共查询到20条相似文献，搜索用时 31 毫秒
1.
The aim of the present paper is to investigate the influence both of gravity field and initial stress on the propagation of
Rayleigh waves in an orthotropic thermoelastic medium subject to certain boundary conditions. We suppose that the body is
under initial stress alonqx
1-direction and incremental thermal stresses. The wave velocity equation has been obtained. Many special cases and comparison
with the previous results have been studied. 相似文献
2.
L. C. Garcia de Andrade 《Astrophysics and Space Science》1992,198(1):79-83
The equivalence of Lagrangian containing gravitational, electromagnetic, scalar, and torsion fields is discussed. It is shown that the equation for the variation of the scalar field leads to a torsion wave equation generated by electromagnetic field leads to a torsion wave equation generated by electromagnetic fields. The system is proved to be equivalent to a Proca field coupling torsion non-minimally to a massive photon and having the scalar Higgs field as a strength of this photon-torsion coupling. The generalized Maxwell equations containing the scalar fields are obtained. The torsion potential around the Sun or a more massive collapsing star in the weak field limit is estimated. 相似文献
3.
The equations of magnetohydrodynamic equilibria for a plasma in a gravitational field are investigated analytically. For equilibria with one ignorable spatial coordinate, the equations reduce to a single nonlinear elliptic equation for the magnetic potential , known as the Grad–Shafranov equation. Specifying the arbitrary functions in the latter equation, one gets a nonlinear elliptic equation. Analytical solutions of the elliptic equation are obtained for the case of a nonlinear isothermal atmosphere in a uniform gravitational field. The solutions are obtained by using the Painlevé analysis, and are adequate for describing parallel filaments of diffuse, magnetized plasma suspended horizontally in equilibrium in a uniform gravitational field. 相似文献
4.
We obtain renormalized stress tensor of a mass-less, charge-less dynamical quantum scalar field, minimally coupled with a spherically symmetric static Lukewarm black hole. In two dimensional analog the minimal coupling reduces to the conformal coupling and the stress tensor is found to be determined by the nonlocal contribution of the anomalous trace and some additional parameters in close relation to the work presented by Christensen and Fulling. Lukewarm black holes are a special class of Reissner-Nordström-de Sitter space times where its electric charge is equal to its mass. Having the obtained renormalized stress tensor we attempt to obtain a time-independent solution of the well known metric back reaction equation. Mathematical derivations predict that the final state of an evaporating quantum Lukewarm black hole reduces to a remnant stable mini black hole with moved locations of the horizons. Namely the perturbed black hole (cosmological) horizon is compressed (extended) to scales which is smaller (larger) than the corresponding classical radius of the event horizons. Hence there is not obtained an deviation on the cosmic sensor-ship hypothesis. 相似文献
5.
In this paper we studied the influence of the initial stress on the propagation of Rayleigh waves in a homogeneous-isotropic, generalized thermo-elastic body, subject to the boundary conditions that the outer surface is traction free. In addition it is subject to linear radiations, adiabatic isothermal transfer conditions. We found that the frequency equation of Rayleigh waves contains a term involving the initial stress and, therefore, the phase velocity of Rayleigh waves changes with respect of this initial stress, when the initial stress, vanishes, the derived frequency equation reduces to that one obtained in classical generalized thermo-elastic case which includes the relaxation time of heat conduction. 相似文献
6.
The force-free electromagnetic field represents a natural generalization of the well-known force-free magnetic field model and allows the magnetic field to maintain electric charge separation.The basic equation for the cylindrical oscillations of the force-free electromagnetic field is obtained and solved for a linear case. The spectrum of possible resonances in a magnetized atmosphere is discussed. 相似文献
7.
本文利用Hartle和Hawking的方法,讨论了具有旋量场的量子宇宙学,得到了相应的Wheeler-De Witt方程。求出了具有旋量场的宇宙波函数。从波函数可以看出,当标度因子α很小时,旋量场的影响很强,具体的形式与初始条件有关,而当标度因子α很大时,旋量场的行为和标量场一样。 相似文献
8.
Consideration is given to the motion of electrons in a photon field of the monoenergetic or power-law spectrum under the conditions when the main mechanism of energy loss is the inverse Compton scattering by field photons. This process changes the primary spectrum of electrons and converts low-energy field photons to high-energy gamma-quanta for which the electron confinement region is assumed to be optically thin. The electron and gamma-ray spectra have been obtained in a wide energy interval including the Klein-Nishina and Thomson regions. A simple qualitative dependence of the solutions found on the field parameters and the primary spectrum of electrons has been established.The electron and gamma-ray spectra have been obtained by numerically solving the kinetic equation dependent on two variables: the energy of electrons and their path (or the time of motion) in a photon field. The results dramatically differ from the solution of the steady-state kinetic equation which depends only on the electron energy and is frequently used in the given problem. 相似文献
9.
Determination of the potential field in a fixed (inertial) system may be accomplished by the solution of a homogeneous linear partial differential equation when a family of orbits of a body moving in the field is given. This partial differential equation was presented and thoroughly analyzed earlier. The present paper discusses the same problem in a rotating system where the centrifugal and Coriolis effects render the pertinent partial differential equation in general non-homogeneous and non-linear. A linear, though non-homogeneous, partial differential equation for the determination of the synodic potential is obtained only in the special case of iso-energetic families of orbits. 相似文献
10.
