To satisfy global electrical energy requirements, photovoltaic (PV) energy is a promising source that can be obtained from the available alternative sources, but partial shading conditions (PSCs), which trap the local maxima power point instead of the global maxima peak power point (GMPP), are a major problem that needs to be addressed in PV systems to achieve the uninterruptable continuous power supply desired by consumers. To avoid these difficulties, a marine predator algorithm (MPA), which is a bio-inspired meta-heuristic algorithm, is applied in this work. The work is validated and executed using MATLAB/Simulink software along with hardware experimentation. The superiority of the proposed MPA method is validated using four different PSCs on the PV system, and their characteristics are compared to those of existing algorithms. The four different PSC outcomes in terms of GMPP are case 1 at 0.07 s 995.0 Watts; case 2 at 0.06 s 674.5 Watts; case 3 at 0.04 s 654.1 Watts; and case 4 at... [more]

A power system’s nonlinearity and complexity increase from time to time due to increases of power demand. Therefore, properly designed power system controlsare required. Without these, system instability will cause equipment failures, and possibly even cascading events and blackouts. To cope with this, intelligent controllers using soft computing are necessary for real time operation. In this paper, the reheat type three-area thermal power system is considered, and the output scaling factors, gain parameters of fuzzy membership functions, and parameters of fuzzy-proportional integral derivative (FPID) controllers are optimized using a differential evolution (DE) optimization techniqueand integral time multiplied absolute error (ITAE) as objective functions. To improve the limitations of the controller and to enhance stability of the system, high voltage direct current (HVDC) technology is advantageous due to its quickresponse capabilities. In this paper, a HVDC is connected in parallel... [more]

The trade impacts of the COVID-19 pandemic and the Russian invasion of Ukraine have raised questions about the role of trade and climate policies in energy security and global emissions. This study updates a widely used integrated assessment model (IAM), MESSAGEix-GLOBIOM, to represent complex trade networks to explicitly draw energy flows from their origins to their destination. It then examines the effects of (1) energy trade tariff policies, such as import tariffs, as a proxy to represent an unfriendly trade environment and (2) a global carbon emissions tax on the global energy trade network. Results indicate that trade tariff policies have marginal effects on the trade network, i.e., the size of trade and importing-exporting regions do not change significantly. While high import tariffs significantly reduce emissions due to reduced fossil fuel imports in the importing region, this effect does not translate to significant emission reductions globally, as trade policies only impact d... [more]

The middle sub-member (Es3z) within the third member (Es3) of the Eocene Shahejie formation is the main source of the generation and accumulation of hydrocarbons in the lacustrine deltas of Bonan depression. Exploration and research work in different blocks is carried out separately. Types of sedimentary facies, and their vertical and lateral evolution in Es3z are not studied in detail. To fill this knowledge gap, we did a detailed analysis of facies and lithological characteristics through integrative studies of cores, well logs and seismic data. Identification of sedimentary structures and lithology of the reservoir zone from cores are calibrated with high-quality well logs and seismic data. Depositional facies in Es3z reservoirs are identified through analysis of sedimentary structures, grain size, log’s trends and seismic sections. Es3z was deposited in the fan delta front setting where five facies associations are found, among them distributary channels consisting of MCS, CSg, PCS... [more]

Mechanised plow and shearer systems are widely applied in underground mines all over the world. Both systems are used in the exploitation of hard coal deposited in the form of seams of various thickness. The selection of the appropriate complex depends on the mining and geological conditions and the thickness of the seam. However, with regard to thin and medium seams, these complexes are competitive solutions. Mines usually use either shearer or plow systems. Both have certain advantages and disadvantages resulting from their design and method of operation, which have been demonstrated and presented in many publications. However, in terms of their failure rate comparison, there are no relevant research and analysis results. Only selective studies of individual machines can be found. The article is concerned with the failure frequency of longwalls equipped with plow and shearer systems in the LW Bogdanka coal mine. The analysis covers a period of 13 months of the mine’s operation, durin... [more]

Molybdenum disulfide (MoS2) has attracted great attention from researchers because of its large band gap, good mechanical toughness and stable physical properties; it has become the ideal material for the next-generation optoelectronic devices. However, the large Schottky barrier height (ΦB) and contact resistance are obstacles hampering the fabrication of high-power MoS2 transistors. The electronic transport characteristics of MoS2 transistors with two different contact structures are investigated in detail, including a copper (Cu) metal−MoS2 channel and copper (Cu) metal−TiO2-MoS2 channel. Contact optimization is conducted by adjusting the thickness of the TiO2 interlayer between the metal and MoS2. The metal-interlayer-semiconductor (MIS) structure with a 1.5 nm thick TiO2 layer has a smaller Schottky barrier of 22 meV. The results provide insights into the engineering of MIS contacts and interfaces to improve transistor characteristics.

