Designers commonly use computer-based modeling and simulation methods to predict artifact behavior. Such predictions are central to engineering decision making. As such, determining how well they correspond to actual artifact behavior is a problem of critical importance. A significant aspect of this problem is determining whether the model used to generate the behavioral predictionsi.e., the behavioral modelreflects the relevant physical phenomena. The process of doing this is referred to as behavioral model validation. Prior works take an integrated approach to validation in which model creators and model users interact throughout the modeling and simulation process. Although effective for many problems, this type of approach is not appropriate for model reuse scenarios. Model validation requires knowledge about the model and its use. In model reuse scenarios, model creators and model users operate in independent processes with limited inter-process communication. The core challenge to behavioral model validation in this setting is that, in general, neither model creators nor model users possess the requisite knowledge to perform behavioral model validation. Presented in this thesis is a conceptual framework for validating reusable behavioral models in model reuse scenarios. This framework solves the problem of creator-user separation by defining specific validation responsibilities for each and an interface by which they communicate. This interface consists of a formal description of the models limitations and the domain over which these limitations are known to be true. The framework is illustrated through basic engineering examples.

Today s market is driven by the desire for increasingly complex products that perform well from manufacturing to disposal. Designing these products for multiple lifecycle phases requires effective management of engineering knowledge and integration of this knowledge across multiple disciplines. By managing this knowledge, products can be realized faster, perform better and be more complex. However, management techniques are often very costly and managers can easily become bogged down with large quantities of information, slowing the design process and degrading knowledge transfer. Thus, a need exists for effective yet inexpensive knowledge management. One approach for decreasing the costs associated with generating design knowledge is to reuse modules of existing knowledge. In Model-Based Systems Engineering (MBSE), information about a design is stored formally in many knowledge structures, or models, including requirements, stakeholders, and analyses. To support the reuse of the existing knowledge in design, MBSE is used as a basis for integrating engineering analysis models. In this thesis, a framework is presented for model classification that organizes models by components and aspects. This scheme is found to be useful in classifying engineering analysis models for reuse by storing them as a set in containers known as Multi-Aspect Component Models (MAsCoMs). Each model in a MAsCoM is related to the formal structure model of a physical component, and to the many aspects of the component that the model represents. The Systems Modeling Language, OMG SysML, is used to implement MAsCoMs and support MBSE. Validation of the MAsCoM concept is performed with fluid-power design examples, including a log splitter, scissor lift, and hydraulic excavator. In these examples, MAsCoMs improve design value by 1) Classifying modular and composable engineering analysis models for reuse in multiple disciplines, and 2) Providing knowledge modules to computer-automated algorithms for the future automated composition of component models into system models to perform system-level analyses.

Adaptive reuse of parametric finite element analysis (FEA) models is a common form of reuse that involves integrating new information into an archived FEA model to apply it towards a new similar physical problem. Adaptive reuse of archived FEA models is often motivated by the need to assess the impact of minor improvements to component-based designs such as addition of new structural components, or the need to assess new failure modes that arise when a device is redesigned for new operating environments or loading conditions. Successful adaptive reuse of FEA models involves reference to supporting documents that capture the formulation of the model to determine what new information can be integrated and how. However, FEA models and supporting documents are not stored in formats that are semantically rich enough to support automated inference of their relevance to a modelers needs. The modelers inability to precisely describe information needs and execute queries based on such requirements results in inefficient queries and time spent manually assessing irrelevant models. The central research question in this research is thus how do we incorporate a modelers intent into automated retrieval of FEA models for adaptive reuse? An automated retrieval method to support adaptive reuse of parametric FEA models has been developed in the research documented in this thesis. The method consists of a classification-based retrieval method based on ALE subsumption hierarchies that classify models using semantically rich description logic representations of physical problem structure and a reusability-based ranking method. Conceptual data models have been developed for the representations that support both retrieval and ranking of archived FEA models. The method is validated using representations of FEA models of several classes of electronic chip packages. Experimental results indicate that the properties of the representation methods support effective automation of retrieval functions for FEA models of component-based designs.

Design synthesis is a fundamental engineering task that involves the creation of structure from a desired functional specification; it involves both creating a system topology as well as sizing the system's components. Although the use of computer tools is common throughout the design process, design synthesis is often a task left to the designer. At the synthesis stage of the design process, designers have an extensive choice of design alternatives that need to be considered and evaluated. Designers can benefit from computational synthesis methods in the creative phase of the design process. Recent increases in computational power allow automated synthesis methods for rapidly generating a large number of design solutions. Combining an automated synthesis method with an evaluation framework allows for a more thorough exploration of the design space as well as for a reduction of the time and cost needed to design a system. To facilitate computational synthesis, knowledge about feasible system configurations must be captured. Since it is difficult to capture such synthesis knowledge about any possible system, a design domain must be chosen. In this thesis, the design domain is hydraulic systems. In this thesis, Model-Driven Software Development concepts are leveraged to create a framework to automate the synthesis of hydraulic systems will be presented and demonstrated. This includes the presentation of a domain specific language to describe the function and structure of hydraulic systems as well as a framework for synthesizing hydraulic systems using graph grammars to generate system topologies. Also, a method using graph grammars for generating analysis models from the described structural system representations is presented. This approach fits in the context of Model-Based Systems Engineering where a variety of formal models are used to represent knowledge about a system. It uses the Systems Modeling Language developed by The Object Management Group (OMG SysML™) as a unifying language for model definition.

