共查询到19条相似文献，搜索用时 109 毫秒
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钱晓雯 《实验室研究与探索》2018,(1)
针对最小化最大完工时间的作业车间调度问题,提出一种基于变邻域搜索的动态烟花算法。变邻域搜索是一类重要的元启发式算法,在每一次迭代计算过程中通过搜索当前解的邻域得到一个改进的解,通过变邻域搜索方法可有效提高局部最优解的精度。与此同时,算法引入进化速度的概念,并通过进化速度计算烟花算法迭代过程中需更新的维度,实时调整相关参数,加快算法收敛,避免陷入局部最优。算例试验表明,该算法具有较好的鲁棒性,且能有效地提高算法搜索精度,加快收敛速度。 相似文献
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给出求权图中某一点到其它所有点的最短路及距离的一种简捷有效的算法，此算法格式严紧，并体现了求解过程。 相似文献
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讨论网络中结点间路径的问题是图论中的基本问题之一，而求其中任两结点间的最短径已有一些方法，也可采用延长算法，即求出两点间的所有路径，算出其路径权值，从而求得最短路径。最短路径在实际中有着广泛的应用，在实际中有一些些求最优的问题，可化为网络中最短路径问题，从而得到最优的第一方案。本提出将任两结点间的不同路径按其权值分布不同阶短路径的概念，并基于Dijkstra算法和路径延长算法，给出根据给定的阶值λ，求相应的λ阶短路径Z算法，可同时获得最优的第一方案、第二方案、…、第λ方案。算法简单、便于手算，并易于计算机处理。 相似文献
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生鲜农产品配送路径规划问题是复杂的NP难问题，为提高配送路径规划效率，有效指导生鲜企业的配送路径规划，文章分析了生鲜配送及带时间窗的车辆路径问题的特点，考虑时间窗约束构建了配送路径最短的数学模型。在传统遗传算法的基础上，引入C-W节约算法改进种群初始化，大规模邻域搜索算法改进局部搜索操作，提出一种混合遗传算法，并进行算例仿真。经计算，算例的最优配送路径包括4条线路，最短配送距离为68.72 km,优于传统遗传算法所得最短路径。验证结果表明：本研究给出的混合遗传算法能较好地解决有时间窗的车辆路径问题，所得方案较优，可以指导企业配送车辆的路径规划。 相似文献
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给出求权图中某一点到其它所有点的最短路及距离的一种简捷有效的算法,此算法格式严紧,并体现了求解过程. 相似文献
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为解决城市物流配送最优路径选取问题,从城市道路网络空间分布形态出发,综合考虑影响最短路径求解的多种因素,建立动态路网模型,并对经典最短路径算法进行改进。结合道路网络的几何性质,以实际路网为例,标记各路段交叉口作为结点,将实际路网部分转化为Manhattan型结构,同时分析相邻交叉口间距离和平均人口对路径选取的影响,通过重新定义考虑双重权重的最短路径权重与参考值[η],对算法进行改进。利用改进算法迭代计算获得最短路径解,并对多个解的情况进行分析,分别比较两条路径的[η]值,并选取其中[η]值较大的一条路径作为最优规划路径。实验结果表明,路网结构转化及算法改进不仅可简化计算,同时参考值[η]的引入还可有效解决最短路径不唯一时最优路径的选取问题。 相似文献
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为求解最小化最大延误无等待流水车间调度问题,提出了3个基于任务块交换的邻域,其中块交换邻域的规模为O(n4),块对换和简化块交换邻域的规模为O(n3).所提邻域的规模均大于现有邻域,因此可提高局部搜索算法的解质量.给出了3个邻域的加速性质,使一个相邻解的评估时间为常量,邻域的评估时间与其规模成正比.同基于支配规则的加速方法相比,所提出的加速性质适用于任何机器数.在禁忌搜索中比较了3个邻域,以及块对换和简化块交换邻域的并集.标准实例集上的计算结果表明:3个基于O(n3)邻域的禁忌搜索算法均好于现有算法;在所有的测试算法中,采用邻域并集的禁忌搜索算法的性能最好. 相似文献
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马晓娜 《赤峰学院学报(自然科学版)》2012,(10):4-6
货郎担问题是组合优化中的著名问题,到目前为止它还没有一个有效算法,本文把它转化为增加限制条件的指派问题,利用指派问题的差额法的变形算法来进行计算,此法适合于求解对称形式的距离矩阵,对于非对称形式的距离矩阵我们也找出了算法,以后再作探讨.此法解得的初始解一般为最优解或接近最优解,当解得的初始解不是最优解时,也给出了改进方法,以及合并两个以上回路的方法.该算法优于传统算法,而且具有一定的实用性. 相似文献
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讨论网络中结点间路径的问题是图论中的基本问题之一 ,而求其中任两结点间的最短路径已有一些方法 ,也可采用延长算法 ,即求出两点间的所有路径 ,算出其路径权值 ,从而求得最短路径。最短路径在实际中有着广泛的应用。在实际中有一些求最优的问题 ,可化为网络中最短路径问题 ,从而得到最优的第一方案。本文提出将任两结点间的不同路径按其权值分成不同阶短路径的概念 ,并基于 Dijkstra算法和路径延长算法 ,给出根据给定的阶值 λ,求相应的 λ阶短路径 Z算法 ,可同时获得最优的第一方案、第二方案、…、第 λ方案。算法简单 ,便于手算 ,并易于计算机处理 相似文献
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INTRODUCTION With the development of novel wireless tech- nologies and increasing available bandwidth, multi- media applications over wireless networks become attractive for both businesses and end users. Fast de- ployment of Wi-Fi HotSpots, increase in wireless coverage of remote habitable areas (Wi-Max, or wireless mesh networks), improved data services over the 2G cellular systems and the long awaited debut of 3G wireless services offer many potential and inter- operable communicatio… 相似文献
