We examine which capabilities technologies provide to support collaborative process modeling. We develop a model that explains how technology capabilities impact cognitive group processes, and how they lead to improved modeling outcomes and positive technology beliefs. We test this model through a free simulation experiment of collaborative process modelers structured around a set of modeling tasks. With our study, we provide an understanding of the process of collaborative process modeling, and detail implications for research and guidelines for the practical design of collaborative process modeling.

Le fort développement actuel des systèmes électroniques embarqués nous conduit à relever le défi de leur fiabilisation, ceci d’autant plus que des organes de sécurité sont souvent concernés et que ces systèmes opèrent dans des conditions environnementales difficiles avec une exigence de réduction de coût drastique. Ce qui caractérise le mieux l’évolution récente de ces systèmes électroniques embarqués c’est une forte intégration qui conduit à réduire leur encombrement et leur poids tout en augmentant la puissance électrique convertie. Il en résulte automatiquement une augmentation de la densité de puissance dissipée et l’étude de leur comportement électrothermique prend, dans ces conditions, une importance fondamentale. Le présent travail concerne le développement d’outils précis de modélisation électrothermique qui permettent d’appréhender l’impact de la technologie choisie (conception, connectiques, matériaux …) sur les phénomènes causés par les défauts qui apparaissent avec le vieillissement. Des règles de robustesse spécifiques à chaque technologie pourront être édictées à l’aide de simulations 3D distribuées présentées dans le mémoire. Dans un premier temps la modélisation électrothermique compacte a été abordée. Ensuite, en se limitant aux modules MOS de puissance, une première classe de problèmes caractérisée par l’absence de commutation peut être traitée en ayant recours à une modélisation électrothermique par éléments finis qui considère que le composant est constitué par un ensemble de zones de résistivités électriques et de conductivités thermiques différentes. Une tentative a été faite en vue d’étendre l’étude électrothermique aux classes de problèmes mettant en œuvre des MOS de puissance fonctionnant en régime de commutation. Le modèle électrique distribué doit alors être capable de calculer et de répartir les pertes totales (état passant, état bloqué et commutation) pour un régime de commutation rapide. Enfin, un soin particulier a été accordé à l’étude du fonctionnement en avalanche, une méthode basée sur l’expérimentation et l’utilisation d’un modèle électrothermique simple afin d’estimer la température de jonction d’un MOSFET de puissance lors de son fonctionnement en régime d’avalanche de courte durée a été développée. Pour conclure, on a démontré qu’il n’existe pas une réponse unique en termes de modélisation électrothermique et que chaque méthode vise à résoudre une classe spécifique de problèmes / The strong current development of embedded electronic systems leads us to the challenge of their reliability, all the more so as the security organs are often involved and that these systems operate in harsh environmental conditions with a requirement to reduce cost drastically. What best characterizes the recent evolution of the embedded electronic systems is a strong integration that leads to reduce their size and weight while increasing the electrical power converted. This automatically increases the power density dissipated and so the study of their electro-thermal behavior becomes of fundamental importance. The present work concerns the development of specific tools that allow electro-thermal modeling to understand the impact of the chosen technology (design, connections, materials ...) on the phenomena caused by defects that occur with ageing. Robustness rules specific to each technology may be adopted using 3D simulations presented in the report. At first, compact electro-thermal modeling was discussed. Second, considering power MOS modules which operate in a non-switching mode, a first class of problems can be treated by using a finite element electro-thermal modeling that assumes that the components act as a set of zones whose electrical and thermal conductivities are different. An attempt was made to extend the electro-thermal study to classes of problems where power MOSFETs are switching. Distributed electrical models must then be able to calculate and allocate total losses (on-state, off-state and switching) for a fast switching rate. Finally, particular attention has been given to the study of avalanche mode operation; a method based on experimentation and the use of a simple electro-thermal model to estimate the junction temperature of a power MOSFET when operating in short duration avalanche mode has been developed. To conclude, we have demonstrated that there is no single answer in terms of electro-thermal modeling and each method developed aims to solve a specific class of problems

