Water scarcity is a major issue in cities situated at the Caspian regions of Kazakhstan. To overcome this issue, two compression heat pump-assisted solar thermal desalination configurations are proposed in this research. A numerical model using the TRNSYS simulation package was developed to predict the energy performance of the proposed systems and was validated with experimental results available in the open literature. The influence of ambient parameters and water depth in the basin of a solar still and insulation thickness was analyzed. The performance of proposed configurations is compared with conventional solar still. The errors noticed at 2 and 10 cm depths are 23.6% and 12.1%, respectively. The simulation results confirmed that the heat pump-assisted regenerative solar still configuration has a 91.1%, 73.0%, 61.6% and 82.6% improved productivity during winter, spring, summer and autumn climates, respectively. The results confirmed that significant improvement in freshwater production was observed with heat regeneration compared to the configuration without heat regeneration. The maximum freshwater production with heat regeneration reached 18.0 kg m−2 day−1 in summer and 9.0 kg m−2 day−1 in winter. The optimal water depth in the basin is observed to be in the range between 0.5 and 2.0 cm, while the insulation thickness is between 5.0 and 7.0 cm. The results confirmed that the proposed configuration satisfies the water requirements in Kazakhstan. © Akadémiai Kiadó, Budapest, Hungary 2024.

The object of the study is the methods of radio frequency resource management in stratospheric communication systems based on high altitude platform stations (HAPS). The problem addressed is the limited radio frequency spectrum, frequency overlap with fifth- and sixth-generation (5G/6G) networks, and the high probability of interference, which complicate efficient spectrum utilization and coordination. The obtained results indicate that within the frequency bands recommended by the International Telecommunication Union (ITU) – 21.4–22.0 GHz, 24.25–27.5 GHz, 47.2–47.5 GHz, and 47.9–48.2 GHz – the probability of interference reaches up to 70% in the 27.5–28.35 GHz band. By applying cognitive radio (CR) technology, interference levels decreased by 60%, and spectrum utilization efficiency increased by 35%. Dynamic spectrum access (DSA) improved spectrum efficiency by 30–45%, while spectrum sharing methods enhanced it by 40–60%. A brief explanation of the results shows that the proposed management approaches significantly increase the efficiency of radio frequency resource use and substantially reduce interference. For example, at a bandwidth of 100 MHz and a signal-to-noise ratio (SNR) of 10, the channel capacity reached approximately 332 Mbps. The distinctive features of the results lie in the comprehensive use of modern technologies that effectively address spectrum scarcity and interference issues, ensuring compatibility of HAPS with existing terrestrial and satellite communication systems. The proposed approaches are suitable for implementation in international and national spectrum coordination and licensing frameworks aimed at expanding broadband connectivity in underserved regions Copyright

This paper proposes a robot designed for automated routine or emergency disinfection in closed premises. The robot is related to the combined type robots. The robot consists of two functional parts: a universal mobile platform (lower part) and a disinfector (upper part), which, if necessary, can be freely moved by personnel on 4 wheels. In the initial position, the upper part of the disinfection robot is at the charging station. The mobile robot drives up to the disinfector, «hooks» it (puts it on itself) and moves along the planned route. The upper part of the disinfector will have its own independent intelligent system, separate from the mobile robot, which, when a person is recognized, stops liquid disinfection: in this case, the UV lamps turn through 180°, the cylindrical body closes and ventilation of the disinfected air from the enclosed space is turned on. In addition, liquid disinfection is only enabled when detecting beds, tables and chairs. With the spray nozzles located at a height of 400 mm, the disinfector can carry out a simultaneous combined treatment of rooms with equipment and furniture, including high-quality processing of the lower surfaces of tables, chairs and beds. To improve the functional characteristics of robotic disinfectors and to simplify their design, a multifunctional robotic disinfector has been proposed. It was found that the result is achieved by the fact that in a multifunctional disinfection robot containing a mobile cart with an autonomous positioning and navigation system, a disinfection platform with a disinfection liquid spraying system and UV lamps with reflectors installed on it, the disinfection platform will have its own autonomous control and power systems © 2022, Eastern-European Journal of Enterprise Technologies. All rights reserved.

