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Contribution of Grid-Forming Control to Angle Stability in the Iberian Peninsula
No full textGrid-forming controls transform the way converter-interfaced renewable resources interact with the power grid, and their impact on angle stability is still not well-known. This paper analyzes the effect of grid-forming controls on the stability of a grid after a severe disturbance consisting of a short-circuit followed by a power system split. A phasor-based model of a grid-forming control is developed and a 1497-bus model of the Iberian Peninsula transmission system is derived from a data set provided by the association of transmission system operators ENTSO-E. The results show that grid-forming controls attenuate the phase jump caused by the split of the power system by 31%, as demonstrated by the deviation of the phase angle, which reduced from 13 degrees to 9 degrees after the application of grid-forming control strategies.This work was funded by Agencia Estatal de Investigación MCIN/AEI/ 10.13039/501100011033 under Grant PID2023-150401OB-C21
Relationship between sensor size and optical bandwidth in perovskite-based solar cells as VLC receivers
Get PDFProceedings of 2025 15th Spanish Conference on Electron Devices (CDE), 28-30 Jan. 2025, Málaga, SpainThis work focuses on the characterization of perovskite photovoltaic cells (PPVCs) for visible light communication (VLC) in terms of efficiency and bandwidth, especially for indoor and outdoor environments. Moreover, a comparison between different perovskite devices bandgap is carried out to observe the relationship between bandgap-bandwidth and bandgap-efficiency. The results demonstrate the viability of using PPVCs for VLC based on the achieved bandwidth of 4.85 MHz and 22% efficiency.This work is part of the STEP-UP (TED2021-131600B-C33) and PLEDs (PID2022-140090OBC22) Projects, both financed by the Spanish Ministry of Science and Innovation MCIN / AEI / 10.13039 / 501100011033, STEP-UP also by the European Union "NextGenerationEU", and PLEDs by "ERDF A way of making Europe", the European Network on future generation Optical Wireless Communication technologies under the Cost Action CA19111 Newfocus, and the Spanish Ministry of Science, Innovation and Universities under "Doctorados Industriales" grant DIN2019-010458
Designing nickel coatings for water erosion performance: Optimisation of grain size and thickness
Get PDFMetallic coatings are gaining interest as an alternative to classical polymeric layers for erosion damage prevention due to their extended durability and sustainability. However, their implementation requires a thorough understanding of protective potential and reliability. This study explores the use of brush-plated nickel coatings on carbon-fibre reinforced composites to enhance their performance against water erosion. A combination of experimental analysis and computational modelling explores the effect of different coating thickness and properties to withstand water droplet erosion damage. Findings reveal a minimum critical coating thickness around 40 μm can significantly improve the erosion resistance.We wish to acknowledge the support of the Henry Royce Institute for advanced materials through the Materials Challenge Accelerator Programme, funded from a grant provided by the Engineering and Physical Sciences Research Council, United Kingdom (EP/X527257/1)
Topology optimization of lattice structures for target band gaps with optimum volume fraction via Bloch-Floquet theory
Get PDFIn this work, a topology optimization algorithm has been developed to design bi-material lattice structures showing a band gap around a target frequency, using just one unit cell through the application of Bloch-Floquet theorem. The Bidirectional Evolutionary Structural optimization (BESO) method has been employed, based on bi-material interpolation. A new objective function has been defined, which uses only the natural frequencies closest to the target one, regardless of their position with respect to the fundamental natural frequency. This reduces the computational cost by limiting the number of frequencies considered, and improves the robustness of the optimization process, as these frequencies adapt to changes in the distribution of materials within the domain, constantly encompassing the target frequency. In addition, a novel approach has been implemented to determine the optimal volume fraction of the materials forming the structure, a parameter typically predefined in other works before starting the optimization process. Consequently, the algorithm can autonomously identify the volume that produces the widest band gap around the target frequency. The algorithm has been evaluated for different cases of lattice structures formed by the periodic repetition of a unit cell in both 1D (1D-CR) and 2D (2D-CR), comparing some results with those obtained in other works through different approaches.F. Gómez-Silva and R. Zaera acknowledge support from MCIN/AEI/10.13039/501100011033 and from FEDER, UE under Grant number PID2021-123294OB-100. This work has been also supported by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M24), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation). R. Ortigosa and J. Martínez-Frutos acknowledge the support of grant PID2022-141957OA-C22 funded by MICIU/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. They also acknowledge the support provided by the Autonomous Community of the Region of Murcia, Spain through the programme for the development of scientific and technical research by competitive groups (21996/PI/22), included in the Regional Program for the Promotion of Scientific and Technical Research of Fundacion Seneca - Agencia de Ciencia y Tecnologia de la Region de Murcia. Funding for APC: Universidad Carlos III de Madrid (Agreement CRUE-Madroño 2024)