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Swarm intelligence approaches, such as ant colony optimization (ACO), are used in adaptive e-learning systems and provide an effective method for finding optimal learning paths based on self-organization. The aim of this paper is to develop an improved modeling of adaptive tutoring systems using ACO. In this model, the learning object is personalized based on learning and solving problem styles. The purposed algorithm, based on ACO, generates the adaptive optimal learning path. The algorithm describes an architecture which supports the recording, processing and presentation of collective learner behavior designed to create a feedback loop informing learners of successful paths towards the attainment of learning goals. The algorithm parameters are tuned dynamically to conform to the actual pedagogical process. The article includes the results of implementation and experiment represent this algorithm is able to provide its main purpose which is finding optimal learning paths based on learning styles and improved performance of previous adaptive tutoring systems. 相似文献
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提出了一种在数控加工中刀位轨迹排列的预控优化算法。该算法在保证加工精度的前提下，使相邻轨迹间的残留高度均达到最大允许值，并使得下一次走刀的初始轨迹线具有最大的走刀步距：通过预控走刀后，再利用无振荡B样条插值得到此次走刀的优化轨迹线，据此可进而求得整张曲面上的刀位轨迹，最后通过刀位脸证进行适当调整以确定最终的刀位轨迹。本文最后给出了一个计算实例，并与常用的等参数法做一比较，结果表明，刀位轨迹数明显减少，轨迹长度也大大缩短，从而验证了此算法的正确性和有效性。 相似文献
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Using longitudinal data collected over 2 years on a sample of 2,745 urban elementary school children (1st-6th graders, ages 6-11 years) from economically disadvantaged communities, effects of stressful experiences within 3 contexts (school, family, neighborhood), cumulative stress, and multiple context stress on 3 indices of children's adjustment (achievement, depression, and aggression) were examined. All 3 stressor contexts were related contemporaneously and longitudinally to negative outcomes across adjustment measures, with differential paths in each predictive model. Cumulative stress was linearly related to increases in adjustment problems but multiple context stress was not related to problematic adjustment beyond effects of cumulative stress alone. The important influence of life events stress on children's adjustment in disadvantaged communities is discussed. 相似文献
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TSP是一个典型的组合优化问题,也是一个NP难题,其可能的路径总数是随着城市数目n的增长而成几何型增长的,所以一般很难准确地求出其最优解,因而寻找出有效的近似求解算法就成了解决此问题的最佳方法。文章首先介绍了在初始化阶段经行改进的遗传方法。通过把改进方法同标准的遗传算法相比较,得出改进遗传算法在性能上有改进。最后,我们还分析了实验结果并提出了评价初始解优劣的一个指标函数——局部相似度函数,并给出了函数的具体表达式。 相似文献
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Ubiquitous “sex tips” in popular media evidence an unquenchable public interest in learning how to experience “great sex,” and studies confirm that a great sexual relationship correlates to general relationship satisfaction, which in turn correlates to overall happiness. While studies of great sex or “optimal sexuality” are few, enough is known to conclude that the paths to great sex depicted in popular media are largely dead ends. This lesson plan will help educators (a) dispel inaccurate information about optimal sexuality disseminated in the popular media and (b) inform students about the components of optimal sexuality. 相似文献
