bluuebunny/crossref_metadata_2025 huggingface dataset:
Financial Technology (FinTech) as a Financial Development Factor in the EU Countries
Authors: Lavrinenko Olga , Čižo Edmunds , Ignatjeva Svetlana , Danileviča Alina , Krukowski Krzysztof
Published: February 2023

The aim of the research is to determine the impact of financial technology (FinTech) on financial development in EU countries. The multi-dimensional nature of the concepts described above and the low availability of data for regions smaller than countries makes it difficult to investigate the link between financial development and FinTech, as well as affects the values of the results due to a certain averaging of indices across countries. The study examines the Global FinTech Index and the Financial Development Index, which characterize financial development in the EU countries, as well as the sub-indices of the Financial Development Index. The article applies frequency analysis and correlation analysis methods. A positive linear relationship between the Global Fintech Index and the Financial Markets Index sub-index, as well as its components Financial Markets Depth Index and Financial Markets Efficiency Index, has been identified. There is also a positive linear relationship between the Global FinTech Index and the Financial Institutions Depth Index, while a negative linear relationship has been identified between the Global FinTech Index and the Financial Institutions Access Index.
Incorporating Problem-Posing into Sixth-Grade Mathematics Classes
Authors: Kovács Zoltán , Báró Emőke , Lócska Orsolya , Kónya Eszter
Published: February 2023

Problem-posing is an essential component of mathematics education because, among other reasons, when students are given the opportunity to pose their problems, they can take ownership of their learning and become more engaged in the given subject. Thus, problem-posing can lead to a deeper understanding of the studied mathematical concepts. In a collaborative action research study, the authors explored whether well-structured problem-posing activities could be incorporated into classes with students of mixed ability in mathematics. This question is addressed by examining the correlation between students’ mathematics grades and problem-posing success. The problem-posing approach used in this paper relies on problem solving as a parallel activity. Hence, the study also focuses on the relationship between problem posing and problem solving. The paper presents the results of a classroom experiment with 86 sixth-grade students and their teachers from Hungary and Romania. After evaluating the students’ problem-posing products and problem-solving performances, the results show that problem posing, based on a worked-out model problem, is a feasible challenge for most students. Moreover, this experiment identified a direct relationship between successful problem posing and problem solving.
Viewpoints on the Development of Critical Thinking Skills in the Process of Foreign Language Teaching in Higher Education and the Labor Market
Authors: Poštić Svetozar , Kriaučiūnienė Roma , Ivancu Ovidiu
Published: February 2023

This paper analyzes the different viewpoints of the participants in four focus groups discussing critical thinking (CT) in teaching/studying foreign languages. Three of them were conducted at Vilnius University and one at the Public Service Language Centre in Vilnius, Lithuania. All of the interviewees agree about the importance of critical thinking, although they define it differently and emphasize a number of various aspects needed for its acquisition and application. Both students/trainees and instructors/trainers describe several classroom activities that stimulate CT and suggest implicit and explicit methods for evaluating it. The focus group discussions were conducted as part of the international projects Think4Jobs, whose main task was to determine the gap between CT as it is taught at institutions of higher education and in the labor market. Answering this question, the participants mention the unpredictability of the labor market, the usefulness of CT for many different jobs and the importance of teaching it for the acquisition of foreign languages.
MVPN: A Defense Architecture against VPN Traffic Hijacking Based on MTD
Authors: Gao Zhen , Chen Fucai , Wang Yawen , He Weizhen , Shi Xin , Xie Genlin
Published: February 2023

With the increasing awareness of privacy protection, Virtual Private Networks (VPNs) are widely used to build a more secure communication tunnel. However, a traffic hijacking attack called blind in/on-path has seriously threatened the security of VPNs. Inspired by Moving Target Defense (MTD), Moving VPN architecture (MVPN) is designed to defend against such attacks. MVPN includes multiple nodes to encrypt and decrypt traffic to enhance reliability. Thus, the consistency judgment algorithm is proposed to make MVPN obtain the ability to perceive attacks. Moreover, according to the judgment result and the state update strategy, the MVPN state is dynamically changed so as to achieve the purpose of active defense. In addition, this paper also designs the multichannel packet classification mechanism and availability assurance strategy, which not only ensures the security and availability of the system but also reduces the performance loss caused by the defense strategy. The simulation verifies that MVPN architecture can reduce the success rate of blind in/on-path attacks by five orders of magnitude. In addition, we implemented and deployed MVPN based on the fast-forwarding framework of the Data Plane Development Kit (DPDK). Experiments in the real environment also show that the MVPN system can effectively prevent attackers from carrying out blind in/on-path attacks.
Combined Economic Emission Dispatch in Presence of Renewable Energy Resources Using CISSA in a Smart Grid Environment
Authors: Azeem Muhammad , Malik Tahir Nadeem , Muqeet Hafiz Abdul , Hussain Muhammad Majid , Ali Ahmad , Khan Baber , Rehman Atiq ur
Published: February 2023

