Energy expenditures are now the main cost for two businesses that generate huge incomes each year for Thailand, which are agribusiness and community tourism. As entrepreneurs have to share a portion of their income as energy utility bills each month. This is a factor which results in them getting a low net return. Recognizing the need for energy management for sustainable use in agriculture focusing on durian cultivation in Kantharalak district and community tourism in Sisaket province, this research used a newly developed optimization algorithm called Kouprey-inspired optimization (KIO) to assist energy management in smart agriculture to support community-based tourism. This was initiated with a smart energy node to reduce the energy and labor costs for volcanic durian planting and accommodation in community-based tourist attractions in Sisaket province. The results showed that the combination of the KIO algorithm and smart energy node allowed for efficient management of the volcanic... [more]

Energy and the environment are important foundations for sustainable economic development. In order to realize the sustainable development of energy economy, clarify the respective responsibilities of the government and enterprises, and explore the internal mechanism of ecological compensation, this paper constructs an evolutionary game model by means of social benefits, ecological compensation, supervision costs, government subsidies, enterprise punishment, enterprise additional income, enterprise emission reduction costs and other means, through the government’s supervision and non-supervision behavior, as well as the cooperation and non-cooperation behavior of enterprises, and analyzes the model parameters and game results. The research shows that: (1) due to the delay effect of technical progress of pollutant discharge, in the long run, the cost of enterprise emission reduction must be less than its benefits. (2) Social benefits brought by government regulation must exceed half of... [more]

We invert gravity and magnetic anomalies for basement relief at the Harrat Rahat Volcanic Field (HRVF) for the purpose of evaluating its geothermal energy prospects. HRVF is dominated by basaltic scoria cones and other volcanic rocks overlying the Proterozoic basement. The area considered for this study is located within the northern HRVF and consists mainly of alkali basalts with lesser amounts of benmoreite, mugearite, hawaiite, and trachyte. Our approach adopts a global optimization technique using Particle Swarm Optimization with automated parameter selection, and a two-dimensional gravity-magnetic (GM) forward modeling procedure. The results of the PSO-based approach indicate a depth to the basement at 0.10−624 m, with greater depths within the central region of a solitary anomalous density body in the HRVF. The obtained basement geometry is corroborated by the depth estimates obtained from other potential field inversion methods. The regions with higher prospects are mapped for a... [more]

This paper introduces a modified consensus-based real-time optimization framework for utility-connected and islanded microgrids scheduling in normal conditions and under cyberattacks. The exchange of power with the utility is modeled, and the operation of the microgrid energy resources is optimized to minimize the total energy cost. This framework tracks both generation and load variations to decide optimal power generations and the exchange of power with the utility. A linear cost function is defined for the utility where the rates are updated at every time interval. In addition, a realistic approach is taken to limit the power generation from renewable energy sources, including photovoltaics (PVs), wind turbines (WTs), and dispatchable distributed generators (DDGs). The maximum output power of DDGs is limited to their ramp rates. Besides this, a specific cloud-fog architecture is suggested to make the real-time operation and monitoring of the proposed method feasible for utility-conn... [more]

The dc-link voltage ripple plays an important role in dc capacitor design for three-phase voltage source converters (VSCs). However, the analytical models of the dc-link voltage ripple have rarely been reported for VSCs with nonlinear output current. This paper first derived the LOH voltages expressions in the dc-link. It reveals that each LOH component in ac current would induce two dc-link LOH voltages. Then the switching frequency harmonic voltages (SHVs) and their envelope expressions are formulated. Moreover, the proposed analytical models could be very much simplified when applied to special cases in the previous literature. Finally, an easy to design dc capacitor equation under nonlinear output current is also derived. Both simulation and experimental results validate the proposed method.

The study presents an investigation of thermal energy consumption for heating in an educational building located in the north-eastern part of Poland in 2017−2020, after deep thermomodernization. An evaluation of the actual energy effects was made based on measurements carried out over a 4-year operational period. They were compared with the results of theoretical calculations included in the energy audit and an attempt was made to describe the reasons for the discrepancies. The planned and achieved economic efficiency indicators were assessed and the amount of reduction of pollutant emissions was determined. The performed analysis allowed for an assessment of the impact of deep thermomodernization in terms of reducing heat energy consumption for central heating purposes, as well as reducing greenhouse gas emissions such as CO2, SOx, NOx and benzo(a)pyrene to the atmosphere. The implementation of thermomodernization in buildings led to savings of about 43% in terms of heat energy consum... [more]

