Les méthodes actuelles utilisées pour l'identification des infrastructures critiques, souvent envisagées dans leurs seules dimensions techniques, montrent certaines limites. Notre thèse postule qu'il est nécessaire de tenir compte du contexte territorial dans lequel ces infrastructures s'inscrivent, dans la mesure où les caractéristiques d'un territoire contribuent à leur criticité. En retour, les infrastructures critiques sont susceptibles d'aggraver la vulnérabilité de ces territoires. Nous développons deux hypothèses de recherche: 1. La "criticité territoriale" exprime le fait que les infrastructures critiques ne sont pas critiques en elles-mêmes, mais par rapport à un contexte socio-économique, politique et géographique. Nous proposons ainsi un ensemble de critères, associés à une approche multiscalaire des systèmes d'infrastructures, permettant l'identification des infrastructures critiques. Une étude de cas portant sur les infrastructures critiques d'énergie de l'Union Européenne valide cette approche. 2. La "criticité politique" souligne la dimension géopolitique des infrastructures critiques : celles-ci reflètent les seuils d'acceptabilité des autorités territoriales, au regard des conséquences potentielles de l'interruption de services essentiels. Cette hypothèse est développée et testée dans le cadre de notre participation au processus de concertation entre l'Union Européenne et ses pays membres pour la mise en place de la Directive 2008/114/EC sur l'identification et la protection des infrastructures critiques européennes. Les conclusions soulignent la pertinence d'une approche géographique et territoriale pour l'identification des infrastructures critiques. / The existing methods for identifying critical infrastructures, mainly based on risk analysis, were found to be insufficient. Our PhD states that the existing territorial vulnerability factors contribute to the criticality of the infrastructures; in return, critical infrastructures enhance this vulnerability. As a consequence, the identification process should be based, not only on technical aspects, but also on a geographical approach. Two main research hypothesis are developed: 1. The "territorial criticality" expresses the fact that an infrastructure is not critical in itself, but its criticality is related to the socio-economic, political and geographical context. We propose a set of criteria and related indicators associated to a multilevel model. A case study shows how these criteria can be applied in the case of the European energy critical infrastructures. 2. The "political criticality" means that the designation of an infrastructure as critical reflects the level of consequences decision-makers are ready to accept. These acceptability thresholds are related to the potential consequences the disruption of such infrastructure could trigger. If the potential consequences go beyond a given threshold, then the infrastructure is considered as critical. We developed and tested this hypothesis in the context of our participation to the preparatory work carried out by the European Commission Joint Research Center to support the European Commission and its member states on the definition of criteria for identifying European Critical Infrastructures (ECI). Conclusions highlight the benefits of a geographical approach to identify critical infrastructures.

Longtemps négligées par les institutions internationales et bailleurs de fond au profit des programmes d’ajustements structurels et autres politiques, les infrastructures ont suscité beaucoup plus d’intérêt au cours des dernières années. Aschauer (1989) et Munnell (1992) furent les premiers à souligner l’importance que pourrait avoir le financement des infrastructures sur le développement économique et la productivité des secteurs privés. Notamment, les retombées de ces investissements dans les pays en développement seraient considérables eu égard au déficit aigu du parc infrastructurel de ces pays. Depuis lors, une vaste littérature s’est développée autour de la question des retombées économiques des investissements en infrastructures, aboutissant parfois à des conclusions beaucoup plus nuancées. Par exemple, d’autres auteurs mettent en garde contre des revers pouvant ressortir desdits investissements (syndrome hollandais, effet d’éviction, etc.). C’est dans ce contexte qu’une étude portant sur l’analyse des impacts de l’accroissement des dépenses publiques en infrastructure initié par le Mali a été conduite. Conformément à la littérature, les modèles d’équilibre général calculable ont été adoptés pour l’évaluation de cette question. La contribution de l’étude est la considération de la durabilité des effets des infrastructures dans le temps à travers la prise en compte de l’aspect dynamique des MEGC. Les résultats ont permis de voir qu’à long terme les investissements en infrastructures mèneraient à une croissance économique. Par ailleurs, le financement des infrastructures via l’aide étrangère favorise le bien-être des ménages et des populations et reste la meilleure option de financement pour le Mali. Toutefois, une hausse massive des dépenses en infrastructures peut induire une appréciation du taux de change néfaste pour l’économie surtout quand elle est financée par les différentes taxes internes (taxe de vente, impôt sur le revenu des ménages et des entreprises). Ceci justifie l’intérêt du gouvernement d’être sélectif quant au mode de financement de ses infrastructures.

