Dissertationen zum Thema „Connectivity infrastructure“

For the last century, automobiles and the roads they require have been a dominant force shaping the modern American landscape. An unrivaled interstate highway system connects major metropolitan areas and is the basis of our transportation infrastructure. Unfortunately, many roadways were not planned or designed with wildlife in mind. As long linear features in the landscape, interstates can function as landscape barriers and cause significant impacts to adjacent wildlife populations. While an aggressive transportation system is being carried out, researchers have only marginally demonstrated the relationships between roadways and wildlife. In such cases, twinned interstate roadways have proven to be the greatest obstacle for wildlife resources. By incorporating ecological design theory into highway planning and design, the transportation community has an opportunity to reassess the short comings of existing highway infrastructure and improve functions of wildlife passage and landscape connectivity. Through system level approaches and analysis applied within an eco-region context, practical solutions can be developed. The following document provides a process for landscape level analysis, wildlife passage structure design and implementation for future planned interstates projects. As a collaborative effort among professionals, we can work towards improving interstate highway systems and retain the relationships occurring within the landscape. The following I-81 design and planning project offers an exceptional opportunity to reassess the inadequacies of the existing interstate infrastructure in terms of landscape connectivity, wildlife resources and public safety, and demonstrate how system level design approaches can give our roadways new shape and form.<br>Master of Landscape Architecture

Manufacturers have begun to realize that in order to have factories which are adapted to the contemporary conditions required for having state of the art manufacturing, the fixed network cables should be replaced by wireless communication with higher capacity. Cellular connectivity has this ability, but to be able to deliver it to manufacturing factories, they would benefit from establishing a suitable ecosystem design for the technology. The purpose of this research paper is to investigate how infrastructure developing telecom companies can work to establish this business ecosystem for cellular connectivity in manufacturing factories and make sure they remain competitive over time. The purpose was fulfilled using a qualitative case study consisting of 20 semi-structured interviews, conducted at a case company. The case study was complemented with a quantitative study to understand the status of current relationships in the ecosystem. Results of the study indicate that: • As cellular connectivity for manufacturing factories is in an early stage of its life cycle, it is of more importance to convince customers of the technology’s benefits, in order to get a market pull, rather than promoting the own product. • A competitive advantage may not be yielded through getting a minimum viable product to the market in the sense of learning about components and complements. However, the minimum viable product should give rise to an opportunity to establish key relationships and experience across the entire ecosystem. • Relationships to all business partners in the ecosystem are considered important. However, the relationships differ in strength, as they are at different maturity stages and needs various amounts of attention and resources. Accordingly, some effort needs to be put into all relationships, but making sure to understand the optimal amount of attention and resources for each relationship may facilitate the choosing of appropriate effort levels.<br>Tillverkande fabriker har börjat inse att de fasta nätverkskablarna borde ersättas med trådlös kommunikation med högre kapacitet, för att deras fabriker ska vara anpassade till dagens förhållanden som krävs för toppmodern tillverkning. Cellulär uppkoppling har denna förmåga, men för att leverera tekniken till tillverkande fabriker borde en lämplig ekosystem-design etableras. Syftet med denna studie är att undersöka hur infrastrukturutvecklande telekomföretag kan arbeta för att etablera detta ekosystem för cellulär uppkoppling i tillverkande fabriker samt se till att vara konkurrenskraftiga över tid. Syftet uppnåddes genom en kvalitativ fallstudie bestående av 20 halvstrukturerade intervjuer som genomfördes på ett företag. Fallstudien kompletterades med en kvantitativ studie för att förstå statusen på nuvarande relationer i ekosystemet. Studiens resultat påvisar att: • Eftersom cellulär uppkoppling för fabriker är i ett tidigt skede av sin livscykel så är det av större betydelse att övertyga kunder om teknikens fördelar för att expandera marknaden snarare än att främja företagets egen produkt. • Vart eftersom tekniken mognar är det viktigt att ha en differentieringsstrategi, för att få en tillfredsställande marknadsandel. En konkurrensfördel uppnås inte garanterat genom komponenter och komplement via att företaget får ut en tidig fungerande produkt på marknaden. Den tidigt fungerande produkten bör dock ge upphov till en möjlighet att etablera viktiga relationer och erfarenheter över hela ekosystemet. • Affärsrelationer till alla parter i ekosystemet anses vara viktiga. Relationerna skiljer sig åt i styrka, eftersom de befinner sig i olika mognadsfaser och behöver olika mängder uppmärksamhet och resurser. Följaktligen måste en viss ansträngning sättas in i alla relationer, men förståelse av den optimala mängden uppmärksamhet och resurser för varje relation kan underlätta valet av lämpliga insatsnivåer.

Industrial automation solutions have traditionally been differentiated and separated from one another by different incompatible and non-interoperable standards used for communication between devices. As a result, customers have often found themselves locked into proprietary ecosystems. Vendors have had to develop multiple versions of essentially the same product to support these ecosystems. Over the past few years a new driver has arisen to further bolster this device and system integration push: the Industrial Internet of Things (IIoT), which can be defined as the connection of devices through the internet in order to collect and share data without human assistance. Since there is no complete IIoT system on the market, the need to integrate a variety of different technologies remains a fact of the IIoT. This combination of different-vendor devices has been limiting innovation and integration of new solutions, with customers not being able to optimize their automation systems to its full value. Intregration of communication levels is an essential requirements for today's most advanced production systems. Furthermore, when it comes to complex processes with real-time requirements, communication standards have their own limitations. In order to face the issue presented, this thesis project will be focused on the study and analysis of a vendor-independent technology able to fulfill today's and tomorrow's industrial communication requirements, with particular focus on Time Sensitive Net- working (TSN) technology designed to face real-time demands.

Considering 91 countries with seaports, this study conducted an empirical inquiry into the broader economic contribution of seaborne trade, from a port infrastructure quality and logistics performance perspective. Investment in quality improvement of port infrastructure and its contribution to economy are often questioned by politicians, investors and general public. A structural equation model (SEM) is used to provide empirical evidence of significant economic impacts of port infrastructure quality and logistics performance. Furthermore, analysis of a multi-group SEM is performed by dividing countries into developed and developing economy groups. The results reveal that it is vital for developing countries to continuously improve the quality of port infrastructure as it contributes to better logistics performance, leading to higher seaborne trade, yielding higher economic growth. However, this association weakens as the developing countries become richer.

