This dissertation begins with proposing a novel street Connectivity Indicator (C.I.) to predict transit performance by identifying the role that street network connectivity plays in influencing the service quality of demand responsive feeder transit services. This new C.I. definition is dependent upon the expected shortest path between any two nodes in the network, includes spatial features with transit demand distribution information and is easy to calculate for any given service area. Subsequently, a methodology to identify and locate critical links within a grid street system for operating feeder transit services is also developed. A 'critical' street link causes the largest change in transit performance due to the link's removal or addition to an existing network. The most important contribution of this section on link criticality is to present a simple closed-form analytical formula in locating the critical link(s) for a grid street network system of 'any' size. Easily computable formulas have been provided and validated by simulation analyses. Another related model is proposed to compute the optimal grid street spacing that would enhance performance of a demand responsive feeder transit system. The model is tested using simulation. Lastly, an analytical model is also developed for estimating optimal service cycle length or headway of a demand responsive feeder transit service designed to serve passengers, especially during peak periods of demand. Simulation analyses over a range of networks have been conducted to validate the new C.I. definition. Results show a desirable monotonic relationship between transit performance and the proposed C.I., whose values are directly proportional and therefore good predictors of the transit performance, outperforming other available indicators, typically used by planners. Further, useful insights indicate a monotonic decrease in link criticality as we depart from the centrally located links to those located at boundaries. Using a real case example from Denver of the Call-n-Ride system operating similar to a demand responsive feeder transit, optimal cycle lengths differed very modestly from those computed using the model. Extensive simulations performed for different sets of feeder service areas and demand densities, further validated the optimal cycle length model.

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No. of bitstreams: 1 MATOS_Tatiana Possati Vieira_2015.pdf: 2425926 bytes, checksum: f13bd0d309eba8a0b1e1c7cb6d7eec9a (MD5) Previous issue date: 2015-10-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The replacement of natural cover, by other land-uses, associate with the forest fragmentation process can result in the decrease of forest connectivity in the landscapes. The diagnosis of landscape structure, through the landscape ecology metrics, intende to direct the restoration activities and the evaluation of forest connectivity. The study aimed at the evaluation of forest connectivity in the the National Forest (FLONA) Capão Bonito and its surrounding area, in the state of São Paulo, Brazil. We produced a land-use/land-cover map, through supervised digital classification, and calculated the landscape metrics (patch and class level) for study area. Selected metrics (Area, ENN and Shape) were used in the production of sustainability index (SI). The forest patches were classified in levels of priority for forest restauration, through SI. In order to identify the forest connectivity was calculated the Integral Index Connectivity (IIC) and we realized the redundancy analysis (RDA), the non-metric multidimensional scaling (NMDS) and multiple regression. Detection was performed by the bird fixed points method and the composition of bird community was obtained through the abundance of species. The diversity index of Shannon Weaver (H ') and species richness was calculated. The land-use/land-cover map indicated that the landscape´s matrix is agriculture, with native forests occupying only 24.45%. The main focuses of forest restoration are the fragments associated with the highest values of SI, because they can guarantee the maintenance and/or the restoration of biodiversity. It was obtained that the IIC =1.000 m influenced in the variance of the birds community and, the shape metric was the main factor that influenced in the composition, richness and diversity of birds. We concluded that is possible to evaluate the connectivity axes using avufauna. The RDA permits the identification of maximum spread for birds. The shape of forest fragments is one of the main factors, influencing in bird community because it is relate with edge effect and forest landscape connectivity. The SI is a simple and effective method for express the priority patches for forest restoration. / Atualmente ocorre a substituição da cobertura natural por outros usos do solo e a fragmentação das áreas florestais, podendo diminuir a conectividade da paisagem. O diagnóstico da estrutura da paisagem, realizado pelas métricas de ecologia da paisagem, tem o objetivo de direcionar as ações de restauração e avaliação da conectividade florestal. O estudo teve por objetivo avaliar a conectividade entre os remanescentes florestais da Floresta Nacional (FLONA) de Capão Bonito e sua área de entorno, no estado de São Paulo, Brasil. Para caracterização da estrutura florestal da