Reliable energy consumption forecasting is essential for building energy efficiency improvement. Regression models are simple and effective for data analysis, but their practical applications are limited by the low prediction accuracy under ever-changing building operation conditions. To address this challenge, a Joinpoint−Multiple Linear Regression (JP−MLR) model is proposed in this study, based on the investigation of the daily electricity usage data of 8 apartment complexes located within a university in Xiamen, China. The univariate model is first built using the Joinpoint Regression (JPR) method, and then the remaining residuals are evaluated using the Multiple Linear Regression (MLR) method. The model contains six explanatory variables, three of which are continuous (mean outdoor air temperature, mean relative humidity, and temperature amplitude) and three of which are categorical (gender, holiday index, and sunny day index). The performance of the JP−MLR model is compared to tha... [more]

Different control strategies for microgrid applications have been developed in the last decade. In order to enhance flexibility, scalability and reliability, special attention has been given to control organisations based on distributed communication infrastructures. Among these strategies, the implementation of consensus protocol stands out to cooperatively steer multi-agent systems (i.e., distributed generators), which is justified by its benefits, such as plug and play capability and enhanced resilience against communication failures. However, as the consensus protocol has a long trajectory of development in different areas of knowledge including multidisciplinary subjects, it may be a challenge to collect all the relevant information for its application in an emerging field. Therefore, the main goal of this paper is to provide the fundamentals of multi-agent systems and consensus protocol to the electrical engineering community, and an overview of its application to control systems... [more]

This work investigates the thermal−physical and rheological properties of hexagonal boron nitride/carbon nanotubes (hBN/CNTs) applied to reinforce water-based working fluid in a flat plate solar collector (FPSC). The hybrid nanoadditives of hBN and the chemically functionalized CNTs (CF-CNTs) were suspended in distilled water (DW) with a nonionic surfactant. The hybridization ratio between CF-CNTs and hBN was optimized to be 40:60. The thermal efficiency tests on the solar collector were carried out using different volumetric flow rates (2, 3, and 4 L/min) under the ASHRAE-93-2010 standard. The morphological characteristics of the hybrid nanoadditives were evaluated using X-ray diffraction (XRD), ultraviolet−visible spectroscopy (UV−vis), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Different concentrations of hBN/CF-CNTs were added to the water-based working fluid to record the optimal wt.% for maximum enhancement in the FPSC’s effic... [more]

This paper proposes a Data-Driven (DD) framework for the real-time monitoring, detection, and mitigation of False Data Injection (FDI) attacks in DC Microgrids (DCMGs). A supervised algorithm is adopted in this framework to continuously estimate the output voltage and current for all Distributed Generators (DGs) with acceptable accuracy. Accordingly, among the various evaluated supervised DD algorithms, Adaptive Neuro-Fuzzy Inference Systems (ANFISs) are utilized because of their low computational burden, efficiency in operation, and simplicity in design and implementation in a distributed control system. The proposed framework is based on the residual analysis of the generated error signal between the estimated and actual sensed signals. The proposed framework detects and mitigates the cyber-attack depending on trends in generated error signals. Moreover, by applying Online Change Point Detection (OCPD), the need for a static user-defined threshold for the residual analysis of the gen... [more]

The paper presents an innovated method for territorial zoning and its implementation in the territory of the Zdíkovský stream catchment area. The basis for projecting is ananthropo-ecological approach to the territory and the proposition of determining the new GES (geo-ecological units). Four essential territorial zones differing by anthropo-ecological burden and the degree of protection are suggested. A procedure for determining ecocritical lines (situations) in the territory, their regime, and possible solutions is suggested in the spirit of sustainability for future generations. The formulae and procedure for calculating the CES (coefficient of ecological stability) or ZSES (essential degrees of ecological stability), which divide the tested territory into appropriate zones, are also suggested. A comparison of zoning prior to 1989 and following was carried out, and it was proven that the significant presence of agricultural and forest subsystems in the territory with the extensive f... [more]

A record amount of renewable energy has been added to global electricity generation in recent years. Among the renewable energy sources, solar photovoltaic (PV) is the most popular energy source integrated into low voltage distribution networks. However, the voltage limits and current-carrying capacity of the conductors become a barrier to maximizing the PV-hosting capacity in low voltage distribution networks. This paper presents an optimization approach to maximize the PV-hosting capacity in order to fully utilize the existing low voltage distribution network assets. To achieve the maximum PV-hosting capacity of the network, a novel method based on the dynamic line rating of the low voltage distribution network, the coordinated operation of voltage control methods and the PV re-phasing technique was introduced and validated using a case study. The results show that the proposed methodology can enhance the PV-hosting capacity by 53.5% when compared to existing practices.

