关键词： Tree searching   directed graphs   Paths   search strategies   Byways   Numerical controls   greedy method  

摘要： This paper places three greedy search problems in the class NC: lexicographic topological-first search (lex-tfs) for DAGs, lexicographic depth-first search (lex-dfs) for DAGs, and lexicographic breadth-first search (lex-bfs) for directed graphs. The latter result answers an open question of Hoover and Ruzzo (A compendium of problems complete for P, draft, November 1985). For each of these problems, we show that the search trees from all sources in a graph of n vertices can be computed by an EREW PRAM in O(log(2) n) time using O(n(3)) operations for lex-dfs and O(n(3) log n) operations for lex-bfs/lex-tfs. Two novel results that emerge from our derivation of the algorithms are of interest in their own right. One uncovers a natural correspondence between the greedy search strategies and lexicographic versions of path finding problems. The other result is our approach to generating parallel algorithms for the lexicographic versions of path-algebra problems in a uniform way. This approach gives rise to a unifying algorithm which yields, as particular cases, NC algorithms for the path problems that correspond to the three greedy search strategies: all-pairs lexmax longest paths for weighted DAGs, all-pairs lexmin paths for DAGs, and all-pairs lexmin shortest paths for weighted directed graphs with no cycles of negative cost. (C) 1995 Academic Press, Inc.

关键词： FLOW INJECTION   MATHEMATICAL MODEL   OPTIMIZATION   POWELLS METHOD  

摘要： A methodology to design a flow- injection system with optimized performance characteristics for different experimental requirements is presented which requires minimal experimental effort. Departing from basic experimental knowledge of the hydrodynamic parameters and rates of the reactions involved, the coupling of a mathematical model describing the flow system with the Powell's optimization algorithm allows the automated generation of a complete set of flow- injection configurations, each of them being optimal with respect to its objective function. From this set of configurations, the performance of the flow- injection system is easily visualized, allowing the user to select the system that better suits the requirements of his particular application and exploiting the potentiality of multiple flow- injection optimal configurations.

摘要： Let k be a field, S = k[x(v) : v is an element of V] be the polynomial ring over the finite set of variables (x(v) : v is an element of V), and rn = (x(v) : v is an element of V) the ideal defining the origin of Spec S. It is theoretically known (see e.g. Alonso et al., 1991) that the algorithmic ideas for the computation of ideal (and module) intersections, quotients, deciding radical membership etc. in S may be adopted not only for computations in the local ring Sm but also for term orders of mixed type with standard bases replacing Grobner bases. Using the generalization of Mora's tangent cone algorithm to arbitrary term orders we give a detailed description of the necessary modifications and restrictions. In a second part we discuss a generalization of the deformation argument for standard bases and independent sets to term orders of mixed type. For local term orders these questions were investigated in Grabe (1991). The main algorithmic ideas described are implemented in the author's REDUCE package CALI (Grabe, 1993a).

关键词： Chain   Design   Manipulators   Algebra   Algorithms  

摘要： A new synthesis algorithm for general three-revolute open chain manipulators is proposed making use of an algebraic formulation for the workspace boundary. This algebraic form of a synthesis model is used to formulate design equations and to discuss the number and the type of the multiple solutions.

摘要： Let K be a field;let P subset of K '' be a finite set and let J(P) subset of K[x(1),...,x(n)] be the ideal of P. A purely combinatorial algorithm to obtain a linear basis of the quotient algebra K[x(1),...,x(n)]/J(P) is given. Such a basis is represented by an n-dimensional Ferrers diagram of monomials which is minimal with respect to the inverse lexicographical order less than or equal to(i.t.). It is also shown how this algorithm can be extended to the case in which P is an algebraic multiset. A few applications are stated (among them, how to determine a reduced Grobner basis of J(P) with respect to less than or equal to(i.t.) without using Buchberger's algorithm).

关键词： 机械设备   折旧   计算   数学模型  

摘要： 长期以来,我国固定资产折旧方法采用平均年限法(即直线法)和工作量法,这种计提方法有其不足之处。设备原值在计提年限内,货币因市场的波动会贬值,如仍按原值来计算提取折旧费,势必造成原有资产的衰减,而使企业萎缩。为此,笔者认为,在设备折旧计提的各个年度中,必须考虑一个该年度的保值系数来进行校正,才能确保企业再生产的能力。 采用双倍余额递减法提取折旧,能加快设备投资的回收,促进设备更新,对经济发达的国家来说能适应其科技飞速发展的需要,而对我国来说。

关键词： 数学形态学   灰值图像   并行处理  

摘要： 在灰值数学形态学的阴影算法的基础上，提出了采用表面点集代替阴影来代表灰值结构核的改进算法，大大降低了二值邻城互连的数量。光学实现采用一个光学非相干相关器与阈值器件结合的二值数学形态学系统，并设计了一种数字空间编码技术使这二维系统能实现算法要求的有限三维操作。

关键词： 数学形态学   细化算法  

摘要： 本文主要讨论了细化算法的定义与条件，二值图像细化的数学原理和基于数学形态学的细化算法。文中对结构模式类型和细化算法的逻辑运算描述提出新的见解，可望深化和丰富基于数学形态学细化算法的内容。

摘要： It is shown that the hierarchical model at finite volume has a symmetry group which can be decomposed into rotations and translations as the familiar Poincaré groups. Using these symmetries, it is shown that the intricate sums appearing in the calculation of the high-temperature expansion of the magnetic susceptibility can be performed, at least up to the fourth order, using elementary algebraic manipulations which can be implemented with a computer. These symmetries appear more clearly if we use the two-adic fractions to label the sites. Then the new algebraic methods are applied to the calculation of quantities having a random walk interpretation. In particular, it is shown that the probability of returning to the starting point after m steps has poles at D=–2,–4,...,–2m, where D is a free parameter playing a role similar to the dimensionality in nearest neighbor models.