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  • Optimal acoustic error sensing for global active control in a harmonically excited enclosure

     Romeu Garbi, Jordi; Balastegui Manso, Andreu; Pamies Gomez, Teresa; Arcos Villamarin, Robert
    Acoustical physics
    Date of publication: 2014-01-01
    Journal article

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    The performance of an active control system in global control of enclosed sound fields depends largely on the localization of the error sensors, among other factors. In this paper a modified cost function is proposed in order to guarantee the maximum attenuation that can be produced by a set of secondary sources in the case of an harmonically excited sound field. The cost function is modified in order to drive the error signal to the value corresponding to the optimally attenuated sound field, instead of minimizing the squared pressure. To evaluate the performance of the proposed control system, its robustness against unstructured error is also investigated using a set of intensive calculations. Following this approach, the sensors can be located anywhere and the optimal attenuation is reached using an equal number of error sensors and secondary sources. The results also suggest that the greater the number of error sensors than secondary sources the more robust the control system is. This behavior holds for both the usual strategy of minimizing the squared pressure and the approach presented in this paper. However, the latter strategy is more robust than the traditional approach of minimizing the squared pressures and its robustness does not depend on the location of the error sensors. Thus, as a main conclusion, the use of the new cost function leads to a guaranteed efficiency and a more robust control system and gives absolute freedom in selecting the location of the error sensors.

  • A power flow analysis of a double-deck circular tunnel embedded in a full-space

     Clot Razquin, Arnau; Romeu Garbi, Jordi; Arcos Villamarin, Robert; Martin Román, Sara-regina
    Soil dynamics and earthquake engineering (1984)
    Date of publication: 2014-02
    Journal article

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    The purpose of the present investigation is to obtain the mean power flow radiated by a double-deck circular tunnel and compares it to the one radiated by a simple circular tunnel. To achieve this, a harmonic line load is applied on the interior floor of the first one and at the bottom of the second one. For the double-deck tunnel, a new analytical model based on the receptance method is developed. The proposed model describes the dynamics of the interior floor using the thin plate theory and considers the Pipe in Pipe (PiP) model to describe the tunnel and soil coupled system. Plain strain conditions are assumed for both systems and conservative coupling is considered between them. Numerical results show significant differences between the power flow radiated by both tunnels, with the one radiated by the double-deck tunnel reaching much higher values. The effect of modifying the flexural rigidity of the interior floor is also presented. © 2013 Elsevier Ltd.

  • A dynamical model of a double-deck circular tunnel embedded in a full-space

     Clot Razquin, Arnau
    Defense's date: 2014-02-20
    Universitat Politècnica de Catalunya
    Theses

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    Aquesta tesis presenta un model dinàmic tridimensional d¿un túnel circular de dos pisos situat en el si d¿un espai infinit. El model fa ús del mètode de la receptància per a obtenir la resposta de l¿estructura completa a partir de la resposta de les seves parts. Els subsistemes considerats són, per una banda, el terra interior, i per l¿altra, el sistema acoblat túnel-terreny. El comportament dinàmic del primer es modelitza mitjançant la teoria clàssica de placa prima i el model Pipe-in-Pipe és l¿escollit per a descriure el segon. Com que el model proposat assumeix que el sistema és geomètricament invariant en la direcció de circulació dels trens, l¿acoblament dels subsistemes es pot realitzar en el domini nombre d¿ona-freqüència. Un cop el model ha estat formulat, es detallen els principals aspectes a tenir en compte en la seva computació numèrica i s¿interpreten els resultats obtinguts. La resposta d¿un túnel de dos pisos tant a una excitació dinàmica com a una de quasiestàtica es comparada a la resposta obtinguda en el cas d¿un túnel d'un únic pis. La primera comparativa es realitza mitjançant un estudi del flux de potència radiat per ambdues estructures sota l¿aplicació d¿una càrrega harmònica lineal. Les principals diferències entre les magnituds i els patrons de radiació són detallades i discutides. La segona comparativa es realitza calculant el flux total d¿energia que travessa una certa superfície del terreny quan una càrrega que es desplaça a velocitat constant es aplicada sobre ambdós túnels. La comparativa entre les respostes dels tunels es realitza per un ampli rang de velocitats. Finalment, es presenta un model complert de via-túnel-terreny obtingut a partir de l¿acoblament d¿un model de superestructura al model de túnel prèviament desenvolupat.

  • Analysis and design of a capillary driven blood plasma separation microfluidic device

     Madadi, Hojjat
    Defense's date: 2014-01-17
    Universitat Politècnica de Catalunya
    Theses