High-Frequency Current Transformer Design to Detect Serial Arcs in More Electric Aircraft
Get PDFSerial arcs in dc circuits are a well-known hazard in the field of photovoltaic systems and it is especially sensitive and critical in aerospace and aeronautic equipment. Unlike parallel arcs, the detection of this particular ionization phenomenon cannot be done with the currently available protection devices, so the industry is interested in finding a solution. The first step is to choose a sensor capable of reading the physical consequences of an active arc and the appearance of high-frequency (HF) current pulses derived from the arc has been proven to be a reliable method of detection. Inductive sensors are allegedly one of the most promising detectors in terms of sensitivity, cost, and adaptability to the circuit wiring. For aircraft applications, size and weight are additional constraints that limit the use of certain heavy inductive sensors, so an air-core inductive sensor was proposed by the authors in a previous work. This article is a step forward in the design of a solution using small and weightless toroidal ferrites to detect serial arcs. The geometric parameters, number of turns, cut-off frequency, bandwidth, and sensitivity connected to a 50- Omega impedance of the proposed sensor are parameterized using a model based on a transformer-equivalent circuit. The model is successfully validated with experimental measurements, and a candidate is chosen according to the constraints imposed by the application in airborne electric systems. Finally, a complete set of measurements of arcs is conducted to test its performance compared with the other two sensors. The aim is to quantify the sensitivity of the HF current pulses created by the arc activity when compared to the background noise.This work was supported in part by the European Union through the HECATE Project under Grant 101101961-HECATE, and in part by the Funding for APC: Universidad Carlos III de Madrid under Agreement CRUE-Madroño 2024
Basic mathematical skills and fraction understanding predict percentage understanding: Evidence from an intelligent tutoring system
Get PDFResearch on fostering learning about percentages within intelligent tutoring systems (ITSs) is limited. Additionally, there is a lack of data-driven approaches for improving the design of ITS to facilitate learning about percentages. To address these gaps, we first investigated whether students' understanding of basic mathematical skills (eg, arithmetic, measurement units and geometry) and fractions within an ITS predicts their understanding of percentages. We then applied a psychological network analysis to evaluate interdependencies within the data on 44 subtopics of basic mathematical concepts, fractions and percentages. We leveraged a large-scale dataset consisting of 2798 students using the ITS bettermarks and working on approximately 4.1 million mathematical problems. We found that advanced arithmetic, measurement units, geometry and fraction understanding significantly predicted percentage understanding. Closer inspection indicated that percentage understanding was best predicted by problems sharing similar features, such as fraction word problems and fraction/natural number multiplication/division problems. Our findings suggest that practitioners and software developers may consider revising specific subtopics which share features with percentage problems for students struggling with percentages. More broadly, our study demonstrates how evaluating interdependencies between subtopics covered within an ITS as a data-driven approach can provide practical insights for improving the design of ITSs. Practitioner notes What is already known about this topic Longitudinal studies showed that basic mathematical skills predict fraction understanding. There is only limited evidence on whether similar predictions can be observed for percentage understanding¿in general and within intelligent tutoring systems. Process data from such intelligent tutoring systems can be leveraged to pursue both educational research questions and optimizing digital learning software. Problems involving percentages typically are word problems requiring multiplications and/or divisions. What this paper adds Similar to the case of fractions, students' performance on advanced arithmetic, measurement units and geometry significantly predicted performance with percentages. Students' performance with fractions also predicted performance with percentages significantly. A psychological network analysis was applied to evaluate specific interdependencies between a range of subtopics (eg, Multiplying and dividing fractions, Adding and subtracting fractions and Calculating with percentages). Fraction word problems and fraction problems involving multiplication/division turned out to be the best predictors of understanding percentages. Implications for practice and/or policy When facing difficulties with percentages, revision of previous mathematical concepts sharing similar features (eg, fraction word problems, fraction/natural number multiplication/division problems) may be advised. Software developers may consider implementing such data-driven revision recommendations for students facing difficulties within intelligent tutor systems. Psychological network analysis can be utilized as a learning analytics method for easy-to-access visualizations illustrating relationships between a large range of different subtopics
