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31.
Friedrich Otto 《Semigroup Forum》2007,75(3):520-535
We consider the problem of deciding Green's relations for various types of finitely presented automatic monoids.
We establish some decidability as well as some undecidability results. 相似文献
32.
Karl Sigman 《Operations Research Letters》2007,35(5):581-583
In Mandelbaum and Yechiali [The conditional residual service time in the M/G/1 queue, http://www.math.tau.ac.il/∼uriy/publications (No. 30a), 1979] and in Fakinos [The expected remaining service time in a single-server queue, Oper. Res. 30 (1982) 1014-1018] a simple formula is derived for the (stationary) expected remaining service time in a M/G/1 queue, conditional on the number of customers in the system. We give a short new proof of the formula using Rate Conservation Law, and generalize to handle higher moments. 相似文献
33.
34.
Karl Strambach C. G. Bartolone 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》1989,59(1):93-99
This research was supported by M.P.I. (R.S. 40%). 相似文献
35.
36.
Th. Friedrich I. Kath A. Moroianu U. Semmelmann 《Journal of Geometry and Physics》1997,23(3-4):259-286
A nearly parallel G2-structure on a seven-dimensional Riemannian manifold is equivalent to a spin structure with a Killing spinor. We prove general results about the automorphism group of such structures and we construct new examples. We classify all nearly parallel G2-manifolds with large symmetry group and in particular all homogeneous nearly parallel G2-structures. 相似文献
37.
38.
The ternary system CsCl?NaCl?LaCl3 was investigated by means of differential thermal analysis and X-ray powder diffraction analysis. There exists one congruently melting compound, Cs2NaLaCl6, crystallizing with the cubic elpasolite structure. No quasi-binary section exists for the whole system, however three binaries range from the ternary compound Cs2NaLaCl6 to NaCl, CsLa2Cl7 and Cs3LaCl6 resp., dividing the system in three areas of composition: one triangle, Cs3LaCl6?Cs2NaLaCl6?CsLa2Cl7, containing additionally a compound Cs2LaCl5 below 510°C, and the two areas CsCl?NaCl?Cs2NaLaCl6?Cs3LaCl6 and Cs2NaLaCl6?NaCl?LaCl3?CsLa2Cl7, containing a mixed crystal range between LaCl3 and Na3La5Cl18. These areas could be further divided in five triangles, so that the whole system contains six Alkemade triangles. 相似文献
39.
Renate Naumann Christine Alexander-Weber Friedrich G. K. Bauche 《Analytical and bioanalytical chemistry》1994,350(3):119-121
Thermogravimetric and X-ray powder diffraction analyses revealed that the pH reference material sodium tetraborate decahydrate (“borax”) is not a stable substance but, loosing some of its water of crystallization, transforms slowly into the pentahydrate. The connected pH changes of the solutions are opposite to and larger than, those expected according to the dilution value of the decahydrate as shown by differential potentiometric measurements. The transformation rate depends on the storing time in the closed original container, the time of and after the first exposure of the material to the atmosphere, the frequency of and the relative humidity during subsequent exposures, and the temperature. The transformation reaction is not understood in detail. However, the experiments showed that sodium tetraborate decahydrate is a reliable pH reference material, whose pH is constant within ΔpH=±0.005 within at least two years after preparation, even if occasionally exposed to the atmosphere. Further work will show whether this time limit can be somewhat extended. 相似文献
40.