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Design and control of a bidirectional multiport DC-DC converter for bipolar DC microgrids with integrated PV and battery interface
No full text© 2025 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The bipolar DC microgrid (BDCMG) has gained increasing relevance with the widespread adoption of DC sources and loads, primarily due to its higher efficiency, reliability, and flexibility. However, multiport DC–DC converters for interfacing multiple sources with BDCMG still face significant challenges, including voltage balancing, bidirectional power exchange capability, and source requirements. To overcome these challenges, this paper presents a new four-port DC-DC converter for interfacing PV and battery to low-voltage BDCMG. The proposed converter allows fully independent bidirectional power flow among all four ports, enabling flexible power management between the BDCMG, PV, and battery. Owing to its completely independent output poles, the converter inherently compensates for voltage imbalance, even in the absence of PV generation. A robust control strategy is implemented to ensure stable and efficient operation over a wide range of conditions. The proposed design is verified through detailed simulation and experimental validation using a 2 × 600 W laboratory prototype. The main advantages of the proposed solution include: (a) inherent voltage balancing, (b) bidirectional power flow capability, (c) high performance and robust control across a wide operating range, (d) suitable voltage gain, low component stress, and minimal component count, (e) simple voltage and current control across all ports, (f) MPPT support, (g) battery charging control, and (h) continuous current interfaces for both the PV and battery ports.Peer ReviewedPostprint (author's final draft
De l’espai a la terra: Explora l’EETAC i l’EEABB a les Jornades de Portes Obertes
No full textL’Escola d’Enginyeria de Telecomunicació i Aeroespacial és el bressol dels futurs enginyers de l’espai i la comunicació global. L’Escola d’Enginyeria Agroalimentària i de Biosistemes millora la producció d’aliments, gestiona l’aigua i protegeix la biodiversita
Parametrització de la precarietat edificada : una metodologia per descriure les limitacions latents del parc edificat
No full textAquest Treball de Fi de Grau analitza la situació del parc edificat existent en un context marcat per la crisi d’accés a l’habitatge i per l’augment progressiu de les exigències europees en matèria d’eficiència energètica. Tot i que aquestes regulacions tenen com a objectiu la descarbonització del parc immobiliari, la seva aplicació pot comportar una pressió addicional sobre un parc edificat envellit, amb mancances constructives i energètiques acumulades que sovint no són visibles en el moment de l’adquisició de l’habitatge. En aquest escenari, la dificultat d’accés a l’habitatge no depèn només del seu preu de mercat, sinó també de les inversions futures necessàries per adequar-lo a les noves exigències normatives. Aquestes mancances no es limiten al comportament energètic, sinó que inclouen també condicionants derivats dels sistemes constructius, de l’antiguitat dels materials i de possibles patologies associades al seu envelliment. Davant d’aquesta realitat, el treball proposa una parametrització de la precarietat edificada com a eina de lectura tècnica, orientada a fer visibles aquestes limitacions latents sense traduir-les en una valoració econòmica ni en una diagnosi exhaustiva. La metodologia es concreta en el desenvolupament d’un full de càlcul basat en criteris arquitectònics observables, estructurats en tres blocs d’anàlisi: la configuració constructiva, la protecció contra les pèrdues energètiques i la configuració del sistema energètic. Aquesta eina permet oferir una lectura sintètica i comparativa del parc edificat, contribuint a una comprensió més informada dels reptes que afronta l’habitatge en el context actual.Este Trabajo de Fin de Grado analiza la situación del parque edificado existente en un contexto marcado por la crisis de acceso a la vivienda y por el aumento progresivo de las exigencias europeas en materia de eficiencia energética. Aunque estas regulaciones tienen como objetivo la descarbonización del parque inmobiliario, su aplicación puede suponer una presión adicional sobre un parque edificado envejecido, con carencias constructivas y energéticas acumuladas que a menudo no son visibles en el momento de la adquisición de la vivienda. En este escenario, la dificultad de acceso a la vivienda no depende únicamente de su precio de mercado, sino también de las inversiones futuras necesarias para adaptarla a las nuevas exigencias normativas. Estas carencias no se limitan al comportamiento energético, sino que incluyen también condicionantes derivados de los sistemas constructivos, de la antigüedad de los materiales y de posibles patologías asociadas a su envejecimiento. Ante esta realidad, el trabajo propone una parametrización de la precariedad edificada como herramienta de lectura técnica, orientada a hacer visibles estas limitaciones latentes sin traducirlas en una valoración económica ni en un diagnóstico exhaustivo. La metodología se