The Tanshan area is located in the southern section of the west margin of the Ordos basin. The Middle Jurassic Yan’an Formation is relatively thick and rich in coal and oil shale layers, having positive potential for energy development. In order to explore the sedimentary environment of oil shale and the controlling factors of organic matter accumulation, 18 oil shale samples collected from two boreholes (Guyou-3 and Guyou-4) in the Tanshan area were selected as the research objects, and organic geochemical and elemental geochemical tests were carried out systematically. The results show that oil shales have the characteristics of medium oil content, medium ash, high calorific value, low sulfur and low maturity stage, which constitutes good hydrocarbon generation potential. The organic matter is mainly humic type, resulting from terrigenous debris and higher plant debris. The indictors of C-value (mean 81.90), Th/U ratio (mean 3.44), CaO/(MgO·Al2 O3) ratio (mean 0.07), δEu (mean 0.71),... [more]

The energy industry has a major impact on the sustainability level of global economies, from job creation to resource efficiency and environmental impact. The aim of our study was to examine the phenomenon of energy production and its main determinants in 37 European economies during the period of 2011−2021. The methodological approach entailed the use of the panel first-difference generalized method of moments (GMM). The empirical results show that the relationship between energy production and predictors such as imports, energy prices, energy productivity, and energy efficiency was monotonic. At the same time, our results indicate a relationship between energy supply and energy production, imports, productivity, and prices. Moreover, energy production depends significantly on the energy productivity, primary energy consumption, and energy imports.

The article summarizes the results of the 25-year time horizon performance analysis of the ground source heat pump that serves as a heat source in a detached house in the climatic conditions that prevail in Wrocław, Poland. The main aim is to assess the potential of ground regeneration and reduction of CO2 emission by passive cooling application. The study adds value to similar research conducted worldwide for various conditions. The behavior of the lower source of the heat pump was simulated using EED software. The ground and borehole properties, heat pump characteristics, heating and cooling load, as well as the energy demand for domestic hot water preparation have been used as input data. Based on the brine temperatures for all analyzed cases including the ground with lower and higher values of conductivity and heat capacity, the borehole filler of inferior and superior thermal properties, and the passive cooling option turned on and off, the seasonal efficiencies of the heat pump h... [more]

Process heating represents about two-thirds of the energy that the industry sector consumes worldwide; this energy comes primarily from burning fossil fuels. There is a wide variety of processes for which solar technologies can supply energy. Within these technologies, the CSPth Central Tower produces heat at temperatures about 600 °C, making it suitable for high-temperature processes. A CSPth Central Tower can be combined with a fuel-based system to form a CSPth Hybrid Central Tower system, which results in a high-reliable energy source with low rates of CO2 emissions. In this work, the levelized cost of heat (LCOH) of the CSPth Hybrid Central Tower technology was calculated. SolarPILOT was used to design and evaluate the CSPth Central Tower; fuel consumption was calculated using a steady-state energy balance. The LCOH was evaluated considering the CO2 prices recommended by the High-Level Commission on Carbon Pricing. The analysis shows that this technology can be highly competitive a... [more]

Today, electricity tariffs play an essential role in the electricity retail market as they are the key factor for the decision-making of end-users. Additionally, tariffs are necessary for increasing competition in the electricity market. They have a great impact on load energy management. Moreover, tariffs are not taken as a fixed approach to expense calculations only but are influenced by many other factors, such as electricity generation, transmission, distribution costs, and governmental taxation. Thus, electricity pricing differs significantly between countries or between regions within a country. Improper tariff calculation methodologies in some areas have led to high-power losses, unnecessary investments, increased operational expenses, and environmental pollution due to the non-use of available sustainable energy resources. Due to the importance of electricity tariffs, the authors of this paper have been inspired to review all electricity tariff designs used worldwide. In this p... [more]

Water scarcity is a global issue recognized by the United Nations under Goal 6 of its Sustainable Development Goals (SDGs), which is to ‘Ensure availability and sustainable management of water and sanitation for all’. This challenging goal requires innovations, especially in areas with freshwater scarcity. Coupling this with the expected significant growth in population, especially in developing countries, presents major challenges to obtaining the appropriate levels of water provision needed. The development of seawater desalination technologies offers hope to alleviate freshwater shortages whilst supporting SDG 6. This research addresses the development of small-scale technology utilizing solar energy for providing clean drinking water in rural, hot, arid, and remote communities. To alleviate water scarcity in rural and isolated areas, a micro solar still (MSS) system that supports a multistage distillation process can be utilized, which evaporates and condenses the saline feed water... [more]