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并行化遗传算法研究 总被引：1，自引：0，他引：1
陈宝国 《淮南师范学院学报》2008,10(3):124-126
并行遗传算法（Parallel Genetic Algorithms,PGA）广泛应用于解决各种优化问题。给出了遗传算法并行化目的描述,做出并行性分析。详细介绍遗传算法三种结构化并行模型：踏脚石模型,岛屿模型,邻接模型。最后给出并行遗传算法的硬件支持环境及性能评价。 相似文献
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《Parenting, science and practice》2013,13(2):127-150
Objective. This research study tested a social cognitive model in which family socioeconomic status (SES) and neighborhood quality predicted parental efficacy, which then predicted the academic and social-emotional adjustment of adolescents through 3 parental behaviors (monitoring, parental involvement, and parent-adolescent communication). Design. The study investigated parental efficacy among a stratified random sample of 929 parents and their adolescent children in the United States. Parents and adolescents provided reports through telephone interviews. Structural equation modeling tested the model fit for the overall sample and for European American (n = 387), African American (n = 259), and Latin American (n = 283) subsamples. Results. The model fit for the overall sample and for each racial or ethnic group. Paths within each model also were examined. For the overall sample, neighborhood quality predicted parental efficacy, parental efficacy predicted reported parental involvement and monitoring, both of which predicted academic and social-emotional adjustment of adolescents, and parent-adolescent communication predicted social-emotional adjustment. Some racial or ethnic differences in paths emerged. Conclusions. Overall, the study supported predictions made by social cognitive theory. Given the link between parental efficacy, parenting behaviors, and adolescent outcomes, 1 important goal of programs for parents of adolescents might be to bolster parental efficacy. 相似文献
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Amy E. Heberle Yolanda M. Thomas Robert L. Wagmiller Margaret J. Briggs‐Gowan Alice S. Carter 《Child development》2014,85(5):2046-2061
Disadvantaged neighborhoods confer risk for behavior problems in school‐aged children but their impact in toddlerhood is unknown. Relations between toddlers’ disruptive behavior and neighborhood disadvantage, family disadvantage, violence or conflict exposure, parent depressive symptoms, and parenting behavior were examined using multilevel, multigroup (girl–boy) models. Participants were 1,204 families (mean child age = 24.7 months). Unique associations between disruptive behavior and all risk factors were observed, but the effect of neighborhood disadvantage was negligible when all of the more proximal factors were accounted for. The results suggest both that children in disadvantaged neighborhoods are at greater risk of behavior problems than children in nondisadvantaged neighborhoods and that optimal prevention/intervention work with these children will attend to proximal risk factors. 相似文献