With increasing concerns on transportation decarbonization, fuel cell hybrid trains (FCHTs) attract many attentions due to their zero carbon emissions during operation. Since fuel cells alone cannot recover the regenerative braking energy (RBE), energy storage devices (ESDs) are commonly deployed for the recovery of RBE and provide extra traction power to improve the energy efficiency. This paper aims to minimize the net hydrogen consumption (NHC) by co-optimizing both train speed trajectory and onboard energy management using a time-based mixed integer linear programming (MILP) model. In the case with the constraints of speed limits and gradients, the NHC of co-optimization reduces by 6.4% compared to the result obtained by the sequential optimization, which optimizes train control strategies first and then the energy management. Additionally, the relationship between NHC and employed ESD capacity is studied and it is found that with the increase of ESD capacity, the NHC can be reduce... [more]

The use of a cobalt-iron (VaCoFe) core is investigated as an alternative to silicon-iron (FeSi) in the design of interior permanent magnet synchronous motors (IPMSM). Considering VaCoFe and FeSi cores, a spoke-type IPMSM geometry is optimized for a torque range up to 40 N·m, providing a general comparative analysis between materials. This is done considering the application of a four-motor competition vehicle’s powertrain. A genetic optimization algorithm is coupled to the motor’s electromagnetic and thermal hybrid analytical/finite-element model to provide sufficiently accurate results within a feasible time. VaCoFe allows an estimated increase of up to 64% in torque for the same efficiency level, or up to 5% in efficiency for the same torque. After optimization and using a detailed time-dependent model, a potential 3.2% increase in efficiency, a core weight reduction of 4.1%, and a decrease of 9.6% in the motor’s core volume were found for the VaCoFe at 20 N·m. In addition, for the s... [more]

This paper presents a new control structure to improve the performance of LCL grid-connected inverters. First, the conventional linear extended state observer (LESO) has difficulty rejecting periodic disturbances, so the proposed method adds an internal model of disturbances into LESO to enhance the harmonic suppression ability. Second, the phase lag caused by the digital delay and LCL resonance make it difficult to ensure the stability of the system. In this paper, the proposed method adds phase compensation for the ESO loop, thus enlarging the stability region of the system with no additional sensors being required. Third, the design of the controller parameters is simplified and the frequency performance analysis of the system is given. Finally, the simulation and experimental results show that the proposed method has good harmonic suppression capability and robust stability.

A thermodynamic model was developed and validated to analyze a high-performance solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system for electric aviation. This study used a process simulation software package (ProMax) to study the role of SOFC design and operation on the feasibility and performance of the hybrid system. Standard modules, including compressor, turbine, heat exchanger, reforming reactor, and combustor were used from the ProMax tool suite while a custom module was created to simulate the SOFC stack. The model used an SOFC test data set as an input. Additional SOFC stack performance effects, such as pressure, temperature, and utilization of air and fuel, were added from open source data. System performance predictors were SOFC specific power, fuel-to-electricity conversion efficiency, and hybrid system efficiency. Using these input data and predictors, a static thermodynamic performance model was created that can be modified for different system configurati... [more]

The optimization of injection−production parameters is an important step in the design of gas injection development schemes, but there are many influencing factors and they are difficult to determine. To solve this problem, this paper optimizes injection-production parameters by combining an improved particle swarm optimization algorithm to study the relationship between injection-production parameters and the net present value. In the process of injection-production parameter optimization, the particle swarm optimization algorithm has shortcomings, such as being prone to fall into local extreme points and slow in convergence speed. Curve adaptive and simulated annealing particle swarm optimization algorithms are proposed to further improve the optimization ability of the particle swarm optimization algorithm. Taking the Tarim oil field as an example, in different stages, the production time, injection volume and flowing bottom hole pressure were used as input variables, and the optima... [more]

Carbonated produced water injection (CPWI) might be considered an efficient alternative to handle the largest waste stream while enhancing the oil recovery and storing carbon dioxide (CO2) underground. This study was an attempt to get a deeper understanding of the oil recovery process through synergy between spontaneous imbibition and isothermal titration calorimetry (ITC) experiments. The results from the spontaneous imbibition experiments showed 7% to 11% additional oil recovery in comparison with plain produced water. Rock−fluid and fluid−fluid interactions, evaluated by isothermal titration calorimetry (ITC) experiments, confirmed that the CPW interactions with oil+EFB+chalk and oil+EFB systems are much more exothermic than those with plain PW in those systems. The synergy between spontaneous imbibition and ITC experiments provides an improved understanding of carbonated water injection in carbonate reservoirs.