L'ingénierie des systèmes complexes et systèmes de systèmes conduit souvent à des activités de modélisation (MA) complexes. Les problèmes soulevés par les MA sont notamment : comprendre le contexte dans lequel elles sont exécutées, comprendre l'impact sur les cycles de vie des modèles qu'elles produisent, et finalement trouver une approche pour les maîtriser. L'objectif principal de cette thèse est d'élaborer une approche formelle pour adresser ce problème. Dans cette thèse, après avoir étudié les travaux connexes en ingénierie système et plus spécifiquement ceux qui portent sur la co-ingénierie du système à faire (le produit) et du système pour faire (le projet), nous développons une méthodologie nommée MODEF pour traiter ce problème. MODEF consiste en: (1) Caractériser les MA comme un système et plus généralement une fédération de systèmes. (2) Construire de manière itérative une architecture de ce système via la modélisation du contenu conceptuel des modèles produits par MA et leur cycle de vie, les tâches réalisées au sein des MA et leurs effets sur ces cycles de vie. (3) Spécifier les attentes sur ces cycles de vie. (4) Analyser les modèles (des MA) par rapport à ces attentes (et éventuellement les contraintes sur les tâches) pour vérifier jusqu'à quel point elles sont atteignables via la synthèse des points (ou états) acceptables. D'un point de vue pratique, l'exploitation des résultats de l'analyse permet de contrôler le déroulement des tâches de modélisation à partir de la mise en évidence de leur impact sur les modèles qu'elles produisent. En effet, cette exploitation fournit des données pertinentes sur la façon dont les MA se déroulent et se dérouleraient de bout en bout. A partir de ces informations, il est possible de prendre des mesures préventives ou correctives. Nous illustrons cela à l'aide de deux cas d'étude (le fonctionnement d'un supermarché et la modélisation de la couverture fonctionnelle d'un système). D'un point de vue théorique, les sémantiques formelles des modèles des MA et le formalisme des attentes sont d'abord données. Ensuite, les algorithmes d'analyse et d'exploitation sont présentés. Cette approche est brièvement comparée avec des approches de vérification des modèles et de synthèse de systèmes. Enfin, deux facilitateurs de la mise en œuvre de MODEF sont présentés. Le premier est une implémentation modulaire des blocs de base de MODEF. Le second est une architecture fédérée (FA) des modèles visant à faciliter la réutilisation des modèles formels en pratique. La formalisation de FA est faite dans le cadre de la théorie des catégories. De ce fait, afin de construire un lien entre abstraction et implémentation, des structures de données et algorithmes de base sont proposés pour utiliser FA en pratique. Différentes perspectives sur les composantes de MODEF concluent ce travail. / The engineering of complex systems and systems of systems often leads to complex modelling activities (MA). Some challenges exhibited by MA are: understanding the context where they are carried out and their impacts on the lifecycles of models they produce, and ultimately providing a support for mastering them. How to address these challenges with a formal approach is the central challenge of this thesis. In this thesis, after discussing the related works from systems engineering in general and the co-engineering of the system to be made (product) and the system for make (project) systems specifically, we position and develop a methodology named MODEF, that aims to master the operation of MA. MODEF consists in: (1) characterizing MA as a system (and more globally as a federation of systems) in its own right; (2) iteratively architecting this system through: the modelling of the conceptual content of the models produced by MA and their life cycles, the tasks carried out within MA and their effects on these life cycles; (3) specifying the expectations over these life cycles and; (4) analysing models (of MA) against expectations (and possibly tasks constraints) - to check how far expectations are achievable - via the synthesis of the acceptable behaviours. On a practical perspective, the exploitation of the results of the analysis allows figuring out what could happen with the modelling tasks and their impacts on the whole state of models they handle. We show on two case studies (the operation of a supermarket and the modelling of the functional coverage of a system) how this exploitation provides insightful data on how the system is end-to-end operated and how it can behave. Based on this information, it is possible to take some preventive or corrective actions on how the MA are carried out. On the foundational perspective, the formal semantics of three kinds of involved models and the expectations formalism are first discussed. Then the analysis and exploitation algorithms are presented. Finally this approach is roughly compared with model checking and systems synthesis approaches. Last but not least, two enablers whose first objectives are to ease the implementation of MODEF are presented. The first one is a modular implementation of MODEF's buildings blocks. The second one is a federated architecture (FA) of models which aims to ease working with formal models in practice. Despite the fact that FA is formalised within the abstract framework of category theory, an attempt to bridge the gap between abstraction and implementation is sketched via some basic data structures and base algorithms. Several perspectives related to the different components of MODEF conclude this work.