak

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Animal Diseases 2023年第2期3卷 90-103页

作者： Jacob I.Irunde Faraja B.Luhanda Department of Mathematics Physics and InformaticsMkwawa University College of EducationIringaTanzania Department of Applied Mathematics and Computational Sciences The Nelson Mandela African Institution of Science and TechnologyArushaTanzania

Taenia solium taeniasis and cysticercosis are neglected zoonotic diseases that affect human health and economies of developing *** this work,we formulate and analyze deterministic and continuous time Markov chain(CTMC)stochastic models to determine parameters that drive Taenia solium taeniasis and cysticercosis and the likelihood of their *** basic reproduction number R0 is computed by the next generation matrix approach,sensitivity index of each parameter in R0 is derived by the normalized forward sensitivity index and the likelihood of diseases’extinction is computed by the multitype branching *** analysis shows that humans with Taenia solium taeniasis,infectious pork and Taenia solium eggs in the environment play an important role in the transmission of Taenia solium taeniasis and cysticercosis,and the model exhibits forward bifurcation at R0=*** implies that R0<1 is a sufficient condition to eliminate Taenia solium taeniasis and *** CTMC model,analysis shows that the probability of Taenia solium taeniasis and cysticercosis extinction is high if the diseases emerge from humans with Taenia solium cysticercosis and there is an outbreak if the diseases emerge from either humans with Taenia solium taeniasis or infectious pork or Taenia solium eggs in the *** control Taenia solium taeniasis and cysticercosis,the intervention strategies should focus on improving hygiene and sanitation for reducing shedding rate of Taenia solium eggs in the environment,inspection of pork for reducing the rate of acquiring Taenia solium taeniasis and spraying of insecticides for killing Taenia solium eggs in the environment.

关键词： Taeniasis Cysticercosis Basic reproduction number Sensitivity analysis Multitype branching process Stochastic model

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Travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation

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Science China mathematics 2011年第3期54卷 555-572页

作者： DENG ShengFu1, GUO BoLing2 & WANG TingChun2,3 1department of mathematics, Zhanjiang Normal University, Zhanjiang 524048, China 2Institute of applied physics and computational mathematics, Beijing 100088, China 3 College of Math and physics, Nanjing University of Information Science and Technology, Nanjing 210044, China 1. Department of Mathematics Zhanjiang Normal University Zhanjiang 524048 China2. Institute of Applied Physics and Computational Mathematics Beijing 100088 China3. College of Math and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation ut-uxxt + (1 + b)umux = buxuxx + uuxxx are considered where b > 1 and m are positive integers. The qualitative analysis methods of planar autonomous systems yield its phase portraits. Its soliton wave solutions, kink or antikink wave solutions, peakon wave solutions, compacton wave solutions, periodic wave solutions and periodic cusp wave solutions are obtained. Some numerical simulations of these solutions are also given.

关键词： homoclinic orbits heteroclinic orbits peakon wave solutions compacton wave solutions periodic cusp wave solutions

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Suppression of stimulated Raman scattering by angularly incoherent light, towards a laser system of incoherence in all dimensions of time, space, and angle

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Matter and Radiation at Extremes 2023年第3期8卷 27-33页

作者： Yi Guo Xiaomei Zhang Dirui Xu Xinju Guo Baifei Shen Ke Lan Department of Physics Shanghai Normal UniversityShanghai 200234China Institute of Applied Physics and Computational Mathematics Beijing 100094China

Laser–plasma instability(LPI)is one of the main obstacles to achieving predictable and reproducible fusion at high gain through laser-driven inertial confinement fusion(ICF).In this paper,for the first time,we show analytically and confirm with three-dimensional particle-incell simulations that angular incoherence provides suppression of the instability growth rate that is additional to and much stronger than that provided by the well-known temporal and spatial incoherence usually used in ICF *** the model used in our calculations,the maximum field ratio between the stimulated Raman scattering and the driving pulses drops from 0.2 for a Laguerre–Gaussian pulse with a single nonzero topological charge to 0.05 for a super light spring with an angular momentum spread and random relative *** particular,angular incoherence does not introduce extra undesirable hot *** provides a novel method for suppressing LPI by using light with an angular momentum spread and paves the way towards a low-LPI laser system for inertial fusion energy with a super light spring of incoherence in all dimensions of time,space,and angle,and may open the door to the use of longer-wavelength lasers for inertial fusion energy.

关键词： scattering dimensions angular

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DYNAMICS OF VORTEX SURFACES IN 3 DIMENSIONS - THEORY AND SIMULATIONS

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PHYSICA D-NONLINEAR PHENOMENA 1989年第1期40卷 91-118页

作者： AGISHTEIN, ME MIGDAL, AA Department of Physics University of California at San Diego La Jolla CA 92093 USA1 1 Current address: Program in Applied and Computational Mathematics Princeton University Fine Hall Washington Road Princeton NY 08544-100 USA.

The dynamics of vortex surfaces in an ideal fluid is considered. The Hamiltonian and the action are constructed and topological conservation laws are discussed. The axially symmetric case is reduced to an effective 2d problem and studied numerically. There is qualitative correspondence with the results of Moore and Krasny for the purely 2d problem. The general case is approximated by means of a triangulated surface and a corresponding computer model is constructed, taking into account the topological conservation laws. The axially symmetric motion of the triangulated surface agrees with the 2d model, but there are some angular instabilities, which may lead to new vortex structures. The large-scale asymmetric 3d simulations with fairly developed instabilities are reported. The results agree with the general scenario of hierarchy of vortex structures.

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Quantum theory of the nonlinear Fano effect in hybrid metal-semiconductor nanostructures: The case of strong nonlinearity

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Physical Review B 2011年第8期84卷 081405(R)-081405(R)页

作者： Wei Zhang Alexander O. Govorov Institute of Applied Physics and Computational Mathematics P.O. Box 8009(28) Beijing 100088 People's Republic of China Department of Physics and Astronomy Ohio University Athens Ohio 45701 USA

We develop a quantum theory of the field-tunable nonlinear Fano effect in the hybrid metal-semiconductor nanostructures, in which the plasmon (semicontinuous collective intraband excitation) and the exciton (discrete single-particle interband excitation) are treated on the same footing. Our quantum theory shows that the quantum interference due to the plasmon-exciton interaction leads to the nonlinear Fano effect described by a generalized complex field-tunable Fano factor for the systems with strong external field and dephasing. We establish the relation between quantum and semiclassical theories and show that the results of the quantum and semiclassical theories differ both qualitatively and quantitatively in the strongly nonlinear regime—in particular, the quantum theory predicts the absence of nonlinear instability in the hybrid systems with plasmon relaxation.

关键词： QUANTUM theory SEMICONDUCTOR-metal boundaries NANOSTRUCTURES NONLINEAR theories PLASMONS (physics) EXCITON theory

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