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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.
421

Torus routing in the presence of multicasts

Ishibashi, Hiroki 01 January 1996 (has links)
No description available.
422

Crosstalk Cancellation in Structured Light Free Space Optical Communication

Briantcev, Dmitrii 04 1900 (has links)
Free-space optics (FSO) is an unlicensed communication technology that uses the free space as a propagation medium to connect two communicating terminal wire- lessly [1]. It is an attractive solution to the last-mile connectivity problems in commu- nication networks, mainly when installing optical fibers is expensive or unavailable. A possible idea to increase the throughput of wireless optical links in free space is to use spatial multiplexing (SMM) [2]. Optical beam distortion due to propagation through a turbulent channel is one of the main factors limiting performance of such a system. Therefore, overcoming the effect of turbulence is a major problem for structured light optical communication in free space. Usually, this problem is approached by using adaptive optics systems and various methods of digital signal processing (DSP) on the receiver side [3–5]. Recently, an idea of optical channel pre-compensation to mit- igate inter-modal crosstalk was proposed [6] and experimentally validated [7]. Such a method, if implemented, will allow the use of entirely passive receivers or, in the case of full-duplex transmission, increase throughput. Here, the performance of a zero-forcing precoding technique to mitigate the effects of an optical turbulence in a Laguerre Gaussian mode based SMM FSO is investigated. Equally, details on a close to reality simulation of the atmospheric turbulence and beam propagation are provided.
423

Širokopásmová FTTx přípojka na architektuře WDM - PON / Wide-band FTTx Networks Terminal in WDM - PON architecture

Bobkovič, Peter January 2010 (has links)
This masters thesis is focusing on the issue of passive optic access networks. It is dealing with the limiting factors for broadband connections, especially attenuation of fibre optics and dispersion. It is also dealing with most commonly used standards of passive optic networks. It clarifies the issue of wavelength-division multiplexing, its advantages and disadvantages, used standards, various types of components for the WDM-networks, their characteristics, application etc. In the practical part of the work you can find the measuring and diagnostics of the passive optic network EPON. It contains measuring by the direct method OLTS, measuring by the Pon Power Meter and optic reflectometer OTDR. At the end I am dealing with the measuring of splitter in the rate of 1:16.
424

Transfert d'énergie par résonance de type Förster pour les diagnostics multiplexés des récepteurs du facteur de croissance épidermique et microARNs / Time-Gated Förster Resonance Energy Transfer Biosensors for Multiplexed Diagnostics of Epidermal Growth Factor Receptors and MicroRNAs

Qiu, Xue 30 June 2016 (has links)
Les nouvelles exigences du diagnostic clinique et de la thérapeutique, particulièrement en termes d’examens au chevet du patient et en médecine de précision, ont conduit à une demande croissante d’analyses à la fois multiplexées et présentant un rendement important, et ce d’un grand nombre de biomolécules au sein d’un échantillon unique. La thèse se concentre sur le développement de biosenseurs multiplexés basés sur le transfert d’énergie par résonance de type Förster résolu en temps de complexes de lanthanide vers des colorants organiques ou des boîtes quantiques. Je présente plusieurs techniques novatrices permettant la détection simultanée et multiplexée de protéines biomarqueurs du cancer (récepteur du facteur de croissance épidermique) ou de microARNs (hsa-miR-20a-5p, hsa-miR-20b-5p et hsa-miR-21-5p) avec de très faibles limites de détection. J’ai utilisé différentes stratégies afin d’obtenir des détections multiplexées telles la détection multiplexée spectrale basée sur les différents spectres d’émission de différents luminophores, et la détection multiplexée temporelle basée sur les durées de vie distinctes des états excités des luminophores. Ces travaux ne sont pas seulement une recherche appliquée qui peut être utilisée en diagnostic clinique, mais constituent également une recherche fondamentale sur le FRET résolu en temps qui ouvre de nouvelles perspectives de détection et augmente considérablement le nombre de biomarqueurs pouvant être détectés. / The new mission of clinical diagnostics and therapeutics, especially in point-of-care testing and precision medicine, has led to an increasing demand for multiplex and high throughput analyses of large numbers of biomolecules within a single sample. The thesis focuses on developing multiplexed biosensors based on time-resolved Förster resonance energy transfer from lanthanide complexes to organic dyes or quantum dots. I present several new techniques to simultaneously and multiplexed detect cancer related protein biomarkers (human epidermal growth factor receptor) or microRNAs (hsa- miR-20a-5p, hsa-miR-20b-5p and hsa-miR-21-5p) with very low limits of detections. I have used different strategies to achieve multiplexed detections such as spectral multiplexed detection based on different emission spectra of different luminophores, and temporal multiplexed detection based on distinguishable excited-state lifetimes of luminophores. The work is not only an applied research that can be used in clinical diagnostics but also a fundamental research of time-resolved FRET, which opens a new dimension of detection and greatly increases the number of biomarkers that can be detected.
425