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    Recientemente, la aparición de dispositivos de laboratorio en un chip (Lab on a chip) ha generado una gran variedad de nuevas aplicaciones especialmente en análisis clínicos y diagnóstico. En particular, la falta de micro dispositivos adecuados para la separación del plasma de la sangre es una barrera para lograr un dispositivo portátil que pueda realizar una análisis de sangre. Con el fin de abordar esta cuestión, un microsistema auto impulsado que pueda obtener una cantidad importante de plasma sanguíneo de una gota de sangre seria un primer paso para un análisis de sangre miniaturizado. En esta tesis se utiliza PDMS (Polydimethylsiloxane ) como material de base para la fabricación del microdispositivo debido a su biocompatibilidad y su bajo coste. Uno de los rasgos característicos del dispositivo presentado es que trabaja solo con presión capilar que elimina la necesidad de fuentes externas. La presión capilar solicitada para conducir sangre a través del microdispositivo se obtiene mediante la modificación del PDMS mediante diferentes agentes tensioactivos, que se mezclan con PDMS pre - curado para lograr un carácter hidrófilo estable. El proceso de filtración se basará en una estructura de columnas con baja relación de aspecto. Estás estructuras se han analizado numéricamente, analíticamente y experimentalmente, para obtener un diseño con baja resistencia al flujo. En concreto, se ha diseñado un conjunto de microcolumnas base diamante ( dMIMP ) que se utilizará como bomba de alto rendimiento y baja resistencia al flujo (35.5 % menor que una bomba microcolumnas circulares ( cMIMP )). Para realizar esta caracterización se ha desarrollado un sistema de fabricación que permita caracterizar las estructruas de PDMS, a alta presión sin que se deformen. Por último, se ha utilizado el PDMS modificado y la bomba capilar optimizada para realizar un diseño de microfiltro de plasma sanguíneo de alto rendimiento. El microdispositivo presentado puede separar más de 0.11microL de plasma de una gota de sangre fresca humana ( 5microL ) sin la necesidad de fuerzas externas con una alta eficiencia ( más del 90 % ) y un tiempo razonable (de 3 a 5 minutos ). El volumen de plasma obtenido es suficiente para implementar diferentes tipos de test sanguíneo y por tant representa el primer paso hacia la creación de un punto de atención portàtil (POC, point of care).

  • Detection of Failure Mechanisms of Tool Steels by means of Acoustic Emission Technique

     Martinez González, Eva
    Defense's date: 2014-01-30
    Universitat Politècnica de Catalunya
    Theses

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    Aquesta tesi es centra en calibrar la tècnica d'emissió acústica (EA) per detectar i identificar mecanismes de dany en acersper eines. El procediment de mesura de l¿EA s'ha desenvolupat i calibrat per a dos assajos mecànics: assaig de flexió iassaig d¿indentació esfèrica.A l¿assaig de flexió es generen esquerdes a la superfície de la proveta degudes a la tensió de tracció màxima. El danys'inicia amb la nucleació d'esquerdes (trencament de carburs i deformació plàstica local) i després, les esquerdes espropaguen a través de la matriu metàl¿lica seguint els carburs trencats. La monitorització de l¿assaig amb EA, permetdetectar i identificar cada etapa de la fractura: el trencament de carburs i plastificació (nucleació), creixement de l¿esquerda através de la matriu d¿acer i la fallada catastròfica final de la mostra.L¿assaig d' indentació esfèrica permeten la creació d'una distribució de tensions en la part afectada de la mostra méscomplexa. Amb l¿ aplicació de càrregues baixes, es genera un camp de tensions en el rang elàstic sota l¿indentador esfèric.Durant els assajos, es va detectar activitat d'EA en aquest rang elàstic, i aquests senyals es relacionen amb la ruptura decarburs situats a la zona d'esforç tallant màxim. Una característica important d'aquest assaig és que la ruptura de carburs esporta a terme sense deformació plàstica, i per tant els senyals de dany es van identificar clarament amb el trencament decarburs.En ambdós assajos, el trencament dels carburs va ser confirmat per mitjà de la EA com causa de la nucleació d'esquerdesen acers per a eines. L¿EA va fer possible identificar el trencament de carburs i la propagació d'esquerdes a través de lamatriu metàl¿lica i predir la fractura final de la mostra en els assajos de flexió. Aquesta tesi proposa una nova configuracióde filtratge en assajos de fractura per eliminar senyals espúries a causa del dany provocat pel contacte entre la mostra i elssuports de la màquina, així com una metodologia per a l¿identificació de mecanismes de dany en mostres de mida petitasobre la base de certes característiques de la forma d'ona dels senyals d¿EA. Des del punt de vista de la recerca dematerials, l'acoblament d¿EA amb la configuració que es proposa en cada assaig millora significativament els resultatsobtinguts dels assajos, ja que permet identificar l'evolució del dany durant el cicle de càrrega. Els resultats experimentalsobtinguts avalen el possible ús de l¿EA en el manteniment preventiu d¿eines de conformat a la indústria

  • Application of a fast pre-calculated model for vibration impact assessment from underground trains to Metro Line 9 of Barcelona

     Balastegui Manso, Andreu; Arcos Villamarin, Robert; Romeu Garbi, Jordi; Pamies Gomez, Teresa
    Noise control engineering journal
    Date of publication: 2013-03
    Journal article

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    The prediction of vibration levels near underground trains is of growing importance for newly constructed infrastructures in cities. Before construction, preliminary studies of vibration impact need to be undertaken in order to identify the buildings that may be affected based on vibration contamination laws and modify the railway line or the type of superstructure if necessary. These studies need fast and economic models due to the large areas they need to cover. The present study aims at predicting the vibration impact for the new Line 9 of Barcelona Underground which is 48 km long. The solution presented is a fast pre-calculated 2D FEM model which is run once for a set of different soil types and tunnel depths, obtaining sets of surface vibration levels. Interpolating between the depths and distances of the tabulated results can be used as a very fast model for prediction. The model is calibrated with measurements in the same conditions (rolling stock and superstructure) as those expected in Line 9 and offers an accuracy not far from current 2.5D and 3D models.