The geographically spatial and controlled distribution of fossil fuel resources, catastrophic global warming, and depletion of fossil fuel resources have forced us to integrate zero- or low-emissions energy resources, such as wind and solar, in the generation mix. These renewable energy resources are unexhausted, available around the globe, and free of cost. The advancement in wind and solar technologies has caused an appreciable decrease in installed the and global levelized costs of electricity via these sources. Therefore, the penetration of renewable energy resources in the generation mix can provide a promising solution to the above-mentioned problems. The aim of simultaneously reducing fuel consumption in terms of “Fuel Cost” and “Emission” in thermal power plants is called a combined economic emission dispatch problem. It is a combinatorial and multi-objective optimization problem. The solution of this problem is to allocate the load demand and losses on the committed units in such way that the overall costs of the generation and emission of thermal units are reduced, while the legal bounds (constraints) are met. It is a highly non-linear and complex optimization problem. The valve-point loading effect makes this problem non-convex. The addition of renewable energy resources (RERs) adds more complexities to this problem because they are intermittent. In this work, chaotic salp swarm algorithms (CISSA) are used to solve the combined economic emission dispatch problem. Chaos is used as an alternative to randomization for the tuning of the control variable to improve the trait of obtaining global extrema. Different test cases having different combinations of thermal, solar, and wind units are solved using the proposed algorithm. The results show the superiority of this study in comparison to the existent research results in terms of the cost of generation and emissions.
Air Defense Interception Plan Generation Method Based on Modified A* Optimization Algorithm
Authors: Song Xiaocheng , Li Zhi , Feng Shuting , Li You , Sun Liang , Jiang Jingjing
Published: February 2023

Aiming at the air defense task requirements for an enemy’s large-scale aircraft attack, this paper presents a plan generation algorithm which can quickly give an interception scheme. The main contribution of this paper is the modification of the standard A* algorithm and its combination of the optimization algorithm and air-defence mission. Firstly, the enemy’s attack weapon and our defense platform are modeled, and kinetic equations and interception efficiency functions are constructed, and the intercepted criterions are established. Then, the interception-cost mixed optimal function is established to clarify the system optimization objective. Secondly, aiming at the characteristics of strong time sensitivity of air defense interception, a modified A* optimization algorithm with fast convergence characteristics is used to solve the optimization problems, the standard A* algorithm is modified and the optimal air defense interception plan under the condition of mixed performance index is given. Finally, the proposed method is verified by numerical simulations.
Judging Stock Trends According to the Sentiments of Stock Comments in Expert Forums
Authors: Chang Zhichao , Zhang Zuping
Published: February 2023

Machine learning has been proven to be very effective and it can help to boost the performance of stock price predictions. However, most researchers mainly focus on the historical data of stocks and predict the future trends of stock prices by designing prediction models. They believe that past data must hide useful information in the future. Due to the lack of human participation, the result of this practice must be accidental. To solve this problem, we propose a novel model called Convolutional Neural Network with Sentiment Check (CNN-SC) in this paper. The model recommended by the authors refers to and expands upon the ideas of experts, and then takes the sentiment value in expert comments as the basis for stock price prediction. This model reflects the humanization of stock price prediction and eliminates the problem of a lack of supervision in machine learning. To demonstrate the effectiveness of our novel method, we compare it with five other popular and excellent methods. Although the C-E-SVR&RF and GC-CNN models are also quite effective, our results indicate the superiority of CNN-SC and it is accurately used to calculate the short-term (seven days later) stock price fluctuation of a single stock.
Review of Methodologies and Metrics for Assessing the Quality of Random Number Generators
Authors: Crocetti Luca , Nannipieri Pietro , Di Matteo Stefano , Fanucci Luca , Saponara Sergio
Published: February 2023

Random number generators are a key element for various applications, such as computer simulation, statistical sampling, and cryptography. They are used to generate/derive cryptographic keys and non-repeating values, e.g., for symmetric or public key cyphers. The strength of a data protection system against cyber attacks corresponds to the strength of the weakest point in the security chain. Therefore, from a mathematical point of view, the security chain can be compromised even if the strongest algorithm is implemented. In fact, if the system requires keys or other random values and the generation process shows a certain vulnerability, the security of the system itself can be compromised. In this article, we present the most reliable tools and methodologies and the main standardisation efforts in the field of computer security to assess the quality of random number generators and ensure that they can be applied to computer security applications by offering adequate security strength. We offer a comprehensive guide that can be used as a quick and practical reference by developers of random number generators of any type to evaluate the random bit streams generated by implemented modules and determine whether or not they can be used in cybersecurity applications. Finally, we also present some use cases to which we applied the presented approach.
Evaluating the Performance of Fuzzy-PID Control for Lane Recognition and Lane-Keeping in Vehicle Simulations
Authors: Samuel Moveh , Yahya Khalid , Attar Hani , Amer Ayman , Mohamed Mahmoud , Badmos Tajudeen Adeleke
Published: February 2023

