Search results for "Cohérence"
showing 10 items of 15 documents
Automatisation des tableaux de bord et cohérence des comportements
2007
International audience; Cet article a pour objet de s'interroger sur les rapports entre l'automatisation des tableaux de bord et la cohérence des comportements. Il ressort de l'étude de deux cas, celui d'une entreprise industrielle et celui d'une banque, que l'augmentation de la formalisation ne crée pas davantage de rigidité mais produit au contraire plus de dynamique ou de continuité et de permanence. Cependant, les résultats montrent aussi la limite d'une gestion automatique de la cohérence dans la mesure où la production des informations nécessaires à l'adaptation à long terme de la firme semble difficilement automatisable.
Dynamique induite par champ laser femtoseconde intense : alignement moléculaire en milieu gazeux dense et effet Kerr
2011
This thesis is devoted to the study of dynamics induced by intense femtoseconds lasers pulses. The first studied dynamics deals with molecular alignment of CO2-X mixtures (X=CO2, Ar, N2), in dense gases (up to 20 bar). Up to now, this regime has never been studied experimentally. In the field-free regime (after laser/matter interaction), molecular alignment exhibits two components : a permanent alignment and a transient one. The influence of collisions appears through population transfers between rotational states, which leads to a decrease of these two contributions. Permanent alignment relaxation time is only tied to inelastics collisions whereas transient alignment relaxation time is tie…
Spatial coherence and potential predictability of intraseasonal descriptors of the rainy season in Soudano-Sahelian Africa : application to the pearl…
2010
The aim of this thesis is twofold : (i) fill a lack of knowledge about the spatial coherence and seasonal predictability of the intraseasonal characteristics (ISC) of the soudano-sahelian rainy season. These ISC are the seasonal rainfall amount (S), the daily rainfall frequency > 1 mm (O), the daily rainfall mean intensity (I), the dates of the onset and withdrawal of the rainy season, the mean length of the dry (LDS) and/or wet spells (LWS) ; (ii) document the climate-agriculture relationship over the Niamey area based on the millet crop example.From FRIEND-AOC daily rainfall records (1950-2000) for a 136 stations-network located in Senegal, Mali, Burkina-Faso and Niger, the spatial cohere…
Génération et interfaçage de lumière à photon unique et contrôle de la dynamique atomique ultra-rapide pour l’information quantique
2010
We develop a robust and realistic mechanism for the generation of indistinguishable single-photon (SP) pulses with identical frequency and polarization. They are produced on demand from a coupled double-Raman atom-cavity system driven by a sequence of laser pump pulses. This scheme features a high efficiency, the ability to produce a sequence of narrow-band SP pulses with a delay determined only by the pump repetition rate, and simplicity of the system free from complications such as repumping process and environmental dephasing. We propose and analyze a simple scheme of parametric frequency conversion for optical quantum information in cold atomic ensembles. Its remarkable properties are m…
Diagnosis and predictability of intraseasonal characteristics of wet and dry spells over equatorial east Africa
2010
Most of Eastern Africa has arid and semi-arid climate with high space-time variability in rainfall. The droughts are very common in this region, and often persist for several years, preceded or followed by extreme floods. Most of the livelihoods and socio-economic activities however remain rain-dependent leading to severe negative impacts during the periods of occurrence of climate extremes. It has been noted that one extreme event was capable of reversing national economic growth made over a period of several years. Thus no sustainable development can be attained in eastern Africa without effective mainstreaming of climate information in the development policies, plans and programmes. Many…
Évènements extrêmes et turbulence optique
2010
National audience; Nous montrons l'impact de l'incohérence dans un système hamiltonien sur l'émergence d'événements extrêmes de types ondes scélérates, en analysant l'évolution à long terme du champ optique. Trois régimes sont identifiés: le premier (i) est caractérisé par des ondes persistantes, le second (ii) est marqué par des ondes intermittentes et le dernier (iii) par de rares ondes sporadiques.
Alignement moléculaire par impulsions laser ultrabrèves : Mesures & Applications
2009
The interaction of an intense ultrashort laser pulse with a molecular sample leads, after the end of the pulse, to molecular alignment at specific time under field-free conditions. This thesis is dedicated to the measurements and applications of this effect. The degree of alignment is determined through the variation of the refractive index induced by the rearrangement of the molecular dipoles. A two-dimensional technique allowing to measure molecular alignment on a single-shot basis is reported in this document. The alignment is then exploited in order to determine physical quantities which are usually difficult to estimate through others methods. The "cross-defocusing technique" has been …
ScaleSem : model checking and semantic web
2012
The increasing development of networks and especially the Internet has greatly expanded the gap between heterogeneous information systems. In a review of studies of interoperability of heterogeneous information systems, we find that all the work in this area tends to be in solving the problems of semantic heterogeneity. The W3C (World Wide Web Consortium) standards proposed to represent the semantic ontology. Ontology is becoming an indispensable support for interoperability of information systems, and in particular the semantics. The structure of the ontology is a combination of concepts, properties and relations. This combination is also called a semantic graph. Several languages have bee…
ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE
2007
This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule…
Automatisation des tableaux de bord et cohérence du contrôle de gestion : à propos de deux cas
2007
Cet article presente les resultats d’une enquete exploratoire dont l’objet est l’etude des rapports entre l’automatisation des tableaux de bord et la coherence du controle de gestion. A partir de deux cas juges exemplaires, celui d’une entreprise industrielle et celui d’une banque, nous etudions cette relation sous l’angle du partage des representations et de la coherence des comportements. Il en ressort que l’augmentation de la formalisation ne cree pas davantage de rigidite mais produit au contraire plus de dynamique ou de continuite et de permanence. Cependant, les resultats montrent aussi la limite d’une gestion automatique de la coherence dans la mesure ou les informations necessaires …