Статьи журнала - Вестник Южно-Уральского государственного университета. Серия: Компьютерные технологии, управление, радиоэлектроника
Все статьи: 1059
Methods and principles of using a priori knowledge in recognition tasks
Статья научная
The using of a priori knowledge is an important part of the development of pattern recognition systems. Often the proper use of a priori knowledge allows bring quality of recognition algorithm to the level of practical usage. The main advantage of using a priori knowledge is that the classification algorithms are prone to errors, whereas a priori statements are always true. In the article will be show how to improve the quality of recognition system using a priori knowledge. The evolution of approaches to the use of knowledge considered by the example of the task of object detection, the advantages and disadvantages of these approaches analyzed. The basic principles of using a priori knowledge in recognition algorithms formulated.
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Статья научная
The paper covers theoretical analysis of the existence conditions for sliding processes in electromechanical servo systems of optical complexes, based on coefficients of differential equations describing the systems. It is shown that these conditions may be formulated by frequency characteristics of dynamic elements of electromechanical complexes. The conditions of sliding based on servo drive frequency characteristics are obtained, and it is shown that these conditions are equivalent to the conditions of absolute stability of obtained equivalent circuits of servo drives with relay elements. With the help of the designed method the author has made suggestions on the synthesis of near-ideal sliding processes in electromechanical complexes described by high-order differential equations. The author assumes that sliding processes may be realized in electromechanical systems with asynchronous drives as well; the data of experiments proving these assumptions are given.
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Model of competitive management of regional building projects
Статья научная
This article describes the verbal model underlying the development of a software decision support competitive regional management of construction projects. Competitive management of projects is understood as the purposeful process beginning with the organisation and carrying out of competition in which result projects-applicants are ordered on the basis of certain criteria, then the winner (or winners) the applicant who has won first place (or, accordingly, some first places - depending on competition conditions), and proceeding appears up to project end. Building projects are considered as complete symbolical systems, and management of them to represent a structural composition of four components: the subject of management, object of mana¬gement; a project environment; algorithm of management of the project and criteria of quality of the project. Based on the analysis and synthesis of project management experience in construction in this article was developed verbal model of competitive regional management of construction projects. The proposed model revealed and clarified the existing ideas about the structure of the organization and mechanisms for the implementation of regional projects and due to the evaluation criteria allowed more adequately articulate the problems solved in the stages of this type of competitive project management.
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Model of project management in the digital educational environment of the university
Статья научная
The paper considers the main aspects of project management in a digital educational environment. Particular attention is paid to solving the problem of improving the theoretical, methodological and technological foundations of effective management of project activities of students in the digital educational environment of the university. The purpose of the study is to develop and theoretically substantiate a model for managing students project activities in the digital educational environment of the university. Materials and methods. The solution of this problem in the text of the article was carried out on the basis of a structural analysis of project activities, as a result of which the structural components and functionality were determined, an analysis was carried out for the compliance of the existing system with functional requirements, measures for the effective management of students' project activities were developed and substantiated. Based on the study of the principles of building a digital educational environment, an analysis and modeling of the project management process was carried out. The structure of the digital educational environment of the university is revealed, presented as an open set of information systems designed to provide various tasks of the educational process. In order to ensure effective management of project activities of students, an author's model of project management in the digital educational environment of the university has been developed. The internal structure of the model is provided by theoretical-methodological, perspective-target, content-semantic, organizational-activity and integrative-evaluative blocks. The technology for implementing the model for managing students' project activities in the digital educational environment of the university, developed in the logical unity of content, procedural and organizational characteristics, is presented. Results. Based on the analysis of scientific and methodological literature, the practice of higher education, the current state of the problem of management of project activities of students is revealed. The features of the digital educational environment of the university and its possibilities in the development of the project culture of students are determined. A model for managing project activities of students has been developed and substantiated, including methodological foundations, conceptual and categorical apparatus, theoretical basis and content and semantic content. The technology of implementation of the model of management of project activities of students in the digital educational environment of the university is presented. Conclusion. The introduction of digital technologies and digital tools, their use in managing an organization, in providing access to digital educational and methodological materials, in expanding the space for creativity contributes to the transition to a model of a personalized organization of the educational process. In turn, the digital educational environment is aimed at improving the quality of education and promoting the educational results of students, controlling them and quickly evaluating them.
