Search results for "NOISE"
showing 10 items of 1375 documents
Role of the colored noise in a FitzHugh-Nagumo system driven by a periodic signal
2007
During these last years the interest in neuronal dynamics increased. The study of this kind of system has been carried out by using the FitzHugh-Nagumo (FHN) model that is a simplified modification of the Hodgkin-Huxley model. Many interesting phenomena can be observed in the presence of fluctuations: modification of detection threshold by manipulation of noisy parameters (FHN model), noise-induced activation and coeherence resonance for suitable noise amplitude (absence of periodic signal), resonant activation for high periodic signals and noise reduction, intrinsic stochastic resonance (ISR) in Hodgkin-Huxley neuron and the enhancement of a weak signal by tuning the subthreshold intrinsic…
Indagine sperimentale sui segnali sonori all’interno dei rotabili per la diagnosi dello stato dell’armamento ferroviario
2003
The maintenance of track provides an relatively frequent operations. A good maintenance-planning allows to reduce the interference between rail traffic and maintenance operations. It is necessary so to use a monitoring system of track conditions. In this paper is showed an indirect monitoring system that correlates track conditions and typical spectrum of in-cab noise. The first results of experimental survey are reported.
Helicopter operations: the environmental impact and ground facilities. Procedures and operational standards for the system’s acceptance.
2012
The link between the heliports, environmental quality and safety is an important challenge in the field of helicopter transport. This challenge is especially crucial when the helicopter operations are carried out on densely urbanized areas. Often these areas have significant constraints and obstacles, particularly in terms of noise pollution. These constraints make the approach/takeoff maneuvers very complicated. The theme of the environmental sustainability of the rotorcraft is strongly felt in many countries. The production of noise is subjected to numerous rules and procedures, which tend to improve the acceptability of the helicopter by residents in neighboring areas to verti/heliports.…
A strategy for the identification of building structures under base excitations
2008
In this paper the evolution of a time domain dynamic identification technique based on a statistical moment approach is presented. This technique is usable in the case of structures under base random excitations in the linear state and in the non linear one. By applying Itoˆ stochastic calculus special algebraic equations can be obtained depending on the statistical moments of the response of the system to be identified. Such equations can be used for the dynamic identification of the mechanical parameters and of the input. The above equations, differently from many techniques in the literature, show the possibility to obtain the identification of the dissipation characteristics independent…
Dynamical identification of building structures: new strategies
2010
In this paper the evolution of a time domain dynamic identification technique based on a statistical moment approach is presented. This technique can be used in the case of structures under base random excitations in the linear state and in the non linear one. By applying stochastic calculus, special algebraic equations can be obtained depending on the statistical moments of the response of the system to be identified. Such equations can be used for the dynamic identification of the mechanical parameters and of the input. The above equations, differently from many techniques in the literature, show the possibility of obtaining the identification of the dissipation characteristics independen…
Restoration of Vertical Line Scratches with a Distributed Genetic Algorithm
2006
This contribution approaches the problem of scratch restoration in old movies as a optimisation's problem. The functional based on the statistical properties of the image around the scratch is optimised using an ad-hoc genetic algorithm. Given the large amount of the computational time needed by genetic algorithms, a network of standard workstations with heterogeneous operating systems has been used. Each workstation in the network works on each scratch to perform the restoration, and a specific machine works as root node with the task of distributing jobs on the network and adding the outputted restored scratches back into the image.
Forecasting noise levels by means of neural networks for assessing urban traffic policies
2005
Within the assessment of the sustainability of plans and actions concerning the built environment, the transportation sector plays an increasing role, due to its importance in the economic and social life of countries. As that, the analysis of the sustainability concerning the transportation sector is now often embodied into the so called Strategic Environmental Analyses (SEA), that should provide local administrators with easy criteria for ranking the environmental suitability of designing policies, and that would seem to encounter the needed features for a correct evaluation of the urban masterplan. The urban noise forecast is very useful for local administrations, which have presently to…
First proposal of a methodology for a preventive assessment of the acoustic impact of advanced landfills
2005
In this paper, the results of a preliminary study on the environmental noise pollution of a technologically advanced landfill to be realized in Sicily (Italy) are presented. The investigation has been carried out analysing, at the beginning, a simulating model suggested by the European Community. The method makes reference to the ISO 9613-2:1996 standard, which suggests a general method of calculation to assess the attenuation of sound during propagation outdoors. The simulation has pointed out the troubles in carrying out the noise pollution assessment of an advanced landfill, where several and different kinds of sound sources are present at the same time; it isn’t always possible, for exa…
A combined CWT-DWT method using model-based design simulator for partial discharges online detection
2009
The suppression of noises is fundamental in onsite Partial Discharge (PD) measurements. For this purpose, the wavelet transform analysis method has been developed and it is a powerful tool for processing the transient and suddenly changing signals. As the wavelet transform possesses the properties of multi-scale analysis and time-frequency domain localization, it is also particularly suitable to process the suddenly changing signals of the partial discharge pulse (PD). In this paper, an improved Wavelet denoising method developed by a model-based design software is presented. Simulations are provided as well as some results obtained during laboratory experiment and on-line PD measurements. …
Signal to Noise Ratio of Silicon Photomultipliers: a study in the Continuous Wave Regime
2014
We report on Signal to Noise Ratio measurements carried out, in the continuous wave regime, at different bias voltages, frequencies and temperatures, on a novel class of silicon photomultipliers fabricated in planar technology on silicon p-type substrate. Signal to Noise Ratio has been measured as the ratio of the photogenerated current, filtered and averaged by a lock-in amplifier, and the Root Mean Square deviation of the same current. The measured noise takes into account the shot noise, resulting from the photocurrent and the dark current. We have also performed a comparison between our SiPMs and a photomultiplier tube in terms of Signal to Noise Ratio, as a function of the temperature …