Rechenschaftsbericht des Rektors, 2009/2010

Für das akademische Jahr 2009/2010 legt das Rektorat gemäß § 16 Abs. 6 Satz 2 LHG seinen Rechenschaftsbericht vor

Forschungsbericht Universität Mannheim 2010 / 2011

Der Forschungsbericht bietet Ihnen eine Übersicht über die Forschungsschwerpunkte der Fakultäten, Abteilungen und Forschungseinrichtungen der Universität Mannheim. Dazu enthält der vorliegende Forschungsbericht Informationen über Einzelprojekte in den jeweiligen Fachdisziplinen sowie über zumeist fächerübergreifende Verbundprojekte wie Sonderforschungsbereiche, Forschergruppen, Wissenschaftscampi, Graduiertenschulen und Promotionskollegs. Die aus den Forschungsaktivitäten hervorgegangenen Publikationen, die Sie in diesem Bericht aufgelistet finden, leisten wichtige Beiträge zum wissenschaftlichen Fortschritt innerhalb der Disziplinen. Die ebenfalls aufgeführten Transferleistungen stellen Beiträge der Grundlagenwissenschaft zur Lösung gesellschaftlicher und wirtschaftlicher Herausforderungen dar. Nicht zuletzt enthält der Forschungsbericht Angaben zu wissenschaftlichen Preisen und Auszeichnungen, zu Veranstaltungen und Tagungen sowie zu akademischen Qualifikationen im Sinne von Promotionen und Habilitationen. Diese Angaben reflektieren die Reputation der Wissenschaftlerinnen und Wissenschaftler und ergänzen die sonstigen forschungsbezogenen Leistungen an der Universität Mannheim

System support for proactive adaptation

Applications in our modern, pervasive computing environments have to adapt themselves or their context in order to cope with changes. In the process, these pervasive applications should be as unobtrusive as possible, i.e., their adaptation should be automatic. In dynamic multi-user systems with shared resources and interactive applications, such adaptations cannot be scripted in advance. Instead, they have to be calculated at runtime. However, the necessary calculations quickly exceed the complexity that can be handled in real-time, i.e., without causing significant delays. The concept of proactive adaptation allows to change applications and/or context based on prediction of context and user behavior. Hence, proactive adaptation can reduce adaptation delays and avoid context interferences by determining coordinated adaptation plans ahead of time, instead of reactively when adaptation becomes necessary. Further, it helps to provide a seamless service to the user, while optimizing the overall system utility. This thesis presents a general framework and middleware-based system support for coordinated proactive adaptation in dynamic multi-user pervasive systems. The framework consists of five major components. The context interaction model and corresponding context broker offers context information, prediction, as well as actuation in a uniform fashion. The application configuration model allows applications to specify their requirements towards their context, as well as detail user preferences and duration-dependent utility and cost functions for adaptation optimization. Configuration algorithms calculate and rate all adaptation alternatives of an application given a current or predicted context and the specified rating functions, before coordination algorithms find interference-free adaptation plans for situations in which multiple applications share a context space. Finally, the adaptation control component combines the individual components of the framework in a two-dimensional control loop for proactive and fallback reactive adaptation. The prototype framework is evaluated in real-time simulations of an interactive pervasive system using recorded user traces

Application coordination in pervasive systems

Our future environment will be managed by a multitude of different pervasive systems. A pervasive system consists of users and devices which cooperate to provide functionality to the users. The provision of functionality is realized by pervasive applications. A major characteristic of pervasive applications is their context-interactivity. On one hand, pervasive applications are context-aware and can adapt themselves to changing context. This ability enables them to provide their functionality in different configurations. On the other hand, pervasive applications have the ability to influence and change the context themselves. A context change can be caused implicitly as a side effect of employed resources or explicitly through the use of actuators. Due to the context-interactivity, problems are likely to occur when two or more applications are executed in the same physical space. Since applications share a common context and interact with it, they can have a direct impact on each other. The described problem is defined as an interference in this thesis. An interference is an application-produced context that impairs the functionality provision of another application. To manage interferences in pervasive systems, a coordination framework is presented. The framework detects interferences using a context model and information about how applications interact with the shared context. The resolution of an interference is achieved through a coordinated application adaptation. The idea is based on the assumption that an alternative application configuration may yield a different context interaction. Thus, the framework determines a configuration for each application such that the context interactions do not interfere. Once a configuration is found for each application, the framework instructs applications to instantiate the selected configuration, resolving the interference. The framework is unique due to three design decisions. At first, the framework is realized as a cross-system coordination layer in order to allow an integration of arbitrary systems. Secondly, the integration of applications can be achieved through the extension of existing systems while preserving their system characteristics. Thirdly, the framework supports a generic interface to integrate arbitrary resolution strategies in order to allow the customization of the framework to the needs of different pervasive systems. The thesis introduces the theoretical concepts of the framework, presents a prototypical implementation and evaluates the prototype and its implemented concepts through extensive measurements