Cosmological perturbations and short distance physics from Noncommutative Geometry

We investigate the possible effects on the evolution of perturbations in the inflationary epoch due to short distance physics. We introduce a suitable non local action for the inflaton field, suggested by Noncommutative Geometry, and obtained by adopting a generalized star product on a Friedmann-Robertson-Walker background. In particular, we study how the presence of a length scale where spacetime becomes noncommutative affects the gaussianity and isotropy properties of fluctuations, and the corresponding effects on the Cosmic Microwave Background spectrum.Comment: Published version, 16 page

Transmission Problems for the Navier–Stokes and Darcy–Forchheimer–Brinkman Systems in Lipschitz Domains on Compact Riemannian Manifolds

M. Kohr acknowledges the support of the Grant PN-II-ID-PCE-2011-3-0994 of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI. The research has been also partially supported by the Grant EP/M013545/1: “Mathematical Analysis of Boundary-Domain Integral Equations for Nonlinear PDEs” from the EPSRC, UK

Grundlegende vorbereitende Untersuchungen fluessigstickstoffgekuehlter elektrischer Antriebssysteme mit Hochtemperatur-Supraleitern (HTSL) (Vorstudie) Abschlussbericht

The discovery of new ceramic HTC materials in 1986/87 with critical temperatures above 77 K inaugurates additional applications in the field of small electrical machines. Therefore the present research project deals with preparing investigations first on liquid nitrogen cooled electrical machines and machine components, that can be extrapolated to using HTC - wound motors. It is intended to investigate 77 K properties of cheap standard materials of the electrical machine construction and to calculate performance characteristics of liquid nitrogen cooled polyphase machines. With these results material demands on HTC wires will be detected. A systematic theoretical and metrological study of materials and machines results in the following summary of the present research project: High quality standard materials of the usual 300 K temperature range can be used at 77 K, on principle there are partly worse material properties (e.g. iron losses). Nevertheless small electrical machines of frame size 250 W have an increase in output coefficient of two to four times and at the same time clearly raised efficiencies compared to the 300 K type. Application advantages of small cryo or HTC machines clearly exceed principal disadvantages, so that cryo machines can be used profitably alreaedy now. After having developed a suitable HTC wire a favourably HTC machine performance will be achieved. (orig.)SIGLEAvailable from TIB Hannover: F96B1380+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Neuartige Energie-Sparpotentiale elektrischer Antriebssysteme

SIGLEAvailable from TIB Hannover: DtF QN1(83,40) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

10 kW Hochtemperatur-Supraleitender (HTSL)-Motor. Design und Berechnung technischer Parameter fuer HTSL-Motoren Forschungsabschlussbericht

The report covers theoretical and experimental investigations on the following different kinds of High-Temperature-Superconducting (HTS) Electrical Machines: HTS hysteresis motor, HTS reluctance motor, HTS permanent magnet excited motor. The basis for calculation and design of HTS motors has been developed and afterwards proved by experiments. Furthermore, new models of HTS motors have been developed and tested. In comparison to conventional machines the HTS machines show a better density of power and a higher output power referred to their mass at a higher power factor and a much more better efficiency. By these results the aim of the research project, developing and investigating a 10 kW HTS motor being competitive and suitable to manufacturing, has been obtained and even extended by doubling the output power. (orig.)Im Bericht sind die theoretischen und experimentellen Untersuchungen der hochtemperatursupraleitenden (HTS) elektrischen Maschinen verschiedenen Bauarten (HTS-Hysteresemotor, HTS-Reluktanzmotor, HTS-permanenterregter Motor) dargestellt. Die Grundlagen fuer die Berechnung von hochtemperatursupraleitenden Motoren sind entwickelt und experimentell bestaetigt worden. Es sind neue Ausfuehrungen von HTS-Motoren entwickelt und experimentell untersucht worden. Die HTS-Maschinen weisen im Vergleich mit konventionellen Maschinen eine bessere Leistungsdichte und eine hoehere massenbezogene Abgabeleistung bei besserem Leistungsfkator und wesentlich besserem Wirkungsgrad auf. Durch diese Ergebnisse ist das Ziel des Forschungsprojekts einen konkurrenzfaehigen und fertigungsfreundlichen 10 kW HTS Motor zu entwickeln und zu untersuchen, erreicht und mit einer doppelten Abgabeleistung ueberschritten worden. (orig.)Available from TIB Hannover: F00B1117+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Texturierte YBCO-Hochtemperatur-Supraleiter. Untersuchung zur Abschaetzung der Moeglichkeiten von schmelztexturierten YBCO-Hochtemperatursupraleitern in energietechnischen Anwendungen

The potential uses of melt textured, high-temperature superconductors in energy technology are shown in great detail, with emphasis on applications for magnetic bearings, magnetic field shielding, and permanent magnets. The study is an up-to-date survey of potential applications, of interest to R+D labs as well as potential users in science and technology. (orig.)Die vorliegende Untersuchung behandelt das energietechnische Anwendungspotential von schmelztexturierten Hochtemperatur-Supraleitern insbesondere in den Gebieten der magnetischen Lagerung, der Magnetfeldabschirmung und der Permanentmagnete. Sie soll damit potentiellen Anwendern, Entwicklern und weiteren Interessenten einen aktuellen Ueberblick ueber den derzeitigen Stand vermitteln. (orig.)SIGLEAvailable from TIB Hannover: F95B1897+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman