Chevret P.,Institute National Of Recherche Et Of Securite
Journal of the Acoustical Society of America | Year: 2015
Sound prediction in open-plan offices is a real challenge for room acoustics models because of the large dimensions involved and because of the complexity of the interior layout. For these reasons, the geometrical theory, based on a high frequency hypothesis, is often cited as an advantageous solution. Two types of approaches are, in general, developed under this hypothesis: the phase-included approach and the energy-based or "incoherent" approach. In this paper, comparisons are presented between calculations performed using these two approaches and measurements conducted in the laboratory where workstations were separated by low dividers and placed under ceilings that were absorbent to various extents. Particular attention was paid to processing diffraction using the uniform theory of diffraction. Narrow-band comparisons between calculations and measurements show that the phase-included model is flawed at low frequencies whenever the characteristic dimensions of the elements of the room (desk, low divider, etc.) are of the same order of magnitude as the wavelength. Conversely, the incoherent formulation, which removes the part played by the interference, gives results at least as accurate, be it in octave band or overall. Boasting very short computation times, the incoherent approach opens up interesting prospects for acoustic predictions in large open-plan offices. © 2015 Acoustical Society of America.
Chevret P.,Institute National Of Recherche Et Of Securite
Applied Acoustics | Year: 2016
The sensitivity of intelligibility to ambient noise modulation is analyzed in this paper by means of two laboratory tests. The first one consists of measuring release from masking using acoustic samples composed of speech noise synthesized in the laboratory, but also real signals measured in two open plan offices. The Speech Reception Threshold values obtained from the experiment for the synthetic signals are compared with the literature. Those obtained for the real samples show significant differences as a function of the open-plane office. Secondly, a new indicator based on the calculation of the speech transmission index (IEC 60268-16, 2011) is proposed, by taking into account the modulation of the ambient noise in the 4 Hz octave band. Simultaneously, a second intelligibility experiment is performed, resulting in a very good correlation between the intelligibility scores and the new indicator. To complete the evaluation, the sound samples of the first test are reused to demonstrate that the indicator is a good descriptor of release from masking due to the modulation of ambient noise for the synthetic signals and that it is capable of classifying work spaces in terms of level of distraction. © 2015 Published by Elsevier Ltd.
Bonthoux F.,Institute National Of Recherche Et Of Securite
Annals of Occupational Hygiene | Year: 2016
Welding fumes are classified as Group 2B 'possibly carcinogenic' and this prompts to the implementation of local exhaust ventilation (LEV). The fume extraction torch with LEV integrated into the tool is the most attractive solution but its capture efficiency is often disappointing in practice. This study assesses the main parameters affecting fume capture efficiency namely the extraction flow rate, the positioning of the suction openings on the torch, the angle of inclination of the torch to the workpiece during welding, the metal transfer modes, and the welding deposition rate. The theoretical velocity induced by suction, estimated from the extraction flow rate and the position of the suction openings, is the main parameter affecting effectiveness of the device. This is the design parameter and its value should never be <0.25 m s-1. The angle of the torch relative to the workpiece also has a great deal of influence. To improve efficiency, work station layouts need to favour positions where the torch is held with angles closer to perpendicular (<15°). Welding with high deposition rates (>1.1g s-1) and spray transfer leads to low capture efficiency if induced velocities are <0.5 m s-1. The results of the study can be used in the design of integrated on-torch extraction systems and provide information for fixing system objectives. © 2016 The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.
Duquenne P.,Institute National Of Recherche Et Of Securite |
Marchand G.,Service Prevention des Risques Chimiques et Biologiques |
Duchaine C.,Laval University
Annals of Occupational Hygiene | Year: 2013
Endotoxins are lipopolysaccharides found in the outer membrane of most Gram-negative bacteria and cyanobacteria. Worker exposure to endotoxins has been shown in a number of work situations and is associated with both respiratory and systemic pathologies. The lack of an occupational exposure limit is mainly due to the absence of a standard protocol at the international level for sampling and analyzing airborne endotoxins. The bibliographic review in this article takes an exhaustive look at the current knowledge on measuring airborne endotoxins. It shows that, despite several reference documents at the international level, the methods used to measure endotoxin exposure differ considerably from one laboratory to another. Standardization is necessary to reduce interlaboratory variability and, ultimately, to improve the use of interstudy data. The bibliographic review presents the current status of standardization for airborne endotoxin measurement methods in the workplace and summarizes areas for further research. This article is both a reference document for all operators wishing to use such methods and a working document to build international consensus around the measurement of airborne endotoxins.
Agency: Cordis | Branch: H2020 | Program: RIA | Phase: NMP-29-2015 | Award Amount: 8.00M | Year: 2016
A definitive conclusion about the dangers associated with human or animal exposure to a particular nanomaterial can currently be made upon complex and costly procedures including complete NM characterisation with consequent careful and well-controlled in vivo experiments. A significant progress in the ability of the robust nanotoxicity prediction can be achieved using modern approaches based on one hand on systems biology, on another hand on statistical and other computational methods of analysis. In this project, using a comprehensive self-consistent study, which includes in-vivo, in-vitro and in-silico research, we address main respiratory toxicity pathways for representative set of nanomaterials, identify the mechanistic key events of the pathways, and relate them to interactions at bionano interface via careful post-uptake nanoparticle characterisation and molecular modelling. This approach will allow us to formulate novel set of toxicological mechanism-aware end-points that can be assessed in by means of economic and straightforward tests. Using the exhaustive list of end-points and pathways for the selected nanomaterials and exposure routs, we will enable clear discrimination between different pathways and relate the toxicity pathway to the properties of the material via intelligent QSARs. If successful, this approach will allow grouping of materials based on their ability to produce the pathway-relevant key events, identification of properties of concern for new materials, and will help to reduce the need for blanket toxicity testing and animal testing in the future.