bluuebunny/crossref_metadata_2025 huggingface dataset:
Subjective Reasons for COVID-19 Vaccine Hesitancy and Sociodemographic Predictors of Vaccination in Nigeria: An Online Survey
Authors: Chutiyami Muhammad , Bello Umar Muhammad , Salihu Dauda , Kolo Mustapha Adam , Alsharari Abdalkarem Fedgash , Sabo Hadiza , Bukar Mohammed , Shehu Usman , Adamu Haruna , Alkali Hafsat Ibrahim , Gambo Amina Abdullahi , Mahmud Fatima Ado , Muhammad Abdullahi Salisu , Bukar Ibrahim Ali
Published: September 2022

The purpose of this study was to examine the subjective reasons for hesitancy to receive COVID-19 vaccination and the sociodemographic factors associated with vaccination uptake. An online social media survey was conducted among the general Nigerian population using a self-developed questionnaire. Data were analyzed using binary logistic regression with crude and adjusted odds ratios (AOR) at a 95% confidence interval (CI) and a p value of less than 0.05. A total of 576 participants with a mean age of 31.86 years participated in the study. 28% (n = 158) received one or more doses of the COVID-19 vaccine. Teachers were significantly less likely than health professionals to be vaccinated (AOR = 0.33, 95% CI 0.16–0.69). In addition, unemployed people (AOR = 0.37, 95% CI 0.15–0.89) were less likely to be vaccinated than government employees, and those of intermediate socioeconomic status (AOR = 0.47 95% CI 0.26–0.88) were less likely to be vaccinated than were those of high socioeconomic status. Five main themes emerged regarding participants’ subjective reasons for hesitating to receive the COVID-19 vaccine: fear related to vaccine content (e.g., efficacy), negative effects on the body (e.g., blood clots), distrust of the system/government (e.g., politics), psychological concerns (e.g., anxiety), and misconceptions. Sociodemographic variables and vaccine misconceptions were found to play an important role in COVID-19 vaccination coverage in Nigeria.
Comparative Plastome Analyses of Ephedra przewalskii and E. monosperma (Ephedraceae)
Authors: Han Shuang , Xia Mingze , Yu Jingya , Xu Hao , Han Yun , Zhang Faqi
Published: September 2022

Ephedra species were erect, branching shrubs found in desert or arid regions worldwide as the source of ephedrine alkaloids. In this study, the complete chloroplast genome of Ephedra przewalskii and E. monosperma on the Qinghai-Tibet Plateau were sequenced, assembled, and annotated. Compared with the other four published Ephedra species, the chloroplast genomes of Ephedra species were highly conservative, with a quadripartite structure. The length of the chloroplast genome was 109,569 bp in E. przewalskii with 36.6% GC and 109,604 bp in E. monosperma with 36.6% GC. We detected 118 genes in both Ephedra species, including 73 PCGs, 37 tRNA genes, and eight rRNA genes. Among them, the ndh family genes were lost, which could be used to study the phylogeny and genetic diversity of the genus Ephedra, combined with multiple highly variable intergenic spacer (IGS) regions. Codon usage preference of Ephedra species was weak. The ratio of non-synonymous substitutions and synonymous substitutions was low, showing that the PCGs of Ephedra may be under the pressure of purifying selection. ML and BI analysis showed similar phylogenetic topologies. Ephedra species clustered together in a well-supported monophyletic clade. E. przewalskii and E. monosperma were not gathered in one clade, consistent with the classification system by Flora of China. This study reveals differences in the chloroplast genomes of Ephedra, providing valuable and abundant data for the phylogenetic analysis and species identification of Ephedra.
Understory Vegetation Dynamics in Non-Native Douglas Fir Forests after Management Abandonment—A Case Study in Two Strict Forest Reserves in Southwest Germany
Authors: Heinrichs Steffi , Dölle Michaela , Vor Torsten , Balcar Patricia , Schmidt Wolfgang
Published: September 2022

The non-native Douglas fir (Pseudotsuga menziesii) is widely distributed in Europe and promoted by forestry due to its assumed resistance against climate change. An increasing cultivation area is, however, viewed critically by nature conservation as negative effects on native biodiversity and naturalness are expected. We investigated plant species diversity and composition in two strict forest reserves (SFR) dominated by Douglas fir in southwest Germany. These reserves were established in the years 2001/2002 to study the development of Douglas fir forests after management abandonment. Vegetation surveys were conducted in 2005 and repeated in 2017. We used re-survey data from a nearby SFR dominated by native tree species as a reference. The understory vegetation showed consistent development after management abandonment, irrespective of tree species identity and origin. It became less diverse and more shade-tolerant over time due to missing soil disturbance and decreasing light availability. In contrast to a native canopy, though, Douglas fir promoted the share of generalist species. Regeneration of Douglas fir largely decreased in the SFRs underlining its competitive weakness against native tree species, mainly against European beech (Fagus sylvatica). Thereby, regeneration patterns of Douglas fir in the SFR were similar to those observed in the native range.
Antiparasitic Potential of Methanol Extract of Brown Alga Sargassum polycystum (Phaeophyceae) and Its LC-MS/MS Metabolite Profiling
Authors: Haron Fatin Khairah , Shah Muhammad Dawood , Yong Yoong Soon , Tan Jen Kit , Lal Mohammad Tamrin Mohamad , Venmathi Maran Balu Alagar
Published: September 2022

