Dissertations / Theses on the topic 'Transmission path'

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
Includes bibliographical references (leaves 77-79).
by Lon E. Sunshine.
Ph.D.

In this thesis, a new transport protocol, the Concurrent Multi-Path Real-time Transmission Control Protocol (cmpRTCP) is proposed. The proposed protocol has been designed to handle real-time streams (video and audio) over IP-networks. One of the key strengths of this protocol lies in its ability to intelligently exploit the availability of multiple paths between multi-homed hosts for concurrent transmission of unicast real-time streams. This work describes the architecture and operation of cmpRTCP in detail. In addition, the limitations of currently used transport protocols in handling real-time streams are also discussed. These limitations of other protocols have played a vital role in the design process of the proposed protocol. Experiments to evaluate the performance of cmpRTCP against other protocols and the results obtained therein are also documented in this work. Results show that cmpRTCP is a best effort protocol that tries to maximize the amount of data that is successfully delivered to the destination in a timely manner under varying drop and delay conditions of the network.

Un aspecte fonamental quan cal resoldre un problema vibroacústic en un sistema mecànic és el de determinar com flueix l’energia des d’una font donada, cap a qualsevol part del sistema. Això permet decidir quines són les accions a prendre per disminuir, per exemple, els nivells de soroll i vibracions en una determinada àrea del sistema. El comportament dinàmic d’un sistema mecànic es pot estimar utilitzant diversos mètodes numèrics, cadascun dels quals enfocat a un marge de freqüència determinat. Mentre a baixes freqüències es poden aplicar mètodes deterministes com el Mètode d’Elements Finits (FEM) o el Mètode d’Elements de Contorn (BEM), a altes freqüències, els mètodes estadístics com l’Anàlisi Estadística Energètica (SEA), esdevenen inevitables. A més a més, diverses tècniques com el FE-SEA híbrid, els models de Distribució Energètica (ED) o l’Anàlisi Estadística de distribució d’Energia modal (SmEdA), entre d’altres, han estat recentment plantejades per tal de tractar amb l’anomenat problema de les mitges freqüències. Tanmateix, encara que alguns mètodes numèrics poden predir la resposta vibroacústica puntual o amitjanada d’un sistema, aquests no proporcionen de forma directa informació sobre com flueix l’energia per tot el sistema. Per tant, cal algun tipus de post-processament per a determinar quines són les vies de transmissió d’energia. L’energia transmesa a través d’un determinat camí que connecti un subsistema font, on l’energia és introduïda, i un subsistema receptor, es pot calcular numèricament. Tot i això, la identificació dels camins que dominen la transmissió d’energia des d’una font fins a un receptor normalment acostuma a basar-se en l’experiència i el parer de l’enginyer. Així doncs, un mètode que permeti obtenir aquests camins de forma automàtica resultaria molt útil. La teoria de grafs proporciona una sortida a aquest problema, ja que existeixen diversos algorismes de càlcul de camins en grafs. En aquesta tesi, es proposa un enllaç entre els models vibroacústics i la teoria de grafs, que permet adreçar els problemes de vies de transmissió de forma directa. La dissertació comença centrant-se en els models SEA. Primerament, es mostra que té sentit realitzar una anàlisi de vies de transmissió (TPA) en SEA. Seguidament, es defineix un graf que representa de forma acurada els models SEA. Tenint en compte que la transmissió d’energia entre fonts i receptors es pot justificar mitjançant la contribució d’un grup finit de vies dominants en varis casos d’interès, es presenta un algorisme per calcular-les. A continuació, s’implementa un algorisme que inclou en el càlcul de camins la naturalesa estocàstica dels factors de pèrdues SEA. Tot seguit, es tracta com es pot estendre l’anàlisi de vies de transmissió al marge de la mitja freqüència. L’aplicació de la teoria de grafs a les mitges freqüències s’adapta per alguns models ED, així com també SmEdA. Finalment, es presenta una altra possible aplicació de la teoria de grafs en vibroacústica. S’implementa una estratègia basada en algorismes de talls en grafs per tal de reduir l’energia en un subsistema receptor amb la modificació d’un grup reduït de factors de pèrdues. Aquest grup de variacions, es troba calculant talls en el graf que separin els subsistemes fonts dels receptors.
A fundamental aspect when solving a vibroacoustic problem in a mechanical system is that of finding out how energy flows from a given source to any part of the system. This would help making decisions to undertake actions for diminishing, for example, the noise or vibration levels at a given system area. The dynamic behavior of a mechanical system can be estimated using different numerical methods, each of them targeting a certain frequency range. Whereas at low frequencies deterministic methods such as the Finite Element Method (FEM) or the Boundary Element Method (BEM) can be applied, statistical methods like Statistical Energy Analysis (SEA) become unavoidable at high frequencies. In addition, a large variety of approaches such as the hybrid FE-SEA, the Energy Distribution (ED) models or the Statistical modal Energy distribution Analysis (SmEdA), among many others, have been recently proposed to tackle with the so-called mid-frequency problem. However, although numerical methods can predict the pointwise or averaged vibroacoustic response of a system, they do not directly provide information on how energy flows throughout the system. Therefore, some kind of post-processing is required to determine energy transmission paths. The energy transmitted through a particular path linking a source subsystem, where external energy is being input, and a target subsystem, can be computed numerically. Yet, identifying which paths dominate the whole energy transmission from source to target usually relies on the engineer's expertise and judgement. Thus, an approach for the automatic identification of those paths would prove very useful. Graph theory provides a way out to this problem, since powerful path algorithms for graphs are available. In this thesis, a link between vibroacoustic models and graph theory is proposed, which allows one to address energy transmission path problems in a straightforward manner. The dissertation starts focusing on SEA models. It is first shown that performing a transmission path analysis (TPA) in SEA makes sense. Then a graph that accurately represents the SEA model is defined. Given that the energy transmission between sources and targets is justified by the contribution of a limited group of dominant paths in many cases of practical interest, an algorithm to find them is presented. Thereafter, an enhanced algorithm is devised to include the stochastic nature of SEA loss factors in the ranking of paths. Next, it is discussed how transmission path analysis can be extended to the mid frequency range. The graph approach for path computation becomes adapted for some ED models, as well as for SmEdA. Finally, we outline another possible application of graph theory to vibroacoustics. A graph cut algorithm strategy is implemented to achieve energy reduction at a target subsystem with the sole modification of a reduced set of loss factors. The set is found by computing cuts in the graph separating source and receiver subsystems.
Un aspecto fundamental a la hora de resolver un problema vibroacústico en un sistema mecánico es el de determinar cómo fluye la energía desde una determinada fuente hasta cualquier parte del sistema. Ello ayudaría a tomar decisiones para emprender acciones destinadas a disminuir, por ejemplo, los niveles de ruido y vibraciones en un área del sistema dada. El comportamiento dinámico de un sistema mecánico se puede estimar utilizando varios métodos numéricos, cada uno de ellos enfocado a un determinado rango de frecuencia. Mientras en las bajas frecuencias se pueden aplicar métodos deterministas como el Método de los Elementos Finitos (FEM) o el método de Elementos de Contorno (BEM), los métodos estadísticos como el Análisis Estadístico Energético son inevitables en las altas frecuencias. Además, se han desarrollado gran variedad de técnicas como el FE-SEA híbrido, los modelos de Distribución de Energía (ED) o el Análisis Estadístico de distribución de Energía modal (SmEdA), entre otras, para tratar el llamado problema de las medias frecuencias. Sin embargo, aunque los métodos numéricos pueden predecir la respuesta vibroacústica puntual o promediada de un sistema mecánico, ellos no proporcionan información sobre como fluye la energía en el sistema. Por lo tanto, hace falta algún tipo de post-procesado para determinar las vías de transmisión de energía. La energía transmitida a través de un determinado camino que conecta un subsistema fuente, donde se introduce la energía, y un subsistema receptor, se puede calcular numéricamente. A pesar de ello, identificar qué caminos dominan la transmisión de energía desde la fuente al receptor normalmente suele recaer en la experiencia o el juicio del ingeniero. Así pues, un método automático para identificar estos caminos resultaría muy útil. La teoría de grafos proporciona una solución a este problema, ya que existen potentes algoritmos de cálculos de caminos en grafos. En esta tesis, se propone un enlace entre los modelos vibroacústicos y la teoría de grafos, que permite abordar los problemas de vías de transmisión de forma directa. La disertación empieza centrándose en los modelos SEA. Primeramente, se muestra que tiene sentido realizar un análisis de vías de transmisión (TPA) en un modelo SEA. Seguidamente, se define un grafo que representa fielmente un modelo SEA. Teniendo en cuenta que en muchos casos de interés práctico, la transmisión de energía entre fuentes y receptores se puede justificar mediante la contribución de un grupo finito de vías de transmisión, se define un algoritmo para encontrarlas. A continuación, se implementa un algoritmo que incluye en el cómputo de caminos la naturaleza estocástica de los factores de pérdidas SEA. Luego, se trata la extensión del análisis de vías de transmisión al rango de media frecuencia. La técnica de teoría de grafos aplicada a cálculo de caminos se adapta para algunos modelos ED y también SmEdA. Finalmente, se presenta otra posible aplicación de la teoría de grafos a la vibroacústica. Se implementa una estrategia basada en algoritmos de cortes en grafos destinada a reducir la energía en un subsistema receptor mediante la simple modificación de un grupo reducido de factores de pérdidas. El grupo se encuentra calculando cortes que separen en el grafo los subsistemas fuentes de los subsistemas receptores.

This paper analyses the process of wealth accumulation with regard to the path dependence theory. Based on the theoretical foundations of Robert King Merton, Vilfredo Pareto and Pierre Bourdieu, mechanisms of wealth accumulation are analyzed. These mechanisms, which are understood as direct and indirect network effects, are formalized using the statistical computing software R. A base model without any mechanisms of wealth accumulation is developed, which makes it possible to include the analyzed mechanisms step by step and observe their effects on the process of wealth accumulation and social inequality. Piketty's findings from his work Capital in the 21st Century are included in the formalized models of wealth accumulation, in particular the relationship between the rate of return on capital and the growth rate of the economy. (author's abstract)

Large scale path loss modeling plays a fundamental role in designing both fixed and mobile radio systems. Predicting the radio coverage area of a system is not done in a standard manner. Wireless systems are expensive systems. Therefore, before setting up a system one has to choose a proper method depending on the channel environment, frequency band and the desired radio coverage range. Path loss prediction plays a crucial role in link budget analysis and in the cell coverage prediction of mobile radio systems. Especially in urban areas, increasing numbers of subscribers brings forth the need for more base stations and channels. To obtain high efficiency from the frequency reuse concept in modern cellular systems one has to eliminate the interference at the cell boundaries. Determining the cell size properly is done by using an accurate path loss prediction method. Starting from the radio propagation phenomena and basic path loss models this thesis aims at describing various accurate path loss prediction methods used both in rural and urban environments. The Walfisch-Bertoni and Hata models, which are both used for UHF propagation in urban areas, were chosen for a detailed comparison. The comparison shows that the Walfisch-Bertoni model, which involves more parameters, agrees with the Hata model for the overall path loss.

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.
Dr. Henry L. Owen III, Committee Member ; Dr. David Keezer, Committee Member ; Dr. D. Scott Wills, Committee Chair.