paisagem produziu-se o mapa de uso e cobertura do solo, por meio de uma classificação digital supervisionada. A partir deste mapa gerou-se métricas de ecologia da paisagem que, por sua vez, compuseram o índice de sustentabilidade (IS). Os remanescentes florestais foram classificados, a partir de IS, quanto a sua prioridade à restauração florestal. Para identificar a conectividade dos remanescentes florestais obteve-se o Índice Integral de Conectividade (IIC). Realizou-se a detecção das aves pelo método de pontos fixos e obteve-se a composição da comunidade por meio da abundância das espécies. Calculou-se o índice de diversidade de Shannon Weaver (H’) e a riqueza de espécies. Para a avaliação da conectividade florestal realizaram-se as análises de redundância (RDA), de escalonamento multidimensional não métrico (NMDS) e de regressão múltipla. O mapa de uso e cobertura do solo indicou que a paisagem é possui uma matriz predominantemente agrícola, com a floresta nativa representando apenas 24,45% da paisagem. Os principais focos da restauração florestal são os fragmentos com maiores valores de IS, visto que eles garantem a manutenção e/ou restauração da biodiversidade. Obteve-se que o valor de IIC 1.000m influencia na variância da comunidade de aves e a métrica shape mostrou-se como principal fator que influencia a composição, a riqueza e a diversidade das aves. Concluiu-se que é possível avaliar os eixos de conectividade usando dados da avifauna, a RDA permite identificar a máxima dispersão para as aves. A forma dos fragmentos florestais é um dos principais fatores que influenciam na comunidade de aves. O IS constituiu-se um método simples e eficaz que permite indicar os fragmentos prioritários a restauração florestal.

Streams and rivers are examples of vital ecosystems that frequently undergo various environmental and anthropogenic stresses. A core question in population ecology is whether a given population will persist under changing ecological conditions. This thesis consists of three papers and is devoted to the mathematical analysis of responses of river-dwelling species to population persistence threats. The first paper presents a stochastic approach to the 'drift paradox' problem, where the classical reaction-advection-diffusion model is replaced by a birth-death-emigration process. We explore the effects of temporally varying flow on the persistence probability and highlight the importance of the benthic stage for the persistence of stream organisms. The second paper addresses the problem of river network fragmentation through disconnecting structures such as dams. We construct a population matrix model that incorporates the spatial structure of the studied river network and compare structural connectivity to an indicator of population persistence. The third paper adapts the same basic matrix model to examine fish response to disturbances travelling downstream from upstream sites. The study of these three aspects of persistence challenges for river populations contributes to the cumulative effects assessment on river networks.

Urban expansion and climate change intensify environmental challenges, rendering traditional engineering solutions for water management and flood mitigation increasingly ineffective and economically unfeasible. Nature-based solutions, such as wetlands, are gaining attention for their potential to offer sustainable alternatives by naturally managing water, and supporting biodiversity. Despite their benefits, the strategic placement of wetlands within urban landscapes is poorly understood, particularly in terms of the dynamic flow of water and sediments through the landscape. The study aimed to develop an optimized framework for strategically placing wetlands in urban areas to enhance hydrological stability and adaptability. It sought to address the research gap by utilizing hydrological connectivity assessments to strategically place wetlands for sediment control, water retention, and flood mitigation, thereby supporting urban adaptability and sustainability goals.  The research applied a combination of hydrological modeling and Geographic Information Systems to evaluate urban catchments for potential wetland sites. It involved the development and application of a revised connectivity index that incorporates multiple factors including land use, soil type, topography, and rainfall-runoff dynamics. The study areas were selected based on their diverse urban and agricultural characteristics to provide an understanding of different urban catchment dynamics. The methodology included detailed mapping of sediment connectivity using advanced GIS techniques and the integration of environmental and hydrological data to model the effects of various connectivity scenarios on potential wetland performance.  