The floating absorber for safety at transient (FAST) was proposed as a solution for the positive coolant temperature coefficient in sodium-cooled fast reactors (SFRs). It is designed to insert negative reactivity in the case of coolant temperature rise or coolant voiding in an inherently passive way. The use of the original FAST design showed effectiveness in protecting the reactor core during some anticipated transients without scram (ATWS) events. However, oscillation behaviors of power due to refloating of the absorber module in FAST were observed during other ATWS events. In this paper, we propose an improved FAST device (iFAST), in which a constraint is imposed on the sinking (insertion) limit of the absorber module in FAST. This provides a simple and effective solution to the power oscillation problem. Here, we focus on an oxide fuel-loaded SFR that is characterized by a more negative Doppler reactivity coefficient and higher operating temperature than the metallic-loaded SFR cor... [more]

The slopes of open-pit mines are often at risk of failure. To identify this hazard, stability analyses are performed. An important element of these stability analyses is the reliable selection of input parameter values for the calculations. This selection is difficult because the slopes of the open pit are disturbed by mining activities. In such conditions, rheological processes, intensified by weathering, develop in open-pit slopes. This study is aimed at setting the strength parameters for the stability analysis of open-pit slopes with a developed slide process, using the random set method. The study was performed on the example of the open pit of the Bełchatów lignite mine, central Poland. A four-stage methodology, according to the random set method, was proposed. The methodology covered the following: site investigation, sensitivity analyses, shear strength reduction (SSR) analyses using numerical calculations, and probability analyses of the factor of safety (FoS) calculation resu... [more]

Polyoxymethylene dimethyl ethers (PODE) are a newly appeared promising oxygenated alternative that can greatly reduce soot emissions of diesel engines. The combustion characteristics of the PODE and diesel blends (the blending ratios of PODE are 0%, 20%, 50% and 100% by volume, respectively) are investigated based on an optical engine under the injection timings of 6, 9, 12 and 15-degree crank angles before top dead center and injection pressures of 100 MPa, 120 MPa and 140 MPa in this study. The results show that both the ignition delay and combustion duration of the fuels decrease with the increasing of PODE ratio in the blends. However, in the case of the fuel supply of the optical engine being fixed, the heat release rate, cylinder pressure and temperature of the blend fuels decrease with the PODE addition due to the low lower heating value of PODE. The addition of PODE in diesel can significantly reduce the integrated natural flame luminosity and the soot formation under all injec... [more]

Nowadays, the increasing number of nonlinear loads and renewable energy resources pose new challenges for the standard electrical grid. Conventional solutions cannot handle most of them. The weakest component in the whole system is a conventional distribution (converting medium to low AC voltage) transformer. It should not operate with unbalanced, heavily distorted voltage and cannot control power flow or compensate current harmonics. One of the promising solutions to replace the conventional transformer and thus minimize power flow and grid distortions is a power electronics device called a solid state transformer (SST). Depending on the SST topology, it can have different functionalities, and, with the proper control algorithm, it is able to compensate any power imbalances in both low voltage (LV) and medium voltage (MV) grid sides. In the case of a three energy conversion stage SST, the LV and the MV stages can be treated separately. This paper focuses on the MV-AC to the MV-DC stag... [more]

The transient process is the key for the design, operation and maintenance of the pipeline network system of the water supply project. This paper aims to study and develop a new type of visual numerical simulation software for the transient process of pipeline network system. Firstly, the software architecture design is illustrated. Then, three tiers of software architecture, i.e., back-tier, middle-tier and front-tier, are studied and developed. Finally, the practical application procedure of the software is illustrated and the accuracy of calculation results is verified. The results indicate that the visual numerical simulation software is designed based on C/S architecture. The software architecture contains back-tier, middle-tier and front-tier. The back-tier includes the model and the algorithm. The middle-tier realizes the decoding of the topology of the pipeline network system and the interaction between the back-tier and the front-tier. The front-tier integrates the visual inte... [more]

The matrix pores of a coalbed methane (CBM) reservoir are mostly nanoscale pores, with tiny pore throats and poor connectivity, which belong to the category of low−permeability gas reservoirs. The matrix particles and organic pore surfaces adsorb a large amount of CBM. These problems are the main reasons that limit the increase in CBM production. At present, the primary measure to increase CBM production is hydraulic fracturing. However, due to the technical characteristics and geological conditions of CBM reservoirs, applying this technology to CBM exploitation still has some key issues that need to be resolved. Therefore, it is essential to develop a new technology that can effectively increase the production of CBM. This paper proposed a method that uses ultrasonic waves to improve the seepage characteristics of CBM reservoir and theoretically verifies the feasibility of this idea using numerical simulation. In this paper, we firstly coupled the temperature, pressure, and seepage pa... [more]