Le rendement d’un hélicoptère est étroitement lié à son poids. L’allègement des composants profite à la charge utile transportable. Il implique généralement une diminution de leur rigidité, donc une augmentation de leur déformation. Les boites de transmission par engrenages sont particulièrement concernées. Elles doivent assurer la transmission de puissances importantes à masse minimale. Les axes des roues dentées se désalignent alors progressivement au fur et à mesure de l’application du chargement. Les topographies des dentures spiroconiques sont corrigées pour tolérer ce déplacement et optimiser les performances du mécanisme. La portée d’engrènement ne doit pas toucher une arête afin d’éviter toute surpression par effet de bord et une dégradation prématurée des dents. Il faut améliorer la répartition de l’effort transmis et des pressions de contact. L’erreur de transmission induit des vibrations et du bruit. Il faut donc la minimiser. L’étude de la correction à appliquer à la denture est fastidieuse et requiert une longue période d’apprentissage lorsqu’elle est réalisée manuellement. Les travaux présentés s’inscrivent dans le cadre d’une automatisation du processus. L’usinage et l’engrènement des dentures sont simulés numériquement. Les méthodes proposées sont simples et robustes. Trois problèmes d’optimisation différents sont traités et analysés
The performance of a helicopter is closely linked to its weight. The components are lightened to benefit the carried payload. That usually involves a reduction in their stiffness, so an increase in their deformation. The transmission gear boxes are particularly affected. They must ensure the transmission of high powers with a minimal mass. The load makes the axes of the gears misaligned. The topographies of the spiral bevel gear teeth are corrected in order to tolerate the displacement and optimize the mechanism performances. The contact path must not touch tooth edges to avoid any overpressure and premature degradation. The distribution of the transmitted load and of the contact pressures must be improved. The transmission error induces vibrations and noise. Therefore, it must be minimized. The study of the correction to be applied to the teeth is tedious and requires a long learning period when it is done manually. The presented works fit into the scheme of an automated process. The machining and meshing of the teeth are simulated numerically. The proposed methods are simple and robust. Three different optimization problems are discussed and analyzed

The continuous growth of traffic demand driven by the brisk increase in number of Internet users and emerging online services creates new challenges for communication networks. The latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build Transparent Optical Networks (TONs) which are expected to be able to satisfy this rapidly growing capacity demand. Moreover, with the ability of TONs to transparently carry the optical signal from source to destination, electronic processing of the tremendous amount of data can be avoided and optical-to-electrical-to-optical (O/E/O) conversion at intermediate nodes can be eliminated. Consequently, transparent WDM networks consume relatively low power, compared to their electronic-based IP network counterpart. Furthermore, TONs bring also additional benefits in terms of bit rate, signal format, and protocol transparency. However, the absence of O/E/O processing at intermediate nodes in TONs has also some drawbacks. Without regeneration, the quality of the optical signal transmitted from a source to a destination might be degraded due to the effect of physical-layer impairments induced by the transmission through optical fibers and network components. For this reason, routing approaches specifically tailored to account for the effect of physical-layer impairments are needed to avoid setting up connections that don’t satisfy required signal quality at the receiver. Transparency also makes TONs highly vulnerable to deliberate physical-layer attacks. Malicious attacking signals can cause a severe impact on the traffic and for this reason proactive mechanisms, e.g., network design strategies, able to limit their effect are required. Finally, even though energy consumption of transparent WDM networks is lower than in the case of networks processing the traffic at the nodes in the electronic domain, they have the potential to consume even less power. This can be accomplished by targeting the inefficiencies of the current provisioning strategies applied in WDM networks. The work in this thesis addresses the three important aspects mentioned above. In particular, this thesis focuses on routing and wavelength assignment (RWA) strategies specifically devised to target: (i) the lightpath transmission quality, (ii) the network security (i.e., in terms of vulnerability to physical-layer attacks), and (iii) the reduction of the network energy consumption. Our contributions are summarized below. A number of Impairment Constraint Based Routing (ICBR) algorithms have been proposed in the literature to consider physical-layer impairments during the connection provisioning phase. Their objective is to prevent the selection of optical connections (referred to as lightpaths) with poor signal quality. These ICBR approaches always assign each connection request the least impaired lightpath and support only a single threshold of transmission quality, used for all connection requests. However, next generation networks are expected to support a variety of services with disparate requirements for transmission quality. To address this issue, in this thesis we propose an ICBR algorithm supporting differentiation of services at the Bit Error Rate (BER) level, referred to as ICBR-Diff. Our approach takes into account the effect of physical-layer impairments during the connection provisioning phase where various BER thresholds are considered for accepting/blocking connection requests, depending on the signal quality requirements of the connection requests. We tested the proposed ICBR-Diff approach in different network scenarios, including also a fiber heterogeneity. It is shown that it can achieve a significant improvement of network performance in terms of connection blocking, compared to previously published non-differentiated RWA and ICBR algorithms.  Another important challenge to be considered in TONs is their vulnerability to physical-layer attacks. Deliberate attacking signals, e.g., high-power jamming, can cause severe service disruption or even service denial, due to their ability to propagate in the network. Detecting and locating the source of such attacks is difficult, since monitoring must be done in the optical domain, and it is also very expensive. Several attack-aware RWA algorithms have been proposed in the literature to proactively reduce the disruption caused by high-power jamming attacks. However, even with attack-aware network planning mechanisms, the uncontrollable propagation of the attack still remains an issue. To address this problem, we propose the use of power equalizers inside the network nodes in order to limit the propagation of high-power jamming attacks. Because of the high cost of such equipment, we develop a series of heuristics (incl. Greedy Randomized Adaptive Search Procedure (GRASP)) aiming at minimizing the number of power equalizers needed to reduce the network attack vulnerability to a desired level by optimizing the location of the equalizers. Our simulation results show that the equalizer placement obtained by the proposed GRASP approach allows for 50% reduction of the sites with the power equalizers while offering the same level of attack propagation limitation as it is possible to achieve with all nodes having this additional equipment installed. In turn, this potentially yields a significant cost saving.    Energy consumption in TONs has been the target of several studies focusing on the energy-aware and survivable network design problem for both dedicated and shared path protection. However, survivability and energy efficiency in a dynamic provisioning scenario has not been addressed. To fill this gap, in this thesis we focus on the power consumption of survivable WDM network with dynamically provisioned 1:1 dedicated path protected connections. We first investigate the potential energy savings that are achievable by setting all unused protection resources into a lower-power, stand-by state (or sleep mode) during normal network operations. It is shown that in this way the network power consumption can be significantly reduced. Thus, to optimize the energy savings, we propose and evaluate a series of energy-efficient strategies, specifically tailored around the sleep mode functionality. The performance evaluation results reveal the existence of a trade-off between energy saving and connection blocking. Nonetheless, they also show that with the right provisioning strategy it is possible to save a considerable amount of energy with a negligible impact on the connection blocking probability. In order to evaluate the performance of our proposed ICBR-Diff and energy-aware RWA algorithms, we develop two custom-made discrete-event simulators. In addition, the Matlab program of GRASP approach for power equalization placement problem is implemented.

QC 20120508

Fans are often used in equipment such as home appliances andelectronic equipment where the margin of profit is small butcustomers demands on a low noise level are high. Therefore,methods for predicting the noise emitted by an applicationincluding one or several fans are desirable in order toimprove, accelerate and reduce the cost of low-noise design.The Noise Shaping Technology (NST) has been developed withinthe EC-project NABUCCO in order to fulfil the aboverequirements on a prediction method. According to NST, thenoise source (not necessary a fan) is described by one orseveral noise descriptors, CSSs, and the correspondingtransmission paths through the structure described by one orseveral transfer functions, ACFs. In this thesis, theapplicability of NST is evaluated on a cabinet for electronicequipment where small axial cooling fans constitute the primarysources of the airborne sound.

As an axial fan is a complex source of sound,simplifications are necessary when modelling its acousticproperties. Therefore, the sound radiation of an axial fan infree space was examined by expanding the generated soundpressure field into spherical harmonics. The conclusion on asource model for the cabinet example, where the fans are moreor less In-duct mounted, is a modified single axial dipole. Themodel is expected to be valid in the entire frequency range ofinterest except in the mid-frequency range where the modaldensity is low. In order to improve the source model in thisfrequency range, a future model based on a rotating dipole isproposed.

The sound power of a small axial fan is measured in an ISO10302 test-rig. In order to take account of flow conditions,acoustically transparent ducts have been developed. These shallbe attached to the test-rig when measuring the sound power ofthe fan. A simple but practical method of how to correct thesound power for the baffling effect of the test-rig has alsobeen developed. Finally, the sound power can be converted intodipole force, which is the airborne CSS corresponding to thesingle axial dipole model.

The corresponding airborne transfer function (ACF), i.e.,from dipole force at the source point to sound pressure at thereceiver point, is measured reciprocally by taking use ofLyamshevs reciprocity relation.

From multiplication of the CSS and the ACF, the soundpressure can be predicted. The prediction shows quite goodagreement with the measured values.

Keywords:axial fan, airborne sound, sourcecharacterisation, transmission path analysis, In-duct,spherical harmonics, rotating dipole, installation effects, ISO10302, flow conditions, baffling effect, acousticallytransparent ducts, Lyamshevs reciprocity relation, reciprocity,CSS, ACF, GSM, NST.