  • Filtering of acoustic emission signals for the accurate identification of fracture mechanisms in bending tests

     Martinez González, Eva; Picas Anfruns, Ingrid; Romeu Garbi, Jordi; Casellas, Daniel
    Materials transactions
    Date of publication: 2013
    Journal article

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    In this manuscript, acoustic emission (AE) analysis is used to identify the fracture mechanisms that take place during a three-point bending test of steel specimens. However, an important source of AE was detected and related to the deformation of the supports and the surface of the steel specimen in contact. This source creates AE signals that are very high in number and amplitude, and prevent determining accurately the onset stress for fracture mechanisms in specimens. A signal filtering is proposed based on the properties of the initial part of the recorded AE waveform, combined with a linear localization. The filtering successfully allows the AE signals to be classified according to their source as background noise, damage due to contact of the specimen surface to the supports and fracture mechanisms occurring in the specimen microstructure as a result of the bending test. The aforementioned filter has been successfully applied in case of a cold work tool steel DIN 1.2379 to determine accurately the stress level at which the first damaging mechanisms start to occur in the microstructure in situ during the three-point bending test. Filtered AE signal results indicating damage in the microstructure have been corroborated by inspection of the specimen's surface in a Confocal Microscope. In default of using the proposed filter, unfiltered signals have been estimated to lead to an overestimation of critical stresses of about 20%, what is undesirable for most applications. © 2013 The Japan Institute of Metals and Materials.

  • Aircraft tracking by means of the Acoustical Doppler Effect

     Martin Román, Sara-regina; Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Pamies Gomez, Teresa
    Aerospace science and technology
    Date of publication: 2013-07
    Journal article

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    The present paper presents a passive acoustic method for aircraft tracking. The Acoustical Doppler Effect, characteristic of signals received by a mesh of spatially distributed microphones is the basis of the method. A one-dimensional version of the Ambiguity function permits the calculation of the frequency stretch factor that exists between the sound signals received by a pair of microphones. The expression for this frequency stretch is a function of the aircraft position and velocity which are estimated by a Genetic Algorithm. The method is suitable for all kinds of aircraft and requires only seven microphones plus the prior knowledge of only the aircraft position and velocity at a given time. Results are given for a simulation test of a 3D straight trajectory of the aircraft and for a sound-propagation model which considers geometrical spreading and atmospheric absorption of sound for a homogeneous medium. The influence of the atmospheric absorption is evaluated and the independence of the method with respect to microphone distribution is proven. The performance of the tracking method has also been evaluated in front of possible inaccuracy on the microphones synchronization.

  • Access to the full text
    New siren tones optimised for increased detectability distances of emergency vehicles  Open access

     Balastegui Manso, Andreu; Romeu Garbi, Jordi; Clot Razquin, Arnau; Martin Román, Sara-regina
    Applied acoustics
    Date of publication: 2013-06
    Journal article

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    Sirens from emergency vehicles are particularly annoying for people living in the vicinities of emergency centres. In order to reduce their discomfort, the present work computes the optimal output power and frequency content of the sirens by taking into account the car noise reduction, the background noise inside the car and the hearing threshold. The combination of these parameters gives rise to frequency windows where the sirens are more effective, hence new siren tones are proposed and their annoyance is assessed through a jury test procedure. The new tones can either increase the detectability distance by 40% without increasing their annoyance or reduce their sound pressure level by 3 dB while keeping their effectiveness in being detected. (C) 2013 Elsevier Ltd. All rights reserved.

    Sirens from emergency vehicles are particularly annoying for people living in the vicinities of emergency centres. In order to reduce their discomfort, the present work computes the optimal output power and frequency content of the sirens by taking into account the car noise reduction, the background noise inside the car and the hearing threshold. The combination of these parameters gives rise to frequency windows where the sirens are more effective, hence new siren tones are proposed and their annoyance is assessed through a jury test procedure. The new tones can either increase the detectability distance by 40% without increasing their annoyance or reduce their sound pressure level by 3 dB while keeping their effectiveness in being detected.

    Postprint (author’s final draft)

  • Measurement of aircraft noise in a high background noise environment using a microphone array

     Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Arcos Villamarin, Robert; Martin Román, Sara-regina
    Transportation research. Part D, transport and environment
    Date of publication: 2013-01
    Journal article

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  • Passive acoustic method for aircraft localization  Open access

