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Comparing principal component analysis (PCA) and -variational autoencoder(-VAE)for anomaly detection in selective laser melting (SLM) process data
No full textThe usability of machine learning approaches for the development of in-situ process monitoring, automated anomaly detection and quality assurance for the selective laser melting (SLM) process receives currently increasing attention. For a given set of real machine data we compare two established methods, principal component analysis (PCA) and -variational autoencoder (-VAE), for their applicability in exploratory data analysis and anomaly detection. We introduce a PCA-based unsupervised feature extraction algorithm, which allows for root cause analysis of process anomalies. The -VAE enables a slightly more compact dimensionality reduction; we consider it an option for automated process monitoring systems
Celebrating the Röntgen anniversary year: pupil experiments at Aschaffenburg University
No full textOn November 8th, 1895, Professor Wilhelm Conrad Röntgen was still working late on cathode rays in his laboratory at the University of Würzburg in Germany. By chance, he found a new type of radiation that was able to penetrate materials. He himself called them X-rays. In his honour, in Germany we call this type of radiation Röntgen´s rays since 1896. In 2020, Germany was celebrating the Röntgen anniversary year, recognizing the discovery of X-rays 125 years ago and the 175th birthday of its discoverer Wilhelm Conrad Röntgen, the first Nobel laureate in physics. Financed by a grant from the Klaus Tschira Foundation, the Reiss-Engelhorn-Museums in Mannheim and the German Röntgen Museum in Remscheid developed an “X-periments mobile” with interactive experiments for children and young people. Following the given motto "X-periments - making the invisible visible", this research station with optical experiments started traveling across Germany in the anniversary year and, due to the corona pandemic in the following year. In summer 2021, the “X-periments mobile” will make a guest appearance at Aschaffenburg University. The experimental set-ups enable school classes and students to gain an overview of optical technologies from infrared light to ultraviolet radiation to X-rays and gamma rays. The aim of the campaign is to inspire the young generation and to attract students for courses in science and technology. This contribution presents the historical discovery of X-rays, the “X-periments mobile” and its experiments, its intention, and the experiences from its stays at different places across Germany
Characterisation of X-ray mirrors based on chromium-iridium tri-layer coatings
No full textIridium-based layer systems are highly effective mirror coatings for space-born X-ray telescopes. During the recent years, Aschaffenburg University of Applied Sciences and its partners developed stress compensated chromium-iridium coatings for such astronomical applications, using chromium as an adhesive layer between iridium reflective layer and mirror substrate. However, there was room for improvement: To overcome the disturbing reflectivity reduction of the iridium absorption edge around 2 keV photon energy, thin overcoat layers of chromium are applied in addition now. This layer system has been analyzed by atomic force microscopy and transmission electron microscopy images. Furthermore, the reflectivity of such innovative X-ray mirrors based on chromium-iridium tri-layer coatings was recently measured at PTB's four-crystal monochromator beamline at the synchrotron radiation facility BESSY II. The experimental results, obtained for photon energies between 1.9 keV and 11 keV at two grazing incidence angles (0.6 degree and 0.9 degree) and their comparison with corresponding simulations are presented in this contribution. When compared to simulations of pure iridium coatings, a significantly higher reflectivity was achieved especially in the soft X-ray regime between 2 keV and 4 keV. Such chromium-iridium tri-layer coatings have high potential to increase the effective area for X-ray telescopes in Lobster Eye Design, for Wolter-I type X-ray optics, and for silicon pore optics as considered for the ATHENA telescope of the European Space Agency
Simultaneous Burr and Cut Interruption Detection during Laser Cutting with Neural Networks
No full textCharakterisierung von Weitwinkel-Röntgenteleskopen in der Testanlage PANTER