Hydrogen consumption is an important performance indicator of fuel cell hybrid vehicles (FCHVs). Previous studies have investigated fuel consumption minimization both under different driving cycles and using various power management strategies. However, different constrains on battery state of charge (SOC) ranges can also affect fuel consumption dramatically. In this study, we develop a power-source sizing model based on the Pontryagin’s Minimum Principle (PMP) to minimize the fuel consumption of FCHVs, considering different driving cycles (i.e., FTP-72 and US06) and SOC ranges (conservative 50−60% and aggressive 20−80%). The different driving cycles and SOC ranges present the real-world circumstances of driving FCHVs to some extent. Fuel consumptions are compared both under different driving cycles and using different SOC ranges. The simulation results show an effective power size map, with outlines of an ineffective sizing zone and an inefficient sizing zone based on vehicle performa... [more]

The non-stationary heat transfer inside a cylindrical channel of a shafted screw conveyor, electrically heated, and filled with a moving biomass was analyzed. The problem of non-stationary heat transport is encountered in the processes of biomass pyrolysis and food products’ sterilization. To solve the heat conduction equation with initial and boundary conditions, the methods of the expansion of the given and unknown functions into a Fourier series in the angular coordinate, and Fourier and Laplace integral transforms in the axial coordinate and time, respectively, were used. As a result of solving this problem, it is shown that the temperature in the reactor consists of two main terms. The first of them is proportional to time, and the second is a superposition of quasi-monochromatic heat pulses decaying with time. Numerical analysis of the temperature distribution in space and time depending on various specific parameters of the system was carried out. The obtained numerical results... [more]

Short-term car rental services, i.e., carsharing, is a solution that has been developing better and better in urban transport systems in recent years. Along with intensive expansion, service providers have to face an increasing number of challenges to compete with each other. One of them is meeting the expectations of customers about the fleet of vehicles offered in the system. While this aspect is noticed in the literature review mainly in terms of fleet optimization and management, there is a research gap regarding the appropriate selection of vehicle models. In response, the article was dedicated to identifying the vehicles that were best suited to carsharing systems from the point of view of frequent customers. The selection of appropriate vehicles was treated as a multi-criteria decision issue, therefore the study used one of the multi-criteria decision support methods—ELECTRE III. The work focuses on researching the opinions of users (experts) who often use carsharing services in... [more]

Hot dry rock (HDR) geothermal energy, as a clean and renewable energy, has potential value in meeting the rapid demand of the social economy. Predicting the temperature distribution of a subsurface target zone is a fundamental issue for the exploration and evaluation of hot dry rock. Numerical finite−element simulation is currently the mainstream method used to study the variation in underground temperature fields. However, it has difficulty in dealing with multiple geological elements of deep and complex hot dry rock models. A Unity networking for hot dry rock temperature (HDRT−UNet) is proposed in this study that incorporates the matrix rock temperature field equation for relating the three parameters of density, specific heat capacity and thermal conductivity. According to the numerical geological structures and rock parameters of cap rocks, faults and magma intrusions, a new dataset simulated by the finite element method was created for training the HDRT−UNet. The temperature simul... [more]

This wind tunnel study was conducted to investigate the similarity laws involved in the reasonable simulation of the wake characteristics of a full-scale wind turbine. A 5 MW scaled wind turbine model was designed using an optimization method based on the blade element momentum (BEM) theory. Subsequently, wind tunnel tests were carried out on the geometrically similar model and the thrust-optimized model, with different yaw angles and under various upstream flow conditions. The results indicated that the wake development of the wind turbine model was closely related to the thrust forces of the wind turbine, and both kinematic and dynamic similarity laws should be observed to achieve wake characteristics that are reasonably similar to those of a full-scale wind turbine. This study investigated the aerodynamic similarity principles of small-scale wind turbine models to develop a more effective method for simulating full-scale turbine wake characteristics in wind tunnel tests. The outcome... [more]

The estimated ultimate recovery (EUR) of shale gas is an important index for evaluating the production capacity of horizontal wells. The Weiyuan shale gas field has wells with considerable EUR differentiation, which hinders the prediction of the production capacity of new wells. Accordingly, 121 wells with highly differentiated production are used for analysis. First, the main control factors of well production are identified via single-factor and multi-factor analyses, with the EUR set as the production capacity index. Subsequently, the key factors are selected to perform the multiple linear regression of EUR, accompanied by the developed method for well production prediction. The thickness and drilled length of Long 111 (Substratum 1 of Long 1 submember, Lower Silurian Longmaxi Formation) are demonstrated to have the uttermost effects on the well production, while several other factors also play important roles, including the fractured horizontal wellbore length, gas saturation, brit... [more]

