Julien MAILLARD | CSTB - Academia.edu (original) (raw)

Papers by Julien MAILLARD

Le present rapport presente un bilan du projet Ville numerique, l'un des quatre projets de re... more Le present rapport presente un bilan du projet Ville numerique, l'un des quatre projets de recherche de la priorite scientifique et technique "Simulations et outils numeriques" du programme de recherche 2010-2013 du CSTB. Le projet Ville numerique integre des travaux sur la simulation et la representation des phenomenes a l'echelle du quartier et de la ville. Il vient completer les projets Referentiel numerique et Simbio qui traitent des echelles composants et bâtiment, respectivement, au sein de la meme priorite. On presente dans une premiere partie le contexte et les enjeux de la recherche menee dans le cadre du projet Ville numerique. La deuxieme partie fournit les principaux resultats et avancees obtenues durant la periode 2012-2013. Les perspectives de cette recherche sont abordees dans une troisieme partie. // The following research report presents an overview of work carried out in the frame of the CSTB project "Ville Numerique". "Ville Numeri...

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Le bruit des transports ferroviaires est compose de plusieurs contributions sonores. Le bruit de ... more Le bruit des transports ferroviaires est compose de plusieurs contributions sonores. Le bruit de roulement, genere par la roue et le rail, represente la source principale pour les vitesses de circulation comprises entre 50 et 300 km/h. Le travail presente dans cet article concerne le developpement d'une methode de simulation auditive du bruit de roulement ferroviaire et traite plusparticuli erement le bruitemisbruit´bruitemis par le rail. Les travaux existants sur le sujet modelisent generalement la contribution du rail par une source ponctuelle situee au point de contact roue/rail. Cette approximation n'est pas toujours valide en particulier dans les hautes frequences pour lesquelles le rayonnement acoustique du rail s'´ etend sur une distance importante. L'approche proposee ici utilise un modele etendu base sur une ligne de monopoles. Les caracteristiques du champ acoustique rayonne par le rail sont presentees ainsi que la technique de synthese proposee. Les result...

Long-term averaged noise indicators are commonly used for designing and sizing protections, and t... more Long-term averaged noise indicators are commonly used for designing and sizing protections, and to satisfy existing regulations for railway infrastructures. These long-term indicators allow to assess the exposure of populations to environmental noise and, in turn, evaluate health related effects. However, long-term indicators may not correlate well with noise perception by residents. In case of highspeed train pass-by, for example, short-term indicators are more directly linked to the high variation of noise level during a short event. For rolling stock characterization, indicators such as LAeq,Tp, SEL, TEL and LA,max are commonly used during the design phase and the validation of the rolling stock. As an extension, such indicators, including LAeq,Te, may also be used to assess the noise perceived by residents for single pass-by events. In this context, a new calculation scheme, compatible with existing normative methods in France and Europe, has been developed for predicting event-related noise indicators in complex environments, under varying meteorological conditions. The standard prediction methods are adapted to obtain the time-dependent sound pressure level during the train pass-by and then derive the different short-term indicators. This paper presents a validation study comparing measured and calculated short term indicators according to current engineering methods. Results are given for different trains and speeds as well as different sites and receiver configurations.

CSTB has successfully developed the electroacoustic system CARMEN which enhances the reverberatio... more CSTB has successfully developed the electroacoustic system CARMEN which enhances the reverberation in concert halls for classical music with high sound quality. The requirement for a more cost-effective solution to satisfy the constraints of smaller multi-purpose halls led to further research. A new system called Carmencita uses some of the CARMEN features such as the Virtual Wall Principle built up by several cells (defined by a loudspeaker, DSP and microphone) but also adds other improvements such as electronic reverberation and the use of a signal matrix. The signal matrix is created using a dedicated network. The Carmencita algorithms have been first programmed in ProTools and, once tested, a specific DSP-card has been developed. This more complex structure will allow an easier installation with fewer cells and less cable wiring requirements. A Carmencita test installation with only 8 cells has been done at La Rampe (France). The test results are shown and discussed. Comparison ...

Exposure to excessive noise is correlated with higher rates of annoyance, sleep disturbance, and ... more Exposure to excessive noise is correlated with higher rates of annoyance, sleep disturbance, and other negative health outcomes. Accurately calculating road noise in complex urban environments is fundamental to assessing potential noise mitigation devices and reducing overall noise exposure. However, computing sound propagation in this setting is difficult because cities have complicated geometries and large domains. For example, engineering methods such as ISO-9613-2 or NMPB 2008 efficiently estimate sound levels but cannot model complex geometries like a T-barrier. In addition, detailed approaches such as the boundary element method or the finite-difference time-domain method produce precise results for any geometry but rapidly become too expensive as the frequency and domain size increase. Using a hybrid formulation alleviates these problems. Specifically, the boundary element method yields a table of the corrections for the domain's involved structures for a range of source ...