In Southeast Asian nations, cultured hybrid groupers are facing serious infestation by the marine parasitic leech Zeylanicobdella arugamensis (Annelida, Hirudinea). They attach to the hybrid groupers by sucking and biting on the surface of the skin, paving the way for secondary infection upon the fish. The objective of the study is to utilize the locally available seaweed to control the infestation of parasitic leeches. The methanol extracts of the brown alga Sargassum polycystum C. Agardh, 1824 (Phaeophyceae) from Sabah were prepared and investigated for antiparasitic efficacy against Z. arugamensis through in vitro bioassay. A total of 126 adult leeches from the host hybrid groupers were obtained from the fish hatchery. The parasitic leeches were treated with the methanol extracts of S. polycystum for 180 min by preparing five different dosages at concentrations of 100, 50, 25, 12.5, and 6.25 mg/mL. The brown alga was found to have high antiparasitic efficacy, resulting in 100% leech mortality over a short period of time. It showed the highest antiparasitic efficacy (total mortality of leeches) in a short time limit of 0.96 ± 0.44 min, for 100 mg/mL of the extract. Observations on leech behavior in the positive control and the seaweed extract treatments showed vigorous swimming before mortality. LC-MS/MS analysis was used to reveal the phytochemical composition of the extract to understand the nature of the main components responsible for its antiparasitic activities. A total of 29 metabolites were identified via Q Exactive HF Orbitrap mass spectrometry, including two flavonoids (ephedrannin A and hinokiflavone), two organoarsenics (1-dimethylarsinoyl-heptadecane and cacodylic acid), four heterocyclic compounds, and two chlorophyll breakdown products. The presence of bioactive compounds could increase the mortality rate of parasitic leeches. Thus, this study concludes that the brown alga showed high efficacy in its antiparasitic activities and can be effectively applied for treatment in grouper aquaculture farms for sustainable aquaculture.
Current Status of and Threats to Sicilian Turtles
Authors: Vecchioni Luca , Arculeo Marco , Vamberger Melita , Marrone Federico
Published: September 2022

Based on the critical review of the literature published in the last 22 years, an attempt was made to evaluate the current knowledge gap on the distribution and status of the native Testudines taxa occurring in Sicily (namely Caretta caretta, Emys trinacris, and Testudo hermanni hermanni), as well as the available knowledge of the only non-native species with putative viable populations occurring on the island, i.e., Trachemys scripta. Summarizing the current information, all of the Testudines species occurring in Sicily showed a fragmented and incompletely-known distribution, and only scarce data are available about their phenology. Moreover, despite their inclusion of international and national laws (Bern Convention, CITES, Habitat directive), all three native species are facing several threats (e.g., habitat alteration, the occurrence of invasive species, parasite spillover) leading to a reduction of their populations on the island. Future monitoring programs on the island should be enhanced, with an emphasis on those taxa in decline. Moreover, involve Citizen Science programs should also be implemented in order to increase the awareness of non-experts and facilitate the monitoring task.
A Comparison of Functional and Oncologic Outcomes between Partial Nephrectomy and Radiofrequency Ablation in Patients with Chronic Kidney Disease after Propensity Score Matching
Authors: Ryoo Hyunsoo , Kang Minyong , Sung Hyun Hwan , Jeon Hwang Gyun , Jeong Byong Chang , Jeon Seong Soo , Lee Hyun Moo , Park Byung Kwan , Seo Seong Il
Published: September 2022

Purpose: This study aimed to compare functional and oncological outcomes between partial nephrectomy (PN) and radiofrequency ablation (RFA) for a small renal mass (SRM, ≤4 cm) in patients with chronic kidney disease (CKD). Materials and Methods: Patients with CKD who underwent either PN or RFA for SRM between 2005 and 2019 were included. Patients were stratified into two categories: CKD stage 2 and CKD stage 3 or higher. We performed propensity score matching (PSM) analysis in patients with CKD stage 2 and CKD stage 3 or higher. We compared the functional and oncological outcomes between two groups according to CKD stage before and after PSM. Results: Among 1332 patients, 1195 patients were CKD stage 2 and 137 patients were CKD stage 3 or higher. After PSM analysis using age, pre-treatment eGFR, and clinical tumor size as matching variables, the PN and RFA groups had 270 and 135 CKD stage 2 patients, respectively, and both had 53 patients each with CKD stage 3 or higher. There were no significant differences in percent change in eGFR at 1 year post-operation between groups in patients with CKD stage 2 and stage 3 or higher. Among all patients with tissue-proven malignancy, the 5-year recurrence-free survival (RFS), cancer-specific survival, and overall survival were significantly higher in the PN group. However, only the 5-year RFS was significantly higher in the PN group after matching. Conclusion: Mortality is low in patients with SRM, and functional outcomes were not significantly different between the two treatments. RFA could be an alternative treatment modality in patients who are poor candidates for surgery.
Search and Rescue in a Maze-like Environment with Ant and Dijkstra Algorithms
Authors: Husain Zainab , Al Zaabi Amna , Hildmann Hanno , Saffre Fabrice , Ruta Dymitr , Isakovic A. F.
Published: September 2022

