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http://hdl.handle.net/2117/3363
Wed, 23 Jul 2014 01:45:10 GMT
20140723T01:45:10Z
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no

Active control of aircraft flyover sound transmission through an open window
http://hdl.handle.net/2117/23261
Title: Active control of aircraft flyover sound transmission through an open window
Authors: Pàmies Gómez, Teresa; Romeu Garbí, Jordi; Genesca Francitorra, Meritxell; Arcos Villamarín, Robert
Abstract: This paper presents an experimental work on active control of sound transmission through a restricted opening bottom hinged window. The main goal of the work is to demonstrate the feasibility of the active technique to limit the loss of attenuation due to the aperture of windows, and its application to aircraft flyover incident noise. The experimental window is placed in an exposed façade of a dwelling close to an airport and subject to flyby aircraft noise. The active control is configured to cancel the pressure at the aperture using a singleinput singleoutput feedforward adaptive system. As a result, a reduction of sound transmission is achieved with low power consumption. In global terms, an increase of almost 3 dB of transmission loss (with respect to the partially opened window insulation values) in the low frequency range (below 160 Hz and according to the National Danish Method for evaluating low frequency noise) is demonstrated, which is equivalent to a reduction of 50% in the loss of insulation caused by opening the window. © 2014 Elsevier Ltd. All rights reserved.
Wed, 18 Jun 2014 14:57:46 GMT
http://hdl.handle.net/2117/23261
20140618T14:57:46Z
Pàmies Gómez, Teresa; Romeu Garbí, Jordi; Genesca Francitorra, Meritxell; Arcos Villamarín, Robert
no
Acoustic insulation, Active noise control, Aircraft noise
This paper presents an experimental work on active control of sound transmission through a restricted opening bottom hinged window. The main goal of the work is to demonstrate the feasibility of the active technique to limit the loss of attenuation due to the aperture of windows, and its application to aircraft flyover incident noise. The experimental window is placed in an exposed façade of a dwelling close to an airport and subject to flyby aircraft noise. The active control is configured to cancel the pressure at the aperture using a singleinput singleoutput feedforward adaptive system. As a result, a reduction of sound transmission is achieved with low power consumption. In global terms, an increase of almost 3 dB of transmission loss (with respect to the partially opened window insulation values) in the low frequency range (below 160 Hz and according to the National Danish Method for evaluating low frequency noise) is demonstrated, which is equivalent to a reduction of 50% in the loss of insulation caused by opening the window. © 2014 Elsevier Ltd. All rights reserved.

Fast computation of an infinite, longitudinallyvarying and harmonic strip load acting on a viscoelastic halfspace
http://hdl.handle.net/2117/22264
Title: Fast computation of an infinite, longitudinallyvarying and harmonic strip load acting on a viscoelastic halfspace
Authors: Arcos Villamarín, Robert; Clot Razquin, Arnau; Romeu Robert, Jordi; Martín Román, SaraRegina
Abstract: In the context of the developing of a numerically efficient model of railway induced ground vibrations, the problem of an infinite, longitudinallyvarying and harmonic strip load acting on the surface of a viscoelastic halfspace is reformulated in order to improve its numerical evaluation. On one hand, the static integrands of this specific problem are modified and introduced into the original integrands to reduce their spectral content at high wavenumbers, saving computational time needed for the numerical integration. On the other hand, a change of variable is applied on the displacements integral solutions resulting on frequency independent integrands. These formulae allow to obtain the displacement solution in the complete xyω field easier and, mostly, faster
Tue, 18 Mar 2014 16:01:01 GMT
http://hdl.handle.net/2117/22264
20140318T16:01:01Z
Arcos Villamarín, Robert; Clot Razquin, Arnau; Romeu Robert, Jordi; Martín Román, SaraRegina
no
In the context of the developing of a numerically efficient model of railway induced ground vibrations, the problem of an infinite, longitudinallyvarying and harmonic strip load acting on the surface of a viscoelastic halfspace is reformulated in order to improve its numerical evaluation. On one hand, the static integrands of this specific problem are modified and introduced into the original integrands to reduce their spectral content at high wavenumbers, saving computational time needed for the numerical integration. On the other hand, a change of variable is applied on the displacements integral solutions resulting on frequency independent integrands. These formulae allow to obtain the displacement solution in the complete xyω field easier and, mostly, faster