concreta en el desarrollo de una hoja de cálculo basada en criterios arquitectónicos observables, estructurados en tres bloques de análisis: la configuración constructiva, la protección frente a las pérdidas energéticas y la configuración del sistema energético. Esta herramienta permite ofrecer una lectura sintética y comparativa del parque edificado, contribuyendo a una comprensión más informada de los retos a los que se enfrenta la vivienda en el contexto actual.This Final Degree Project analyzes the condition of the existing building stock within a context shaped by the housing access crisis and the progressive tightening of European energy efficiency requirements. Although these regulations aim to decarbonize the real estate sector, their implementation may place additional pressure on an aging building stock, characterized by accumulated constructive and energy-related deficiencies that are often not visible at the time of housing acquisition. In this context, difficulties in accessing housing are not determined solely by market price, but also by the future investments required to adapt dwellings to new regulatory demands. These shortcomings are not limited to energy performance, but also include constraints related to construction systems, material aging, and potential pathologies associated with long-term deterioration. In response to this situation, the project proposes a parametrization of built precariousness as a technical reading tool, aimed at making these latent limitations visible without translating them into an economic valuation or an exhaustive diagnostic. The methodology is implemented through the development of a spreadsheet based on observable architectural criteria, structured into three analytical blocks: constructive configuration, protection against energy losses, and energy system configuration. This tool provides a synthetic and comparative reading of the building stock, contributing to a more informed understanding of the challenges currently facing housing
Nonlinear projection-based model order reduction with machine learning regression for closure error modeling in the latent space
No full textA significant advancement in nonlinear projection-based model order reduction (PMOR) is presented through a highly effective methodology. This methodology employs Gaussian process regression (GPR) and radial basis function (RBF) interpolation for closure error modeling in the latent space, offering notable gains in efficiency and expanding the scope of PMOR. Moving beyond the limitations of deep artificial neural networks (ANNs), previously used for this task, this approach provides crucial advantages in terms of interpretability and a reduced demand for extensive training data. The capabilities of GPR and RBFs are showcased in two demanding applications: a two-dimensional parametric inviscid Burgers problem, featuring propagating shocks across the entire computational domain, and a complex three-dimensional turbulent flow simulation around an Ahmed body. The results demonstrate that this innovative approach preserves accuracy and achieves substantial improvements in efficiency and interpretability when contrasted with traditional PMOR and ANN-based closure modeling.Charbel Farhat and Radek Tezaur acknowledge partial support by the Office of Naval Research under Grant N00014-23-1-2877 and Grant N00014-23-1-2413; and partial support by the Air Force Office of Scientific Research under Grant FA9550-22-1-0004 and Grant FA9550-20-1-0358. Sebastian Ares de Parga acknowledges partial support by the Departament de Recerca i Universitats de la Generalitat de Catalunya under Grant FI-SDUR 2021; partial support by the Fulbright Commission Spain through a Fulbright Predoctoral Research Fellowship (2024–2025); and partial support by the Department of Aeronautics and Astronautics at Stanford University.Peer ReviewedPostprint (published version
PGD-based local surrogate models via overlapping domain decomposition: A computational comparison
No full textAn efficient strategy to construct physics-based local surrogate models for parametric linear elliptic problems is presented. The method relies on proper generalized decomposition (PGD) to reduce the dimensionality of the problem and on an overlapping domain decomposition (DD) strategy to decouple the spatial degrees of freedom. In the offline phase, the local surrogate model is computed in a non-intrusive way, exploiting the linearity of the operator and imposing arbitrary Dirichlet conditions, independently at each node of the interface, by means of the traces of the finite element functions employed for the discretization inside the subdomain. This leads to parametric subproblems with reduced dimensionality, significantly decreasing the complexity of the involved computations and achieving speed-ups up to 100 times with respect to a previously proposed DD-PGD algorithm that required clustering the interface nodes. A fully algebraic alternating Schwarz method is then formulated to couple the subdomains in the online phase, leveraging the real-time (less than half a second) evaluation capabilities of the computed local surrogate models, that do not require the solution of any additional low-dimensional problems. A computational comparison of different PGD-based local surrogate models is presented using a set of numerical benchmarks to showcase the superior performance of the proposed methodology, both in the offline and in the online phase.The authors acknowledge funding as follows. MD: EPSRC grant EP/V027603/1. BJE: EPSRC Doctoral Training Partner-ship grant EP/W523987/1. MG: Spanish Ministry of Science, Innovation and Universities and Spanish State Research Agency MICIU/AEI/10.13039/501100011033 (Grant No. PID2023-149979OB-I00); Generalitat de Catalunya, Spain (Grant No. 2021-SGR-01049); MG is Fellow of the Serra Húnter Programme of the Generalitat de Catalunya.Peer ReviewedPostprint (published version
