Search results for " variability"
showing 10 items of 853 documents
Experimental validation of a distribution theory based analysis of the effect of manufacturing tolerances on permanent magnet synchronous machines
2017
An experimental study on the effect of permanent magnet tolerances on the performances of a Tubular Linear Ferrite Motor is presented in this paper. The performances that have been investigated are: cogging force, end effect cogging force and generated thrust. It is demonstrated that: 1) the statistical variability of the magnets introduces harmonics in the spectrum of the cogging force; 2) the value of the end effect cogging force is directly linked to the values of then remanence field of the external magnets placed on the slider; 3) the generated thrust and its statistical distribution depend on the remanence field of the magnets placed on the translator.
Bayesian Analysis of Population Health Data
2021
The analysis of population-wide datasets can provide insight on the health status of large populations so that public health officials can make data-driven decisions. The analysis of such datasets often requires highly parameterized models with different types of fixed and random effects to account for risk factors, spatial and temporal variations, multilevel effects and other sources on uncertainty. To illustrate the potential of Bayesian hierarchical models, a dataset of about 500,000 inhabitants released by the Polish National Health Fund containing information about ischemic stroke incidence for a 2-year period is analyzed using different types of models. Spatial logistic regression and…
Multiscale partial information decomposition of dynamic processes with short and long-range correlations: theory and application to cardiovascular co…
2022
Abstract Objective. In this work, an analytical framework for the multiscale analysis of multivariate Gaussian processes is presented, whereby the computation of Partial Information Decomposition measures is achieved accounting for the simultaneous presence of short-term dynamics and long-range correlations. Approach. We consider physiological time series mapping the activity of the cardiac, vascular and respiratory systems in the field of Network Physiology. In this context, the multiscale representation of transfer entropy within the network of interactions among Systolic arterial pressure (S), respiration (R) and heart period (H), as well as the decomposition into unique, redundant and s…
Remote heart rate variability for emotional state monitoring
2018
International audience; Several researches have been conducted to recognize emotions using various modalities such as facial expressions , gestures, speech or physiological signals. Among all these modalities, physiological signals are especially interesting because they are mainly controlled by the autonomic nervous system. It has been shown for example that there is an undeniable relationship between emotional state and Heart Rate Variability (HRV). In this paper, we present a methodology to monitor emotional state from physiological signals acquired remotely. The method is based on a remote photoplethysmography (rPPG) algorithm that estimates remote Heart Rate Variability (rHRV) using a …
A spatial multilevel analysis of Italian SMEs Productivity
2009
In this paper, we adapt multilevel analysis methods to investigate the spatial variability of SMEs productivity across the Italian territory, and account for differences in the socio-economic context. Our results suggest that to properly capture the variability of the data, it is important to allow for both spatial mean and slope effects. Social decay has the expected negative impact. However, while this effect is larger on firms with smaller capital intensity, firms with higher capital intensity seem to be less affected by geography. Greater territorial heterogeneity emerges among those firms with lower capital to labour ratios.
A Spatial Multilevel Analysis of Italian SMEs Productivity
2009
Abstract In this paper, we adapt multilevel analysis methods to investigate the spatial variability of SMEs' productivity across the Italian territory, and account for differences in the socio-economic context. Our results suggest that to properly capture the variability of the data, it is important to allow for both spatial mean and slope effects. Social decay has the expected negative impact. However, while this effect is larger on firms with smaller capital intensity, firms with higher capital intensity seem to be less affected by geography. Greater territorial heterogeneity emerges among those firms with lower capital to labour ratios. Une analyse spatiale a plusieurs niveaux de la prod…
The effect of mechanical defects on the strength distribution of elementary flax fibres
2009
Flax fibres are finding non-traditional applications as reinforcement of composite materials. The mechanical properties of fibres are affected by the natural variability in plant as well as the damage accumulated during processing, and thus have considerable variability that necessitates statistical treatment of fibre characteristics. The strength distribution of elementary flax fibres has been determined at several fibre lengths by standard tensile tests, and the amount of kink bands in the fibres evaluated by optical microscopy. Strength distribution function, based on the assumption that the presence of kink bands limits fibre strength, is derived and found to provide reasonable agreemen…
An improved perspective in the representation of soil moisture: potential added value of SMOS disaggregated 1 km resolution product
2018
Abstract. This study uses the synergy of multiresolution soil moisture (SM) satellite estimates from the Soil Moisture Ocean Salinity (SMOS) mission, a dense network of ground-based SM measurements, and a Soil Vegetation Atmosphere Transfer (SVAT) model, SURFEX (Externalized Surface) – module ISBA (Interactions between Soil-Biosphere-Atmosphere), to examine, i) the comparison and suitability of different operational SMOS SM products to provide realistic information on the water content of the soil as well as the added value of the newly released SMOS Level 4 3.0 all weather disaggregated ~ 1 km SM (SMOS_L4 3.0 ), and ii) its potential impact for improving uncertainty associated to SM initia…
Genetic diversity in Cytisus aeolicus Guss. (Leguminosae), a rare endemite of the Italian flora
1998
ABSTRACT Cytisus aeolicus Guss, is an endemic plant restricted to the isles of Vulcano, Stromboli and Alicudi in the Aeolian archipelago. All known populations were assayed for genetic variability using enzyme polymorphism. Allozyme variation at 16 loci coding for 10 enzyme systems was examined. The great majority of loci turned out to be monomorphic or fixed heterozygous. The observed genetic depauperation is indicative of historical factors, such as the bottleneck effect associated with migration, and the founder effect in population re-establishment. The low genetic diversity is largely partitioned within rather than among populations, indicating that extant populations have not been est…
Exploring the spatial relationship between airborne-derived red and far-red sun-induced fluorescence and process-based GPP estimates in a forest ecos…
2019
International audience; Terrestrial gross primary productivity (GPP) plays an essential role in the global carbon cycle, but the quantification of the spatial and temporal variations in photosynthesis is still largely uncertain. Our work aimed to investigate the potential of remote sensing to provide new insights into plant photosynthesis at a fine spatial resolution. This goal was achieved by exploiting high-resolution images acquired with the FLuorescence EXplorer (FLEX) airborne demonstrator HyPlant. The sensor was flown over a mixed forest, and the images collected were elaborated to obtain two independent indicators of plant photosynthesis. First, maps of sun-induced chlorophyll fluore…