The paper endeavours to explore and analyse some critical issues in the oil and gas market that cropped up around the spread of COVID-19 and tries to identify the key drivers and triggers pertaining therewith. The spread of the first wave that began in March 2020 is crucial because of the global economic downturn that ensued due to lockdown and imposed restrictions coupled with a protracted oil price war that began between Saudi Arabia and Russia. The paper tries to address some key research questions to understand the triggers and drivers around the pandemic. These are: (1) whether the behaviour of OPEC or its key players around the pandemic could be considered uniquely different; (2) what could the triggers be for the increased volatilities that cropped up in both physical and financial markets during the pandemic; (3) what was really different about the oil market crisis around the pandemic that transformed it to an unprecedented storage crisis; (4) what really went wrong with the m... [more]

The main purpose of this study was to develop a photovoltaic module array (PVMA) and an energy storage system (ESS) with charging and discharging control for batteries to apply in grid power supply regulation of high proportions of renewable energy. To control the flow of energy at the DC load and charge/discharge the battery uniformly, this work adapted a bidirectional buck−boost soft-switching converter and the maximum power point tracking (MPPT) technique of the photovoltaic module array. First, a boost converter is used with the perturb and observe (P&O) method, so that the photovoltaic module array can work at the maximum power point (MPP) at any time. When the output power of the photovoltaic module array is greater than the load power, the excess power is used to charge the battery; on the contrary, if the output power of the photovoltaic module array is lower than the load power, the battery discharges for auxiliary power supply. This makes the voltage of the DC link maintain a... [more]

Changing the fuel mix used in the heating industry, i.e., switching to greener fuels, is one of the possible solutions to prevent rising costs for final consumers in the context of rising emission allowance prices. This paper presents a methodology that offers the possibility to perform a comprehensive technical and economic assessment of a theoretical solution—changing the fuel mix of centralized heating sources—and other strategic decisions within a district’s heating systems. Emphasis is placed on fuels with a negative price, such as municipal waste. The presented approach can also be used to assess the effect of other significant changes related to the configuration of district heating systems on the economy of the plant, such as the impact of a decrease in heat demand and implementation of a steam turbine. The key benefit of this paper is an approach based on mathematical modelling of the operation of individual boilers with different operating parameters in terms of their start-u... [more]

As one of the effective renewable energy sources, wind energy has received attention because it is sustainable energy. Accurate wind speed forecasting can pave the way to the goal of sustainable development. However, current methods ignore the temporal characteristics of wind speed, which leads to inaccurate forecasting results. In this paper, we propose a novel SSA-CCN-ATT model to forecast the wind speed. Specifically, singular spectrum analysis (SSA) is first applied to decompose the original wind speed into several sub-signals. Secondly, we build a new deep learning CNN-ATT model that combines causal convolutional network (CNN) and attention mechanism (ATT). The causal convolutional network is used to extract the information in the wind speed time series. After that, the attention mechanism is employed to focus on the important information. Finally, a fully connected neural network layer is employed to get wind speed forecasting results. Three experiments on four datasets show that... [more]

In the development of fault-tolerant systems, simulation is a common technique used to obtain insights into performance and dependability because it saves time and avoids the risks of testing the behavior of real-world systems in the presence of faults. Fault injection in a simulation offers a high controllability and observability, and thus is ideal for an early dependability analysis and fault-tolerance evaluation. Heating, ventilation, and air conditioning (HVAC) systems in critical infrastructures, such as airports and hospitals, are safety-relevant systems, which not only determine energy consumption, system efficiency, and occupancy comfort but also play an essential role in emergency scenarios (e.g., fires, biological hazards). Hence, fault injection serves as a practical and essential solution to assess dependability in different fault scenarios of HVAC systems. Hence, in this paper, we present a simulation-based fault injection framework with a combination of two techniques, s... [more]

In this study, we reported experimental results of a water droplet falling on trapezoidal grooved surfaces of heated silicon wafers with the groove width varied from 20 μm to 640 μm and the depth from 20 μm to 40 μm. Based on the observation of droplet dynamics captured by high-speed camera, we found that on the denser grooved surface, the maximum spreading diameter of the droplet perpendicular to the groove direction was smaller than that on the sparser grooved surface with the same groove depth. The residence time of the droplet on the denser grooved surface was shorter than that on the sparser grooved surface. The Leidenfrost point increased 50 °C with the groove width varied from 20 μm to 640 μm and decreased 10 °C when the depth was changed from 20 μm to 40 μm, which were higher than that on the smooth surface. Due to the deformation of the droplet during the droplet dynamics, it was difficult to calculate the heat transfer by measuring the droplet volume reduction rate. Based on... [more]

