Refine
Year of publication
Document Type
- Bachelor Thesis (244)
- Master's Thesis (35)
- Report (19)
- Article (11)
- Other (4)
- Doctoral Thesis (1)
- Periodicalpart (1)
Language
- German (265)
- English (47)
- Multiple languages (3)
Is part of the Bibliography
- no (315) (remove)
Keywords
- Augenoptik (17)
- Abschlussarbeit (7)
- Augenoptiker (7)
- Studie (7)
- Kontaktlinse (6)
- Hörgerät (5)
- Leitfaden (5)
- Bachelorarbeit A/H (4)
- Marketing (4)
- Optometrie (4)
Institute
- Optik und Mechatronik (132)
- Augenoptik und Hörakustik (68)
- Wirtschaftswissenschaften (46)
- Internationale Betriebswirtschaft (29)
- Maschinenbau und Werkstofftechnik (14)
- Master of Science in Vision Science and Business (6)
- Elektronik und Informatik (3)
- Chemie (1)
- Informatik (1)
- Technischer Redakteur (1)
Soft magnetic Fe-Al alloys have been a subject of research in the past. However, they never saw the same reception in technical applications as the Fe-Si or Fe-Ni alloys, which is, to some extent, due to a low ductility level and difficulties in manufacturing. Additive manufacturing (AM) technology could be a way to avoid issues in conventional manufacturing and produce soft magnetic components from these alloys, as has already been shown with similarly brittle Fe-Si alloys. While AM has already been applied to certain Fe-Al alloys, no magnetic properties of AM Fe-Al alloys have been reported in the literature so far. Therefore, in this work, a Fe-12Al alloy was additively manufactured through laser powder bed fusion (L-PBF) and characterized regarding its microstructure and magnetic properties. A comparison was made with the materials produced by casting and rolling, prepared from melts with an identical chemical composition. In order to improve the magnetic properties, a heat treatment at a higher temperature (1300 °C) than typically applied for conventionally manufactured materials (850–1150 °C) is proposed for the AM material. The specially heat-treated AM material reached values (HC: 11.3 A/m; µmax: 13.1 × 103) that were close to the heat-treated cast material (HC: 12.4 A/m; µmax: 20.3 × 103). While the DC magnetic values of hot- and cold-rolled materials (HC: 3.2 to 4.1 A/m; µmax: 36.6 to 40.4 × 103) were not met, the AM material actually showed fewer losses than the rolled material under AC conditions. One explanation for this effect can be domain refinement effects. This study shows that it is possible to additively manufacture Fe-Al alloys with good soft magnetic behavior. With optimized manufacturing and post-processing, further improvements of the magnetic properties of AM L-PBF Fe-12Al may still be possible.
Based on a data-driven approach, a computer-assisted workflow for the quantitative analysis of optical Kerr microscopy images of sintered FeNdB-type permanent magnets was developed. By analyzing the domain patterns visible in the Kerr image with data-driven approaches such as traditional machine learning and advanced deep learning, we can quantify grain orientation and size with a better trade-off between accuracy and higher throughput than electron backscatter diffraction (EBSD). The key distinction between traditional machine learning and advanced deep learning lies in feature extraction. Traditional methods require manual, user-dependent feature extraction from input data, while advanced deep learning achieves this automatically. The predictions from the trained models were compared to the measurements from EBSD for performance evaluation. The proposed data-driven model is trained on the dataset created from the correlative microscopy technique, which requires the images of grains extracted from the Kerr microscopy and corresponding EBSD grain orientation data (Euler angles). The fine-tuned deep learning model shows better generalization ability than the traditional machine learning models trained on the manually extracted features and resulted in a mean absolute error of less than 5° for grain orientation of the anisotropic magnet samples when evaluated against the measured EBSD values. The developed approach has reduced the measurement effort for grain orientation by 5 times and have sufficient accuracy when compared to the EBSD.
In this study, we investigate the use of artificial neural networks as a potentially efficient method to determine the rate capability of electrodes for lithium-ion batteries with different porosities. The performance of a lithium-ion battery is, to a large extent, determined by the microstructure (i.e., layer thickness and porosity) of its electrodes. Tailoring the microstructure to a specific application is a crucial process in battery development. However, unravelling the complex correlations between microstructure and rate performance using either experiments or simulations is time-consuming and costly. Our approach provides a swift method for predicting the rate capability of battery electrodes by using machine learning on microstructural images of electrode cross-sections. We train multiple models in order to predict the specific capacity based on the batteries’ microstructure and investigate the decisive parts of the microstructure through the use of explainable artificial intelligence (XAI) methods. Our study shows that even comparably small neural network architectures are capable of providing state-of-the-art prediction results. In addition to this, our XAI studies demonstrate that the models are using understandable human features while ignoring present artefacts.