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Multilayered approach to model predictive industrial process control
Статья научная
The method of the industrial processes efficiency increasing based on the multilayered approach to the control task solution is proposed in the article. According to this approach the existing technology regulations of estimation process conducting in terms of the true accuracy of operating parameters holding is used as the regulatory constraint defining their acceptable region. Within the field specified the process of the controlled operating parameters values optimization according to the current data about operation is implemented. The optimization process is based on multidimensional simplex method usage and orthogonal planning of problem solving in combination with the method of effective domain elliptic approximation. The example of using the proposed method for the blast-furnace process efficiency increasing is given.
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Need of developing information systems of managing a technology lifecycle of industrial enterprises
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The following article is aimed at justifying the need of developing new information systems of managing a lifecycle of technologies in order to increase the efficiency of industrial enterprise performance. This necessity was caused by the objective processes happening in the world, specifically globalization of the world economy and further specialization of labour which led to segregation of production facilities from R&D centers developing new types of products and doing market research. In this regard, the competitiveness of industrial enterprises is now primarily to be defined by the efficiency of the technologies used in the production process. However, nowadays the vast majority of information systems are aimed not at managing technologies, but at managing products. The author shows the common ground and differences between the management systems of a product lifecycle and management systems of a technology lifecycle as well as what competitive advantages industrial enterprises will get implementing management systems of a technology lifecycle. At the same time, the transition into such system should not have a revolutionary nature. It can be implemented due to the improvement of the available information systems, with shifting the focus on improving the existing technologies and creating new ones. Upon such transition, industrial enterprises will keep the available competences in developing new types of products and will receive an additional impulse of development due to the increase in efficiency of the technologies used.
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Neural network forecasting of time series
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In the work, we built a predictive neural network to successfully predict several main classes of radar data, as well as economic indicators. It is a two-layer neural network feedforward network based on the backpropagation error algorithm. The results of forecasting real radio signals. Based on the results of the forecast, it turned out that the neural network ensures the accuracy of the short-term forecast. In this article, we describe the procedures for selecting characteristics for learning a neural network, justifying the choice of the structure of the neural network, training and the results obtained. Time series forecasting is currently an important topic, as it has a wide range of applications (radar, medicine, socio-economic sphere, energy, risk management, engineering applications, etc.). Analysis of works in the field of long-term forecasting of non-deterministic signals showed that at the moment the least studied is the neural network long-term forecasting. The use of neural networks for long-term forecasting is based on their ability to approximate nonlinear functions, the accumulation of history and its application in forecasting and learning ability. The work was based on the method of neural network forecasting using a two-layer network with direct distribution. The implemented neural network can be used to predict real signals of different frequency bands. This study can be very useful in medicine, geodesy, Economics and other areas.
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Статья научная
The development of public transport in cities is an effective way to reduce “congestion” in the road network and, as a result, increase the speed of passenger transportation. Improving the quality of urban bus services helps attract more passengers. Bus intervals are calculated once for each route line individually, based on the average congestion of passengers at the stops. In turn, the sudden accumulation of a large number of passengers at bus stops causes that not all passengers can move in a timely manner, which causes concern for passengers. This is one of the factors that reduces the quality of passenger transport services. The aim of the study is to develop a model for predicting the congestion of passengers at bus stops to optimize traffic management of urban public transport. Materials and methods. This article presents a neural network model for predicting passenger congestion at bus stops. It takes into account the spatio-temporal characteristics of bus traffic. Results. The developed model for predicting passenger congestion at bus stops was tested on real data from bus route 3 (Dushanbe, Tajikistan). The model made it possible to predict passenger traffic (the number of passengers at bus stops) with an accuracy of 72% to 74.5% of the actual number of passengers at bus stops. Conclusion. The proposed method, in contrast to other methods, allows you to automatically adapt the forecasting model to the changing conditions of the route line. This method is universal and can be used for other route lines (bus stops). It does not require much time to reconfigure.
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Non-intrusive temperature measurement for liquid flow using compensators of pipelines
Статья научная
The article presents the results of a numerical study that aimed to accuracy improvement for non-intrusive measurements of the liquid flow temperatures in standard pipelines compensators. Non-intrusive measuring devices are one of the modern promising and profitable tools that stimulate the improvement of technologies and the involvement of world corporations in this sphere, while the growing intellectualization of measurements positively affects the safety and efficiency of the industry. The numerical study result is consistent with the results of laboratory tests and shows the general regularity of flow velocity effect the error of non-intrusive temperature measurements. Shown that measurements after the upper or lower elbow of the compensator makes possible to reduce the measurement error in the Reynolds (Re) range of about 1000-7000, which is characteristic for the onset of turbulent flow of a liquid. Also shown that gravity negatively affects the accuracy of measurements, so preference should be given to horizontally located compensators. Obtained that the flow in pipeline determines the largest temperature change in the wall region of the pipe for relatively high Re, and along the pipeline axis for small Reynolds numbers. In combination with the flow characteristics in the compensator, it changes temperature distribution and error, depending on the flow velocity in the pipeline. In particular, this effect determines error decreasing for temperature measurement in the compensators at low Re numbers. The existing surface temperature sensors, with correction the surface temperature measurements to the flow temperature, require calibration to work on flows with Re numbers varying over a wide range, and binding these measurements to pipeline compensators can improve the quality of measurements due to smoothing and, fluctuation thermal and hydrodynamic influences.
