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  • Mathematical modeling of the stress-strain state of an elastic mass near a spherical cavity taking into account the technological heterogeneity of its mechanical properties

    It is considered a centrally symmetric stress-strain state of the rock mass near the underground spherical cavity taking into account the technological heterogeneity of the rocks of the near-edge region. The mathematical model was developed and analytical solutions were found for this problem. The technological heterogeneity of the elastic properties of the rock mass material was modeled by a radially inhomogeneous coefficient of elasticity at a constant Poisson's ratio. The variable coefficient of elasticity for heterogeneous rocks was approximated by a generalized polynomial with undetermined coefficients. On the basis of experimental data, a numerical calculation of the stress-strain state components for the problem was carried out, and characteristic effects were detected.

    Keywords: stress-strain state, rock mass with technological heterogeneity, underground spherical cavity, mathematical model

  • Data analysis based on private cloud technology

    The article is devoted to the use of a private cloud for data analysis. Modern cloud technologies can significantly reduce costs, and today many companies are increasingly moving their corporate systems and business applications to the cloud, including the data analysis process. The aim is to analyze the quotations of precious metals for the period from 01/01/2018 to 08/01/2018, taken from the information portal Finam.ru for retail traders. To achieve this goal, the following tasks were set: network virtualization, projection of a private cloud based on Microsoft System Center Virtual Machine Manager 2012, the development of a service for forecasting data on precious metal quotations (gold, silver, platinum, palladium) using a time series algorithm and a decision tree. The subject of research is the technology of the private cloud, use it to deploy the service to analyze the data. In the conclusion the results of the service are shown, the practical use of cloud computing for data analysis is shown. The evaluation of the quality of the constructed models makes it possible to consider it satisfactory from the statistical point of view.

    Keywords: cloud computing, private cloud, data mining, cloud service, virtualization, data analysis, forecasting

  • Development of a model of the process of internal corrosion of pipelines of heating networks

    A dynamic model of the process of internal corrosion of pipelines of heating networks is considered. Model include five level: the level of the wall thickness of the pipeline, the level of slowing down of thinning of the wall of the pipeline from pH, the level of accelerating of thinning of the wall of the pipeline from temperature, the level of accelerating of thinning of the wall of the pipeline from the oxygen concentration, the level of slowing down of thinning of the wall the pipeline from the carbonate index. The composition of variables includes one level of state, thar characterize the process of thinning the wall of the pipeline due to internal corrosion, and four levels, that characterize the performance of network water. Six rates of changing of the physical indicators, that characterize the growth (dynamics) of the ongoing process, are taken into account. Four dependencies of influence are connect the subsystems of the complex into a single whole. The results of the evaluation of the dynamics of the pipe wall thinning process in the process of internal corrosion for a period of 1 year and 5 years presented. The software implementation in the Mathcad environment is considered.

    Keywords: dynamic model, internal corrosion of pipelines, corrosion of the heat network, corrosion factor

  • Quality assessment and improvement of acoustic environment in a classroom

    Assessment of influence of speech intelligibility and reverberation time on the quality of acoustics Determination by theoretical method and computer simulation method of reverberation time in the modern audience and the audience, built more than 10 years ago. Determination of sound absorption coefficients of surface materials in both classrooms. Modernize of classrooms using wood fiber panels to increase sound absorption and reduce reverberation time. As a result, the reverberation time of the upgraded audiences has become less than one at all frequencies. This ensures good speech quality and efficiency of the educational process.

    Keywords: acoustics, classroom acoustics, reverberation time, speech intelligibility, sound absorption coefficient, computer simulation, wood fiber

  • Computer simulation of interaction of silicate and phosphate additives by quantum chemical analysis

    This paper presents two methods of computer simulation (quantum chemical analysis and molecular dynamics) of the interaction of additives with the iron surface. Quantum chemical interaction of silicate and phosphate additives with iron surface was carried out. The plate model was used for quantum chemical analysis, calculations were carried out in the DFT approximation. The method of molecular dynamics is based on the calculation of the evolution of the system of interacting particles of atoms and molecules by integrating the equations of their motion. It is shown that the oxidation of the surface leads to a decrease in the adhesion energy of both individual additives and their combinations, allowing to find the influencing factors on the behavior of tribosystems.