Erosion and sediment delivery from upland areas to waterbodies is a major problem impacting water quality in the United States and elsewhere. Measures to reduce these impacts are either targeted at reducing erosion on-site or at reducing delivery of sediment to waterbodies. AMEENA (Areal Modeling of Erosion for Environmental Nonpoint Applications) is a spatially distributed model that estimates erosion and deposition on a watershed scale by predicting erosion and transport over the landscape surface. Erosion is predicted based on the Revised Universal Soil Loss Equation (RUSLE), and sediment transport capacity is estimated as a function of upslope flow volume, local gradient, and land use. Gross erosion is routed to edge-of-stream with a routing algorithm that iteratively compares available sediment with transport capacity on a cell by cell basis from ridge cells to stream cells. The model is implemented completely within a raster GIS to facilitate use of the model as a tool to readily evaluate impact of land use practices on sediment delivery to streams. AMEENA was validated using field data of net erosion and sediment deposition from three field studies. AMEENA predicted the spatial distribution of net erosion and deposition better than WaTEM/SEDEM which is a distributed parameter erosion model based on a similar modeling approach. AMEENA's suitability to simulate the impact of management practices such as filter strips and critical area planting was evaluated on plot (profile) scale and catchment scale simulations. Results of plot scale simulations were intuitive and the model proved more reasonable for these scenarios than did RUSLE2 and WEPP. The catchment scale study highlighted features of AMEENA that are not available in RUSLE2 and WEPP in terms of identifying erosion “hot spots” and the ability to utilize the explicit sediment flow path identification in locating best placement of off-site sediment control measures. Since AMEENA does not account for in-stream erosion processes, it is not suitable for simulating areas dominated by channel or gully erosion. / Ph. D.

A poluição hídrica é um dos principais desafios ambientais enfrentados atualmente, causada, principalmente, pelas atividades humanas que introduzem substâncias e materiais prejudiciais aos sistemas ambientais. Umas das principais formas de poluição hídrica é por meio do enriquecimento de nutrientes que traz como consequência a eutrofização das águas. Esse processo altera as características ecológicas dos ecossistemas aquáticos, causando impactos ambientais, econômicos e sociais. Na bacia hidrográfica do ribeirão do Lobo, localizada na região centro-leste do estado de São Paulo, observa-se a presença de diversas atividades que podem alterar a qualidade de suas águas se não forem devidamente planejadas e geridas. Sendo assim, o objetivo desse trabalho foi avaliar os efeitos das atividades humanas sobre o aporte de nutrientes na bacia hidrográfica do ribeirão do Lobo. Para tanto, foram simuladas as cargas e concentrações de fósforo e nitrogênio total nos cursos hídricos da bacia, por meio de uma modelagem distribuída a partir do acoplamento de equações empíricas em ambiente SIG. Informações de uso e ocupação do solo, topográficas, demográficas e hidrológicas foram utilizadas para simular as cargas e concentrações de nutrientes geradas por fontes pontuais e difusas de poluição. Análises dos parâmetros físicos, químicos e biológicos das águas do rio Itaqueri, ribeirão do Lobo e córrego Água Branca foram realizadas a fim de avaliar a qualidade das águas e o desempenho do método utilizado. Os resultados indicam que as cargas simuladas de nitrogênio e fósforo total são majoritariamente geradas por fontes difusas de poluição, com percentual de 81% e 76% respectivamente. A sub-bacia do rio Itaqueri é a região mais crítica da área de estudo, produzindo mais de 50% das cargas de nitrogênio e fósforo total. De toda a carga pontual produzida anualmente na bacia, aproximadamente 90% são geradas na sub-bacia do rio Itaqueri via córrego Água Branca. Os modelos de regressão linear entre as concentrações simuladas e observadas apresentaram relações significativas. Para o nitrogênio, o coeficiente de determinação (R²) encontrado foi igual a 0,73 (p < 0,05) e, para o fósforo, o valor encontrado foi igual a 0,72 (p < 0,05). Esse estudo mostrou que, apesar das limitações, a metodologia foi representativa para a área de estudo, indicando que o modelo foi capaz de diagnosticar e predizer a distribuição espacial da concentração de nutrientes nos sistemas hídricos da bacia hidrográfica do ribeirão do Lobo. / Water pollution is one of the main environmental challenges currently facing, caused mostly by human activities that introduce harmful substances and materials into environmental systems. One of the main forms of water pollution is through the enrichment of nutrients that results in eutrophication of water. This process may change the ecological characteristics of aquatic environments, causing environmental, economic and social impacts. In the Lobo river basin, located in the central region of São Paulo state, several activities can pollute the water of the basin. Thus, the objective of this work was to evaluate the effects of human activities on the nutrient supply in the Lobo river basin. For that, the loads and concentrations of total phosphorus and total nitrogen were simulated for the watercourses through a distributed modeling from the combination of empirical equations in GIS. Land use, topographical, demographic and hydrological information were used to simulate the loads and concentrations of nutrients generated by point sources and diffuse pollution sources. Physical, chemical and biological analysis of waters of the Itaqueri, Lobo and Água Branca streams were carried out in order to evaluate the water quality and the performance of the method used. The results revealed that the simulated loads of total nitrogen and total phosphorus are mostly generated by diffuse sources, with a percentage of 81% and 76% respectively. The Itaqueri river sub-basin is the most critical region of the study area, producing more than 50% of total nitrogen and total phosphorus loads. It was also observed that of all point load produced annually in the basin, 90% are generated in the river Itaqueri sub-basin, through Água Branca stream. The linear regression models between the simulated and observed concentrations of nitrogen and phosphorus presented significant relationship. For nitrogen, the determination coefficient (R²) found was 0.73 (p < 0.05) and for phosphorus the value found was 0.72 (p < 0.05). This study showed that the methodology was representative for the study area, indicating that the model was able to assess the spatial distribution of nutrient concentration in the water systems of the Lobo river basin.