In the fast-growing but also highly competitive market of battery-powered power tools, cell-pack-cooling systems are of high importance, as they guarantee safety and short charging times. A simulation model of an 18 V power tool battery pack was developed to be able to evaluate four different pack-cooling systems (two heat-conductive polymers, one phase change material, and non-convective air as reference) in an application scenario of practical relevance (the intensive use of a power tool followed by cooling down and charging steps). The simulation comprises battery models of 21700 cells that are commercially available as well as heat transfer models. The study highlights the performance of the different cooling materials and their effect on the maximum pack temperature and total charging cycle time. Key material parameters and their influence on the battery pack temperature and temperature homogeneity are discussed. Using phase change materials and heat-conductive polymers, a significantly lower maximum temperature during discharge (up to 26%) and a high shortening potential of the use/charging cycle (up to 32%) were shown. In addition to the cooling material sweep, a parameter sweep was performed, varying the external temperature and air movement. The high importance of the conditions of use on the cooling system’s performance was illustrated.
Transformations in the work–nonwork interface highlight the importance of effectively managing the boundaries between life domains. However, do the ways individuals manage the boundaries between work and nonwork life change from one day to the next? If so, which antecedents may explain these intra-individual fluctuations in boundary management? Drawing on boundary management, spillover, and resource theories, we investigate daily changes in segmentation preferences and integration enactments as a function of experiencing strain in work and nonwork life. Assuming that changes in segmentation preferences reflect an individual’s strategy to regulate negative cross-role spillover, we suppose that strain increases individuals’ segmentation preferences; at the same time, however, it could force individuals to enact more integration.
Identification and quantitative segmentation of individual blood vessels in mice visualized with preclinical imaging techniques is a tedious, manual or semiautomated task that can require weeks of reviewing hundreds of levels of individual data sets. Preclinical imaging, such as micro-magnetic resonance imaging (μMRI) can produce tomographic datasets of murine vasculature across length scales and organs, which is of outmost importance to study tumor progression, angiogenesis, or vascular risk factors for diseases such as Alzheimer’s. Training a neural network capable of accurate segmentation results requires a sufficiently large amount of labelled data, which takes a long time to compile. Recently, several reasonably automated approaches have emerged in the preclinical context but still require significant manual input and are less accurate than the deep learning approach presented in this paper—quantified by the Dice score. In this work, the implementation of a shallow, three-dimensional U-Net architecture for the segmentation of vessels in murine brains is presented, which is (1) open-source, (2) can be achieved with a small dataset (in this work only 8 μMRI imaging stacks of mouse brains were available), and (3) requires only a small subset of labelled training data. The presented model is evaluated together with two post-processing methodologies using a cross-validation, which results in an average Dice score of 61.34% in its best setup. The results show, that the methodology is able to detect blood vessels faster and more reliably compared to state-of-the-art vesselness filters with an average Dice score of 43.88% for the used dataset.
EMDR-Therapie im Vergleich zu EMDR-Therapie, erweitert durch taktilen und auditorischen Stimulus
(2023)
EMDR (Eye Movement Desensitization and Reprocessing) ist ein neurobiologisch orientierter psychotherapeutischer Ansatz zu Behandlung von posttraumatischen Belastungsstörungen (PTBS) und anderen belastenden Lebensereignissen. Dabei werden Augenbewegungen eingesetzt, um die Verarbeitung und Integration traumatischer Erinnerungen zu erleichtern. Diese nichtinterventionelle Anwendungsbeobachtung untersucht die Bedeutung von Augenbewegungen in EMDR und potenzielle Vorteile der Einbeziehung auditiver und taktiler Reize in die Therapie.
The surface topography of biodegradable polymer foils is modified by mechanical imprinting on a submillimeter length scale. The created patterns strongly influence the wetting behavior and allow the preparation of hydrophobic surfaces with controlled solid-liquid interaction. A detailed analysis of anisotropic surface patterns reveals that the observed effect arises from a combination of topographical and compositional changes that are introduced to the surface. As a main result it is found that an individual combination of material and structure is required for the production of water-repellent biopolymer foils that are highly attractive for packaging applications.
