Climate change is an important issue that affects energy consumption, causes health problems, such as heat stroke, and requires urgent countermeasures. Serious health problems, including cardiac arrest, often occur in winter in traditional residences in Japan. Cooling-heating energy is required to maintain a healthy thermal environment. Although energy efficiency standards for buildings have been introduced worldwide to reduce energy consumption and various passive energy-saving methods are being investigated, traditional residences still face difficulties in conducting renovations because of various restrictions, such as the conservation of historical or aesthetic values. In this study, these issues and their appropriate countermeasures were investigated for a traditional townhouse in Kyoto, Japan, “Kyo-machiya” (including its new form “Heisei-no-Kyo-machiya”). The potential of reducing heating and cooling loads was examined by conducting numerical analysis considering residents’ life... [more]

The electric machines are the elements most used at an industry level, and they represent the major power consumption of the productive processes. Particularly speaking, among all electric machines, the motors and their drives play a key role since they literally allow the motion interchange in the industrial processes; it could be said that they are the medullar column for moving the rest of the mechanical parts. Hence, their proper operation must be guaranteed in order to raise, as much as possible, their efficiency, and, as consequence, bring out the economic benefits. This review presents a general overview of the reported works that address the efficiency topic in motors and drives and in the power quality of the electric grid. This study speaks about the relationship existing between the motors and drives that induces electric disturbances into the grid, affecting its power quality, and also how these power disturbances present in the electrical network adversely affect, in turn,... [more]

The deflection magnet (DM) is the most important component of the Neutral Beam Injection (NBI) system of Experimental Advanced Superconducting Tokamak (EAST), which can magnetically deflect the un-neutralized charged particles after the neutralized process of the beam is extracted from the ion source, and then form a neutral beam injected into the tokamak. Under the operating conditions of the NBI system, by using the thermocouple monitoring system in the experiment, it can be found that the currently operating DM beam collimator has a quite high temperature rise. It is necessary to redesign the DM beam collimator to improve its heat transfer performance. The parallel arrangement of multiple rows of tubes is proposed as the basic method for the redesign of the beam collimator of DM, the thermal-fluid-structure analysis model of this redesign model is established and its temperature field, pressure field and stress field are analyzed. Taking the surface temperature of the beam collimato... [more]

The study aimed to present the features of a 2-DOF vibration reduction system (VRS) equipped with a linear electrodynamic motor in passive, semi-active and active mode. At first, the VRS model was formulated. Then, simulation tests of the VRS were conducted to distinguish its most advantageous features in each mode and to analyze dynamic performance and energy consumption. Next, the VRS was experimentally tested to evaluate its effectiveness in each mode for the assumed excitations and to compare tests results against simulation data. In active mode, a sliding mode algorithm was employed for motor control, while in semi-active mode, the equivalent damping coefficient analysis was used.

The Internet of Vehicles (IoV), where people, fleets of electric vehicles (EVs), utility, power grids, distributed renewable energy, and communications and computing infrastructures are connected, has emerged as the next big leap in smart grids and city sectors for a sustainable society. Meanwhile, decentralized and complex grid edge faces many challenges for planning, operation, and management of power systems. Therefore, providing a reliable communications infrastructure is vital. The fourth industrial revolution, that is, a cyber-physical system in conjunction with the Internet of Things (IoT) and coexistence of edge (fog) and cloud computing brings new ways of dealing with such challenges and helps maximize the benefits of power grids. From this perspective, as a use case of IoV, we present a cloud-based EV charging framework to tackle issues of high demand in charging stations during peak hours. A price incentive scheme and another scheme, electricity supply expansion, are present... [more]

Yttrium oxyhydride exhibits photochromic properties at ambient temperature and pressures. Although oxygen plays an important role in determining the optoelectronic properties of the material, the question remains open regarding the site that it occupies in the crystal structure. In this paper, we address the issue by synchrotron radiation and neutron powder diffraction measurements. We report that the oxide anions occupy tetrahedral sites together with hydride anions in the face-centered cubic structure.

Autonomous energy management is becoming a significant mechanism for attaining sustainability in energy management. This resulted in this research paper, which aimed to apply deep reinforcement learning algorithms for an autonomous energy management system of a microgrid. This paper proposed a novel microgrid model that consisted of a combustion set of a household load, renewable energy, an energy storage system, and a generator, which were connected to the main grid. The proposed autonomous energy management system was designed to cooperate with the various flexible sources and loads by defining the priority resources, loads, and electricity prices. The system was implemented by using deep reinforcement learning algorithms that worked effectively in order to control the power storage, solar panels, generator, and main grid. The system model could achieve the optimal performance with near-optimal policies. As a result, this method could save 13.19% in the cost compared to conducting ma... [more]

