abstract: Emerging modular cable network architectures distribute some cable headend functions to remote nodes that are located close to the broadcast cable links reaching the cable modems (CMs) in the subscriber homes and businesses. In the Remote- PHY (R-PHY) architecture, a Remote PHY Device (RPD) conducts the physical layer processing for the analog cable transmissions, while the headend runs the DOCSIS medium access control (MAC) for the upstream transmissions of the distributed CMs over the shared cable link. In contrast, in the Remote MACPHY (R-MACPHY) ar- chitecture, a Remote MACPHY Device (RMD) conducts both the physical and MAC layer processing. The dissertation objective is to conduct a comprehensive perfor- mance comparison of the R-PHY and R-MACPHY architectures. Also, development of analytical delay models for the polling-based MAC with Gated bandwidth alloca- tion of Poisson traffic in the R-PHY and R-MACPHY architectures and conducting extensive simulations to assess the accuracy of the analytical model and to evaluate the delay-throughput performance of the R-PHY and R-MACPHY architectures for a wide range of deployment and operating scenarios. Performance evaluations ex- tend to the use of Ethernet Passive Optical Network (EPON) as transport network between remote nodes and headend. The results show that for long CIN distances above 100 miles, the R-MACPHY architecture achieves significantly shorter mean up- stream packet delays than the R-PHY architecture, especially for bursty traffic. The extensive comparative R-PHY and R-MACPHY comparative evaluation can serve as a basis for the planning of modular broadcast cable based access networks. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

Hybrid inorganic-organic networks have been studied in both chemistry and materials science due to properties, (e.g. porosity, magnetic and electronic behaviors) that may lead to applications in catalysis, gas absorption and storage. It is important to understand the different structural topologies shown by hybrid networks to help develop practical applications for these materials. The research is focused on the design and synthesis of well-defined hybrid network structures that have potential to contain molecular size cavities that can be used for catalysis and gas storage. In the field of organic-inorganic hybrid networks, the goals are to design and synthesize 1D, 2D and 3D networks with cavities, and to characterize them by X-ray, TGA and surface area measurements. Twenty-six networks have been successfully made with interesting structure topologies. These hybrid network structures are classified into three series based on their ligands. Series I contains ten hybrid networks constructed from the flexible ligand, 4, 4′-trimethylenedipyridine (TMDP), Zn2+ ions, and H3PO3, and with aromatic alcohols as templates to direct the formation of various hybrid network structures. Series II consists of five structures constructed from the relatively rigid ligand, 4, ′-bisimidazolelybipyridine (BIB) with metal ions (Cu2+, Ni2+) and the conjugated bases of H3PO3 and H3PO4. The BIB ligand is not commercially available so is produced and characterized by NMR, mass spectrometry and TGA. Rigid network structures were expected to construct with pores of molecular dimensions with the BIB ligand. To date, the BIB ligand has not yield the desired porous network, however, these 3D hybrid networks have interesting topologies, one of which is an interdigitated network that is the precursor for 3D interpenetrated networks. Series III contains five hybrid structures constructed from various organic ligands, such as tartaric acid, picolinic acid and 1, 2, 4-triazole. In addition to the hybrid networks, six hydrogen bonded networks were prepared. Graph-Analysis is applied to study these hydrogen bonded network structures. The Ï â ¦.Ï interaction is also discussed within the hydrogen bonded networks. / Ph. D.

Ce manuscrit présente la synthèse de nouveaux réseaux hybrides organiques/inorganiques à base de différents ligands imidazoliums. Trois ligands imidazoliums possédant chacun des caractéristiques spécifiques ont été synthétisés et utilisés avec l’objectif de parvenir à la formation de réseaux hybrides multiferroïques c’est-à-dire des réseaux qui possède à la fois un ordre magnétique et un ordre électrique. La modification du ligand a ainsi permis d’obtenir des composés répondant aux critères (de symétrie en particulier) à remplir pour la présence d’un ordre électrique. Pour construire le réseau inorganique magnétique nous avons travaillé sur la synthèse de composés à base de métaux de transition de la première série ou de lanthanides. L’ensemble des composés obtenus a été caractérisé par un ensemble de techniques (diffraction des rayons X, spectroscopie FTIR et UV-Vis, analyses thermiques et élémentaires). Les propriétés magnétiques, de luminescence et de ferroélectricité des composés ont aussi été étudiées. / This thesis presents the syntheses of new hybrid coordination networks based on imidazolium ligands. Three kinds of ligands possessing their own features were synthesized and used with the main objective to obtain multiferroic hybrid networks meaning networks which display a magnetic order and a ferroelectric order. The modification of the ligand allowed to obtain compounds filling criteria (on the symmetry) for a ferroelectric order. The magnetic inorganic network was built due to the synthesis of compounds based on first row metals or lanthanides. All compounds were characterized by several techniques (X-rays diffraction, spectroscopic measurements, thermal and elemental analyses). Magnetic, luminescence and ferroelectric properties were also studied.