    Keywords: lubricant, method, quantum chemical analysis, molecular dynamics, tribology, friction, computer simulation

  • Software implementation of automated annotation of documents

    The article provides an overview of the methods of automatic abstracting and annotating documents. The description of classification of methods of annotation and abstracting on various criteria is presented. The algorithm of automatic annotation is described in detail, the key step of which is the transformation of all words in the text into lemmas (lemmatization). The developed program sets the upper limit of the output annotation in order to avoid receiving the abstract instead of the annotation.

    Keywords: annotation, abstracting, lemmatization, algorithm, software implementation, database, text analysis

  • Regression model of the ice coverage of the White Sea

    The paper describes the regression model of the change in the ice coverage of the White Sea, obtained on the basis of satellite data of NSIDC. Changes in the ice coverage of the White Sea are mathematically described by a polynomial of the 6th degree, the quality of which is characterized by a coefficient of determination of 0.78. On the basis of the obtained mathematical model, the terms and duration of the phases of the ice regime of the White Sea are established, and also the analysis of the rate of formation and destruction of ice formations is given.

    Keywords: ice coverage, ice phenomena, regression model, White Sea, satellite data of NSIDC

  • A synergistic method for the control crawler platform

    The problem of synthesis of the speed regulation law and the angle of rotation of a crawler platform with DC electric drives in a nondeterministic medium is discussed. The solution of the task is achieved by using a synergetic controller with a hierarchical control principle. The crawler platform control is considered on the basis of the mathematical model of platform motion and electric drives

    Keywords: synergetic control theory, ACAR method, hierarchical method, integral adaptation, crawler platform, DC electric drive

  • Mathematical description of dispersed flows of inhomogeneous liquids

    The article deals with the issues of dispersion of heterogeneous liquids by spray nozzles in order to divide them into components. The influence of various parameters on the size of the droplets obtained is investigated. For the mathematical description the probabilistic approach is applied, which allows to obtain a differential function of the particle size distribution, which can form the basis of the engineering method of calculation of this class of separators. An expression for determining the average value of the angular velocity of the internal flow is compiled. These dependences allow us to calculate the most probable value of the angular velocity corresponding to the decay of complex drops into secondary ones, which are the drops of the initial liquids.

    Keywords: particle, emulsion, non-uniform liquid, droplets, jet, nozzle, velocity, flow, parameter, separator

  • The planned experiment in determining the characteristics of field-effect transistors

    With the help of the previously developed application Plex, automation of planning and conducting multifactor experiments in the study of the characteristics of field-effect transistors was performed. The regression and dispersion analysis of experimental data is carried out, the quality of regression models is estimated, the influence of the number of initial experimental points on the quality of regression models is investigated. The application increases the efficiency of research related to field experiments in determining the characteristics of field-effect transistors, as it makes it possible to reduce the number of required experiments, to automate the processes of storage, extraction and processing of information.

    Keywords: planning, factor, experiment, field (unipolar) transistor, application, regression, dispersion, prediction, approximation, simulation

  • Analysis of the energy-output ratio of production process of wood fuel from waste wood

    It is proposed to use energy efficiency as a criterion for optimizing of wood fuel production when comparing different technologies with the help of simulation modeling. The results of the calculation of the specific consumption of energy resources per unit of produced fuel chips are considered under the processing technologies under consideration. The costs of energy resources are taken into account starting from the stage of harvesting of low quality fuel wood in the cutting area, ending with shipment of fuel chips to the consumer. The energy efficiency of the considered technological process for the production of fuel chips with the help of a system of machines consisting of an feller buncher, a mobile wood chipper and a chip transport machine accounted for 93.76% with a chip transport distance of 50 km, the energy intensity of the product was 7.949 tons of fuel equivalent for 1 thousand dense cubic meters of fuel chips. The offered technique allows to make the comparative estimation of power efficiency of various technologies of manufacture of fuel chips.

