Preliminary separation minimizes damage of free grain by the working parts of the thresher when stripping standing crops. For this purpose, it is advisable to use the inclined chamber of a combine harvester. The purpose of this study is to evaluate the separating ability of a rotary separator depending on its design parameters and operating mode. The research included two stages. In the first series of experiments, the distance between the rod rings was changed (6; 8; 10; 12, and 14 mm), in the second series: the peripheral speed of the rotor surface (1 to 3 m/s). Experimental studies were carried out on winter wheat of the “Moskovskaya 56” variety with a moisture content of 12%. The inclination angle of the experimental installation body in all variants of the experiment was 45°, and the supply of stripped grain heap was 1 kg/s. Based on the results of laboratory studies, it was established that the intensity of separation of free grain increases as the distance between the rod rings of the device increases and the peripheral speed of the rotors decreases. The maximum passage of loose grain (100%) corresponds to a peripheral speed of the rotors of 1 m/s and a distance between the rod rings of 14 mm. The reserves for increasing the productivity of a rotary separator are an increase in the diameter of the rotors and a decrease in their peripheral speed. When these parameters change by 30 to 35%, the transport capacity of the inclined chamber remains at an acceptable level.

The development or modernization of tillage machinery aims to increase its service life and efficiency and reduce the negative impact on the soil. In order to increase the efficiency of agricultural machines, the author attempted to optimize the working element of a subsoler – its plate – through topological and parametric modeling. The subsoiler plate with the mass of 1.925 kg with maximum stresses 176.8 MPa was used as a base model. The author determined the plate zones having the least influence on the stiffness and strength of the implement structure. When designing the modernized plate, the following parameters were taken into account: safety factor on the ultimate strength – 1.5 to 2; maximum mass reduction – less than 50%, minimum reduction – more than 10%. The plate is manufactured by laser cutting from 09G2S or 30XGSA steel. The manufacturing process, strength and wear characteristics, and cost were considered to be not lower than the base variant. The algorithm developed in the SysML system modeling language helped systematize the process and establish functional and non-functional requirements and limitations. Using Autodesk Fusion 360 automatic design system, the author developed the rational geometric shape of the soil cultivation plate of the subsoiler with a mass of 1.585 kg and a maximum stresses of 169.5 MPa according to this algorithm. Topological optimization resulted in a 17.67% reduction in the part’s weight at the second iteration while maintaining strength and wear resistance characteristics. By determining the thickness of the element, the author established compliance with the safety factor requirement. Samples of subsoiler plates with thickness of 16 mm were made of 09G2S steel. To confirm the calculated strength characteristics it is necessary to carry out laboratory and field tests of the prototype of the lightweight design.

Small mini-tubers up to 15 mm can be used for growing high-quality food potatoes saturated with scarce trace elements, for example, selenium, which is a powerful immunomodulator and antioxidant. This requires determining the optimum concentration of selenium applied to plants. The authors studied the yield and basic quality indicators of selenium-saturated food potato tubers grown in 2019-2021 from non-standard mini-tubers with a size of 10 to 15 mm. The research was conducted in 2019-2021 on varieties Gulliver, Ametist and Grand grown on sod-podzolic medium-cultivated sandy loam soil. The experiment course included two options: control – without treatment, experiment – leaf treatment of plants with sodium selenite. The studies were carried out in accordance with the existing methods. As a result of the experiment, the average gross yield was 17.3 to 18.7 t/ha, the marketability in terms of tuber size was 96.5 to 97.4%. In the experiment samples, the selenium content in tubers averaged 0.040 to 0.0375 mg/kg over three years, which does not exceed the maximum permissible concentration in potatoes of 0.5 mg/kg. When using leaf treatment with sodium selenite, the increase in the selenium content in tubers relative to the control was 0.08 to 0.10 mg/kg of raw weight. Leaf treatment with sodium selenite at a dose of 3 g/ha did not significantly affect the quality of potato tubers, but increased the selenium content in tubers to 0.06 to 0.10 mg/kg of raw weight. The profitability of growing food potatoes from small non‑standard mini‑tubers obtained by the aerohydroponic method and leaf treatment with sodium selenite, depending on the variety, is 16.1 to 28.6%. To obtain optimum selenium content in tubers, it is proposed to increase the concentration of sodium selenite and continue research on increasing yield and improving the quality of tubers.

