bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study of Heat Transfer Enhancement by Arc-Shaped Fins in a Shell-Tube Thermal Energy Storage Unit
Authors: Chen Qicheng , Wu Junting , Sun Kanglong , Zhang Yingjin
Published: October 2022

Latent heat thermal energy storage (LHTES) technology can alleviate the mismatch between the supply and demand of solar energy and industrial waste heat, but the low thermal conductivity of phase change materials (PCMs) is an issue that needs to be solved. In this work, the effects of the bifurcated fins on melting and solidification are studied, and local and global entropy generation are discussed. The radial lag time and the circumferential lag time were defined to evaluate thermal penetration and thermal uniformity. Subsequently, a novel arc-shaped fin configuration was proposed to further enhance the heat transfer. The results showed that attaching the bifurcated fins could effectively reduce the global entropy generation. Increasing the trunk fin length was beneficial to enhance the thermal uniformity and promote the melting process, while increasing the branch fin was more effective in the solidification process. Overall, thermal uniformity determined the phase change process. More importantly, the concentric arc-shaped fins significantly reduced the heat transfer hysteresis region, showed better thermal performance than straights fins, and the energy storage and release time were reduced by 52.7% and 51.6%, respectively.
Analysis of the Influence of System Parameters on Launch Performance of Electromagnetic Induction Coil Launcher
Authors: Guan Shaohua , Guan Xiaocun , Wu Baoqi , Shi Jingbin
Published: October 2022

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes a pulse power supply and launcher. The parameters of the pulse power supply mainly include the discharge voltage and the capacitance value of the capacitor bank. The structural parameters of the launcher mainly include the bore size of the launcher, the air gap length between the armature and the drive coil, the length and width of the drive coil, and the trigger position of the armature. Change in single or multiple parameters in the launch system will influence the launch performance. The influence of single or multiple parameters on the launch performance was summarized, and the physical law as analyzed. The influence law of the EICL system parameters on the launch performance was obtained, which lays a theoretical foundation for the optimization design of EICL. Finally, experimental verification was carried out by a single-stage test platform.
Geochemical Characteristics of the Chang 7 Source Rocks of the Triassic Yanchang Formation in Ordos Basin, China: Implications for Organic Matter Accumulation and Shale Oil Potential
Authors: Hao Lewei , Ma Xiaofeng , Gao Wenqiang , Ren Zhaocai , Tao Huifei , Huang Weikai
Published: October 2022

The Chang 7 member of the Upper Triassic Yanchang Formation in the Ordos Basin is considered to hold the main source rocks for conventional and unconventional oil and gas. The lamination or lithology alteration in vertical and lateral directions, even over a short distance, is a common feature in lacustrine source rocks. The differences in the geochemical characteristics of black shales, dark mudstones and interbedded sandstones have been scarcely reported, and their influences on the petroleum generation potential and shale oil potential are not clear. To this end, 22 core samples were collected from the Lower and Middle Chang 7 (C7-3 and C7-2) members of the Triassic from well CYX in the Qingcheng area. By conducting a series of geochemical analyses including TOC, Rock-Eval pyrolysis yields, bitumen extraction and quantification, and the separation and quantification of saturates, aromatics, resins and asphaltenes, along with biomarker analyses, several results were found. Firstly, the C7-3 and C7-2 source rocks are thermally mature and have entered into the stage of hydrocarbon generation. The C7-3 and C7-2 source rocks have a good to very good hydrocarbon generation potential especially the C7-3 black shales. Secondly, terrigenous source input is more abundant in C7-2, whereas the source input of phytoplankton, algae or microbial lipids is more abundant in C7-3. Moreover, a high TOC content basically corresponds to low wax indexes, terrigenous/aquatic ratios (TARs), and Pr/nC17 and Ph/nC18 ratios and high C27/C29 regular sterane ratios, which suggests that the source input of phytoplankton, algae or microbial lipids is favorable for OM accumulation. Third, analyses of the molecular composition of saturated fractions in shales and interbedded sandstones and the production index demonstrate the migration of petroleum from organic-rich source rocks to their organic-lean counterparts. The C7-2 dark mudstones could be considered as a potential “sweet spot” since their oil saturation index (OSI) was the highest among all the studied samples and they are more enriched in light aliphatic fractions.
Calculation Method for Assessing the Storage Capacity of Nitrogen Compounds in LNT Reactors
Authors: Kamela Wojciech , Wojs Marcin K. , Orliński Piotr
Published: October 2022