La multiplication du nombre d'objets, qui ont vocation à être connectés à Internet (e.g., smartphones, capteurs), et la croissance des échanges de données effectués par des individus en situation de mobilité ont conduit, et conduiront encore, à une augmentation significative du trafic de données dans les réseaux, et en particulier dans les réseaux cellulaires. Les récents progrès réalisés au niveau de la couche physique pour accroître les débits dans ces réseaux pourraient s'avérer insuffisants dans le futur avec l'émergence d'un Internet des objets. Il nous semble dès lors intéressant d'étudier des architectures réseau alternatives ou complémentaires. Les réseaux hybrides à connectivité intermittente (RHCI), qui sont constitués d'une infrastructure et de parties formées par des objets fixes ou mobiles communiquant en mode ad hoc, font partie de ces architectures qui méritent d'être étudiées. Dans cette thèse, nous étudions les bénéfices que pourrait apporter l'utilisation des techniques des réseaux pair-à-pair et des communications opportunistes dans les RHCI. Nous proposons une architecture pair-à-pair décentralisée et non structurée qui permet d'assurer les communications entre des objets dans des RHCI de grande taille via différents modes de communication. Un prototype de plateforme, baptisé Nephila a été développé, pour évaluer cette approche en simulation. / The number of devices that are likely to get connected to the Internet (e.g., smartphones, sensors), and the amount of data produced by people using these devices grow continuously, especially in cellular networks. Latest developments performed on the physical layer to increase the networks' bandwidth might be insufficient in the future, because of the emergence of the Internet of things. Therefore, it seems to be interesting to study new or complementary network architectures. Intermittently-Connected Hybrid Networks (ICHN), which are composed both of an infrastructure part and of parts formed by mobile device communicating using ad hoc mode, are examples of those architectures that deserve to be studied. In this thesis, we study benefits that peer-to-peer mechanisms and opportunistic networking techniques could bring to ICHN. We propose a decentralized unstructured peer-to-peer overlay architecture that supports communications between devices in wide ICHNs. A prototype named Nephila has been developed to evaluate this approach in simulation.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / In this work is presented the hydrothermal synthesis, the structural studies and spectroscopic properties of three coordination polymers based on lanthanides ions (Eu3+, Tb3+ and Gd3+) and DPA as ligand (DPA= 2,6- dipicolinate). Structural study of [Eu(DPA)(HDPA)(H2O)2.4H2O] displayed the presence of self-assembled dimeric and hexameric water clusters fit in the linear chains and the respective role on the stabilization of supramolecular strucuture. The spectroscopic investigations show the low quantum efficiency (η = 12.7%) caused by large contribution of non-radiative decay rates governing the relaxation process due to vibronic coupling with water molecules. The coordination polymers [Tb(DPA)(HDPA)] and [Gd(DPA)(HDPA)] are isostructurals and allowed the investigation about energy transfers processes. In the case of [Tb(DPA)(HDPA)] compound, the photoluminescence data shown the high quantum yield of emission (≈ 50%) due tho the DPA ligand to be a good sensitizer and the lack of water molecules coordinated directly to metal. / Nesse trabalho é apresentado a síntese hidrotermal, estudo estrutural e as propriedades espectroscópicas de três polímeros de coordenação baseados nos lantanídeos (Eu3+, Tb3+ e Gd3+) e o DPA como ligante (DPA= 2,6- dipicolinato). A determinação estrutural do [Eu(DPA)(HDPA)(H2O)2.4H2O] evidencia a presença de clusters de água auto organizados com dímeros e hexâmeros intercalando as diferentes cadeias e o respectivo papel na estabilização da estrutura supramolecular tridimensional. Através dos estudos espectroscópicos foi evidenciado a baixa eficiência quântica (η = 12.7%) como reflexo da larga contribuição das taxas não-radiativas que controlam o processo de relaxação, devido ao acoplamento vibrônico com as moléculas de água. Os polímeros de coordenação [Tb(DPA)(HDPA)] e [Gd(DPA)(HDPA)] são iso-estruturais e permitiram a investigação do processo de transferência de energia. No caso do composto [Tb(DPA)(HDPA)], os dados de luminescência mostraram elevado rendimento quântico da emissão (≈ 50%) devido ao ligante DPA se um bom sensibilizador e a ausência de moléculas de água coordenadas ao metal.

