Search results for "Power spectral density"

showing 5 items of 15 documents

Stochastic Response Of Fractionally Damped Beams

2014

Abstract This paper aims at introducing the governing equation of motion of a continuous fractionally damped system under generic input loads, no matter the order of the fractional derivative. Moreover, particularizing the excitation as a random noise, the evaluation of the power spectral density performed in frequency domain highlights relevant features of such a system. Numerical results have been carried out considering a cantilever beam under stochastic loads. The influence of the fractional derivative order on the power spectral density response has been investigated, underscoring the damping effect in reducing the power spectral density amplitude for higher values of the fractional de…

PhysicsCantileverEuler-Bernoulli beam Fractional constitutive law Power spectral densityMechanical EngineeringMathematical analysisAerospace EngineeringSpectral densityOcean EngineeringStatistical and Nonlinear PhysicsCondensed Matter PhysicsEuler–Bernoulli beam fractional constitutive law power spectral densityFractional calculusSystem dynamicsTerm (time)AmplitudeNuclear Energy and EngineeringControl theoryFrequency domainSettore ICAR/08 - Scienza Delle CostruzioniExcitationCivil and Structural Engineering
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A representation of wind velocity by means of fractional spectral moments

2009

This paper deals with the definition of a new function that is a link between Power Spectral Density (PSD) and correlation function, called the Fractional Spectral Moments function. This is defined as the moment of complex order g of the one-sided PSD. It is shown that by means of this complex function both the correlation function and PSD can be represented with great accuracy.

Power Spectral DensityFractional CalculuWind Speed VelocityCorrelation FunctionFractional Spectral MomentSettore ICAR/08 - Scienza Delle CostruzioniSpectral MomentGeneralized Taylor Serie
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A new representation of power spectral density and correlation function by means of fractional spectral moments

2009

In this paper, a new perspective for the representation of both the power spectral density and the correlation function by a unique class of function is introduced. We define the moments of order gamma (gamma being a complex number) of the one sided power spectral density and we call them Fractional Spectral Moments (FSM). These complex quantities remain finite also in the case in which the ordinary spectral moments diverge, and are able to represent the whole Power Spectral Density and the corresponding correlation function.

Power spectral density; Correlation function; Spectral moments; Fractional spectral moments; Generalized Taylor series; Fractional calculusMechanical EngineeringMathematical analysisPerspective (graphical)Stochastic ProcesseAerospace EngineeringSpectral densityOcean EngineeringStatistical and Nonlinear PhysicsMaximum entropy spectral estimationFunction (mathematics)Wind engineeringCondensed Matter PhysicsSpectral MomentFractional calculusCorrelation function (statistical mechanics)IngenieurwissenschaftenNuclear Energy and EngineeringEarthquake engineeringOrder (group theory)ddc:620Representation (mathematics)Settore ICAR/08 - Scienza Delle CostruzioniCivil and Structural EngineeringMathematics
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Time-Frequency Characteristics of In-Home Radio Channels Influenced by Activities of the Home Occupant

2019

While aging is a serious global concern, in-home healthcare monitoring solutions are limited to context-aware systems and wearable sensors, which may easily be forgotten or ignored for privacy and comfort reasons. An emerging non-wearable fall detection approach is based on processing radio waves reflected off the body, who has no active interaction with the system. This paper reports on an indoor radio channel measurement campaign at 5.9 GHz, which has been conducted to study the impact of fall incidents and some daily life activities on the temporal and spectral properties of the indoor channel under both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions. The time-frequ…

device-free fall detectionComputer scienceReal-time computingWearable computerVDP::Information and communication science: 42002 engineering and technologylcsh:Chemical technology01 natural sciencesBiochemistryArticleAnalytical ChemistryDoppler power spectral density0202 electrical engineering electronic engineering information engineeringlcsh:TP1-1185Electrical and Electronic EngineeringInstrumentationnon-stationary radio channels010401 analytical chemistry020206 networking & telecommunicationsAtomic and Molecular Physics and Optics0104 chemical sciencesTime–frequency analysisspectrogram analysisVDP::Informasjons- og kommunikasjonsvitenskap: 420Radio waveCommunication channelambient-assisted livingSensors (Basel, Switzerland)
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Passive Control of Linear Structures Equipped with non-Linear Viscous Dampers and Amplification Mechanism

2008

Fluid damper devices in civil structures such as buildings or bridges are commonly used as energy absorbers for seismic protection. The problem in the response analysis of structures with filled dampers mainly consists in the fact that, due to the strongly nonlinear behavior of such equipments, the response spectrum technique fails. Moreover, in order to enhance the damping effect various toggle brace configurations have been recently proposed. In this paper by using the concept of power spectral density function compatible with the elastic response spectrum and the stochastic linearization technique, the equivalent damping ratio is obtained. It is shown that once the system is linearized r…

viscous dampers nonlinearity seismic protection toggle brace power spectral density stochastic analysisSettore ICAR/08 - Scienza Delle Costruzioni
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