The presented study describes proprietary calculation methods that simulate the process of storing nitrogen dioxide elevation in a catalytic LNT reactor. The first section’s points of reference are the achievements of the article’s authors and the possibility of modeling NO2 adsorption processes in LNT reactors. The rest of the article presents model calculations (proposed by the authors) of the course of the NO2 storage process in LNT reactors. It considers one in its transition period, affecting the improvement and duration of the adsorption process. The conclusion presents selected results of simulation calculations obtained with the help of the equations’ authors and an evaluation of the results. A review of theoretical considerations is consistent with the experimental data, suggesting that the proposed computational solution may be used in future analytical validity assessments of LNT reactor tools under operating conditions.
Simulation-Based and Data-Driven Techniques for Quantifying the Influence of the Carbon Binder Domain on Electrochemical Properties of Li-Ion Batteries
Authors: Knorr Tobias , Hein Simon , Prifling Benedikt , Neumann Matthias , Danner Timo , Schmidt Volker , Latz Arnulf
Published: October 2022

Most cathode materials for Li-ion batteries exhibit a low electronic conductivity. Therefore, a considerable amount of conductive additives is added during electrode production. A mixed phase of carbon and binder provides a 3D network for electron transport and at the same time improves the mechanical stability of the electrodes. However, this so-called carbon binder domain (CBD) hinders the transport of lithium ions through the electrolyte and reduces the specific energy of the cells. Therefore, the CBD content is an important design parameter for optimal battery performance. In the present study, stochastic 3D microstructure modeling, microstructure characterization, conductivity simulations as well as microstructure-resolved electrochemical simulations are performed to identify the influence of the CBD content and its spatial distribution on electrode performance. The electrochemical simulations on virtual, but realistic, electrode microstructures with different active material content and particle size distributions provide insights to limiting transport mechanisms and optimal electrode configurations. Furthermore, we use the results of both the microstructure characterization and electrochemical simulations to deduce extensions of homogenized cell models providing improved predictions of cell performance at low CBD contents relevant for high energy density batteries.
Automated Cybersecurity Tester for IEC61850-Based Digital Substations
Authors: Hong Junho , Song Tai-Jin , Lee Hyojong , Zaboli Aydin
Published: October 2022

Power substations are the crucial nodes of an interconnected grid, serving as the points where power is transferred from the transmission/distribution grids to the loads. However, interconnected cyberphysical systems and communication-based operations at substations lead to many cybersecurity vulnerabilities. Therefore, more sophisticated cybersecurity vulnerability analyses and threat modeling are required during productization phases, and system hardening is mandatory for the commercialization of products. This paper shows the design and methods to test the cybersecurity of multicast messages for digital substations. The proposed vulnerability assessment methods are based on the semantics of IEC61850 Generic Object Oriented Substation Event (GOOSE) and Sampled Value (SV), and cybersecurity features from IEC62351-6. Different case scenarios for cyberattacks are considered to check the vulnerabilities of the device under test (DUT) based on the IEC62351-6 standard. In order to discover security vulnerabilities in a digital substation, the proposed cybersecurity tester will generate malicious packets that compromise the regular functionality. The results show that the proposed cybersecurity testing module is able to detect potential vulnerabilities in multicast messages and the authentication methods (e.g., message authentication code) of multicast communications. Both commercial and simulated devices are used for the case studies.
A Numerical Study on the Decomposition and Diffusion Characteristics of SF6 in Gas-Insulated Switchgear with Consideration of the Temperature Rising Effect
Authors: Jia Chenglong , Zhao Wenbin , Zhu Yong , Lu Wu , Tang Zhong
Published: October 2022

The optimized concentration of SF6 gas is the key to maintaining a good insulation performance by GIS equipment. The precise measurements of the SF6 concentration and decomposition byproducts could be used to indicate the remaining GIS insulation level during long-term operations. In this paper, a finite-element simulation model was created to investigate the SF6 gas decomposition and diffusion dynamics. A theoretical analysis and simulation of the overheating fault, i.e., the contact between the GIS disconnect switches, were carried out, followed by an estimation of the SF6 decomposition and diffusion characteristics caused by the local heating faults, based on the calculated flow velocity field and temperature field.
Porcellio scaber Latr. and Lumbricus terrestris L.—PAHs Content and Remediation of Long-Term Aging Soil Contamination with Petroleum Products during a Single- and Two-Species Experiment
Authors: Gospodarek Janina , Petryszak Przemysław , Kafel Alina , Paśmionka Iwona B.
Published: October 2022

The presence of earthworms in soil contaminated with petroleum products (PPs) increase the rate of decomposition. The use of more than one animal species simultaneously in soil remediation could accelerate the process. However, the effects may be different when long-term aging soil contamination exists during which toxic by-products can be formed. This study evaluated the effect of soil contamination with PPs (petrol, diesel fuel, and used engine oil) carried out 12 and 24 months earlier on the life parameters of Lumbricus terrestris L. during single- and dual-species breeding with Porcellio scaber Latr. The changes in the content of total petroleum hydrocarbons (TPH) in the soil were also measured, as were the levels of polycyclic aromatic hydrocarbon (PAH) accumulation in the bodies of the test animals. Survival of earthworms cultivated separately (single-species experiment) in soil contaminated with diesel fuel 12 months earlier significantly decreased, while body mass gain was not significantly changed under the influence of tested PPs. Breeding of L. terrestris together with P. scaber contributed to significant mortality of earthworms regardless of treatments, while woodlice showed much greater resistance to PPs. Occurrence of both animals in soil contaminated with engine oil 24 months earlier resulted in a significant reduction in TPH after 4 weeks (by 29% compared to the initial soil). The content of PAHs in the tissues of L. terrestris was higher than in P. scaber, and the highest amounts of PAHs were found when earthworms were exposed to engine oil. Use of L. terrestris together with P. scaber can be considered a promising scenario for increasing the effectiveness of remediation of soils contaminated with petroleum products, however, further research is needed to establish conditions preventing excessive mortality of earthworms in such a layout.
Class-C Pulsed Power Amplifier with Voltage Divider Integrated with High-Voltage Transistor and Switching Diodes for Handheld Ultrasound Instruments
Authors: Choi Hojong
Published: October 2022

