Publikationsserver der Ostbayerischen Technischen Hochschule Regensburg
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Operational wear behaviour of 3D-printed lightweight metal gears: EDS and oil analysis comparison
No full textAdditive manufacturing (AM) has come to the fore in recent years among manufacturing techniques. This technique, which has different advantages than traditional ones such as casting, forging and machining, is expected to be widely used in producing machine parts like gears in the coming years. Therefore, experimental data on AM parameters for lightweight metal gears are important for industrial production. In this study, a wear test was applied to AlSi10Mg and Ti6Al4V gears under operational conditions, and the wear behaviour of conventionally and additively manufactured gears was compared. The amount of abrasion elements was determined by analysing the oil in the gearbox. In addition, gear surfaces were analysed using scanning electron microscopy and an energy-dispersive spectrometer before and after wear. Thus, the wear behaviour of gears produced by conventional and AM under service conditions was demonstrated comparatively
Out of the Loop: Structural Approximation of Optimisation Landscapes and non-Iterative Quantum Optimisation
No full textThe Quantum Approximate Optimisation Algorithm (qaoa) is a widely studied quantum-classical iterative heuristic for combinatorial optimisation. While qaoa targets problems in complexity class NP, the classical optimisation procedure required in every iteration is itself known to be NP-hard. Still, advantage over classical approaches is suspected for certain scenarios, but nature and origin of its computational power are not yet satisfactorily understood. By introducing means of efficiently and accurately approximating the qaoa optimisation landscape from solution space structures, we derive a new algorithmic variant: Instead of performing an iterative quantum-classical computation for each input instance, our non-iterative method is based on a quantum circuit that is instance-independent, but problem-specific. It matches or outperforms unit-depth qaoa for key combinatorial problems, despite reduced computational effort. Our approach is based on proving a long-standing conjecture regarding instance-independent structures in qaoa. By ensuring generality, we link existing empirical observations on qaoa parameter clustering to established approaches in theoretical computer science, and provide a sound foundation for understanding the link between structural properties of solution spaces and quantum optimisation
Reducing Transient Behavior in Simulation-Based Digital Twins: A Novel Initialization Approach for Order Picking Systems
No full textIn the context of facilitating operational decision-making through simulation-based digital twins, precise and expeditious synchronization of simulation models with real-system load states is paramount. Such synchronization serves to attenuate the typical transient behavior observed in material flow simulation, confining it to a brief temporal window. This paper delineates a novel conceptual framework for initializing simulation models, illustrated through an exemplar of an order picking system integrated with SAP Extended Warehouse Management as its warehouse and operation management system. Through empirical inquiry, the ramifications of the proposed initialization framework on simulation model transient behavior are scrutinized. Notably, the reference simulation model commences in a state of ‘empty’ load. The findings of this study evince that the proposed approach yields a significant improvement in transient behavior
Characterization of Tunable Rebound Properties of Microstructured Magnetoactive Elastomers
No full textWe present a novel method to control the rebounding behavior of small mm-sized solid balls by employing magnetoactive elastomers (MAEs) with microstructured surfaces. An MAE is a composite material consisting of μm-sized ferromagnetic particles dispersed in a soft elastomer (e.g., polydimethylsiloxane) matrix. In the act of rebounding, the ball hits an MAE surface and bounces back. The MAE samples contained 75 wt.% of iron. This composite material is known to respond to an applied magnetic field with increased stiffness (due to the magnetorheological effect) and plasticity. To adjust the rebound properties, the top layer of the MAE material was additionally modified by micromachining lamellar structures with different dimensions on the 100 μm scale via laser ablation. Due to the resulting high aspect ratio, these surface structures were sensitive to the magnetic field direction. The lamellas could stand up straight or lay down flat. The rebound behavior was evaluated by using a custom build apparatus that facilitates dropping of the balls in a precise and repeatable manner. A ball was dropped from different heights. The ball trajectory was captured with a high-speed camera to investigate the rebound properties. The recorded video was processed using a custom software written in Python. The experimental procedure and data processing algorithms are presented in detail. The results for the samples with different geometrical dimensions are provided as examples. It is made evident that the magnetic field influences the rebound properties of small non-magnetic balls impinging microstructured MAE surfaces. The change in surface topography is an effective way to control the ball rebound. The fabrication flexibility in geometrical dimensions of surface microstructures opens a convenient way to tune the desired response to magnetic fields. The presented idea may find applications in impact mitigation or small-scale sorting machinery, e.g. for recycling
Modelling of measuring systems – From white box models to cognitive approaches
No full textMathematical models of measuring systems and processes play an essential role in metrology and practical measurements. They form the basis for understanding and evaluating measurements, their results and their trustworthiness.
