- 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.
Search results
Showing 1 to 4 of 4 (0.018 seconds)Spelling suggestions: "subject:"hayan"" "subject:"mayan""
| 1 |
A Framework to Simulate and Improve Terahertz Quantum Well PhotodetectorsFerre, Simon 13 August 2013 (has links)
A wide range of applications have been recognized for terahertz radiations. In fact, medical imaging, homeland security screening, very high-speed wireless telecommunications systems and even drug and gas detection are boosting the development of terahertz emitters and receivers. The work of this thesis is among the efforts in that regard.
Actual terahertz detectors are suffering many drawbacks, they are bulky, very slow, not very sensitive or operates at non-practical temperatures. Combined with the complexity to realize terahertz emitters, it explains the difficulties of terahertz radiations to ensure market penetration with practicable civil applications. In that regard, we aim to better understand and improve a specific terahertz photodetector: the Terahertz Quantum Well Photodetector. Those devices working principle relies on a photocurrent created by the excitation of electrons from ground states of quantum wells to the continuum under terahertz impinging light. The intensity of the photocurrent is depending on the intensity of the radiation received by the device.
The device active region is made of a multiple quantum wells GaAs/AlGaAs system. By changing the design of the device, that is the thicknesses of each layer, the aluminum fraction of the doping concentration, we can modify its performances. Documented and commented Matlab functions and routines have been implemented in order to simulate a given structure and scripts have been written to find the optimum parameters for a target absorption frequency. Our model has been verified by comparison with experimental data reported in the literature.
Based on our model, we systematically study the impact of the active region and contact parameters on the device performances. In addition, innovative designs are proposed in order to reduce the undesirable dark current and thus increase the detectivity. They benefits from many-body effects, effects that are usually a constraint on the design. To our knowledge this is the first time those effects are used to realize innovative designs and increase the performances of quantum well infrared photodetectors.
Finally we expose other designs that have been tested in the infrared domain with QWIP and adapt them to the terahertz range. In particular, we propose a quantum cascade photodetector, a double barrier bound-to-miniband and a phonon-assisted band to miniband structures.
|
| 2 |
A Framework to Simulate and Improve Terahertz Quantum Well PhotodetectorsFerre, Simon 13 August 2013 (has links)
A wide range of applications have been recognized for terahertz radiations. In fact, medical imaging, homeland security screening, very high-speed wireless telecommunications systems and even drug and gas detection are boosting the development of terahertz emitters and receivers. The work of this thesis is among the efforts in that regard.
Actual terahertz detectors are suffering many drawbacks, they are bulky, very slow, not very sensitive or operates at non-practical temperatures. Combined with the complexity to realize terahertz emitters, it explains the difficulties of terahertz radiations to ensure market penetration with practicable civil applications. In that regard, we aim to better understand and improve a specific terahertz photodetector: the Terahertz Quantum Well Photodetector. Those devices working principle relies on a photocurrent created by the excitation of electrons from ground states of quantum wells to the continuum under terahertz impinging light. The intensity of the photocurrent is depending on the intensity of the radiation received by the device.
The device active region is made of a multiple quantum wells GaAs/AlGaAs system. By changing the design of the device, that is the thicknesses of each layer, the aluminum fraction of the doping concentration, we can modify its performances. Documented and commented Matlab functions and routines have been implemented in order to simulate a given structure and scripts have been written to find the optimum parameters for a target absorption frequency. Our model has been verified by comparison with experimental data reported in the literature.
Based on our model, we systematically study the impact of the active region and contact parameters on the device performances. In addition, innovative designs are proposed in order to reduce the undesirable dark current and thus increase the detectivity. They benefits from many-body effects, effects that are usually a constraint on the design. To our knowledge this is the first time those effects are used to realize innovative designs and increase the performances of quantum well infrared photodetectors.
Finally we expose other designs that have been tested in the infrared domain with QWIP and adapt them to the terahertz range. In particular, we propose a quantum cascade photodetector, a double barrier bound-to-miniband and a phonon-assisted band to miniband structures.
|
| 3 |
L'influence de la situation géopolitique au Moyen-Orient sur la génération des accords israélo-arabes depuis Camp David I : La frontière d'IsraëlHirtzlin-Pinçon, Olivier 19 June 2008 (has links) (PDF)
La question moyenne-orientale est dans l'actualité depuis 1948. C'est en cette année que se crée l'Etat d'Israël sur les décombres du mandat britannique en Palestine. Dès le commencement, la guerre va commencer à fixer les frontières entre Israël et ses voisins arabes. Cependant, après 1967, une nouvelle question va apparaître, celle des relations avec les Territoires occupés. En conséquence, l'Etat d'Israël aura deux questions frontalières à gérer : la question interétatique classique et la question interne avec les Palestiniens. Cette recherche tente de démontrer les voies employées par les différents acteurs régionaux et internationaux pour trouver une solution à cette question juridique qui cause l'instabilité régionale. On s'appuiera sur le droit, l'Histoire, la science politique (en particulier, l'étude des idéologies sioniste et arabiste) et les relations internationales pour trouver une cohérence aux réussites et aux échecs qui ont émaillé l'histoire du Moyen-Orient depuis 1948 et le fait qu'Israël n'ait encore que deux frontières internationalement reconnues, une avec l'Egypte et l'autre avec le royaume de Jordanie.
|
| 4 |
Sovereignty, Peacekeeping, and the United Nations Emergency Force (UNEF), Suez 1956-1967: Insiders’ PerspectivesHilmy, Hanny 13 February 2015 (has links)
This research is concerned with the complex and contested relationship between the sovereign prerogatives of states and the international imperative of defusing world conflicts. Due to its historical setting following World War Two, the national vs. international staking of claims was framed within the escalating imperial-nationalist confrontation and the impending “end of empire”, both of which were significantly influenced by the role Israel played in this saga. The research looks at the issue of “decolonization” and the anti-colonial struggle waged under the leadership of Egypt’s President Nasser. The Suez War is analyzed as the historical event that signaled the beginning of the final chapter in the domination of the European empires in the Middle East (sub-Saharan decolonization followed beginning in the early 1960s), and the emergence of the United States as the new major Western power in the Middle East.
The Suez experience highlighted a stubborn contest between the defenders of the concept of “sovereign consent” and the advocates of “International intervention”. Both the deployment of the United Nations Emergency Force (UNEF) and its termination were surrounded by controversy and legal-political wrangling. The role of UNEF and UN peacekeeping operations in general framed the development of a new concept for an emerging international human rights law and crisis management. The UNEF experience, moreover, brought into sharp relief the need for a conflict resolution component for any peace operation. International conflict management, and human rights protection are both subject to an increasing interventionist international legal regime. Consequently, the traditional concept of “sovereignty” is facing increasing challenge.
By its very nature, the subject matter of this multi-dimensional research involves historical, political and international legal aspects shaping the research’s content and conclusions. The research utilizes the experience and contributions of several key participants in this pioneering peacekeeping experience. In the last chapter, recommendations are made –based on all the elements covered in the research- to suggest contributions to the evolving UN ground rules for international crisis intervention and management. / Graduate / hilmyh@uvic.ca
|
Page generated in 0.0259 seconds