A novel Class-C pulsed power amplifier with a voltage divider integrated with a high-voltage transistor and switching diodes is proposed to reduce DC power consumption and increase the maximum output power for handheld ultrasound instruments. Ultrasonic transducers in ultrasound instruments are devices that convert electrical power into acoustic power or vice versa, which are triggered by power amplifiers. Efficient power conversion is also very important to avoid thermal issues in handheld ultrasound instruments owing to limited battery power and excessive heat generation caused by the enclosed structures of the handheld ultrasound instruments. Consequently, higher output power and lower DC power consumption are desirable for a power amplifier. Therefore, a circuit to control power amplifiers was developed. The measured output power (94.66 W) and DC power consumption (2.12 W) when using the proposed circuit are better than those when using the existing Class-C pulsed power amplifier (74.90 W and 2.77 W, respectively). In the pulse-echo measurement mode, the echo amplitude (12.34 mVp-p) and bandwidth (27.74%) of the proposed Class-C pulsed power amplifier were superior to those of the existing Class-C pulsed power amplifier (4.38 mVp-p and 23.25%, respectively). Therefore, the proposed structure can improve the performance of handheld ultrasound instruments.
Antarctic Shipborne Tourism: Carbon Emission and Mitigation Path
Authors: Li Guomin , Li Wei , Dou Yinke , Wei Yigang
Published: October 2022

The rapidly increasing concentrations of carbon dioxide lead to a threat of global climate change. As one of the major sources of carbon emissions in the Antarctic region, shipborne tourism in the Antarctic is expanding rapidly. Consequently, the carbon emissions of shipborne tourism in Antarctica are rapidly increasing. However, there is not enough attention being paid to this issue. In this paper, a calculation model was established to calculate the carbon emissions of cruise ships from the 2003/04 season to the 2016/17 season. The evolution of the carbon emissions from Antarctic cruise ships was described. An aggregate energy efficiency index was developed to evaluate the energy efficiency performance of Antarctic vessels. The key drivers were analyzed to find the paths of carbon reduction. The results show that: (1) The emissions per passenger-trip did not show a downward trend. The total carbon emissions increased continuously with the increasing number of tourists. The total carbon emissions in the 2016/17 season was double that in the 2003/04 season. (2) The aggregate energy efficiency index of Antarctic tour vessels has not reached an advanced level yet. It is the main reason for the high value of emissions per passenger-trip. (3) Due to the oversupply of Antarctica tour ships, there is a low rate of occupancy, which accounts for the decline in aggregate energy efficiency from the 2014/15 season to the 2016/17 season. This study suggests that the administrators of Antarctica should strengthen supervision of the tourism market, control the rapid growth in the number of cruise ships, improve the aggregate energy efficiency of cruise ships and form an efficient and green Antarctic tourism management system.
Water Energy in Poland in the Context of Sustainable Development
Authors: Piwowar Arkadiusz , Dzikuć Maciej
Published: October 2022

The current production of water energy in Poland is much lower than the theoretical and technical potential. The aim of the article is to analyse the current state of hydropower in Poland as well as the prospects and conditions for development. Poland's total technical hydropower potential is estimated at 12,000–14,000 GWh/year, but currently, approx. 20% of this potential is used. The considerations undertaken in the study concern, for example, pumped-storage power plants and the development of small hydropower plants. Hydropower plants are not only important from the point of view of electricity production and storage, but also fulfill many other functions, including the general social, which is an essential element of the implementation of the concept of sustainable development. The analyses show that the hydropower sector in Poland may be an important element of low-carbon energy and an important element of energy security. Increasing the volume of electricity production from hydropower by 5% will contribute to the growth in CO2 reduction by 140,702 tons. The stabilization function of the power system in Poland is also significant.
An Experimental and Numerical Study of Abrupt Changes in Coal Permeability with Gas Flowing through Fracture-Pore Structure
Authors: Li Lin , Zhang Shufan , Li Zhiqiang , Chen Xiangjun , Wang Lin , Feng Shuailong
Published: October 2022