Les modèles hydrologiques sont des outils indispensables pour calculer les débits a l’exutoire des bassins versants, la gestion des aménagements hydrauliques ou encore la prévision et la prévention des inondations. Les précipitations représentent la variable climatique principale à l’origine des débits des cours d’eau qui s’écoulent au sein d’un bassin versant. De ce fait, la réponse hydrologique du bassin est fortement dépendante de la représentativité des données d’entrée de précipitation.Les radars météorologiques, qui permettent aujourd’hui d’accéder a des mesures a haute résolution spatiale et temporelle des champs de précipitation, sont de plus en plus utilises dans le domaine de la prévision, pour le suivi des situations hydrométéorologiques. Cependant, la mesure des précipitations par radar est entachée d’erreurs qui peuvent affecter gravement la qualité des simulations de débit. De ce fait, l’utilisation des données de précipitations a haute résolution spatiale pour la modélisation hydrologique est souvent limitée par rapport a l’utilisation des données pluviométriques.Récemment, Météo-France a développe une réanalyse des lames d’eau au pas de temps horaire, sur une durée de 10 ans, en combinant l’ensemble des données de précipitation radar et pluviométriques : les mesures radars ont été corrigées et étalonnées avec le réseau de mesure au sol horaire et journalier. Dans cette thèse, nous proposons d’étudier l’intérêt de cette nouvelle base de données à haute résolution spatiale pour la modélisation pluie-débit.Dans un premier temps, nous avons développe et valide un modèle hydrologique semi-distribue qui a la capacité de fonctionner pour différentes résolutions spatiales, de la représentation globale jusqu’a une discrétisation spatiale très fine des bassins. Dans un deuxième temps, l’impact de la résolution spatiale des données d’entrée de précipitation sur la simulation des débits a été analysé. L’apport de l’information radar pour l’estimation des précipitations a été évalue par rapport a une utilisation exclusive des pluviomètres, par le biais de la modélisation pluie-débit en termes de précision des débits a l’exutoire des bassins. Enfin, le modèle semi-distribue TGR a été comparé avec le modèle global GRP actuellement opérationnel dans les Services de Prévision des Crues. L’originalité de notre travail réside sur l’utilisation de données d’observation sur un large échantillon de 181 bassins versants français représentant une grande diversité de tailles et conditions climatiques, ce qui nous permet d’apporter un diagnostic robuste et des éléments de réponse sur les problématiques scientifiques traitées. / Hydrologic models are essential tools to compute the catchment rainfall-runoff response required for river management and flood forecast purposes. Precipitation dominates the high frequency hydrological response, and its simulation is thus dependent on the way rainfall is represented. In this context, the sensitivity of runoff hydrographs to the spatial variability of forcing data is a major concern of researchers. However, results from the abundant literature are contrasted and it is still difficult to reach a clear consensus.Weather radar is considered to be helpful for hydrological forecasting since it provides rainfall estimates with high temporal and spatial resolution. However, it has long been shown that quantitative errors inherent to the radar rainfall estimates greatly affect rainfall-runoff simulations. As a result, the benefit from improved spatial resolution of rainfall estimates is often limited for hydrological applications compared to the use of traditional ground networks.Recently, Météo-France developed a rainfall reanalysis over France at the hourly time step over a 10-year period combining radar data and raingauge measurements: weather radar data were corrected and adjusted with both hourly and daily raingauge data. Here we propose a framework to evaluate the improvement in streamflow simulation gained by using this new high resolution product.First, a model able to cope with different spatial resolutions, from lumped to semi-distributed, was developed and validated. Second, the impact of spatial rainfall resolution input on streamflow simulation was investigated. Then, the usefulness of spatial radar data measurements for rainfall estimates was compared with an exclusive use of ground raingauge measurements and evaluated through hydrological modelling in terms of streamflow simulation improvements. Finally, semi-distributed modelling with the TGR model was performed for flood forecasting and compared with the lumped forecasting GRP model currently in use in the French flood forecast services. The originality of our work is that it is based on actual measurements from a large set of 181 French catchments representing a variety of size and climate conditions, which allows to draw reliable conclusions.

