"Convert Unix timestamps to human-readable dates and vice versa. Supports seconds, milliseconds, ISO 8601, RFC 2822, timezone comparison, and auto-detection."
"Loudspeakers for Vented Enclosures: a Backwards Approach for Speaker Selection (LoVE BASS)"
name:
"Loudspeakers for Vented Enclosures: a Backwards Approach for Speaker Selection (LoVE BASS)"
datePublished:
"2019"
author:
Person
givenName:
"Francisco"
familyName:
"Castells"
name:
"Francisco Castells"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
publication:
Periodical
name:
"Voice Coil."
abstract:
"In this article, the problem of designing vented enclosures is revisited, with a backward concept: from the box to the driver as opposed to taking a given driver and designing an enclosure. The classical procedure starts by choosing a supposedly appropriate driver for the target enclosure. No specific recommendations are available for transducer selection, apart from designer’s expertise, which leads to a trial-and-error approach until a convenient transducer is found."
ListItem
position:
2
item:
ScholarlyArticle
headline:
"Perfect broadband sound absorber metamaterial for noise reduction in a rocket launch"
name:
"Perfect broadband sound absorber metamaterial for noise reduction in a rocket launch"
datePublished:
"2021"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Rubén"
familyName:
"Picó"
name:
"Rubén Picó"
Person
givenName:
"Víctor J."
familyName:
"Sánchez-Morcillo"
name:
"Víctor J. Sánchez-Morcillo"
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Alejandro"
familyName:
"Cebrecos"
name:
"Alejandro Cebrecos"
Person
givenName:
"Mara Salut"
familyName:
"Escartí-Guillem"
name:
"Mara Salut Escartí-Guillem"
publication:
Periodical
name:
"European Congress and Exposition on Noise Control Engineering (EuroNoise 2021)"
abstract:
"Metamaterials based on Helmholtz resonators represent alternatives for noise mitigation applications where traditional materials can not be used due to the environmental conditions. One such case is found in the extreme acoustic event caused by a rocket launch. Metamaterials can also be designed on demand to act on the sound waves at a specific frequency range, which depends on the particular application. In this work we present the design procedure of a metamaterial panel, with a potential use for noise mitigation during a rocket launch. The proposed sound absorber presents almost perfect sound absorption in a prescribed bandwidth. The geometrical parameters of a unit cell, the building block of the panel, are obtained by using the transfer matrix method, and the use of optimization algorithms. The effective acoustical parameters of the designed metamaterial are also obtained. Using the effective parameters, the acoustical response of a panel built from an array including a large number of unit cells is numerically computed. Finally, experiments in an impedance tube that validate the theoretical results are presented."
ListItem
position:
3
item:
ScholarlyArticle
headline:
"Sound diffusing metasurfaces based on elastic plates and membranes"
name:
"Sound diffusing metasurfaces based on elastic plates and membranes"
datePublished:
"2021"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Jean-Philippe"
familyName:
"Groby"
name:
"Jean-Philippe Groby"
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Vicente"
familyName:
"Romero-García"
name:
"Vicente Romero-García"
publication:
Periodical
name:
"European Congress and Exposition on Noise Control Engineering (EuroNoise 2021)"
abstract:
"Traditional acoustic diffusers are based on quarter-wavelength resonators, and they are commonly built using slotted panels. The use of this kind of resonators implies that these panels can hardly be manufactured to work at low frequencies due to the resulting high thickness. Recently, the use of resonant metamaterials based on Helmholtz resonators, i.e., metadiffusers, has been proposed to reduce panel thickness. In this work we propose the use of plate and membrane (I will use only plate) resonators to go one step further in managing sound reflection using ultrathin metasurfaces of deep subwavelength dimensions. Using a 5.7-cm thick panel, a mean diffusion coefficient of 0.8 in the range from 400 to 800 Hz has been numerically and theoretically observed. The potential of resonant metamaterials based on plate and membrane resonators is demonstrated and its limitations discussed. This study provides the guidelines and design tools for prototyping these low-thicknesses panels to generate diffuse reflections."
ListItem
position:
4
item:
ScholarlyArticle
headline:
"Application of metamaterials to control noise scattering during space vehicle lift-off"
name:
"Application of metamaterials to control noise scattering during space vehicle lift-off"
datePublished:
"2021"
author:
Person
givenName:
"Mara Salut"
familyName:
"Escartí-Guillem"
name:
"Mara Salut Escartí-Guillem"
Person
givenName:
"Pablo Barriuso"
familyName:
"Feijoo"
name:
"Pablo Barriuso Feijoo"
Person
givenName:
"Alejandro"
familyName:
"Cebrecos"
name:
"Alejandro Cebrecos"
Person
givenName:
"Marcos Chimeno"
familyName:
"Manguán"
name:
"Marcos Chimeno Manguán"
Person
givenName:
"Pedro Cobo"
familyName:
"Parra"
name:
"Pedro Cobo Parra"
Person
givenName:
"Luis Miguel García"
familyName:
"Raffi"
name:
"Luis Miguel García Raffi"
Person
givenName:
"Jean-Philippe"
familyName:
"Groby"
name:
"Jean-Philippe Groby"
Person
givenName:
"Sergio Hoyas"
familyName:
"Calvo"
name:
"Sergio Hoyas Calvo"
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Mario Lázaro"
familyName:
"Navarro"
name:
"Mario Lázaro Navarro"
Person
givenName:
"Julien"
familyName:
"Leng"
name:
"Julien Leng"
Person
givenName:
"José Nieto"
familyName:
"Mocholí"
name:
"José Nieto Mocholí"
Person
givenName:
"Rubén"
familyName:
"Picó"
name:
"Rubén Picó"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Elena Roibás"
familyName:
"Millán"
name:
"Elena Roibás Millán"
publication:
Periodical
name:
"European Congress and Exposition on Noise Control Engineering (EuroNoise 2021)"
abstract:
"Metamaterials made of resonant building blocks based on Helmholtz resonators have been developed as perfect acoustic absorbers. The performance of these metamaterials is analyzed when used to control the scattering of noise during a space vehicle lift-off. In this event, two main contributions of sound should be controlled: i) the reflected from the launch pad and ii) the transmitted through the faring wall. Numerical models are developed to predict the vibro-acoustic response of two metamaterials designed for these two problems. The approach is to simplify the numerical model by obtaining a simplified panel with equivalent acoustic and mechanical behavior on the frequency range of interest. The first solution is based on a rainbow trapping structure that will be applied as an exhaust channel cover. Later, an ultra-thin perfect absorber is designed to be added to the fairing composite sandwich. Results show a significant noise reduction while small effects of the vibro-acoustic coupling are theoretically and numerically observed. The developed methodology enables a simplification in the noise control analysis and opens the way for its use in other applications."
