The article discusses the use of mathematical modeling of the transmission of a car in the Simulink environment. Studies of the influence of individual transmission factors on the functional parameters of the KAMAZ 4308 car have been carried out. Differential equations describing the operation of the transmission are solved in a matrix way, allowing to study the dynamics of the car taking into account the moments of inertia of the engine, transmission and individual wheels of the car.
Keywords: transmission, wheeled vehicle, clutch, differential, gear ratio, simulation, maximum speed
The mathematical model of coordination of private and public interests in the implementation of innovations in the case of multiple agents is studied. It is taken into account the presence of two management levels, that are several agents and the supervisor.The relationship between the supervisor and the agents is designed hierarchically in accordance with the information regulations of the Stackelberg games. Two mehods, simulation modeling and the method of qualitatively representative scenarios (QRS), are used to construct Stackelberg equilibria. Numerical experiments have been carried out using these two methods. The analysis of the obtained results is given.
Keywords: Stackelberg game, simulation modeling, method of qualitatively representative scenarios (QRS), supervisor, agents
This paper presents a mathematical model and a geometric method of image-based object classification intended to improve the accuracy of object classification by filtering out noise objects.
Keywords: image processing, object recognition, pattern recognition, object identification, classification
At present, various software systems are widely used to carry out researches in the field of technology, make it possible to create mathematical models of real objects. Their further study allows to obtain a large amount of calculated data necessary for units’ design, resource assessment and performance of the object under study. This makes it possible to significantly reduce the conduct of experimental studies of real objects, as well as to obtain additional data that characterize specific parts during operation, such as the values of internal stresses, natural vibration frequencies, data on strength, fatigue, etc. However, during the process of real objects models creating, not always all the necessary data is available. In this regard, it is necessary to carry out research with some real details. To determine the material hardness of the rotor shaft of the turbocharger at different depths from the shaft surface, special new samples were made. Next, the microhardness of the material was determined. The hardness of the material from the surface decreases and at a depth of 1 mm becomes equal to the hardness of the unhardened one. After research finishing, a geometric model of the rotor shaft is created. The model is created using the SolidWorks Simulation complex. The working part of the shaft model consists of two layers: the first one is the surface with increased hardness and 1 mm thick; the second one is internal unhardened. This model is used in the research and development of technological processes for the repair of the part.
Keywords: software package, mathematical model, static analysis, rotor shaft, hardening, hardness, sample, depth, surface layer, repair
Porous media can be used as heat transfer intensifiers in the petrochemical, refrigeration, food, energy, and other industries. In this paper, heat transfer in a porous medium with a pulsating flow is studied numerically. The simulation was carried out in the AnsysFluent software product. The porous medium was represented as a two-dimensional channel with square tubes. The working medium was air and water. The heat transfer and hydraulic resistance of a porous medium in a pulsating flow are determined for different porosity and fiber diameter depending on the Reynolds number, Prandtl number, frequency and amplitude of pulsations. It is shown that with an increase in the intensity of pulsations, an increase in heat transfer occurs. Heat transfer intensification essentially depends on regime and geometrical parameters. Several empirical correlation are proposed for calculating heat transfer and the degree of heat transfer intensification for symmetric and asymmetric flow pulsations. The thermal-hydraulic efficiency is determined for the same Reynolds numbers and powers for pumping the heat carrier in a porous medium with symmetric and asymmetric flow pulsations.
Keywords: heat transfer, pulsation flow, porous media, mathematical modeling, thermal-hydraulic efficiency
the article analyzes the economic instruments used by states in domestic and foreign policy from the point of view of identifying the existing coercive mechanisms in modern social practices. The study revealed how states use economic instruments as the preferred means of geopolitical struggle. In addition, the work separately reflects the fact that States should preserve the right to an original socio-economic model of development. We should also not forget about the negative consequences of unilateral coercive measures. Using the method of cognitive modeling and constructing cognitive maps, the authors identify the connections in the analyzed social practices from the perspective of studying the means of geo-economic pressure.