A small-size sprayer with vertical oscillations of the distributor boom without complex copying and compensating devices does not provide quality spraying. Primary seed production requires the development of new approaches to ensure the spreading accuracy of plant protection products (PPP). For this purpose the concept of application of adaptive distribution system of a small-size boom sprayer is proposed and theoretically substantiated. Field experiments with the use of a single-axis boom sprayer of the wheelbarrow type were carried out. The theoretical description of conditions of fulfillment of the spraying operation in relation to violation of the scheme of distribution of working liquid is given. Optimization of values of current frontal angles of the spraying torch is carried out. It has been established that the average range of vertical vibrations of the boom of a single-legged sprayer, like a wheelbarrow, ranges from 16° to 29°. A hypothesis has been proposed to increase the uniformity of distribution of liquid preparations. This is achieved by controlling the geometry of the spray pattern. Analytical dependences of the influence of the geometric parameters of the sprayer and the angle of its transverse inclination on the formed width of the processed strip and the required spray pattern angle were found. A nomogram and operational schedule of sprayer operating modes for the adaptive sprayer distribution system have been developed. With a base spray angle of 110°, the permissible limits for the width of the processing strip; with a lower tilt of the boom, a spray angle of 85° is provided, and with an upper tilt, 135 to 145°. The use of the original balancing device reduces the vertical boom oscillation range up to 14°. The difference in the values of the coefficient of variation of the transverse distribution of the working fluid, at typical and adaptive orientation of the planes of the spray-cone angle in the model experiment was 9.5%. The proposed hypothesis is confirmed.

Large dairy farms use mainly imported technological equipment in automated rotary milking parlors, which provide the maximum throughput capacity of 100 to 500 animals per hour. The most capital-intensive component of the rotary ‘Carousel’ milking parlor is a rotating platform carrying the main load (its own weight and the weight of the animals being moved). The nearly round-the-clock operation mode predetermines significant power consumption and wear of the drive, support, guide rollers and rails making it rather labor-intensive to replace these parts. Therefore, an urgent issue is the import substitution of equipment. In order to increase the operational reliability of the rotary ‘Carousel’ milking parlor, to reduce capital costs during installation, and current costs for maintenance and repair, the authors proposed to develop a resource-saving design of the rotary milking platform. The paper presents the technological design of levitating milking platform of the ‘Carousel’ type with the use of movers operating on permanent magnets (Halbach array) on the magnetic levitation principle (unsupported suspension), and the structural and logical model of a magnetic suspension of the milking platform. The advantages of such a system include the practical absence of friction force to rotate the load-carrying platform with animals, which will require significantly lower drive power. In addition, we obtain quiet movement, significantly lower operating costs associated with the need to replace the support rollers, lubricate bearings, and maintain two or three electric traction drives, etc. The innovative attractiveness of the development lies in the possibility of designing circular and linear magneto-planning electric transport in technological installations to move and manage animals in milking parlors, and move robotic feed cars in feed shops, storage facilities, and around the farm.

