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Linkages between Complex Adaptive Systems (CAS) thinking and efficiency analysis remain in their infancy. This research associates the basic building blocks of the CAS 'flocking' metaphor with the essential building block concepts of Data Envelopment Analysis (DEA). Within a proposed framework DEA "decision-making units" (DMUs) are represented as agents in the agent-based modeling (ABM) paradigm. Guided by simple rules, agent DMUs representing business units of a larger management system, 'align' with one another to achieve mutual protection/risk reduction and 'cohere' with the most efficient DMUs among them to achieve the greatest possible efficiency in the least possible time. Analysis of the resulting patterns of behavior can provide policy insights that are both evidence-based and intuitive. This research introduces a consistent methodology that will be called here the Complex Adaptive Productive Efficiency Method (CAPEM) and employs it to bridge these domains. This research formalizes CAPEM mathematically and graphically. It then conducts experimentation employing using the resulting CAPEM simulation using data of a sample of electric power plants obtained from Rungsuriyawiboon and Stefanou (2003). Guided by rules, individual agent DMUs (power plants) representing business units of a larger management system,'align' with one another to achieve mutual protection/risk reduction and 'cohere' with the most efficient DMUs among them to achieve the greatest possible efficiency in the least possible time. Using a CAS ABM simulation, it is found that the flocking rules (alignment, cohesion and separation), taken individually and in selected combinations, increased the mean technical efficiency of the power plant population and conversely decreased the time to reach the frontier. It is found however that these effects were limited to a smaller than expected sub-set of these combinations of the flocking factors. Having been successful in finding even a limited sub-set of flocking rules that increased efficiency was sufficient to support the hypotheses and conclude that employing the flocking metaphor offers useful options to decision-makers for increasing the efficiency of management systems. / Ph. D.

NetLogo has become a standard platform for agent-based simulation, yet there appears to be widespread belief that it is not suitable for large and complex models due to slow execution. Our experience does not support that belief. NetLogo programs often do run very slowly when written to minimize code length and maximize clarity, but relatively simple and easily tested changes can almost always produce major increases in execution speed. We recommend a five-step process for quantifying execution speed, identifying slow parts of code, and writing faster code. Avoiding or improving agent filtering statements can often produce dramatic speed improvements. For models with extensive initialization methods, reorganizing the setup procedure can reduce the initialization effort in simulation experiments. Programming the same behavior in a different way can sometimes provide order-of-magnitude speed increases. For models in which most agents do nothing on most time steps, discrete event simulation—facilitated by the time extension to NetLogo—can dramatically increase speed. NetLogo’s BehaviorSpace tool makes it very easy to conduct multiple-model-run experiments in parallel on either desktop or high performance cluster computers, so even quite slow models can be executed thousands of times. NetLogo also is supported by efficient analysis tools, such as BehaviorSearch and RNetLogo, that can reduce the number of model runs and the effort to set them up for (e.g.) parameterization and sensitivity analysis.

Le diagnostic et la prise en charge des infections ostéo-articulaires (IOA) sont souvent complexes occasionnant une perte osseuse irréversible. La variabilité intra et inter-patient en terme de présentation clinique rend impossible le recours à une description systématique ou à une analyse statistique pour le diagnostic et l'étude de cette pathologie. Le développement d'IOA résulte d'interactions complexes entre les mécanismes cellulaires et moléculaires du tissu osseux et les bactéries. L'objectif de cette thèse est de modéliser l'IOA afin de simuler le comportement du système suite à des interactions au niveau cellulaire et moléculaire en utilisant l'approche de modélisation à base d'agents. Nous avons utilisé une méthode basée sur l'analyse bibliographique pour extraire les caractéristiques du modèle et les utiliser pour deux aspects. Le premier consiste en l'élaboration de la structure du modèle en identifiant les agents et les interactions, et le deuxième concerne l'estimation quantitative des différents paramètres du modèle. La réponse du système BJI aux différentes tailles d’inoculum bactérien a été simulée par la variation de différents paramètres. L'évolution des agents simulés a ensuite été analysée en utilisant une modélisant par des systèmes dynamiques non linéaires et une méthodologie "Datadriven", grâce auxquelles nous avons décrit le système d'IOA et identifié des relations plausibles entre les agents. Le modèle a réussi à présenter la dynamique des bactéries, des cellules immunitaires innées et des cellules osseuses au cours de la première étape de l'IOA et pour différentes tailles d'inoculum bactérien. La simulation a mis en évidence les conséquences sur le tissu osseux résultant du processus de remodelage osseux au cours de l'IOA. Ces résultats peuvent être considérés comme une base pour une analyse plus approfondie et pour la proposition de différentes hypothèses et scénarios de simulation qui pourraient être étudiés dans ce laboratoire virtuel. / Bone and joint infections are one of the most challenging bone pathologies that associated with irreversible bone loss and long costly treatment. The high intra and inter patient's variability in terms of clinical presentation makes it impossible to rely on the systematic description or classical statistical analysis for its diagnosis or studying. The development of BJI encompasses a complex interplay between the cellular and molecular mechanisms of the host bone tissue and the infecting bacteria. The objective of this thesis is to provide a novel computational modeling framework that simulates the behavior resulting from the interactions on the cellular and molecular levels to explore the BJI dynamics qualitatively and comprehensively, using an agent-based modeling approach. We relied on a meta-analysis-like method to extract the quantitative and qualitative data from the literature and used it for two aspects. First, elaborating the structure of the model by identifying the agents and the interactions, and second estimating quantitatively the different parameters of the model. The BJI system’s response to different microbial inoculum sizes was simulated with respect to the variation of several critical parameters. The simulation output data was then analyzed using a data-driven methodology and system dynamics approach, through which we summarized the BJI complex system and identified plausible relationships between the agents using differential equations. The BJI model succeeded in imitating the dynamics of bacteria, the innate immune cells, and the bone cells during the first stage of BJI and for different inoculum size in a compatible way. The simulation displayed the damage in bone tissue as a result of the variation in bone remodeling process during BJI. These findings can be considered as a foundation for further analysis and for the proposition of different hypotheses and simulation scenarios that could be investigated through this BJI model as a virtual lab.