No description available.

No / The last decade has seen an exponential rise in the use of wireless sensor networks (WSNs) in various applications. While these have been primarily used on their own, researchers are now looking into ways of integrating these WSNs with other existing communication technologies. One such network is the satellite network which provides significant advantage in providing communication access to remote locations due to their inherent large coverage areas. Combining WSNs and satellite will enable us to perform efficient remotely monitoring in areas where terrestrial networks may not be present. However in such a scenario, the placement of sensor nodes is crucial in order to ensure efficient routing and energy-efficiency. This paper presents four network architectures for sensor-satellite hybrid networks, sensor-satellite direct communication, connections via a gateway node employing random node layout, grid-based node layout and cluster-based node layout with data aggregation. These architectures were simulated using network simulator 2 (ns-2) and then their packet loss rate, average end-to-end packet delay, and overall energy consumption were compared. The paper concludes by proposing a suitable network topology for environmental monitoring applications.

The objective of this research is to develop an optimized quality of service (QoS) assurance algorithm with the differentiated services (DiffServ) architecture, and a differentiated polling algorithm with efficient bandwidth allocation for QoS assurance in the hybrid multi-hop mesh/relay networks. These wide area networks (WANs), which will employ a connection-based MAC protocol, along with QoS-enabled wireless local area networks (WLANs) that use a contention-based MAC protocol, need to provide an end-to-end QoS guarantee for data communications, particularly QoS-sensitive multimedia communications. Due to the high cost of construction and maintenance of infrastructure in wireless networks, engineers and researchers have focused their investigations on wireless mesh/relay networks with lower cost and high scalability. For current wireless multi-hop networks, an end-to-end QoS guarantee is an important functionality to add, because the demand for real-time multimedia communications has recently been increasing. For real-time multimedia communication in heterogeneous networks, hybrid multi-hop mesh/relay networks using a connection-based MAC protocol, along with QoS-enabled WLANs that use a contention-based MAC protocol can be an effective multi-hop network model , as opposed to multi-hop networks with a contention-based MAC protocol without a QoS mechanism. To provide integrated QoS support for different QoS mechanisms, the design of the cross-layer DiffServ architecture that can be applied in wireless multi-hop mesh/relay networks with WLANs is desirable. For parameterized QoS that requires a specific set of QoS parameters in hybrid multi-hop networks, an optimized QoS assurance algorithm with the DiffServ architecture is proposed here that supports end-to-end QoS through a QoS enhanced WAN for multimedia communications. For a QoS assurance algorithm that requires a minimum per-hop delay, the proper bandwidth to allow the per-hop delay constraint needs to be allocated. Therefore, a polling algorithm with a differentiated strategy at multi-hop routers is proposed here. The proposed polling algorithm at a router differentially computes and distributes the polling rates for routers according to the ratio of multimedia traffic to overall traffic, the number of traffic connections, and the type of polling service. By simulating the architecture and the algorithms proposed in this thesis and by analyzing traffic with the differentiated QoS requirement, it is shown here that the architecture and the algorithms produce an excellent end-to-end QoS guarantee.

With the emergence of connected and autonomous vehicles, sensors are increasingly deployed within car. Traffic generated by these sensors congest traditional intra-vehicular networks, such as CAN buses. Furthermore, the large amount of wires needed to connect sensors makes it hard to design cars in a modular way. These limitations have created impetus to use wireless technologies to support intra-vehicular communication. In this dissertation, we tackle the challenge of designing and evaluating data collection protocols for intra-car networks that can operate reliably and efficiently under dynamic channel conditions. First, we evaluate the feasibility of deploying an intra-car wireless network based on the Backpressure Collection Protocol (BCP), which is theoretically proven to be throughput-optimal. We uncover a surprising behavior in which, under certain dynamic channel conditions, the average packet delay of BCP decreases with the traffic load. We propose and analyze a queueing-theoretic model to shed light into the observed phenomenon. As a solution, we propose a new protocol, called replication-based LIFO-backpressure (RBL). Analytical and simulation results indicate that RBL dramatically reduces the delay of BCP at low load, while maintaining its high throughput performance. Next, we propose and implement a hybrid wired/wireless architecture, in which each node is connected to either a wired interface or a wireless interface or both. We propose a new protocol, called Hybrid-Backpressure Collection Protocol (Hybrid-BCP), for the intra-car hybrid networks. Our testbed implementation, based on CAN and ZigBee transceivers, demonstrates the load balancing and routing functionalities of Hybrid-BCP and its resilience to DoS attacks. We further provide simulation results, obtained based on real intra-car RSSI traces, showing that Hybrid-BCP can achieve the same performance as a tree-based protocol while reducing the radio transmission power by a factor of 10. Finally, we present TeaCP, a prototype Toolkit for the evaluation and analysis of Collection Protocols in both simulation and experimental environments. TeaCP evaluates a wide range of standard performance metrics, such as reliability, throughput, and latency. TeaCP further allows visualization of routes and network topology evolution. Through simulation of an intra-car WSN and real lab experiments, we demonstrate the functionality of TeaCP for comparing different collection protocols.

