A regional integrated energy system (RIES) is an electricity-centric multi-energy system that can realize the mutual conversion of electricity, heat, cold, and other energy. Through multi-flexible resource interaction and the transaction of multi-investment entities, the efficiency of energy utilization can be improved. To systematize energy-consuming entities and scale photovoltaic-based renewable energy in a distribution network, the energy-consuming behavior, energy-producing schedule, and trading strategy can be coupled. Considering the interaction between the energy-consuming behavior and the uncertainty of distributed photovoltaic output, an optimal operation method for RIES is proposed on the basis of social network theory and an uncertain evolutionary game method in this paper. From the perspective of the operator, the overall profits of RIES are maximized considering the entity characteristics of both the demand and the supply side. A case study shows that the proposed method... [more]

Plasma parameters of radiofrequency discharge generated at low pressures in an argon-oxygen mixture addressed for biomedical surface sterilization have been optimized. Numerical results illustrate the density distributions of different species and electron temperatures during the electrical discharge process. The current discharge acting in the abnormal range decreases at higher oxygen gas flow rates. The temperature of electrons drops with pressure while it rises by adding oxygen. Nevertheless, electron density displays an adverse trend, exhibited by the electron’s temperature. The average particle density of the reactive species is enhanced in Ar/O2 compared to He/O2, which ensures a better efficiency of Ar/O2 in sterilizing bacteria than He/O2. The impact of oxygen addition on the discharge mixture reveals raised oxygen atom density and a reduction in metastable oxygen atoms. A pronounced production of oxygen atoms is achieved at higher frequency domains. This makes our findings pro... [more]

In the case of the energy sector (including mining companies) and the implementation of their development projects, it is necessary to obtain a social license to operate for a given project, which is associated with the involvement of various groups of stakeholders in the project and should be consistent with the company’s strategy. The basis for obtaining permission to operate is to conduct a stakeholder mapping process. Such an analysis will aid effective dialogue with all stakeholders and guide appropriate relationship building. The aim of this paper is to present the authors’ method of stakeholder mapping, which is an independent methodical idea that can be implemented in any enterprise. This paper comprehensively presents this algorithm, starting with the identification of stakeholder groups, through the determination of their level of interest and influence, ending with the construction of a matrix indicating the necessity of undertaking specific communication activities. Finally... [more]

Both long-distance oil and gas pipelines often pass through areas with unstable geological conditions or natural disasters. As a result, they are prone to bending, displacement, and deformation due to the action of an external environmental loading, which poses a threat to the safe operation of pipelines. The in-line inspection method that is based on the implementation of high-precision inertial measurement units (IMU) has become the main means of pipeline bending stress-strain detection technique. However, to address the problems of the inconsistent identification, low identification efficiency, and high misjudgment rate during the application of the traditional manual identification methods, a feature identification approach for the in-line inspected pipeline bending strain based on the employment of an optimized deep belief network (DBN) model is proposed in this work. In addition, our model can automatically learn features from the pipeline bending strain signals and complete clas... [more]

Lubricants are substances of the foremost importance in the modern world, as they are essential to the proper functioning of various mechanisms. Most lubricants, however, are still made from petroleum fractions. I light of this, and due to various environmental problems, the search for feasible biolubricants has become essential. This study obtained biolubricants through the in situ transesterification of microbial biomass, containing at least 20 wt% of lipids. The following two distinct biomasses were evaluated: the marine microalgae, Dunaliella salina, and the consortium of microalgae-fungi, Scenedesmus obliquus and Mucor circinelloides. Microbial oil from both biomasses presented a fatty acid profile with high amounts of oleic acid. The oil of D. salina had a lower content of polyunsaturated fatty acids relative to the microbial consortium profile, which indicates that this is a good configuration for increasing biolubricant oxidation resistance. The catalyst used was a Keggin-struc... [more]

Wireless power transfer (WPT) is a well-known problem, and has received wide attention in the next generation industrial applications and consumer electronics. On the other hand, frequency diverse array (FDA) is a new concept with the ability to generate a range-angle dependent beampattern. Therefore, some researchers are engaged in designing WPT systems based on the FDA framework (FDA-WPT) instead of phased arrays. Unlike phased arrays, the FDA beampattern is time-variant. Therefore, existing beam collection efficiency models based on the phased array are not suitable for the FDA-WPT system. More importantly, the time-variant property of FDAs is usually ignored in the literature, and the system configuration of the target area where the power-harvesting end is located does not conform to the actual WPT scenario. In this paper, we derive and present accurate models of the FDA-WPT system. The power transfer performance of the corrected FDA-WPT system is then compared with the phased arr... [more]

