共振引出系统的布局研究和模拟计算

在介绍1/3整数共振引出基本理论和相关技术的同时,通过简明的解析公式,详细研究和分析了共振引出系统的布局原理.以一台小型医用质子同步加速器的磁铁聚焦结构为基础,给出了设计实例,并与计算机模拟结果进行了比较.     

Exact solution procedures for the balanced unidirectional cyclic layout problem

In this paper, we consider the balanced unidirectional cyclic layout problem (BUCLP) arising in the determination of workstation locations around a closed loop conveyor system, in the allocation of cutting tools on the sites around a turret, in the positioning of stations around a unidirectional single loop AGV path. BUCLP is known to be NP-Complete. One important property of this problem is the balanced material flow assumption where the material flow is conserved at every workstation. We first develop a branch-and-bound procedure by using the special material flow property of the problem. Then, we propose a dynamic programming algorithm, which provides optimum solutions for instances with up to 20 workstations due to memory limitations. The branch and bound procedure can solve problems with up to 50 workstations.     

A heuristic multi-start decomposition approach for optimal design of serial machining lines

We study an optimal design problem for serial machining lines. Such lines consist of a sequence of stations. At every station, the operations to manufacture a product are grouped into blocks. The operations within each block are performed simultaneously by the same spindle head and the blocks of the same station are executed sequentially. The inclusion and exclusion constraints for combining operations into blocks and stations as well as the precedence constraints on the set of operations are given. The problem is to group the operations into blocks and stations minimizing the total line cost. A feasible solution must respect the given cycle time and all given constraints. In this paper, a heuristic multi-start decomposition approach is proposed. It utilizes a decomposition of the initial problem into several sub-problems on the basis of a heuristic solution. Then each obtained sub-problem is solved by an exact algorithm. This procedure is repeated many times, each time it starts with a new heuristic solution. Computational tests show that the proposed approach outperforms simple heuristic algorithms for large-scale problems.     

集中供热系统“管-站”布局及管网优化设计方法研究

对大型集中供热系统而言,设计过程包括"管-站"布局设计和管网系统设计。根据最优化理论,提出了集中供热系统的两级优化设计模型,即第一级的"管站"布局优化和第二级的管网系统多目标优化设计模型。由于"管-站"布局优化模型属NP-hard问题(不确定问题),为寻求有效解法,对"管站"布局优化模型提出两步分级法求解,即优化过程分两步进行,第一步为分区优化,第二步为选址优化。运用本文所述方法对辽河油田振兴区集中供热改造工程,进行了优化设计,取得了较好效果。     

Linear layouts measuring neighbourhoods in graphs

In this paper we introduce the graph layout parameter neighbourhood-width as a variation of the well-known cut-width. The cut-width of a graph G=(V,E) is the smallest integer k, such that there is a linear layout ?:V→{1,…,|V|}, such that for every 1?i<|V| there are at most k edges {u,v} with ?(u)?i and ?(v)>i. The neighbourhood-width of a graph is the smallest integer k, such that there is a linear layout ?, such that for every 1?i<|V| the vertices u with ?(u)?i can be divided into at most k subsets each members having the same neighbourhood with respect to the vertices v with ?(v)>i.We show that the neighbourhood-width of a graph differs from its linear clique-width or linear NLC-width at most by one. This relation is used to show that the minimization problem for neighbourhood-width is NP-complete.Furthermore, we prove that simple modifications of neighbourhood-width imply equivalent layout characterizations for linear clique-width and linear NLC-width.We also show that every graph of path-width k or cut-width k has neighbourhood-width at most k+2 and we give several conditions such that graphs of bounded neighbourhood-width have bounded path-width or bounded cut-width.     

Dynamic Programming Algorithms for Generating Optimal Strip Layouts

This paper presents dynamic programming algorithms for generating optimal strip layouts of equal blanks processed by shearing and punching. The shearing and punching process includes two stages. The sheet is cut into strips using orthogonal guillotine cuts at the first stage. The blanks are punched from the strips at the second stage. The algorithms are applicable in solving the unconstrained problem where the blank demand is unconstrained, the constrained problem where the demand is exact, the unconstrained problem with blade length constraint, and the constrained problem with blade length constraint. When the sheet length is longer than the blade length of the guillotine shear used, the dynamic programming algorithm is applied to generate optimal layouts on segments of lengths not longer than the blade length, and the knapsack algorithm is employed to find the optimal layout of the segments on the sheet. Experimental computations show that the algorithms are efficient.     

L形通道布线的展开法

本文提出将L形通道展成直通道的布线方法，对展开后的直通道定义了水平约束、垂直约束、拐角约束、走线约束，利用赋权的混合图反映这四种约束、并逐步将图中的无向边转变成有向边，按照有向图的线网上下关系，完成直通道布线，再收缩冗余布线区变成L形通道布线.     

Queue layouts of iterated line directed graphs

In this paper, we study queue layouts of iterated line directed graphs. A k-queue layout of a directed graph consists of a linear ordering of the vertices and an assignment of each arc to exactly one of the k queues so that any two arcs assigned to the same queue do not nest. The queuenumber of a directed graph is the minimum number of queues required for a queue layout of the directed graph.We present upper and lower bounds on the queuenumber of an iterated line directed graph L^k(G) of a directed graph G. Our upper bound depends only on G and is independent of the number of iterations k. Queue layouts can be applied to three-dimensional drawings. From the results on the queuenumber of L^k(G), it is shown that for any fixed directed graph G, L^k(G) has a three-dimensional drawing with O(n) volume, where n is the number of vertices in L^k(G). These results are also applied to specific families of iterated line directed graphs such as de Bruijn, Kautz, butterfly, and wrapped butterfly directed graphs. In particular, the queuenumber of k-ary butterfly directed graphs is determined if k is odd.     

Wiring edge-disjoint layouts

We consider the wiring or layer assignment problem for edge-disjoint layouts. The wiring problem is well understood for the case that the underlying layout graph is a square grid (Lipski Jr. and Preparata, 1987). In this paper, we introduce a more general approach to this problem. For an edge-disjoint layout in the plane, respectively in an arbitrary planar layout graph, we give equivalent conditions for k-layer wirability. Based on these conditions, we obtain linear-time algorithms to wire every layout in a tri-hexagonal grid or a tri-square-hexagonal grid, respectively, using at most five layers.     

卫星舱三维布局优化模型及判断不干涉性算法

本以人造卫星仪器舱布局问题为背景。建立了在抛物圆柱体空间中带性能约束的长方体群的布局优化模型。分析模型中不干涉性约束的性质，利用凸集分离定理给出了等价的显式表达式，并构造了判断不干涉性的算法。