This study presents the use of a vision-based fuzzy-PID lane-keeping control system for the simulation of a single-track bicycle model. The lane-keeping system (LKS) processes images to identify the lateral deviation of the vehicle from the desired reference track and generates a steering control command to correct the deviation. The LKS was compared to other lane-keeping control methods, such as Ziegler–Nichols proportional derivative (PD) and model predictive control (MPC), in terms of response time and settling time. The fuzzy-PID controller had the best performance, with fewer oscillations and a faster response time compared to the other methods. The PD controller was not as robust under various conditions due to changing parameters, while the MPC was not accurate enough due to similar reasons. However, the fuzzy-PID controller showed the best performance, with a maximum lateral deviation of 2 cm, a settling time of 12 s, and Kp and Kd values of 0.01 and 0.06, respectively. Overall, this work demonstrates the potential of using fuzzy-PID control for effective lane recognition and lane-keeping in vehicles.
Automated Pre-Play Analysis of American Football Formations Using Deep Learning
Authors: Newman Jacob , Sumsion Andrew , Torrie Shad , Lee Dah-Jye
Published: February 2023

Annotation and analysis of sports videos is a time-consuming task that, once automated, will provide benefits to coaches, players, and spectators. American football, as the most watched sport in the United States, could especially benefit from this automation. Manual annotation and analysis of recorded videos of American football games is an inefficient and tedious process. Currently, most college football programs focus on annotating offensive formations to help them develop game plans for their upcoming games. As a first step to further research for this unique application, we use computer vision and deep learning to analyze an overhead image of a football play immediately before the play begins. This analysis consists of locating individual football players and labeling their position or roles, as well as identifying the formation of the offensive team. We obtain greater than 90% accuracy on both player detection and labeling, and 84.8% accuracy on formation identification. These results prove the feasibility of building a complete American football strategy analysis system using artificial intelligence. Collecting a larger dataset in real-world situations will enable further improvements. This would likewise enable American football teams to analyze game footage quickly.
Pore-Scale Investigation of Low-Salinity Nanofluids on Wetting Properties of Oil Carbonate Reservoir Rocks Studied by X-ray Micro-Tomography
Authors: Ivanova Anastasia , Kuandykova Azhar , Rodionov Alexander , Morkovkin Andrey , Burukhin Alexander , Cheremisin Alexey
Published: February 2023

Low-salinity surfactant nanofluids have recently shown promising results in the wettability alteration of reservoir rocks from oil-wet state towards more water-wet state. However, the investigation of pore-level interactions of nanofluids injection in real oil carbonate rocks at reservoir conditions, which determines the overall fluid dynamics, is lacking. Therefore, in this work, we studied the effect of nanoparticles augmented low-salinity surfactant flooding on the wettability alteration of hydrophobic carbonate rocks with harsh reservoir conditions via X-ray micro-tomography. The designed experiment scheme involved core flooding with an X-ray transparent core-holder developed for studying the flow properties of fluids at the micro level (pore scale). The wettability was quantified by measuring the differences in contact angles after the injection of low salinity, low-salinity surfactant, and low-salinity surfactant nanofluid. The findings illustrate that surfactant flooding with silica nanoparticles had a more pronounced influence on the contact angle among other injected fluids. The contact angle of the rock fell from 144° to 49°, corresponding to the water-wet conditions of carbonate rocks. The results show that the addition of a low concentration (0.005 wt.%) of SiO2 nanoparticles was enough for wettability changes in oil carbonate rocks. This study illustrates that a combination of surfactant, low-salinity, and nanoparticle features has a more pronounced effect on the three-phase contact angle than if applied separately.
Load Forecasting Models in Smart Grid Using Smart Meter Information: A Review
Authors: Dewangan Fanidhar , Abdelaziz Almoataz Y. , Biswal Monalisa
Published: February 2023

The smart grid concept is introduced to accelerate the operational efficiency and enhance the reliability and sustainability of power supply by operating in self-control mode to find and resolve the problems developed in time. In smart grid, the use of digital technology facilitates the grid with an enhanced data transportation facility using smart sensors known as smart meters. Using these smart meters, various operational functionalities of smart grid can be enhanced, such as generation scheduling, real-time pricing, load management, power quality enhancement, security analysis and enhancement of the system, fault prediction, frequency and voltage monitoring, load forecasting, etc. From the bulk data generated in a smart grid architecture, precise load can be predicted before time to support the energy market. This supports the grid operation to maintain the balance between demand and generation, thus preventing system imbalance and power outages. This study presents a detailed review on load forecasting category, calculation of performance indicators, the data analyzing process for load forecasting, load forecasting using conventional meter information, and the technology used to conduct the task and its challenges. Next, the importance of smart meter-based load forecasting is discussed along with the available approaches. Additionally, the merits of load forecasting conducted using a smart meter over a conventional meter are articulated in this paper.
Analysis of the Thermal Performance of Isothermal Composite Heat Accumulators Containing Organic Phase-Change Material
Authors: Musiał Michał , Lichołai Lech , Pękala Agnieszka
Published: February 2023