Coal permeability is related to the fracture-pore structure of coal and is a key factor in determining gas drainage efficiency. The characteristics of the methane flow in coal fractures are different from those in coal matrix pores. However, due to the difficulty of observing fast methane flow in coal fractures, the effect of gas flow in coal fractures on coal permeability has seldom been considered and investigated. In this study, a cylindrical coal sample is used for the measurement of coal permeability under different gas pressures, and an abrupt change in coal permeability evolution was observed. Then, a tandem fracture-pore permeability model was adopted to analyze these new methane flow phenomena. In this permeability model, the deformation of coal fractures was directly analyzed and modeled without the reversed derivation. With the consideration of elastic modulus of coal fractures, the deformation of coal fractures is controlled by the effective strain of coal fractures, the adsorption-induced strain and effective strain of coal matrix. The research results show that (1) coal fractures quickly and significantly influence coal permeability by resisting coal deformation; (2) a complete evolution of coal permeability consists of the fast permeability change caused by methane flow in coal fractures and the slow permeability change caused by methane flow in coal matrix; (3) the low efficiency of gas mass exchange between coal fractures and coal matrix leads to a two-stage evolution for gas desorption flow and coal permeability.
Modular SEPIC-Based Isolated dc–dc Converter with Reduced Voltage Stresses across the Semiconductors
Authors: Ewerling Marcos Vinicius Mosconi , Lazzarin Telles Brunelli , Illa Font Carlos Henrique
Published: October 2022

This paper presents the theoretical analysis, experimental results and generalized structure for N modules of an isolated dc–dc SEPIC converter. The structure comes from the integration of N conventional SEPIC converters based on the input-series and output-parallel connection. The main advantages provided by the proposed structure are reduced voltage stress across the semiconductors and division of the current stress in the output diodes. The proposed converter is presented in a generalized approach, varying the voltage stress across the semiconductors according to the number of modules used. As the converter uses more than one switch, the commands can be either equal or phase-shifted by 360∘/N degrees. When operating with phase-shift modulation, a multilevel converter is obtained, which brings another advantage of the structure, since there is a reduction in the volume of the input inductors (Li1 and Li2) and the output capacitor (Co). In this paper, the steady-state analysis, a dynamic model, system control and experimental results are presented for phase-shift modulation and discontinuous conduction mode (DCM). The performance of the proposed converter was verified in a prototype with four modules and the following specifications: 500 W output power, 800 V input voltage, 120 V output voltage and 50 kHz switching frequency. The converter achieved 94.42% efficiency at rated power.
Urban Energy Management—A Systematic Literature Review
Authors: Modrzyński Paweł , Karaszewski Robert
Published: October 2022

Environmental protection is currently one of the key priority areas of the European Union (EU). The search for effective solutions for the supply and use of energy in cities is currently a key topic. The reduction in gas emissions and the use of renewable energy sources are goals that result from environmental aspects. The purpose of this publication is to conduct a literature review in the area of municipal energy management. Municipal energy management systems integrate many areas, from energy supply systems and the modernization of public transport to the energy demand reduction of residential and commercial facilities. The results of the literature review research have allowed for the classification of articles based on the following criteria: research methodology, research purpose, research data collection method, use of research results article type, and research subject area.
Optimal Design of Permanent Magnet Synchronous Machine Based on Random Walk Method and Semi 3D Magnetic Equivalent Circuit Considering Overhang Effect
Authors: Kim Su-min , Jung Woo-Sung , Kim Woo-Hyeon , Bang Tae-Kyoung , Lee Dae-Hyun , Kim Yong-Joo , Choi Jang-Young
Published: October 2022

Permanent magnet synchronous machines (PMSMs) with an overhang structure can increase power density by compensating for the increased magnetic energy of permanent magnets. To analyze the overhang structure, a three-dimensional (3D) analysis of PMSMs is essential. However, 3D analysis takes a long time and the modeling process is complicated in the initial design stage. To overcome these problems, a magnetic equivalent circuit technique is applied to the 2D model. In this paper, an optimal design method for PMSMs with an overhang structure is proposed based on the semi 3D magnetic equivalent circuit (MEC) and random walk method. By using semi 3D MEC, it is possible to quickly analyze PMSM and obtain accurate electromagnetic analysis results considering the overhang effect. Moreover, the volume and weight of PMSM can be minimized by optimizing the rotor’s four design parameters using a random walk algorithm. To obtain high efficiency, the objective function is selected so that copper loss is minimized under the same constraints. The validity of the proposed design technique is verified by comparing the analysis results of semi 3D MEC and 3D finite element method for the derived optimal model.
Regional Photovoltaic Power Forecasting Using Vector Autoregression Model in South Korea
Authors: Jung A-Hyun , Lee Dong-Hyun , Kim Jin-Young , Kim Chang Ki , Kim Hyun-Goo , Lee Yung-Seop
Published: October 2022