L’Impact des caractéristiques spatiales sur les dynamiques de développement urbain est d’un grand intérêt dans les études urbaines. L’interaction entre les résidents et les caractéristiques spatiales est d’un intérêt particulier dans le contexte des modèles urbains car de nombreux modèles urbains sont fondés sur le processus d’installation des individus dans des parties spécifiques des villes. Il s’agit d’une étude sur la dynamique de développement urbain avec des Automates Cellulaires et un Système Multi-Agent. Le développement urbain de cette étude recouvre le « urban renewal » et la mobilité résidentielle. Il correspond à la mobilité résidentielle des ménages qui sont attirés par le confort résidentiel et le confort de centralité ; ces conforts sont localisés dans quelques quartiers de Strasbourg. La diversité et la qualité de ces conforts deviennent des critères pour les choix résidentiels de telle façon que chaque ménage recherche la proximité de ces conforts. Dans cette étude l’Automate Cellulaire modélise les caractéristiques techniques des unités spatiales, celles-ci sont identifiées par des attributs inhérents qui sont égaux aux conforts dans les résidences et dans les zones urbaines. Dans le Système Multi-Agent la population de la ville de Strasbourg interagit entre elle et avec la ville. Les agents représentent les classes socio-professionnelles des ménages. Pendant un changement spatio- temporel, l’aspiration des ménages forme le développement socio-spatio-temporelle de la ville. / The impact of spatial characteristics on the dynamics of urban development is a topic of great interest in urban studies. The interaction between the residents and the spatial characteristics is of particular interest in the context of urban models where some of the most famous urban models have been based on the process of individual settlements in some specific parts of cities.This research investigates the dynamism of urban development modeled by Cellular Automata and Multi-Agent System. The urban development, in this study embraces urban renewal and residential mobility. It corresponds to the residential mobility of households, attracted by residential and centrality comfort; these comforts are crystallized in some areas and residences of Strasbourg. The diversity and quality of these comforts become criteria for residential choice in a way that the households seek for proximity to these comforts.The Cellular Automata in this study, models the spatial characteristics of urban spatial units and they are identified by some inherent attributes that are equal to the comfort in residences and urban areas. The Multi- Agent System represent a system in which the population of the city interact between them and between them and the city; the agents delegate the socio-professional classes of households. During the spatiotemporal change, the aspiration of households forms the socio-spatio-temporal development of the city.

NetLogo has become a standard platform for agent-based simulation, yet there appears to be widespread belief that it is not suitable for large and complex models due to slow execution. Our experience does not support that belief. NetLogo programs often do run very slowly when written to minimize code length and maximize clarity, but relatively simple and easily tested changes can almost always produce major increases in execution speed. We recommend a five-step process for quantifying execution speed, identifying slow parts of code, and writing faster code. Avoiding or improving agent filtering statements can often produce dramatic speed improvements. For models with extensive initialization methods, reorganizing the setup procedure can reduce the initialization effort in simulation experiments. Programming the same behavior in a different way can sometimes provide order-of-magnitude speed increases. For models in which most agents do nothing on most time steps, discrete event simulation—facilitated by the time extension to NetLogo—can dramatically increase speed. NetLogo’s BehaviorSpace tool makes it very easy to conduct multiple-model-run experiments in parallel on either desktop or high performance cluster computers, so even quite slow models can be executed thousands of times. NetLogo also is supported by efficient analysis tools, such as BehaviorSearch and RNetLogo, that can reduce the number of model runs and the effort to set them up for (e.g.) parameterization and sensitivity analysis.

