The reliability of a low-voltage asynchronous electric motor is primarily determined by the reliability of the stator winding insulation. Common reasons for the failure of the insulation system are the unsatisfactory quality of the enameled wires and electrical insulating materials used for imperfection and violation of the technological process of winding and insulating work, and the discrepancy between operating modes. In the vast majority of cases, failures occur due to damage to the inter-turn insulation as the weakest element. This causes the need to study the insulation system resistance to the formation of defects. The results of assessing the stability of the insulation of winding wires to defect formation are obtained, taking into account the features of the operational loads characteristic of frequency-controlled drives with pulse-width modulation of the output voltage and the influence of the inter-turn insulation defectiveness level on its reliability indicators is also studied. The authors have developed the measures to reduce the defectiveness of inter-turn insulation at the manufacturing stage and during operation. This will ensure a minimum level of insulation defects and increase the resource of asynchronous electric motors by reducing the number of failures.
To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.
To cool solar panels in hot season, it is necessary to use special cooling devices. The most optimal way of cooling is the use of liquid cooling, realized by means of a pump. This article provides an overview and evaluation of ways to cool solar panels using various devices. The relevance of the research is caused by the need to reduce the temperature of solar panels in order to increase the output power in the hot season. The main aim of the research is to compare and choose the most optimal way to cool solar panels. Methods: comparative analysis, mathematical modeling in the ANSYS environment. Results. Comparative characteristic of TEM, radiators, fans and liquid cooling is given, an example of cooling a solar panel using liquid cooling to spray a liquid flow of 29 l/min is calculated. The panels will cool down from 45 to 35 °C in 4,7 minutes. For one EasySunSolar solar panel with a capacity of 100 W, costing $100, taking into account electrical work, an additional heat sink module will cost about $50.
To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.
In the present work, Al7075 based hybrid composites was developed using stir casting technique. Al7075 hybrid composites with different weight percentage of Mica, Graphite and E-glass fiber were developed to study the effect of these reinforcements on microstructure and mechanical properties, E-Glass fiber is kept constant at 0, 2, 4%, Mica is varied from 1-3% in steps of 1 and Graphite varied from 1-5% in steps of 2. It can be seen that the three peaks corresponding to Al were seen at 38º, 46º and 65º 2θ angles and small peaks related to all the three reinforcement mica, graphite and E-glass fiber were observed in the XRD pattern. Grain size analysis was examined using Clemex Image-Analyzer software, it was observed that decrease in grain size of Al7075 matrix was found to decrease with the increase in reinforcements, Hardness was found to increase with increase in reinforcement content whether it could E-glass fiber from 0% - 4% or mica from 1% - 3% or graphite content from 1% - 5%. Ultimate tensile strength increased with the increase in reinforcement content both before and after heat treatment.
Currently, there are practically no automated systems for controlling power flow within the specified limits when the power line is overloaded by active power. Regulation is assigned to the dispatchers of the power system or is carried out by means of emergency automation, which disconnects consumers. Therefore, an urgent task is to expand the arsenal of tools for automatic control of active power flow in overload mode. Relevance. A significant increase in electricity consumers leads to a complication of the electric power system. The workload for dispatching personnel is increasing. Maintaining the smooth operation of the elements of the power system is a very important and responsible task. In modern electric power industry, timely warning and elimination of overloads of network elements are relevant. The study aims are development and research of an intelligent automatic control system for the flow of active power along a power line based on the mathematical apparatus of fuzzy logic. The system is based on the use of the regulating effect of the load. Research methodology. Methods of calculating static load model during their actualization were used. The method of fuzzy sets was used in the construction of an intelligence control system for active power flows in overload condition. The effectiveness was estimated by expert methods. Results. The use of artificial intelligence methods for automatic regulation of transformer voltage under load allows up to 5–7 % reducing the flow of active power in overload mode.
This review summarizes industrial applications of inorganic and organic polyvalent (hypervalent) iodine compounds. Inorganic iodate salts have found some application as a dietary supplements and food additives. Iodine pentafluoride is used as industrial fluorinating reagent, and iodine pentoxide is a powerful and selective oxidant that is particularly useful in analytical chemistry. Common organic hypervalent iodine reagents such as (dichloroiodo)benzene and (diacetoxyiodo)benzene are occasionally used in chemical industry as the reagents for production of important pharmaceutical intermediates. Iodonium salts have found industrial application as photoinitiators for cationic photopolymerizations. Various iodonium compounds are widely used as precursors to [18F]-fluorinated radiotracers in the Positron Emission Tomography (PET).