Electrical energy generation and distribution systems are good examples of complex systems. They include continuous, discrete, and social dynamics. They are operated by millions of human and non-human (or electro-mechanical) agents, and they show statistical properties found in other complex systems, such as power-law distributions in failure sizes. A number of recent large blackouts in Europe and North America have emphasized the societal importance of understanding these dynamics. Classical electromagnetic analysis alone frequently does not provide the insight required to characterize and mitigate risks in the electricity infrastructure. The objective of this thesis is to obtain insights into the dynamics of power grids using tools from the science of complex systems. In particular, this thesis will compare the topology, electrical structure, and attack/failure tolerance of power grids with those of theoretical graph structures such as regular, random, small-world, and scale-free networks. Simulation results in this thesis will describe the cost of the disturbances as a function of failure or attack sizes. The cost associated with network perturbations is often measured by changes on the diameter or average path length, whereas in the electricity industry, the loss of power demand (or blackout size) is the best indicator of the cost or impact of disturbances to electricity infrastructure.

O trabalho busca debater as principais dificuldades e potencialidades da inserção urbana das infraestruturas hídricas de drenagem. O objeto de estudo é o Sistema de Reservatórios de Amortecimento de Cheias, conhecidos como piscinões, na interface com a estrutura urbana da Região Metropolitana de São Paulo. Busca-se, ao entender o existente, redefinir e ampliar seu significado. O principal objetivo da pesquisa é contribuir com uma abordagem mais abrangente e multidisciplinar do entendimento da reservação da água pluvial na metrópole, entendendo-o não somente como mero sistema de fluxos cuja única finalidade é a eficiência técnica. Evidencia-se que o sistema de contenção de águas pluviais tem potencial para desempenhar um papel relevante na qualificação espacial em diversas escalas e contribuir para a estruturação e legibilidade das localidades as que pertencem. / The objective of this research is to discuss the main challenges and potentials of integrating water infrastructure in urban morphology. The case study that will be examined is the Flood Storage Reservoirs System, or as it is colloquially referred to piscinões, along with its interface with the urban structure of the Metropolitan Region of São Paulo. This research aims to contribute to the understanding of drainage through a more comprehensive approach, beyond that of its technical efficiency as a flow system. It is clear that the flood storage system has the potential to play an important role in the qualification of its urban space at various scales and contribute to the locality structure.

One of the consequences of China’s rapid urbanization is the disappearance, or at least, mismanagement of the many lakes of the Central Yangtze River Basin. The thesis investigates the situation by conducting a complex system analysis, revealing four most pressing issues surrounding the lakes: flood management, sustaining agricultural practice, controlling urban development and maintaining a healthy ecosystem. The inadequacy in Central Yangtze River Basin’s flood capacity requires that the many lakes in the region be preserved and connected to form a flood retention network. Unfortunately, this preservation is threatened by urban development that seeks to infill the lakes. As well, many of the lakes are now divided into independent lotus farms and fish ponds which do not provide for a sustainable aquatic ecosystem. The city of Wuhan and its Lake Shahu is the focus of this thesis. Lake Shahu is a microcosm of the regional condition, and its centrality within the city of Wuhan brings about a particular set of problems, namely, the lake is perceived as an obstacle for communication and transit as well as an impediment for much needed city expansion. The thesis proposes a solution to the complex problem surrounding Lake Shahu by synthesizing a system of integrated infrastructure which would reconnect the lake and the Yangtze River, as well as provide a flood berm, public spaces, lotus farms, fisheries, wetlands and an artificial platform as land for city expansion. The infrastructural system is to instigate a process of transformation which sets up a symbiotic relationship among elements on site. For example, the Land Over Water project will allow penetration of sunlight to sustain the ecosystem below while staging a lively urban life above and supplying the lotus farms below with grey water collected from households. The design approach, known as Landscape Urbanism, is exemplified by Field Operation’s Fresh Kills Landfill Rehabilitation project where agricultural techniques and strategic planting are used to create a diverse range of habitats and event spaces over the course of 30 years. In the case of Lake Shahu, the importance of agriculture is highlighted for its engineering potential as well as its economic capacity to support the remaining rural farming population in the area. Aided by the transformation of the landscape and given the tools for monitoring the lake’s ecosystem, the farmers and fishermen can eventually become stewards of the land and water. Not unlike Fresh Kills, the project of Lake Shahu is staged for a 35-year period. The project evolves along the rapid development of China at a much slower pace as the natural processes required to stabilize the landscape will take a long time. By the end of the transformation, a sustainable system capable of adapting to changes in the urban, agrarian and natural environment will be able to support generations to come.