Classic analytical parametric modelling is based on largely complete knowledge of measurement technology and the measurement process.
But due to digital transformation towards the Internet of Things (IIoT) with an increasing number of intensively and flexibly networked measurement systems and consequently ever larger amounts of data to be processed, data-based modelling approaches have gained enormous importance.
This has led to new approaches in measurement technology and industry like Digital Twins, Self-X Approaches, Soft Sensor Technology and Data and Information Fusion.
In the future, data-based modelling will be increasingly dominated by intelligent, cognitive systems. Evaluating of the accuracy, trustworthiness and the functional uncertainty of the corresponding models is required.
This paper provides a concise overview of modelling in metrology from classical white box models to intelligent, cognitive data-driven solutions identifying advantages and limitations. Additionally, the approaches to merge trustworthiness and metrological uncertainty will be discussed
Data of a systematic literature research on eye tracking in software engineering [Data set]
No full textHow did the data collection work?
By systematic research in the IEEE Xplore and ACM digital libraries we extracted 125 papers. Further details on the procedure can be found in the journal paper.
What data is provided?
In this repository you can find the extracted data, i.e., file data.xlsx
Multi-Site Aggregate Production Planning With Resilience Consideration
No full textThe recent years have shown a high frequency of disruptions like natural disasters or manmade disruptions, leading, for example, to transport routes or production facilities being unavailable for extended periods. Many manufacturing companies, which nowadays operate in a global production network, are heavily exposed to these disruptions. This results in both significant costs and substantial exceeding of promised deadlines. If it concerns the first company in a supply chain, it causes correspondingly significant delays in promised deadlines for subsequent companies in the supply chain, including a correspondingly significant increase in costs. Both are exemplified in this paper through a case study. This case study demonstrates that through resilience, both implications can be significantly reduced
Teaching Digital Electronics Principles by Connecting Diverse Technologies
No full textA lab course for digital electronics is developed and implemented in the second semester of a bachelor of engineering study program. This lab course runs parallel to a lecture about the basics of digital electronics. The goal of this lab course is that students should acquire the competence to develop digital circuits, no matter which design technique or circuit technology they use. Therefore, students have to learn abstract thinking without sticking to a certain digital design technique or circuit technology. For this reason, digital circuits with identical functions are developed by students, using different digital design techniques. A SPICE simulation software, the Analog Discovery board, VHDL simulation and implementation using an FPGA board are used for the five experiments with increasing complexity that are carried out during this lab course. The last task is a small project where students can carry out own ideas. The lecturer sees that students are very engaged during this lab course and also their feedback is very positive. They answered that the time frame and complexity of the course was appropriate, the usage of the Analog Discovery board was very instructive, and they learned much. In sum, the students are very satisfied with the course. This success is encouraging to retain the overall structure of this lab course and develop the details further
Kvc-Ongoing: Keystroke Verification Challenge
