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Electromagnetic vibration energy harvesting is a relatively new technology that transforms kinetic energy from mechanical vibrations into electrical energy, allowing the substitution of batteries or cables for powering ultra-low-power devices like wireless sensor networks for structural health monitoring. For this aim, different magnet and coil configurations have been proposed for the design of these harvesters by several researchers. In this paper, four cylindrical “Magnet in-line coil” configurations with back steel, which include a typical single-magnet, a double-magnet array, and two proposed cylindrical Halbach magnet arrays of three and five magnets, are analyzed using the finite element method and compared in terms of their magnetic flux linkage and transduction factor. The numerical simulations are conducted in all cases with the same materials properties, coil parameters, and geometrical boundaries, the latter consisting of the total cross-sectional area of the magnets and the coil, the air gaps, and the total volume of the transducer mechanism. Furthermore, the design that provides the best performance is analyzed with two different coil configurations. It is finally found that the proposed cylindrical Halbach magnet array with three magnets and one-center coil presents the best results, reaching an average transduction factor of 95.83 Vs/m and a normalized power density of 19.72 mW/cm3g2.

The environmental problems due to ground-borne vibrations induced by underground railway traffic are an issue of growing concern in urban areas as the demand for underground railway network has been increased. The demand gives rise to the construction of more tunnels, faster trains and use of innovative designs for tunnel structure. Double- deck tunnels are one of these designs in which tunnel is divided into two sections by an interior oor. The aim of this study is to assess the efficiency of dynamic vibration absorbers (DVAs) as vibration mit- igation measures for ground-borne vibrations induced by train pass-by in a double-deck tunnel. A previously developed semi-analytical model of a track-tunnel-ground system along with the two-dimensional multi- degree-of-freedom rigid body model of the vehicle is employed to compute the energy ow radiated upwards due to train pass-by. Considering the crucial role of DVAs parameters in their efficiency, a global optimization approach based on a genetic algorithm (GA) is used to obtain the op- timum parameters of DVAs. The performance of DVAs is assessed for two train speeds taking into account their efficiency in reducing the to- tal radiated energy from the tunnel. The results show more than 6 dB reduction in total radiated energy by the use of optimized DVAs This work has been carried out in the context of Industrial Doctorates Plan, with the financial support of AV Ingenieros and AGAUR from Generalitat de Catalunya. The authors would like to extend their gratitude to Universi- tat Politècnica de Catalunya (UPC) for its financial support. The second au- thor also wants to acknowledge the funds provided by the NVTRail project, with grant reference POCI-01-0145-FEDER-029577, funded by FEDER funds through COMPETE2020 (Programa Operacional Competitividade e Interna- cionalizaçao (POCI)) and by national funds (PIDDAC) through FCT/MCTES

This thesis studies the vibration pattern synthesis in structures using the Dynamic Mode Decomposition (DMD) method. This numerical model is used for one degree of freedom, to know the axial response, according to x. Firstly the effectiveness of the DMD method is evaluated and give good results to reconstruct the signal, applying to initial conditions of the structure's vibration to extract the shape and temporal characteristics of the DMD modes, which were then used to synthesize the desired vibration pattern in the structure. Next, QR factorization is used in order to find sensor placement. Results showed that the DMD method, combined with QR factorization, can effectively synthesize the desired vibration pattern in structures. However, conditions about spacing of the sensors is necessary to optimize the interpolation. Regarding further research, it’s needed to study the method's limitations and potential application in more complex systems or when dealing with high-frequency data. Incoming

En aquest treball es presenta una proposta d’implementació del manteniment preventiu. Aquest es basa en anàlisi de vibracions a les màquines més importants del procés productiu de la fàbrica Knauf de Guixers (Solsonès). Es defineixen les diferents eines que es disposa per tal de fer els anàlisis i la metodologia seguida per a un diagnòstic exitós. També es veuran les mesures preses més rellevants amb els seus diagnòstics i resultats reals que s’han anat obtenint. I finalment, es mostrarà la metodologia seguida per implementar l’anàlisi de vibracions i es detalla un pla de formació a un mecànic a càrrec de l’empresa. En este trabajo se presenta una propuesta de implementación del mantenimiento preventivo. Éste se basa en análisis de vibraciones en las máquinas más importantes del proceso productivo de la fábrica Knauf de Guixers (Solsonès). Se definen las diferentes herramientas que se dispone para realizar los análisis y la metodología seguida para un diagnóstico exitoso. También se verán las medidas tomadas más relevantes con sus diagnósticos y resultados reales que se han obtenido. Y, finalmente, se mostrará la metodología seguida para implementar el análisis de vibraciones y se detalla un plan de formación a un mecánico a cargo de la empresa. This work will see the implementation of preventive maintenance based on vibration analysis on the most important machines in the production process of the Knauf factory in Guixers (Solsonès). It defines the different tools available to perform the analysis and the methodology followed for a successful diagnosis. It could be seen the most relevant steps taken with your diagnoses and the actual results that have been obtained. And finally, it will show how to implement vibration analysis with training for a mechanic in charge of the company.

