A theoretical study of radial flow chromatography was carried out based on a general nonlinear multicomponent rate model which considers radial dispersion. external mass transfer, intraparticle diffusion. and nonlinear multicomponent isotherms. Radial dispersion and mass transfer coefficients were treated as variables which are dependent on the radial coordinate of the radial flow column. The m...

The BEM is applied to the solution of the torsion problem of non-homogeneous anisotropic non-circular prismatic bars. The problem is formulated in terms of the warping function. This formulation leads to a second order partial differential equation with variable coefficients, subjected to a generalized Neumann type boundary condition. The problem is solved using the Analog Equation Method (AEM)...

To study the problem of the assigned Gauss curvature with conical singularities on Riemanian manifolds, we consider the Liouville equation with a single Dirac measure on the two-dimensional sphere. By a stereographic projection, we reduce the problem to a Liouville equation on the euclidean plane. We prove new multiplicity results for bounded radial solutions, which improve on earlier results o...

Westudy theGreen functionof thePoisson equation in two, three and four dimensions. The solution g of the equation g x x x x D 2 d  ¢ = ¢      ( ) ( ) ( ) , where x and x ¢  areD-dimensional position vectors, is customarily expanded into radial and angular coordinates. For the two-dimensional case (D=2), we find a subtle interplay of the necessarily introduced scaleLwith the radial com...

The radial Schrödinger equation for a spherically symmetric potential can be regarded as a one dimensional classical harmonic oscillator with a time-dependent spring constant. For solving classical dynamics problems, symplectic integrators are well known for their excellent conservation properties. The class of gradient symplectic algorithms is particularly suited for solving harmonic oscillato...

Exact solutions are derived for an n-dimensional radial wave equation with a general power nonlinearity. The method is based on the introduction of groupinvariant jet space variables associated with the point symmetry group admitted for the wave equation and is applicable more generally to any nonlinear PDEs. It is shown to yield not only group-invariant solutions as derived by standard symmetr...