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All Mobile Network Operators (MNOs) as well as international carriers are moving voice services from the legacy Public Switched Telephone Network (PSTN) to Voice over IP (VoIP). The benefit is that VoIP traffic can be easily rerouted at any moment, thus giving companies a variety of options as traffic can be rerouted to any carrier of choice leading to different Quality of Service (QoS) levels (and thus agreements) as well as different prices to choose from. With a fierce competition for the telecom companies involved in the voice traffic hubbing business, this new landscape offers not only opportunities but also opens the system to vulnerabilities. The stakes are actually quite high: If harm can be done to one of these international carriers, other companies will route away their traffic. The result will be significant financial damages for the company as well as a serious harm to its reputation. The aim of this paper is to raise awareness that internationalcarriers and in particular their VoIP traffic can be exposed to debilitating attacks to harm these systems that are critical for our everyday life. The experimentation in this project demonstrates with a hands-on example how a major carrier can be hacked and rendered useless. In particular, we craft a framework for testing the security of interconnects between MNOs and international carriers. The central point of the paper will be to demonstrate how easy it can be to attack major carriers in the market: using common open source tools without having any information in advance. Moreover, the goal is to understand how the market functions, how interconnects between companies are built, where the weaknesses are, and which solutions can thwart those threats and secure these systems.

This research explores the feasibility of providing innovative and effective solutions for traffic congestion. The design of reservation systems is being considered as an alternative and/or complementary travel demand management (TDM) strategy. A reservation indicates that a user will follow a booking procedure defined by the reservation system before traveling so as to obtain the right to access a facility or resource. In this research, the reservation system is introduced for a cordon-based downtown road network, hereafter called the Downtown Space Reservation System (DSRS). The research is executed in three steps. In the first step, the DSRS is developed using classic optimization techniques in conjunction with an artificial intelligence technology. The development of this system is the foundation of the entire research, and the second and third steps build upon it. In the second step, traffic simulation models are executed so as to assess the impact of the DSRS on a hypothetical transportation road network. A simulation model provides various transportation measures and helps the decision maker analyze the system from a transportation perspective. In this step, multiple simulation runs (demand scenarios) are conducted and performance insights are generated. However, additional performance measurement and system design issues need to be addressed beyond the simulation paradigm. First, it is not the absolute representation of performance that matters, but the concept of relative performance that is important. Moreover, a simulation does not directly demonstrate how key performance measures interact with each other, which is critical when trying to understand a system structure. To address these issues, in the third step, a comprehensive performance measurement framework has been applied. An analytical technique for measuring the relative efficiency of organizational units, or in this case, demand scenarios called network Data Envelopment Analysis (DEA), is used. The network model combines the perspectives of the transportation service provider, the user and the community, who are the major stakeholders in the transportation system. This framework enables the decision maker to gain an in-depth appreciation of the system design and performance measurement issues. / Ph. D.

Passage of Clean Air Act Amendments of 1990 have placed greater responsibility on transportation planners, requiring greater integration of transportation and air quality planning processes. Inclusion of Travel Demand Management (TDM) measures into a State Implementation Plan (SIP) or a Transportation Improvement Program (TIP) requires the evaluation of these measures for emission impacts. Traditional method of analysis of a TDM measure using TDM software is labor intensive and time consuming. This process involves the execution of the four step travel demand forecasting models for each emission analysis. This could delay the process of approving a transportation program to be included in the State Implementation Plan. To simplify the process of emission impact analysis of TDMs using TDM software, a link between TDM software and MOBILE5a was developed. In developing the linkage, three parameters were considered crucial. These three parameters were the VMT mix, speed, and operating mode mix. It was determined that the changes in the values of these parameters would have substantial impact on emission factors. Methodologies were formulated to predict the changes in the values of these parameters due to the implementation of TDM measures. To predict the changes in the VMT mix factors, vehicle composition rates were developed by analyzing the 1990 National Personal Transportation Survey (NPTS). Changes in speed and operating mode mix were estimated using the methodologies developed by Sierra Research, Inc. A software model called TDMLinK was developed to link the TDM software and MOBILE5a. The three methodologies developed to predict the changes in the value of parameters were incorporated into this software. TDMLinK reports the percent reductions of emissions for each TDM scenario modeled and for each pollutant. This software extends the ability of TDM software to do screening analysis of TDM strategies. / Master of Science