     Martin Román, Sara-regina
    Defense's date: 2013-07-15
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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    The present thesis investigates a passive acoustic method to locate maneuvering aircraft. The method is based on the acoustical Doppler effect, as a particular effect of the signals received by a mesh of spatially distributed microphones. A one-dimensional version of the ambiguity function allows for the calculation of the frequency stretch factor that occurs between the sound signals received by a pair of microphones. The mathematical expression for this frequency stretch is a function of the aircraft position and velocity, both of them being estimated by a genetic algorithm. The method requires only a minimum of seven microphones and the prior knowledge of the aircraft position and velocity at a given time. The advantages of the method are that it is suitable for all kind of aircraft, not only propeller-driven, and is not restricted to low heights above the ground. Its applicability could be, for instance, to supplement aircraft noise monitoring systems or to supervise small airports activities. This doctoral research includes the theoretical background of the method as well as the detailed description of its implementation. To assess the performance of the method, results from computer simulations are discussed. First of all, noise propagation is considered in a lossless medium, thus only geometrical spreading influences the sound emitted by the source traveling to the receivers. The accuracy of each step of the method has been evaluated and the results obtained reveal acceptable performance. Due to the large distances between microphones and the aircraft in flight, the atmospheric attenuation plays a major roll. Therefore, computer simulations have also been carried out under the assumption of an homogeneous but non lossless medium to evaluate the influence of the atmospheric absorption on the aircraft location. Under these conditions, the performance of the method with respect to the microphone distribution is discussed. Moreover, the location method has also been tested for a possible inaccuracy on the microphones synchronization. Finally, an outdoor experimental validation of the acoustic method has been carried out with a radio control airplane. The description of the experimental test is detailed in the present work as well as the results obtained.

    La tesi desenvolupa, implementa i valida un mètode acústic per a la localització d’aeronaus. El mètode es basa en l’efecte Doppler que es percep en els registres de diferents micròfons distribuïts al voltant d’un aeroport. La versió u-dimensional de la funció d’ambigüitat permet el còmput del factor de compressió o expansió que sorgeix entre els registres freqüencials d’ un parell de micròfons. Aquest factor Freqüencial es pot expressar matemàticament en funció de la posició i velocitat de l’aeronau, que s’estimen en aquesta tesi a partir d’algoritmes genètics. El mètode només requereix de set micròfons i el coneixement previ de la posició de l’avió en un moment donat. Els principals avantatges del mètode són que és un mètode vàlid per qualsevol tipus d’aeronau, no només per avions d’hèlix o helicòpters, i que no restringeix a vols de baixa alçada. La seva aplicació podria ser, per exemple, complementar un sistema de monitorització de soroll aeri o bé supervisar l’activitat dels aeroports petits que no disposen de sistemes de radar. Aquesta investigació inclou el desenvolupament teòric del mètode així com la descripció detallada de la seva implementació. Per tal d’avaluar l’efectivitat del mètode, es presenten i analitzen resultats obtinguts a partir de diverses simulacions. Com a primer cas, es considera que el so es propaga en un medi conservatiu, és a dir, el so que es propaga des de la font fins als receptors només es veu afectat per l’atenuació geomètrica. Sota aquest model senzill de propagació, s’ha analitzat l’accuracy de cada un dels passos del mètode i els resultats obtinguts posen de manifest una bona ... del mètode. Tenint en compte que les distàncies entre els micròfons i l’avió en vol són llargues, l’atenuació atmosfèrica influeix també en la propagació del so emès per l’avió. Per tant, el segon cas de simulacions que s’han dut a terme considera un medi de propagació homogeni i no conservatiu amb l’objectiu d’avaluar la influència de l’atenuació atmosfèrica en la localització acústica de l’aeronau. Sota aquestes condicions, també s’ha analitzat l’eficàcia del mètode en funció de la distribució de micròfons. A més, el mètode de localització s’ha posat a prova sota possibles errors en la sincronització dels set micròfons. Finalment, s’ha dut a terme una validació experimental del mètode amb una avioneta de radio control al Club Aeronàutic Egara. La descripció d’aquest test experimental es detalla en la tesis així com els resultats obtinguts que demostren la validesa satisfactòria del mètode.

  • On the use of a linear microphone array to measure wind turbine aerodynamic noise

     Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Pamies Gomez, Teresa; Solé, Jaume
    Wind energy
    Date of publication: 2012-01-11
    Journal article

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    A linear microphone array is shown to be a simple tool to locate aerodynamic sound sources on a horizontal axis wind turbine. This paper discusses the capabilities and limitations of a linear microphone array to locate sound sources and measure aerodynamic noise on the blades of a horizontal axis wind turbine rotor. Compared with a planar microphone array, a linear array requires fewer microphones to achieve the same resolution, a simpler structure to support it and a simpler signal processing algorithm. For a linear array, areas exist in the rotor plane where the sources cannot be located unambiguously. For certain applications, it is not necessary to map the whole rotor plane. This paper also shows the result of an experimental test aimed at locating and measuring aerodynamic sound sources on the three blades of a wind turbine. Each blade received a different surface treatment, with the goal of comparing their relative sound emission levels. The test was carried out with a 10.32 m linear microphone array, placed horizontally near the ground, extending parallel to the rotor plane. The results show that for all three blades, most of the noise is generated in the outer 25% of the blade span, with a maximum occurring just after the blade has passed the horizontal position going downwards. Results also show that tripped blade is the noisiest of the three, whereas the smoothest, polished blade is clearly the quietest. Copyright © 2012 John Wiley & Sons, Ltd.

  • Impacto acústico generado como consecuencia de la implantación de un skate park

     Jimenez Diaz, Santiago; Romeu Garbi, Jordi; Alsina Sánchez, Antoni
    Congreso Ibero-americano de Acústica
    Presentation's date: 2012-10-02
    Presentation of work at congresses

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    Un skate park es una instalación singular formada por un conjunto de elementos y obstáculos, fuentes sonoras potenciales, que se imlpanta en un entorno urbano abierto. El estudio de impacto acústico de este tipo de actividad no se puede realizar por evaluación de una actividad respecto de los receptores será diferente en cada caso. El cálculo por simulación permite incluir todas estas variables, pero requiere tener previamente la potencia acústica radiada y la directividad de cada fuente sonora (actividad del patinador sobre el elemento y obstáculo) de que consta la instalación del skate park. Una vez caracterizadas las fuentes de ruido, usando los datos topográficos y meteorólogicos del lugar, se determinan mediante simulación informática, los niveles de inmisión sonora procedentes de las diferentes fuentes del skate park que llegan a la fachada de los receptores.