Orientador: Amir Ordacgi Caldeira
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-08-18T12:04:56Z (GMT). No. of bitstreams: 1 GarciaRodriguez_AlexisOmar_D.pdf: 2441638 bytes, checksum: 00dfa78fb7b0c9f69778a51704c587b7 (MD5) Previous issue date: 2011
Resumo: Este trabalho foi motivado por várias dificuldades encontradas no estudo do artigo de M. Ueda, Transmission Spectrum of a Tunneling Particle Interacting with Dynamical Fields: Real- Time Functional Integral Approach, Phys. Rev. B 54, 8676 (1996). Nesse artigo, num formalismo de tempo real, é descrito o tunelamento de uma partícula através de uma barreira utilizando tempos não reais de travessia através dessa barreira. No presente trabalho é proposto um formalismo mais amplo de tempo real para uma introdução mais natural de valores complexos do tempo na descrição do tunelamento de uma partícula cm interação com o ambiente. Esta proposta está baseada no chamado método do tempo complexo utilizado no caso do tunelamento de uma partícula sem interação com o ambiente estudado nos trabalhos de D. W. McLaughlin, J. Math. Phys. 13, 1099 (1972) c B. R. Holstein c A. R. Swift, Am. J. Phys. 50, 833 (1982). Seguindo o trabalho citado de Ueda, o ambiente da partícula é representado através de um conjunto, ou banho térmico, de osciladores harmônicos caracterizados por uma função de densidade espectral J(w). Utilizando o método de Feynman de integrais de trajetória, integramos sobre as coordenadas dos osciladores do banho c obtemos uma expressão exata para o espectro de transmissão da partícula para uma temperatura do banho T > O. Limitando-nos então ao caso mais simples T = O, estudamos o tunelamento dissipativo da partícula através da barreira. Considerando h um parâmetro pequeno (limite semiclássico), aproximamos o espectro de transmissão da partícula através da contribuição das trajetórias clássicas c suas trajetórias vizinhas. Nesta aproximação consideramos a variação da ação efetiva da partícula para tempos dados de duração das trajetórias c deste modo substituímos o procedimento variacional seguido no trabalho indicado de Ueda onde não é considerada a variação nos tempos de travessia da partícula através da barreira. Num segundo problema variacional nos tempos de duração das trajetórias clássicas de acordo com o método do tempo complexo e considerando também a variação nas posições iniciais c finais dessas trajetórias, obtemos as equações de movimento das chamadas trajetórias clássicas especiais. Este tratamento das coordenadas iniciais c finais das trajetórias clássicas substitui o procedimento seguido no trabalho de Ueda onde é considerc1da uma aceleração nula durante todo o trajeto de movimento incluindo o trajeto na região da barreira. Diferentemente do artigo citado de Ueda, no presente trabalho utilizamos pacotes de ondas relativamente bem localizados para descrever os estados inicial e final da partícula. Em consequência, aproximamos o espectro de transmissão da partícula através de trajetórias clássicas especiais com coordenadas iniciais c finais iguais ao valor médio da coordenada para esses pacotes de ondas. O procedimento seguido neste trabalho, baseado no método do tempo complexo, permite obter o fator ele acoplamento apropriado entre as duas trajetórias que descrevem a ação efetiva ela partícula substituindo assim o procedimento de tipo ad hoc seguido com este fim no trabalho indicado de Ueda. O método do tempo complexo permite obter também o termo ela diferença entre a ação efetiva da partícula c o expoente ele tunelamento, sendo que estas grandezas são tratadas como iguais no trabalho citado de Ueda. Considerando termos até primeira ordem num campo elétrico externo c na interação da partícula com o banho de osciladores, obtemos expressões gerais para o expoente de tunelamento, o espectro de transmissão, a taxa total de tunelamento c o tempo de travessia da partícula através da barreira, válidas para um banho de osciladores com uma função de densidade espectral arbitrária. Assim temos que a interação da partícula com um banho de osciladores com uma função de densidade espectral arbitrária diminui a taxa total de tunelamento. Adicionalmente, obtemos que a interação da partícula com os osciladores do banho com frequências ?a = ?C ~ 1.9 T , onde T0 é o tempo característico de travessia através da barreira no caso cm que não há interação da partícula com o banho de osciladores nem campo elétrico, não afeta o tempo característico de travessia através da barreira. Por outro lado, a interação da partícula com os osciladores do banho que têm frequências ?a < ?C (?a > ?C) diminui (aumenta) o tempo característico de travessia através da barreira. No caso de um banho de osciladores com uma única frequência w c uma constante de acoplamento com a partícula dada por Ca = Ca (wT)a , são identificados cinco comportamentos diferentes em função de w para o expoente característico de tunelamento e o tempo característico de travessia através da barreira. Estes comportamentos correspondem aos valores de s < 1, s = 1, 1 < s < 2, s = 2 e s > 2. No trabalho de M. Ueda, Phys. Rev. B 54, 8676 (1996), foi considerado somente o expoente característico de tunelamento no caso s = 1. No caso de um banho ôhmico de osciladores a temperatura zero, assim corno no caso de um banho de osciladores com uma única frequência, obtemos que o espectro de transmissão da partícula é zero para urna energia final característica da partícula maior que a energia inicial característica. Este resultado corrige o resultado correspondente no trabalho citado de Ueda, o qual não é consistente do ponto de vista físico, permitindo também obter de um modo mais coerente a corrente de tunelamento entre dois metais separados por um material isolante a temperatura zero. Obtém-se também que a interação da partícula com um banho ôhmico de osciladora não afeta o tempo característico de travessia através da barreira até primeira ordem nessa interação
Abstract: This work was motivated by several difficulties found when studying the article by M . Ueda, Transmission Spectrum of a Tunneling Particle Interacting with Dynamical Fields: Real-Time Functional-Integral Approach, Phys. Rev. B 54, 8676 (1996). In that paper, using a real-time formalism, a tunneling particle is described by complex traversal times of tunneling. In the present work we propose a broader real-time formalism that allows for a more natural introduction of complex values of time in the description of a tunneling particle interacting with the environment. This proposal is based on the well-known complex time method used in the case of a tunneling particle with no interaction with the environment studied in the works of D. W. McLaughlin, J. Math. Phys. 13, 1099 (1972) and B. R. Holstein and A. R. Swift, Am. J. Phys. 50, 833 (1982). Following the cited work of Ueda, the environment of the particle is represented by a set, or heat bath, of harmonic oscillators which is characterized by a spectral density function J(w). Using the Feynman path integrals method, we integrate out the coordinates of the bath oscillators and obtain an exact expression for the transmission spectrum of the particle for a bath temperature T > O. Limiting ourselves to the simpler case T = O, we study the case of a dissipative tunneling of the particle. Considering h a small parameter (semiclassical limit) we approximate the transmission spectrum of the particle by the contribution of the classical trajectories and its neighboring paths. In this approach we consider the variation of the effective action of the particle for given duration times of the paths and replace the variation procedure followed in the cited work of Ueda where the variation in the traversal times of tunneling is not considered. In a second variation problem for the duration times of the classical paths, according to the complex time method and considering also the variation in the initial and final positions of these paths, we obtain the equations of motion for the so-called special classical paths. This treatment of the initial and final coordinates of the classical paths replaces the procedure followed in the cited work of Ueda where an acceleration equal to zero is considered during the entire path of motion including the region under the barrier. Unlike the cited article of Ueda, we use in the present work wave packets relatively well localized to describe the init.ial and final statics of the particle. Conscqncnt.ly, we approximate the transmission spectrum of the particle through special classical paths with initial and final coordinates equal to the average value of the coordinate for those wave packets. The procedure followed in this work, based on the complex time method, gives the appropriate coupling factor between the two paths describing the effective action of the particle and thus replaces the ad hoc procedure followed for this purpose in the cited work of Ueda. The complex time method also allows us to obtain the difference term between the effective action of the particle and the tunneling exponent. These quantities are treated as equal in Ueda\'s work. Considering terms up to first order in an external electric field and the interaction of the particle with the bath of oscillators, we obtain general expressions for the tunneling exponent, transmission spectrum, total tunneling rate and traversal time of tunneling, which are valid for a bath of oscillators with an arbitrary spectral lenity function. We find that the interaction of the particle with a bath of oscillators with an arbitrary spectral density function decreases the total tunneling rate. Also, we find that the interaction of the particle with the bath oscillators with frequencies ?a = ?C ~ 1.9 T , where To is the characteristic traversal time of tunneling when there is no interaction of the particle with the bath of oscillators nor electric field. , does not affect the characteristic traversal time of tunneling. On the other hand, the interaction of the particle with the bath oscillators having frequencies ?a< ?c (?a: > ?c decreases (increases) the characteristic traversal time of tunneling. In the case of a bath of oscillators with a single frequency w and a coupling constant with the particle given by Ca = Ca (wT)a we identify five different behaviors deepening on w for the characteristic tunneling exponent and the characteristic traversal time of tunneling. These behaviors correspond to the values of s < 1, s = 1, 1 < s < 2, s = 2 and s > 2. In the work of M. Ueda, Phys. Rev. B 54, 8676 (1996), it was only considered the characteristic tunneling exponent in the case s = 1. In the case of an ohmic bath of oscillators at zero temperature, as well as in the case of a bath of oscillators with a single frequency, we obtain that the transmission spectrum of the particle is ;1,cro for a final characteristic energy of the particle greater than the initial characteristic energy. This result corrects the corresponding result in Ueda work, which is not consistent from a physical point of view, allowing also for a more coherent derivation of the tunneling current between two metals separated by an insulating material at zero temperature. It is also obtained that the interaction of the particle with an ohmic bath of oscillators does not affect the characteristic traversal time of tunneling up to first order in that interaction
Doutorado
Física
Doutor em Ciências

This dissertation deals with four topics. The first three are in the same environment, the transmission paths. The fourth refers to the synthesis of subsystems and more specifically to two subsystems linked by any number of elastic elements. In the first topic it is proved that the solution of any linear mechanical system can be expressed as a linear combination of signal transmission paths. This is done in the framework of the Global Transfer Direct Transfer (GTDT) formulation for vibroacoustic problems. Transmission paths are expressed as powers of the transfer matrix. The key idea of the proof is to generalise the Neumann series of the transfer matrix ,which is convergent only if its spectral radius is smaller than one, into a modified Neumann series that is convergent regardless of the eigenvalues of the transfer matrix. The modification consists in choosing the appropriate combination coefficients for the powers of the transfer matrix in the series. A recursive formula for the computation of these factors is derived. The theoretical results are illustrated by means of numerical examples. Finally, we show that the generalised Neumann series can be understood as an acceleration of Jacobi iterative method. For complex geometries, the definition of the subsystems is not a straightforward task. We present as a second topic a subsystem identification method based on the direct transfer matrix, which represents the first-order paths. The key ingredient is a cluster analysis of the rows of the powers of the transfer matrix. These powers represent high-order paths in the system. Once subsystems are identified, the proposed approach also provides a quantification of the degree of coupling between subsystems. This information is relevant to decide whether a subsystem may be analysed independently of the rest or subsystems or not. The two features (subsystem identification and quantification of the degree of coupling) are illustrated by means of numerical examples: plates coupled by means of springs and rooms connected by means of a cavity. In the third work, Advanced Transfer Path Analysis (ATPA) is applied to a cuboid-shaped box. The simplicity of this vibroacoustic system helps to make a detailed analysis of the ATPA method in a more controlled environment than in situ measurements in trains, wind turbines or other mechanical systems with complex geometry, big dimensions and movement. At the same time, a numerical model (based on finite elements) of the box is developed. The agreement between the experimental measurements and the numerical results is good. The numerical model is used in order to perform tests that cannot be accomplished in practise. The results are helpful in order to verify hypotheses, provide recommendations for the testing procedures and study some aspects of ATPA such as the reconstruction of operational signals by means of direct transfer functions or to quantify and understand which are the transmission mechanisms in the box. The fourth topic introduces a method to synthesize the modal characteristics of a system from the modal characteristics of its subsystems. The interest is focused on those systems with elastic links between the parts which is the main feature of the proposed method. An algebraic proof is provided for the case of arbitrary number of connections. The solution is a system of equations with a reduced number of degrees of freedom that correspond to the number of elastic links between the subsystems. In addition the method is also interpreted from a physical point of view (equilibrium of the interaction forces). An application to plates linked by means of springs shows how the global eigenfrequencies and eigenmodes are properly computed by means of the subsystems eigenfrequencies and eigenmodes.
Aquest treball estudia quatre temes. Els tres primers estan en el àmbit de les vies de transmissió. El quart fa referencia a la síntesi de subsistemes i mes concretament a dos subsistemes lligats per un nombre qualsevol de molles. En el primer treball es demostra que la solució de qualsevol sistema mecànic lineal es pot expressar com una combinació lineal de vies de transmissió de senyal. Això es fa en el marc de la formulació per problemes vibroacústics del Global Transfer Direct Transfer (GTDT). Les vies de transmissió s'expressen com les potencies de la matriu de transferències. La idea clau de la demostració es generalitzar la sèrie de Neumann aplicada a la matriu de transferència, que és una sèrie convergent només si el radi espectral és menor que u, amb una sèrie de Neumann modificada que convergeix amb independència del radi espectral de la matriu de transferència. La modificació consisteix en escollir els coeficients apropiats per a les potències de la matriu de transferència a la sèrie. Una fórmula recursiva facilita el càlcul. Els resultats teòrics s'il·lustren amb exemples numèrics. Finalment es mostra que la sèrie de Neumann generalitzada es pot aplicar per accelerar el mètode iteratiu de Jacobi. En geometries complexes, la definició dels subsistemes no es directe. Com a segon tòpic es presenta un mètode per a identificar els subsistemes que es basa en la matriu de transferència que representa els camins de primer ordre. La clau es un estudi clúster de les files de les potencies de la matriu de transferència. Aquestes potencies representen els camins d'ordre superior en el sistema i són més afectats per l'esmorteïment que els camins d'ordre inferior. Quan el subsistemes estan identificats, el mètode proposat també dona una quantificació del grau d'acoblament entre els subsistemes. Aquesta informació és important per decidir quan un subsistema es pot analitzar amb independència de la resta de subsistemes. Les dues aplicacions (identificació i quantificació del grau d'acoblament,) s?il·lustren mitjanant exemples numèrics: plaques lligades amb molles i habitacions connectades per un forat. En el tercer treball s'aplica ATPA a una caixa. La simplicitat d'aquest sistema vibroacústic ajuda a poder fer una anàlisi detallada del mètode ATPA en un entorn més controlat que el que es disposa amb assaigs en trens, turbines eòliques o altres sistemes mecànics de geometria complexa, grans dimensions i que estan en moviment. Es fa un model numèric basat en Elements Finits que correspon bé amb els assaigs fets sobre la caixa real. El model numèric s'empra per provar resultats del mètode que son difícils de demostrar en experiments reals, també per trobar procediments per limitar les imprecisions inevitables als assaigs i que poden afectar a la reconstrucció dels senyals en funcionament real i per aprofundir en els mecanismes de transmissió del senyal. El quart treball introdueix un mètode per a sintetitzar les característiques modals d'un sistema a partir de les característiques modals dels subsistemes. L'interès s'adreça als sistemes que tenen les seves parts lligades elàsticament sent aquest aspecte el factor diferencial. Es fa una demostració algebraica per a qualsevol nombre de connexions. El resultat és un sistema d'equacions de dimensió igual al nombre de connexions que, normalment, és molt inferior al nombre de graus de llibertat. El mètode s'interpreta a més des del punt de vista físic (equilibri entre les forces de interacció). Amb un exemple consistent en dues plaques lligades amb molles es demostra que freqüències i modes propis es calculen de forma adient.

