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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

Diagnostic des défauts de réseaux électriques filaires par la réflectométrie / Fault diagnosis of wired electric networks by reflectometry

Oumri, Mohamed 16 May 2014 (has links)
Cette thèse s’intéresse au diagnostic de défauts de réseaux électriques filaires à l'aide de la réflectométrie. Pour concevoir des algorithmes de diagnostic, nous avons étudié le problème direct (simulations numériques des réseaux électriques) et le problème inverse (détermination de certaines propriétés d’un réseau à partir des mesures de réflectométrie). Concernant le problème direct, nous avons développé une méthode de calcul du coefficient de réflexion d’un réseau sous forme d’arbre qui est basée sur la résolution successive d’équations différentielles de Riccati. Nous avons également généralisé l’équation de BLT pour des réseaux électriques composés de branches non uniformes et automatisé la méthode de sa résolution. La thèse a apporté deux nouveaux résultats concernant le problème inverse. Le premier résultat porte sur l’estimation des longueurs et des coefficients de pertes des branches d'un réseau électrique sous forme d’étoiles via une méthode itérative. Le deuxième porte sur l’identification, au moins partiellement, des matrices d’admittance des branches d’un réseau électrique modélisé par l’équation de BLT. Les méthodologies et les formalismes proposés dans la thèse sont validés soit par des simulations numériques, soit par des mesures réelles. / This thesis focuses on fault diagnosis of wired electric networks using reflectometry. To develop diagnostic algorithms, we studied the direct problem (numerical simulations of electrical networks) and the inverse problem (determination of certain properties of a network from reflectometry measurements). For the direct problem, we developed a method for the computation of reflection coefficients. This method is based on the successive solving for a Riccati differential equation. We also generalized the BLT equation for the nonuniform electric networks and automated the resolution of this method. The thesis has made two new results concerning the inverse problem. The first result concerns the estimation of lengths and loss coefficients of the branches of a star network via an iterative method. The second focuses on the identification, at least partially, of the branches admittance matrices of a electric network modeled by the equation of BLT. The methodologies and formalisms proposed in this thesis are validated either by numerical simulations or by real measurements.
2

Impact Evaluation of Intentional Electromagnetic Interference (IEMI) on Targeted Loads in Complex Networks Using Analytical Investigations

Li, Bing January 2017 (has links)
With the proliferation of various electronic and electrical devices, IEMI has become a critical issue that may severely threaten the modern society. For practical protection considerations, it is crucial to comprehensively evaluate the potential damages resulted by IEMI. The major objective of this thesis is to study the impacts of IEMI on the targeted load in complex networks. More exactly, with respect to certain IEMI, the characteristics of the resulting frequency response on the targeted load are studied, and the effects of network configurations, i.e., the attribute of load impedances, lengths of lines, parameters of disturbance source, location of source and network structures, are also investigated. First, we developed a novel efficient method to solve the frequency response, which is applicable for arbitrary networks. The key idea is decomposing the whole complex network into multiple equivalent units, and performing a recursive approach to efficiently compute the frequency response without losing the precision. Subsequently, we studied the periodicity of the load response in the frequency domain. Starting with a simple network, we derived and verified the period of the frequency response. During the study, the periodicity with respect to load and media was discussed. Furthermore, with respect to five important time-domain norms, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change, and peak time integral of the pulse, we considered a parameterized ultra-wideband (UWB) transient as the disturbance source, and thoroughly studied its impacts on the targeted load regarding network configurations, which include load impedance, the lengths of lines and parameters of the UWB transient. Finally, we adopted a statistical approach to investigate the receptivity at the targeted load in a network. Via complementary cumulative distribution function, the stochastic IEMI and its effects on the targeted load were studied. Moreover, by statistical approach, we also investigated how the network structure affects the frequency response of the targeted load. The results give suggestions on how to protect the targeted load by varying network structures. / <p>QC 20170922</p>
3

Assessment Of Shielding Effectiveness By Using Electromagnetic Topology Method

Yaslak, Halil Ibrahim 01 February 2013 (has links) (PDF)
In this thesis, determination of the shielding effectiveness of a rectangular shielding box with apertures on its walls by using electromagnetic topology (EMT) technique based on Baum-Liu-Tesche (BLT) equation is presented. The presented technique is applied to determine the field penetration into various rectangular shielding boxes with different sizes and aperture dimensions. An HP branded computer case is also analysed as a rectangular shielding box with a CD driver slot as an aperture. Results on electromagnetic field penetration through the apertures into the boxes at different frequencies are obtained by using the presented method and compared with the results obtained by using CST MICROWAVE STUDIO&reg / software simulation.
4

Utilizing Humanized Mice to Study Human Specific Innate Immune Responses in Immuno-Oncology