A power flow analysis of a doubledeck circular tunnel embedded in a fullspace
http://hdl.handle.net/2117/21431
Title: A power flow analysis of a doubledeck circular tunnel embedded in a fullspace
Authors: Clot Razquin, Arnau; Romeu Garbí, Jordi; Arcos Villamarín, Robert; Martín Román, SaraRegina
Abstract: The purpose of the present investigation is to obtain the mean power flow radiated by a doubledeck 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 doubledeck 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 doubledeck tunnel reaching much higher values.
Mon, 03 Feb 2014 13:08:32 GMT
http://hdl.handle.net/2117/21431
20140203T13:08:32Z
Clot Razquin, Arnau; Romeu Garbí, Jordi; Arcos Villamarín, Robert; Martín Román, SaraRegina
no
Doubledeck tunnel, Power flow, Receptance method, Underground vibrations, Viscoelastic fullspace
The purpose of the present investigation is to obtain the mean power flow radiated by a doubledeck 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 doubledeck 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 doubledeck tunnel reaching much higher values.

Aircraft tracking by means of the Acoustical Doppler Effect
http://hdl.handle.net/2117/21112
Title: Aircraft tracking by means of the Acoustical Doppler Effect
Authors: Martín Román, SaraRegina; Genesca Francitorra, Meritxell; Romeu Garbí, Jordi; Pàmies Gómez, Teresa
Abstract: 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 onedimensional 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 soundpropagation 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.
Tue, 31 Dec 2013 10:42:13 GMT
http://hdl.handle.net/2117/21112
20131231T10:42:13Z
Martín Román, SaraRegina; Genesca Francitorra, Meritxell; Romeu Garbí, Jordi; Pàmies Gómez, Teresa
no
aircraft, tracking, Doppler effect, wideband crossambiguity function, timedelay, parameterestimation, sensor array, localization, altitude, targets, stretch, radar, engineering
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 onedimensional 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 soundpropagation 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.

Micromechanical damage in tool steels analyzed by acoustic emission technique
http://hdl.handle.net/2117/18640
Title: Micromechanical damage in tool steels analyzed by acoustic emission technique
Authors: Picas Anfruns, Ingrid; Martínez González, Eva; Casellas, Daniel; Romeu Garbí, Jordi
Abstract: 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.
Fri, 05 Apr 2013 11:01:05 GMT
http://hdl.handle.net/2117/18640
20130405T11:01:05Z
Picas Anfruns, Ingrid; Martínez González, Eva; Casellas, Daniel; Romeu Garbí, Jordi
no
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.

New siren tones optimised for increased detectability distances of emergency vehicles
http://hdl.handle.net/2117/18181
Title: New siren tones optimised for increased detectability distances of emergency vehicles
Authors: Balastegui Manso, Andreu; Romeu Garbí, Jordi; Clot Razquin, Arnau; Martín Román, SaraRegina
Abstract: 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.
Mon, 11 Mar 2013 16:09:47 GMT
http://hdl.handle.net/2117/18181
20130311T16:09:47Z
Balastegui Manso, Andreu; Romeu Garbí, Jordi; Clot Razquin, Arnau; Martín Román, SaraRegina
no
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.

Some analytical aspects of viscoelastic Lamb’s problem for improving its numerical evaluation
http://hdl.handle.net/2117/17598
Title: Some analytical aspects of viscoelastic Lamb’s problem for improving its numerical evaluation
Authors: Arcos Villamarín, Robert; Romeu Garbí, Jordi; Clot Razquin, Arnau; Genesca Francitorra, Meritxell
Abstract: Two analytical modifications of the original viscoelastic timeharmonic 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.
Thu, 07 Feb 2013 16:13:13 GMT
http://hdl.handle.net/2117/17598
20130207T16:13:13Z
Arcos Villamarín, Robert; Romeu Garbí, Jordi; Clot Razquin, Arnau; Genesca Francitorra, Meritxell
no
Two analytical modifications of the original viscoelastic timeharmonic 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.

On the use of a linear microphone array to measure wind turbine aerodynamic noise
http://hdl.handle.net/2117/17597
Title: On the use of a linear microphone array to measure wind turbine aerodynamic noise
Authors: Genesca Francitorra, Meritxell; Romeu Garbí, Jordi; Pàmies Gómez, Teresa; Solé, Jaume
Abstract: 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.
Thu, 07 Feb 2013 15:53:52 GMT
http://hdl.handle.net/2117/17597
20130207T15:53:52Z
Genesca Francitorra, Meritxell; Romeu Garbí, Jordi; Pàmies Gómez, Teresa; Solé, Jaume
no
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.

