Metallic samples with unique micro- and nano-scale surface structures can easily be fabricated with Direct Laser Interference Patterning. Like in all laser processes, the material interacts with the laser radiation and as a result, thermal effects occur. These effects have a significant influence on the resulting quality of the surface patterns. In this study, the thermal effects occurring during Direct Laser Interference Patterning of stainless steel and aluminum sheets are investigated. The used experimental setup consisted of a picosecond pulsed laser source operating at 532 nm wavelength, combined with a two-beam interference optical head. An infrared camera in an off-axis position is used to detect the resulting thermal radiation of the laser process varying different process parameters such as laser power and repetition rate. The obtained results reveal a correlation between the recorded signal by the infrared camera and the reached surface quality. They show an impact of the thermal effects on the quality of the surfaces and the amount of solidified material on the resulting line-like pattern. Threshold values of the detected infrared signal detected are determined to classify the obtained surface conditions.

LAMpAS technology satisfies the increasing demand for products with novel surface performances at an affordable cost by the combination of high-power ultrashort laser sources in combination with new optical concepts for fast materials processing with minimal heat impact on the work piece. Inspired by natural surfaces, LAMpAS offers well-defined surface patterns with controlled length-scales and feature sizes smaller than 1 µm that can provide advance surface functions. LAMpAS technology can provide a wide range of surfaces with novel functionalities.

Recently, process monitoring emerges as a breakthrough technology in industrial laser machines applications to enhance process stability and economic efficiency while ensuring high-quality pro-cessing parts and significantly reducing scrap rate. Furthermore, the latest advances in monitoring systems open a broad range of new opportunities to increase the capabilities of laser surface structur-ing. In this study, stainless steel and aluminum substrates are structured with a line-like geometry by Direct Laser Interference Patterning. A high-speed infrared camera is used to detect the thermal effects throughout the laser process. Simultaneously, a diffraction measurement system is implemented to analyze the quality of the fabricated periodic patterns by comparing the diffraction order characteris-tics. This specific combination of the systems allows a remarkably high-performance process moni-toring and quality assurance. The obtained results reveal a correlation between the signals detected by the infrared camera and the intensity of the diffraction orders recorded with the quality of the surface reached.

Recently, monitoring systems have become crucial components in industrial-scale laser machines to increase process reliability and efficiency. Particularly, monitoring methods have the potential to optimize and ensure the quality of laser surface patterning by indirectly characterizing the surface topography. Here, a diffraction measurement system, based on scatterometry, is used to determine the mean depth of laser-induced periodic surface structures (LIPSS) on stainless steel by analyzing the characteristics of the resulting diffraction patterns. To this end, LIPSS were produced with a ps-pulsed laser system operating at a wavelength of 1064 nm. The results reveal that the mean depth of LIPSS can be extracted from the intensity of the captured diffraction orders down to approximately 14 nm. This compact monitoring tool can be easily adapted to industrial-scale laser systems to improve the quality control and stability of surface microtexturing processes.