The magnetic levitation reaction flywheel (MLRW) is a novel actuator of spacecraft attitude control because of its significant advantages, including lack of friction and active suppression of vibration. However, in a vacuum environment, the poor heat dissipation conditions make it more sensitive to various losses and rises in temperature. Therefore, increasing temperature is the key issue for components used in space. In this study, the losses of the three kinds of heat-generating areas in the MLRW, namely, the passive magnetic bearing (PMB), the active magnetic bearing (AMB) and brushless DC motor (BLDCM), were analyzed and calculated. Based on the electromagnetic field theory, the loss model of PMB was proposed. Based on the finite element method (FEM) and Bertotti model, the loss power of the AMB and the BLDCM was obtained. The calculated loss values were brought into the FEM to calculate the temperature field distribution of the MLRW system. Then, the key factors affecting the heat... [more]

This paper aims to find the optimal size of parameters of a C-type filter in a non-sinusoidal system using a new optimization method called the Archimedes optimization algorithm (AOA). The inductance and capacitance values of the filter are acquired in which the power loss in the Thevenin resistor and the power loss characteristics of the load bus are minimized based on a new proposed objective function. Subject to technical and practical limitations of the IEEE 519 standard, an optimization problem is defined to achieve an optimal filter design that can increase the system power quality. The effectiveness of the proposed method is proved by comparison with the recent previously published methods. The results show the effectiveness of the proposed approach using the AOA in finding the minimum power losses and the harmonic content of frequency-dependent components. Eventually, the current study confirmed that the suggested objective function minimizes power losses of fundamental and har... [more]

With the increase in the penetration of battery electric vehicles (BEVs) all over the world, utilities should start considering their increased demand as part of their electric demand. Generally, the literature lacks works that consider the impact of transportation electrification on the reliability of the power system. Thus, this paper proposes a new mechanism for reliability assessment including BEVs, with both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) modes. Three charging strategies: uncontrolled, controlled unidirectional, and controlled bidirectional are considered in this paper to model the interactions between the transportation and electric power systems. A dynamic stochastic consumption model for a fleet of BEVs is developed to be used in the reliability assessment for the distribution networks. This dynamic model takes into consideration the variability and uncertainty of different trip purposes, starting and ending trip times, as well as the corresponding battery cons... [more]

Pumps as turbines are widely used in the world, wherein the hydraulic thrust of a turbine pump is one of the key factors affecting the safe and stable operation of a unit. There are a lot of difficulties to evaluate the hydraulic thrust by site observation and experiment. These difficulties can be resolved if a numerical simulation is applied. The present work aims to analyze the axial and radial hydraulic thrust of a prototype turbine pump in turbine mode, and then to determine the dynamic response characteristics of the turbine pump shafting. The axial hydraulic thrust in the turbine mode is upward, with a fluctuation range of 155 t to 175 t. The pressure fluctuation in the runner can be 16% of the unit head. The simulation results provide a good reference for understanding the hydraulic performance of the turbine pump and useful guidance for the operation of the unit. The structure analysis shows that the runner has asymmetrical deformation in the axial and radial directions. The am... [more]

Measures taken by the public administration to prevent the spread of the COVID-19 pandemic have led to drastic consequences for the economy. The full identification of its effects is hindered due to the delay in publishing the results of public statistics. The use of financial reports prepared by self-government authorities of all municipalities in Poland made it possible to obtain preemptive information in relation to the public statistics regarding the impact of COVID-19-related limitations on the energy expenditures incurred by local government units (LGUs), as well as an assessment of to what extent the LGUs had rationalized the energy consumption. By contrast, data from reports of energy companies made it possible to determine the impact of restrictions arising from the pandemic on the amount of energy sold and revenues from sales made by these companies. The analyses use indexes of the dynamics of changes in energy prices as well as indexes of the dynamics of changes in energy ex... [more]

In China, with the increasing permeability of wind power, the power supply capacity is enough overall, but has shortage in partial-time. During peak hours, the capability of wind power consumption is poor and the power balance becomes more difficult. In order to maximize the utilization of wind power, the net loads are chosen as the response objectives, which contain significant uncertainties and have no probabilistic distribution characteristics. Under the traditional day-ahead power dispatch mode with fixed length time intervals and in the regions with insufficient hydroelectricity, the thermal generators take charge of the peak-load shaving. The frequent adjustments of thermal power output affect the system operation safety, economic benefits, and environmental benefits. Thus, a time-interval-varying optimal power dispatch strategy based on net load time-series characteristics is proposed in this paper. The net loads respond differently to intervals. The length of each time interval... [more]

