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61.
Let A?(??) denote the set of functions belonging to the disc algebra having real Fourier coefficients. We show that A?(??) has Bass and topological stable ranks equal to 2, which settles the conjecture made by Brett Wick in [18]. We also give a necessary and sufficient condition for reducibility in some real algebras of functions on symmetric domains with holes, which is a generalization of the main theorem in [18]. A sufficient topological condition on the symmetric open set ?? is given for the corresponding real algebra A?(??) to have Bass stable rank equal to 1 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
62.
The fracture behaviour of polycrystalline sintered and rolled tungsten rods was investigated from ?150°C to 950°C by means of three-point bending tests and electron microscopy where special attention was drawn to the influence of the microstructure. This thorough investigation demonstrates the positive impact of the crystallographic and grain shape anisotropy in tungsten. Specimens extracted along the rolling direction exhibit twice as high fracture toughnesses and a significantly reduced brittle-to-ductile transition temperature than the other two investigated orientations. Furthermore, these specimens show a change in their fracture mode from transgranular to intergranular fracture with crack deflection occurring around 270°C. In an in situ SEM fracture test, the origin of this crack deflection could be clarified. Finally, a fracture mechanics model is presented which predicts correctly the transition between the two fracture modes and which gives an energy criterion suitable to interpret experimental fracture results. 相似文献
63.
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65.
It is shown that the incomplete scalar meson nonets found by T?rnqvist [1] and T?rnqvist & Roos [2], employing a new version
of the Helsinki unitarised quark model, should in fact be complete, including an as yet unconfirmed light below 1 GeV (old ) and the established (1500). A detailed comparison is presented with the predictions of the Nijmegen unitarised meson model, in which two complete
scalar nonets show up below 1.5 GeV [3]. The reason for the flavour-nonet breaking found in [1,2] we argue to originate in
the use of coupling constants for the three-meson vertex which are not independent of flavour. Also some statements made in
[1] are critically reviewed.
Received: 17 February 1999 / Published online: 15 July 1999 相似文献
66.
E. H. Riesenfeld H. E. Wohlers Lockyer Beckmann und Rupp 《Fresenius' Journal of Analytical Chemistry》1907,46(2-3):167-169
Ohne Zusammenfassung 相似文献
67.
Anna Evans Anja Bieberle-Hütter Henning Galinski Jennifer L. M. Rupp Thomas Ryll Barbara Scherrer René Tölke Ludwig J. Gauckler 《Monatshefte für Chemie / Chemical Monthly》2009,140(9):975-983
Abstract Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable
electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode
(i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems
fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in
the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such
a micro-SOFC system approach seems feasible and offers a promising alternative to state-of-the-art batteries in portable electronics.
Graphical abstract Graphical Abstract text
相似文献
68.
F. Havermeyer C. Pruner R.A. Rupp D.W. Schubert E. Krätzig 《Applied physics. B, Lasers and optics》2001,72(2):201-205
The absorption spectra of poly(methyl methacrylate) (PMMA) doped with the photoinitiator 2,2-dimethoxy-2-phenylacetophenone
(DMPA) change under illumination with UV light. Time-resolved measurements of the kinetics of the absorption changes at 352 nm
prove the existence of a second light-induced reaction besides the expected light-induced decay of the photoinitiator. We
propose a model for this second process which is in good agreement with the observed experimental facts.
Received: 17 July 2000 / Published online: 5 October 2000 相似文献
69.
Summary: Organically modified montmorillonites (OMs), carrying alkyl chains, phenyl groups, or a combination of both, were prepared and compounded with polyethylene. The oxygen permeability coefficients and tensile properties of the nanocomposites were correlated to the exfoliation of the OMs. Partial exfoliation was achieved, although no intercalation was observed. Aromatic moieties attached to the clay surface led to a stronger interaction between the OM layers and less exfoliation.
70.
F. Kahmann J. Badura K. Lytze R. Blachnik R. A. Rupp 《Applied Physics A: Materials Science & Processing》1993,57(1):77-80
Holographic recording and erasure experiments in Cd13P4S22I2 crystals are reported. The refractive index change of the volume phase hologram is larger than n=1.5×10–4, whereas the static dielectric constant of this reversible storage medium is only about 10. These are rather unusual properties if compared with electrooptic KNbO3. 相似文献