直径不超过2的2连通无爪图是哈密顿图

不包含2K_2的图是指不包含一对独立边作为导出子图的图.Kriesell证明了所有4连通的无爪图的线图是哈密顿连通的.本文证明了如果图G不包含2K_2并且不同构与K_2,P_3和双星图,那么线图L(G)是哈密顿图,进一步应用由Ryjá(?)ek引入的闭包的概念,给出了直径不超过2的2连通无爪图是哈密顿图这个定理的新的证明方法.     

Balancing and scheduling tasks in assembly lines with sequence-dependent setup times

The classical Simple Assembly Line Balancing Problem (SALBP) has been widely enriched over the past few years with many realistic approaches and much effort has been made to reduce the distance between the academic theory and the industrial reality. Despite this effort, the scheduling of the execution of tasks assigned to every workstation following the balancing of the assembly line has been scarcely reported in the scientific literature. This is supposed to be an operational concern that the worker should solve himself, but in several real environments, setups between tasks exist and optimal or near-optimal tasks schedules should be provided inside each workstation. The problem presented in this paper adds sequence-dependent setup time considerations to the classical SALBP in the following way: whenever a task is assigned next to another at the same workstation, a setup time must be added to compute the global workstation time. After formulating a mathematical model for this innovative problem and showing the high combinatorial nature of the problem, eight different heuristic rules and a GRASP algorithm are designed and tested for solving the problem in reasonable computational time.     

二、三阶可逆矩阵可以相似对角化的几何条件

从几何的角度给出了特征值不含1的二、三阶可逆矩阵可以相似对角化的一个充分条件和二、三阶可逆矩阵可以相似对角化的一个充分必要条件.     

伏拱对赵州桥力学行为的影响

采用数值计算的方法分析了赵州桥上的两对伏拱对桥身拱轴线形状及拱券应力分布的影响，一方面阐明了伏拱的存在使桥体的圆弧形拱轴线与符合力学原理的恒载压力线十分接近，另一方面，说明伏拱的存在明显消除了桥体拱券中的拉应力，加强了桥体的安全性，从而对这座千年古桥的卓越力学性能有了进一步的认识。     

A new multivariable <Subscript><Emphasis Type="BoldItalic">6</Emphasis></Subscript><Emphasis Type="BoldItalic">ψ</Emphasis><Subscript><Emphasis Type="BoldItalic">6</Emphasis></Subscript> summation formula

By multidimensional matrix inversion, combined with an A _r extension of Jackson’s ₈ φ ₇ summation formula by Milne, a new multivariable ₈ φ ₇ summation is derived. By a polynomial argument this ₈ φ ₇ summation is transformed to another multivariable ₈ φ ₇ summation which, by taking a suitable limit, is reduced to a new multivariable extension of the nonterminating ₆ φ ₅ summation. The latter is then extended, by analytic continuation, to a new multivariable extension of Bailey’s very-well-poised ₆ ψ ₆ summation formula. Partly supported by FWF Austrian Science Fund grants P17563-N13, and S9607 (the second is part of the Austrian National Research Network “Analytic Combinatorics and Probabilistic Number Theory”).     

On multiply of sections of line bundles on compact Riemann surfaces

In this paper,we give some conditions on the surjective of multiply maps H~0(R,L)×H~0(R,K)→H~0(R,L(?)K).Here R is a compact Riemann surface,L a line bundle on R and K is the canonical line bundle.     

The basic feasible functionals in computable analysis

We give a correspondence between two notions of complexity for real functions: poly-time computability according to Ko and a notion that arises naturally when one considers the application of Mehlhorn's class of the basic feasible functionals to computable analysis. We show that both notions define the same set of polynomial-time computable real functions.     

New Experimental and Theoretical Results for Argon Broadening and Shift of HCO+ Rotational Lines

An experimental and theoretical study of the pressure broadening and the pressure shift of three HCO⁺ rotational lines (j=4←3, 5←4 and 6←5) perturbed by collisions with Ar is presented. The measurements are carried out at 77 K and are compared to close‐coupling calculations performed on an accurate potential energy surface for the Ar–HCO⁺ interaction extending from small to very large separations between the ion and the perturber. For the pressure broadening, agreement between experiment and theory is satisfactory for both close‐coupling and semiclassical calculations. For the pressure shift, however, close‐coupling calculations are superior. The results agree with experiment in sign and order of magnitude, while semiclassical calculations are inaccurate for the shift of the presently studied lines because they neglect the contribution of strong collisions.     

Asymptotic expansion of the one-loop approximation of the Chern–Simons integral in an abstract Wiener space setting

In an abstract Wiener space setting, we construct a rigorous mathematical model of the one-loop approximation of the perturbative Chern–Simons integral, and derive its explicit asymptotic expansion for stochastic Wilson lines.     

In‐line monitoring of immiscible polymer blends in a rheometer with a fiber‐optics‐assisted fluorescence detection system

In‐line studies of the initial stages of shear‐induced coalescence in two‐phase polymer blends were carried out with a home‐built device combining a cone and plate rheometer and a fiber‐optic‐assisted fluorescence detection system. A blend of 90 wt % poly(2‐ethylhexyl methacrylate) (PEHMA) and 10 wt % poly(butyl methacrylate) (PBMA) was prepared by the casting of films onto a solid substrate from mixed aqueous latex dispersions of the two polymers. The dispersions were prepared via emulsion polymerization under conditions in which both components were formed as spherical particles with a very narrow size distribution. By using a 14:1 particle ratio of PEHMA to PBMA, we obtained films in which 120‐nm PBMA particles were surrounded by a PEHMA matrix. The blend contained phenanthrene‐labeled PBMA particles and anthracene‐labeled PBMA particles in a ratio of 4:1, whereas the PEHMA matrix polymer was unlabeled. We monitored the anthracene‐to‐phenanthrene fluorescence intensity ratio (I₄₇₀/I₃₆₀) as a measure of direct nonradiative energy transfer from phenanthrene to anthracene, whereas the blend was sheared at different shear rates and temperatures. Under no‐shear conditions, the results of in‐line experiments were in good agreement with the results of off‐line measurements of energy transfer by conventional techniques. In blends under shear, the two sets of experiments, in‐line and off‐line, did not agree with each other. The cause of this disagreement was associated with normal forces in the blend under shear that affected the optical path length and the relative intensities of the fluorescence signals of the phenanthrene and anthracene groups in the blend. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2302–2316, 2001