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基于节点关系的城市供水网络关键区域识别 被引量:1
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作者 韩建军 曾辉 《水电能源科学》 北大核心 2020年第1期119-122,98,共5页
为提高城市供水系统管理效率、明确供水系统的重点区域,运用图论及布尔矩阵理论,基于供水网络节点关系,提出供水网络分区模型及关键区域识别方法。首先,分析城市供水系统组成,建立供水网络有向拓扑图,以直接关系和可达关系两方面揭示节... 为提高城市供水系统管理效率、明确供水系统的重点区域,运用图论及布尔矩阵理论,基于供水网络节点关系,提出供水网络分区模型及关键区域识别方法。首先,分析城市供水系统组成,建立供水网络有向拓扑图,以直接关系和可达关系两方面揭示节点关系;然后,分解可达矩阵,划分网络层次,提出城市供水网络分区方法,定义节点依赖水平和驱动水平,测度节点关键性,识别关键区域;最后,结合具体城市供水网络规划进行分析。结果表明,供水网络分区及关键区域与实际情况符合;水源节点的驱动水平最高,顶层节点的依赖水平最大;水源区关键性最高,供水末端区域关键性最低。该方法为城市供水系统安全防护或灾害条件下应急高效救援提供理论指导。 展开更多
关键词 城市供水 节点关系 分区 节点关键性 区域关键性
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结构仿真高精度有限元网格划分方法 被引量:63
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作者 李涛 左正兴 廖日东 《机械工程学报》 EI CAS CSCD 北大核心 2009年第6期304-308,共5页
为了得到高精度计算结果的有限元网格,在有限元模型任一单元小片内将其误差分解为全局误差与局部误差两部分:局部误差是由于该单元小片内单元的残值所引起的,而全局误差是由单元小片外区域内单元的残值所导致。提出关键性区域的概念,并... 为了得到高精度计算结果的有限元网格,在有限元模型任一单元小片内将其误差分解为全局误差与局部误差两部分:局部误差是由于该单元小片内单元的残值所引起的,而全局误差是由单元小片外区域内单元的残值所导致。提出关键性区域的概念,并得出有限元求解模型中所有关键性区域的网格划分水平决定整个有限元模型的计算结果精度的论断。基于该结论建立高精度有限元网格划分方法流程。以连杆为实例,应用高精度有限元网格划分方法流程对连杆进行高精度网格划分。在压缩工况下,对其平面模型进行关键性区域的划分,并研究其误差特性,可知局部误差是连杆结构仿真误差的主导部分。划分疏密得当的高精度网格。应用实例证明了提出方法的可行性、实用性。 展开更多
关键词 结构仿真 有限元 关键性区域 连杆
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Changes in the Ecological Characteristics of Key Biodiversity Areas in the BRI Region 被引量:2
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作者 WANG Boyu YAN Huimin +1 位作者 FENG Zhiming YANG Yanzhao 《Journal of Resources and Ecology》 CSCD 2022年第2期328-337,共10页
Key Biodiversity Areas(KBAs)are ecological conservation priorities proposed by IUCN and widely recognized by most countries.Evaluating the changes in the ecological characteristics in KBAs is important for biodiversit... Key Biodiversity Areas(KBAs)are ecological conservation priorities proposed by IUCN and widely recognized by most countries.Evaluating the changes in the ecological characteristics in KBAs is important for biodiversity conservation and the construction of Protected Areas(PAs).There are various ecosystem types in the Belt and Road Initiative(BRI)region,which has an extremely high value of biodiversity conservation,and the KBAs should be the prime targets of ecological protection efforts.Using the data of land cover,NDVI and Nighttime Light(NTL),we analyzed the ecological conditions of the KBAs in the BRI region,and their temporal and spatial variations,from the perspectives of vegetation coverage and human activities.The conclusions are:(1)There is generally no significant difference in the land cover of the KBAs,among which forest,wilderness and grassland are the main types;(2)The NDVI of the KBAs showed an increase,indicating that the vegetation was gradually improving,while a few KBAs presenting vegetation degradation were mainly distributed in the Indochina Peninsula,Qinghai-Tibet Plateau and Central and Western Asia;and(3)The NTL in the KBAs was very low,indicating that the human pressure on the natural ecosystems was limited,and only a few KBAs distributed in Central and Eastern Europe,India,and the Indochina Peninsula have high human activity intensity which also showed an increase.This study emphasizes that we should make full use of the biome succession law,and limit the interference of human activities on natural ecosystems for ecological protection of the KBAs,so as to continuously make new breakthroughs in the construction of Protected Areas(PA)in the BRI region. 展开更多
关键词 Biodiversity Areas(KBAs) the Belt and Road Initiative(BRI) land cover vegetation coverage human activities temporal and spatial variations
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