In the face of increasing climate concerns and the intensive development of the renewable energy sector, oil and gas companies need to develop strategies to not only comply with the new rules of the game, but to also benefit from them. This study includes prospects for development of the global energy system along with analysis of decarbonization strategies for the largest players in the oil and gas market, and defines conceptual directions to improve strategic planning systems of oil and gas companies in order to ensure sustainability in the context of a global energy transition. The theoretical background of this study is based on the fundamental concepts and methods of strategic planning, as well as modern approaches to strategic planning in the oil and gas industry. This study makes three contributions. First, we maintain that a broad, systematic understanding of the consequences of energy system transformation and defining its role in the new market should be the crucial task of p... [more]

The paper analyzes the influence of the material from which the ferromagnetic core of a transformer is made on the characteristics of a full-bridge converter. Experimental investigations were carried out for three bridge converters containing transformers with ring cores made of various materials: iron powder, ferrite, and nanocrystalline material. The properties of the aforementioned converters were considered in a wide range of changes of input voltage, load resistance, as well as frequency and the duty cycle of the control signal. Based on the obtained measurements results of the relationship between the parameters of the used transformer core and the obtained values of the output voltage, the energy efficiency of the full bridge converter was discussed. The method of transformer modeling in the SPICE program for the analysis of the considered converter in this program was proposed. The correctness of this model was demonstrated for a converter containing a transformer with a powder... [more]

This paper presents a simple mathematical and Simulink model of a two-phase hybrid stepper motor, where ignoring the permeance space harmonics of the hybrid stepper motor is regarded as the main physical assumption in this article. Moreover, the dq transformation method is adopted as the main mathematical approach for the derivation of the proposed model, where simple voltages, currents, and torque equations are obtained and used to build the proposed Simulink and circuit model of the stepper motor. The validity and the effectiveness of the proposed model are examined by comparing its results with the results collected from the Simulink model in the library of Matlab. The obtained simulation results showed that the proposed model achieved a high simplicity and high accuracy when compared with conventional models.

In this present investigation, emittance and performance attributes of a diesel engine using micro-algae spirulina blended biodiesel mixtures of various concentrations (20%, 35%, 50%, 65%, 80%, and 100%) were evaluated. An optimization model was also developed using an Artificial Neural Network (ANN) to characterize the experimental parameters. Experimental findings demonstrated significant improvement in brake specific fuel consumption (BSFC) using varied blends. Furthermore, brake thermal efficiency (BTE) is decreased gradually for biodiesel blends as compared to diesel. Micro-algae spirulina blends have shown lower concentrations of NOX and HC while increasing CO2 relative to pure diesel. To develop the model, three sets of optimizers, namely, adam, nadam, and adagrad, along with activation functions, such as sigmoid, softmax, and relu, were selected. The results revealed that sigmoid activation function with adam learning optimizer by using 32 hidden layer neurons has given the lea... [more]

Rooftop solar photovoltaics have the potential to successfully electrify rural and scattered communities worldwide. However, access to clean, high-quality, reliable and affordable energy remains elusive for several households in rural areas of the developing world. To fully comprehend, unpack and proffer meaningful solutions to this mismatch, energy sources in use and types in areas where rural electrification through solar home systems are profiled. Furthermore, grassroot communities’ perceptions of rooftop solar photovoltaics (PVs) was explored. A case study design was adopted. Thirty (30) households were purposively sampled from three selected villages. Their perceptions on the adoption of solar photovoltaic home systems were analysed qualitatively using Atlas ti 8 software. Thematic network analysis was pursued. Households in the chosen villages use grid connections, paraffin, solar PV, firewood and candles to meet their energy needs. The chosen villages used energy for water heati... [more]

Heavy fuel oil has an energy density content comparable to distillate fuels but a very high viscosity that necessitates extra heating before spray combustion inside a boiler. Heavy fuel oil is also characterized by high asphaltenes, carbon residues, trace metals, such as vanadium and nickel, fuel-bound nitrogen, and sulfur. Asphaltenes are heavy polycyclic aromatic compounds with embedded heteroatoms and significantly affect the physico-chemical properties of heavy fuels; this makes them very difficult to burn and leads to the formation of large cenospheres (lightweight, inert, hollow spheres), due to an inefficient burning process. The primary goal of this study is to experimentally investigate the influence of the asphaltene concentration on the combustion of HFO under a swirling flame, finally reducing gaseous and solid pollution. We tested HFO samples containing asphaltene concentrations of 4, 6, 8, 16, and 24 wt.%, prepared by blending the light oil of diesel and pure asphaltenes... [more]

