2019年, 第71卷, 第02期　
刊出日期：2019-02-01

  

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  Numerical Analysis of Unsteady Magneto-Biphase Williamson Fluid Flow with Time Dependent Magnetic Field

  Madiha Bibi, M. Y. Malik, A. Zeeshan

  理论物理通讯. 2019, 71(02): 143-151.

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  Numerical investigation of the dusty Williamson fluid with the dependency of time has been done in current disquisition. The flow of multiphase liquid/particle suspension saturating the medium is caused by stretching of porous surface. The influence of magnetic field and heat generation/absorption is observed. It is assumed that particle has a spherical shape and distributed uniformly in fluid matrix. The unsteady two-dimensional problems are modeled for both fluid and particle phase using conservation of mass, momentum and heat transfer. The finalized model generates the non-dimensioned parameters, namely Weissenberg number, unsteadiness parameter, magnetic parameter, heat generation/absorption parameter, Prandtl number, fluid particle interaction parameter, and mass concentration parameters. The numerical solution is obtained. Locality of skin friction and Nusselt number is deliberately focused to help of tables and graphs. While inferencing the current article it is clearly observed that increment of Williamson parameter, unsteadiness parameter, magnetic parameter, volume fraction parameter, and mass concentration parameter reduces the velocity profile of fluid and solid particles as well. And increment of Prandtl number, unsteadiness parameter, volume fraction parameter, and mass concentration parameter reduces the temperature profile of fluid and solid particles as well.
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  Characteristics of Rogue Waves on a Soliton Background in the General Coupled Nonlinear Schrödinger Equation

  王秀彬, 韩波

  理论物理通讯. 2019, 71(02): 152-160.

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  Under investigation in this work is the general coupled nonlinear Schrödinger (gCNLS) equation, which can be used to describe a wide variety of physical processes. By using Darboux transformation, the new higher-order rogue wave solutions of the equation are well constructed. These solutions exhibit rogue waves on a multi-soliton background. Moreover, the dynamics of these solutions is graphically discussed. Our results would be of much importance in enriching and predicting rogue wave phenomena arising in nonlinear and complex systems.
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  New Bilinear Bäcklund Transformation and Higher Order Rogue Waves with Controllable Center of a Generalized (3+1)-Dimensional Nonlinear Wave Equation

  申亚丽, 姚若侠, 李岩

  理论物理通讯. 2019, 71(02): 161-169.

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  In this paper, we first obtain a bilinear form with small perturbation u₀ for a generalized (3+1)-dimensional nonlinear wave equation in liquid with gas bubbles. Based on that, a new bilinear Bäcklund transformation which consists of four bilinear equations and involves seven arbitrary parameters is constructed. After that, by applying a new symbolic computation method, we construct the higher order rogue waves with controllable center to the generalized (3+1)-dimensional nonlinear wave equation. The rogue waves present new structure, which contain two free parameters α and β. The dynamic properties of the higher order rogue waves are demonstrated graphically. The graphs tell that the parameters α and β can control the center of the rogue waves.
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  A Note on the Transformation of Variables of KP Equation, Cylindrical KP Equation and Spherical KP Equation

  刘春平

  理论物理通讯. 2019, 71(02): 170-174.

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  In a recent article (Commun. Theor. Phys. 67 (2017) 207), three (2+1)-dimensional equations-KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same KdV equation by using different transformation of variables, respectively. In this short note, by adding an adjustment item to original transformation, three more general transformation of variables corresponding to above three equations have been given. Substituting the solutions of the KdV equation into our transformation of variables, more new exact solutions of the three (2+1)-dimensional equations can be obtained.
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  Chiral Extrapolation of Lattice Data of ∧_b → ∧_c Form Factors

  李瑞成, 郭新恒

  理论物理通讯. 2019, 71(02): 175-191.

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  An extrapolation to the physical limit for the lattice data of ∧_b → ∧_c form factors computed in the nonphysical region is made in this work through a class of fitting functions proposed by us with nonlinear dependence on m_π² derived in the chiral perturbative theory (ChPT) and the heavy quark effective theory (HQET) framework. Then the results are applied to calculate the differential and integrated ∧_b → ∧_c semileptonic decay rates. Meanwhile, a comparison between our results and those obtained through the extrapolation functions with naive linear dependence on m_π² is made. It is shown that the difference between the extrapolated central values of these two cases is about 5%. The total uncertainties (depending on the momentum transfer q²) in the linear case are about 5%~10% (caused by the uncertainties of lattice data) and those in the nonlinear case are about 10%~20% (caused by the uncertainties of both lattice data and input parameters in ChPT and HQET). More accurate lattice data and parameters in ChPT and HQET are needed to reduce the uncertainties of the extrapolated results.
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  Properties of Charmonium States in a Phenomenological Approach

  Praveen P D'Souza, Antony Prakash Monteiro, K. B. Vijaya Kumar

  理论物理通讯. 2019, 71(02): 192-202.

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  We investigate the spectrum and decay rates of charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining potential along with the potential derived from instanton vacuum to account for the hyperfine mass splitting of charmonium states in variational approach. We predict radiative E1, M1, two-photon, lepton and two-gluon decay rates of low lying charmonium states. An overall agreement is obtained with the experimental masses and decay widths. We have estimated the branching ratio of two gluons decaying into light hadrons.
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  Roles of N△ → NN and πN → △ Reactions in Heavy-Ion Collisions at Intermediate Energies

  谢文杰, 王丽君, 苏军, 张丰收

  理论物理通讯. 2019, 71(02): 203-208.

