Vladyslav Shubenko

This study focuses on the physical modelling of the aggregate composition of the arable soil horizon in order to evaluate its effect on the yield of winter wheat. It is hypothesised that the maximum possible yield can be achieved under the soil and climatic conditions of southern Ukraine on South Ukrainian chernozem if the arable horizon has a varying aggregate composition with tillage depth. It has been established that the arable horizon must have a layer-specific aggregate composition in order to achieve this maximum yield. Three layers can be distinguished: above-seed layer, where 10–20 mm aggregates account for around 55 per cent; the seed layer, where 0.25–5 mm aggregates account for around 80 per cent; and the sub-seed layer, where 20–50 mm aggregates account for around 60 per cent. This information can be used to evaluate existing mechanised technologies and to develop new soil tillage technologies and tools for tillage machines adapted to the local soil and climatic conditions of southern Ukraine. The practical significance of the research findings lies in their application to modelling soil tillage processes and developing new technical and technological solutions related to soil cultivation.

The object of the present research is a machine-tractor unit based on a tractor consisting of an energy (high-energy tractor—EM) and a technological (additional traction axle—TM) module. This tractor uses three-row crop cultivators, each with an operating width of 4.2 m. One of these cultivators is attached centrally to the technological module, and the other two are connected to the sides of the energy module in its front part. The research aimed to determine the influence degree of such a unit scheme and design parameters on the stability of its movement in the horizontal plane. The theoretical analysis was performed using amplitude (AFC) and phase (PFC) frequency characteristics obtained based on the developed mathematical model of the modular unit movement when it processes a disturbing effect. The difference in traction resistances of the unit’s side cultivators was adopted as the latter. Finally, it was established that blocking the vertical hinge of the TM contributes to a significant increase in the unit motion stability. The practical implementation of this method of joining EM and TM in the horizontal plane allows the unit to work out a disturbing influence in the frequency range 0.65–5.50 s⁻¹ to eliminate the resonant AFC peaks and reduce their value. When the TM hinge is locked at a torque oscillation frequency of 2.5 s⁻¹, the AFC is 2.82 times less than when it is free. Blocking the TM vertical hinge increases the delay in the unit’s response to a disturbance. At an oscillation frequency of the latter of 1.5 s⁻¹, this delay is 0.6 s, and at a frequency of 0.5 s⁻¹, it increases by more than three times, reaching a level of 1.9 s.

The object of this study is photovoltaic modules with different seasonal tilt angles at different geographical latitudes. The average annual efficiency of photovoltaic modules with different seasonal angles set at different geographical latitudes has been determined as the annual weighted average value of the cosine of the angle of incidence of solar rays on the plane of the photovoltaic module. The influence of seasonal tilt angles of photovoltaic modules at different geographical latitudes on their average annual efficiency was analyzed. Approximate values of the seasonal tilt angles of photovoltaic modules at different geographic latitudes take values that differ from the geographic latitude value by plus 15° for the winter period and minus 15° for the summer period. Modeling the average annual efficiency of photovoltaic modules depending on the seasonal tilt angles at different geographical latitudes made it possible to obtain refined values of the seasonal tilt angles of photovoltaic modules. Thus, at the latitude of 0°, 10°, 20°, 30°, 40°, 50°, and 60°, the tilt angle of photovoltaic modules for the winter period will be 14.8°, 24.6°, 34.5°. 44.4°, 54.1°, 63.6°, and 73°, respectively, and for summer ‒ minus 14.5°, minus 4.6°, 5°, 15.1°, 25.1°, 34.9°, and 44.7°. Dependences were obtained for determining the seasonal tilt angles of photovoltaic modules depending on the value of geographic latitude. The difference in the average annual efficiency of photovoltaic modules, which are installed at seasonal angles, and photovoltaic modules, which track the position of the Sun in the vertical plane, is 0.4 %. The results could be used as a basis for evaluating the efficiency of photovoltaic modules when determining the seasonal tilt angle at different geographic latitudes

The article presents the results that can be a prerequisite for the introduction of a pre-sowing electrotreatment of winter rape seeds into the production process. The results of photon emission by rape seeds after electrical stimulation are highly correlated with the data obtained during determination of its sowing qualities and field germination. Absorption and transformation of the energy of the external electric field during the electrostimulation of winter rape seeds occurs non-linearly. It was established that the main transformations take place during the first 15 s, regardless of the electric field intensity. Relaxation processes were revealed, which become dominant after 15 s of electrical stimulation. The pre-sowing electrical stimulation improved the sowing properties of winter rapeseed. The highest values of germination energy and laboratory germination (87% and 96%), which exceeded the control by 9% and 8%, were obtained under the treatment mode E=2 kV·cm ⁻¹ , t=30 s. Pre-sowing electrostimulation of winter rape seeds at optimal conditions helps to increase its field germination. Under the treatment mode E=2 kV·cm ⁻¹ , t=30 s was 90%, and with E=3 kV·cm ⁻¹ , t=30 s – 83% versus 79.7% in the control.

The object of this study is the process of soil compaction with ring-spur and ring-tooth rollers. Based on the zonal optimization of the agrophysical parameters of the arable horizon, the influence of the rolling working bodies on the soil environment in terms of creating a uniform set layer density during pre-sowing tillage was investigated. It was established that soil density should be evaluated in a zonal section together with its aggregate composition, humus content, moisture, etc. Smooth-water-filled, ring-tooth, and ring-spur rollers were studied. The use of a smooth water-filled roller in previous studies contributed to the high unevenness of the compaction of the upper and lower layers of the arable horizon, which indicated the impracticality of further experiments. The research of ring-tooth and ring-spur rollers was carried out by the method of a multifactorial experiment under defined soil and climatic conditions (soil type, sod-podzolic; layer-by-layer soil moisture, 26...28 %; layer-by-layer soil density, 0.96...1.25 g/cm3). Regression models were built of the influence of the specific load, the frequency of passes, and the working speed of the unit on the density of the soil in layers: 0–5; 5–10; 10–15; 15–20; 20–25; 25–30 cm. To assess the heterogeneity of soil density in layers 0–5 and 5–10 cm, a data array was constructed. It was established that the ring-spur roller, even at a speed of up to 6 km/h, is not a tool suitable for regulating the equilibrium density of the seed layer. The best for pre-sowing soil cultivation is a ring-tooth roller (specific soil load, 350 kg/m; unit speed up to 6 km/h). The derived regression equations make it possible to select such a specific load on the ring-tooth roller that could provide a rational value of the layer density of the soil. This is economically and environmentally expedient.