Mechanical engineering and machine science
Purpose of research. Currently, exoskeletons are getting widespread use. They enhance human capabilities in terms of ease of movement, carrying loads and different types of activities that require considerable effort. Especially effective are those exoskeletons that make it possible to make complex types of movement of both for the lower and upper limbs, which significantly expands the capabilities of a person when performing loading and unloading operations. Relatively recently, they have started the development of exoskeletons which use the elements of gravity compensation. Therfore, the study of energy costs in the process of load lifting and the study of gravitational compensators influence on the magnitude of moments made by the electric drives of the femoral and knee joints, is relevant and is revealed in this paper.
Methods. Methods of system analysis, design of biotechnical systems, control theory, theory of mechanisms and machines, methods of mathematical modeling of dynamic systems, methods of optimal planning and design were used to solve the problems. Mathematical packages Matlab/Simulink were used to make software products.
Results. The study shows that the use of gravity compensators can significantly reduce the load on electrodrives. The movement of load is due to the operation of engines located in the area of ankle, knee and thigh joints. Since the movement of the exoskeleton occurs in the sagittal plane during load lifting, the position of the exoskeleton links in space is determined by four independent parameters.
Conclusion. The mathematical model of load lifting by a man in an exoskeleton has been developed. Mathematical modeling of the process of load lifting with the help of exoskeleton electric drives has been made. A special attention is paid to the study of gravitational compensators influence on the magnitude of moments created by the electric drives of femoral and knee joints. It shows that the use of gravity compensators can significantly reduce the load on electric drives. Also, the study of energy costs in the process of load lifting has been conducted.
Purpose of research. The present paper concerns the close analysis of detecting the sizes of defects and ways of their identification. The aim is to solve the problem of rational choice of equipment, which will make it possible to fully, clearly and reliably judge the quality of the product. This is important because, depending on the material of the product, the resulting defect sizes may vary.
Methods. For this purpose, this article discusses a method for determining the actual size of defects’ images in ultrasonic control of export oil pump cases made of 20GL steel grade using a flaw detector with digital-focused antenna arrays. The paper describes the main differences in the configuration of equipment that uses different techniques of image restoration, and the feasibility of applying multi-channel sensors for the control of this type parts. The design of the antenna array and phased antenna array has been considered as well as the principle of operation of sensors with phased array antenna and digital phased array antenna. The study of the cast body of export oil pump has been completed, during which defects such as “microporosity” was found. There have been identified their maximum permissible front distances and the formula to determine their actual size has been deduced. The dependence of frontal sizes of defect images on the depth of their occurrence in the product has been considered.
Results. According to the obtained data, a graph of dependence of the frontal size of a defect image on the depth of occurrence has been constructed. Using this graph, it is possible to determine the maximum permissible sizes of defect images for intermiary depth, excluding calculations, which confirms the economic efficiency in the analysis of the control results using this method.
Conclusion. The authors substantiate the feasibility of using equipment with phased array antenna and digital phased array antenna.
The strenghening thermomechanical treatment represens the combined processing treatment – a combination of plastic deformation and hardening in one technological process. Year after year, it is more widely applied in industry.
Purpose of research. The study of strenghening thermomechanical treatment operating modes influence on the formation of mechanical properties of steel, which is a very important scientific problem associated with obtaining materials with a given set of mechanical features.
Methods. High-temperature thermomechanical treatment was conducted under the conditions in which the processes of recrystallization of deformed austenite were partially or completely supressed, and the process of polygonization got the most development, with the goal of forming a developed substructure of austenite inherited by martensite during subsequent quenching.
The paper investigated the change in the properties of high-strength reinforcement under heating (tempering) with different intensity. High-temperature thermomechanical treatment was carried out by including a hardening device in the technological line of the mill No. 280 LLC “Tulachermet-steel”. The studies were carried out on two modes of mill No. 280 operation. Low-carbon reinforcing steels St3 and ST5 were accepted as the studied steels.