Made available in DSpace on 2016-03-15T19:38:10Z (GMT). No. of bitstreams: 1 Mauricio Moderno de Carvalho.pdf: 2212181 bytes, checksum: 274e2da279304668d738afe9e3483c45 (MD5) Previous issue date: 2008-08-06 / Fundo Mackenzie de Pesquisa / By adopting a ring topology and optical switches we propose a novel protection mechanism for time division multiplexed passive optical network (TDM-PON) that provides resilience against multiple network fails. Some protection schemes have been proposed in order to give resilience for passive optical network (PON) as defined at ITU-T Recommendation G983.1. However that recommendation defines the optical distribution network (ODN) and equipment duplication to protect it against multiple points of fail. We propose a ring topology with dual fibers paths capable to protect the network by switching these lines individually according to the local alarms detected by each optical network unit (ONU). According to our proposal neither equipment nor network should be duplicated to provide survivability to the system. / Adotando uma topologia em anel e chaves ópticas, estamos propondo um novo mecanismo de proteção para redes ópticas passivas TDM (Time Division Multiplexed) que possibilita a proteção da rede contra múltiplos pontos de falha. Muitos esquemas de proteção foram propostos para dar confiabilidade para as redes ópticas passivas como definido pela recomendação ITUT G.983.1. Para permitir proteção contra múltiplos pontos de falhas a recomendação ITU-T define a duplicação da rede óptica (ODN) e equipamento. Apresentamos, então, uma topologia em anel com dois caminhos ópticos distintos protegendo a rede pela comutação individual destas linhas de acordo com a detecção de alarmes locais por cada Optical Network Unit (ONU). Conforme nossa proposta, nem o equipamento ou a rede precisam ser duplicadas para prover proteção do sistema.

[pt] Este trabalho apresenta um sistema de interrogação de sensores a rede de Bragg em fibras ópticas, baseado em reflectometria no domínio do tempo e filtros fixos a rede de Bragg. Utilizando uma fonte de luz pulsada, a posição espectral do sensor é relacionada à razão da intensidade dos pulsos, tornando a detecção independente de variações de intensidade. São abordados aspectos teóricos e experimentais referentes aos princípios de funcionamento desta técnica. Uma vez que a filtragem é feita com redes de Bragg, apenas um circuito de fotodetecção é utilizado e um número reduzido de acopladores/circuladores ópticos é necessário, o sistema possibilita reduzir consideravelmente o custo para a interrogação de um conjunto de sensores. A utilização de apenas um circuito de fotodetecção apresenta a vantagem de manter as mesmas características para todos os pulsos, minimizando influências externas neste circuito como, por exemplo, variações da temperatura ambiente. Foi montada uma bancada de testes para a interrogação de seis sensores. Comparações entre os resultados experimentais e simulados mostram boa concordância. Extrapolações indicam que seria possível interrogar sensores com uma variação espectral de 2 nanômetros, com incertezas menores que 10 picometros, o que é adequado para sensores de temperatura. Análises de interferência entre dois canais adjacentes mostram pouca influência entre eles e são apresentadas opções para diminuir essa interferência. / [en] This work presents a system for the interrogation of fiber- optic Bragg grating sensors based on time domain reflectometry and Bragg grating fixed filters. Using a pulsed light source, the spectral position of the sensor is related to the ratio of two pulses intensities, making detection independent of intensity variations. Theoretical and experimental aspects regarding the working principles of this technique are discussed. Since filtering is accomplished with Bragg grating so that only one photodetection circuit is used and a reduced number of optic couplers/circulators are needed, the system provides a considerable reduction in the cost of interrogation for a set of sensors. Using only one photodetection circuit also has the advantage of maintaining the same characteristics for all pulses, thus minimizing external influences in this circuit, such as variations in the environment temperature. A test stand was assembled for the interrogation of six sensors. Comparisons between experimental and simulated results show a good agreement. Extrapolations indicate that it would be possible to interrogate sensors with a spectral variation of 2 nanometers, with uncertainties lower than 10 pm, which is adequate for temperature sensors. Cross talk analyses between two adjacent channels show small influence between them, and approaches to reduce this interference are presented.

