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Fluorinated Polymers for Photonics—From Optical Waveguides to Polymer-Clad Glass Optical Fibers
No full textIn this paper, our work in the field of fluorinated UV-curable polymers is reviewed. These polymers possessing tunable low refractive indices and low optical propagation losses for telecommunication wavelengths are intended to be used as core and cladding materials for the fabrication of passive channel waveguides in optical microchips on the polymer platform. This application requires low thermo-optic coefficients. With this goal, we used a combination of fluorinated polymers with low-refractive index inorganic nanoparticles of SiO2 and MgF2. Another application requiring extremely low refractive indices is polymer cladding for optical glass fibers. UV-curable fluorinated monomers/oligomers were used
Demonstration of ultra-high dose rate electron irradiation at FLASHlab@PITZ
No full textObjective. The photo injector test facility at DESY in Zeuthen (PITZ) is building up an R&D platform, known as FLASHlab@PITZ, for systematically studying the FLASH effect in cancer treatment with its high-brightness electron beams, which can provide a uniquely large dose parameter range for radiation experiments. In this paper, we demonstrate the capabilities by experiments with a reduced parameter range on a startup beamline and study the potential performance of the full beamline by simulations. Approach. To measure the dose, Gafchromic films are installed both in front of and after the samples; Monte Carlo simulations are conducted to predict the dose distribution during beam preparation and help understand the dose distribution inside the sample. Plasmid DNA is irradiated under various doses at conventional and ultra-high dose rate (UHDR) to study the DNA damage by radiations. Start-to-end simulations are performed to verify the performance of the full beamline. Main results. On the startup beamline, reproducible irradiation has been established with optimized electron beams and the delivered dose distributions have been measured with Gafchromic films and compared to FLUKA simulations. The functionality of this setup has been further demonstrated in biochemical experiments at conventional dose rate of 0.05 Gy s−1 and UHDR of several 105 Gy s−1 and a varying dose up to 60 Gy, with the UHDR experiments finished within a single RF pulse (less than 1 millisecond); the observed conformation yields of the irradiated plasmid DNA revealed its dose-dependent radiation damage. The upgrade to the full FLASHlab@PITZ beamline is justified by simulations with homogeneous radiation fields generated by both pencil beam scanning and scattering beams. Significance. With the demonstration of UHDR irradiation and the simulated performance of the new beamline, FLASHlab@PITZ will serve as a powerful platform for studying the FLASH effects in cancer treatment
Hochgeschwindigkeitszählung von Maden für eine nachhaltige Proteinproduktion
No full textInsekten werden aufgrund ihres Proteingehalts als eine der nachhaltigen Quellen für die Lebensmittelproduktion der Zukunft angesehen. Sie werden, analog zu den heutigen Zuchtbetrieben für Schweine und andere Nutztiere, auch in industriellen Anlagen gezüchtet. Zur Steuerung und Optimierung dieses Zuchtprozesses muss eine Erfassung der Zahl der unter gegebenen Bedingungen aufgezogenen Insekten vorgenommen werden. Im Unterschied zu Großsäugern ist die Individuenzahl von Insekten sowie deren Larvenstadien jedoch um Magnituden größer, so dass bei der Ermittlung der Anzahl der Insekten mittel- und langfristig auf eine vollautomatisierte maschinelle Erfassung umgestellt werden muss. In dieser Arbeit wird eine Methode zur präzisen Zählung einer großen Zahl von Maden der Schwarzen Soldatenfliege (Hermetia illucens) in einem prototypischen Aufbau vorgestellt
AI-Driven Research in the Recruitment and Selection Process: Application of an AI Taxonomy With a Systematic Literature Review