  • Micro-mechanical damage in tool steels analyzed by acoustic emission technique

     Picas, Ingrid; Martinez González, Eva; Casellas, Daniel; Romeu Garbi, Jordi
    Journal of acoustic emission
    Date of publication: 2012-12-30
    Journal article

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    The carbides in tool steels act as hard particles and dictate the wear resistance. The origin of failure of these steels is mostly related with the carbide cracking, as a nucleation site of final cracks. This paper shows the acoustic emission (AE) signals related with the nucleation (carbide cracking) and the crack growth (in the metallic matrix) during a monotonic bending test of a tool steel obtained by ingot metallurgy routes (DIN 1.2379). The paper presents a relationship between the frequency spectrum of AE signals obtained and the microscopic images during the test.

  • Aircraft noise-monitoring according to ISO 20906: evaluation of uncertainty derived from the human factors affecting event detection

     Asensio, Alberto; Ausejo, Miguel; Kambrosic, Kristian; Kang, Jiang; Moschioni, Giovanni; Pagán, R.; Pavón, I.; Romeu Garbi, Jordi; Trujillo, J. A.; Vigano, Giacomo; Ruiz Delgado, Manuel; Recuero López, Manuel
    Applied acoustics
    Date of publication: 2012
    Journal article

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  • Estudio micro-mecánico de daño en aceros para herramientas mediante la técnica de la emisión acústica

     Martinez González, Eva; Picas, Ingrid; Casellas, Daniel; Romeu Garbi, Jordi
    Revista de la Asociación Española de Ensayos No Destructivos
    Date of publication: 2012-09-01
    Journal article

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  • Analysis of fracture resistance of tool steels by means of acoustic emission

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    The e-journal and exhibition of non-destructive testing
    Date of publication: 2012-02-01
    Journal article

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  • Some analytical aspects of viscoelastic Lamb¿s problem for improving its numerical evaluation

     Arcos Villamarin, Robert; Romeu Garbi, Jordi; Clot Razquin, Arnau; Genesca Francitorra, Meritxell
    Wave motion
    Date of publication: 2012-08-27
    Journal article

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    Two analytical modifications of the original viscoelastic time-harmonic Lamb’s problem expressions are presented with the aim of improving their numerical integration efficiency. Firstly, a new change of variable in the Lamb’s problem integrands is proposed, which allows a standardization of the integration sampling vector and a complete spatialfrequency field solution after performing only one numerical integration/transformation. Secondly, the Lamb’s problem static integrands are modified and introduced into the original integrands to reduce their spectral content at high wavenumbers and, therefore, the sampling vector lengths needed to avoid aliasing.

  • CONTROL ACTIVO DE TRANSMISION DE RUIDO A TRAVES DE APERTURAS

     Pamies Gomez, Teresa; Balastegui Manso, Andreu; Arcos Villamarin, Robert; Romeu Garbi, Jordi
    Participation in a competitive project

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  • Actualització del mapa estratègic de soroll i proposta de mapa de capacitat acústica del municipi de Terrassa

     Llorens Baucells, Maria; Alsina Sánchez, Antoni; Latorre Raez, Josep; Romero Blasco, Jesús; López López, Susi; Jimenez Diaz, Santiago; Pamies Gomez, Teresa; Romeu Garbi, Jordi
    Date: 2012-10
    Report

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  • Actualització del mapa estratègic de soroll del municipi de Barberà del vallès

     González Balsera, Manuel; Suso, Jesús; Jimenez Diaz, Santiago; Pamies Gomez, Teresa; Romeu Garbi, Jordi
    Date: 2012-11
    Report

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  • On the power and frequency of auditory signals on emergency vehicles

     Balastegui Manso, Andreu; Romeu Garbi, Jordi; Clot, Arnau; Martin Román, Sara-regina
    International Congress and Exposition on Noise Control Engineering
    Presentation's date: 2011-09
    Presentation of work at congresses

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  • Determination of the near field distance for point and line sources acting on the surface of an homogeneous and viscoelastic half-space

     Arcos Villamarin, Robert; Romeu Garbi, Jordi; Balastegui Manso, Andreu; Pamies Gomez, Teresa
    Soil dynamics and earthquake engineering (1984)
    Date of publication: 2011
    Journal article

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    Contaminació acústica  Open access

     Romeu Garbi, Jordi; Jimenez Diaz, Santiago
    Date of publication: 2011
    Book chapter

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  • Active control of sound transmission through an aperture

     Pamies Gomez, Teresa
    Defense's date: 2011-07-18
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • A model for railway induced ground vibrations in the frame of preliminary assessment studies  Open access

     Arcos Villamarin, Robert
    Defense's date: 2011-07-13
    Department of Mechanical Engineering, Universitat Politècnica de Catalunya
    Theses

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    This thesis focuses on the development of an analytical model for the generation and propagation parts of a global model of ground induced vibrations to be used in preliminary assessment studies for the case of at-grade railway infrastructures. The model is designed prioritising its speed, simplicity and usability ahead its accuracy modelling the real railway system. This model takes into account the subgrade as a viscoelastic and homogeneous half-space, the superstructure as a 2-layer supporting model and the vehicle as 1DOF system. With the aim of simplify the model, the superstructure/subgrade interaction is studied in terms of the wheel/rail contact dynamics, bounding in what cases this interaction can be neglected. The adaptation of this model when a far eld semi-analytical model is desired to be used as the propagation model is fully developed, by means of the dimensioning of the near eld and far eld regions.