Study on Fault Detection andLocalization for Wave length Division Multiplexing Passive Optical Network

Poudel, Sunil January 2013 (has links)
Wavelength division multiplexing passive optical network (WDM-PON) can meet growing bandwidth demand in access network by providing high bandwidth to the end users. Failure in the access network is becoming critical as a large volume of traffic might be affected. Therefore, an effective supervision mechanism to detect and localize the fault is required to shorten the service interruption time. Meanwhile, open access provides a certain freedom for end users to choose the service and hence boosts competition among service/network providers. On the other hand, to offer open access in WDM-PON could result in a substantial change on architectural design, e.g., multiple feeder fibers (FFs) instead of a single one may be required to connect different service/network providers. Consequently, the traditional supervision mechanisms don’t work properly in open WDM-PON. To fill in this gap, several fault supervision mechanisms to support open access in WDMPON are proposed in this thesis. They can be applied to both disjoint and co-located FF layout where the choice of providers is done through wavelength selection. The feasibility of such solutions has been validated by evaluating transmission performance. We have carried out simulations in VPItransmissionMaker for different deployment scenarios. The results have confirmed that no significant degradation of the transmission performance is introduced by the proposed monitoring schemes compared to the benchmark, where no any fault supervision method is implemented.
426

Sunlight Modulation for Optical Wireless Communication

Ammar, Sahar 04 1900 (has links)
Solar energy is widely used for electricity generation, heating systems, and indoor environment daytime illumination. Indeed, large amounts of Sunlight energy remain insufficiently used. In this work, we aim at employing sunlight for data transmission as another option for wireless communications. Being emitted by an uncontrollable source, taming the Sunlight is a challenging task that requires appropriate technolo- gies to manipulate incident light. Throughout this thesis, we first review switchable glass technologies and investigate their potential use for light modulation. Liquid Crystal Devices (LCD) have adequate response time and contrast characteristics for such an application. In this regard, we design a novel Dual-cell Liquid Crystal Shutter (DLS) by stacking two Liquid Crystal cells that operate in opposite manners, and we build our Sunlight modulator with an array of DLSs. Then, we adopt Time Division Multiplexing and polarization-based modulation to boost the data rate and eliminate the flickering effect. In addition, we provide mathematical modeling of the system and study its performance in terms of communication and energy consumption. Finally, we introduce some numerical results to examine the impact of multiple parameters on the system’s performance and compare it with state-of-the-art, which showed that our system features higher data rates and extended link ranges.
427

Analyse de performance des réseaux optiques à commutation en sous-longueur d'onde / Performance analysis of subwavelength switching optical networks

