Search results for "correlation [momentum]"
showing 9 items of 59 documents
The affine equivariant sign covariance matrix: asymptotic behavior and efficiencies
2003
We consider the affine equivariant sign covariance matrix (SCM) introduced by Visuri et al. (J. Statist. Plann. Inference 91 (2000) 557). The population SCM is shown to be proportional to the inverse of the regular covariance matrix. The eigenvectors and standardized eigenvalues of the covariance, matrix can thus be derived from the SCM. We also construct an estimate of the covariance and correlation matrix based on the SCM. The influence functions and limiting distributions of the SCM and its eigenvectors and eigenvalues are found. Limiting efficiencies are given in multivariate normal and t-distribution cases. The estimates are highly efficient in the multivariate normal case and perform …
Taxonomy of correlations of wind velocity;an application to the Sicilian area.
2008
Abstract We present an algorithm that allows us to analyze the cross-correlation of wind velocity measured in different locations; this algorithm is applied to 29 recording stations in Sicily. The results show that such correlations present a significant and persistent ultrametric structure that is influenced by the geographical neighborhood as well as by the presence of mountain and the sea. The algorithm presented, that is also able to reveal weak correlations, can be used as a starting point for the development of multivariate models of wind.
Anomalous diffusion and nonlinear relaxation phenomena in stochastic models of interdisciplinary physics
2020
The study of nonlinear dynamical systems in the presence of both Gaussian and non-Gaussian noise sources is the topic of this research work. In particular, after shortly present new theoretical results for statistical characteristics in the framework of Markovian theory, we analyse four different physical systems in the presence of Levy noise source. (a) The residence time problem of a particle subject to a non-Gaussian noise source in arbitrary potential profile was analyzed and the exact analytical results for the statistical characteristics of the residence time for anomalous diffusion in the form of Levy flights in fully unstable potential profile was obtained. Noise enhanced stability …
Robustness of texture parameters for color texture analysis
2006
This article proposes to deal with noisy and variable size color textures. It also proposes to deal with quantization methods and to see how such methods change final results. The method we use to analyze the robustness of the textures consists of an auto-classification of modified textures. Texture parameters are computed for a set of original texture samples and stored into a database. Such a database is created for each quantization method. Textures from the set of original samples are then modified, eventually quantized and classified according to classes determined from a precomputed database. A classification is considered incorrect if the original texture is not retrieved. This metho…
Modeling long-range memory with stationary Markovian processes
2009
In this paper we give explicit examples of power-law correlated stationary Markovian processes y(t) where the stationary pdf shows tails which are gaussian or exponential. These processes are obtained by simply performing a coordinate transformation of a specific power-law correlated additive process x(t), already known in the literature, whose pdf shows power-law tails 1/x^a. We give analytical and numerical evidence that although the new processes (i) are Markovian and (ii) have gaussian or exponential tails their autocorrelation function still shows a power-law decay =1/T^b where b grows with a with a law which is compatible with b=a/2-c, where c is a numerical constant. When a<2(1+c) th…
Calculating the implied correlation matrix for a Path Analysis model
2014
To overcome the limitations of two existing methods for calculating a Path Analysis implied correlation matrix, this paper presents an alternative method for calculating this matrix. This new method is based on a recurrence principle which is easy and quick to implement. This method is also operational regardless of the number of variables. The consequences of this result with the estimation or testing stages will be illustrated on the basis of examples.
Vocal Tract Discomfort Scale (VTDS) and Voice Symptom Scale (VoiSS) in the early identification of Italian teachers with voice disorders
2019
Abstract Introduction The current Italian law does not include any guidance regarding voice education, prevention of voice disorders and screening in subjects with high vocal loading such as teachers. Objectives We aimed to check the correlation between the Vocal Tract Discomfort Scale (VTDS) with the Voice Symptom Scale (VoiSS) for the evaluation of Italian teachers. In addition, we aimed to investigate whether there are differences in the frequency and intensity of discomfort symptoms in teachers with disabilities comparing vocal tract discomfort symptoms in teachers with high risk (HRVD) and low risk (LRVD) of vocal disorders according to the VoiSS cutoff (> 15.5). Methods We analyzed…
Alignments of Time Intensity curves in sensory analysis
2006
International audience
Mathematics Competence Level: The Contribution of Non-symbolic and Spatial Magnitude Comparison Skills.
2019
Magnitude comparison skills have been related to mathematics competence, although results in this area vary. The current study aimed to describe the performance of 75 children (aged 4-5 years) in two comparison tasks; and examine the strength of the relationship between each of the two tasks and mathematics competence level (MCL). Participants were assessed with the Early Numeracy Test which provides a global MCL score. Magnitude comparison skills were assessed with two tasks: a non-symbolic number comparison task and a spatial comparison task. Results of the Pearson correlation analysis showed a relationship between the two tasks with better performance in the spatial comparison task. Regr…