The terms “global warming” and “climate change” refer to the large-scale impacts of human actions such as the burning of fossil fuels and extensive deforestation that contribute to a rise in the level of greenhouse gases in the atmosphere [...]

In a world in which electricity is increasingly necessary, it is vitally important to ensure that the supply of this electricity is safe, reliable, sustainable, and environmentally friendly, reducing CO2 emissions into the atmosphere and the use of fossil fuels [...]

Using solar panels is one of the cleanest ways to generate electricity ever created by mankind. The efficiency of rapidly expanding solar panels decreases during their lifetime for several reasons, such as photodegradation, hot spots, potentially induced degradation, etc. Dirt and debris accumulation on the surface of the solar panels can also significantly contribute to their performance degradation due to the diminishing of the solar radiation reaching their active surfaces. Numerous degradation mitigation methods are cited in the literature. This article briefly outlines these basic measures.

The use of fossil fuels (methane, oil, etc.) is undergoing an unprecedented crisis now. There is the urgent need to search for alternative energy sources. A wide range of degraded organic materials can be effectively used to provide energy together with environmental protection. Soapstock is a hazardous waste containing a high concentration of toxic organic compounds of man-made origin (fatty acids, surfactants, dyes, etc.). To prevent environmental contamination such substances require an effective treatment approach. The goal of the study was to isolate the adapted-to-fatty-acids methanogenic microbiome and investigate the patterns of sodium acetate and soapstock degradation with simultaneous biomethane synthesis. The effectiveness of the degradation of sodium acetate and soapstock by non-adapted and adapted microbiomes was evaluated by decreasing the concentration of dissolved organic compounds. The effectiveness of the fermentation process was determined by the biogas (mixture of C... [more]

Electromagnetic ultrasonic testing technology has advantages in measuring the thickness of pipelines in service. However, the ultrasonic signal is susceptible to corrosions on the internal and external surfaces of the pipeline. Since the electromagnetic ultrasonic signal is nonlinear, and a dynamic model is difficult to establish accurately, in this paper, a new unscented Kalman filter (UKF) method based on a sliding mode observer (SMO) is proposed. The experiments, conducted on five different testing samples, validate that the proposed method can effectively process the signals drowned in noise and accurately measure the wall thickness. Compared with FFT and UKF, the signal-to-noise ratio of the signals processed by SMO−UKF shows a maximum increase of 155% and 171%. Meanwhile, a random assignment method is proposed for the self-regulation of hyper parameters in the process of Kalman filtering. Experimental results show that the automatic adjustment of hyper parameters can be accomplis... [more]

A plethora of multi-functional materials with properties that can be adjusted and tuned to meet the needs of energy storage and conversion has emerged over the last years [...]

The application of wind-generated energy is increasing at a great rate, about 11% per year, with an installed capacity of 837 GW in 2021, and it is the primary non-hydro renewable technology; in many countries, it is the main source of electric energy [...]

This study aimed to reveal the anisotropic permeabilities of tight oil reservoirs impacted by heterogeneous minerals. SEM imaging, image processing, fractal calculation, microscopic reservoir modeling, and visual flow simulation were carried out to investigate the above problems. Results show that the variation coefficient of two-dimensional permeability for the studied tight reservoir samples ranges from 0.09 to 0.95, with an average value of 0.68. The penetration coefficient ranges from 1.16 to 2.64, with an average value of 2.13. The ratio of maximum to minimum permeability is between 1.25 and 7.67, with an average value of 5.62. The fluid flow in tight reservoirs has significant anisotropy comprising dominant flow through conductive channels. Flow in tight oil reservoirs tends to involve minor hydraulic fracturing with no proppant.

Crosswind action on a train poses a risk of vehicle overturning or derailment. To assess if new train designs fulfill the safety requirements, computational fluid dynamics is commonly used. This article presents a comprehensive wind flow analysis on an example of a TGV high-speed train. Large yaw angle range is studied with the application of widely used Reynolds-averaged Navier−Stokes (RANS) turbulence models. The predictive performance of popular RANS-based models in that regime has not been reported extensively before. The context of simulations is a study of crosswind stability using methodology presented in norm EN 14067-6:2018. It is shown that for yaw angles up to 45 degrees, aerodynamic forces predicted by all the studied RANS-based models are consistent with experimental data. At larger yaw angles, flow structure becomes complicated, separation lines are no longer defined by geometry, and significant discrepancies between turbulence models appear, with relative differences bet... [more]

With the advancement of an intellectual and numerical society, the coal mining industry has also begun to change to intelligence. As an important aspect of intelligent coal mine construction, coal mine communication has put forward more stringent standards for communication quality. For the complex communication environment in mines, the transmission of communication signals is always damaged by various noises and interferences, resulting in serious distortion of the communication signals received at the receiving end. Therefore, the use of traditional receivers for information recovery has the problem of high bit error rate (BER), which cannot meet the standard of intelligent coal mine construction. Based on this, the aim of this research is to combine convolutional neural networks (CNN) and multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) communication systems to design an intelligent receiver model for complex mine communication systems. At the receive... [more]