One of the consequences of China’s rapid urbanization is the disappearance, or at least, mismanagement of the many lakes of the Central Yangtze River Basin. The thesis investigates the situation by conducting a complex system analysis, revealing four most pressing issues surrounding the lakes: flood management, sustaining agricultural practice, controlling urban development and maintaining a healthy ecosystem. The inadequacy in Central Yangtze River Basin’s flood capacity requires that the many lakes in the region be preserved and connected to form a flood retention network. Unfortunately, this preservation is threatened by urban development that seeks to infill the lakes. As well, many of the lakes are now divided into independent lotus farms and fish ponds which do not provide for a sustainable aquatic ecosystem. The city of Wuhan and its Lake Shahu is the focus of this thesis. Lake Shahu is a microcosm of the regional condition, and its centrality within the city of Wuhan brings about a particular set of problems, namely, the lake is perceived as an obstacle for communication and transit as well as an impediment for much needed city expansion. The thesis proposes a solution to the complex problem surrounding Lake Shahu by synthesizing a system of integrated infrastructure which would reconnect the lake and the Yangtze River, as well as provide a flood berm, public spaces, lotus farms, fisheries, wetlands and an artificial platform as land for city expansion. The infrastructural system is to instigate a process of transformation which sets up a symbiotic relationship among elements on site. For example, the Land Over Water project will allow penetration of sunlight to sustain the ecosystem below while staging a lively urban life above and supplying the lotus farms below with grey water collected from households. The design approach, known as Landscape Urbanism, is exemplified by Field Operation’s Fresh Kills Landfill Rehabilitation project where agricultural techniques and strategic planting are used to create a diverse range of habitats and event spaces over the course of 30 years. In the case of Lake Shahu, the importance of agriculture is highlighted for its engineering potential as well as its economic capacity to support the remaining rural farming population in the area. Aided by the transformation of the landscape and given the tools for monitoring the lake’s ecosystem, the farmers and fishermen can eventually become stewards of the land and water. Not unlike Fresh Kills, the project of Lake Shahu is staged for a 35-year period. The project evolves along the rapid development of China at a much slower pace as the natural processes required to stabilize the landscape will take a long time. By the end of the transformation, a sustainable system capable of adapting to changes in the urban, agrarian and natural environment will be able to support generations to come.

Reproduction de : Thèse doctorat : Sciences économiques. Economie des transports : Lyon 2 : 2007. / Titre provenant de l'écran-titre. Bibliogr.