Laser melting manufacturing of large elements of lunar regolith simulant for paving on the Moon
(2023)
The next steps for the expansion of the human presence in the solar system will be taken on the Moon. However, due to the low lunar gravity, the suspended dust generated when lunar rovers move across the lunar soil is a significant risk for lunar missions as it can affect the systems of the exploration vehicles. One solution to mitigate this problem is the construction of roads and landing pads on the Moon. In addition, to increase the sustainability of future lunar missions, in-situ resource utilization (ISRU) techniques must be developed. In this paper, the use of concentrated light for paving on the Moon by melting the lunar regolith is investigated. As a substitute of the concentrated sunlight, a high-power CO2 laser is used in the experiments. With this set-up, a maximum laser spot diameter of 100 mm can be achieved, which translates in high thicknesses of the consolidated layers. Furthermore, the lunar regolith simulant EAC-1A is used as a substitute of the actual lunar soil. At the end of the study, large samples (approximately 250 × 250 mm) with interlocking capabilities were fabricated by melting the lunar simulant with the laser directly on the powder bed. Large areas of lunar soil can be covered with these samples and serve as roads and landing pads, decreasing the propagation of lunar dust. These manufactured samples were analysed regarding their mineralogical composition, internal structure and mechanical properties.
Future lunar exploration will be based on in-situ resource utilization (ISRU) techniques. The most abundant raw material on the Moon is lunar regolith, which, however, is very scarce on Earth, making the study of simulants a necessity. The objective of this study is to characterize and investigate the sintering behavior of EAC-1A lunar regolith simulant. The characterization of the simulant included the determination of the phase assemblage, characteristic temperatures determination and water content analysis. The results are discussed in the context of sintering experiments of EAC-1A simulant, which showed that the material can be sintered to a relative density close to 90%, but only within a very narrow range of temperatures (20–30 °C). Sintering experiments were performed for sieved and unsieved, as well as for dried and non-dried specimens of EAC-1A. In addition, an analysis of the densification and mechanical properties of the sintered specimens was done. The sintering experiments at different temperatures showed that the finest fraction of sieved simulant can reach a higher maximum sintering temperature, and consequently a higher densification and biaxial strength. The non-dried powder exhibited higher densification and biaxial strength after sintering compared to the dried specimen. This difference was explained with a higher green density of the non-dried powder during pressing, rather than due to an actual influence on the sintering mechanism. Nevertheless, drying the powder prior to sintering is important to avoid the overestimation of the strength of specimens to be fabricated on the Moon.
The use of computers spread among the population, both for work and leisure purposes. This poses an increased risk factor for dry eye disease, a multifactorial disease influencing the surface of the eye. With the recent increasing usage of head-mounted displays, it is critical to determine whether or not they have the same impact on the tear film as conventional screens.
Ein Ziel der vorliegenden Bachelorthesis ist es, die Berufsbilder OrthoptistIn und OptometristIn vorzustellen,deren Zusammenhänge und Unterschiede hinsichtlich der Betreuung von Kindern zu ermitteln und somit gegenüberzustellen. Um die notwendigen Informationen für eine Gegenüberstellung zu erhalten, soll eine Online-Umfrage durchgeführt werden. Es soll gezeigt werden, welche Gemeinsamkeiten in der Vorgehensweise bezüglich der Betreuung von Kindern vorliegen. Für die Gegenüberstellung sollen zudem Grundlagen zu den Berufsbildern und deren Aufgabenbereich sowie zu den visuellen Begebenheiten von Kindern erarbeitet und aufgezeigt werden. Des Weiteren soll ein Leitfaden zur optometrischen Betreuung von Kindern mit binokularen Sehproblemen ab dem Grundschulalter erstellt werden, der zur praktischen Anwendung für Optometristen dient und ein Protokoll zur Dokumentation von Ergebnissen beinhaltet. Dieser Leitfaden soll Optometristen ein strukturiertes und geleitetes Vorgehen ermöglichen.
In Branchen wie Luftfahrt, Hotellerie oder Autovermietungen gehört «Revenue-Marketing» (kurz: RM) in Form von dynamischer Preisgestaltung schon lange zum angewendeten Standard. Ziel dieser Studie ist herauszufinden, wie die Haltung der schweizerischen Augenoptikerbranche gegenüber «Revenue-Marketing» ist. Es wird analysiert, wie viele Augenoptikfachgeschäfte in der Schweiz dynamische Preise anwenden und wie viele diese nicht anwenden. Es wird analysiert, wie die dynamischen Preise gesteuert werden und welche Produkte betroffen sind. Werden noch keine dynamischen Preise verwendet, wird nachgefragt, ob eine mögliche Einführung geplant ist. Sofern keine Einführung geplant ist, werden die Ablehnungsgründe analysiert. Zudem wird geforscht, ob die Firmengrösse einen Einflussfaktor auf die Verwendung von «Revenue-Marketing» hat.
