AGH (Akademia Górniczo-Hutnicza) University of Science and Technology: Journals

    On Evolution of Migrating Population with Two Competing Species

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    Computer experiment study of population evolution and its dynamics  is presented for two competing species A and B which share two habitats (1 and 2) of limited environmental capacity. The Penna model of biological aging,  based on concept of defective mutation accumulation was adopted for migrating population. In this paper we assume and concentrate on the case when only one species A is mobile. For isolated habitats and for any initial population, we get at equilibrium spatial population distribution (A,  B) between the two locations - A occupies location 1 while B-species is present in 2. The effect of migration between habitats is reported  for  some migration   scenarios. With increasing migration we get a sequence (A, B) - (A, AB) - (A, A) - (B, B) distribution. Another scenarios bring different sequences of population distribution, size and characteristics

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    Kronika i informacje

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    A STUDY ON THE DESIGN OF AUXETIC STRUCTURE OF SEAT SKELETON

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    This paper presents numerical study of deformation and stresses in seat skeleton elements subject to static and dynamic pressure loads. Elastic skeleton made of polyamide or elastomer is taken as an example of a seat material. Auxetic type of seat structure ensures the reduction of real contact stresses between human body and seat, making it more comfortable than typical. FEM analysis is performed using ABAQUS system. Numerical calculations are carried out to determine the nonlinear stiffness characteristics of seat springs. The study makes possible the selection of material and structural topology fulfilling design constraints and additional recommendations concerning structural flexibility, stability and optimal reduction of contact stresses. This paper presents an application of the problem

    ORTHOTROPIC YIELD CRITERIA IN A MATERIAL MODEL FOR TIMBER STRUCTURES

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    The continuum structural model for the failure analysis of timber structures in the plane stress state is discussed in the paper. Constitutive relations are established in the framework of the mathematical multi-surface elasto-pla-sticity theory with three orthotropic strength criteria that have been incorporated in the model as the plasticity conditions. The invariant form of the criteria is given based on the representation theory of scalar-valued functions of the orthotropic invariants. The model is implemented into a commercial finite element code by means of user-defined subroutines. Introductory implementation tests of the proposed numerical algorithm are presented in the paper

    MICROSTRUCTURE EVALUATION OF Ni-Mn-Ga ALLOY

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    This paper summarises the applications of MSMA materials, outlines the mechanism of magnetic shape memory effect and provides the procedure for microstructure evaluation of samples as well as the results of microstructure analysis using the example of the Ni-Mn-Ga alloy

    MEASUREMENTS OF SMA PROPERTIES USING ADVANCED OPTICAL METHODS

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    Shape Memory Alloys are called smart or advanced materials because of their special features which are very useful in the latest solutions. Therefore, it is very important to gain a good knowledge of all these features for the purposes of modeling, describing, and ultimately controlling the behavior of these materials. This paper describes how to measure selected properties of SMA. It describes how to measure real temperature and diameter of thin SMA wires. At the end, we use a high speed camera to find out how an SMA wire breaks during stretching

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