Increasing extreme rainfall events caused by global climate change have had a significant impact on urban drainage systems. As a critical component of a pumping station, a large-scale slanted axial-flow pump (SAFP) featuring high specific speed plays a critical role in mitigating urban flooding and waterlogging. In this study, to reveal the transient characteristics of a SAFP at shut-off conditions, a computational fluid dynamics (CFD) based approach with dynamic mesh was proposed. Multiple shut-off conditions with various shut-down speeds of the sluice gate (SG) were modeled. Our analysis demonstrated that both the shut-off conditions and the slanted structure have conspicuous impacts on the hydrodynamic performance of a SAFP. Reducing the shut-down speed leads to a greater reverse flow rate and higher runner speed. The water hammer effect was simulated with different shut-down speeds, increasing the water head by 5.07−10.42 m, the axial force by 163.46−297.06 kN∙m, and the axial mome... [more]

Cross-linked polyethylene (XLPE) carries a high fire risk. In this paper, a cone calorimeter is used to carry out radiation ignition experiments, and the heat release rate (HRR), mass loss rate (MLR) and other combustion parameters of XLPE cables under three kinds of radiation intensity are measured. By comparing the ignition time and HRR of samples under different conditions, the following conclusions are drawn: (1) The ignition time of XLPE cables decreases significantly with the increase in external thermal radiation intensity. The critical ignition heat flux (CHF) is about 16.24 kW/m2. (2) The HRR curve of XLPE is consistent with the characteristics of hot, thick material. The HRR rises rapidly to the first peak after ignition and then rapidly decreases. Then, it slowly rises to the second peak. Finally, it slowly decays until the combustion stops. (3) The first peak values of HRR of XLPE under different radiation intensities are almost the same. The time for the second peak of HRR... [more]

The aim of the study was to determine the possibilities of using cup plants (Silphium perfoliatum L.) to generate energy. The energy balances of the combustion and anaerobic digestion were compared. The research showed that cup plants could be used as a raw material for solid fuel and for anaerobic digestion. An energy balance simulation showed that electricity could be generated through the anaerobic digestion of cup plants. The following amounts could be generated in the anaerobic digestion process: 1069 kWhe from 1 Mg of the raw material fragmented with an impact mill, 738.8 kWhe from 1 Mg of the raw material extruded at a temperature of 150 °C, and as much as 850.1 kWhe from 1 Mg of the raw material extruded at 175 °C. The energy balance of the combustion of biofuel in the form of cup plant pellets showed that 858.28 kWht could be generated from 1 Mg of the raw material. The combustion of solid biofuel generated a relatively low amount of heat in comparison with the expected amount... [more]

The purpose of the present study is to simulate the continuous bend erosion process in different directions, using the dense discrete particle model (DDPM). The influence of the length of the straight pipe in the middle of the continuous bend is investigated. The Rosin−Rammler method is introduced to define the diameter distribution of erosion particles, which is theoretically closer to the actual engineering erosion situation. The numerical model is based on the Euler−Lagrange method, in which the continuous phase and the particle phase are established on a fixed Euler grid. The Lagrange model is used to track the particles, and the interaction between particles is simulated by particle flow mechanics theory. The velocity field distribution, pressure variation, and turbulent kinetic energy of gas−solid two-phase flow, composed of natural gas and gravel in the pipeline, are studied. The simulation results, using the one-way coupled DPM and the four-way coupled DDPM, are compared and an... [more]

As it emerges from the literature, electricity access in rural contexts is deeply intertwined with socioeconomic dynamics. However, the advent of a reliable and sufficient source of electricity is not the sole driver that might contribute to local development. Indeed, complementary activities might have a crucial role in sustaining the development of rural communities as well as the electricity access. The current research addresses the lack of counterfactual scenarios in which the impact of complementary activities on electrification projects can be investigated. The authors introduce the case study of Matembwe village, a rural community in the Njombe region of Tanzania. The data collection includes the electricity consumption, number of electricity connections, and number of income-generating activities in a timespan ranging from 1989 to 2015. The analysis is based on system dynamics. The study considers different scenarios representing the dynamics related to the following complemen... [more]

This paper presents a new average behavioral model, named a resistor-network (RN) model, that accurately predicts the electrical characteristics of the Dickson charge pump (DCP) circuit in the slow-switching limit and the fast-switching limit regions based on steady-state analysis. The RN model describes the steady-state behavior of a single-stage DCP using a network of resistors, which can then be cascaded to model N-stage DCP, taking into account the top- and bottom-plate parasitic capacitances. The RN model provides a comprehensive insight into various design parameters of the DCP, including the input/output current, output voltage, load characteristics, losses caused by parasitics, and power efficiency. Simulation results show that the proposed RN model accurately predicts the output voltage and power efficiency of the DCP over a wide range of switching frequencies, from 0.1 Hz to 1 GHz, with an error of less than 2% at the maximum power efficiency. The RN model provides designers... [more]