Indre, Raluca Maria 05 November 2012 (has links)
Un défi majeur dans les réseaux d’aujourd’hui est de combler l’écart entre la haute vitesse de la transmission optique et la vitesse plus limitée du traitement électronique des données. Une option est de commuter les données directement dansle domaine optique. Dans cette thèse, nous proposons plusieurs solutions permettant la commutation dans le domaine optique à une granularité plus fine que la longueur d’onde, technique que nous appelons commutation sous-longueurd’onde. Pour montrer la pertinence des solutions proposées, nous analysons leur performance en termes de capacité de trafic, de débit et de délai. La performance est évaluée à la fois par des simulations et en utilisant des modèles de filesd’attente appropriés. Nous considérons d’abord le cas des réseaux métropolitains (Metropolitan Area Networks, MAN) et nous étudions la performance d’un anneau optique avec multiplexage en longueur d’onde (Wavelength Division Multiplexing, WDM) dans lequel la communication entre les noeuds du réseau se fait par insertion/extraction de données dans des créneaux temporels. Nous présentons un protocole entièrement distribué conçu pour assurer l’équité dansce réseau. Nous proposons également un mécanisme d’assemblage de paquets capable d’assurer des délais faibles ainsi que des taux de remplissage élevés. Nous proposons ensuite des solutions de commutation sous-longueur d’onde qui peuvent être appliquées dans le cas plus général des réseaux asynchrones. D’abord, nous proposons de résoudre le problème des collisions de la commutation optique par rafale (Optical Burst Switching, OBS) par la mise en oeuvre d’un mécanisme de réservation. Afin de maximiser l’utilisation des ressources, nous proposons d’adapter la taille de la rafale optique à la charge du réseau.Ensuite, nous proposons une solution alternative pour construire un réseau coeur tout-optique. A cette architecture, nous associons un protocole d’accès ainsi qu’un algorithme d’allocation dynamique de bande passante et nous analysons les performances de la solution proposée. Par le biais d’une étude de cas, nousmontrons que notre solution est capable de réduire considérablement la consommation énergétique par rapport aux architectures actuelles basées sur des routeurs IP. Enfin, nous proposons un nouveau dispositif optique capable derésoudre la contention directement dans le domaine optique. Nous montrons que ce dispositif simple peut être utilisé pour construire des réseaux optiques dynamiques à courte portée tels que les réseaux d’accès ou les centres de traitement de données. / A key challenge in today’s networks is to bridge the gap between high-speed optical transmission and limited electronic processing. This can be achieved by enabling payload to be switched directly in the optical domain.A simple solutionto provide optical switching is by allocating one wavelength channel to each source-destination pair, a technique called Optical Circuit Switching (OCS). Due to lack of sharing, OCS suffers from limited scalability. To overcome this issue,the capacity of each wavelength channel must be dynamically shared among different source-destination pairs. This requires data to be switched at subwavelength granularity by means of subwavelength switching. In this thesis, wepropose several solutions which enable subwavelength switching in optical networks. To show the relevance of the proposed solutions, we analyse their performance in terms of traffic capacity, flow throughput and packet delay. Performance is evaluated both through simulations and by means of appropriate queueing models. We first consider the case of Metropolitan Area Networks (MAN) and we study the performance of synchronous time-slotted Wavelength DivisionMultiplexing (WDM) ring in which network nodes communicate by inserting and extracting data from time-slots. We present a fully distributedMedia Access Control (MAC) protocol designed to ensure fairness. We also propose a burst assembly mechanism able to ensure low assembly delays and high fill rates of the optical time-slots. We then propose subwavelength switching solutions which can be applied in the more general case of asynchronous wide area networks. We first propose to solve the contention problems of conventional Optical Burst Switching (OBS) and the low utilization issue of wavelength-routed OBS byimplementing a two-way reservation OBS scheme in which the size of the opticalburst increases proportionally with the network load so as to maximize resourceutilization. Next, we propose a solution for building an all-optical wide area network based on multipoint-to-multipoint lightpath sharing. We also design an associated MAC protocol and a dynamic bandwidth allocation algorithm and analyse the performance of the proposed solution. By means of a case study, we show that the proposed solution has the potential to considerably reduce power consumption with respect to current router-based architectures. Finally, we propose a novel optical device able to solve contention directly in the optical domain withoutrequiring any optical buffering, electronic signalling or header processing. We show that thissimple device can be used as a building block for dynamic and power efficient short-range optical networks such as access networks or data centers.
428

Lanthanide Energy Transfer Donors on Nanoparticles Surfaces : From Fundamental Mechanisms to Multiplexed Biosensing / Transfert d'énergie entre lanthanides et nanoparticules : des mécanismes fondamentaux aux biosenseurs multiplexés