With the growing reliability of modern ad hoc networks, it is encouraging to analyze the potential involvement of autonomous ad hoc agents in critical situations where human involvement could be perilous. One such critical scenario is the Search and Rescue effort in the event of a disaster, in which timely discovery and help deployment is of utmost importance. This paper demonstrates the applicability of a bio-inspired technique, namely Ant Algorithms (AA), in optimizing the search time for a route or path to a trapped victim, followed by the application of Dijkstra’s algorithm in the rescue phase. The inherent exploratory nature of AA is put to use for faster mapping and coverage of the unknown search space. Four different AA are implemented, with different effects of the pheromone in play. An inverted AA, with repulsive pheromones, was found to be the best fit for this particular application. After considerable exploration, upon discovery of the victim, the autonomous agents further facilitate the rescue process by forming a relay network, using the already deployed resources. Hence, the paper discusses a detailed decision-making model of the swarm, segmented into two primary phases that are responsible for the search and rescue, respectively. Different aspects of the performance of the agent swarm are analyzed as a function of the spatial dimensions, the complexity of the search space, the deployed search group size, and the signal permeability of the obstacles in the area.
On Quantum Entropy
Authors: Geiger Davi , Kedem Zvi M.
Published: September 2022

Quantum physics, despite its intrinsically probabilistic nature, lacks a definition of entropy fully accounting for the randomness of a quantum state. For example, von Neumann entropy quantifies only the incomplete specification of a quantum state and does not quantify the probabilistic distribution of its observables; it trivially vanishes for pure quantum states. We propose a quantum entropy that quantifies the randomness of a pure quantum state via a conjugate pair of observables/operators forming the quantum phase space. The entropy is dimensionless, it is a relativistic scalar, it is invariant under canonical transformations and under CPT transformations, and its minimum has been established by the entropic uncertainty principle. We expand the entropy to also include mixed states. We show that the entropy is monotonically increasing during a time evolution of coherent states under a Dirac Hamiltonian. However, in a mathematical scenario, when two fermions come closer to each other, each evolving as a coherent state, the total system’s entropy oscillates due to the increasing spatial entanglement. We hypothesize an entropy law governing physical systems whereby the entropy of a closed system never decreases, implying a time arrow for particle physics. We then explore the possibility that as the oscillations of the entropy must by the law be barred in quantum physics, potential entropy oscillations trigger annihilation and creation of particles.
On the Genuine Relevance of the Data-Driven Signal Decomposition-Based Multiscale Permutation Entropy
Authors: Jabloun Meryem , Ravier Philippe , Buttelli Olivier
Published: September 2022

Ordinal pattern-based approaches have great potential to capture intrinsic structures of dynamical systems, and therefore, they continue to be developed in various research fields. Among these, the permutation entropy (PE), defined as the Shannon entropy of ordinal probabilities, is an attractive time series complexity measure. Several multiscale variants (MPE) have been proposed in order to bring out hidden structures at different time scales. Multiscaling is achieved by combining linear or nonlinear preprocessing with PE calculation. However, the impact of such a preprocessing on the PE values is not fully characterized. In a previous study, we have theoretically decoupled the contribution of specific signal models to the PE values from that induced by the inner correlations of linear preprocessing filters. A variety of linear filters such as the autoregressive moving average (ARMA), Butterworth, and Chebyshev were tested. The current work is an extension to nonlinear preprocessing and especially to data-driven signal decomposition-based MPE. The empirical mode decomposition, variational mode decomposition, singular spectrum analysis-based decomposition and empirical wavelet transform are considered. We identify possible pitfalls in the interpretation of PE values induced by these nonlinear preprocessing, and hence, we contribute to improving the PE interpretation. The simulated dataset of representative processes such as white Gaussian noise, fractional Gaussian processes, ARMA models and synthetic sEMG signals as well as real-life sEMG signals are tested.
Estimation of Radial Basis Function Network Centers via Information Forces
Authors: Sousa Júnior Edilson , Freitas Antônio , Rabelo Ricardo , Santos Welflen
Published: September 2022

The determination of The Radial Basis Function Network centers is an open problem. This work determines the cluster centers by a proposed gradient algorithm, using the information forces acting on each data point. These centers are applied to a Radial Basis Function Network for data classification. A threshold is established based on Information Potential to classify the outliers. The proposed algorithms are analysed based on databases considering the number of clusters, overlap of clusters, noise, and unbalance of cluster sizes. Combined, the threshold, and the centers determined by information forces, show good results in comparison to a similar Network with a k-means clustering algorithm.
Feedback Loops in Opinion Dynamics of Agent-Based Models with Multiplicative Noise
Authors: Djurdjevac Conrad Nataša , Köppl Jonas , Djurdjevac Ana
Published: September 2022

