13 Zentrale Universitätseinrichtungen
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/14
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Item Open Access Grundsätze hochschuldidaktischer Arbeit : am Zentrum für Lehre und Weiterbildung(Stuttgart : Universität Stuttgart, Zentrum für Lehre und Weiterbildung, 2017) Braun, Thorsten; Kröber, Edith; Loewe, Simone; Qekaj, Avni; Rapp, Sonja; Kröber, Edith; Braun, Thorsten (Redaktion)Der Artikel befasst sich mit aktuellen, programmatischen Grundsätzen hochschuldidaktischer Arbeit, wie sie durch das Zentrum für Lehre und Weiterbildung der Universität Stuttgart verfolgt und umgesetzt werden. Ausgehend von einer Skizze des Europäischen Hochschulraums wird das Programmziel des "Lebenslangen Lernens" kritisch diskutiert und reflektiert. Anschließend werden die zentralen, thematischen Orientierungspunkte für praktische, hochschuldidaktische Arbeit vorgestellt und knapp umrissen. Der Artikel richtet sich an Hochschullehrende sowie Hochschuldidaktikerinnen und Hochschuldidaktiker.Item Open Access Process migration in a parallel environment(Stuttgart : Höchstleistungsrechenzentrum, Universität Stuttgart, 2016) Reber, Adrian; Resch, Michael (Prof. Dr.- Ing. Dr. h.c. Dr. h.c. Prof. E.h.)To satisfy the ever increasing demand for computational resources, high performance computing systems are becoming larger and larger. Unfortunately, the tools supporting system management tasks are only slowly adapting to the increase in components in computational clusters. Virtualization provides concepts which make system management tasks easier to implement by providing more flexibility for system administrators. With the help of virtual machine migration, the point in time for certain system management tasks like hardware or software upgrades no longer depends on the usage of the physical hardware. The flexibility to migrate a running virtual machine without significant interruption to the provided service makes it possible to perform system management tasks at the optimal point in time. In most high performance computing systems, however, virtualization is still not implemented. The reason for avoiding virtualization in high performance computing is that there is still an overhead accessing the CPU and I/O devices. This overhead continually decreases and there are different kind of virtualization techniques like para-virtualization and container-based virtualization which minimize this overhead further. With the CPU being one of the primary resources in high performance computing, this work proposes to migrate processes instead of virtual machines thus avoiding any overhead. Process migration can either be seen as an extension to pre-emptive multitasking over system boundaries or as a special form of checkpointing and restarting. In the scope of this work process migration is based on checkpointing and restarting as it is already an established technique in the field of fault tolerance. From the existing checkpointing and restarting implementations, the best suited implementation for process migration purposes was selected. One of the important requirements of the checkpointing and restarting implementation is transparency. Providing transparent process migration is important enable the migration of any process without prerequisites like re-compilation or running in a specially prepared environment. With process migration based on checkpointing and restarting, the next step towards providing process migration in a high performance computing environment is to support the migration of parallel processes. Using MPI is a common method of parallelizing applications and therefore process migration has to be integrated with an MPI implementation. The previously selected checkpointing and restarting implementation was integrated in an MPI implementation, and thus enabling the migration of parallel processes. With the help of different test cases the implemented process migration was analyzed, especially in regards to the time required to migrated a process and the advantages of optimizations to reduce the process’ downtime during migration.Item Open Access Mapping molecular surfaces of arbitrary genus to a sphere(2015) Frieß, FlorianMolecular surfaces are one of the most widely used visual representations for the analysis of molecules. They allow different properties of the molecule to be shown and allow additional information to be added, such as chemical properties of the atoms, using colour. With the usual representation of molecular surfaces being three dimensional there are common problems, such as occlusion and view-dependency. To solve these problems a two dimensional representation of the molecular surface can be created. For molecules with a surface of genus zero there are different methods of creating the sphere that is used as an intermediate object to create the map. For molecules with a higher genus this process becomes more difficult. Tunnels can only be mapped to the sphere if they are closed at some point inside the tunnel. Introducing arbitrary cuts can lead to small areas on the map. The deeper inside the tunnel the cut is placed the smaller the area. To avoid these small areas the cuts have to be placed close to the entrance of the tunnel. Therefore a mesh segmentation is performed to identify the tunnel and to create a genus zero surface for the molecule. Based on this identification further information can be displayed, such as geodesic lines showing how the tunnels are connected.Item Open Access Code execution reports: visually augmented summaries of executed source code fragments(2016) Siddiqui, Hafiz AmmarUnderstanding a fragment of code is important for developers as it enables them to optimize, debug and extend it. Developers adopt different procedures for understanding a piece of code, which involves going through the source code, documentation, and profilers results. Various code comprehension techniques have suggested code summarization approaches, which generates the intended behavior of code in natural language text. In this thesis, we present an approach to summarize the actual behavior of a method during its execution. For this purpose, we create a framework that facilitates the generation of interactive and web-based natural language reports with small embedded word-size visualizations. Then, we develop a tool that profiles a