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Power Cycling Testing for Power Semiconductor Switches:Methods, Standards, Limitations, and Outlooks
No full textReliability is a critical performance metric for power semiconductor switches and power electronic systems. Yet guidance on how to test and quantify that reliability is fragmented in the existing literature, particularly with the rapid adoption of wide-bandgap (WBG) devices and novel packaging technologies. This review brings guidance on what designers, reliability engineers, and researchers need to know about power cycling testing (PCT). We provide three major contents: first, introducing how new materials and packaging shift dominant failure mechanisms; second, comparing the main PCT standards joint electron device engineering council (JEDEC), automotive electronics council (AEC), international electrotechnical commission (IEC), and automotive qualification guideline (AQG) and explaining why the “test-to-fail” standard principle is overtaking legacy “test-to-pass” rules; and third, summarizing the unique challenges and existing solutions of applying PCT methods to WBG and ultra-WBG devices. Notably, to the best of the authors’ knowledge, this is the first in-depth analysis of the newly released IEC 60749-34:2025 and AQG 324:2025, benchmarked against their earlier editions. Moreover, by collecting more than 200 testing samples from the existing literature, we also offer the first generic lifetime model that spans Si, SiC, multiple bond-wire materials, and die-attach technologies. Finally, the limitations and associated open questions are discussed to identify future research opportunities.</p
Sequence Impedance Prediction for Grid-Connected Converters Based on Bi-LSTM
Get PDFThe large-scale application of voltage-source converters (VSCs) to power grids may negatively impact their stability. Stability analysis methods based on impedance modeling offer a theoretical framework to analyze and address this issue. However, under conditions of uncertainty regarding the internal structure and parameters of VSCs, existing impedance measurement techniques using frequency scanning are limited in terms of data acquisition and accuracy. In practice, the power output demand for VSCs in grid-connected operation tends to vary, making it challenging for frequency scanning schemes to account for changes in operating conditions. To address this challenge, this article proposes a sequence impedance prediction solution based on a bidirectional long short-term memory method, which requires only limited data to accomplish high-precision prediction of the overall impedance of VSCs under multiple operating points. Unlike the existing dq-based impedance prediction schemes, the sequence impedance method will greatly simplify the prediction process, and the physical meaning is clear. In addition, this article applies trained model to a small-scale VSC model through transfer learning for experimental validation. The process saves computational resources while maintaining prediction accuracy and demonstrates the adaptability of the proposed model.</p
Grid code requirements for the integration of renewable energy sources in Indonesia—a review
No full textThe large-scale integration of renewable energy sources into electric grids proposes significant challenges for any power grid management and planning. To address these challenges, system operators have developed GCs so that the grid operates safely, reliably, and economically. These codes establish technical, operational, and procedural standards for the connection and operation of renewable energy systems to the utility grid. This article investigates the current state of GCs in Indonesia as a case study, highlighting the growing need for updated and robust regulations to allocate renewable energy integration. The article focuses on the integration requirements for microgrid technologies, which are vital for decentralized energy systems and the proliferation of renewable resources, especially in remote and off-grid areas, especially Indonesia, and targets Indonesia to adopt renewable energy. Insights from Denmark’s advanced energy framework are utilized to propose recommendations for enhancing Indonesia’s GCs. A comparative analysis between the standard of IEEE 1547-2003 and IEEE 1547-2018 to compliance in terms of voltage regulation, fault ride-through capabilities, and Distributed Energy Resources (DERs) interoperability is carried out
Uncertainty-driven optimization of photovoltaic-integrated building-level energy Hubs:Advancing SDG 7 targets
No full textThis paper develops a bi-level uncertainty-driven optimization model whose fundamental elements are risk management at the upper level and the techno-economic and environmental assessment at the lower level to enhance the energy efficiency of photovoltaic-integrated building-level energy hubs (BEHs), supporting the goals of Sustainable Development Goal 7. The lower level uses the energy hub tool to model buildings as BEHs, efficiently coordinating energy carriers, conversion technologies, and storage systems. It aims to determine optimal operational schedules that meet various constraints while minimizing operational costs. The upper level applies risk-averse decision-making using information-gap decision theory to handle multiple, interdependent uncertainties over the operational horizon. A hybrid solution approach combines the non-dominated sorting genetic algorithm II at the upper level with the DICOPT solver at the lower level, addressing the model's complex, mixed-integer, and nonlinear structure. A hybrid decision-making tool is developed by integrating the fuzzy satisfying method with the distance metric methodology to identify the optimal solution from the Pareto frontier. The model is validated through cases on an industrial building, demonstrating superior performance over traditional approaches in key performance indicators. Overall, the model offers a robust and scalable method for optimizing energy efficiency in the building sector under simultaneous uncertainties.</p
Optimal construction of microgrids in a radial distribution system considering system reliability via proposing dominated group search optimization algorithm
Get PDFIn contemporary electrical networks, reliability stands as a paramount attribute. Since the introduction of distributed generation (DG) and microgrid (MG) concepts has considerably changed the structure of distribution networks, it is necessary to consider reliability aspects while going toward modern smart grids. This study introduces a novel methodology focusing on the partitioning of radial distribution systems into distinct MGs, strategically aimed at minimizing energy not supplied (ENS) to fortify overall system reliability. Two types of faults are considered including DG and busbar failures, and the impact of each kind of fault is investigated. Besides, a new Markov model is proposed to evaluate the reliability of DGs and MGs. Given the stochastic nature of the majority of DGs, the incorporation of energy storage systems (ESSs) can significantly enhance system performance. Therefore, this paper dedicates attention to exploring optimal ESS placement. To address the complex challenge of optimizing system partitioning, a modified version of the group search optimization (GSO) algorithm, named dominated GSO (DGSO) is proposed. The PG&E 69-bus distribution system is studied with two different structures to accurately investigate the effectiveness of the proposed partitioning approach on the system reliability. Moreover, the optimal number of MGs to be constructed within the intended system is determined
‘Caesar Augustus (Imperator)’, Roman Historiography section, Trends in Classics – Greek and Roman Humanities Encyclopedia (GROH), De Gruyter.