This paper presents recent validation results of a new auralization approach for non-stationary u... more This paper presents recent validation results of a new auralization approach for non-stationary urban traffic noise. The technique uses a real time granular synthesis algorithm to construct the source signals of engine and tire emission noise. Vehicles moving with arbitrary engine and speed variations can thereby be auralized dynamically. Acoustic propagation effects between sources and listener position are modeled based on standard engineering propagation methods with individual 3D rendering of perceptually important propagation paths and diffuse rendering of the summed remaining contributions. Perceptual validation tests of the granular synthesis approach are discussed. Results of the comparison of pass-by noise sequences obtained from on-site recordings and from the auralization approach modeling the same site are also discussed. The chosen site, an urban street, includes two types of road surface types. The auralized sequences based on equivalent traffic conditions also include additional road surfaces as well as a low noise barrier. Pass-by noise levels obtained on auralized sequences are compared to on-site measured levels.

Dans cet article, l'amélioration de l'indice d'affaiblissement acoustique d'une demi-cloison (pla... more Dans cet article, l'amélioration de l'indice d'affaiblissement acoustique d'une demi-cloison (plaques de plâtre sur une ossature métallique) en basses fréquences par un système de contrôle actif est étudiée théoriquement et expérimentalement. La demi-cloison sépare la salle d'émission et la salle de réception. Le principe de la simulation est basé sur la méthode découplée de GRIM développée par le CSTB ; la demi-cloison est modélisée par la méthode d'éléments finis avec le logiciel Nastran. La simulation permet d'évaluer l'influence du type de sources de contrôle (monopole ou dipôle), du nombre de sources de contrôle, du temps de réverbération dans la salle d'émission. Le système expérimental combine des haut-parleurs comme source de contrôle et des microphones pour les signaux d'erreur. Chaque cellule de contrôle (haut-parleur/microphone) est positionnée régulièrement avec un maillage de 60x60 cm 2 devant la demi-cloison excitée par un champ diffus. Le contrôle actif est implémenté par un système monocanal sur chaque cellule. La vitesse vibratoire de la demicloison, l'intensité transmise sont notamment mesurées pour analyser les mécanismes du contrôle actif.

Organization, 1998

Fluid-borne vibrations in piping systems remains a serious problem in applications such as marine... more Fluid-borne vibrations in piping systems remains a serious problem in applications such as marine vessels where mechanical fatigue and radiated noise are critical factors. In the case of pumps or hydraulic engines, the main source of vibrational energy is in the fluid axisymmetric plane wave associated with the system pressure pulsations. Due to fluid/structure coupling, this wave propagates in both the pipe wall and fluid. For high levels of pressure pulsations, the resulting radial and axial wall motion can then cause mechanical fatigue and unwanted radiated noise. Passive pulsations dampers have been used traditionally to reduce the fluid pressure pulses. The use of such passive devices is limited however in critical applications due to the resulting static pressure loss which decreases the system performance. This report describes the design and testing of a non-intrusive fluid wave actuator for the active control of pressure pulses. The actuator consists of a circumferential ring of PZT stacks acting on the pipe outside wall to generate an axisymmetric plane wave in the fluid through radial motion coupling. After briefly describing a simplified model of the actuator along with predicted performances, experimental results will show the control performance of the actuator applied to the discharge line of an oil driven hydraulic engine.

The Journal of the Acoustical Society of America, 1993

The Journal of the Acoustical Society of America, 2012

An algorithm for the real time synthesis of internal combustion engine noise is presented. Throug... more An algorithm for the real time synthesis of internal combustion engine noise is presented. Through the analysis of a recorded engine noise signal of continuously varying engine speed, a dataset of sound samples is extracted allowing the real time synthesis of the noise induced by arbitrary evolutions of engine speed. The sound samples are extracted from a recording spanning the entire engine speed range. Each sample is delimitated such as to contain the sound emitted during one cycle of the engine plus the necessary overlap to ensure smooth transitions during the synthesis. The proposed approach, an extension of the PSOLA method introduced for speech processing, takes advantage of the specific periodicity of engine noise signals to locate the extraction instants of the sound samples. During the synthesis stage, the sound samples corresponding to the target engine speed evolution are concatenated with an overlap and add algorithm. It is shown that this method produces high quality audio restitution with a low computational load. It is therefore well suited for real time applications.