The findings demonstrated that the connectivity index model effectively identifies locations within catchments that benefit from wetland implementation. Areas characterized by specific roughness and runoff properties were pinpointed as optimal for managing sediments effectively. Comparative analyses of different hydrological models highlighted how variations in sediment connectivity could influence the strategic placement of wetlands, thereby optimizing their ecological and hydrological benefits. The research also quantified the potential impacts of newly introduced wetlands on the local hydrological connectivity and explored their broader implications, evaluating effects both upstream and downstream of the implementation site, showcasing significant benefits in terms of sediment retention and flood mitigation. The study suggests that the thoughtful placement of wetlands, informed by thorough hydrological connectivity assessments, has the potential to enhance the adaptability of the built environment to climate change effects. Such optimized placement might effectively address challenges related to flood and sediment management and could support sustainable urban development by incorporating ecological aspects into urban planning. / Stadsutvidgning och klimatförändringar förstärker miljöutmaningar och gör traditionella ingenjörslösningar för vattenhantering och översvämningsreducering alltmer ineffektiva och ekonomiskt ohållbara. Naturbaserade lösningar, såsom våtmarker, får ökad uppmärksamhet för sin potential att erbjuda hållbara alternativ genom naturlig vattenhantering och stöd till biologisk mångfald. Trots sina fördelar är den strategiska placeringen av våtmarker inom urbana landskap dåligt förstådd, särskilt när det gäller dynamiskt flöde av vatten och sediment genom landskapet. Studien syftade till att utveckla en optimerad ram för strategisk placering av våtmarker i urbana områden för att förbättra hydrologisk stabilitet och anpassningsförmåga. Den strävade efter att täcka forskningsgapet genom att använda bedömningar av hydrologisk konnektivitet för att strategiskt placera våtmarker för sedimentkontroll, vattenretention och översvämningsminskning, därigenom stödja städers anpassningsförmåga och hållbarhetsmål.  Forskningen tillämpade en kombination av hydrologisk modellering och geografiska informationssystem för att utvärdera urbana avrinningsområden för potentiella våtmarksplatser. Den involverade utvecklingen och tillämpningen av ett reviderat konnektivitetsindex som integrerar flera faktorer inklusive markanvändning, jordart, topografi och nederbörds-avrinningsdynamik. Studieområdena valdes utifrån deras mångfaldiga urbana och jordbruksmässiga egenskaper för att ge en förståelse för olika urbana avrinningsdynamiker. Metodologin inkluderade detaljerad kartläggning av sedimentkonnektivitet med avancerade GIS-tekniker och integration av miljö- och hydrologiska data för att modellera effekterna av olika konnektivitetsscenarier på potentiell våtmarksprestanda.  Resultaten visade att konnektivitetsindexmodellen effektivt identifierar platser inom avrinningsområden som gynnas av våtmarksetablering. Områden som kännetecknas av specifika grovhetsegenskaper och avrinningsegenskaper pekades ut som optimala för effektiv sedimenthantering. Jämförande analyser av olika hydrologiska modeller belyste hur variationer i sedimentkonnektivitet kunde påverka den strategiska placeringen av våtmarker, därigenom optimering av deras ekologiska och hydrologiska fördelar. Forskningen kvantifierade även potentiella effekter av nyintroducerade våtmarker på lokal hydrologisk konnektivitet och utforskade deras bredare implikationer, genom att utvärdera effekter både uppströms och nedströms om implementeringsplatsen och visa på betydande fördelar när det gäller sedimentretention och översvämningsskydd. Studien antyder att genomtänkt placering av våtmarker, informerad av noggranna bedömningar av hydrologisk konnektivitet, har potential att förbättra byggd miljös anpassningsförmåga till klimatförändringseffekter. En sådan optimerad placering kan effektivt hantera utmaningar relaterade till översvämningar och sedimenthantering och kan stödja hållbar stadsutveckling genom att integrera ekologiska aspekter i stadsplaneringen.

Mobile Ad Hoc Networks (MANETs) are a class of infrastructure less network architecture which are formed by a collection of mobile nodes that communicate with each other using multi-hop wireless links. They eliminate the need for central management, hence each node must operate cooperatively to successfully maintain the network. Each node performs as a source, a sink and a router. Future applications of MANETs are expected to be based on all-IP architecture, carrying a multitude of real-time multimedia applications such as voice, video and data. It would be necessary for MANETs to have an efficient routing and quality of service (QoS) mechanism to support diverse applications. This thesis proposes a set of cooperative protocols that provide support for QoS routing. The first is the on-demand, Non-Disjoint Multiple Routes Discovery protocol (NDMRD). NDMRD allows the establishment of multiple paths with node non-disjoint between source and destination node. It returns to the source a collection of routes with the QoS parameters. The second part of the protocol is the Node State Monitoring protocol for the purpose of monitoring, acquisition, dissemination and accumulation of QoS route information. The third part of the protocol implements the QoS route selection based on a Genetic Algorithm. The GA is implemented online with predetermined initial population and weighted-sum fitness function which operates simultaneously on the node bandwidth, media access delay, end to end delay and the node connectivity index (NCI). The term node connectivity index is a numerical value designed to predict comparatively the longest time a node-pair might be connected wirelessly.