In South Africa, non-motorised transport (NMT) modes such as cycling and walking are generally used by poor people to access centres of employment, public services (for example, library, educational institutions, public transport) and other amenities as well as for recreational activities. Notably, the lack of integration among the different public transport modes (namely, NMT, bus, train and minibus) creates a major obstacle in the provision of an integrated, sustainable and effective public transport system. Likewise, the absence of proper recognition of NMT in government and social strata creates a problem in the supply of a satisfactory public transport service, that is, a public transport service that meets the needs of all users. Motivated by the gap in NMT integration with the overall public transport system, the study was undertaken to explore enabling factors to integrate NMT as a key element of the Integrated Rapid Public Transport Network (IRPTN). Social and political factors were explored, specifically, post-modern theory in urban transport planning and policy. In addition, the study explored enabling factors to integrate NMT as a feeder service and key element of an IRPTN from the perspectives of the participants of the study. The results of the study showed that infrastructure, the environment, promotion, and safety and security were identified as enabling factors to integrate NMT as a key element of an IRPTN. According to the results, government needs to promote NMT use. Subsequently, construction and the repair or widening of sidewalks and roads needs to be done. The results also showed that attractive NMT environments are necessary as well as adequate safety and security measures along NMT routes. It is suggested that a seamless, safe, inclusive, affordable, effective and reliable public transport system could be provided once these enabling factors are in place. Further research is advised, within the wider public transport population in eThekwini, as well as other NMT and public transport systems. The emphasis of this research should be on finding out whether the broader public transport population responds in the same way to the idea of integrating NMT and public transport. / Transport Economics, Logistics and Tourism / M. Com. (Transport Economics)

Le trafic dans les réseaux optiques est en constante augmentation depuis de nombreuses années. CISCO affirme qu'il devrait augmenter d'un facteur 13 en 2020. Ceci induit une augmentation de la consommation énergétique et de l'évolution de la taille des réseaux entrainant un accroissement de la complexité des réseaux. Dans ce contexte, pour répondre à l'augmentation du débit dans les réseaux et procure un réseau de télécommunications fiable, il faut prévoir une planification et une ingénierie de réseaux adaptées. Dans ce but, nous étudions dans cette thèse le design d'un nœud de commutation optique ROADM. nous considérons différentes architectures de nœud, composants et sous-systèmes utilisés dans les configurations de nœud RODM "Broadcast and Select" et "Route and Select". Diverses configurations de modules d'insertion/extraction sont analysées ("Colored/colorless, directional/directionless et contentional/contentionless"). Pour ce faire, nous avons développé un simulateur de nœud ROADM dans une plateforme de trafic dynamique et nous avons proposé une stratégie de gestion offline de la contention à l'intérieur du nœud. Nous avons obtenu une réduction du rapport de blocage intra noeud de l'ordre de 1.5. Ensuite, nous nous sommes focalisés sur la planification des futures générations de réseaux optiques métro cœur. Dans ce but, nous avons étudié la possibilité d'une transmission non cohérente à 100 Gb/s en utilisant le format de modulation PDM-DQPSK. Ensuite, nous avons considéré l'implémentation de la PDM-CS-DQPSK. La qualité de transmission de ces deux systèmes a finalement été évaluée / Traffic demand is exponentially increasing in recent years. Cisco forecast claims that by 2020, transport traffic will be 13 times of today's traffic transmission. This incremental traffic demand makes concerns about energy consumption and network scalability as well as increasing the network complexity. In this respect, to adresse the future traffic demand requirement and provide a reliable telecommunication network, precise network planning and engineering are needed. To this aim, we adress the problem of ROADM node design by presenting different architectures, components and subsystems to investigate the Broadcast and Select and Route and Select ROADM node architectures. Colored/colorless, directional/directionless and contentional/contentionless add/drop module configurations are studied. Futhermore, the problem of Intra Node Blocking is investigated by developing a node simulator in a dynamic network traffic platform. In this respect, we propose an offline contention management strategy for an ROADMnode in order to efficiently decrease the Intra Node blocking ration by more than 1.5 order of magnitude. Finally, we focus on network planning by investigating short and medium term network upgrades for metro-core optical network. To this goal, we investigate the possibility of non coherent signal transmission in metro-core segment of hierarchical layered optical network. Quality of transmission for 100 Gbit/s PDM-DQPSK-modulation format is investigated. Then, we propose the implementation of PDM-CS-DQPSK modulation format to transmit 100 Gbit/s signals in ROADM based optical transmission systems

