2019年, 第71卷, 第03期　
刊出日期：2019-03-01

  

• 全选
  |

• Select
  Thermally Radiative Viscous Fluid Flow Over Curved Moving Surface in Darcy-Forchheimer Porous Space

  A. Rauf, Z. Abbas, S. A. Shehzad, T. Mushtaq

  理论物理通讯. 2019, 71(03): 259-266.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  A numerical analysis is developed for incompressible hydromagnetic viscous fluid passed through a curved stretching surface. Fluid saturated by porous space is bounded by curved surface. Term of porous medium is characterized by implementation of Darcy-Forchheimer theory. Adequate similarity variables are implemented to develop a system of non-linear ordinary differential system of equations, which govern the flow behavior. The impact of radiation constraint and Eckert number is incorporated in the energy equation. Numerical scheme based on RKF45 technique is implemented to solve the derived flow model. Prescribed heat flux (PHF) and prescribed surface temperature (PST) boundary conditions are utilized on temperature with Prescribed Surface Concentration (PSC) and Prescribed Mass Flux (PMF) on concentration. Flow behavior is discussed for both the slip and no-slip conditions. Dimensionless physical quantities are presented through graphs and tables.
• Select
  On the Role of Differentiation Parameter in a Bound State Solution of the Klein-Gordon Equation

  B. C. Lütfüoğlu

  理论物理通讯. 2019, 71(03): 267-273.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Recently, the bound state solutions of a confined Klein-Gordon particle under the mixed scalar-vector generalized symmetric Woods-Saxon potential in one spatial dimension have been investigated. The obtained results reveal that in the spin symmetric limit discrete spectrum exists, while in the pseudo-spin symmetric limit it does not. In this manuscript, new insights and information are given by employing an analogy of the variational principle. The role of the difference of the magnitudes of the vector and scalar potential energies, namely the differentiation parameter, on the energy spectrum is examined. It is observed that the differentiation parameter determines the measure of the energy spectrum density by modifying the confined particle's mass-energy in addition to narrowing the spectrum interval length.
• Select
  Gauge Transformation for BC_r-KP Hierarchy and Its Compatibility with Additional Symmetry

  耿露敏, 陈慧展, 李娜, 程纪鹏

  理论物理通讯. 2019, 71(03): 274-280.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The BC_r-KP hierarchy is an important sub-hierarchy of the KP hierarchy. In this paper, the BC_r-KP hierarchy is investigated from three aspects. Firstly, we study the gauge transformation for the BC_r-KP hierarchy. Different from the KP hierarchy, the gauge transformation must keep the constraint of the BC_r-KP hierarchy. Secondly, we study the gauge transformation for the constrained BC_r-KP hierarchy. In this case, the constraints of the Lax operator must be invariant under the gauge transformation. At last, the compatibility between the additional symmetry and the gauge transformation for the BC_r-KP hierarchy is explored.
• Select
  Influence of Partial Coherent Light on the Transmission Spectrum and Goos-Hänchen Shift in Rydberg Atomic Medium

  Dilawar Ali, Muhammad Umer Iftikhar, Muqaddar Abbas, Ziauddin

  理论物理通讯. 2019, 71(03): 281-286.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  A cold atomic medium (Rydberg medium) with cascade configuration under the blockade mechanism is considered. A partial coherent light (PCL) beam is incident on the medium, which makes an angle θ with z-axis. We study the influence of PCL field on the transmission spectrum and find high transmission of probe field for PCL field. Conversely, it is investigated that the transparency of probe field decrease for coherent light field. The transmission of probe field is also studied via beam width of PCL field and investigated high transmission of probe field for small beam width and vice versa. Interestingly, the Goos-Hänchen shift (GHS) in the transmitted light (TL) is studied for PCL field. Large negative and positive GHS in the TL are investigated for PCL field and small beam width of PCL field.
• Select
  Neutrino Phenomenology of a High Scale Supersymmetry Model

  雷莹珂, 刘纯

  理论物理通讯. 2019, 71(03): 287-292.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  CP violation in the lepton sector, and other aspects of neutrino physics, are studied within a high scale supersymmetry model. In addition to the sneutrino vacuum expectation values (VEVs), the heavy vector-like triplet also contributes to neutrino masses. Phases of the VEVs of relevant fields, complex couplings, and Zino mass are considered. The approximate degeneracy of neutrino masses mν1 and mν2 can be naturally understood. The neutrino masses are then normal ordered, ～ 0.020 eV, 0.022 eV, and 0.054 eV. Large CP violation in neutrino oscillations is favored. The effective Majorana mass of the electron neutrino is about 0.02 eV.
• Select
  β^--Decay Half-Lives for Waiting Point Nuclei Around N=126

