Research of the acoustic phenomenon produced by isolated scatterers and its applicability as a noise reducing device in transport infrastructures. Search for an optimised and sustainable design.

Tesis por compendio[ES] El control de ruido ambiental es una preocupación de primera magnitud para las sociedades avanzadas, debido a los problemas derivados que ocasionan en la salud de los ciudadanos. Una de las soluciones más extendidas para el control del ruido en su fase de transmisión en la utilización de pantallas acústicas. La aparición de nuevos materiales formados por redes de dispersores acústicos aislados, denominados cristales de sonido, está revolucionando el campo del apantallamiento acústico, posibilitando el avance tecnológico de esta área. Así, en los últimos años, las pantallas acústicas basadas en cristales de sonido se han posicionado como una alternativa viable a las pantallas acústicas tradicionales, puesto que ofrecen múltiples ventajas frente a las soluciones actuales. En el presente trabajo se muestra primeramente una recopilación de los avances realizados en el campo del apantallamiento acústico mediante esta tipología de pantallas. No obstante, aún existen líneas de investigación abiertas en esta área, que es necesario abordar para conseguir el objetivo de aplicar esta tecnología como atenuadores de sonido en las infraestructuras de transporte. Durante el periodo de formación de la doctoranda, se ha trabajado en algunas de las líneas de investigación activas en este campo del apantallamiento acústico. Una de estas investigaciones condujo al descubrimiento de interferencias entre los efectos de la resonancia y la dispersión múltiple de los cristales de sonido cuando estos efectos se producen en rangos de frecuencia cercanos. También hemos diseñado un nuevo dispositivo de reducción de ruido basado en cristales de sonido, utilizando herramientas de optimización multiobjetivo, que permitan apantallar y reflejar de forma difusa el ruido. El empleo de esta nueva herramienta de diseño identificó la necesidad de realizar un estudio comparativo de los métodos de simulación más utilizados para estimar el rendimiento de los dispositivos basados en cristales de sonido. Por último, hemos realizado un estudio psicoacústico para determinar la percepción de la reducción de molestia que proporcionan las pantallas acústicas basadas en cristales sonido y las barreras tradicionales, determinando si los parámetros objetivos que evalúan su rendimiento coinciden con la respuesta subjetiva de los usuarios.[CA] El control de soroll ambiental és una preocupació de primera magnitud per a les societats avançades, a causa dels problemes derivats que ocasionen en la salut dels ciutadans. Una de les solucions més esteses per al control del soroll en la seua fase de transmissió en la utilització de pantalles acústiques. L'aparició de nous materials formats per xarxes de dispersors acústics aïllats, denominats cristals de so, està revolucionant el camp de l'apantallament acústic, possibilitant l'avanç tecnològic d'esta àrea. Així, en els últims anys, les pantalles acústiques basades en cristals de so s'han posicionat com una alternativa viable a les pantalles acústiques tradicionals, ja que oferixen múltiples avantatges enfront de les solucions actuals. En el present treball es mostra primerament una recopilació dels avanços realitzats en el camp de l'apantallament acústic per mitjà d'esta tipologia de pantalles. No obstant això, encara hi ha línies d'investigació obertes en esta àrea, que és necessari abordar per a aconseguir l'objectiu d'aplicar esta tecnologia com a atenuadors de so en les infraestructures de transport. Durant el període de formació de la doctoranda, s'ha treballat en algunes de les línies d'investigació actives en este camp de l'apantallament acústic. Una d'estes investigacions va conduir al descobriment d'interferències entre els efectes de la ressonància i la dispersió múltiple dels cristals de so quan estos efectes es produïxen en rangs de freqüència pròxims. També hem dissenyat un nou dispositiu de reducció de soroll basat en cristals de so, utilitzant ferramentes d'optimització multiobjectiu, que permeten apantallar i reflectir de forma difusa el soroll. L'ús d'esta nova ferramenta de disseny va identificar la necessitat de realitzar un estudi comparatiu dels mètodes de simulació més utilitzats per a estimar el rendiment dels dispositius basats en cristals de so. Finalment, hem realitzat un estudi psicoacústic per a determinar la percepció de la reducció de molèstia que proporcionen les pantalles acústiques basades en cristals so i les barreres tradicionals, determinant si els paràmetres objectius que avaluen el seu rendiment coincidixen amb la resposta subjectiva dels usuaris.[EN] Control of environmental noise is a major concern for advanced societies because of the resulting problems for citizens' health. One of the most widespread solutions for controlling noise in its transmission phase is the use of acoustic screens. The emergence of new materials made up of arrays of isolated acoustic scatterers, called sonic crystals, is revolutionizing the field of acoustic screening. In recent years, acoustic screens based on sonic crystals have positioned themselves as a viable alternative to traditional acoustic screens, as they offer multiple advantages over current traditional solutions. This Doctoral dissertation compiles the advances in the field of acoustic screening using this type of sonic crystals. However, there is still active research in this area which needs to be addressed and studied in order to apply this technology as noise reduction devices in transport infrastructures. Therefore, during the PhD student's training period, we have researched the acoustic phenomena produced by isolated scatterers in order to better understand the physical phenomena behind the lasts designs of this type of screen. One of these researches led to the discovery of interferences between the effects of resonance and multiple scattering of sonic crystals when occurring in nearby frequency ranges. Also we have designed a new noise reduction device based on sonic crystals, using multi-objective optimization tools, which would block and diffuse the noise. This new designing tool identified the need for a comparative study of the most commonly used simulation methods to estimate the performance of devices based on sonic crystals. Finally, we have carried out a psychoacoustic study that determined the perception of the annoyance reduction provided by acoustic screens based on sonic crystals and traditional barriers, determining whether the objective parameters that evaluate their performance match to the subjective response of the users.Agradezco al Ministerio de Ciencia e Innovación por la ayuda concedida dentro del programa Doctores Industriales. Asimismo, a mi tutor en empresa Dr. Juan José Martín Pino, por posibilitar la realización de esta investigación dentro de la empresa BECSA. Al Departamento de Física Aplicada de la Universitat Politècnica de València, a la Comisión Académica del Programa de Doctorado de Matemáticas y al Centro de Tecnologías Físicas: Acústica, Materiales y Astrofísica.Peiró Torres, MDP. (2021). Research of the acoustic phenomenon produced by isolated scatterers and its applicability as a noise reducing device in transport infrastructures. Search for an optimised and sustainable design [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164903TESISCompendi