<div>With increasing focus on large scale planning and allocation of resources for protection against future flood risk, it is necessary to analyze and improve the deficiencies in the conventional flood modeling approach through a better understanding of the interactions between river hydrodynamics and subsurface processes. Recent studies have shown that it is possible to improve the flood inundation modeling and mapping using physically-based integrated models that incorporate observable data through assimilation and simulate hydrologic fluxes using the fundamental laws of conservation of mass at multiple spatiotemporal scales. However, despite the significance of integrated modeling in hydrology, it has received relatively less attention within the context of flood hazard. The overall aim of this dissertation is to study the heterogeneity in complex physical processes that govern the watershed response during flooding and incorporate these effects in integrated models across large scales for improved flood risk estimation. Specifically, this dissertation addresses the following questions: (1) Can physical process incorporation using integrated models improve the characterization of antecedent conditions and increase the accuracy of the watershed response to flood events? (2) What factors need to be considered for characterizing scale-dependent physical processes in integrated models across large watersheds? (3) How can the computational efficiency and process representation be improved for modeling flood events at large scales? (4) Can the applicability of integrated models be improved for capturing the hydrodynamics of unprecedented flood events in complex urban systems?</div><div><br></div><div>To understand the combined effect of surface-subsurface hydrology and hydrodynamics on streamflow generation and subsequent inundation during floods, the first objective incorporates an integrated surface water-groundwater (SW-GW) modeling approach for simulating flood conditions. The results suggest that an integrated model provides a more realistic simulation of flood hydrodynamics for different antecedent soil conditions. Overall, the findings suggest that the current practice of simulating floods which assumes an impervious surface may not be providing realistic estimates of flood inundation, and that an integrated approach incorporating all the hydrologic and hydraulic processes in the river system must be adopted.</div><div><br></div><div>The second objective focuses on providing solutions to better characterize scale-dependent processes in integrated models by comparing two model structures across two spatial scales and analyzing the changes in flood responses. The results indicate that since the characteristic length scales of GW processes are larger than SW processes, the intrinsic scale (or resolution) of GW in integrated models should be coarser when compared to SW. The results also highlight the degradation of streamflow prediction using a single channel roughness when the stream length scales are increased. A distributed channel roughness variable along the stream length improves the modeled basin response. Further, the results highlight the ability of a dimensionless parameter 𝜂1, representing the ratio of the reach length in the study region to maximum length of the single stream draining at that point, for identifying which streams may require a distributed channel roughness.</div><div><br></div><div>The third objective presents a hybrid flood modeling approach that incorporates the advantages of both loosely-coupled (‘downward’) and integrated (‘upward’) modeling approaches by coupling empirically-based and physically-based approaches within a watershed. The computational efficiency and accuracy of the proposed hybrid modeling approach is tested across three watersheds in Indiana using multiple flood events and comparing the results with fully- integrated models. Overall, the hybrid modeling approach results in a performance comparable to a fully-integrated approach but at a much higher computational efficiency, while at the same time, providing objective-oriented flexibility to the modeler.</div><div><br></div><div>The fourth objective presents a physically-based but computationally-efficient approach for modeling unprecedented flood events at large scales in complex urban systems. The application of the proposed approach results in accurate simulation of large scale flood hydrodynamics which is shown using Hurricane Harvey as the test case. The results also suggest that the ability to control the mesh development using the proposed flexible model structure for incorporating important physical and hydraulic features is as important as integration of distributed hydrology and hydrodynamics.</div>

