Design of a self-adjusting antenna feed for a homologous designed tiltable 20m-radio-telescope

Radioteleskope sind verschiedenartigen Umwelteinflüssen ausgesetzt. Dadurch hervorgerufene Verformungen der Reflektoroberfläche verändern deren geometrischen Eigenschaften und können die ursprüngliche Position und Form des Brennpunkts verändern. Eine Abweichung dieses Brennpunkt von der Lage der Primärantenne beeinflusst die Leistungsfähigkeit des Teleskops. Die vorliegende Arbeit zeigt eine Methode zur theoretischen Abschätzung der Verformung durch das Eigengewicht des Reflektors des INRAS RT–20. Jene nach der Idee des homologen Designs von Hoerners konstruierten Teleskopen weisen eine Stützstruktur auf, die die Reflektorfläche unabhängig vom Elevationswinkel in einer der ursprünglichen Form ähnlichen Gestalt halten. Somit kann die Verformung durch das Nachführen der Primärantenne ausgeglichen werden. Grundlage der Untersuchung ist ein vorhandenes Strukturmodell des RT–20–Teleskops. Zusammen mit den zugehörigen Geometriedaten und Materialparameten wird ein Finite-Element-Modell erstellt. Für dieses wird ein Belastungsfall mit dem Eigengewicht für verschiedene Elevationswinkel simuliert. Um die deformierte Reflektorfläche mathematisch zubeschreiben und den passenden Brennpunkt zu bestimmen wird eine parametrisierte Form eines Best-Fit-Paraboloids erörtert. Für die Ermittlung der Parameter werden drei Optimierungsalgorithmen in Matlab ausgeführt und miteinander verglichen. Daraus wird die Verschiebung des Brennpunkts (Defokussierung) ermittelt und der Bedarf einer Korrekturbewegung für die Primärantenne abgeschätzt. In einem Entwurfsprozess werden nach den Ideen der VDI2221–Norm technische Prinzipe für ein Aktuierungssystem entwickelt und bezüglich ausgewählter Kriterien gegeneinander abgewogen. Als Resultat dieses Bewertungsprozesses wird eines der Prinzipe erwählt und spezifiziert. Für die spätere Umsetzung werden Komponenten vorgeschlagen, Bauteile vorbereitend konstruiert und in einer CAD–Software zu einer funktionierenden Baugruppe zusammengefügt.Radio telescopes are exposed to various environmental conditions. These can produce deformations of the reflector surface that will have impact on its paraboloidal characteristics determining the position and shape of the focal point. A misalignment between the reflector focal point and the radiation–receiving primary antenna influences the performance of the telescope. The actual work presents a method to estimate theoretically the dead–weight induced deformation of the reflector surface for the INRAS PUCP RT–20 radio telescope. Such homologous designed telescopes consist of a backing structure supporting the reflector surface to retain a shape familiar to the original one and independent of the elevation angle. So it is possible to compensate the deformation by the adjustment of the primary antenna. The analysis of the deformation is done for an existing structural model of the RT–20. This model is meshed with the corresponding geometrical and material properties. In a finite–element software the load situation due to the telescope’s dead weight is simulated for different elevation angles. To describe the deformed reflector surface in a mathematical way an expression for a parametrized best-fitting paraboloid is derived. To determine the fit-parameters for the discrete point set, three optimization algorithms are executed in Matlab and their results compared. Based on this, the need of a re-alignment of the primary antenna is demonstrated. Thereupon a design process for an actuation system intended for the corrective movement is performed, following the ideas of the VDI2221–norm. Several mechanical concepts are presented and evaluated in relation to their suitability for the main needs. Based on this assessment, a parallel–kinematic mechanism is chosen as the most convenient concept. This is examined in more detail, including a deviation for the inverse kinematics. For this concept, a preliminary selection of specific components is done and assembled in a CAD–prototype.Tesi

Frühdiagnose lokaler, struktureller Schäden der Gelenkoberflächen humaner Femurkondylen anhand fluoreszenzmikroskopisch-räumlicher Analysen