Keywords: cyberwarfare, cyberattacks, cybersecurity risks, communication networks, transport systems, tactical, operational and strategic initiatives
The paper presents analytical estimates of the proximity of solutions to boundary value problems for elastic-creeping layered composite materials widely used in technology under long-term loading, and also gives the corresponding averaged model for such materials. The estimates show the possibility of using the averaged model over a long time interval for the problem of loading by a constantly acting force. Previously, this statement was confirmed by numerical experiments comparing solutions of boundary value problems for an effective (averaged) model and direct numerical calculation using the original model for a highly inhomogeneous layered material. Analytical estimates are based on previously obtained estimates of the proximity of solutions to stationary problems of elasticity theory. For the one-dimensional model considered in this work, the following property is established: if the constitutive relations for various phases of the composite material are written as dependences of deformations on stresses, then the coefficients for the same form of writing the constitutive relations of the averaged model are obtained as simple weighted average values of similar coefficients for individual phases.
Keywords: layered composite materials, creep theory, averaging method, evaluating the efficiency of the averaging method, asymptotically long time interval
The article describes the simulation in the Simulink environment of the operation of a stepper motor used as an electric drive of the scanning mechanism for the Earth orientation device. The purpose of the study is to determine the minimum power consumption in each range of values for inductance and resistance. If the model is found to be inoperable above certain values of the specified parameters, the measurement range narrows to an area where there is enough energy to properly work out a given angle. The simulation is based on the parameters of NEMA17 engines, in particular, NEMA 17HS3410. Voltage control in the system is carried out by means of a PI controller, the influence of the regulator on the energy consumption of the system is shown. The regularities of the formation of angular velocity of various amplitudes when working out a turn in open and closed control systems are noted. The range of electrical parameters at which the engine operates with almost the same power consumption is determined. The lowest power values at which the engine is operable are found. The results of the work are visualized in the form of three-dimensional surfaces, recommendations for the continuation of research are developed.
Keywords: stepper motor, simulation, Earth orientation device, power consumption
The paper presents the results of a study aimed at selecting a safe depth of an underground collector. In the scientific and normative literature there are no specific recommendations for the depth of tunneling through the existing highways. There are only recommendations for tunneling through railway embankments. Purpose of this study: scientifically substantiated recommendations for the use of reinforced concrete pipes as collector cases. The decision of problems for achievement of the objective will be carried out by means of numerical experiment - a method of finite elements.
Keywords: reinforced concrete case, underground collector, safe depth, mathematical modeling, case structures, highway, closed method of work, trenchless laying, finite element method, subsidence trough
Refrigerating machines are designed to cover peak heat generation in public buildings. At the same time, peak loads are often short-term and most of the time the refrigerating machines operate at 40-60% of their maximum capacity. The article deals with the issues of uneven cold consumption on the example of a sports complex located in Volgograd. When designing the air conditioning system of the games hall, a cooling system with the use of "chiller-fan coils"is used. An effective solution to reduce costs is to include a cold storage battery in the cooling station circuit. The use of a cold storage battery allows you to reduce operating costs.
Keywords: cooling system, air conditioning system, refrigeration machine, cold storage, energy consumption, peak loads, variable energy consumption
The article proposes a method for assessing the risk of a possible stay of an automated special-purpose information system in a critical state, based on the synthesis of two heterogeneous mathematical models, one of which allows taking into account the intensity of DDOS attacks and the intensity of application processing, based on Markov processes, and the second is one of the forms of a formal description of protection systems, with complete overlap, in which the interaction of the "threat area", "protected area" is considered – areas of resources of an automated information system for special purposes, and "protection systems" – security mechanisms of an automated information system. The developed method makes it possible to simulate the information security tools included in the automated information system for special purposes, under the influence of DDOS attacks, taking into account both the empirical values obtained as a result of measurements or modeling, and the theoretical base of parameters specified by input data. In the synthesis of the two models, the lack of uncertainty of some of the input parameters, taking into account the values based on expert estimates, was eliminated.
Keywords: automated information system, security assessment, queuing system, risk
This article discusses the importance of timely defect detecting of automated electronic car control systems for prevention of serious failures. Also the first stage of mathematic modeling mechanism is presented, it includes construction models of the dependence of the number of failures by time with various methods of diagnosting the technical condition of the car.