We introduce an agent-based model for co-evolving opinions and social dynamics, under the influence of multiplicative noise. In this model, every agent is characterized by a position in a social space and a continuous opinion state variable. Agents’ movements are governed by the positions and opinions of other agents and similarly, the opinion dynamics are influenced by agents’ spatial proximity and their opinion similarity. Using numerical simulations and formal analyses, we study this feedback loop between opinion dynamics and the mobility of agents in a social space. We investigate the behaviour of this ABM in different regimes and explore the influence of various factors on the appearance of emerging phenomena such as group formation and opinion consensus. We study the empirical distribution, and, in the limit of infinite number of agents, we derive a corresponding reduced model given by a partial differential equation (PDE). Finally, using numerical examples, we show that a resulting PDE model is a good approximation of the original ABM.
Robustness Evaluation of the Open Source Product Community Network Considering Different Influential Nodes
Authors: Zhou Hongli , You Siqing , Yang Mingxuan
Published: September 2022

With the rapid development of Internet technology, the innovative value and importance of the open source product community (OSPC) is becoming increasingly significant. Ensuring high robustness is essential to the stable development of OSPC with open characteristics. In robustness analysis, degree and betweenness are traditionally used to evaluate the importance of nodes. However, these two indexes are disabled to comprehensively evaluate the influential nodes in the community network. Furthermore, influential users have many followers. The effect of irrational following behavior on network robustness is also worth investigating. To solve these problems, we built a typical OSPC network using a complex network modeling method, analyzed its structural characteristics and proposed an improved method to identify influential nodes by integrating the network topology characteristics indexes. We then proposed a model containing a variety of relevant node loss strategies to simulate the changes in robustness of the OSPC network. The results showed that the proposed method can better distinguish the influential nodes in the network. Furthermore, the network’s robustness will be greatly damaged under the node loss strategies considering the influential node loss (i.e., structural hole node loss and opinion leader node loss), and the following effect can greatly change the network robustness. The results verified the feasibility and effectiveness of the proposed robustness analysis model and indexes.
Fusion of Infrared and Visible Images Based on Three-Scale Decomposition and ResNet Feature Transfer
Authors: Ji Jingyu , Zhang Yuhua , Hu Yongjiang , Li Yongke , Wang Changlong , Lin Zhilong , Huang Fuyu , Yao Jiangyi
Published: September 2022

Image fusion technology can process multiple single image data into more reliable and comprehensive data, which play a key role in accurate target recognition and subsequent image processing. In view of the incomplete image decomposition, redundant extraction of infrared image energy information and incomplete feature extraction of visible images by existing algorithms, a fusion algorithm for infrared and visible image based on three-scale decomposition and ResNet feature transfer is proposed. Compared with the existing image decomposition methods, the three-scale decomposition method is used to finely layer the source image through two decompositions. Then, an optimized WLS method is designed to fuse the energy layer, which fully considers the infrared energy information and visible detail information. In addition, a ResNet-feature transfer method is designed for detail layer fusion, which can extract detailed information such as deeper contour structures. Finally, the structural layers are fused by weighted average strategy. Experimental results show that the proposed algorithm performs well in both visual effects and quantitative evaluation results compared with the five methods.
The Impact of Soybean Futures and Crude Oil Futures on Palm Oil Indexes: Evidence from Bounds Test of Level Relationship and Causality Analysis
Authors: Jamil Izaan , Kogid Mori , Lim Thien Sang , Lily Jaratin
Published: September 2022

This paper investigates the impact of soybean and crude oil futures on palm oil indexes by utilising monthly data from three palm oil indexes listed in Bursa Malaysia, i.e., the Asian palm index, Malaysian palm index, and Plantation index, spanning from January 2010 to June 2020. The impacts were analysed using the Autoregressive Distributed Lag (ARDL) bounds test approach and causality test. The statistical findings revealed that the Asian palm index has a long-run relationship with crude oil futures and crude palm oil, and a short-run relationship with soybean futures, crude oil futures, and crude palm oil. On the other hand, the Malaysian palm index has a short-run relationship with soybean futures and crude palm oil, whereas the Plantation index has a short-run relationship with crude oil futures, crude palm oil, and exchange rate. For the long-run strategy, this study recommends close monitoring of crude oil futures. Meanwhile, the short-run strategy requires close monitoring of the crude oil and soybean futures. Eventually, the empirical findings proposed that interested parties such as fund managers, investors, and traders should pay attention to crude oil and soybean futures to mitigate risk and diversify their portfolios with greater emphasis on crude oil futures.
Lab-on-a-Chip Electrochemical Immunosensor Array Integrated with Microfluidics: Development and Characterisation
Authors: Felemban Shifa , Vazquez Patricia , Balbaied Thanih , Moore Eric
Published: September 2022