Die Diagnose früher struktureller Veränderungen im Gelenkknorpel ist nach wie vor ein klinisches Problem. In diesem Kontext ist die Organisation der Chondrozyten als bildbasierter Biomarker zur Feststellung früher struktureller und/oder degenerativer Veränderungen prinzipiell geeignet. Dieser Biomarker beruht bisher im Wesentlichen auf einer subjektiven Klassifizierung der Verteilungsmuster der oberflächennahen Chondrozyten. Mit dieser Arbeit sollten Fragen zur methodischen Weiterentwicklung der Verwendung der räumlichen Organisation der superfiziellen Chondrozyten als bildbasierter Biomarker beantwortet werden. Hierzu wurden Proben (n=16) aus der Knorpeloberfläche von humanen Femurcondylen zunächst makroskopisch-visuell nach Schädigungsgrad klassifiziert und im Anschluss elektronen- und fluoreszenzmikroskopisch aufgearbeitet. Neben der Erfassung weiterer optisch-visueller Scores incl. des räumlichen Verteilungsmusters der oberflächlichen Chondrozyten erfolgt auch die Bestimmung von quantitativen Messparametern, wobei durch exakte Übereinanderlagerung der REM- und der fluoreszenzmikroskopischen Bilder, ein Vergleich sowohl global über die ganze Probe hinweg, wie auch lokal in einzelnen kleinen Ausschnitten innerhalb der Probe zu ermöglicht wurde. Veränderungen der räumlichen Organisation der superfiziellen Chondrozyten waren dabei bereits im visuell-makroskopisch- und rasterelektronenmikroskopisch intakten Knorpelproben zu finden. Eine lokale Betrachtungsweise der Proben schien dabei der globalen überlegen. Es konnte ein Panel an quantitativen und qualitativen Messparametern der räumlichen Organisation superfizieller Chondrozyten bestimmt werden, das gegenüber REM-Untersuchungen verlässlich dazu geeignet ist, Schäden der Knorpeloberfläche anzuzeigen. Dabei gingen relativ geringe Unterschiede in der Intaktheit der Knorpeloberflächen in der REM mit prominenten und deutlich diagnostifizierbaren Veränderungen in der räumlichen Organisation einher. Proben mit REM intakter Knorpeloberfläche vs. REM-unebener Oberfläche mit Fibrillationen konnten durch Untersuchungen der räumlichen Organisation der superfiziellen Chondrozyten erstmalig statistisch erfolgreich voneinander unterschieden werden. Damit könnte die visuelle Klassifikation der räumlichen Organisation der superfiziellen Chondrozyten ein besonders wichtiges Kriterium in der Früh-Diagnose von osteoarthrotischen Veränderungen von Gelenken sein, bestenfalls bereits im histologischen OARSI-Stadium I

THE H3/H4 HISTONE GENE CLUSTER OF LAND SNAILS (GASTROPODA: STYLOMMATOPHORA): TS/TV RATIO, GC3 DRIVE AND SIGNALS IN STYLOMMATOPHORAN PHYLOGENY

Histone gene primers were developed for land snails (Stylommatophora). The partial H3/H4 histone gene cluster was cloned and sequenced for 18 species. Transcription of the H3 and H4 genes was divergent (each gene is transcribed in the opposite direction) as has been found for other protostome and diploblast animals, with the exception of Mytilus. In the bivalve Mytilus transcription of both genes occurs in the same direction, i.e. land snails and bivalves seem to differ in their histone gene organization. The non-transcribed H3/H4 spacer varied in length between 279 and 691 basepairs. Nucleotide polymorphisms in this non-transcribed spacer might be of significance to study phylogenetics and systematics of closely related species and genera. As expected, the coding regions exhibited no amino acid substitution among land snail species. However, one amino acid substitution was found in comparison between land snails and Drosophila. The transition/transversion (TS/TV) ratio of H3 and H4 was predominately shaped by the third codon position and ranged in most cases from 1.0 to 2.0, indicating low nucleotide saturation. GC content was calculated for the third codon position (GC3 index at the ‘wobble' base position). The histone GC3 values were far lower in land snails than values currently available for other genomes (i.e. mammals). This indicates that H3/H4 histone wobble bases of land snails evolve without strong GC drive. Phylogenetic trees were reconstructed from the coding regions. We used Succinea putris (Elasmognatha) as outgroup. Trichia villosa (Helicoidea) showed six apomorphic nucleotide signals. Moreover, the nucleotide signals give evidence that the Cochlicopidae, Vertiginidae and Valloniidae are paraphyletic family categories. The paraphyletic status of cochlicopid, vertiginid and valloniid gastropods is also supported by our unpublished ribosomal DNA tree

A Proof Strategy Language and Proof Script Generation for Isabelle/HOL

We introduce a language, PSL, designed to capture high level proof strategies in Isabelle/HOL. Given a strategy and a proof obligation, PSL's runtime system generates and combines various tactics to explore a large search space with low memory usage. Upon success, PSL generates an efficient proof script, which bypasses a large part of the proof search. We also present PSL's monadic interpreter to show that the underlying idea of PSL is transferable to other ITPs.Comment: This paper has been submitted to CADE2

Is it COVID or a Cold? An Investigation of the Role of Social Presence, Trust, and Persuasiveness for Users\u27 Intention to Comply with COVID-19 Chatbots

The COVID-19 pandemic challenged the existing healthcare system by demanding potential patients to self-diagnose and self-test a potential virus contraction. In this process, some individuals need help and guidance. However, the previous modus-operandi to go to a physician is no longer viable because of the limited capacity and danger of spreading the virus. Hence, digital means had to be developed to help and inform individuals at home, such as conversational agents (CA). The human-like design and perceived social presence of such a CA are central to attaining users’ compliance. Against this background, we surveyed 174 users of a commercial COVID-19 chatbot to investigate the role of perceived social presence. Our results provide support that the perceived social presence of chatbots leads to higher levels of trust, which are a driver of compliance. In contrast, perceived persuasiveness seems to have no significant effect