When preparing treatment solutions of fertilizers and pesticides for technological processes, one should mix liquids taking into account the precise dosing of components. However, the existing designs of dosing and mixing devices do not provide qualitative dosing. Moreover, a sharp increase of fraction quantity may result in a hydraulic impact. To eliminate these disadvantages, based on analytical research of available designs and patent search results, the authors worked out a mixer for preparing solutions of various concentrations. The device is also capable of changing the ratio of components in the process of operation. The device provides smooth change of preparation concentrations due to the design of dosing valves forming square-shaped ports with a changing configuration. The port plates move relative to each other both horizontally and vertically. The proposed device smoothly changes the concentration of the solution, thereby providing for more accurate dosing. It was experimentally found that a smoother change in the flow rate of treatment liquid according to the solution concentration is observed at a distance from the axes of symmetry of the dosing device disks to the rotation axis of the distribution ports, equal to 0.04 to 0.1 m. The deviation of the actual treatment liquid flow rate from the calculated one does not exceed 5%. The integration of the developed mixer into the systems of fertigation units, sprayers and other specialized machines will ensure better quality of the fine irrigation of plants, seeds, and soil.

The nutritional value of feed is assessed with optical instruments using infrared incandescent or halogen lamps as a source of excitation of the spectral signal of the feed. However, no use is still made of energy-efficient diode optics of the visible radiation range. The authors conducted research to identify the possibility of developing a portable feed value analyzer using a spectral analyzer based on diode optoelectronics. First, the Micran-3 infrared microscope was used to study the microstructure of concentrated feed components; then, measurement ranges were selected. The authors studied characteristic ranges of photoluminescence of corn grain, sunflower meal, grain stillage, and rapeseed meal. Excitation (absorption) spectra were measured at synchronous scanning by the SM 2203 spectrofluorimeter monochromators to analyze luminescence spectra of corn silage and concentrated mixed fodder. As a result, integral parameters of spectra were calculated: integral absorption capacity and the photoluminescence flux index. It has been established that the intensity of luminescence spectra of corn silage in the range between 360 and 370 nm and that of concentrated mixed fodder in the range between 420 and 440 nm differ in more than four times. The value of captured photovoltage of corn silage and concentrated mixed fodder differs in six times. The results of optical measurements have proved that the discrepancy of indicators characterizing the nutritional value of feed (dry matter content, total protein content, etc.) has a significant influence on the parameters of optical signals. The authors have proposed the functional design of a portable optical analyzer with diodes, which is capable of estimating the nutritional value of feed by the non-contact method for 12 hours running without additional recharging.

The bioreactor of a static mini-model of the artificial gastrointestinal tract of fish will provide modeling of processes in the gastrointestinal tract of industrially grown fish (carp, trout, and sturgeon). The study aimed to determine the thermodynamic processes occurring in the bioreactor and the possibility of using the thermoelectric converter TEC1-12706 in the temperature control system of the bioreactor. The temperature in a bioreactor with a volume of up to 200 ml should vary from 45 to 14℃, the accuracy of maintaining the temperature is 0.1℃. As a result, a mathematical model was obtained with an adjustment according to the identified system parameters, which makes it possible to evaluate thermodynamic processes in the bioreactor, select hardware and create its general mathematical model. The parameters of the Peltier element were identified using a prototype layout measuring the temperature of the cold side of the converter, the hot radiator, the environment, the temperature of the liquid in the reactor, and the current consumed. The operation of the real system took place at an external temperature of 28.31℃; all physical drives were in the temperature equilibrium and under the same initial conditions. A comparison of temperature changes in the real system and the mathematical model obtained as a result of identifying the parameters of the Peltier element showed a non-perfect match of values, but the nature of the temperature change is identical. The following conclusions have been drawn: in the mathematical model, it is necessary to take into account additional drives and flows describing non-ideal conditions of experimental data, for example, thermal reflection of the working surface of the table and partial reflection of air flows. One third of the maximum converter power is sufficient to reduce the temperature of the filled bioreactor by 2 to 3℃. Thus, the thermoelectric converter TEC1-12706 can be used in an in vitro modeling system of the gastrointestinal tract of fish.

