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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Formalisme d'octet applique à la propagation d'ondes dans des milieux piezoélectriques inhomogènes / Octet formalism applied for wave propagation in piezoelectric inhomogeneous media

Lam, Mountaga 05 December 2008 (has links)
Le développement de matériaux piézoélectriques innovants pour la réalisation de transducteurs, de capteurs ou d'actionnneurs nécessite la mise en oeuvre de dispositifs de caractérisation performants. Dans ce contexte, ce document propose des méthodes de modélisation de la propagation d'ondes ultrasonores dans des structures multicouches ou a gradients continus de propriétés. Au préalable, deux méthodes de caractérisation, ont été exposées et appliquées à des céramiques de type PZT. L'une d'entre elle, appelée méthode de spectroscopie de transmission, utilise une mise en forme matricielle de l'équation de propagation des ondes accoustiques. Cette formulation analytique facilite la résolution de l'équation de propagation, et permet également une représentation des phénomènes de transmissions d'ondes à travers une structure. La validité de ces modèles est clairement établie à travers des hétérostructures piézoélectriques. / The developpement of innovative piezoelectric materials for achievement of transducers, sensors or actuators requires the implementation of hight performance of characterization method. In this context, this document proposes two methods modeling the ultrasonic wave propagation in multilayered structures and continutes graded materials. Prior, two models of characterizations were presented and applied for PZT ceramics. They use a matrix formalism of the equation of accoustic waves. This analytical formulation facilitates the resolution of the propagation equation of propagation, and facilitate the representation of the phenomena of wave transmission through a structure. The validity of these models is clearly established through comparisons of results from finite element and measurement in piezoelectric heterostructures.
2

The marketing of facsimile transceivers in Hong Kong /

Yung, Yuen-sun. January 1985 (has links)
Thesis (M.B.A.)--University of Hong Kong, 1985.
3

Numerical model of the transient behavior of a copper-water heat pipe

Etter, Christy L. 05 1900 (has links)
No description available.
4

De la transmission au partage des savoirs selon Jacques Maritain et Paulo Freire : prolégomènes à une pédagogie du développement en Afrique / As from the transmission to the sharing of knowledge, according to Jacques Maritain and Paulo Freire : the introduction to the pedagogy of developpement in Africa

Ruguduka Baleke, Stanislas 12 December 2009 (has links)
La notion du développement de l’Afrique est essentiellement liée à son histoire, et particulièrement à celle des indépendances. Les peuples d’Afrique espéraient que l’accession à l’indépendance politique, allait suivre une indépendance économique, synonyme du développement humain. Mais tel ne fut pas le cas. A son tour, l’éducation, au lieu de former des personnes capables d’apporter leur savoir être et leur savoir faire à la construction d’une société juste pour le développement, elle s’est contenté d’importer la forme scolaire occidentale et de mettre en place des politiques économiques libérales. Aujourd’hui, il n’est plus question de reprendre ce chemin. Le développement n’aura aucun sens s’il n’est pas solidaire, authentique et intégral. Ce travail s’inscrit dans une démarche consistant à construire une version authentiquement africaine du développement. Celle-ci est indissociable d’une philosophie de l’éducation pour l’Afrique, dont l’exploitation et la construction seront les objectifs de cette thèse. Un penseur s’est déjà engagé sur cette voie : c’est Jacques Maritain. En s’opposant à une philosophie libérale de l’éducation, il a ouvert les perspectives d’une éducation au développement solidaire. Dans le contexte de l’Amérique latine, un autre penseur et pédagogue, Paulo Freire, a réfléchi sur un paradigme éducatif alternatif. La recherche d’une nouvelle philosophie éducative pour l’Afrique passe par l’étude comparative de ces deux auteurs contemporains. / The notion of the development of Africa is primarily tributary to its history and specifically to that of its independence. The African people expected that the accession to political independence would be followed by the economical independence that is instrumental in human development. The African Educational system has imported the western education prototype and has put in place free market policies instead of training/educating/moulding individuals capable of contributing with their intellectual and practical knowledge towards the making of a fair society that enhances development. To date, it is out of question to stick to this model. Development will not have any meaning if it is not genuine, showing solidarity and inclusiveness. This work is intended to conceive a typically genuine African model of development. This is ultimately linked /inseparable to the African philosophy of education whose concerns and making will constitute the objectives of this thesis. A philosopher, Jacques Maritain has already explored that possibility. While opposing the liberal education system, he has opened prospects to education for [development that shows solidarity /communal development] . Within Latin America’s context, another philosopher and educationist, Paulo Freire, has considered an alternative education paradigm. The search for a new philosophy of education for Africa is tributary to the comparative study of these two contemporary scholars.
5

Variable-property flow and heat transfer to single spheres in high temperature surroundings

Sayegh, Namir Najib January 1977 (has links)
No description available.
6

Influenza virus shedding and transmission in households

Lau, Lee-hang, Lincoln, 劉力恆 January 2012 (has links)
Background The dynamics of influenza virus transmission are not yet fully understood, hindering the appropriate development and implementation of control and mitigation strategies. One major uncertainty relates to the profile of infectiousness over time in humans infected by influenza virus, and how variation in infectiousness might contribute to the risk of transmission in households. Methods In 2008 and 2009, two large community-based studies were conducted to study the household transmission of influenza viruses in Hong Kong. I analyzed data on viral shedding and disease in participants, and used statistical models to examine how viral shedding patterns and other factors might affect the risk of influenza virus transmission in households, both within individuals over time, and between individuals with different patterns in viral shedding. Results The patterns of viral shedding relative to the time of illness (acute respiratory illness; ARI) onset in naturally acquired infections were found to be largely comparable to the patterns observed in experimental infections. Viral shedding detected by RT-PCR peaks around the day of ARI onset after which levels of shedding declined over around 7 days, and viral shedding tended to be greater in children than adults. The patterns of viral shedding in cases of seasonal A subtypes were similar, although the trends of shedding in cases of seasonal B differed with some indication of a plateau in shedding for up to 5 days after illness onset. The risk of household influenza transmission was significantly associated with log10 viral shedding, though not with influenza related signs and symptoms such as cough. Conclusions The patterns of viral shedding observed in naturally-acquired influenza A virus infections correlated with the pattern of infectiousness over time after onset of illness. The majority of infectiousness was estimated to occur within 2-3 days of illness onset, with implications for isolation strategies. The heterogeneous nature of individual viral shedding suggests the possibility of substantial variation in infectiousness, particularly among children. / published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy
7

Epidemiology of intestinal parasites in relation to HIV infection in Western Kenya with special reference to Cryptosporidium

Gatei, Wangeci January 2002 (has links)
No description available.
8

Signal transduction in neural systems: role of excitability

王宇靑, Wang, Yuqing. January 2000 (has links)
published_or_final_version / Physics / Doctoral / Doctor of Philosophy
9

The dynamics of packed beds with intraphase heat transfer

Jeffreson, Carl Patrick January 1971 (has links)
1 v. (various pagings) : ill. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1972
10

Retrofitting of angle legs of transmission towers to increase load capacity

Tongkasame, Chirawat January 2008 (has links)
The ability of a retrofitting method that bolted additional angle members in parallel to existing transmission tower legs to increase their load capacity was examined, using both experimental work and complex finite element modelling. New design models and parameters were developed in order to easily achieve the target capacity increase.

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