The Journal of the Acoustical Society of America, 1992

The Journal of the Acoustical Society of America, 1998

A numerical study comparing the use of two structural sensing approaches for sound radiation cont... more A numerical study comparing the use of two structural sensing approaches for sound radiation control is performed on a baffled rectangular plate. The first sensing approach implements an array of accelerometers whose outputs are filtered to construct an estimate of the sound pressure radiated at given angles in the far field. The second method uses the same array of point sensors to estimate the net volume acceleration of the plate. Results show the improved performances of the sensor observing far-field sound radiation over a volume acceleration based on sensor.

Dans le cadre de recherches sur le rendu sonore dynamique d'environnements complexes, nous propos... more Dans le cadre de recherches sur le rendu sonore dynamique d'environnements complexes, nous proposons une nouvelle méthode de classification des chemins acoustiques entre une source et un auditeur placés dans un environnement virtuel. La propagation du sonà l'intérieur de cette scène est représentéeà l'aide d'un graphe de réflexions. Chaque noeud de ce graphe bidirectionnel représente une réflexion du son sur un deséléments de la scène, la source du graphe représentant la source sonore et le puits, l'auditeur. Le processus de restitution spatialisée reste aujourd'hui la partie la plus complexeà réaliser en temps réel ; c'est pourquoi il est essentiel de réduire le nombre de contributions, i.e., le nombre de chemins de notre graphe. Un modèle psycho-acoustiques aété créé en prenant en compte les phénomènes de masquage spatial et temporel des chemins sonores.À partir de ces données, les chemins sont agrégés en paquets nécessitant une seule opération de spatialisation, celle du chemin prédominant dans le groupe.

The Journal of the Acoustical Society of America, 1994

This paper discusses new work concerned with developing structural sensors and associated signal ... more This paper discusses new work concerned with developing structural sensors and associated signal processing techniques that provide time domain estimates of far-field pressure or structural wave-number information. The sensor arrangement consists of multiple accelerometers whose outputs are passed through an array of linear filters. The impulse response of each filter is constructed from the appropriate Green's function for the elemental source area associated with each sensor. The outputs of the filter array are then summed in order to predict far-field pressure or wave-number information somewhat analogous to the well-known boundary element technique. A major significance of the approach is that it provides time domain information and can thus be efficiently applied to active structural acoustic control approaches.

Proceedings of the ICA congress, 2019

Railway noise contributes significantly to noise pollution both outside and within cities. In rec... more Railway noise contributes significantly to noise pollution both outside and within cities. In recent years, prediction models have been developed to study exposure levels and evaluate abatement solutions. Going one step further, auralization may provide an effective mean for evaluating perceptually the impact of railway noise on the soundscape near existing or future infrastructures. This paper extends railway noise emission models to propose an auralization approach based on physical parameters. As a first step, the approach focuses on rolling noise radiated by the track and wheels, which represents the main noise source over a wide range of speed. The excitation of the wheel/rail system by surface roughness is modeled in the time domain based on the system mobilities. Next, rail emission is modeled as a set of discrete coherent monopoles, while the wheel contribution uses resonant filters based on its structural response. Finally, the contribution of track sleepers is included following the standard TWINS model. Validations of the approach compare auralized pass-by levels with measured data. Preliminary results from listening tests evaluating the realism of auralized pass-by noise samples are also presented.

This paper presents a validation study of a recently developed auralization technique for non-sta... more This paper presents a validation study of a recently developed auralization technique for non-stationary traffic noise in urban areas. The approach implements a real time sample-based synthesis of engine and tire noise components allowing the restitution of moving vehicles with varying speed and engine regime. The acoustic propagation between sources and the listener location is modeled using standard engineering methods where the most important propagation paths are rendered individually. Results from an urban test site comparing recorded and auralized sequences of road traffic noise are discussed. The site features two types of road surfaces. Statistical pass-by analysis and binaural recordings were carried out for both road surface types. Auralized sequences using equivalent traffic flow conditions were then simulated. Different noise abatement approaches including low barriers and additional road surface types were also simulated. Pass-by sound pressure level indicators obtained...

2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2012

In order to synthesize the noise of internal combustion engines at arbitrary speed variations, an... more In order to synthesize the noise of internal combustion engines at arbitrary speed variations, an overlap-add-based method is proposed to be applied to sound samples extracted from a prerecorded engine noise at a continuously-varying speed. The objective of this new method is to minimize the phase discontinuities between a finite number of harmonics of the sample sounds likely to be concatenated. The harmonicity of the synthesized signal is then preserved which greatly enhances the acoustic quality of the restitution. Moreover, the synthesis stage is well suited for real time applications due to a low computational load compared to existing approaches. The proposed analysis-synthesis method can be applied to any harmonic sound whose spectral content depends solely on its fundamental frequency. By analogy to existing overlap-and-add methods, the method introduced here is referred to as Harmonic Synchronous Overlap and Add (HSOLA).

Journal of Sound and Vibration, 1999