  • Mapa estratègic de soroll de la ctra. BV-5001 entre els P.Q. 0 i 19+885

     Jimenez Diaz, Santiago; Romeu Garbi, Jordi
    Date: 2011-04
    Report

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  • TECCOL11-1-0007-15

     Romeu Garbi, Jordi
    Participation in a competitive project

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  • Street categorization for the estimation of day levels using short-term measurements

     Romeu Garbi, Jordi; Genesca Francitorra, Meritxell; Pamies Gomez, Teresa; Jimenez Diaz, Santiago
    Applied acoustics
    Date of publication: 2011-07
    Journal article

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  • Sound radiation from an aperture in a rectangular enclosure under low modal conditions

     Pamies Gomez, Teresa; Romeu Garbi, Jordi; Genesca Francitorra, Meritxell; Balastegui Manso, Andreu
    Journal of the Acoustical Society of America
    Date of publication: 2011-07
    Journal article

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  • Passive acoustic method for tracking moving sound sources

     Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Pamies Gomez, Teresa; Balastegui Manso, Andreu
    Acta acustica united with acustica
    Date of publication: 2011-01
    Journal article

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  • Aplicación de la Emisión Acústica (EA) al estudio del comportamiento micro-mecánico de los AHSS

     Martinez González, Eva; Romeu Garbi, Jordi; Picas Anfruns, Ingrid; Casellas Padro, Daniel
    Congreso Nacional de Ingeniería Mecánica
    Presentation's date: 2010-11-04
    Presentation of work at congresses

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  • Planes específicos para la reducción de la contaminación acústica de la ciudad de Terrassa

     Jimenez Diaz, Santiago; Romeu Garbi, Jordi; Genesca Francitorra, Meritxell; Alsina Sánchez, Antoni
    Congreso Nacional de Acústica
    Presentation's date: 2010-10-14
    Presentation of work at congresses

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  • Access to the full text
    Recreation noise in acoustic mapping  Open access

     Romeu Garbi, Jordi; Jimenez Diaz, Santiago; Genesca Francitorra, Meritxell; Sanchez Venegas, Angel
    International Congress and Exposition on Noise Control Engineering
    Presentation's date: 2010-06-16
    Presentation of work at congresses

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    As far as most of citizens complains are about noise coming from recreational activities, usually related with the presence of people in the street around bars, pubs, parties and other activities carried out in public spaces, it seems reasonable to include this kind of noise source in the strategic noise maps, especially if the main objective of the noise mapping is to draw action plans. A methodology is proposed to analyze that kind of noise environments including short-term and long-term measurements, obtaining the acoustic indicators Ln and Lden as well as number of people exposed to those indicators. The results obtained in six different cities show that similar trends can be found for commercial streets in different cities, showing an increase of 5 dBA in Leq between 5 p.m and 8 p.m compared to the average value of Leq during the rest of day time. Night recreational noise seems more variable and an in field study must be carried out. It has also been found that around 10% of population is exposed to noise coming from commercial streets.

  • Access to the full text
    A ground-borne vibration assessment model for rail systems at-grade  Open access

     Cardona, J.; Romeu Garbi, Jordi; Arcos Villamarin, Robert; Balastegui Manso, Andreu
    International Congress and Exposition on Noise Control Engineering
    Presentation's date: 2010-06-16
    Presentation of work at congresses

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    Due to the increasing number and kilometres of new railways lines, either high speed railway lines or commuter lines, as well as the increasing in human sensitivity versus ground-borne vibration generated for this mean of transport, a sustained growth in complaints due to the annoyance caused by railway vibrations has been detected. In order to predict the field vibrations caused by new railway lines in the project stage, which will be useful to design appropriate countermeasures, in the present work a ground-borne vibration model for rail systems at-grade developed by the authors is validated with experimental measurements in an existing commuter railway line. It checked that this model is a very useful tool to predict the vibration field that will be caused by a railway infrastructure in the planning stage of the project.

  • Integral curriculum on noise control in Spain: a cooperative task

     Romeu Garbi, Jordi; Genesca Francitorra, Meritxell; Pamies Gomez, Teresa
    International Congress on Acoustics
    Presentation's date: 2010-08-25
    Presentation of work at congresses

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    Analysis of fracture resistance of tool steels by means of acoustic emission.  Open access

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    European Conference on Acoustic Emission
    Presentation's date: 2010-09-09
    Presentation of work at congresses

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    The usage of advanced high strength steels (AHSS) in structural automotive components has been broadened in the past few years to satisfy the strict specifications of the automotive industry. Besides showing excellent strength to weight rations, AHSS have several limitations due to the high loads required in cold forming and cutting tools, which decrease considerably the tooling performances. Therefore, these important forces of impact provoke unforeseen breakage of the dies. The aim of this research is to study the micromechanical behaviour and fracture mechanisms (nucleation and crack propagation) during fracture of tool steels using the acoustic emission (EA) technique. To do that, bending testing specimens of different tool steels were monitored in order to establish a relationship between AE signals and their mechanical behavior (carbide breakage, cracks emanating from them and crack propagation through the metallic matrix).

