Search results for "neuma"

Parallel fictitious domain method for a non‐linear elliptic neumann boundary value problem

1999

Parallelization of the algebraic fictitious domain method is considered for solving Neumann boundary value problems with variable coefficients. The resulting method is applied to the parallel solution of the subsonic full potential flow problem which is linearized by the Newton method. Good scalability of the method is demonstrated on a Cray T3E distributed memory parallel computer using MPI in communication. Copyright © 1999 John Wiley & Sons, Ltd.

Spectral theory of a Neumann-Poincaré-type operator and analysis of cloaking by anomalous localized resonance II

2014

If a body of dielectric material is coated by a plasmonic structure of negative dielectric constant with nonzero loss parameter, then cloaking by anomalous localized resonance (CALR) may occur as the loss parameter tends to zero. The aim of this paper is to investigate this phenomenon in two and three dimensions when the coated structure is radial, and the core, shell and matrix are isotropic materials. In two dimensions, we show that if the real part of the permittivity of the shell is $-1$ (under the assumption that the permittivity of the background is $1$), then CALR takes place. If it is different from $-1$, then CALR does not occur. In three dimensions, we show that CALR does not occu…

Nonlinear nonhomogeneous Neumann eigenvalue problems

2015

We consider a nonlinear parametric Neumann problem driven by a nonhomogeneous differential operator with a reaction which is $(p-1)$-superlinear near $\pm\infty$ and exhibits concave terms near zero. We show that for all small values of the parameter, the problem has at least five solutions, four of constant sign and the fifth nodal. We also show the existence of extremal constant sign solutions.

On the number of solutions of a Duffing equation

1991

The exact number of solutions of a Duffing equation with small forcing term and homogeneous Neumann boundary conditions is given. Several bifurcation diagrams are shown.

Multiplicity of solutions for two-point boundary value problems with asymptotically asymmetric nonlinearities

1996

Porous medium equation with absorption and a nonlinear boundary condition

2002

where is a bounded domain with smooth boundary, @=@ is the outer normal derivative, m ? 1; p; and q are positive parameters and u0 is in L∞( ). Problems of this form arise in mathematical models in a number of areas of science, for instance, in models for gas or :uid :ow in porous media [3] and for the spread of certain biological populations [13]. In the semilinear case (that is for m=1), there is an extensive literature about global existence and blow-up results for this type of problems, see among others, [5,9,16] and the literature therein. For the degenerate case (that is for m = 1), with a nonlinear boundary condition, local existence and uniqueness of weak solutions which are limit o…

Characterization of the inter-annual, seasonal, and diurnal variations of condensation particle concentrations at Neumayer, Antarctica

2011

Continuous condensation particle (CP) observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 cm<sup>−3</sup>) showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 10<sup>3</sup> cm<sup>−3</sup> in March. Minimum values below 10<sup>2</sup> cm<sup>–3</sup> were observed during June/July. Dedicated time series analyses in the time and frequency domain revealed no significant correlations between…

Fractional p-Laplacian evolution equations

2016

Abstract In this paper we study the fractional p-Laplacian evolution equation given by u t ( t , x ) = ∫ A 1 | x − y | N + s p | u ( t , y ) − u ( t , x ) | p − 2 ( u ( t , y ) − u ( t , x ) ) d y for  x ∈ Ω ,  t > 0 , 0 s 1 , p ≥ 1 . In a bounded domain Ω we deal with the Dirichlet problem by taking A = R N and u = 0 in R N ∖ Ω , and the Neumann problem by taking A = Ω . We include here the limit case p = 1 that has the extra difficulty of giving a meaning to u ( y ) − u ( x ) | u ( y ) − u ( x ) | when u ( y ) = u ( x ) . We also consider the Cauchy problem in the whole R N by taking A = Ω = R N . We find existence and uniqueness of strong solutions for each of the above mentioned problem…

Existence and Regularity for a Class of Nonlinear Hyperbolic Boundary Value Problems

2002

AbstractThe regularity of the solution of the telegraph system with nonlinear monotone boundary conditions is investigated by two methods. The first one is based on D'Alembert-type representation formulae for the solution. In the second method the telegraph system is reduced to a linear Cauchy problem with a locally Lipschitzian functional perturbation; then regularity results are established by appealing to the theory of linear semigroups.

A system for rapid radiochemical separations from aqueous solutions

1969

Abstract For the study of short-lived fission products, an automatic system has been developed that allows to irradiate aqueous solutions sealed in polystyrene capsules, to separate chemically the radioactive products formed, and to start counting, all within a few seconds. Irradiations are performed in a pneumatic tube system installed in a horizontal beam hole of a reactor. The capsule is projected into a separation apparatus where it breaks by impact. Its content is then sucked through a thin reactive layer that takes up the desired product. The whole sequence of irradiation, transportation, chemical separation, and counting is controlled by automatic timers. The adaption of this techniq…