Lab-on-a-chip has recently become an alternative for in situ monitoring for its portability and simple integration with an electrochemical immunoassay. Here, we present an electrochemical cell-on-a-chip configured in a three-electrode system to detect benzo(a)pyrene (BaP) in water. 11-Mercaptoundecanoic acid (MUA), a self-assembled monolayer (SAM), was used to modify a gold chip surface to reduce the randomness of antibody binding. A carboxylic acid group was activated with -ethyl-3-(3-dimethylaminopropyl) (EDC) in combination with N-hyrodsuccinimide (NHS) before antibody immobilisation. The mechanism of the electrochemical reactions on a gold surface and SAM formation were investigated by cyclic voltammetry and contact angle measurements. The data revealed a lower contact angle in the modified chip and a scan rate of 50 mV/s. Through the addition of modification layers and thiol end groups to the SAM, our design allowed the chip surface to became more insulated. All were tested by amperometric detection using the developed Q-sense system. This novel technique detected multiple samples, and completed the analysis reasonably quickly. While the integrated system proved successful in a lab setting, the aim of the research is to use this system for in situ analysis, which can be brought into a water environment to carry out tests with existing processes. In this way, any issues that may arise from an environmental setting can be rectified in an efficient manner.
On Unstable Spatial Modes and Patterns in Cellular and Graph Neural Circuits
Authors: Goras Liviu
Published: September 2022

The aim of this paper is to discuss several aspects regarding the dynamics and pattern formation in select cellular and graph neural circuit type architectures and to propose a new application. A unifying approach for these types of neural circuits based on unstable spatial modes using the mode decoupling technique is presented. The main objective of this study is that of showing the way the dynamics can be prescribed by speculating the relationship between the extended graph Laplacian and nodal equations of a specific architecture. Based on the above, the possibility of designing a so-called spatial comparator that can extract the sign of a prescribed spatial mode contained in a spatial signal, using unstable circuits for which that mode is associated with a right half-plane eigenvalue, is analyzed and illustrated with simulations in CMOS technology.
The Status Quo and Future of Hydropower in Slovenia
Authors: Hočevar Marko , Novak Lovrenc , Drešar Primož , Rak Gašper
Published: September 2022

Slovenia is a Central European country with a long history of hydropower. This paper gives a brief introduction to the current status of hydropower utilization and informs about some selected successful examples of hydropower plant operation. One such example is fish passage and flood risk reduction on the lower reaches of the Sava River at the Brežice hydroelectric power plant, taking into account a complex of morphological, hydrological, hydraulic, and anthropogenic factors. Future development is considered against the background of the National Energy and Climate Plan, which does not envisage any significant expansion in the capacity or function of the hydropower sector. The envisaged capacity increase is from the current 4430 GWh to around 4580 GWh by 2030. It is shown that the current energy storage capacity of Slovenia’s only pumped storage plant will be sufficient to offset the introduction of new non-dispatchable renewable energy sources by 2030. By around 2028, the country will have a need for electrical energy storage from renewable energy sources, reaching a modest total of only 6140 MWh per year. However, by sticking to the unambitious National Energy and Climate Plan, Slovenia will miss the opportunity to remain self-sufficient in electricity generation and significantly increase its share of renewable energy sources. The National Energy and Climate Plan aims to increase the share of renewable energy in total energy generation from 25% in 2020 to 27% by 2030.
Liquid–Gas Jet Pump: A Review
Authors: Zhang Huiyan , Zou Daohang , Yang Xuelong , Mou Jiegang , Zhou Qiwei , Xu Maosen
Published: September 2022

To promote the development and application of the liquid–gas jet pump (LGJP), the research status of its design theory, internal flow mechanism, structural optimization and practical application are reviewed. The development history of the LGJP is briefly reviewed, the latest research and application progress of the LGJP is introduced, and the pulse-type of LGJP, especially the centrifugal jet vacuum pump (CJVP), is emphatically discussed. The research and development direction of the LGJP is analyzed and proposed: CFD will be more deeply applied to the mechanism research and performance improvement of the LGJP; the diversity and heterogeneity of the fluid medium and its influence on the internal flow mechanism are the research highlights of the LGJP; it is urgent to study the gas–liquid two-phase flow and pumping mechanism inside the pulsed liquid–gas jet pump (PLGJP), especially the CJVP.
Investigation of Herbicide Decomposition Efficiency by Means of Detonative Combustion
Authors: Biegańska Jolanta , Barański Krzysztof
Published: September 2022

The decomposition of seven herbicides (atrazine, linuron, lenacil, chloridazon, dinoseb acetate, prometryn, and diuron) was carried out by detonative combustion. The investigated blasting material was produced on the basis of porous ammonium nitrate, which served as an oxidizer, while the pesticides played the role of the fuel. Detonative decomposition of the mixtures was carried out in blast-holes in soil. The efficiency of the decomposition process was assessed using the techniques of gas chromatography, high-efficiency liquid chromatography, and additionally by biological tests according to the grading of the European Weed Research Council. The results demonstrate an efficient decomposition of the tested herbicides. In the tested soil samples taken after the detonation decomposition of the herbicide, no symptoms of phytotoxic effects on the plants were found. This was confirmed by the lack (or at most negligible amounts) of residual herbicides in the soil samples. Only for the samples of chloradizine and diuron were large amounts of residual biologically active substance found.
Research on Renewable-Energy Accommodation-Capability Evaluation Based on Time-Series Production Simulations
Authors: Zhou Dan , Zhang Qi , Dan Yangqing , Guo Fanghong , Qi Jun , Teng Chenyuan , Zhou Wenwei , Zhu Haonan
Published: September 2022