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Non-linear filtering of chaotic signal in the presence of noise
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The creation of radio engineering systems based on the effects of stochastic and chaotic dynamic is a promising direction. The task of developing such systems must be oriented toward using the results of theoretical studies of processes in nonlinear radiophysical systems. The subject of this study is the nonlinear filtering of a mixture of chaotic oscillations and noise based on the stochastic resonance effect occurring in a bistable system with the aim of isolating the information chaotic signal. Usually, noise is considered to be “white”, and the signal is narrow-banded. As a bistable system, a Schmitt trigger can be used. For narrowband signals, the stochastic resonance effect has been studied in sufficient detail theoretically, for broadband information signals, applied research is insufficient. The stochastic resonance effect is a phenomenon in which the response of a nonlinear system to a weak external signal amplifies with increasing noise intensity to some optimal value. In the study of radio engineering systems, chaotic oscillations can be used as information systems. Theoretical basis for research of information processing systems in radio engineering systems using chaotic signals is research in the field of nonlinear radiophysics. Of particular importance in this case is the selection of solutions at the model level, in particular, based on the results of circuit simulation of practically realized devices on the existing element base.
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Статья научная
An algorithm for nonparametric detection of a narrowband signal under Gaussian noise is proposed. The main advantages of the algorithm are the absence of the need for a priori information about the carrier frequency of the signal and the independence of the detection threshold of the noise level. Using simulation, we obtained the detection characteristics of the proposed algorithm.
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O точности численных методов решения уравнений Вольтерра I рода в задачах теплопереноса
Статья научная
Статья посвящена исследованию точности методов решения задачи измерения, возникающей при определении температуры внутри объекта, подвергаемого влиянию внешнего управляющего теплового воздействия. Подход к построению численного решения задачи измерения, связанной с проблемой определения температуры, основан на сведении первоначальной задачи к решению интегрального уравнения, характеризующего прямую зависимость температуры от измеряемых величин. Интегральное уравнение получено с помощью прямого и обратного преобразований Лапласа с привлечением регуляризующего подхода и математического аппарата теории обратных задач. Результирующее интегральное уравнение относится к классу уравнений Вольтерра I рода типа свертки с ядром, имеющим специфические особенности. В данной работе исследуется точность численных методов решении интегрального уравнения со специфическим ядром с точки зрения механизмов реализации машинной арифметики. Вычислительные схемы методов основаны на использовании product integration method, квадратуры средних прямоугольников. В работе также приведены результаты исследования погрешности вычислительной схемы оптимального по порядку метода, основанного на применении преобразований Фурье и метода проекционной регуляризации. Метод применяется для непосредственного решения исходной задачи без перехода к интегральной модели и позволяет получать численные решения с гарантированной точностью. С целью получения экспериментальной оценки точности численных методов и сравнительного анализа машинной точности методов интегральной аппроксимации и оптимального по порядку метода проведен вычислительный эксперимент. Результаты эксперимента свидетельствуют о принципиальной возможности получения численных решений задачи измерения с высоким уровнем точности.
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On exponential stability for linear difference equations with delays
Статья научная
The article gives an overview of recent results on the stability of finite-difference equations with delay. All results are compared with known signs of exponential stability of linear difference equations. The results are obtained using the Bohl-Perron theorem and comparing the equation under study with an equation for which the Cauchy function is positive. The Bohl-Perron theorem allows us to reduce the question of the exponential stability of a linear difference equation with delay to the solvability of an operator equation in one of the functional infinite-dimensional spaces. That is, in fact, to an estimate of the norm or the spectral radius of a bounded linear operator in this space. For this estimation, different difference inequalities are used. One way to obtain such inequalities is to evaluate the fundamental solution in the event that this solution is positive.