China’s high-quality economic development is hampered by market distortions, and promises to achieve peak carbon emissions by 2030, meaning that its economic growth faces serious environmental constraints. We use a heterogeneous stochastic frontier model to analyze the impact of factor market distortions and carbon dioxide emissions on economic growth, and to evaluate the Chinese energy industry’s chain technical efficiency under the influence of factor distortions and carbon dioxide emissions. Finally, the counterfactual measurement method is used to calculate the factor market distortions and loss of the energy industry chain technology efficiency as a result of carbon dioxide emissions. The main research results show that China’s energy technology efficiency is 0.959, and the average energy industry chain technical efficiency for each region from the highest to the lowest is east (0.961), center (0.957), northeast (0.955), and west (0.950). The space for efficiency improvement is 3.... [more]

Increased renewable energy production and storage is a key pillar of net-zero emission. The expected growth in the exploitation of offshore renewable energy sources, e.g., wind, provides an opportunity for decarbonising offshore assets and mitigating anthropogenic climate change, which requires developing and using efficient and reliable energy storage solutions offshore. The present work reviews energy storage systems with a potential for offshore environments and discusses the opportunities for their deployment. The capabilities of the storage solutions are examined and mapped based on the available literature. Selected technologies with the largest potential for offshore deployment are thoroughly analysed. A landscape of technologies for both short- and long-term storage is presented as an opportunity to repurpose offshore assets that are difficult to decarbonise.

This study examines the carbon reduction investment decisions of the electric power energy supply chain considering carbon trading and carbon subsidy policies in China’s “dual carbon” context. By building a three-level supply chain system including electric power producers, retailers, and consumers, we discuss the optimal decision-making problem of the supply chain for three models of decentralized supply chain decision making without government subsidies, centralized supply chain decision making with government subsidies, and centralized supply chain decision making with government subsidies and carbon emission reduction cost sharing. Through model solving and further numerical simulations, the results showed that the increase in carbon emission reduction investment cost has a significant negative impact on power price and the total expected income of the supply chain. However, a reasonable level of government carbon emission reduction subsidy can effectively alleviate the increase in... [more]

The main subject of research involves the characteristics and assessment of the already ongoing process of maritime shipping radical decarbonization. There were identified and analyzed international legal and administrative regulatory measures as well as a package of technical, technological, operational and economic solutions, including the possibility of choosing alternative low-emission fuels that are necessary to achieve the already set targets by 2050. This research aimed to indicate and assess the most promising types of measure which are to be applied to achieve the required reduction of CO2 emissions in global shipping as well as developing a potential roadmap leading to their implementation. In the conducted research work, mainly qualitative analyses were applied, i.e., factor analysis (FA), comparative analysis (CA), and a series of consultations with representatives of the maritime industry were carried out, following the procedure typical for the Delphi technique. The main... [more]

Taking into account the international policies in the field of environmental protection in the world in general, and in the European Union in particular, the reduction of greenhouse gas (GHG) emissions, and primarily of carbon dioxide, has become one of the most important objectives. This can be obtained through various renewable energy sources and non-polluting technologies, such as the mixing of hydrogen and natural gas. Combining hydrogen with natural gas is an emerging trend in the energy industry and represents one of the most important changes in the efforts to achieve extensive decarbonisation. The importance of this article consists of carrying out a techno-economic study based on the simulation of annual consumptions regarding the construction and use of production capacities for hydrogen to be used in mixtures with natural gas in various percentages in the distribution network of an important operator in Romania. In order to obtain relevant results, natural gas was treated as... [more]

Since the Industrial Revolution, fossil fuels have become the main energy source for economic development. However, fossil fuels have also been linked to serious environmental impacts. China has recently undergone rapid economic growth, but its development model demands large amounts of energy and causes severe pollution. Therefore, there has been a recent shift toward the development of coordinated strategies to achieve economic growth while minimizing energy consumption and preserving the environment. This study sought to explore the spatiotemporal evolution of the coordination degree between economic growth, energy consumption, and environmental conservation (i.e., the “3E” system) in China, thus establishing a basis to improve coordinated development and minimize regional differences. This study evaluated 30 Chinese provinces using mathematical models. Between 2000 and 2019, the coordinated development level of the components of the 3E system in China increased steadily but remaine... [more]

The essential requirement for a cleaner environment, along with rising consumption, puts a strain on the distribution system and power plants, reducing electricity availability, quality, and security. Grid-connected photovoltaic systems are one of the solutions for overcoming this. The examination and verification of transformerless topologies and control techniques was a significant goal of this study. The transformerless concept is advantageous for its high efficiency; the transformerless converter has added advantages of reduced price, complexity, weight, and size. This study presents a novel high-efficiency transformerless architecture that does not create common-mode currents and does not inject DC current into the grid. A single-phase transformerless inverter circuit with two step-down converters was constructed in this study. Low-frequency switches determine the polarity of the grid connection. In order to control the gate pulses of switching devices, which each regulate a half-... [more]