This paper presents the results of material tests, experimental tests and statistical analysis of the thermal performance of three types of heat accumulators containing an organic phase-change material and two materials of a higher thermal conductivity: a copper mesh and porous coke recyclate. The aim of the research was to empirically and statistically compare the increase in the PCM heat distribution through a copper conductor and coke recyclate. The research was conducted in accordance with an incomplete central compositional experimental design and using the Statistica software. The studies of the structure and chemical composition of the coke recyclate used and the empirical testing of the finished heat accumulators confirmed an improvement in the distribution and storage of heat by the accumulator with the phase-change material and coke recyclate compared to the pure phase-change material and copper-conductor accumulators, as the holding time of a temperature of 20 °C was extended by seven minutes and nine minutes, respectively. Moreover, the results of the statistical analysis provided answers as to which of the assumed input quantities—initial temperature, battery geometry, and heating temperature—were statistically significant for each of the three battery types considered. The determined approximating functions were verified in terms of the statistical validity of their use for all three types of heat accumulators tested. The results obtained are important answers to the current problems in the design and modification of phase-change heat accumulators applied in the construction industry to reduce the emissivity of structures and increase their energy efficiency.
Revisiting the Deep Geothermal Potential of the Cheshire Basin, UK
Authors: Brown Christopher Simon
Published: February 2023

Deep geothermal energy can aid in the decarbonization of heat within the UK; this is required to meet net zero carbon emissions targets by 2050. The Cheshire Basin represents a significant opportunity for the development of deep geothermal resources; there are vast quantities of high permeability sandstones in hydraulic continuity, with temperatures favorable for direct heat use and, potentially, for power generation. Newly produced basal temperature maps in this study indicate the likely maximum temperatures for the basin, with the hottest temperature expected to be between 100 and 131.2 °C in the Crewe area. There have also previously been a range of estimates highlighting a geothermal resource within the basin to be in the region of 44.1 to 75 × 1018 J; however, previous estimates for heat in place are limited to simple volumetric or geometrical constraints. Therefore, this paper uses digitized depth and temperature maps to provide new estimates for the heat in place. Results suggest the resource has been underestimated and there is a need for more detailed evaluation. Depending on the geothermal gradient, the resource could be between 91 and 144 × 1018 J (1.26 to 1.45 × 1017 J/km2). Although there is a significant amount of heat in place, geological issues preventing development remain, such as the uncertainty in the quality of the reservoir at depth due to data limitations and the lateral continuity of the Manchester Marls Formation, which could act as a barrier to flow. Nevertheless, further regional assessment of the basin and data acquisition is required to build confidence in the reservoir quality and reduce uncertainty. This could unlock the basin for geothermal development.
Steps towards Decarbonization of an Offshore Microgrid: Including Renewable, Enhancing Storage and Eliminating Need of Dump Load
Authors: Anglani Norma , Di Salvo Salvatore R. , Oriti Giovanna , Julian Alexander L.
Published: February 2023

A novel control strategy to manage the integration of a wind turbine (WT) and an energy storage unit to an existing stand-alone microgrid servicing an oil and gas (O&G) rig is the topic of this paper. The control strategy includes a primary and a secondary controller that, using the battery in tandem with the WT, does not require any dump load (A). The secondary controller includes an energy management system (EMS) which uses the estimated wind production and other specific local information to size the battery to avoid the curtailment of the WT (B) and simultaneously provide the framework for the economic analysis (C). Points A, B and C are the main novelties introduced with this work. Additionally, a primary controller operates the original microgrid source, a gas turbine (GT), at its maximum efficiency through an active power control strategy to lower fuel consumption, by prioritizing the exploitation of the renewable energy source through the combination EMS and battery sizing. The microgrid is simulated and the combined controller of the battery and GT bench-tested.
Parameter Estimation of a Grid-Tied Inverter Using In Situ Pseudo-Random Perturbation Sources
Authors: Gerber Ian Paul , Mwaniki Fredrick Mukundi , Vermeulen Hendrik Johannes
Published: February 2023

Inverters are playing an increasingly important role in the electrical utility grid due to the proliferation of renewable energy sources. Obtaining inverter models with accurate parameters is, therefore, essential for grid studies and design. In this paper, a methodology to estimate the output impedance and parameters of a residential grid-tied inverter is proposed. The methodology is first verified through simulation. A sensitivity analysis is conducted to determine the influence of the filter and controller parameters on the output impedance of the inverter. The simulated output impedance, voltage, and current are used in a parameter estimation methodology to obtain filter and controller parameters. It is shown that up to seven parameters can be estimated accurately. The proposed methodology is further investigated through a practical experiment. Two perturbation sources, the pseudo-random binary sequence perturbation and pseudo-random impulse sequence perturbation, are used, in turn, to perturb a residential grid-tied inverter that delivers up to 1.6 kW with the aim of obtaining its output impedance. The output impedances obtained through both pseudo-random sources are compared. It is shown that a pseudo-random binary sequence perturbation source applied in series between the grid and the inverter under test allows for the best estimation of the grid-tied inverter’s output impedance. A black-box modeling approach aimed at estimating an analytical transfer function of the output impedance from experimental data is also discussed.
Renewable Energy and Energy Storage Systems
Authors: Sayed Enas , Olabi Abdul , Alami Abdul , Radwan Ali , Mdallal Ayman , Rezk Ahmed , Abdelkareem Mohammad
Published: February 2023