Fabricación de fibras de cristal fotónico y grabación de redes de Bragg

Los trabajos y experimentos desarrollados en esta tesis han ido dirigidos fundamentalmente a la fabricación de fibras de cristal fotónico y a la grabación de redes de Bragg en éstas. Este proyecto se ha desarrollado en dos partes. La primera parte consiste en conocer las características y propiedades de las redes de Bragg grabadas en fibras ópticas. Describe cuáles son las técnicas empleadas para la fabricación de redes de Bragg y explica el método utilizado en la grabación de redes en este trabajo, enfatizando la técnica de apodización de redes de Bragg que se implementó como mejora en el sistema de grabación previamente existente. Se describen algunas de las aplicaciones desarrolladas en temas tales como láseres de fibra óptica, filtros ópticos de microondas y cavidades Fabry-Perot. La parte del trabajo dedicada a estas aplicaciones ha sido la grabación de las redes de difracción con la anchura, amplitud y forma espectral adecuada además de realizar en buena parte de los experimentos el montaje del sistema y las medidas de caracterización correspondientes. En la segunda parte se trata de fabricar fibras de cristal fotónico fotosensibles a la luz ultravioleta, para poder grabar redes de Bragg sobre éstas, con láseres convencionales en la banda de 240 nm sin necesidad de recurrir a láseres de femtosegundos o de longitudes de onda más cortas. Se ha trabajado en la fabricación de fibras de cristal fotónico. Se explica de forma detallada el proceso de fabricación mediante la técnica de apilamiento de capilares y estiramiento, y el resultado de los diferentes tipos de fibra obtenidos. En primer lugar se trabajó en fibras cuyo único material era la sílice, y posteriormente se fabricaron fibras microestructuradas con el núcleo dopado con otros materiales. Por una parte se utilizó como dopante el erbio, necesario en fibras destinadas a la construcción de láseres y amplificadores, y por otra parte, empleamos el germanio en la fabricación de fibras fotosensibles para poder grabar redes de Bragg. Analizamos las propiedades de guiado de las fibras fabricadas en función de los parámetros de su estructura. En particular se caracterizan ampliamente las propiedades de una fibra con el núcleo en forma de “Y” y se muestran los resultados de algunos experimentos para estudiar cómo afecta la inserción de un líquido con alto índice de refracción a la propagación de la luz en la fibra. Estas fibras también se han utilizado para la generación de supercontinuo. Ha sido posible emplear la técnica de grabación de redes de Bragg en fibra convencional para el caso de las fibras de cristal fotónico. Se detallan los aspectos de las redes uniformes grabadas en las diferentes fibras de cristal fotónico previamente fabricadas, así como la grabación de redes con chirp en fibras abocinadas (cónicas). Se ha caracterizado la longitud de onda de Bragg de las redes frente a la tensión y la temperatura, comparando los resultados con los característicos de las fibras convencionales; también se han infiltrado líquidos en los agujeros de fibras con redes grabadas para estudiar los cambios que pueden introducir en sus características.The work developed in this thesis is about photonic crystal fiber fabrication and fiber Bragg grating photoinscription in them. The work is divided in two parts. The first one has been focused on the properties and characteristics of the fiber Bragg gratings fabricated in conventional fibers and also explains the photoinscription process that has been employed. A group of gratings with different characteristics has been designed to develop several applications as for example optic fiber lasers, microwave optical filters and Fabry-Perot cavities. These devices and the fiber gratings features required