    Keywords: fuel chips, production technique of wood fuel, optimization criterion, energy-output ratio, energy efficiency

  • Technology of polynomial fragmentary regression description of experimental data in the "Cut-Glue" method of approximation

    The methodology of regression mathematical description of fragments of experimental data of arbitrary dimension by polynomials necessary for a given accuracy of order and structure is considered with the help of a hybrid of classical regression analysis and a modified evolutionary genetic algorithm through which the polynomial structure is varied and optimized.

    Keywords: optimization, approximation, regression analysis, mathematical model, experimental data, heuristic methods, evolutionary-genetic algorithm

  • Methods for processing navigation information in order to improve accuracy

    The article is devoted to the research of methods of processing of navigation information. To collect experimental navigation information, a system based on the Real time locating system was used, which includes 9 receivers and one label. Label positioning takes place by measuring the distance from the label to the receivers (at least 3). Measurements were made at 9 points on the test polygon to determine the point with the highest standard deviation (STD). However, there is no relationship between the position of the point and the STD. As a result, data sets of navigational information were received, which are subject to further processing. The standard deviation of the navigation system is calculated. The methods of linear filtration are studied: a median filter, a moving average filter and a Wiener filter. Their effectiveness was assessed from the point of view of the reduction of STD. The algorithms of each of the filters are presented. Shown are graphs showing the smoothing properties of the filters. The general properties of the pros and cons of each filter are given. The STD is calculated after applying different filters. Conclusions are given about the most effective filter from the point of view of the STD. It turned out to be a moving average filter. However, the decrease in STD was not significant. Conclusions are drawn about the need to integrate navigation information from various sources.

    Keywords: navigation, positioning, data filter, linear filter, moving average filter, median filter, Wiener filter, mobile objects control, navigation information processing, standard deviation

  • Numerical study of the heat sink with a change in the aggregate state of the working substance

    In the article, a numerical study of the heat sink with a change in the aggregate state of the oil is carried out. Simulation was carried out in Ansys Fluent CAD for two modes, static - with constant heating of the oil at 340K and dynamic, at which the heating temperature varied with time from 340K to 270K. Heat transfer in the event of a change in the aggregate state of a substance is widely used in cases where it is necessary to achieve the maximum efficiency of heat exchange. In this case, the energy is expended on the phase transition of the substance, for example, to evaporation from the liquid phase. The advantage of the heat-sink design described in this work is a rather high rate of heat transfer, greater resistance to various influences, including mechanical ones, which is primarily ensured by the simplicity of construction, eliminating the drawbacks of classical designs, which are cumbersome (the presence of an external cooling circuit ) and the limited rate of heat transfer.

    Keywords: heat dissipation, numerical methods, aggregate state, computational experiment, heat exchange efficiency

  • Investigation of the efficiency of the pin heat sink by numerical methods

    In the article, the authors carried out a computer experiment in Ansys Fluent CAD to study the efficiency of a heat sink surface in terms of reducing the temperature of a heat-loaded source. Providing optimal thermal conditions for electronic products is one of the most important problems in the design of radio electronic equipment. Increasing the temperature of electronic products significantly reduces the reliability of their work. The work is devoted to numerical modeling of the heat sink surface efficiency of a pin radiator with an internal heat source. A conclusion is drawn about the ineffectiveness of performing a heat sink pin surface, not the entire surface is equally effective.