This article provides an overview of residential vapor-compression air conditioners operating under high ambient temperatures (HAT). For the purpose of this article, a minimum temperature criterion, 40 °C and above, was developed to evaluate studies that were conducted at HAT. Several HAT organizations and projects were launched with the purpose of assessing the performance of low-GWP (GWP = global warming potential) refrigerants when operating under HAT and accelerating the transition to such refrigerants. Previous studies of air conditioner improvements (i.e., for condensers, evaporators, compressors, and refrigerants) were discussed under HAT conditions. This article also explores the challenges, the possible design modifications, and several limitations of air conditioners operating under HAT. Condenser improvements showed an 18 to 50% higher coefficient of performance (COP) and an 8 to 30% higher cooling capacity. Only one study was found for evaporator enhancement under HAT which... [more]

Although photovoltaic (PV) systems play an essential role in distributed generation systems, they also suffer from serious safety concerns due to DC series arc faults. This paper proposes a lightweight convolutional neural network-based method for detecting DC series arc fault in PV systems to solve this issue. An experimental platform according to UL1699B is built, and current data ranging from 3 A to 25 A is collected. Moreover, test conditions, including PV inverter startup and irradiance mutation, are also considered to evaluate the robustness of the proposed method. Before fault detection, the current data is preprocessed with power spectrum estimation. The lightweight convolutional neural network has a lower computational burden for its fewer parameters, which can be ready for embedded microprocessor-based edge applications. Compared to similar lightweight convolutional network models such as Efficientnet-B0, B2, and B3, the Efficientnet-B1 model shows the highest accuracy of 96.... [more]

A magnetic lead screw (MLS) is a device that can help a wave energy converter (WEC) to transform the low-speed linear wave motion into high-speed rotary motion with no frictional contact. However, the dynamic performance of the MLS is insufficient because only the permanent magnet (PM) is used to couple the magnetic field between the rotor and mover. To improve the dynamic performance of the MLS, a novel structure of an electromagnetic lead screw (EMLS) for the application of a WEC is proposed in this paper. In the proposed EMLS, a helical-shaped PM is mounted on the inner side of the rotor, which is as same as the traditional MLS. However, helical-shaped slots are grooved on the surface of the mover, and two-phase helical-shaped AC winding is placed in these slots to generate the controlled helical-shaped magnetic field. In this paper, the topology and the operating theory are introduced firstly. Then, the three- and its corresponding two-dimensional axis-symmetric finite element anal... [more]

Petrophysics in unconventional reservoirs, especially multiscale characterization and multiphase flow, is relevant to multi-disciplinary porous media research (e [...]

The residential sector is a major contributor to the global energy demand. The energy demand for the residential sector is expected to increase substantially in the next few decades. As the residential sector is responsible for almost 40% of overall electricity consumption, the demand response solution is considered the most effective and reliable solution to meet the growing energy demands. Home energy management systems (HEMSs) help manage the electricity demand to optimize energy consumption without compromising consumer comfort. HEMSs operate according to multiple criteria, including electricity cost, peak load reduction, consumer comfort, social welfare, environmental factors, etc. The residential appliance scheduling problem (RASP) is defined as the problem of scheduling household appliances in an efficient manner at appropriate periods with respect to dynamic pricing schemes and incentives provided by utilities. The objectives of RASP are to minimize electricity cost and peak lo... [more]

The electromagnetic frequency regulator (EFR) device has proven to be an attractive solution for driving grid-connected electrical generators in distributed generation (DG) systems based on renewable energy sources (RES). However, the dynamic characteristic of the EFR has not yet been discussed for cases where its parameters vary from the nominal values. To evaluate this issue, this paper proposes a method for transient and steady-state performance analysis applied to the EFR device considering parametric variations. To perform this analysis, a dynamic model of the EFR device is derived, and its dynamic characteristics are discussed. Based on this model, the system’s controller gains are designed by using the root-locus method (RLM) to obtain the desired dynamic performance. Then, a sensitivity analysis of the closed-loop poles under the effect of parameters variation is performed. In addition, the paper also presents an analysis of the EFR-based system operating with the designed cont... [more]

With the ratification of the Paris Agreement at the Paris Climate Conference, reducing carbon emissions has become a global interest. Coal is one of the main industries causing carbon emissions; thus, quantifying carbon emissions from coal mining is an important step in reducing these emissions. Firstly, based on the life cycle idea, in this paper, we define the Carbon Emission Boundary of the fully mechanized coal mining method. Secondly, the carbon emission accounting model (B-R model) of fully mechanized coal mining is established, which includes the total amount of carbon emissions and the carbon emissions of each mining link during the mining process. The Fifth-II mining area of the Jinda Coal Mine in Tengzhou City is taken as an example. We collect the relevant data on carbon emissions in the mining process of the Jinda Coal Mine, and the B-R model is used to obtain the carbon emissions in the mining process of this mining area. Finally, the feasibility of the B-R model is furthe... [more]