The aim of this research is to analyze the impact of the orbital motorway B-40 or fourth belt Barcelona in the polycentric urban structure of the Barcelona Metropolitan Region or (BMR). The changes discussed in this research are the result of distance variation between the different urban centers of the MRB and the transformation of mobility patterns. Infrastructure B-40 was initially called by roads planners as Fourth Ring Road Barcelona, later in the territorial it changed to a typology of orbital motorway and designated B-40. The name of B-40 Motorway corresponds to its ability to bind different urban systems of the Vallès Oriental, Vallès Occidental and Baix Llobregat setting up a metropolitan corridor in the sector known as second crown of Barcelona. This infrastructure has appeared in different planning documents for fifty years and now is under construction. In this research, the layout of the B-40 proposed in the Territorial Metropolitan Plan (PTMB) is evaluated. The methodology developed is structured assuming that the level of Polycentricity depends on the size and location of the centers (morphological polycentrism) and relations between them (functional polycentrism). Polycentrism is evaluated for two different situations with (current situation ) and without (future situation) path and for three different periods. Polycentrism change is evaluated through a set of indicators use information flows between urban centers. Mobility flows for different situations and periods are estimated using a origin constrain gravity model in which the impedance function is the matrix of minimum distances. The research used Green index (the special functional polycentricity of the urban network), the indicator Potential Accessibility (commuting is used as an activity function, and minimum distances matrix as an impedance function), Shannon entropy index (use the LTL information) and a series of territorial indicators that facilitate interpretation of the results. The results obtained indicate that the morphological characteristics of the territorial system not present modifications at short notice by insertion of a road. However, functional relationships show that the process of decentralization of the activity to other crowns of the BMR. The B-40 structure, a road corridor which spatial modifies the sector of the AP-7 at Vilafranca where the municipalities of small size and demographic weight experience changes in accessibility. Another area where important changes are observed corresponding to the outermost municipalities Vallès Oriental. In the area of Maresme, the influence of the B-40 is moved to the furthest municipalities of Mataró. The Garraf area, presents significant changes in connectivity relationships between its main sub center Vilanova I la Geltrú and the surrounding municipalities. At a general level, it is seen that the biggest effect of the B-40 is produced in the interior of the BMR, at the level of the coastline municipalities experience few modifications.<br>El objetivo de esta investigación es analizar el impacto de la autovía B-40 o cuarto cinturón de Barcelona en la estructura urbana policéntrica de la Región Metropolitana de Barcelona (RMB). Particularmente, se cuantificó y analizó el cambio en el policentrismo generado por la construcción de la B-40 a partir de los cambios en la distancia y la modificación de las relaciones funcionales producidas por la variación de los patrones de movilidad. La infraestructura analizada inicialmente fue denominada por los planificadores de carreteras como Cuarto Cinturón de Ronda de Barcelona. Posteriormente se considera en la planificación territorial y se designa de acuerdo a su tipología como Autovía Orbital B-40 o Ronda del Vallès. Esa nueva clasificación corresponde a su capacidad para articular los diferentes sistemas urbanos de la comarca del Vallès Oriental, Occidental y del Baix Llobregat y configura un corredor metropolitano en el sector denominado segunda corona de Barcelona. Esta infraestructura aparece en diferentes documentos de planificación desde hace cincuenta años y actualmente se encuentra en proceso de construcción. Para este estudio se analiza el trazado de la B-40 propuesto en el Plan Territorial Metropolitano de Barcelona (PTMB). La metodología formulada está estructurada asumiendo que el nivel de policentrismo depende del tamaño y localización de los centros (policentrismo morfológico) y de las relaciones entre ellos (policentrismo funcional). El policentrismo se evalúa para dos situaciones diferentes denominadas sin (situación actual) y con (situación futura con B-40) y para tres periodos temporales. El analisis se realiza a través de una serie de indicadores que utilizan la información de los flujos de movilidad entre los diferentes municipios. La movilidad para los diferentes periodos se estima empleando un modelo de interacción espacial de tipo gravitatorio acotado en origen que utiliza como función de impedancia la matriz de distancias mínimas (sin y con) y la matriz de movilidad laboral para el periodo específico de análisis. En esta investigación para evaluar el policentrismo se utiliza el indicador de Green, el indicador de Potencial de Accesibilidad, el indicador de Entropía de Shannon y una serie de indicadores de tipo territorial que permiten la interpretación de los resultados obtenidos. Los resultados obtenidos señalan que las características morfológicas del sistema territorial no presentan modificaciones a corto plazo por la inserción de un eje viario. En cuanto a las relaciones de tipo funcional estas denotan que se está produciendo paulatinamente un proceso de descentralización de la actividad hacia las coronas más exteriores de la RMB. También, se constata que a pesar, de la disminución en su capacidad de oferta y retención de la actividad Barcelona sigue siendo el principal centro de empleo del ámbito de estudio. Asimismo, la B-40 estructura un corredor viario que modifica espacialmente el sector de la AP-7 a la altura de Vilafranca donde los municipios de pequeñas dimensiones o de poco peso demográfico experimentan importantes cambios en accesibilidad. Otro sector donde se aprecian importantes cambios corresponde a los municipios más externos del Vallès Oriental. En el sector del Maresme, la influencia de la B-40 se traslada a los municipios más alejados de Mataró. En el sector del Garraf, se aprecian importantes modificaciones en las relaciones de conectividad que se producen entre Vilanova i la Geltrú y los municipios de su entorno. A nivel general se aprecia que el mayor efecto de la B-40 se produce en la zona ubicada entre de 30 y 40 Km de Barcelona. Para el caso especifico de Barcelona y su continu urbano los principales cambios en este sector se producen en los municipios de menores dimensiones y peso demográfico. Los grandes municipios no experimentan cambios significativos en movilidad, tampoco en accesibilidad.

A functionally connected urban tree infrastructure (UTI) contributes to ecosystem function, resilience, and the provision of Ecosystem Services (ES). Variation in tree height is an important attribute influencing movement of passerines, habitat quality and landscape patterns. UTI provided ES are particularly beneficial in the most deprived areas of a city. Presented in this thesis is an exploration into the social-ecological shape of a UTI using a holistic, multi-scale and dimensional, landscape approach. The potential landscape connectivity of a UTI in the City of Salford, UK was quantified and compared using the integral index of connectivity (IIC) across vertically stratified canopies existing in 2005, 2009, and 2013. System resilience was assessed through landscape graph network analysis and by the identification of canopies critical in maintaining connectivity (dIIC). The index of multiple deprivation (IMD) was related to UTI landscape composition and configuration through a series of statistical tests. The connectivity of Salford’s vertically stratified UTI was low (IIC = <0.000001 – 0.0045), besides this the temporal change in connectivity was complex with no discernible overall pattern. The rate of connectivity increase decreased after a 90-120m gap-crossing threshold. The resilience of Salford’s UTI relies on the connectivity of canopies within 4 to 5 sub-connected regions, depending on passerine perception, increasing to 10 -16 smaller regions for canopies above 17.1m. The resilience and stability of these sub-connected regions were often reliant on a central canopy patch. UTI composition is related negatively with deprivation, UTI configuration is related positively, while structural diversity of canopy heights revealed no correlation with deprivation. The research in this thesis contributes to the debates on how to best manage the UTI for both people and nature. The findings of this thesis have a number of important implications for future urban landscape management, especially as previously unknown landscape patterns have been identified.

