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Holographic freeform micro hole processing using Bessel beams
No full textBessel beams are advantageous tools for micro drilling applications due to their diffraction-free properties, their long focal length, and their small focal spot diameter. However, their application in industry is limited because they are challenging to integrate into flexible beam shaping systems. This work is intended to overcome limitations in flexibility by presenting a new approach paving the way to high-aspect ratio freeform holes. Therefore,
a spatial light modulator was integrated into an axicon-based setup to merge diffraction-free ablation with the flexibility of holographic spatial beam shaping. A dynamic change of the phase hologram displayed on the spatial light modulator during the process allows for the generation of arbitrary ablation geometries. In contrast to other holographic approaches, the diffraction-free nature of the Bessel beam allows ablation over an extended focal
depth without any focus control needed. The applicability of the approach was demonstrated by processing arbitrary hole shapes, such as ellipses, squares, or star-shapes. The hole sizes of the freeform holes range from 4 μm to 80 μm. Furthermore, up-scaling of the process is demonstrated by using the setup for generation of multi-Bessel spots
Risikoorientierte Management Control Systems im Beschaffungsmanagement von kleinen und mittelständischen Unternehmen
No full textMegatrend Klimawandel, Krisen und regulatorische Vorgaben wie das Lieferkettensorgfaltspflichtengesetz (LkSG) haben in den letzten Jahren enorme Herausforderungen für Unternehmen generiert. Unternehmen sehen sich einem steigenden Steuerungsbedarf im Bereich Risikomanagement und Beschaffung gegenüber. Ein geeignetes Instrument im strategischen und operativen Controlling ist hierfür ein risikoorientiertes
Management Control System. Darüber hinaus macht das LkSG Vorgaben für die Ausgestaltung eines Risikomanagements. Insbesondere die Ausgestaltung der Lieferketten
und des Risikomanagements mussten neu gedacht und strategisch eingebunden werden.
Daneben zeigen sich auch zunehmend Nachhaltigkeitsimplikationen auf das Working
Capital Management in Unternehmen. Insbesondere das LkSG wirkt zunehmend auf unternehmerische Entscheidungen und führt zu Trade-offs zwischen Compliance,
Nachhaltigkeit und Profitabilität. Hier können Sustainability Control Systems eine wichtige Rolle spielen, die im Vergleich mit klassischen Management Control Systems Nachhaltigkeitsaspekte inkludiere
Astronomy events at Aschaffenburg University to attract future students
No full textIn 2023, the German Federal Ministry of Education and Research and the German organisation for science communication “Wissenschaft im Dialog” jointly proclaimed a “Science Year 2023” in Germany with the motto “Our Universe”. One of the numerous events that have been supported has been that of the project “Zirkus UNI-versum”, which took place in summer 2023 at Aschaffenburg University of Applied Sciences. This project, and other activities for schools, intend to stimulate the interest of pupils in STEM subjects and to attract future engineering students
Various highly effective sputtered layer structures as catalysts for H2O2 decomposition for use in satellite engines
No full textCatalysts are frequently employed in both research and industrial applications to facilitate or accelerate chemical reactions. One such application is in monopropellant thrusters for space propulsion systems, where hydrogen peroxide (H2O2) is used as a liquid propellant. The decomposition of liquid hydrogen peroxide into water and oxygen gas, which ultimately generates thrust, can be achieved using noble metal catalysts from the platinoid group, such as platinum and iridium. This promotes the use of more environmentally friendly and less toxic propellants, such as H2O2, instead of hydrazine and nitrogen tetroxide (NTO). The optimization of coating structures with these catalytic materials is essential for future space applications, as it aims to extend the lifespan of catalyst materials and results in a better utilization of H2O2 in satellite engines.
Therefore, different layer structures were deposited onto Duranit D99 pellets using a controlled magnetron sputtering process. Previous studies have shown that the used sputtering pressure has a strong influence on the structure of the deposited coatings [2][3]. Certain parameter combinations produce catalytic layers with rough textures and a highly porous microstructure, see figure 1 [1].
To improve the thermal and mechanical stability of the sputtered layers, thin adhesive layers of Titanium and Zirconium were applied beneath the catalytic layer.
The pellets were then heated in an oven at 640°C for one minute to simulate the thermal effects experienced in a satellite engine during ignition. Following this, the catalytic performance of the pellets was tested in laboratory experiments using 30% H2O2. Pellets with sputtered platinum as the catalytic coating delivered the best results. These coatings will be further evaluated in an engine test conducted at the German Aerospace Centre (DLR).
