Current Contribution Research Articles

Control-based Fault Current Limiter for Minimizing Impact of Distributed Generation Units on Protection Systems

Distributed generation units (DGUs) bring some problems to the existing protection system, such as those associated with protection blinding and sympathetic tripping. It is known that fault current limiters (FCLs) help minimize the negative impact of DGUs on the protection system. In this paper, a control-based FCL is proposed, i.e., the FCL is integrated into the DGU control law. To this end, a predictive control strategy with fault current limitation is suggested. In this way, a DGU is controlled, not only for power exchange with the power grid but also to limit its fault current contribution. The proposal is posed as a constrained optimization problem allowing taking into account the current limit explicitly in the design process as a closed-loop solution. A linear approximation is proposed to cope with the inherent nonlinear constraints. The proposal does not require incorporating extra equipment or mechanisms in the control loop, making the design process simple. To evaluate the proposed control-based FCL, both protection blinding and sympathetic tripping scenarios are considered. The control confines the DGU currents within the constraints quickly, avoiding large transient peaks. Therefore, the impact on the protection system is reduced without the necessity that the DGU goes out of service.

Protection of the Future Harbor Area AC Microgrids Containing Renewable Energy Sources and Batteries

A significant share of global carbon emissions is related to marine vessels running solely on fossil fuels. The hybrid or fully electrified marine vessels using battery energy storage systems (BESS) both for onboard propulsion system and for cold-ironing during docking at harbor areas will significantly reduce marine related carbon emissions. However, the transformation of marine vessels’ operations from diesel engines to BESS will necessarily require charging stations and other electric power infrastructure at harbor areas. The sustainable and cheap energy of renewable energy sources like wind turbine generators (WTGs), photovoltaic (PV) systems and related BESS could be used at harbor areas for charging depleted vessel-BESS and supplying power to cold-ironing loads. For this purpose, two new harbor area smart grid or AC microgrid models have been developed by our research group. This paper presents a comprehensive analysis of three-phase short-circuit faults for one of the proposed AC microgrid models using PSCAD/EMTDC simulations. The fault study of harbor area AC microgrid-1 is done for both grid-connected and islanded modes. The main purpose of the fault study is to check if grid-connected mode overcurrent settings of intelligent electronic devices (IEDs) will also be valid for different islanded mode fault cases with different fault current contributions from converter-based distributed energy resources (DERs) including WTG, PV and BESS. The extent of fault current contribution from DERs and BESS to avoid adaptive protection settings and to ensure definite-time protection coordination and fast fuse operations during different islanded modes is investigated.

MOLECULAR STUDY OF CORE-SHELL RATIO EFFECT ON THERMOPHYSICAL PROPERTIES OF SIO2@AU-WATER NANOFLUID

Thermal conductivity (λ) and specific heat capacity (<i>c<sub>p</sub></i>) are essential thermophysical properties related to thermal storage systems. Molecular simulations of the shell-to-total-radius ratios (Φ) of SiO<sub>2</sub>@ Au nanoparticle (NP) are used to investigate their impact on the <i>c<sub>p</sub></i> and λ of water nanofluids (NFs) containing this NP. The roles of solid/liquid and solid/solid interfaces on <i>c<sub>p</sub></i> and λ are identified by using the calculations of the vibrational density of state (VDOS) of the SiO<sub>2</sub>@Au nanoparticle, the core (SiO<sub>2</sub> molecule), the shell (Au atom), and the thin layer of water molecules next to the particle surface. The effects of core-shell NPs on the characteristics of the base fluid are further understood by using the VDOS mismatch between the NP and the thin water layer and the radial distribution function of water molecules. The heat current contribution is discussed to view the λ increase mechanism of NF. It is found that <i>c<sub>p</sub></i> increases with increasing Φ, while λ increases with decreasing Φ. The convection component and the virial term consisting of the heat current are considerable contributions. New correlations are proposed for calculating the <i>c<sub>p</sub></i> and λ of NFs containing core-shell NPs, thus explaining the contributions of the components to <i>c<sub>p</sub></i> and λ of NFs. The study of the effect of Φ on the thermophysical characteristics of these NFs provides molecular insight into the roles of the solid/liquid and solid/solid interfaces. These results contribute to the understanding of the thermophysical properties of core-shell NFs and their uses in solar thermal applications.

