Nowadays, mobility represents a key sector to achieve the goal of carbon neutrality. Indeed, the development of hybrid powertrains is contributing to a reduction in the environmental impact of vehicles. One of the most promising energy-saving solutions is regenerative braking, which enables deceleration while recovering energy, otherwise wasted. Even though much scientific community effort has been addressed to the optimization of this technology in the automotive field, the increase of energy storage systems efficiencies enables the overcoming of the constraints related to the reuse of electric energy in railway vehicles. This solution could be extremely useful for those railway vehicles which operate on non-electrified lines, where traction is usually provided by diesel engines. For this reason, the present work focuses on how regenerative braking technology could be exploited in diesel-powered rail applications. In further detail, a diagnostic train working on real railway lines has... [more]

It is well known that all real automatic control systems (ACS) are significantly nonlinear systems. Along with this, in engineering analysis the simplifications of their mathematic description, that is, linearization, are inevitable. These simplifications naturally introduce errors into engineering calculations. For the most complicated calculation of stability conditions, these errors can be very significant, since they lead to not only incorrect forecast of the ACS condition but also to the operating inability of the designed ACS. Most often, engineers simplify nonlinear structures in their calculations. In other words, they linearize these structures according to one of the numerous approaches which have been developed over 100 years. Calculation methods for linear ACS, in particular the Nyquist criterion, can be applied to the already linearized structure for the calculation of ACS stability condition. In this article, the authors suppose that for electromechanical and power ACS it... [more]

The energy crisis caused first by the COVID-19 pandemic and continued by the Russo-Ukrainian War has demonstrated that energy is a determining factor in the conduct of activities of any state. Several studies have examined the relationship between energy consumption and economic growth, developing various theories, but there is no consensus. This study investigates relationships by analyzing several regression models and choosing the fittest. Then, the verification of its validity is performed through the neural network, which gives greater credibility to the results obtained. Furthermore, using a structural analysis, the investigation is expanded to ranking the impact of sector-specific energy consumption on economic growth. The research includes data from 1995 to 2020 for the European Union (EU) and Romania. The results indicate that short-term energy consumption can have a positive or negative impact on economic growth, both in the EU and Romania. The structural analysis highlights... [more]

Smart and mechanically flexible energy harvesting/storage devices are attractive for the immensely growing electronic, automobile, medical, and aerospace markets. The leading challenges with current devices are their limitations regarding installation on curvy design, high-manufacturing cost, and lower production rate. Therefore, new design strategies in terms of new materials, cost, and ability to scale up fabrication are imperative to meet the contemporary and future demands of these fast-growing markets. Flexographic printing is one of the newest technologies that promises cost-effective energy devices with better energy harvesting and high storage performance. Current knowledge, selection of suitable materials, and methods of flexographic printing for solar cell and battery construction are reviewed and summarized in this paper in comparison to existing printing technologies. The main purpose of this review is to provide a comprehensive idea of flexographic printing for energy devi... [more]

This paper presents an analysis of the energy consumption of a continuous flow ohmic heater (CFOH) with advanced process controls for heating operations in the food and drinks industry. The study was carried out by using operational data collected from a CFOH pilot plant that was designed and constructed at the National Centre of Excellence for Food Engineering (NCEFE), Sheffield Hallam University. The CFOH is controlled by a PC and includes an onboard Programmable Logic Controller (PLC) and a Human Machine Interface (HMI) so that it can be operated as a stand-alone unit with basic on/off and power setting control but without any advanced control features. The technical solution presented in this paper for heating foods demonstrates significant energy saving compared with conventional heating methods. Using the CFOH, the electric current generated in the food products by the Joule effect produces a rapid temperature increase with very high energy efficiency. This technique eliminates t... [more]

A hybrid feature selection (HFS) algorithm to obtain the optimal feature set to attain optimal forecast accuracy for short-term load forecasting (STLF) problems is proposed in this paper. The HFS employs an elitist genetic algorithm (EGA) and random forest method, which is embedded in the load forecasting algorithm for online feature selection (FS). Using selected features, the performance of the forecaster was tested to signify the utility of the proposed methodology. For this, a day-ahead STLF using the M5P forecaster (a comprehensive forecasting approach using the regression tree concept) was implemented with FS and without FS (WoFS). The performance of the proposed forecaster (with FS and WoFS) was compared with the forecasters based on J48 and Bagging. The simulation was carried out in MATLAB and WEKA software. Through analyzing short-term load forecasts for the Australian electricity markets, evaluation of the proposed approach indicates that the input feature selected by the HFS... [more]