Results. It has been experimentally established that the maximum cooling capacity of the existing hardening device is manifested when three working sections with a water pressure of about 13 in each section are turned on. In this case, high-temperature thermomechanical treatment should be carried out at the maximum cooling rate in the strengthning device in accordance with the specified strength class, i.e., include the least number of working sections. Intensive cooling mode contributes to the formation of a homogeneous structure in the reinforcement with a high mechanical complex. It was found that during high-temperature thermomechanical treatment it is advisable to withstand the deformation temperature in the range of 1000...1050 ℃ to guarantee the production of reinforcement of a given class. It has been shown that the inclusion of a strengthening device in the mill line directly behind the flying shears, and not behind the finishing stand of the mill leads not only to the trouble-free operation of shears, but also to an increase in the post-deformation aging between the end of deformation and the beginning of bar hardening to a value close to the optimal, responsible for the formation of a polygonal substructure in austenite, the inheritance of which by martensite provides high mechanical properties of steel after high-temperature thermomechanical treatment.
Conclusion. These results can be applied to create resource-saving material treatment processes.
Purpose of research. The article deals with the adaptation of the algorithm of the extended Kalman filter for the integration of data from sensors of physical values of a mobile robot
Methods. Integration of data is the process of information (data) fusion for determination or prediction of the state of an object. Integration provides increased robustness of robot control and accuracy of machine perception of information. This process is similar to repeated experiments in order to determine in direct and/or indirect ways the value of a physical quantity with the required accuracy. In the control system of a mobile robot, the integration of sensor data is carried out by one or more computing devices (for example, processors or microcontrollers) [1-5].
Results. Advances in digital signal processing and image processing are based on new algorithms, increasing the speed of data processing by computing devices and increasing the speed of access to data stored in storage (storage devices) and the capacity of the latter. Computing devices also perform averaging and filtering of signals of individual sensors and their further matching. The problem of sustainable integration and processing of information from different measuring devices can be solved with the help of the Kalman filter algorithm. The Kalman linear filter algorithm and, in particular, the extended Kalman filter algorithm perform a large amount of computation in the course of their work. In comparison with the linear Kalman filter, the extended Kalman filter significantly increases the requirements for the computing power of the onboard computer (computing device, computer) of amobile robot.
Conclusion. The main effect of integration is to obtain fundamentally new information that cannot be obtained from individual sensors. This approach relieves data channels of large (excessive) data flows coming directly from the sensors, and reduces the requirements for computing power of the computing device of the upper level of the structure of the mobile robot control system.
Purpose of research. Powder copper is widely used in various fields of machine engineering for the production of electrical contact and antifriction products. The quality of sintered products is estimated by density and porosity. One of the main methods for determining the porosity of formed and sintered products is a metallographic method with elements of qualitative and quantitative analysis of pore geometry.
The properties of sintered products made of electroerosive copper powder have not been studied up to the present, which makes it impossible to predict their properties and scope of practical application.
The purpose of the work is to study porosity and pore-size distribution of sintered samples of electroerosive copper powder.
Methods. To perform the planned studies, waste of electrical copper wire (GOST 859-2001) was used. As a working fluid distilled water was used. To obtain a powder of copper a unit to produce powders of conductive materials (patent for invention RF № 2449859) was applied. Dispersion parameters were: voltage 220 V, capacity 45.5 µF, pulse repetition rate 100 Hz.
Isostatic pressing of electroerosive copper powder obtained in water was carried out in isostatic press "EPSI" CIP 400-200*1000Y. The compacted samples were sintered in a high-temperature furnace "Nabertherm" VHT 8/22 in vacuum at a temperature of 900 °C and 1000 °C for 1 hour.
The porosity of the sintered samples of electroerosive copper powder obtained in the water was determined by metallography using optical inverted microscope OLYMPUS GX51 .
Results. Based on the results of the conducted studies, it was experimentally proved that the porosity of a sintered sample of electroerosive copper powder at 900 °C is 5.8 %, the porosity of a sintered sample of electroerosive copper powder at 1000 °C is 2.16 %.
Conclusion. The obtained experimental data can be used to create resource-saving processes for processing metal alloys and composite materials.
Constructions
Purpose of research. The purpose of the study is to develop an experimental design of an integrated air heater, conduct and analyze experiments as well as to determine the main characteristics of a thermoelectric generator in low-grade heat recovery of waste gases.