The use of fossil fuels has contributed to climate change and global warming, which has led to a growing need for renewable and ecologically friendly alternatives to these. It is accepted that renewable energy sources are the ideal option to substitute fossil fuels in the near future. Significant progress has been made to produce renewable energy sources with acceptable prices at a commercial scale, such as solar, wind, and biomass energies. This success has been due to technological advances that can use renewable energy sources effectively at lower prices. More work is needed to maximize the capacity of renewable energy sources with a focus on their dispatchability, where the function of storage is considered crucial. Furthermore, hybrid renewable energy systems are needed with good energy management to balance the various renewable energy sources’ production/consumption/storage. This work covers the progress done in the main renewable energy sources at a commercial scale, including solar, wind, biomass, and hybrid renewable energy sources. Moreover, energy management between the various renewable energy sources and storage systems is discussed. Finally, this work discusses the recent progress in green hydrogen production and fuel cells that could pave the way for commercial usage of renewable energy in a wide range of applications.
Energy Context: Analysis of Selected Studies and Future Research Developments
Authors: Morea Donato , El Mehtedi Mohamad , Buonadonna Pasquale
Published: February 2023

Energy context has been the subject of a great deal of research from different perspectives, including, but not limited to: energy transition, renewable energy, nuclear power, energy saving, energy use, energy level, energy trade, energy security, traction energy, energy communities, energy poverty, Energy Performance Contracting (EPC), climate change, climate policy, and climate sustainability [...]
Technological and Intellectual Transition to Mining 4.0: A Review
Authors: Zhironkina Olga , Zhironkin Sergey
Published: February 2023

Ensuring a sustainable supply for humankind with mineral raw materials and preventing fuel and energy crises, minimizing human-made accidents and the negative impact of industry on the environment, the inflow of funds and innovations into the mining sector should be expanding in time and space. To do this, new mining platforms should have not only innovative and technological, but also social-and-economic coverage of the latest competencies, which Mining 4.0 fully corresponds to. The achievements of the Fourth Industrial Revolution, embodied in “end-to-end” digital and convergent technologies, are able to ensure the stable development of the mineral resource sector in the face of fluctuations in raw material demand and the profitability of mining enterprises, strengthening environmental safety legislation. Mining 4.0 is also a response to the technological shocks associated with the accelerated digital modernization of the manufacturing and infrastructure industries. This article attempts to give a multilateral overview of mining industries transformation in the course of the diffusion of Industry 4.0 technologies, to highlight the core and frontiers of Mining 4.0 expansion, to show the opportunities and threats of replacing physical systems and humans in mining with cyber-physical systems. Further, the technological, economic and social horizons of the transformation of Mining 4.0 into Mining 5.0 with specific threats of total digitalization are discussed.
Recent Trends, Opportunities and Challenges in Sustainable Management of Rice Straw Waste Biomass for Green Biorefinery
Authors: Rathour Ranju Kumari , Devi Mamta , Dahiya Pushpak , Sharma Nitish , Kaushik Neelam , Kumari Dolly , Kumar Pradeep , Baadhe Rama Raju , Walia Abhishek , Bhatt Arvind Kumar , Bhatia Ravi Kant
Published: February 2023

Waste rice straw biomass and its burning in open fields have become a serious issue of greenhouse gases emission and air pollution, which has a negative impact on public health and the environment. However, the environmental impact of burning this agro-waste can be mitigated by diverting it towards green biorefinery through the sustainable production of energy, biofuels, organic chemicals, and building blocks for various polymers. This will not only help to reduce the reliance on limited fuels and various chemicals derived from petroleum, but also help in the restoration of the environment in a sustainable manner through its complete utilization. To maximize the inherent conversion potential of rice straw biomass into valuable products, this agriculture waste biomass requires a comprehensive analysis and a techno-economic review for its sustainable management. This review article focuses on the sustainable management of rice straw waste biomass via innovative valorization approaches, as well as the opportunities and challenges encountered in this sector for meeting the demand of current and future green biorefineries.
Life Cycle Assessment of an Integrated PV-ACAES System
Authors: Cocco Daniele , Lecis Lorenzo , Micheletto Davide
Published: February 2023

