共查询到20条相似文献，搜索用时 203 毫秒
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针对Job shop调度问题,提出了一种改进的禁忌搜索算法,通过从当前解的正序和倒序两个方向同时进行邻域搜索,扩大了搜索的范围。实验结果表明,该算法能有效地解决Job Shop问题。 相似文献
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针对车辆路径问题,提出了改进禁忌搜索算法.在求解过程中,采取双层操作构造邻域结构,设计动态禁忌表来改变禁忌表长度,提高整体寻优能力.仿真实验证明了算法的可行性和有效性. 相似文献
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吴储彬 《职教通讯(江苏技术师范学院学报)》2006,12(6)
本文介绍一种均值加速中值滤波迭代算法,该算法不需要对所有像素的邻域值进行排序,而是对像素的邻域值有选择性的排序,排序后的中值直接替代原像素值.理论分析与实验结果表明:该算法能有效地降低中值滤波算法的时间复杂度,可将常用的快速排序算法复杂度O(N ln N)简化为O(N(1+ln N)/2),且去噪声效果良好,在图像处理中有广泛的应用前景. 相似文献
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本文主要研究基因无方向的基因组重排的反转排序问题.本文算法基于断点图的概念,给出一个时间复杂性为O(maxb3(π),nb(π)),空间复杂性为O(n)的求解近似最优解的算法,其中n为基因组中基因个数,π=(π1,π2,...πn)表示n个基因的一种排列,b(π)表示排列π中的断点数.数据试验的结果表明,该近似算法可以求得较好的结果. 相似文献
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郝晓军 《河北职业技术学院学报》2009,(2)
研究了怎样对于服从正态分布的平面点集进行的凸包算法加速,理论上计算了最适合的加速因子,同时通过相应的加速因子得到正态点集分布的凸包算法最优复杂度O(n)。 相似文献
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侯淑静 《黄冈职业技术学院学报》2015,(1):99-102
旅行售货商问题(简称TSP)是离散优化的一个经典的重要问题,对求解算法的研究非常重要。在介绍求解TSP问题的贪婪算法、禁忌搜索算法、模拟退火算法、遗传算法的基本思想之后,提出了相应的算法。针对测试库的四个典型算例,用程序实现这些算法,对这些算法的运行时间和结果进行比较研究。结果表明贪婪算法短时间就可以得出解,禁忌搜索算法与遗传算法的效果相当,模拟退火算法比遗传算法的结果好。 相似文献
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介绍了天线调谐器阻抗匹配网络的结构和调谐的本质,提出采用基于启发式算法的邻域搜索算法来解决这一个NP-hard问题;给出了基于固定步长的最近邻域搜索算法的迭代步骤,通过对邻域结构和搜索方式的改进,降低了搜索空间、加快了调谐速度;最后采用基于最近邻域搜索的4种算法对10 m短波鞭状天线进行匹配仿真,验证了改进算法的有效性。 相似文献
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郝晓军 《廊坊师范学院学报(自然科学版)》2009,9(2):32-34
研究了怎样对于服从正态分布的平面点集进行的凸包算法加速,理论上计算了最适合的加速因子,同时通过相应的加速因子得到正态点集分布的凸包算法最优复杂度O（n）。 相似文献
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多聚焦图像融合就是综合和处理多个源图像的信息,来获取对同一场景或物体的更为准确、更为全面、更为可靠的图像描述．对于可见光成像系统而言,特别是含有长焦距的光学镜头,对景深有一定的限制．因此,将场景中的所有物体都成像清晰是很难的,这个问题采用多聚焦图像融合技术可以很好解决．通过提出一种基于差异演化的多聚焦图像融合算法,首先将源图像进行分块,然后用清晰度评价函数比较对应图像块的清晰度,选择清晰度高的作为清晰图像块,最终重构融合图像．该方法的积极意义在于,优化后的图像块比没被优化的使用效果更佳．实验结果表明,从定量和视觉两方面评价,都明显优于遗传算法和其他传统的图像融合方法． 相似文献
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基于约束的部分枚举策略的空间关系图匹配算法研究 总被引：5，自引：0，他引：5
本提出了一种基于约束的部分枚举空间关系图匹配策略．该策略通过使用在匹配过程中动态生成的2类匹配约束条件智能预测当前匹配状态的后继有效的枚举状态以跳过无效的中间匹配状态，达到状态空间剪枝的目的，可以有效降低空间关系图匹配过程中状态搜索空间．根据理论分析，该策略在最好情况下的时间复杂度为O(n^2)，在几乎很少发生的最坏情况下时间复杂度为O(n!)；其空间复杂度都是O(n)．所提出的方法已在笔研发的手绘草图识别系统Smart Sketchpad中取得了很好的识别效果． 相似文献
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通过运用大块NAND研究闪存转换层的基本原理,针对物理闪存中的数据块和更新块,利用地址混合映射的方法,对逻辑块号和页号进行拆分,区分更新块的热门页及数据块的冷门页,使用改进的优化算法根据其空闲程度进行部分、完全或交换合并优化,最后通过实验对存储利用率和缓存大小影响进行性能分析,实验数据表明:运用该算法可以有效提高NAND闪存存储效率. 相似文献
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OBJECTIVE: To better understand how neighborhood and individual factors are related to child maltreatment. METHOD: Using an ecological framework, a multi-level model (Hierarchical Linear Modeling) was used to analyze neighborhood structural conditions and individual risk factors for child abuse and neglect. Parents (n = 400) of children under the age of 18 were systematically selected from 20 randomly selected census-defined block groups with different risk profiles for child maltreatment report rates. Parents were administered the Neighborhood Environment for Children Rating Scales, the Child Abuse Potential Inventory, the Zimet measure of social support, and the Conflict Tactics Scales as a measure of childhood experience with violence. RESULTS: Neighborhood factors of impoverishment and child care burden significantly affect child abuse potential after controlling for individual risk factors. However, neighborhood effects are weaker than they appear to be in aggregate studies of official child maltreatment reports. Variation in child abuse potential within neighborhoods is greater than between neighborhoods. However, adverse neighborhood conditions weakend the effects of known individual risk and protective factors, such as violence in the family of origin. CONCLUSIONS: If individual potential for child maltreatment is more evenly distributed across neighborhoods than reported maltreatment, then neighborhood and community play an important, if as yet unspecified, role in child maltreatment. Multi-level models are a promising research strategy for disentangling the complex interactions of individual and contextual factors in child maltreatment. 相似文献
