Search results for "dynamique"
showing 10 items of 187 documents
Behaviour of common estimators in dynamic error-components models with autocorrelated disturbances
1997
The purpose of this paper is to make a presentation of the properties of a set of estimators comprising the within, between, OLS and GLS estimators in the study of dynamic error - components models with autocorrelated disturbances. We underline in this study the importance of the statistical distribution governing the initial values for the process and the structure of xit variable for the limiting values of the estimators when the temporal dimension is fixed but the individual dimension N grows indefinitly.
Controlling rotational dynamics of molecules by shaped ultra-short laser pulses
2004
This manuscript presents various studies falling under the set of themes of coherent control. We establish, as well theoretically as in experiments, the possibility of finely handling the rotational dynamics of linear molecules. In order to operate this handling, the ultra-short pulses are shaped by a pulse shaper. Its principle and its installation are described in a detailed way. The rotational dynamics of the linear nitrogen molecule (N2) is handled while exploiting the relative excitation between the even and odd rotational components of the wavepacket in weak mode of field. That, we chose a periodic phase modulation well defined of the exiting pulse. A temporal analysis comes to clarif…
Analyse expérimentale et numérique du comportement de véhicules terrestres en présence d'un vent latéral instationnaire
2013
The automotive manufacturers are nowadays more and more interested in crosswind aerodynamics. Indeed, the driver is subjected every day to strong side air flows, for example when overtaking another vehicle or when passing through a lateral wind wall, generated by terrain topography (as in the case of the passage near the empty space between two buildings).The aerodynamic efforts generated in these situations can lead to undesired lateral deviations,which can be dramatic if the driver is surprised. Different experimental studies, reproducing the effects of a dynamic yaw angle, pointed out the issues of the steady methods, commonly used to qualify the vehicle crosswind behaviour. Little is st…
Population dynamics and genetics of European Pond Turtle Emys orbicularis
2013
Dispersal, characterized by the movements of individuals in space leading to gene flows, allows populations to connect. The study of dispersal has become of essential importance to predict the consequences of global changes on the population structures and dynamics. Species with limited dispersal, such as chelonians, are particularly threatened by these phenomena. Our study aimed at analyzing the dispersal of the European pond turtle (Emys orbicularis), in decline in Europe, in a habitats fragmentation context and determining the causes of this behavior through analysis of population dynamics and genetics. Our results show, firstly, that the slow generation time in Emys orbicularis (about 1…
Identity dynamics and social partitions : the case of identity "racial" Blacks in France
2011
Our research work investigates - from a psycho-social point of view - the «racial» identity of the black population in France, notably in their relation with the white population, so as to point up the identity dynamics that exist between the various groups. The theoretical framework is related to social grouping and one of its developments, i.e. the concept of social partitioning. Such conception is based on the existence of several types of inter-category relations (partitioning) that allow apprehending the nature of individuals’ identity positioning within the framework of an inter-group relation and make it dynamic through the notion of co-construction. Our methodology is based mainly o…
Entre la diversité institutionnelle et la dynamique locale, les effets contextuels ...
1993
actes des journées scientifiques sur le changement en éducation, Paris, Université René Descartes-Paris 5, 11-13 janvier 1990] / [organisées par l'Unité de recherche associée au CNRS Sociologie de l'éducation]; International audience
Descriptive and hedonic temporal sensory analysis
2016
Over the last years, so-called rapid methods for sensory evaluation have been developed to collect sensory description of products from consumers. Moving forward in this direction, this thesis proposes to pair Temporal Dominance of Sensations (TDS) with dynamic liking. This new method, named Temporal Drivers of Liking (TDL), highlights sensory drivers of consumer liking and determines how the dynamic perception can impact the hedonic response. This work proposes to compute the Liking While Dominant (LWD) score as the average liking scores given to a product while a given attribute was perceived as dominant and to look at its deviation from the mean liking score of this product. When signifi…
Contribution of a new dynamic climate regionalization protocol for estimating the water balance of Douglas-fir forests
2022
Quantifying the regionalized impacts of climate change on forests is a major ecologicaland socio-economic issue. The decline of Douglas-fir (Pseudotsuga menziesii) has been observed forabout 20 years and should be accelered. Recent work shows that regionalized estimation of waterbalance under forest canopy is hampered by the ability of regional climate models to correctlysimulate precipitation amount and seasonal cycle. Here we evaluate the ability of a new climateregionalization protocol to simulate a realistic precipitation regime required for the calculation offorest soil water balance.
Influence of the Madden-Julian Oscillation on Southern African summer rainfall
2007
Rain-causing mechanisms over Southern Africa (south of 15˚S) involve both tropical and temperate dynamics. Most studies focused on the synoptical timescale, while the intraseasonal (20-120 days) variability has more been neglected to date. This study aims at determining whether the dominant mode of intraseasonal variability in the Tropics, namely the Madden-Julian Oscillation (MJO), has a significant impact on Southern African rainfall and associated atmospheric dynamics. The examination of outgoing longwave radiation (OLR) over Southern Africa shows indeed significant intraseasonal fluctuations at the 30-60 day timescale, i.e. in the pe- riods that are typically reminiscent of the MJO. In ord…
Solid-state diffusion phenomena in heterogeneous gas-solid reactions : Application to oxides sulfidation
2018
Phase transition phenomena involving the mobility of the reaction interface are involved in a wide variety of chemical reactions and applications. A good example is the sulfidation reaction experienced by the metal oxide-based materials used in the framework of gas purification or catalysts preparation applications. These reactions involve solid-state diffusion phenomena of the reactive species (atomic or ionic form) through the layer of product formed during the reaction (oxide, sulfide, or metal phase). In many cases, solid-state diffusion has a direct impact on the reaction mechanisms while determining the growth direction of the formed phases, as well as the overall kinetics of the reac…