CONTRIBUIÇÕES DE PAULO FREIRE PARA A EDUCAÇÃO DE JOVENS E ADULTOS: UMA REVISÃO NARRATIVA

ABSTRACT: Even 50 years after the launch of Paulo Freire's Pedagogy of the Oppressed, his current contributions to the field of education are perceptible. This article discusses the education for young people and adults guided by Freire's principles. To do so, we developed a narrative review based on the book Pedagogy of the Oppressed and analyzed four themes, namely: (I) the human essence and knowledge; (II) the individual-society relationship; (III) the theory-practice relationship and the objectivity-subjectivity relationship; (IV) the social purposes of education and the teacher's place in the educational process. As a result, we perceived that Paulo Freire's pedagogy is the result of a long life journey, a man's journey between his origins, his world, experiences, readings, and contact with other subjects. His pedagogical and humanistic ideas depart from the micro to the macrocosms, from the world of the less privileged classes in opposition to the privileged ones. In the educational field of young people and adults, taking Paulo Freire as an inclusive educator means, among other aspects, building types of knowledge that consider diverse worldviews and enables the humanization process.

CT Study of the Cranial Osteology of the Gray Short-Tailed Opossum Monodelphis domestica (Wagner, 1842) (Marsupialia, Didelphidae) and Comments on the Internal Nasal Skeleton Floor

The individual bones of the adult cranium of the gray short-tailed opossum, Monodelphis domestica (Wagner, 1842) are described and illustrated in multiple views based on CT scans. The author previously reported on the outer bony surfaces of the skull of Monodelphis Burnett, 1830, and the current contribution is a companion piece, paying particular attention to the inner bony surfaces (within the endocranium and nasal cavity) and the facets between individual cranial elements, including the ethmo- and frontoturbinals. Comments are provided on the internal nasal floor skeleton, which in M. domestica includes a fused conglomerate formed by the medial palatine processes of the premaxillae, the vomer, the ethmoid, the presphenoid, and the orbitosphenoids. This conglomerate includes horizontal shelves just dorsal to the hard palate, and occurs widely in marsupials but is currently unknown in monotremes and placentals.

CaV3.1 T-type calcium channels are important for spatial memory processing in the dorsal subiculum

The dorsal subiculum (dSub) is one of the key structures responsible for the formation of hippocampal memory traces but the contribution of individual ionic currents to its cognitive function is not well studied. Although we recently reported that low-voltage-activated T-type calcium channels (T-channels) are crucial for the burst firing pattern regulation in the dSub pyramidal neurons, their potential role in learning and memory remains unclear. Here we used in vivo local field potential recordings and miniscope calcium imaging in freely behaving mice coupled with pharmacological and genetic tools to address this gap in knowledge. We show that the CaV3.1 isoform of T-channels is critically involved in controlling neuronal activity in the dSub in vivo. Altering neuronal excitability by inhibiting T-channel activity markedly affects calcium dynamics, synaptic plasticity, neuronal oscillations and phase-amplitude coupling in the dSub, thereby disrupting spatial learning. These results provide an important causative link between the CaV3.1 channels, burst firing of dSub neurons and memory formation, thus further supporting the notion that changes in neuronal excitability regulate memory processing. We posit that subicular CaV3.1 T-channels could be a promising novel drug target for cognitive disorders.

Relationship between Fault Level and System Strength in Future Renewable-Rich Power Grids

The fault level is used as a simple indicator for scanning the system strength in power systems. To an extent, this has proven its efficacy in classical power systems based on synchronous generation (SG). However, power electronics-based renewable energy sources (RESs), due to their controlled and limited fault current contribution, may affect the impedance, fault level, and system strength in a non-linear manner. Hence, this raises a question about the validity of using the fault level as a measure reflecting the system strength in future grids. This paper intends to shed light on the above question by examining the correlation between the fault level and the system strength in future grid scenarios. This is achieved in two steps: first, by employing the measure-based Thevenin impedance for fault level estimation in renewable-rich grids, and second, by comparing these estimated fault levels with those obtained from steady-state and dynamic simulations. While the results have demonstrated the suitability of using the fault level for system strength scanning in scenarios of low penetration of RESs, they revealed that such a tool might be misleading with very high RES penetrations. The findings have been verified using the adjusted IEEE nine-bus test system in DIgSILENT PowerFactory.