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  Within the framework of the isospin-dependent transport model, the roles of the reactions N△ → NN and πN → △ are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N△ → NN plays an important role for heavy impact systems and small impact parameters than for light impact systems and large impact parameters. The resorption process πN → △ is of importance for heavy impact systems and large impact parameters than for light impact systems and small impact parameters. Thus the influences of the reaction N△ → NN (πN → △) on pion production dynamics can be neglected in heavy-ion collisions for smaller (larger) impact parameters and light systems. It is the reaction πN → △ that causes the anti-correlation of pions and nucleons in the rapidity dependence of the directed flow.
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  Dark Energy Accretion onto Van der Waal's Black Hole

  Sandip Dutta, Ritabrata Biswas

  理论物理通讯. 2019, 71(02): 209-219.

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  We consider the most general static spherically symmetric black hole metric. The accretion of the fluid flow around the Van der Waal's black hole is investigated and we calculate the fluid's four-velocity, the critical point and the speed of sound during the accretion process. We also analyze the nature of the universe's density and the mass of the black hole during accretion of the fluid flow. The density of the fluid flow is also taken into account. We observe that the mass is related to redshift. We compare the accreting power of the Van der Waal's black hole with Schwarzschild black hole for different accreting fluid.
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  f(G, T) Gravity with Cylindrically Symmetric Relativistic Fluids

  M. Farasat Shamir, M. Awais Sadiq

  理论物理通讯. 2019, 71(02): 220-230.

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  The aim of this paper is to examine the structure scalars with account of f(G, T) theory of gravity. We consider the cylindrically symmetric spacetime with dissipative anisotropic background. We have determined the structure scalars by orthogonally decomposing the Riemann curvature tensor and it is shown that these scalars are associated with fundamental properties of fluid. We further investigate the mass function along with the transport equation and discuss their role on the evolutionary stages of relativistic stellar systems. We have also analyzed these structure scalars for static fluid distributions and it is concluded that all possible solutions of field equations can be expressed through these scalars.
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  Semi-exact Solutions of Konwent Potential

  董茜, 董世山, Eduardo Hernández-Márquez, Ramón Silva-Ortigoza, 孙国华, 董世海

  理论物理通讯. 2019, 71(02): 231-236.

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  In this work we study the quantum system with the symmetric Konwent potential and show how to find its exact solutions. We find that the solutions are given by the confluent Heun function. The eigenvalues have to be calculated numerically because series expansion method does not work due to the variable z ≥ 1. The properties of the wave functions depending on the potential parameter A are illustrated for given potential parameters V₀ and a. The wave functions are shrunk towards the origin with the increasing|A|. In particular, the amplitude of wave function of the second excited state moves towards the origin when the positive parameter A decreases. We notice that the energy levels $\epsilon_{i}$ increase with the increasing potential parameter|A|≥ 1, but the variation of the energy levels becomes complicated for|A|∈ (0, 1), which possesses a double well. It is seen that the energy levels $\epsilon_{i}$ increase with|A|for the parameter interval A ∈ (-1, 0), while they decrease with|A|for the parameter interval A ∈ (0, 1).
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  Nonlinear Dispersive and Dissipative Electrostatic Structures in Two-Dimensional Electron-Positron-Ion Quantum Plasma

  Nabakumar Ghosh, Biswajit Sahu

  理论物理通讯. 2019, 71(02): 237-242.

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  The nonlinear features of two-dimensional ion acoustic (IA) solitary and shock structures in a dissipative electron-positron-ion (EPI) quantum plasma are investigated. The dissipation in the system is taken into account by incorporating the kinematic viscosity of ions in plasmas. A quantum hydrodynamic (QHD) model is used to describe the quantum plasma system. The propagation of small but finite amplitude solitons and shocks is governed by the Kadomtsev-Petviashvili-Burger (KPB) equation. It is observed that depending on the values of plasma parameters (viz. quantum diffraction, positron concentration, viscosity), both compressive and rarefactive solitons and shocks are found to exist. Furthermore, the energy of the soliton is computed and possible solutions of the KPB equation are presented numerically in terms of the monotonic and oscillatory shock profiles
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  Active Online Learning in the Binary Perceptron Problem

  周海军

  理论物理通讯. 2019, 71(02): 243-252.

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  The binary perceptron is the simplest artificial neural network formed by N input units and one output unit, with the neural states and the synaptic weights all restricted to ±1 values. The task in the teacher-student scenario is to infer the hidden weight vector by training on a set of labeled patterns. Previous efforts on the passive learning mode have shown that learning from independent random patterns is quite inefficient. Here we consider the active online learning mode in which the student designs every new Ising training pattern. We demonstrate that it is mathematically possible to achieve perfect (error-free) inference using only N designed training patterns, but this is computationally unfeasible for large systems. We then investigate two Bayesian statistical designing protocols, which require 2.3N and 1.9N training patterns, respectively, to achieve error-free inference. If the training patterns are instead designed through deductive reasoning, perfect inference is achieved using N +log₂N samples. The performance gap between Bayesian and deductive designing strategies may be shortened in future work by taking into account the possibility of ergodicity breaking in the version space of the binary perceptron.
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  An Approximation of the Steady Gravity Wave Induced by Mountainous Topography

  Peng-Cheng Xu, Qun-Jie Zuo, Shou-Ting Gao

  理论物理通讯. 2019, 71(02): 253-258.

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  An approximation of the orography gravity wave, which is induced by mountainous topography, is considered in this study. By assuming that the horizontal wind is a linear function with respect to the height, the approximating equation for the orography gravity waves is obtained. Four topography functions are considered in this study and the orography gravity wave are obtained. The dynamics of the orography gravity wave is then discussed by considering the effect of the surface topography and background horizontal wind.