Cette thèse présente le développement d’implants en titane poreux sur mesure pour la chirurgie maxillo-faciale. Après avoir caractérisé mécaniquement le titane grade 2 obtenu par un procédé de fabrication additive, le Selective Laser Melting, nous avons réalisé des simulations éléments finis afin de développer un motif élémentaire aux propriétés mécaniques proches de celles de l’os. L’affaiblissement des propriétés initiales du titane permet d’éviter les phénomènes de résorption osseuse menant au descellement de prothèses par exemple. La structure développée garantit une ostéointégration optimale en permettant au tissu osseux de croître à l’intérieur des porosités.Pour accélérer l’intégration des implants dans l’os, nous avons développé un traitement de surface composé d’une immersion dans de l’hydroxyde de sodium et d’une anodisation. Ceci permet de créer une nouvelle couche d’oxyde, en surface du titane, avec laquelle l’os va pouvoir créer rapidement des liens chimiques forts.Enfin, un modèle numérique propre à un patient a été réalisé pour étudier l’influence d’implants crâniens en différents matériaux sur la distribution des températures au niveau de la tête. Il s’est avéré qu’un implant en titane poreux présente un comportement thermique proche de celui du tissu osseux, ce qui garantit la protection thermique du cerveau. Un modèle simplifié assimilant la tête à une sphère a été confronté au modèle précédent. Les résultats de ces deux modèles coïncident, il est donc suffisant de réaliser un modèle simple pour prédire la distribution de la température dans la tête. Ces travaux ont conduit à plusieurs implantations de substituts osseux en titane poreux. / This thesis deals with the development of patient specific porous titanium implants for maxillo-facial surgery. Once the mechanical properties of Selective Laser Melted commercially pure grade 2 titanium were characterized, finite elements simulations were carried out to create an elementary pattern with mechanical properties close to those of human bone.Weakening the initial properties of titanium enables to avoid the bone resorption phenomenon that frequently leads to prosthesis loosening. The ability of bone to grow into the porosities of the designed structure ensures optimal osseointegration of the implants.A new surface treatment composed of an immersion in sodium hydroxyde followed by an anodic oxydation was developed to improve the substitute integration to bone. This treatment enables to create a new oxyde layer on titanium with which bone will quickly create strong chemical links.We designed a patient specific numerical model in order to check the impact of cranial substitutes made of various materials on the modification of temperature fields in the head. Porous titanium implant and bone showed very similar thermal responses. Therefore, a porous titanium implant provides excellent thermal protection of brain. This model was set against a simplified one where the head was considered as a sphere. Since the results of these models were very similar, we concluded that the simplified modelling is appropriate to quickly predict temperature fields in the head with implant.So far, several porous bone substitutes based on the elementary pattern developed in this thesis were successfully implanted in humans

We consider the problem of electromagnetic propagation along a wire which passes through an aperture. We begin by formulating an integral equation in terms of the electric field at the aperture. The solution of the integral equation allows us to determine parameters of interest such as the equivalent admittance, the current on the wire, and the electric field. We solve the integral equation using both a zeroth order and method of moments approximation for the aperture field. From this we are able to compute the admittance and current in the frequency domain. We next calculate the current response to a transient pulse excitation. The results show that the screen provides little shielding from pulse penetration along the wire. Finally, we calculate solutions for the electric field. The results are given in several contour plots.

The problem of a wire penetrating a circular aperture in an infinite screen and coupling energy into a cavity behind that screen is considered. We formulate an integral equation in terms of the electric field in the aperture. This integral equation is solved using two approximate methods: a zeroth-order approximation valid at low frequencies, and the method of moments. In addition, we introduce an equivalent circuit model to aid in our physical interpretation of the problem. Numerical results for the interior current on the wire and for the equivalent circuit admittance parameters are presented in order to provide a comparison between the two approximations. Inside the cavity, we examine the components of the electric field as a function of position. Finally, the exterior magnetic field far from the aperture is studied as a function of frequency. We examine the relationship between interior resonance features associated with the presence of the cavity and observations of the exterior field.