Aryee, Ken-Edwin 16 July 2019 (has links)
The kinetics of tumor growth and progression are governed by the interaction between tumor cells, the non-malignant stroma and both innate and adaptive immune cell lineages. Innate immunity has a critical role in the control of tumor cell growth and metastasis. The microenvironment of many tumors is populated with innate immune cells, including regulatory natural killer (NK) cells and dendritic cells (DCs), tumor associated macrophages, and myeloid derived suppressor cells, that suppress normal immune function. Much of our understanding of interactions between tumors and the innate immune system is based on experimental studies performed in mouse “syngenic” models. However, there is clear need for a mechanistic understanding of the human innate immune system within the tumor microenvironment. The goal of my thesis is to characterize the interactions between human innate immune cells and tumors and to define specific pathways and cell lineages that are targets for immune modulation. A central focus of my thesis is the use of cutting-edge humanized mouse models based on the immunodeficient NOD-scid IL2Rgnull (NSG) mouse strain to study human immuno-oncology. In the first section of my thesis I describe studies that evaluate the influence of inflammatory stimuli on innate immune control of tumors. Agents that induce inflammation have been used since the 18th century for the treatment of cancer. The inflammation induced by agents such as toll-like receptor (TLR) agonists is thought to stimulate tumor-specific immunity in patients and augment control of tumor burden. While NSG mice lack murine adaptive immunity (T and B cells), these mice maintain a residual murine innate immune system that responds to TLR agonists. Here I describe a novel NSG mouse strain lacking TLR4 that fails to respond to lipopolysaccharide (LPS). NSG-Tlr4null mice support human immune system engraftment and enables the study of human specific responses to TLR4 agonists. My data demonstrate that specific stimulation of TLR4 activates human innate immune system and promotes regression of human patient derived xenograft (PDX) tumors. In the second section of my thesis I describe the development of an NSG mouse strain that constitutively expresses human Interleukin 15 (IL15) and supports the development of functional human NK cells. Using humanized NSG-IL15 transgenic mice (NSG-Tg(Hu-IL15), my data clearly demonstrate a critical role for human NK cells in limiting growth of a PDX melanoma. In the third section of my thesis I describe, the use of the bone marrow/liver/thymus (BLT) humanized mouse model to study the interactions between the human immune system and PDX melanoma and to evaluate the response of the melanoma to immunotherapy modalities. My results collectively suggest that mice engrafted with human immune systems and bearing human tumors can be harnessed as translational models, which are critically needed as tools to study tumor immunotherapy. These humanized mouse models are an ideal translational tool to advance our understanding of human immuno-oncology and for development and testing of novel immune therapies for the treatment of malignancies.
5

Sea TENTACLE: Track, Engage, & Neutralize Threats - Asymmetric & Conventional - in the Littoral Environment

Black, Brian C., Bollock, Laura H., Bouabid, Sinene, Glova, Michael A., Hall, Jason A., Harden, Glynn M., Hickle, Curtis J., Hosoglu, Selcuk, Majewicz, Peter, Mullenix, Kenneth R., Nozik, Andrew B., Sarar, Stephen F., Ucar, Hakan 01 1900 (has links)
Includes supplementary material. / Sea TENTACLE is a proposed afloat platform whose primary mission is to utilize the state-of-the-art technology of unmanned vehicles to monitor and neutralize all subsurface enemy threats in the littorals. This mission can be specified further as anti-submarine warfare, mine warfare and maritime surveillance. The design philosophy of Sea TENTACLE embodies the ideal of providing a multi-mission capable sea frame extending network-centric warfare into the littorals. The design goals of the TSSE team were first to develop a platform to deploy, recover, and maintain unmanned vehicle (e.g. UUVs, USVs, UAVs) and second to enableto ship to act as an afloat network operations center for distributed assets. Allowing all units to work together seamlessly to conduct focused missions in the littorals makes the Sea TENTACLE a creitical component within the network-centric environment. The versatility of its cargo hold and modular design allows Sea TENTACLE to be outfitted dynamically to complete a veriety of secondary missions including humanitarian aid, salvage and spacial operations support. Sea TENTACLE's combat management and operations system will employ the Enterprise architecture design enabling C4ISR capabilities that will meet emerging network centric warfare needs.
6

Winter Blues is Old News : Creating the conditions to recognize our dependency on natural light cycles and prevent Seasonal Affective Disorder (SAD)

Thomas Langer, Mariano January 2023 (has links)
The short dark days of winter, related lack of energy, and low mood have always been part of life for those living in northern latitudes. For many, the gradual changes of the seasons are accompanied by the gradual degradation of their mental health. This disruptive effect is called Seasonal Affective Disorder (SAD). It is defined as major depressive episodes characterized by their seasonal recurrence for at least 2 consecutive years. Symptoms generally involve fatigue and a severe lack of energy leading to difficulty in performing daily activities as well as increased worry, anxiety, and irritability. Product Design in the field of SAD is positioned primarily in the treatment phase. Bright Light Therapy (BLT) products are used to attempt to alleviate the symptoms of the disorder. Efforts should focus on the prevention of mental illness to have a holistic impact on sustainable development. This project aims to identify an innovation opportunity where Product Design can be leveraged to prevent SAD. By leveraging semiotics, the study of signs and how meanings are created, in the field of lighting and design, a concept was developed that aims at complementing existing regulations in providing users with the conditions for improved well-being in the home. SAD is strongly linked to natural light and its cycles. Windows, the main provider of this kind of light in the home, have practical, comfort- and information-related roles. The developed concept aims at enhancing the meaning of windows to highlight our dependency on natural light cycles and prevent SAD. To effectively evaluate the concept and its effectiveness in creating meaning, it must be further developed and exposed to potential users.
7

