high purity fluorapatite (fa) with rod-like and spherical-like morphology was synthesized via sol-gel method. chemical characterization of fa powders was done by xrd and ftir analyses. crystallite samples were calculated using scherer method. morphology of fa powders was investigated with tem and sem images. the results revealed that increasing the time of hydrolysis of phosphate sols significa...

A matrix map F (x) is said to be (matricially) convex, if u T F (x)u is a convex function for every u. In this paper, semideenite systems of the type F (x) 0, where F (x) is ma-tricially convex, are considered. This class of problems generalizes both aane semideenite inequalities as well as ordinary convex inequality systems. After establishing characterizations and properties of matricial conv...

The Sznajd model in less than a year has found several followers. An isolated person does not convince others; a group of people sharing the same opinions influences the neighbours much more easily. Thus on a square lattice, with variables +1 (Democrats) and –1 (Republicans) on every lattice site, a pair (or plaquette) of neighbours convinces its six (eight) nearest neighbours of its own opinio...

This paper is concerned with the approximate solution of a functional differential equation of the form: x′(t) = α(t)x(t)+β (t)x(t−1)+ γ(t)x(t +1). (1) We search for a solution x, defined for t ∈ [−1,k],(k ∈ IN), which takes given values on the intervals [−1,0] and (k− 1,k]. Continuing the work started in [10], we introduce and analyse some new computational methods for the solution of this pro...

The renormalization of a quadratic-like map is studied. The threedimensional Yoccoz puzzle for an infinitely renormalizable quadratic-like map is discussed. For an unbranched quadratic-like map having the a priori complex bounds, the local connectivity of its Julia set is proved by using the three-dimensional Yoccoz puzzle. The generalized version of Sullivan’s sector theorem is discussed and i...

The tetrahedral finite element approximation of the Stokes problem is analyzed by means of polynomials piecewise of degree k +1 for the velocity and continuous piecewise of degree k for the pressure. A stability result is given for every k ≥ 1.

We discuss a new method for the iterative computation of a portion of the singular values and vectors of a large sparse matrix. Similar to the Jacobi-Davidson method for the eigenvalue problem, we compute in each step a correction by (approximately) solving a correction equation. It is shown that this JDSVD method can be seen as an accelerated (inexact) Newton scheme. We compare the method with...