A Multilevel Agent-Based Approach to model and simulate Systems of Systems

International audienceThis article proposes a generic modeling approach of systems of systems (SoS) using agent-based modeling (ABM). SoSs are large scale systems including numerous-possibly heterogeneous-interacting component systems (CS) evolving in a dynamic environment. The aim of this article is to provide generic formalism allowing to represent and control the whole complexity of a SoS using agent-based simulations. Models generated using this formalism encompass static and dynamic aspects of SoSs. They consider reorganization of SoSs caused by changes of goals or subsystem capacity. All these elements are illustrated in this article using a SoS case study of Intelligent Automated Vehicles (IAV) initiated by the InTraDE (Intelligent Transportation for Dynamic Environment) European project to automate the port container logistic

Conception et modélisation de systèmes de systèmes : une approche multi-agents multi-niveaux

The main problematic of this thesis, which takes place in the context of the european project InTraDE (Intelligent Transportation for Dynamic Environment), deals with the modeling of systems of systems (SoS). A SoS is a system composed of a hierarchy of autonomous systems present in several representation levels. This thesis answers the need of generic modeling tools respecting the fundamental characteristics of SoS, proposing a multi-level multi-agent formalism and algorithms wich insure their respect. The use of a multi-agent model allows to take advantage of the natural autonomy of agents and the multi-level aspect of our model permits to modeled entities to reason about the organisational hierarchy of the system, carrying the explicit notion of level.Besides the modeling of complex systems, this thesis also deals with the problematic related to their simulations,particularly, the fact that computer resources (used memory and microchips) needed to simulate with precision such systems are truly important. We propose a methodology to benefit from the muli-level simulations capacity to producecompromise between the simulation precision and the used computer resources.La problématique générale de cette thèse, qui s'inscrit dans le contexte du projet européen InTraDE (Intelligent Transportation for Dynamic Environment), concerne la modélisation de systèmes de systèmes (SdS). Un SdS est un système composé d'une hiérarchie de systèmes autonomes présents à différents niveaux de représentation. Cette thèse répond au besoin d'outils de modélisation généralistes respectant les caractéristiques fondamentales des SdS,en proposant un formalisme multi-agents multi-niveaux et les algorithmes qui assurent le respect de ces caractéristiques. L'utilisation d'un modèle multi-agents permet de profiter de l'autonomie naturelle des agents et l'aspect multi-niveaux de notre modèle permet aux entités modélisées de raisonner à propos de l'organisation hiérarchique du système en leur offrant la notion explicite de niveau.En plus de la modélisation des systèmes complexes, cette thèse aborde les problématique liées à leur simulation, en particulier, le fait que les ressources informatiques (mémoire et microprocesseur utilisés) nécessaires pour simuler avec précision de tels systèmes sont particulièrement importantes. Nous proposons ainsi une méthodologie pour tirer partie de la capacité des simulations multi-niveaux à produire un compromis entre la précision de la simulation et les ressources informatiques utilisées

Conception and modeling of systems of systems : a multi-level mult-agent approach

La problématique générale de cette thèse, qui s'inscrit dans le contexte du projet européen InTraDE (Intelligent Transportation for Dynamic Environment), concerne la modélisation de systèmes de systèmes (SdS). Un SdS est un système composé d'une hiérarchie de systèmes autonomes présents à différents niveaux de représentation. Cette thèse répond au besoin d'outils de modélisation généralistes respectant les caractéristiques fondamentales des SdS, en proposant un formalisme multi-agents mullti-niveaux et les algorithmes qui assurent le respect de ces caractéristiques. L'utilisation d'un modèle multi-agents permet de profiter de l'autonomie naturelle des agents et l'aspect multi-niveaux de notre modèle permet aux entités modélisées de raisonner à propos de l'organisation hiérarchique du système en leur offrant la notion explicite de niveau. En plus de la modélisation des systèmes complexes, cette thèse aborde les problèmatique liées à leur simulation, en particulier, le fait que les ressources informatiques (mémoire et microprocesseur utilisés) nécessaires pour simuler avec précision de tels systèmes sont particulièrement importantes. Nous proposons ainsi une méthodologie pour tirer partie de la capacité des simulations multi-niveaux à produire un compromis entre la précision de la simulation et les ressources informatiques utilisées.The main problematic of this thesis, which takes place in the context of the european project InTraDE (Intelligent Transportation for Dynamic Environment), deals with the modeling of systems of systems (SoS). A SoS is a system composed of a hierarchy of autonomous systems present in several representation levels. This thesis answers the need of generic modeling tools respecting the fundamental characteristics of SoS, proposing a multi-level multi-agent formalism and algorithms wich insure their respect. The use of a multi-agent model allows to take advantage of the natural autonomy of agents and the multi-level aspect of our model permits to modeled entities to reason about the organisational hierarchy of the system, carrying the explicit notion of level. Besides the modeling of complex systems, this thesis also deals with the problematic related to their simulations, particularly, the fact that computer resources (used memory and microchips) needed to simulate with precision such systems are truly important. We propose a methodology to benefit from the muli-level simulations capacity to produce compromise between the simulation precision and the used computer resources