In recent years, renewable energy has received extensive attention due to its advantages of sustainability, economy, and environmental protection. However, with the rapid development of renewable energy, the problem of curtailment is becoming increasingly serious. Studying the calculation method and establishing a quantitative evaluation system of renewable energy accommodation capacity are important means to solve this problem. This paper comprehensively considers the factors affecting the accommodation of renewable energy, establishes a accommodation calculation model with the maximum accommodation of renewable energy as the optimization target based on the time series production simulation method, and uses the hybrid particle swarm optimization (PSO) algorithm to solve it. The model is verified with historical data such as load, photovoltaic (PV), and wind power in a certain region throughout the year. The experimental results verify the rationality of the renewable-energy accommodation-capacity model proposed in this paper and the correctness of the theoretical analysis. The calculation results have important reference and guiding significance for the operation and control of power-grid planning and dispatching.
Integration Opportunities of Power-to-Gas and Internet-of-Things Technical Advancements: A Systematic Literature Review
Authors: Magyari József , Hegedüs Krisztina , Sinóros-Szabó Botond
Published: September 2022

As renewable electricity integration generates grid-balancing challenges for network operators, new ways of grid resilience receive significant attention from the energy research community. Power-to-gas (P2G) applications could produce and use green hydrogen. Thus, they enable the integration of more renewable energy into the energy system. Meanwhile, Internet-of-things (IoT) solutions could optimize renewable energy applications in decentralized systems. Despite the strategic importance of both technologies in renewable-rich grid developments, opportunities for P2G advancements based on IoT and related solutions have not come to the forefront of renewable energy research. To fill in this research gap, this study presents a hybrid (thematic and critical) systematic literature review to explore how strategic co-specialization opportunities appear in recent publications. Findings suggest that P2G and IoT could be fundamentally linked within the proposed frameworks of multi-energy systems and energy internet, but further empirical research is needed regarding their operative and strategic integration (e.g., cost reduction, risk management and policy incentives).
Numerical Studies on the Flow of Coal Water Slurries with a Yield Stress in Channel Bends
Authors: Liu Yang , Yao Qige , Gao Feng , Gao Yanan
Published: September 2022

Improving the efficiency of transport of coal water slurries (CWSs) and determining pipe wear both necessitate accurate predictions of flow characteristics in pipelines with complex geometries. At the bends of the channels, the flow is significantly influenced by the bend curvature, flow rate, and the rheological properties of the slurries that are viscoplastic. Herein, we numerically simulated the flow of CWS in curved channels with different curvature ratios, at different flow rates, and using different rheological models, respectively. The results showed that, due to the yield stress on the cross-stream slices, the velocity profiles showed an unyielded plug. The plug deflects outwards in most circumstances, except at the bend core in the highly curved channel, and, at the same time, at the lower conveying rate, which is due to the fact that the larger inner-wall-pointed pressure gradient has to be balanced by large velocities at the inner bend and, hence, the centrifugal effects are weakened at the lower conveying rate. Interestingly, the larger curvature, together with a higher conveying rate, induces a kidney-shaped velocity field at the bend exit, with two separated up and down velocity maximum zones, due to the larger wall shear stresses at the top and bottom than occur in the other cases. The bend brings in a secondary flow consisting of the following: an inward transverse flow at the bend entrance; two Dean swirls in symmetry in the vertical direction at the slices of the bend core and bend exit; and decayed swirls near the outlet. As the curvature ratio increases, the location of the strongest swirls switches from the bend core to the bend exit, since the flow in the highly curved channel requires a longer distance to fully develop the vortices. Decrease in the yield stress and decrease in the consistency index induce a shrinkage of the plug and enhance the streamwise flow and, thus, decrease the cross-stream secondary flow, especially in the channel with the larger curvature.
Hybrid Fault-Tolerant Control for Air-Fuel Ratio Control System of Internal Combustion Engine Using Fuzzy Logic and Super-Twisting Sliding Mode Control Techniques
Authors: Alsuwian Turki , Riaz Umar , Amin Arslan Ahmed , Qadir Muhammad Bilal , Almasabi Saleh , Jalalah Mohammed
Published: September 2022

Safety and critical applications employ fault-tolerant control systems (FTCS) to increase reliability and availability in the event of a failure of critical components. Process facilities may employ these technologies to cut down on production losses caused by equipment failures that occur on an irregular or unscheduled basis. Air–fuel ratio (AFR) adjustment in the fuel system of internal combustion engines (ICE) is crucial for enhancing engine efficiency, saving fuel energy, and safeguarding the environment. This paper proposes a novel hybrid fault-tolerant control system (HFTCS) for controlling the AFR in ICEs that combines the features of both an active fault-tolerant control system (AFTCS) and a passive fault-tolerant control system (PFTCS). The fault detection and isolation (FDI) unit is designed using fuzzy logic (FL) as part of an AFTCS to give estimated sensor values to the engine controller when the sensor becomes faulty. Super-twisting sliding mode control (ST-SMC) is implemented as part of a PFTCS to maintain AFR by adjusting the throttle actuator in the fuel supply line under faulty conditions. Lyapunov stability analysis is also performed to make sure that the system remains stable in both normal and faulty conditions. According to the results in the Matlab/Simulink environment, the suggested system stays robust and stable during sensor faults. In faulty situations, it also maintains the AFR at 14.6 without any degradation, and a comparison with previous studies is carried out. The study shows that the suggested approach is an innovative and highly dependable solution for AFR control in ICEs, preventing engine shutdown and output loss for higher profitability.
An Approach for Determining Voltage Imbalance Contributions Based on Complex Independent Component Analysis
Authors: Moraes Márcio Arvelos , Brito Vinícius Henrique Farias , de Oliveira José Carlos
Published: September 2022