Acelerómetros y sensores de vibración
http://hdl.handle.net/2117/14718
Title: Acelerómetros y sensores de vibración
Authors: Romeu Garbí, Jordi; Genesca Francitorra, Meritxell
Fri, 20 Jan 2012 16:40:00 GMT
http://hdl.handle.net/2117/14718
20120120T16:40:00Z
Romeu Garbí, Jordi; Genesca Francitorra, Meritxell
no

Estimating the rate and luminosity function of all classes of GRBs
http://hdl.handle.net/2117/14357
Title: Estimating the rate and luminosity function of all classes of GRBs
Authors: Balastegui Manso, Andreu; Canal, Ramon; RuizLapuente, Pilar
Abstract: The aim of the present work is to estimate the rate and luminosity functions of short, intermediate and long gammaray bursts (GRBs) by fitting their intensity distributions wih parameterized explosion rates and luminosity functions. The results show that the parameters of the rate and luminosity function for long GRBs can be calculated with an accuracy of 1030%. However, some parameters of intermediate and short GRBs have large uncertainties. An important conclusion is that there was initially a large outburst in the frequency of long GRBs, and consequently a large outburst in the starformation rate, if they come from collapsars. Finally, a simulated intensity distribution has been constructed to test the ability of the method to recover the simulated parameters.
Thu, 29 Dec 2011 14:50:10 GMT
http://hdl.handle.net/2117/14357
20111229T14:50:10Z
Balastegui Manso, Andreu; Canal, Ramon; RuizLapuente, Pilar
no
The aim of the present work is to estimate the rate and luminosity functions of short, intermediate and long gammaray bursts (GRBs) by fitting their intensity distributions wih parameterized explosion rates and luminosity functions. The results show that the parameters of the rate and luminosity function for long GRBs can be calculated with an accuracy of 1030%. However, some parameters of intermediate and short GRBs have large uncertainties. An important conclusion is that there was initially a large outburst in the frequency of long GRBs, and consequently a large outburst in the starformation rate, if they come from collapsars. Finally, a simulated intensity distribution has been constructed to test the ability of the method to recover the simulated parameters.

Analysis of fracture resistance of tool steels by means of acoustic emission
http://hdl.handle.net/2117/12017
Title: Analysis of fracture resistance of tool steels by means of acoustic emission
Authors: Martínez González, Eva; Picas Anfruns, Ingrid; Casellas Padró, Daniel; Romeu Garbí, Jordi
Abstract: The automotive manufacturers currently use advanced highstrength steels (AHSS) to produce lightweight vehicles with increased safety performance. While showing excellent strengthtoweight 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.
Tue, 22 Mar 2011 13:06:33 GMT
http://hdl.handle.net/2117/12017
20110322T13:06:33Z
Martínez González, Eva; Picas Anfruns, Ingrid; Casellas Padró, Daniel; Romeu Garbí, Jordi
no
The automotive manufacturers currently use advanced highstrength steels (AHSS) to produce lightweight vehicles with increased safety performance. While showing excellent strengthtoweight 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.

Two step optimization of transducer locations in single input single output tonal global active noise control in enclosures
http://hdl.handle.net/2117/10176
Title: Two step optimization of transducer locations in single input single output tonal global active noise control in enclosures
Authors: Palacios Higueras, José Ignacio; Romeu Garbí, Jordi; Balastegui Manso, Andreu
Abstract: Global active control of sound can be achieved inside enclosures under low modal
acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed.
These strategies usually rely on partial approximation to the problem, focusing on the
study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated
acoustic field. It is also shown that in a real case, the optimum position is that of a
minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure.
Mon, 08 Nov 2010 14:25:47 GMT
http://hdl.handle.net/2117/10176
20101108T14:25:47Z
Palacios Higueras, José Ignacio; Romeu Garbí, Jordi; Balastegui Manso, Andreu
no
Global active control of sound can be achieved inside enclosures under low modal
acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed.
These strategies usually rely on partial approximation to the problem, focusing on the
study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated
acoustic field. It is also shown that in a real case, the optimum position is that of a
minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure.