Recently, controlling a wind energy conversion system (WECS) under fluctuating wind speed and enhancing the quality of power delivered to the grid has been a demanding challenge for many researchers. This paper provides a comprehensive review of synchronous generator-based WECSs. This paper will investigate the growth of wind energy in Egypt and throughout the world, as well as the technological and financial significance of wind energy. The block diagram of a typical grid-connected WECS, power control techniques, characteristic power curve-based maximum power point tracking (MPPT), and MPPT techniques are also presented in this study. Moreover, this study compares different power converter topologies for grid-connected and independent WECSs that use a permanent magnet synchronous generator (PMSG).

This paper presents the first approach to a current control problem for the direct matrix converter (DMC), which makes use of the deep reinforcement learning algorithm. The main objective of this paper is to solve the real-time capability issues of traditional control schemes (e.g., finite-set model predictive control) while maintaining feasible control performance. Firstly, a deep Q-network (DQN) algorithm is utilized to train an agent, which learns the optimal control policy through interaction with the DMC system without any plant-specific knowledge. Next, the trained agent is used to make computationally efficient online control decisions since the optimization process has been carried out in the training phase in advance. The novelty of this paper lies in presenting the first proof of concept by means of controlling the load phase currents of the DMC via the DQN algorithm to deal with the excessive computational burden. Finally, simulation and experimental results are given to dem... [more]

Electricity generation using distributed renewable energy systems is becoming increasingly common due to the significant increase in energy demand and the high operation of conventional power systems with fossil fuels. The introduction of distributed renewable energy systems in the electric grid is crucial for delivering future zero-emissions energy systems and is cost-effective for promoting and facilitating large-scale generation for prosumers. However, these deployments are forcing changes in traditional energy markets, with growing attention given to transactive energy networks that enable energy trading between prosumers and consumers for more significant benefits in the cluster mode. This change raises operational and market challenges. In recent years, extensive research has been conducted on developing different local energy market models that enable energy trading and provide the opportunity to minimize the operational costs of the distributed energy resources by promoting loc... [more]

Wave energy provides a renewable and clear power for the future energy mix and fights against climate change. Currently, there are many different wave energy converters, but their costs of extracting wave energy are still much higher than other matured renewables. One of the best indicators of calculating the generating cost of wave energy is the ‘levelized cost of energy’ (LCOE), which is the combined capital expenditure (CAPEX), operational expenditure (OPEX), and decommissioning cost with the inclusion of the annual energy production, discount factor, and project’s lifespan. However, the results of the LCOE are in disagreement. Hence, it is important to explore the cost breakdown of wave energy by the wave energy converter (WEC), so for finding potential ways to decrease the cost, and finally compare it with other renewable energies. Different WECs have been installed in the same place; the Wave Dragon LCOE platform is the best one, with an energy conversion of EUR 316.90/MWh, follo... [more]

As a major component in electric power systems, power transformers are one of the most expensive and important pieces of electrical equipment. The trouble-free operation of power transformers is an important criterion for safety and stability in a power system. Technical diagnostics of electrical equipment are a mandatory part of preventing accidents and ensuring the continuity of the power supply. In this study, a complex diagnostic methodology was proposed and applied for special power transformers’ risk estimation. Twenty special power transformers were scored with the proposed risk estimation methodology. For each transformer, dissolved gas analysis (DGA) tests, transformer oil quality analysis, visual inspections of all current equipment on-site and historical data for the operation of each electrical research were conducted. All data were collected and analyzed under historical records of malfunctioning events. Statistical data for expected fault risk, based on long-term records,... [more]

In this paper, we present the development of a non-linear model predictive controller for the trajectory tracking of a quadrotor using the CasADi optimization framework. The non-linear dynamic model of the quadrotor was derived using Newton−Euler equations, and the control algorithm and drone dynamics were wrapped in Matlab. The proposed controller was tested by simulating the tracking of a 3D helical reference trajectory, and its efficiency was evaluated in terms of numerical performance and tracking accuracy. The results showed that the proposed controller leads to faster computational times, approximately 20 times faster than the Matlab toolbox (nlmpc), and provides better tracking accuracy than both the Matlab toolbox and classical PID controller. The robustness of the proposed control algorithm was also tested and verified under model uncertainties and external disturbances, demonstrating its ability to effectively eliminate tracking errors.