La recherche en imagerie moléculaire repose beaucoup sur les performances en tomographie d'émission par positrons (TEP). Les avancées technologiques en électronique ont permis d'améliorer la qualité de l'image fournie par les scanners TEP et d'en augmenter le champ d'application. Le scanner LabPET II, en développement à l'Université de Sherbrooke, permettra d'atteindre des résolutions spatiales inégalées.La conception de ce scanner requiert une très grande densité de détecteurs de l'ordre de 39 000 sur un anneau de 15 cm de diamètre par 12 cm de longueur axiale. D'autre part, l'Université de Sherbrooke mène également des travaux en tomodensitométrie (TDM) par comptage de photons individuels. Ces travaux s'insèrent dans un programme de recherche menant à réduire par un facteur 1,5 à 10 la dose de rayon X par rapport aux doses actuelles en TDM. Un circuit intégré (ASIC) a été développé pour supporter les performances attendues en TEP et en TDM. Cependant, la très grande densité de canaux rend inadéquate la vérification externe, sur circuits imprimés (PCB), des fonctionnalités des 64 canaux d'acquisition du circuit intégré actuellement en conception. Ainsi, un générateur de charge électronique a été conçu et intégré dans l'ASIC afin de pouvoir vérifier directement sur le circuit intégré ( On-Chip ) le fonctionnement de la chaine d'acquisition. Il permettra aussi de faire les tests pour le calcul de la résolution d'énergie et de la résolution en temps intrinsèque. La communication des données avec l'ASIC se fait par une ligne différentielle afin de maximiser l'immunité des signaux contre le bruit et d'assurer la vitesse de communication voulue.La norme Low-Voltage Differential Signaling (LVDS) a été choisie pour ce type de communication. En effet, trois récepteurs LVDS, basse consommation, ont été conçus et intégrés dans l'ASIC afin de recevoir les commandes de fonctionnement de l'ASIC à partir d'une matrice de portes programmables Field-Programmable Gate Array (FPGA) et de communiquer le signal d'horloge aux différents blocs. Pour augmenter la fiabilité du traitement effectué par l'électronique frontale, une mesure en température de l'ASIC est nécessaire. Un capteur de température basé sur la boucle à délais Delay-Locked Loop (DLL) a été conçu et intégré. En effet, la mesure de la température de l'ASIC permet d'intervenir en réalisant une compensation sur les mesures et en contrôlant le système de refroidissement en cas de sur-échauffement.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Current ground-based tracking systems at the DoD test and training ranges require transmission of a variety of signals from rotating platform to fixed control and process center. Implementation of commercial off the shelf (COTS) solution for transmitting high-speed, multiple-channel data signals over a rotational platform prompt the development of an advanced electro-optic hybrid rotating-to-fixed information transmission technology. Based on current demand, an Air Force-sponsored Small Business Innovative Research (SBIR) contract has been awarded to Physical Optics Corporation (POC) to modify existing tracking mounts with a unique electro-optic hybrid rotary joint (EOHRJ). The EOHRJ under current development is expected to provide the following features: 1) include a specially designed electrical slip-ring, which is able to accommodate hundreds of transmission channels, including electrical power, control, feedback, and low-speed data signals; 2) include an optical fiber slip-ring which, by incorporating with electrical time division mulitplexing (TDM) and optical wavelength division multiplexing (WDM) technologies, is able to provide multiple channel, high data rate (over gigabits per second), and bi-directional signal transmission; and 3) is designed to be reliable for harsh environmental operation, adaptive to stringent size requirement, and accommodating to existing electrical and mechanical interfaces. Besides the military use, other possible commercial applications include on board monitoring of satellite spinners, surveillance systems, instrumentation and multi spectral vision systems, emergency/medical instruments, remote sensing, and robotics.