This diploma thesis is about creating a program to model turbulent cells of different sizes on the chosen transmission path. The initial part of the work is devoted to the formation of atmospheric turbulence and the mathematical description of the extent of turbulence and its effect on optical waves. The methods of the turbulence generation and their physical description of formation are described below. The practical part is devoted to the created program in the MATLAB.

Cette thèse interroge les dynamiques de construction du rapport à la politique (intérêt, critique, indifférence, engagement etc.) des descendants d’immigrés nés en France – ou y ayant grandi – et résidant dans un quartier d'habitat social dans lequel est mise en oeuvre la politique de la ville. L'originalité de ce travail vient du fait que différents rapports à la politique sont étudiés et que les familles rencontrées sont originaires de différents pays (Sénégal, Algérie, Maroc, Vietnam, Laos, Comores etc.). L'analyse développée à partir d’entretiens biographiques souligne l’influence des différents parcours migratoires des parents et des expériences communes des enfants sur la construction de leurs attitudes politiques ; elle questionne leur éventuelle spécificité. Elle accorde une attention particulière à la mémoire familiale et aux dynamiques des transmissions intergénérationnelles, aux trajectoires socioprofessionnelles des descendants d’immigrés et de leurs parents ainsi qu’au contexte local de vie
This PhD questions the dynamics of political attitudes (interest, criticism, indifference, involvement etc.) of French youths from non-European immigrant background born or raised in France in deprived areas where a specific policy is implemented. The originality of this study is that it includes different attitudes towards politics and different countries of origin. The interlocutors interviewed are from Senegal, Algeria, Morocco, Vietnam, Laos, Comoros etc. The analysis developed from biographical interviews underlines the influence of the different migration paths of the parents, and the common experiences of their children on the construction of their political attitudes; it questions their possible specificity. This analysis pays particular attention to the family memory and the dynamics of intergenerational transmission, to the socio-professional trajectories of immigrants’ descendants and those of their parents as well as their local context of residence

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The construction of electricity generation projects are held in places where there are specific conditions for its implementation, and it appears that these are not always close to the consumer markets. The energy needs to be transported to the consumption centers located many kilometers away, and to this end are used to power transmission lines. These developments are characterized by many different situations that impact on their time of completion. In order to pursue project management options so that deadlines are met, this research applies a risk management methodology for projects by means of the quantitative risk assessment. It is addressed to the energy transmission area with a focus on the project deadline. The proposed model adopts the Critical Chain Project Management – CCPM, whereby the appropriate activities duration are those achievable in the shortest time as possible. The use of CCPM calls for the application of buffers along the project schedule to control the uncertainties. The proposed methodology applies the Monte Carlo Simulation – MCS to the schedule, associating the Minimum, Most likely and Maximum times to the activities. The identified risks are related to these activities. The outcome resulting from the proposed methodology is quantitative and provides useful information to containment and contingency actions.
A construção dos empreendimentos de geração de energia elétrica é realizada nos locais onde existem condições específicas para sua implantação, e, nem sempre estes são próximos aos centros consumidores. A energia gerada necessita ser transportada para os centros de consumo localizados a muitos quilômetros de distância, e, para tal são utilizadas as Linhas de Transmissão de Energia. Estes empreendimentos caracterizam-se por encontrar situações diversas e que impactam no seu prazo de conclusão. Com o objetivo de buscar opções de gerenciamento de projetos para que os prazos sejam alcançados, esta pesquisa aplica uma metodologia para gestão dos riscos em projetos, com a aplicação de análise quantitativa dos riscos. Será aplicada na área de transmissão de energia com foco no prazo de conclusão. O modelo proposto utiliza o método do Gerenciamento de Projeto pela Corrente Crítica – CCPM, por meio do qual as durações das atividades consideradas são aquelas exequíveis no menor prazo possível. O uso da CCPM prevê a introdução de buffers no cronograma do projeto para controlar as incertezas. A metodologia proposta aplica ao cronograma a Simulação de Monte Carlo- SMC, associando às suas atividades o prazo Mínimo, Mais Provável e Máximo. Os riscos identificados são associados às atividades. O resultado da aplicação da metodologia proposta é uma análise dos riscos do projeto indicando a probabilidade de consumo dos buffers, as atividades que mais impactam no seu consumo e os riscos associados a estas. O resultado desta análise é quantitativa e gera informações úteis para ações de contenção e contingência.

VHF står för "Very High Frequency" och är ett frekvensband som ligger i området 30 - 300 MHz. Maritim VHF är standard för Sjöfartsverket och fungerar över hela världen. Det är ett kommunikationssystem som bidrar till ökad säkerhet och kan rädda liv på sjön. Andra vanliga kommunikationssystem som mobiltelefoni fungerar inte tillförlitligt. Idag fungerar mobiltelefoni i stora delar av skärgården och längs kusterna men när det gäller kommunikation mellan fartyg längre ut till havs är den maritima VHF-kommunikationen överlägsen. Sjöfartsverket driver för sitt eget och kunders behov ett mobilradionätverk kallat kustradionätverket. Radiotrafiken i nätet sker både på Very High Frequency (VHF) och Medium frequency (MF). VHF-systemet är ett internationellt system som bland annat används till att kommunicera till sjöss och den trafiken befinner sig i frekvensbandet 155.5 - 162.025 MHz. Inom VHF-bandet finns det 55 kanaler. Kanalerna vid kustradiostationen kallas för duplexkanaler och innebär att kustradiostationerna sänder och tar emot signaler på två olika frekvenser. Radioutbredningen hos antennen som är installerad på basstationen har riktverkan i vissa riktningar och dämpningar i andra. Detta kan ses i strålningsdiagrammet under kapitlet "Täckningsmodell" och avsnittet antennen. Andra faktorer som kan påverka radioutbredningen är förluster i basstationenssystemet, topologin hos området mellan sändare och mottagare samt väderberoende utbredningsegenskaper. Genom att hitta de tänkbara faktorer som påverkar signalutbredningen kan en täckningsmodell förutses. Det är förluster som finns i basstationen, radiolänken samt förluster vid mottagarantennen.

Nikolai Tesla's revolutionary experiments demonstrated the possible benefits of transmitting power wirelessly as early as 1891. Applications for the military, consumers, emergency personnel, remote sensors, and others use Tesla’s discovery of wireless power. Wireless power transmission (WPT) has the potential to be a common source of consumable energy, but it will only receive serious consideration if the transmit and receive systems are extremely efficient and capable of delivering usable amounts of power. Research has been conducted to improve the efficiency and performance of nearly every aspect of WPT systems, but the relatively new field of metamaterials (MTMs) has yet to play a dominate role in improving system performance. A gradient index (GRIN) MTM lens was designed using Ansoft’s High Frequency Structure Simulator (HFSS) to improve antenna gain and thereby increase WPT system performance. A simple WPT demonstration system using microstrip patch antennas (MPAs) confirmed the benefits of the GRIN MTM lens. The WPT demonstration system, MPAs, and GRIN MTM lens were constructed and experimentally tested near 2.45 GHz. The theoretical and experimental gain improvement of the MPA due to the GRIN MTM lens is 5.91 dB and 7.06 dB, respectively.

L’évolution constante des technologies sans fil telles que le Wi-Fi, les normes de réseaux mobiles ou d’objets connectés, a donné naissance à de nouvelles applications et usages. Les possibilités offertes par cette multitude d’alternatives sont exploitées par les réseaux sans fil hétérogènes qui, en combinant au sein d’un réseau unique plusieurs technologies, permettent aux utilisateurs d’accéder à des services complémentaires de façon transparente. Cependant, pour bénéficier pleinement de ces avantages, plusieurs défis techniques sont à relever. L’un d’eux est relatif au déploiement de ces réseaux multi- technologies. En pratique, cette tâche s’appuie sur des règles et outils d’ingénierie afin de réaliser une planification optimale. Dans ce contexte, un objectif de la thèse a été d’établir des modèles sur lesquels peuvent se baser les outils d’ingénierie radio afin d’optimiser le déploiement de réseau locaux sans fil multi- technologies.Il s’agit principalement de calibrer des modèles de propagation pour l’estimation de couverture radio en environnement indoor résidentiel entre 800 MHz et 60 GHz; d’établir un modèle de débit pour l’estimation de capacité Wi-Fi en fonction du trafic montant et descendant; et de concevoir un modèle de résolution multi-objectif pour optimiser le positionnement de points d’accès opérant à 5 et 60 GHz. En complément, cette thèse a également proposé des recommandations pratiques visant à placer au mieux les points d’accès en phase de déploiement. Cela s’est fait par le biais d’études de sensibilité de couverture à divers facteurs, tels que l’environnement immédiat de l’émetteur ou encore la présence de personnes faisant obstruction
The constant evolution of wireless technologies such as Wi-Fi, mobile networks standards or IoT, has given rise to new applications and usages. The possibilities offered by this multitude of alternatives are exploited by heterogeneous wireless networks which, by combining within a single network several technologies, provide the users with a seamless access to complementary services. However, to take full advantage of these benefits, there are several technical issues to address. One of them is related to the deployment of these multi-technology networks. In practice, this task relies, most of the time, on radio network design software to achieve optimal planning. In such context, the main objective of this thesis is to establish models which can be used by radio network planning tools in order to the deployment of multi-technology wireless local area networks. This task has involved calibrating propagation models for radio coverage estimation, in residential indoor environments from 800 MHz to 60 GHz; developing a throughput model for Wi-Fi capacity estimation based on uplink and downlink traffic; and establishing a multi- objective resolution model to optimize the positioning of access points operating at 5 and 60 GHz. Moreover, this thesis also proposes practical recommendations for a better positioning of access points during deployment phases. This task has been achieved through coverage sensitivity studies to various factors, such as the transmitter surroundings or the presence of obstructing people

Les systèmes de localisations existants présentent des insuffisances au niveau desapplications en environnement indoor. Ces insuffisances se traduisent soit par la non-disponibilité des signaux (le GPS) dans ce type d'environnement, soit par leur manque de précision quand ils sont prévus à cet effet. Ces limites ont motivé la recherche de nouvelles techniques. Les transmissions Ultra-Large Bande (ULB) de par leur singularité en matière de précision et de faible puissance d'émission, s'avèrent être la meilleure réponse à la problématique ci-dessus. Nous avons donc choisi cette technique pour mettre au point un procédé de localisation endogène permettant d'assurer, avec précision, la continuité des services de localisation dans les environnements indoor. Ce procédé s'appuie sur la localisation en trois dimensions (3-D). Il utilise la technique temporelle de différenciation du temps d'arrivée (TDOA). Cette technique permet de mieux tirer profit de la bonne résolution temporelle de l'ULB et de pallier au problème de synchronisation entre l'émetteur et le récepteur. Deux techniques de transmission ULB ont été étudiées : la technique d'accès multiples par séquence directe (DS-CDMA) et la technique d'accès multiples par sauts temporels (TH-CDMA). Une autre étape importante de notre étude a été de développer un algorithme non-itératif de localisation en 3-D pour réduire le temps de calcul. En effet, l'utilisation d'un algorithme non-itératif permet d'optimiser les performances du système en termes de temps de calcul voire de coûts de consommation énergétique. Après l'étude théorique des différents blocs du système, le système a été tout d'abord simulé dans le canal Gaussien (AWGN) et les canaux IEEE.802.15.4a indoor. Il a été ensuite testé dans différents environnements réels de types laboratoires. Les résultats obtenus démontrent que l'utilisation des techniques de transmission basées sur la technologie radio impulsionnelle ULB permet d'obtenir un système de localisation en 3-D avec une précision centimétrique pour les applications indoor.