In most cases, internal insulation is the only solution to improve the energy efficiency of historic buildings. However, it is one of the most challenging and complex energy efficiency measures due to changes in boundary conditions and hygrothermal behavior of the wall, particularly in cold climates. This study presents the long-term monitoring of the hygrothermal performance of an internally insulated historic stone wall building. The study aimed to assess the hygrothermal behavior of the dolomite wall if mineral wool insulation is applied internally on the north-east wall in the rooms with and without high internal moisture load. The measurements included temperature, relative humidity, water content, and heat flux. Monitoring results are compared with 1D hygrothermal simulations and a building energy consumption simulation. The in situ measurement results and hygrothermal assessment shows energy consumption decreased by 55% with relative humidity under the insulation staying belove... [more]

This study determines and presents the capital and operating costs imposed by the use of CO2 capture technologies in the refining and petrochemical sectors. Depending on the refining process and the CO2 capture method, CO2 emissions costs of EUR 30 to 40 per ton of CO2 can be avoided. Advanced low-temperature CO2 capture technologies for upgrading oxyfuel reformers may not provide any significant long-term and short-term benefits compared to conventional technologies. For this reason, an analysis was performed to estimate the CO2 reduction potential for the oil and gas industries using short- and long-term ST/MT technologies, was arriving at a reduction potential of about 0.5−1 Gt/yr. The low cost of CO2 reduction is a result of the good integration of CO2 capture into the oil production process. The results show that advanced gasoline fraction recovery with integrated CO2 capture can reduce the cost of producing petroleum products and reduce CO2 emissions, while partial CO2 capture ha... [more]

An energy-efficient thermal control management method for space remote sensors using optical, mechanical, electrical, and thermal integration is proposed. The satellite power resources are insufficient, so an energy-efficient loop heat pipe (LHP) is designed for six intermittently operating detectors. The charge-coupled device (CCD) has a total heat generation of 72 W and operates for 8 min per orbital cycle. The LHP includes a capillary pump, six cold plates, and two radiators. The working fluid of the LHP is high-purity ammonia and the material of the wick is ceramic. The drive power on the capillary pump evaporator automatically switches between 30 W and 90 W depending on the operating mode of the remote sensor, resulting in an average power saving of about 58.2% compared to a conventional LHP. For the optical structure, a three-stage insulation technology was developed to save heater power and improve temperature stability. A transient numerical simulation model of the LHP was deve... [more]

Over the years, energy is becoming an essential factor with an impact on social, economic, and environmental aspects. More than 2.5 billion people are connected to agriculture worldwide, so the importance of agricultural energy production has become increasingly important. This study provides a comprehensive review of renewable energy, environment, and farm publication trends. Two hundred articles from 1988 to 2022 were analyzed, with special attention devoted to the last three extreme years, using the Scopus database and the Bibliometrix tool for analysis and visualization. Research on this topic experienced significant developments after 2008, with many fluctuations being revealed. Historically, China and the USA were the most productive countries in agricultural energy production advancements. However, in the last three years, the research center’s respective contributions have undergone major changes. China maintained its dominance, but the importance of the USA fell sharply, and n... [more]

Computer modelling and digitalization are integral to the wind energy sector since they provide tools with which to improve the design and performance of wind turbines, and thus reduce both capital and operational costs. The massive sensor rollout and increase in big data processing capacity over the last decade has made data collection and analysis more efficient, allowing for the development and use of digital twins. This paper presents a methodology for developing a hybrid-model-based digital twin (DT) of a power conversion system of wind turbines. This DT allows knowledge to be acquired from real operation data while preserving physical design relationships, can generate synthetic data from events that never happened, and helps in the detection and classification of different failure conditions. Starting from an initial physics-based model of a wind turbine drivetrain, which is trained with real data, the proposed methodology has two major innovative outcomes. The first innovation... [more]

Reformulating the history matching problem from a least-square mathematical optimization problem into a Markov Decision Process introduces a method in which reinforcement learning can be utilized to solve the problem. This method provides a mechanism where an artificial deep neural network agent can interact with the reservoir simulator and find multiple different solutions to the problem. Such a formulation allows for solving the problem in parallel by launching multiple concurrent environments enabling the agent to learn simultaneously from all the environments at once, achieving significant speed up.