In this project the validity of an in-situ method to evaluate resilient elements is verified for systems with more than one connection. Potential advantages of this method would be testing elements under more realistic and representing conditions, as well as greater flexibility of the systems that can be evaluated. An introduction to the necessary theoretical formulation is given as well as an evaluation of the current state of the art. The theoretical formulation also includes a theoretical demonstration of the method for multiple connections. The method is validated using a combination of numerical models based on the Finite Element Method as well as different experiments conducted in a laboratory. The numerical models not only validate the hypothesis that the method can be applied to systems with multiple connections, but they are also used to study the effect of neglecting some of the degrees of freedom that describe these connections. The experimental case studies were divided in two parts, one with a single isolator to validate the laboratory setting used and a second one where multiple connections were considered. The results obtained for this second case were compared with those from the theoretical basis and the numerical models and this showed that they were erroneous. The comparison highlighted that these discrepancies can be attributed to the fact that some degrees of freedom of the system that were not initially measured may play an unexpectedly important role in this case study, and this led to the accumulation of error. The results show that this method is valid but it may be mainly applicable to cases where all the degrees of freedom of the system are known and can be measured. Future possible lines of research are included on the project and expand on the possibilities of both the numerical and the experimental methods to view how modifications to the system affect the results. En este proyecto la validez de un método in-situ para evaluar elementos aisladores es verificada para sistemas con más de una conexión. Las ventajas potenciales de este método serían poder evaluar elementos bajo condiciones más realistas y representativas, así como mayor flexibilidad en los tipos de sistema que pueden ser evaluados. Está incluida en el trabajo una introducción al marco teórico necesario, así como una evaluación del estado del arte actual. El marco teórico también incluye una demostración teórica del método para múltiples conexiones. El método ha sido validado usando una combinación de modelos numéricos basados en el método de elementos finitos y experimentos realizados en un laboratorio. Los modelos numéricos no solo validan la hipótesis de que el método se puede aplicar a sistemas con múltiples conexiones, sino que también se usan para estudiar el efecto de ignorar algunos de los grados de libertad que describen las conexiones. Los casos de estudio experimentales fueron separados en dos partes, la primera con un elemento aislante para evaluar la configuración del laboratorio y una segunda parte donde se utilizaron múltiples conexiones. Los resultados conseguidos en ese segundo caso fueron comparados con aquellos de la base teórica y los modelos numéricos y se observó que eran erróneos. La comparación resaltó que esas discrepancias podían ser atribuidas al hecho de que algunos grados de libertad dedl sistema que no habían sido medidos en un principio podían tener un rol más importante de lo esperado en este caso de estudio y eso llevó a una acumulación del error. Los resultados generales muestran que el método es válido pero podría ser solo aplicable a casos en los cuales todos los grados de libertad del sistema son conocidos y pueden ser medidos. The results show that this method is valid but it may be mainly applicable to cases where all the degrees of freedom of the system are known and can be measured. Algunas posibles líneas de investigación futuras son incluidas en el trabajo y expanden las posibilidades de los métodos numéricos y experimentales para ver como modificaciones en el sistema pueden afectar los resultados.

Una de las principales preocupaciones de las empresas encargadas de diseñar elementos para vehículos es que sus componentes resistan condiciones extremas como vibraciones y choques sin romper o dejar de funcionar para validar su fiabilidad. Por ese motivo, se solicitan todo tipo de ensayos, como por ejemplo el test de vibración. Los ensayos de vibración, muy solicitados en todos los ámbitos, tienen la particularidad que requieren un utillaje para conectar pieza y mesa vibratoria para poder efectuar el ensayo con éxito. El siguiente estudio pretende optimizar el diseño de un utillaje óptimo partiendo de un ensayo de vibración ya realizado. El diseño se desarrolla con un modelo numérico y su validación mediante un análisis modal experimental. La optimización se centra en evitar resonancias en el rango de frecuencias de interés. Este proceso permite determinar cómo se tendría que haber mecanizado dicho utillaje y aprovechar dicha información en ensayos futuros.