Search results for "Statistical"
showing 10 items of 4960 documents
Numerical study of blow-up and stability of line solitons for the Novikov-Veselov equation
2017
International audience; We study numerically the evolution of perturbed Korteweg-de Vries solitons and of well localized initial data by the Novikov-Veselov (NV) equation at different levels of the 'energy' parameter E. We show that as |E| -> infinity, NV behaves, as expected, similarly to its formal limit, the Kadomtsev-Petviashvili equation. However at intermediate regimes, i.e. when |E| is not very large, more varied scenarios are possible, in particular, blow-ups are observed. The mechanism of the blow-up is studied.
A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-me…
2011
[EN] The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individua…
Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly…
2011
[EN] Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results pr…
Modified Landau levels, damped harmonic oscillator and two-dimensional pseudo-bosons
2010
In a series of recent papers one of us has analyzed in some details a class of elementary excitations called {\em pseudo-bosons}. They arise from a special deformation of the canonical commutation relation $[a,a^\dagger]=\1$, which is replaced by $[a,b]=\1$, with $b$ not necessarily equal to $a^\dagger$. Here, after a two-dimensional extension of the general framework, we apply the theory to a generalized version of the two-dimensional Hamiltonian describing Landau levels. Moreover, for this system, we discuss coherent states and we deduce a resolution of the identity. We also consider a different class of examples arising from a classical system, i.e. a damped harmonic oscillator.
Southern-Tyrrhenian seismicity in space-time-magnitude domain
2006
An analysis is conducted on a catalogue containing more than 2000 seismic events occurred in the southern Tyrrhenian Sea between 1988 and October 2002, as an attempt to characterise the main seismogenetic processes active in the area in space, time and magnitude domain by means of the parameters of phenomenological laws. We chose to adopt simple phenomenological models, since the low number of data did not allow to use more complex laws. The two main seismogenetic volumes present in the area were considered for the purpose of this work. The first includes a nearly homogeneous distribution of hypocentres in a NW steeply dipping layer as far as a…
Visualization of Parameter Sensitivity of 2D Time-Dependent Flow
2018
In this paper, we present an approach to analyze 1D parameter spaces of time-dependent flow simulation ensembles. By extending the concept of the finite-time Lyapunov exponent to the ensemble domain, i.e., to the parameter that gives rise to the ensemble, we obtain a tool for quantitative analysis of parameter sensitivity both in space and time. We exemplify our approach using 2D synthetic examples and computational fluid dynamics ensembles.
Topology of correlation-based minimal spanning trees in real and model markets
2003
We present here a topological characterization of the minimal spanning tree that can be obtained by considering the price return correlations of stocks traded in a financial market. We compare the minimal spanning tree obtained from a large group of stocks traded at the New York Stock Exchange during a 12-year trading period with the one obtained from surrogated data simulated by using simple market models. We find that the empirical tree has features of a complex network that cannot be reproduced, even as a first approximation, by a random market model and by the one-factor model.
Statistical analysis of latency outcomes in behavioral experiments
2011
In experimental designs of animal models, memory is often assessed by the time for a performance measure to occur (latency). Depending on the cognitive test, this may be the time it takes an animal to escape to a hidden platform (water maze), an escape tunnel (Barnes maze) or to enter a dark component (passive avoidance test). Latency outcomes are usually statistically analyzed using ANOVAs. Besides strong distributional assumptions, ANOVA cannot properly deal with animals not showing the performance measure within the trial time, potentially causing biased and misleading results. We propose an alternative approach for statistical analyses of latency outcomes. These analyses have less distr…
On the Statistical Properties of the Capacity of Spatially Correlated Nakagami-M MIMO Channels
2008
This paper studies the statistical properties of the channel capacity of spatially correlated Nakagami-m multiple- input multiple-output (MIMO) channels. We have derived closed- form expressions for the probability density function (PDF), the cumulative distribution function (CDF), the level-crossing rate (LCR), and the average duration of fades (ADF) of the lower bound on the channel capacity. In order to study the impact of the spatial correlation on the channel capacity, the analysis of the statistical properties of the channel capacity is carried out for different receiver antenna spacings. It is observed that the antenna spacing has a significant influence on the spread and maximum val…
On the statistical properties of the capacity of sparse multipath fading channels
2014
Most existing works in wireless communications assume rich scattering. However, there is growing experimental evidence that physical wireless channels can exhibit a sparse structure. By assuming an asymmetric Doppler power spectral density (PSD), we can model and simulate sparse channels by using a finite sum of weighted complex harmonic functions, also called sum of cisoids (SOC). In this paper, we focus on the analysis of the statistical properties of the instantaneous capacity of sparse SOC-based multipath fading channels under line-of-sight (LOS) conditions. The probability density function (PDF), the cumulative distribution function (CDF), the level-crossing rate (LCR), and the average…