Enhancement of adsorption efficiency by surface modified Avocado seed for xylene removal

<p>The current study work's contribution relates to the removal of xylene using an adsorbent with modified surfaces made from a naturally occurring substance called avocado seed. With the aid of a muffle furnace heated to 600⁰c, this was converted to become activated carbon. Activated carbon is modified on the surface using titanium di oxide (Tio2). This surface modification demonstrated significant performance in the designated surface area of 67.35 m2 g-1. The varied levels of xylene concentration drop at three distinct temperatures 30, 60, and 90⁰C were visible. Applying the Thomas and Adams-Bohart to describe equilibrium adsorption data resulted in the model having the highest R2 values for describing equilibrium isotherm data. SEM patterns captured the degree of the surface modification with increased porosity; however, XRD and FTIR analyses of the surface modified adsorbent did not reveal any structural distortion. This thorough analysis resulted in the efficient removal of 93% of xylene by cost-effective adsorbent</p>

The Importance of Implementing SDGs by Small and Medium Size Enterprises: Evidence from Germany and Poland

This study addresses the problems attributed to the implementation process of Sustainable Development Goals (SDGs) in relation to the SME sector in Germany and Poland. The initial part of this study discusses the theoretical aspects of sustainable development, with particular emphasis on the adoption of the 2030 Agenda for Sustainable Development, including 17 SDGs. The importance of the contribution made by small and medium sized enterprises (SMEs) to the development of today’s economies, based on the example of OECD countries, was also highlighted. Regarding methodology, to answer the research questions, empirical data were obtained using a simplified online questionnaire based on a pre-established questionnaire. The target group consisted of experts on SMEs, not the SMEs themselves, in order to obtain an external view of the SME sector. As part of the general conclusions, it can be stated that the current contribution of SMEs to the implementation of the SDGs presents, on average, an upward tendency. Certainly, a greater involvement of entrepreneurs and a better understanding of the specificity of sustainable development processes would be advisable. In addition, it is noticeable that the national context is significant in the implementation of the SDGs. For example, German enterprises pay more attention to the environmental dimension of sustainable development, whereas Polish enterprises pay more attention to supply chain management. Overall, most of the respondents stated that the absence of financial resources remains the primary obstacle to the implementation of sustainable development goals in enterprises, while motivation results from cost reduction and increase in turnover.

Optical genome mapping and revisiting short-read genome sequencing data reveal previously overlooked structural variants disrupting retinal disease−associated genes

PurposeStructural variants (SVs) play an important role in inherited retinal diseases (IRD). Although the identification of SVs significantly improved upon the availability of genome sequencing, it is expected that involvement of SVs in IRDs is higher than anticipated. We revisited short-read genome sequencing data to enhance the identification of gene-disruptive SVs. MethodsOptical genome mapping was performed to improve SV detection in short-read genome sequencing−negative cases. In addition, reanalysis of short-read genome sequencing data was performed to improve the interpretation of SVs and to re-establish SV prioritization criteria. ResultsIn a monoallelic USH2A case, optical genome mapping identified a pericentric inversion (173 megabase), with 1 breakpoint disrupting USH2A. Retrospectively, the variant could be observed in genome sequencing data but was previously deemed false positive. Reanalysis of short-read genome sequencing data (427 IRD cases) was performed which yielded 30 pathogenic SVs affecting, among other genes, USH2A (n = 15), PRPF31 (n = 3), and EYS (n = 2). Eight of these (>25%) were overlooked during previous analyses. ConclusionCritical evaluation of our findings allowed us to re-establish and improve our SV prioritization and interpretation guidelines, which will prevent missing pathogenic events in future analyses. Our data suggest that more attention should be paid to SV interpretation and the current contribution of SVs in IRDs is still underestimated.

Enhancing Intangible Cultural Heritage for Sustainable Tourism Development in Rural Areas: The Case of the “Marche Food and Wine Memories” Project (Italy)

In the context of increasing interest in the contribution made by culture to the implementation of the goals and targets of the 2030 Agenda for Sustainable Development, the present research investigates how intangible cultural heritage (ICH) can help sustainable tourism in rural areas. Adopting a case study methodology, we analyzed the “Marche Food and Wine Memories” project, an initiative promoted by CiùCiù, a winery based in Offida, a small village in the Marche region (Italy). After discussing the strategies and tools adopted to enhance rural heritage, the analysis focuses on the involvement of local communities and businesses in the different phases of the process. The research aimed to understand: (1) the project’s current contribution to the economic, social, cultural and environmental dimensions of sustainability; and (2) its strengths and weaknesses and possible future improvements. The research findings confirm the high potentialities of ICH-based initiatives for sustainable tourism development in rural areas, but also reveal the need to improve the level of networking with local businesses and highlight gaps in marketing and management skills. Finally, the results provide policy and managerial implications for similar ICH-based initiatives.