Keywords: diagnosting, modeling, technical service of the car, failure, automated system, electronic control unit, engine
A brief analysis of the previously proposed indexes for assessing the publication activity of the authors is presented. Their shortcomings and low information content and reliability are shown.
Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production
The article is devoted to the use of artificial intelligence tools to solve technical problems in the construction industry. It is noted that the use of neural networks will allow taking into account the behavior of materials in various experimental conditions. The authors present a comparative analysis of approaches to neural network training, in particular, the structures of multilayer and LSTM networks are considered. It is established that LSTM networks are more effective in solving problems of identification properties of materials.
Keywords: neural network, non-destructive testing, identification task, multilayer network, LSTM network, impact indentation, indentation, strength properties of materials, neural network technologies, statistical distribution
This article analyzes the calculated fire curve in accordance with the ignition heat source in the compartment. To predict the calculated fire curve, the exponential equation proposed in the previous study was compared with the heat release rate measured in a fire experiment. The lag index, which is the main factor used to predict the time it will take to reach the maximum heat release rate, has decreased in proportion to the ignition heat source.
Keywords: fire calculation curve, pipe insulation, ignition heat source, deceleration index, heat release rate
In this article, we investigate the effectiveness of using multiple pipes for heat dissipation. The study assumes laminar flow under steady-state conditions. Various mixtures are numerically investigated at different flow rates. Various nanofluids flowing through multiple parallel pipes have been numerically investigated to study the effects of temperature rise. Thanks to the benefits they bring to the cooling process, nanofluids have opened up a new way to improve the performance of thermal systems. A typical nanofluid consists of a base fluid, which is usually water, and nanoparticles.
Keywords: heat exchanger, flow tube, nanofluid, bottom heating, coefficient of friction, pressure drop
The article studies the dependence of the temperature of a heat-loaded element of microelectronics on the parameters of the shape of the heat-removing body. Numerical modeling of the study of the efficiency of the heat-removing surface in terms of reducing the source temperature was carried out in the Ansys Fluent CAD system. The advantage of the heat sink design described in the work is considered to be a fairly high intensity of heat removal from the thermally active region and a small weight, which is provided by the simplicity of the heat sink system and the increased heat transfer rate, which makes it economically advantageous to calculate the use of material and time costs for the manufacture of the product. The increased temperature of electronic equipment elements significantly affects the reliability of their operation. In this paper, the task is to ensure the normal temperature regime of the housing of a heat-loaded microelectronics element using a passive cooling system of a specially designed shape.
Keywords: heat sink, efficiency of the heat-removing structure, thermal resistance, temperature regime, heat transfer, thermal resistance, heat dissipation, heat-loaded element
The aim of this study was to analyze the possibility of using a mathematical model of logistic regression for the recognition of malignant neoplasms on digital images of the skin. The study used a database containing 6594 digital skin images. At the first stage of the study, digital skin images were segmented to isolate the object under study, in which morphometric and color characteristics corresponding to the parameters of the classical ABCD system were determined. At the second stage, the characteristics were used in the classification into malignant and benign neoplasms using logistic regression. When classifying images, the highest value of the accuracy indicator (67.9 [66.9; 68.8]%) was obtained during classification using logistic regression, built on the basis of the reverse Wald stepwise method. Thus, the logistic regression built on the basis of the reverse stepwise Wald method can be applied in the classification of malignant neoplasms on digital images of the skin, but further research and determination of the optimal parameters are required.
