Portal del coneixement obert de la UPC

Enviaments recents

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  Comunicació de congrés Accés obert

  Beyond diagonal RIS-assisted MIMO transmission: beamforming gain and capacity optimization

  (2026) Moreno Locubiche, Ainna Yue; Vidal Manzano, José; Universitat Politècnica de Catalunya. SPCOM - Processament del Senyal i Comunicacions; Universitat Politècnica de Catalunya. Doctorat en Teoria del Senyal i Comunicacions; Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions

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  Reconfigurable Intelligent Surfaces (RIS) have emerged as a transformative technology in wireless communications, offering unprecedented control over signal propagation. This study focuses on passive beyond diagonal reconfigurable intelligent surface (BD-RIS), which has been proposed to generalize conventional diagonal RIS, in Multiple-Input Multiple-Output (MIMO) downlink (DL) communication systems. We compare the performance of transmit beamforming (TxBF) and MIMO capacity transmission with waterfilling power allocation in the millimeter wave (mmWave) band, where propagation primarily occurs under line-of-sight (LOS) conditions. In the lack of closedform expressions for the optimal RIS elements in either case, our approach adopts a gradient-based optimization approach requiring lower complexity than the solution in [1]. Numerical results reveal that BD-RIS significantly outperforms traditional diagonal RIS in terms of spectral efficiency and coverage.

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  Article Accés obert

  Encoding a topological gauge theory on a ring-shaped Raman-coupled Bose gas

  (2026-06-03) Iacovelli, Claudio; Cabedo, Josep; Tarruell, Leticia; Celi, Alessio

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  Topological gauge theories constitute a framework for understanding strongly correlated quantum matter in terms of weakly interacting composite degrees of freedom. Their topological properties become evident when these theories are realized on a space of nontrivial topology. Here, we propose a scheme to realize a one-dimensional topological gauge theory, the so-called chiral BF theory, on a ring geometry. We obtain such a theory by dimensionally reducing Chern-Simons theory on a disk to the chiral BF theory defined on the ring. Then, we encode the theory into a Hamiltonian with a coupling between angular momentum and density, and we propose and numerically benchmark its realization in an optically dressed Bose gas confined in a ring-shaped trap. There, the topological properties of the underlying theory manifest themselves through a magnetic flux variable that is density dependent. We quantify such density-dependent magnetic flux in terms of the ground-state angular momentum and the chiral properties of the system through a Bogoliubov analysis. Our proposal enables the observation of topological features of the chiral BF theory that become manifest due to the nontrivial topology of the ring geometry.

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  Projecte Final de Màster Oficial Accés obert

  Feasibility study on low-cost transatlantic airline operations: comparing large-hub and small primary airports

  (Universitat Politècnica de Catalunya, 2026-07-08) Sopena López, Sara; Universitat Politècnica de Catalunya. Departament d'Enginyeria de Projectes i de la Construcció

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  Este Trabajo Fin de Máster analiza la viabilidad de establecer una ruta aérea transatlántica de bajo coste entre el Aeropuerto Josep Tarradellas Barcelona–El Prat (BCN) y la región de Florida Central, comparando dos posibles aeropuertos de destino: Melbourne Orlando International Airport (MLB) y Orlando International Airport (MCO). El objetivo principal es determinar cuál de los dos aeropuertos ofrece mayores ventajas estratégicas, operativas y económicas para la aerolínea LEVEL en el desarrollo de una nueva ruta de largo recorrido. La metodología se estructura en cinco áreas principales: análisis de demanda y previsión de tráfico, evaluación de la infraestructura aeroportuaria, análisis de viabilidad financiera, revisión del entorno regulatorio y de incentivos, y evaluación estratégica mediante matrices de decisión. Para ello se utilizaron datos públicos de la Federal Aviation Administration (FAA), estadísticas aeroportuarias, indicadores socioeconómicos, encuestas a potenciales pasajeros y modelos de análisis financiero. Los resultados muestran que MCO dispone de una demanda potencial significativamente mayor, una red internacional consolidada y una infraestructura aeroportuaria superior. Sin embargo, MLB presenta ventajas relevantes para el modelo low-cost long-haul debido a sus menores costes operativos, menores tasas aeroportuarias, menores niveles de congestión y una mayor accesibilidad a programas de financiación e incentivos para el desarrollo de nuevas rutas. El análisis financiero indica que MLB presenta menores costes por operación y un umbral de rentabilidad más favorable, mientras que MCO requiere mayores niveles de ocupación para alcanzar la rentabilidad. La evaluación integrada de los factores de demanda, infraestructura, viabilidad financiera y entorno regulatorio concluye que ambos aeropuertos son técnicamente capaces de soportar una operación transatlántica. No obstante, MLB ofrece una mejor alineación estratégica con el modelo de negocio de bajo coste de LEVEL, especialmente durante las fases iniciales de implantación de la ruta. Aunque MCO podría facilitar mayores niveles de ocupación gracias a su mercado más amplio, MLB proporciona una combinación más equilibrada de costes reducidos, eficiencia operativa y potencial de crecimiento, convirtiéndose en la alternativa recomendada para el desarrollo de la nueva conexión entre Barcelona y Florida Central.

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  Article Accés obert

  Relationships between airport centrality and delays in the European air network

  (Omnia Science, 2026-06) Rodrigues, Tiago; Silva, Jorge; Brito, Eliane

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  Purpose: This study investigates the relationship between the centrality of airports in the European air network and the levels of recorded delays. Design/methodology/approach: This investigation employs a case study of the European air transport network, selecting eight European airports, over the period between 2022 and 2024. Based on official traffic and delay data, adjacency matrices and lists are constructed, and macros are developed to automate data extraction and organization. A new Weighted Betweenness Centrality formula is proposed, specifically adapted to the characteristics of air networks, and punctuality data is aggregated into monthly indicators of average delay and standard deviation for each airport. Findings: The results show that large hubs maintain high Weighted Betweenness Centrality values over time, in line with their structural role in the network. Periods with high delays and peaks of variability are revealed, with frequent parallel evolution between average delay and standard deviation. It is suggested that increased centrality, as a rule, does not necessarily imply a proportional increase in delays, although in airports such as Barcelona (BCN) and Rome (FCO) a clearer trend of increasing average delay and standard deviation with centrality is observed. Research limitations/implications: The time frame, 2022-2024, was defined based on available data, coinciding with the period of progressive recovery of the European air network in the post Covid-19 pandemic period. Originality/value: The developed macros, the proposed Weighted Betweenness Centrality formula, and the aggregation of punctuality data into monthly indicators of average delay and standard deviation for each airport, allow us to draw conclusions about the relationships between these variables.

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  Examen Accés restringit a la comunitat UPC

  Final exam

  (Universitat Politècnica de Catalunya, 2026-01-09)

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