Methods. The experimental unit consists of two blocks – a thermoelectric generator operating on the principle of cross heat exchange for heat recovery with concurrent heating of the incoming air, which is supplied as a mixture to the burner device of the boiler unit; and an adsorber block filled with blast furnace slag for cleaning the waste gases from nitrogen, sulphur and carbon oxides. To achieve these goals, the work is based on the proposed thermoelectricity effect, which works on the principle of converting thermal energy into electricity at a temperature difference between hot and cold junctions in thermoelectric sections consisting of two metals different in their electronegativity. At the same time, in an integrated air heater, the intensification of the process of adsorption of harmful components by granulated blast furnace slag takes place, which reduces the heat content and temperature of waste gases, reduces emissions of flue gases and, as a result, increases environmental safety of the area adjacent to the boiler. In particular, the study of countercurrent heat exchange in the design of the thermoelectric generator was carried out.
Results. The main result of the research work is the development of an experimental design of an integrated air heater, an experimental technique and the determination of the main characteristics of the thermoelectricity generation process.
Conclusion. The use of such an integrated air heater can improve the efficiency of heat-generating units of low, medium and high power installed in the central heating stations, multi-family and single-family houses. The gained electric power with the subsequent transformation can be used for power supply of automatiс equipment of boilers of low, medium and high power, and for power supply of the stations of cathodic protection against electrochemical corrosion of back-end surfaces formed as a result of the presence of water vapors in waste gases.
Purpose of research. The purpose of the study is to carry out an applied research of buildings' thermal mode of Southwest state university on the basis of energy audit results and development of scientific and technical actions of thermal sanitation including search of expedient options of enclosing structures' warming and increase of heat supply system by thermal energy accumulation.
Methods. Heat power indicators of research objects and their comparison with standards were defined on the basis of energy audit results. It was done for the research objective achievement. Possible options of bringing thermal resistance of enclosing structures to required values were analysed taking into account minimization of capital expenditure. Inclusion of warmth accumulators on transition phase in the system of heat consumption is offered. It is used for removal of heat superfluous at night from heating system and its rational use for economy consumption of thermal energy. Saved thermal energy is supposed to be used for hot water supply (HWS) in the afternoon. Integration of thermal accumulators allows to smooth unevenness of HWS loadings for decentralized heat supply system. Shutdown of the main source (heat generator) on usage time of accumulated warmth gives positive ecological effect, i.e. provides reduction of greenhouse gases emissions. Ways in efficiency increase of warmth faze changing accumulator of housing type is offered to use.
Results. Development of technical actions for ensuring power efficiency and increase in consumer's quality of research objects is a result of the carried-out research.
Conclusion. Implementation of developed actions for thermal protection and the use of energy efficient engineering actions allows to achieve the following results: to increase consumer quality of buildings, to bring parameters of an internal microclimate to standards; to prolong service life of enclosing structures considerably, to provide consumption economy of energy resources on heat supply due to decrease in transmission and filtration heat losses and rational heat expenses with the use of thermal storage devices; to reduce the volume of harmful emissions of combustion products due to shutdown of heat source by usage time of accumulated warmth.
Computer science, computer engineering
Purpose of research. The article is devoted to development and approbation of parameters' assessment technique of anchor inertia moments of direct current motor with an independent excitation (DCM IE) and its loadings used in laboratory vibration installation for chaotic dynamics research.
Methods. The DCM IE mathematical model and technique description for assessment of anchor inertia moment with loading as a result of parametrical identification on the basis of approximation integrated curve of current runaway and implementation of spectral analysis is described in the article. Joint dynamics modeling of Maxon RE25 electric motor with electric and mechanical part was done in Matlab Simulink system. Mechanical part was constructed in MSC Adams. Technique operability of parametrical identification was checked on the basis of machine experiment results.
Results. Structure and general view of information and measuring system of laboratory vibration installation for chaotic dynamics research on the basis of input-output NI USB-6009 module is presented. Dispersal curves and an amplitude range of current received during experiment for definition of anchor inertia moments of Maxon RE25 engine and debalances are analysed. Calculation of anchor inertia moments and debalances are made according to an offered technique. Calculation of relative errors in comparison with passport value is also made.
Conclusion. According to the results of carried out parallel experiments it is found out that experiments can be made according to Kokhren's criterion. And the error of DCM anchor inertia moments definition is no larger than 5%. Therefore it can also be used for calculations with sufficient accuracy of debalances inertia moments.
Purpose of research. The article is devoted to the development of production predicting models and their stability conditions.
