提出一种求解安全约束机组组合(security constrained unit commitment,SCUC)问题的邻域搜索外逼近(outer approximation based on neighborhood search,NS-OA)法. OA将SCUC问题分解为一系列混合整数线性规划(mixed integer linear prog...提出一种求解安全约束机组组合(security constrained unit commitment,SCUC)问题的邻域搜索外逼近(outer approximation based on neighborhood search,NS-OA)法. OA将SCUC问题分解为一系列混合整数线性规划(mixed integer linear programming,MILP)主问题和非线性规划(nonlinear programming,NLP)子问题,通过MILP主问题和NLP子问题的最优解来逼近SCUC问题的最优解.为克服迭代过程中MILP主问题规模大的不足,利用SCUC问题对应UC问题的最优解为中心来构造邻域,然后在此邻域内搜索MILP主问题的最优解.数值结果表明,所提邻域搜索能有效减小搜索空间,大大提高了算法的计算效率,所提NS-OA算法能有效求解大规模SCUC问题,具有良好的应用前景.展开更多
【目的】分析果树害虫国内外相关科技文献,深入了解果树害虫在全世界范围内的研究热点和趋势。【方法】利用文献计量学的方法,以Web of Science数据库为数据源,对果树害虫研究的年度和国家进行了科研合作、关键词、论文发表数量的统计...【目的】分析果树害虫国内外相关科技文献,深入了解果树害虫在全世界范围内的研究热点和趋势。【方法】利用文献计量学的方法,以Web of Science数据库为数据源,对果树害虫研究的年度和国家进行了科研合作、关键词、论文发表数量的统计分析。【结果】通过Web of Science核心合集数据库,检索出美国、中国、巴西、澳大利亚和意大利等20个国家在1995—2020年发表了8551篇果树害虫相关文献。国内外果树害虫发表文献数量最多的国家分别是美国和中国,在果树类型、虫害和虫害管理3个方面频次出现最高的分别为杧果、果蝇和生物防治。高频关键词的聚类分析发现果树害虫的研究热点与绿色可持续防控相关,尤其侧重有害生物综合治理(Integrated Pest Management,IPM)和生物防治两个方面的研究。【结论】近25年国内外对果树害虫的研究关注度除了2019年之外,整体处于上升趋势,研究内容涵盖果树害虫寄主植物、虫害种类和防控技术等方面。IPM和生物防治作为新兴的防治方法,通过利用有益生物及其产物控制有害生物种群数量,达到了避免化学农药防治害虫对果实的危害和影响,以及利于食用者身体健康的双赢效果,已经在果树虫害防治中得到了广泛的应用。展开更多
Deciphering the role of climatic oscillations in species divergence helps us understand the mechanisms that shape global biodiversity.The coldadapted species may have expanded their distribution with the development o...Deciphering the role of climatic oscillations in species divergence helps us understand the mechanisms that shape global biodiversity.The coldadapted species may have expanded their distribution with the development of glaciers during glacial period.With the retreat of glaciers,these species were discontinuously distributed in the high-altitude mountains and isolated by geographical barriers.However,the study that focuses on the speciation process of cold-adapted species is scant.To fill this gap,we combined population genetic data and ecological niche models(ENMs)to explore divergence process of snow partridge(Lerwa lerwa).Lerwa lerwa is a cold-adapted bird that is distributed from 4,000 to 5,500 m.We found 2 genetic populations within L.lerwa,and they diverged from each other at about 0.40–0.44 million years ago(inter-glacial period after Zhongliangan glaciation).The ENMs suggested that L.lerwa expanded to the low elevations of the Himalayas and Hengduan mountains during glacial period,whereas it contracted to the high elevations,southern of Himalayas,and Hengduan mountains during inter-glacial periods.Effective population size trajectory also suggested that L.lerwa expanded its population size during the glacial period.Consistent with our expectation,the results support that inter-glacial isolation contributed to the divergence of cold-adapted L.lerwa on Qinghai-Tibetan Plateau.This study deepens our understanding of how climatic oscillations have driven divergence process of cold-adapted Phasianidae species distributed on mountains.展开更多
文摘提出一种求解安全约束机组组合(security constrained unit commitment,SCUC)问题的邻域搜索外逼近(outer approximation based on neighborhood search,NS-OA)法. OA将SCUC问题分解为一系列混合整数线性规划(mixed integer linear programming,MILP)主问题和非线性规划(nonlinear programming,NLP)子问题,通过MILP主问题和NLP子问题的最优解来逼近SCUC问题的最优解.为克服迭代过程中MILP主问题规模大的不足,利用SCUC问题对应UC问题的最优解为中心来构造邻域,然后在此邻域内搜索MILP主问题的最优解.数值结果表明,所提邻域搜索能有效减小搜索空间,大大提高了算法的计算效率,所提NS-OA算法能有效求解大规模SCUC问题,具有良好的应用前景.
文摘【目的】分析果树害虫国内外相关科技文献,深入了解果树害虫在全世界范围内的研究热点和趋势。【方法】利用文献计量学的方法,以Web of Science数据库为数据源,对果树害虫研究的年度和国家进行了科研合作、关键词、论文发表数量的统计分析。【结果】通过Web of Science核心合集数据库,检索出美国、中国、巴西、澳大利亚和意大利等20个国家在1995—2020年发表了8551篇果树害虫相关文献。国内外果树害虫发表文献数量最多的国家分别是美国和中国,在果树类型、虫害和虫害管理3个方面频次出现最高的分别为杧果、果蝇和生物防治。高频关键词的聚类分析发现果树害虫的研究热点与绿色可持续防控相关,尤其侧重有害生物综合治理(Integrated Pest Management,IPM)和生物防治两个方面的研究。【结论】近25年国内外对果树害虫的研究关注度除了2019年之外,整体处于上升趋势,研究内容涵盖果树害虫寄主植物、虫害种类和防控技术等方面。IPM和生物防治作为新兴的防治方法,通过利用有益生物及其产物控制有害生物种群数量,达到了避免化学农药防治害虫对果实的危害和影响,以及利于食用者身体健康的双赢效果,已经在果树虫害防治中得到了广泛的应用。
基金supported by the second National Survey on Terrestrial Wildlife Resources in China.
文摘Deciphering the role of climatic oscillations in species divergence helps us understand the mechanisms that shape global biodiversity.The coldadapted species may have expanded their distribution with the development of glaciers during glacial period.With the retreat of glaciers,these species were discontinuously distributed in the high-altitude mountains and isolated by geographical barriers.However,the study that focuses on the speciation process of cold-adapted species is scant.To fill this gap,we combined population genetic data and ecological niche models(ENMs)to explore divergence process of snow partridge(Lerwa lerwa).Lerwa lerwa is a cold-adapted bird that is distributed from 4,000 to 5,500 m.We found 2 genetic populations within L.lerwa,and they diverged from each other at about 0.40–0.44 million years ago(inter-glacial period after Zhongliangan glaciation).The ENMs suggested that L.lerwa expanded to the low elevations of the Himalayas and Hengduan mountains during glacial period,whereas it contracted to the high elevations,southern of Himalayas,and Hengduan mountains during inter-glacial periods.Effective population size trajectory also suggested that L.lerwa expanded its population size during the glacial period.Consistent with our expectation,the results support that inter-glacial isolation contributed to the divergence of cold-adapted L.lerwa on Qinghai-Tibetan Plateau.This study deepens our understanding of how climatic oscillations have driven divergence process of cold-adapted Phasianidae species distributed on mountains.