The search for pioneering nutraceuticals from plants is genuine and crucial. Based on the literature review as per Ayurvedic texts, four common plants Capparis spinosa L. (flower buds), Caesalpinia bonducella L.(seeds), Luffa acutangula L.(fruits) and Cassia occidentalis L. (aerial parts) were selected to develop nutraceuticals and were standardized. Based on the nutraceutical and pharmacological efficacies of the individual plant drugs selected, three different herbal nutraceutical formulations were prepared. Nutraceuticals before and after lyophilization were subjected to standardization studies. Nutraceutical formulation 3 developed was found to be best due to its high nutraceutical values when compared to others. Results depicted that up to the dose level of 2000 mg/kg.bw (acute oral toxicity), 1000 mg/kg.bw (sub-acute oral toxicity), it doesn’t produced any lethality in the experimental animals. To conclude that the selected herbal formulation developed from selected plant ingredients was found to possess distinct nutraceutical values. The present work contributes for the development of human healthcare through nutraceutical product with remarkable medicinal properties in herbal way.
Supercapacitors (SCs) are used extensively in high-power potential energy applications like renewable energy systems, electric vehicles, power electronics, and many other industrial applications. This is due to SCs containing high-power density and the ability to respond spontaneously with fast charging and discharging demands. Advancements in material and fabrication techniques have induced a scope for research to improve the application of SCs. Many researchers have studied various SC properties and their effects on energy storage and management performance. In this paper, various fractional calculus-based SC models are summarized, with emphasis on analytical studies from derived classical SC models. Study prevails such parameterized resistor–capacitor networks have simplified the representation of electrical behavior of SCs to deal with the complicated internal structure. Fractional calculus has been used to develop SC models with the aim of understanding their complicated structure. Finally, the properties of different SC models utilized by various researchers to understand the behavior of SCs are listed using an equivalent circuit.
During drilling, different problems are encountered that can interfere with smooth drilling processes, including the accumulation of cuttings, reduced penetration rates, pipe sticking, loss of wellbore stability, and loss of circulation. These problems are generally encountered with conventional drilling mud, such as the bentonite–barite mud system. Formation damage is the most common problem encountered in bentonite mud systems with high solid content. In this work, we aimed to formulate two low-solid nondispersed (LSND) muds: carboxymethyl cellulose (CMC)–LSND mud and partially hydrolyzed polyacrylamide (PHPA)–LSND mud. A comparative analysis was performed to evaluate their property enhancements. LSND muds aid in maintaining hole stability and proper cutting removal. The results of this work show that the addition of both CMC and PHPA helps to improve drilling fluid properties; however, the PHPA–LSND mud was found to be superior. Shale swelling is a major concern in the petroleum industry, as it causes various other problems, such as pipe sticking, low penetration rates, and bit wear. The effect of these two LSND polymer muds in inhibiting shale swelling was analyzed using shale collected from the Champhai district of Mizoram, India.
The aim of this work is to substantiate the efficiency of ethyl or isoamyl alcohol application as the third component of coal-water fuels based on the results of experimental study of coaxial spraying. Studies of alcohols influence on spraying characteristics of coal-water fuels can rarely be found in the literature. Instantaneous fields of fuel droplets velocities in several cross-sections of the jet were determined using Particle Image Velocimetry method. Interferometric Particle Imaging method was used to determine droplets distribution by size in the jet of sprayed coal-water fuel. It was experimentally established that substitution of water (no more than 3 % by weight) in the composition of coal-water slurry by fairly typical alcohols leads to decrease in droplet velocities of alcohol-coal-water slurries in comparison with conventional coal-water fuel by 15–18 %. Concentration of sufficiently small fuel droplets (up to 200 microns) increases by 13.4±0.2 % and by 6.6±0.2 % during atomization of alcohol-coal-water slurries with addition of ethyl and isoamyl alcohol, respectively. Introduction of no more than 5 % by weight of the studied alcohols into the coal-water slurry will reduce the cost of fuel by 15–73 % in comparison with fuel oil. Influence of small additives of ethyl and isoamyl alcohol in the composition of coal-water fuel on spraying characteristics proves the possibility of efficient application of such three-component slurries in thermal power engineering. The results obtained are of practical significance, since they illustrate the possibility of reducing the ignition delay time for droplets of alcohol-coal-water slurries after they are sprayed in the furnaces of boiler units.