The aim of this paper is to evaluate the overall life cycle environmental impact of an adiabatic compressed air energy storage (ACAES) system, which is designed to achieve the best match between the power production of a photovoltaic (PV) power plant and the power demand from the final user. The electrical energy demand of a small town, with a maximum power load of about 10 MW, is considered a case study. The ACAES system is designed with a compressor-rated power of about 10 MW and charging and discharging times of 10 and 24 h, respectively. Different sizes of the PV plant, ranging from 20 to 40 MWp, and two different solutions for the compressed air storage, an underground cavern, and a gas pipeline, are analyzed. The aim of this analysis is to compare the impacts on human health, ecosystem quality, climate change, and resource consumption of the PV power generation plant and the integrated PV-ACAES system with those of a reference scenario in which the end user demand is met entirely by the grid. The best results in terms of a reduction in environmental impact in comparison to the reference scenario are obtained for a small PV plant (20 MW) without the ACAES section, with reductions of about 85–95% depending on the category of impact. The integration of the ACAES system improves energy self-consumption but worsens the environmental impact, especially for air storage in gas pipelines. The best configuration in terms of environmental impact is based on a 30 MW PV plant integrated with an ACAES section using an underground cavern for air storage and allows for improvements in the energy self-consumption of between 38% and 61%, with a reduction in the environmental impact compared to the reference scenario of about 80–91% depending on the impact category.
Influence of Supercritical CO2 Fluid on CH4 and CO2 Diffusion in Vitrinite-Rich Coals and Inertinite-Rich Coals
Authors: Li Wei , Lin Weili , Liu Hongfu , Song Xiaoxia , Wei Zhenji
Published: February 2023

Coal maceral composition has a great effect on gas adsorption and diffusion. The interaction between maceral composition and supercritical CO2 (SCCO2) fluid will affect gas diffusion behavior in coals. Thus, the diffusivity derived from adsorption kinetics of CH4 and CO2 in vitrinite- and inertinite-rich coals with low-violate bituminous rank collected from the Hancheng mine of the Weibei coalfield pre- and post-SCCO2 fluid exposure (SFE) were tested at the conditions of 45 °C and 0.9 MPa. In combination with pore distribution and functional group content, the possible mechanism of the alterations in gas diffusion characteristics in coals with various maceral compositions was addressed. The results show that for vitrinite-rich coals, SFE increases the macropore apparent diffusion coefficient of CH4, while this treatment decreases the micropore apparent diffusion coefficient of CH4. However, the reverse trend is found for CO2 diffusion–adsorption rate. For inertinite-rich coals post-SFE, CH4 diffusion–adsorption rate increases, while an increase and a decrease in diffusivity CO2 occur for macropore and micropore, respectively. Generally, SFE shows a stronger impact on CO2 adsorption rate than CH4 in coals. The results suggest that the diffusion of CH4 and CO2 in coals with different maceral compositions show selectivity to SCCO2 fluid. The possible reason can be attributed to the changes in pore structure and surface functional group content. SFE causes an increase in macro/mesopore volume of all samples. However, SFE induces a reduction in oxygen-containing species content and micropore volume of inertinite-rich coals, while the opposite trend occurs in vitrinite-rich coals. Thus, the changes in pore volume and surface functional group account for the difference in gas diffusivity of coals with different maceral compositions. With regard to the micropore diffusion–adsorption behavior of CH4 and CO2, the impact of oxygen-containing species is superior to pore volume. The oxygen-containing species favor CO2 diffusion–adsorption but go against CH4 transport. This effect accounts for the reduction in the micropore diffusion–adsorption rate of CH4 and the increase in micropore diffusivity of CO2 in vitrinite-rich coals, respectively. However, the aforementioned effect is the opposite for inertinite-rich coals. Overall, the changes in gas diffusion in coals with different maceral composition during the CO2-ECBM process requires further attention.
Performance of a Heat-Pipe Cooled Concentrated Photovoltaic/Thermoelectric Hybrid System
Authors: Sabry Mohamed , Lashin Abdelrahman
Published: February 2023

Compared to traditional one-sun solar cells, multijunction concentrator cells operating under concentrated solar radiation are advantageous because of their high output and low cooling costs. Such a concentrator PV requires a cooling technique to maintain its performance and efficiency. The performance of a multi-junction concentrator photovoltaic cell of efficiency around 33%, operating under concentrated solar radiation (160–250 sun), has been tested. Heat pipes were used in this study as a fast and efficient way of rejecting heat accumulated in the cells. In this work, the evaporator side of the heat pipe was set in thermal contact with the back side of the solar cell such that the excess heat was transferred efficiently to the other side (condenser side). To positively utilize such excessive heat, two thermoelectric generators were thermally attached to either side of the condenser of the heat pipe, and each was attached to a fin-shaped heat sink. Four different cooling configurations were tested and compared. The net power obtained by this concentrator solar cell employing two types of TEG with different lengths as a cooling alongside two thermoelectric generators for heat-to-electricity conversion was 20% and 17%, corresponding to the long and short heat pipe configurations, respectively, compared to traditional a heat sink only configured at an optical concentration of 230 suns.
Fostering Macroeconomic Research on Hydrogen-Powered Aviation: A Systematic Literature Review on General Equilibrium Models
Authors: Mueller Tobias , Gronau Steven
Published: February 2023