The currently still high fossil energy demand is forcing the glass industry to search for innovative approaches for the reduction in CO2 emissions and the integration of renewable energy sources. In this paper, a novel power-to-methane concept is presented and discussed for this purpose. A special focus is on methods for the required CO2 capture from typical flue gases in the glass industry, which have hardly been explored to date. To close this research gap, process simulation models are developed to investigate post-combustion CO2 capture by absorption processes, followed by a techno-economic evaluation. Due to reduced flue gas volume, the designed CO2 capture plant is found to be much smaller (40 m3 absorber column volume) than absorption-based CO2 separation processes for power plants (12,560 m3 absorber column volume). As there are many options for waste heat utilization in the glass industry, the waste heat required for CO2 desorption can be generated in a particularly efficient... [more]

We analyze crude oil’s dependence and the risk spillover effect on the Chinese stock market and the gold market. We compare both static and dynamic copula functions and calculate the average upward and downward spillover effect using the time-varying Copula model and the conditional value-at-risk approach. By utilizing daily data on crude oil prices, China’s stock market, and the gold market, we observe an asymmetric spillover effect: the downside spillover effects from crude oil prices on the Chinese stock market and gold market are larger than the upside spillover effect. We then identify changes in the structure of the sample periods and calculate the dynamic conditional correlation between them. In addition, we explore the optimal weight and hedge ratios in diversified portfolios to mitigate potential risks. Our results suggest that investors and portfolio managers should frequently adjust their portfolio strategies, particularly during extreme events like COVID-19, when financial... [more]

Although the end of combustion engine vehicles seems inevitable under a new climate target for 2030, a complete ban on the combustion engine would be counterproductive. E-fuels, which are produced using renewable electricity from hydrogen and carbon dioxide, could act as a possible large-scale solution for achieving climate-neutral mobility, as they allow us to reduce greenhouse gas emissions while leveraging the existing energy infrastructure. Against such a background, it is critical to examine how the related technological landscape is constructed and might affect the subsequent knowledge generation. By adopting a social-network perspective, the aim of this study is to investigate the degree of technological knowledge relatedness of e-fuel technology using patent data. This is accomplished by analyzing the influence of individual knowledge areas and categorizing them into a matrix model, with each quadrant playing a unique role. The main findings show that the patent landscape is do... [more]

Electric vehicles could be a significant aid in lowering greenhouse gas emissions. Even though extensive study has been done on the features and traits of electric vehicles and the nature of their charging infrastructure, network modeling for electric vehicle manufacturing has been limited and unchanging. The necessity of wireless electric vehicle charging, based on magnetic resonance coupling, drove the primary aims for this review work. Herein, we examined the basic theoretical framework for wireless power transmission systems for EV charging and performed a software-in-the-loop analysis, in addition to carrying out a performance analysis of an EV charging system based on magnetic resonance. This study also covered power pad designs and created workable remedies for the following issues: (i) how power pad positioning affected the function of wireless charging systems and (ii) how to develop strategies to keep power efficiency at its highest level. Moreover, safety features of wireles... [more]

WCO-Biodiesel can be used as a fuel instead of fossil energy for the copper smelting industry will not only save resources but also protect the environment. The pyrolysis of WCO-Biodiesel in the melting pool is influenced to some extent by the copper slag (CS) generated during the copper smelting process. In this study, the effects of CS on the kinetic triplet, thermodynamics, product characteristics and reaction mechanism of WCO-Biodiesel are comprehensively investigated via a thermogravimetric analyzer and pyrolysis experimental system. Firstly, the apparent activation energy (Eα) is calculated using STR, and Eα decreased at different α under the influence of CS. Then, the trend of the WCO-Biodiesel pyrolysis mechanism with α is determined by the master plots method based on 18 commonly used models similar to the Pn and D1 models. The analysis of WCO-Biodiesel pyrolysis gas products shows that more flammable gases containing H are formed under the influence of CS. The analysis of the... [more]

The adoption of renewable energy remains Sub-Saharan Africa’s best option to achieve sustainable growth and mitigate climate change. The essence of this study is to examine the factors that determine the adoption of renewable energy adoption in Africa by employing the System Generalized Methods-Of-Moment (GMM) to analyze data sourced from 1990 to 2019 on some selected African economies. The study examined the tripartite role of the economic, environmental, and socio-political factors on renewable energy adoption in Africa and noted that a positive relationship exists between economic and renewable energy adoption, supporting the validity of the feedback hypothesis. Hence, a policy that supports simultaneous growth of the economy and renewable energy could be adopted. The results further show that environmental factors such as carbon emission and ecological footprint negatively impact renewable energy (RE) adoption in Sub-Saharan African economies. The impact of socio-political factors... [more]

Reservoir lithology identification is the basis for the exploration and development of complex lithological reservoirs. Efficient processing of well-logging data is the key to lithology identification. However, reservoir lithology identification through well-logging is still a challenge with conventional machine learning methods, such as Convolutional Neural Networks (CNN), and Long Short-term Memory (LSTM). To address this issue, a fully connected network (FCN) and LSTM were coupled for predicting reservoir lithology. The proposed algorithm (LSTM-FCN) is composed of two sections. One section uses FCN to extract the spatial properties, the other one captures feature selections by LSTM. Well-logging data from Hugoton Field is used to evaluate the performance. In this study, well-logging data, including Gamma-ray (GR), Resistivity (ILD_log10), Neutron-density porosity difference (DeltaPHI), Average neutron-density porosity(PHIND), and (Photoelectric effect) PE, are used for training and... [more]