for a good operation are described too. In the second part, the fabrication process of photosensitive photonic crystal fibers is described. We have fabricated several photosensitive photonic crystal fibers with a germanium doped region in the core of the fiber. This doped region provides the fiber with photosensitivity to 244 nm light and allows us to fabricate fiber Bragg gratings using our equipment. Moreover, we analyze the guiding properties of our fibers and we focus on the ones from a “Y-shaped” fiber. The properties of this fiber can be modified after its fabrication if a material is inserted inside the holes. We obtain interesting results when we fill this fiber employing liquids with a particular refractive index. The results of the fiber Bragg gratings photoinscribed in the photonic crystal fibers are shown. The fabrication of chirped gratings in tapered fiber is studied, and the Bragg wavelength shift as a function of temperature and strain is compared to the shift of the gratings written in conventional fibers. At the end, some experiments are developed to describe the spectral changes of the gratings when a liquid is inserte

Temperature sensor based on Ge-doped microstructured fibers

The fundamental mode cutoff properties of Ge-doped microstructured fibers, filled with a liquid, permit the implementation of wavelength- and amplitude-encoded temperature sensors with an ultra-high sensitivity. The cutoff wavelength changes with temperature, and the thermo-optic coefficient of the liquid determines the sensitivity of the sensor. Sensitivity as high as 25 nm/◦C is reported. In addition, simple amplitude interrogation techniques can be implemented using the same sensor heads

Interferences in Locally Resonant Sonic Metamaterials Formed from Helmholtz Resonators

[EN] The emergence of materials artificially designed to control the transmission of waves, generally called metamaterials, has been a hot topic in the field of acoustics for several years. The design of these metamaterials is usually carried out by overlapping different wave control mechanisms. An example of this trend is the so-called Locally Resonant Sonic Materials, being one of them the Phononic Crystals with a local resonant structure. These metamaterials are formed by sets of isolated resonators in such a way that the control of the waves is carried out by resonances and by the existence of Bragg bandgaps, which appear due to the ordered distribution of the resonators. Their use is based on the creation of resonance peaks to form additional nontransmission bands mainly in the low frequency regime, usually below the first Bragg frequency. The coupling of both gaps has been made in some cases, but it is not always so. In this work, using a periodic structure formed by Helmholtz resonators, we report the existence of interferences between the resonances and the Bragg bandgaps when they are working in nearby frequency ranges, so that they prevent the coupling of both gaps. We explain their physical principles and present possible solutions to mitigate them. To this end, we have developed numerical models based on the finite element method, and the results have been verified by means of accurate experimental results obtained under controlled conditions. Published under license by AIP Publishing.M.P.P.T. is grateful for the support of pre-doctoral Grant by the "Ministerio de Economia y Competitividad" of Spain through reference No. DI-15-08100.Peiró-Torres, MDP.; Castiñeira Ibáñez, S.; Redondo, J.; Sánchez Pérez, JV. (2019). Interferences in Locally Resonant Sonic Metamaterials Formed from Helmholtz Resonators. 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Comparative study of simulation methods for the quantification of the acoustic insulation provided by periodic structures