Renewable energy forecasting is a key for efficient resource use in terms of power generation and safe grid control. In this study, we investigated a short-term statistical forecasting model with 1 to 3 h horizons using photovoltaic operation data from 215 power plants throughout South Korea. A vector autoregression (VAR) model-based regional photovoltaic power forecasting system is proposed for seven clusters of power plants in South Korea. This method showed better predictability than the autoregressive integrated moving average (ARIMA) model. The normalized root-mean-square errors of hourly photovoltaic generation predictions obtained from VAR (ARIMA) were 8.5–10.9% (9.8–13.0%) and 18.5–22.8% (21.3–26.3%) for 1 h and 3 h horizon, respectively, at 215 power plants. The coefficient of determination, R2 was higher for VAR, at 4–5%, than ARIMA. The VAR model had greater accuracy than ARIMA. This will be useful for economical and efficient grid management.
Active Filtering of Inverter Output Waveforms Based on Orthogonal Space Vector Theory
Authors: Muc Adam , Iwaszkiewicz Jan
Published: October 2022

This paper presents a DC/AC converter consisting of two two-level inverters. The complex converter is built using two standard three-phase inverters: the main inverter (MI) and the auxiliary one (AI). The MI is controlled in a simple way to generate the stepped output voltage and the AI works as an active filter limiting the higher harmonics in the MI output voltage. The filtering process is based on the orthogonal space vector theory. A development and modification of the basic solution are presented here. The output voltage of the MI takes the shape of a stepped voltage comparable to the voltage generated by multilevel inverters. The AI operates as a very effective active power filter (APF) of the MI output voltage. The AI power is significantly lower in comparison to the MI power.
Performance Evaluation of the Impact of Clustering Methods and Parameters on Adaptive Neuro-Fuzzy Inference System Models for Electricity Consumption Prediction during COVID-19
Authors: Oladipo Stephen , Sun Yanxia , Amole Abraham
Published: October 2022

Increasing economic and population growth has led to a rise in electricity consumption. Consequently, electrical utility firms must have a proper energy management strategy in place to improve citizens’ quality of life and ensure an organization’s seamless operation, particularly amid unanticipated circumstances such as coronavirus disease (COVID-19). There is a growing interest in the application of artificial intelligence models to electricity prediction during the COVID-19 pandemic, but the impacts of clustering methods and parameter selection have not been explored. Consequently, this study investigates the impacts of clustering techniques and different significant parameters of the adaptive neuro-fuzzy inference systems (ANFIS) model for predicting electricity consumption during the COVID-19 pandemic using districts of Lagos, Nigeria as a case study. The energy prediction of the dataset was examined in relation to three clustering techniques: grid partitioning (GP), subtractive clustering (SC), fuzzy c-means (FCM), and other key parameters such as clustering radius (CR), input and output membership functions, and the number of clusters. Using renowned statistical metrics, the best sub-models for each clustering technique were selected. The outcome showed that the ANFIS-based FCM technique produced the best results with five clusters, with the Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Coefficient of Variation (RCoV), Coefficient of Variation of the Root Mean Square Error (CVRMSE), and Mean Absolute Percentage Error (MAPE) being 1137.6024, 898.5070, 0.0586, 11.5727, and 9.3122, respectively. The FCM clustering technique is recommended for usage in ANFIS models that employ similar time series data due to its accuracy and speed.
System Frequency Control Method Driven by Deep Reinforcement Learning and Customer Satisfaction for Thermostatically Controlled Load
Authors: Chen Rusi , Liu Haiguang , Liu Chengquan , Yu Guangzheng , Yang Xuan , Zhou Yue
Published: October 2022

The intermittence and fluctuation of renewable energy aggravate the power fluctuation of the power grid and pose a severe challenge to the frequency stability of the power system. Thermostatically controlled loads can participate in the frequency regulation of the power grid due to their flexibility. Aiming to solve the problem of the traditional control methods, which have limited adjustment ability, and to have a positive influence on customers, a deep reinforcement learning control strategy based on the framework of soft actor–critic is proposed, considering customer satisfaction. Firstly, the energy storage index and the discomfort index of different users are defined. Secondly, the fuzzy comprehensive evaluation method is applied to evaluate customer satisfaction. Then, the multi-agent models of thermostatically controlled loads are established based on the soft actor–critic algorithm. The models are trained by using the local information of thermostatically controlled loads, and the comprehensive evaluation index fed back by users and the frequency deviation. After training, each agent can realize the cooperative response of thermostatically controlled loads to the system frequency only by relying on the local information. The simulation results show that the proposed strategy can not only reduce the frequency fluctuation, but also improve customer satisfaction.
COVID-19 Impact on the Energy Sector in the United States (2020)
Authors: Vaz Warren S.
Published: October 2022

