Power Engineering Research Articles

Comparative Ranking Preferences Decision Analysis through a Novel Fuzzy TOPSIS Technique for Vehicle Selection

Acquiring a vehicle or financing its purchase is often considered a luxury, particularly for middle-class households. In addition to their primary concern, consumers prioritize distinguishing elements such as vehicle type, size, capacity, engine power, fuel efficiency, safety features, and life-cycle costs. Furthermore, the choice of vehicle has multiple factors and is contingent upon the financial prosperity of the household, allowing for precise expression. The decision-making process is complex and entails selecting the most appropriate alternatives. This study proposes a novel fuzzy technique for order of preference by similarity to the ideal solution (FTOPSIS) method to solve vehicle selection multi-criteria decision-making (MCDM) problems. Decision-makers express their opinions on each alternative and criterion in linguistic terms, in terms of generalized interval type-2 trapezoidal fuzzy numbers (GIT2TrFNs). The FTOPSIS process involved utilizing the defuzzification of GIT2TrFNs to acquire the normalization matrix. Finally, the proposed approach prioritizes the options and chooses the best vehicle when faced with conflicting criteria, as illustrated through a numerical illustration.

Performance Evaluation of Ball Mill Type Grinding Machine for Particle Size Reduction of Porang Glucomannan Crystals

A wide gap in the price of glucomannan flour and porang tubers leads to develop a machine to process tubers into fine flour with good performance. The purpose of this research was to analyze and determine the performance of a ball mill machine on the flour yield as well as its quality. Research was conducted at PT Daud Teknik Maju Pratama from January – May 2023. Testings were carried out under two treatment factors, namely rotational speed (21.2 and 41.6 rpm) and processing time (0.5 h, 1.0 h, 1.5 h, 2 h). The test was carried out using 150 g sample for each treatment with three replications. The response variables included capacity, percentage of size reduction, material losses, engine power, and flour quality. The results showed that the optimum capacity of the ball mill machine was 12.5 kg/batch. The highest percentage of size reduction was 96.27% and the lowest material loss (3.73%) were obtained at 21.2 rpm for 0.5 h of miling process. Treatment with 41.6 rpm for 2 h produced the best flour quality with moisture content of 11.87% and fine flower yield of 63.97% passing through 100-mesh sieve. The power requirements of electric motors at 21.2 rpm and 41.6 rpm were 0.8063 kW and 0.9101 kW, respectively. The best milling capacity (1.560 g/min) was resulted at rotational speed of 62.27% CS. The ball mill machine showed superior results as compared to a disk mill which was not able to grind the glucomannan crystals up to 100-mesh size.Keywords: Ball mill, Glucomannan flour, Performance test, Porang, Refining.

Intelligent deep learning techniques for energy consumption forecasting in smart buildings: a review

Urbanization increases electricity demand due to population growth and economic activity. To meet consumer’s demands at all times, it is necessary to predict the future building energy consumption. Power Engineers could exploit the enormous amount of energy-related data from smart meters to plan power sector expansion. Researchers have made many experiments to address the supply and demand imbalance by accurately predicting the energy consumption. This paper presents a comprehensive literature review of forecasting methodologies used by researchers for energy consumption in smart buildings to meet future energy requirements. Different forecasting methods are being explored in both residential and non-residential buildings. The literature is further analyzed based on the dataset, types of load, prediction accuracy, and the evaluation metrics used. This work also focuses on the main challenges in energy forecasting due to load fluctuation, variability in weather, occupant behavior, and grid planning. The identified research gaps and the suitable methodology for prediction addressing the current issues are presented with reference to the available literature. The multivariate analysis in the suggested hybrid model ensures the learning of repeating patterns and features in the data to enhance the prediction accuracy.

Understanding the Role of Public Transportation in Supporting the Care Economy in Washington, DC, USA

Women’s empowerment is a powerful engine for personal and societal economic development and well-being. Nevertheless, gender biases in physical infrastructure investments lead to negative consequences for women and children that reduce their empowerment and limit their economic benefits. Public fixed-route buses, such as those in Washington, DC, illustrate how physical transportation infrastructure has innate gender biases. These young residents likely depend on strollers to travel longer than a few blocks. The Washington Metropolitan Area Transit Authority (WMATA) runs the public transportation system in Washington, DC. In 2021, 7% of DC’s 720,000 residents were under five. WMATA maintains a fleet of approximately 1595 buses, 95% of which banned the onboarding of open strollers until recently. This ban directly limited the use of Metro buses for the caregivers of young children, primarily women. It also reduced the opportunities for these caregivers to participate in DC’s economic life. In neighborhoods dependent on buses for essential mobility, the stroller ban reduces employment, healthcare, social service, educational, and recreational offerings beyond walkable distances. This paper examines the publicly available discussions and actions that led to the updated stroller policy and offers opportunities for improving caregiver transit access in Washington, DC, and, by extension, other cities worldwide.