ListItem
position:
5
item:
ScholarlyArticle
headline:
"Launch sound level characterisation and mitigation: numerical modelling framework and metamaterial proof of concept."
name:
"Launch sound level characterisation and mitigation: numerical modelling framework and metamaterial proof of concept."
datePublished:
"2021"
author:
Person
givenName:
"Mara Salut"
familyName:
"Escartí-Guillem"
name:
"Mara Salut Escartí-Guillem"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Pablo Barriuso"
familyName:
"Feijoo"
name:
"Pablo Barriuso Feijoo"
Person
givenName:
"Alejandro"
familyName:
"Cebrecos"
name:
"Alejandro Cebrecos"
Person
givenName:
"Marcos Chimeno"
familyName:
"Manguán"
name:
"Marcos Chimeno Manguán"
Person
givenName:
"Pedro Cobo"
familyName:
"Parra"
name:
"Pedro Cobo Parra"
Person
givenName:
"Luis Miguel García"
familyName:
"Raffi"
name:
"Luis Miguel García Raffi"
Person
givenName:
"Jean-Philippe"
familyName:
"Groby"
name:
"Jean-Philippe Groby"
Person
givenName:
"Sergio Hoyas"
familyName:
"Calvo"
name:
"Sergio Hoyas Calvo"
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Mario Lázaro"
familyName:
"Navarro"
name:
"Mario Lázaro Navarro"
Person
givenName:
"Julien"
familyName:
"Leng"
name:
"Julien Leng"
Person
givenName:
"José Nieto"
familyName:
"Mocholí"
name:
"José Nieto Mocholí"
Person
givenName:
"Elena Roibás"
familyName:
"Millán"
name:
"Elena Roibás Millán"
Person
givenName:
"Vicente"
familyName:
"Romero-García"
name:
"Vicente Romero-García"
Person
givenName:
"Rubén"
familyName:
"Picó"
name:
"Rubén Picó"
Person
givenName:
"Víctor J."
familyName:
"Sánchez-Morcillo"
name:
"Víctor J. Sánchez-Morcillo"
Person
givenName:
"F. Simón"
familyName:
"Hidalgo"
name:
"F. Simón Hidalgo"
Person
givenName:
"I. C.S."
familyName:
"Ngan"
name:
"I. C.S. Ngan"
publication:
Periodical
name:
"16th European Conference on Spacecraft structures, Materials & Environmental Testing."
abstract:
"Due to the severe acoustic environment during space vehicle lift off the prediction and mitigation of acoustic levels becomes a vital issue. This paper conforms the engineering background needed to develop a new sound mitigation method for vehicle launchers. The sound propagation within a launch event has been analysed with dedicated CFD, identifying the shock waves and the evolution of the SPL generated. Data analysis of the pressure field surrounding the fairing demonstrates a vertical directivity. On the structural domain, a numerical modelling framework composed of an hybrid FEM/BEM/SEA model has been postulated. The results provide the basis to analyse the mitigation structures proposed. On the acoustic side, two different metamaterial structures are presented, both made of a periodic unit cell of Helmholtz resonators. On the launch pad, the metamaterial partially covers the exhaust channels and provides quasi-perfect broadband sound absorption. On the fairing the metamaterial is added to the existing wall and introduce an absorption peak. These findings provide a noise mitigation technique that has the potential to improve the attenuation efficiency, thus, reducing the acoustic loading and the risk of technical failure during the launch stage."
ListItem
position:
6
item:
ScholarlyArticle
headline:
"Acoustic field prediction during the launch of rockets"
name:
"Acoustic field prediction during the launch of rockets"
datePublished:
"2020"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Alejandro"
familyName:
"Cebrecos"
name:
"Alejandro Cebrecos"
Person
givenName:
"Rubén"
familyName:
"Picó"
name:
"Rubén Picó"
Person
givenName:
"Víctor J."
familyName:
"Sánchez-Morcillo"
name:
"Víctor J. Sánchez-Morcillo"
publication:
Periodical
name:
"Tecniacústica 2020: 50º Congreso Español de Acústica. XI Congreso Ibérico de Acústica. Faro, Portugal."
abstract:
"This work presents the prediction of noise generated during the launch of space rockets. A semiempirical model was applied, using as input data the physical and geometric characteristics of the jet of gases propelled by the rocket, which acts as the primary source of noise. The model is based on the one originally proposed by Eldred back in 1971 and its subsequent modifications. We expanded the model with expressions for the estimation of the acoustic power of noise sources. To validate the prediction in a particular case, we have considered the launch of the VEGA rocket from European Space Agency, at the launchpad located in Kourou (French Guiana). Using as reference experimental data recorded during a launch, the study confirms that the semi-empirical model predicts the acoustic field generated during the launch with great precision, especially in the low and medium frequencies, which are the most interesting from the point of view of impact that this noise has on the rocket and its load."