Guia temàtica Biblioteca ETSAB: Ciutats per a la gent: el dret a la ciutat
No full textSelecció de documents que fan referència a una nova forma de construir ciutats on la gent sigui la seva màxima protagonista: ciutats amables, pensades per als vianants, segures, d’acollida, creatives, inclusives... Ciutats per a tots on la gent aprofiti i frueixi del seu entorn i els espais públics de la ciutat.Postprint (author's final draft
Influencia de parámetros de cultivo en la formación de esferas de celulosa bacteriana
No full textLa celulosa bacteriana (CB) es un biomaterial que está siendo ampliamente estudiado por sus propiedades, que, lo hacen afín para una gran variedad de aplicaciones, entre las cuales se encuentran el tratamiento de aguas residuales, biomédicas, empaquetamiento alimenticio, entre otros. En este trabajo, se evaluaron diferentes parámetros (RPM y nivel de llenado) de crecimiento de celulosa bacteriana para la obtención controlada de diferentes tamaños de esferas de CB. Se encontró que las variables analizadas y su interacción tienen un efecto significativo en la producción de esferas, siendo el nivel de llenado la variable que más influye en los resultados. Adicionalmente, se obtuvo un modelo valido para la predicción del tamaño de las esfera
Electrocaloric and energy storage properties of barium stannate titanate system: A multifunctional approach
No full textThe multifunctional behavior of BaTi1–xSnxO3 ceramics was systematically investigated within the compositional range 0.09 = x = 0.20, focusing on their potential for energy-related applications. Structural and dielectric studies revealed a gradual suppression of long-range ferroelectric order and the emergence of diffuse, multiphase regimes with increasing Sn substitution. This compositional evolution strongly influenced the electrical response, leading to slim polarization loops and enhanced functional properties. Notably, the composition with x = 0.15 exhibited a recoverable energy-storage density of approximately 45 mJ/cm3 with an efficiency of around 77 %, whereas the strongest electrocaloric response was observed for x = 0.09, yielding an electrocaloric strength of about 0.40 K mm/kV near room temperature. These results highlight the critical role of phase coexistence and relaxor-like behavior in tailoring the multifunctionality of BaTi1–xSnxO3, positioning this system as a promising lead-free platform for capacitive energy storage and solid-state cooling technologies.The authors thank the National Council of Scientific and Technological Development (CNPq) grants 309494/2022-2 and 408662/2023-9, Minas Gerais Research Foundation (FAPEMIG) grants PPM-00661-16 and APQ-02875-18, MCTI/FINEP/FNDCT (grant 0966/24 #01.25.0086.00) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 for financial support. M.V. and J.E.G. acknowledge financial support from grant #2024/14882-0, São Paulo Research Foundation (FAPESP).Peer ReviewedPostprint (published version
Optimización para el cambio de material de una llanta de vehículo pesado
No full textThis work studies the potential of ultra-high-strength steel for the manufacturing of
wheels in the heavy transport sector, aiming to find a competitive alternative that
improves operational efficiency and reduces vehicle mass. The study considers
USIBOR®1500 press-hardened steel as a means to enhance the performance of
conventional wheels.
The geometric design of the wheel was defined based on strict mechanical and
regulatory requirements. Lightweighting objectives were established to allow these
steels to compete in weight with aluminum alloys and conventional Dual Phase steels,
without compromising the load capacity required for commercial transport. The study
strictly follows international testing standards, such as ISO 6892-1 for tensile
characterization and SAE J267 for radial and rotary fatigue testing procedures.
Subsequently, numerical simulations were performed in ANSYS®, where models were
adjusted using S-N curves and mechanical properties to accurately reflect the
component's service life. The tests were simulated with the highest possible fidelity to
real-world conditions. The results demonstrate that while DP600 fails critically with a
crown thickness of 4 mm, USIBOR®1500 not only withstands this reduction but also
allows for an optimization of the disc thickness from 7.5 mm to just 5 mm.
Consequently, the proposed design guarantees infinite life (107 cycles) by operating
within the material's elastic limits.