By 2020 there will be 50 billion connected devices over the Internet. With the fast-increasing data traffic demand in both fixed and mobile networks, network operators need to migrate networks towards next generation solutions. The network migration requires the enormous investment in equipment and infrastructure, while the revenues are not expected to grow significantly. Therefore, one of the main challenges for network operators is to find out a proper cost-effective optical network solution that can match future high capacity demand and flexibly support multiple network services on a common network infrastructure. The first part of the thesis addresses the Active Optical Network (AON) and its migration strategies towards Next Generation Optical Access (NGOA) solutions. Several migration strategies are proposed from the perspective of network topology, data plane and control plane. A general methodology for Techno-Economic analysis has been developed and applied to the Total Cost of Ownership (TCO) calculation of different NGOA solutions. The thesis provides a complete cost evaluation of AON migration paths, which can be used by network operators to assess the economic feasibility of network migration. A converged Optical Transport Network (OTN) that can serve both fixed and mobile network services is beneficial from the cost-saving perspective. However, the different types of services, require different network performance. The second part of the thesis focuses on the investigation of the converged OTN that can be flexibly and timely adjusted to satisfy varying service conditions. A programmable OTN featured with Wavelength Division Multiplexing (WDM) in the data plane and Software Defined Networking (SDN) in control plane has been proposed. To demonstrate the benefits of the converged OTN, the thesis also provides a multi-domain orchestration architecture for the multiple network services.  The resource orchestration, across three network domains: OTN, mobile network and cloud, enables agile service creation and optimized resource allocation among the multiple domains. / <p>QC 20170512</p>

[pt] Com a crescente demanda por maior capacidade na transmissão de dados, uma solução tem sido estudada para transmissão de rádio sobre fibra combinando múltiplos canais de dados sobre a portadora óptica na rede de acesso baseada em multiplexação por sub-portadoras. Ademais, essa rede de acesso é comumente ramificada na forma de uma rede óptica passiva. Monitoramento desses enlaces em fibra é, então, cada vez mais importante. A tecnologia atual de reflectometria óptica no domínio do tempo utilizada para monitoramento opera em um comprimento de onda óptico separado e possui ampla largura de banda de detecção, tornando-se relativamente cara. A busca por uma alternativa de monitoramento de alta precisão e baixo custo é de suma importância para a oferta de transmissão com garantia de qualidade de serviço. Neste trabalho, o uso de multiplexação por sub-portadoras é explorado, incorporando uma técnica de monitoramento de varredura de tom de baixa frequência na transmissão de dados. Um modelo matemático para a resposta em frequência do enlace foi derivado e a localização e a intensidade de uma falha são estimadas através da comparação com a amplitude e a fase detectadas da luz retroespalhadaa medida em que é feita uma varredura de frequência do sinal de monitoramento, aplicando-se um algoritmo de minimos quadrados. O modelo proposto considera que a medida do enlace antes da ocorrência de uma falha é conhecida. Uma única falha nova pode então ser detectada com precisão e sua posição e intensidade são estimadas da maneira descrita. / [en] With ever growing demand for higher capacity in data transmission, a solution has been proposed for analog Radio over Fiber transmission, combining several data channels over the optical carrier in the access network using Sub-Carrier Multiplexing (SCM). Furthermore, this access network is often branched in the form of a passive optical network (PON). Monitoring such fiber links is thus increasingly important. Current optical time domain reflectometry (OTDR) technology used for monitoring operates at a separate optical wavelength and has wide bandwidth detection, making it relatively costly. The pursuit of a low cost, high precision monitoring alternative is of paramount importance for cost effective quality of service (QoS) improvement. In this work employment of SCM for data multiplexing is exploited embedding a low frequency tone sweep monitoring technique into data transmission. A mathematical model for the frequency response of the link was derived and the fault location and intensity is estimated through comparison with acquired amplitude and phase of the backscattered light for the varying frequency by applying a simple least mean squared (LMS) algorithm. The modeling suggested requires that measurement of the link prior to the occurrence of a fault is known. A single new fault can then be accurately detected and its position and intensity estimated in the way described.

Lors de la réalimentation des auxiliaires d’une tranche nucléaire, l’étape la plus à risque est la remise sous tension brusque du transformateur à cause des surtensions. Dans un soucis perpétuel d’amélioration de la modélisation de ces transitoires, les modèles et techniques doivent évoluer. Le but de ces travaux de thèse est de proposer de nouvelles méthodologies permettant d’évaluer les paramètres mal connus de la modélisation. Lors des mises sous tension des lignes électriques, une méthodologie s’appuyant sur l’identification (optimisation ou techniques issues du traitement du signal) permet de déterminer les paramètres variables de la modélisation. Cependant, un des paramètres influents pour les surtensions est le flux rémanent. Face aux problèmes actuels rencontrés pour l’estimer (méthode non directe, dérive, …), une nouvelle méthode basée sur la mesure des flux de fuites du circuit magnétique est proposée. Des mesures réelles utilisant des capteurs de technologie « fluxgate » sont réalisées et permettent d’estimer le flux rémanent. / During the re-energization of the auxiliaries of a nuclear power plant, the more dangerous step is the re-energization of the power transformer, because of the temporary overvoltages. In order to improve the transient modeling, models and techniques may be improved. The purpose of this thesis is to suggest new methodologies to identify the uncertain parameters of the model. When the line re-energization occurs, an identification methodology (optimization or methods using signal processing) allows determining the model variable parameters. However, one of the most important parameters in the overvoltages is the residual flux. Given the actual problems found on estimation strategies (no direct method, derivation,…), a new method established for the leakage flux measurement of the magnetic circuit is proposed. Real measurements using « fluxgate » technology sensors were realized, permitting to estimate the residual flux.