La greffe de thymus humain lors de l'humanisation des souris NOD/SCID/IL2Rγcnull: optimisation du modèle pour l’étude de la fonction des lymphocytes T humains in vivo

Colas, Chloé 10 1900 (has links)
Aujourd'hui, l'un des modèles de souris humanisées le plus robuste est obtenu en injectant des cellules souches hématopoïétiques humaines (HSC) issues de foie fœtal humain et en implantant du thymus fœtal autologue. Ce modèle, appelé BLT (Bone marrow/Liver/Thymus), s'est révélé capable de supporter une reconstitution, une maturation et une sélection optimales des cellules T. Les souris BLT sont utilisées pour de nombreuses études telles que la compréhension de la biologie du VIH ou plus récemment en médecine régénérative. Grâce à ce modèle, nous avons pu d’une part étudier le rôle des cellules dendritiques plasmacytoïdes (pDC) lors de l’infection par le VIH mais aussi mieux comprendre la formation in vivo de tératomes lors de l’utilisation d’iPSC. Cependant, l'une des principales limites de cette technique réside dans l'obtention du tissu fœtal. Ici, nous avons décrit un nouveau protocole de souris humanisées greffées avec du thymus humain en utilisant des matériaux plus accessibles: du thymus humain retiré lors d’une chirurgie cardiaque chez des nouveaux-nés ou des enfants, et des HSC de sang de cordon. Des morceaux de ces thymus ont été implantés dans les quadriceps de souris immunodéficientes, après avoir été mis en culture. Ces souris CCST (Cord blood and Cardiac Surgery Thymus) ont permis une prise de greffe importante et un meilleur développement des lymphocytes T humains que les souris humanisées sans thymus. Les lymphocytes T des souris CCST et BLT ont montré une fonction similaire, évaluée par des tests de prolifération ex vivo et par rejet de lignées de cellules leucémiques allogéniques in vivo. Nous avons testé l’intérêt de cette nouvelle stratégie dans le modèle de l’infection au VIH-1, qui représente le modèle type de l’utilité des BLT. Nous avons montré que les souris CCST sont sensibles à l'infection par le VIH-1 par voie muqueuse ou intrapéritonéale, comme l'indique la détection de l'ADN du VIH et des cellules p24 +, similairement aux souris BLT. Les souris CCST ont présenté des réponses de lymphocytes T spécifiques du VIH-1 ex vivo plus efficaces que les BLT. Lors du traitement antirétroviral, les souris CCST, comme les BLT, ont vu leur charge virale diminuer. Ces résultats démontrent que les souris CCST représentent une alternative au modèle de souris BLT classique. Ces thymus, éthiquement plus facile à obtenir, peuvent être utilisés pour générer un grand nombre de souris par rapport aux thymus fœtaux. / Immunodeficient mice engrafted with human immune system provide an exciting in vivo model for a better understanding of its functioning and for development of new therapies. Today, one of the most robust humanized mouse model is achieved by injecting human hematopoietic stem cells (HSC) from fetal liver along with an implantation of autologous fetal thymic tissue. This model, called BLT, was shown to be able to support an optimal T cell reconstitution, maturation and selection. BLT mice are extensively used for many studies such as understanding HIV biology or in regenerative medicine. Indeed, our work used BLT mice on one hand to study the role of plasmacytoid dendritic cells (pDC) during the HIV infection and on the other hand to better understand the formation of teratomes from iPSCs in vivo. However, one of the biggest limitations of this technique is the procurement of the fetal tissue. Here we describe a new protocol to do humanized mice engrafted with human thymus pieces by using more accessible materials: human thymus obtained during cardiac surgery and cord blood HSC. Indeed, thymus is spontaneously removed during cardiac surgery in neonates and young children, thus it is an easy and ethical way to obtain this tissue. Those thymuses pieces were implanted in the quadriceps of a immunodeficient mice, after being put in culture. CCST mice (Cord blood and Cardiac Surgery Thymus) exhibited a significant engraftment of T-cells, compared to humanized mice without thymus. T-cells from both CCST and BLT mice showed a similar function as evaluated by proliferation assays upon PHA stimulation ex vivo and rejection of allogeneic leukemic cells lines in vivo. CCST mice were susceptible to HIV-1 infection via mucosal or intraperitoneal route, as shown by detectable viral load, HIV DNA and p24+ cells, at similar levels to those of BLT mice. Importantly, CCST mice displayed more effective ex vivo HIV-1-specific T-cell responses compared to BLT. Upon antiretroviral treatment, CCST mice, like BLT, were able to diminish the viral load. Our data suggest that CCST mice represent an alternative to the regular BLT mouse model. Those easy-to-access thymuses can be used to generate a large number of mice compared to fetal thymuses.

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