Universität Stuttgart

Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1

Browse

Filters

2020 - 2025108

Settings

Start date: 2020Subject: search.filters.subject.600

Search Results

Now showing 1 - 10 of 108
  • Thumbnail Image
    ItemOpen Access
    Untersuchung der Antriebsstrangdynamik in Windenergieanlagen
    (2020) Horch, Joachim
    Diese Arbeit beschäftigt sich damit die Stabilität und Funktionstüchtigkeit des Antriebsstranges einer Windenergieanlage der Größenordnung 10 MW zu untersuchen. Hierfür erfolgt der Aufbau eines Computermodells einer 10-MW-Windenergieanlage mithilfe des Mehrkörpersimulationsprogrammes SIMPACK. Weiterhin wird eine Parameterstudie durchgeführt, welche über eine Matlab-induzierte SIMPACK-Simulation speziell ausgewählte Parameter des Antriebsstranges variiert, Simulationen durchführt und so den Einfluss bestimmter Parameter, sowie Parameterkombinationen, auf die Stabilität des Antriebsstranges prüft. Auf diese Weise sollen Stabilitätskriterien für einen Antriebsstrang dieser Größenordnung ermittelt werden. Es erfolgen sowohl statische, als auch dynamische Untersuchungen.
  • Thumbnail Image
    ItemOpen Access
    Touching data with PropellerHand
    (2022) Achberger, Alexander; Heyen, Frank; Vidackovic, Kresimir; Sedlmair, Michael
    Immersive analytics often takes place in virtual environments which promise the users immersion. To fulfill this promise, sensory feedback, such as haptics, is an important component, which is however not well supported yet. Existing haptic devices are often expensive, stationary, or occupy the user’s hand, preventing them from grasping objects or using a controller. We propose PropellerHand, an ungrounded hand-mounted haptic device with two rotatable propellers, that allows exerting forces on the hand without obstructing hand use. PropellerHand is able to simulate feedback such as weight and torque by generating thrust up to 11 N in 2-DOF and a torque of 1.87 Nm in 2-DOF. Its design builds on our experience from quantitative and qualitative experiments with different form factors and parts. We evaluated our prototype through a qualitative user study in various VR scenarios that required participants to manipulate virtual objects in different ways, while changing between torques and directional forces. Results show that PropellerHand improves users’ immersion in virtual reality. Additionally, we conducted a second user study in the field of immersive visualization to investigate the potential benefits of PropellerHand there.
  • Thumbnail Image
    ItemOpen Access
    Digital factory transformation from a servitization perspective : fields of action for developing internal smart services
    (2023) Neuhüttler, Jens; Feike, Maximilian; Kutz, Janika; Blümel, Christian; Bienzeisler, Bernd
    In recent years, a complex set of dynamic developments driven by both the economy and the emergence of digital technologies has put pressure on manufacturing companies to adapt. The concept of servitization, i.e., the shift from a product-centric to a service-centric value creation logic, can help manufacturing companies stabilize their business in such volatile times. Existing academic literature investigates the potential and challenges of servitization and the associated development of data-based services, so-called smart services, with a view to external market performance. However, with the increasing use of digital technologies in manufacturing and the development of internal smart services based on them, we argue that the existing insights on external servitization are also of interest for internal transformation. In this paper, we identify key findings from service literature, apply them to digital factory transformation, and structure them into six fields of action along the dimensions of people, technology, and organization. As a result, recommendations for designing digital factory transformation in manufacturing companies are derived from the perspective of servitization and developing internal smart services.
  • Thumbnail Image
    ItemOpen Access
    Wege zur Ermittlung von Energieeffizienzpotenzialen von Informations- und Kommunikationstechnologien
    (Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2020) Miller, Michael; Hufendiek, Kai (Prof. Dr.-Ing.)
  • Thumbnail Image
    ItemOpen Access
    A framework for similarity recognition of CAD models in respect to PLM optimization
    (2022) Zehtaban, Leila; Roller, Dieter (Univ.-Prof. Hon.-Prof. Dr.)
  • Thumbnail Image
    ItemOpen Access
    Automatische Applikation modellbasierter Diesel-Luftsystem-Funktionen in Motorsteuergeräten
    (2020) Xie, Yijiang; Kistner, Arnold (Prof. Dr.-Ing.)
    The continuous development of diesel engines for meeting the legal and functional requirements, e.g. reducing emissions and fuel consumption while taking drivability into account, has led to a significant increase in the number of sensors and actuators required for the engine. For the diesel-air system it means to introduce a turbocharger, a system for exhaust gas recirculation (EGR), an exhaust gas aftertreatment system, a variable valve control, etc. In order to control such an increasingly complex system in diesel engines, ECU-functions are developed by means of a model-based approach. The success of a model-based development methodology is based on a precise and e cient modeling of the relevant engine behavior. Because of the limited computing power of an ECU, a combination of physical models and so-called calibration parameters is usually preferred for engine modeling. The calibration parameters can be scalar or one or two-dimensional empirical models and usual ly have to be determined (calibrated) by experiments on an engine test bench. Typical examples for such calibration parameters are lookup-tables for modeling the cylinder charge (volumetric e ciency) and the e ective area of the EGR valve. In this thesis a procedure is proposed which is able to calibrate the ECU functions for stationary relationships, e.g. in the diesel-air system, automatically and with as little measurement e ort as possible in terms of the number of measurement points. The algorithm runs within the framework of sequential experimental planning, in which Gaussian models with non-stationary covariance functions are