Vulnérabilité, interdépendance et analyse des risques des postes sources et des modes d’exploitation décentralisés des réseaux électriques

In view of the increasing use of Information and Communication Technol-ogies in power systems, it is essential to study the interdependencies between these coupled heterogeneous systems. This thesis focuses on the modeling of multi- infrastructure systems. This includes interdependencies and the three major failures families: common mode, escalat-ing and cascading. It is indeed necessary to identify the weaknesses that can trigger one or multiple failure(s) and cascade through these interdependent infrastructures, causing unex-pected and increasingly more serious failures to other infrastructures. In this context, different approaches, based on the theory of Complex Networks, are developed to identify the most critical components in the coupled heterogeneous system. One of the major scientific barriers addressed in this thesis is the development of a unified mathematical model to represent the behavior.Au vu de l’utilisation croissante des technologies de l’information et de la communication dans les réseaux électriques, il est indispensable d’étudier l’étroite liaison entre ces infrastructures et d’avoir une vision intégrée du système couplé. Cette thèse porte ainsi sur la modélisation des systèmes multi-infrastructures. Cela inclut les interdépendances et les trajectoires de défaillances de type modes communs, aggravations et cascades. Il est en effet nécessaire d’identifier les points de faiblesse qui peuvent déclencher une ou de multiples défaillance(s), se succéder en cascade au travers de ces infrastructures liées et ainsi entrainer des défaillances inattendues et de plus en plus graves dans des autres infrastructures. Dans cette optique, différents modèles basés sur la théorie des Réseaux Complexes sont développés afin d’identifier les composants les plus importantes, et pourtant critiques, dans le système interconnecté. Un des principaux verrous scientifiques levé dans cette thèse est relatif au développement d'un modèle mathématique « unifié » afin de représenter les comportements des multiples infrastructures non-homogènes qui ont des interdépendances asymétriques

An Institutional Perspective on the role of the state in broadband delivery in Nigeria

Nigeria, often lauded for its immense economic potential, struggles with the formidable challenge of extending effective broadband services to all its regions, particularly unserved/underserved rural and suburban areas. Despite strategies such as enhanced licensing regimes for Internet Service Providers (ISPs) and Mobile Network Operators (MNOs), and the adoption of shared infrastructure policies, significant connectivity gaps remain. This research seeks to examine the issues surrounding broadband provision in Nigeria through three focal questions: the role of governance across multiple levels in broadband delivery, the enduring barriers — such as corruption and governance inefficiency — to its effective rollout, and the impact of the nation's industrial policy in telecommunications on broadband availability and efficacy. Employing a qualitative approach, the study engaged 26 participants from diverse sectors – including academics, ISP personnel, and policymakers – and conducted an analysis of archival government documents. Grounded in institutionalist political economy framework, the research offers a comprehensive view of Nigeria's telecommunications environment. The study brings to the fore a combination of factors like corruption, governance, and institutional barriers, revealing how they are rooted in Nigeria's historical and socio-political fabric. It also extends the traditional understanding of governance, highlighting its multi-faceted roles beyond policy execution to include regulation and oversight. The research culminates in actionable recommendations for policymakers and industry stakeholders, emphasising the need for coherent, well-executed industrial policies, and suggesting a shift in focus from policy justification to its practical implementation. Structured across seven chapters, this thesis offers empirical evidence, theoretical advancements, and practical guidelines aimed at fostering an interconnected, inclusive, and effective broadband infrastructure in Nigeria

"The authority of the steam" : power dynamics of digital production in the Bitcoin blockchain

This thesis offers a critical investigation of the Bitcoin currency and the operation of its technical structure, i.e. blockchain technology. The main objective of the research is to identify and describe the specific power dynamics performed by and through this digital phenomenon. “Power dynamics” are framed in this work largely in terms of authority and sovereignty. To structure an exploration of such dynamics, the narrative is overarched by four different notions of “utopia” —as paradox, ideal, no-place, and imagined governance— that address the following main questions always underpinned by the general inquiry on power: What is the Bitcoin Blockchain? Where is it located? How are power relations performed in it? And how are power relations modified in relation with previous institutional systems? The thesis addresses distinct notions of authority in Bitcoin through the observation of its historical, spatial, and organizational characteristics. It maps the techno-political emergence of the blockchain system, the geographical distribution of Bitcoin’s infrastructural network, and the strategies for governance involved in its development as software. Based on the observation of these settings, this thesis argues that Bitcoin posits a restructuration of power dynamics through the automation of code, in particular, through its process of production. In order to develop this restructuration, the power dynamics of the Bitcoin blockchain are weighted against authority models of the state’s institutions. The thesis builds upon existing political theories of Empire (Hardt and Negri), protocol (Galloway), and the Stack (Bratton) to develop a critical account of Bitcoin’s power dynamics. The work sits in between the disciplines of Media Theory, Software Studies, Political Theory, and Digital Methods, and makes use of qualitative and quantitative methods to empirically support the former argument

Immersion Into Noise

Joseph Nechvatal's Immersion Into Noise investigates multiple aspects of cultural noise by applying our audio understanding of noise to the visual, architectual and cognative domains. The author takes the reader through phenomenal aspects of the art of noise into algorithmic and network contexts, beginning in the Abside of the Grotte de Lascaux

Immersion Into Noise

Joseph Nechvatal's Immersion Into Noise investigates multiple aspects of cultural noise by applying our audio understanding of noise to the visual, architectual and cognative domains. The author takes the reader through phenomenal aspects of the art of noise into algorithmic and network contexts, beginning in the Abside of the Grotte de Lascaux

Dissecting Latency in the Internet's Fiber Infrastructure

The recent publication of the `InterTubes' map of long-haul fiber-optic cables in the contiguous United States invites an exciting question: how much faster would the Internet be if routes were chosen to minimize latency? Previous measurement campaigns suggest the following rule of thumb for estimating Internet latency: multiply line-of-sight distance by 2.1, then divide by the speed of light in fiber. But a simple computation of shortest-path lengths through the conduits in the InterTubes map suggests that the conversion factor for all pairs of the 120 largest population centers in the U.S.\ could be reduced from 2.1 to 1.3, in the median, even using less than half of the links. To determine whether an overlay network could be used to provide shortest paths, and how well it would perform, we used the diverse server deployment of a CDN to measure latency across individual conduits. We were surprised to find, however, that latencies are sometimes much higher than would be predicted by conduit length alone. To understand why, we report findings from our analysis of network latency data from the backbones of two Tier-1 ISPs, two scientific and research networks, and the recently built fiber backbone of a CDN