Background: The world of today is immensely interconnected. Over the past decades, national economies have been de-bordered and the promoting of the flows of goods, people, capital and services across the borders is evident, as opposed to when flows only moved within national economies. Former vertical structures of old nations have been replaced by a horizontal flow structure in a complex and intertwined global economy. Attracting flows is essential for the growth and survival of cities. Hubs functions as important connection points for these flows and are therefore highly important. Research procedure: The purpose of this thesis is to describe how city regions function from a hub perspective by mapping the most important hubs in the Oresund Region, and investigating the connectivity and collaboration between these hubs. This study has a qualitative and inductive approach with a case study design and the empirical findings is based on twelve interviews with representatives of different fields. Results: The most important hubs were divided into three categories: transport, economic and infrastructure hubs, illustrated in the hub categorization model. The results indicate that there is a interconnectivity issue with interdependencies between the different hubs in the Oresund Region. This is illustrated through the hub relationship model. Collaboration seems to take place mostly within sectors and through the municipalities..

Le principe de l'Internet des objets (IdO) est d'interconnecter non seulement les capteurs, les appareils mobiles et les ordinateurs, mais aussi les particuliers, les maisons, les bâtiments intelligents et les villes, ainsi que les réseaux électriques, les automobiles et les avions, pour n'en citer que quelques-uns. Toutefois, la réalisation de la connectivité étendue de l'IdO tout en assurant la sécurité et la confidentialité des utilisateurs reste un défi. Les systèmes IdO présentent de nombreuses caractéristiques non conventionnelles, telles que l'évolutivité, l'hétérogénéité, la mobilité et les ressources limitées, qui rendent les solutions de sécurité Internet existantes inadaptées aux systèmes basés sur IdO. En outre, l'IdO préconise des réseaux peer-to-peer où les utilisateurs, en tant que propriétaires, ont l'intention d'établir des politiques de sécurité pour contrôler leurs dispositifs ou services au lieu de s'en remettre à des tiers centralisés. En nous concentrant sur les défis scientifiques liés aux caractéristiques non conventionnelles de l'IdO et à la sécurité centrée sur l'utilisateur, nous proposons une infrastructure sécurisée de l'IdO activée par la technologie de la chaîne de blocs et pilotée par des réseaux peer-to-peer sans confiance. Notre infrastructure sécurisée IoT permet non seulement l'identification des individus et des collectifs, mais aussi l'identification fiable des objets IoT par leurs propriétaires en se référant à la chaîne de blocage des réseaux peer-to-peer sans confiance. La chaîne de blocs fournit à notre infrastructure sécurisée de l'IdO une base de données fiable, immuable et publique qui enregistre les identités individuelles et collectives, ce qui facilite la conception du protocole d'authentification simplifié de l'IdO sans dépendre des fournisseurs d'identité tiers. En outre, notre infrastructure sécurisée pour l'IdO adopte un paradigme d'IdO socialisé qui permet à toutes les entités de l'IdO (à savoir les individus, les collectifs, les choses) d'établir des relations et rend l'IdO extensible et omniprésent les réseaux où les propriétaires peuvent profiter des relations pour définir des politiques d'accès pour leurs appareils ou services. En outre, afin de protéger les opérations de notre infrastructure sécurisée de l'IdO contre les menaces de sécurité, nous introduisons également un mécanisme autonome de détection des menaces en complément de notre cadre de contrôle d'accès, qui peut surveiller en permanence le comportement anormal des opérations des dispositifs ou services<br>The premise of the Internet of Things (IoT) is to interconnect not only sensors, mobile devices, and computers but also individuals, homes, smart buildings, and cities, as well as electrical grids, automobiles, and airplanes, to mention a few. However, realizing the extensive connectivity of IoT while ensuring user security and privacy still remains a challenge. There are many unconventional characteristics in IoT systems such as scalability, heterogeneity, mobility, and limited resources, which render existing Internet security solutions inadequate to IoT-based systems. Besides, the IoT advocates for peer-to-peer networks where users as owners intend to set security policies to control their devices or services instead of relying on some centralized third parties. By focusing on scientific challenges related to the IoT unconventional characteristics and user-centric security, we propose an IoT secure infrastructure enabled by the blockchain technology and driven by trustless peer-to-peer networks. Our IoT secure infrastructure allows not only the identification of individuals and collectives but also the trusted identification of IoT things through their owners by referring to the blockchain in trustless peer-to-peer networks. The blockchain provides our IoT secure infrastructure with a trustless, immutable and public ledger that records individuals and collectives identities, which facilitates the design of the simplified authentication protocol for IoT without relying on third-party identity providers. Besides, our IoT secure infrastructure adopts socialized IoT paradigm which allows all IoT entities (namely, individuals, collectives, things) to establish relationships and makes the IoT extensible and ubiquitous networks where owners can take advantage of relationships to set access policies for their devices or services. Furthermore, in order to protect operations of our IoT secure infrastructure against security threats, we also introduce an autonomic threat detection mechanism as the complementary of our access control framework, which can continuously monitor anomaly behavior of device or service operations

Le développement d'infrastructures linéaires de transport conduit, à toutes les échelles, à une artificialisation du territoire et au morcellement du milieu naturel. La fragmentation du paysage est un processus spatial qui s'accompagne d'une diminution progressive de la connectivité entre les différents éléments nécessaires au bon déroulement des processus écologiques. Ainsi, le maintien d'un bon niveau de connectivité entre les habitats naturels, s'il est compatible avec les activités humaines, est devenu un enjeu majeur pour la préservation de la biodiversité. En mobilisant des méthodes empruntées à la théorie des graphes et à l'écologie du paysage, la thèse cherche à démontrer l'intérêt de la modélisation des réseaux écologiques par les graphes paysagers, dans l'analyse des impacts des infrastructures à l'échelle régionale. Cette démarche, fondée sur la modélisation, a permis de démontrer l'influence du réseau écologique du chevreuil dans la localisation des collisions entre les individus de cette espèce et les véhicules empruntant le réseau de la DIR est en Franche-Comté. Le travail a également permis de proposer un cadre méthodologique pour localiser l'impact potentiel de la branche est de la LGV Rhin-Rhône sur la distribution d'une espèce, et estimer la distance de perturbation de cette infrastructure. Enfin, deux démarches sont proposées pour évaluer quantitativement et hiérarchiser des aménagements afin d'éviter ou d'atténuer ces impacts. Les résultats montrent la pertinence de l'intégration des réseaux écologiques dans les études d'impacts des infrastructures de transport.