[EN] Nowadays there are different available methods to perform simulations in acoustics. The suitability of them strongly depends on the system studied in each case. In the present work, a comparison between different methods (Multiple Scattering, Finite Elements Method and Finite Difference Time Domain) is carried out particularized to the quantification of the isolation provided by periodic structures (Sonic crystals). It has been considered a systematic study about computational time, precision and computational cost.[ES] Actualmente existen diferentes métodos para realizar simulaciones acústicas. La conveniencia de utilizar un método u otro depende del sistema que se estudia en cada caso. En este trabajo se realiza una comparativa entre diferentes métodos (Múltiple Scattering, Método de Elementos Finitos y Método de Diferencias Finitas en el Dominio del Tiempo) aplicados a la cuantificación del aislamiento proporcionado por estructuras periódicas (cristales de sonido). Se considera un estudio sistemático sobre tiempo computacional, la precisión y el coste computacional.This work was partially supported by the Spanish “MINISTERIO DE ECONOMIA, INDUSTRIA Y COMPETITIVIDAD” under the project TEC2015-68076-R.Parrilla-Navarro, MJ.; Redondo, J.; Sánchez Pérez, JV.; Peiró-Torres, MDP. (2018). Comparative study of simulation methods for the quantification of the acoustic insulation provided by periodic structures. Revista de Acústica. 49(1-2):3-10. http://hdl.handle.net/10251/112955S310491-

Marco para parsing predictivo interactivo aplicado a la lengua castellana

El marco teórico de Parsing Predictivo Interactivo (IPP) permite construir sistemas de anotación sintáctica interactivos. Los anotadores humanos pueden utilizar estos sistemas de ayuda para crear árboles sintácticos con muy poco esfuerzo (en comparación con el trabajo requerido para corregir manualmente árboles obtenidos a partir de un analizador sintáctico completamente automático). En este artículo se presenta la adaptación a la lengua castellana del marco IPP y su herramienta de anotación IPP-Ann, usando modelos obtenidos a partir del UAM Spanish Treebank. Hemos llevado a cabo experimentación simulando al usuario para obtener métricas de evaluación objetivas para nuestro sistema. Estos resultados muestran que el marco IPP aplicado al UAM Spanish Treebank se traduce en una importante cantidad de esfuerzo ahorrado, comparable con el obtenido al aplicar el marco IPP para analizar la lengua inglesa mediante el Penn Treebank.The Interactive Predictive Parsing (IPP) framework allows us the construction of interactive tree annotation systems. These can help human annotators in creating error-free parse trees with little effort (compared to manually post-editing the trees obtained from a completely automatic parser). In this paper we adapt the IPP framework and the IPP-Ann annotation tool for parse of the Spanish language, by using models obtained from the UAM Spanish Treebank. We performed user simulation experimentation and obtained objective evaluation metrics. The results establish that the IPP framework over the UAM Treebank shows important amounts of user effort reduction, comparable to the gains obtained when applying IPP to the English language on the Penn Treebank.Work supported by the EC (FEDER, FSE), the Spanish Government and Generalitat Valenciana (MICINN, ”Plan E”, under grants MIPRCV ”Consolider Ingenio 2010” CSD2007-00018, MIT-TRAL TIN2009-14633-C03-01, ALMPR Prometeo/2009/014 and FPU AP2006-01363)