An overview concerning the utilization of fusel oil as an alternative fuel in the engine applications

Diesel engines will continue to be discussed in the coming years because of their harm to the environment resulting from emitted pollutants. These engines are unrivaled in the transportation industry owing to the high power achieved at high compression ratios. In recent years, studies have been carried out on the use of alternative fuels instead of diesel in compression ignition engines. Fusel oil (FO) is a by-product acquired from several types of agricultural biomass by different techniques. To conclude, in the present paper, researches in the published literature for diesel engines using fuel blends containing FO as an alternative fuel have been reviewed in detail. FO's high octane number, high oxygen content, and low freezing point make it stand out as a fuel additive. In addition, the calorific value of FO is lower than diesel, and its density and viscosity are higher. When FO is infused at different concentrations to diesel fuel (DF) or DF-biodiesel mixtures, fuel consumption increases in compression-ignition engines while engine power decreases compared to reference DF. There is a noticeable decrease in CO and NOx pollutants in fuel blends using FO. The amount of water in the FO has an adverse effect on diesel engines. In the article, firstly, the production and properties of FO are reviewed and its fuel properties are summarized. Then, the effects of diesel/FO and diesel/biodiesel/FO mixtures on engine performance and emissions are discussed. Finally, the positive and negative aspects of FO for diesel engines are summarized.

Badania wpływu pola magnetycznego na proces tworzenia kamienia w urządzeniach termicznych

Water is used as working fluids in hydro and thermal power engineering, as well as in heat supply and cooling systems. In the process of heating water in water-heating boilers, scale forms due to the precipitation of crystals of mineral additives and mineral salts. Over time, the accumulation of scale with low thermal conductivity leads to a decrease in the internal diameter of the pipes. Consequently, the flow of liquid is hindered, the hydraulic resistance increases and the thermal conductivity of the device decreases. The scale layer is usually removed by acid washing of the internal heat exchange surfaces or mechanical washing. However, both methods involve the use of a substantial amount of chemicals and result in highly polluted wastewater. In addition, it significantly increases operating costs. The article uses statistical methods for processing experimental data, and generally accepted methods for conducting experiments to study the patterns of scale formation using control and measuring instruments and accurate methods for measuring technological parameters. The main purpose of the paper is to study the influence of a constant magnetic field on the formation of mineral salts deposits on the surface of walls of thermal appliances used in chemical, oil refining, and food processing industry. The influence of a constant magnetic field on the formation of scale on the surface of the walls of the heating element in a water heater has been established. According to the results of an experiment aimed at preventing the accumulation of mineral salt deposits on the surface of the heating element in a water heating boiler under the influence of a magnetic field, the amount of mineral salt precipitate deposited on such surface can be reduced up to 5.2 times. Consequently, the prevention of mineral scale formation is achieved, eliminating the need to use expensive chemicals. The stable operation of the devices contributes to enhanced thermal efficiency. Under the influence of a magnetic field, scale formation decreases on average by a factor of 5, as long as the water temperature does not exceed 70°C. However, if the temperature rises above 90°C, the scale formation rate gradually increases.

Investigating the characteristics of internal discharge shock waves in gas‐insulated switchgear under varied gap configurations

AbstractGas‐insulated switchgears (GIS) are crucial components of high‐voltage power transmission and distribution systems. Internal discharges within GIS have garnered significant attention in the field of power engineering. This study investigates the characteristics of internal discharge shock waves in GIS under an air pressure of 0.3 MPa and three different discharge gap conditions: 1, 1.5, and 2 mm. High‐speed shadowing techniques are used to analyse the propagation speed, morphology, and post‐wave parameters. The study findings reveal that although the characteristics of internal discharge shock waves in GIS noticeably change with the gap size, they also exhibit a consistent trend: as the gap size increases, the initial shock wave accelerates, intensifying the discharge. Simultaneously, the rate of attenuation rises, with the shock wave becoming weaker after ≈30 µs. Furthermore, the post‐wave parameters follow a similar pattern, with an increase in gap size leading to higher parameter values but also a faster decay rate. The parameters decay more rapidly between 10 and 20 µs, slow down between 20 and 30 µs, and ultimately stabilize after around 30 µs. The results of this study hold significant theoretical and practical implications for the monitoring, diagnosis, and prevention of internal discharges in GIS.

