Search results for "ACOUSTIC"

Characteristics of seasonal variations and noises of the daily double-difference and PPP solutions

2020

Abstract Long term GNSS observations provided by networks of the continuously operating reference stations (CORS) allow for determination of the global and local tectonic plate movements and seasonal variations. In recent years, PPP (Precise Point Positioning) technique has become increasingly popular and most likely in the future will replace relative positioning with CORS stations. In this paper, we discuss the difference of the velocity and seasonal component estimates of 25 Latvian CORS stations on the basis of daily PPP solutions from the Nevada Geodetic Laboratory and double-difference solutions from the Institute of Geodesy and Geoinformatics of the University of Latvia. Time series …

GUEST EDITORS' EDITORIAL: NOISE IN CONDENSED MATTER AND COMPLEX SYSTEMS

2005

Statistical analysis of noise levels in urban areas

1991

Abstract Environmental noise measurements have been carried out during recent years in different cities and locations of Spain. The noise levels have been continuously sampled over 24 h periods using a noise level analyzer. The data contained in this paper represent a total of 4200 measurement hours. All the information has been used to investigate the time patterns of the noise levels under a wide range of different conditions and to study the relationships between several noise descriptors in urban areas.

STATISTICAL ANALYSIS OF URBAN NOISE LEVELS

1990

Path Integral Methods for the Probabilistic Analysis of Nonlinear Systems Under a White-Noise Process

2020

Abstract In this paper, the widely known path integral method, derived from the application of the Chapman–Kolmogorov equation, is described in details and discussed with reference to the main results available in literature in several decades of contributions. The most simple application of the method is related to the solution of Fokker–Planck type equations. In this paper, the solution in the presence of normal, α-stable, and Poissonian white noises is first discussed. Then, application to barrier problems, such as first passage problems and vibroimpact problems is described. Further, the extension of the path integral method to problems involving multi-degrees-of-freedom systems is anal…

Constraints on neutrino masses from Planck and Galaxy clustering data

2013

We present here bounds on neutrino masses from the combination of recent Planck cosmic microwave background (CMB) measurements and galaxy clustering information from the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey-III. We use the full shape of either the photometric angular clustering (Data Release 8) or the 3D spectroscopic clustering (Data Release 9) power spectrum in different cosmological scenarios. In the Lambda CDM scenario, spectroscopic galaxy clustering measurements improve significantly the existing neutrino mass bounds from Planck data. We find Sigma m(v) < 0.39 eV at 95% confidence level for the combination of the 3D power spectrum with Planck C…

Plasma Effecton Pulse Parameters of Sound Wave

2019

This article presents the experimental results of the effect of gas discharge plasma on an acoustic wave. It is shown that after a certain intensity of the acoustic wave, the presence of plasma leads to a decrease in the Q -factor of the acoustic resonator, a shift in the acoustic resonance in the gas discharge tube at a lower frequency, and after switching off the acoustics, low-frequency gas oscillations with a frequency of 2 Hz are generated in the tube.

Optical frequency domain reflectometer distributed sensing using microstructured pure silica optical fibers under radiations

2016

International audience; We investigated the capability of micro-structured optical fibers to develop multi-functional, remotely-controlled, Optical Frequency Domain Reflectometry (OFDR) distributed fiber based sensors to monitor temperature in nuclear power plants or high energy physics facilities. As pure-silica-core fibers are amongst the most radiation resistant waveguides, we characterized the response of two fibers with the same microstructure, one possessing a core elaborated with F300 Heraeus rod representing the state-of-the art for such fiber technology and one innovative sample based on pure sol-gel silica. Our measurements reveal that the Xray radiations do not affect the capaci…

Probing interactions within the dark matter sector via extra radiation contributions

2013

The nature of dark matter is one of the most thrilling riddles for both cosmology and particle physics nowadays. While in the typical models the dark sector is composed only by weakly interacting massive particles, an arguably more natural scenario would include a whole set of gauge interactions which are invisible for the standard model but that are in contact with the dark matter. We present a method to constrain the number of massless gauge bosons and other relativistic particles that might be present in the dark sector using current and future cosmic microwave background data, and provide upper bounds on the size of the dark sector. We use the fact that the dark matter abundance depends…

Radiation Hardened Optical Frequency Domain Reflectometry Distributed Temperature Fiber-Based Sensors

2015

International audience; We study the performance of Optical Frequency Domain Reflectometry (OFDR) distributed temperature sensors using radiation resistant single-mode optical fibers. In situ experiments under 10 keV X-rays exposure up to 1 MGy( SiO 2 ) were carried out with an original setup that allows to investigate combined temperature and radiation effects on the sensors within a temperature range from 30 ° C to 250 ° C. Obtained results demonstrate that optical fiber sensors based on Rayleigh technique are almost unaffected by radiation up to the explored doses. We show that a pre-thermal treatment stabilize the sensor performance increasing the accuracy on temperature measurement fro…