In order to predict the gasoline consumption in China, this paper propose a novel data-trait-driven rolling decomposition-ensemble model. This model consists of five steps: the data trait test, data decomposition, component trait analysis, component prediction and ensemble output. In the data trait test and component trait analysis, the original time series and each decomposed component are thoroughly analyzed to explore hidden data traits. According to these results, decomposition models and prediction models are selected to complete the original time series data decomposition and decomposed component prediction. In the ensemble output, the ensemble method corresponding to the decomposition method is used for final aggregation. In particular, this methodology introduces the rolling mechanism to solve the misuse of future information problem. In order to verify the effectiveness of the model, the quarterly gasoline consumption data from four provinces in China are used. The experimenta... [more]

Since there are not standard configurations of the Concentrating Photovoltaic (CPV) systems, several types of optics are designed and analyzed. In this paper, the optical performances of a spherical mirror and a commonly used Fresnel lens of the same diameter are compared, highlighting their impact on the CPV system energy performance. First, the absolute and percentual variation trends of optical concentration factor and optical efficiency as function of the distance between each optical system and receiver are analyzed. The concentration levels obtained by means of the spherical mirror are much higher than the Fresnel lens, with maximum values of optical efficiency equal to 72.8% and 24.1%, respectively. The analysis of the concentration reduction due to a solar-tracking failure has also allowed the estimation of the acceptance angle, thus observing that the spherical mirror requires a less accurate solar tracker with respect to the Fresnel lens, especially if a secondary optics is a... [more]

This paper aimed at evaluating the influence of different vertical equivalent damping ratios of a 3-dimensional combined isolation bearing (3D-CIB) as regards seismic response and isolation effectiveness. A comparative study of the seismic response in terms of acceleration floor response spectra (FRS), peak acceleration, displacement response of the nuclear reactor building, and dynamic response of the 3D-CIB was carried out. The results showed that: (1) the horizontal FRS is slightly influenced by the vertical equivalent damping ratio of 3D-CIB, whereas the increase of the vertical equivalent damping ratio has a significant effect on reducing the vertical FRS; (2) the peak vertical acceleration increased with the decrease in the vertical equivalent damping ratios of 3D-CIB and the difference of peak accelerations calculated by the damping ratio of 20 and 25% is within 10%; (3) the increase of the vertical equivalent damping ratio is capable of reducing the horizontal displacement and... [more]

Carbon capture and storage is considered an effective mitigation strategy to reduce the most challenging emissions from heavy industries and gas processing. The safe transport of carbon dioxide via pipelines is an important aspect for developing large-scale Carbon Capture and Storage projects. Dispersion modeling for heavy gas such as carbon dioxide is considerably different from natural gas. The set up for modeling simulations is more challenging than conventional natural gas pipeline for several reasons, such as the differences in thermodynamics that must be considered. Moreover, when the carbon dioxide is transported in dense or liquid phase, the rapid phase changing, and possible consequent formation of solids should be considered. Finally, the equation of state required for accurate prediction of parameters is generally different than the ones applicable for natural gas. The main scope of this comprehensive review is to identify the most important parameters, critical events, suit... [more]

Blue Economy represents a new and interesting concept on a global level, both from the economic potential but also by the fact that it can be used to reduce environmental degradation. The main goal of this research is to identify the causality relations between the greenhouse gas emissions, the Blue Economy and economic growth based on a panel of annual data from the 28 countries that are members of the European Union (EU) over the 2009−2018 period. After applying stationarity and cointegration tests, the long term cointegration coefficients shall be determined with the help of the fully modified ordinary least squares (FMOLS) estimator. Granger causality estimation based on the vector error correction model (VECM) was applied to identify the causality relationship between the variables and to detect the direction of causality. Based on the identified causality relations, the Blue Economy has a significant influence on greenhouse gas emissions in the long run. Unidirectional causality... [more]

The paper presents a new method for modelling the warming up process of a water system with elements regulating the flow in a stochastic manner. The paper presents the basic equations describing the work of typical elements which the water installation is composed of. In the proposed method, a new computational algorithm was used in the form of an iterative procedure enabling the use of boundary conditions that can be stochastically modified during the warming-up process. A typical situation, when such a modification is processed, is the regulation of the medium flow through two-way or three-way valves or applying additional heat source. Moreover, the presented method does not require the transformation of the differential equations, describing the operation of individual elements, into a linear form, which significantly facilitates analytical work and makes it more flexible. The example of analysis of the operation of water installation used for controlling temperature of the process... [more]

