20005 research outputs found
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Zukunftsmodell (private) Fernhochschulen? Eine Text-Mining-Analyse studentischer Zufriedenheit aus der Perspektive der Selbstbestimmungstheorie
No full textPrivate Hochschulen sind in den letzten Jahren stark gewachsen. Großen Anteil daran hat das Fernstudium, das als Studienmodell der Zukunft gilt. Dennoch sind private Hochschulen in der Hochschulforschung bislang kaum beforscht. Diese Forschungslücke adressiert der Beitrag, indem er Faktoren für studentische Zufriedenheit an privaten Fernhochschulen mittels eines Text-Minings von über 10.000 studentischen Bewertungstexten identifiziert. Die Auswertung mittels Kookkurrenz-Netzwerkanalyse aus Perspektive der Selbstbestimmungstheorie (SDT) deutet darauf hin, dass die untersuchten Hochschulen ihren Studierenden erfolgreich ermöglichen, ihr Bedürfnis nach Autonomie, Kompetenz und sozialer Eingebundenheit im Sinne der SDT zu befriedigen. Dazu tragen eine flexible, selbstbestimmte Studiengestaltung, bedarfsorientierte Supportstrukturen und eine instruktive Online-Lernumgebung bei. Die Studie liefert Impulse für das Verständnis des Aufstiegs privater Fernhochschulen aus studentischer Perspektive
Model predictive pose optimization for energy efficient robotic machining
No full textOne focus of aviation research in recent years has been the reduction of greenhouse gases through weight savings in aircraft construction, e.g. by using lightweight materials such as CFRP components. Lighter aircraft lead to less fuel consumption, which impacts the global carbon footprint and is an important step towards CO₂-neutral flying. In order to achieve national climate goals, the environmental impact should already be assessed at the production stage. Most recently, hybrid kinematics consisting of serial kinematics (industrial robots on linear rails) and parallel kinematics (hexapod) mounted to the robot’s end effector, have been studied at Fraunhofer IFAM for the purpose of machining distorted CFRP-components. This work analyzes to which extent the redundant degrees of freedom of such hybrid kinematics can be exploited to determine energetically advantageous poses during machining. Therefore, the inverse kinematics are solved within an Optimal Control Problem (OCP) including the forward kinematics as well as minimizing the system’s energy consumption while following a reference trajectory
Effective permittivity determination procedure for 3D-printed dielectric lenses
No full textThis work extends the usual design process of dielectric lenses by introducing a novel procedure for determining the effective permittivity of 3D-printed dielectric lenses. A determination lens with a significant side lobe characteristic is designed to determine the effective permittivity while accounting for the specific influences of the 3D-printing process. By using the obtained permittivity value, the lens design can be optimized to achieve a desired performance. A gain accuracy of 0.15 dBi and an SLL accuracy of less than 2.2 dBi is achieved. This procedure integrates seamlessly into the dielectric lens development process, enhancing its accuracy and reliability
Cross-sectoral reliability-constrained sizing of thermal storage in multi-energy systems
No full textThe increasing electrification in district heating systems through electric heat pumps and the resulting coupling between electrical and heating systems presents challenges to network operators and planners, but it also offers high flexibility potential in distribution network operation. The flexibility offered by electric heat pumps and thermal storages can play a vital role in providing affordable energy storage and the potential for load shifting. However, this flexibility comes with uncertainty as it depends on changing weather conditions and customer behavior. Therefore, the correct sizing of the thermal storage capacities in the planning phase of multi-energy systems (MES) is essential for guaranteeing sufficient flexibility for electrical network operation. Moreover, existing reliability metrics do not capture the interactions between the electrical and thermal domains of MESs. In this paper, a novel methodology is presented for optimal sizing under the uncertainty of thermal storage capacities in a heating network coupled to an electrical network. Distributionally robust chance-constrained optimization (DRCC) is used to model the system to limit the probability of insecure operation due to uncertainty in heat demand forecasting. The proposed approach is demonstrated on a modified MES and the results are compared to those obtained from a conventional deterministic optimization model. A new reliability metric, Expected Heat Not Supplied (EHNS), is introduced to evaluate system reliability. The proposed methodology is designed to provide network planners and operators with the optimal storage capacities needed to balance robustness against existing uncertainties, costs, and system reliability