ListItem
position:
7
item:
ScholarlyArticle
headline:
"Beyond Schroeder diffusers using acoustic metasurfaces"
name:
"Beyond Schroeder diffusers using acoustic metasurfaces"
datePublished:
"2020"
author:
Person
givenName:
"Noé"
familyName:
"Jiménez"
name:
"Noé Jiménez"
Person
givenName:
"Trevor J."
familyName:
"Cox"
name:
"Trevor J. Cox"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Eric"
familyName:
"Ballestero"
name:
"Eric Ballestero"
Person
givenName:
"Jean-Philippe"
familyName:
"Groby"
name:
"Jean-Philippe Groby"
Person
givenName:
"Vicente"
familyName:
"Romero-García"
name:
"Vicente Romero-García"
publication:
Periodical
name:
"Tecniacústica 2020: 50º Congreso Español de Acústica. XI Congreso Ibérico de Acústica. Faro, Portugal."
abstract:
"Sound diffusers are structured surfaces designed to control the scattering of acoustic waves, mainly used in room acoustics to improve sound quality. However, as they are mainly based on quarterwavelength resonators, phase-grating diffusers result in heavy and thick structures. We present a novel approach to design deep-subwavelength sound diffusers based on subwavelength resonating units, i.e., metamaterials. The proposed “metadiffusers” show broadband diffusion ranging from 250 Hz to 2 kHz using panels of 3 cm, 20 times thinner than traditional designs. In addition, their performance can be tailored to classical quadratic residue, primitive root, and ternary sequence designs. In the presentation we will review recent developments in this type of metasurfaces, including membrane and plate diffusers, and novel holographic approaches."
ListItem
position:
8
item:
ScholarlyArticle
headline:
"Aprendizaje basado en proyectos en las materias transductores acústicos y vibroacústica"
name:
"Aprendizaje basado en proyectos en las materias transductores acústicos y vibroacústica"
datePublished:
"2018"
author:
Person
givenName:
"Jaime"
familyName:
"Ramis"
name:
"Jaime Ramis"
Person
givenName:
"Jesús"
familyName:
"Carbajo"
name:
"Jesús Carbajo"
Person
givenName:
"Juan de Dios"
familyName:
"González"
name:
"Juan de Dios González"
Person
givenName:
"Pedro"
familyName:
"Poveda"
name:
"Pedro Poveda"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Enrique G."
familyName:
"Segovia"
name:
"Enrique G. Segovia"
Person
familyName:
"others"
name:
"others"
publication:
Periodical
name:
"Memorias del Programa de Redes-ICE de calidad, innovación e investigación en docencia universitaria. Convocatoria 2017-18."
abstract:
"El presente trabajo resume las experiencias llevadas a cabo durante el curso 2017-18 con el objetivo de introducir la metodología de aprendizaje basado en proyectos (ABP) en dos materias de segundo y tercer curso, respectivamente, de la titulación de Grado en Ingeniería en Sonido e Imagen en Telecomunicación (GISIT) que se imparte en la Universidad de Alicante. La primera de ellas, denominada Transductores Acústicos, corresponde a una asignatura obligatoria de cuarto cuatrimestre mientras que la segunda, Vibroacústica, es una materia optativa. Ambas constituyen un escenario apropiado para aplicar la metodología de ABP. La experiencia que se está llevando a cabo este curso pretende ser el anticipo a una propuesta completa de cambio de metodología si así lo permiten las circunstancias."
ListItem
position:
9
item:
ScholarlyArticle
headline:
"Cálculo corregido, basado en la teoría moderna, de los campos acústicos (directo, temprano y tardío)"
name:
"Cálculo corregido, basado en la teoría moderna, de los campos acústicos (directo, temprano y tardío)"
datePublished:
"2018"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Jenaro"
familyName:
"Vera Guarinos"
name:
"Jenaro Vera Guarinos"
publication:
Periodical
name:
"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
abstract:
"El cálculo teórico de los campos directo, temprano y reverberante han sido objeto de análisis por parte de muchos autores. Este trabajo se basa en las teorías de Barron y Lee (1988), y de Sato y Bradley (2008). Nuestro estudio se desarrolla a partir de datos experimentales y en la posibilidad de usar otros resultados obtenidos en modelos de simulación validados con ayuda de “EASE”, lo que posibilita tener una amplia variedad de situaciones. Es por lo que los coeficientes de ajuste que introducimos en las ecuaciones de la teoría revisada o moderna proporcionan ahora unos resultados más ajustados a la realidad. Dichos coeficientes pretenden, en su definición, estar relacionados con la posición de la fuente y la geometría del recinto. A parte de una mejor bondad en los ajustes respecto a los resultados experimentales, se ha encontrado que lo que llamamos ‘campo temprano’ presenta un decaimiento que depende de la inversa de la distancia."