Solar energy intermittency is one of the main challenges encountered by thermal energy storage systems in concentrated solar power plants due to the low heat transfer rates during charging operations. The critical thermophysical property to be considered for combating this problem is the thermal conductivity. Thus, base fluids with dispersed nanoparticles, better known as nanofluids, have become materials with great potential since they enhance efficiency during charging intervals by increasing the charged material's thermal conductivity by up to 89 %. By gathering and analyzing results from various studies in nanofluids, it was observed that there is a considerable improvement in the thermal storage material compared with the base fluid alone. There is also an increase in the thermal conductivity as nanoparticles are added. Obtaining an increase as great as 99 % allows faster rates of heat transfer. Overall, this may significantly improve the efficiency of thermal energy storage systems in concentrated solar power plants.
The use of photovoltaic power plants is gradually increasing in order to reduce energy costs and greenhouse gas emissions at airports. Airports are suitable settlements for the installation of photovoltaic power plants as they have vast and free of shade areas that are not used in aviation activities. In this study, a 1 MWp photovoltaic power plant is proposed for Gaziantep Airport, Turkey. Performance, economic and environmental benefits of the proposed system were analyzed using the PVsyst simulation tool developed by the University of Geneva in Switzerland. The study demonstrates that Gaziantep Airport is suitable to installation of a grid-connected photovoltaic system and has a high solar energy resource. The proposed photovoltaic power plant at Gaziantep Airport is predicted to operate with an annual electricity generation of 1702.09 MWh, 78.6 % annual average performance ratio (PR), 19.43 % average capacity factor (CF) and 4.67 [h/d] annual average daily final yield.
Photovoltaic (PV) technologies represent a key role in the ongoing energy transition towards the decarbonisation of convectional power systems and to reduce the harmful population impact to environment. Nowadays, the majority of market available photovoltaic PV technologies are silicon based with a usual energy conversion efficiency of less than 20%. The major drawbacks of the widely used silicon PV technologies are related to performance degradation due to aging as well as performance drops that occur during periods of elevated operating temperatures. In order to improve performance, as well as the lifetime of the PV systems, various cooling techniques have been investigated in the last two decades. The main goal of the specific cooling approaches for PV panels is to ensure efficient thermal management, as well as economic suitability. In this review paper, different cooling strategies are categorized, discussed and thoroughly elaborated in order to provide deep insight related to an expected performance improvement and economic viability. The main results of this review indicate that the cooling approaches for PVs can ensure a performance improvement ranging from about 3% up to 30%, depending if passive or active cooling approaches are applied. The main results also indicate that the economic viability as well as environmental suitability of the specific cooling approaches is not sufficiently discussed in the existing research literature.
In this work, we provide a literature review of water treatment techniques and propose a novel resource-efficient solution for the purification of aqueous media from microbiological contamination. Methods: Combined filter sorbents were developed and studied based on novel modified nanostructured filter materials. Synthetic and natural zeolite were used as the mineral base. The production technique was optimized to coat minerals with aluminum oxyhydroxide by means of a sol–gel process. Additional treatment with fine zinc particles obtained by electrospark dispersion was applied to modify the sorbent surface and obtain the surface charge required. Results: The antibacterial, sorption and physicochemical properties of the samples as well as their surface structures were investigated. According to broad microbiological tests, the possibility of purifying bacterial-contaminated water was demonstrated to an acceptable level by means of adsorption filtration. Conclusion: The proposed novel approach for water treatment against bacterial contamination can be considered an alternative to the currently available water treatment technologies.