Hydrogen is a promising fuel to decarbonize aviation, but macroeconomic studies are currently missing. Computable general equilibrium (CGE) models are suitable to conduct macroeconomic analyses and are frequently employed in hydrogen and aviation research. The main objective of this paper is to investigate existing CGE studies related to (a) hydrogen and (b) aviation to derive a macroeconomic research agenda for hydrogen-powered aviation. Therefore, the well-established method of systematic literature review is conducted. First, we provide an overview of 18 hydrogen-related and 27 aviation-related CGE studies and analyze the literature with respect to appropriate categories. Second, we highlight key insights and identify research gaps for both the hydrogen- and aviation-related CGE literature. Our findings comprise, inter alia, hydrogen’s current lack of cost competitiveness and the macroeconomic relevance of air transportation. Research gaps include, among others, a stronger focus on sustainable hydrogen and a more holistic perspective on the air transportation system. Third, we derive implications for macroeconomic research on hydrogen-powered aviation, including (I) the consideration of existing modeling approaches, (II) the utilization of interdisciplinary data and scenarios, (III) geographical suitability, (IV) the application of diverse policy tools and (V) a holistic perspective. Our work contributes a meaningful foundation for macroeconomic studies on hydrogen-powered aviation. Moreover, we recommend policymakers to address the macroeconomic perspectives of hydrogen use in air transportation.
Financial and Economic Stability of Energy Sector Enterprises as a Condition for Poland’s Energy Security—Legal and Economic Aspects
Authors: Zając Adam , Balina Rafał , Kowalski Dariusz
Published: February 2023

The energy security of each country is one of the main factors of its proper functioning. Currently, in the era of problems related to energy security resulting from, among other things, the war in Ukraine, this topic is particularly important. This article presents issues related to Poland’s energy security, understood as the financial and economic stability of enterprises operating in the energy industry. This stability is considered in two aspects: macroeconomic, where the focus is mainly on the aspect of state intervention in market processes; and microeconomic, where factors determining the financial security of energy enterprises were identified, including internal and external factors affecting the functioning of these entities. In order to achieve the assumed research goals, the analysis of the indicated problems was based on non-reactive research, consisting in the assessment of the available information. It included studies of normative acts, official statistical data, industry reports and analyses, as well as data obtained in the form of a public information request. Two basic research methods were used in the work—dogmatic–legal and comparative analyses. The identification of factors affecting the security of companies in the sector was carried out on the basis of data on the entire energy sector in Poland for the years 2015–2021 on a semi-annual basis. Vector-autoregressive models were used for the analysis. As a result of the analyses, it was established that market failures and public safety are the premises justifying the public financing of enterprises in the electricity generation, transmission, distribution and trade sectors. At the same time, the conducted research showed that the level of financial security of energy enterprises in Poland was affected by the ratio of the value of goods and materials sold to net sales revenue, as well as the level of EBIT (earnings before deducting interest and taxes) margin, and among external factors, the level of GDP (gross domestic product), CPI (consumer price index) and Crude Oil were important.
Microalgal Carbon Dioxide (CO2) Capture and Utilization from the European Union Perspective
Authors: Zieliński Marcin , Dębowski Marcin , Kazimierowicz Joanna , Świca Izabela
Published: February 2023

The increasing concentration of anthropogenic CO2 in the atmosphere is causing a global environmental crisis, forcing significant reductions in emissions. Among the existing CO2 capture technologies, microalgae-guided sequestration is seen as one of the more promising and sustainable solutions. The present review article compares CO2 emissions in the EU with other global economies, and outlines EU’s climate policy together with current and proposed EU climate regulations. Furthermore, it summarizes the current state of knowledge on controlled microalgal cultures, indicates the importance of CO2 phycoremediation methods, and assesses the importance of microalgae-based systems for long-term storage and utilization of CO2. It also outlines how far microalgae technologies within the EU have developed on the quantitative and technological levels, together with prospects for future development. The literature overview has shown that large-scale take-up of technological solutions for the production and use of microalgal biomass is hampered by economic, technological, and legal barriers. Unsuitable climate conditions are an additional impediment, forcing operators to implement technologies that maintain appropriate temperature and lighting conditions in photobioreactors, considerably driving up the associated investment and operational costs.
Optimal Installation of Heat Pumps in Large District Heating Networks
Authors: Capone Martina , Guelpa Elisa , Verda Vittorio
Published: February 2023