Finally, a comparative analysis of costs and operational benefits was conducted. The
total mass reduction of 34.48% (from 44 kg to 28.83 kg) offsets the higher unit cost of
USIBOR®1500. This optimization increases payload capacity and reduces fuel
consumption, validating the use of ultra-high-strength steels as an efficient and
sustainable solution for the transport industry.Este trabajo estudia el potencial de un acero de ultra-alta resistencia mecánica para
la fabricación de llantas para el sector del transporte pesado, con el objetivo de
encontrar una alternativa competitiva que mejore la eficiencia operativa y reduzca la
masa del vehículo. El estudio considera el acero endurecible por prensa
USIBOR®1500 para mejorar las prestaciones de las llantas convencionales.
Se ha procedido a definir el diseño geométrico de la llanta en base a requisitos
mecánicos y normativos estrictos. Se han definido objetivos de aligeramiento que
permitan a estos aceros competir en peso con las aleaciones de aluminio y los aceros
habituales de tipo Dual Phase, sin comprometer la capacidad de carga necesaria para
el transporte comercial. El estudio sigue en todo momento los estándares
internacionales de ensayo, tales como la ISO 6892-1 para la caracterización de la
tracción y la SAE J267 para los procedimientos de ensayo de fatiga radial y de
rotación.
Más tarde, se ha realizado la simulación numérica en ANSYS®, se ha ajustado los
modelos mediante curvas S-N y propiedades mecánicas para reflejar la vida útil del
componente y se han simulado los ensayos de la forma más fidedigna posible. Los
resultados demuestran que, mientras el DP600 falla críticamente con un espesor de
corona de 4 mm, el USIBOR®1500 no solo soporta dicha reducción, sino que permite
optimizar el espesor del disco de 7,5 mm a solo 5 mm. Gracias a esto, el diseño
propuesto garantiza vida infinita (107 ciclos) operando dentro de los límites elásticos
del material.
Finalmente, se ha realizado una comparativa de costes y beneficios operativos. La
reducción de masa total del 34,48% (de 44 kg a 28,83 kg) compensa el mayor coste
unitario del USIBOR®1500. Esta optimización incrementa la carga útil y reduce el
consumo de combustible, validando el uso de aceros de ultra-alta resistencia como
una solución eficiente para la sostenibilidad en el transporte
The cosymplectic Chern–Hamilton conjecture
No full textIn this paper, we study the Chern–Hamilton energy functional on compact cosymplectic manifolds, fully classifying in dimension 3 those manifolds admitting a critical compatible metric for this functional. This is the case if and only if either the manifold is co-Kähler or if it is a mapping torus of the 2-torus by a hyperbolic toral automorphism and equipped with a suspension cosymplectic structure. Moreover, any critical metric has minimal energy among all compatible metrics. We also exhibit examples of manifolds with first Betti number admitting cosymplectic structures, but such that no cosymplectic structure admits a critical compatible metric.S. Dyhr received the support of a fellowship from the “la Caixa” Foundation (ID 100010434) with fellowship code LCF/BQ/DI23/11990085. Á. González-Prieto is supported by the Spanish State Research Agency projects PID2021-124440NB-I00 and PID2024-156578NB-I00. E. Miranda is supported by the Catalan Institution for Research and Advanced Studies via an ICREA Academia Prize 2021. D. Peralta-Salas is supported by the grants RED2022-134301-T and PID2022-136795NB-I00 funded by MCIN/AEI/10.13039/501100011033. S. Dyhr and E. Miranda are supported by the Spanish State Research Agency project PID2023-146936NB-I00 funded by MICIU/AEI/10.13039/501100011033. Á. González-Prieto and D. Peralta-Salas are supported by the project CEX2023-001347-S. The last three authors are supported by the Bilateral AEI-DFG project: Celestial Mechanics, Hydrodynamics, and Turing Machines with reference codes PCI2024-155042-2 and PCI2024-155062-2. All authors are partially supported by the project EIC2-1-172 ‘Computational, dynamical and geometrical complexity in fluid dynamics’ (COMPLEXFLUIDS), Ayudas Fundación BBVA a Proyectos de Investigación Científica 2021. This work is supported by the Spanish State Research Agency, through the Severo Ochoa and María de Maeztu Program for Centers and Units of Excellence in R&D (CEX2020-001084-M). We thank CERCA Programme/Generalitat de Catalunya for institutional support.Peer ReviewedPostprint (published version