Das nachfolgende Datenrepository enthält sämtliche Software und Datenmodelle, die im Rahmen der Dissertation "Ein ontologiebasiertes Verfahren zur automatisierten Bewertung von Bauwerksschäden in einer digitalen Datenumgebung" verwendet wurde. Nachfolgend ist das dazugehörige Abstrakt der Dissertation dargestellt: Neue Technologien im Bereich der Bauwerks- und Schadenserfassung führen zu einer Automatisierung und damit verbundenen Effizienzsteigerung von Inspektionsprozessen. Eine adäquate Digitalisierung des erfassten Bauwerkzustandes in ein BIM-Modell ist jedoch gegenwärtig nicht problemlos möglich. Eine Hauptursache hierfür sind fehlende Spezifikationen für ein digitales Modell, das aufgenommene Schäden repräsentieren kann. Ein Problem bilden dabei Unschärfen in der Informationsmodellierung, die üblicherweise bei BIM-Verfahren im Neubau nicht auftreten. Unscharfe Informationen, wie z.B. die Klassifizierung detektierter Schäden oder Annahme weiterer verborgener Schäden, werden derzeit manuell von Experten evaluiert, was oftmals eine aufwendige Auswertung kontextueller Informationen in einer Vielzahl verteilter Bauwerksdokumente erfordert. Eine automatisierte Bewertung detektierter Schäden anhand des Bauwerkskontextes wird derzeit noch nicht in der Praxis umgesetzt. In dieser Dissertation wird ein Konzept zur Repräsentation von Bauwerksschäden in einem digitalen, generisch strukturierten Schadensmodell vorgestellt. Das entwickelte Konzept bietet hierbei Lösungsansätze für Probleme gegenwärtiger Schadensmodellierung, wie z.B. die Verwaltung heterogener Dokumentationsdaten, Versionierung von Schadensobjekten oder Verarbeitung der Schadensgeometrie. Das modulare Schema des Schadensmodells besteht aus einer generischen Kernkomponente, die eine allgemeine Beschreibung von Schäden ermöglicht, unabhängig von spezifizierenden Faktoren, wie dem betroffenen Bauwerkstyp oder Baumaterial. Zur Definition domänenspezifischer Informationen kann die Kernkomponente durch entsprechende Erweiterungsschemata ergänzt werden. Als präferierte Serialisierungsmöglichkeit wird das Schadensmodell in einer wissensbasierten Ontologie umgesetzt. Dies erlaubt eine automatisierte Bewertung der modellierten Schadens- und Kontextinformationen unter Nutzung digitalisierten Wissens. Zur Evaluation unscharfer Schadensinformationen wird ein wissensbasiertes Bewertungsverfahren vorgestellt. Das hierbei entwickelte Schadensbewertungssystem ermöglicht eine Klassifizierung detektierter Schäden, sowie Folgerung impliziter Bewertungsinformationen, die für die weitere instandhalterische Planung relevant sind. Außerdem ermöglicht das Verfahren eine Annahme undetektierter Schäden, die potentiell im Inneren des Bauwerks oder schwer erreichbaren Stellen auftreten können. In der ontologischen Bewertung werden dabei nicht nur Schadensmerkmale berücksichtigt, sondern auch Informationen bezüglich des Bauwerkskontext, wie z.B. der betroffene Bauteil- oder Materialtyp oder vorliegende Umweltbedingungen. Zur Veranschaulichung der erarbeiteten Spezifikationen und Methoden, werden diese abschließend an zwei Testszenarien angewendet.

New technologies in the field of building and damage detection lead to an automation of inspection processes and thus an increase in efficiency. However, an adequate digitalisation of the recorded building data into a BIM model is currently not possible without problems. One main reason for this is the lack of specifications for a digital model that can represent recorded damages. Thereby, a primary problem are uncertainties and fuzzy data in the information modelling, which usually does not occur when applying BIM for new buildings. Fuzzy information, such as the classification of detected damages or the assumption of further hidden damages, is currently evaluated manually by experts, which often requires a complex evaluation of contextual information in a multitude of distributed building documents. An automated evaluation of detected damages based on the building context is applied or implemented in practice. In this thesis a concept for the representation of structural damages in a digital, generically structured damage model is presented. The developed concept offers solutions for problems of current damage modelling, e.g. the management of heterogeneous documentation data, versioning of damage objects or processing of the damage geometry. The modular scheme of the damage model consists of a generic core component, which allows a general description of damages, independent of specifying factors, such as the type of construction or building material concerned. For the definition of domain-specific information, the core component can be supplemented by corresponding extension schemes. As a preferred serialisation option, the damage model is implemented in a knowledge-based ontology. This allows an automated evaluation of the modelled damage and context information using digitised knowledge. For the evaluation of fuzzy damage information, a knowledge-based evaluation procedure is presented. The developed damage evaluation system allows a classification of detected damages as well as the conclusion of implicit evaluation information relevant for further maintenance planning. In addition, the method allows the assumption of undetected damages that can potentially occur inside the structure or in places that are difficult to reach. In the ontological assessment, not only damage characteristics are considered, but also information regarding the building context, such as the affected component or material type as well as existing environmental conditions. To illustrate the developed specifications and methods, the whole concept is applied to two test scenarios.

Supplemental material and supporting information for the publication: Fritzsche et al. (2022), “Toward unraveling the mechanisms of aerosol generation during phonation” (DOI: 10.1063/5.0124944). \\ For the purpose of investigating the atomization of respiratory mucus during phonation, a new experimental setup was designed which emulates the vocal folds, their oscillating movement and the expiratory air flow in a simplified manner. The primary atomization of an artificial mucus can be observed. Based on the shadowgraphy measurements carried out, droplet size spectra were evaluated and the influence of the parameters flow rate, oscillation frequency and amplitude was investigated. Furthermore, high-speed recordings allowed the visualization and discussion of the droplet formation mechanisms.

For the purpose of investigating the atomization of respiratory mucus during phonation, a new experimental setup was designed which emulates the vocal folds, their oscillating movement and the expiratory air flow in a simplified manner. The primary atomization of an artificial mucus can be observed. Based on the shadowgraphy measurements carried out, droplet size spectra were evaluated and the influence of the parameters flow rate, oscillation frequency and amplitude was investigated. Furthermore, high-speed recordings allowed the visualization and discussion of the droplet formation mechanisms.