The use of liquefied natural gas (LNG) in the transportation sector is increasing, and boil-off gas (BOG) management systems are considered viable options to increase economic efficiency and reduce greenhouse gas emissions at LNG refueling stations. The present study proposed an economically optimized method by investigating four refueling station scenarios, including different BOG management systems. Among the four scenarios, the scenario in which compressed natural gas was produced from BOG had the lowest minimum selling price (MSP) and was the most economical. Sensitivity and uncertainty analyses were conducted for the economically optimal scenario, which identified the factors with the most influential impact and their uncertainties on the MSP. Finally, to determine the feasibility of the business through profitability analysis, the net present value, discounted payback period, and present value ratio due to changes in the discount rate were presented, and the discounted cash flow... [more]

The rising demand for electricity, economic benefits, and environmental pressures related to the use of fossil fuels are driving electricity generation mostly from renewable energy sources. One of the main challenges in renewable energy generation is uncertainty involved in forecasting because of the intermittent nature of renewable sources. The demand also varies according to the time of day, the season, the location, the climate, and the availability of resources. Microgrids offer a potential solution for the integration of small-scale renewable energy sources and loads along with energy storage systems and other non-renewable sources. However, intermittent generation and varying demand need to be matched to provide stable power to consumers. Therefore, it is crucial to design an energy management system to effectively manage the energy sources and supply loads for reliable and efficient operation. This paper reviews different techniques proposed in the literature to achieve the obje... [more]

Because the road surfaces of the underground roadways in coal mines are slippery, uneven, with dust and water mist, and the noise and light illumination effects are significant, global positioning system (GPS) signals cannot be received, which seriously affects the ability of the odometer, optical camera and ultrasonic camera to collect data. Therefore, the underground positioning of coal mines is a difficult issue that restricts the intellectualization of underground transportation, especially for automatic robots and automatic driving vehicles. Ultra-wide band (UWB) positioning technology has low power consumption, high performance and good positioning effects in non-visual environments. It is widely used in coal mine underground equipment positioning and information transmission. In view of the above problems, this research uses the WLR-5A mining unmanned wheeled chassis experimental platform; uses two UWB receivers to infer the position and yaw information of the vehicle in the und... [more]

Higher carbon alcohols such as n-propanol, n-butanol, and n-pentanol that can be produced from biomass can be used as alternative fuels in diesel engines. These alcohols can mix with both diesel fuel and biodiesel without any phase separation. Currently, unregulated emissions such as toxicity and total polycyclic aromatic hydrocarbon (PAH) from the use of these alcohols are not monitored. Investigating the effects of increasing the alternative fuel concentration for use in a diesel engine on PAH emissions will contribute to the protection of the environment and extend the engine’s operating life. In this study, the effects of adding 35% (by volume) n-propanol, n-butanol and n-pentanol to diesel and biodiesel on unregulated emissions in a diesel engine were compared. In the total PAH emission of biodiesel, the mixture containing n-pentanol stood out compared to other mixtures with a decrease of 39.17%. In higher alcohol-diesel mixtures, the highest reduction was observed in the n-butano... [more]

Microgrids are defined as a cluster of loads, distributed energy resources, and storage devices, and they are receiving worldwide attention due to the increasing rate of consumption of nuclear and fossil fuels and the community demand for reducing pollutant emission in electricity generation fields [...]

Thermal efficiency and power density improvement are the main research foci of the literature on diesel engines. The Miller cycle is considered to be one of the most promising methods of diesel engine operation. In this study, a fully variable valve timing and lift mechanism (CD-HFVVS) was studied to determine the possibility of a Miller operation. Firstly, the valve seat impact buffer in the mechanism was tested, which proved that the buffer can effectively eliminate the valve seat impact. Then the influences of different speeds and oil temperatures were studied. The results show that the valve opening duration is prolonged when engine speed increases, and the valve lift and duration are reduced while the oil temperature increased. The valve timing and lift can be fully adjusted by changing the oil discharge position and the initial plunger position, which further proves that CD-HFVVS can achieve the performance optimization of the Miller cycle. By using the mechanism, a single cylind... [more]

This study reports on the structure analyses of NiO-BCZY (BCZY = BaCe0.54Zr0.36Y0.1O3-δ) anode composite materials with the ratio of 50:50 for proton ceramic fuel cells (PCFCs) application. A product of sintered NiO-BCZY was developed to understand the structural properties of the anode materials. The objectives of this work were (a) to investigate the lattice expansion of the anode by using a high-temperature XRD (HT-XRD) from 400−700 °C; and (b) to calculate the crystallite size of the sample by using Scherrer’s and Williamson Hall’s methods. The results obtained from the HT-XRD revealed that the diffraction peaks of NiO and BCZY are matched with the cubic phase perovskite structure. For example at T = 400 °C, the lattice parameter of NiO is a = 4.2004 Å and BCZY is a = 4.3331 Å. The observation also showed that the lattice expansion increased with the temperature. Furthermore, analyses of the Scherrer and Williamson Hall methods, respectively, showed that the crystallite size is str... [more]

This article proposes the study, control and analysis of the topology of an AC−AC modular multilevel converter, known in the literature as the Hexverter. The Hexverter is capable of converting the energy between two AC systems with a reduced number of elements, if compared with other modular multilevel topologies, which makes this topology attractive in AC−AC applications. However, there are few studies about the Hexverter in the literature, so this work presents its operation principle, conducts modeling, and proposes a control scheme for the converter’s proper operation, validating the operation and control via hardware-in-the-loop emulation.

