Dans la situation d’un radar monostatique la configuration diédrique présente l’avantage de renvoyer un signal fort grâce au mécanisme de double rebond. De plus, il s’agit d’une configuration omniprésente par exemple en zone urbaine, avec des structures rue-bâtiment, ou en forêt, avec des structures de type sol-arbre. Les signaux rétrodiffusés sont donc liés à ces structures, plus précisément aux matériaux les composant, via leurs permittivités diélectriques. Retrouver ces permittivités depuis la mesure des champs rétrodiffusés permettrait l’identification des matériaux de la structure diédrique. Ceci mène à des applications telles que la détection de défauts dans la structure, l’estimation de la teneur en eau des sols ou du béton, ou in fine à des thématiques de classification, pour des objets dans des images radar par exemple, ou de détection de changement. En modélisant le mécanisme de double rebond lié à la structure de dièdre par deux réflexions successives via les coefficients de Fresnel, trois méthodes d’inversion des permittivités ont été mises en place au cours de la thèse. La première, analytique, utilise à un angle d’incidence donné la mesure des champs copolarisés. Les deux autres méthodes, alliant une partie analytique et une partie numérique, nécessitent la mesure, du ratio polarimétrique pour l’une, du champ horizontal pour l’autre, effectuée à deux angles d’incidence différents. Ces méthodes ont été validées numériquement à l’aide de la méthode d’Optique Géométrique fournie par le logiciel FEKO. Des mesures en chambre anéchoique ont été effectuées afin de valider ces méthodes. De même une mesure in-situ a été effectuée sur un dièdre en béton formé par un angle entre deux murs. / For a monostatic radar, the dihedral arrangementexhibits a strong response compare tobare surface. This phenomenon can be seen in radarimages of urban areas or forestry as building andstreets and trunks and ground are forming such structures.This signature can be modelled with the doublebounce equation as a cascade of Fresnel reflectioncoefficients. These coefficients depend on the permittivitiesof the structures. Finding these permittivitiesfrom the backscattered fields may allowed to identifythe materials involved in the dihedral. Thereforethiscan be applied for default detection, moisture retrievaland classification topics for instance.By modelling the double bounce scattering with Fresnelcoefficients, three methods have been developedto retrieve these permittivities. The first one uses asingle incidence angle and the measurements of copolarisedfields. The last two methods need the measurementof the copolarised fields ratio or of the horizontalelectric field alone at two different incidenceangles. All these methods have been validated, firstnumerically using FEKO RL-GO method, then experimentally,with measurements in anechoic chamber. Atlast, in-situ measurements have been performed on awall corner made of concrete to assess the methodon a real case.

O consumo domiciliar de microcomputadores cresceu de forma acelerado nos últimos anos. Apesar de grupos com determinadas características socioeconômicas terem um consumo maior de computadores, o consumo vem aumentando em todos os grupos. Ou seja, mesmo com diferenças grandes, o consumo de computadores não é mais uma exclusividade dos mais ricos, dos mais bem instruídos ou de determinadas regiões do país. Os modelos Probit e double-hurdle se mostraram adequados para analisar o consumo de computadores no Brasil. O modelo Probit ajustou bem os dados na análise da presença de um computador no domicílio. Já para a despesa com computador, o modelo double-hurdle se mostrou melhor que o modelo Tobit, uma vez que este separa a análise do processo de decisão de compra em dois, separando a decisão de gastar da decisão de quanto gastar. / Household consumption of microcomputers grew up fast in recent years. Despite some socioeconomic groups take highercomputer consumption, consumption is increasing in all groups. In other words, even with large differences, the consumption of computers is no longer uniqueness of wealthier, better educated or at certain regions of the country. Probit and double-hurdle models were suitable for analyzing the consume of computers in Brazil. The Probit model adjusted well the data set in the analysis of the presence of a computer at home. For the computer spending the double-hurdle model proved better than Tobit because separates the analysis of the purchase decision process in two, separating the decision to spend from the decision of how much spend.