The Gippsland Regional Aquatic Centre (GRAC) opened in the town of Traralgon, Victoria, Australia early in 2021. The GRAC utilizes a geothermal energy heating system as an alternative to conventional natural gas furnaces. We have examined 12 full months of heat production from the geothermal system of the GRAC and compared its economic performance against equivalent heat production by natural gas. The geothermal system—the first of its kind in Victoria—operated at >95% availability over its first year of operation. Our economic assessment indicates that the breakeven price for the geothermal energy is about 35% the equivalent price of natural gas and the payback period for the geothermal system is about five years. The results justify the initial capital outlay by Latrobe City Council and are likely to stimulate further development of geothermal heat systems in the region.

In order to study the mechanical characteristics and seepage mechanism of the structural plane under the action of seepage water pressure, the shear−seepage coupling test was carried out. It was found that with an increase in seepage water pressure, the peak shear strength, and shear stiffness of the structural plane decreased, while the peak dilatancy angle, average dilatancy angle, peak shear displacement, initial flow rate, and peak flow rate increased. The profile JRC and 3D morphology parameters under different Y values increased as seepage water pressure increased, indicating that the wear degree of the structural plane decreased. The contact area, effective aperture, average aperture, and hydraulic aperture of the structural plane all increased in phase with the increase in shear displacement, and they all increased in trend with the increase in seepage water pressure. The distribution and evolution law of the structural plane aperture were analyzed by programming using scanning... [more]

Pool boiling, enabling remarkable phase-change heat transfer, has elicited increasing attention due to its ubiquitous applications in solar thermal power stations. An explicit understanding of the effect of system pressure on pool boiling is required to enhance the phase-change heat transfer. Despite its wide application when exploring the potential mechanism of boiling, the molecular dynamics method still needs to be improved when discussing the working mechanism of system pressure. Therefore, in the present study, a novel molecular dynamics simulation method of nanoscale pool boiling was proposed. This method provides a way to change and control pressure during the phase-change process. Furthermore, the bubble nucleation and growth in nanoscale pool boiling are quantitatively investigated through pressure-control molecular dynamics simulations. We expect that this study will improve the present simulation method of pool boiling and provide useful insights to the physics of the proces... [more]

This paper presents the thermal calculations of an air-finned heat exchanger working at temperatures above zero degrees and their verification through testing on a real device. Then, on the basis of the calculations, the influence of evaporation temperature on the drying rate of the constant speed of air flowing through the exchanger was analysed. A quantitative analysis of the effect of the temperature difference between the air being dried and the evaporator on the acceleration of the process was performed. For the analysed case, the same water mass (condensate) can be obtained for an evaporation temperature of 0 °C almost four times faster than for 10 °C. To compare temperature cases, the SMER (specific moisture evaporation ratio) was calculated, which allowed the systems to be compared in terms of energy consumption. The theoretical analysis showed that by reducing the boiling point by 10 degrees, we could increase the SMER from 0.51 kgh20/kWh to 2.18 kgh20/kWh. After receiving the... [more]

Different charge structures have different interior ballistic performance. Existing research is based on experimental measurements or the lumped parameter method to obtain limited ballistic characteristics, which indirectly impacts the analysis of the parameters’ distribution, requiring a complex modeling solution process. Besides this, the ignition performance of different charge structures needs to be further explored. The disadvantages of previous studies have limited the feasibility of further optimization of the composite charge structure. In this paper, we apply a two-dimensional two-phase flow method based on the Eulerian−Lagrangian model to study the performance of different composite charge structures. First, we establish the mathematical model of different particle types based on interior ballistics, which is directly related to the research foundation of subsequent ballistic performance. Next, we investigate the multi-scale reaction flow of complex charge structures by the t... [more]

The influence of the improvement of the finned tube radiator unit structure on the fluid flow and heat transfer effect of the locomotive was studied. A saw-toothed fin structure with aluminum instead of copper was proposed to keep the position and size of the flat copper hot water pipe unchanged. CFD simulation analysis was carried out by ICEPAK17.0, under the conditions of an ambient temperature of 24.6 °C, atmospheric pressure of 85,040 Pa and air density ρ = 0.94 kg/m3, to compare the changes of velocity field, temperature field, turbulence field and field synergy angle. The sawtooth structure of the new heat sink increases the turbulence effect of the fluid, reduces the thickness of the outer boundary layer of the water pipe, and strengthens the heat transfer effect of the radiator. Finally, the baffle height, wing window width and sawtooth angle of the sawtooth structure were selected, and the heat transfer coefficient and pressure under three conditions of low, medium and high we... [more]