The present work consists of developing a new hybrid FL-INC optimization algorithm for the solar water pumping system (SWPS) through a SEPIC converter whose objective is to improve these performances. This technique is based on the combination of the fuzzy logic of artificial intelligence and the incremental conductance (INC) technique. Indeed, the introduction of fuzzy logic to the INC algorithm allows the extraction of a maximum amount of power and an improvement in the efficiency of the SWPS. The performance of the system through the SEPIC converter is compared with those of the direct coupling to show the interest of the indirect coupling, which requires an adaptation stage driven by an optimal control algorithm. In addition, a comparative analysis between the proposed hybrid algorithm and the conventional optimization techniques, namely, P&O and INC Modified (M-INC), was carried out to confirm improvements related to the SWPS in terms of efficiency, tracking speed, power quality,... [more]

Thrust, propulsion, vector control of supersonic jets has been applied to jet and rocket engines, ejectors, and other many devices. In general, there are two approaches to this type of control, namely mechanical moving systems and fluidic thrust vector control systems without moving parts, with mechanical moving systems being the most common. However, generally speaking, these systems are very complicated, and more simple methods and devices are desired. In this study, an extremely simple method for the thrust vector control of a supersonic jet by a fluidic Coanda nozzle (FC-nozzle) using the entrainment of the surrounding fluid and Coanda effect is newly proposed. The FC-nozzle consists of a pipe nozzle (Pi-nozzle), spacer, and linearly expanded Coanda nozzle (Co-nozzle) with eight suction pipes (Su-pipes) installed to surround the jet from the Pi-nozzle. The jet from the Pi-nozzle flows straight with the entrainment flow of the surrounding fluid. When some Su-pipes are closed, the pr... [more]

The impact of single-slope solar still with and without flat-plate collector was evaluated experimentally and numerically. Experimental analysis was conducted for four different water depths (3, 6, 9, 12 cm) in on-sunshine hours between 11 AM to 5 PM in Bhopal (23.2599° N, 77.4126° E), India. The thermo efficiency was 51.31% for 3 cm water depth while 24.29% for 12 cm water depth in an active mode of operation. In the case of passive mode, the thermo efficiency was 17.02% for 3 cm water depth and 6.77% for 12 cm water depth. The average exergy efficiency of single-slope solar still is 66.60% for 3 cm depth which is higher than 12 cm depth, i.e., 23.14%. The hourly variation parameters of solar still were also calculated and analyzed. The overall results obtained in the analysis state that solar still performs effectively when coupled with a flat-plate solar collector. According to econometric evaluation, the fabrication expense of a single-slope solar-basin-still is 126.43$ whereas the... [more]

There is a huge requirement for power systems to reduce power losses. Adding distributed generators (DGs) is the most common approach to achieving lower power losses. However, several challenges arise, such as determining the ideal size as well as location of the utilized distributed generators. Most of the existing methods do not consider the variety of load types, the variety and size of the utilized DGs besides reducing the convergence time and enhancing the optimization results. The paper performed an optimization algorithm that integrated a golden search-based flower pollination algorithm and fitness-distance balance (FDB) to find out the optimal size as well as the location of the distributed generators. It was then compared with different optimization methods to determine the best optimization technique, and it was determined to be the best technique. In addition, different types of DGs are considered, including solar energy, wind energy, and biogas, along with optimizing the si... [more]

In the present paper, we introduce a decision-support framework to (a) classify and prioritize the municipalities of a country based on their suitability to host PV energy projects and (b) pinpoint and evaluate suitable technically and economically viable, as well as environmentally and socially sustainable, sites for PV installation in the most suitable municipalities of a country. The proposed framework is applied in Portugal. It consists of two distinctive stages: ‘Energy Roadmap for PV Deployment’ and ‘PV Site-Selection Analysis and Assessment’. In the first stage, the most and least suitable municipalities for PV deployment in Portugal are identified by analyzing important environmental and technoeconomic PV siting criteria in GIS and applying the TOPSIS method. In the second stage, an integrated PV site-selection assessment is conducted in the Portuguese municipality with the highest suitability index for PV installations. This is achieved by combining a proper GIS siting model w... [more]