ListItem
position:
10
item:
ScholarlyArticle
headline:
"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en EASE"
name:
"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en EASE"
datePublished:
"2018"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Jenaro"
familyName:
"Vera Guarinos"
name:
"Jenaro Vera Guarinos"
publication:
Periodical
name:
"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
abstract:
"En este trabajo abordamos de nuevo la relación entre campo útil (0-50ms) y perjudicial (50msinfinito). Se realizan medidas “in situ” de dos recintos de planta rectangular cuyas dimensiones son diferentes con el fin de evitar que los resultados estén determinados por el tamaño. La intención de nuestro estudio es validar los resultados experimentales frente a los obtenidos mediante modelos para así poder realizar un estudio en profundidad de cuáles son las propiedades que gobiernan la propagación del campo acústico en espacios cerrados. El software que se ha utilizado en este caso ha sido “EASE” a partir del cual se obtuvo un conjunto de respuestas impulsivas que posibilitaron un tratamiento equivalente al realizado con las experimentales. Los resultados obtenidos muestran gran similitud. Por lo que con la metodología empleada podremos a partir de ahora profundizar en el estudio de la propagación del campo acústico sin necesidad de realizar tediosas campañas de medidas “in situ” y con la posibilidad de realizar cambios “ad libitum” por ejemplo en la distribución de absorciones."
ListItem
position:
11
item:
ScholarlyArticle
headline:
"Comportamiento vibroacústico de contenedores cilíndricos en aire"
name:
"Comportamiento vibroacústico de contenedores cilíndricos en aire"
datePublished:
"2018"
author:
Person
givenName:
"Francisco J."
familyName:
"Rodrigo"
name:
"Francisco J. Rodrigo"
Person
givenName:
"Pedro"
familyName:
"Poveda"
name:
"Pedro Poveda"
Person
givenName:
"Jesús"
familyName:
"Carbajo"
name:
"Jesús Carbajo"
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Jaime"
familyName:
"Ramis"
name:
"Jaime Ramis"
publication:
Periodical
name:
"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
abstract:
"Este trabajo describe el procedimiento experimental llevado a cabo para estudiar el comportamiento radiante de la superficie de la base de estructuras en forma semilcilindro de 50 cm de diámetro y una superficie lateral de 15 cm de altura cuando son excitados mediante un actuador en el centro de la base. El nivel de vibración ha evaluado mediante acelerómetros de pequeño tamaño completando un detallado análisis modal. Las medidas de nivel de presión sonora se han realizado en una superficie cercana a la fuente y los datos se han procesado de acuerdo con la técnica de Holografia Acústica de Campo Cercano (NAH). Además de comparar los resultados de distintos materiales (acero y aluminio), se estudia la influencia de la condición de unión entre la superficie de la base y la superficie lateral de la estructura."
ListItem
position:
12
item:
ScholarlyArticle
headline:
"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en catt-acoustic"
name:
"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en catt-acoustic"
datePublished:
"2017"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
Person
givenName:
"Jenaro Vera"
familyName:
"Guarinos"
name:
"Jenaro Vera Guarinos"
Person
givenName:
"María Soledad Yebra"
familyName:
"Calleja"
name:
"María Soledad Yebra Calleja"
publication:
Periodical
name:
"Tecniacústica 2017: 48º Congreso Español de Acústica; Encuentro Ibérico de Acústica; European Symposium on Underwater Acoustics Applications; European Symposium on Sustainable Building Acoustics."
abstract:
"Basándonos en los resultados obtenidos en trabajos anteriores, se plantea el estudio del fenómeno desde el punto de vista de la simulación en un modelo tridimensional. Se comprueba que existe un paralelismo evidente entre los resultados de la simulación y lo experimental. Para ahondar en la cuestión se aplica el procedimiento en un recinto de menor tamaño y se extraen las consecuencias pertinentes sobre: validez, importancia de la geometría y disposición del mobiliario."
ListItem
position:
13
item:
ScholarlyArticle
headline:
"Difusores acústicos basados en resonadores de membrana y placa"
name:
"Difusores acústicos basados en resonadores de membrana y placa"
datePublished:
"2019"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
publication:
Periodical
name:
"Universitat Politècnica de València. Departamento de Física Aplicada. Escuela Politécnica Superior de Gandia."
abstract:
"Los difusores acústicos tradicionales están basados en resonadores de cuarto de longitud de onda construidos con paneles ranurados. Es por ello que dichos paneles difícilmente pueden ser fabricados para trabajar en bajas frecuencias debido al elevado espesor resultante. Recientemente se ha propuesto el uso de metamateriales resonantes basados en resonadores de Helmholtz para reducir el espesor del panel, es decir, metadifusores. En este trabajo se propone el empleo de resonadores de placa y membrana para ir un paso más allá, consiguiendo controlar la reflexión del sonido empleando metasuperficies ultraplanas con un espesor mucho más pequeño que la longitud de onda."
ListItem
position:
14
item:
ScholarlyArticle
headline:
"Estudio de la relación campo directo/reverberado; útil/perjudicial"
name:
"Estudio de la relación campo directo/reverberado; útil/perjudicial"
datePublished:
"2018"
author:
Person
givenName:
"José M."
familyName:
"Requena-Plens"
name:
"José M. Requena-Plens"
publication:
Periodical
name:
"Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal."