The leakage inductance of the transformer in a dual active bridge (DAB) dc−dc converter directly impacts the ac current waveforms and the power factor; thus, it can be considered a design requirement for the transformer. In the existing literature, a choice is made to either ensure soft switching in nominal power or to minimize the RMS current of the transformer. The inductance is typically obtained using optimization procedures. Implementing these optimizations is time-consuming, which can be avoided if a closed-form equation is derived for the optimum leakage inductance. In this paper, analytical formulas are derived to estimate the desired leakage inductance such that the highest RMS value of the current in the operation region of a DAB is kept to its minimum value. The accuracy and sensitivity of the analytical solutions are evaluated. It is shown that in a large design domain, the solution for the YY-connected MFT has a less than 3% error compared to the results obtained from an o... [more]

This paper presents a novel observer-based robust fault predictive control (OBRFPC) approach for a wind turbine time-delay system subject to constraints, actuator/sensor faults, and external disturbances. The proposed approach is based on an augmented state-space representation that contains state-space variables and estimation errors. The proposed augmented representation is then used to synthesize a robust predictive controller. In addition, an observer is developed and used to estimate both state variables and actuator/sensor faults. To ensure that the proposed approach has disturbance rejection capabilities, the disturbance estimates were merged with the prediction model. In addition, the disturbance rejection capabilities and fault tolerance were insured by formulating the control process as an optimization problem subject to constraints in terms of linear matrix inequalities (LMIs). As a result, the controller gains are acquired by solving an LMI problem to guarantee input-to-sta... [more]

The study on morphology and distribution of sublacustrine fan are necessary for the exploration of oil and gas, which could help to effectively predict the reservoirs of sublacustrine fans. In this paper, the distribution and geomorphology of sublacustrine fans of Dongying Formation in Liaoxi uplift (Bohai Bay Basin, East China) and their controlling factors (including shape and formations) have been analyzed in detail based on seismic, core, and logging data. The main conclusions achieved in this study are: (1) During the sequence of the third member of Dongying Formation (SQd3), two types of sublacustrine fan, including channelized fan (in channel shape) and non-channelized fan (in tongue shape and lobe shape), developed on the eastern slope of Liaoxi uplift, which inherited the characteristics of sediments structural maturity in braided river delta front (good sandstone sorting and high structural maturity); (2) Steep slope was favorable for forming tongue shape sublacustrine fans w... [more]

At present, various contradictions in most coal-energy cities have become increasingly prominent, which has become a disharmonious factor restricting the optimization and upgrading of coal-energy cities. Since the turn of the century, taking effective improvement and protection measures and promoting the economic transformation of cities reliant on coal as an energy source has been the primary job of departments at all levels in order to secure the sustainable growth of cities. In this paper, the economic transformation and sustainable growth of coal-energy cities are included in the enhanced TOPSIS economic transformation evaluation model based on the proposed entropy weight. This study examines the industrialization of cities that rely on coal energy resources, assesses the industrial efficacy of coal energy using the DEA technique, and proposes a plan for the industrialization of cities that rely on coal energy resources. This paper summarizes the industrial transformation process o... [more]

The hydrocarbon-bearing formation of Miano gas field belongs to the Early Cretaceous and it is bounded by two shale intervals, which are considered as maximum flooding surfaces (MFS). The hydrocarbon-bearing interval includes two reservoir units: a tight gas reservoir and its overlying conventional reservoir. Core samples, borehole logs, and well production performance revealed that the two reservoirs present reversed trends in reservoir quality through the gas field without obvious barriers. The average shale volume of the tight gas reservoir changes from 24.3% to 12.2% and the average permeability changes from 32.65 mD to 0.02 mD from the south to north. However, the average effective porosity of the overlaying conventional reservoir increases from 20% to 26% and the average permeability increases from 10 mD to 300 mD. The reversed trends in the two reservoirs lead to challenges in production forecast and development well proposals in the tight gas reservoir. Therefore, reservoir cha... [more]

This study explores the effects of autonomous cars and how they may affect the design of transportation systems. The research investigated the determinants of consumer adoption of autonomous vehicles in Thailand. The research was driven by increasing environmental protection awareness and the need to conserve it through revolutionary technology. The study adopted the extended UTAUT model, where a quantitative method was adopted using primary data from 381 respondents. The results indicated that consumer adoption of autonomous vehicles in Thailand is influenced by performance expectancy, effort expectancy, facilitating conditions, environmental benefits, and purchase subsidy. The recommendations developed were that, to enhance the consumers’ intention to adopt autonomous vehicles, the concerned stakeholders should improve on aspects, such as the ability to improve job performance, increase productivity, ease of use, flexibility, clarity, and understanding, as well as improve social stat... [more]

The main goal of Fault Detection and Diagnosis (FDD) processes is to identify faults, determine their sources, and recognize solutions before the system is further harmed or service is lost [...]