A pictorial view on false positive findings of 68Ga-PSMA-11 PET/CT and their prognostic value in patients with prostate carcinoma after radical prostatectomy and undetectable PSA values.

Recently, gallium-68-prostate-specific membrane antigen-11 (68Ga-PSMA-11) positron emission tomography/computed tomography (PET/CT) has become a key imaging method in prostate carcinoma staging and biochemical progression, with varying sensitivities in different studies (from 40% to 80%). After four years of experience with 68Ga-PSMA-11 PET/CT, we found that it is possible to detect lesions with increased PSMA expression in patients with undetectable prostate specific antigen (PSA) levels after radical prostatectomy. The key questions we wanted to answer were as follows: if those lesions were malignant and could the early detection of those malignant lesions have a role in patient management? We aimed to identify and follow up PSMA-positive findings for a period of 4 years in patients with prostate cancer after radical prostatectomy and undetectable PSA values at the time of the examination. We also explored false-positive lesions in detail. The study included all patients who underwent radical prostatectomy and had undetectable PSA values <0.05ng/mL and who underwent 68Ga-PSMA-11 PET/CT between July 2019 and December 2019. We performed 220 studies and found 40 patients with these characteristics; these patients were included in this study. All of them were followed up until July 2023. Any finding with increased radiopharmaceutical accumulation above the background activity in the respective area was considered a false positive. Prostate-specific membrane antigen accumulation in established lesions was assessed semi-quantitatively by the maximum standardized uptake value (SUVmax) and qualitatively by the four-point visual scale proposed in the E-PSMA recommendations. We found 15/40 (37.5%) patients with PSMA-positive findings. These were predominantly bone changes without a corresponding CT abnormality or discrete cystic or osteoblastic lesions with above-background increased PSMA expression. The mean SUVmax of these non-specific lesions was 3.02 (SD 2.86). After 3.5-4 years of follow-up, biochemical progression was found in only two of the patients.The great sensitivity of the method nowadays is a powerful engine for the development of new therapeutic options. On the other side, the lower specificity due to false positive findings, if misinterpreted, might lead to switching to a higher stage, with the planned radical treatment replaced by palliative treatment. The presence of 68Ga-PSMA-11 PET/CT-positive findings in patients after radical prostatectomy and an undetectable PSA had a low predictive value for future progression. The interpretation of 68Ga-PSMA-11 PET/CT should always include a complex assessment of the clinical setting-the risk group, PSA value and degree of PSMA accumulation in the lesions. In these situations, further clarification of PSMA-positive findings is appropriate before deciding to change treatment.

Solving differential‐algebraic equations in power system dynamic analysis with quantum computing

AbstractPower system dynamics are generally modeled by high dimensional nonlinear differential‐algebraic equations (DAEs) given a large number of components forming the network. These DAEs' complexity can grow exponentially due to the increasing penetration of distributed energy resources, whereas their computation time becomes sensitive due to the increasing interconnection of the power grid with other energy systems. This paper demonstrates the use of quantum computing algorithms to solve DAEs for power system dynamic analysis. We leverage a symbolic programming framework to equivalently convert the power system's DAEs into ordinary differential equations (ODEs) using index reduction methods and then encode their data into qubits using amplitude encoding. The system nonlinearity is captured by Hamiltonian simulation with truncated Taylor expansion so that state variables can be updated by a quantum linear equation solver. Our results show that quantum computing can solve the power system's DAEs accurately with a computational complexity polynomial in the logarithm of the system dimension. We also illustrate the use of recent advanced tools in scientific machine learning for implementing complex computing concepts, that is, Taylor expansion, DAEs/ODEs transformation, and quantum computing solver with abstract representation for power engineering applications.