This study investigates the surface modification of commercial activated carbon “BAU-A” through liquid-phase oxidation using hydrochloric acid to enhance its structural and physicochemical properties. The treatment introduces various oxygen-containing functional groups, including hydroxyl, phenolic, carboxylic, lactone, and quinone groups, as confirmed by IR spectroscopy. These chemical changes significantly influence the morphology and surface organization of the carbon material. Structural analysis shows changes in pore characteristics and a reduction in certain pore volumes, while X-ray diffraction results indicate a decrease in crystalline mineral phases associated with elements such as sodium, calcium, and magnesium, suggesting effective demineralization.

Dye wastewater pollution has become a significant environmental issue threatening aquatic ecosystems and human health. To achieve green and efficient removal of organic dye (e.g., methylene blue (MB)), bio-based magnetic composite beads (Fe3O4/SiO2@SA) were prepared through HCl-assisted SiO2 extraction, co-precipitation and ion-crosslinking under mild conditions, without high pressure, high reaction temperature or toxic chemicals. Batch adsorption studies of MB were used to explore the adsorption performance and mechanism of Fe3O4/SiO2@SA. The experimental results demonstrate that the MB removal rate of Fe3O4/SiO2@SA composite beads reaches 91.75% under optimised adsorption conditions (25 ℃, pH 9, 100 mg/L initial MB concentration, 20 mL solution volume, and 10 mg adsorbent dosage). Compared to Fe3O4 and Fe3O4/SiO2 powders, the adsorption capacity is much higher at 183.77 mg/g. Physisorption and monolayer adsorption were demonstrated. The optimal adsorption capacity of Fe3O4/SiO2@SA on MB is 925.77 mg/g. In addition, Fe3O4/SiO2@SA enabled rapid and efficient solid-liquid separation through an external magnetic field and exhibits excellent reusability. The removal efficiency stayed at 80.1% after six cycles of adsorption and desorption, and reached 81.1% in river water. The Fe3O4/SiO2@SA composite beads possess excellent adsorption capability, rapid magnetic separability and good reusability, providing a sustainable solution for dye water treatment. This research provides novel viewpoints and experimental supports for the evolution of low-cost, recyclable, environmentally friendly adsorbents.

This study addresses the development of an optimized seed encapsulation (pelleting) system for sunflower seeds to improve resistance against phytopathogens and pests while reducing reliance on conventional fungicides. The research focuses on selecting a cost-effective encapsulating composition based on gelatin and polyvinyl alcohol (PVA), combined with commercial fungicidal agents “Maxim” and “Kruizer.” The work evaluates the ability of the coating to enhance seed protection, support early plant development, and improve germination conditions under adverse environmental factors.

В растениеводстве большое значение имеет применение различных микроэлементов для обработки семян, которые оказывают стимулирующее действие рост и развитие растений. В данной статье приведены результаты влияния предпосевной обработки семян сои агроминералами на основе бентонита таган и биостимуляторов фунгицидного действия, который состоит из комплексов янтарной кислоты и этилендиамина янтарной кислоты с ионами серебра и меди в сочетании с пленкообразующим веществом крахмалом на хозяйственно полезные качества культуры. Выявлено различное влияние агроминералов на вегетационный период развития сои, урожайность, на массу 1000 семян, количество бобов на растениях, содержание белка и жира в семенах. Установлено, что предпосевная обработка отдельными комплексами SA-Сu SA-Ag, и Starch-SA-Cu приводит к сокращению вегетационного периода на 5-8 дней, агроминерал на основе Tgn-EDSA-Ag-Starch и Tgn-EDSA-Cu- Starch наоборот увеличивает длину вегетационного периода на 4-7 дней. Получена прибавка урожая на 3,1-3,5 ц/га (Нур+) и 3,0-4,1 ц/га (Прогресс) по сравнению с контролем. Так же отмечено влияние агроминералов на массу 1000 семян, количество бобов на растениях, содержание белка и жира в семенах.

