Search results for " acoustic"
showing 10 items of 344 documents
Materials Communicating with the BIM: Aims and First Results of the McBIM Project
2019
This paper introduces McBIM, a French national research project working on on-line monitoring on concrete structure. This project gathers 3 french laboratories (the CRAN, LAAS and LIB) associated with one company (360SmartConnect/FINAO SAS) that are working together from 2018 to 2021. It proposes 1) to design a “communicating concrete”, made of concrete equipped with embedded low-energy wireless microsensor network, able to manage and exchange data using BIM standards, and 2) to demonstrate the usefulness of this approach across several building lifecycle phases, namely the manufacturing, construction and exploitation phases for structural health monitoring. The paper will first start by in…
Dynamic carrier distribution in quantum wells modulated by surface acoustic waves
2001
We have investigated the dynamics of photogenerated carriers under surface acoustic wave (SAW) fields in GaAs quantum wells using spatially and time-resolved photoluminescence (PL). The frequency and phase of the PL oscillations under a SAW yield information about the carrier distribution and the band-gap modulation induced by the SAW. We directly prove that the transport properties of the carriers ultimately control their distribution, storage and, subsequent recombination in the modulated potential.
Integrated photonic routers driven by surface acoustic waves
2016
Durante la segunda mitad del siglo XX se produjo un desarrollo excepcional de la capacidad de transmitir y procesar información electrónicamente. Esto fue debido en parte a la capacidad de integrar en un único substrato una gran cantidad de transistores, que son las unidades fundamentales de procesamiento de datos. Este comportamiento quedó resumido en la ley de Moore, que predecía que el número de transistores integrados se duplicaría cada 24 meses. Esta tendencia, que se ha mantenido hasta la actualidad con transistores de tamaño nanométrico, no puede continuar indefinidamente. Uno de los problemas fundamentales reside en la capacidad limitada para disipar el calor que generan los disposi…
Acoustic methods for measuring the porosities of porous materials incorporating dead-end pores
2013
International audience; The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont et al. [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high …
High performance algorithms based on a new wawelet expansion for time dependent acoustics obstale scattering
2007
This paper presents a highly parallelizable numerical method to solve time dependent acoustic obstacle scattering problems. The method proposed is a generalization of the ``operator expansion method" developed by Recchioni and Zirilli [SIAM J.~Sci.~Comput., 25 (2003), 1158-1186]. The numerical method proposed reduces, via a perturbative approach, the solution of the scattering problem to the solution of a sequence of systems of first kind integral equations. The numerical solution of these systems of integral equations is challenging when scattering problems involving realistic obstacles and small wavelengths are solved. A computational method has been developed to solve these challenging p…
Analysing longitudinal turbulence intensity in vegetated channels
2007
Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. In this paper the turbulence structure of open-channel flow over a flexible grass vegetation is investigated. Velocity measurements were carried out, in a rectangular flume, using a 2D-ADV (Acoustic Doppler Velocimeter) for different values of stem concentration, water discharge, and bed slope. The experimental results showed that: 1) the maximum value of the longitudinal turbulence intensity occurs at a water depth close to the bent vegetation height; 2) the turbulence intensity damps for increasing values of the stem concentration; 3) above the vegetation hei…
Diagnosis and therapy of vestibular schwannoma.
2009
MRI studies are of paramount importance for diagnosis and follow-up measurements during conservative and postinterventional management of vestibular schwannomas (VS). MRI findings that convey important information for hearing-preservation VS surgery are: length of tumor-cochlear nerve contact, involvement of the internal auditory canal, incomplete filling of internal auditory canal, tumor size less than 15 mm and the intralabyrinthine signal intensity on 3DFT-CISS gradient-echo images. Functional neuro-otologic studies of facial nerve function, hearing and vestibular/balance function provide a valuable means of assessment of the actual impairment of the functional status of the VS patient. …
Influence of nerve of origin and tumor size of vestibular schwannoma on dynamic posturography findings.
2006
Condition 5-score (C5S) and vestibular ratio (VER) correlate, but condition-6-score (C6S) and mean overall balance score (MOBS) do not, with the size of an inferior vestibular nerve (IVN) vestibular schwannoma (VS). In IVN VS patients the visual system plays a major role in the maintenance of postural stability.To test whether the size of a superior vestibular nerve (SVN) or IVN VS, as measured on MRI scans, correlates with computerized dynamic platform posturography (CDPP) findings and whether CDPP findings could preoperatively predict the nerve of origin of the VS.This was a retrospective study. Seventy-five consecutive VS patients were evaluated. C5S, C6S, VER, and MOBS were evaluated. S…
Imaging of Vestibular Schwannoma With Prevalent Cystic Component
2009
Not available
Subjective Assessment of Concert Halls: a Common Vocabulary for Music Lovers and Acousticians
2012
In recent years we have interviewed members of the audience after musical performances and asked them to evaluate the acoustics of the concert halls. A group of music lovers (with a high level of musical training and experience) and acousticians (with a wide knowledge of the physical characteristics of sound transmission) also attended each performance and answered the same questions as the general public. This group thereby served as a control group when evaluating surveys of the general public. In this paper, the results obtained when analyzing these control group surveys are presented. This analysis shows that a common vocabulary exists between music lovers and acousticians when rating a…