Applied Machine Learning: Reconstruction of Spectral Data for the Classification of Oil-Quality Levels

In modern complex systems and machines - e.g., automobiles or construction vehicles - different versions of a "Condition Based Service" (CBS) are deployed for maintenance and supervision. According to the current state of the art, CBS is focusing on monitoring of static factors and rules. In the area of agricultural machines, these are for example operating hours, kilometers driven or the number of engine starts. The decision to substitute hydraulic oil is determined on the basis of the factors listed. A data-driven procedure is proposed instead to leverage the decision-making process. Thus, this paper presents a method to support continuous oil monitoring with the emphasis on artificial intelligence using real-world spectral oil-data. The reconstruction of the spectral data is essential, as a complete spectral analysis for the ultraviolet and visible range is not available. Instead, a possibility of reconstruction by sparse supporting wavelengths through neural networks is proposed and benchmarked by standard interpolation methods. Furthermore, a classification via a feed-forward neural network with the conjunction of Dynamic Time Warping (DTW) algorithm for the production of labeled data was developed. Conclusively, the extent to which changes in hyper-parameters (number of hidden layers, number of neurons, weight initialization) affect the accuracy of the classification results have been investigated

Tragulidae and pecoran ruminants from the latest Middle Miocene (Sarmatian, late Astaracian) of Austria.

One of the richest and most complete European terrestrial vertebrate faunas of late Middle Miocene age (12.2¿12.0 Ma; Gross et al., in press) was found near Gratkorn, at the northeastern realm of the Styrian Basin (Austria). It is one of the rare localities from the Sarmatian sensu stricto (late Serravallian) in the Central Paratethys area with a vertebrate fauna, both high in quality as well as rich in quantity. So far, 62 taxa are recorded, including Euprox furcatus, Micromeryx flourensianus and Dorcatherium naui. This is one of the rare records of Dorcatherium naui older than Vallesian and the oldest finding of the species from the Paratethys realm so far. Up to now, Dorcatherium naui of pre-Vallesian ages have only been described from Przeworno (Poland; Glazek et al., 1971), and Abocador de Can Mata (Spain; Alba et al., 2011), which are of latest Middle Miocene age like Gratkorn. Therefore the latter does not only represent one of the oldest records of Dorcatherium naui but also supports the wide distribution of the taxon already at the latest Middle Miocene. In contrast to the site of Abocador de Can Mata, where Dorcatherium naui is an infrequent element (Alba et al., 2011), the species is abundant at the locality of Gratkorn. Apart from this the larger mammal fauna of Abocadar de Can Mata and Gratkorn is quite similar, except of proboscidean and bovid taxa. While in Abocador de Can Mata Gomphotherium, Deinotherium and bovids are present (Alba et al., 2009), in Gratkorn only Deinotherium giganteum was found until now. Bovids were found in contemporaneous sediments in the eastern Styrian Basin (Gross et al., in press), though. With the material of Gratkorn previous ideas on ecological adaptations in Dorcatherium (Rössner, 2004) are supported and the understanding of the ecological niche of the ¿forest-dweller¿ Dorcatherium is specified. Besides new ideas on dispersal, evolution and ecology of Dorcatherium the locality of Gratkorn also enables an in-depth evaluation of its species separation. The specimens from Gratkorn demonstrate, in comparison with other Material from the Paratethys area, a clear distinction between Dorcatherium crassum and Dorcatherium naui and underline the taxonomic separation of both species as accepted by several authors (e.g. Alba et al., 2011). REFERENCES Alba, D.M. et al. (2009). Middle Miocene vertebrate localities from Abocador de Can Mata (els Hostalets de Pierola, Vallès Penedès Basin, Catalonia, Spain): An update after the 2006-2008 field campaigns. Paleolusitana, 1, 59¿73. Alba, D.M. et al. (2011). Middle Miocene tragulid remains from Abocador de Can Mata: the earliest record of Dorcatherium naui from Western Europe. Geobios, 44, 135-150. Glazek, J. et al. (1971). Miocene vertebrate faunas from Przeworno (Lower Silesia) and their geological setting. Acta Geologica Polonica, 21(3), 473-516. Gross, M. et al. (in press). Gratkorn ¿ A benchmark locality for the continental Sarmatian s. str. of the Central Paratethys. International Journal of Earth Sciences, doi: 10.1007/s00531-010-0615-1. Rössner, G.E. (2004). Community structure and regional patterns in late Early to Middle Miocene Ruminantia of Central Europe. Courier Forschungs-Institut Senckenberg, 249: 91-100.Peer Reviewe