No full textA review of the literature on the application of artificial intelligence (AI) in the recruitment and selection process (RSP) was conducted, but no relevant studies were identified. While several reviews have focussed on AI in human resource management in general, none of these have examined the RSP in detail or employed an AI taxonomy for clustering. Consequently, we applied an AI taxonomy identified in the literature with the aim to identify the stages of the RSP in the focus of research and the algorithms mostly used. We conducted a systematic literature review underpinned by a concept matrix, complemented by a computational literature review (CLR), that employed natural language processing (NLP). The initial 4,579 studies were sourced from three databases and narrowed down to a total of 502. Our major findings indicate that the majority of studies were categorised under the stages “assessment & selection” and “processing incoming applications” in the RSP. The predominant algorithms in use pertain to the field of NLP and machine learning. The CLR emphasised the significance of ethics in AI research. While our study has expanded the general AI taxonomy by incorporating an ethical perspective and is one of the studies with the most articles used to reflect this topic, it is solely focussing on describing the past. Nevertheless, this article helps to align research on exploring and testing alternative approaches with those most frequently used
Perceived safety using multi-lane and canopied bicycles (velocars)
No full textThe feeling of safety is one of the most crucial elements of bicycle promotion. Newer bicycle designs with three or even four wheels have constructive possibilities to implement some safety features comparable to a car, e. g. brake lights, warning lights, and indicator lights, a seat belt or even a canopy to protect the driver from rain and headwinds. Positioning this kind of vehicle between micro car and bicycle, manufacturers try to address new user groups for which a bicycle has been no option nor a car. Further developments of recumbent bicycles, velomobiles and cargo bikes, the velocar from the 1930s is experiencing a renaissance. A new design language based on the car, a higher elevation of the head above street level and the addition of the electric motor mean that a completely new vehicle category may emerge that has the chance to develop from a niche into a mass product. Would new user groups be attracted by this kind of vehicle? This research investigates the perceived safety of 124 experienced cyclists riding on cycles like cargo bikes and velomobiles with a wide body of nearly one meter
Erkennung von Schadmustern an Personenverkehrszügen und Evaluierung der Konfidenz zur Auswahl robuster Features für „Predictive Maintenance“ - Projekt ESPEK
No full textIm Rahmen des Projekts ESPEK wurden Häufigkeit und Relevanz bestimmter Schäden an verbreiteten Waggontypen analysiert und basierend darauf im Rahmen eines Konzepts „KI-gestützte Inspektion“ praxistaugliche, datenbasierte, durch künstliche Intelligenz unterstützte digitale Lösungen entwickelt, um Schäden an ausgewählten Personenwaggons automatisiert visuell zu erkennen. Ausgehend von den bisher maßgeblich manuellen Inspektionsabläufen und Checklisten können selbige durch die vorgeschlagenen Software- und Hardwareautomatisierungen effizienter gestaltet werden. Übergeordnet werden die Sicherheit der Fahrgäste erhöht, das Problem des Fachkräftemangel bekämpft sowie Ausfall- und Standzeiten reduziert, was letztlich zur besseren Auslastung des Systems Schiene insgesamt beiträgt und Zugfahren preiswerter und pünktlicher machen kann
Konzeption und prototypische Umsetzung eines Exporters im Oxford Common File Layout (OCFL) für die Repository-Software OPUS4
No full textMit dem Oxford Common File Layout (OCFL) wurde im Jahr 2020 eine Lösung vorgestellt, wie die Austauschbarkeit von Daten zwischen unterschiedlichen Repository-Systemen und die langfristige Verfügbarkeit digitaler Objekte ermöglicht werden kann. Verschiedene Metadatenschemata und unterschiedliche Speicherorganisationen erschwerten dies bislang. In dieser Arbeit wird untersucht, ob es möglich ist aus der Repository-Software OPUS4 einen OCFL-konformen Export zu erstellen. Hierzu wird zunächst ein technisches Konzept zur Umsetzung eines OCFL-Exporters aus OPUS4 entworfen, welches anschließend prototypisch in einer OPUS4-Testinstanz implementiert wird, um Anpassungen am Exporter vorzunehmen. Die erzeugten Daten werden mit Hilfe eines Validators geprüft. Es folgt eine Auswertung der Ergebnisse. In der Arbeit wird die technische Machbarkeit eines OCFL-Exporters für die Repository-Software OPUS4 untersucht. Dabei werden Probleme und Herausforderungen ermittelt, sowie Grenzen aufgezeigt.In 2020, the Oxford Common File Layout (OCFL) was presented as a solution for enabling the exchange of data between different repository systems and