Rectilinear steiner tree heuristics and minimum spanning tree algorithms using geographic nearest neighbors

We study the application of the geographic nearest neighbor approach to two problems. The first problem is the construction of an approximately minimum length rectilinear Steiner tree for a set ofn points in the plane. For this problem, we introduce a variation of a subgraph of sizeO(n) used by YaO [31] for constructing minimum spanning trees. Using this subgraph, we improve the running times of the heuristics discussed by Bern [6] fromO(n ² log n) toO(n log² n). The second problem is the construction of a rectilinear minimum spanning tree for a set ofn noncrossing line segments in the plane. We present an optimalO(n logn) algorithm for this problem. The rectilinear minimum spanning tree for a set of points can thus be computed optimally without using the Voronoi diagram. This algorithm can also be extended to obtain a rectilinear minimum spanning tree for a set of nonintersecting simple polygons.The results in this paper are a part of Y. C. Yee's Ph.D. thesis done at SUNY at Albany. He was supported in part by NSF Grants IRI-8703430 and CCR-8805782. S. S. Ravi was supported in part by NSF Grants DCI-86-03318 and CCR-89-05296.     

试论就业形势与战略

论述了就业的特殊重要性、目前我国就业形势的极端严重性，以及所应当采取的战略和措施。     

企业间的商战模型分析

针对日益激烈的市场竞争，探讨了引发大规模商战的原因，建立了两企业集团间的商战模型，并分析了模型的均衡点，同时在此基础上建立了多个企业集团问商战模型，分析了模型的稳定性，最后根据模型的结论给出了企业间避免恶性商战的相关建议与对策。     

关于地方本科学院组建和发展中若干问题的探讨

本文论述了组建地方本科学院的客观必然性，分析了在组建和发展过程中亟待解决的矛盾和问题，提出了政府应加大宏观调控力度，对高等教育地方化应有理性选择，努力办出特色应成为学院发展的核心任务。     

东江河流生态评价及其修复方略

本文通过对大型无脊椎底栖动物状况的调查对东江河流水生态状况进行了分析,并在此基础上提出了生态修复方略。从上游到河口选12个点采集底栖动物样本,发现东江流域底栖动物生物多样性在上游和中游保持在较高水平,而到下游则迅速降低到零。对增江湾、西枝江牛轭湖等处的取样进行分析并探讨改善东江生态的方法。针对不同生态应力提出了3种生态修复方略:1.创造多样性的生物栖息地,开发和形成一系列类似增江湾那样的缓流滞流区,把已经隔离的牛轭湖和江边湖泊湿地重新与江水连通;2.调整大坝运用方式,采取大坝泄放的流量逐渐增加和减少的方式,给生物发出流速增大和降低的信号,使其得以准备和躲避;3.稳定岸坡、控制侵蚀、保护和发育河边植被。     

一种改进的共同进化遗传算法及其应用

将共同进化遗传算法应用于临床营养决策优化中,虽然取得了一定成果,但算法中仍存在早熟现象、局部搜索能量弱等问题,为此提出一种改进的共同进化模型。算法使用新的子群体划分方法和交叉算子,引入精英保留策略、信息交换原则和小生境技术。通过对糖尿病营养治疗的仿真表明,改进后的算法在保证群体多样性和避免早熟现象的前提下,提高了算法的局部和全局寻优能力,且膳食配方中营养素达标率符合要求,满足专家建议的糖尿病饮食需求。     

Color Grouping in Space and Time: Evidence From Negative Color-Based Carryover Effects in Preview Search.

Five experiments addressed the role of color grouping in preview search (D. G. Watson & G. W. Humphreys, 1997). Experiment 1 used opposite color ratios of distractors in preview and second search displays, creating equal numbers of distractors in each color group in the final display. There was selective slowing for new targets carrying the majority color of the old items. This effect held when there was no bias in the preview and only the second search set had an uneven color ratio (Experiment 2). In Experiment 3, participants had foreknowledge of the target color, and effects were shown over and above those due to color biases. Experiment 4 demonstrated negative color carryover even when previews changed color. Experiment 5 showed reduced color carryover effects when previews were presented more briefly. Collectively, the results provide evidence for inhibitory carryover effects in preview search based on feature grouping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response Selection in Visual Search: The Influence of Response Compatibility of Nontargets.

The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

电网无功补偿方式的探讨

概述了电网无功补偿的基本情况，并对几种无功补偿方式进行了技术分析，结合几种补偿方式的特点，提出了无功补偿配置原则。