Volume 31, Nº 2 (2021)

Introduction. Grain harvesters are used for no more than two months within a year. They must have maximum operating reliability, since even short downtime during the harvesting period result in large crop losses. The purpose of the study is to identify the causes of combine harvester failures within the warranty period.
Materials and Methods. Identifying consequences of failures and ensuring the reliability of grain harvesters are based on an improved classification of failures. In the process of studying, there have been proposed the ways to solve the problem of combine harvester downtime based on the analysis of the time for grain harvester troubleshooting. The category of severity of failure consequences was taken into account.
Results. Through monitoring in the period from 2018 to 2020, there were found failures of units and systems of grain harvesters with low reliability indexes within the warranty period. Most of the failures (59.2%) were found in Russian-manufactured combines, of which operational failures are 55.9%, structural failures – 26.7%, and production failures – 17.4%. The general patterns of changes in the average time for combine troubleshooting have been determined. A geometric model of a detail for the trouble-free operation of combines (header auger shaft) was created. The finite element analysis (ANSYS) was used to identify parts, which are subject to maximum workload. There have been identified units and parts, which fail to function within the warranty period, because of design and technological defects.
Discussion and Conclusion. In order to reduce the time to find the consequences of failures, it is necessary to create a more extensive network of enterprises providing a wide range of services, improve the organization of technical service and expand direct links with the manufacturers of equipment in order to respond quickly and make the necessary design and technological decisions.

Introduction. The purpose of research is to develop a mathematical model for assessing and forecasting the complex negative impacts of agricultural technologies on water bodies. This problem is relevant because of the need to enlarge agricultural enterprises. The created model for forecasting is necessary to make an objective assessment, taking into account the complex effect of machine technologies applied to agricultural production and all biogenic elements that have a negative impact on water bodies.
Materials and Methods. There was used the Spesivtsev – Drozdov method of logical-linguistic modeling, which allows giving expert knowledge a form mathematical model. Four experts were interviewed, and the obtained data became a subject of the regression analysis. The adequacy of the model was confirmed using the coefficient of determination and Fisher’s test.
Results. A hierarchical system of 6 factors and 14 sub-factors was formed, including both the applied machine technologies and the management decisions on the matter. There was created a model containing a polynomial equation reflecting the influence of factors on the level of negative impact of technologies and equations that determine the influence of sub-factors on factors.
Discussion and Conclusion. The created model can be used for practical purposes to support making decisions for planning, forecasting and selecting scenarios to modernize agricultural enterprises. The model equations make it possible to understand the significance of factors and sub-factors affecting the level of negative impact (diffuse load) on water bodies. This allows us to choose more effective ways to reduce the negative impact by choosing the most significant factors and/or sub-factors as objects of management.

Introduction. Production of safe food requires the avoidance of using chemical means to bring weeds under control in cultivating crops. Existing tillage loosening and separating machine PRSM-5 Dokuchaevskaya optimizes the physical and mechanical state of the cultivated soil layer, while the weeds are carefully removed from the soil by combing out together with the whole weed root system and laid on the surface, where they dry up under the influence of climatic factors. During the operation of the tillage machine, about 30% of the total energy consumption is spent on the rotor drive. 
Materials and Methods. The soil was considered as an elastic-plastic medium. The generalized Hookeʼs law model and a variant of the plastic flow theory were taken into account. To simplify the calculations, there was used the experimental study information on the position in space of the soil deformation surface. The intensity of stresses of polyplastic deformations of the soil layer was determined. For the numerical solution of the problem, the Ritz method was used.
Results. In connection with the indicated disadvantages, the parameters of the rotor ripper are justified taking into account the reduction in energy consumption for its drive. As a result of solving the problem by the Ritz method, the geometric shape of the rotor ripper was determined. The energy performance of the section of the tillage machine was evaluated by the torque of the rotor drive of the loosening-separating device. The rotor drive torque was determined for rippers with flat, convex, and concave profiles and for the profile substantiated during the study.
Discussion and Conclusion. The profile substantiated during the study provides the best conditions for transporting the soil at the initial moment of the rotor entry into the soil and the minimum energy consumption for its drive.

Introduction. The article presents the results of a study of using various methods for thermal processing of bakery products. It is shown that the infrared method is one of the most promising methods of heat treatment. The analysis showed that when combining different methods of heat treatment, the products retain their consumer qualities and the time of the technological cycle is reduced. The author proposes to use the method of thermal processing in the fast food industry.
Materials and Methods. The subject of the study is a new method of thermal processing of bakery products made from wheat-rye flour using infrared radiation. For the study, a heating unit was manufactured in accordance with the patent for utility model No. 199820, where heating elements made using the grid-screen printing technology were installed; the performance of heating elements was controlled by a device with a PID controller of the TRM 148-T brand with an RS-485 interface.
Results. The article shows that this method can be used to create a uniform product heating. The results of studies on the control of temperature conditions for baking bread are presented. It has been shown that the time of baking bread decreased by more than 25%, while the consumer quality of the product did not change.
Discussion and Conclusion. The studies have shown that the use of the method for thermal processing opens up new opportunities for the fast food industry and other sectors of the national economy. The results of the study showed that together with a set of experimental data, this method will be possible to use in the individual sector and to carry out the intellectualization of the process of preparing various food products.

Introduction. In this article the study subject is the power supply system of the pre-start heater. The purpose of the study is to evaluate the possibility of using a thermoelectric generator to power the liquid preheater with optimization of the flow section of the thermoelectric generator heat exchanger.
Materials and Methods. It is proposed to use a thermoelectric generator as an additional energy source to reduce electric power consumption by a pre-start heater. In the course of the study, various structures of the flow section of the thermoelectric generator heat exchanger have been modeled. The thermal and hydrodynamic analyses were carried out in the software environment ANSYS Workbench, Solidworks Flow Simulation to develop the most effective design for the flow section of the thermoelectric generator heat exchanger.
Results. An experimental installation was assembled and the dependence of the temperature modes of the pre-start heater on the output parameters of the thermoelectric generator was determined.
Discussion and Conclusion. It has been proved the possibility of reducing the power consumption of the vehicle battery during thermal preparation of the internal combustion engine by using a thermoelectric generator adapted to the power supply system of the liquid pre-start heater.