Information gathered socially online is a key feature of the growth and development of modern society. Presently the Internet is a platform for the distribution of data. Millions of people use Online Social Networks daily as a tool to get updated with social, political, educational or other occurrences. In many cases information derived from an Online Social Network is acted upon and often shared with other networks, without further assessments or judgments. Many people do not check to see if the information shared is credible. A user may trust the information generated by a close friend without questioning its credibility, in contrast to a message generated by an unknown user. This work considers the concept of credibility in the wider sense, by proposing whether a user can trust the service provider or even the information itself. Two key components of credibility have been explored; trustworthiness and expertise. Credibility has been researched in the past using Twitter as a validation tool. The research was focused on automatic methods of assessing the credibility of sets of tweets using analysis of microblog postings related to trending topics to determine the credibility of tweets. This research develops a framework that can assist the assessment of the credibility of messages in Online Social Networks. Four types of credibility are explored (experienced, surface, reputed and presumed credibility) resulting in a credibility hierarchy. To determine the credibility of messages generated and distributed in Online Social Networks, a virtual network is created, which attributes nodes with individual views to generate messages in the network at random, recording data from a network and analysing the data based on the behaviour exhibited by agents (an agent-based modelling approach). The factors considered for the experiment design included; peer-to-peer networking, collaboration, opinion formation and network rewiring. The behaviour of agents, frequency in which messages are shared and used, the pathway of the messages and how this affects credibility of messages is also considered. A framework is designed and the resulting data are tested using the design. The resulting data generated validated the framework in part, supporting an approach whereby the concept of tagging the message status assists the understanding and application of the credibility hierarchy. Validation was carried out with Twitter data acquired through twitter’s Application Programming Interface (API). There were similarities in the generation and frequency of the message distributions in the network; these findings were also recorded and analysed using the framework proposed. Some limitations were encountered while acquiring data from Twitter, however, there was sufficient evidence of correlation between the simulated and real social network datasets to indicate the validity of the framework.

This thesis describes the paradigm of complex systems and discusses possibilities of their modeling and simulations. The work shows the suitability of using multi-agent modeling for creating abstraction of social environment, that is one of the major complex systems. Thesis content includes an analysis of tools that are available for creating multi-agent simulators. The core of this thesis are processed research documents and a demonstrative model of social phenomenon known as procrastination.

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Les revêtements perméables se développent en France et à l’étranger comme une technique d’avenir en réponse aux enjeux de la protection des sols et de l’amélioration du cycle de l’eau en milieu urbain. Le développement de pavés drainants au sein du laboratoire de l’ESITC Caen a mis en évidence le besoin de quantifier les apports des revêtements perméables pour répondre aux attentes des acteurs locaux et favoriser l’utilisation de ces techniques par les aménageurs. Dans ce but, ce travail de thèse porte sur la description des processus hydrologiques au sein des revêtements perméables et la quantification de leurs bénéfices sur le ruissellement urbain. Deux modèles ont été développés pour répondre à ces objectifs.Le premier permet de modéliser les processus hydrologiques au sein des structures perméables avec une approche physique basée sur la résolution de l’équation de RICHARDS par la méthode des éléments finis. Cette modélisation apporte des éléments de compréhension sur l’influence des propriétés de la structure et de son environnement sur ses performances. Elle a abouti à la proposition d’une représentation conceptuelle du comportement hydrologique des structures perméables. Le second modèle permet de modéliser le comportement hydrologique d’un bassin versant avec une approche par systèmes multi-agents. Différents scénarios d’implantation de revêtements perméables ont été simulés sur un site d’étude réel situé à Ouistreham en Normandie. L’exploration de ce modèle apporte des éléments de quantification des bénéfices de l’implantation des revêtements perméables sur le ruissellement de surface. Les résultats obtenus mettent en évidence le lien entre le ratio de surface perméable sur la surface imperméable et la réduction du ruissellement. Ils soulignent l’importance de la dispersion des zones de revêtements perméables pour optimiser leurs bénéfices. / Permeable pavements are developing in France and abroad as a promising response to the growing issues of ground protection and the improvement of the water cycle in urban areas. The development of pervious concrete within the laboratory of ESITC Caen had highlighted the need to quantify the contributions of the permeable pavement, and thus meeting the expectations of local authorities and encouraging the use of these techniques by urban planners. In this purpose, this Phd aims at describing the hydrological mechanisms of the permeable pavements and quantifying their benefits on surface runoff. Two models were developed to respond to these objectives. The first one allows modeling the hydrological processes inside permeable pavement structures with a physically-based approach, which solves RICHARD’s law with a finite element method. This modeling enables the understanding of the influence of the properties of the structure and its environment on its performances. Results have led to the proposal of a conceptual representation of permeable structures. The second model allows modeling the hydrological behavior of an urban catchment with an agent-based approach. Various scenarios of permeable pavement implemantations were simulated on a real study site located at Ouistreham in Normandy. The analysis of this model enables the quantifying of the benefits of the implementation of permeable pavements on surface runoff. Results highlight the link between the permeable surface on the impermeable surface ratio and the reduction of runoff. They emphasize the importance of dispersing permeable pavement areas to maximize their benefits.