In recent years, a great deal of attention has been given to wireless connectivity solutions that are capable of establishing wireless ad-hoc networks between mobile nodes. Whilst most of these networks are formed using a combination of fixed and mobile infrastructure, completely infrastructure-less networks are thought to become more commonplace in the future. Moreover, this type of network structure seeks to utilise multi-hop connectivity between mobile nodes rather than the traditional single-hop connectivity established between fixed access points.The initial configuration phase and subsequent maintenance phase of a multi-hop wireless ad-hoc network requires the use of appropriate routing functions to exist between the mobile nodes. Therefore, it is essential that a routing protocol capable of determining correct and optimal routing path information in the presence of node mobility and the mobile radio environment be sought. Furthermore, it is beneficial to utilise the limited wireless bandwidth efficiently, such that a routing protocol should be designed specifically in the context of a multi-hop wireless ad-hoc network topology. This can be achieved through employing a non-hierarchical approach and using neighbouring nodes to act as intermediate relay nodes.The proposed routing protocol, called the Multi-hop Wireless Ad-hoc Routing Protocol (MultiWARP), is comprised of both a proactive and reactive routing component, thus forming a hybrid protocol which is able to exploit the benefits of each component. It is shown that manipulating these two components within the context of an awareness region, which divides the network into 2 regions, the routing overhead can be minimised. For the proactive component, the necessary network topology information that must be transmitted between neighbouring nodes is encoded within a routing update (RUPDT) packet. In this study, three alternative RUPDT encoding schemes have been formulated to encode the network topology in an efficient manner to reduce the RUPDT packet size.For the reactive component, a novel covercasting mechanism is designed that minimises the number of route request (RREQ) transmissions required to determine the routing path by utilising existing routing table information. Supplementary techniques are then utilised, such as snooping, route repair, and route optimisation to further optimise performance and minimise the route discovery delay (latency). This same covercasting mechanism is then utilised to efficiently transmit periodic RUPDT packets between neighbouring nodes to maintain routing table validity at each node, without having to resort to flooding which causes the “broadcast storm problem”. In addition, several route selection algorithms are considered which distribute traffic data between the intermediate relay nodes comprising the ad-hoc network.The performance and computational complexity of the proposed hybrid routing protocol is shown by means of computer simulations and theoretical analysis. Various traffic scenarios and topologies are presented to obtain the routing protocol performance metric results, and these are compared with other protocols found in the literature. For a multi-hop wireless ad-hoc network, it is shown that the proposed hybrid routing protocol, MultiWARP, is able to achieve higher average system performance in terms of improved throughput and stability performance when compared to other wireless ad-hoc routing protocols, such as DSR.

Avec une population dépassant les 1,4 milliard d'habitants, faisant ainsi de l'Afrique le deuxième continent le plus peuplé au monde après l'Asie, la contribution de ce continent au commerce mondial demeure modeste. La littérature économique identifie divers facteurs contribuant à la marginalisation des nations africaines dans le commerce mondial, notamment un déficit de compétitivité. S'appuyant sur la littérature existante et reconnaissant l'absence de solution universelle, cette thèse explore, à travers ses trois chapitres, les voies qu'offrent la compétitivité prix et hors prix pour une meilleure intégration des nations africaines au commerce mondial. Le premier chapitre s'intéresse à la mesure de la compétitivité des prix, en examinant spécifiquement la compétitivité du franc CFA à travers le prisme du taux de change d'équilibre comportemental (BEER) et de la parité du pouvoir d'achat (PPA). Une contribution notable réside dans la prise en compte des rentes naturelles, particulièrement importantes dans le contexte des pays africains. Les résultats soulignent des disparités entre les unions monétaires (UEMOA et CEMAC), les sous-périodes et les pays considérés. L'analyse des résultats en fin de la période 2014-2016 n'appelle pas à un réajustement de la parité. Le deuxième chapitre explore l'impact de la sous-évaluation des taux de change sur la survenue d'épisode d'accélérations de croissance des exportations de produits africains. L'analyse englobe une variété de produits d'exportation clés, tant primaires que manufacturés, avec une approche microéconomique unique adaptée à chaque produit. Sur la période 1995-2017, 96 épisodes sont identifiés pour 41 pays africains. Les estimations confirment que la sous-évaluation stimule significativement les poussées de croissance d'exportations des produits africains. Le troisième et dernier chapitre se concentre sur la compétitivité hors prix, en explorant les implications du déploiement rapide des câbles sous-marins le long des côtes africaines pour la sophistication du panier d'exportations des pays africains. A partir d'un échantillon de pays en développement, incluant 23 pays d'Afrique subsaharienne sur la période 1995-2017, les résultats indiquent que l'interconnectivité numérique améliore globalement la complexité des exportations. L'impact positif décroît avec l'accroissement des distances géographiques et maritimes par rapport aux marchés mondiaux, sauf en Afrique subsaharienne, où ces distances amplifient les avantages de l'interconnectivité numérique. Une exploration des mécanismes à l'origine du processus de sophistication des exportations induit par l'interconnectivité numérique a mis en évidence une augmentation des exportations de biens différenciés et une participation accrue aux chaînes de valeur mondiales<br>With a population of over 1.4 billion, making Africa the world's second most populous continent after Asia, its contribution to world trade remains modest. Economic literature identifies several factors contributing to the marginalization of African nations in world trade, including a lack of competitiveness. Drawing on the existing literature, and recognizing that there is no universal solution, this thesis explores, in three chapters, the ways in which price and non-price competitiveness can help African nations to integrate more fully into world trade. The first chapter looks at the measurement of price competitiveness, specifically examining the competitiveness of the CFA franc through the prism of the behavioral equilibrium exchange rate (BEER) and purchasing power parity (PPP). One notable contribution is the inclusion of natural rents, which are particularly important in African countries. The results highlight disparities between monetary unions (WAEMU and CEMAC), sub-periods and countries considered. Analysis of the results at the end of the 2014-2016 period does not call for a readjustment of parity. The second chapter explores the impact of undervalued exchange rates on the occurrence of episodes of accelerated growth in exports of African products. The analysis encompasses a variety of key export products, both primary and manufactured, with a unique microeconomic approach tailored to each product. Over the period 1995-2017, 96 episodes are identified for 41 African countries. Estimates confirm that undervaluation significantly stimulates growth surges in African export products. The third and final chapter focuses on non-price competitiveness, exploring the implications of the rapid deployment of submarine cables along African coasts for the sophistication of African countries' export baskets. Based on a sample of developing countries, including 23 Sub-Saharan African countries over the period 1995-2017, the results indicate that digital interconnectivity improves export sophistication overall. The positive impact decreases with increasing geographical and maritime distances from world markets, except in sub-Saharan Africa, where these distances amplify the benefits of digital interconnectivity. An exploration of the mechanisms underlying the process of export sophistication induced by digital interconnectivity highlighted an increase in exports of differentiated goods and greater participation in global value chains

Secure mobile apps, including end-to-end encrypted messaging apps such as Whats-App and Signal, are increasingly popular today. These apps require trust in a centralized key directory to automatically exchange the public keys used to secure user communication. This trust may be abused by malicious, subpoenaed, or compromised directories. A public key infrastructure (PKI) solution that requires less trust would increase the security of these commonly used apps.CONIKS is a recent PKI proposal that features transparent key directories which publish auditable digests of the public keys they present to queriers. By monitoring its key every time a new digest is published, a client can verify that its key is published correctly, reducing the need to trust the directory. CONIKS features improved security at the cost of unique auditing and monitoring requirements. In this thesis, we examine CONIKS' suitability as a PKI solution for secure mobile apps. We present a threat analysis of possible attacks on the CONIKS protocol and explore several important implications of CONIKS' system description, including recommendations for whistleblowing and key change policies. We also analyze mobile device usage data to estimate whether typical mobile device Internet connectivity is sufficient to fulfill CONIKS' monitoring requirement.