Comparison of Standard and Racing Roller Weight Variations on CVT on the Power and Torque of the Honda Beat 110cc

This automatic motorbike uses an automatic transmission system called CVT (Contynously Variable Transmission). CVT is a system that automatically changes speed according to engine speed. This machine does not use transmission gears, but instead uses two pulleys (front and rear) which are connected by a belt (v-belt. The advantege of a CVt automatic transmission is that it can provide speed changes in torque from the engine to the rear whells automatically. This research aims to determine the effect of roller weight on the power and engine torque of a 110 cc two wheeled vehicle. The background of this research is to determine the power and torque of motorbikes for each roller weight studied and to draw conclusions about better use of rollers weight. This research uses experimental research methods, the materials used are standard 12gr,11gr,10gr,9gr,8gr rollers, as a comparison and 110cc injection beat motorbikes. The toll used in this research is a dynamometer. This tool shows directly the maximum power results at a certain rpm. Changes in the weight of the Honda Beat 110cc CVT roller affect the power produced by the engine. Changes in roller weight can affect the size of the engine’s power and torque. This in proven by data showing changes in engine power and torque during each test. Therefore, it is hoped that the result of this test can be used as a reference for improving engine peformance in vehicles.

A call-to-action: integrate a learning health system framework into longitudinal population studies to improve health response in Africa.

Longitudinal population studies (LPSs) in Africa have the potential to become powerful engines of change by adopting a learning health system (LHS) framework. This is a call-to-action opinion and highlights the importance of integrating an LHS approach into LPSs, emphasizing their transformative potential to improve population health response, drive evidence-based decision making, and enhance community well-being. Operators of LPS platforms, community members, government officials, and funding agencies have a role to contribute to this transformative journey of driving evidence-based interventions, promoting health equity, and fostering long-term public health solutions for African communities.

A Visual Study on of HCB/Gasoline Dual-Fuel Combustion Strategy and Premix Ratio in a Diesel Engine

Article A Visual Study on of HCB/Gasoline Dual-Fuel Combustion Strategy and Premix Ratio in a Diesel Engine Qian Wang *, Botian Guo, Lixuan Cao, Xu Liu, Yi Jiang, and Jiawei Yao School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China * Correspondence: qwang@ujs.edu.cn Received: 8 November 2023 Accepted: 22 January 2024 Published: 30 January 2024 Abstract: This study investigates the combustion characteristics of hydrogen catalysed biodiesel (HCB) ignited gasoline in an optical engine using the Reactivity Controlled Compression Ignition (RCCI) combustion model. The experiment uses a single injection strategy to determine the optimum injection timing for gasoline ignition by varying the HCB injection timing (-30 to -15° CAATDC) and the ratio of high to low reactivity fuel energy (10% to 30%), to investigate the gasoline premix ratio, and to analyse the flame development characteristics. The results indicate that as the HCB energy ratio increases, the in-cylinder pressure and heat release rate increase significantly, and the in-cylinder combustion temperature improves significantly. As the injection timing is delayed, the combustion phase shifts back, and when the injection timing is close to the upper stop, the in-cylinder combustion pressure and heat release rate increase first increase and then decrease. Based on the results, it can be concluded that optimising the HCB injection timing and energy ratio can effectively control the distribution of the fuel-air mixture in the combustion chamber, thereby improving combustion efficiency and emission performance. By strategically adjusting the injection timing, an ideal balance between fuel stratification and flame propagation can be achieved, which ultimately improves the overall combustion process. The results of this study provide valuable insights for the further development of combustion control strategies and contribute to the development of more efficient and environmentally friendly engine technologies.

Study on Combustion and Soot Formation Characteristics of RCCI Engine with Diesel Mixed with PODE Ignited Gasoline