abstract:
"La división entre campo directo y campo reverberante es correcta aunque en la práctica carece de utilidad, debido a que la fisiología del oído humano agrupa el campo directo y algunas de las primeras reflexiones haciendo creer a nuestro cerebro que todo ello constituye un solo sonido. Este concepto fue desarrollado por Hass (1951), donde se demuestra que hasta cierto tiempo todo el sonido recibido se integra y el cerebro lo procesa como un único sonido sin reflexiones y además ubica el origen del sonido en el lugar de donde se ha recibido el primer sonido. El tiempo definido por Hass para la comunicación hablada es de 50 milisegundos, es decir, todo sonido (directo y reflejado) hasta transcurridos los 50 milisegundos es integrado por el sistema auditivo humano y entendido como un único sonido, este concepto produjo que se utilizara más convenientemente la nomenclatura de campo directo, campo temprano (engloba todo sonido después del campo directo hasta los 50 ms) y campo reverberante (todo sonido después de los 50 ms). El campo reverberante definido como el campo comprendido desde los 50 milisegundos, llega después del tiempo en el que el oído humano integra el sonido como uno solo e interfiere en el sonido que se pretendía oír. Es por ello que los campos acústicos se pueden denominar como campo útil (campo directo y campo temprano) y campo perjudicial (campo reverberante desde los 50 ms). Teniendo en cuenta el concepto de campo útil y campo perjudicial y, entendiendo la importancia de la relación de éstos en la inteligibilidad de la palabra, se puede comprender la importancia de poder calcular matemáticamente los campos de la forma más correcta posible. Actualmente existen multitud de ecuaciones que si bien se aproximan al comportamiento experimental de los campos acústicos no son del todo correctos y por tanto no se pueden utilizar para prever el comportamiento. Los últimos cálculos desarrollados por Barron y Lee (1988) son de los pocos que tienen en cuenta una separación temporal para calcular matemáticamente el campo útil y perjudicial, aunque como se verá en este trabajo estos cálculos no se corresponden con el comportamiento real. Ante esta problemática se propone un cálculo modificado de los campos, basado en las ecuaciones de Barron y Lee e inspirado en la búsqueda de un ajuste en el cálculo de Sato y Bradley (2008), donde, a partir de una serie de medidas experimentales o mediante modelos acústicos, se comparan con el cálculo teórico de los campos útil y perjudicial y se buscan coeficientes de ajuste para obtener finalmente un cálculo teórico válido relacionando los coeficientes obtenidos con las características del recinto."
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"headline":"Loudspeakers for Vented Enclosures: a Backwards Approach for Speaker Selection (LoVE BASS)",
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"abstract":"In this article, the problem of designing vented enclosures is revisited, with a backward concept: from the box to the driver as opposed to taking a given driver and designing an enclosure. The classical procedure starts by choosing a supposedly appropriate driver for the target enclosure. No specific recommendations are available for transducer selection, apart from designer’s expertise, which leads to a trial-and-error approach until a convenient transducer is found."
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"headline":"Perfect broadband sound absorber metamaterial for noise reduction in a rocket launch",
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"abstract":"Metamaterials based on Helmholtz resonators represent alternatives for noise mitigation applications where traditional materials can not be used due to the environmental conditions. One such case is found in the extreme acoustic event caused by a rocket launch. Metamaterials can also be designed on demand to act on the sound waves at a specific frequency range, which depends on the particular application. In this work we present the design procedure of a metamaterial panel, with a potential use for noise mitigation during a rocket launch. The proposed sound absorber presents almost perfect sound absorption in a prescribed bandwidth. The geometrical parameters of a unit cell, the building block of the panel, are obtained by using the transfer matrix method, and the use of optimization algorithms. The effective acoustical parameters of the designed metamaterial are also obtained. Using the effective parameters, the acoustical response of a panel built from an array including a large number of unit cells is numerically computed. Finally, experiments in an impedance tube that validate the theoretical results are presented."
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"headline":"Sound diffusing metasurfaces based on elastic plates and membranes",
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"@type":"Person",
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"abstract":"Traditional acoustic diffusers are based on quarter-wavelength resonators, and they are commonly built using slotted panels. The use of this kind of resonators implies that these panels can hardly be manufactured to work at low frequencies due to the resulting high thickness. Recently, the use of resonant metamaterials based on Helmholtz resonators, i.e., metadiffusers, has been proposed to reduce panel thickness. In this work we propose the use of plate and membrane (I will use only plate) resonators to go one step further in managing sound reflection using ultrathin metasurfaces of deep subwavelength dimensions. Using a 5.7-cm thick panel, a mean diffusion coefficient of 0.8 in the range from 400 to 800 Hz has been numerically and theoretically observed. The potential of resonant metamaterials based on plate and membrane resonators is demonstrated and its limitations discussed. This study provides the guidelines and design tools for prototyping these low-thicknesses panels to generate diffuse reflections."
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"abstract":"Metamaterials made of resonant building blocks based on Helmholtz resonators have been developed as perfect acoustic absorbers. The performance of these metamaterials is analyzed when used to control the scattering of noise during a space vehicle lift-off. In this event, two main contributions of sound should be controlled: i) the reflected from the launch pad and ii) the transmitted through the faring wall. Numerical models are developed to predict the vibro-acoustic response of two metamaterials designed for these two problems. The approach is to simplify the numerical model by obtaining a simplified panel with equivalent acoustic and mechanical behavior on the frequency range of interest. The first solution is based on a rainbow trapping structure that will be applied as an exhaust channel cover. Later, an ultra-thin perfect absorber is designed to be added to the fairing composite sandwich. Results show a significant noise reduction while small effects of the vibro-acoustic coupling are theoretically and numerically observed. The developed methodology enables a simplification in the noise control analysis and opens the way for its use in other applications."
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"name":"16th European Conference on Spacecraft structures, Materials & Environmental Testing."
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"abstract":"Due to the severe acoustic environment during space vehicle lift off the prediction and mitigation of acoustic levels becomes a vital issue. This paper conforms the engineering background needed to develop a new sound mitigation method for vehicle launchers. The sound propagation within a launch event has been analysed with dedicated CFD, identifying the shock waves and the evolution of the SPL generated. Data analysis of the pressure field surrounding the fairing demonstrates a vertical directivity. On the structural domain, a numerical modelling framework composed of an hybrid FEM/BEM/SEA model has been postulated. The results provide the basis to analyse the mitigation structures proposed. On the acoustic side, two different metamaterial structures are presented, both made of a periodic unit cell of Helmholtz resonators. On the launch pad, the metamaterial partially covers the exhaust channels and provides quasi-perfect broadband sound absorption. On the fairing the metamaterial is added to the existing wall and introduce an absorption peak. These findings provide a noise mitigation technique that has the potential to improve the attenuation efficiency, thus, reducing the acoustic loading and the risk of technical failure during the launch stage."