Nodes in a cognitive radio mesh network may select from a set of available channels to use provided they do not interfere with primary users. This ability can improve overall network performance but introduces the question of how best to use these channels. This project addresses the following specific problem: given a routing path P, choose which channels each link in P should use and their transmission schedule so as to maximize the end-to-end data flow rate (throughput) supported by the entire path. This problem is relevant to applications such as streaming video or data where a connection may be long lasting and require a high constant throughput. The problem is hard due to the presence of both intra-flow and inter-flow interference. We have developed a new constant-factor approximation algorithm for this problem. If certain conditions on the path are met, the performance guarantee is 1/4 of optimal. It has been shown by simulation results that the end-to-end throughput given by the proposed algorithm is often within 90% or better of optimal.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Owing to the huge range of application scenarios for wireless networks, new prospects for the current and future applications of the Internet, making new communication paradigms such as the Internet of Things (IoT) and 5G networks. Two important networks are included in this scenery: Wireless Sensor Networks (WSN) provide key devices for developing the IoT communication paradigm, such as the sensors used for collecting different kind of information, and the Wireless Mesh Network (WMN) that enable interoperability between heterogeneous network, covering large areas with at am low cost.Eeach one these networks have specific characteristics, for example, the WSN has serious restrictions (e.g. power consumption, low speed wireless links, interference) while the WMN offers high data rates through multiple radios and channels. In this context, it is necessary to find solutions that can ensure more efficient communication system based on the optimized utilization of the network resources. So it was created a multi-objective routing algorithm, called Routing-Aware of path Length, Link quality, and traffic Load (RALL). This seeks to strike a balance between three objectives: to minimize the network bottlenecks, to reduce path length, and to avoid links with low quality, for resolution the routing problem for WSN, Then the RALL approach was adapted to match the specialty of the WMN, entitled Routing Aware of path Length, Link quality, and traffic Load Weighted (RALLW). The results indicate that combining multiple objectives when performing routing can benefit networks performance. The RALL and RALLW results in a good performance with regard to the delivery rate, throughput, delay, and power consumption when compared to other approaches, however the RALLW approach did not significant differences when compared to the RALL.
A utilização das redes sem fio em diversas aplicações está criando uma nova perspectiva de utilidade para a Internet atual fazendo com que novos paradigmas de comunicação sejam desenvolvidos, como a Internet das coisas (IoT) e redes 5G. Dois tipos de rede sem fio se destacam nesses novos cenários, a Rede de Sensores Sem Fio (RSSF) que fornece dispositivos fundamentais para a implementação dos ambientes inteligentes e da IoT, e a Rede em Malha Sem Fio (RMSF) que permite a interoperabilidade entre os tipos de redes, cobrindo grandes áreas e com um custo relativamente baixo. Essas redes possuem peculiaridade específicas, por exemplo a RSSF possui fortes restrições de consumo energético e capacidade de transmissão, já a RMSF é uma rede com maior capacidade de transmissão e maior alcance. Nesse contexto, é necessário desenvolver soluções que tornam a rede eficiente através da otimização dos seus recursos. Inicialmente foi desenvolvida a abordagem Routing Aware of path Length, Link quality, and traffic Load (RALL) para realizar o roteamento multiobjetivo em RSSF, em seguida, realizamos uma adaptação dessa abordagem para refletir as especificidades dos cenários de uma RMSF, essa adaptação foi intitulada de Routing Aware of path Length, Link quality, and traffic Load Weigthed (RALLW). Em ambas abordagens o problema de roteamento multiobjetivo é composto por três objetivos (quantidade de saltos, quantidade de enlaces com baixa qualidade e balanceamento da rede), comuns a RSSF e a RMSF, apesar de existirem diferenças significativas entre elas ao modelar os objetivos. Os resultados indicam que a combinação de múltiplos objetivos ao realizar o roteamento pode beneficiar o desempenho da rede. As abordagens RALL e RALLW resultaram em bons resultados quando comparados com outras abordagens, em relação à taxa de entrega, vazão, atraso e consumo de energia, entretanto, a abordagem RALLW não mostrou diferenças significativas quando comparada a abordagem RALL.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The present study was developted with the main object to evaluate the invasive ability, persitence and behavior of Salmonella Schwarzengrund in embryos and broiler chicks with one day of birth. Initially, 260 fertile eggs from broiler chicken were incubated e randomly distributed onto three different incubators. In the nineteenth day post incubation, the eggs were submited to candling and at the time 40 eggs were eliminated. The remaining eggs were distrubuted and 50 eggs were inoculated with 0,2 mL of sterile buffered saline 0,85% trough the air chamber and 50 eggs were inoculated with 1,5 x 104 UFC/0,2mL of Salmonella Schwarzengrund trough the air chamber, 100 were incubated without treatment. After the eclosion, the one day-old chicks were equally distributed in four treatments, discriminated well below: T1 – feed control – 30 chicks from incubator number 1, and received 0,1 mL of sterile buffered saline 0,85% per g of feed; T2 – feed inoculated - 30 chicks from incubator number 1, received feed with 5,3 x 10 4/0,1mL/g of Salmonella Schwarzengrund in buffered saline 0,85% per g de of feed until the seventh day-old; T3- inoculated control trough air chamber -30 chicks from inoculated embryos with 0,2 mL of sterile buffered saline 0,85% trough the air chamber; T4- inoculated trough air chamber - 30 chicks from inoculated embryos with 1,5 x 104 UFC/0,2mL de Salmonella Schwarzengrund in the air chamber. Salmonella Schwarzengrund was able to cause embryo mortality, enteric colonization, negatively influenced the weight gain, septicemic and enteric signs, with no correlation between the inoculation way. The bidrs shown clinical signs seen as feces adered to cloaca,diarrhea, prostration, decreased appetite, growth retardation and sleepness. The contamination determined higher weight and length of intestinal and liver with 25 days.Therefore is conclude that Salmonella Schwarzengrund is able to invade and persist in organs of inoculated air chamber embryo and one day old chicks contaminated feed.
O presente estudo foi desenvolvido com o objetivo de investigar a capacidade invasiva e a persistência da Salmonella Schwarzengrund em embriões e pintos de corte de um dia. Foram incubados, inteiramente ao acaso, 260 ovos férteis de frangos de corte em três incubadoras distintas. Com 19 dias de incubação fez-se a ovoscopia e, 40 ovos foram eliminados. O restante dos ovos foram distribuídos da seguinte maneira: 50 ovos foram inoculados com 0,2 mL de solução salina tamponada esterilizada 0,85% via câmara de ar, 50 ovos foram inoculados com 1,5 x 104 UFC/0,2mL de Salmonella Schwarzengrund na câmara de ar e 100 foram incubados sem nenhum inóculo, para posterior inoculação nos pintos de um dia. Após a eclosão, os pintos de um dia foram distribuídos igualmente em quatro tratamentos, assim discriminados: T1 - controle da ração - constituído de 30 pintos livres de Salmonella, e receberam ração inoculada com 0,1 mL solução salina tamponada a 0, 85% por g de ração; T2 – inoculado ração - constituído de 30 pintos oriundos da incubadora 1, receberam ração com 5,3 x 10 4/0,1mL/g de Salmonella Schwarzengrund em solução salina tamponada 0, 85% por grama de ração até o sétimo dia de vida; T3- pintos controle oriundos da inoculação via câmara de ar ainda embriões -30 pintos oriundos de embriões inoculados com 0,2 mL de solução salina 0,85% tamponada, esterilizada na câmara de ar; T4- pintos contaminados câmara de ar ainda embriões- 30 pintos oriundos de embriões inoculados com 1,5 x 104 UFC/0,2mL de Salmonella Schwarzengrund na câmara de ar. Salmonella Schwarzengrund foi capaz de causar a mortalidade embrionária, colonizar o intestino, influenciar negativamente o ganho de peso, determinar quadro septicêmico e entérico independente da via de inoculação. As aves apresentaram sinais clínicos como fezes aderidas à cloaca, diarreia, prostração, apetite diminuído, retardo no crescimento e sonolência. A contaminação determinou maior peso e comprimento do intestino e fígado com 25 dias. Conclui-se que Salmonella Schwarzengrund possui a capacidade invasiva e de persistência em aves oriundas da inoculação da câmera de ar e em pintos de um dia por ração contaminada.

Optical packet switching (OPS) is one of the more promising solutions for meeting the diverse needs of broadband networking applications of the future. By virtue of its small data traffic granularity as well as its nanoseconds switching speed, OPS can be used to provide connection-oriented or connectionless services for different groups of users with very different networking requirements. The optical buffer and the switch fabric are two of the most important components in an OPS router. In this research, novel designs for the optical buffer and switch fabric are proposed and experimentally demonstrated. In particular, an optical buffer that is based on a folded-path delay-line tree architecture will be discussed. This buffer is the most compact non-recirculating optical delay line buffer to date, and it uses an array of high-speed ON-OFF optical reflectors to dynamically reconfigure its delay within several nanoseconds. A major part of this research is devoted to the design and performance optimization of these high-speed reflectors. Simulations and measurements are used to compare different reflector designs as well as to determine their optimal operating conditions. Another important component in the OPS router is the switch fabric, and it is used to perform space switching for the optical packets. Optical switch fabrics are used to overcome the limitations imposed by conventional electronic switch fabrics: high power consumption and dependency on the modulation format and bit-rate of the signals. Currently, only those fabrics that are based on the broadcast-and-select architecture can provide truly non-blocking multicast services to all input ports. However, a major drawback of these fabrics is that they are implemented using a large number of optical gates based on semiconductor optical amplifiers (SOA). This results in large component count and high energy consumption. In this research, a new multicast-capable switch fabric which does not require any SOA gates is proposed. This fabric relies on a passive all-optical gate that is based on the Four-wave mixing (FWM) wavelength conversion process in a highly-nonlinear fiber. By using this new switch architecture, a significant reduction in component count can be expected.