Life cycle assessment studies of concentrated solar power technology: A literature review
Get PDFThe current study offers a literature review of Life Cycle Assessment (LCA) in the context of Concentrated Solar Power (CSP) technology. The methodology involved a bibliometric search and an in-depth critical literature review. The existing reviews indicated opportunities to enhance clarity in the methodology used for selecting literature. Subsequently, the reviewed literature was presented in tabular format, categorized according to CSP plant configuration, subsystem, and technology purpose. The findings indicate lack of available data to perform accurate inventories, and a lack of harmonization of the Life Cycle Impact Assessment methodologies. The results revealed that the most analyzed impact category was climate change, with values averaging 50 g CO2, eq/kWh. There is a need for more LCA investigations about dish-Stirling and Linear Fresnel plants, as well as investigations analyzing other impact categories. Many studies in the CSP LCA domain are directing their attention towards thermal storage, however, the environmental impact of the decommissioning of plants has not yet been thoroughly analyzed. It has been observed that SimaPro is the preferred LCA software by the authors, together with Ecoinvent as database. The literature review revealed a gap in knowledge in LCA studies addressing operational challenges such as corrosion or fatigue, emerging solutions, and updated inventory data, presenting an opportunity for researchers to enhance the market viability of CSP technologies by addressing these deficiencies. Finally, a simplified case study comparing Central Receiver and Parabolic Trough Collector (PTC) systems found that PTC had higher environmental impacts due to the contribution of the Heat Transfer Fluid (HTF).The authors would like to thank the EU-funded HORIZON MSCA
“TOPCSP: Towards competitive, Reliable, Safe and Sustainable
Concentrated Solar Power (CSP) Plants” Doctoral Network Project:
[grant number 101072537]
An experimental study of high-velocity multiple impact on the structural behaviour of GFRP Cross-Ply laminates
Get PDFThis study examines the experimental behaviour of composite structures subjected to high-velocity multiple impact, which is critical in applications where simultaneous impacts from multiple projectiles or debris may occur. This work also investigates the influence of the distance between projectiles on global variables, including the damaged area. Furthermore, a comparison is conducted between single and multiple high-velocity impact. The findings reveal that both the damaged area, the ballistic limit and the residual velocity of the projectiles are significantly affected by the simultaneous multiple impact phenomenon.This work was supported by the Universidad Carlos III de Madrid in the Acción Estratégica en “Modelos de Daño en Composites en Problemas Dinámicos” (grant number 2010/00309/003)
Dimorphos's Material Properties and Estimates of Crater Size from the DART Impact
Get PDFArtículo escrito por un elevado número de autores/as, solo se referencia el/la que aparece en primer lugar y autora perteneciente a la UC3M. El resto de autores son: Kathryn M. Kumamoto, Dawn M. Graninger, Mallory E. DeCoster, Wendy K. Caldwell, Jason M. Pearl, J. Michael Owen, Olivier Barnouin, Gareth S. Collins, R. Terik Daly, Jens Ormö, Jessica Sunshine, Carolyn M. Ernst, Toshi Hirabayashi, Simone Marchi, Laura Parro, Harrison Agrusa, Megan Bruck Syal, Nancy L. Chabot, Andy F. Cheng, Thomas M. Davison, Elisabetta Dotto, Eugene G. Fahenstock, Fabio Ferrari, Martin Jutzi, Alice Lucchetti, Robert Luther, Nilanjan Mitra, Maurizio Pajola, Sabina Raducan, KT Ramesh, Andrew S. Rivkin, Alessandro Rossi, Paul Sánchez, Stephen R. Schwartz, Stefania Soldini, Jordan K. Steckloff, Filippo Tusberti, Kai Wünnemann and Yun ZhangOn 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft intentionally collided with Dimorphos, the moon of the binary asteroid system 65803 Didymos. This collision provided the first full-scale test of a kinetic impactor for planetary defense. Images from DART's DRACO camera revealed Dimorphos to be an oblate spheroid covered in boulders of varying sizes and shapes. Very little was known about Dimorphos prior to DART's impact, including its shape, structure, and material properties. Approach observations and those following the DART impact have provided crucial knowledge that narrows the parameter space relevant to modeling the impact into Dimorphos. Here we present the results of a suite of hydrocode simulations of the DART impact on Dimorphos. Despite remaining uncertainties, initial models of DART's kinetic impact provide important information about the results of DART (e.g., potential crater size and morphology, ejecta mass) and the properties of Dimorphos. Simulations here suggest that Dimorphos has near-surface strength ranging from a few Pascals to tens of kPa, which corresponds to crater sizes of 40–60 m. Simulated crater sizes provide a crucial comparison metric for the European Space Agency Hera mission when it arrives at the Didymos system. Hera's measurement of crater size in combination with measurement of Dimorphos's mass will allow us to assess our simulations and provide the information needed to make the DART impact experiment both the first test of a planetary defense mitigation mission and the first full-scale planetary defense simulation validation exercise.This work was supported by the DART mission, NASA Contract No. 80MSFC20D0004. Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL–JRNL-853805. Portions of this work were supported by the Advanced Simulation and Computing (ASC) Verification and Validation Planetary Defense Program at Los Alamos National Laboratory. Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract 89233218NCA000001. LA-UR-24-25758. MP, AL, and FT acknowledge financial support from Agenzia Spaziale Italiana (ASI, contracts No. 2019-31-HH.0 and No. 2022-8-HH.0). The work by J.O., S.R., and G.S.C was supported by grant PID2021-125883NBC22 by the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe.” The work by J.O., I.H., S.R., R.L., M.J., and K.W. was supported by the Spanish Research Council (CSIC) support for international cooperation: I-LINK project ILINK22061
Indemnización y las fronteras entre compensar, castigar y prevenir
No full text[ES] El objetivo central de este trabajo es responder sobre la compatibilidad jurídica entre la responsabilidad civil extracontractual y las funciones punitiva y preventiva, en contraposición a la teoría tradicional de índole estrictamente reparatoria. La metodología utilizada es basada en la revisión bibliográfica, legislativa y jurisprudencial, buscando en los estudios un equilibrio entre la teoría y la práctica, incluyendo sistemas jurídicos elegidos como ejemplos de las familias del civil law y common law. El estudio comienza con apuntes de Teoría General del Derecho, pasa por la historia del Derecho Romano y por nociones de la filosofía aristotélica, para introducir una reflexión crítica sobre el concepto de daño y las finalidades de la Responsabilidad Civil. Concluye con el potencial multifuncional de la indemnización, que permite calibrar la fuerza sancionatoria para alcanzar diferentes objetivos, según cada ordenamiento. A continuación, se analiza la figura de los punitive damages y las formas de indemnización punitiva adoptadas por países de tradición inspirada en la cláusula general de responsabilidad civil inaugurada por el Código Civil Francés de 1804. El objeto de estudio se somete a un análisis crítico con el apoyo de las contribuciones de las teorías absolutas y relativas sobre la finalidad de las penas, llevando a la conclusión que indemnizar, castigar y prevenir no necesariamente tienen diferentes propósitos, pues se aproximan a depender del marco teórico utilizado y a partir de las distintas formas de comprender el fenómeno sancionatorio. La función prescriptiva de la indemnización despunta como puerto seguro, capaz de representar la complejidad subjetiva de la relación de responsabilidad, incluyendo el direccionamiento del comando normativo a los polos de esa relación. De un lado, se tutela el daño sufrido por la víctima y, de otro, se comunica al ofensor sobre el rechazo de su conducta por el ordenamiento. Se propone la clasificación de la indemnización basada en el enfoque de los criterios de su cálculo en relación con el ofensor y la víctima. Se denomina daño moral por grave conducta a la violación del interés existencial de la víctima que resulta de la reificación ilícita sufrida al ser afectada por una conducta de elevado nivel de reprochabilidad, marcada por la presencia de dolo o culpa grave. En paralelo, se concibe la respectiva indemnización como una multa civil, desdibujando las fronteras tradicionalmente establecidas entre pena e indemnización. Se sitúa en un marco garantista, enfocándose en la preservación de los derechos fundamentales tanto de la víctima como del ofensor. Esto resulta en la idealización de una forma de gestión civil del ilícito, por medio de una cláusula general de multa civil, creada bajo las fronteras establecidas por principios de protección típicos del Derecho Sancionador. Se destaca el presupuesto de legalidad para que se puedan elegir criterios pautados en el ofensor como base de cálculo para la indemnización, incluso cuando dicha sanción esté justificada por motivos estrictamente reparatorios. Finalmente, se plantea una propuesta de límites para la aplicación y cálculo de la multa civil.