Article Study on Combustion and Soot Formation Characteristics of RCCI Engine with Diesel Mixed with PODE Ignited Gasoline Qian Wang, Botian Guo, Wenjun Zhong *, Peng Jiang *, and Xu Liu School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China * Correspondence: wj_zhong@ujs.edu.cn (W.Z.); jiangpeng@ujs.edu.cn (P.J.) Received: 8 November 2023 Accepted: 23 January 2024 Published: 30 January 2024 Abstract: Polymethoxydimethyl ether (PODE) is a promising clean alternative fuel with the potential to improve carbon emissions from internal combustion engines. However, when used as a sole fuel, its low viscosity leads to increased wear on high-pressure pumps and injectors. Furthermore, its low calorific value makes it unsuitable for direct application in diesel engines. Numerous studies have shown that blending PODE with diesel results in lower soot generation throughout the entire combustion cycle in diesel engines. However, the process of reducing in-cylinder soot generation is not yet clear, necessitating further optical diagnostics of in-cylinder combustion. Therefore, the aim of this study is to investigate the influence of PODE/diesel blend combustion on the combustion characteristics and soot generation properties of reactivity controlled compression ignition (RCCI) diesel engines. The study employs an optical engine and conducts experiments using high-speed imaging and two-color pyrometry. Preliminary experiments indicate that a 50% premixed ratio exhibits better heat release and lower soot generation. Thus, this study explores the effects on in-cylinder combustion and soot generation properties by varying the PODE blending ratio and injection strategy under a 50% premixed ratio. Results indicate that with an increase in PODE blending ratio, both peak in-cylinder pressure and heat release rate decrease, and the combustion duration is prolonged. Compared to diesel, the soot content of P20D80 (20% PODE and 80% diesel) and P50D50 (50% PODE and 50% diesel) is 55.22% and 36.55% respectively, while the heat release is 97.89% and 95.39% of that of diesel. The total amount of soot generated was 55.22% and 36.55% of that of direct injection P0D100, the high temperature area of soot was reduced by 52.9% and 73.32% respectively, the stable value of the average soot temperature was reduced by 6.65 K and 20.25 K respectively, and the average KL factor was the stability values were reduced by 10.35% and 16.12% respectively. P50D50 effectively reduces soot generation while maintaining thermal efficiency. Furthermore, an investigation of injection strategy under P50D50 condition reveals that segmented injection results in lower cylinder pressure, peak heat release rate, and total soot generation compared to single injection. The average temperature of the two-stage injection strategy increased, and the average temperature of soot stable time under the operating conditions of D-40/-20, D-35/-20 and D-30/-20 were 2100.85 K, 2210.16 K and 2192.24 K, respectively. The stable values of the average KL factor of soot under the operating conditions of D-40/-20, D-35/-20 and D-30/-20 were 86.52%, 66.62% and 62.79% of those of S-20, respectively. Although it effectively suppresses soot generation, it comes at the cost of sacrificing a portion of heat release.

CO2 capture feasibility by Temperature Swing Adsorption in heavy-duty engines from an energy perspective

This study made an energy performance analysis and an estimate of the volume and weight of an innovative carbon capture and storage (CCS) system by temperature swing adsorption (TSA) hybridised with an organic Rankine cycle (ORC) working with the waste heat contained in the exhaust gases of a natural gas engine. To achieve this, two varying-sized engines are simulated across the entire rpm range and under partial engine loads. Subsequently, energy simulations are conducted at two CO2 capture rates (CCR) and employing three sorbents (MOF-74-Mg, PPN-6-CH2-DETA and activated carbon) to compare the CCS-ORC performance. Results demonstrate the viability of installing CCS-ORC systems in heavy-duty vehicles since they require less than 6 % of the total volume of the studied vehicles. The engine power penalty induced by the CCS-ORC system varies from 1.9 % with MOF-74-Mg to 23.5 % with activated carbon at 100 % of CCR, leading to a maximum 6.14 % rise in engine fuel consumption. Finally, the maximum CO2 capture process energy consumption is 631 kJ/kgCO2, 9.9 % lower than the literature reported for TSA. Based on these promising results, applying the hybridised system presented in this paper for CO2 capture in sectors that use heavy-duty engines is a strategy to implement.

Experimental and cfd analysis of the influence of fuel injection timing on the behavior of a gasohol-based gdi engine

ABSTRACT This work examines the impact of FIT (Fuel Injection Timing) on engine’s performance of an automotive, Gasoline Direct Injection (GDI) engine using Gasohol (85% Gasoline + 15% Ethanol by mass) as fuel. The start of FIT was experimentally varied from −280 CAD (Crank Angle Degrees) to −330 CAD at 10 CAD intervals by using an open ECU. Experiments were performed at variable power outputs (such as 5, 8, 10, 13, 16, 18 and 21 kW) at a constant speed of 2500 rpm. CFD simulations were carried out for the above said conditions to understand engine’s behavior. Considering the conventional start of injection, advancing the FIT showed improvement the BTE (brake thermal efficiency) up to −320 CAD BTDC. The maximum BTE was observed as 31.8% at the engine power output of 21 kW (whereas it was 28.6% at −300°CAD). CFD results confirmed the improvement in the air-fuel mixing rate and swirl motion. With the use of advanced FITs, the emissions of carbon monoxide (CO) and hydrocarbons (HC) were decreased. The CFD emission results for CO and HC showed good agreement with the experimental findings. With the advanced FITs, NOx emissions showed an increase at all loads. The in cylinder pressure was observed to be higher with advanced FITs. Modeling results are very well supported with experimental pressures. It is concluded that advancing the fuel injection timing might improve the performance and lower HC and CO emissions of a Gasohol-based GDI engine. The optimized injection timing of −320 CAD could be recommended for the aforementioned engine’s greatest performance.