A. M. Elnaggar 《Astrophysics and Space Science》1992,190(2):177-190
The object of the present paper is to investigate the influence of initial stress on the waves propagation in a generalized thermoelastic granular medium subjected to the boundary conditions that the outer surface is traction free. In addition, it is subjected to temperature boundary conditions. The wave velocity equation for the generalized thermoelastic granular medium Rayleigh wave under the influence of initial stress has been obtained. The classical result has been derived as a limiting case similar to one which was obtained by Ewinget al. (1957). 相似文献
11.
12.
John A. Adam 《Astrophysics and Space Science》1987,133(2):317-337
The reduced linearized equations of ideal magnetohydrodynamics which are highly nonlinear in the eigenvalue parameter, are linearized about a prescribed value of that parameter, enabling the equation to be expressed as a Schrödinger equation with piecewise uniform coefficients. Reflection and transmission coefficients are obtained using standard techniques, and in addition to the possibility of total transmission of an incident wave occurring (together with complex-valued resonance energies), the magnetic field introduces other total transmission energy levels which have no counterpart in the absence of a magnetic field. 相似文献
13.
A. M. Abd-Alla 《Astrophysics and Space Science》1991,178(2):175-183
The aim of the present paper is to investigate generation of waves in an infinite micropolar elastic medium under the influence both of initial stressp and body forces X. The equation of motion has been solved applying the Fourier-Hankel transform. The final results, the displacement, the stress, the rotation, and the couple stress components have been obtained in analytical form as integrals involving Bessel function of first kind and of zero order. 相似文献
14.
The influence of compressibility of the medium on cosmic ray (CR) fluctuations has been investigated. The CR transport equation has been used to obtain an equation for the second moment of CR particle density (correlation function of the particle density). It is shown that the effects due to the compressibility of the medium has an essential influence on CR fluctuations. The relations between CR power spectra and random velocity field have been determined. For the turbulence which is created by an ensemble of weak sound waves we have obtained the connection between the spectral indices of CR power spectra and the velocity field. It is shown that the spectral indices of CR power spectra and the velocity field of random sound waves coincide. 相似文献
15.
The transport of cosmic rays in the interplanetary medium is considered in terms of the kinetic equation describing the energetic
particle scattering by magnetic irregularities and their focusing by the regular interplanetary magnetic field. The analytical
expression for solar cosmic ray distribution function in the approximation of radial regular magnetic field is obtained and
the evolution of energetic particle angular distribution is analyzed. The obtained results can be used for the analysis of
ground-level enhancements of cosmic ray intensity. 相似文献
16.
G. M. Webb 《Solar physics》1986,106(2):287-313
The equations of magnetohydrostatic equilibria for a plasma in a gravitational field are investigated analytically. For equilibria with one ignorable spatial coordinate, the equations reduce to a single nonlinear elliptic equation for the magnetic potential A. Similarity solutions of the elliptic equation are obtained for the case of an isothermal atmosphere in a uniform gravitational field. The solutions are obtained from a consideration of the invariance group of the elliptic equation. The importance of symmetries of the elliptic equation also appears in the determination of conservation laws. It turns out that the elliptic equation can be written as a variational principle, and the symmetries of the variational functional lead (via Noether's theorem) to conservation laws for the equation. As an example of the application of the similarity solutions, we construct a model magnetostatic atmosphere in which the current density J is proportional to the cube of the magnetic potential, and falls off exponentially with distance vertical to the base, with an e-folding distance equal to the gravitational scale height. The solutions show the interplay between the gravitational force, the J × B force (B, magnetic field induction) and the gas pressure gradient. 相似文献
17.
The study of Einstein's field equations describing Robertson-Walker cosmological models with massive scalar field and viscous fluid representing the matter has been made. The problem has been investigated with and without the source density in the wave equation. Corresponding exact solutions of the field equations have been obtained under different physical equations of state: namely, (i) dust distribution, (ii) Zeldovich fluid distribution, (iii) disordered distribution of radiation subject to physically realistic conditions. The physical interpretations of the physically realistic solutions has been investigated. It has been found that physically realistic solutions has been obtained for closed cosmological models only. 相似文献
18.
The field equations and the equation of motion for stationary, axisymmetric, rotating ideal magnetohydrodynamic flow are presented. Exact solutions are obtained for rigid rotation, for vanishing and nonvanishing Lorentz force. 相似文献
19.
The dynamical problem for thermal stresses in an infinite isotropic elastic cylinder of radius a with its axis along the z-axis, subject to fixed boundary conditions is studied. The Fourier heat conduction equation has been solved applying the Fourier transform and the theory of complex variable. The thermoelastic equation of motion has been separated into two wave equations which can be solved separately. The temperature, the displacement and the stress components have been obtained in analytical form as series involving Bessel function of first kind and of order zero. 相似文献
20.
The various modes of plasma turbulence waves (including MHD waves) are easily excited under cosmic circumstances. In this paper, if we consider that the celestial bodies rotate, there is a source term generated for the magnetic induced equation by the excited plasma turbulence waves. If we expand the turbulent field in the Fourier series and include rotation velocity, the dynamo equation for turbulent waves is obtained. We have also obtained the solutions of various wave forms corresponding to different rotation velocities and then we significantly discuss the magnetic fields in the Sun, planets, and other celestial bodies. 相似文献