Blockchain-based secure archiving of sensor malfunctions in structural health monitoring systems
No full textStructural health monitoring (SHM) systems are widely used to assess the condition of civil infrastructure. Sensor malfunctions in SHM systems may result in erroneous assessments, illuminating the need for secure archiving of malfunctions. However, methods with online functionality for secure archiving of sensor malfunctions in SHM systems have not been reported yet. This paper presents a system for secure archiving of sensor malfunctions based on blockchain technology, designed as a modular add-on for SHM systems. Using a public blockchain framework, the blockchain-based archiving system is implemented and validated for two use cases, demonstrating the potential of blockchain for SHM systems
Highly Shielded Peroxo‐Cerium(IV)‐Containing polyoxometalate: synthesis, structure, and oxidative studies
No full textThe peroxo-bridged di-cerium(IV)-di-lithium-containing polyoxometalate [(CeIV 2O2)Li2(P2W16O59)2]16 (Ce2Li2P4W32) is synthesized in a one-pot aqueous synthetic procedure and isolated as a hydrated mixed alkali salt, K13.6Na1.4Li[(CeIV 2O2)Li2(P2W16O59)2]·32H2O (KNaLi-Ce2Li2P4W32). The novel polyanion Ce2Li2P4W32 comprises a side-on peroxo-group bridging two cerium(IV) and two lithium ions, which are encapsulated between two dilacunary, face-on {P2W16} Wells–Dawson units, with a vacant site in each of the two belts. The polyanion Ce2Li2P4W32 is characterized in the solid state by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy and in solution by 31P NMR and Raman spectroscopy, respectively. Ce2Li2P4W32 and the peroxogroup are shown to be highly stable in a large pH range and up to almost boiling temperatures, but at the same time the polyanion is reactive toward oxidation of triphenylphosphine, involving the peroxo group and the cerium(IV) centers
Enhancing end-of-life sustainability through modularity and interface design in product development
No full textThis study highlights the importance of interface design in sustainable product development within a circular economy. By focusing on the end-of-life (EOL) phase, the research emphasizes modular product architectures’ role in improving component separability, reusability, and recyclability. An extended Module Interface Graph (MIG) was developed to assess interface variance, detachability, and material pairings, enabling the identification of critical interfaces that significantly influence EOL outcomes. The approach was successfully applied to a portal milling machine, demonstrating its ability to highlight key areas for design improvements, such as transitioning from non-detachable to standardized, detachable interfaces. This method showcases the potential for early interface considerations to enhance both environmental sustainability and product lifecycle management
Towards an indicator for assessing the potential for geometric standardization in the development of variant lightweight products
No full textProduct development is a dynamic, multidisciplinary field shaped by evolving customer demands and the need for individualized products, increasing product variety. Key factors include economic performance, customer satisfaction, and sustainability. Lightweight design drives innovation by enhancing weight-specific performance, optimizing resources, and reducing CO2 emissions, especially in transportation. However, conflicts arise as lightweight design focuses on individual variants, neglecting broader product family implications, while Design for Variety strategies often exclude lightweight design. This study examines the interplay between product variety and lightweight design, proposing a measurement framework to support the development of variant products and their components within product families in the context of lightweight design
Assessing knowledge gaps about shipping emissions: designing educational programs for sustainable maritime logistics for future professionals in Albania & Montenegro
No full textThis study assesses knowledge gaps among Albanian and Montenegrin maritime professionals regarding EU shipping emissions and their implication on current and future curricula. Survey data revealed educational needs across economic, legislative, and engineering domains. Utilizing IMO model course frameworks and competence-based assessment methodologies, we propose structured educational interventions to facilitate knowledge transfer from established EU member states to the West Balkan countries. The findings contribute to environmental management policy by addressing regional capacity development needs for maritime emissions compliance, technological innovation and best practices