This study comprehensively examines the effects of the COVID-19 pandemic on energy consumption in the United States. The purpose of the study is to quantify the effects of lockdowns and pandemic disruptions on energy consumption trends in order to inform policymakers and utilities on how to prepare for such events in the future. The study focuses on 2020 data collected by the Federal government. The effects are quantified using descriptive statistics. State-wise and sector-wise data have been presented using plots and heat maps. Related metrics like COVID case data, GDP, emissions, and expenditures were also presented. The total energy consumption fell by 7.5% in 2020. Besides Alaska, every state saw a decrease in energy, with some as high as 26%. The residential sector had the most states that saw an increase in energy, stemming from lockdowns and working from home. Similarly, petroleum consumption saw a decrease of 11.4% as a result of a decrease in travel. Biomass-related renewable energy generation fell by 23% due to decreased demand, while all other sources increased by 7.3%. Carbon dioxide emissions fell by 10.4%, methane by 2.8%, and nitric oxide by 6.7%. The overall per capita energy expenditure for the country dropped by 18.5%. There was a stronger correlation between GDP and energy consumption than between GDP and COVID case counts. The pandemic did not affect each state or sector evenly. The statistics and correlations presented here can be used in the ongoing effort to study the global impact of the pandemic and prepare for future challenges.
Influence of Radial Flows on Power Density and Gas Stream Pressure Drop of Tubular Solid Oxide Fuel Cells
Authors: Essaghouri Abdellah , Zeng Zezhi , Zhao Bingguo , Hao Changkun , Qian Yuping , Zhuge Weilin , Zhang Yangjun
Published: October 2022

The development of solid oxide fuel cells (SOFCs) for powering vehicles requires high power densities. The radial flows generated by the insert structures in SOFC fuel channels could improve the power density by facilitating the fuel to enter the porous anode for electrochemical reactions. In this paper, we developed a 2D axisymmetric numerical model to examine the influence of a convergent conical ring insert on the flow and mass transfer characteristics in a tubular SOFC. The mass transfer conductance of fuel was analyzed and proposed to quantify the performance of different insert designs. The effects of the radius and offset angle of the convergent conical ring insert were examined and analyzed. We demonstrate that increasing the insert radius could increase the fuel mass transfer conductance and effectively improve the net output power of the tubular SOFC by 12% while the offset angle of the inserts exhibits a negligible impact on the fuel mass transfer conductance. Increasing the offset angle could help reduce the gas-phase pressure drop in fuel channels by 42%. The present study helps improve our understanding of the relationship between fuel mass transfer conductance and electrochemical reactions. It also proposes channel design methods based on mass transfer conductance for high-power-density solid oxide fuel cells.
Local Evolution Model of the Communication Network for Reducing Outage Risk of Power Cyber-Physical System
Authors: Fang Yuchen , Tang Xiafei , Tang Li , Chen Yang , Wang Weiyu
Published: October 2022

The deep integration of power grids and communication networks is the basis for realizing the complete observability and controllability of power grids. The communication node or link is always built according to the physical nodes. This step is alternatively known as “designing with the same power tower”. However, the communication networks do not form a “one-to-one correspondence” relationship with the power physical network. The existing theory cannot be applied to guide the practical power grid planning. In this paper, a local evolution model of a communication network based on the physical power grid topology is proposed in terms of reconnection probabilities. Firstly, the construction and upgrading of information nodes and links are modeled by the reconnection probabilities. Then, the power flow entropy is employed to identify whether the power cyber-physical system (CPS) is at the self-organized state, indicating the high probability of cascading failures. In addition, on the basis of the cascading failure propagation model of the partially dependent power CPS, operation reliabilities of the power CPS are compared with different reconnection probabilities using the cumulative probability of load loss as the reliable index. In the end, a practical provincial power grid is analyzed as an example. It is shown that the ability of the power CPS to resist cascading failures can be improved by the local growth evolution model of the communication networks. The ability is greater when the probability of reconnection is p = 0.06. By updating or constructing new links, the change in power flow entropy can be effectively reduced.
A BiLSTM-Based DDoS Attack Detection Method for Edge Computing
Authors: Zhang Yiying , Liu Yiyang , Guo Xiaoyan , Liu Zhu , Zhang Xiankun , Liang Kun
Published: October 2022

With the rapid development of smart grids, the number of various types of power IoT terminal devices has grown by leaps and bounds. An attack on either of the difficult-to-protect end devices or any node in a large and complex network can put the grid at risk. The traffic generated by Distributed Denial of Service (DDoS) attacks is characterised by short bursts of time, making it difficult to apply existing centralised detection methods that rely on manual setting of attack characteristics to changing attack scenarios. In this paper, a DDoS attack detection model based on Bidirectional Long Short-Term Memory (BiLSTM) is proposed by constructing an edge detection framework, which achieves bi-directional contextual information extraction of the network environment using the BiLSTM network and automatically learns the temporal characteristics of the attack traffic in the original data traffic. This paper takes the DDoS attack in the power Internet of Things as the research object. Simulation results show that the model outperforms traditional advanced models such as Recurrent Neural Network (RNN) and Long Short Term Memory (LSTM) in terms of accuracy, false detection rate, and time delay. It plays an auxiliary role in the security protection of the power Internet of Things and effectively improves the reliability of the power grid.
Analysis of Exhaust Emissions from Heavy-Duty Vehicles on Different Applications
Authors: Ziółkowski Andrzej , Fuć Paweł , Lijewski Piotr , Jagielski Aleks , Bednarek Maciej , Kusiak Władysław
Published: October 2022

