The need for high-quality aspheres is rapidly growing, necessitating increased accuracy in their measurement. A reliable uncertainty assessment of asphere form measurement techniques is difficult due to their complexity. In order to explore the accuracy of current asphere form measurement techniques, an interlaboratory comparison was carried out in which four aspheres were measured by eight laboratories using tactile measurements, optical point measurements, and optical areal measurements. Altogether, 12 different devices were employed. The measurement results were analysed after subtracting the design topography and subsequently a best-fit sphere from the measurements. The surface reduced in this way was compared to a reference topography that was obtained by taking the pointwise median across the ensemble of reduced topographies on a Cartesian grid. The deviations of the reduced topographies from the reference topography were analysed in terms of several characteristics including peak-to-valley and root-mean-square deviations. Root-mean-square deviations of the reduced topographies from the reference topographies were found to be on the order of some tens of nanometres up to 89 nm, with most of the deviations being smaller than 20 nm. Our results give an indication of the accuracy that can currently be expected in form measurements of aspheres.
Future catalyst systems need to be highly efficient in a limited packaging space which normally leads to a design where the flow distribution in front of the catalyst is not perfectly uniform. Measurements on the flow test bench show that the implementation of perforated foils for the corrugated and flat foils has the capability to distribute the flow within the channels in radial direction so that the maximum of the given catalyst surface is of use, even under very poor uniformity indices. Therefore a remarkable reduction in back pressure is measured. Emission results demonstrate cold start improvement due to reduced heat capacity. The use of LS-structured (Longitudinal structured) corrugated foils creates high turbulence level within the single channels. The substrate lights-up earlier and the maximum conversion efficiency is reached much quicker. It can be shown that a 300 cpsi Metalit with 50 µm foil thickness creates the same efficiency during the European Driving cycle like a 600 cpsi with ultra thin wall, even at reduced catalyst volume. The combination of LS type corrugated foil with perforated flat foils further improve catalyst efficiency.
Ein stetig steigender Fundus an Informationen ist heute notwendig, um die immer komplexer werdende Technik heutiger Kraftfahrzeuge zu verstehen. Funktionen, Arbeitsweise, Komponenten und Systeme entwickeln sich rasant. In immer schnelleren Zyklen verbreitet sich aktuelles Wissen gerade aus Konferenzen, Tagungen und Symposien in die Fachwelt. Den raschen Zugriff auf diese Informationen bietet diese Reihe Proceedings, die sich zur Aufgabe gestellt hat, das zum Verständnis topaktueller Technik rund um das Automobil erforderliche spezielle Wissen in der Systematik aus Konferenzen und Tagungen zusammen zu Die Reihe wendet sich an Fahrzeug-und Motoreningenieure sowie Studierende, die aktuelles Fachwissen im Zusammenhang mit Fragestellungen ihres Arbeitsfeldes suchen. Professoren und Dozenten an Universitäten und Hochschulen mit Schwerpunkt Kraftfahrzeug-und Motorentechnik finden hier die Zusammenstellung von Veranstaltungen, die sie selber nicht besuchen konnten. Gutachtern, Forschern und Entwicklungsingenieuren in der Automobilund Zulieferindustrie sowie Dienstleistern können die Proceedings wertvolle Antworten auf topaktuelle Fragen geben. stellen und als Buch in Springer.com wie auch elektronisch in SpringerLink und Springer Professional bereit zu stellen.
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