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991.
992.
An M[X]/G/1 retrial G-queue with single vacation and unreliable server is investigated in this paper. Arrivals of positive customers form a compound Poisson process, and positive customers receive service immediately if the server is free upon their arrivals; Otherwise, they may enter a retrial orbit and try their luck after a random time interval. The arrivals of negative customers form a Poisson process. Negative customers not only remove the customer being in service, but also make the server under repair. The server leaves for a single vacation as soon as the system empties. In this paper, we analyze the ergodical condition of this model. By applying the supplementary variables method, we obtain the steady-state solutions for both queueing measures and reliability quantities. 相似文献
993.
SERIES PERTURBATIONS APPROXIMATE SOLUTIONS TO N-S EQUATIONS AND MODIFICATION TO ASYMPTOTIC EXPANSION MATCHED METHOD 总被引:1,自引:0,他引:1
IntroductionTheasymptoticexpansionmatchedmethodwasdevelopedonthebasisofPlandtl’sBoundaryLayersTheory[1- 3].In 1 960’slater,thevalidmatchedprincipleswereadvancedbyVanDykeandKaplun[4 ,5 ],respectively .Buttheapplicablerangeofthemethodwasrestrictedbythedifficultyth… 相似文献
994.
995.
In this article, we try to understand which generically complete intersection monomial ideals with fixed radical are Cohen–Macaulay. We are able to give a complete characterization for a special class of simplicial complexes, namely the Cohen–Macaulay complexes without cycles in codimension 1. Moreover, we give sufficient conditions when the square-free monomial ideal has minimal multiplicity. 相似文献
996.
Let W → 𝔸 2 be the universal Weierstrass family of cubic curves over ?. For each N ≥ 2, we construct surfaces parameterizing the three standard kinds of level N structures on the smooth fibers of W. We then complete these surfaces to finite covers of 𝔸 2. Since W → 𝔸 2 is the versal deformation space of a cusp singularity, these surfaces convey information about the level structure on any family of curves of genus g degenerating to a cuspidal curve. Our goal in this note is to determine for which values of N these surfaces are smooth over (0, 0). From a topological perspective, the results determine the homeomorphism type of certain branched covers of S 3 with monodromy in SL2 (?/N). 相似文献
997.
Let (R, m) be a two-dimensional regular local ring and let A be a finitely generated torsion-free R-module. If A is a complete module, then Dan Katz and Vijay Kodiyalam show A satisfies five conditions. They ask whether these five conditions are equivalent without assuming A to be complete. In a previous paper we determined all implications among these five conditions with one exception. In this paper, with an additional hypothesis on the units of R, we resolve the remaining case. 相似文献
998.
R. Alkofer C. S. Fischer R. Williams 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):53-60
The U
A(1) problem of QCD is inevitably tied to the infrared behaviour of quarks and gluons with its most visible effect being the
-mass. A dimensional argument of Kogut and Susskind showed that the mixing of the pseudoscalar flavour-singlet mesons with
gluons can provide a screening of the Goldstone pole in this channel if the full quark-quark interaction is strongly infrared
singular as ∼ 1/k
4 . We investigate this idea using previously obtained results for the Landau gauge ghost and gluon propagator, together with
recent determinations for the singular behaviour of the quark-gluon vertex. We find that, even with an infrared vanishing
gluon propagator, the singular structure of the quark-gluon vertex for certain kinematics is apposite for yielding a non-zero
screening mass. 相似文献
999.
H. Y. Li X. Zhao S. Gao X. Y. Xu H. Zhou S. L. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):1-6
By using the closed-orbit theory including the effect of Coulomb scattering together with an electrical image potential approach,
the recurrence spectra and the dynamical behaviours of the Rydberg hydrogen atom near a metal surface are presented. Theoretical
analysis and numerical simulation reveal that the impacts of the image potential contributing to the recurrence spectrum are
qualitatively analogous to that of the parallel electrical and magnetic fields on the Rydberg atom. The recurrence spectra
are computed for a few selected scaled energies and the results demonstrate that the scaled energy dominates the dynamical
properties of system. With the increase of the scaled energy e from small to large, the whole trend of spectral structure
is from simple to complex,and then simple. 相似文献
1000.
Essential properties of halo nuclei can be described in terms of a few low-energy constants. For neutron halo nuclei, analytical
results can be found for wave functions and electromagnetic transition matrix elements in simple but well-adapted models.
These wave functions can be used to study nuclear reactions; an especially simple and instructive example is Coulomb excitation.
A systematic expansion in terms of small parameters can be given. We present scaling laws for excitation amplitudes and cross-sections.
The results can be used to analyze experiments like 11Be Coulomb excitation. They also serve as benchmark tests for more involved reaction theories. 相似文献