This dissertation plots the myriad connections between Southern France and the multicultural Iberian Peninsula during the eleventh to thirteenth centuries, the people to people contacts which effectively connected Southern France with the Islamic world. The example of courtly culture demonstrates the pattern of informal cultural absorption that resulted from these contacts, as aspects of Andalusian courtly culture were adopted and adapted to Occitan court settings, fitting within a pattern of Pan-Mediterranean courtly culture. This courtly culture absorption was a result of the long-term and broad-based people to people connections and acculturation between Occcitania and the multi-cultural Iberian world. First, using charter evidence, the interaction between the two Iberias, one Islamic and Arabic, the other Christian and Latin, is traced through the people, institutions, and infrastructure that passed from one Iberia to the other. By the early twelfth century, major Islamic medinas with large Arabic-speaking populations had been incorporated into the Christian kingdoms. In the close confines of these medina/urbs,day-to-day life brought different religious and ethnic groups together. Properties bought, sold, and exchanged involved people of different faiths and backgrounds. Women, like the nuns at Sigena outside Huesca, or the Islamic and Jewish brides of French settlers, often had a unique role to play intercultural interaction. On the other side of the Pyrenees, several types of cross border relationships occurred: family ties through marriages and alliances, institutional ties through monastic and church affiliation, and travel ties through legates, bishop and abbot appointments, and pilgrimage. Roads to the Spanish shrine of Saint-James of Compostela blanketed southern France, bringing pilgrims to stops along the way at Sainte-Foy de Conques, Saint-Sernin de Toulouse, the Cathedral of Bayonne, and La-Sauve-Majeure. The archival and published charters of these towns and monasteries of Occitania show how these relationships created the means for acculturation, interaction and communication between Occitan and Iberia. As a consequence of these trans-Pyrenean relationships, people with Iberian, Arabic-language origins, interacted with Occitan peoples bringing greater awareness of the intellectual and material culture of Iberia with its cosmopolitan sensibilities. My dissertation demonstrates the cultural reverberations resulting from cross-cultural contact. While most agree that there was some Arabic influence on medieval Europe, it is generally limited to instances where there is a clear paper trail, such as translated scientific, medical and philosophical texts. There is still significant scholarly resistance to the idea of a more generalized cultural influence due to the theory that connections between Arabic-speaking populations and Europeans were limited and inhibited by language and cultural barriers. we accept that people absorb cultural influence in many ways, including orally, visually, and in what are termed 'low culture' registers, often imperfectly understanding what they scavenge, contact and communication become key to understanding acculaturation. My methodology, using names, ethnicity, and information on captured in charters to identify cross-cultural interaction and evidence of cultural influence, focuses on the pathway from the Arabophone world to Occitania. Since charter evidence shows that cross-cultural interaction was long-term, rapidly increasing over the eleventh and twelfth centuries, and broad-based, involving many areas of Occitania and many types of people. acculturation would be the expected outcome.

Astrocytes are the most abundant non-neuronal cells in vertebrate brains. Although Drosophila melanogaster has fewer astrocytic cells relative to neuronal and other glial cell populations, they, like vertebrate astrocytes, are located in synaptic regions, organized into exclusive, minimally-overlapping domains, and play developmental roles in synaptogenesis. But, do Drosophila astrocytes have parallel roles in the regulation of synaptic signaling? Preliminary electron microscopic (EM) data indicates that astrocytic processes are located at a greater distance, on average, from Drosophila synapses than they are from vertebrate synapses, thus raising questions about their capacity to alter synaptic signals. Do astrocytic cells and processes occupy stereotyped synaptic regions across repeating segmental structures and across individuals? In the studies presented here, we have addressed these questions directly in the ventral nerve cord (VNC) of the third-instar larva. We collected the first whole-cell patch-clamp recordings from Drosophila astrocytes. These indicate that intrinsic membrane properties, such as low membrane resistance, high capacitance, a hyperpolarized resting potential relative to neurons, a passive current-voltage relationship, coupling to other astrocytic cells, and an absence of voltage-gated currents, are shared between astrocytes of highly divergent species. Next, we optogenetically activated of a group of glutamatergic pre-motor neurons and showed that astrocytes respond with a glutamate transporter current that is mediated by Eaat1, and that acute, pharmacological and chronic, genetic blockades of this transporter have subsequent effects on the decay of post-synaptic motor neuron currents. Then, we used three-dimensional EM to locate the pre-motor glutamatergic neurons that were activated in the physiological study and measured the distance from each presynaptic site to the nearest astrocytic process. We found that these distances vary 100-fold even along a single neurite and that these structures are rarely in direct contact, but that no synapse is positioned greater than one micron from an astrocytic process. Thus, it is in this anatomical configuration that the regulation of post-synaptic currents by Eaat1 occurs. Finally, we generated a library of single, fluorescently-labeled astrocytes that were co-labeled with fiduciary landmarks, and used this library to compare the placement of astrocyte cell bodies and arbors across VNC segments and individuals. We found substantial variation in the gross shape, size, and territory covered by astrocytes, and conclude that their neuropil domains are not reliably stereotyped. Given the consistent placement of neuronal connectome elements, this indicates that signals of a specific synapse are not regulated by a designated astrocyte. Together, these findings reveal new functional parallels between Drosophila and vertebrate astrocytes. These findings argue for the relevance and applicability of mechanistic discovery in Drosophila astrocytes, and set the stage for further inquiry into the genetic determinants of astrocyte morphology and physiology.

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CNPQ
Testes não treponêmicos, como o “Veneral Disease Research Laboratory”(VDRL), podem apresentar muitos falso negativos e baixa reprodutibilidade. Em locais de recursos limitados também não permitem diagnóstico e tratamento precoces. Nestes, os testes rápidos (TRs) apresentaram maior número de gestantes diagnosticadas e tratadas e maior redução de sífilis congênita (quando utilizados na primeira consulta de pré-natal com simultâneo tratamento da gestante). Este estudo validou o TR DPP® Sífilis e comparou a sua performance com a do VDRL em pacientes obstétricas internadas em maternidades públicas e filantrópicas do Recife-PE, em relação a um padrão de referência (PR) da pesquisa para diagnóstico da sífilis. Metodologia: a seleção foi pelo VDRL realizado nas maternidades. Ingressaram todas as pacientes internadas com VDRL (+) e uma a duas internadas com VDRL (-) imediatamente após. Todas as participantes realizaram pela pesquisa o DPP e os testes do PR: imunoenzimático (ELISA) + hemaglutinação (TPHA) e absorção de anticorpos treponêmicos fluorescente (FTA-ABS) quando ELISA e TPHA discordantes. Resultados: Foram analisadas 1228 pacientes. O DPP® apresentou sensibilidade de 92,9% (IC 95% 90,2-95), especificidade de 99,2% (98,3-99,6), razão de verossimilhança (+) de 120 (86,6-166,5), (-) de 0,07 (0,07-0,08) e “odds ratio” de 1686 (699,4-4065). Os valores preditivos (+) e (-) corrigidos pela prevalência real de sífilis gestacional da população foram 73,9% (70,1-77,3) e 99,8% (99,8-99,9). Porém, a sensibilidade do TR foi significantemente inferior nas pacientes PR (+) / VDRL (-) (39%: 25,66-54,3) que nas com PR (+) / VDRL (+) < 1:8 (97,1%: 93,5-98,8) e ≥ 1:8 (99,1%: 96,7-99,7). Na comparação com o VDRL, O DPP® apresentou maior razão de verossimilhança (+) e “odds ratio” nas duas maternidades em que foi possível a comparação, melhor especificidade em todas e melhor sensibilidade e razão de verossimilhança (-) em cinco, no geral sem significância estatística. O VDRL apresentou maior variação de sensibilidade e especificidade nas maternidades, no geral com significância estatística. Foi observado queda na sensibilidade do TR nas pacientes PR (+) / VDRL (-) nas maternidades em que os cálculos foram possíveis, porém com pequena casuística impedindo extrapolações conclusivas. Conclusão: o DPP® Sífilis apresentou boa performance, porém com sensibilidade diretamente relacionada à prevalência de PR (+) /VDRL (+) (sífilis ativa). Portanto, a seleção nas maternidades pelo VDRL superestimou a real prevalência de sífilis da população estudada, superestimando também a sensibilidade do DPP®, ficando a real entre 39 e 92,9%. Em comparação com o VDRL, o DPP® apresentou melhor performance e menor variação de sensibilidade e especificidade, no geral sem significância estatística. A execução do VDRL pelas maternidades e do DPP® pela pesquisa pode ter superestimado a performance do TR. A baixa sensibilidade do TR em populações com baixa prevalência de sífilis ativa não inviabiliza (a princípio) o seu uso, uma vez que são indicados em áreas de recursos limitados, com grande prevalência de sífilis ativa. Os ganhos em diagnóstico e tratamento oportunos de gestantes e redução de sífilis congênita ocorrerão se uso compulsório do TR com tratamento da gestante na primeira consulta de pré-natal.
Non-treponemal tests (NTTs), like the Veneral Disease Research Laboratory (VDRL), can present many false (-) and low reproducibility. In limited resources, it’s also unable to allow early diagnosis and treatment. In this places, the rapid tests (RTs) present the highest number of pregnant women diagnosed and treated and the greater reduction of congenital syphilis (when done at the first prenatal visit with simultaneous pregnant women treatment). This study validated the TR DPP® Sífilis and compared his performance with the VDRL in obstetric patients hospitalized in public and philanthropic maternity hospitals in Recife-PE, in relation to the reference standard (RS) of the research syphilis diagnosis. Methodology: the selection was done by VDRL performed in the maternity hospitals. All hospitalized patients with VDRL (+) and one to two hospitalized with VDRL (-) admitted immediately after were ingressed. All participants performed by the research the DPP and the tests from the RS: immunoenzymatic (ELISA) + haemagglutination (TPHA) and fluorescent treponemal antibody absorption (FTA-ABS) when TPHA and ELISA were discordants. Results: 1228 patients were analyzed. The DPP® showed sensitivity of 92.9% (95% CI 90.2-95), specificity of 99.2% (98.3-99.6), likelihood (+) ratio of 120 (86,6-166.5), likehood (-) ratio of 0.07 (0.07-0.08) and odds ratio of 1686 (699.4-4065). Predictive values (+) and (-) corrected by the real prevalence of gestational syphilis study population were 73.9% (70.1-77.3) and 99.8% (99.8-99.9). However, the sensitivity of RT was significantly lower in RS (+) / VDRL (-) patients (39%: 25.66-54.3) than RS (+) / VDRL (+) < 1:8 (97.1%: 93.5 -98.8) and ≥ 1:8 (99.1%: 96.7-99.7) patients. In the comparison with the VDRL, DPP ® showed a greater likelihood ratio (+) and odds ratio in the two maternity hospitals where the comparison was possible, better specificity in all of them and better sensitivity and likelihood (-) ratio in five of them, generally without statistical significance. The VDRL present greater sensitivity and specificity variation, generally with statistical significance. There was also a decrease in the sensitivity of RT in RS (+) / VDRL (-) patients in the maternity hospitals where the calculations were possible, but the small casuistry preventing conclusive extrapolations. Conclusion: The DPP ® Sifilis showed good performance, but sensitivity directly related to the prevalence of RS (+) with VDRL (+) (active syphilis). Therefore, the selection by VDRL overestimated the real syphilis prevalence of the study population, overestimating the sensitivity of 92.9% of the DPP®, being the real test sensitivity between 39 and 92.9%. Compared to VDRL, the RT showed better performance and lower sensitivity and specificity variation, generally without significance. The execution of VDRL by maternity hospitals and DPP® by research may have overestimated the RT performance. The low RT sensitivity in low prevalence of active syphilis populations doesn’t make the test unfeasible (at first), since it’s indicated in limited resources, with high prevalence of active syphilis. The gains in the timely diagnosis and treatment of pregnant women with reduction of congenital syphilis will occur if the RT is used compulsorily, with treatment during the first prenatal visit.

Die vorliegende Dissertation verfolgt das Ziel, die von Nervenzellen maximal erreichte Signalrate zu bestimmen. Außerdem werden die bislang weitgehend unbekannten Anpassungen einer Synapse an die Anforderungen hochfrequenter Signalübertragung untersucht. Die maximale Übertragungsrate spielt im zentralen Nervensystem eine wichtige Rolle für die Codierung und Verarbeitung von Informationen. Neben den Grundlagen der synaptischen Übertragung und der neuronalen Informationscodierung werden in der Einleitung die anatomischen Gegebenheiten der Kleinhirnrinde und der Moosfaser-Körnerzell-Synapse vorgestellt. Präsynaptische patch-clamp-Messungen von Moosfaserboutons und die erstmals durchgeführten Messungen von präsynaptischen Boutons und postsynaptischen Körnerzellen („Paarableitungen“) werden erläutert. Mit Hilfe dieser Methoden wird gezeigt, dass die Kommunikation zwischen Nervenzellen mit Raten von bis zu einem Kilohertz stattfinden kann. Hierbei ist die präsynaptische Freisetzung von Botenstoffen schneller und effizienter als bisher bekannt. Ein einzigartiges Repertoire präsynaptischer Mechanismen wird charakterisiert und bildet die Grundlage der nachgewiesenen, hochfrequenten Informationsübertragung.