Emissions from the road transport sector are a major contributor to the climate change. Commonly used heavy vehicles powered by diesel engines emit toxic and harmful compounds that adversely affect the environment. For this reason, increasingly newer Euro emission standards are being introduced. Therefore, the emission performance of heavy-duty vehicles used in the transportation processes of diverse loads was investigated. The first research object was a set of vehicles equipped with a crane used for loading and unloading timber. The measurements were carried out in a specially designed research test reflecting the way the vehicle is used. It consisted of the drive to the loading site, the transport of timber to the destination and the processes of loading and unloading timber. The test route included driving on both unpaved forest roads and asphalt roads. The second research object was a set of vehicles used in long-distance road transport. The research route characterizing the traffic of vehicles from the cited group was selected here. There were three stages of the route–urban, extra-urban and highway. The whole trip was carried out with a load of 24,800 kg. The testing equipment consisted of SEMTECH DS and AVL Micro Soot Sensor devices belonging to the PEMS (Portable Emission Measurement System) group. Based on the obtained results, the influence of the operating conditions on the exhaust emissions and fuel consumption was determined.
Hybrid Carbonated Engineered Water as EOR Solution for Oil-Wet Carbonate Formation
Authors: Ghosh Bisweswar , Kilybay Alibi , Thomas Nithin Chacko , Haroun Mohammed , Rahman Md Motiur , Belhaj Hadi
Published: October 2022

Carbonated water has proven advantages over conventional CO2 injection in terms of arresting free CO2 mobility, low-pressure injection, lower volume requirement, and higher efficiency. The term “engineered water” is designated to selective ion-spiked injection water with the advantage of the ion-exchange reactions with the rock minerals and releasing trapped oil. This article investigated the synergic effect of dissolved CO2 and engineered water for oil recovery and understanding inner mechanisms. Recovery efficiencies were evaluated through coreflood studies, which revealed that the hybrid water could recover 6–10% more oil than engineered water and about 3% more than carbonated water. HP-HT pendant-drop studies show the insignificance of IFT reduction. Wettability change from oil wet to near-water wet is attributed as a significant factor. The dissolution of Ca2+ and Mg2+ and deposition of SO42− observed in coreflooding may have a significant contribution to oil recovery. Pore enlargement evidenced in NMR-PSD and NMR-ICP results support this claim. The study confirmed that the EWI-CWI hybrid technique could be a promising EOR method, eliminating the requirement for high-pressure injection, the problems of gravity segregation, and the early breakthrough of CO2. It can also be an effective EOR solution, providing a significant cost advantage and higher oil recovery in addition to the environmental benefits of CO2 sequestration.
Development of a Biomass Gasification Process for the Coproduction of Methanol and Power from Red Sea Microalgae
Authors: Al-Rabiah Abdulrahman A. , Al-Dawsari Jiyad N. , Ajbar Abdelhamid M. , Al Darwish Rayan K. , Abdelaziz Omar Y.
Published: October 2022

In this study, an algae biomass gasification process using a dual fluidized bed with combined power and methanol cogeneration was developed. The gasification process was modeled using Aspen Plus and validated using experimental data of two microalgae species (Nannochloropsis oculata and Dunaliella salina) commonly found on the western coast of Saudi Arabia. The impacts of different operating conditions, including the gasifier temperature, steam-to-biomass ratio, and algae-char split ratio, on the compositions of four main gases (CO, CO2, CH4, and H2) were investigated. The results of the parametric studies indicated that the gasification temperature has a significant effect on the composition of the synthesis gas, where 700–850 °C was the ideal operating range for gasification. Altering the ratio of biomass to steam showed a slightly smaller effect on the synthesis gas composition. The char split ratio should be kept below 75% to ensure an adequate heat supply to the process. The proposed process successfully converted 45.7% of the biomass feed to methanol at a production capacity of 290 metric tons per day. On the other hand, 38 MW of electricity capacity was generated in the combined power cycle.
Combustion, Ecological, and Energetic Indicators for Mixtures of Hydrotreated Vegetable Oil (HVO) with Duck Fat Applied as Fuel in a Compression Ignition Engine
Authors: Shepel Oleksandra , Matijošius Jonas , Rimkus Alfredas , Orynycz Olga , Tucki Karol , Świć Antoni
Published: October 2022