method for runtime behavior, and then it processes the information. The tool uses our framework to generate a visually augmented natural language summary report that explains the behavior of the code. In the end, we conduct a small user study to evaluate the quality of our code execution reports.Item Open Access Visual analytics of big data from distributed systems(2017) Kutzleb, AndréDistributed Systems are challenging to debug because the temporal order of events and distributed states are hard to track. The high complexity of distributed systems make fully automatic reasoning difficult to apply. Domain experts are often required to reason about the behavior of a system based on log files from various sources. This situation presents a good opportunity for visual analytics. Data from multiple sources can be preprocessed and visualized, and then domain experts can conduct exploratory analysis to accelerate the identification of issues. The goal of this master thesis was to create such a visual analytics tool to help domain experts explore data collected from distributed systems more efficiently and assist in identifying bugs and anomalies. The system was used by domain experts and helped to identify issues in a distributed system, showing that visual analytics can be a useful tool to assist domain experts in their daily work.Item Open Access Visualizing Optimization Trajectories(2019) Hägele, DavidNonlinear constraint optimization has many applications in technical, scientific as well as economic fields. Understanding solver behavior can help to improve solvers, choose appropriate hyperparameters, and formulate better performing nonlinear programs. This thesis proposes a visual analytics tool for analyzing constraint optimization problems. The optimization process is depicted by a set of two-dimensional trajectories, representing the trace of intermediate solutions during the optimization process. This allows us to obtain an overview of the evolution of the optimization process. To support detailed analysis, supplemental views are added to show the constraints violations and areas of feasible solution. Furthermore, different interaction techniques are implemented to facilitate the exploration process. To showcase the usefulness of the approach, findings from an exemplary analysis based on optimization logs of robot motion planning are presented.Item Open Access Online visualization of German power plants and their production(2017) Ullah, Kazi RiazMaps are used for centuries to visualize geographical or topological information and nowadays, with modern technology, we can create interactive maps that allow us to display and access additional information. Some of them have even become part of our daily life, such as, almost real-time traffic information. Furthermore, maps are often used to display data of population densities, temperatures and spatial distribution of geographical phenomenon. Fraunhofer Institute of Solar Energy ISE decided to build an interactive map that shows the locations of all power plants listed on the European Energy Exchange (EEX). Since July 2014, the Fraunhofer ISE has been providing interactive charts on electricity production and other related information about electricity and power generation in Germany. These charts became very popular and widely used by people from different professions, namely scientists, politicians, journalists as well as online/printed media. Due to the high popularity of these interactive energy charts, an interactive map has been added to the Energy Charts data visualization portal to make the framework more informative and interesting for users. The map has several search options and levels of detail for searching different power plant locations, technical data, and connectivity to the high voltage transmission lines. Furthermore, this new visualization framework is interconnected with the existing energy charts. The dynamic linking, brushing and filtering technique in both map and energy charts have enhanced the framework by an additional layer providing more visibility and information on the selected power plants.Item Open Access Die Klausur als Orakel? : Arbeitsergebnisse einer Klausurentwicklung in der Technischen Thermodynamik(Stuttgart : Universität Stuttgart, Zentrum für Lehre und Weiterbildung, 2018) Braun, Thorsten; Kröber, EdithDer Aufsatz stellt Zwischenergebnisse einer hochschuldidaktischen Kooperation mit dem Institut für Technische Thermodynamik und thermische Verfahrenstechnik (ITT) an der Universität Stuttgart vor. Es werden typische Schwachpunkte einer Klausur aus Perspektive einer Kompetenzmodellierung aufgezeigt und erläutert. Ziel ist es dabei, für Gütekriterien bei der Klausurgestaltung zu sensibilisieren und Ansatzpunkte aufzuzeigen, wie diese Kriterien umgesetzt werden können. Auch wenn die Ausführungen implizit auf eine Prüfungsmodellierung mittels Item Response Theory hinarbeiten, sind sie ohne Vorkenntnisse in der Testtheorie verständlich und umsetzbar.Item Open Access A fully coupled thermomechanical 3D model for all phases of friction stir welding(2016) Hoßfeld, MaxAlthough friction stir welding (FSW) has made its way to industrial application particularly in the last years, the FSW process, its influences and their strong interactions among themselves are still not thoroughly understood. The lack of understanding mainly arises from the adverse observability of the actual process with phenomena like material ow and deposition, large material deformations plus their complex thermo-mechanical interactions determining the weld formation and its mechanical properties. A validated numerical process model may be helpful for closing this gap as well as for an isolated assessment of individual influences and phenomena. Hereby such a model will be a valuable assistance for process and especially tool development. In this study a Coupled Eulerian-Lagrangian (CEL) approach with Abaqus V6.14 is used for modeling the whole FSW process within one continuous model. The resolution reached allows not only simulating the joining of two sheets into one and real tooling geometries but also burr and internal void formation. Results for temperature fields, surface and weld formation as well as process forces are shown and validated.Item Open Access Carl Gustav Jochmann als Sprachkritiker der Restauration(2017) Malo, Markus