A research agenda for nonvascular photoautotrophs under climate change.

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Blood‐based electro‐osmotic flow of non‐Newtonian nanofluid (Carreau‐Yasuda) in a tapered channel with entropy generation

AbstractThe motivation of current contribution is to signify the assessment of entropy generation in the flow of generalized Newtonian fluid generated under the influence of electro‐osmosis and peristalsis. The flow has been confined by a tapered channel with certain flow assumptions. The fundamental conservations laws of mass, momentum, energy and concentration along with the Poisson and Nernst‐Planck equations are used to identify the problem in given domain. The Poisson equation is solved analytically for potential function under the Debye‐Huckel linearization approximation while the expressions are attained with association of conservation concept under widely used assumptions of minor Reynolds number and long wavelength. The velocity in axial direction, temperature and nanoparticles profiles are numerically approximated using shooting method. The electric force parameter and radiative constant are being expressed against different flow, temperature and concentration features via various sketches. The results for Newtonian and Carreau fluid as particular case are also presented via numerous plots and tables. It is expected that the obtained theoretical results are very useful for the resilience of medical instatements.

Renewable Energy Resources Technologies and Life Cycle Assessment: Review

Moving towards RER has become imperative to achieve sustainable development goals (SDG). Renewable energy resources (RER) are characterized by uncertainty whereas, most of them are unpredictable and variable according to climatic conditions. This paper focuses on RER-based electrical power plants as a base to achieve two different goals, SDG7 (obtaining reasonably priced clean energy) and SDG13 (reducing climate change). These goals in turn would support other environmental, social, and economic SDG. This study is constructed based on two pillars which are technological developments and life cycle assessment (LCA) for wind, solar, biomass, and geothermal power plants. To support the study and achieve the main point, many essential topics are presented in brief such as fossil fuels’ environmental impact, economic sustainability linkage to RER, the current contribution of RER in energy consumption worldwide and barriers and environmental effects of RER under consideration. As a result, solar and wind energy lead the RER electricity market with major contributions of 27.7% and 26.92%, respectively, biomass and geothermal are still of negligible contributions at 4.68% and 0.5%, respectively, offshore HAWT dominated other WT techniques, silicon-based PV cells dominated other solar PV technologies with 27% efficiency, combustion thermochemical energy conversion process dominated other biomass energy systems techniques, due to many concerns geothermal energy system is not preferable. Many emerging technologies need to receive more public attention, intensive research, financial support, and governmental facilities including effective policies and data availability.

A numerical analysis of the transport of modified hybrid nanofluids containing various nanoparticles with mixed convection applications in a vertical cylinder

The hybrid materials are an impressive class of nanofluids with exciting thermal outcomes and present applications in enhancing the heat transfer procedure, solar energy, extrusion processes, and in different engineering processes. The current contribution aims to reflect the improved mechanism of the heat transfer phenomenon for hybrid nanofluids. Aluminum oxide, copper, and copper oxide at different solid volume fractions are used to report the thermal phenomenon. For the base material, water is used. The mixed convection applications are also encountered. The moving cylinder with a stretched uniform velocity causes the flow. The velocity slip and convective boundary constraints are used to observe the flow phenomenon. The hybrid nanofluid is expressed via different mathematical relations. The shape factors for hybrid nanomaterials are presented. The Keller box numerical method with effective accuracy has been entertained for the simulation process. The applications of parameters for the current model are explained via graphs.

TARGETING IMPLICATION IN A JOINT FORCE OPERATION FOR NATIONAL DEFENSE

In this paper I wanted to highlight the importance of the targeting process in planning and conducting an eventual joint force operation for the purpose of armed national defense. Even though Romania is an active member of the North Atlantic Treaty Organization (NATO), for national defense purposes Romanian armed forces must be capable to plan and conduct operations with existent armed structures until allied forces would intervene in case of an armed aggression under article 5 specifications. Having participated with forces and structures in various multinational operations and exercises alongside current national contributions under NATO partnership, Romanian armed forces continuously improve their level of training and over time implemented in our standing doctrines and field manuals many of our partner’s procedures. One such procedure is the target management process. National joint force headquarters including those functioning at component and division levels should permanently consider, plan and conduct target management training for responsible personnel, especially with those working in information and operation modules, as they will be part of targeting working committees, groups or cells that activate at their respective structures both in peacetime or combat operations. One other significant factor influencing the target management process in a national defense operation is the application of Laws of Armed Conflict and rules of engagement in an eventual armed aggression.