One of the important factors affecting the anchoring force of the end encapsulated bolt is the mechanical properties of the rock formation at the anchoring end. For the fully encapsulated bolt, its bearing performance is closely related to the mechanical properties of the bolt passing through the rock stratum and its permutation mode. In this study, a series of laboratory pull-out tests of multi-strata anchorage systems was carried out based on an actual engineering background. The bearing performances and failure mechanisms of the multi-strata anchorage system under different anchoring methods and combinations of rock stratum were studied. The evolution law of the axial force and shear stress of the Agent-Rock interface was also analyzed. The test results showed that, for end encapsulation, changes in the mechanical properties of the rock strata at the anchoring end caused differences in bearing capacity, while full-length encapsulation markedly reduced the disparities. The position o... [more]

The energy efficiency of a renewable energy system is inextricably linked to the energy storage technologies used in conjunction with it. The most extensively utilized energy storage technology for all purposes is electrochemical storage batteries, which have grown more popular over time because of their extended life, high working voltage, and low self-discharge rate. However, these batteries cannot withstand the very low temperatures encountered in cold regions, even with these very promising technical characteristics. The cold northern temperatures affect the batteries’ electromotive force and thus decrease their storage capacity. In addition, they affect the conductivity of the electrolyte and the kinetics of electrochemical reactions, thus influencing the capacity and speed of electrons in the electrolyte. In this article, which is intended as a literature review, we first describe the technical characteristics of charge−discharge rate of different electrochemical storage techniqu... [more]

Thermal comfort in cities is increasingly becoming a concern and comfortable places can be highly valuable for a variety of activities. Our investigation aims to explore how to improve the quality of cities by considering the relationship between microclimatic conditions, thermal sensation, and human preferences. The case study conducted in the open areas of Tallinn University of Technology (TalTech) campus, which is quite populated by visitors, staff, and students. We used a mixed-methods approach to assess outdoor thermal comfort, based on qualitative and quantitative findings of the relationships between the measured weather conditions and the results of thermal comfort assessment through the PET index and subjectively perceived thermal sensation. In the qualitative part, data was collected through semi-structured interviews. The main conclusions from the interviews were used to design a survey and the samples. Based on the results, it was possible to identify places that offer diff... [more]

In the present paper, an investigation into Thailand’s energy demand is performed to determine if: (1) a linear or nonlinear Engel curve better explains the relationship between income and energy consumption, and (2) systems with pre-commitments better model energy consumptions. Four demand systems are estimated: an almost ideal demand system (AIDS), the quadratic almost ideal demand system (QAIDS), generalized almost ideal demand system (GAIDS), and the generalized quadratic almost ideal demand system (GQAIDS). Elasticities are calculated for policy implications. The empirical results suggest that models considering pre-commitments and nonlinear Engel curves may be slightly more appropriate for Thailand’s energy system, from both statistic and economic standpoints. Statistical inferences appear to favor the GQAIDS model based on the encompassing results. Economic reasonability also appears to favor the GQAIDS model, in particular, petroleum products, as it provides results consistent... [more]

The controlled short-circuit transfer is used to control the heat input of the molten pool and the base metal in the cold metal transfer welding process, including droplet formation, droplet transfer and molten pool flow. Based on the influence of arc pressure on the surface of the molten pool, droplet impact and residual energy on the flow behavior of the molten pool, this research proposes the arc pressure driving model, the droplet impact driving model and the residual energy transfer model on the molten pool surface respectively, and on this basis, a theoretical model of controlled driving and spreading of the cold metal transition bath is proposed. The theoretical relationship between the surface shape of the keyhole and the driving force, and the relationship between the surface shape of the molten pool and the welding current are established. The model accurately predicts the formation width and contact angle of the molten pool in a specific interval, which can better control th... [more]

The low-carbon transition of the power system is essential for China to achieve peak carbon and carbon neutrality. However, China could suffer power shortages due to radical policies in some extreme cases. The gap between power demand and supply from March 2021 to November 2021 ranged between 5.2 billion kW·h and 24.6 billion kW·h. The main reason for the power shortage was over-reliance on renewable energy and insufficient coal power supply for the power system. The low-carbon transformation path of the electric system needs to be explored with more flexibility for power security. This study applied a modified LEAP model and carried out a forecast analysis of thermal power generation and installed capacity in 2025 and 2030 under normal and extreme weather scenarios. The results suggested that: the installed capacity of thermal power will need to account for about 44.6−46.1% of power generation in 2025 and 37.4−39.3% in 2030, with the assumption of power shortages caused by the instabi... [more]

