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861.
In 1979, Papadimitriou and Yannakakis gave a polynomial time algorithm for the scheduling of jobs requiring unit completion times when the precedence constraints form an interval order. The authors solve here the corresponding problem, for preemptive scheduling (a job can be interrupted to work on more important tasks, and completed at a later time, subject to the usual scheduling constraints.) The m-machine preemptive scheduling problem is shown to have a polynomial algorithm, for both unit time and variable execution times as well, when the precedence constraints are given by an interval order. 相似文献
862.
863.
Ian W. Roxburgh 《General Relativity and Gravitation》1991,23(9):1071-1080
In Finsler spaces the intervalds=F(x
i
,dx
i
) is an arbitrary function of the coordinatesx
i
and coordinate incrementsdx
i
withF homogeneous of degree one in thedx
i
. It is shown that for Riemannian spacesds
R
2=g
ij
dx
i
dx
i
which admit a non trivial covariantly constant tensorH
i
.(x
k
) there is an associated Finsler space with the same geodesic structure. The subset of such Finsler spaces withH
i
.(x
k
) a vector or second rank decomposable tensor is determined. 相似文献
864.
We consider a specific continuous-spin Gibbs distribution μt=0 for a double-well potential that allows for ferromagnetic ordering. We study the time-evolution of this initial measure under
independent diffusions.
For `high temperature' initial measures we prove that the time-evoved measure μt is Gibbsian for all t. For `low temperature' initial measures we prove that μt stays Gibbsian for small enough times t, but loses its Gibbsian character for large enough t. In contrast to the analogous situation for discrete-spin Gibbs measures, there is no recovery of the Gibbs property for
large t in the presence of a non-vanishing external magnetic field. All of our results hold for any dimension d≥2. This example suggests more generally that time-evolved continuous-spin models tend to be non-Gibbsian more easily than
their discrete-spin counterparts.
Research carried out at EURANDOM and supported by Deutsche Forschungsgemeinschaft 相似文献
865.
Don Hadwin K. J. Harrison J. A. Ward 《Proceedings of the American Mathematical Society》2006,134(8):2169-2178
We obtain necessary and sufficient conditions for the existence and the uniqueness of rank-one completions of a partial matrix, and we verify a conjecture of Hadwin and Larson concerning the nature of completely rank-nonincreasing linear functionals defined on pattern subspaces.
866.
V. M. Kuz’kin O. Yu. Lavrova S. A. Pereselkov V. G. Petnikov K. D. Sabinin 《Acoustical Physics》2006,52(1):65-76
The space-time spectral characteristics of the field of background internal waves (IW) are obtained for two oceanic shelf
regions (the Atlantic shelf of the United States and the Kamchatka shelf) and analyzed. Within the framework of a numerical
experiment, it is shown that the observed anisotropy of the IW field may considerably affect the low-frequency sound fluctuations
in the aforementioned regions and, in particular, may change the interference invariant of the sound field. 相似文献
867.
R. Euler B. Fricke T. Morović W. -D. Sepp A. Rosén 《Zeitschrift für Physik A Hadrons and Nuclei》1980,297(2):101-104
Total energy SCF calculations were performed for noble gas difluorides in a relativistic procedure and compared with analogous non-relativistic calculations. The discrete variational method with numerical basis functions was used. Rather smooth potential energy curves could be obtained. The theoretical Kr-F and Xe-F bond distances were calculated to be 3.5 a.u. and 3.6 a.u. which should be compared with the experimental values of 3.54 a.u. and 3.7 a.u. Although the dissociation energies are off by a factor of about five it was found that ArF2 may be a stable molecule. Theoretical ionization energies for the outer levels reproduce the experimental values for KrF2 and XeF2 to within 2 eV. 相似文献
868.
869.
W. Rattanasakulthong C. Sirisathitkul 《Applied Physics A: Materials Science & Processing》2006,83(1):77-81
Thermal and magnetotransport properties of mechanically alloyed Co30Cu70 powders of three different milling times are studied. Both milling and annealing bring about oxidation of the samples. The powders show exothermic behaviors corresponding to the lattice-recovery process. Different milling times and annealing temperatures give rise to different exothermic peaks because of oxidation and the cluster distribution. At room temperature, the compressed powders show, on average, up to 11% giant magnetoresistance (GMR) under 10 kOe with sharp switching. The results may be understood in terms of spin-dependent scattering across Co/oxide/Cu interfaces. Annealing reduces the resistance but does not promote the GMR. By annealing at 400 °C, the GMR is entirely suppressed as the magnetic content is largely replaced by oxides. PACS 72.15.Eb; 75.47.De; 75.47.Np 相似文献
870.