Arbeitsbericht Nr. 2014-02, April 2014

In diesem Beitrag wird die Erstellung eines Metamodells zur Entwicklung einer Kollaborationsplattform für die Druckbranche dargestellt. Die beschriebenen Arbeiten und Erkenntnisse sind im Rahmen des vom Bundesministerium für Wirtschaft und Technologie geförderten Forschungsprojekts PRINT-IT (Förderkennzeichen KF2987001ED2) entstanden. Ziel des Projekts ist die Entwicklung einer Kollaborationsplattform zur auftragsspezifischen unternehmensübergreifenden Leistungserstellung für kleine und mittelständische Unternehmen der Druckbranche. Das erstellte Metamodell dient dazu, die für die Kollaborationsplattform relevanten Objekte und Beziehungen so zu strukturieren, zu visualisieren und zu beschreiben, dass die Kommunikation über bestimmte Sachverhalte vereinfacht wird und damit Planung, Entwicklung, Anwendung und Weiterentwicklung der Kollaborationsplattform unterstützt werden. Eine besondere Eigenschaft des Metamodells ist, dass neben der Konfiguration von Dienstleistungen und Produkten durch Kunden auch die Verknüpfung von Dienstleistungs- und Produkteigenschaften mit Produktionsprozessen und Ressourcen von Anbietern berücksichtigt werden

The fracture behavior of Cr2AlC coatings

The erosion - and self-healing - behavior of Cr2AlC MAX phase coatings has been investigated [1]. It is well known that Cr2AlC coatings can be deposited at temperatures of around 450 °C [2], which is significantly lower than for other MAX phase systems, which often require growth temperatures around 900 °C [3]. To further explore the applicability of the Cr2AlC system in harsh environments, it is necessary to determine its mechanical response. Recent advances in micromechanical testing allow investigating the mechanical properties of hard coatings, especially the fracture behavior, which is of particular interest for several thin film applications. Furthermore, it is possible to deposit the Cr2AlC system with different microstructures, e.g. nanocrystalline or amorphous [2]. Preliminary results revealed a fracture toughness of ~2 MPam1/2 for a coating with columnar morphology. In this investigation, the effect of morphology and microstructure on the fracture toughness of Cr2AlC coatings will be presented. References [1] D. Eichner, A. Schlieter, C. Leyens, L. Shang, S. Shayestehaminzadeh, J.M. Schneider, Solid particle erosion behavior of nanolaminated Cr2AlC films, Wear. 402–403 (2018) 187–195. doi:10.1016/j.wear.2018.02.014. [2] C. Walter, D.P. Sigumonrong, T. El-Raghy, J.M. Schneider, Towards large area deposition of Cr2AlC on steel, Thin Solid Films. 515 (2006) 389–393. doi:10.1016/j.tsf.2005.12.219. [3] P. Eklund, M. Beckers, U. Jansson, H. Högberg, L. Hultman, The Mn+1AXn phases: Materials science and thin-film processing, Thin Solid Films. 518 (2010) 1851–1878. doi:10.1016/j.tsf.2009.07.184

Further X-ray detections of Herbig stars

The interpretation of X-ray detections from Herbig Ae/Be stars is disputed as it is not clear if these intermediate-mass pre-main sequence stars are able to drive a dynamo and ensuing phenomena of magnetic activity. Alternative X-ray production mechanisms, related to stellar winds, star-disk magnetospheres, or unresolved late-type T Tauri star companions have been proposed. In a series of papers we have been investigating high-resolution X-ray Chandra images of Herbig Ae/Be and main-sequence B-type stars to test the T Tauri hypothesis by spatially resolving known visual companions from the primaries. Here we report on six as yet unpublished Chandra exposures from our X-ray survey of Herbig stars. The target list comprises six Herbig stars with known cool companions, and three further A/B-type stars that are serendipitously in the Chandra field-of-view. In this sample we record a detection rate of 100%, i.e. all A/B-type stars display X-ray emission at levels of log(L_x/L_bol) ~ -5...-7. The analysis of hardness ratios confirms that HAeBe's have hotter and/or more absorbed X-ray emitting plasma than more evolved B-type stars. Radiative winds are ruled out as exclusive emission mechanism on basis of the high X-ray temperatures. Confirming earlier results, the X-ray properties of Herbig Ae/Be stars are not vastly different from those of their late-type companion stars (if such are known). The diagnostics provided by the presently available data leave open if the hard X-ray emission of Herbig stars is due to young age or indicative of further coronally active low-mass companion stars. In the latter case, our detection statistics imply a high fraction of higher-order multiple systems among Herbig stars.Comment: 11 pages; accepted for publication in Astronomy & Astrophysics Main Journa