Renewable energies have been the only sources recording a clear increase in total installed capacity, setting a record in new power capacity in 2020, despite the pandemic. The European Union Green Deal represents a strategy towards a sustainable economic model. In this framework, land-based geothermics has seen very limited development; however, offshore geothermics is almost completely absent in the discussion on energy source alternatives, even though it represents a real challenge for energy transition, including the production of green hydrogen. This article discusses an excursus on the activities carried out on offshore geothermal areas worldwide. We focused on the energy potential capacity of the Marsili volcanic seamount located over the bathial plain of the Tyrrhenian Basin, describing the detailed geological, geochemical, and geophysical investigations that have been carried out on that seamount since the 2000s. All the collected data have shown evidence supporting the existen... [more]

The earth-to-air heat exchanger (EAHE) is a well-founded and verified solution used in modern buildings both for heating and cooling purposes around the world. However, there is a lack of studies on operation of such devices cooperating with ventilation systems of buildings in hourly time step. In this study, the 5R1C thermal network model of a building from EN ISO 13790 was coupled with the EAHE model from EN 16798-5-1 to calculate hourly outlet air temperature. To improve the effectiveness of the considered solution, an additional algorithm was developed to choose between the EAHE outlet and ambient air as the source of ventilation air. Simulations were conducted in a spreadsheet for a low-energy single-family building. Ground temperature was compared with measurements taken in the considered location. The application of the EAHE with the proposed bypass resulted in a decrease in annual energy use for space heating and cooling from 14.82 GJ and 1.67 GJ to 12.74 GJ and 0.93 GJ, i.e.,... [more]

This work aims at investigating the effects of forest heterogeneity on a wind-turbine wake under a neutrally stratified condition. Three types of forests, homogeneous (idealized), a real forest having natural heterogeneity, and an idealized forest having a strong heterogeneity, are considered in this study. For each type, three forest densities with Leaf Area Index (LAI) values of 0.42,1.7, and 4.25 are investigated. The data of the homogeneous forest are estimated from a dense forest site located in Ryningsnäs, Sweden, while the real forest data are obtained using an aerial LiDAR scan over a site located in Pihtipudas, about 140 km north of Jyväskylä, Finland. The idealized forest is made up of small forest patches to represent a strong heterogeneous forest. The turbine definition used to model the wake is the NREL 5 MW reference wind turbine, which is modeled in the numerical simulations by the Actuator Line Model (ALM) approach. The numerical simulations are implemented with OpenFOA... [more]

The paper presents a comparative analysis of selected algorithms for prediction and data analysis. The research was based on data taken from a computerized numerical control (CNC) milling machine. Methods of knowledge extraction from very large datasets, characteristics of classical analytical methods used in datasets and knowledge discovery in database (KDD) processes were also described. The aim of the study is a comparative analysis of selected algorithms for prediction and data analysis to determine the time and degree of tool usage in order to react early enough and avoid unwanted incidents affecting production effectiveness. The research was based on K-nearest neighbor, decision tree and linear regression algorithms. The influence of the rate of learning and testing set sizes were evaluated, which may have an important impact on the optimization of the time and quality of computation. It was shown that precision decreases with the increase of the K value of the average group, whi... [more]

This paper presents the electrical system factors having an influence on the work efficiency and performance of the LC passive harmonic filters (PHFs). Such filters are very often used in industries for the purpose of harmonics mitigation and reactive power compensation. Before their installation in the electrical system, many investigations should be performed in order to ensure their good design as well as work efficiency after connection. In this paper, the factors having an influence on the PHFs work efficiency and performance, such as the grid short-circuit power, primary grid voltage spectrum (voltage measured at the PCC before the filter connection), load reactive power and current characteristic harmonics, manufacturer filter parameters tolerance and filter-detuning phenomena are investigated. Most of the quoted factors are mentioned in the literature, but the novelty of this paper is that, based on the case study example of the single-tuned filter investigated in the laborator... [more]

One of the main sources of energy utilized in the Mongolian Gers is coal and wood mainly for the purpose of heating and other domestic use. This heavily increases the air pollution levels. A viable solution for handling the air pollution is switching to renewable energy sources (RES). Grid-connected photovoltaic (PV) systems with battery back-up provide a reliable solution to the problem addressing the energy demand and pollution control. This paper proposes a grid-connected PV−second-life battery system and its operation strategy. A single Ger, which consists of a PV array, battery energy storage system (BESS), and an electric heater (EH), is modeled and tested. The trading coefficient and selling unit price are calculated based on variables such as loan, selling price, and purchasing price. The advantages of the proposed strategy are its simple design and easy implementation. The economic result shows that there is a significant reduction in the electricity bill during winters, while... [more]