La mise en place des réseaux de continuités écologiques dans les paysages nécessite l'estimation de la connectivité fonctionnelle, particulièrement lorsque ces paysages sont fragmentés par les Infrastructures Linéaires de Transport (ILT). Dans ce contexte, des suivis génétiques et démographiques ont été réalisé sur quatre espèces terrestres dans un paysage fragmenté par six types d'infrastructures en Dordogne, France. Les résultats ont montré qu'une part importante de la variabilité génétique (38 %) est expliquée par les ILT, qui agissent majoritairement comme des barrières à la dispersion. Cependant, les effets des ILT varient fortement d'une espèce à l'autre et peuvent, dans certains cas, agirent comme des éléments favorisant la dispersion. Par ailleurs, l'utilisation conjointe des outils de génétique du paysage et des suivis démographiques montre que selon l'approche utilisée, les résultats peuvent diverger. Ces deux approches devraient donc être davantage utilisées simultanément dans les études paysagères<br>Implementing networks of ecological continuities requires estimation of functional connectivity in landscapes. Particularly when those landscapes are fragmented by Large-scale Transportation Infrastructures (LTIs). In this context, four terrestrial species were monitored using genetic and demographic surveys across six LTIs in south-western France. The results showed that a significant amount of genetic variability was explained by LTIs (38%), that are mostly acting as dispersal barriers. However, LTI effects are variable depending on the species under study and, in some cases, they can even act as infrastructures enhancing dispersal. Furthermore, the combined use of genetic tools and demographic surveys showed that depending on the selected approach, results might differ. Therefore, these two approaches should be more used simultaneously in landscape surveys

Climate changes are predicted to increase precipitation intensities and occurrence of extreme rainfall events in the near future. Scandinavia has been identified as one of the most sensitive regions in Europe to such changes; therefore, an increase in the risk for flooding, landslides and soil erosion is to be expected also in Sweden. An increase in the occurrence of extreme weather events will impose greater strain on the built environment and major transport infrastructures such as roads and railways. This research aimed to identify the risk of flooding at the road-stream intersections, crucial locations where water and debris can accumulate and cause failures of the existing drainage facilities. Two regions in southwest of Sweden affected by an extreme rainfall event in August 2014, were used for calibrating and testing a statistical flood prediction model. A set of Physical Catchment Descriptors (PCDs) including road and catchment characteristics was identified for the modelling. Moreover, a GIS-based topographic Index of Sediment Connectivity (IC) was used as PCD. The novelty of this study relies on the adaptation of IC for describing sediment connectivity in lowland areas taking into account contribution of soil type, land use and different patterns of precipitation during the event. A weighting factor for IC was calculated by estimating runoff calculated with SCS Curve Number method, assuming a constant value of precipitation for a given time period, corresponding to the critical event. The Digital Elevation Model of the study site was reconditioned at the drainage facilities locations to consider the real flow path in the analysis. These modifications led to highlight the role of rainfall patterns and surface runoff for modelling sediment delivery in lowland areas. Moreover, it was observed that integrating IC into the statistic prediction model increased its accuracy and performance. The calibrated model was then validated in another area, located in the central part of Sweden, affected by severe rainfall event in August 2004, in order to verify its robustness even in ungauged catchments.

The aim ofthis thesis is to create an analytical framework to understand the specificity and potential of these areas from a critical view of the current extensive growth model operating on the territory, which is performing strategic areas that can offer instrumental knowledge useful for the project in the contemporary city. As an alternative to the reductionism or the lack of flexibility and excessive spatial determinism that often characterize this type of spaces, thes thesis proposes an alternative vision based on a carfeul reading of the specific elements and its resources (the specificity of the precedent) as well as the understanding and use of its proven potential resistance in front of the dynamics established (marginal value) states the criteria and develops the intervention guidelines in from their recognition as areas critical to the recovery of the biophysical matrix and the orientation of post-industrial urban establisments, articulate their protection and promote the systematic destruction regular updating through an active and progressive incorporation into proceses of contemporary urban innovation.The thesis is divided into four main research parts. The first part aims to clarify the origins of the research and the decisive moments of change. To grasp today's potential, infrastructural voids need to be analyzed and understood before the developing role of the transportation and telecommunication infrastructures in shaping the contemporary city and the dynamics that have generated their evolution. That is why the impact is analyzed in the context of technological advances in urban ideology and configured to set up a tradition based analysis(2.Background). The second part, once introduced in its specific research topic, and having a certain state of affairs, aims to find conceptual parameters and operational strategies to objectify precisely the framework of the research (3. Conclusions : conceptual parameters , operational strategies). The third part is based on the assumptions set out in the second and with the intention of verifying its validity, and consist in the application of conceptual parameters as research tools in selected opertional strategies (4. Strategic Sample Applications). Finally, the fifth part is the application of conceptual parameters as instruments of research in a case study, Barcelona, with the aim ofverifying its real potential (5. Barcelona. Aspecific application).<br>L'objectiu de la tesi és analitzar la especificitat i el potencial deis buits infraestructurals des d'una visió crítica envers el model operatiu vigent de creixement urbà extensiu sobre el territori, interpretant que es tracta d'espais estrategics que poden proporcionar un coneixement instrumental de gran valua pel projecte alternatiu de la ciutat contemporània. Com alternativa al reduccionisme programàtic o bé a la manca de flexibilitat i l'excés de determinisme espcial que sovint caracteritzen aquest tipus d'espais , la tesi proposa una visió alternativa que, basada en una lectura atenta i específica dels elements existents i dels seus recursos (la específicitat dels seus precedents) així com en l'enteniment i l'aprofitament del seu demostrat potencial de resistència enfront de les dinàmiques establertes (valor de marginalitat), sàpiga elaborar aquells criteris i aquelles pautes d'intervenció que, a partir del seu reconeixement com a espais decisius per la recuperació de la matriu biofisica i per la reorientació deis establiments urbans post industrials , articulin la seva protecció davant la sistematica destrucció habitual i promoguin la seva actualització mitjançant una activa i progressiva incorporació als processos d'innovació urbana contemporanis. La tesi s'estructura entorn de 4 parts d'investigació principals. La primera part té com objectiu precisar quis són els orígens de recerca i alhora, i no menys important, quins són els moments de canvi decisius relatius a l'objecte de la tesi. Per poder copsar el potencial que tenen avui els espais buits postindustrials és necessari abans analitzar i entendre quin ha estat el rol que han desenvolupat les infraestructures de transport i telecomunicacions en la configuració de la ciutat contemporània i les dinàmiques qua han condicionat la seva evolució. És per això que s'analitza la incidència dels avenços tecnològics en la ideología de l'espai urbà i es configura una tradició propia per establir la base de l'analisi (2. Antecedents). La segona part, una vegada generada la tradició pròpia i específica de la recerca, i havent determinat un estat de la qüestió, permet determinar uns paràmetres conceptuals i unes estratègies operatives concretes que acoten i objectiven de forma precisa el marc de la recerca (3. Conclusions: parametres conceptuals , estratègies operatives). La tercera part, a partir de les premises establertes en la segona i amb la intenció de verificar la seva validesa, consisteix en la aplicació deis paràmetres conceptuals com instruments de recerca en les estratègies operatives seleccionades (4. Aplicacions estratègiques exemplars). Finalment, la cinquena part consisteix en la aplicació desl paràmetres conceptuals com instruments de recerca sobre el cas real de Barcelona, també amb l'objectiu de verificar el seu potencial real (5. Barcelona. Una aplicació singular).