Ce travail réalisé au sein du Service d'Exploration Fonctionnelle Respiratoire (Hôpital de la Croix-Rousse) évalue la prise en charge de patients souffrant de broncho-pneumopathie obstructive chronique (BPCO) dans le cadre d'une réadaptation fonctionnelle.<br />Nous avons évalué d'abord les effets d'un programme de réhabilitation réalisé sur 80 patients (VEMS à 46%) pendant 14 semaines dans le Service en ambulatoire à raison de 3 fois par semaine. Le bénéfice est significatif sur le test de marche, le questionnaire de qualité de vie et l'index de BODE. <br />Pendant ce programme, nous avons également évalué sur 30 patients les effets d'un entraînement spécifique des muscles ventilatoires avec augmentation significative de la pression maximale inspiratoire à l'issue de ces séances.<br />Un groupe plus restreint de patients (12 patients :VEMS à 34 %) a bénéficié pendant le réentraînement de l'apport d'une ventilation non invasive (VNI) afin de leur permettre d'accomplir la totalité du programme de réentraînement. <br />La suite de la réhabilitation à domicile est également très importante. Notre dernière étude a évalué les effets d'un programme de réhabilitation à domicile sur une période de 1 à 5 ans avec poursuite de l'amélioration des acquis du réentraînement effectué au préalable dans le Service EFR.

Afin d'étudier le fonctionnement des organes, les chercheurs utilisent l'imagerie médicale pour faire des observations d'une façon non invasive. Parmi les techniques d'imagerie les plus utilisées, on cite la tomographie d'émission par positrons (TEP) qui permet d'obtenir des informations fonctionnelles et métaboliques et la tomodensitométrie (TDM) qui fournit des informations sur l'anatomie. Le LabPET II est un scanner bimodal combinant les techniques TEP et TDM. Il est développé par le Centre d'Imagerie Moléculaire de Sherbrooke (CIMS) et le Groupe de Recherche en Appareillage Médical de Sherbrooke (GRAMS), et dispose de plusieurs fonctionnalités innovantes qui le rendent unique dans sa résolution spatiale et sa qualité d'image. Il est également le premier scanner à intégrer totalement les modes TEP et TDM sur les mêmes détecteurs et dans un même système électronique. Ceci se fait grâce à un module détecteur composé d'une matrice de 64 cristaux scintillateurs couplés à 64 photodiodes à avalanche. L'acquisition des signaux se fait par un circuit intégré dédié composé de 64 canaux d'acquisition analogiques et d'un processeur numérique pour le traitement des données. Les travaux de ce projet ont pour but de réviser le circuit intégré à application spécifique (ASIC) incluant la chaîne d'acquisition et de stabiliser son fonctionnement, afin d'améliorer les performances du scanner dans les deux modes TEP et TDM. Ceci a été effectué à travers la conception de nouveaux circuits analogiques et la modification des circuits actuels. Des interventions ont été faites sur différents composants de l'ASIC. Au niveau du canal analogique, des modifications ont été apportées sur les sous-circuits, d'une part pour améliorer le taux de réjection de l'alimentation et ainsi baisser le niveau de bruit, et d'autre part pour augmenter les marges de stabilité et éliminer le risque d'oscillation à gain élevé. Au niveau des circuits auxiliaires de l'ASIC, le circuit de transmission différetielle basse-tension (LVDS) a été révisé pour corriger des défaillances constatées sur les versions précédentes et de nouvelles références de tension ont été conçues pour remplacer les sources précédentes qui souffraient d'instabilités face aux variations de la température et des paramètres du processus de fabrication. Ces travaux ont d'abord été validés par une série de simulations, puis un premier circuit intégré comportant une partie des modifications a été fabriqué avec la technologie CMOS 0,18 µm de la Taiwan Semiconductor Manufacturing Company (TSMC). Ceci a permis de valider un premier lot de révisions et de faire des tests poussés avant de procéder à la mise à jour finale de l'ASIC. Une fois fonctionnel, ce circuit pourra fonctionner d'une façon stable dans les deux modes d'imagerie TEP et TDM et permettra ainsi de réaliser un premier prototype d'un scanner bimodal totalement intégré.