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The paper introduces a stochastic model for a class of population-based global optimization meta-heuristics, that generalizes existing models in the following ways. First of all, an individual becomes an active software agent characterized by the constant genotype and the meme that may change during the optimization process. Second, the model embraces the asynchronous processing of agent’s actions...
This paper presents the research on optimization of the splicing process in the electric arc of telecommunication optical fibers and erbium doped EDF fibers. The results of the calculations of diffusion coefficients GeO2 in telecommunication optical fibers and diffusion coefficients Er and Al2O3 (together) in the fiber EDF are presented. Diffusion coefficients were determined for the fusion temperature...
The paper reports on the medium wavelength infrared (MWIR) unipolar barrier infrared detector (UBIRD) nBn/B-n type (n-type barrier) HgCdTe detector’s photoelectrical performance. The UBIRD nBn/B-n type HgCdTe detector was modelled using commercially available software APSYS. Detailed analysis of the detector’s performance (such as dark current, photocurrent, responsivity, and detectivity) versus bias...
Conditions for the existence of positive and asymptotically stable realizations for descriptor discrete-time linear systems are established. Procedures for computation of positive and asymptotically stable realizations for improper transfer matrices are proposed. The effectiveness of the methods is demonstrated on numerical examples.
The process of design of building composites, like concrete is a complex one and involves many aspects like physical and mechanical properties, durability, shielding efficiency, costs of production and dismantlement etc. There are plenty of parameters to optimize and computer tools can help to choose the best solution. A computer aided design plays an important role nowadays. It becomes more accurate,...
We present a new version of the Athena code, which solves magnetohydrodynamic equations in two-dimensional space. This new implementation, which we have named Athena-GPU, uses CUDA architecture to allow the code execution on Graphical Processor Unit (GPU). The Athena-GPU code is an unofficial, modified version of the Athena code which was originally designed for Central Processor Unit (CPU) architecture...
The paper addresses the problems of the sensitivity analysis and optimal design of multi-span sandwich panels with a soft core and flat thin steel facings. The response functional is formulated in a general form allowing wide practical applications. Sensitivity gradients of this functional with respect to dimensional, material and support parameters are derived using adjoint variable method. These...
Self-repairing means ability to the total or partial recovering of the properties which were worsened as a consequence of damage of the material. The subject of the paper is evaluation of ability to self-repair of a cement composite modified with epoxy resin without a hardener. The methodology of investigation of self-repairing building materials, developed by the authors, has been described, with...
The Riemann-Liouville, Caputo and Gr¨unwald-Letnikov fractional order difference operators are discussed and used to state and solve the controllability problem of a nonlinear fractional order discrete-time system. It is shown that independently of the type of fractional order difference, such a system is locally controllable in q steps if its linear approximation is globally controllable in q steps.
The paper deals with information concerning properties and technology of a new generation cementitious composite i.e. Ultra-High Performance Concrete. High performance here means both high strength and high durability under the influence of environmental factors. This group of composites is mainly represented by Reactive Powder Concretes (RPC), which show both outstanding durability and mechanical...
The paper presents an idea of predicting durability of concrete structures with steel reinforcement under conditions of chloride and carbonation corrosion risk. Mechanisms of destruction due to steel corrosion in such conditions are shown. The recently elaborated model of carbonation and general model of chloride diffusion have been discussed. An algorithm of the rest service life time prognosis has...
In the paper linear distributed delay stochastic systems are considered. Using theory of stochastic differential equations sufficient conditions for different kinds of stability are formulated and proved. The article attempts to generalise results presented in the paper [1] and thus theorems proved in [1] become a special case of a generalised approach. The considered class is wider - the function...
The aim of this paper is to present the application of Computational Fluid Dynamics (CFD) to the assessment of conditions inside construction works during a fire. The CFD method is now commonly used to support the design process of fire safety in construction works. This method is very useful at the preliminary stage of design because it is possible to check the internal environment during a fire...
The paper presents the impact of high temperature on cement concrete. The presented data have been selected both from the author’s most recent research and the published literature in order to provide a brief outline of the subject. The effect of a high temperature on concrete covers changes taking place in cement paste, aggregates, as well as the interaction of these two constituents, that result...
Load and resistance have to be treated as random variables because of natural and man-made uncertainties. Statistical parameters, i.e. bias factors and coefficients of variation, are presented for natural effects of dead load, live load for buildings and bridges, and environmental loads. Man-made effects are more difficult to quantify as they include also human errors. For resistance, the uncertainties...
This paper presents an application of the grid convergence index (GCI) concept based on the Richardson extrapolation to a selected simple problem of a cantilever beam loaded with vertical forces at the tip end. The GCI method, popular in computational fluid dynamics, has been recently recommended for finite element (FE) applications in solid and structural mechanics. Based on the results obtained...
The paper considers the failure study of concrete structures loaded by the pressure wave due to detonation of an explosive material. In the paper two numerical methods are used and their efficiency and accuracy are compared. There are the Smoothed Particle Hydrodynamics (SPH) and the Finite Element Method (FEM). The numerical examples take into account the dynamic behaviour of concrete slab or a structure...
The procedure of the formulation of constitutive equations for asphalt-aggregate mixes is based very often on rheological schemes composed of classical elastic, plastic and viscous elements. The parameters of these schemes can be obtained based on laboratory experiments. In order to obtain better curve fitting results one can use non-classical viscoelastic elements described by fractional derivatives...
In this paper, a global monitoring system based on the measurement of acoustic emission (AE) due to active deterioration processes is presented. This allows us to examine the entire volume of an element and to locate and identify the type and the dynamics of the deterioration processes under service conditions. The resulting data are used to determine and locate the damage processes that are dangerous...
Different methods of quantitative assessment of structural robustness has been proposed and widely discussed in recent years. This paper starts out with an outline of the requirements and discussion of the conventional and risk based methods and measures of structural robustness. The probability and consequence analysis related to the assessment of robustness usually contains the statistical, fuzzy...
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