In photovoltaic (PV) systems, inverters have an essential role in providing an energy supply to meet the demand with power quality. Inverters inject energy into the grid considering that a renewable source is available; however, during intermittent periods or in the absence of power generation, the inverter remains inactive, which decreases the performance of the PV system. One way to increase the operation of inverters is to operate them as Volt-Amps Reactive (VAR) compensators to generate reactive power in the absence of renewable sources. The paper presents the development of a control scheme that allows the PV system’s inverter to improve the power factor in the electrical system with or without PV power generation. The proposed control is based on using a sliding mode controller (SMC) current control loop and PI-based voltage control loop. The control scheme is developed in MATLAB/SIMULINK, and for real evaluation, a PV prototype is implemented. The control strategy efficiency is... [more]

Steel production is one of the biggest emitters of greenhouse gas in the industrial sector with about 8% of total global CO2 emissions. Although the majority of emissions can be attributed to primary steel production, there is also potential for reducing CO2 emissions in downstream steel processing. Large industrial furnaces, which are necessary for heating steel, are currently primarily fired with natural gas and by-product gases from primary steel production, offering great potential for heat recovery measures from exhaust gases. However, switching to alternative climate-neutral fuels could change this potential and thus jeopardize the economic viability of heat recovery measures. In the present work, it was therefore examined to what extent a change in energy sources in industrial furnaces affects the potential use of heat recovery in steel processing. For this purpose, an optimization model was used that takes into account heat recovery by means of direct heat transfer, heat pumps... [more]

Global gas markets are changing as natural gas (NG) is replaced by biomethane. Biomethane is produced by upgrading biogas, which can have a molar concentration of methane to over 98%. This renewable energy has been injected into the pipeline networks of NG, which offers the possibility to increase its usage in industrial and residential applications. However, the expectation of the increase in biomethane proportion on the NG grids could increase the fluctuations on the composition of the NG−biomethane mixture in amplitude and frequency. In this context, the injection of biomethane into the existing network of NG raises a discussion about the extent to which variations in gas quality will occur and what permissible limits should exist, as variations in combustion characteristics can affect the operation of the combustion processes, with consequences for consumers, distributors and gas producers. This study describes a gas quality analysis with regard to the use of biomethane in industri... [more]

A photovoltaic (PV) system is composed of a PV panel, controller and boost converter. This review article presents a critical review, contributing to a better understanding of the interrelationship of all these internal devices in the PV system, their respective layouts, fundamental working principles, and architectural effects. The PV panel is a power-generating device. A controller is an electronic device that controls the circulating circuits in a PV system to collect as much PV output as possible from the solar panel. The boost converter is an intermediate device that regulates the PV output based on the duty cycle provided by the controller. This review article also updates readers on the latest information regarding the technological evolution of these interconnected devices, along with their predicted future scope and challenges. Regarding the research on PV panels, this paper explains in depth the mathematical modeling of PV cells, the evolution of solar cell technology over ge... [more]

The aim of the paper is to analyze the effectiveness of smoke exhaust ventilation for the protection of metro technical personnel. Therefore, the specified technological corridor as a part of the underground station was chosen. The Fire Dynamics Simulator (FDS) was used to carry out numerical simulations. Due to the low fire hazard, the heat release rate (HRR) was set at 1 MW after 250 s. Four cases were analyzed: three differing in the location of the fire source and a reference case in which the smoke exhaust ventilation is turned off. The analysis took into account temperature distributions and gas flow speeds, and qualitative verification of visibility. It was shown that the variant in which the fire source was located in the middle of the corridor turned out to be the most unfavorable variant in terms of the effectiveness of smoke exhaust ventilation. The operation of the smoke exhaust ventilation improved visibility, and reduced the temperature from 270 °C to 120−155 °C, dependin... [more]

In recent decades, electronic devices have tended towards miniaturization, which necessitates the development of new cooling systems. Droplet cooling on a heated wall is effectively used in power devices with high heat flux densities. The use of a surfactant leads to an increase in the diameter of the wetted spot and the rate of droplet evaporation. Despite the wide interest and numerous works in this area, there are still unexplored questions regarding the influence of surfactant and wall temperature on convection, of nonisothermality, and of the decrease in the partial pressure of vapor with increasing surfactant concentration. This work experimentally studies the effect on the rate of droplet evaporation of wall temperature in the range 20−90 °C and of the concentration of surfactant in an aqueous solution of sodium lauryl sulfate (SLS) from 0 to 10,000 ppm. It is shown for the first time that an inversion of the evaporation rate related to the droplet diameter occurs with increasin... [more]