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151.
M. Abreu 《Discrete Mathematics》2008,308(10):1810-1815
Murty [A generalization of the Hoffman-Singleton graph, Ars Combin. 7 (1979) 191-193.] constructed a family of (pm+2)-regular graphs of girth five and order 2p2m, where p?5 is a prime, which includes the Hoffman-Singleton graph [A.J. Hoffman, R.R. Singleton, On Moore graphs with diameters 2 and 3, IBM J. (1960) 497-504]. This construction gives an upper bound for the least number f(k) of vertices of a k-regular graph with girth 5. In this paper, we extend the Murty construction to k-regular graphs with girth 5, for each k. In particular, we obtain new upper bounds for f(k), k?16. 相似文献
152.
The class of γn-complete hypergroups is introduced. Several properties and examples are found both of γn-complete hypergroups and of KH hypergroups. 相似文献
153.
A binary relation R does not always possess the desirable property of transitivity. Consequently, this needs to be imposed artificially by deviating
as little as possible from R. In this paper, three approaches to transitive approximation are analyzed within a common distance-based framework: exterior
(transitive closure), interior (openings or maximal transitive sub-relations contained in R) and mixed (transitive fittings) approximation. Additionally, we propose a method for obtaining all these transitive approximations.
The method is based on a distance function optimization framework that leads to straightforward goal programming models. 相似文献
154.
Ze-shui Xu 《佛山科学技术学院》2009,1(1):79-89
An intuitionistic preference relation is a powerful means to express decision makers’information of intuitionistic preference
over criteria in the process of multi-criteria decision making. In this paper, we first define the concept of its consistence
and give the equivalent interval fuzzy preference relation of it. Then we develop a method for estimating criteria weights
from it, and then extend the method to accommodate group decision making based on them And finally, we use some numerical
examples to illustrate the feasibility and validity of the developed method. 相似文献
155.
Przemys?aw Górka 《Journal of Mathematical Analysis and Applications》2008,341(2):1413-1426
We examine the evolution of crystals in three dimensions. We assume that the Wulff shape is a prism with a hexagonal base. We include the Gibbs-Thomson law on the crystal surface and the so-called Stefan condition. We show local in time existence of solutions assuming that the initial crystal has admissible shape. 相似文献
156.
157.
Ka Chun Cheung 《Insurance: Mathematics and Economics》2008,42(2):651-655
Comonotonicity provides a convenient convex upper bound for a sum of random variables with arbitrary dependence structure. Improved convex upper bound was introduced via conditioning by Kaas et al. [Kaas, R., Dhaene, J., Goovaerts, M., 2000. Upper and lower bounds for sums of random variables. Insurance: Math. Econ. 27, 151-168]. In this paper, we unify these results in a more general context using the concept of conditional comonotonicity. We also construct an approximating sequence of convex upper bounds with nice convergence properties. 相似文献
158.
Electrons on infinite coupled chains with nearest neighbour couplings under uniform electric and magnetic fields can be expressed as conditionally solvable systems, which concerns both discrete coordinate and wavenumber representations. We then have to account for multiparameter extra-conditions relying on the single chain phase of the system, which amounts to perform a suitable selection of parameters. The implicit plots provided by such conditions exhibit both regular and irregular patterns. This results in the onset of a finite number of Wannier–Stark resonances, now by performing rescalings needed. However, this time the resonance width is sensitive to the quantum number characterizing the Stark-ladder. Bound-state limits, rescalings and approximations proceeding irrespective of the wavenumber have also been presented. 相似文献
159.
交流电桥的示波器测量方法 总被引:1,自引:0,他引:1
传统的交流电桥教学采用毫伏表,本文给出了一种采用示波器的电桥教学与测量方法,能更直观展示电桥的幅、相关系,有更好的教学效果。 相似文献
160.
A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of concrete.The relation between the fractal box dimension in large scale and the damage to concrete in small scale is deduced.And the evolutionary process of elastic modulus and strength in small scale is given.Consequently,the multi-scale numerical model is proposed to describe the constitutive relation of concrete between small scale and large scale.A two-dimensional static analysis of a concrete block is performed by using this model and the calculation result is discussed.The propagation of cracks of the concrete block is also studied. 相似文献