Cette recherche vise à résoudre un problème particulier du contrôle de vibration des structures intelligentes. Notre objectif est de réduire les vibrations dans une zone spécifique de la structure intelligente avec une perturbation qui couvre une large gamme de fréquences. De plus, dans cette zone spécifique, ni l'actionnement ni la détection ne sont possibles.Ici, nous faisons face à plusieurs défis principaux. Premièrement, nous devons contrôler les vibrations d’une zone spécifique de la structure, alors que nous n’avons accès aux mesures que dans d’autres zones. Deuxièmement, la large bande passante de la perturbation implique que nombreux modes doivent être contrôlés au même temps, ce qui nécessite l'utilisation de plusieurs actionneurs et capteurs. Cela conduit à un contrôleur MIMO difficile à obtenir avec les méthodes classiques de conception de contrôleur. Troisièmement, il faut éviter le problème de propagation, qui consiste à garantir la stabilité en boucle fermée lorsque le contrôleur basé sur un modèle est appliqué à la configuration réelle. Pour relever ces défis, nous étudions deux stratégies de contrôle: le contrôle centralisé et le contrôle distribué.Pour le contrôle centralisé, nous proposons une méthodologie qui nous permet d’obtenir un contrôleur MIMO simple permettant de relever ces défis. Tout d'abord, plusieurs techniques de modélisation et d’identification sont appliquées pour obtenir un modèle précis d'ordre faible de la structure intelligente. Ensuite, une méthode de synthèse basée sur le contrôle H_∞ avec un critère H_∞ particulièrement proposé est appliquée. Ce critère H_∞ intègre plusieurs objectifs de contrôle, y compris les défis principaux. En particulier, le problème de débordement se transforme en un problème de stabilité robuste et sera garanti en utilisant ce critère. Le contrôleur H_∞ obtenu est une solution standard du problème H_∞. Le contrôleur final est obtenu en simplifiant ce contrôleur H_∞ sans perdre la stabilité en boucle fermée ni dégrader les performances. Cette méthodologie est validée sur une structure de poutre avec des transducteurs piézoélectriques et la zone centrale est celle où les vibrations devraient être réduites. L'efficacité du contrôleur obtenu est validée par des simulations et des expériences.Pour le contrôle distribué, on considère la même structure de poutre et les mêmes objectifs de contrôle. Il existe des méthodes visant à concevoir des contrôleurs distribués pour les systèmes spatialement interconnectés. Cette recherche propose une méthode basée sur la FEM, associée à plusieurs techniques de réduction de modèle, permettant de discrétiser spatialement la structure de poutre et d'en déduire les modèles d’espace d'état des sous-systèmes interconnectés. La conception des contrôleurs distribués ne sera pas abordée dans cette recherche. / This research aims at solving a particular vibration control problem of smart structures. We aim at reducing the vibration in a specific zone of the smart structure under the disturbance that covers a wide frequency band. Moreover, at this specific zone, neither actuation nor sensing is possible.Here we face several main challenges. First, we need to control the vibration of a specific zone of the structure while we only have access to measurements at other zones. Second, the wide bandwidth of the disturbance implies that numerous modes should be controlled at the same time which requires the use of multiple actuators and sensors. This leads to a MIMO controller which is difficult to obtain using classical controller design methods. Third, the so-called spillover problem must be avoided which is to guarantee the closed-loop stability when the model-based controller is applied on the actual setup. To tackle these challenges, we investigate two control strategies: the centralized control and the distributed control.For centralized control, we propose a methodology that allows us to obtain a simple MIMO controller that accomplishes these challenges. First, several modeling and identification techniques are applied to obtain an accurate low-order model of the smart structure. Then, an H_∞ control based synthesis method with a particularly proposed H_∞ criterion is applied. This H_∞ criterion integrates multiple control objectives, including the main challenges. In particular, the spillover problem is transformed into a robust stability problem and will be guaranteed using this criterion. The obtained H_∞ controller is a standard solution of the H_∞ problem. The final controller is obtained by further simplifying this H_∞ controller without losing the closed-loop stability and degrading the performance. This methodology is validated on a beam structure with piezoelectric transducers and the central zone is where the vibration should be reduced. The effectiveness of the obtained controller is validated by simulations and experiments.For distributed control, we consider the same beam structure and the same control objectives. There exist methods aiming at designing distributed controllers of spatially interconnected system. This research proposes a FEM based method, combined with several model reduction techniques, that allows to spatially discretize the beam structure and deduce the state-space models of interconnected subsystems. The design of distributed controllers will not be tackled in this research.