Made available in DSpace on 2016-06-02T20:00:59Z (GMT). No. of bitstreams: 1 6187.pdf: 10612563 bytes, checksum: a862a5af5f2efd3cad4a6dabde238766 (MD5) Previous issue date: 2014-06-24 / Universidade Federal de Sao Carlos / It deduces, nowadays, that one of the biggest challenges to be overcome by planning and urban management is the condition between the conservation of natural resources committed by the process of urbanization and the urban development. This lead to be necessity of developing strategies that provides control conditions and reverse the effects of the socio environmental degradation, as in the case of urban flooding and irregular settlements in conservation areas. From this context stands out the green infrastructure, a system based in environmental urban planning, which offers the perspective of upgrading the urban environment through the development of hybrid networks, that links green spaces and surface water areas. Through analyses of urban landscapes they are identified the socio environmental conditions and they establish strategies using specific planning to guarantee the existence, the recovering and expansion of natural resources in urban spaces. Thus the concept of green infrastructure comes from the idea that natural spaces fulfill infrastructure function, consolidating a landscape of high performance while offering environment benefits. To that situation, it uses several types that enable the conservation of natural ecosystem and their functions: climate regulations, soil permeability, aquifer supply, filtering the storm water, controlling the air and noisy pollution, increased by biodiversity and recreational areas, promotion of nom motorizing mobility, among others. Therefore, this study aims to define the real methods to introduce the system of green infrastructure in a geographic division in urban area of Ribeirão Preto SP, so that it is possible to establish to this area a model of occupation to mitigate negative environmental impacts caused by urban expansion. It will be useful as an example for other cities to get success when they consider this important aspect in their planning to urban space. / Constata-se, atualmente, que um dos grandes desafios a ser superado pelo planejamento e gestão urbana refere-se à conciliação entre a conservação dos recursos naturais, comprometidos pelo processo de urbanização, e o desenvolvimento urbano. Isso leva à necessidade de desenvolver estratégias que ofereçam condições de controle e reversão dos efeitos da degradação socioambiental, como no caso das inundações urbanas e das ocupações irregulares em áreas de preservação. A partir deste contexto destaca-se a infraestrutura verde, um sistema fundamentado no planejamento urbano ambiental, que oferece a perspectiva de requalificação do ambiente urbano por meio do desenvolvimento de redes hibridas, que articulam áreas verdes e corpos hídricos superficiais. Por meio de análises sobre a paisagem urbana, são identificadas as condições socioambientais do meio e estabelecidas estratégias, mediante planejamento específico, para garantir a existência, a recuperação e a ampliação dos recursos naturais existentes no espaço urbano. Desse modo, a concepção da infraestrutura verde parte da ideia de que espaços naturais cumpram funções infraestruturais, consolidando uma paisagem com elevado desempenho que oferece benefícios socioambientais. Para isso, faz-se uso de diversas tipologias que permitem a conservação dos ecossistemas naturais e de suas funções: regulação climática, permeabilidade do solo, abastecimento de aquíferos, filtragem das águas pluviais, controle da poluição atmosférica e sonora, aumento da biodiversidade e de áreas de lazer, promoção de mobilidade não motorizada, dentre outras. Logo, este trabalho visa definir as diretrizes necessárias à implantação de sistema de infraestrutura verde em um recorte geográfico sobre a área urbana de Ribeirão Preto SP, de forma que o espaço em questão possa estabelecer um modelo de ocupação que atenue os impactos ambientais negativos (ocasionados pela expansão urbana), além de servir como exemplo para que outras cidades tenham êxito ao considerar a infraestrutura verde como um importante aspecto no planejamento do espaço urbano.