Les ganglions de la base (GB) sont un ensemble de noyaux sous-corticaux impliqués dans les fonctions motrices, mnésiques et cognitives. Le globus pallidus externe (GPe) est un noyau GABAergique, qui tient la place de structure relais entre le striatum et le noyau sous-thalamique au sein du réseau des GB. Les changements de mode et de fréquence de décharge des neurones du GPe sont connus pour être les signatures électro-physiologiques des maladies de Parkinson (MP) et de Huntington (MH). Dans la MP, où les concentrations de GABA extracellulaires sont anormalement élevées dans le GPe, il est admis que la voie striato-pallidale (STR-GPe) est hyperactive, ce qui contribue à l’hypoactivité des neurones pallidaux. A l’inverse dans la MH, il est admis que l’hyperactivité des neurones du GPe est due à la dégénérescence de la voie STR-GPe levant la principale influence inhibitrice du GPe. Cependant, les mécanismes moléculaires impliqués dans ces changements d’activité pallidale sont encore peu connus. Nous avons donc entrepris des expériences de biologie moléculaire, d’immunohistochimie et d’électrophysiologie sur tranches, afin de mieux caractériser l’origine des modifications de transmission GABAergique conduisant aux changements d’activité électro-physiologique des neurones du GPe dans ces deux pathologies à l’aide de modèles animaux. Mes principaux résultats montrent l’apparition d’une inhibition tonique dans les neurones du GPe due à un déficit de recapture du GABA dans la MP et une réduction précoce de la transmission synaptique GABAergique dans la MH. Ces résultats suggèrent que les altérations de la transmission GABAergique contribuent à la physiopathologie de la MP et la MH
The basal ganglia (BG) are a group of sub-cortical nuclei involved in motor, memory and cognitive functions. In the BG, the GABAergic external globus pallidus (GPe) holds a position of relay nucleus between the striatum (STR) and the sub thalamic nucleus within the indirect pathway of the BG. Modifications of rate and pattern of activity of this nucleus are known to be the electrophysiological signatures of Parkinson’s (PD) and Huntington’s diseases (HD). In PD, hyperactivity of the striato-pallidal (STR-GPe) pathway is thought to be responsible for the increase of the extracellular GABAergic concentrations in the GPe and participate to the hypoactivity of pallidal neurons observed in experimental Parkinsonism. In contrast, during HD, it is recognized that the hyperactivity of GPe neurons is due to the degeneration of striato-pallidal neurons and thus to the reduction of the main source of pallidal GABAergic inhibition. However, the molecular mechanisms involved in these modifications of pallidal activity are not well characterized. Therefore, using PD and HD animal models, the 6-OHDA rodents and the R6-1 transgenic mice respectively, we have performed molecular biology, immunohistochemistry and electrophysiological in vitro experiments in order to better understand the origin of GABAergic transmission alterations leading to changes in electrophysiological activity of GPe neurons into these two pathologies. My main results show the apparition of a tonic GABAergic inhibition due to a deficit of GABA uptake in PD and a early stage reduction of GABAergic synaptic transmission in HD. Altogether, these results suggest that alterations of GABAergic transmission contribute to the pathophysiology of PD and HD

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007.
Bruce R. Ellingwood, Committee Chair ; Abdul-Hamid Zureick, Committee Member ; James I. Craig, Committee Member ; Reginald DesRoches, Committee Member ; Kenneth M. Will, Committee Member.

Les terminaux de communications sans fil évoluent en des terminaux supportant plusieurs standards. L'un des challenges est d'utiliser le meilleur standard au bon moment. L'émetteur d'une radio cognitive agile en fréquence se doit d'être reconfigurable afin de transmettre l'information dans des bandes fréquentielles sous utilisées et d'avoir recours au standard offrant la meilleure qualité de communication. L'élément le plus critique dans un émetteur est l'étage de puissance et sa connexion avec l'antenne. Les principaux problèmes devant être pris en compte par l'amplificateur de puissance (PA) sont: la linéarité, la puissance délivrée à l'antenne et le rendement. Un émetteur numérique basé sur un amplificateur de puissance commandé numériquement (DPA) est étudié et un prototype a été implémenté afin de démontrer la faisabilité du concept. Le DPA est principalement utilisé dans les architectures polaires plutôt que cartésienne. L'architecture proposée est basée sur une approche à multiple voies combinée à une conversion de fréquences. La diversité introduite sur les fréquences d'échantillonnage permet de contrôler le niveau d'impuretés spectrales émisses. Celles-ci proviennent de la conversion directe numérique vers RF. Cette conversion est réalisée par le DPA sans le recours à des filtres passifs. Les émetteurs implémentés en technologies CMOS avancées ont souvent recours à une architecture à multiple voies. L'approche présentée dans ce manuscrit tire avantage de cette structure parallèle afin de générer des signaux portant la même information mais échantillonnés à des fréquences différentes. Le standard LTE a été pris comme standard de référence, et un modulateur d'enveloppe a été conçu en technologie CMOS 65nm. Les conversions de fréquences bande de base et la logique de contrôle on été implémentées sur FPGA. La recombinaison des voies est réalisée à l'aide de composants discrets. Le prototype de modulateur d'enveloppe numérique réalisé, démontre le principe d'atténuation d'images pouvant atteindre 6dB dans le cas d'un système à deux voies. Les DPAs supportent quatre fréquences d'échantillonnage {100 MS/s; 133 MS/s; 152 MS/s; 160MS/s}. L'amplificateur délivre jusqu'à 16.7dBm sur la bande 0.9 à 1.9 GHz et assure un PAE de 12.4% avec un EVMrms de -28dB. Le prototype a été testé avec des signaux LTE de 10 MHz et 802.11g de 20 MHz. La surface totale occupée par le circuit est de 1.04mm² tandis que la surface dédié aux DPAs et logique de contrôle occupent seulement 0.25mm²
Wireless communication terminals are evolving towards multi-standard terminals. One of the challenges is to use the best standard available at the right moment. The transmit part of a frequency agile cognitive radio must be highly reconfigurable in order to transmit information in an unused spectral zone and to use the suitable standard to obtain the optimum communication. The most critical element in a transmitter is the power amplifier and its interface with the antenna. Key problems that need to be addressed by the Power Amplifier (PA) are the linearity, ability to deliver power to the antenna and efficiency. In this work a digital transmitter based on a digitally controlled power amplifier (DPA) is investigated, and a prototype has been implemented to prove the feasibility of the concept. The DPA is mostly used in polar transmitters rather than Cartesian ones. The proposed architecture is based on multi-path approach with different sample rate conversions. This diversity of sample rates helps to manage the spurious emissions due to the direct digital to RF conversion performed by the DPA without the need of passive filters. The transmitters implemented in advanced CMOS process are commonly based on multiple paths architecture. The approach proposed in this work takes advantage of this parallel structure to generate several signals with the same information but with different sample rates. The LTE standard has been taken as the standard example, and a 2-path digital envelope modulator has been designed in a 65nm CMOS technology. The baseband sample rate conversions and control logic have been implemented on FPGA. The path recombination is performed with o_-board components. The fabricated prototype digital envelope modulator IC demonstrates the image attenuation principle with up to 6dB attenuation. The DPAs support four sample rates {100 MS/s; 133 MS/s; 152 MS/s; 160MS/s}. The amplifier delivers up to 16.7dBm over a 0.9 - 1.9 GHz band while providing 12.4% PAE and a -28dB EVMrms.The prototype was tested with a 10 MHz LTE and a 20 MHz 802.11g standards. The total circuit occupies 1.04mm² and the area dedicated to the DPA and control logic only occupies 0.25mm²

La substance noire réticulée (SNr) est la principale structure de sortie des ganglions de la base (BG), un réseau sous-cortical contrôlant l'élaboration des programmes moteurs ainsi que des fonctions d'apprentissage cognitives et associatives. L'identification de types de cellules distincts dans le BG a joué un rôle clé pour comprendre les propriétés et les fonctions de ce circuit. Des études récentes suggèrent que la SNr est composé de plusieurs types de cellules mais jusqu'à présent cette diversité neuronale n'a jamais été prise en compte concernant le fonctionnement normal et pathologique de ce noyau, notamment dans la maladie de Parkinson (MP). En combinant des approches immunohistochimiques et électrophysiologiques chez la lignée de souris PVCre::Ai9T, nous avons démontré que les neurones de la SNr exprimant la protéine parvalbumine (PV+) ont des propriétés anatomiques et électrophysiologiques différentes de celles des neurones ne l’exprimant pas (PV-). Notre analyse anatomique montre que les neurones PV+ et PV- sont présents à proportion égale dans la SNr, mais avec une distribution distincte, les neurones PV+ étant enrichis dans la partie latérale de la SNr alors que les neurones PV- sont présents dans la partie médiale de ce noyau. Nos enregistrements électrophysiologiques in vitro ont révélé que les neurones PV+ ont une activité électrique plus élevée que les cellules PV-. De plus, nos données indiquent que la perte de dopamine (DA) et le traitement à la L-DOPA induisent une réduction profonde de l'excitabilité des neurones PV+ de la SNr dans un modèle murin de MP (la souris 6-OHDA) sans modifier l'activité des neurones PV-.Il est bien connu que l'activité des neurones de la SNr est contrôlée par les afférences GABAergiques des neurones striataux (STR-SNr) de la voie directe (dSPN) et du globus pallidus (GP-SNr). Nous avons effectué une manipulation optogénétique de ces deux voies inhibitrices et montré que ces deux populations neuronales sont innervées de manière équivalente par le STR et le GP. Nos résultats ont également révélé que l'inhibition striatale était plus efficace que l’inhibition pallidale pour réduire l'activité des deux sous-types de neurones SNr. De plus, nous avons observé que les2synapses STR-SNr et GP-SNr affichent la même plasticité à court terme sur les neurones PV+ et PV- de la SNr. Enfin, nous avons montré que la transmission GABAergique est affectée de manière différentielle sur les cellules PV+ et PV- suite à une déplétion DAergique. D'une part, les neurones PV+ sont plus sensibles à l'inhibition striatale que les cellules PV- après une déplétion en DA. D’autre part, l’inhibition pallidale est réduite sur les neurones PV+ et augmentée sur les PV- après la perte de DA, suggérant un déséquilibre de l'inhibition pallidale entre ces deux populations SNr.Il est aussi connu que les niveaux extracellulaires de GABA sont élevés dans la SNr chez les modèles rongeurs de MP, ce qui suggère que les neurones de la SNr pourraient être inhibés de manière permanente par une inhibition dite tonique. Ainsi, Nous avons caractérisé la transmission extrasynaptique GABAergique dans la SNr des souris témoins et 6-OHDA. Nos enregistrements de patch-clamp ont révélés que les neurones PV- présentent une inhibition tonique plus importante que les cellules PV+ chez les souris témoins. La présence et l'implication des sous-unités δ et α5 dans les récepteurs GABAA extrasynaptiques ont également été étudiées, révélant une présence et un effet majeurs des sous-unités α5 sur les neurones PV. Cependant, contrairement à ce qui était attendu, la déplétion chronique en DA ne provoque aucun changement de l'inhibition tonique ni dans les cellules PV+ ni dans les neurones PV- de la SNr.Nos résultats mettent en évidence l'importance de différencier les populations cellulaires de la SNr pour une meilleure connaissance du fonctionnement des BG en situation physiologique et physiopathologique tel que dans la MP
The substantia nigra pars reticulate (SNr) is the main output structure of the basal ganglia (BG), a subcortical network controlling the elaboration of motor programs as well as cognitive and associative learning functions. The identification of distinct cell-types within the BG has played a key role for understanding the properties and functions of this circuit. Recent studies suggest that the SNr is composed of several cell types but until now this neuronal diversity has never been taken into consideration regarding normal and pathological functioning of this nucleus, particularly in Parkinson’s disease (PD). By combining immunohistochemical and electrophysiological approaches in the PVCre::Ai9T mouse line, we have demonstrated that SNr neurons expressing the protein parvalbumin (PV+) exhibit different anatomical and electrophysiological properties than non PV-expressing (PV-) neurons. Our anatomical analysis reveal that PV+ and PV- neurons are present in equal proportion in the SNr, but with a distinct distribution, PV+ being enriched in the lateral part of the SNr, while PV- are found in the medial portion of the nucleus. In vitro electrophysiological recordings from identified PV+ and PV- neurons in the SNr also revealed that PV+ neurons fired at relatively higher rates than PV- cells. Additionally, our data revealed that DA loss and subsequent L-DOPA treatment induce a profound reduction of the excitability of PV+ SNr neurons in a 6-OHDA mouse model of PD while activity of PV- remains unchanged by these treatments.It is well known that the activity of SNr neurons is controlled by GABAergic inputs from striatal dSPN and the GP. We performed optogenetic manipulation of STR-SNr and GP-SNr inputs in order to determine whether PV+ and PV- SNr neurons received equivalent inputs from these two nuclei. We tested the impact of STR-SNr or GP-SNr activation on the activity of SNr neurons in cell-attached configuration and then switched to whole-cell voltage-clamp to characterize short-term plasticity of these synapses. Our results show that both PV+ and PV- SNr neurons are innervated by the STR and the GP. They also revealed that inhibition from dSPN was more powerful to silence activity of both subtypes of SNr neurons. Indeed, we observed that both STR-SNr and GP-SNr synapses displayed short-term depression in PV+ and PV- SNr neurons. DA loss affected GABA transmission in a different manner in PV+ and PV- SNr cells. On one hand, PV+ neurons were more sensible to striatal synaptic inhibition than PV- cells after DA depletion. On the other hand, PV-GP inputs were reduced on PV+ neurons and increased in PV- cells after DA loss suggesting a disequilibrium in pallidal inhibition between these two SNr populations.Furthermore, considering that rodent models of PD have shown elevated extracellular levels of GABA in the SNr which can exert a tonic extrasynaptic inhibition on SNr neurons, we decided to characterize GABAergic extrasynaptic transmission in the SNr of control and 6-OHDA lesioned mice. We studied GABAA mediated tonic inhibition by performing whole-cell patch-clamp recordings of PV+ and PV- SNr neurons in acute slices. We observed that PV- SNr neurons displayed larger GABAA receptor-mediated tonic currents than PV+ cells in the SNr of control mice. The presence and involvement of δ and/or α5 extrasynaptic subunits in GABAA receptors mediating this type of transmission was also studied, revealing a major presence and effect of α5-subunits on PV- neurons probably mediating the tonic currents observed in these neurons. However, contrary to expected, chronic DA-depletion did not trigger any increase in tonic inhibition neither in PV+ cells nor in PV- SNr neurons.All these findings highlight the importance of differentiating cell populations in the SNr to a better knowledge of the BG circuit in normal and pathological states such as in PD