Air pollution is becoming a major issue in cities across the world, its common cause being the use of fossil fuel combustion engines in both private and collective transport modes. However, alternative technologies, such as biofuels, hybrid and battery electric vehicles, are on the rise. The objective of this thesis is to assess the optimal system’s configuration – a combination of electric traction and the use of biofuels – in a sub-group of Curitiba’s public bus network through the application of two optimisation models – least energy consumption and least cost. Based on these models, total energy, cost and greenhouse gas (GHG) emissions can be calculated for different scenarios to identify the advantages of switching to a low-carbon system. Furthermore, these models can be used by planners and decision makers as a starting point in defining the path towards a cleaner transport system. The results from the energy optimisation indicate that electrification is key in reducing total energy consumption, as this technology is by far the most energy efficient. A 12% reduction could be achieved, when compared to the current scenario (only using diesel B7), and CO2 emissions could be cut by 74%. The cost optimisation shows that electrification is not yet cost competitive compared to other biofuels (biodiesel, bioethanol and biogas), as biodiesel is the only technology selected by the model due to its overall lower cost. Nonetheless, if electricity costs are reduced, which can be achieved, for example, through a reduction or abolition of taxes, electrification becomes an attractive alternative to biofuels. Under these conditions (40% lower electricity price), energy consumption is reduced by 5% and GHG emissions are cut down to 30%. Political will and strategies to decrease the cost of vehicles turn out to be essential in supporting electrification in public transport. Furthermore, adaptations in the time schedules and the organisation of the main transport hubs are required to accommodate battery electric buses.  The number of fast charging stations is usually on a par with the number of bus routes to be electrified. Cost synergies achieved by sharing the cost of a charger among electrified routes with a common start/end stop are crucial to secure the attractiveness of e-mobility. This underlines the importance of analysing infrastructure needs in public transport networks holistically. / A poluição atmosférica é um problema sério em praticamente todas as grandes cidades do mundo, sendo a sua origem mais comum, o uso de combustíveis fósseis em motores de combustão, tanto em veículos de uso privado como em veículos de transporte coletivo. No entanto, tecnologias alternativas, tais como o uso de biocombustíveis, e a utilização de veículos híbridos e elétricos, estão em expansão. Esta tese tem como objectivo avaliar a configuração ideal do sistema, utilizando, num subgrupo da rede de transportes de Curitiba, uma combinação de tração elétrica e de uso de biocombustíveis. Esta avalição é feita através da aplicação de dois modelos de optimização: menor consumo energético e menor custo global. Com base nestes dois modelos, o consumo energético e os custos globais, bem como as emissões de gases de efeito de estufa (GEE), podem ser calculados para os diferentes cenários, de modo a se identificarem as vantagens da transição para um sistema de baixo carbono. Acresce que estes dois modelos podem ser usados por planeadores e decisores, como ponto de partida na definição do caminho a seguir para a transição para um sistema de transporte mais ecológico. Os resultados da otimização do consumo energético, indicam que a eletrificação é fundamental para reduzir o consumo total de energia, pois esta tecnologia é, de longe, a mais eficiente em termos energéticos. Uma redução do consumo total de energia em 12% poderá ser alcançada em relação ao cenário actual (que use apenas o diesel B7) e as emissões de CO2 poderão ser reduzidas em 74%. Na otimização de custos, os resultados mostram que a eletrificação ainda não é competitiva em termos de custos, quando comparada com o uso de biocombustíveis (biodiesel, bioetanol e biogas), uma vez que o biodiesel é a única tecnologia selecionada pelo modelo por ter menores custos associados. No entanto, se os custos da eletricidade forem reduzidos, nomeadamente, através da diminuição ou supressão de impostos, a eletrificação torna-se uma solução atrativa. Numa situação de redução do preço da energia elétrica em 40 %, o consumo de energia é reduzido em 5% e as emissões de GEE são reduzidas para 30%. Vontade política e estratégias destinadas a diminuir o custo dos veículos elétricos, tornam-se essenciais para promover a eletrificação dos transportes públicos. Acresce que, a adaptação dos horários e a organização dos principais terminais de transporte, são necessários para possibilitar a  operacionalidade dos ônibus elétricos. De acordo com os resultados dos dois modelos, o número de estações de recarga rápida é aproximadamente igual