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On one problem of control of voltage during signal transmission in a long line
Статья научная
This article discusses the problem of controlling the process of electromagnetic oscillations in a long-distance transmission line. A long line is understood as an electrical line formed, in the simplest case, by two parallel current conductors, the length of which exceeds the wavelength of the transmitted electromagnetic waves, and the distance between the conductors is much less than the wavelength. Such a line is characterized by four distributed parameters, namely the ohmic resistance of the conductor, inductance, electrical capacity and leakage coefficient. A signal generator is connected to the left end of the line, and the right is grounded, but not of high quality. When transmitting a signal, the current and voltage make small oscillation. The control is the voltage at the left end of the long line, and the disturbance voltage at the right end, the values of which are limited. The boundaries of their permissible values are set. The magnitude of the aggregate of external disturbances acting on the conductor is not known exactly, but only its variation limits are given. Aim. The purpose of the control process is that at a given moment in time, the average value of the voltage value is in a given interval. This average is calculated using the specified function. Materials and methods. To solve the problem, the method of optimizing the guaranteed result was applied. Results. A transition was made to a new one-dimensional variable, with the help of which the considered problem was reduced to a control problem of the same type in the presence of interference. This made it possible to find the necessary and sufficient conditions under which it is possible to achieve the set goals with any admissible set of external forces and interference at the right end. A corresponding algorithm for constructing the law of voltage change at the left end of the conductor is proposed. An example is analyzed that clearly shows how management is built that guarantees the achievement of the set goal. Conclusion. If the found necessary and sufficient conditions are fulfilled, then it is always possible to construct such a law of voltage variation at the left end, which will lead to the achievement of the goal for any admissible interference.
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On one solution of the numerical problem differentiation in calculation vertical speed of aircraft
Статья научная
To ensure safety and improve the efficiency of flight missions, reliable information about the altitude and speed parameters of the aircraft (AC) is required. Therefore, improving the algorithm for calculating the vertical speed used as part of the algorithmic support for air signal systems (ASS) is a very urgent task. Purpose of the study. The problem of calculating the vertical speed of an aircraft in the ASS is considered. Materials and methods. The analysis of literature data on the use of numerical differentiation procedures to solve this problem is carried out, it is noted that the methods used are based on different ideas and approaches. It is indicated that two-point algorithms are significantly worse than multi-point algorithms in terms of the achieved accuracy, however, they are characterized by significant simplicity and speed. Various versions of multipoint algorithms are used, differing in complexity, the amount of information used, and the accuracy achieved. The features of the regularizing algorithms, which are essentially filters of a low-frequency useful signal, suppressing the high-frequency component of the error in measuring the altitude signal or, what is the same, atmospheric pressure, are noted. The data on systems with hardware differentiation of the height signal are given. Results. A fairly simple four-point algorithm for numerical differentiation is proposed and substantiated. Due to the averaging of both the measurement results themselves and the estimates of the derivatives, significant filtering of noise is realized, which is an important advantage of the algorithm. For greater accuracy in estimating the vertical speed, it is envisaged to include a preliminary filtering algorithm in the experimental data processing scheme. The filtering algorithm is found from the solution of the optimization problem; it is shown that this algorithm is structurally similar to the filtering algorithms constructed according to the well-known approaches of R. Kalman. The results of computational experiments on the study of the features and characteristics of the proposed algorithms are presented, illustrating their advantages, performance and the possibility of further use in ASS. It is shown that preliminary filtering significantly increases the accuracy of the vertical velocity estimation. Conclusion. The developed algorithms can be used to improve the algorithmic support of the ASS.
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On the information support improvement of IT project management system
Статья научная
Information support of enterprise’s IT project management requires continuous improvement and introduction of the appropriate changes. The study of industrial enterprise activities showed that an automated IT project management system plays the main role in this aspect. Development of an automated IT project management system is a complex and time consuming task but it is very important to execute the operational control of IT projects. Therefore, the main purpose of this article is the operation analysis and development of recommendations on information support improvement of IT project management system. In addition, the main stages of the information system life cycle were identified taking into account the mandatory requirements to the business processes. Along with the analysis of the industrial enterprise brunches the diagram of the IT project management business processes was drawn. It helps to visualize the problem, and to provide as-is and to-be situation (as it is and as it should be) allowing to identify the main benefits of IT projects AMS implementation.
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On the solution of the setting quality problem for the relay controllers
Статья научная
The paper considers a problem of setting the automatic control systems (ACS) including two-position and three-position PID-controllers. The problem can be generally solved by a method of direct simulation analysis of transient response in ACS. To perform a parametric identification of the models of controlled objects, the numerical procedures of determining the optimal parameters of their differential equations have been developed for both experimental transient response curves and transient functions of the working closed systems. The algorithms of digital implementation for the relay controllers are presented. The results of process simulation in two-position and three-position systems are analyzed. The outcomes of the research can be used to select the relay controller settings.
