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Ritter A.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Schmid M.,Institute for Rapid Product Development Inspire | Affolter S.,University of Applied science Buchs
Polymer Testing

Results obtained from two round robin test programmes are summarized and presented. Size exclusion chromatography (SEC) in both organic and aqueous phases was used to determine the average molar masses of six different polymers. The data were collected by Empa and evaluated using a robust statistical method concerning repeatability and reproducibility standard deviations. Refractive index (RI) and light scattering (LS) were utilized for signal detection. The results of the measurements indicate that the determination of molecular weights by LS is associated with a high degree of uncertainty compared to data measured by RI. For the SEC measurements in the aqueous phase, repeatability is good, unlike reproducibility. Comparisons of molar mass data determined by aqueous SEC in different laboratories are regarded as at least doubtful. © 2010 Elsevier Ltd. All rights reserved. Source

Standardized efficiency and capacity measurements of residential heat pumps deviate from real time performance due to several factors. While standardized measurements are performed at steady state operation, heat pumps in the field are usually capacity controlled using on-off cycling. In order to determine the difference between these operating modes, laboratory and field measurements were conducted to verify transient models of air-source and geothermal heat pumps. Heat pump performance was then simulated for several operating conditions typical for central European installations. It was shown that air-source heat pumps experience performance losses of only 1-2% for short cycling times. In the case of geothermal heat pumps, the recovery of the ground probe during the off time can lead to efficiency gains of up to 5%. Results of this study help to provide improved control strategies for heat pumps using on-off cycling as capacity control. They also support the conclusion that standardized measurements according to EN14511 accurately represent the efficiency of residential heat pumps both in continuous and in part load operation. © 2012 Elsevier Ltd and IIR. All rights reserved. Source

Keferstein C.P.,University of Applied science Buchs | Marxer M.,University of Applied science Buchs | Gotti R.,University of Applied science Buchs | Thalmann R.,Federal Office of Metrology METAS | And 3 more authors.
CIRP Annals - Manufacturing Technology

Reference spheres play an important role in the accuracy of multisensor coordinate measuring machine (CMM) applications. Nowadays there are a number of spheres specialized in the characteristics of different CMM probing systems. This paper presents a unique reference sphere which meets sometimes contradictory requirements of different measurement principles. With this sphere it is possible to qualify all probing systems widely used today. It is suitable for contacting and non-contacting probing systems such as vision systems, chromatic and laser probes and Computed Tomography. With this sphere, it is possible to achieve tactile probing errors of less than 1 μm. © 2012 CIRP. Source

Schwyn Thony S.,Evatec Ltd. | Wuthrich S.,Evatec Ltd. | Padrun M.,Evatec Ltd. | Burgunder M.,University of Applied science Buchs | And 5 more authors.
Optics InfoBase Conference Papers

Distribution shields are commonly used in e-beam evaporation systems to improve the thickness uniformity on the coated substrates. The shape of these shields is traditionally optimized in a number of correction loops. Simulation of the thickness distribution on the substrate holder and the optimization of the form of the distribution shield will cut the development time and can lead to smaller shields yielding reduced material consumption and higher throughput. © OSA 2013. Source

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