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OBJECTIVE: To better understand how neighborhood and individual factors are related to child maltreatment. METHOD: Using an ecological framework, a multi-level model (Hierarchical Linear Modeling) was used to analyze neighborhood structural conditions and individual risk factors for child abuse and neglect. Parents (n = 400) of children under the age of 18 were systematically selected from 20 randomly selected census-defined block groups with different risk profiles for child maltreatment report rates. Parents were administered the Neighborhood Environment for Children Rating Scales, the Child Abuse Potential Inventory, the Zimet measure of social support, and the Conflict Tactics Scales as a measure of childhood experience with violence. RESULTS: Neighborhood factors of improverishment and child care burden significantly affect child abuse potential after controlling for individual risk factors. However, neighborhood effects are weaker than they appear to be in aggregate studies of official child maltreatment reports. Variation in child abuse potential within neighborhoods is greater than between neighborhoods. However, adverse neighborhood conditions weakened the effects of known individual risk and protective factors, such as violence in the family of origin. CONCLUSIONS: If individual potential for child maltreatment is more evenly distributed across neighborhoods than reported maltreatment, then neighborhood and community play an important, if as yet unspecified, role in child maltreatment. Multi-level models are a promising research strategy for disentangling the complex interactions of individual and contextual factors in child maltreatment. 相似文献
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Dan Cloney Gordon Cleveland John Hattie Collette Tayler 《Early education and development》2016,27(3):384-401
Research Findings: This article provides Australian evidence of the availability and quality of early childhood education and care (ECEC) services in low–socioeconomic status (SES) neighborhoods. There is less availability of ECEC in low-SES areas in Australia, and these programs provide a lower average quality of care than in more advantaged neighborhoods. Families tend to travel short distances to ECEC programs (Mdn = 2.9 km), and therefore families in low-SES areas are limited in the programs they can choose or are faced with higher transport costs than families in more advantaged neighborhoods. This study uses government licensing data from a population of 6,937 ECEC services together with a sample of 2,494 children enrolled in 421 ECEC classrooms. Practice or Policy: Established measures of the local ECEC market tend to overestimate its size and in turn the availability of ECEC. Measures of ECEC market density should be tested for sensitivity to reductions in size. SES gradients are observed within local ECEC markets, meaning that attempts to lift supply and quality in low-SES areas require specific and targeted policy intervention. 相似文献
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A multi-dimensional concatenation scheme for block codes is introduced.in which information symbols are interleaved and re-encoded for nmore than once.It provides a convenient platform to design high performance codes with flexible interleaver size,Coset based MAP soft-in/soft-out decoding algorithms are presented for the F24 code.Simulation results show that the propsed coding scheme can achieve high coding gain with flexible interleaver length and very low decoding complexity. 相似文献
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对Aln团簇与O2桥吸附的机理进行了量子化学研究,从而确定Aln团簇与O2桥式吸附的可行性.利用Becke型三参数密度泛函模型,采用Lee-Yang-Parr泛函,在6-31＋＋g（d,p）基组条件下对所有结构进行优化,确定所有构型均无虚频率的情况下,得到Aln团簇与O2桥式吸附的几何结构、稳定性、最高和最低占据轨道以及能隙、解离能、平均原子结合能和吸附能等相关参数.进而对AlnO2团簇（n=1~9）的稳定性进行研究,结果表明Al（nn=l~9）团簇都能很好的与O2吸附,Al2O2团簇具有最大的相对稳定性. 相似文献
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