The purpose of the present work was to determine the thermal performance of borehole heat exchangers, considering the influences of their geometric configurations and the thermophysical properties of the soil, grout and pipe wall material. A three-dimensional model was developed for the heat and mass transfer in soil (a porous medium) and grout, together with one-dimensional conductive heat transfer through the pipe walls and one-dimensional convective heat transfer of the heat transfer fluid circulating in the pipes. An algorithm was developed to solve the mathematical equations of the model. The COMSOL Multiphysics software was used to implement the algorithm and perform the numerical simulations. An apparatus was designed, installed and tested to implement the thermal response test (TRT) method. Two wells of depth 50 m were drilled in the Almaty region in Kazakhstan. Gravel and till/loam were mainly found, which are in accordance with the stratigraphic map of the local geological data. In each well, two borehole heat exchangers were installed, which were an integral part of the ground source heat pump. The TRT measurements were conducted using one borehole heat exchanger in one well and the data were obtained. The present TRT data were found to be in good agreement with those available in literature. The numerical results of the model agreed well with the present TRT data, with the root-mean-square-deviation within 0.184 °C. The TRT data, together with the predictions of the line-source analytical model, were utilized to determine the soil thermal conductivity ((Formula presented.) = 2.35 W/m K) and the thermal resistance of the borehole heat exchanger from the heat transfer fluid to the soil ((Formula presented.) = 0.20 m K/W). The model was then used to predict the efficiencies of the borehole heat exchangers with various geometric configurations and dimensions. The simulation results show that the spiral borehole heat exchanger extracts the highest amount of heat, followed by the multi-tube, double U-type parallel, double U-type cross and single U-type. It is also found that the spiral configuration can save 34.6% drilling depth compared with the conventional single U-type one, suggesting that the spiral configuration is the best one in terms of the depth and the maximum heat extracted. The simulation results showed that (i) more heat was extracted with a higher thermal conductivity of grout material, in the range of 0.5–3.3 W/m K; (ii) the extracted heat remained unchanged for a thermal conductivity of pipe material higher than 2.0 W/m K (experiments in the range of 0.24–0.42 W/m K); (iii) the extracted heat remained unchanged for a volumetric flow rate of water higher than 1.0 m3/h (experimental flow rate 0.6 m3/h); and (iv) the heat extracted by the borehole heat exchanger increased with an increase in the thermal conductivity of the soil (experiments in the range of 0.4–6.0 W/m K). The numerical tool developed, the TRT data and simulation results obtained from the present work are of great value for design and optimization of borehole heat exchangers as well as studying other important factors such as the heat transfer performance during charging/discharging, freezing factor and thermal interference. © 2022 by the authors.

This study presents the synthesis and characterization of a nickel nanocatalyst supported on acid-modified activated carbon (ACm) prepared via the wet impregnation method for the hydrodechlorination of Polychlorinated Biphenyls. Commercial activated carbon BAU-A was treated with hydrochloric acid to enhance surface functionality and improve metal anchoring. Spectroscopic analysis revealed that carboxyl and carbonyl groups on the modified carbon surface play a key role in stabilizing nickel nanoparticles. The catalyst exhibits a highly developed porous structure, with nickel nanoparticles dispersed within micro- and mesopores, ensuring high accessibility of active sites. The catalyst achieved a 84.21% conversion of 2,2′,3,3′,4-pentachlorobiphenyl, demonstrating strong catalytic efficiency toward persistent organic pollutants.

Typical leg exoskeletons employ open-loop kinematic chains with motors placed directly on movable joints; while this design offers flexibility, it leads to increased costs and heightened control complexity due to the high number of degrees of freedom. The use of heavy servo-motors to handle torque in active joints results in complex and bulky designs, as highlighted in the existing literature. In this analytical study, we introduced a novel synthesis method with analytical solutions provided for synthesizing the lower-limb exoskeleton. Furthermore, we proposed a mathematical model of multicriteria optimization; as a result, we obtained several lower-limb exoskeleton mechanisms comprising only six links, well-suited to the human anatomical structure, exhibit superior trajectory accuracy, efficient force transmission, satisfactory step height, and having internal transfer segment of the foot. © 2023 by the authors.