IDENTIFICATION OF AN AUTOREGRESSIVE PROCESS USING MATLAB

The article aims to apply the methods of regression analysis in estimation task the reliability indicators of an infocommunication system and data trend forecasting. The task of assessment the reliability indicators of infocommunication systems is based, traditionally, on statistical data, the collection and processing is carried out by monitoring system. To obtain the calculated indicators as close as possible to the real practical results it is necessary to process a large number of measurements. In this sense, the theory of filtration is widely used in various estimation problems. It allows to support the possibility of effective solution of technical issues and implementation through mathematical modeling programs. The article is aimed to consider the issues of data trend forecasting for parameters calculation of infocommunication systems. One of the most effective solutions is the use of regression analysis methods. The research gives development and analysis of mathematical and program models. Based on theoretical calculations, methods for solving the problem are determined and experimental research are carried out. The article solves the problem of identifying an autoregressive process through the Yule-Walker equations. In addition to theoretical calculations, a program has been developed that allows handle the process of calculations in the Matlab environment. As a result, it is proposed to compare the results of identification time series of variables through the Yule-Walker system with the classical parameter estimation by the least squares method. The results are shown graphically.

Theory of filtration in a double porosity medium

This paper defines a generalized mathematical model of filtration in a double porosity medium, taking into ac- count recent ideas on liquid and gas flow in rocks with an anomalously low permeability (including nanoporous rocks). The obtained generalized equation takes into consideration, in contrast to the classical model, the integral effects of direct filtration of an energy (or heat) carrier in low-permeable inclusions. The laws of gas flow variations at the discharge point are compared with the classical double porosity model and with the Boussinesq– Leibenzon model.

PROBLEMS OF NONSTATIONARY FILTRATION

he article deals with the classical hydrodynamic theory of filtration. Discusses models of soil, fluid and nature of fluid flow that formed the basis for the creation of the classic filtration theory. Also discusses the assumptions made for the linearization of the equations. Evaluated the scope of the classical filtration theory. Proposed a new model of filtration through a porous medium, based on the application of the laws of theoretical mechanics. It is based on the classical model of soil: the soil is composed of capillaries with ..parallel axes, in which the liquid moves. For tasks of infiltration equations of motion. Considered special cases of unsteady motion of a finite volume of liquid. Numerical example a machine experiment.

Influence of the aerosol flow and exposure time on the structural changes in the filtering half masks material

The flow of air and aerosol particles through the filtering half masks material depends on the structure porosity. It is very difficult to determine the behaviour of the filtering material during the process of extraction and retention of aerosols. The samples of five filtering half mask models were used in this investigation. Dynamics of the aerosol filtration through the filtering materials was tested using a method for testing the leakage of aerosol particles through the filtering material and a method for testing the inhalation resistance of filtering material, both specified in the SRPS EN 149:2013. Recording of the structural changes in the samples of the tested materials was carried out by the technique of scanning electron microscopy. The experiments showed a deviation of the results in relation to the theory of filtration the finely dispersed submicron sized particles. It was concluded that the aerosol leakage through the filtering half masks and their resistance to aerosol flow change depend on the aerosol flow rates and the on filtration process duration, as a direct consequence of the newly-made changes in the structure of the filtering material and due to reversibility effect between the filtration process and the changes in the filtering material.

Estimation of Filtration Efficiency – from Simple Correlations to Digital Fluid Dynamics

Aerosol filtration in fibrous filters is one of the principal methods of accurate removal of particulate matter from a stream of gas. The classical theory of depth filtration of aerosol particles in fibrous structures is based on the assumption of existing single fibre efficiency, which may be used to recalculate the overall efficiency of entire filter. Using “classical theory” of filtration one may introduce some errors, leading finally to a discrepancy between theory and experiment. There are several reasons for inappropriate estimation of the single fibre efficiency: i) neglecting of shortrange interactions, ii) separation of inertial and Brownian effects, ii) perfect adhesion of particles to the fibre, iv) assumption of perfect mixing of aerosol particles in the gas stream, v) assumption of negligible effect of the presence of neighbouring fibres and vi) assumption of perpendicular orientation of homogenous fibres in the filtration structure. Generally speaking, “classical theory” of filtration was used for characterization of the steady - state filtration process (filtration in a clean filter, at the beginning of the process) without deeper investigation of the influence of the nternal structure of the filter on its performance. The aim of this review is to outline and discuss the progress of deep-bed filtration modelling from the use of simple empirical correlations to advanced techniques of Computational Fluid Dynamics and Digital Fluid Dynamics.