Univ., Diss.--Trier, 2006.

Reproduction de : Thèse doctorat : Génie civil : Cergy-Pontoise : 2005. / Titre provenant de l'écran titre. Bibliogr. f.197-204. Index.

No description available.

The indole alkaloids, a class of natural products, have received much synthetic attention for years due to their diverse structures and interesting biological properties. We are particularly interested in synthesizing some of the yohimbine alkaloids extracted from the bark of a tall evergreen African tree (Corynanthe yohimbe, commonly known as fringe tree). Yohimbine and its stereoisomers have been tempting targets for synthetic organic chemists for more than fifty years. These compounds feature a pentacyclic ring system with two heteroatoms and five stereogenic centers. Broadly, the fifteen different synthetic approaches that led to the successful completion of yohimbine alkaloids relied only on two basic synthetic strategies. In the first strategy, the last step almost always was the formation of the C(2)-C(3) bond by either Pictet-Spengler reaction or by Bischler-Napieralski reaction with the concomitant formation of the C ring. The second strategy involved the annulation of the D and E rings onto the intact ABC ring system. With our double annulation methodology, herein, we report a completely different synthetic approach to access the yohimbine alkaloids, and our disconnections are not even remotely close to the synthetic designs used in the past. Our key steps include double Michael reaction to construct the E ring, an intramolecular cyclization to construct the D ring, and finally, the functionality on the D ring can be elaborated to form the C ring of the yohimbine alkaloids.

Thesis (Maste). / Collection of master theses of the postgraduate LLM program "International Tax Law", Viennna University of Economics and Business Administration.

The New Grove Dictionary of Jazz defines “double time” as “the apparent doubling of the tempo […] achieved by halving the prevailing note value.” A more precise term for this concept is “double-time feel.” The question of how a musical performance creates double-time feel has received little scholarly attention. Grove’s explanation is incomplete because “halving the prevailing note value” is sometimes perceived by listeners as diminution within an unchanged tempo. My hypothesis is that swing rhythm, pervasive in many styles of jazz, not only facilitates the use of double-time feel but allows for subtle gradations in its use. I offer a model that classifies rhythms according to how strongly they support (or undermine) a double-time feel in a swing rhythm context, and I apply the model to performances by Louis Armstrong and Lee Morgan. My analysis demonstrates these artists’ fine-grained control over double-time feel and suggests directions for future research.

Doctorat en droit / info:eu-repo/semantics/nonPublished

O consumo domiciliar de microcomputadores cresceu de forma acelerado nos últimos anos. Apesar de grupos com determinadas características socioeconômicas terem um consumo maior de computadores, o consumo vem aumentando em todos os grupos. Ou seja, mesmo com diferenças grandes, o consumo de computadores não é mais uma exclusividade dos mais ricos, dos mais bem instruídos ou de determinadas regiões do país. Os modelos Probit e double-hurdle se mostraram adequados para analisar o consumo de computadores no Brasil. O modelo Probit ajustou bem os dados na análise da presença de um computador no domicílio. Já para a despesa com computador, o modelo double-hurdle se mostrou melhor que o modelo Tobit, uma vez que este separa a análise do processo de decisão de compra em dois, separando a decisão de gastar da decisão de quanto gastar. / Household consumption of microcomputers grew up fast in recent years. Despite some socioeconomic groups take highercomputer consumption, consumption is increasing in all groups. In other words, even with large differences, the consumption of computers is no longer uniqueness of wealthier, better educated or at certain regions of the country. Probit and double-hurdle models were suitable for analyzing the consume of computers in Brazil. The Probit model adjusted well the data set in the analysis of the presence of a computer at home. For the computer spending the double-hurdle model proved better than Tobit because separates the analysis of the purchase decision process in two, separating the decision to spend from the decision of how much spend.