A considerable improvement of the traditional FPGA-based digital design methodology by using an Arduino sensor board

[EN] The traditional way to learn and teach Digital Systems has been changing over the last decades by the use of Hardware Description Languages (HDL) and Field Programmable Gate Array (FPGA) evaluation boards. The use of an Arduino development kit with different sensors connected to the FPGA upsizes the students experience in the area of Digital Systems. A temperature and humidity ambience sensor combined with an ultrasound sensor to measure distance can effectively be used by students to implement its first serial data converter that takes the sensor data and shows the obtained values from the Arduino in the seven segment display of the FPGA kit. After three years of experience in the new grade courses at the UPV Telecommunication School the number of students enjoying this new way to learn the subject Fundamentals of Digital Electronics (FSD) has dramatically risen up with an increase of a 20% in the number of students that pass the subject and that select the electronic branch of telecommunication studies in the future semesters.Martínez Peiró, MA.; Larrea Torres, MÁ.; Lidon Roger, J.; Jiménez Jiménez, Y.; Torres Curado, R.; Tébar Ruiz, Á. (2020). A considerable improvement of the traditional FPGA-based digital design methodology by using an Arduino sensor board. Editorial Universitat Politècnica de València. 81-89. https://doi.org/10.4995/INN2019.2019.10091OCS818

Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings

In this paper, we describe the properties of Fabry-Perot fiber cavity formed by two fiber Bragg gratings in terms of the grating effective length. We show that the grating effective length is determined by the group delay of the grating, which depends on its diffraction efficiency and physical length. We present a simple analytical formula for calculation of the effective length of the uniform fiber Bragg grating and the frequency separation between consecutive resonances of a Fabry-Perot cavity. Experimental results on the cavity transmission spectra for different values of the gratings' reflectivity support the presented theory

Parallel laser micromachining based on diffractive optical elements with dispersion compensated femtosecond pulses

We experimentally demonstrate multi-beam high spatial resolution laser micromachining with femtosecond pulses. The effects of chromatic aberrations as well as pulse stretching on the material processed due to diffraction were significantly mitigated by using a suited dispersion compensated module (DCM). This permits to increase the area of processing in a factor 3 in comparison with a conventional setup. Specifically, 52 blind holes have been drilled simultaneously onto a stainless steel sample with a 30 fs laser pulse in a parallel processing configuration

Influence of diet in urinary levels of metals in a biomonitoring study of a child population of the Valencian region (Spain)

[EN] Pollution by trace elements and its possible effect on organisms has become a worldwide concern due to the increasing presence of trace elements in the environment and especially in the food chain. Exposure to chemicals has traditionally been measured using environmental samples, however, human biomonitoring brings a different perspective, in which all sources and exposure pathways are integrated. The objective of this paper is to discern the possible relationship between children's diet and the metals found in children urine. With this aim in mind, a total of 120 voluntaries participated in a diet survey carried out in a school-aged population (age 6-11) from the Valencian region. In addition, twenty trace elements were analysed in children urine (arsenic, antimony, barium, beryllium, caesium, cadmium, cobalt, copper, lead, manganese, mercury, molybdenum, nickel, platinum, selenium, thallium, thorium, uranium, vanadium and zinc). Results permitted to compare metal levels in urine with metal levels of other biomonitoring studies to conclude that values, including ours, were similar in most studies. On the other hand, children who ate more vegetables had the highest values in cadmium, copper, molybdenum, antimony, thallium, vanadium, and zinc, while those who ate more fish reached higher values in mercury. Finally, children who ate more cereals and baked products had higher values in total arsenic. (c) 2017 Elsevier B.V. All rights reserved.This study was part of the research project CIPAV supported by the Conselleria de Educacion, Generalitat Valenciana (GV/2011/007).Pérez-Torres, R.; Doménech Antich, EM.; Conchado Peiró, A.; Sanchez, A.; Coscollà, C.; Yusà, V. (2018). Influence of diet in urinary levels of metals in a biomonitoring study of a child population of the Valencian region (Spain). The Science of The Total Environment. 618:1647-1657. https://doi.org/10.1016/j.scitotenv.2017.10.011S1647165761