}
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"headline":"Acoustic field prediction during the launch of rockets",
"name":"Acoustic field prediction during the launch of rockets",
"datePublished":"2020",
"author": [
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
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"name":"Víctor J. Sánchez-Morcillo"
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"name":"Tecniacústica 2020: 50º Congreso Español de Acústica. XI Congreso Ibérico de Acústica. Faro, Portugal."
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"abstract":"This work presents the prediction of noise generated during the launch of space rockets. A semiempirical model was applied, using as input data the physical and geometric characteristics of the jet of gases propelled by the rocket, which acts as the primary source of noise. The model is based on the one originally proposed by Eldred back in 1971 and its subsequent modifications. We expanded the model with expressions for the estimation of the acoustic power of noise sources. To validate the prediction in a particular case, we have considered the launch of the VEGA rocket from European Space Agency, at the launchpad located in Kourou (French Guiana). Using as reference experimental data recorded during a launch, the study confirms that the semi-empirical model predicts the acoustic field generated during the launch with great precision, especially in the low and medium frequencies, which are the most interesting from the point of view of impact that this noise has on the rocket and its load."
}
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"@type":"ScholarlyArticle",
"headline":"Beyond Schroeder diffusers using acoustic metasurfaces",
"name":"Beyond Schroeder diffusers using acoustic metasurfaces",
"datePublished":"2020",
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{
"@type":"Person",
"givenName":"Noé",
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"familyName":"Cox",
"name":"Trevor J. Cox"
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"@type":"Person",
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"name":"José M. Requena-Plens"
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"name":"Jean-Philippe Groby"
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"name":"Vicente Romero-García"
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"name":"Tecniacústica 2020: 50º Congreso Español de Acústica. XI Congreso Ibérico de Acústica. Faro, Portugal."
},
"abstract":"Sound diffusers are structured surfaces designed to control the scattering of acoustic waves, mainly used in room acoustics to improve sound quality. However, as they are mainly based on quarterwavelength resonators, phase-grating diffusers result in heavy and thick structures. We present a novel approach to design deep-subwavelength sound diffusers based on subwavelength resonating units, i.e., metamaterials. The proposed “metadiffusers” show broadband diffusion ranging from 250 Hz to 2 kHz using panels of 3 cm, 20 times thinner than traditional designs. In addition, their performance can be tailored to classical quadratic residue, primitive root, and ternary sequence designs. In the presentation we will review recent developments in this type of metasurfaces, including membrane and plate diffusers, and novel holographic approaches."
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"headline":"Aprendizaje basado en proyectos en las materias transductores acústicos y vibroacústica",
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"@type":"Person",
"givenName":"Jaime",
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"givenName":"Enrique G.",
"familyName":"Segovia",
"name":"Enrique G. Segovia"
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"publication": {
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"name":"Memorias del Programa de Redes-ICE de calidad, innovación e investigación en docencia universitaria. Convocatoria 2017-18."
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"abstract":"El presente trabajo resume las experiencias llevadas a cabo durante el curso 2017-18 con el objetivo de introducir la metodología de aprendizaje basado en proyectos (ABP) en dos materias de segundo y tercer curso, respectivamente, de la titulación de Grado en Ingeniería en Sonido e Imagen en Telecomunicación (GISIT) que se imparte en la Universidad de Alicante. La primera de ellas, denominada Transductores Acústicos, corresponde a una asignatura obligatoria de cuarto cuatrimestre mientras que la segunda, Vibroacústica, es una materia optativa. Ambas constituyen un escenario apropiado para aplicar la metodología de ABP. La experiencia que se está llevando a cabo este curso pretende ser el anticipo a una propuesta completa de cambio de metodología si así lo permiten las circunstancias."
}
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"@type":"ListItem",
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"@type":"ScholarlyArticle",
"headline":"Cálculo corregido, basado en la teoría moderna, de los campos acústicos (directo, temprano y tardío)",
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{
"@type":"Person",
"givenName":"José M.",
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"name":"José M. Requena-Plens"
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{
"@type":"Person",
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"familyName":"Vera Guarinos",
"name":"Jenaro Vera Guarinos"
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"publication": {
"@type":"Periodical",
"name":"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
},
"abstract":"El cálculo teórico de los campos directo, temprano y reverberante han sido objeto de análisis por parte de muchos autores. Este trabajo se basa en las teorías de Barron y Lee (1988), y de Sato y Bradley (2008). Nuestro estudio se desarrolla a partir de datos experimentales y en la posibilidad de usar otros resultados obtenidos en modelos de simulación validados con ayuda de “EASE”, lo que posibilita tener una amplia variedad de situaciones. Es por lo que los coeficientes de ajuste que introducimos en las ecuaciones de la teoría revisada o moderna proporcionan ahora unos resultados más ajustados a la realidad. Dichos coeficientes pretenden, en su definición, estar relacionados con la posición de la fuente y la geometría del recinto. A parte de una mejor bondad en los ajustes respecto a los resultados experimentales, se ha encontrado que lo que llamamos ‘campo temprano’ presenta un decaimiento que depende de la inversa de la distancia."