O trabalho busca debater as principais dificuldades e potencialidades da inserção urbana das infraestruturas hídricas de drenagem. O objeto de estudo é o Sistema de Reservatórios de Amortecimento de Cheias, conhecidos como piscinões, na interface com a estrutura urbana da Região Metropolitana de São Paulo. Busca-se, ao entender o existente, redefinir e ampliar seu significado. O principal objetivo da pesquisa é contribuir com uma abordagem mais abrangente e multidisciplinar do entendimento da reservação da água pluvial na metrópole, entendendo-o não somente como mero sistema de fluxos cuja única finalidade é a eficiência técnica. Evidencia-se que o sistema de contenção de águas pluviais tem potencial para desempenhar um papel relevante na qualificação espacial em diversas escalas e contribuir para a estruturação e legibilidade das localidades as que pertencem. / The objective of this research is to discuss the main challenges and potentials of integrating water infrastructure in urban morphology. The case study that will be examined is the Flood Storage Reservoirs System, or as it is colloquially referred to piscinões, along with its interface with the urban structure of the Metropolitan Region of São Paulo. This research aims to contribute to the understanding of drainage through a more comprehensive approach, beyond that of its technical efficiency as a flow system. It is clear that the flood storage system has the potential to play an important role in the qualification of its urban space at various scales and contribute to the locality structure.

Today, organisations that seek a competitive advantage are adopting virtual infrastructures that share and manage computing resources. The trend is towards implementing collaborating applications that are supported by web services technology. Even though web services technology is rapidly becoming a fundamental development paradigm, adequate security constitutes the main concern and obstacle to its adoption as an industry solution. An important issue to address is the development of suitable access control models that are able to not only restrict access to unauthorised users, but also to discriminate between users that originate from different collaborating parties. In web services environments, access control is required to cross the borders of security domains, in order to be implemented between heterogeneous systems. Traditional access control systems that are identity-based do not provide a solution, as web services providers have to deal with unknown users, manage a large user population, collaborate with others and at the same time be autonomous of nature. Previous research has pointed towards the adoption of attribute-based access control as a means to address some of these problems. This approach is still not adequate, as the trustworthiness of web services requestors cannot be determined. Trust in web services requestors is thus an important requirement to address. For this reason, the thesis investigated trust, as to promote the inclusion of trust in the web services access control model. A cognitive approach to trust computation was followed that addressed uncertain and imprecise information by means of fuzzy logic techniques. A web services trust formation framework was defined that aims to populate trust concepts by means of automated, machine-based trust assessments. The structure between trust concepts was made explicit by means of a trust taxonomy. This thesis presents the WSACT – or the Web Services Access Control incorporating Trust –model. The model incorporates traditional role-based access control, the trust levels of web services requestors and the attributes of users into one model. This allows web services providers to grant advanced access to the users of trusted web services requestors, in contrast to the limited access that is given to users who make requests through web services requestors with whom a minimal level of trust has been established. Such flexibility gives a web services provider the ability to foster meaningful business relationships with others, which portrays humanistic forms of trust. The WSACT architecture describes the interacting roles of an authorisation interface, authorisation manager and trust manager. A prototype finally illustrates that the incorporation of trust is a viable solution to the problem of web services access control when decisions of an autonomous nature are to be made. / Thesis (PhD (Computer Science))--University of Pretoria, 2008. / Computer Science / unrestricted

A large number of spatial datasets have inconsistent and/or outdated metadata. In certain cases, metadata is entirely absent. Some spatial data producers suggest that metadata creation and maintenance is a time consuming and labour-intensive process. Conversely, users experience difficulties in understanding and accessing spatial datasets, if associated metadata is insufficient or non-existent. Eventually, deficient metadata use may lead to loss of spatial data meaning and cause its very existence to be forgotten. The purpose of the study was to assess the main challenges hindering metadata creation and maintenance on the part of producers and its usage on the part of users in South Africa. The main findings showed that: data was accessed at expected levels via the internet; most data users accepted alternative spatial data media including compact disks and hardcopy; the spatial data industry is generally under financial budget constraints; particularly in the public sector, lack of skilled personnel in spatial metadata management resulted in staff turnover problems; the framework datasets indicated outdated metadata; and different producers used inconsistent metadata standards and a number of organizations were at rudimentary stage of spatial metadata development. In conclusion, spatial data producers should be encouraged to maintain data with complete documentation in a standardized spatial metadata to assure information consistency for users. Raising awareness about spatial metadata benefits may encourage data managers and top leaders to build on metadata priorities. Moreover, strong compliance with the SDI policy necessitates solid cooperation amongst the spatial data community. / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2009.