Search results for "NOISE"
showing 10 items of 1375 documents
Vulnerability during pregnancy in an urban environment : do environmental and individual risk factors cumulate?
2018
International audience; Apart from demographic, socio-economic, behavioral, nutritional and medico-obstetrical factors, environmental factors have been suggested to be associated with adverse pregnancy outcomes, such as preterm birth, low birth weight or hypertensive disorders. According to a recent review of the literature, there is some suggestive evidence of adverse associations with environmental noise especially for low birth weight. However, the way these individual and environmental vulnerabilities combine has been scarcely studied. The objective of this study was to describe the accumulation of individual, socio-economics, medical and environmental vulnerability markers and to asses…
Production of 6-pentyl-alpha-pyrone by Trichoderma sp. from vegetable oils
1997
International audience
Numerical vibroacoustic analysis of plates with constrained-layer damping patches
2011
International audience; A numerical vibroacoustic model that can manage multilayered plates locally covered with damping patches is presented. All the layers can have an on-axis orthotropic viscoelastic behavior. Continuity of displacements and transverse shear stresses at each interface is enforced, which permits to write the entire displacement field in function of the displacements of the-common-first layer, leading to a two-dimensional plate model. The problem is then discretized by Rayleigh-Ritz's method using a trigonometric basis that includes both sine and cosine functions in order to treat various boundary conditions. The excitation can be of mechanical kind (concentrated or distri…
Numerical Optimization of Liner Impedance in Acoustic Duct
2020
Abstract The SALUTE project aims at evaluating performance of metacomposites for acoustic smart lining in grazing turbulent flow. Theoretical and numerical investigations are carried out for designing innovative specimen. A specific focus is placed in the realization of prototypes for evaluating the metacomposite liner performances in 2D and 3D liners, its process complexity and robustness. The insight gain in this project is new tools for obtaining innovative samples; the acoustical experimental tests demonstrate efficiency and robustness of such technology for controlling UHBR noise emission. This paper is focused on parametric study based on the maximization of the absorption coefficient…
Acoustic properties of plates with unevenly distributed macro perforations backed by woven meshes
2012
A hybrid model describing the acoustic properties of plates with macro-perforations that can be unevenly distributed on the plate surface and backed by woven or precision woven meshes with microscopic perforations is proposed. The plate perforations may be of circular or rectangular shapes. Since the perforated plate may not necessarily be considered as an equivalent fluid, its surface impedance is calculated by the Maa model [Noise Control Eng. J. 29, 77-84 (1987)], whereas the Johnson-Champoux-Allard model [J. Appl. Phys. 70, 1975-1979 (1991)] is used for the mesh. It is observed that the absorption of the carrying plate seems to depend on the hydraulic diameter of the perforations and no…
Indoor noise exposure assessment of primary school children living in a french urban area
2012
International audience; The recent development of powerful noise mapping softwares allows to assess the exposure to environmental noise at the scale of an agglomeration. However noise levels inside dwellings are still unknown at such scales. To evaluate indoor noise levels and to investigate the factors which determine them, an eight-day noise measurement campaign was carried out in 50 childrens home. These children were randomly chosen among 8 or 9-year-old pupils attending the public primary schools of Besançon (France). Microphones were placed in the childs bedroom, outdoor in front of the bedrooms facade, and in the main room. Equivalent sound pressure levels (LAeq) were calculated d…
Gas sensors arrays (electronic noses) : a study about the speed/accuracy ratio
2000
Abstract New Fingerprint Mass Spectra (FMS) systems claim for a higher precision, a reduced analysis time, and a lower drift, compared with Gas Sensors Arrays ‘Electronic Noses’. We demonstrated in this study that metal oxide gas sensors may have highly improved performances for both accuracy and run time, when used in optimum conditions. The different noise components were quantified referring to popular words (equivalent of ethanol concentration) using the transfer function of the sensor. It was pointed out that sample surrounding greatly affects the noise level, and that the signal-to-noise ratio may be dramatically increased, reducing the distortion generally assessed between sensor and…
Noise Analysis and Comparison of Phase-and Frequency-Detecting Readout Systems: Application to SAW Delay Line Magnetic Field Sensor
2019
International audience; Transmission surface acoustic wave (SAW) sensors are widely used in various fields of application. In order to improve the limit of detection (LOD) of such sensor systems, it is essential to understand and quantify the relevant noise sources. Only then, strategies for noise reduction can be developed. In this paper, low noise readout systems for the application with SAW sensors in an open-loop and a closed-loop configuration are presented and experimentally investigated with regard to their phase noise on the example of a SAW delay line magnetic field sensor. Besides a comprehensive analysis of the phaseand frequency modulated signals, respectively, previously derive…
Noise characterization of analog to digital converters for amplitude and phase noise measurements
2017
International audience; Improvements on electronic technology in recent years have allowed the application of digital techniques in phase noise metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use. In most digital schemes the Analog to Digital Converters (ADCs) set the ultimate performance of the system, therefore the proper selection of this component is a critical issue. Currently, the information available in literature describes in depth the ADC features only at frequency offsets far from the carrier. However, the perfo…
Equivalence of Open-Loop and Closed-Loop Operation of SAW Resonators and Delay Lines
2019
International audience; Surface acoustic wave (SAW) sensors in the form of two-port resonators or delay lines are widely used in various fields of application. The readout of such sensors is achieved by electronic systems operating either in an open-loop or in a closed-loop configuration. The mode of operation of the sensor system is usually chosen based on requirements like, e.g., bandwidth, dynamic range, linearity, costs, and immunity against environmental influences. Because the limit of detection (LOD) at the output of a sensor system is often one of the most important figures of merit, both readout structures, i.e., open-loop and closed-loop systems, are analyzed in terms of the minim…