The optimal planning of grid-connected microgrids (MGs) has been extensively studied in recent years. While most of the previous studies have used fixed or time-of-use (TOU) prices for the optimal sizing of MGs, this work introduces real-time pricing (RTP) for implementing a demand response (DR) program according to the national grid prices of Iran. In addition to the long-term planning of MG, the day-ahead operation of MG is also analyzed to get a better understanding of the DR program for daily electricity dispatch. For this purpose, four different days corresponding to the four seasons are selected for further analysis. In addition, various impacts of the proposed DR program on the MG planning results, including sizing and best configuration, net present cost (NPC) and cost of energy (COE), and emission generation by the utility grid, are investigated. The optimization results show that the implementation of the DR program has a positive impact on the technical, economic, and enviro... [more]

The construction of charging infrastructure has a positive effect on promoting the diffusion of new energy vehicles (NEVs). This study uses natural language processing (NLP) technology to explore consumer preferences for charging infrastructure from consumer comments posted on public social media. The findings show that consumers in first-tier cities pay more attention to charging infrastructure, and the number of comments accounted for 36% of the total. In all comments, consumers are most concerned about charging issues, national policy support, driving range, and installation of private charging piles. Among the charging modes of charging piles, direct current (DC) fast charging is more popular with consumers. The inability to find public charging piles in time to replenish power during travel or high energy consumption caused by air conditioning is the main reason for consumers’ range anxiety. Increasing battery performance, improving charging convenience, and construction of batter... [more]

X-ray CT imaging provides a 3D view of a sample and is a powerful tool for investigating the internal features of porous rock. Reliable phase segmentation in these images is highly necessary but, like any other digital rock imaging technique, is time-consuming, labor-intensive, and subjective. Combining 3D X-ray CT imaging with machine learning methods that can simultaneously consider several extracted features in addition to color attenuation, is a promising and powerful method for reliable phase segmentation. Machine learning-based phase segmentation of X-ray CT images enables faster data collection and interpretation than traditional methods. This study investigates the performance of several filtering techniques with three machine learning methods and a deep learning method to assess the potential for reliable feature extraction and pixel-level phase segmentation of X-ray CT images. Features were first extracted from images using well-known filters and from the second convolutional... [more]

The presented paper, which is the first of two parts, shows the results of numerical investigations of a heat exchanger channel in the form of a cylindrical tube with a thin insert. The insert, placed concentrically in the pipe, uses the phenomenon of thermal radiation absorption to intensify the heat transfer between the pipe wall and the gas. Eight geometric configurations of the insert size were numerically investigated using CFD software, varying its diameter from 20% to 90% of the pipe diameter and obtaining the thermal-flow characteristics for each case. The tests were conducted for a range of numbers Re = 5000−100,000 and a constant temperature difference between the channel wall and the average gas temperature of ∆T = 100 °C. The results show that the highest increase in the Nu number was observed for the inserts with diameters of 0.3 and 0.4 of the channel diameter, while the highest flow resistance was noted for the inserts with diameters of 0.6−0.7 of the channel diameter. T... [more]

The main purpose of the paper is to present a proposal to measure the relationships between Goal 7 of the 2030 Agenda for Sustainable Development and one of the areas considered in the green growth concept: environmental production efficiency. Both of these areas illustrate the relationship between the natural environment and the economy, emphasizing transformations in the field of energy use. Selected taxonomic methods, TOPSIS, and multicriteria taxonomy, were applied to study the relationships between the two areas. The results of the EU countries classification showed a variety of countries’ development pathways within a single economic community. Despite continued attempts to equalize the development levels between European Union countries in many strategic areas, they remain highly diversified. That is also true for the areas analyzed in the paper, which is a disturbing situation, indicating that both strategies might not correlate in all respects. Further research into the relati... [more]

Optimal renewable energy source (RES) selection needs a strategic decision for reducing environmental pollutions, use of conventional resources, and improving economic development. In the process of RESs evaluation, several aspects like environmental, economic, social, and technical requirements play an important role. In addition, diverse factors affect the appropriate RES selection problem which adheres to uncertain and imprecise data. Thus, this selection process can be considered as a complex uncertain multi-criteria decision making (MCDM) problem. This study aims to introduce a novel integrated methodology based on Step-wise Weight Assessment Ratio Analysis (SWARA) and Combined Compromise Solution (CoCoSo) methods within single-valued neutrosophic sets (SVNSs) context, wherein the decision-makers and criteria weights are completely unknown. In the proposed approach, the criteria weights are determined by the SWARA method, and the most suitable RES alternative is determined by an i... [more]

