Electrostatics in a gravitational field

Author(s):  
E. T. Copson

SynopsisIn this paper, the electrostatic potential of a point charge in a Reisser-Nordström gravitational field is found in closed form by using the theory of Hadamard's elementary solution of a partial differential equation of elliptic type.

Author(s):  
S. S. Okoya

This paper is devoted to closed-form solutions of the partial differential equation:θxx+θyy+δexp(θ)=0, which arises in the steady state thermal explosion theory. We find simple exact solutions of the formθ(x,y)=Φ(F(x)+G(y)), andθ(x,y)=Φ(f(x+y)+g(x-y)). Also, we study the corresponding nonlinear wave equation.


1981 ◽  
Vol 34 (2) ◽  
pp. 113 ◽  
Author(s):  
EA Jeffery

The partial differential equation 02rf>+m2c/>+Ac/>3 = 0 (where 0 2 = 0;-\72) is converted to the ordinary differential equation 2�>/du2 + (Nlu)d�>ldu +m2c/> +).�>3 = O. In this conversion, 02U and (OU)2 are assumed to depend only on u, where u is a Fnction of x,y, Z, t, and further, Nlu is the normal curvature of the hypersurface u = constant. In order to solve for u, the analogous Euclidean 4-space problem with 0 2 = 0; +\72 is examined initially. The only possible values of N are then 0, 1, 2, 3 corresponding to hypersurfaces that are a hyperplane, a hypercylinder (one curved face), a hypercylinder (two curved faces) and a ypersphererespectively. These hypersurfaces are transformed to Minkowski space via xk ~ ixk , k = 1,2,3. Then by solving the ordinary differential equation new solutions to the original partial differential equation are found, one of which has a closed form.


Author(s):  
E. T. Copson

SummaryIt is shown that the elementary solution Γ(x, ξ; t – τ) of the equationbehaves, as t → τ + O, in very much the same manner as the elementary solution of the equation of heat.


1981 ◽  
Vol 31 (4) ◽  
pp. 405-414
Author(s):  
J. Chabrowski ◽  
B. Thompson

AbsrtactThe purpose of this note is to investigate traces of the functions In(1 +|u|), where u is a solution of a semi-linear partial differential equation of elliptic type, belonging to an appropriate Sobolev space. This article complements the results of Chabrowski and Thompson (1980), and Mihailov (1972), (1976).


2022 ◽  
Vol 6 (1) ◽  
pp. 24
Author(s):  
Muhammad Shakeel ◽  
Nehad Ali Shah ◽  
Jae Dong Chung

In this article, a new method for obtaining closed-form solutions of the simplified modified Camassa-Holm (MCH) equation, a nonlinear fractional partial differential equation, is suggested. The modified Riemann-Liouville fractional derivative and the wave transformation are used to convert the fractional order partial differential equation into an integer order ordinary differential equation. Using the novel (G’/G2)-expansion method, several exact solutions with extra free parameters are found in the form of hyperbolic, trigonometric, and rational function solutions. When parameters are given appropriate values along with distinct values of fractional order α travelling wave solutions such as singular periodic waves, singular kink wave soliton solutions are formed which are forms of soliton solutions. Also, the solutions obtained by the proposed method depend on the value of the arbitrary parameters H. Previous results are re-derived when parameters are given special values. Furthermore, for numerical presentations in the form of 3D and 2D graphics, the commercial software Mathematica 10 is incorporated. The method is accurately depicted, and it provides extra general exact solutions.


1931 ◽  
Vol 2 (3) ◽  
pp. 135-139 ◽  
Author(s):  
H. S. Ruse

Hadamard defines the “elementary solution” of the general linear partial differential equation of the second order, namely(Aik, BiC being functions of the n variables x1, x2, .., xn, which may be regarded as coordinates in a space of n dimensions), to be one of those solutions which are infinite to as low an order as possible at a given point and on every bicharacteristic through that point.


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