Reactive power compensation based on a capacitor plant connected to a rural 0.4 kV distribution network, when using non-specialized contactors, is accompanied by the occurrence of large starting currents of capacitors. In addition, the installation of a conductor connection with load current transformers requires structural modification of the capacitor plant. In order to eliminate these disadvantages, it is proposed to use a capacitor bank controlled by a time relay and protected from inrush currents by three RL circuits. In this case, the “on–off” mode of the capacitor bank must be switched to by an internal signal of the capacitor bank setting the time interval “on–off”. Using a mathematical model, as well as a three-phase physical model with a power of 1.2 kV, the authors studied the behavior of transient and steady-state currents at various values of the parameters of RL circuits. The initial invariant parameters of the model were the reactive resistances of capacitors and inductors. The nominal value of the phase current of the capacitor bank was 2.14 A. The variable parameters were the values of the active resistances of the RL circuits, which took the values of 0, 10, 20, 30 and ∞. The oscillogram of stationary and transient current was studied. As a result, it was found that in order to match the capacitor bank to the criterion of using circuit breakers and contactors of the 0.4 kV network, the resistance value of the RL circuit resistor of each phase of a three-phase capacitor bank should be tenfold higher than the reactance of the current-limiting coil of the RL circuit and be five times less than the reactance value of the power capacitor of the capacitor bank phase. In rural 0.4 kV electric networks, a single 25 kV capacitor plant with simple autonomous control can be installed to compensate for reactive power. Several capacitor plants can compensate for reactive loads of 50 and 75 kVAr.

Exergy analysis of the designed system is necessary to determine the degree of its thermodynamic perfection. The research goal was to evaluate the degree of increasing the efficiency of an installation on an experimental bench heat pump designed to study heat extraction from the back surface of a solar panel and its conversion into useful work. Two methods were analyzed – selection of a refrigerant and analysis of external sources. The analysis of the methods was used to compare the exergy efficiency of a modernized installation, including a heat pump and a solar panel as an additional low-grade heat source, with a laboratory heat pump installation before modernization. The authors performed exergy calculation, fluid selection, and analysis of external sources. It was revealed that the most effective method for assessing the exergy efficiency of new technical solutions is the method of analyzing the external sources. Calculations have established that the energy-efficient operation scheme of a heat pump together with a solar panel leads to the highest efficiency of 23.4%. However, this value is achieved with a large amount of sunlight, an air temperature of about 25℃ and a perpendicular incidence of sunlight on the panel. The exergy of electricity consumed by the electric motor compared to the heat pump before modernization was reduced by 8.92 kJ/kg, and the exergy efficiency of the modernized installation increased by 7.5%. The results prove the effectiveness of redirecting electrical energy to power the compressor. Installing a solar panel and heat pump will improve the environmental situation and save money due to the lack of fuel costs.

Distributed generation is a good solution for areas remote from centralized power supply sources as it helps increase the reliability of consumer operation. Distributed generation power supply systems use renewable sources of electricity, diesel generators and gasoline generators in the form of mobile power stations, which in most cases are not equipped with modern means of protection. This study presents an analysis of existing means of protecting electric generators from abnormal and emergency operating conditions, including voltage asymmetry, which is one of the factors reducing the service life of generators and is typical for rural electrical networks. During the analysis, the authors determined the main types of generator protection against emergency operation modes: protection of stator windings, protection against underfrequency and overfrequency, protection against undervoltage and overvoltage, protection against voltage (current) asymmetry. It is noted that the main cause of voltage asymmetry leading to mechanical vibration and rapid overheating of the rotor is single-phase loads in the system, which are unevenly distributed over three phases. The problem of voltage asymmetry is mainly solved by redistributing loads in transmission lines and/or installing compensating devices. However, in rural power supply systems, unbalanced load distribution is rarely corrected. The voltage asymmetry can be compensated through the use of hybrid active power filters of series compensation and improved control methods of these filters. Voltage converters that are effective in equalizing voltage asymmetry in PV systems can effectively protect small capacity diesel power generators provided that the use of additional equipment is economically viable.