On a Powder Consolidation Problem
The problem of the consolidation of an aerated fine powder under gravity is considered. The industrial relevance of the problem is discussed and a mathematical model is introduced. The mathematical structure is that of a coupled system for three unknowns, pressure, stress, and height of the powder in the (axisymmetric) bunker containing it. The system itself consists of a parabolic PDE, an ODE, and an integral equation determining a free boundary corresponding to the height of the powder. Existence and uniqueness of a solution is established. A numerical method based on a formulation of the semidiscretized problem as an index 1 DAE is proposed and implemented. The feasibility of the approach is illustrated by computational results.
A general nonlinear mathematical model for soil consolidation problems
This paper presents a three-dimensional consolidation model, based on mixture theory. Both the Eulerian and the Lagrangian formulations are given in one dimension for finite strain and general material nonlinearity. Then the paper formulates the initial boundary value problems related to several situations of relevant geotechnical engineering interest, such as consolidation between draining and impervious boundaries subjected to stress and/or velocity conditions, consolidation under own weight of a layer growing due to deposition of wet material, or to sedimentation of solid particles in a quiescent fluid.
On Hilbert's thirteenth problem and related questions
Hilbert's thirteenth problem involves the study of solutions of algebraic equations. The object is to obtain a complexity estimate for an algebraic function. As of now, the problem remains open. There are only a few partial algebraic results in this connection, but at the same time the problem has stimulated a series of studies in the theory of functions with their subsequent applications. The most brilliant result in this cycle is Kolmogorov's theorem on superpositions of continuous functions.