used to approximate the relations of interest. For adaptive experimental planning an active sampling strategy is developed based on the concept of mutual information and optimal system inputs (engine speed, fuel quantity, air actuators, etc.) and which determines the resulting operating points, with respect to the input space coverage, the inhomogeneous properties of the relations, the uncertainty of the estimated calibration parameters and the feasibility of the operating points. The method is able to predict the stationary engine behavior, which results from the selected system inputs, by means of the physical structure of the air system and the data-based models of the calibration parameters. On this basis the uncertainties of the application parameters are estimated using extended Kalman filters. The feasibility of the operating point is checked by comparing the predicted system behavior with the engine limits. For validation the developed algorithm was implemented on an engine test bench to calibrate the air system of a diesel engine equipped with high and low pressure EGR, a variable geometry turbocharger and variable valve timing. As a result, using the presented approach, using as little as approx. 130 measurement points is enough to obtain a comparable application quality to that achieved by conventional methods with more than 800 measurement points.
  • Thumbnail Image
    ItemOpen Access
    Rigorous compilation for near-term quantum computers
    (2024) Brandhofer, Sebastian; Polian, Ilia (Prof.)
    Quantum computing promises an exponential speedup for computational problems in material sciences, cryptography and drug design that are infeasible to resolve by traditional classical systems. As quantum computing technology matures, larger and more complex quantum states can be prepared on a quantum computer, enabling the resolution of larger problem instances, e.g. breaking larger cryptographic keys or modelling larger molecules accurately for the exploration of novel drugs. Near-term quantum computers, however, are characterized by large error rates, a relatively low number of qubits and a low connectivity between qubits. These characteristics impose strict requirements on the structure of quantum computations that must be incorporated by compilation methods targeting near-term quantum computers in order to ensure compatibility and yield highly accurate results. Rigorous compilation methods have been explored for addressing these requirements as they exactly explore the solution space and thus yield a quantum computation that is optimal with respect to the incorporated requirements. However, previous rigorous compilation methods demonstrate limited applicability and typically focus on one aspect of the imposed requirements, i.e. reducing the duration or the number of swap gates in a quantum computation. In this work, opportunities for improving near-term quantum computations through compilation are explored first. These compilation opportunities are included in rigorous compilation methods to investigate each aspect of the imposed requirements, i.e. the number of qubits, connectivity of qubits, duration and incurred errors. The developed rigorous compilation methods are then evaluated with respect to their ability to enable quantum computations that are otherwise not accessible with near-term quantum technology. Experimental results demonstrate the ability of the developed rigorous compilation methods to extend the computational reach of near-term quantum computers by generating quantum computations with a reduced requirement on the number and connectivity of qubits as well as reducing the duration and incurred errors of performed quantum computations. Furthermore, the developed rigorous compilation methods extend their applicability to quantum circuit partitioning, qubit reuse and the translation between quantum computations generated for distinct quantum technologies. Specifically, a developed rigorous compilation method exploiting the structure of a quantum computation to reuse qubits at runtime yielded a reduction in the required number of qubits of up to 5x and result error by up to 33%. The developed quantum circuit partitioning method optimally distributes a quantum computation to distinct separate partitions, reducing the required number of qubits by 40% and the cost of partitioning by 41% on average. Furthermore, a rigorous compilation method was developed for quantum computers based on neutral atoms that combines swap gate insertions and topology changes to reduce the impact of limited qubit connectivity on the quantum computation duration by up to 58% and on the result fidelity by up to 29%. Finally, the developed quantum circuit adaptation method enables to translate between distinct quantum technologies while considering heterogeneous computational primitives with distinct characteristics to reduce the idle time of qubits by up to 87% and the result fidelity by up to 40%.
  • Thumbnail Image
    ItemOpen Access
    Die Kornstruktur und der Heißrisswiderstand von Laserstrahlschweißnähten in Aluminiumlegierungen
    (München : utzverlag, 2020) Hagenlocher, Christian; Graf, Thomas (Prof. Dr. phil. nat.)
    Die Kornstruktur einer Schweißnaht beeinflusst ihren Widerstand gegen die Bildung von Nahtmittenheißrissen. Im Rahmen dieser Arbeit wurde der übergreifende Zusammenhang zwischen Schweißparameter, Kornstruktur und Heißrisswiderstand beim Laserstrahlschweißen durch analytische Gleichungen beschrieben und das resultierende Modell experimentell validiert.
  • Thumbnail Image
    ItemOpen Access
    Schaustücke : Einblicke in wissenschaftliche Sammlungen der Universität Stuttgart
    (Stuttgart : Universität Stuttgart, 2022) Wiatrowski, Frank (Gestaltung, Fotograf); Engstler, Katja Stefanie (Gestaltung); Ceranski, Beate (Vorwort); Rambach, Christiane (Vorwort)
    Die wissenschaftlichen Sammlungen der Universität zeugen von einer langen Lehr- und Forschungstradition. In Fakultäten und Instituten, in der Universitätsbibliothek und im Universitätsarchiv sind vielfältige Sammlungen beheimatet, zum Teil mit ungewöhnlichen oder gar einzigartigen Objekten. Die Broschüre gibt erste Einblicke in diese vielfach versteckte Welt der universitären Sammlungen in Stuttgart.
  • Thumbnail Image
    ItemOpen Access