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111.
The master problem in Benders's partitioning method is an integer program with a very large number of constraints, each of which is usually generated by solving the integer program with the constraints generated earlier. Computational experience shows that the subset B of those constraints of the master problem that are satisfied with equality at the linear programming optimum often play a crucial role in determining the integer optimum, in the sense that only a few of the remaining inequalities are needed. We characterize this subset B of inequalities. If an optimal basic solution to the linear program is nondegenerate in the continuous variables and has p integer-constrained basic variables, then the corresponding set B contains at most 2p inequalities, none of which is implied by the others. We give an efficient procedure for generating an appropriate subset of the inequalities in B, which leads to a considerably improved version of Benders's method. 相似文献
112.
Resource partitioning theory claims that Increasing concentration enhances the life chances of specialist organizations. We systematically think through this theory, specify implicit background assumptions, sharpen concepts, and rigorously check the theory's logic. As a result, we increase the theory's explanatory power, and claim—contrary to received opinion'that under certain general conditions, resource partitioning and the proliferation of specialists can take place independently of organizational mass and relative size effects, size localized competition, diversifying consumer tastes, increasing number of dimensions of the resource space, and changing niche widths. Our analysis makes furthermore clear that specialist and generalist strategies are asymmetric, and shows that not concentration enhances the life chances of specialists but economies of scale instead. Under the conditions explicated, we argue that if scale economies come to dominate, the number of organizations in the population increases, regardless of the incumbents' sizes. 相似文献
113.
本文为"碳酸钙形成过程中重金属离子的配分问题研究"的第二部分.上文介绍了配分问题的理论基础、实验方法和重金属离子的配分特征.本文则介绍配分问题的理论机制.作者综述了有关重金属离子在方解石晶面上选择吸附的最新实验; 介绍了用原子力显微镜观察晶面上单分子台阶分布的研究结果; 评述了研究重金属离子配分问题的理论机制; 讨论了两阶段理论模型, 多重表面座模型, 表面薄膜模型和化学吸附层模型的应用;提出了深入开展杂质分凝理论研究的建议. 相似文献
114.
A critical review on the effect of ultrasound (US) on enzymes and their biocatalytic action is presented here. Discussion on the information users of US acquire before utilizing the different devices, and the importance they give to US frequency is constant along the review. The authors have gone into the different areas in which the US–enzyme binomial has been applied. The lack of enough information on the US–enzyme-working conditions under which each piece of research has been developed, and the necessity to provide complete information on the data and metadata to give enough light on each piece of research (and thus on the potential comparison of results from different studies) are critically exposed. With this aim, the study has been divided into the positive effect of US on enzymes to favor the production of metabolites, polymers or proteins; and the degradation, inhibition or activation of the biocatalyst under US application. Also the effect of US on enzyme production and the main fields of application of the US–enzyme binomial are discussed. 相似文献
115.
116.
以训练成本最小化为目标,构建了动态扇区划分管制员指派数学模型,通过引入虚拟扇区将模型设计成标准指派问题,为采用LINGO或MATLAB等工具求解奠定了基础.用空间集合抽象了管制员所管控扇区在扇区变动前后的位置关系,根据位置关系用代数式量化了指派成本.根据计算分析结果,提出了减少训练成本,缩短动态扇、区前置准备时间的建议措施. 相似文献
117.
Asad Muhammad Khan Syed Sakhawat Shah 《Journal of Dispersion Science and Technology》2013,34(9):1247-1254
Ultraviolet (UV) and Fourier transformed infrared (FTIR) spectra of ciprofloxacin hydrochloride (Cpf) were studied under different pH conditions. The effect of aqueous, strong acidic, (pH 0.5–1.0) and a basic (pH 9.2) conditions on spectral behavior of Cpf was investigated in aqueous as well as in micellar environment of sodium dodecyl sulfate (SDS). Cpf shows partitioning from aqueous to micellar phase in a strong acidic as well as in a basic environment. Cpf shows no partitioning or binding to micelle in aqueous phase. Conductivity studies show that critical micelle concentration of SDS is increased with increasing concentration of Cpf. Different sites are responsible for binding under different pH conditions. 相似文献
118.
Britton Harris 《Annals of Operations Research》2003,123(1-4):37-52
This paper develops two methods for finding building-blocks for solving Rosing's multi-Weber problem as a set-covering problem in zero–one programming. The building blocks are those subsets of the universe of points to be partitioned that do not contain any non-members within their own convex hulls. For a particular universe of 100 cities, there are almost six billion such subsets, and the paper sets out computational methods that make this enumeration feasible. Some of these methods have wider applications, but the central methods are closely tailored to this problem. Means are also suggested for reducing the number of subsets to be enumerated, without ruling out possibly optimal solutions for the complete problem. 相似文献
119.
120.
José R. Mohallem 《Theoretical chemistry accounts》2002,107(6):372-374
It is shown that a supposed catastrophe of Bader's theory of atoms in molecules, suggested by Cassam-chena? and Jayatilaka
[Theor Chem Acc (2001) 105: 213] is merely a consequence of the approximate character of the adiabatic Born–Oppenheimer theory of molecular
structure, and that nonadiabatic approaches could be in accordance with Bader's ideas.
Received: 4 April 2001 / Accepted: 5 September 2001 / Published online: 3 June 2002 相似文献