Relevance: Hypomagnetic conditions have undesirable effects concerning various fields of science and technology. In biology, they cause adverse circumstances, which affect the functioning of living organisms. However, humans experience hypomagnetic fields (HMF) during space exploration, through some branches of production, military objects, and community transport. On the other hand, various high-precision technologies must have or operate under a hypomagnetic field. Aims: We aimed to provide a critical analysis of several ways of preparing hypomagnetic field, differences between hypomagnetic chambers and Helmholtz coils, and review of thematic patents and articles available in the Russian Federation. Methods: We structured and analyzed modern achievements in HMF. Experimental studies on living organisms were evaluated because they show different technical conditions connected to the theme of the hypomagnetic field. Results: Based on this analysis, a new resource-effective technology, which reveals several concerns on the hypomagnetic field, was offered. This technology is essential to be used during preparations for space missions, which require products with special necessities in terms of effectiveness and reliability. Conclusion: We summarized and correlated the results of experiments with possible magnetic conditions, which can occur during space missions and in some military and civil applications. Protection strategies from hypomagnetic conditions were considered. Novel experiments regarding realistic conditions were suggested.
A model of one-dimensional (1D) cold plasma with an external train of rigidly structured bunches with diverse charges has been introduced. In this model, a solution is presented that cancels the wakefield after the train is found. The density of such bunches can be much greater than the density of the plasma, and a high amplitude electrical field arising inside the train can be used for charged-particle acceleration. In addition, analytical and numerical simulations have been performed.
Silver nanoparticles (AgNPs) are synthesized from the root extract of the Abutilon indicum plant. Nitrate reductase enzyme and/or other extra cellular proteins released from the extract reduce the silver nitrate to silver ions. These proteins or enzymes serve as a template for the silver nucleation sites in the development of silver nanoparticles, and also act as capping agents, preventing silver ion agglomeration. XRD analysis predicts the phase of the nanoparticles. Transmission Electron Microscope (TEM) and Scanning Electron Microscope analyses have revealed that the synthesized AgNPs are spherical in shape, with an average size of 17 nm. From the data, it is noted that the protein molecules and fatty acids present in the root extract of Abutilon indicum, play a vital role in reducing silver salts and as capping AgNPs at various concentrations. Bactericidal activity acting against the clinical pathogens was performed, and it was observed that NP inhibition is highly dependent on their size and surface. Cytotoxic studies were carried out with these synthesized silver nanoparticles using MTT assay on MCF-7 cells.
In this work, we aimed to predict possible field production scenarios in case of asphaltene deposition based on field data as well as recommend remediation and stimulation measures to mitigate the risks of asphaltene deposition in the reservoir. We considered the influence of asphaltene formation in the near-wellbore of producers on the production data without reservoir pressure maintenance system in one of the oil fields. The asphaltene envelope in the reservoir oil was obtained, and the operating conditions of the field were evaluated under the possibility of asphaltene deposition. According to the results of dynamic modeling, the pressure map was plotted and the low-pressure areas in the near-wellbore were shown, which contributes to the aggravation of the problem associated with the asphaltene envelope. Based on the geometrical features of the low-pressure area, the dependence of the permeability reduction in the near-wellbore of the production well on the operating time was obtained using the asphaltene deposition model proposed by Wang and Civan. Based on the Buckley-Leverett theory, the field production profiles were calculated with and without asphaltene deposition. A decrease in the oil rate and consequently, the decrease in cumulative oil production in the field is expected due to the damage formation by solids. Maintenance of the production level will be facilitated by treating the near-wellbore with aromatic solvents and maintaining the reservoir pressure above the asphaltene onset pressure.
Due to the rapid growth in the world population, there has been an increase in energy consumption globally. The problem of efficient energy use becomes more relevant and stimulates research and development of new energy and resource-saving technologies. This task is becoming more complicated when the other factors are accounted for, resulting in multiple-factor trade-offs, such as the water-energy-food nexus. This paper highlights the main points for the development of Process Integration in the Commonwealth of Independent States (CIS) countries. It shows the main achievements in the field to date and demonstrates the scientific schools that are working on these problems. A comprehensive review of modern approaches and methods, which are now being developed or have been recently developed, was done. It shows a research gap in Process Integration in CIS and other leading countries. It demonstrates the significant research potential as well as practical applications. The main challenges in process systems engineering and for the sustainable development of industrial energy systems are also discussed. Industry digital transformation, energy transition, circular economy, and stronger energy and water integration are pointed out as priorities in analysis, design, and retrofit of society in the future. A state-of-the-art review in the area of integration of continuous and batch processes, mass integration technologies, and process intensification is presented to show the variety of existing approaches. The necessity of Process Integration development in the CIS is shown to be a necessary condition for building a more sustainable society and a resource-efficient economy.
