Search results for "Serie"
showing 10 items of 1270 documents
Kurzweil-Henstock type integral in fourier analysis on compact zero-dimensional group
2009
Abstract A Kurzweil-Henstock type integral defined on a zero-dimensional compact abelian group is studied and used to obtain a generalization of some results related to the problem of recovering, by generalized Fourier formulae, the coefficients of convergent series with respect to the characters of such a group.
NUMERICAL ALGORITHMS
2013
For many systems of differential equations modeling problems in science and engineering, there are natural splittings of the right hand side into two parts, one non-stiff or mildly stiff, and the other one stiff. For such systems implicit-explicit (IMEX) integration combines an explicit scheme for the non-stiff part with an implicit scheme for the stiff part. In a recent series of papers two of the authors (Sandu and Zhang) have developed IMEX GLMs, a family of implicit-explicit schemes based on general linear methods. It has been shown that, due to their high stage order, IMEX GLMs require no additional coupling order conditions, and are not marred by order reduction. This work develops a …
Investigating effects in GNSS station coordinate time series
2014
The vertical and horizontal displacements of the Earth can be measured to a high degree of precision using GNSS. Time series of Latvian GNSS station positions of both the EUPOS®-Riga and LatPos networks have been developed at the Institute of Geodesy and Geoinformation of the University of Latvia (LU GGI). In this study the main focus is made on the noise analysis of the obtained time series and site displacement identification. The results of time series have been analysed and distinctive behaviour of EUPOS®-Riga and LatPos station coordinate changes have been identified. The possible dependences of GNSS station coordinate distribution on EPN station problems, seismic activity of some area…
Geobotanical approach to detect land-use change of a Mediterranean landscape: a case study in Central-Western Sicily
2018
A landscape is a palimpsest of the interactions between human activities and ecological dynamics. In an interdisciplinary perspective of dialogue between the ‘Two Cultures’ (Natural Sciences and Humanities), a study of a rural area has been carried out through a reading of plant ecosystems as signs of human impact. The purpose of this paper—as part of the project ‘Harvesting Memories’: Ecology and landscape archaeology of Castro/Giardinallo Valley and Mt. Barrau district (Corleone, Palermo, Sicily)—is to analyse the formative-processes of a Sicilian rural landscape and its changes in the last century. A key element in the reconstruction of the formation of the present landscape is the serie…
CloudSim: A fair benchmark for comparison of methods for times series reconstruction from cloud and atmospheric contamination
2015
Cloud contamination of optical data is a constant and annoying feature of time series analyses, whether while using vegetation indices or surface temperatures, since it tends to decrease artificially the values taken by these parameters. Therefore, any time series analysis of optical data needs a previous step for gap-filling reconstruction of the time series. Numerous techniques have been presented in the literature to carry out this preliminary and mandatory step. However, the evaluation and comparison of these techniques is difficult, since no “truth” time series is available. We present here a probabilistic model (CloudSim) to provide global typical annual time series for NDVI (Normaliz…
Structure function as a tool in AE and Dst time series analysis
1995
A new method to analyse the structure function (SF) has been constructed and used in the analysis of the AE time series for the years 1978-85 and Dst time series for 1957-84. It is shown that this SF analysis makes a clear distinction between affine and periodicity dominated time series, and it displays the essential periodicities of the series in a range relevant to its characteristic time scale. The AE time series is found to be affine such that the scaling exponent changes at a time scale of 113 (±9) minutes. On the other hand, in the SF function analysis, the Dst data are dominated by the 24-hour and 27-day periods. The 27-day period is modulated by the annual variation.
Improvement of gross motor and cognitive abilities by an exercise training program: three case reports
2014
Marianna Alesi,1 Giuseppe Battaglia,2 Michele Roccella,1 Davide Testa,1 Antonio Palma,2 Annamaria Pepi1 1Department of Psychology, 2Department of Law, Social and Sport Science, University of Palermo, Palermo, Italy Background: This work examined the efficacy of an integrated exercise training program (coach and family) in three children with Down syndrome to improve their motor and cognitive abilities, in particular reaction time and working memory. Methods: The integrated exercise training program was used in three children with Down syndrome, comprising two boys (M1, with a chronological age of 10.3 years and a mental age of 4.7 years; M2, with a chronological age of 14.6 years and a ment…
Functional data analysis for optimizing strategies of cash flow management
2015
The cash management deals with problem of automating and managing cash flow processes. Optimization of the management processes greatly reduces overall cash handling costs. The present analysis is an empirical study of cash flows, from and to bank branches, deriving an underlying theoretical framework, which can in a reasonable way be connected with the optimal strategy. Functional data analysis is considered an appropriate framework to analyse the dynamics of the time series behavior of cash flows: since the observations are not equally spaced in time and their number is different for each series, they are converted in a collection of random curves in a space spanned by finite dimensional …
Exact simulation of first exit times for one-dimensional diffusion processes
2019
International audience; The simulation of exit times for diffusion processes is a challenging task since it concerns many applications in different fields like mathematical finance, neuroscience, reliability horizontal ellipsis The usual procedure is to use discretization schemes which unfortunately introduce some error in the target distribution. Our aim is to present a new algorithm which simulates exactly the exit time for one-dimensional diffusions. This acceptance-rejection algorithm requires to simulate exactly the exit time of the Brownian motion on one side and the Brownian position at a given time, constrained not to have exit before, on the other side. Crucial tools in this study …
Optimizing and comparing gap-filling techniques using simulated NDVI time series from remotely sensed global data
2019
Abstract NDVI (Normalized Difference Vegetation Index) time series usually suffer from remaining cloud presence, even after data pre-processing. To address this issue, numerous gap-filling (or reconstruction) techniques have been developed in the literature, although their comparison has mainly been local to regional, with only two global studies to date, and has led to sometimes contradictory results. This study builds on these different comparisons, by testing different parameterizations for five NDVI temporal profile reconstruction techniques, namely HANTS (Harmonic Analysis of Time Series), IDR (iterative Interpolation for Data Reconstruction), Savitzky-Golay, Asymmetric Gaussian and Do…