Complex system representation for vulnerability analysis

Many socio-technical systems are endowed of dynamism, self-organization, emergency etc. These attributes make them as complex systems. Because of this complexity, the representation is a crucial step for vulnerability analysis. The objective of this paper is to provide a generic framework of complex systems representation for vulnerability analysis. We used infrastructure network such as power grid, gas and telecommunication system to illustrate our proposal. It is separated in five layers: Spatial framework, Stake, Flow, Environment, and Network structure. The static view consists of a network structure (Nodes and edges). The dynamic view is related to the flow circulation, components’ states variations, and interdependences among them. Characteristics of these factors are described. The environment refers to outside perturbations that could happen. With our proposal it is possible to model many classes of complex system as the basis of vulnerability analysis. For this purpose, some modelling rules are proposed. The result allows performing simulations. Results of the simulation can be used for instance to find out vulnerability model into complex systems, or to validate existing models

Decision support for infrastructure network vulnerability assessment in natural disaster crisis situations

This thesis deals with infrastructure network vulnerability analysis in the natural disaster context. It starts from the observation that infrastructure such as water supply or power grid has significant influence on natural disasters’ indirect consequences. The aim is to model the vulnerability to take efficient actions. The scientific approach is divided into two complementary parts. The first one deals with the vulnerability assessment, while the second one focuses on the decision aiding process to be implemented for the assessed vulnerability reducing. The proper vulnerability analysis is based on the analysis objects modelling. In order to achieve this, we will adopt a graph theory representation. A literature review will allow us to identify the graph structure which best suits the context of the thesis. In a multi network analysis environment, interdependences, i.e. relationships between components of the same network or different networks - are a determining factor for any vulnerability model. We have thus proposed an approach to model interdependence compatible with the graph theory. There are two types of relationships: the one first is functional (dependence), while the second one is dysfunctional (influence). The vulnerability is assessed by a simulation-based approach. It is composed of one part relating to the system ability to resist the feared event; and the other part relative to its ability to be back on its nominal state after the disaster. When the vulnerability is determined, the next step will be to take the necessary decisions to manage it. This part on the decision aiding is itself divided into two sub parts: first of all the process to be used for the crisis management is established. Then a methodology for decision aiding is proposed and results on a Decision Support System development. In the age of the internet and social networks, it is possible to deploy the application on the internet

Aide à la décision pour l’analyse de la vulnérabilité des réseaux d’infrastructure face à une crise de catastrophe naturelle

Cette thèse traite de la Vulnérabilité des réseaux face aux catastrophes naturelles. Elle part du constat que les infrastructures telles que les réseaux d’eau, d’électricité influencent considérablement les conséquences indirectes des catastrophes naturelles. Elle vise donc à modéliser la vulnérabilité dans de telles situations pour une prise de décision efficace. La démarche scientifique est divisée en deux parties complémentaires. La première traite de la vulnérabilité des dits systèmes, tandis que la seconde se concentre sur le processus d’aide à la décision à mettre en œuvre en vue de réduire la vulnérabilité. L’analyse proprement dite de la vulnérabilité repose sur la modélisation des objets de l’analyse. Pour ce faire nous adopterons une représentation par la théorie des graphes. La revue de la littérature à ce niveau nous a permis d’identifier les structures de graphe les mieux adaptées au contexte de la thèse. Dans un environnement d’analyse multi réseau, les interdépendances, c’est-à-dire les liens entre les composants d’un même réseau ou de réseaux différents-sont un facteur déterminant pour tout modèle de vulnérabilité. Nous avons ainsi proposé un modèle compatible avec la théorie des graphes. Sont distingués deux types d’interdépendances. La première est fonctionnelle (dépendance), et la seconde est dysfonctionnelle (influence). La vulnérabilité quant à elle, est déterminée par une approche basée sur la simulation. Elle est composée d’une première partie relative à l’aptitude du système à résister à l’évènement redouté ; et d’une seconde partie relative à son aptitude à se recouvrer des conditions opérationnelles après la catastrophe. Le calcul de la vulnérabilité est un point d’entrée pour assister l’analyste dans sa prise de décision. La deuxième partie aborde ce thème. Elle est elle-même divisée en deux sous parties : La première traite du processus à mettre en œuvre pour la gestion de la crise ; la deuxième du Système Interactif d’Aide à la Décision réalisé. Une méthodologie d’aide à la décision et supportée par un outil informatique. À l’ère de l’internet et des réseaux sociaux, il est envisageable de déployer l’application sur internet. ABSTRACT : This thesis deals with infrastructure network vulnerability analysis in the natural disaster context. It starts from the observation that infrastructure such as water supply or power grid has significant influence on natural disasters’ indirect consequences. The aim is to model the vulnerability to take efficient actions. The scientific approach is divided into two complementary parts. The first one deals with the vulnerability assessment, while the second one focuses on the decision aiding process to be implemented for the assessed vulnerability reducing. The proper vulnerability analysis is based on the analysis objects modelling. In order to achieve this, we will adopt a graph theory representation. A literature review will allow us to identify the graph structure which best suits the context of the thesis. In a multi network analysis environment, interdependences, i.e. relationships between components of the same network or different networks - are a determining factor for any vulnerability model. We have thus proposed an approach to model interdependence compatible with the graph theory. There are two types of relationships: the one first is functional (dependence), while the second one is dysfunctional (influence). The vulnerability is assessed by a simulation-based approach. It is composed of one part relating to the system ability to resist the feared event; and the other part relative to its ability to be back on its nominal state after the disaster. When the vulnerability is determined, the next step will be to take the necessary decisions to manage it. This part on the decision aiding is itself divided into two sub parts: first of all the process to be used for the crisis management is established. Then a methodology for decision aiding is proposed and results on a Decision Support System development. In the age of the internet and social networks, it is possible to deploy the application on the internet