Using monthly data from September 2004 to February 2020, this paper investigates the connectedness of the renewable energy, common stock, oil, and technology markets. The time-domain Diebold and Yilmaz spillover index approach is used to analyze the volatility spillover between these four markets. The study’s findings reveal that the oil and clean energy markets have bidirectional volatility spillover. The oil market has been found to be a net receiver of volatility. Furthermore, the study shows that volatility spillover is stronger in extreme positive and negative shock periods than in medium shock periods. Our findings show that, during crisis periods, the volatility spillover index rises, while the total connection reached its lowest point in 2015. Our findings suggest that policymakers should be informed that, as long as oil prices remain low, alternative energy-producing industries will not require specific policies to mitigate their vulnerability to crude oil price shocks. Howeve... [more]

This study focused on the thermal degradation of peanut shells in the presence and absence of a termite hill as the catalyst. EDX, XRF, SEM, SAA and XRD were employed for the characterization of the termite hill. The bio-oil obtained from peanut shell pyrolysis was analyzed by GC-MS. To ascertain the kinetic parameters of the reaction, thermogravimetric analysis of peanut shells was carried out with and without a termite hill at heating rates of 3, 12, 20 and 30 °C·min−1. TG/DTG of peanut shells revealed four steps of weight loss from 30 to 800 °C. The weight loss was attributed to the evaporation of water and degradation of hemicellulose, cellulose and lignin. The Kissinger method was applied for the evaluation of kinetic parameters. The activation energy (E) for the non-catalyzed degradation reactions of hemicellulose, cellulose and lignin was evaluated as 108.082, 116.396 and 182.908 kJ/mol, with a pre-exponential factor (A) of 1.9 × 108, 2.42 × 109 and 2.98 × 1011 min−1, respective... [more]

The petrophysical properties of Miocene mudstones and gas bearing-heteroliths were the main scope of the work performed in one of the multihorizon gas fields in the Polish Carpathian Foredeep. Ten boreholes were the subject of petrophysical interpretation. The analyzed interval covered seven gas-bearing Miocene horizons belonging to Sarmatian and Badenian deposits. The water saturation in shaly sand and mudstone intervals was calculated using the Montaron connectivity theory approach and was compared with Simandoux water saturation. Additionally, the Kohonen neural network was used for qualitative interpretation of four PSUs (petrophysically similar units), which represent the deposits of comparable petrophysical parameters. This approach allowed us to identify the sediment group with the highest probability of hydrocarbon saturation. Then, the spatial distribution of PSUs and reservoir parameters was carried out in Petrel. The resolution of the model was selected to reflect the variab... [more]

Green consumption is usually understood in the context of green consumption values and receptivity to green communication. Voluntary simplicity, a related yet distinct construct that relies on ecological responsibility, has not been included in the same framework. This paper bridges this gap and extends the original model to consider green consumption and voluntary simplicity in a unified structure. Based on a study conducted in Romania, it was found that 70% of the variation in buying behavior is explained by a combination of direct and mediated influences. The main takeaway is that any serious attempt to encourage responsible buying has to rely on a reduction in the absolute level of consumer demand. This result has far-reaching implications because the current paradigm of economic growth and prosperity is tributary to consumerism. The question is not how to avoid curtailing consumption and substitute green products for those harming the environment, but rather how to make voluntary... [more]

Small-scale uncontrolled passive wind generator systems are an attractive solution for rural energy generation because of the system’s reliability and low cost. However, designing these uncontrolled wind generators for good power matching with the wind turbine is challenging and often requires external impedance matching. In this paper, permanent magnet generators with different stator and rotor structures were investigated and designed to increase the generator’s synchronous inductance for a natural impedance matching. For the design methodology, multi-objective optimisation was used to design the generators for near-maximum turbine power matching, whereby internal impedance matching was reached as much as possible. It was shown that altering the placement and orientation of the permanent magnets in the rotor is a viable method to achieve the desired impedance matching; however, these generators do not have the best performance. It was found that the surface-mounted permanent magnet g... [more]

The influence of the HS (hot streak) and unsteady wake on the overall cooling performance of a rotor blade was studied in this paper. The results show that: (1) Both the magnitude and temperature of the HS gradually drops down as it passes downstream of the vane passage. (2) Within one stator period, the highest cooling performance of the blade can be observed at the initial time points, when the LE (leading edge) of the blade turns towards the trailing edge of the vane. (3) The lowest cooling performance of the blade can be observed at the time point 0.5 T, when the LE of the blade turns towards the center of the vane passage. (4) Surface temperatures in areas with unfavorable local heat flow are usually higher than the temperature of the coolant. The additional TBCs may exert adverse effects on heat dissipation from the substrate metal to the mainstream, which has a negative effect on the improvement of the overall cooling effectiveness of the coated blade. (5) Within a stator period... [more]