Review of Methods for Addressing Challenging Issues in the Operation of Protection Devices in Microgrids with Voltages of up to 1 kV That Integrates Distributed Energy Resources

With the large-scale integration of distributed energy resources (DER) into passive distribution networks with voltages of up to 1 kV, these networks are being converted into microgrids. When the topology and operating conditions change, several challenging issues arise related to the functioning of the protection devices (PD) that are in operation. Most DERs, including renewable generators, are integrated into microgrids by means of inverters. In the event of short circuits (SC) in microgrids, these DERs provide a fault current contribution of no more than 1.2–2.0 Irated at the fault location. This makes it difficult to identify the fault location and to carry out the selective disconnection of the faulty element by means of conventional PDs. This article provides an overview of engineering solutions for improving conventional protection schemes that have been historically used in passive distribution networks, as well as for creating modern protection schemes based on innovative principles and new methods. The use of adaptive protections built on decentralized and centralized principles in most cases ensures the reliable protection of microgrids. Modern intelligent electronic devices (IEDs), where protection functions are implemented, rank higher with respect to their technical perfection in terms of reliability, sensitivity, selectivity, and speed performance. The use of multi-agent systems in the implementation of modern protection schemes requires the availability of broadband communication channels, which hinders their use because of the high cost. The combined use of fault current limiters (FCL) and energy storage systems (ESS) allows for the reliable operation of microgrid protections. The use of modern PDs ensures the reliable operation of DERs and power supply to consumers in microgrids, both in the case of grid-connected and islanded operation modes. Since there is no unified concept of designing protection schemes for microgrids with DERs, the choice of specific approaches to the design of protection schemes should be based on the results of a comparative technical and economic analysis of different options.

Tides, Internal and Near‐Inertial Waves in the Yermak Pass at the Entrance of the Atlantic Water to the Arctic Ocean

AbstractIn the crucial region of the Yermak Plateau where warm Atlantic water enters the Arctic ocean, we examined high frequency variations in the Yermak Pass Branch over a 34 months‐long mooring data set. The mooring was ice covered only half of the time with ice‐free periods both in summer and winter. We investigated the contribution of residual tidal currents to the low frequency flow of Atlantic Water (AW) and high frequency variations in velocity shears possibly associated with internal waves. High resolution model simulations including tides show that diurnal tide forced an anticyclonic circulation around the Yermak Plateau. This residual circulation helps the northward penetration of the AW into the Arctic. Tides should be taken into account when examining low frequency AW inflow. High frequency variations in velocity shears are mainly concentrated in a broad band around 12 hr in the Yermak Pass. Anticyclonic eddies, observed during ice‐free conditions, modulate the shear signal. Semi‐diurnal internal stationary waves dominate high frequency variations in velocity shears. The stationary waves could result from the interaction of freely propagating semi‐diurnal internal waves generated by diurnal barotropic tides on critical slopes around the plateau. The breaking of the stationary waves with short length scales possibly contribute to mixing of AW at the entrance to the Arctic.

Tibor Valuch. Everyday Life under Communism and After: Lifestyle and Consumption in Hungary, 1945–2000

Tibor Valuch. <i>Everyday Life under Communism and After: Lifestyle and Consumption in Hungary, 1945–2000</i>

Enhancements to Language Modeling Techniques for Adaptable Log Message Classification

Minimizing the resolution time of service-impacting incidents is a fundamental objective of Information Technology (IT) operations. Efficient root cause analysis, adaptable to diverse service environments, is key to meeting this objective. One method that provides additional insight into an incident, and hence allows enhanced root cause analysis, is categorisation of the events and log messages that characterize an incident into pre-defined operational groups. Well established natural language processing techniques that utilize pre-trained language models and word embeddings can be leveraged for this task. The adaptability of pre-trained models to classify log messages, containing large quantities of domain-specific language, remains unknown. The current contribution investigates multiple ways of addressing this deficiency. We demonstrate increased granularity of word embeddings by using character decompositions and sub-word level representations, and also explore the augmentation of word embeddings using features derived from convolutional operations. After observing that the performance of high-specificity models decreases as the number of previously unseen words increases, we explore the circumstances in which we can use a model trained with a low-specificity corpus to correctly classify log messages. Through the application of fine-tuning techniques, we can adapt our pre-trained classifier to classify log messages from service environments not encountered during pre-training in a time, and memory efficient manner. We conclude that we can effectively adapt pre-trained classifiers for impromptu service environments.