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.

Novel unimorph deformable mirror for space applications

Abstract: We have developed a new type of unimorph deformable mirror, designed to correct for low-order Zernike modes. The mirror has a clear optical aperture of 50 mm combined with large peak-to-valley Zernike amplitudes of up to 35 μm. Newly developed fabrication processes allow the use of prefabricated super-polished and coated glass substrates. The mirror's unique features suggest the use in several stronomical applications like the precompensation of atmospheric aberrations seen by laser beacons and the use in woofer-tweeter systems. Additionally, the design enables an efficient correction of the inevitable wavefront error imposed by the floppy structure of primary mirrors in future large space-based telescopes. We have modeled the mirror by using analytical as well as finite element models. We will present design, key features and manufacturing steps of the deformable mirror.

The effectiveness and impact of action learning on business graduates’ professional practice

Abstract: The organizational world has long recognized action learning (AL) as an invaluable tool for managerial development. However, AL’s popularity among organizations did not translate into its adoption ...

A development roadmap for critical technologies needed for TALC: a deployable 20m annular space telescope

Abstract: Astronomy is driven by the quest for higher sensitivity and improved angular resolution in order to detect fainter or smaller objects. The far-infrared to submillimeter domain is a unique probe of the cold and obscured Universe, harboring for instance the precious signatures of key elements such as water. Space observations are mandatory given the blocking effect of our atmosphere. However the methods we have relied on so far to develop increasingly larger telescopes are now reaching a hard limit, with the JWST illustrating this in more than one way (e.g. it will be launched by one of the most powerful rocket, it requires the largest existing facility on Earth to be qualified). With the Thinned Aperture Light Collector (TALC) project, a concept of a deployable 20 m annular telescope, we propose to break out of this deadlock by developing novel technologies for space telescopes, which are disruptive in three aspects: • An innovative deployable mirror whose topology, based on stacking rather than folding, leads to an optimum ratio of collecting area over volume, and creates a telescope with an eight times larger collecting area and three times higher angular resolution compared to JWST from the same pre-deployed volume; • An ultra-light weight segmented primary mirror, based on electrodeposited Nickel, Composite and Honeycomb stacks, built with a replica process to control costs and mitigate the industrial risks; • An active optics control layer based on piezo-electric layers incorporated into the mirror rear shell allowing control of the shape by internal stress rather than by reaction on a structure. We present in this paper the roadmap we have built to bring these three disruptive technologies to technology readiness level 3. We will achieve this goal through design and realization of representative elements: segments of mirrors for optical quality verification, active optics implemented on representative mirror stacks to characterize the shape correction capabilities, and mechanical models for validation of the deployment concept. Accompanying these developments, a strong system activity will ensure that the ultimate goal of having an integrated system can be met, especially in terms of (a) scalability toward a larger structure, and (b) verification philosophy.

CLOWT: A Multifunctional Test Facility for the Investigation of Organic Vapor Flows

Abstract: Organic vapor flows are met in a wide range of technical applications (e.g., energy conversion, chemical processes, and refrigeration). Typically, organic fluids contain complex molecules, and their thermodynamic behavior deviates significantly from the ideal or perfect gas laws. The applicability of scaling laws to organic vapor flows is very limited, and there is a need for detailed experimental investigations under relevant process conditions. Furthermore, such investigations can provide a validation basis for the simulations performed with Computational Fluid Dynamics (CFD) tools. On the other hand, there exists a serious lack in experimental organic vapor flow test facilities. In this contribution, a novel Closed Loop Organic vapor Wind Tunnel (CLOWT) is presented. The concept of CLOWT is based on a closed-loop continuously running wind tunnel cycle. Its main components are a blower, a diffuser, a settling chamber, a contraction zone, a test section module, and a return, including a throttle valve and a mass flow meter. The test facility CLOWT applies the modular design approach which enables analysis of various flow configurations and components like blowers, small axial test turbines, nozzle flows or transonic flows past test objects. Thanks to an auxiliary heating system, organic vapor flows can be investigated at elevated pressure and temperature levels. The operation of CLOWT is based on closed gas turbine cycle control methods (e.g., inventory control). In addition to the general test facility concept, the paper gives a detailed discussion of the CLOWT special design features.

Korrosionsmonitoring von Stahlbetonbauwerken - Das DGZfP-Merkblatt B12

Abstract: Korrosionsmonitoring von Stahl- oder Spannbetonbauwerken hat in den vergangenen Jahren als Erganzung zur herkommlichen Bauwerksuntersuchung deutlich an Relevanz gewonnen. Einsatzgebiete sind z. B. Bauteile, die nach Fertigstellung nicht mehr zuganglich sind oder an denen aufgrund vorhandener Beschichtungen keine Potentialfeldmessungen durchgefuhrt werden konnen. Weiterhin kann Korrosionsmonitoring auch fur die Uberwachung des Korrosionsfortschritts an korrodierenden Systemen z. B. zum Nachweis des Instandsetzungserfolgs bei Anwendung des Prinzips W-Cl gemas Instandsetzungsrichtlinie des DAfStb oder zum Funktionsnachweis bei KKS-Installationen nach DIN EN ISO 12696 eingesetzt werden. Trotz zunehmender Bedeutung Existieren fur das Korrosionsmonitoring bis dato keine Richtlinien oder Handlungsempfehlungen. Diese Lucke soll das Merkblatt B12 „Korrosionsmonitoring von Stahl- und Spannbetonbauwerken“ der Deutschen Gesellschaft fur zerstorungsfreie Prufung DGZfP fullen, das im Fruhjahr 2018 veroffentlicht wurde. In diesem Beitrag werden das Merkblatt B12 vorgestellt, die grundlegenden Messprinzipien erlautert und anhand von Anwendungsbeispielen das Potenzial von Korrosionsmonitoring bei Neubau- und Bestandsobjekten illustriert.