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Optimization of A-star search algorithm
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Introduction. Autonomous mobile robots must be able to plan global and local motion paths. The A-star path planning algorithm allows us to calculate the shortest path between the starting and end points on a map with known static obstacles. In real conditions, when additional information about the area is entered (difficult or dangerous sections, areas with speed limits) and the cost of overcoming them is taken into account, A-star can lead to a non-optimal, for these conditions, solution of the problem. Aim. Consider options for optimizing the A-star path planning algorithm for use in various conditions with restrictions on the number of turns, linking to critical points on a map of the area, difficult and dangerous areas and аssess the quality of the optimization. Materials and methods. Research is carried out by computer simulation of the A-star algorithm and options for its optimization in the MATLAB environment. The criteria for evaluating the quality of optimization are focused primarily on computational time and the path optimality with respect to the selected parameters. Results. The results of path calculation performed using the A-star algorithm before and after optimization are presented. In both cases, the following are estimated and compared: calculation time, number of analyzed polygons, number of turns and path length. Conclusion. In most cases, the optimization of the algorithm increases the path length and calculation time, but not significantly. Moreover, the new path corresponds to the given conditions, is the shortest in these conditions and, therefore, is optimal. The considered optimization options allow you to calculate the path taking into account additional information, estimate the path length and computational time. On the basis of these evaluations, it is possible to choose path planning method suitable for individual scenario.
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Optimization of classifiers ensemble construction: case study of educational data mining
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The choosing the best prediction method of education results is major challenge of Educational Data Mining (EDM). This EDM paper compares the results of student's performance forecast produced by the individual binary classifiers (Naïve Bayes, Decision Tree, Multi-Layer Perceptron, Nearest Neighbors, Support Vector Machine algorithms) and their ensembles, which are trained (tested) on dataset containing up to 38 input attributes (weekly attendance in mathematics, the intensity of study, interim assessment) of 84 (36) secondary school students from Nasiriyah, Iraq. The two-class school performance was predicted - passing or not passing on final exam. Three following stages of comparison were completed. At the first stage of the experiment, the dependence of classifiers from the input attributes was investigated. It was shown that the forecast accuracy rises from 61.1-77.7% when all 38 attributes were used, to 75.0-80.5%, if base classifier trained with five attributes pre-selected by Ranker Search method. Then, in second stage, to each of the base classifier the AdaBoost M1 procedure has been applied and five homogenous ensembles were created. And only two of these ensembles demonstrated small rise of 3% in accuracy comparing to corresponding stand-alone classifier, but the overall maximal prediction accuracy of 80.5% stayed the same. Finally, comparing the accuracies of 77.7% and 83.3% achieved by the heterogeneous ensemble consisted of five simple voting base classifiers and by the heterogeneous meta-ensemble of five simple voting AdaBoost homogenous ensembles correspondingly, we conclude that improvement of the quality of the individual classifier or homogeneous ensembles allows to construct more powerful EDM prediction methods.
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Introduction. Currently, the most important task of the steel industry is to constantly update the product range, increase its operational characteristics, and increase the efficiency of equipment use. Achieving goals is possible with a methodological base based on the principles of system analysis. In metallurgy, multi-electrode arc furnaces using three-phase alternating current are widely used. The lining layer present in such units during operation is subjected to thermal and electromagnetic effects created by the arc. A quantitative measure of this effect is the lining wear coefficient (LWC). In most studies, the influence of the described factors on the LWC is not taken into account. At the same time, heat fluxes affecting all elements of the furnace structure, including the lining, depend on the shape of the arc. Aim. Selecting the parameters of the electric arc furnace, which optimizes the lining wear coefficient. Materials and methods. When performing the work, methods of computational mathematics and evolutionary methods of numerical optimization of functions of many variables were used. Software which uses freely distributed scientific libraries was based on them. Results. The influence of the system of three burning arcs on the wear coefficient of the lining is considered taking into account the shape of the axis of the arc column. Conclusion. An algorithm and program have been elaborated that allow us to evaluate the thermal perception of the lining depending on the shape of the arcs. Based on the developed algorithm, special software can be created that is integrated into the system of automated regulation and prediction of the thermal operation of multi-electrode arc units to increase the reliability of assessing the wear of the furnace lining under different technological modes of arc burning.
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