  • A measurement method to discriminate aircraft fly-over noise

     Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Pamies Gomez, Teresa
    International Congress on Acoustics
    Presentation's date: 2010-08-26
    Presentation of work at congresses

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  • Mapas estratégicos de ruido en Catalunya

     Jimenez Diaz, Santiago; Romeu Garbi, Jordi; Pamies Gomez, Teresa; Majó Torrent, Maite
    Congreso Nacional de Acústica
    Presentation's date: 2010-10-15
    Presentation of work at congresses

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  • Agglomeration noise strategic maps in Catalonia

     Jimenez Diaz, Santiago; Romeu Garbi, Jordi; Pamies Gomez, Teresa; Majó, Maite
    International Congress and Exposition on Noise Control Engineering
    Presentation's date: 2010-06-15
    Presentation of work at congresses

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  • Analysis of fracture resistance of tool steels by means of acoustic emission

     Martinez González, Eva; Picas Anfruns, Ingrid; Casellas Padro, Daniel; Romeu Garbi, Jordi
    Journal of acoustic emission
    Date of publication: 2010-12-10
    Journal article

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    The automotive manufacturers currently use advanced high-strength steels (AHSS) to produce lightweight vehicles with increased safety performance. While showing excellent strengthto-weight ratios, AHSS have several limitations due to the high loads required in cold forming and cutting processes, which lead to accelerated wear and premature fracture of tools. Thus, new tool materials with improved mechanical behavior ought to be developed with regard to the tool failure mechanisms. The aim of this work is to shed light on the fracture mechanisms acting in tools (i.e. crack nucleation and propagation) applying the acoustic emission (AE) technique. Bending tests using two different tool steels were monitored in order to establish a relationship between AE signals and fracture events.

  • Aircraft noise monitoring with linear microphone arrays

     Genesca Francitorra, Meritxell; Romeu Garbi, Jordi; Pamies Gomez, Teresa; Sanchez Venegas, Angel
    IEEE aerospace and electronic systems magazine
    Date of publication: 2010-01
    Journal article

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  • Acelerómetros y sensores de vibración

     Romeu Garbi, Jordi; Genesca Francitorra, Meritxell
    Automática e instrumentación
    Date of publication: 2010-04
    Journal article

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  • Control structures and optimal sensor/actuator allocation: application in active noise control  Open access

     Cuguero Escofet, Miquel Àngel
    Defense's date: 2010-03-05
    Department of Automatic Control, Universitat Politècnica de Catalunya
    Theses

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    Aquesta tesi presenta treball original i aplicat en l'àrea del control i la col·locació de sensors/actuadors (S/A) en sistemes de Control Actiu de Soroll (ANC). Primer, s'han aplicat tècniques de control i identificació robustes per a aconseguir ANC. La fase d'identificació està basada en una proposta d'identificació robusta orientada al control, considerant descripcions del sistema tant paramètriques com no-paramètriques, així com quantificant la incertesa. El disseny del controlador compara les estructures de control feedback (FB), feedforward (FF) i híbrida (FB/FF). El controlador feedback és sintetitzat i avaluat en el marc del control robust, i s'ha dissenyat utilitzant control òptim H∞ plantejat com un problema de sensibilitats mixtes. El controlador FF és un identificador adaptatiu, basat en l'algorisme σ robustament normalitzat. S'han desenvolupat dues propostes per a decidir quina de les estructures de control és més eficient, aplicades a un conducte de 4 metres amb soroll de banda ampla. A més a més, s'han mostrat de manera explícita els compromisos entre identificació i control, les limitacions inherents a un llaç de control feedback, així com qüestions relatives a la implementació de sistemes ANC. També s'han tractat altres qüestions com la relació entre acompliment, ordre del controlador, models paramètrics/no-paramètrics i implementació en processadors digitals de senyal (DSP), així com s'han comparat resultats teòrics i experimentals en el conducte. Les llacunes que encara resten entre teoria i pràctica en aquest tipus d'aplicacions també s'han resumit. D'altra banda, en aquest treball també es tracta el problema de com quantificar la col·locació de sensors i actuadors, amb la finalitat de controlar un sistema físic determinat. La mesura per a determinar la millor localització de S/A es basa en un criteri de llaç tancat orientat al control, el qual optimitza tant acompliment com qüestions pràctiques d'implementació. Aquesta mesura hauria de calcular-se abans del disseny, implementació i prova del controlador. La utilització d'aquesta mesura minimitza la prova combinatòria de controladors en totes les possibles combinacions de S/A. Per a aconseguir-ho, s'han definit diferents mesures que pesen l'acompliment potencial en llaç tancat, la robustesa, el número de condició de la planta (guanys relatius entrada/sortida (I/O)) així com altres qüestions d'implementació, com l'ordre del controlador. Aquestes poden calcular-se utilitzant software estàndard, tant per a models d'una-entrada-una-sortida (SISO) com per a models de múltiples-entrades-múltiples-sortides (MIMO) i poden aplicar-se a múltiples problemes d'enginyeria, ja siguin mecànics, acústics, aeroespacials, etc. En aquest treball, aquests resultats també s'han il·lustrat amb l'aplicació ANC presentada i validat amb dades experimentals. Com a resultat d'aplicar aquestes mesures, s'obté la localització de S/A que aconsegueix la millor atenuació del soroll en llaç tancat amb el menor ordre possible del controlador.