Des solutions de vérification efficaces nous semblent indispensables afin d’assurer la continuité des services en place et le déploiement de nouveaux services dans les réseaux 5G. Cette problématique ne se limite pas aux techniques de vérification, nos travaux portent aussi sur la formalisation des besoins d'un service réseau complet. Nous avons travaillé sur un langage de programmation facilitant la vérification dans les contrôleurs SDN. Puis nous avons défini des contrats de comportement réseau afin de clarifier les propriétés à vérifier pour assurer le bon fonctionnement d'un service. Enfin nous avons étudié MANO pour proposer une extension du standard permettant de vérifier les configurations réseau au niveau de l'orchestrateur<br>We believe that effective verification solutions are essential to ensure the continuity of existing services and the deployment of new services in 5G networks. This problem is not limited to verification techniques, our work also concerns the formalization of needs of a complete network service. We worked on a programming language to facilitate verification in SDN controllers. Then we defined network behavior contracts to clarify the properties to be verified to ensure the proper functioning of a service. Finally, we studied MANO to propose an extension of the standard to check the network configurations at the orchestrator level

The world-wide intensification of agriculture has led to a decline in species richness due to land use change, isolation, and fragmentation of natural and semi-natural habitats in agricultural and forestry landscapes. As a consequence, there is a current landscape management focus on the importance of green infrastructure to mitigate biodiversity decline and preserve ecosystem functions e.g. pollination services and pest control. Even though intensification in agriculture has been ongoing for several hundreds of years, remnant habitats from earlier management practices may still be remaining with a surprisingly high plant richness. Preserving these habitats could help conserving plant species richness in agricultural landscapes, as well as other organisms that are dependent on plants for food and shelter. In this thesis I focus on two small remnant habitats; midfield islets and borders between managed forest and crop field in southeastern Sweden. In the past, both habitats were included in the grazing system and therefore often still have remnant population of grassland specialist species left today. I have used these two remnant habitats as model habitats to investigate the effect of landscape factors and local factors on species richness of plants, flower morphologies and plants with fleshy fruits. Additively, I analysed the effect of surrounding landscape and local openness on the functions; pollination success, biological pest control of aphids and seed predation on midfield islets. One of my studies showed that spatial distribution and size of the habitat affected plant species richness. Larger habitat size and higher connectivity between habitats increased species richness of plants in the habitats. Openness of the habitats was shown to be an important factor to increase species richness and richness of flower morphologies, both on midfield islets and in forest borders. Even though midfield islets had the highest species and morphology richness, both habitat types are needed for habitat complementary as forest borders have more plants with fleshy fruits and a higher richness of plant species that flowers in spring/early summer. It was also shown that a more complex forest border, not just with gaps in the canopy, but also with high variation in tree stem sizes increases plant species richness in the field layer. The conclusion is that by managing small remnant habitats to remain or become more semi-open and complex in their structure, would increase species richness of plants, grassland specialist species, and flower morphologies. It would also increase some ecosystem functions as seed predation and biologic pest control of aphids are more effective close to trees. If both midfield islets and forest borders would be managed to be semi-open, the area and connectivity of semi-open habitat would increase in the agricultural landscape, which may also improve pollination success as the connectivity between populations has a possibility to increase. Grassland specialist species are clearly abundant in the small remnant habitats. As the decline of semi-natural grasslands is causing a decline in grassland specialists’ species, not only plants, I recommend that small remnant habitats are included in conservation and management plans and strategies to improve habitat availability and connectivity for grassland species in agricultural landscapes.<br><p>Research funder Ekoklim. Project:4339602.</p><p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

En milieu urbain, la concurrence entre les enjeux de préservation de la biodiversité et de la densification du territoire est particulièrement développée. Dans une optique d’aide à la décision, une meilleure connaissance des zones les plus conflictuelles est requise. Face au constat d’insuffisance et d’inadéquation des données et des méthodes nécessaires à la cartographie des Trames vertes urbaines, notre travail s’intègre en premier lieu dans une démarche technique. Celle-ci est centrée sur la mise en place d’une méthode de traitement d’images satellitaires Très Haute Résolution Spatiale Pléiades (THRS) pour l’extraction de la végétation arborée et herbacée à l’échelle fine d’une emprise urbaine. D’abord appliquée à des données fictives, cette méthode est ensuite déployée sur quatre territoires (Toulouse, Muret, Pierrefite-Nestalas et Strasbourg). Bien que fondée sur une approche pixel, la simplicité de la méthode, qui s’appuie sur des outils libres, et les résultats obtenus (indice Kappa supérieur à 85 %) garantissent sa reproductibilité sur de vastes territoires plus ou moins urbanisés. Cette donnée de végétation est ensuite exploitée pour modéliser les connectivités écologiques potentielles du paysage urbain et périurbain toulousain. L’approche mobilise la théorie des graphes et permet d’évaluer l’impact d’un aménagement urbain sur la biodiversité. Le cas du Boulevard Urbain Nord de Toulouse est étudié. La cartographie proposée des réservoirs de biodiversité, hiérarchisés à l’aide de métriques de connectivité, est avant tout indicative. Elle est finalement confrontée à des documents d’urbanisme (Plans Locaux d’Urbanisme) afin d’obtenir une meilleure visibilité des territoires à enjeux environnementaux et urbanistiques. En fonction des enjeux fixés par les acteurs du territoire et à travers le filtre applicatif, cette thèse propose un outil robuste d’analyse et d’aide à la décision pour la gestion et la planification du territoire<br>In urban areas, competition between land development and ecological conservation is intense. To assist decision making, a better knowledge of those areas of interest is required. Regarding inadequacy data and methods needed for ecological network mapping in urban areas, the aim of our study is to develop a method for semi-automatic vegetation extraction with Very High Spatial Resolution Pleiades imagery (VHSR). Initially applied to training samples, the process is then be deployed to four French study areas (Toulouse, Muret, Pierrefite-Nestalas and Strasbourg). The reproducibility of this method over large urbanized areas is ensured by its simplicity and the results of a pixel-based classification (kappa coefficient higher than 85 %). This extraction workflow uses free or open-source software. This vegetation data is then used in order to model potential ecological connectivity in Toulouse’s urban and peri-urban areas. Impacts on biodiversity due to urban planning are assessed using graph theory. The “Boulevard Urbain Nord de Toulouse” project, a road infrastructure, is studied. Graph metrics have been calculated to assess the level of connectivity at habitat patches and landscape scales. We classified the importance of the patches which is cross-tabulated with planning documents (PLU, a local town planning) in order to locate conflict urban areas: between biodiversity preservation and urbanization. Depending on the issues set out by local actors and through the application filter, this thesis proposes a robust analytical tool and decision-making aid for landscape management and land planning