Multilevel Agent-Based Modeling of System of Systems

—This paper deals with the generic modeling of systems of systems (SoSs) using agent-based modeling. SoSs are large-scale systems, including numerous—possibly heterogeneous— interacting component systems evolving in a dynamic environment. The aim of this paper is to provide generic formalism allowing to represent and control the whole complexity of a SoS using agent-based simulations. In particular, organizational aspects of SoSs are managed with the Agent–Group–Role model. Functional aspects, guiding SoSs to accomplish their global goals, are handled via a functional specification. Multilevel aspects are mod-eled with the Influence Reaction Model for Multilevel Simulation (IRM4MLS) agent-based meta-model. Models generated using this formalism encompass static and dynamic aspects of SoSs. They consider reorganization of SoSs caused by changes of goals or subsystem capacity. All these elements are illustrated in this paper using a SoS case study of Intelligent Autonomous Vehicles initiated by the Intelligent Transportation for Dynamic Environment (InTraDE) European project to automate the port container logistic. Index Terms—Agent-based modeling (ABM), complex system engineering, systems of systems (SoSs)

Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations

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Engineering hierachical complex systems : an agent-based approach - The case of flexible manufacturing systems

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Multi-agent Multi-level Modeling - A methodology to Simulate Complex Systems

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Effect of Tocilizumab vs Usual Care in Adults Hospitalized With COVID-19 and Moderate or Severe Pneumonia

International audienceImportance Severe pneumonia with hyperinflammation and elevated interleukin-6 is a common presentation of coronavirus disease 2019 (COVID-19).Objective To determine whether tocilizumab (TCZ) improves outcomes of patients hospitalized with moderate-to-severe COVID-19 pneumonia.Design, Setting, and Particpants This cohort-embedded, investigator-initiated, multicenter, open-label, bayesian randomized clinical trial investigating patients with COVID-19 and moderate or severe pneumonia requiring at least 3 L/min of oxygen but without ventilation or admission to the intensive care unit was conducted between March 31, 2020, to April 18, 2020, with follow-up through 28 days. Patients were recruited from 9 university hospitals in France. Analyses were performed on an intention-to-treat basis with no correction for multiplicity for secondary outcomes.Interventions Patients were randomly assigned to receive TCZ, 8 mg/kg, intravenously plus usual care on day 1 and on day 3 if clinically indicated (TCZ group) or to receive usual care alone (UC group). Usual care included antibiotic agents, antiviral agents, corticosteroids, vasopressor support, and anticoagulants.Main Outcomes and Measures Primary outcomes were scores higher than 5 on the World Health Organization 10-point Clinical Progression Scale (WHO-CPS) on day 4 and survival without need of ventilation (including noninvasive ventilation) at day 14. Secondary outcomes were clinical status assessed with the WHO-CPS scores at day 7 and day 14, overall survival, time to discharge, time to oxygen supply independency, biological factors such as C-reactive protein level, and adverse events.Results Of 131 patients, 64 patients were randomly assigned to the TCZ group and 67 to UC group; 1 patient in the TCZ group withdrew consent and was not included in the analysis. Of the 130 patients, 42 were women (32%), and median (interquartile range) age was 64 (57.1-74.3) years. In the TCZ group, 12 patients had a WHO-CPS score greater than 5 at day 4 vs 19 in the UC group (median posterior absolute risk difference [ARD] −9.0%; 90% credible interval [CrI], −21.0 to 3.1), with a posterior probability of negative ARD of 89.0% not achieving the 95% predefined efficacy threshold. At day 14, 12% (95% CI −28% to 4%) fewer patients needed noninvasive ventilation (NIV) or mechanical ventilation (MV) or died in the TCZ group than in the UC group (24% vs 36%, median posterior hazard ratio [HR] 0.58; 90% CrI, 0.33-1.00), with a posterior probability of HR less than 1 of 95.0%, achieving the predefined efficacy threshold. The HR for MV or death was 0.58 (90% CrI, 0.30 to 1.09). At day 28, 7 patients had died in the TCZ group and 8 in the UC group (adjusted HR, 0.92; 95% CI 0.33-2.53). Serious adverse events occurred in 20 (32%) patients in the TCZ group and 29 (43%) in the UC group (P = .21).Conclusions and Relevance In this randomized clinical trial of patients with COVID-19 and pneumonia requiring oxygen support but not admitted to the intensive care unit, TCZ did not reduce WHO-CPS scores lower than 5 at day 4 but might have reduced the risk of NIV, MV, or death by day 14. No difference on day 28 mortality was found. Further studies are necessary for confirming these preliminary results.Trial Registration ClinicalTrials.gov Identifier: NCT0433180

Effect of anakinra versus usual care in adults in hospital with COVID-19 and mild-to-moderate pneumonia (CORIMUNO-ANA-1): a randomised controlled trial

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