No full textThis article presents the Keystroke Verification Challenge - onGoing (KVC-onGoing), on which researchers can easily benchmark their systems in a common platform using large-scale public databases, the Aalto University Keystroke databases, and a standard experimental protocol. The keystroke data consist of tweet-long sequences of variable transcript text from over 185,000 subjects, acquired through desktop and mobile keyboards simulating real-life conditions. The results on the evaluation set of KVC-onGoing have proved the high discriminative power of keystroke dynamics, reaching values as low as 3.33% of Equal Error Rate (EER) and 11.96% of False Non-Match Rate (FNMR) @1% False Match Rate (FMR) in the desktop scenario, and 3.61% of EER and 17.44% of FNMR @1% at FMR in the mobile scenario, significantly improving previous state-of-the-art results. Concerning demographic fairness, the analyzed scores reflect the subjects’ age and gender to various extents, not negligible in a few cases. The framework runs on CodaLab
HEKATE - Implementierung eines Dashboards zur Visualisierung von Auswertungen des HASKI Konzepts für einen umfassenden Einblick in den Lernprozess
No full textIn der gegenwärtigen Bildungslandschaft erfährt die adaptive Hochschullehre eine zunehmende Relevanz, da traditionelle Lehrmethoden vielfach nicht mehr hinreichend sind, um den individuellen Bedürfnissen der Studierenden zu entsprechen. Das Projekt HEKATE zielt darauf ab, die Erkenntnisse aus dem HASKI-System, einem innovativen Ansatz für personalisierte Lernunterstützung basierend auf KI und maschinellem Lernen, effektiv zu visualisieren. HEKATE ergänzt das HASKI-System durch die Entwicklung eines Dashboards, welches eine transparente und nachvollziehbare Darstellung der Lernstildaten ermöglicht.
Das Ziel des Projekts besteht in der Umsetzung einer Visualisierungslösung, die sich durch eine hohe Benutzerfreundlichkeit sowie Leistungsfähigkeit auszeichnet und alle relevanten Lern- und Nutzungsdaten Studierender adäquat abbildet. Die funktionalen Anforderungen umfassten die präzise Darstellung von Lernstil-Ergebnissen, Quiz- und Übungsergebnissen sowie die Integration des ARIADNE-Konzepts. Des Weiteren werden nichtfunktionale Ziele definiert, welche eine hohe Benutzerfreundlichkeit, Systemsicherheit, kurze Ladezeiten sowie eine verlässliche Datenverarbeitung umfassten. Hekate bietet sowohl für Studierende als auch für Lehrende einen erheblichen Mehrwert, indem es Lern- und Nutzungsmuster auf einfache und intuitive Weise visualisiert. Die Integration in die HASKI-Umgebung und Moodle gewährleistet eine nahtlose Einbindung der Anwendung in bestehende Lernumgebungen, wodurch sich der Nutzen weiter steigert. In künftigen Entwicklungsstufen könnten zusätzliche Visualisierungsoptionen und Funktionen integriert werden, um das System weiter zu optimieren und an die Bedürfnisse der Nutzer anzupassen.In the current educational landscape, adaptive university teaching is becoming increasingly relevant, as traditional teaching methods are often no longer sufficient to meet the individual needs of students. The HEKATE project aims to effectively visualise the findings from the HASKI system, an innovative approach to personalised learning support based on AI and machine learning. HEKATE complements the HASKI system by developing a dashboard that enables a transparent and comprehensible visualisation of learning style data.
The aim of the project is to implement a visualisation solution that is characterised by a high level of user-friendliness and performance and adequately depicts all relevant learning and usage data of students. The functional requirements included the precise visualisation of learning style results, quiz and exercise results as well as the integration of the ARIADNE concept. Non-functional goals were also defined, which included a high level of user-friendliness, system security, short loading times and reliable data processing. Hekate offers significant added value for both students and teachers by visualising learning and usage patterns in a simple and intuitive way. The integration into the HASKI environment and Moodle ensures a seamless integration of the application into existing learning environments, which further increases the benefits. In future development stages, additional visualisation options and functions could be integrated in order to further optimise the system and adapt it to the needs of users