A biologically inspired navigation concept based on the Landmark-Tree map for efficient long-distance robot navigation

Map-based navigation is a crucial task for any mobile robot. Usually, in an unknown environment, this problem is addressed by applying Simultaneous Localization and Mapping based on metric grid-maps. However, such maps are in general rather computational expensive and do not scale well. Insects are able to cover large distances and reliably find back to their nests, although they are quite limited in their resources. Inspired by theories on insect navigation, we developed a data structure which is highly scalable and efficiently adapts to the available memory during run-time. Positions in space are memorized as snapshots, which are unique configurations of landmarks. Unlike conventional snapshot or visual map approaches, we do not simply store the landmarks as a set, but we arrange them in a tree-like structure according to the relevance of their information. The resulting navigation solely relies on the direction measurements of arbitrary landmarks. In this work, we present the concept of the Landmark-Tree (LT) map and apply it to a mobile platform equipped with an omnidirectional camera. We verify the reliability and robustness of the LT-map concept in simulations as well as by experiments with the robotic platform

The Role of Pseudomonas aeruginosa ExoY in an Acute Mouse Lung Infection Model

The effector protein Exotoxin Y (ExoY) produced by Pseudomonas aeruginosa is injected via the type III secretion system (T3SS) into host cells. ExoY acts as nucleotidyl cyclase promoting the intracellular accumulation of cyclic nucleotides. To what extent nucleotidyl cyclase activity contributes to the pathogenicity of ExoY and which mechanisms participate in the manifestation of lung infection is still unclear. Here, we used an acute airway infection model in mice to address the role of ExoY in lung infection. In infected lungs, a dose-dependent phenotype of infection with bacteria-expressing ExoY was mirrored by haemorrhage, formation of interstitial oedema in alveolar septa, and infiltration of the perivascular space with erythrocytes and neutrophilic granulocytes. Analyses of the infection process on the cellular and organismal level comparing infections with Pseudomonas aeruginosa mutants expressing either nucleotidyl cyclase-active or -inactive ExoY revealed differential cytokine secretion, increased prevalence of apoptosis, and a break of lung barrier integrity in mice infected with cyclase-active ExoY. Notably, of all measured cyclic nucleotides, only the increase of cyclic UMP in infected mouse lungs coincides temporally with the observed early pathologic changes. In summary, our results suggest that the nucleotidyl cyclase activity of ExoY can contribute to P. aeruginosa acute pathogenicity

Mapping the material distribution of a complex structure in an electron beam

The simulation and analysis of High Energy Physics experiments require a realisticsimulation of the detector material and its distribution. The challenge is to describe all activeand passive parts of large scale detectors like ATLAS in terms of their size, position and materialcomposition. The common method for estimating the radiation length by weighing individualcomponents, adding up their contributions and averaging the resulting material distribution overextended structures provides a good general estimate, but can deviate significantly from the materialactually present.A method has been developed to assess its material distribution with high spatial resolutionusing the reconstructed scattering angles and hit positions of high energy electron tracks traversingan object under investigation. The study presented here shows measurements for an extendedstructure with a highly inhomogeneous material distribution. The structure under investigation isan End-of-Substructure-card prototype designed for the ATLAS Inner Tracker strip tracker — aPCB populated with components of a large range of material budgets and sizes.The measurements presented here summarise requirements for data samples and reconstructedelectron tracks for reliable image reconstruction of large scale, inhomogeneous samples, choicesof pixel sizes compared to the size of features under investigation as well as a bremsstrahlungcorrection for high material densities and thicknesses