[PO] O objetivo central deste trabalho é analisar a compatibilidade jurídica entre a responsabilidade civil extracontratual e as funções punitiva e preventiva, em contraste com a teoria tradicional de caráter estritamente reparatório. A metodologia utilizada baseia-se em pesquisa bibliográfica, legislativa e jurisprudencial, buscando um equilíbrio entre teoria e prática, incluindo sistemas jurídicos escolhidos como exemplos das famílias da civil law e common law. O estudo começa com considerações sobre a Teoria Geral do Direito, passa pela história desde o Direito Romano e por noções da filosofia aristotélica, para introduzir uma reflexão crítica sobre o conceito de dano e as finalidades da Responsabilidade Civil, concluindo pelo potencial multifuncional da indenização, que permite calibrar a força sancionatória para alcançar diferentes objetivos, dependendo de cada ordenamento jurídico. Em seguida, é analisada a figura dos punitive damages e as formas de indenização punitiva adotadas por países de tradição inspirada na cláusula geral de responsabilidade civil inaugurada pelo Código Civil Francês de 1804. O tema é abordado criticamente com o auxílio das contribuições das teorias absolutas e relativas sobre a finalidade das penas, levando à conclusão de que indenizar, punir e prevenir não necessariamente possuem propósitos diferentes, pois se aproximam dependendo do marco teórico utilizado e das diferentes formas de compreender o fenômeno sancionatório. A função prescritiva da indenização se destaca como um porto seguro, capaz de representar a complexidade subjetiva da relação de responsabilidade, incluindo o direcionamento do comando normativo para os polos dessa relação. De um lado, tutela-se o dano sofrido pela vítima e, de outro, comunica-se ao ofensor o repúdio à sua conduta pelo ordenamento jurídico. Propõe-se a classificação da indenização com base no direcionamento dos critérios de cálculo para o ofensor e a vítima, denominando dano moral por conduta grave a violação do interesse existencial da vítima decorrente da reificação ilícita sofrida ao ser atingida por uma conduta de elevado nível de reprovação, marcada pela presença de dolo ou culpa grave. Paralelamente, pensa-se na respectiva indenização como uma multa civil, borrando as fronteiras tradicionalmente erigidas entre pena e indenização. O tema é situado no marco garantista, considerando a preservação dos direitos fundamentais da vítima e do ofensor, resultando na idealização de uma forma de gestão civil do ilícito, por meio de uma cláusula geral de multa civil, criada dentro dos limites estabelecidos por princípios de proteção típicos do Direito Sancionador, destacando-se o pressuposto da legalidade para que se possa escolher critérios pautados no ofensor como base de cálculo para a indenização, mesmo que essa sanção seja justificada por uma perspectiva estritamente reparatória. Por fim, é apresentada uma proposta de limites para a aplicação e cálculo da multa civil.[EN] The central objective of this work is to address the legal compatibility between civil liability and the punitive and preventive functions, in contrast to the traditional theory of strictly reparative nature. The methodology employed is based on a literature, legislative, and jurisprudential review, seeking to find a balance between theory and practice in the studies conducted, including selected legal systems as examples from the civil law and common law families. The study begins with notes on General Theory of Law, progresses through the history of Roman Law and concepts from Aristotelian philosophy, and introduces a critical reflection on the concept of damage and the purposes of civil liability. It concludes with the multifunctional potential of indemnification, which allows for the calibration of the sanctioning force to achieve different objectives, according to each legal system. Next, the concept of punitive damages is analyzed, along with the forms of punitive indemnification adopted by countries with a tradition inspired by the general clause of civil liability established by the French Civil Code of 1804. The object of study undergoes a critical analysis supported by contributions from absolute and relative theories regarding the purpose of penalties, concluding that compensating, punishing, and preventing do not necessarily have different purposes; rather, they converge depending on the theoretical framework utilized and the various ways of understanding the punitive phenomenon. The prescriptive function of indemnification emerges as a safe harbor, capable of representing the subjective complexity of the responsibility relationship, including the direction of the normative command toward the poles of that relationship. On one hand, it protects the damage suffered by the victim, and on the other, it informs the offender of the legal system's rejection of their conduct. A classification of indemnification is proposed based on the approach to the criteria for its calculation in relation to the offender and the victim. The violation of the existential interest of the victim resulting from the unlawful reification suffered when affected by conduct of a high degree of reproach, marked by the presence of intent or gross negligence, is designated as moral damage due to serious fault. In parallel, the respective indemnification is conceived as a civil fine, blurring the traditionally established boundaries between penalty and indemnification. This concept is situated within a guarantee framework, focused on preserving the fundamental rights of both the victim and the offender. This leads to the idealization of a form of civil management of the unlawful act, through a general clause of civil fine created under the limits established by protective principles typical of sanctioning law. Finally, a proposal is presented for limits on the application and calculation of the civil fine.Programa de Doctorado en Derecho por la Universidad Carlos III de MadridPresidenta: María Ángeles Parra Lucán.- Secretario: Bruno Leonardo Cámara Carrá.- Vocal: Rafael de Freitas Valle Dresc