Methods: Predicting models are actively used in modern control systems, in information support intellectual systems of decision-making. They have a huge role in any activity connected with signals' processing including anomalies detection of various technological processes and assessment of risk potential of critical information infrastructure objects. They can also be used in monitoring systems of security threats. Special class among predicting models is represented by the models based on experiences of proceeding processes (for example, regularities taken from the data which are saved up as a result of an object work).
Results. Virtual "instant" model of an object belonging to this class is described in the article. It is presented taking into account multiple and large-scale decomposition of entrance influences vectors and the forecast of an object output. The described model gives the forecast without possible future conditions of an expected background. The approach based on the wavelet-analysis which is characterized by a unique opportunity of detailed frequency analysis in time is developed for stability study of virtual "instant" model. Stability conditions of the predicting model are received on the basis of this approach. This model has allocation conditions for approximating and detailing components for four types of ratios between memory depth on input and output.
Conclusion: Predicting model of oil processing in which memory depth on an input is more than memory depth on output is described in the article. It is shown that the accuracy of virtual "instant" model forecast is higher than linear predicting model has at rare data of laboratory analysis. One of stability conditions depending on decomposition depth is shown for the constructed model. On the basis of received results analysis it is possible to draw a conclusion on applicability of received stability conditions for risk potential assessment of process development forecast implementation in monitoring systems of security threats.
Purpose of research. is cost reduction of electric grid companies due to development of information management system of commercial losses. Implementation of an information system provides information systematization and formation of electric power balances capable to output information about losses on various sites of network structure such as 0.4 kV air and cable power lines.
Methods. Losses estimate method which uses summarized information about network schemes and loadings. This method includes calculation of electric power losses on the basis of losses dependence on total length and lines, total power and equipment received on the basis of technical parameters of lines and equipment or statistical data.
Results. There is a problem with losses tracking of electric power on various voltage levels in many power supply organizations. It is connected as with lack of functionality in existing information systems of cuts formation on various levels of network structure and also with network structure maintenance on each connected subscriber. Electric power supply organizations have no opportunity to trace electric power transport systemically from supplying elements (tires of substations) to 0.4 kV air and cable lines of low voltage transfer. It happens due to hierarchy lack in existing structures of supplying elements. It is impossible to define on what network sites losses exceed admissible norms and manage them without registration data systematization.
Conclusion. Information system was implemented on the basis of an objective which systematizes registration data and forms electric power balances on various levels of network structure. Review results (data collection) have information about alleged commercial losses on definite electric network sites.
Purpose of research. A reconfigurable computer system consists of a computing system and special-purpose computers that are used to solve the tasks of vector and matrix algebra, pattern recognition. There are distinctions between matrix and associative systems, neural networks. Matrix computing systems comprise a set of processor units connected through a switching device with multi-module memory. They are designed to solve vector, matrix and data array problems. Associative systems contain a large number of operating devices that can simultaneously process multiple data streams. Neural networks and neurocomputers have high performance when solving problems of expert systems, pattern recognition due to parallel processing of a neural network.
Methods. An information graph of the computational process of a reconfigurable modular system was plotted. Structural and functional schemes, algorithms that implement the construction of specialized modules for performing arithmetic and logical operations, search operations and functions for replacing occurrences in processed words were developed. Software for modelling the operation of the arithmetic-symbol processor, specialized computing modules, and switching systems was developed.
Results. A block diagram of a reconfigurable computing modular system was developed. The system consists of compatible functional modules and is capable of static and dynamic reconfiguration, has a parallel connection structure of the processor and computing modules through the use of interface channels. It consists of an arithmeticsymbol processor, specialized computing modules and switching systems; it performs specific tasks of symbolic information processing, arithmetic and logical operations.
Conclusion. Systems with a reconfigurable structure are high-performance and highly reliable computing systems that consist of integrated processors in multi-machine and multiprocessor systems. Reconfigurability of the structure provides high system performance due to its adaptation to computational processes and the composition of the processed tasks.
Purpose of research. The object of the study is a network cloud service built on the basis of a replicated database. Data in distributed computing systems are replicated in order to ensure the reliability of their storage, facilitate access to data as well as to improve the storage system performance. In this regard, the problem of analyzing the effectiveness of processing the queries to replicated databases in a network-based cloud environment, and, in particular, the problem of organizing priority query queues for updating databae copies (update requests) and for searching and reading information in databases (query-requests). The purpose of this work is to study and organize priority modes in a network distributed computing system with cloud service architecture.
