Comparative analysis of the profile variability of black soil water-physical properties when long-term applying plowing and no-till technologies use (the case of Panfily Research Station)

The results of actual research on profile variability of soil water-physical properties of undisturbed structure at the plots, where traditional plowing and no-till technology have been applied for 11 years, are given. The comparative research was conducted based on a stationary field experiment, which is carried out at Panfily Research Station of the National Scientific Center "Institute of Agriculture NAAS" when applying a system of laboratory diagnostics of water-physical properties created in the Institute of Water Problems and Land Reclamation of NAAS based on hydrophysical methods. The characteristics of main hydrophysical functions, namely moisture conductivity and water holding capacity, as well as hydrological constants - maximum hygroscopic moisture, withering point, minimal water holding capacity, maximum water holding capacity, specific surface area and active moisture range were obtained for three different depths. Based on the results of comparison, it was found that mesoporosity was more developed in the soil on the plots under plowing, while macroporosity was more developed on the no-till plots. The fundamental result is determining the inversion type of profile distribution of moisture conductivity in unsaturated soil. Thus, under on the no-till plots the highest values of moisture conductivity were observed in the deepest soil layer (0,70-0,85 m), decreasing to the soil surface, while on the plots under plowing the highest values of moisture conductivity were observed in cultivated soil layer (0,00-0,15 m), which naturally decreased in depth. The profile distribution of moisture conductivity on the no-till plots contributed to the infiltration supply of groundwater and capillary feeding of soil root layers from the deeper ones.

Physical and technical aspects of the technology of energysaving drying of wood in chambers with natural circulation of the agent

The problems of energy saving are one of the most urgent problems of modern industry and timber processing is no exception in this. In all wood processing, wood drying stands out for its energy consumption. A possible direction for significantly reducing the energy intensity of wood drying is the use of modes based on the phenomenon of thermal and moisture conductivity in chambers with a natural circulation of the drying agent. The theoretical and experimental studies carried out by the authors made it possible to create a wood drying technology that reduces the energy consumption of the process by 40-45% with a certain (15-17 %) loss in the productivity of drying equipment compared to chambers operating with forced circulation of the drying agent.

Moisture–Conductivity Calibration for Electrical Imaging of Horticultural Substrate

Electrical imaging studies of laboratory- and small-scale plant root zones are gaining increasing attention. However, for essential moisture–conductivity calibrations on numerous substrate columns with variability in dry density, the use of one conventional strategy is relatively laborious or complicated. Thus, in this work, a relatively convenient calibration method is presented, and the objective is to identify its feasibility and potential to assess the effects of factors (e.g., volumetric water content (VWC), and dry density) on conductivity and establish necessary moisture–conductivity curves for porous materials (e.g., soils and substrates). In the method, with a specially designed fixture, variable VWCs, dry densities and related complex conductivities of the samples can be easily acquired through static compaction. The results show that the in-phase conductivity (or magnitude of conductivity) increases with the increasing VWC or dry density, primarily owing to the increase in the dominant pore water connectivity. Moreover, the effect of dry density on conductivity is relatively smaller than that of VWC. Thus, for the substrates at dry densities with certain variability, good power law relations (R2 ≥ 0.99) between in-phase conductivity (or magnitude of conductivity) and VWC at different frequencies can be established. Overall, the proposed approach is practical, promising, and relatively time- and labor-saving.

Possible Directions in the Improvement of Small-Sized Household Drying Plants

The main problem that we have to face in agriculture is processing and storage of agricultural products. One of the most preferred processing methods is drying. The dried product is stored longer, while the requirements for storage conditions are more tolerant. Standard dryers are a sealed chamber where the dried product is located; they work in cycles: loading-drying-unloading. Such characteristics are well suited for small agricultural enterprises. Traditional drying methods, as a rule, involve large energy costs and take a long time. The development of highly efficient drying equipment is possible because of improving the technology and designs of devices that intensify heat and mass transfer, by creating combined dryers and optimal drying schemes, combining the drying process with other processes. (Research purpose) The research purpose is in considering rational methods of physically justified processes of high-intensity drying of agricultural products for the development of effective drying equipment. (Materials and methods) The description of heat and mass transfer processes allows you to choose a rational method; solve the problem of forecasting processes; determine the way to increase the efficiency of drying and equipment. (Results and discussion) The rate of moisture transfer in the material depends on the moving of moisture inside and the surface of the material to the drying agent. The value of the drying speed depends on the temperature, humidity and air speed, the dried air accelerates the drying process. (Conclusions) The magnitude and relative direction of the thermodynamic forces of moisture conductivity and thermal moisture conductivity determines the intensity of material dehydration. For a specific drying method, optimal technological modes of dehydration should be created, ensuring the production of high-quality materials. Closed-cycle devices with recirculation of the drying agent and heat energy recovery reduce the energy consumption for the process.