Offshore wind farms (OWF) are establishing their position to be the next strategy to expand the growth horizon of wind power production. For proper integration of OWFs into the existing grid, the voltage source converter (VSC)-based high voltage direct current (HVDC) transmission is being vastly utilized. For the stable operation of the existing grid, these VSC-HVDC-connected OWFs need to abide by the fault ride through (FRT) grid codes. Though there are many proposed solutions to tackle the FRT problem of the onshore wind farms, all of them cannot be applied to the OWFs. The OWFs cannot respond to the onshore faults depending solely on local measurements. Additionally, there are very few techniques available for FRT capability enhancement of the doubly fed induction generator (DFIG)-based OWFs. One notable solution is the use of the DC chopper resistor across the HVDC line. No intelligent controller is yet to be reported for better control of the DC chopper resistor. To enhance the pe... [more]

This study proposes a patch antenna with an H-shaped slot with direct matching and harmonic tuning (rejection) functions for microwave power transfer. This antenna enables an integrated active antenna in which the power amplifier and antenna are directly connected without using a matching circuit for the fundamental frequency and harmonic rejection filter to improve the efficiency of the amplifier. The integrated design also reduces the total size of the amplifier and antenna, allowing for a higher-density array antenna. Characteristic mode analysis was performed to explain the working principle of the harmonic rejection function. The designed antenna at 5.8 GHz was fabricated to study its harmonic tuning function. The magnitude of the reflection coefficient of the proposed antenna was at a fundamental frequency of −40.4 dB for an amplification device with an optimum load impedance of 100 Ohm. At the second harmonic frequency, the magnitude and phase of the reflection coefficient at th... [more]

The automotive sector is greatly contributing to pollutant emissions and recent regulations introduced the need for a major control of, and reduction of, internal combustion engine emissions. Artificial intelligence (AI) algorithms have proven to hold the potential to be the thrust in the state-of-the-art for engine-out emission prediction, thus enabling tailored calibration modes and control solutions. More specifically, the scientific literature has recently witnessed strong efforts in AI applications for the development of nitrogen oxides (NOx) virtual sensors. These latter replace physical sensors and exploit AI algorithms to estimate NOx concentrations in real-time. Still, the calibration of the algorithms, together with the appropriate choice of the specific metric, strongly affects the prediction capability. In the present paper, a machine learning-based virtual sensor for NOx monitoring in diesel engines was developed, based on the Extreme Gradient Boosting (XGBoost) machine le... [more]

This paper was conducted to delimit the water influx in the Hamzeh oil reservoir, located in northeastern Jordan approximately 150 km east of Amman. Petroleum reservoirs are frequently encompassed by water aquifers that back up the reservoir pressure through water inflow. When the pressure declines in a petroleum reservoir, the water aquifer responds by providing an influx of water. Gradually, the damage is reduced and then eliminated, and more oil is produced from the reservoir. The material balance equation (MBE) is used as the fundamental method for this study, predicting reservoir performance for a period of 11 years. The results for this study prove that the reservoir has a water drive mechanism and that the original oil in place (OOIP) was 24,958,290 m3. The projected oil recovery factor ranges from 10.9 to 25 percent for the Hummar and Shueib formations, respectively, depending on the areal efficiency assumed in the calculations. The water influx for the 11-year period was predi... [more]

The current socio-economic and environmental context obliges companies to increase their energy efficiency to be competitive, and the development of Industry 4.0 technologies should contribute to improve it. This article analyses the influence of Industry 4.0 technologies on energy efficiency and the mediation of quality management of production process variables. After a descriptive analysis, a correlation and regression analysis is presented using information from 72 projects for the integration of Industry 4.0 technologies in industrial companies. At a global level, it is confirmed that the four technology groups (Artificial Vision and Artificial Intelligence, Additive Manufacturing and Robotics, Big Data and Advanced Analytics, and Internet of Things) contribute to improving energy efficiency by an average of 15−25% in the processes where they are integrated. In addition, the regression model determines that improved decision-making capabilities strongly mediate the achievement of... [more]

Heating induction is a new environmentally friendly, energy-saving technology that offers a more effective performance than other common heaters. The energy-use efficiency of an inductor circuit is greater than 80 percent, while a biomass tank and tungsten coil have 70 percent and 51.8 percent efficiency, respectively. This method also produces more heat than any other forms of heating using gas or coal. The induction heating method has attracted significant interest and has seen application worldwide. Based on this important source of heating, we have designed and developed a large induction-heating machine with high energy to heat up a tank directly. The aim is to degrade organic waste as much as possible and convert it into an effective fertilizer by adding mesophilic microorganisms; the fertilizer transforming process takes no more than 24 h. The tank featured in our design has a 100-cm radius and is 155 in length; this is very large. The aim of this process is to reduce the amount... [more]