  游击林, 吴庆东, 张小平, 支启军

  理论物理通讯. 2019, 71(03): 293-297.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  We have systematically analyzed the experimental β^--decay half-lives of waiting point heavy nuclei around neutron number N=126. A new set of parameters for the exponential formula of β^--decay half-lives is proposed. The forbidden transition effects are included in the new set of parameters self-consistently. Theoretical β^--decay half-lives of nuclei around N=126 are compared with recent theoretical results and experimental data. It is found that the new theoretical results are in better agreement with experimental data. The unknown β^--decay half-lives of some nuclei in this region are predicted for studies on nuclear structure far from stability and the nucleosynthesis in stars.
• Select
  Energy Conditions and Conservation Laws in LRS Bianchi Type I Spacetimes via Noether Symmetries

  Sumaira Saleem Akhtar, Tahir Hussain

  理论物理通讯. 2019, 71(03): 298-306.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  In this paper, we have completely classified the locally rotationally symmetric (LRS) Bianchi type I spacetimes via Noether symmetries (NS). The usual Lagrangian corresponding to LRS Bianchi type I metric is used to find the set of determining equations. To achieve a complete classification, these determining equations are generally integrated to find the components of NS vector field and the metric coefficients. During this procedure, several cases arise which give different Noether algebras of dimension 5,..., 9, 11, and 17. A comparison is established between the obtained NS and the Killing and homothetic vectors. Corresponding to all NS generators, the conservation laws are stated by using Noether's theorem. The metrics which we have obtained as a result of our classification are shown to be anisotropic or perfect fluids which satisfy certain energy conditions.
• Select
  Entropy Quantization of Schwarzschild Black Hole

  M. Atiqur Rahman

  理论物理通讯. 2019, 71(03): 307-311.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The surface gravity of Schwarzschild black hole can be quantized from the test particle moving around different energy states analog to the Bohr's atomic model. We have quantized the Hawking temperature and entropy of Schwarzschild black hole from quantization of surface gravity. We also have shown that the change of entropy reduces to zero when the boundary shrinks to very small size.
• Select
  A Modified Gravity Theory: Null Aether

  Metin Gürses, Çetin Şentürk

  理论物理通讯. 2019, 71(03): 312-326.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  General quantum gravity arguments predict that Lorentz symmetry might not hold exactly in nature. This has motivated much interest in Lorentz breaking gravity theories recently. Among such models are vector-tensor theories with preferred direction established at every point of spacetime by a fixed-norm vector field. The dynamical vector field defined in this way is referred to as the "aether". In this paper, we put forward the idea of a null aether field and introduce, for the first time, the Null Aether Theory (NAT)-a vector-tensor theory. We first study the Newtonian limit of this theory and then construct exact spherically symmetric black hole solutions in the theory in four dimensions, which contain Vaidya-type non-static solutions and static Schwarzschild-(A) dS type solutions, Reissner-Nordström-(A) dS type solutions and solutions of conformal gravity as special cases. Afterwards, we study the cosmological solutions in NAT:We find some exact solutions with perfect fluid distribution for spatially flat FLRW metric and null aether propagating along the x direction. We observe that there are solutions in which the universe has big-bang singularity and null field diminishes asymptotically. We also study exact gravitational wave solutions-AdS-plane waves and pp-waves-in this theory in any dimension D ≥ 3. Assuming the Kerr-Schild-Kundt class of metrics for such solutions, we show that the full field equations of the theory are reduced to two, in general coupled, differential equations when the background metric assumes the maximally symmetric form. The main conclusion of these computations is that the spin-0 aether field acquires a "mass" determined by the cosmological constant of the background spacetime and the Lagrange multiplier given in the theory.
• Select
  Modulated Dust-Acoustic Wave Packets in an Opposite Polarity Dusty Plasma System