Keywords: mathematical model, digital skin images, logistic regression, image classification, skin cancer
Increasing the accuracy and quality of the surface layer of the product with minimal time and economic costs is the number one task of any engineering production, for this high-precision cutting is used. Overestimation of cutting conditions leads to an increase in contact loads acting on the cutting insert of the tool, which in turn affects the performance of this cutting tool and leads to a decrease in the efficiency of its use. It has been established that under production conditions, the failure of the cutting tool due to the destruction of cutting plates with different sections is 80-85%. The solution is to reduce bending stresses by reducing the area of coverage, thereby reducing the wave of deflection under load that the cutting wedge experiences. Also in the studies, the results of the dependence of deflections on the angle of coverage of the plate were obtained using analytical calculations and approximated in the form of a graph. The ideal angle for wrapping the plate is close to 2α = 100°, where deflections are practically absent (minimum). The article considers the possibility of confirming the correlation of stress propagation in a round insert during turning. The results of the calculation show that the bending moment at the place of application of the load also increases with an increase in the angle of coverage of the plate, as in the case described by the studies during milling. Thus, the correlation of stress propagation during processing with a round insert during milling and turning is confirmed.
Keywords: Cutting tool, bending stresses, cutting process simulation, cutting wedge, turning, milling, deformation, multifaceted indexable insert
The Canny Edge Detection algorithm for processing X-ray images has been developed. The results of the computational experiments have shown that the adaptive Gaussian filter improves the anti-noise ability and displays the location of the edges more accurately.
Keywords: detection of Canny edges, Gaussian filter, analysis of medical radiographic images, visualization of noise absorption
We present and investigate a discrete model of competitive resource allocation, taking into account the opportunistic behavior of the participants in the competition (active agents). We used the method of qualitatively representative scenarios of simulation modeling for the study of the model. The Nash equilibrium is found numerically. The dependence of the behavior of the game participants on the parameters of the model is investigated.
Keywords: corruption, competiive resource allocation, imitation modeling, qualitatively representative scenarios
The occurrence of convection in a two-layer system consisting of a region of a free fluid and a porous array saturated with the same fluid is investigated. The equations in the Oberbeck-Bussinesq approximation are used to describe the motion of a pure fluid, and the equations based on Darcy's law are used for the porous layer. Using the shifted grid scheme, the plane problem is approximated in natural variables. At the interface, special formulas derived by the integro-interpolation method and taking into account the different types of equations in the two domains are applied. The results of calculating critical numbers corresponding to the occurrence of convection for different heights of the porous layer and Darcy numbers are presented.
Keywords: dconvection, porous medium, Oberbeck-Boussinesq equations, Darcy model, shifted grids, stability
Numerical investigations of the dependences of the output characteristics of the ion strontium vapor laser on the pressure and temperature of the active medium were carried out. Based on the results of calculations, a range of conditions for the excitation of the active medium was found for the realization of the multiwave lasing regime on visible and infrared transitions of the strontium ion (λ=430.5; 416.2; 1091 and 1033 nm SrII). A number of patterns were revealed that are inherent in the active medium of a strontium vapor laser, and the physical mechanisms that determine them were established. The investigations results provide a possibility to choose the conditions for optimal excitation of multiwave strontium vapor lasers, as well as to control the relative contribution of various spectral components to the output radiation.
Keywords: multiwave radiation, recombination pumping, self-termination transition, strontium vapor laser, numerical modeling
In this paper, the authors consider the problem of reflexively controlled cyber wars of our time on the example of influence in cyberspace, which is currently both a medium for conflict and its tool. The implemented cyberattacks and the danger of hacker attacks are analyzed. Separately, it is noted that the risks associated with cyber intrusions may include the loss or disclosure of consumer data, theft or disclosure of intellectual property, as well as the loss of investors as a result of the theft of funds or a decrease in the market value of companies subjected to cyber attacks. It is concluded that cybersecurity is a constantly evolving landscape, and currently there is an urgent need to constantly learn both from our own experience and from the experience of other companies that effectively counteract cyber attacks. In addition, an important condition is that successful interaction with opponents in cyberspace requires constant striving
Keywords: cyberwarfare, cyberattacks, cybersecurity risks, communication networks, transport systems, tactical, operational and strategic initiatives
The article discusses the experimental implementation of a cloud data center based on the principles of sharing economy. The research presents an algorithm and implementation of resource management for shared consumers. The article demonstrates a qualitative assessment of the system performance and basic performance tests of web applications deployed according to the proposed model.
Keywords: cloud technologies, web application, consumer economy, virtua