A High electromagnetic shielding, light weight, low cost plastic package is developed by using a woven continuous carbon fiber (WCCF) epoxy composite. Three different weaving types of WCCF, plain¡Bbalanced twill and uni-direction structure, are fabricated for understanding the shielding property of the WCCF composites. By weaving the WCCF in a balanced twill structure with excellent conductive network, it shows that the SE can reach to about 80dB under plane-wave source measurement and about 50dB in the near-field source measurement. By comparison of cost, weight, and shielding performance for optical transceiver modules fabricated by the housings of woven continuous carbon fiber, nanoscale hollow carbon nanocapulses (HCNCs) epoxy composites and nylon and liquid crystal polymer (LCP) with carbon fiber filler composite, the WCCF composites shows lower cost, light weight, and higher electromagnetic shielding than the other types of composites.

Electromagnetic shielding materials for plastic packaging in laser modules application were studied experimentally. Bipheny1, Nylon and LCP mixed with Al-powder, Al-flake, carbon-fibers and steel-fibers was fabricated and measured in shielding effectiveness(SE) for EMI. Compression molding, double-screw extrusion and injection molding were used for fabrication. We examed the mechanical properties and shielding effectiveness of these compounds. The SE of conductive plastics was measured to be 40dB at 30MHz and 60dB at 1GHz for carbon-fiber and plastic mixture. The experiment result indicates that introducting conductive carbon fiber fillers into plastics will produce conductive composites having an excellent SE to reduce EMI. With these excellent SEs, such conductive carbon fiber fillers into plastics are suitable for use in low-cost laser modules.

Abstract The Nylon and liquid crystal polymer(LCP) filled with conductive carbon fiber applied to 155Mbps and 1.25Gbps transceiver modules for electromagnetic(EM) shielding were studied. The measured results showed that the shielding effectiveness(SE) of 155Mbps and 1.25Gbps transceiver module were 13dB and 20dB to conform to FCC class B standard, respectively. This indicates that the plastic housing filled with conductive carbon fiber is suitable for EM shielding in plastic laser transceiver module applications.

This research mainly focuses on the electromagnetic shielding effectiveness of bamboo -charcoal, using cement mortar with bamboo-charcoal ingredient replacing parts of thin aggregates weight, and then finds the feasibility of electromagnetic shielding effectiveness by using bamboo-charcoal applied to cement mortar. Experiment contains two parts, one is to use different proportions of bamboo-charcoal with replacing with thin aggregates weights( 0%¡B3%¡B5% and 7% ),and the other is to use three kinds of thickness(3mm¡B4mm and 5mm), to measure the effectiveness of electrom- agnetic shielding, and to probe into whether cement mortar with bamboo-charcoal ingredient can shield electromagnetic or not. After researching on cement mortar with bamboo-charcoal, it can be used in civil engineering and ocean engineering, and this experiment will act on the premise which is not affecting the property of cement mortar with bamboo-charcoal, continuing using the condition of reference(Yu,2007) to probe into the electromagnetic shielding effectiveness of cement mortar with bamboo-charcoal, expecting this material can be used to domestic architecture, for protecting the health of our home environment.

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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We investigate the EM properties of four different type composites which are nylon and liquid-crystal polymer with carbon fiber filler composites, woven continuous carbon fiber epoxy composites(balanced twill structure, plain weave structure, uni-direction weave structure), and liquid-crystal polymer with carbon nanotubes filler composites. By comparison of fabrication methods, cost and weight of the optical transceiver module housings, and shielding effectiveness under plane wave and near-field conditions, the woven continuous carbon fiber epoxy composites(balanced twill structure and plain weave structure) show lower cost, lighter weight, and higher EM shielding effectiveness than the other types of composites. Furthermore, they also perform good radiation susceptibility in our measurements. For these reasons, the proposed woven continuous carbon fiber epoxy composite package for an optical transceiver is suitable for use in a low-cost light wave transmission system.