Thermodynamic analysis on the effect of altitude on the exhaust energy recovery of electric turbocompound engines

The deterioration of fuel economy for turbocharged engines with altitude is an urgent problem. Turbocompounding is a promising technology to fully recover exhaust energy and reduce engine fuel consumption at off-design altitudes, but it is affected by the environmental boundary caused by altitude. In this study, the effect and mechanism of altitude on the exhaust energy recovery of turbocompound engines were revealed via thermodynamic analysis. The results show that the total system power output of the turbocompound engine is higher than that of the base engine at different altitudes, the maximum improvement percentage of which reaches up to 4.3%; and the total power output deteriorates less with increasing altitude. When the altitude increases to 4 km, the exhaust energy utilization coefficient of turbocompound engine decreases by only about 2%. Based on energy and exergy analysis, full recovery and utilization of exhaust energy contribute to improving the altitude adaptability of turbocharged engines. The maximum altitude while maintaining the engine power constant for the turbocompound engine is 4.66 km under an engine speed of 1800 r/min. Thus, the altitude range over which turbocompound diesel engines can operate efficiently is widened.

Operation Analysis of Coordinated Droop Control for Stand-alone DC Micro-grid

This paper introduces a coordinated droop control for the stand-alone DC micro-grid., which is composed of photo voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid

Multivariate analysis of pedestrian-related crashes on Vienna’s roads

Pedestrians are the least protected traffic group when compared to other participants. When compared to moto riders (independent of engine power) they have head protection provided by helmet or vehicle metal shield along with airbag that is providing highest level of body protection for personal vehicles drivers. This vulnerable group is characterized by the high presence of very young participants whose psychological characteristics place them in a vulnerable risky subgroup. According to the police original data on crashes involving pedestrians in the town of Vienna, since 2010 there was highest number of crashes in 2012 and after slow decrease is recorded but still high in total number of crashes involving only pedestrians is an extremely worrying problem.This research is essential to address leading characterizations in crashes with the aim to answer what is current trend in crash occurrence during 2010–2020 inside Vienna municipality, and what is predicted trend. Is there significant and distinctive difference based on gender and age with specific conditions under which crashes are occurring influencing different injury degree. Multiple regression undoubtedly points fields for action in statistically based findings providing the most important answer to this research: why crashes do occur so frequently and what is leading cause of injured pedestrians. Stepwise procedure in discriminant analysis at statistically significant level shows what differentiates injured and not injured pedestrians.

The quantum Carnot-like heat engine: The level degenerate case

The two-level quantum heat engines have been studied extensively. Before that, the optimization of most heat engines was mainly concentrated in non-degenerate cases. We consider the level degeneracy, then calculate the maximum operation time and the irreversible dissipation coefficient of the two-level system under the scheme of linear tuned levels. In the high-temperature limit, we find that the level degeneracy affects the maximum power of the two-level heat engine. Especially in the case of the same degeneracy of the ground state and the excited state, the influence is the greatest. In addition, we also show that the degeneracy does not affect the efficiency at maximum power and the consistent relation of the two-level Carnot-like heat engine.

Application of Methods Based on Artificial Intelligence and Optimisation in Power Engineering—Introduction to the Special Issue

The challenges currently faced by network operators are difficult and complex. Presently, various types of energy sources with random generation, energy storage units operating in charging or discharging mode and consumers with different operating characteristics are connected to the power grid. The network is being expanded and modernised. This contributes to the occurrence of various types of network operating states in practice. The appearance of a significant number of objects with random generation in the power system complicates the process of planning and controlling the operation of the power system. It is therefore necessary to constantly search for new methods and algorithms that allow operators to adapt to the changing operating conditions of the power grid. There are many different types of method in the literature, with varying effectiveness, that have been or are used in practice. So far, however, no one ideal, universal method or methodology has been invented that would enable (with equal effectiveness) all problems faced by the power system to be solved. This article presents an overview and a short description of research works available in the literature in which the authors have used modern methods to solve various problems in the field of power engineering. The article is an introduction to the special issue entitled Advances in the Application of Methods Based on Artificial Intelligence and Optimisation in Power Engineering. It is an overview of various current problems and the various methods used to solve them, which are used to cope with difficult situations. The authors also pointed out potential research gaps that can be treated as areas for further research.