This work presents a multiscale experimental and numerical investigation of CO2 foam generation, strength, and propagation during alternating injection of surfactant solution and CO2 at reservoir conditions. Evaluations were conducted at the core-scale and with a field-scale radial simulation model representing a CO2 foam field pilot injection well. The objective of the experimental work was to evaluate foam generation, strength, and propagation during unsteady-state surfactant-alternating-gas (SAG) injection. The SAG injection rapidly generated foam based upon the increased apparent viscosity compared to an identical water-alternating-gas (WAG) injection, without surfactant. The apparent foam viscosity of the SAG continually increased with each subsequent cycle, indicating continued foam generation and propagation into the core. The maximum apparent viscosity of the SAG was 146 cP, whereas the maximum apparent viscosity of the WAG was 2.4 cP. The laboratory methodology captured transi... [more]

There is an interest in harvesting energy from people’s footsteps in crowded areas to power smart electronic devices with low consumption. The average power consumption of these devices is approximately 10 μW. The energy from our footsteps is green and free, because walking is a routine activity in everyday life. The energy floor is one of the most efficient pieces of equipment in vibration-based energy harvesting. The paper aims to improve the previous design of the energy floor—called Genpath—which uses a rotational electromagnetic (EM) technique to generate electricity from human footsteps. The design consists of two main parts of (1) the EM generator, including the lead-screw mechanism for translation-to-rotation conversion, and (2) the Power Management and Storage (PMS) circuit. The improvement was focused on the part of the EM generator. A thorough investigation of the design components reveals that the EM generator shaft in the previous Genpath design cannot continuously rotate... [more]

Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are the most appropriate alternatives for conventional vehicles (internal combustion engine (ICE)-based) for smart urban transport—as an element of sustainable modes of transportation [...]

The article deals with adding the power of a local object to a solar−wind system when consuming electricity from the grid within the power limit. The parameter’s calculation technique for the different values of degree of power increase was considered. The load schedule, the electricity consumption, use of installed power, boundary conditions of generation, and ensuring energy balance were taken into account. Furthermore, data from the renewable source’s generation archive for the location of the object were used. The control of the power consumed by the object was carried out on the taken values of added and total load power with binding to photovoltaic generation. The added power reference on some time intervals was carried out according to the actual renewable generation power value. This increases the degree of use of the battery capacity and energy from renewable sources. The reference of the added power with the state of battery charge formation was carried out according to the f... [more]

The integration of wind energy into power systems has intensified as a result of the urgency for global energy transition. This requires more accurate forecasting techniques that can capture the variability of the wind resource to achieve better operative performance of power systems. This paper presents an exhaustive review of the state-of-the-art of wind-speed and -power forecasting models for wind turbines located in different segments of power systems, i.e., in large wind farms, distributed generation, microgrids, and micro-wind turbines installed in residences and buildings. This review covers forecasting models based on statistical and physical, artificial intelligence, and hybrid methods, with deterministic or probabilistic approaches. The literature review is carried out through a bibliometric analysis using VOSviewer and Pajek software. A discussion of the results is carried out, taking as the main approach the forecast time horizon of the models to identify their applications... [more]

The treatment of municipal wastewater is considered a cornerstone for the protection of public health and environment. However, a major issue derived from this process is the large quantities of produced sewage sludge. Although anaerobic digestion is a widely applied method in Wastewater Treatment Plants (WWTPs) aiming to stabilize the sludge and to recover energy in the form of methane, it is usually limited due to the reduced decomposition efficiency and slow biodegradation rate of this recalcitrant substrate. For this reason, various pretreatment methods have been proposed aiming to modify the sludge structure, solubilize the organic matter, and decrease the crystallinity of sludge so as to accelerate hydrolysis and consequently enhance methane production. The current research is a comprehensive collection of recent advances in pretreatment technologies that can be potentially applied in wastewater treatment facilities. The critical review analysis presented herein reveals the sever... [more]

Increasing the share of renewable energy in the final energy consumption is a way to ensure independence from external supplies of fossil fuels, which is a fundamental political and economic challenge for many countries nowadays. One such country is Ukraine, which depended on Russian gas supplies and energy (electricity) from nuclear power plants. Russian gas is not delivered anymore to Ukraine, and Russians have recently taken over some of the nuclear power plants. The changes in the political situation force Ukraine to search for alternative energy sources. In countries with high agricultural production potential, one of the basic options seems to be popularization of modern methods of obtaining energy from biomass (bioenergy), which so far has played a minor role in the country’s energy mix (less than 2% in the case of Ukraine). The analysis carried out on the case of the Kyiv Region indicates that the annual economic potential of biomass in the region is equivalent to 1743 thousand... [more]

The design of an adsorption solar air conditioning system is investigated by using a model with an activated carbon−methanol working pair. This system is analysed with the solar insolation levels and ambient temperatures of Singapore. The proposed design mainly consists of two tubular reactor heat exchangers (TRHEXs) operating out of phase and driven by heat from an evacuated tube solar collector (ETSC). The pair of TRHEXs act as a thermal compressor and contain about 2.275 kg of activated carbon per reactor. The evacuated tube solar collector (ETSC) has better performance and is more cost effective than the flat plate solar collector (FPSC), even though it has a higher cost per unit. On the hottest day of the year, the proposed adsorption system has a maximum cooling power of 2.6 kW and a COP of 0.43 at a maximum driving temperature of 139 °C with a 9.8 m2 ETSC area. The system has a total estimated cost of EUR 10,550 corresponding to about SGD 14,800 with a 7-year payback time. At si... [more]

