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1.
设Z_P={1,2,…,P-1,0},在模P的加法运算下,Z_P是一个群。Z_P上定义n维广义正方体,其顶点集为{(x_1,x_2,…,x_n):x_i∈Z_P.i=1,2,…,n},两个顶点x和y之间有一条棱,当且仅当sum from i=1 to n丨x_i-y_i丨=1 mod(P)。在这个定义下,本文证明了对任意P≥2和n≥2,Z_P中n维广义正方体上存在一个经过所有顶点的哈密顿回路。文中给出了一些例子作为应用。 相似文献
2.
Power assignment for wireless ad hoc networks is to assign a power for each wireless node such that the induced communication
graph has some required properties. Recently research efforts have focused on finding the minimum power assignment to guarantee
the connectivity or fault-tolerance of the network. In this paper, we study a new problem of finding the power assignment such that the induced communication graph is a spanner for the original communication graph when all nodes have the maximum power. Here, a spanner means that the length of the
shortest path in the induced communication graph is at most a constant times of the length of the shortest path in the original
communication graph. Polynomial time algorithm is given to minimize the maximum assigned power with spanner property. The
algorithm also works for any other property that can be tested in polynomial time and is monotone. We then give a polynomial time approximation method to minimize the total transmission radius of all nodes. Finally, we
propose two heuristics and conduct extensive simulations to study their performance when we aim to minimize the total assigned
power of all nodes.
The author is partially supported by NSF CCR-0311174. 相似文献
3.
运用图模型理论研究冲突视角下中欧班列运营过程中运输订单商业竞争战略,构建“渝新欧”班列运营商、“苏满欧”班列运营商和昆山IT企业之间的商业竞争冲突模型。利用TOPSIS法评估班列的运输效率,确定决策者偏好,通过计算均衡解获得符合各决策者利益的理性对策。借助灵敏度分析研究决策者偏好改变对模型冲突结果的影响。研究表明:在竞争中,运输效率较低的一方可以通过降低价格弥补自身劣势而获得订单;运输效率较高的一方只有通过降价才能获得订单。该研究为班列运营商提供利益冲突中的商业竞争战略,能为顾客企业选择高效合理的运输线路提供有效的战略决策,同时亦能为宏观调控者规范市场、提高市场运输效率提供有效的政策启示。 相似文献
4.
《Risk analysis》2018,38(5):929-946
Graphs show promise for improving communications about different types of risks, including health risks, financial risks, and climate risks. However, graph designs that are effective at meeting one important risk communication goal (promoting risk‐avoidant behaviors) can at the same time compromise another key goal (improving risk understanding). We developed and tested simple bar graphs aimed at accomplishing these two goals simultaneously. We manipulated two design features in graphs, namely, whether graphs depicted the number of people affected by a risk and those at risk of harm (“foreground+background”) versus only those affected (“foreground‐only”), and the presence versus absence of simple numerical labels above bars. Foreground‐only displays were associated with larger risk perceptions and risk‐avoidant behavior (i.e., willingness to take a drug for heart attack prevention) than foreground+background displays, regardless of the presence of labels. Foreground‐only graphs also hindered risk understanding when labels were not present. However, the presence of labels significantly improved understanding, eliminating the detrimental effect of foreground‐only displays. Labels also led to more positive user evaluations of the graphs, but did not affect risk‐avoidant behavior. Using process modeling we identified mediators (risk perceptions, understanding, user evaluations) that explained the effect of display type on risk‐avoidant behavior. Our findings contribute new evidence to the graph design literature: unlike what was previously feared, we demonstrate that it is possible to design foreground‐only graphs that promote intentions for behavior change without a detrimental effect on risk understanding. Implications for the design of graphical risk communications and decision support are discussed. 相似文献
5.
In this paper we develop a segmentation scheme for digital images based upon an iterative binary coloring technique that takes into account changing behavior of adjacent pixels. The output is a hierarchical structure of images which allows a better understanding of complex images. In particular, we propose two algorithms that should be considered as image preprocessing techniques. 相似文献
6.
Vincenzo Cutello Giuseppe Nicosia Mario Pavone 《Journal of Combinatorial Optimization》2007,14(1):9-33
We present a new Immune Algorithm, IMMALG, that incorporates a Stochastic Aging operator and a simple local search procedure to improve the overall performances in
tackling the chromatic number problem (CNP) instances. We characterize the algorithm and set its parameters in terms of Kullback
Entropy. Experiments will show that the IA we propose is very competitive with the state-of-art evolutionary algorithms. 相似文献
7.
In a series of 2 papers, Kang, Du and Tian solved the existence problem for G-decomposition of λ
K
n
when G is any simple graph with 6 vertices and 7 edges, except when G is the graph T=K
4∪K
2. Notice that a T-decomposition can be considered to be a Pairwise Balanced Design in which each block of size 4 has been matched to a block
of size 2. In this paper we remove this exception for all λ≥2. The case when λ=1 is also addressed.
This paper is written in honor of Frank Hwang on the occasion of his 65th birthday. 相似文献
8.
Bernard Gendron Alain Hertz Patrick St-Louis 《Journal of Combinatorial Optimization》2007,13(2):163-178
We consider the problem of orienting the edges of a graph so that the length of a longest path in the resulting digraph is
minimum. As shown by Gallai, Roy and Vitaver, this edge orienting problem is equivalent to finding the chromatic number of
a graph. We study various properties of edge orienting methods in the context of local search for graph coloring. We then
exploit these properties to derive four tabu search algorithms, each based on a different neighborhood. We compare these algorithms
numerically to determine which are the most promising and to give potential research directions. 相似文献
9.
略论《山海经图》的流传情况 总被引:3,自引:1,他引:2
沈海波 《上海大学学报(社会科学版)》2000,(5)
现存的《山海经》是《山海经图》的释读文字 ,所以要研究《山海经》还必须对《山海经图》的有关情况进行考证。《山海经图》亡佚的时间 ,大致可推定在汉宣帝至汉成帝之间 相似文献
10.
王先安 《湖南工程学院学报(社会科学版)》1997,(1)
借助于 Auoto CAD强有力的绘图功能及其内嵌式Autolisp语言,准确、迅速、直观、简便地解决机构运动分析中的问题。 相似文献