In recent years, corporate involvement in CSR has become increasingly important and appreciated in the context of the ideas and assumptions regarding sustainable development. Due to the specificity of the energy sector, its particular impact on the environment, the living conditions of the population, and the social involvement of energy companies is particularly desirable, therefore it is observed and assessed by many stakeholder groups. The aim of this article is to assess the CSR commitment of Polish energy companies listed on the Warsaw Stock Exchange. The assessment was based on the proposed indicator model, based on the data published in the annual reports of the companies. The study uses data from the years 2016−2020. The main research question is as follows: What is the engagement in CSR activities of six Polish energy companies towards contractors, investors, employees, society, and the environment? The obtained results show that the investigated energy companies present a sim... [more]

In this study, we propose a four-plate structure with two shielding plates to produce shielded capacitive power transfer (S-CPT) at an operating frequency of 6.78 MHz for a 10 W system. By eliminating the inductors at the secondary side to form an asymmetrical topology, an S-CPT system was developed with a class-E power amplifier. Using MATLAB software, analysis was performed to obtain the parameters in the S-CPT system regarding resonance and impedance matching, and the proposed coupler structure was investigated through electric field simulation. The shield plate voltage stability was also investigated by analysing both the simulation and hardware experiment results. A prototype of S-CPT was established to validate the analysis results and to demonstrate the voltage at the shield plate of the proposed coupler structure. The experimental results are in good agreement with the simulation results. The proposed S-CPT exhibits an AC−AC efficiency of 84%, with a 56% voltage ground stabilit... [more]

With the increased emphasis on climate change and reducing harmful emissions in the atmosphere, interest in power electronics converters and electric motor drives has led to significant new developments in areas such as renewable energy systems or electric propulsion [...]

Power quality (PQ) has become an important topic in today’s power system scenario. PQ issues are raised not only in normal three-phase systems but also with the incorporation of different distributed generations (DGs), including renewable energy sources, storage systems, and other systems like diesel generators, fuel cells, etc. The prevalence of these issues comes from the non-linear features and rapid changing of power electronics devices, such as switch-mode converters for adjustable speed drives and diode or thyristor rectifiers. The wide use of these fast switching devices in the utility system leads to an increase in disturbances associated with harmonics and reactive power. The occurrence of PQ disturbances in turn creates several unwanted effects on the utility system. Therefore, many researchers are working on the enhancement of PQ using different custom power devices (CPDs). In this work, the authors highlight the significance of the PQ in the utility network, its effect, and... [more]

The assessment of the groundwater flow rate around the cavern periphery is a critical requirement for the design of underground water-sealed oil storage caverns and commonly made through seepage analysis, where a reasonable estimation of the hydraulic conductivity of the host rock is the key issue. However, it is a challenge to accurately determine the hydraulic conductivity of natural rock masses owing to their heterogeneous and anisotropic nature. The underground storage cavern project has a unique favorable condition in that there is a water curtain system that can provide considerable hydraulic test data for inferring hydraulic parameters; however, no well-established method has ever been proposed to exploit these data for characterizing heterogeneity in hydraulic conductivity. This study presents a new approach to evaluate the spatial variation of hydraulic conductivity using water curtain borehole data. This approach treats the peripheral region of each borehole as a homogenous u... [more]

(1) Background—The aim of this paper was to indicate whether the taxation of facilities related to renewable or low-emission energy differed significantly from that of facilities generating electricity from coal. (2) Methods—The research was conducted using a descriptive method, and because of the legal nature of the article, a crucial role was played by the dogmatic method. (3) Results—The thesis according to which only the “construction part” is subject to the property tax is the result of many years of disputes between the taxpayers and the tax authorities. In practice, it is difficult to compare the tax burden on assets related to coal and low-emission power generation because of the construction of the tax base in Polish property tax law. Most often, however, the tax burden on assets, which is calculated in the context of the amount of energy produced, tends to favour coal-fired power generation. (4) Conclusion: The property tax regulations in Poland treat the assets used for ener... [more]

The present study is focused on the development of a material model where the orthotropic-visco-elastic and orthotropic-visco-plastic mechanical behavior of a polymeric material is considered. The increasing need to reduce the climate-damaging exhaust gases in the automotive industry leads to an increasing usage of electric powered drive systems using Lithium-ion (Li-ion) batteries. For the safety and crashworthiness investigations, a deeper understanding of the mechanical behavior under high and dynamic loads is needed. In order to prevent internal short circuits and thermal runaways within a Li-ion battery, the separator plays a crucial role. Based on results of material tests, a novel material model for finite element analysis (FEA) is developed using the explicit solver Altair Radioss. Based on this model, the visco-elastic-orthotropic, as well as the visco-plastic-orthotropic, behavior until failure can be modeled. Finally, a FE simulation model of the separator material is perfor... [more]