Vol 31, No 1 (2021)

Introduction. The article deals with the conditions for growing greenhouse plants. Supplementary lighting supports the process of plant photosynthesis and the microclimate in the greenhouse. The authors suggest the ways to reduce energy consumption in greenhouses by controlling the microclimate and process of supplementary lighting in greenhouses.
Materials and Methods. Special lighting and temperature are required for growing greenhouse plants. A method of efficient plant growing is light and temperature control. The development of a control algorithm requires the mathematical models that relate the process of photosynthesis to the microclimate parameters. There are given the mathematical models based on the experimental data.
Results. The control system and algorithm to control plant-growing conditions have been developed to maintain the greenhouse microclimate. LED lamps are used to control the lighting process. The authors present the developed block diagram of the control system, which contains four channels responsible for the main energy-intensive microclimate factors. The description of the algorithm of the greenhouse light-temperature control is given.
Discussion and Conclusion. In conclusion, the need to maintain the greenhouse microclimate and supplementary lighting with the different radiation spectrum for the efficient cultivation of greenhouse plants is shown. The developed structure and control algorithm for the supplementary plant lighting process and greenhouse illumination through using LED lamps help reduce energy consumption.

Introduction. Grinding sugar beet should be carried out with minimal losses in centrifugal beet cutters with specially designed knives that provide frequent and constant chaotic longitudinal-lateral cutting of circular conductive beet knots. The objective of the work is to increase the reliability of the knives of centrifugal beet cutters by structural and technological strengthening in the process of their production and restoration.
Materials and Methods. The state of the cutting edges of the knives was determined by using the micrometric measurement of the wear and deformation of the edges. Physical and mechanical indicators were analyzed based on the values of wear resistance, microhardness, and bending endurance.
Results. The analyzes of the defective state of the knives of centrifugal beet cutters and theoretical studies of the grinding process have allowed formulating the factors affecting the permeability of the beet chips and the efficiency of their grinding with knives of a special diamond-shaped design. Experimental studies have made it possible to establish dynamically substantiated design parameters of an improved knurled knife.
Discussion and Conclusion. The proposed measures ensured an increase in the durability of knives by 27–30%, the relative wear resistance of cutting edges by 20%, the limit of endurance of cutting edges for bending by 25% and a shift increase in the length of chips by 18–20% with an increase in its permeability by 16–18%. 

Introduction. The completed developments are aimed at creating a new technology for increasing the wear resistance of a thin-walled instrument of complex configuration made of steel 65G for cutting beets at sugar enterprises. The most important requirement to improve the operability and durability of such a tool is the preservation of its profile and cutting edge during operation.
Materials and Methods. A new developed equipment and technological process of strengthening using low-temperature nitrogen plasma were used to solve this problem. There have been determined optimal processing parameters that ensure the formation of a quasi-morphic structure on the friction surface that reduces the defectiveness of the cutting edge after its machining and also provides a process of self-sharpening due to tool strengthening on one side.
Results. The comparative studies of the friction surface of products after operational tests have shown that their resistance increase significantly when strengthening both new and used products. This is determined by the nature of the quasi-morphic structure formed and the specific relief in friction on the working surface.
Discussion and Conclusion. To describe the new process of strengthening thin-walled products, the structure formation on the friction surface was analyzed in detail with the use of metallographic images and its phase relationship variability was estimated by the optic-mathematical analysis of various zones (compression and vacuum) formed as friction bands. This was done trough modeling with the estimation of the distribution density of the conditional colors of the analyzed fragments.

Introduction. A review of research on modeling and calculating moisture contours showsthat at this stage there is a developed formalized mathematical apparatus connecting physically reasonable parameters and hydro-physical properties of soils. However, to improve the efficiency of drip irrigation and fertigation, it is necessary to determine the effect of fertilizers dissolved in irrigation water on hydrophysic properties of soil, and on the basis of the findings to determine the effect of fertilizers on shapes and sizes of moisture contours.
Materials and Methods. To investigate the effect of fertilizers on the dynamics of moisture contours, potassium monophosphate was used, because it has a “bad” mobility in soil and it is cost-efficient to be introduced into irrigation water. Potassium monophosphate effects on density, viscosity, osmotic pressure, moisture contact angle and surface tension of irrigation water. As a result, there are changes in soil water retention curve and its hydraulic conductivity function. Therefore, moisture contours are formed with small, but still significant differences.
Results. A software tool has been developed that allows exploring the dynamics of the moisture contours of different soil types and texture with different porosity and with a previously known moisture distribution in depth.
Discussion and Сonclusion. When potassium monophosphate or other nutrients are added to water, small changes of the formation of moisture contours are observed. The results obtained enable us to calculate irrigation norms at the design stage of the planning process of fertilizer distribution with irrigation water during drip irrigation for different concentrations.

Introduction. When carrying out an energy assessment of agricultural machines and traction tests of tractors, the most important indicator is the value of the tractive effort. The existing methods for determining the tractive effort of tractors imply the use of specialized measuring instruments, such as strain gauges and devices for processing and displaying information. The accuracy of determining the tractive effort is significantly influenced by the physical and mechanical properties of soil. To process the useful signal during the measurement of tractive effort, the data stream of the strain gauge sensor must be subjected to additional digital filtering taking into account the operating conditions of the agricultural unit.
Materials and Methods. The functions of changing the tractive effort obtained on the K-744R2 tractor in various gears have been analyzed. An algorithm for digital processing of the signal of a strain gauge force meter based on a median filter has been developed that makes it possible to increase the measurement accuracy. The advantage of the proposed method is the ability to cut off sharp short-term impulse noise and sharp fluctuations in the amplitude of the measured value.
Results. A method for determining the amount of tractive effort using median signal processing has been proposed. A device for determining the tractive effort during testing of agricultural tractors and units has been developed. The choice of the main components of the device for determining the magnitude of the tractive effort has been substantiated. As a result of the research, a device for measuring and digital processing of the signal of a force meter based on a microcontroller and specialized software for processing initial data in real time was designed and manufactured.
Discussion and Conclusion. The developed method makes it possible to exclude the negative effect of impulse noise arising in the process of measuring the tractive effort of the tractor. The proposed device for measuring the tractive effort of tractors is compatible at the level of the exchange protocol with existing devices, has a high speed of operation in real time, multi-channel operation.

Introduction. In this article, the problem of temperature distribution in an oil-bearing formation with a hydraulic fracture and a vertical injection well is numerically modeled.
Materials and Methods. To describe the process of temperature distribution in the formation under the action of the fluid injected into the formation, the Fourier-Kirchhoff equation of convective heat transfer is used. To solve this equation, the discontinuous Galerkin method on staggered unstructured grids is used. To describe the process of pressure change in the formation under the action of the injection well, an equation is used that is obtained based on the continuity equation and Darcy’s law. To solve it, the discontinuous Galerkin method on an unstructured triangular grid is used. To parallelize the numerical algorithm, the MPI library is used.
Results. The article presents a numerical algorithm and the results of modeling the dynamics of the temperature fields in an oil reservoir with a hydraulic fracture and a vertical injection well.
Discussion and Conclusion. A numerical algorithm based on the discontinuous Galerkin method for math modeling of the temperature and pressure fields in a oil-bearing formation with a hydraulic fracture and injection well was developed and implemented. The results obtained for the distribution of temperature and pressure in the fracture are adequate and in good agreement with the specified initial-boundary conditions. Further work in this direction involves modeling on tetrahedral unstructured meshes for a more accurate study of the ongoing processes.