Münster University of Applied Sciences

About: Münster University of Applied Sciences is a education organization based out in Münster, Germany. It is known for research contribution in the topics: Luminescence & Laser. The organization has 694 authors who have published 1067 publications receiving 12597 citations.

Self-Sustained Pulsations in an Intra-Cavity Pumped Thin-Disk Laser

Abstract: We investigate laser dynamics in an intra-cavity pumped Yb:YAG thin-disk laser. The intra-cavity pumped thin-disk laser comprises two Yb:YAG thin-disk lasers. A first, diode-pumped thin-disk laser pumps a second thin-disk laser. The disk of the second laser is placed inside the resonator of the first laser and serves as its useful loss. The first laser is restricted to a wavelength of 1030 nm or shorter by a custom made mirror. This mirror has a high reflectivity at 1030 nm and a reduced reflectivity at 1050 nm. The second laser has its own V-shaped resonator that is composed of the intra-cavity pumped disk, a HR mirror, and an output coupler. The setup is shown in figure 1 on the left.

Bottom-up organized recycling networks as strategies for corporate sustainability

Abstract: Sustainability has become an urgent requirement and challenge for society as well as for decision makers in policy and economy, considering the limited resources and growing consumption. Sustainability is interpreted in ecological, economic and social dimensions. Ecologically, non-renewable resources must not be disposed anymore but regained in product and material cycles. Managing material cycles requires the coordination of companies along the end-of-life processing chain. However, a central coordinating institution may not appear. Developing and supporting bottom-up structures, which integrate recycling companies on a voluntary basis seems promising. This paper describes an approach of how to organize bottom-up recycling networks. Considering different goals in recycling, like material value or focus on special materials, technological strategies for WEEE-waste are evaluated and matched with actual material prices. Companies are able to compare their course of action with theoretical options in order to improve competitiveness.

Vibration and shock testing of a 50 mm aperture unimorph deformable mirror

Abstract: We present our latest results on a refined unimorph deformable mirror which was developed in the frame of the ESA GSTP activity ”Enabling Technologies for Piezo-Based Deformable Mirrors in Active Optics Correction Chains”. The identified baseline concept with the soft piezoceramic material PIC151 successfully sustained all vibration requirements (17.8 gRMS random and 20 g sine) and shock testing (300 g SRS). We cover the mirror design development which reduces the stress in the brittle piezo-ceramic by 90% compared to the design from a former GSTP activity. We briefly address the optical characterization of the deformable mirror, namely the achieved Zernike amplitudes as well as the unpowered surface deformation (1.7 μm) and active flattening (12.3 nmRMS). The mirror produces low-order Zernike modes with a stroke of several tens of micrometer over a correction aperture of 50 mm, which makes the mirror a versatile tool for space telescopes.

Improving classifier performance by knowledge-driven data preparation

Abstract: Classification is a widely used technique in data mining. Thereby achieving a reasonable classifier performance is an increasingly important goal. This paper aims to empirically show how classifier performance can be improved by knowledge-driven data preparation using business, data and methodological know-how. To point out the variety of knowledge-driven approaches, we firstly introduce an advanced framework that breaks down the data preparation phase to four hierarchy levels within the CRISP-DM process model. The first 3 levels reflect methodological knowledge; the last level clarifies the use of business and data know-how. Furthermore, we present insights from a case study to show the effect of variable derivation as a subtask of data preparation. The impact of 9 derivation approaches and 4 combinations of them on classifier performance is assessed on a real world dataset using decision trees and gains charts as performance measure. The results indicate that our approach improves the classifier performance.

Analysis of the Micro-Processes Occurring on Different Wear Protection Layers under Abrasive and Impact Wear using Laser Scanning Microscopy

Abstract: Neben den gezielt herbeigeführten technischen Verschleißvorgängen sowie den auf tribologischen Prozessen basierenden Fertigungsverfahren ist Verschleiß in der industriellen Produktion überwiegend unerwünscht [1]. Er birgt Gefahren für Mensch und Umwelt und führt zu hohen monetären Verlusten. Das Ausmaß des jährlich entstehenden wirtschaftlichen Received: April 18, 2018 Accepted: May 23, 2018 Translation: E. Engert