}
},
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"@type":"ListItem",
"position":10,
"item": {
"@type":"ScholarlyArticle",
"headline":"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en EASE",
"name":"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en EASE",
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"author": [
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
},
{
"@type":"Person",
"givenName":"Jenaro",
"familyName":"Vera Guarinos",
"name":"Jenaro Vera Guarinos"
}
],
"publication": {
"@type":"Periodical",
"name":"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
},
"abstract":"En este trabajo abordamos de nuevo la relación entre campo útil (0-50ms) y perjudicial (50msinfinito). Se realizan medidas “in situ” de dos recintos de planta rectangular cuyas dimensiones son diferentes con el fin de evitar que los resultados estén determinados por el tamaño. La intención de nuestro estudio es validar los resultados experimentales frente a los obtenidos mediante modelos para así poder realizar un estudio en profundidad de cuáles son las propiedades que gobiernan la propagación del campo acústico en espacios cerrados. El software que se ha utilizado en este caso ha sido “EASE” a partir del cual se obtuvo un conjunto de respuestas impulsivas que posibilitaron un tratamiento equivalente al realizado con las experimentales. Los resultados obtenidos muestran gran similitud. Por lo que con la metodología empleada podremos a partir de ahora profundizar en el estudio de la propagación del campo acústico sin necesidad de realizar tediosas campañas de medidas “in situ” y con la posibilidad de realizar cambios “ad libitum” por ejemplo en la distribución de absorciones."
}
},
{
"@type":"ListItem",
"position":11,
"item": {
"@type":"ScholarlyArticle",
"headline":"Comportamiento vibroacústico de contenedores cilíndricos en aire",
"name":"Comportamiento vibroacústico de contenedores cilíndricos en aire",
"datePublished":"2018",
"author": [
{
"@type":"Person",
"givenName":"Francisco J.",
"familyName":"Rodrigo",
"name":"Francisco J. Rodrigo"
},
{
"@type":"Person",
"givenName":"Pedro",
"familyName":"Poveda",
"name":"Pedro Poveda"
},
{
"@type":"Person",
"givenName":"Jesús",
"familyName":"Carbajo",
"name":"Jesús Carbajo"
},
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
},
{
"@type":"Person",
"givenName":"Jaime",
"familyName":"Ramis",
"name":"Jaime Ramis"
}
],
"publication": {
"@type":"Periodical",
"name":"Tecniacústica 2018: 49º Congreso Español de Acústica; XI Congreso Iberoamericano de Acústica; X Congreso Ibérico de Acústica."
},
"abstract":"Este trabajo describe el procedimiento experimental llevado a cabo para estudiar el comportamiento radiante de la superficie de la base de estructuras en forma semilcilindro de 50 cm de diámetro y una superficie lateral de 15 cm de altura cuando son excitados mediante un actuador en el centro de la base. El nivel de vibración ha evaluado mediante acelerómetros de pequeño tamaño completando un detallado análisis modal. Las medidas de nivel de presión sonora se han realizado en una superficie cercana a la fuente y los datos se han procesado de acuerdo con la técnica de Holografia Acústica de Campo Cercano (NAH). Además de comparar los resultados de distintos materiales (acero y aluminio), se estudia la influencia de la condición de unión entre la superficie de la base y la superficie lateral de la estructura."
}
},
{
"@type":"ListItem",
"position":12,
"item": {
"@type":"ScholarlyArticle",
"headline":"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en catt-acoustic",
"name":"Campo directo (útil)/reverberado (perjudicial) resultados experimentales frente a simulación en catt-acoustic",
"datePublished":"2017",
"author": [
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
},
{
"@type":"Person",
"givenName":"Jenaro Vera",
"familyName":"Guarinos",
"name":"Jenaro Vera Guarinos"
},
{
"@type":"Person",
"givenName":"María Soledad Yebra",
"familyName":"Calleja",
"name":"María Soledad Yebra Calleja"
}
],
"publication": {
"@type":"Periodical",
"name":"Tecniacústica 2017: 48º Congreso Español de Acústica; Encuentro Ibérico de Acústica; European Symposium on Underwater Acoustics Applications; European Symposium on Sustainable Building Acoustics."
},
"abstract":"Basándonos en los resultados obtenidos en trabajos anteriores, se plantea el estudio del fenómeno desde el punto de vista de la simulación en un modelo tridimensional. Se comprueba que existe un paralelismo evidente entre los resultados de la simulación y lo experimental. Para ahondar en la cuestión se aplica el procedimiento en un recinto de menor tamaño y se extraen las consecuencias pertinentes sobre: validez, importancia de la geometría y disposición del mobiliario."
}
},
{
"@type":"ListItem",
"position":13,
"item": {
"@type":"ScholarlyArticle",
"headline":"Difusores acústicos basados en resonadores de membrana y placa",
"name":"Difusores acústicos basados en resonadores de membrana y placa",
"datePublished":"2019",
"author": [
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
}
],
"publication": {
"@type":"Periodical",
"name":"Universitat Politècnica de València. Departamento de Física Aplicada. Escuela Politécnica Superior de Gandia."
},
"abstract":"Los difusores acústicos tradicionales están basados en resonadores de cuarto de longitud de onda construidos con paneles ranurados. Es por ello que dichos paneles difícilmente pueden ser fabricados para trabajar en bajas frecuencias debido al elevado espesor resultante. Recientemente se ha propuesto el uso de metamateriales resonantes basados en resonadores de Helmholtz para reducir el espesor del panel, es decir, metadifusores. En este trabajo se propone el empleo de resonadores de placa y membrana para ir un paso más allá, consiguiendo controlar la reflexión del sonido empleando metasuperficies ultraplanas con un espesor mucho más pequeño que la longitud de onda."
