On the boundary value problem for the spectrally loaded heat conduction operator

We consider the boundary value problems in a quarter-plane for a loaded heat conduction operator (one-dimensional in the space variable). A peculiarity of the operator in question is as follows: first, the spectral parameter is the coefficient of the loaded summand; second, the order of the derivative in the loaded summand is equal to that of the differential part of the operator, and third, the load point moves with a variable velocity. We demonstrate that the boundary value problem under study is Noetherian.     

Statistical analysis of findings in external and internal audits and assessments in a testing laboratory

A statistical analysis of findings in assessments by an accreditation body, external audits and internal audits in an accredited testing laboratory for gamma-ray spectrometry is presented. The frequencies of observations reported in different areas were examined and analysed. The differences are interpreted in terms of the varying importance associated with the different areas as perceived by auditors and assessors.     

Groups of Exponential Algebras

In this paper we study groups corresponding a free exponential algebra, a free product of exponential algebras and a HNN-extension of exponential algebras over a field F of characteristic 0.     

Quotient rings and Fountain-Gould left orders by the local approach

We study Fountain-Gould left orders in semiprime rings coinciding with their socles by means of local rings at elements.     

Numerical simulation of astronomical observations with ISO-LWS

Summary The purpose of this work is the numerical simulation of the ISO-LWS spectrometer output with a computer code aiming at obtaining data similar as far as possible to those to be gained during the mission. With such data the processing and analysis programmes will be tested in order to assess the instrument capabilities and limits. As an example we have simulated the realization of a spectral and spatial map of the sky region with the outflow of L1551-IRS5. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.     

On some generalizations of the radical of an ideal and the radical of a submodule

In the paper, the notions of radical of an ideal and radical of a submodule are generalized and described.     

Vibrations of elastic string with nonhomogeneous material

In this paper we analyze from the mathematical point of view a model for small vertical vibrations of an elastic string with fixed ends and the density of the material being not constant. We employ techniques of functional analysis, mainly a theorem of compactness for the analysis of the approximation of Faedo-Galerkin method. We obtain strong global solutions with restrictions on the initial data u₀ and u₁, uniqueness of solutions and a rate decay estimate for the energy.     

Inverse coefficient problem for a wave equation in a bounded domain

The nonlinear inverse problem for a wave equation is investigated in a three-dimensional bounded domain subject to the Dirichlet boundary condition. Given a family of solutions to the equation defined on a closed surface within the original domain, it is required to reconstruct the coefficient determining the velocity of sound in the medium. The solutions used for this purpose correspond to the acoustic medium perturbations localized in the neighborhood of a certain closed surface. The inverse problem is reduced to a linear integral equation of the first kind, and the uniqueness of the solution to this equation is established. Numerical results are presented.     

On Left Regular Ordered Semigroups

The main result of the paper is a decomposition theorem of the left regular ordered semigroups into left regular and left simple semigroups.