Le neurone est une cellule polarisée qui se divise en deux compartiments spécialisés : le compartiment somato-dendritique et le compartiment axonal. Généralement, le premier reçoit l'information en provenance d'autres neurones et le second génère un message en sortie lorsque la somme des entrées dépasse une valeur seuil au segment initial de l'axone. Ce signal de nature discrète appelé potentiel d'action (PA) est propagé activement jusqu'à la terminaison synaptique où il déclenche la transmission chimique de l'information. Cependant, la fonction axonale ne se résume pas à la simple transmission des séquences de PA à l'image d'un câble de télégraphe. L'axone est également capable de transmettre des variations continues de signaux électriques infraliminaires dit analogues et les combiner avec l'information digitale véhiculée par le PA. J'ai consacré la majorité de mon travail de thèse à l'étude de ce nouvel aspect de la fonction axonale dans le cadre de la transmission synaptique entre les neurones pyramidaux au sein du réseau excitateur CA3 de l'hippocampe de rat. Les résultats obtenus à partir d'enregistrements de paires de neurones pendant ma thèse mettent en évidence deux sortes de signalisation analogue et digitale qui aboutissent à la facilitation de la transmission synaptique. La facilitation analogue-digitale (FAD) a été observée lors d'une dépolarisation prolongée, mais également à la suite d'une hyperpolarisation transitoire au niveau du corps cellulaire. Ce sont deux versants d'une même plasticité à court-terme qui découle de l'état biophysique des canaux ioniques sensibles au voltage étant à l'origine du PA
The neuron is a polarised cell divided into two specialized compartments: the somato-dendritic and the axonal compartment. Generally, the first one receives information arriving from other neurones and the second generates an output message, when the sum of inputs exceeds a threshold value at the axon initial segment. This all-or-none signal, called the action potential (AP) is propagated actively to the synaptic terminal where it triggers chemical transmission of information. However, axonal function is not limited to transmission of AP sequences like a telegraph cable. The axon is also capable of transmitting continuously changing sub-threshold electric signals called analogue signals and to combine them with the digital information carried by the AP. I devoted the majority of my thesis work to the study of these novel aspects of axonal function in the framework of synaptic transmission between pyramidal neurons in the CA3 excitatory network of the rat hippocampus. The results obtained through paired recordings brought to light two kinds of analogue and digital signalling that lead to a facilitation of synaptic transmission. Analogue-digital facilitation (ADF) was observed during prolonged presynaptic depolarization and also after a transient hyperpolarization of the neuronal cell body. These are two sides of the same form of short-term synaptic plasticity depending on the biophysical state of voltage gated ion channels responsible for AP generation. The first variant of ADF induced by depolarization (ADFD) is due to AP broadening and involves Kv1 potassium channels

Wearable technology has attracted global attention in the last decade and the market is experiencing an unprecedented growth. Wearable devices are designed to be low-profile, light-weight and integrated seamlessly into daily life. Comfort is one of the most important requirements for wearable devices. Fabric based antennas are soft, flexible and can be integrated into clothing. State of the art textile manufacturing techniques such as embroidery, combined with advanced conductive textile materials can be used to fabricate flexible fabric based on-body antennas. In this thesis, the feasibility of using computerised embroidery in the fabrication of wearable, flexible yet functional fabric based antennas have been examined. The fabric based antennas are embroidered using conductive threads. The most suitable materials for fabricating embroidered antennas have been identified. The embroidered fabric based antenna systems including transmission lines and low-profile detachable connectors have been fabricated and their RF performances have been tested. The optimal manufacturing parameters related to embroidery such as stitch direction, spacing and length have been examined. The repeatability of embroidered antennas, cost estimation, and complexity of manufacturing process have been clearly presented. The results can be used to inform and provide guidelines for the development of representative products that can be mass manufactured. A new simulation approach has been introduced to analyse the anisotropic properties of embroidered conductive threads. Simulations and measurements indicate that the performances of embroidered antennas are affected by the anisotropic surface current due to the embroidered stitches. Exploiting the current direction, a novel non-uniform meshed patch antenna has been designed. Representative results show that the non-uniform meshed structure can significantly reduce more than 75% of the usage of conductive materials for the microstrip antennas with negligible effect on the antenna performance.

At the intersection of geography and public health, the field of spatial epidemiology seeks to use the tools of geospatial analysis to answer questions about disease. In this work we explore two areas: the use of geostatistical modeling as an extension of niche modeling, and the use of mobility metrics to augment modeling for epidemic responses. Niche modeling refers to the practice of using statistical methods to relate the underlying spatially distributed environmental variables to an outcome, typically presence or absence of a species. Such work is common in disease ecology, and often focuses on exploring the range of a disease vector or pathogen. The technique also allows one to explore the importance of each underlying regressor, and the effect it has on the outcome. We demonstrate that this concept can be extended, through geostatistical modeling, to explore non-logistic phenomena such as incidence. When combined with weather forecasts, such efforts can even predict incidence of an upcoming season, allowing us to estimate the total number of expected cases, and where we would expect to find them. We demonstrate this in Chapter 2, by forecasting the incidence of melioidosis in Australia given weather forecasts a year prior. We also evaluate the efficacy of this technique and explore the impact of environmental variables such as elevation on melioidosis. But these techniques are not limited to free-living and vector-borne pathogens. We theorize that they can also be applied to diseases that spread exclusively by person-to-person contact. Exploring this allows us to find areas of underreporting, as well as areas with unusual local forcing which might merit further investigation by the health department. We also explore this in Chapter 4, by relating the incidence of hepatitis C in rural Virginia to demographic data. The West African Ebola Outbreak of 2014 demonstrated the need to include mobility in predictive disease modeling. One can no longer assume that neglected tropical diseases will remain contained and immobile, and the assumption of random mixing across large areas is unwise. Our efforts with modeling mobility are twofold. In Chapter 3, we demonstrate the creation of mobility metrics from open source road and river network data. We then demonstrate the usefulness of such data in a meta-population patch model meant to forecast the spread of Ebola in the Democratic Republic of Congo. In Chapter 4, we also demonstrate that mobility data can be used to strengthen outbreak detection via hotspot analysis, and to augment incidence models by factoring in the incidence rates of neighboring areas. These efforts will allow health departments to more accurately forecast incidence, and more readily identify disease hotspots of atypical size and shape.
Doctor of Philosophy
The focus of this work is called “spatial epidemiology”, which combines geography with public health, to answer the where, and why, of disease. This is a growing field, and you’ve likely seen it in the news and media. Have you ever seen a map of the United States turning red in some virus disaster movie? The real thing looks a lot like that. After the Ebola outbreak of 2014, public health agencies wanted to know where the next one might hit. Now that there is another outbreak, we need to ask where and how will it spread? What areas are hardest hit, and how bad is it going to get? We can answer all these questions with spatial epidemiology. Our work adds to two aspects of spatial epidemiology: niche modeling, and mobility. We use niche modeling to determine where we could find certain diseases, usually those that are spread by insects or animals. Consider Lyme disease, you get it from the bite of a tick, and the tick gets it from a white-footed mouse. But both the mice and ticks only live in certain parts of the country. With niche modeling we can determine where those are, and we can also guess at what makes those areas attractive to the mice and ticks. Is it winter harshness, summer temperatures, rainfall, and/or elevation? Is it something else? In Chapter 2, we show that you can extend this idea. Instead of just looking at where the disease is, what if we could guess how many people will get infected? What if we could do so, a year in advance? We show that this can be done, but we need a good idea of what the weather will be like next year. In Chapter 4, we show that you can do the same thing with hepatitis C. Instead of Lyme’s ticks and mice, hepatitis C depends on drug-use, unregulated tattooing, and unsafe sex. And like with Lyme, these things are only found in certain places. Instead of temperature or rainfall, we now need to find areas with drug-problems and poverty. But we can get an idea of this from the Census Bureau, and we can make a map of hepatitis C as easily as we did for Lyme. But hepatitis C spreads person-to-person. So, we need some idea of how people move around the area. This is where mobility comes in. Mobility is important for most public health work, from detecting outbreaks to estimating where the disease will spread next. In Chapter 3, we show how one could create a mobility model for a rural area where few maps exist. We also show how to use that model to guess where the next cases of Ebola will show up. In Chapter 4, we show how you could use mobility to improve outbreak and hotspot detection. We also show how it’s used to help estimate the number of cases in an area. Because that number depends on how many cases are imported from the surrounding areas. And the only way to estimate that is with mobility.