ao número de rotas de ônibus a serem eletrificadas. A redução de custos alcançada, partilhando um carregador entre rotas electrificadas com paragens inicial/final comuns, é crucial para garantir a atratividade da mobilidade eléctrica. Isto sublinha a importância dos benefícios de uma análise holística da infrastrutura de recarga nas redes de transporte público coletivo. / Luftföroreningar är en stor utmaning i städer runt om i  världen. Den gemensamma orsaken är användningen av förbränningsmotorer med fossila bränslen i både privata och kollektiva transportsätt. Dock alternativt teknik, såsom biobränslen, hybrid- och batterielektriska fordon, har uppmärksammats och deras användning ökar. Syftet med denna avhandling är att bedöma det optimala systemets konfiguration - en kombination av elektrisk drivkraft  och användningen av biobränslen - i Curitibas allmänna bussnät genom tillämpning av två optimeringsmodeller – en som minimiserar  energiförbrukning och en som minimizerar kostnader. Baserat på dessa modeller, de totala utsläpp och energiförbrukningen, samt deras respektiva kostnader kan beräknas för olika scenarier. På detta sätt  fördelarna med att byta till ett kolfrisystem identifieras. Dessutom kan dessa modeller användas av planerare och beslutsfattare som utgångspunkt för att definiera strategier mot en renare transportsystem. Resultaten från energioptimering indikerar att elektrifiering är nyckeln till att minska  systemets energiförbrukning, eftersom denna teknik är överlägset mest energieffektiv. En minskning på 12% skulle kunna uppnås, jämfört med det utgångsscenariot (endast med diesel B7) och koldioxidutsläppen skulle kunna minska med 74%. Kostnadsoptimeringen visar att elektrifiering ännu inte är kostnadseffektiv jämfört med andra biobränslen (biodiesel, bioetanol och biogas). I detta scenario är biodiesel den enda tekniken som valts av modellen på grund av dess lägre kostnad. Men om elkostnaderna minskas blir elektrifiering ett attraktivt alternativ till biobränslen. Detta skulle kunna uppnås, till exempel, genom skattebefrielse.  Under dessa förutsättningar (40% lägre elpris) minskas energiförbrukningen med 5% och utsläppen minskar med30%. Politisk vilja och strategier för att minska fordonskostnaden visar sig vara avgörande för att stödja elektrifiering av kollektivtrafiken i Curitiba. Dessutom anpassningar av tidstabellerna och organisationen av de viktigaste bytespunkter är nödvändiga. Antalet snabba laddstationer är vanligtvis i linje med antalet busslinjer som ska elektrifieras. Kostnadssynergier uppnås genom att dela kostnaden för en laddare bland elektrifierade linjer med ett gemensamt start / slutstopp. Det är avgörande för att säkerställa e-mobilitetens attraktivitet. Det visar också vikten av att analysera infrastrukturbehoven i kollektivtrafiknätet holistiskt.

[pt] Para suportar os requisitos das redes móveis de 5a geração (5G), os sistemas de comunicação óptica serão usados nas redes de acesso. Isso ocorre porque a evolução das RAN (Radio Access Networks) incluem a centralização do equipamento mais crítico para implantar pontos de acesso móveis de baixa potência, como DAS (Distributed Antenna Systems) e Small Cells. Os serviços emergentes solicitam a implantação de tecnologias de rádio sobre fibra com ênfase na eficiência de largura de banda, eficiência energética e alta confiabilidade. Neste âmbito, um monitoramento eficiente da camada física é imperativo para a operação dessas redes. O sistema de monitoramento deve fornecer uma localização de falhas em serviço, econômico, centralizado e com impacto mínimo para a transmissão de dados. Esta tese propõe vários sistemas de monitoramento incorporado no transceptor utilizando reflectometria óptica no domínio do tempo. Os sistemas de monitoramento são testados em diferentes sistemas de transmissão de dados e arquiteturas de rede, onde é apresentada uma validação simulada e outras experimentais. / [en] In order to support the requirements for 5th generation mobile networks (5G), optical communication systems will be used in the access part of the network. This is because the evolution of radio access networks includes the centralization of the most critical equipment in order to deploy low power mobile access points, like distributed antenna systems and small cells. The emerging services call for the deployment of radio over fibre technologies with emphasis on bandwidth efficiency, energy efficiency and high reliability. Within this scope, an efficient monitoring of the physical layer would become essential for the operation of these networks. The monitoring system should provide in-service, cost efficient and centralized fault localization with minimum impact on data transmission. This thesis proposes several transceiver-embedded optical time domain reflectometry monitoring systems. The monitoring systems are tested over different data transmission systems and network architectures, where one architecture was simulated and several others experimentally validated.