  S. Jahan, N. A. Chowdhury, A. Mannan, A. A. Mamun

  理论物理通讯. 2019, 71(03): 327-333.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The nonlinear propagation of the dust-acoustic bright and dark envelope solitons in an opposite polarity dusty plasma (OPDP) system (composed of non-extensive q-distributed electrons, iso-thermal ions, and positively as well as negatively charged warm dust) has been theoretically investigated. The reductive perturbation method (which is valid for a small, but finite amplitude limit) is employed to derive the nonlinear Schrödinger equation. Two types of modes, namely, fast and slow dust-acoustic (DA) modes, have been observed. The conditions for the modulational instability (MI) and its growth rate in the unstable regime of the DA waves are significantly modified by the effects of non-extensive electrons, dust mass, and temperatures of different plasma species, etc. The implications of the obtained results from our current investigation in space and laboratory OPDP medium are briefly discussed.
• Select
  Interaction of Wave Trains with Defects

  陈贤伟, 李鹏飞, 袁晓平, 赵叶华, 马军, 陈江星

  理论物理通讯. 2019, 71(03): 334-338.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The evolution and transition of planar wave trains propagating through defects (obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regimes, namely fusion, "V" waves, and spiral waves, are observed in turn and the underlying mechanism is discussed. The dynamics is concerned with the shapes of the defects. Circle, triangle, and rectangle defects with different sizes are considered. The increase of pacing frequency broadens the fan-shaped broken region in the behind of a rectangle defect. The increase of width of a triangle defect leads to breakup of wave trains easier while the change of height shows opposite effect, which is presented in a phase diagram. Dynamical comparison on defects with different shapes indicates that the decrease of the defect width along the propagation of wave trains makes the fan-shaped region and the minimal frequency for breakup of spiral both increased.
• Select
  Spin-Dependent Electron Tunneling in ZnSe/Zn_1-xMn_xSe Heterostructures with Double δ-Potentials

  L. Bruno Chandrasekar, M. Karunakaran, K. Gnanasekar

  理论物理通讯. 2019, 71(03): 339-343.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Using the matrix method, spin-dependent tunneling properties such as barrier transparency, the degree of resonance polarization, and tunneling lifetime of electrons are examined in the non-magnetic/diluted magnetic semiconductor heterostructure. The effects of the double δ-potential and the magnetic field are discussed on the transport properties of the electrons. The introduction of double δ-potential shifts the resonance peak of polarization to the higher energy value. Both height and position of the δ-potential influence the degree of resonance polarization in the considered heterostructure. The increasing magnetic field enhances the spin-polarization.
• Select
  Boundary Layer Flow over a Curved Surface Imbedded in Porous Medium

  Shafiq Ahmad, S. Nadeem, Noor Muhammad

  理论物理通讯. 2019, 71(03): 344-348.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  This research is made to visualize the boundary layer flow by a curved stretching sheet embedded in porous medium. The geometry is bended (curved), therefore the curvilinear coordinates are used to model the present problem. Fluid is electrically conducting with the presence of uniform magnetic field. The governing non-linear partial differential equation reduces to non-linear ordinary differential equations by using the dimensionless suitable transformations. The numerical solutions are obtained by using the method bvp4c from MATLAB. The effects of curvature parameter, nondimensional magnetic parameter, and porosity parameter on the velocity field and skin friction coefficient are examined. The skin friction profile enhances with enhancing the values of porosity and magnetic parameter. Comparison of the present results with the existing results in the literature for the flat surface is also given.
• Select
  Pull-in Instability Analysis of Nanoelectromechanical Rectangular Plates Including the Intermolecular, Hydrostatic, and Thermal Actuations Using an Analytical Solution Methodology

  F. Samadani, R. Ansari, K. Hosseini, A. Zabihi

  理论物理通讯. 2019, 71(03): 349-356.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The current paper presents a thorough study on the pull-in instability of nanoelectromechanical rectangular plates under intermolecular, hydrostatic, and thermal actuations. Based on the Kirchhoff theory along with Eringen's nonlocal elasticity theory, a nonclassical model is developed. Using the Galerkin method (GM), the governing equation which is a nonlinear partial differential equation (NLPDE) of the fourth order is converted to a nonlinear ordinary differential equation (NLODE) in the time domain. Then, the reduced NLODE is solved analytically by means of the homotopy analysis method. At the end, the effects of model parameters as well as the nonlocal parameter on the deflection, nonlinear frequency, and dynamic pull-in voltage are explored.