The study aims to develop a system of models and a method for optimizing the operating modes of a catalytic reforming unit using fuzzy information, which makes it possible to effectively control the reforming process of the object under study. The object of study of this work is a catalytic reforming unit that has been operating for more than half a century and is characterized by the lack of clarity of some part of the initial information. The research methods are methods of system analysis, mathematical modeling, multicriteria optimization, and expert assessments, as well as methods of theories of fuzzy set theories, which allows formalizing and using fuzzy information, as well as experimental-statistical methods. As a result of the conducted research, the following main results were obtained. Based on a systematic approach, an effective methodology has been developed for developing a system of models of interconnected plant units using various types of available information, includi... [more]

The purpose of this study is to determine Girona Cathedral’s thermal performance and to verify that it is suitable for containing historical pieces of art. We present the results of our analysis of the indoor thermal conditions during the period from January 2011 to December 2016. Real data were collected from strategically located probes inside the cathedral and from an outside weather station. The results were compared with an EnergyPlus computer model to verify the calculations and improve decision making. The model considers the envelope’s thermal inertia, the characteristics of the enclosure, and the passive systems for performing thermal analysis. The cathedral’s indoor environment is very stable. Because of a high capability of thermal-energy accumulation, a one-month thermal lag between indoor and outdoor temperatures exists. Furthermore, the maximum and minimum temperatures are dampened, with a two-degree variation above or below the outdoor average, depending on the season. T... [more]

The findings of the analysis of data on the accident rate of power transformers indicate that one of the main causes of their failures is a decrease in the dielectric strength of the insulation. To reduce failures and extend the service life of power transformers in operation, the issue of enhancing the techniques for assessing the condition of their internal insulation becomes relevant. Currently, when selecting the major insulation of transformers, one takes into account the dependency of the dielectric strength of the oil passage on its width. Experts discuss the issues involved in the choice of major insulation while taking into account the effect of the generalized factor being the volume of the oil passage. The solution to that problem largely depends on the study of the statistical characteristics of the dielectric strength of oil passages of different volumes and the effect rated parameters of transformers have on them. The efficiency of the application of such diagnostic chara... [more]

Electric energy metering plays a crucial role in ensuring fair and equitable transactions between grid companies and power users. With the implementation of the State Grid Corporation’s energy Internet strategy, higher requirements have been put forward for power grid companies to reduce costs and increase efficiency and user service capabilities. Meanwhile, the accuracy and real-time requirements for electric energy measurements have also increased. Electricity information collection systems are mainly used to collect the user-side energy metering data for the power users. Attributed to communication errors, communication delays, equipment failures and other reasons, some of the collected data is missed or confused, which seriously affects the refined management and service quality of power grid companies. How to deal with such data has been one of the important issues in the fields of machine learning and data mining. This paper proposes a collaborative fitting algorithm to solve the... [more]

Offshore wind (OSW) has the potential to cut greenhouse gas (GHG) emissions and halt damaging climate change. However, policies to foster an OSW industry in Norway have long been small and scarce. Recent events suggest that this is changing, as the state-owned enterprise Enova decided to grant a record NOK 2.3 bn to build the world’s largest floating offshore wind farm in 2019, the Hywind Tampen project. Based on previous work by the corresponding author, we summarize the political development of OSW in Norway to distil generalisable lessons. The corresponding author employed interviews, document analysis and process tracing, using a theory of policy change to characterise the observed political change. She found that the main obstacle for early OSW deployment has been that environmental and visibility concerns have exacerbated energy−political ones that are created by a longstanding lack of local energy demands. As the green energy demand on a global scale is soaring, the lack of OSW... [more]

Current transportation and, in general, mobility have a negative impact on our environment [...]

The underlying circuit control is a key problem of the hybrid energy-storage system (HESS) in electric vehicles (EV). In this paper, a composite non-linear control strategy (CNC) is proposed for the accurate tracking current/voltage of the fully-active HESS by combining the exact feedback linearization method and the sliding mode variable structure control technology. Firstly, by analyzing the circuit characteristics of HESS, the affine non-linear model of fully-active HESS is derived. Then, a rule-based energy management strategy (EMS) is designed to generate the reference current value. Finally, the HESS is linearized by the exact feedback linearization method, and the proposed CNC strategy is developed combined with sliding mode variable structure control technology to ensure fast response, high performance, and robustness. At the same time, the stability proof based on the Lyapunov method is given. Moreover, the performance of the CNC strategy is thoroughly investigated and compare... [more]