The aim of this study is to conduct a thorough theoretical study on mobile learning (mlearning) in order to achieve the primary objective of the study which is to develop a general framework to implement and manage mobile technologies in a higher education environment. The focus of the literature study was to research the state of mobile technologies and their relevance to teaching and learning. The literature study investigate the implications of mobile technologies for students, lecturers and thus for the institution and provided an overview of frameworks found in literature with the emphasis on the management of m–learning within the higher education institution. M–learning is part of a new mobile conception of society, with the mobility of the technologies impacting on the mobility of the students, the lecturers and ultimately on the mobility of higher education. Literature suggests that, while m–learning is proving to be innovative, the factors that most strongly impact on the ultimate success or failure of mlearning will depend on human factors, the balancing of technological ideals and pedagogical imperatives, and the successful management of the interface between human educational systems and technology systems. The proposed general framework focuses on addressing key issues related to m–learning from the perspective of the student, the lecturer and thus the institution. In order to remain competitive higher education needs to be diligent in maintaining the complex technology infrastructure that supports a thriving mobile culture that will meet and exceed the expectations of both lecturers and students. The empirical research conducted had as objectives to investigate the mobile technology assets of respondents with regard to the hardware and the software that they own, the mobile technology actions of respondents in regard to what they do with the mobile technology that they own and to investigate the respondent's attitude towards mobile technologies. A survey was designed and distributed to a sampling of the academic staff and students of the North–West University (NWU) in South Africa, specifically the Potchefstroom Campus. There is ample proof from the empirical study that there is a gap with regard to the level of accessibility, usage, and attitude with regards to the different interest groups in the higher education environment. Higher education institutions should invest in investigating these gaps further and in leveraging off the benefits of the effective management of these technologies to improve teaching and learning. The final chapter concludes with a summary of the secondary objectives researched in the literature (Chapter two) and empirical research (Chapter three) chapters in order to support recommendations towards the primary objective of this study. The rapid pace of adoption and advancement of mobile technologies creates opportunities for new and innovative services provided through such mobile devices. Higher education finds itself in the early innings of the mobile Internet pulling both lecturers and students towards the same place: smaller, faster, cheaper devices working together in a web of connectivity. Recommendations were made in this final chapter on how higher education institutions can leverage the benefits of the effective management of mobile technologies to improve teaching and learning. M–learning has the potential to increase the capacity of higher education through improving efficiency and productivity of teaching and learning. Mlearning could address challenges related to quality of teaching such as continuous professional training, lifelong upgrading, connecting with academics worldwide and communicating effectively with students. Higher education is discovering the potential of mlearning to promote student engagement and improving the quality of learning. Management of higher education institutions and systems, management of policymaking including storage and analysis of data, construction and assessment of policy scenarios, and tracer studies or academic tracking systems can be improved through the use of m–learning. Mobile technologies will continue to increasingly become an integral part of students' and lecturers' private and day to day lives and m–learning will be integral in educational content delivery. Additional research is required to study the effective and optimal implementation of m–learning. A better understanding of the benefits and leverage thereof is required and additional research should provide answers to these questions.<br>Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

The relationship between transportation and economic development is well documented. Two requirements indispensable to this relationship are access (ability to reach a place) and connectivity (relationship of the place to others). The interaction of people and markets via transportation infrastructure facilitates trade and increased social interaction; all vital for development. This thesis examines the nature of access and connectivity of the multi-modal transport network (i.e. road, rail, water and air modes) of Northern Manitoba, a study area characterized by many small communities distributed in a vast area, with some having no year-round overland access, forcing them to rely on the seasonally constructed winter road system. Models of the four modal networks (graph theory) are used to analyze the transportation network’s structure, accessibility and connectivity for specific points in time with a view to understand network change. Recommendations are offered that would facilitate the integration of transportation planning.

This study aims to clarify the nature and characteristics of green infrastructure and green infrastructure planning; to identify general planning principles for green infrastructure; and to formulate pertinent research questions with respect to green infrastructure planning. A literature review and Berlin case study are employed to achieve these aims. While there are numerous definitions of green infrastructure, it is generally considered to comprise a network of green spaces and water features. Two key characteristics of green infrastructure are identified viz. multifunctionality and connectivity. These lend some commonality to what may at first appear as disparate definitions. Importantly, green infrastructure makes a critical contribution to the three components of sustainability viz. environment, economy and equity. The multifunctional nature of green infrastructure is pivotal in this role, whether one is considering functions or benefits. Green infrastructure planning is a strategic planning approach which aims to create multifunctional networks across landscape scales, from regional to city to neighbourhood. It can be viewed as an activity within the field of landscape planning, and has links to urban planning, regional development planning and social planning. The case study city, Berlin, has a strong focus on this sort of planning, with its Land Use Plan providing a framework for a city-wide green infrastructure characterised by both connectivity and multifunctionality. As for green infrastructure planning principles, three examples spanning the years 2006 to 2016 are reviewed. The influence of landscape ecology is pervasive, particularly in regard to connectivity. Two additional principles (along with strategies) are suggested. The first is: green infrastructure planning should emulate ‘indispensable patterns’ in both urban and rural landscapes; and the second: green infrastructure planning should be aligned with the statutory land use planning process. Finally, a number of general and Berlin-specific research questions are put forward. It is also suggested there is a need for a comparative case studies between cities, since studies across locations are relatively rare. It is concluded that green infrastructure is a significant and increasingly influential concept. In dealing with this complex and multi-faceted concept, green infrastructure planning has several significant challenges, one of the more important is how to integrate it within the statutory land use planning process, or at the very least, how to maximise its influence on that process. At stake is not only the continued implementation of sustainable development, but also progress in the urgent task of climate change mitigation and adaptation.

