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151.
二层信用策略下部分延期付款的库存模型 总被引:1,自引:0,他引:1
当前二层信用期相关文献考虑的都是零售商提供给其顾客相同的信用期,但现实中零售商往往会根据物品的种类不同提供给顾客不同的信用期.为研究此问题,建立了优化供货周期使零售商平均相关成本最小的库存模型,证明了最优供货周期的存在性,并给出实例加以说明. 相似文献
152.
We developed a novel microfluidic cell culture device in which magnetic beads repetitively collide with osteoblast cells, MC3T3‐E1, owing to attractive forces generated by pulsed electromagnetic fields and consequently the cells were physically stimulated by bead impacts. Our device consists of an on‐chip microelectromagnet and a microfluidic channel which were fabricated by a microelectromechanical system technique. The impact forces and stresses acting on a cell were numerically analyzed and experimentally generated with different sizes of bead (4.5, 7.6 and 8.4 μm) and at various pulse frequencies (60 Hz, 1 kHz and 1 MHz). Cells were synchronized at each specific phase of the cell cycle before stimulation in order to determine the most susceptible phase against bead impacts. The cells were stimulated with different sizes of bead at various pulse frequencies for 1 min at G1, S and G2 phases, respectively, and then counted immediately after one doubling time. The growth rate of cells was highly accelerated when they were stimulated with 4.5 μm beads at G1 phase and a pulse frequency of 1 MHz. Almost all of the cells were viable after stimulation, indicating that our cell stimulator did not cause any cellular damage and is suitable for use in new physical stimulus modalities. 相似文献
153.
We present a new algorithm for continuation of limit cycles of autonomous systems as a system parameter is varied. The algorithm
works in phase space with an ordered set of points on the limit cycle, along with spline interpolation. Currently popular
algorithms in bifurcation analysis packages compute time-domain approximations of limit cycles using either shooting or collocation.
The present approach seems useful for continuation near saddle homoclinic points, where it encounters a corner while time-domain
methods essentially encounter a discontinuity (a relatively short period of rapid variation). Other phase space-based algorithms
use rescaled arclength in place of time, but subsequently resemble the time-domain methods. Compared to these, we introduce
additional freedom through a variable stretching of arclength based on local curvature, through the use of an auxiliary index-based
variable. Several numerical examples are presented. Comparisons with results from the popular package, MATCONT, are favorable
close to saddle homoclinic points. 相似文献
154.
Hongtao Zhao 《Discrete Mathematics》2008,308(21):4931-4940
The existence spectrums for large sets of Hamilton cycle decompositions and Hamilton path decompositions are completed. Also, we show that the completion of large sets of directed Hamilton cycle decompositions and directed Hamilton path decompositions depends on the existence of certain special tuscan squares. Several conjectures about special tuscan squares are posed. 相似文献
155.
Jun Fujisawa 《Discrete Mathematics》2008,308(12):2382-2388
Let G be a (k+m)-connected graph and F be a linear forest in G such that |E(F)|=m and F has at most k-2 components of order 1, where k?2 and m?0. In this paper, we prove that if every independent set S of G with |S|=k+1 contains two vertices whose degree sum is at least d, then G has a cycle C of length at least min{d-m,|V(G)|} which contains all the vertices and edges of F. 相似文献
156.
We show that the conjectures by Matthews and Sumner (every 4-connected claw-free graph is Hamiltonian), by Thomassen (every 4-connected line graph is Hamiltonian) and by Fleischner (every cyclically 4-edge-connected cubic graph has either a 3-edge-coloring or a dominating cycle), which are known to be equivalent, are equivalent to the statement that every snark (i.e. a cyclically 4-edge-connected cubic graph of girth at least five that is not 3-edge-colorable) has a dominating cycle.We use a refinement of the contractibility technique which was introduced by Ryjá?ek and Schelp in 2003 as a common generalization and strengthening of the reduction techniques by Catlin and Veldman and of the closure concept introduced by Ryjá?ek in 1997. 相似文献
157.
158.
David Défossez 《Discrete Mathematics》2008,308(11):2265-2268
In this note we prove a long-standing conjecture of Sterboul [P. Duchet, Hypergraphs, in: R. Graham, M. Grötschel, L. Lovász (Eds.), Handbook of Combinatorics, 1995, pp. 381-432 (Chapter 7)], which states that a hypergraph is bicolorable provided it does not contain a specific kind of odd cycle. This is currently the strongest result of its kind, improving on results by Berge [Graphs and Hypergraphs, North-Holland, American Elsevier, Amsterdam, 1973] and Fournier and Las Vergnas [Une classe d’hypergraphes bichromatiques II, Discrete Math. 7 (1974) 99-106; A class of bichromatic hypergraphs, Ann. Discrete Math. 21, in: C. Berge, V. Chvátal (Eds.), Topics on Perfect Graphs, 1984, pp. 21-27]. 相似文献
159.
Péter Frankl 《Discrete Mathematics》2008,308(8):1415-1424
An r-uniform hypergraph is k-edge-hamiltonian iff it still contains a hamiltonian-chain after deleting any k edges of the hypergraph. What is the minimum number of edges in such a hypergraph? We give lower and upper bounds for this question for several values of r and k. 相似文献
160.
The prism over a graph G is the Cartesian product G □ K2 of G with the complete graph K2. If the prism over G is hamiltonian, we say that G is prism‐hamiltonian. We prove that triangulations of the plane, projective plane, torus, and Klein bottle are prism‐hamiltonian. We additionally show that every 4‐connected triangulation of a surface with sufficiently large representativity is prism‐hamiltonian, and that every 3‐connected planar bipartite graph is prism‐hamiltonian. © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 181–197, 2008 相似文献