The aim of the present study was to investigate the effects of the application of hydrotreated vegetable oil (HVO) mixed with pure duck fat (F100) as fuel, replacing the conventional fossil diesel fuel (D100). The tests were performed using a four-stroke direct injection CI engine diesel engine. Six fuel samples were used: D100, HVO100, F100, as well as three HVO–fat mixtures F25, F50, and F75. To further study the main characteristics of fuel combustion, the AVL BOOST software (Burn program) was applied. The results of experimental studies showed that with the addition of pure fat to HVO, the ignition delay phase increased with an increase in the amount of heat released during the premix combustion phase and the pressure and temperature rise in the cylinder increased; however, the mentioned parameters were not higher as compared to diesel fuel. It was found that as the concentration of fat in the HVO–fat mixtures increases, the viscosity and density increases, while LHV was decreased, which thereby increases brake specific fuel consumption and slightly decreases brake thermal efficiency in comparison to diesel fuel. A decrease of CO2, HC, NOx emissions, and smoke was established for all HVO–fat mixtures as compared to diesel fuel at all loads; however; under low loads, CO emissions increased.
Parameters Identification of Proton Exchange Membrane Fuel Cell Model Based on the Lightning Search Algorithm
Authors: Mohanty Banaja , Madurai Elavarasan Rajvikram , Hasanien Hany M. , Devaraj Elangovan , Turky Rania A. , Pugazhendhi Rishi
Published: October 2022

The fuel cell is vital in electrical distribution networks as a distributed generation in today’s world. A precise model of a fuel cell is extensively required as it rigorously affects the simulation studies’ transient and dynamic analyses of the fuel cell. This appears in several microgrids and smart grid systems. This paper introduces a novel attempt to optimally determine all unknown factors of the polymer exchange membrane (PEM) fuel cell model using a meta-heuristic algorithm termed the Lightning search algorithm (LSA). In this model, the current–voltage relationship is heavily nonlinear, including several unknown factors because of the shortage of fuel cell data from the manufacturer’s side. This issue can be treated as an optimization problem, and LSA is applied to detect its ability to solve this problem accurately. The objective function is the sum of the squared error between the estimated output voltage and the measured output voltage of the fuel cell. The constraints of the optimization problem involve the factors range (lower and upper limit). The LSA is utilized in minimizing the objective function. The effectiveness of the LSA-PEM fuel cell model is extensively verified using the simulation results performed under different operating conditions. The simulation results of the proposed model are compared with the measured results of three commercial fuel cells, such as Ballard Mark V 5 kW, BCS 500 W and Nedstack PS6 6 kW, to obtain a realistic study. The results of the proposed algorithm are also compared with different optimized models to validate the model and, further, to determine where LSA stands in terms of precision. In this regard, the proposed model can yield a lower SSE by more than 5% in some cases and high performance of the LSA-PEMFC model. With the results obtained, it can be concluded that LSA prevails as a potential optimization algorithm to develop a precise PEM fuel cell model.
Nickel in the Environment: Bioremediation Techniques for Soils with Low or Moderate Contamination in European Union
Authors: Vischetti Costantino , Marini Enrica , Casucci Cristiano , De Bernardi Arianna
Published: October 2022

The review deals with the environmental problem caused by low or moderate nickel concentrations in soils. The main effects of this potentially toxic element on the soil biota and the most common crop species are addressed. Moreover, the paper emphasises biological remediation methods against nickel pollution in European soils. The focus is on the well-accepted phytoremediation strategy alone or in combination with other more or less innovative bioremediation approaches such as microbial bioremediation, vermiremediation and the use of amendments and sequestrants. Results acquired in real field and laboratory experiments to fight against nickel contamination are summarised and compared. The main objective was to evidence the ability of the above natural techniques to reduce the nickel concentration in contaminated sites at a not-risky level. In conclusion, the examined works agree that the efficiency of phytoremediation could be implemented with co-remediation approaches, but further studies with clear and comparable indices are strongly recommended to meet the challenges for future application at a large scale.
The Rich Get Stronger: The Purse Seine Fishery of the Turkish Straits System
Authors: Koyun Sefer Furkan , Yıldız Taner , Ulman Aylin
Published: October 2022

Purse seiners generally try to maximize their revenues by targeting multiple species, starting with the most valuable ones available. The technology and capacity of purse seiners can be exceptionally high for the stocks found in the Marmara Sea, Turkey’s only inland sea, due to its small size and nearly totally enclosed nature. Due to their large capabilities, they are responsible for the majority of catches and hence declines from this sea and thus should be held responsible for the poor state of marine stocks in the region. This study examines the catch compositions, expenses, and revenue sharing of purse seiners by using one representative vessel class for each of the four vessel length categories in the Marmara Sea. Surveys were also conducted with purse seine fishers to assess their perceptions related to fisheries management strategies along with their ideas for transitioning towards sustainable fisheries. As purse seiners are prominent stakeholders in the Marmara Sea fisheries, they should be incorporated into management guidance for effectiveness, along with other stakeholders. This study provides novel socio-economic data along with their perspectives, which may assist in improving policy decisions and capabilities. Our results demonstrate that purse seiners do not consider that their actions are a contributing factor to the current state of the fisheries, they trust in their amassed historical local knowledge, and seem to want to rebuild the resources, however only with minimal rules imposed on their sector.