    Keywords: thermal mode of equipment, pin heat sink, numerical methods, aerodynamic flow

  • A method for improving the convergence of a single-center decomposition of a molecular orbital

    Investigation of the interaction of electromagnetic radiation with molecular systems gives most of the information about their structure and properties. Interpretation of experimental data is directly determined by the knowledge of the structure of energy levels and its change in the transition of these systems to an excited state. A key task of the methods for calculating the molecular orbitals of excited states is to accurately describe the emerging vacancies of the molecular core, leading to radial relaxation of the electron density. A method is proposed for an exact description of the electron density of a molecular system near its nuclei, which provides solutions to the problem of slow convergence of molecular orbitals in a single-center representation. The implementation of the computational procedure is examined using the example of a diatomic hydrogen fluoride molecule. The energy characteristics of the ground and ionized states of the molecule are estimated

    Keywords: single-center method, molecular orbital, excited state, ionized state, deep shell

  • Application of the optical heterodyning method for receiving L-band signals

    In this paper, we consider the application of the optical heterodyning method for signal processing of a receiving device. The simulation of the developed scheme was carried out in the environment of OptiSystem. Also presented are the results of modeling, explaining the principle of operation of this scheme.

    Keywords: optical heterodyning, radio frequency, L-band, signal spectrum

  • The technique of calculating the matrix elements of spectroscopic quantities for complex atomic configurations

    The paper presents an overview of the existing calculation schemes and the technique for obtaining the angular parts of the matrix elements of the spectroscopic quantities operators with the discussion of cases of complex electron configurations containing nonequivalent electrons. Using the example of a configuration with four unfilled electronic shells, the high efficiency of the technique for constructing wave functions of arbitrary electronic configurations is shown, based on a combination of Slater's determinant approach and the procedure for sequential coupling of orbital and spin moments on the basis of the Clebsch-Gordan coefficients in the LS coupling approximation.

    Keywords: Slater determinant, Clebsch-Gordan coefficient, orbital angular momentum, spin moment, 3j-symbol, coefficients of fractional parentage, LS-coupling

  • Application of parametric design in finite element modeling

    The method of parametric modeling and design based on the example of a building is studied, the architectural image of which is a set of circular helical and cylindrical surfaces defined by coordinates through functions of the corresponding surfaces in the SAPPHIRE software. Alternative methods for specifying surfaces in the SAPPHIRE PC, AutoCAD with subsequent export to the LIRA PC for engineering calculations of the frame of the building for various combinations of loads by the finite element method are presented. The object of the study is a 360-meter-high building with a hardness core in the form of a cylindrical shell of revolution. The height of the floor is 3 m. Around the rigid shell there are three circular helical surfaces that "rise" in a spiral upward along with the core of rigidity to a mark of 360 meters from the level of the ground floor. One of the most universal ways to create a surface is to specify it through a formula, because you can easily change the shape and appearance of the surface without manually editing the geometry of the model in the drawing. The development of the parametric architecture calls for the creation of new approaches to the calculation of unique buildings and structures, the improvement of software complexes that implement the finite element method, and the appearance of new varieties of finite elements with curvilinear boundaries.

    Keywords: parametric architecture, surface, shape of the object, shell, curve, model, geometry, program, formula surface, helical surface

  • Modeling housing ball joint passenger car

    The compare the durability of the existing ball bearings (SHO) with the polymer homogeneous element with the durability of the modified supports, a cell model with the averaged placement of the modifier in SHO substrate and a model for bringing the multilayer sho body to the equivalent single-layer one are constructed; calculations of contact pressure, contact deformations and stresses are performed. The calculation takes into account the rheological and physico-chemical properties of the components of SHO substrate and modifier, the influence of the environment. As a result of calculations, it was found that at all points of the contour the material experiences a biaxial plane two-dimensional stress state, called pure shear with the presence of shear stresses. The most intense point of danger is the point lying in the center of the platform of contact of details.