Chen, Chi 05 July 2019 (has links)
Le multiplexage optique basé sur des nanoparticules offre de nombreux avantages pour la biodétection et l'imagerie à multiparamètres. Toutefois, les modifications apportées à un paramètre entraînent également la modification d’autres paramètres. Par conséquent, la couleur, la durée de vie ou l’intensité ne peuvent pas être utilisées, respectivement, comme paramètre indépendant. Cette thèse peut être divisée en deux aspects. Le premier concerne le développement d'un multiplexage à une seule nanoparticule avec un temps résolu, basé sur le transfert d'énergie par résonance de type Förster (FRET) des complexes de lanthanides aux points quantiques (QD) et ensuite aux colorants fluorescents. Une investigation systématique de toutes les différentes combinaisons avec une large gamme de donneurs et d'accepteurs sur le QD est présentée, et les résultats expérimentaux sont comparés à la modélisation théorique. Le résultat ne contribue pas seulement à une compréhension complète de ces voies de transfert d'énergie compliquée entre multi donneurs / accepteurs sur des nanoparticules, mais offre également la possibilité d'utiliser les modèles pour développer de nouvelles stratégies permettant de préparer le QD avec une couleur, une durée de vie et une intensité réglables de manière indépendante. Le deuxième aspect porte sur le mécanisme de transfert d'énergie du Tb à la nanoparticule d'or (AuNP). Le transfert d'énergie par nanosurface (NSET) s'est révélé être un mécanisme opérationnel pour l'extinction des PL par les AuNP, une information importante pour le développement, la caractérisation et l'application de nanobiocapteurs basés sur l'extinction des PL par les AuNP. / Optical multiplexing based on nanoparticles provides many advantages for multiparameter biosensing and imaging. However, the changes in one parameter also lead to changing of other parameters, and thus, color, lifetime, or intensity could not be used as an independent parameter, respectively. This thesis can be divided into two aspects. The first one focuses on developing time-resolved single-nanoparticle multiplexing based on Förster resonance energy transfer (FRET) from lanthanide complexes to quantum dot (QD) to fluorescent dyes. Systematical investigation of all different combinations with a broad range of numbers of donors and acceptors on QD are presented, and the experimental results are compared with theoretical modelling. The result do not only contribute to a full understanding of such complicated multi donor-acceptor energy transfer pathways on nanoparticles but also open the opportunity to use the models for developing new strategies to achieve the QD with independent tunable color, lifetime and intensity. The second aspect focuses on the energy transfer mechanism from Tb to gold nanoparticle (AuNP). Nanosurface energy transfer (NSET) proved to be an operational mechanism in PL quenching by AuNPs, which is important information for the development, characterization, and application of nanobiosensors based on PL quenching by AuNPs.
429

Multicarrier transceivers using DFT filter banks with perfect reconstruction property

Duplessis-Beaulieu, François January 2008 (has links)
No description available.
430

Testable Clock Distributions for 3d Integrated Circuits

Buttrick, Michael T 01 January 2011 (has links) (PDF)
The 3D integration of dies promises to address the problem of increased die size caused by the slowing of scaling. By partitioning a design among two or more dies and stacking them vertically, the average interconnect length is greatly decreased and thus power is reduced. Also, since smaller dies will have a higher yield, 3D integration will reduce manufacturing costs. However, this increase in yield can only be seen if manufactured dies can be tested before they are stacked. If not, the overall yield for the die stack will be worse than that of the single, larger die. One of the largest issues with prebond die testing is that, to save power, a single die may not have a complete clock distribution network until bonding. This thesis addresses the problem of prebond die testability by ensuring the clock distribution network on a single die will operate with low skew during testing and at a reduced power consumption during operation as compared to a full clock network. The development of a Delay Lock Loop is detailed and used to synchronize disconnected clock networks on a prebond die. This succeeds in providing a test clock network that operates with a skew that is sufficiently close to the target postbond skew. Additionally, a scheme to increase interdie bandwidth by multiplexing Through-Silicon Vias (TSVs) by the system clock is presented. This technique allows for great increase in the number of effective signal TSVs while imposing a negligible area overhead causing no performance degradation.

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