Methods. The study was conducted on the basis of two types of behavioural patterns: models based on Petri nets to describe and verify the functioning of a distributed computing system with replicated databases represented as a pool of resource units with several units, and models based on the GPSS simulation language for possible evaluation of passage of query time of each type in queues depending on the priority of queries.
Results. Based on two simulation methods, the operation of a cloud system with database replicas was analyzed. In this system two distributed cloud computing systems interact: MANET Cloud based on a wireless network and Internet Cloud based on the Internet. These databases together are the basis of the DBaaSoD (Data Bases as a Service on Demand) cloud service (databases as a service organized at user’s query). To study this system the models of two classes were developed. The model based on Petri nets is designed to test the simulated distributed application for proper functioning. The decisions on the mapping of Petri nets on the architecture of computer networks are discussed. The simulation statistical model is used to compare the priority and non-priority maintenance modes of query- and update-requests by the criterion of average passage of time of queries in queues.
Conclusion. System models based on Petri nets were tested, which showed their liveness and security, which makes it possible to move from models to building formalized specifications for network applications for network cloud services in distributed computing systems with replicated databases. The study of GPSS-model showed that in the case of priority service of update-requests, the time of passage for them is reduced by about 2 to 4 times compared with query-requests, depending on the intensity of the query-requests. In the non-priority mode, the serving conditions for update-queries deteriorate and the time of passage in the queue for them increases by about 2 to 6 times as compared with query-requests depending on the intensity of the query-requests.
Purpose of research. is to assess the performance of the infrastructure of the Data processing system (DPS) of graphic user interface (GUI), taking into account the functional purpose and operation conditions of its elements. The object of the study is the GUI DPS since it is a typical element of the automated-information system (AIS) infrastructure of an enterprise, based on the centralized two-level structure of LAN in automated working place (AWP) and computer (servers).
Methods. The article presents a model of functioning of a local area network for processing geospatial information, organized using the client-server technology, which takes into account the impact on the overall performance of AWP parameters that perform not the main function, but the supporting one. In modern conditions, the amounts and diversity of data used in planning, organizing and implementing large information projects significantly increased. In addition to data from space monitoring systems, the flow of geodesic, meteorological and geophysical information is growing, which needs to be analyzed and taken into account when preparing and conducting projects. Even today, the necessary types of data in the required amounts cannot be accepted, processed and integrated using the existing technical means of ground infrastructure.
Results. The research performed in the article showed that the functional reliability factor significantly affects the basic functional properties of the considered GUI DPS so it is necessary to take into account functional reliability of the elements when analyzing and choosing the systems of the class under consideration.
Conclusion. The contradictions that have arisen between the increased flows of information and the existing possibilities of their processing and use necessitate application of new tools, in particular, based on the principles of geo-information technology and geospatial information.Purpose of reseach. One of the most pressing environmental problems is the formation of production and consumption waste; moreover, the bulk of the waste is not involved in the circular economy but is disposed at landfills and waste dumps that pose a serious ecological hazard to the environment and public health. The authors of the article substantiate the need to apply modern information technologies for a qualitative and quantitative analysis of the composition of emissions, a comprehensive assessment of the environmental state near sources of pollution, a study of cause-effect relationships in the ‘environment – public health’ system, and health risk assessment for the subsequent justification of the priority management decisions to ensure the environmental health and public safety.
Methods. The main method used to assess the negative impact of municipal solid waste landfills on the health of the population living in the areas of their effect is the concept of risk assessment and analysis.
Results. Particular attention was paid to the analysis of information technologies used in assessing the risk to public health from emissions of landfills of municipal solid waste; examples of using software products at various stages of assessing the risk to public health from emissions from Kursk landfill were considered. To take into account the specific uncertainties that are due to the peculiarities of the functioning of municipal solid waste landfills as risk sources, the authors developed an electronic database of the municipal solid waste morphological composition and landfill facilities.
Conclusion. The developed database will allow us to level the uncertainties that arise in assessing the risk to public health from emissions of municipal solid waste landfills to the extent possible, and, so, increase the objectivity of the obtained risk assessment results.
ISSN 2686-6757 (Online)