In the context of power quality problems, the voltage imbalance index is relevant, given its harmful impacts on the networks and loads. Thus, reliable and viable methodologies for practical use are necessary to determine agents’ contributions. This article presents a noninvasive method for sharing responsibility for imbalances based on the principle of superposing the individual voltage imbalance produced by the parties. A procedure based on the Complex Independent Component Analysis (CICA) technique is proposed to meet the parameters required by the superposition method. Based on the measurements of voltages and currents carried out on the point of common coupling (PCC), the negative sequence impedances are determined using the CICA method under the terms needed by the superposition principle. The methodology’s effectiveness is evaluated through performance comparisons carried out over the process, in light of the response from the methods for sharing responsibilities currently published in the literature of this domain. The results obtained through the proposed approach show good adherence to the procedures presented with solid conceptual bases. However, unlike these, this article’s methodology offers practical perspectives for application in the field.
Controlling Factors and Forming Types of Deep Shale Gas Enrichment in Sichuan Basin, China
Authors: Shi Xuewen , Wu Wei , Wu Qiuzi , Zhong Kesu , Jiang Zhenxue , Miao Huan
Published: September 2022

In order to find out the enrichment mechanism and forming type of deep shale gas, taking the Longmaxi Formation shale in the Desheng–Yunjin Syncline area of Sichuan Basin as an example, we determined the mineralogy, organic geochemistry, physical property analysis, gas and water content, and the influence of three factors, namely sedimentation, structural conditions, and hydrogeological conditions, on the enrichment of shale gas. The results show that Longmaxi Formation shale in Desheng–Yunjin Syncline area is a good hydrocarbon source rock that is in the over-mature stage and has the characteristics of high porosity, low permeability, and high-water saturation. The contents of clay and quartz are high, and the brittleness index is quite different. According to the mineral composition, nine types of lithofacies can be found. The development characteristics of Longmaxi Formation shale and the sealing property of the roof have no obvious influence on the enrichment of shale gas, but the tectonic activities and hydrodynamic conditions have obvious influence on the enrichment of shale gas. The main control factors for shale gas enrichment in different regions are different. According to the main control factors, the gas accumulation in the study area can be divided into three types: fault-controlled gas, anticline-controlled gas, and hydrodynamic-controlled gas. The fault-controlled gas type is distributed in the north of the Desheng syncline and the north of the Yunjin syncline, the anticline-controlled gas type is distributed in the south of the Desheng syncline and the south of the Yunjin syncline, and the hydrodynamic-controlled gas type is distributed in the middle of the Baozang syncline. This result is of great significance for deep shale gas exploration.
Optimal Power Management of Interconnected Microgrids Using Virtual Inertia Control Technique
Authors: Elshenawy Mahmoud , Fahmy Ashraf , Elsamahy Adel , Kandil Shaimaa A. , El Zoghby Helmy M.
Published: September 2022

Two interconnected AC microgrids are proposed based on three renewable energy sources (RESs): wind, solar, and biogas. The wind turbine drives a permanent magnet synchronous generator (PMSG). A solar photovoltaic system (SPVS) with an appropriate inverter was incorporated. The biogas genset (BG) consists of a biogas engine coupled with a synchronous generator. Two interconnected AC microgrids, M1 and M2, were considered for study in this work. The microgrid M2 is connected to a diesel engine (DE) characterized by a continuous power supply. The distribution power loss of the interconnected AC microgrids comprises in line loss. The M1 and M2 losses are modeled as an objective function (OF). The power quality enhancement of the interconnected microgrids will be achieved by minimizing this OF. This research also created a unique frequency control method called virtual inertia control (VIC), which stabilizes the microgrid frequency using an optimal controller. In this paper, the following five controllers are studied: a proportional integral controller (PI), a fractional order PI controller (FOPI), a fuzzy PI controller (FPI), a fuzzy fractional order PI controller (FFOPI), and a VIC based on FFOPI controller. The five controllers were tuned using particle swarm optimization (PSO) to minimize the (OF). The main contribution of this paper is the comprehensive study of the performance of interconnected AC microgrids under step load disturbances, step changes in wind/solar input power, and eventually grid following/forming contingencies as well as the virtual inertia control of renewable energy resources used in the structure of the microgrids.
Review of Smart Grid and Nascent Energy Policies: Pakistan as a Case Study
Authors: Abbas Syed , Ali Zulfiqar , Mahmood Anzar , Haider Syed , Kousar Anila , Razzaq Sohail , Hassan Tehzeeb , Su Chun-Lien
Published: September 2022

