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Bloque IV: Fundamentos de dinámica de estructuras y análisis sísmico de edificios
No full text2025/20261r quadrimestr
Autonomous mobile low-cost sensor node for high-resolution noise sampling in urban environments
No full textThis paper outlines algorithm-level optimizations that allow a low-cost Mobile Acoustic Sensor Node (MASN) to achieve fully autonomous, continuous noise monitoring using hybrid solar and vibration energy harvesting. The core of this work is the algorithm-level optimization of signal processing, data transmission, and positioning tasks, combined with the efficient integration of hardware low-power modes. These optimizations were quantitatively evaluated and compared with non-optimized references and sensors from existing literature. The signal processing enhancements, specifically the computation of acoustic indicators via Power Spectral Density, resulted in a 61.4% power reduction while maintaining theoretical compliance with IEC standards (61672-1:2013, 61260-1:2014). Furthermore, a comparative analysis with a Class 1 Sound Level Meter experimentally validated the accuracy of the results. For the positioning task, a server-side interpolation procedure reduced power consumption and data volume by enabling longer update periods. Compared to 1-s sampling, extending the positioning period to 16 s reduced power consumption by 81.7%, resulting in an average positioning error of about 4.7 m. Finally, for the transmission task, the combination of data coding and delta compression yielded a 76.5% reduction in the required data payload compared to an ASCII representation. The cumulative effect of these algorithmic optimizations resulted in a total power consumption of 23.5 mW, enabling the node to operate fully autonomously with an optimal data transmission periodicity of approximately three minutesThis research was funded by the State Research Agency (Agencia Estatal de Investigación) through the project “Mobile Acoustic Sensor network for Automatic NOise Mapping” (MASANOM, Ref. PID2022-141702OB-I00). Additional support was provided by ACCIÓ (Agència per a la Competitivitat de l’Empresa) under the “CLOUD NOISE” project (Ref. ACE120/24/000090)Postprint (published version
OPTIMITZACIÓ I SIMULACIÓ (Examen final 1r quadrimestre)
No full textProblemesResolved2025/20261r quadrimestr
Creación de un gemelo digital para tareas de optimización del seakeeping de embarcaciones mediante la predicción del estado del mar usando sensores y simulaciones
No full textThis thesis addresses the inverse problem of estimating the directional sea state from ship motion responses obtained by physical manners, a critical capability for performance monitoring and operational decision support in marine vessels. The core challenge lies in reconstructing the wave spectrum, which is a continuos directional function, from a limited set of noisy motion measurements, a challenging problem in which one has to be very accurate not to commit any mistakes that spoils the reconstruction process itself
Comparative analysis of ultra-low-power PPM demodulation algorithms applied to underwater biotelemetry systems’ bidirectional acoustic tags
No full textIn this article, a comparative analysis of pulse position modulation demodulation algorithms tailored for ultra-low-power applications is presented, specifically in the context of bidirectional acoustic tags developed to improve marine biotelemetry data acquisition. Various algorithms and techniques were evaluated, with the three most theoretically efficient methods tested using a simplified acoustic transmission model and validated against qualitative field data. The two algorithms demonstrating the highest detection performance were subsequently implemented on a bidirectional acoustic tag prototype, where power measurements were conducted to identify the method offering the optimal balance between signal detectability and energy consumption. The results show that the Göertzel algorithm achieves detection performance equivalent to the FFT-based approach while offering significantly improved energy efficiency, operating at a reduced microcontroller clock frequency of 16 MHz, compared to the 24 MHz required by the FFT implementation.This work was supported in part by Spanish Ministerio de Ciencia, Innovación y Universidades (BITER-ECO, BITER-LANDER, and
BITER-AUV) under Grant PID2020-114732RBC31, Grant PID2020-114732RBC32, and Grant PID2020-114732RBC33; in part by the
Generalitat de Catalunya’s ‘‘SARTI-MAR’’ under Grant 2021 SGR 00259; in part by the Secretaria d’Universitats i Recerca del
Departament d’Empresa i Coneixement de la Generalitat de Catalunya, on FI-SDUR under Grant BDNS 612831 (GB); in part by Spanish National Program Ramón y Cajal under Grant RYC2022-038056-I (IM); and in part by the Severo Ochoa Centre of Excellence
Accreditation funded by AEI 10.13039/501100011033 under Grant CEX2024-001494-S.Peer ReviewedPostprint (published version
ECONOMIA I EMPRESA (Examen final 1r quadrimestre)
No full textTest, preguntes curtes i problemesResolved2025/20261r quadrimestr
Comment on “Effects of nanobubble on physical properties of water: A coarse-grained molecular dynamics analysis” by Yuhang Du, Fanqi Pei, Zhi Wen, and Guofeng Lou [J. Mol. Liq. 437 (2025) 128445]
No full textIn the referenced article the authors employ a coarse-grained molecular dynamics approach to explore the influence of nanobubbles on the viscosity and surface tension of water. Surface tension is computed via the pressure-tensor method, and the simulations indicate that nanobubbles systematically reduce the surface-tension coefficient. A linear empirical correlation is proposed for the ratio ¿/¿f,where¿ is the surface tension of nanobubble water and ¿f that of pure water under identical conditions. However, this linear relation is calibrated only within T ¿ [300,350] K, despite the pressure coefficients spanning up to 100 bar, where liquid water remains stable at temperatures significantly above 350 K. A direct extension of the linear form leads to unphysical predictions outside the calibration interval.In this Comment, by linking the molecular-dynamics results of Du et al. with classical interfacial thermodynamics-originating in Gibbs’ adsorption theory and later strengthened by Frenkel’s molecular-kinetic framework- it is demonstrated that the temperature dependence of ¿/¿f should follow an exponential attenuation law. This form naturally reduces to the authors’ linear correlation via a first-order expansion, while remaining physically consistent at higher temperatures. Moreover, the resulting model predicts a molecular Gibbs free energy in excellent agreement with independent values reported in the literature, thus lending further confidence to the MD simulations of Du et al.Postprint (author's final draft