The pressure relief of coal pillars in close-distance multi-coal seam goaf is a complex engineering problem with the characteristics of “dynamic mine pressure”. Hence, this paper studies such problems. First, the influence factors of the coal pillar in the goaf on the mine pressure of the mining face of the lower coal seam under this condition were theoretically analyzed, and it was concluded that vertical stress is the most important element, followed by horizontal stress. Next, a physical similarity simulation experiment was designed to study the stress distribution law of the coal pillar floor in the goaf before and after pressure release and the damage depth. Finally, a technology and monitoring method for coal pillar blasting pressure alleviation in goaf were introduced and implemented in engineering practice. After the pressure is alleviated, the surrounding rock stress of the lower coal seam mining face is redistributed, and the vertical stress is decreased by 20%. The adjacent... [more]

The explosion-proof diesel engine trackless rubber-tyred vehicle (TRTV) has the disadvantages of high fuel consumption and serious exhaust emissions, while the problems of insufficient power and short endurance limit the development of the explosion-proof battery trackless rubber-tyred vehicle. Hybrid technology can effectively reduce fuel consumption and emissions on the basis of ensuring sufficient power. Exploring the application of hybrid electric trackless rubber-tyred vehicle (HETRTV) has practical significance for coal mine auxiliary transportation. The degree of hybridization (DOH) will directly affect the performance and cost of TRTV, which needs to be focused in the development process. The effects of DOH on dynamic performance, fuel economy, emission performance, and cost were studied based on a simulation by ADVISOR, and the results were verified and analyzed by experiment. Compared with the flameproof diesel engine trackless vehicles, HETRTV with the optimal DOH exhausts h... [more]

This study seeks to address the issue of the development factors influencing technological entrepreneurship capabilities of enterprises during the COVID-19 epidemic crisis. This research is particularly relevant in light of the leading role given to innovation and science-oriented technology companies in the economic and epidemiological crisis. This study aims to analyze the impact of the changing environment on the predictors of technological entrepreneurship, assess their impact by the management practice and establish a causal relationship between the used variables. The paper draws on foreign literature review, covering fundamental theoretical fields in international management literature, to develop an integrated research framework. Based on a differentiated approach, the collaborative framework emphasizes a range of network processes and attributes, their interactions and moderating managerial relationships related to their impact on companies’ technological entrepreneurship capa... [more]

The present paper demonstrates a proof-of-concept by introducing a variable guide vane system in the draft tube of a high-head Francis model turbine. The aim is to examine the hydraulic performance of the turbine while mitigating the pressure pulsations in the draft tube. The guide vanes can rotate about an axis up to ±45°. The pressure pulsations mitigation studies were performed at lower- and upper-part loads. The hydraulic performance was examined at all operating ranges within the turbine head. There were six guide vane configurations considered between ±45°. The findings demonstrate that the highest efficiency loss with a guide vane configuration that mitigates the pressure pulsations is marginal, with modest improvements at the best efficiency point. The pressure pulsations are 100% mitigated at the lower part load, and there is a maximum decrement in the pressure pulsations up to 80% at the upper part load. The study demonstrates that such a system can improve the operational fl... [more]

Worldwide need for renewable energy sources increases significantly with the drastic negative greenhouse effects of climate change. This study considers a water-cooled hybrid thermo-electric panel (PV/T) which contributes to better harvesting of solar energy. A numerical CFD model was developed for power generation of a standard PV panel as well as for a water-based PV/T system laminated with polymer matrix composite (PMC) materials, and user-defined functions (UDFs) were developed and integrated with the CFD model to implement exact boundary conditions. Experimentation under daily weather conditions was carried out in order to validate the numerical CFD model by measuring the surface temperatures of PV and PV/T systems as well as the temperatures of the water inlet and outlet of the cooling system. The results show that the maximum and minimum deviations of the surface temperature between numerical and experimental studies matched well compared with the studies performed in the litera... [more]

The continually increasing fossil fuel prices, the dwindling of these fuels, and the bad environmental effects which mainly contribute to global warming phenomena are the main motives to replace conventional transportation means to electric. Charging electric vehicles (EVs) from renewable energy systems (RES) substantially avoids the side effects of using fossil fuels. The higher the increase in the number of EVs the greater the challenge to the reliability of the conventional power system. Increasing charging connections for EVs to the power system may cause serious problems to the power system, such as voltage fluctuations, contingencies in transmission lines, and loss increases. This paper introduces a novel strategy to not only replace the drawbacks of the EV charging stations on the power system’s stability and reliability, but also to enhance the power system’s performance. This improvement can be achieved using a smart demand side management (DSM) strategy and vehicle to grid (V... [more]

The energy sector, along with the conditions of the natural and built environment, are significantly affected by the tremendous increase in total energy consumption [...]