Oscillating drying of red oak wood blanks

The reasons for the reduction in the price of the lamella made of oak wood have been determined. It is established that during the drying of oak wood at low temperatures there is an accumulation of moisture in the near-surface zone, the so-called “conditional source of moisture”. This leads to the formation of light spots in the middle of the lumber, which have long been in conditions of high air humidity and had a low rate of moisture removal. To avoid this defect, it is proposed to intensify the drying process by using oscillating schedules, which consist of periods of heating and cooling of wood. During the heating period, the temperature of the material gradually rises, the wood receives heat stroke and accumulates heat, drying occurs only due to the moisture gradient. During cooling, the air temperature decreases, the degree of saturation increases and, accordingly, the equilibrium moisture content increases. As a result, the surface layers of the material are moistened, the moisture is leveled along the thickness of the wood, there is a relaxation of drying stresses. In the laboratory, experimental studies of oscillating drying of red oak wood blanks with a thickness of 30 and 50 mm were performed. The amplitude of temperature fluctuations is determined - 30 ° С and the expediency of cyclic heating only until the average moisture content of the material reaches 20%, after which the wood should be dried to the required final moisture content at a constant heating temperature. A method for calculating the duration of oscillating drying is proposed, which takes into account the peculiarities of the kinetics of the periods of heating and cooling of sawtimbers made of red oak wood with a thickness of 30 mm and 50 mm. It is recommended to consider the process of temperature change kinetics as the sum of the processes of cyclic heating, which occurs in polynomial dependence, and cyclic cooling, which occurs in exponential dependence. It is determined that the ratio of the duration of cyclic heating to the duration of cyclic cooling is 1/3. Using heat and mass transfer criteria and the experimentally determined coefficient of moisture conductivity of red oak wood, an adequate model for calculating wood temperature and relative humidity during wood heating and cooling cycles has been developed. Based on the obtained results of theoretical and experimental studies, oscillating drying schedules of red oak blanks of different thickness are proposed, which exclude the formation of white spots in the middle of the material. The process was reduced by 1.5–2.4 times and energy consumption was reduced by 1.53 times. Experimentally determined indicators of residual stresses, the magnitude of the stress difference in the workpieces after drying and the values of the tensile strength showed that the quality of drying corresponds to the I quality category according to DSTU 4921: 2008. Comparison of the obtained values with the maximum allowable values of tensile strength across the fibers in the tangential direction σm = 6.5 MPa showed a margin of safety - 25%, which indicates the possibility of using oscillating drying schedules for high-quality drying of red oak wood blanks. Keywords: Red oak (Quercus rubra), moisture conductivity coefficient, oscillating schedules, drying quality, drying duration.

THE TRANSFORMATION OF SOIL-RECLAMATION PROCESSES WHEN CHANGING THE WATER BALANCE OF AGRICULTURAL LANDSCAPES OF THE LOWER POVOLGHYE (VOLGA REGION)

The article presents the results of a study of the peculiarities of transformation of soilreclamation processes in agricultural landscapes of the Lower Volga region under the influence of changes in the water balance during irrigation and subsequent cessation of irrigation. The increase of the income part of water balance due to irrigation in an adverse combination of poor drainability, weak filtration capacity waterbearing rocks and mineralization of ground waters leads to the development of adverse processes in soils, like a rise of groundwater and salinization. It is proved that the changes in the water supply from automorphic type to hydromorphic type and the changes in the composition of the soil-absorbing ratio significantly transform the main hydrophysical characteristic and moisture conductivity functions of zonal soils, which are required for forecasting water and salt regimes of soils. It is proved that the nature of changes in the salt regime of long-irrigated soils degraded as a result of secondary salinization after being removed from agricultural use is determined by the drainage of territories. It is established that self-reclamation of soils of saline fallow areas occurs if drainage ensures the exclusion of groundwater participation in the water regime of the root layer, which is important to take into account for the involvement of abandoned areas in agriculture.

Research of Hygienic Properties and Choice of Materials for Workwear at Electricity Industry

One of the main tasks solved at the stage of designing workwear is the choice of materials whose hygienic properties correspond to specific operating conditions. By occupation and depending on climatic conditions, a person can be exposed to various kinds of negative and dangerous influences. Given this, this article is devoted to the study of hygienic properties and the choice of workwear materials for electric power engineers. Analysis production conditions of enterprises of the electric power industry, showed that the presence of distributed electric charges that create electrostatic fields, cause a high electrostatic hazard and negatively affect the human body. The article presents the results of laboratory tests of air permeability, hygroscopicity, moisture conductivity and thermal resistance of materials, gives recommendations for selection optimal thickness of materials for workwear and operation in hot climates. Based on the results of the analysis of works devoted to the development of clothing for hot climatic conditions, the results of thermophysical studies are given.

Innovative technologies for low-rise construction

The article presents the results of the implementation of promising areas of construction and construction of low-rise buildings. The problems of improving the environmental safety and financial stability of agricultural construction through the implementation of effective systems that provide energy conservation, the creation of comfortable conditions in the rooms are considered. It is noted that a factor that has been given special attention in recent years is the environmental safety of the materials used and the reduction of the negative load on the environment of systems using these materials. The article provides the rationale that the heat-efficient system should not only be based on the use of materials with low thermal conductivity, but should also suggest a reasonable minimization of the joints between the products included in the insulation sheath and between products and structures. In constructions with the use of polyethylene foam, seamless insulating sheath is formed, which has high thermal resistance. The low vapor and wind permeability and moisture conductivity of polyethylene foam makes it possible to dispense with the construction without additional vapor barrier and wind protection, which improves the performance of the casing and its durability due to the reduction in the complexity of manufacturing wall structures.