No full textExtending battery life in CubeSats by charging current control utilizing a long short-term memory network for solar power predictions
No full textRecently, there has been a surge in small satellites and CubeSats. A crucial factor limiting the duration of their missions is the lifespan of their batteries. Typically, batteries are charged immediately when there is sufficient power generated from the solar panels. However, this practice results in additional charging stress and degradation due to unnecessarily high current amplitudes. In this work, a distributed charging strategy based on solar power prediction is proposed to mitigate charging stress and thereby extend battery life, ensuring sufficient charging without jeopardizing spacecraft operation. The proposed method for power generation prediction relies on a Long Short-Term Memory (LSTM) network, trained on GOMX-4A satellite telemetry data. The proposed LSTM method performed an order of magnitude better, with a root mean square error (RMSE) of 0.2274 W, while a baseline prediction utilizing a Seasonal Auto-Regressive Moving Average has an RMSE of 1.2406 W. Using the predicted power generation from the LSTM method, the current is distributed using a proposed charging multiplier control, resulting in 72.0882% reduction in the median charging current. A direct possible impact on lithium-ion batteries was evaluated by employing an electrochemical model from the literature, confirming that the proposed strategy effectively reduces degradation caused by lithium plating. Moreover, the capacity fade in the example scenario at 25 °C was reduced by 0.0849%. The extent of degradation reduction will vary according to the required mission profile, the operational conditions, the specific chemistry, and the type of battery in use.</p
The Palgrave Handbook of Creativity in Sport
No full textThe Palgrave Handbook of Sport and Creativity is an extensive scholarly resource (currently) covering more than 40 chapters written by respected researchers and educators working in the intersection between sport and creativity research or related disciplines. Bringing together a diverse international cast of distinguished experts, the Handbook synthetizes the study of sport and creativity to offer a unique exploration of these multifaceted phenomena. Accordingly, the Handbook is intended to be an expansive, interdisciplinary introduction to the emerging field of creativity research in sport, serving as an irreplaceable reference and learning resource pertaining to topical debates and cutting-edge studies across the field
The Composition of the Fecal and Mucosa-adherent Microbiota Varies Based on Age and Disease Activity in Ulcerative Colitis
No full textBackgroundPediatric-onset ulcerative colitis (pUC) represents a more aggressive disease phenotype compared with adult-onset UC. We hypothesized that this difference can, in part, be explained by the composition of the microbiota.MethodsIn a prospective, longitudinal study, we included pediatric (N = 30) and adult (N = 30) patients with newly or previously (>1 year) diagnosed UC. We analyzed the microbiota composition in the mucosa-adherent microbiota at baseline, using 16S rRNA gene sequencing, and the fecal microbiota at baseline and at 3-month intervals, using shotgun metagenomics.ResultsFor fecal samples, the bacterial composition differed between pUC and aUC in newly diagnosed patients (β-diversity, Bray Curtis: R2 = 0.08, P = .02). In colon biopsies, microbial diversity was higher in aUC compared with pUC (α-diversity, Shannon: estimated difference 0.54, P = .006). In the mucosa-adherent microbiota, Alistipes finegoldii was negatively associated with disease activity in pUC while being positively associated in aUC (estimate: −0.255 and 0.098, P = .003 and P = .02 in pUC and aUC, respectively). Finally, we showed reduced stability of the fecal microbiota in pediatric patients, evidenced by a different composition of the fecal microbiota in newly and previously diagnosed pUC, a pattern not found in adults.ConclusionsOur results indicate that pediatric UC patients have a more unstable fecal microbiota and a lower α diversity than adult patients and that the microbiota composition differs between aUC and pUC patients. These findings offer some explanation for the observed differences between pUC and aUC and indicate that individualized approaches are needed if microbiota modifications are to be used in the future treatment of UC
Women's empowerment and social work practice in Iran:understanding and addressing women's vulnerability
No full textFollowing the Islamic Revolution in 1979, and due to traditional values, social workers who provide support for vulnerable women in Iran must navigate within a system that often limits women’s agency and autonomy. Based on ten semi-structured interviews with experienced Iranian social workers, this article illuminates how women’s vulnerability and empowerment are perceived and how women’s vulnerability is addressed in the empowerment process. The findings offer valuable insights to enhance empowerment practice by reflecting on the impacts of cultural norms and values on women’s empowerment. They contribute to a more nuanced understanding of how social workers in Iran perceive and address vulnerability and empowerment