the long-term availability of digital objects. Various metadata schemas and different storage organizations have made this difficult so far. This work examines whether it is possible to create an OCFL-compliant export from the OPUS4 repository software. To do this, a technical concept for implementing an OCFL exporter from OPUS4 is first designed, which is then implemented prototypically in an OPUS4 test instance to make adjustments to the exporter. The generated data is checked using a validator. This is followed by an evaluation of the results. The work examines the technical feasibility of an OCFL exporter for the OPUS4 repository software. It identifies problems and challenges, and shows limitations
Untersuchung von Methoden zur Vorhersage der Ausleihzahlen von Büchern in öffentlichen Bibliotheken anhand ihrer Coverbilder
No full textIn dieser Arbeit untersuche ich, ob anhand der Coverbilder von Büchern deren Ausleihhäufigkeit in öffentlichen Bibliotheken vorhergesagt werden kann. Zusätzlich werte ich aus, ob ein Einbezug der Titel der Bücher sowie der Namen der Autor*innen die Vorhersagequalität verbessert. Dazu setze ich Werkzeuge aus dem Bereich Machine Learning ein. Mithilfe von Bild- und Textverarbeitungsverfahren (die Erstellung von Farbhistogrammen sowie die Verwendung von mit Deep Learning vortrainierten Modellen) erstelle ich Embeddings für die vorliegenden Daten. Die Ausleihhäufigkeit versuche ich in Form einer Klassifikation vorherzusagen, und verwende dafür einen KNN-Algorithmus. Die Vorhersagegenauigkeit (Accuracy) erreicht, unter Verwendung verschiedener Kombinationen von Embeddings und weiterer Parameter, nur einen Höchstwert von 65%. Damit ist die Vorhersage zwar besser, als zufälliges Raten, aus meiner Sicht aber nicht ausreichend belastbar, um auf dieser Grundlage zum Beispiel Erwerbungsentscheidungen zu treffen.In this thesis, I investigate whether the cover images of books can be used to predict their circulation frequency in public libraries. Additionally, I analyse whether the inclusion of titles of the books and the names of the authors improves the prediction quality. For this, I use machine learning tools. With the help of image and text processing methods (colour histograms and pre-trained deep learning models), I create embeddings for the data. I try to predict the circulation frequency as a classification using a KNN algorithm. Using different combinations of embeddings and other parameters, the prediction accuracy reaches a maximum value of 65%. This makes the prediction better than random guessing, but in my opinion, it is not sufficiently reliable to be used e.g. as a basis for making acquisition decisions
Subjective validation for short-term material flow simulation
No full textMaterial flow simulation, by means of discrete event simulation (DES), is frequently applied to support decision-making in production planning and control. However, manual modeling can be time-consuming and error-prone. Hence, numerous studies propose the automation of model generation and synchronization to overcome these challenges. However, in this context, validation techniques are rarely addressed. Therefore, we introduce a subjective validation technique for short-term material flow simulation based on a coherent methodology for data acquisition and visualization. The methodology is utilized to evaluate the outcome of an approach for computerized model generation and simulation. By means of an industrial use case, we hypothesize the causes for the deviation between the operation of a manufacturing system and the simulation of its generated virtual companion
A Novel Exponential Continuous Learning Rate Adaption Gradient Descent Optimization Method
No full textWe present two novel, fast gradient based optimizer algorithms with dynamic learning rate. The main idea is to adapt the learning rate α by situational awareness, mainly striving for orthogonal neighboring gradients. The method has a high success and fast convergence rate and relies much less on hand-tuned hyper-parameters, providing greater universality. It scales linearly (of order O(n)) with dimension and is rotation invariant, thereby overcoming known limitations. The method is presented in two variants C2Min and P2Min, with slightly different control. Their impressive performance is demonstrated by experiments on several benchmark data-sets (ranging from MNIST to Tiny ImageNet) against the state-of-the-art optimizers Adam and Lion