http://www.openstarts.units.it:80/dspace/handle/10077/4159 2013-05-18T12:43:03Z http://www.openstarts.units.it:80/dspace/handle/10077/4231 Title: Low Frequency Electromagnetic Scattering. The Impedance Problem for a Spere Authors: Venkov, George; Arnaoudov, Yani Abstract: We consider the low-frequency scattering problem of a plane electromagnetic wave by a small sphere, of the boundary of which an impedance condition is satisfied. The impedance boundary condition was introduced by Leontovich (1948) and it accounts for situations where the obstacle is not perfectly conducting but the exterior field will not penetrate deeply into the scatterer. Il provides a method to simulate the material properties of the surface of highly absorbing coating layers. For the near electromagnetic field we obtain the low-frequency coefficients of the zeroth and the first order while in the far field we derive the leading non-vanishing terms for the scattering amplitude, the scattering and the absorption cross-sections. Type: Articolo 2001-01-01T00:00:00Z http://www.openstarts.units.it:80/dspace/handle/10077/4230 Title: Singular semilinear elliptic equations in the half-space Authors: Tintarev, Kyril Abstract: We show that equation $x_{N}^{q}\Delta u+u^{p-1}=0$ on the half-space $Y=\mathbf{R}^{N-1}\times\left(0,\infty\right)$ and on some of its subsets has a ground state solution for $q=N-\frac{p\left(N-2\right)}{2},\; p\;\epsilon\left(2,2*\right)$. For N $\geq$ 3 the end point cases p=2 and p=2{*} correspond to eh Hardy inequality and the limit exponent Sobolev inequality respectively. For N=2 the problem can be interpreted in terms of Laplace-Beltrami operator on the hyperbolic half-plane. Type: Articolo 2001-01-01T00:00:00Z http://www.openstarts.units.it:80/dspace/handle/10077/4229 Title: Special relativity without physics Authors: Pfeffer, Washek F. Abstract: Using only causality and the constant speed of light, I derive the Poincaré transformation group. In this derivation I make no a priori assumptions about the linearity or continuity of the transformations Type: Articolo 2001-01-01T00:00:00Z http://www.openstarts.units.it:80/dspace/handle/10077/4228 Title: A monomiality principle approach to the Gould-Hopper Polynomials Authors: Noschese, Silvia Abstract: We show how to derive properties of the Gould-Hopper polynomials using operational rules associated with the monomiality principle. Type: Articolo 2001-01-01T00:00:00Z