No full textIm Rahmen einer bayerisch-tschechischen Kooperation entstanden zwei mechanisch baugleiche Röntgenteleskope, bestückt mit Gold- und Iridium-beschichteten Planspiegeln. Die Charakterisierung der nach dem ägyptischen Gott HORUS benannten Teleskope erfolgte an der Röntgentestanlage PANTER des Max-Plack-Instituts für extraterrestrische Physik. Diese Vakuum-Testanlage simuliert parallel auf die Teleskope einfallendes Sternenlicht, wobei hier die Strahlung aus einer Röntgenquelle in 120 Metern Abstand stammt. Die Messungen selbst fanden in einer daran angebauten 12 Meter langen Testkammer von 3,5 Metern Durchmesser statt. Im März 2021 sahen die HORUS-Teleskope zum erstem Mal Röntgenlicht. Während der Testkampagne von ca. 54 Stunden Dauer wurden 536 Einzelmessungen an den beiden Teleskopen durchgeführt, bei denen Photonenenergien und Einfallswinkel variiert wurden. Von einer empfindlichen CCD-Kamera, einem Prototyp der eROSITA-Satellitenkamera, wurden hierbei insgesamt 11.153.574 Röntgenphotonen individuell detektiert, analysiert und digital verarbeitet. Die beiden Weitwinkel-Röntgenteleskope haben eine Winkelauflösung von circa 4 Bogenminuten und eine Brennweite von rund zwei Metern.Poste
Eukaryotic Genomes Show Strong Evolutionary Conservation of k-mer Composition and Correlation Contributions between Introns and Intergenic Regions
No full textSeveral strongly conserved DNA sequence patterns in and between introns and intergenic regions (IIRs) consisting of short tandem repeats (STRs) with repeat lengths <3 bp have already been described in the kingdom of Animalia. In this work, we expanded the search and analysis of conserved DNA sequence patterns to a wider range of eukaryotic genomes. Our aims were to confirm the conservation of these patterns, to support the hypothesis on their functional constraints and/or the identification of unknown patterns. We pairwise compared genomic DNA sequences of genes, exons, CDS, introns and intergenic regions of 34 Embryophyta (land plants), 30 Protista and 29 Fungi using established k-mer-based (alignment-free) comparison methods. Additionally, the results were compared with values derived for Animalia in former studies. We confirmed strong correlations between the sequence structures of IIRs spanning over the entire domain of Eukaryotes. We found that the high correlations within introns, intergenic regions and between the two are a result of conserved abundancies of STRs with repeat units ≤2 bp (e.g., (AT)n). For some sequence patterns and their inverse complementary sequences, we found a violation of equal distribution on complementary DNA strands in a subset of genomes. Looking at mismatches within the identified STR patterns, we found specific preferences for certain nucleotides stable over all four phylogenetic kingdoms. We conclude that all of these conserved patterns between IIRs indicate a shared function of these sequence structures related to STRs
Designing a European Monetary Fund: What role for the IMF?
No full textThe so-called Troika, consisting of the EU-Commission, the European Central Bank (ECB) and the International Monetary Fund (IMF), was supposed to support the member states of the euro area which had been hit hard by a sovereign debt crisis. For that purpose, economic adjustment programs were drafted and monitored in order to prevent the break-up of the euro area and sovereign defaults. The cooperation of these institutions, which was born out of necessity, has been partly successful, but has also created persistent problems. With the further increase of public debt, especially in France and Italy, the danger of a renewed crisis in the euro area was growing. The European Stability Mechanism (ESM) together with the (strongly politicized) European Commission will replace the Troika in the future, following decisions of the EU Summit of December 2018. It shall play the role of a European Monetary Fund in the event of a crisis. The IMF, on the other side, will no longer play an active role in solving sovereign debt crises in the euro area. The current course is, however, inadequate to tackle the core problems of the euro zone and to avoid future crises, which are mainly structural in nature and due to escalating public debt and lack of international competitiveness of some member countries. The current Corona crisis will aggravate the institutional problems. It has led to a common European fiscal response ("Next Generation EU"). This rescue and recovery program will not be financed by ESM resources and will not be monitored by the ESM. One important novelty of this package is that it involves the issuance of substantial common European debt