Power-to-heat technology represents a promising solution for the decarbonization of the energy sector. The installation of large-scale heat pumps within district heating systems is widely recognized to be a cost-effective and competitive way to provide flexibility to the electric system, enhancing the use of intermittent renewable energy sources. The goal of this paper is to show how the economic and environmental benefits provided by the installation of a large-scale heat pump in existing district heating systems vary according to the installation location in different scenarios. To do that, an integrated methodology is developed. This includes a physical model of the thermo-fluid dynamic of the district heating network and a detailed modeling of the heat pump. To compare the different positions and also the different operating conditions, an approach based on exergy analysis is adopted. Moreover, a specific control strategy of the mass-flow rate is analyzed to further reduce greenhouse gas emissions. The application to a real large-scale district heating network shows that reductions in CO2 emissions of almost 4% can be obtained by installing a single heat pump of about 4 MWe (over a total thermal load of about 305 MWt), while this positive effect can be reduced by up to 63% if placing the heat pump at non-optimal locations.
Numerical Study on the Heat Transfer Characteristics of Cu-Water and TiO2-Water Nanofluid in a Circular Horizontal Tube
Authors: Bose Jefferson Raja , Manova Stephen , Angeline Appadurai Anitha , Asirvatham Lazarus Godson , Gautam Sneha
Published: February 2023

A numerical simulation of convective heat transfer coefficient (hconv) was studied with Cu-Water and TiO2-Water nanofluids flowing through a circular tube subjected to uniform wall heat flux boundary conditions under laminar and turbulent regimes. Four different concentrations of nanofluids (ɸ = 0.5, 1, 1.5 and 2%) were used for the analysis and the Reynolds number (Re) was varied from laminar (500 to 2000) to turbulent flow regime (5000 to 20,000). The dependence of hconv on Re and ɸ was investigated using a single-phase Newtonian approach. In comparison to base fluid, average hconv enhancements of 10.4% and 7.3% were noted, respectively, for the maximum concentration (ɸ = 2%) and Re = 2000 for Cu-Water and TiO2—water nanofluids in the laminar regime. For the same ɸ under the turbulent regime (Re = 20,000), the enhancements were noted to be 14.6% and 13.2% for both the nanofluids, respectively. The random motion (Brownian motion) and heat diffusion (thermophoresis) by nanosized particles are the two major slip mechanisms that have more influence on the enhancement of hconv. In addition, the Nusselt number (Nu) of the present work was validated for water with the Shah and Dittus Boelter equation and found to have good agreement for both the regimes.
Synthesis of Graphite-Encapsulated Ni Micro- and Nanoparticles Using Liquid-Phase Arc Discharge
Authors: Ualkhanova Marzhan N. , Zhakypov Alibek S. , Nemkayeva Renata R. , Aitzhanov Madi B. , Kurbanov Beybars Y. , Akhanova Nazym Ye. , Yerlanuly Yerassyl , Orazbayev Sagi A. , Shchur Dmytro , Zolotarenko Anatolii , Gabdullin Maratbek T.
Published: February 2023

In this work, the synthesis of nickel particles encapsulated in a few-layer graphene shell was carried out using the method of electric arc discharge in the liquid phase, in various media: deionized water, alcohol, and toluene. Nickel and graphite were used as electrodes. The study was carried out to analyze how various liquids, acting as a cooling medium and a source of carbon, affect the formation of a protective shell around metal particles. Raman studies, analysis of X-ray diffraction data, and scanning electron microscopy confirmed the formation of spherical encapsulated nickel particles in all types of liquid media. It was found out that the use of toluene as a cooling medium increased the number of particles with a graphite shell and allowed obtaining micro- and nanoparticles covered with monolayer graphene. The absence of oxygen in the composition of toluene, in contrast with alcohol and especially water, prevents the oxidation of nickel particles during the synthesis. This fact, along with the initial basic hexagonal carbon structure of toluene, makes it a good medium for the formation of metal particles covered with a protecting graphite shell as a result of arc discharge in the liquid phase.
IEC 62443 Standard for Hydro Power Plants
Authors: Heluany Jessica B. , Galvão Ricardo
Published: February 2023

This study approaches cyber security in industrial environments focusing on hydro power plants, since they are part of the critical infrastructure and are the main source of renewable energy in some countries. The theoretical study case follows the standard IEC 62443-2-1 to implement a cyber security management system (CSMS) in a hydro power plant with two generation units. The CSMS is composed of six steps: (1) initiate CSMS, (2) high level risk assessment, (3) detailed risk assessment, (4) establish policies, procedures, and awareness, (5) select and implement countermeasures, and (6) maintain the CSMS. To perform the high-level risk assessment, an overview of the most common activities and vulnerabilities in hydro power plants systems is presented. After defining the priorities, the detailed risk assessment is performed based on a HAZOP risk analysis methodology focusing on hackable digital assets (cyber-HAZOP). The analysis of the cyber-HAZOP assessment leads to mitigations of the cyber risks that are addressed proposing modifications in the automation architecture, and this also involves checking lists to be used by the stakeholders during the implementation of the solution, emphasizing security configurations in digital assets groups.