    Keywords: ball bearing, durability, modeling, polymer material, granule, modification

  • Method of estimation of protection of mobile ground objects from technical means of observation of the opponent in conditions of the Arctic

    The method of estimation of protection of mobile ground objects from technical means of observation of the opponent in conditions of the Arctic, executed with application of methods of the theory of simulation, the theory of random impulse streams and the theory of recognition of images is presented

    Keywords: Security, probability, movable ground object, the technical means of surveillance, weapons and military equipment, simulation, pulse flows, the recognition, the telltale signs

  • Mathematical modeling of the magnetic field distribution in the vicinity of the erythrocyte

    Erythrocyte, when moving through a narrow capillary, stretches out and rolls like a tractor's caterpillar. Charges located on the surface of the erythrocyte, move together with the membrane and generate a magnetic field in the vicinity of the erythrocyte membrane, which can affect both elements of blood flow outside the erythrocyte, and its contents, in particular, the iron atoms that make up the hemoglobin. A three-dimensional model of the erythrocyte is constructed. The shape of the erythrocyte is approximated by a truncated cylinder of radius r with generators L1 and L2. It is assumed that all charges on the surface of the erythrocyte are the same and evenly distributed over the surface of the erythrocyte. Charges move along with the membrane along closed curves (trapezoids). Moving charge creates a magnetic field, the strength of which depends on the magnitude and speed of the charge. On the erythrocyte membrane there are several charges and each of them at some selected point creates a magnetic field. The total strength of the magnetic field is defined as the vector sum of the strains created by each of the charges. The following parameter values ​​were used in the calculations. The charge of the erythrocyte is 20 million elementary charges. The number of charges on the erythrocyte membrane is 38594. The rotation frequency of the erythrocyte membrane is 20 revolutions per second. The erythrocyte radius is 2 μm. The erythrocyte volume is 94 μm3. The erythrocyte surface area is 135 μm2, the lengths of the truncated cylinder forming are 3.4 μm and 11.5 μm. The erythrocyte speed is 100 μm / sec. The step along the space is 0.1 μm. The performed calculations of the magnetic field strength H have shown that the rotation of the erythrocyte membrane with the charges placed on it leads to a significant redistribution of the magnetic field in the vicinity of the erythrocyte. And with an increase in the frequency of rotation of the erythrocyte membrane, the heterogeneity of H increases significantly and can lead to a change in hemodynamics in the microcirculation system.

    Keywords: mathematical model, erythrocyte, narrow capillary, magnetic field, microcirculation

  • On one method of solving the operational planning problem on a situational network

    In this paper, we consider the task of constructing a work plan in the form of a chain of control actions that change the system, and methods for solving it. The problem of finding the optimal path on the situational network is constructed with a mathematical description of the initial conditions and the requirements for the result. Briefly describes the standard solution of this problem: the method of fuzzy products. The main problems of the fuzzy product method are considered. The solution of the task of constructing the chain of actions of an operator on a situational network using the dynamic programming mechanism is described. A combined method is proposed for finding chains of actions with procedural construction of a situational network using the dynamic programming method with constraints. The first step and step l of the algorithm for solving this problem are described. The advantages of this method over other.

    Keywords: situational modeling, fuzzy sets, graph theory, decision theory, documentation, complex systems, fuzzy logic, fuzzy situation networks, set theory, optimal control theory, dynamic programming

  • Application of methods of data mining in the development of the system of classification of students' competencies for the university web-site

    The article is devoted to the problem of using artificial neural networks as one of the methods of data mining (intellectual data analysis) for classifying the competencies of university students when determining the educational specialization. It describes the complexity of the process of selecting specialization and the associated negative consequences, as well as an approach to solving the given problem using software classification tools. As a basis for the implementation of the proposed tools, the student's information system is used on the website of the University of Tartus, Syria. The article presents data selection criteria to form the training sample, which includes the academic performance in some courses as input vectors. The values of the output vector depend on completed specialization and it get into the training set only if it is properly selected. On the basis of these data, the structure of a multilayer artificial neural network is formed and the learning algorithm is selected, the results of which are reflected on the university's website in the form of advice on the choice of future specialization, which has allowed increase the effectiveness of the educational process.

    Keywords: Data mining, artificial neural network, web-design, machine learning, classification

  • Simulation of the design activity diversification of innovative enterprise

    The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, the organizations of the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.

    Keywords: differential equations, perfect mixing cell, dynamics, model, material balance, state of equilibrium, nonstationary process