}
},
{
"@type":"ListItem",
"position":14,
"item": {
"@type":"ScholarlyArticle",
"headline":"Estudio de la relación campo directo/reverberado; útil/perjudicial",
"name":"Estudio de la relación campo directo/reverberado; útil/perjudicial",
"datePublished":"2018",
"author": [
{
"@type":"Person",
"givenName":"José M.",
"familyName":"Requena-Plens",
"name":"José M. Requena-Plens"
}
],
"publication": {
"@type":"Periodical",
"name":"Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal."
},
"abstract":"La división entre campo directo y campo reverberante es correcta aunque en la práctica carece de utilidad, debido a que la fisiología del oído humano agrupa el campo directo y algunas de las primeras reflexiones haciendo creer a nuestro cerebro que todo ello constituye un solo sonido. Este concepto fue desarrollado por Hass (1951), donde se demuestra que hasta cierto tiempo todo el sonido recibido se integra y el cerebro lo procesa como un único sonido sin reflexiones y además ubica el origen del sonido en el lugar de donde se ha recibido el primer sonido. El tiempo definido por Hass para la comunicación hablada es de 50 milisegundos, es decir, todo sonido (directo y reflejado) hasta transcurridos los 50 milisegundos es integrado por el sistema auditivo humano y entendido como un único sonido, este concepto produjo que se utilizara más convenientemente la nomenclatura de campo directo, campo temprano (engloba todo sonido después del campo directo hasta los 50 ms) y campo reverberante (todo sonido después de los 50 ms). El campo reverberante definido como el campo comprendido desde los 50 milisegundos, llega después del tiempo en el que el oído humano integra el sonido como uno solo e interfiere en el sonido que se pretendía oír. Es por ello que los campos acústicos se pueden denominar como campo útil (campo directo y campo temprano) y campo perjudicial (campo reverberante desde los 50 ms). Teniendo en cuenta el concepto de campo útil y campo perjudicial y, entendiendo la importancia de la relación de éstos en la inteligibilidad de la palabra, se puede comprender la importancia de poder calcular matemáticamente los campos de la forma más correcta posible. Actualmente existen multitud de ecuaciones que si bien se aproximan al comportamiento experimental de los campos acústicos no son del todo correctos y por tanto no se pueden utilizar para prever el comportamiento. Los últimos cálculos desarrollados por Barron y Lee (1988) son de los pocos que tienen en cuenta una separación temporal para calcular matemáticamente el campo útil y perjudicial, aunque como se verá en este trabajo estos cálculos no se corresponden con el comportamiento real. Ante esta problemática se propone un cálculo modificado de los campos, basado en las ecuaciones de Barron y Lee e inspirado en la búsqueda de un ajuste en el cálculo de Sato y Bradley (2008), donde, a partir de una serie de medidas experimentales o mediante modelos acústicos, se comparan con el cálculo teórico de los campos útil y perjudicial y se buscan coeficientes de ajuste para obtener finalmente un cálculo teórico válido relacionando los coeficientes obtenidos con las características del recinto."
}
}
]
}
}
]
}
"Ultrasound Medical and Industrial Laboratory (UMIL)"
EducationalOrganization
name:
"Polytechnic University of Valencia (UPV)"
department:
"Higher Polytechnic School of Gandia (EPSG)"
EducationalOrganization
name:
"University of Alicante (UA)"
department:
"Higher Polytechnic School (EPS)"
EducationalOrganization
name:
"IES Salesianos (San José Artesano) & IES Luis García Berlanga"
hasOccupation:
Occupation
name:
"R&D Software Developer"
description:
"Firmware development for embedded systems (STM32 and ARM architectures) applied to power electronics, specifically for utility-scale inverters in renewable energy plants (Solar & Storage). Key contributions:
"
Occupation
name:
"Predoctoral researcher"
description:
"Researcher in the R&D line: Acoustic Metamaterials for Ultrasound Histotripsy treatments. Project: New generation of smart metasurfaces based on additive manufacturing for strategic applications in telecommunications (Metasmart). Funded by the Valencian Agency for Innovation (Reference: INNEST/2022/345). Some planned tasks:
"
Occupation
name:
"Predoctoral researcher"
description:
"The main objective is to conduct research and development of acoustic metamaterials for use in architectural applications and medical imaging. Goals achieved:
"
Occupation
name:
"Researcher in European project"
description:
"Implement and experimentally validate a sound mitigation method, applicable to a real space vehicle launch configuration (VEGA), that results in a significant decrease in sound pressure levels generated in the launch area during spacecraft liftoff. Project funded by ESA (European Space Agency) with reference ESA AO/1-9479/18/NL/LvH, in collaboration with: CNRS/Laboratoire d'Acoustique de la Université du Mans; COMET Ingeniería; Spanish National Research Council (CSIC) and Polytechnic University of Madrid. All project objectives were completed at 100%:"
Occupation
name:
"Research internship"
description:
"Internship in different research projects in the Applied Acoustics Group, belonging to the University Institute of Physics Applied to Sciences and Technologies of the Higher Polytechnic School of Alicante. Goals achieved:"
Occupation
name:
"Founder and Vocal Member"
description:
"Association based at the Higher Polytechnic School of the University of Alicante. Founded in 2016. Promotes project-oriented microcontroller programming knowledge. Activities performed:"
"Convert Unix timestamps to human-readable dates and vice versa. Supports seconds, milliseconds, ISO 8601, RFC 2822, timezone comparison, and auto-detection."
"MikroTik Honeypot: Trap & Auto-Block Port Scanners"
description:
"Configure a MikroTik honeypot to detect port scanners, log malicious activity, and auto-block attackers using firewall address lists and the RAW table."