Search results for " NOISE"

Temporal difference method for processing dynamic speckle patterns

2010

A temporal difference method for processing dynamic speckle images is proposed. In the method two speckle images of an object, separated by a time interval, are subtracted one from the other to detect whether the speckle structure has changed or not. The rationale of the method is discussed. A variant of the method that allows measuring the area of an activity zone surrounded by a static region is tested in digital simulations. As a demonstrative experiment, that variant is employed to characterize the drying of a damp patch in filter paper.

Attractors of stochastic lattice dynamical systems with a multiplicative noise and non-Lipschitz nonlinearities

2012

AbstractIn this paper we study the asymptotic behavior of solutions of a first-order stochastic lattice dynamical system with a multiplicative noise.We do not assume any Lipschitz condition on the nonlinear term, just a continuity assumption together with growth and dissipative conditions, so that uniqueness of the Cauchy problem fails to be true.Using the theory of multi-valued random dynamical systems we prove the existence of a random compact global attractor.

SCELTA E APPLICAZIONE DI NUOVI STANDARD DI MANOVRA NELLE FASI DI DECOLLO ED ATTERRAGGIO DELL’ELICOTTERO - MODELLO E SPERIMENTAZIONE -

Una zona o un ambiente ha tipicamente un livello sonoro che lo caratterizza e ci si aspetta che le variazioni di quell’ambiente in equilibrio dovute ad un evento acustico insolito alterino le sensazioni delle persone in quel contesto. Non ci si può riferire al buon senso per valutare se disturbiamo o danneggiamo il prossimo, è necessario individuare le fonti di rumore e valutare l’impatto ambientale tramite indagini di tipo qualitativo e fasi sperimentali di misura. Lo studio condotto ha correlato il dato qualitativo a quello quantitativo sia in ambito predittivo che tramite rilievi sul campo. Gli scopi e gli obiettivi sono incentrati a: ricercare una simulazione coerente di propagazione de…

No linealidad y asimetría en el proceso generador del Índice Ibex35

2013

This paper analyzes the behavior of Ibex35 from January 1999 to December 2001, in order to check if it follows a different process from random walk so its return is not a white noise and it can be predictable, against the efficient market hypothesis. For that, a nonlinear generating process of return will be considered and a STAR-APARCH model will be specified. This model allows a nonlinear behavior in the conditional mean and in the conditional variance. The empirical results show that the Ibex35 follows a nonlinear and asymmetric process, both in the conditional mean as in the conditional variance, so the weak-version of efficient market hypothesis is rejected. El trabajo analiza el compo…

Measurement of ultra-low heating rates of a single antiproton in a cryogenic Penning trap

2019

Physical review letters 122(4), 043201 (2019). doi:10.1103/PhysRevLett.122.043201

Alteraciones del sueño producidas por el ruido ambiental*

1989

ResumenEste articulo presenta los resultados de una encuesta realizada con el objetivo de valorar distintos aspectos relacionados con el ruido ambiental y sus efectos sobre determinadas comunidades urbanas. Un total de 263 residentes en 5 emplazamientos diferentes de la ciudad de Valencia fueron entrevistados. En estos 5 emplazamientos se realizaron de manera independiente una serie de medidas de los niveles de ruido durante las 24 horas del dia y en distintos días de la semana.:El 400%0 de los encuestados manifestó tener alguna dificultad para dormirse y el 59% de ellos lo atribuyó al ruido causado por el tráfico. Asimismo, un 49% de los encuestados declaró despertarse durante la noche (el…

The Community Response to Aircraft Noise Around Six Spanish Airports

1993

Abstract The community response to aircraft noise has been studied through a social survey. A total of 1800 persons living in the vicinity of six major Spanish airports have been interviewed at their homes concerning the environmental quality of the area, dissatisfaction with road traffic noise and aircraft noise, activities interfered with by noise, most disturbing aircraft types, and subjective evaluation of airport impact. All the responses obtained in this survey have been compared with aircraft noise levels corresponding to the residence locations of the people interviewed (values of NEF levels were calculated with the INM model). The results obtained in this work allow one to evaluate…

A study of noise transmission through cylindrical shell using modal truncation approach

2011

International audience; The study of the vibroacoustic behaviour of cylindrical structure like aircraft fuselage requires the establishment of very large models, and the numerical results which can be obtained are often difficult to interpret. On the other hand, the study of simple structures such as cylindrical shells is useful to validate the criteria and tools that can be used to simplify the models of complex structures. The presented study concerns the sound transmission through a cylindrical shell coupled to a cavity and subjected to an incident acoustic wave. Noise reduction is obtained and validated by a numerical method which uses structural and acoustical modes. A criterion for se…

Viscoelastic bearings with fractional constitutive law for fractional tuned mass dampers

2015

Abstract The paper aims at studying the effects of the inherent fractional constitutive law of viscoelastic bearings used as devices for tuned mass dampers. First, the proper constitutive law of the viscoelastic supports is determined by the local constitutive law. Then, the characteristic force–displacement relationship at the top of the bearing is found. Taking advantage of the whole bearing constitutive laws, the tuning of the mass damper is proposed by defining the damped fractional frequency, which is analogous to the classical damped frequency. The effectiveness of the optimal tuning procedure is validated by a numerical application on a system subjected to a Gaussian white noise.

Characterization of electromagnetic noise suppression sheet for aerospace applications

2016

Electromagnetic noise suppression sheets based on absorber materials can be an interesting solution to reduce or suppress noise emissions at a high-frequency region that may cause complex EMI problems. These materials usually are characterized by their permeability but their performance also depend on other factors such as dimension, geometry, thickness or noise source kind. Three experimental methods are proposed in order to characterize absorber sheets in different kind of applications taking into account the last factors. These setups make it possible to test several samples with different characteristics and to analyse the absorption capacity in applications with transmission line probl…