    Esta tesis presenta trabajo original y aplicado en el área del control y la colocación de sensores/actuadores (S/A) en sistemas de Control Activo de Ruido (ANC). Primero, se han aplicado técnicas de control e identificación robustas para conseguir ANC. La fase de identificación está basada en una propuesta de identificación robusta orientada al control, considerando descripciones del sistema tanto paramétricas como no-paramétricas, así como cuantificando la incertidumbre. El diseño del controlador compara las estructuras de control feedback (FB), feedforward (FF) e híbrida (FB/FF). El controlador feedback es sintetizado y evaluado en el marco del control robusto, y se ha diseñado utilizando control óptimo H∞ planteado como un problema de sensibilidades mixtas. El controlador FF es un identificador adaptativo, basado en el algoritmo σ robustamente normalizado. Se han desarrollado dos propuestas para decidir cual de las estructuras de control es más eficiente, aplicadas a un conducto de 4 metros con ruido de banda ancha. Además, se han mostrado de manera explícita los compromisos entre identificación y control, las limitaciones inherentes a un lazo feedback, así como cuestiones relativas a la implementación de sistemas ANC. También se han tratado otras cuestiones como la relación entre desempeño, orden del controlador, modelos paramétricos/no-paramétricos e implementación en procesadores digitales de señal (DSP), así como se han comparado resultados teóricos y experimentales en el conducto. Las lagunas que aún quedan entre teoría y práctica en este tipo de aplicaciones también se han resumido. Por otra parte, en este trabajo se trata también el problema de como cuantificar la colocación de sensores y actuadores, con la finalidad de controlar un sistema físico determinado. La medida para determinar la mejor localización de S/A se basa en un criterio de lazo cerrado orientado al control, el cual optimiza tanto desempeño como cuestiones prácticas de implementación. Esta medida debería calcularse antes del diseño, implementación y prueba del controlador. La utilización de esta medida minimiza la prueba combinatoria de controladores en todas las posibles combinaciones de S/A. Para conseguirlo, se han definido distintas medidas que pesan el desempeño potencial en lazo cerrado, la robustez, el número de condición de la planta (ganancias relativas entrada/salida (I/O)) y otras cuestiones de implementación, como el orden del controlador. Éstas pueden calcularse utilizando software estándar, tanto para modelos de una-entrada-una-salida (SISO) como para modelos de múltiples-entradas-múltiples-salidas (MIMO) y pueden aplicarse a múltiples problemas ingenieriles, ya sean mecánicos, acústicos, aeroespaciales, etc. En este trabajo, estos resultados también son ilustrados con la aplicación ANC presentada y validados con datos experimentales. Como resultado de aplicar estas medidas, se obtiene la localización de S/A que consigue la mejor atenuación de ruido en lazo cerrado con el menor orden posible del controlador.

    This thesis presents novel and applied work in the area of control and sensor/actuator (S/A) allocation in Active Noise Control (ANC) systems. First, robust identification and control techniques to perform ANC have been applied. The identification phase is based on a control-oriented robust identification approach that considers both parametric and nonparametric descriptions of the system, and quantifies the uncertainty. The controller design compares the feedback (FB), feedforward (FF) and hybrid (FB/FF) control structures. The feedback control is synthesized and evaluated in the robust control framework, and it is designed using H∞ optimal control as a mixed-sensitivity problem. The FF controller is an adaptive identifier, based on the robustly normalized σ-algorithm. Two approaches are developed to decide which control structure is more efficient on a 4-m duct example with broadband noise. In addition, the compromises between identification and control, the inherent limitations of feedback and implementation issues in ANC are explicitly pointed out. Relations between performance, controller order, parametric/nonparametric models and digital signal processor (DSP) implementation are discussed. Theoretical and experimental results on the duct are compared. The gaps that still remain between theory and practice in this type of applications, are also outlined. Furthermore, this work considers the problem of quantifying the location of sensors and actuators in order to control a certain physical system. The measure to determine the best S/A location is based on a closed loop control-oriented criteria, which optimizes overall performance and practical implementation issues. In addition, it should be computed before the actual controller is designed, implemented and tested. The use of this measure minimizes the combinatorial controller testing over all possible S/A combinations. To this end, several measures have been defined which weight the potential closed-loop performance, robustness, plant condition number (input/output (I/O) relative gains) and implementation issues, such as the controller order. These may be computed with standard software, either for Single Input Single Output (SISO) models or Multiple Input Multiple Output (MIMO) models, and may be applied to many engineering problems: mechanics, acoustics, aerospace, etc. Here, these results are also illustrated with the prior ANC example and validated against experimental data. The outcome of applying these measures is the selection of the S/A location which achieves the best closed loop noise attenuation with the lowest possible controller order.