Smart grid plays a vital role in energy management systems. It helps to mitigate the demand side management of electricity by managing the microgrid. In the modern era, the concept of hybrid microgrids emerged which helps the smart grid management of electricity. Additionally, the Internet of Things (IoT) technology is used to integrate the hybrid microgrid. Thus, various policies and topologies are employed to perform the task meticulously. Pakistan being an energy deficient country has recently introduced some new policies such as Energy Wheeling Policy (EWP), Energy Import Policy (EIP), and Net Metering/Distributed Generation Policy (NMP) to manage the electricity demand effectively. In addition, the Energy Efficiency and Conservation Act (EECA) has also been introduced. In this paper, we present the overview and impact of these policies in the context of the local energy market and modern information and communication mechanisms proposed for smart grids. These new policies primarily focus on energy demand–supply for various types of consumers such as the demand for bulk energy for industrial ventures and the distributed production by consumers. The EWP deals with obtaining power from remote areas within the country to ease the energy situation in populated load centers and the EIP highlights energy import guidelines from foreign countries. The NMP deals with the integration of renewable energy resources and EECA is more focused on the measures and standardization for energy efficiency and conservation. The benefits and challenges related to EWP, NMP, and EIP have also been discussed concerning the present energy crisis in Pakistan. The generalized lessons learned and comparison of a few aspects of these policies with some other countries are also presented.
Application of a Fractional Transfer Function for Simulating the Eddy Currents Effect in Electrical Systems
Authors: Moroz Volodymyr , Makarchuk Oleksandr
Published: September 2022

Some electrical devices contain a solid nonlaminated magnetic core as a component. In the case of variable magnetic flux, eddy currents arise in such a core, which should be taken into account for computer simulation if higher precision is needed. The fractional order transfer function (FOTF) based on the simple traditional model of excitation circuit of a DC machine is proposed for eddy current simulation. This model is illustrated by mathematical (based on differential equations and the Laplace operator) and structural approaches to the excitation circuit of a common DC generator with a solid core. The skin effect for more precise simulation of eddy currents is also considered by means of fractional order transfer functions in the computer models. Magnetic saturation and hysteresis were not taken into account in this case. The proposed model is simple and ensures adequate accuracy, confirmed experimentally using the FOTF Toolbox for MATLAB and Simulink. This model is distinct and proposed for the fast and accurate computer simulation of eddy currents in electrical devices with a solid magnetic core.
Iranian Household Electricity Use Compared to Selected Countries
Authors: Fatourehchi Dorsa , Noguchi Masa , Doloi Hemanta
Published: September 2022

Buildings account for nearly 40% of energy use in global contexts and climatic conditions tend to contribute to consumption. Human activities are also influential in energy consumption and carbon dioxide (CO2) emissions that lead to global warming. Residential buildings are responsible for a considerable share. There are countries aggravating this situation by heavily relying on fossil fuels. Oil-rich countries are allocating an energy subsidy to the public, making energy cheaper for their consumers. This may result in negative consequences, including households’ inefficient energy use behaviours in countries such as Iran. Beyond the impact of energy subsidy allocation, this study aims to explore the climatic and non-climatic factors that affect the increase in domestic electricity use, particularly in Iran. For this purpose, this study begins with a comparative analysis between countries with and without the energy subsidy to examine the trends in domestic electricity use. Afterwards, the tendency of households’ electricity use in Iran will be analysed in consideration of climatic and non-climatic factors among several provinces in Iran. This study exploited published statistical data for the analysis. The results indicate the tendency of increased domestic electricity use due to the country’s generous subsidy offered to the public as well as climatic and non-climatic factors in Iran. These results may provide an opportunity for future studies regarding building occupants’ inefficient energy use behaviours for policy enactment in Iran and other oil-rich countries.
Comparison of Freshwater Mussels Unio tumidus and Unio crassus as Biomonitors of Microplastic Contamination of Tisza River (Hungary)
Authors: Almeshal Wael , Takács Anita , Aradi László , Sandil Sirat , Dobosy Péter , Záray Gyula
Published: September 2022

Unio crassus and Unio tumidus mussels were collected at four sampling sites in the Tisza River (Hungary) to investigate their applicability as sentinel species for the biomonitoring of microplastic contamination. Since mussels, as filter feeders, are able to ingest particles only below a physically defined size, it was expected that their sentinel role in rivers is restricted to small particles, including fibers or microfibers. This assumption was confirmed by our results, as fibers were detected as the dominant particles in all the 80 mussel samples investigated. The length and diameter of the fibers changed in the size range of 20–1000 μm and 10–75 μm, respectively. The number of fibers in the individuals originating from the same sampling site was nearly two times higher in Unio tumidus than in Unio crassus and amounted to 2.7–4.9 and 5.2–8.3 items/individual. The fiber/g soft tissue ratio between these species could be characterized by a factor of three. After applying Raman spectrometry, mostly indigo-dyed polyethylene terephthalate and cellulose-based fibers, as well as a few larger (200 um) polyamide fragments, were identified. The microplastic particles stored temporarily by mussels provide only restricted qualitative information on the microplastic load of the Tisza River, and as our observations confirmed, the sampling efficiency of these ‘living sampling devices’ is highly species-specific.