The bedroom community has become a prevalent and oft-criticized part of the modern architectural landscape. These suburban towns have continually grown radially outward from major cities across the nation since the end of the Second World War. While these suburbs have served to fulfill housing needs and wants of society, pressure to develop has often forced this growth to occur at a much more rapid rate than a traditional community. This rapid development has led to poorly implemented infrastructure, especially with regard to walkability and public transportation, which has fallen short of meeting the needs of users. These solutions in turn have contributed to the automotive dependence of society, despite the numerous detrimental effects this engenders, such as waste of natural resources, greenhouse gas emissions, and increased congestion of roadways. This has led many within the architectural community to push for a shift away from the suburbs due to their lack of sustainability, especially when compared to urban environments. However, the reality of the situation which our society faces does not enable us to simply abandon the suburbs in a mass exodus to city centers. Even if it did, there is a large percentage of the population which simply likes suburbia and its associated lifestyle. If this is the case, then, there needs to be a shift in the way transit is implemented within these communities. This thesis will examine how improving access to transit can revitalize bedroom communities and better serve their residents. Through examining the town of Beacon, NY, a bedroom community serving New York City and currently underutilizing its existing transit infrastructure, this thesis will explore how architecture can integrate mass transit into lives and daily activities of a community in order to better serve its residents and reduce automotive dependency.

Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial Technologies<br>Cycling has been considered a viable option to generate a modal shift from fossil dependent transportation modes. In this framework, measurements and tools that aid connected bicycle infrastructure planning have been developed. This is the case of the Bicycle Network Analysis score, a connectivity measure adapted for the U.S. It is based on the Levels of Traffic Stress methodology and computed mainly with OpenStreetMap data. Its aim is to quantify how well the low-stress bicycle network in a city connects people with the places they want to go. For this research, the BNA open source tool is adapted to a European context to validate its ability of quantifying low-stress connectivity. Three core elements are evaluated: stress network, destinations, and the overall score itself. They are related to cycling behaviors from two validation data sources: travel to work data in England and Wales, and crowdsourced bicycle trip routes in The Netherlands. The results indicate that in England and Wales, there is a significantly higher percentage of bicycle trips performed between origin-destination pairs with a low-stress connection between them. Additionally, a positive correlation is found between the percentage of bicycle trips within a city and its overall BNA score. In the Dutch case, the destinations core element is evaluated, determining that the destinations contemplated in the BNA score calculation are also among the highly frequented by cyclists. However, their importance within the score computation might require adjustments. Although a comprehensive validation cannot be achieved due to data limitations, evidence that providing low-stress connections between origins and destinations relates to bicycle commuting in cities is found. Therefore, special attention should be given to those measures that can greatly benefit the decision-making process when planning for sustainable cities.

Improperly designed road-stream crossings can fragment stream networks by restricting or preventing aquatic organism passage. These crossings may also be more vulnerable to high flow events, putting critical human infrastructure at risk. Climate change, which will require access to suitable habitat for species persistence, and is also predicted to increase the frequency and magnitude of extreme floods, underscores the importance of maintaining stream connectivity and resilient infrastructure. Given the large number of road-stream crossings and the expense of replacement, it is increasingly important to prioritize removals and account for the multiple benefits of these management actions. I developed an aquatic barrier prioritization scheme that combines potential habitat gain, stream thermal resilience, aquatic organism passage, and culvert risk of failure. To assess relative thermal resilience, I deployed paired air-water thermographs in several New England watersheds and analyzed relative thermal sensitivity (relationship of water to air temperature) and exposure (duration, frequency, and magnitude of warm stream temperature episodes) among streams. These were combined into a single metric of thermal resilience corresponding with the distance of that stream’s sensitivity and exposure from the watershed median. To test the relationship between risk of failure, culvert dimensions, and stream connectivity, I developed a logistic regression to predict risk of failure using data from two watersheds that experienced extreme flooding from Hurricane Irene (2011). Finally, I applied the resultant prioritization scheme to 66 road-stream crossings in the Westfield River watershed (MA). Thermal habitat quality varied considerably within and among watersheds. Stream sensitivity was generally lower than the widely accepted 0.8 ̊C increase in stream temperature for every 1 ̊C increase in air temperature (Westfield median sensitivity = 0.44), with substantial differences among streams. Exposure also varied widely among streams, indicating that some headwater streams in New England are more thermally resilient than previously thought. Risk of infrastructure failure was predicted with a logistic regression using culvert constriction ratio and predicted aquatic organism passage as predictors (Likelihood ratio test, X2=59.1, df=3, p- value=9.2e-13), indicating that underdesigned culverts were more likely to be barriers to passage and more likely to fail in extreme flow events. To prioritize culverts, this study ultimately used a piecewise approach that identified culverts opening the longest reaches of thermally resilient habitat, and then ranked those culverts by infrastructure replacement need. In the Westfield River, the prioritization clearly identified crossing replacements most likely to yield multiple benefits. The scheme I developed can accommodate changes in the relative weights of the different criteria, which will reflect differences in management and conservation concerns in the confidence of inputs. In conclusion, increasing connectivity by removing barriers may be one of the most effective ways to mitigate the effects of climate change on aquatic systems, but it is important to remove the right barriers.

The Information Technology (IT) as subject taught in South African secondary schools is considered to be a very perplexing subject. The IT as a subject has four learning outcomes which are E-Communication (weight 10%), Social and Ethical Issues (weight 10%), Hardware and Systems Software (weight 20%) and Programming and Software Development (weight 60%). The Programming and Software Development enjoys the highest weight as outcome of IT and it is believed to be the main cause of the difficulty of IT. The number of Grade 9 learners willing to offer IT as a subject in Grade 10 is decreasing and the number of learners pursuing IT until Grade 12 is declining in every school in South Africa annually. The aim of this research is to investigate methods that enhance teaching and learning Information Technology at a selected high school focusing on Grade12 learners. Although this work investigated many teaching and learning methods, it has come to be known that the hybrid system or method is the best to adopt and apply in teaching and learning of IT in high schools especially in the relevant target high school. Thirty (30) participants were sampled. Three (3) data collection instruments, which were questionnaires, interviews and observations were used. Results that were obtained from the use of these data collection instruments were recorded and analysed. Results from these instruments were compared and conclusions drawn. A major finding was that the hybrid system that combines both teacher-centered and learner-centered teaching approaches was able to enhance the teaching and learning of IT.<br>Science and Technology Education<br>M. Ed. (Natural Science Education)