Hydrogen peroxide is also expected to play a crucial role in future lunar and Martian colonization efforts. In this context, catalytic coatings would be used to decompose H2O2 to supply astronauts with water and oxygen, rather than to generate thrust in satellite engines
Automated Tracking of User Interactions in Web-Based Adaptive Learning for Software Engineering
No full textThis paper explores the automation of generating and dispatching Experience API (xAPI) statements for comprehensive tracking of user interactions in e-learning environments. It introduces the react-xapi-wrapper library, an extension of the xAPI JavaScript library designed for use in web applications. Key aspects discussed include the library’s features, its integration into a web-based adaptive learning system (ALS) for software engineering, and the custom verbs used. The goal is to reduce implementation effort for tutors and developers while taking advantage of xAPI’s interoperability, scalability, and ability to track student learning activities and behaviors, laying the foundation for more responsive and personalized learning experiences
Towards Practicable Machine Learning Development Using AI Engineering Blueprints
No full textThe implementation of artificial intelligence (AI) in business applications holds considerable promise for significant improvements. The development of AI systems is becoming increasingly complex, thereby underscoring the growing importance of AI engineering and MLOps techniques. Small and medium-sized enterprises (SMEs) face considerable challenges when implementing AI in their products or processes. These enterprises often lack the necessary resources and expertise to develop, deploy, and operate AI systems that are tailored to address their specific problems.
Given the lack of studies on the application of AI engineering practices, particularly in the context of SMEs, this paper proposes a research plan designed to develop blueprints for the creation of proprietary machine learning (ML) models using AI engineering and MLOps practices. These blueprints enable SMEs to develop, deploy, and operate AI systems by providing reference architectures and suitable automation approaches for different types of ML.
The efficacy of the blueprints is assessed through their application to a series of field projects. This process gives rise to further requirements and additional development loops for the purpose of generalization. The benefits of using the blueprints for organizations are demonstrated by observing the process of developing ML models and by conducting interviews with the developers
Fractographic Analysis and Fatigue Behavior of Additively Manufactured Ni‐Superalloy Components with Post Processing Heat Treatment and Hot Isostatic Pressing
No full textA report is made on a study of mechanical properties and fractographic characteristics of laser powder bed fusion (PBF‐LB/M)‐built Inconel 718, performing heat treatments and hot‐isostatic pressing. For this, tensile components are heat‐treated by different processes, as namely stress relief (SR), SR and double aging (SR + DA), and hot‐isostatic pressing are conducted. For the mechanical testing, the ultimate tensile strength (UTS) as well as the fatigue behavior are evaluated, examining differences in maximum load behavior, elongation, and the different regimes of fatigue. As changes in material structure can be observed, the sole SR leads to a diminished UTS, while the combination of SR + DA develops an UTS of Rm = 1277 MPa. Within the fatigue behavior, the HIP shows a very balanced material structure with an increased high cycle and very high cycle regime, as the texture gets homogenized during the heat treatment. The metallographic analysis can quantify the material changes, as the density and the hardness are improved by virtue of the heat treatments. Furthermore, the fractographic analysis shows the differences in fracture behavior, arising due to the microstructural changes, as crack initiation points, crack propagation, and forced fractures can be categorized by scanning electron microscopy
On the Impact of Process Parameters and Ambient Temperature on Tensile Strength and Fatigue Behaviour of SLS-Built Polyamide-12
No full textWe report on a comprehensive study of tensile strength and fatigue behaviour depending on process parameters and ambient temperature. For this, Polyamide-12 components are fabricated using Selective Laser Sintering. Firstly, different process parameters like, e.g, scan-speed, laser power, and applied energy density are varied. Secondly, the ambient temperature during testing is varied, evaluating the impact of decreased, respectively increased test temperatures on the characteristics of the Polyamide-12 components. For all components, the static and dynamic mechanical load behaviour is investigated, quantifying the changes in the Ultimate Tensile Strength (UTS) and the endurance limit. As the applied energy density transpires as a decisive parameter, a variation leads to significant changes in UTS and endurance limit, whereas an adjustment of scan-speed and laser power at a constant energy density do not affect the mechanical properties. Finally, the ambient temperature during testing is evaluated, demonstrating different ambient application conditions. The impact of an active cooling of the component as well as increased temperatures on the mechanical behaviour is tested, providing fundamental findings on the operating life of Polyamide-12 components
‚A desirable place to work‘. Hochschulen für Angewandte Wissenschaften (HAWs) im neuen Wettbewerb um Arbeitgeberattraktivität und die Rolle der Arbeitskultur
No full textThe productivity of universities of applied sciences (UASs) depends highly
upon qualified and particularly motivated professorial staff. In times of a
shortage of skilled workers, the public sector with its earning potential or the
prospect of job security is hardly a convincing alternative to industry and
business. Rather 'softer' components such as work culture, motivation, worklife
balance, compatibility of family and career as well as flexibility of work location
and working hours (new work) are becoming more important for attracting
future professors. In context of the federal-state program “FH-Personal”,
we present approaches of the TH Aschaffenburg to employer branding,
which bring the local organizational and working culture into the picture