Comparing axial eye length to other physiological properties of the eye, body height and the head
(2022)
Purpose: To find, if there is any relationship between axial eye length and other physiological properties of the eye (horizontal corneal diameter, average corneal radius, central corneal thickness, objective spherical equivalent, pupillary distance), body height, and head size. Can any of these correlations eventually complement models in myopia progression or be the model for further research.
Telemedicine assisted non-mydriatic Fundus imaging for detection of Diabetic Retinopathy in Colombia
(2022)
Diabetic retinopathy (DR) is a well-recognized complication of diabetes mellitus where retinal function is compromised. It is considered a public health disease and is the fifth leading cause of visual impairment worldwide. But although the worldwide prevalence is continually increasing, little is known about the frequency of this disease in Colombia, South America. On the other hand, telemedicine is presented as a tool that has the potential to improve access to health care services, for remote or rural populations, and for those who have limited access due to physical or other disabilities. Recent technological advances in telecommunication and digital imaging, including fundus photography, telemedicine represents a valuable clinical aid for the documentation and diagnosis of ocular pathologies, and therefore helps to minimize adverse outcomes associated with chronic disease such as diabetes mellitus.
Ziel: Eine Analyse der aktuellen wissenschaftlichen Literatur zu Orthokeratologie bei Myopie. Es werden Studienergebnisse zu verschiedenen Aspekten der Orthokeratologie miteinander verglichen und auf ihre Übereinstimmung überprüft. Der Fokus wird auf die Veränderungen der visuellen Wahrnehmung und der kornealen Beschaffenheit während und nach der Anwendung von Orthokeratologie gelegt.
Ziele: Ziel dieser Arbeit ist es, eine funktionierende Software zu entwickeln, die es ermöglicht, aufgrund von verschiedenen Messungen, einen evidenzbasierten Therapievorschlag zur Behandlung des trockenen Auges zu generieren. Sie soll an das jeweilige örtliche Angebot von Mess- und Therapieoptionen anpassbar sein, um das große und oft unübersichtliche Angebot an Therapieoptionen effizienter und somit wirtschaftlicher nutzen zu können.
Der positive Versorgungseffekt digitaler Gesundheitsanwendungen bei onkologischen Erkrankungen am Beispiel des Mammakarzinoms kann anhand onkologischer Leitlinienempfehlungen abgeleitet werden. Existieren bereits Studien zu Gesundheitsanwendungen mit positivem Versorgungseffekt, können die behandelten Funktionen als evidenzbasierter Ansatz verwendet werden. Betreffen diese Studien andere Krankheiten, sind diese Untersuchungen nicht auszuschließen. Ein positiver Versorgungseffekt könnte sich dennoch bei Brustkrebspatient:innen zeigen. Hier besteht in jedem Fall Forschungsbedarf. Bei der Umsetzung der Leitlinienempfehlungen mittel App sollte darauf geachtet werden, ob die Empfehlungen allein durchführbar sind oder ob dafür professionelle persönliche Unterstützung nötig ist. Je nach Ergebnis wird entschieden, ob die Empfehlung digital umsetzbar ist oder nicht.
The purpose of this master thesis is to make a manual on cataracts so that optometrists in the Republic of Croatia have in one place everything about the causes, diagnosis, and treatment of cataracts. According to the World Health Organization cataract is one of the leading causes of vision impairment in the world. By properly diagnosing the type of cataract, we provide patients with a better quality of life and a visual aid with which they will achieve maximum visual acuity. This master’s thesis will summarize all the knowledge from the master's degree in Aalen in order to get a broader picture of the formation of cataracts. On daily basis optometrists encounter cataract pathology, the goal is to better understand what affects cataract formation, from drugs to systemic diseases, and to ultimately help the client see better after resolving cataract pathology.
Die Notwendigkeit optometrischer Dienstleistungen, die über die Refraktion hinausgehen, ist seit einiger Zeit bekannt. Doch für den Beweis, dass und wie sie im Fachgeschäft funktionieren, fehlen meist die Erfahrungen. In dieser Abschlussarbeit wird dies an einem seit über 15 Jahren angewendeten Optometrie-Konzept eines augenoptischen Fachgeschäfts bewiesen. Es werden die Anfänge der Pioniere retrospektiv betrachtet, die gegenwärtige Anwendung des optometrischen Untersuchungskonzepts und Möglichkeiten, die die Zukunft bietet.