Search results for " statistics"

Effect of parametric variation of center frequency and bandwidth of morlet wavelet transform on time-frequency analysis of event-related potentials

2017

Time-frequency (TF) analysis of event-related potentials (ERPs) using Complex Morlet Wavelet Transform has been widely applied in cognitive neuroscience research. It has been widely suggested that the center frequency (fc) and bandwidth (σ) should be considered in defining the mother wavelet. However, the issue how parametric variation of fc and σ of Morlet wavelet transform exerts influence on ERPs time-frequency results has not been extensively discussed in previous research. The current study, through adopting the method of Complex Morlet Continuous Wavelet Transform (CMCWT), aims to investigate whether time-frequency results vary with different parametric settings of fc and σ. Besides, …

Periodic and quasi-periodic orbits of the dissipative standard map

2011

We present analytical and numerical investigations of the dynamics of the dissipative standard map. We first study the existence of periodic orbits by using a constructive version of the implicit function theorem; then, we introduce a parametric representation, which provides the interval of the drift parameter ensuring the existence of a periodic orbit with a given period. The determination of quasi--periodic attractors is efficiently obtained using the parametric representation combined with a Newton's procedure, aimed to reduce the error of the approximate solution provided by the parametric representation. These methods allow us to relate the drift parameter of the periodic orbits to th…

Air conditioning and heat-related mortality: a multi-country longitudinal study

2020

Background: Air conditioning has been proposed as one of the key factors explaining reductions of heat-related mortality risks observed in the last decades. However, direct evidence is still limited. Methods: We used a multi-country, multi-city, longitudinal design to quantify the independent role of air conditioning in reported attenuation in risk. We collected daily time series of mortality, mean temperature, and yearly air conditioning prevalence for 311 locations in Canada, Japan, Spain, and the USA between 1972 and 2009. For each city and sub-period, we fitted a quasi-Poisson regression combined with distributed lag non-linear models to estimate summer-only temperature–mortality associ…

Influence of the quadratic term in the alongwind stochastic response of SDOF structures

1996

A parametric study, regarding the influence of the quadratic pressure term, which is often neglected in the literature, on the stochastic alongwind response of a single-degree-of-freedom (SDOF) structure subjected to wind action, is presented. The results are reported in terms of percentages of difference in the evaluation of the response, by considering and neglecting the quadratic pressure term. The changing parameters considered are: the terrain drag coefficient, the structure height, the structure natural radian frequency, the structure damping coefficient and the wind reference mean velocity. The response stochastic analysis has been carried out in the time domain, by means of the mome…

Ductility of Reinforced Concrete Members Externally Wrapped with Fiber-Reinforced Polymer Sheets

2007

The effectiveness of external wrapping with fiber-reinforced polymer for enhancing the curvature ductility of lightly reinforced concrete members is investigated. Referring to members with circular transverse cross sections, the performances in terms of both strength and ductility capacities are analyzed, and the predictive reliability of two different recent constitutive models, available in the literature and able to take into account the softening behavior of confined concrete, is checked. A parameter characterizing the effectiveness of the confining wrapping is proposed, and characteristic values are suggested. Moreover, referring to ductility increases due to confinement effects, a com…

Nonlinear System Response for Impulsive Parametric Input

1997

In engineering applications when the intensity of external forces depends on the response of the system, the input is called parametric. In this paper dynamical systems subjected to a parametric deterministic impulse are dealt with. Particular attention has been devoted to the evaluation of the discontinuity of the response when the parametric impulse occurs. The usual forward difference and trapezoidal integration schemes have been shown to provide only approximated solutions of the jump of the response; hence, the exact solution has been pursued and presented under the form of a numerical series. The impulse is represented throughout the paper by means of a classical Dirac’s delta functio…

Analytical properties of horizontal visibility graphs in the Feigenbaum scenario

2012

Time series are proficiently converted into graphs via the horizontal visibility (HV) algorithm, which prompts interest in its capability for capturing the nature of different classes of series in a network context. We have recently shown [1] that dynamical systems can be studied from a novel perspective via the use of this method. Specifically, the period-doubling and band-splitting attractor cascades that characterize unimodal maps transform into families of graphs that turn out to be independent of map nonlinearity or other particulars. Here we provide an in depth description of the HV treatment of the Feigenbaum scenario, together with analytical derivations that relate to the degree di…

Lidar : traitement avancé des données et interprétation archéologique - cours 2016

2016

A multicriteria extension of the efficient market hypothesis

2021

Challenging the Efficient Market Hypothesis (EMH) has been a recurrent topic for researchers and practitioners since its formulation. Hundreds of empirical studies claim to either prove or disprove the EMH by means of a number of heterogeneous methods. Even though the EMH is usually adjusted to a measure of risk, there is a lack of a formal analysis within a multiple-criteria context. In this paper, we propose a extension of the EMH that accommodates the foundations of multiple-criteria decision analysis. To this end, we rely on a family of parametric signed dissimilarity measures to assess multidimensional performance differences. Since normalization is a critical step in our approach to a…

Statistical biophysical parameter retrieval and emulation with Gaussian processes

2019

Abstract Earth observation from satellites poses challenging problems where machine learning is being widely adopted as a key player. Perhaps the most challenging scenario that we are facing nowadays is to provide accurate estimates of particular variables of interest characterizing the Earth's surface. This chapter introduces some recent advances in statistical bio-geophysical parameter retrieval from satellite data. In particular, we will focus on Gaussian process regression (GPR) that has excelled in parameter estimation as well as in modeling complex radiative transfer processes. GPR is based on solid Bayesian statistics and generally yields efficient and accurate parameter estimates, a…