ASI是 Articulated Subject Index 的简称,国内习惯称之为“挂接主题索引”。该索引的阅读是科技文献检索中的一个难点。本文提出一种新的阅读方法,将结构复杂的说明语短语归纳成六种“基本形式”,用“顺接”与“反接”的方式连读。该...ASI是 Articulated Subject Index 的简称,国内习惯称之为“挂接主题索引”。该索引的阅读是科技文献检索中的一个难点。本文提出一种新的阅读方法,将结构复杂的说明语短语归纳成六种“基本形式”,用“顺接”与“反接”的方式连读。该法简明,易于为读者掌握。展开更多
由于实时跟踪移动的空间对象需要不断地查询和更新空间数据库的索引,经典R树空间索引结构的静态管理空间对象的方法并不适合移动环境,从而导致系统执行效率非常低下。根据对移动对象运动模式的分析,文中提出了一种称为ASI(Adaptive Spat...由于实时跟踪移动的空间对象需要不断地查询和更新空间数据库的索引,经典R树空间索引结构的静态管理空间对象的方法并不适合移动环境,从而导致系统执行效率非常低下。根据对移动对象运动模式的分析,文中提出了一种称为ASI(Adaptive Spatial Index based on Motion Characteristic of Moving Objects)的移动空间对象索引结构,阐述了该索引结构的核心算法、构造方法、具体的数据存储方案,最后给出了该索引结构的试验分析结果。展开更多
Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determi...Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determined in six sizes of aggregates(>2,2-1,1-0.6,0.6-0.25,0.25-0.053,<0.053 mm).Significantly high(p<0.05)structural stability indexes(SSI)and ag-gregate stability indexes(ASI)were recorded in the topsoil horizon,which may be attributed to the high soil organic matter(SOM)content in aggregates from topsoil.In addition,ASI and SSI were positively correlated(r=0.569,p<0.05)with each other,which indicated that the stability of soil aggregates could contribute to the structural stability of bulk soil.Moreover,accumulation factors(AF),principal component analysis(PCA)and Pearson's correlation co-efficients were used for metal element assessment.The results indicated that SOM was not a key factor affecting the accumulation of Ca,Mg,Al,Fe,Mn,Pb,Cd and Cu in soil aggre-gates.In general,AF values for metal elements in microaggregates(<0.25 mm)were high,which showed that metals preferred to accumulate in fine soil aggregates.The PCA and Pearson's correlation coefficients indicated that soil parent materials primarily controlled the distribution of Al,Ca,Fe,Mg and Mn,while materials derived from technogenic sources have important impacts on the distribution of Cd,Cu and Pb in soil aggregates along the soil profile.展开更多
FTIR spectrum data can not only be used to indicate kerogen type and maturity, but also to determine organic facies of source rock. Aliphatic chain structure indices (ACSI) and an aromatic structure index (ASI) are in...FTIR spectrum data can not only be used to indicate kerogen type and maturity, but also to determine organic facies of source rock. Aliphatic chain structure indices (ACSI) and an aromatic structure index (ASI) are introduced to divide sedimentary organic facies of different source rocks into three types: swamp, swamp_lacustrine and lacustrine facies. The indices also reveal the fine difference of the organic matters, such as kerogen types, petroleum potential and nature of hydrocarbon products.展开更多
文摘由于实时跟踪移动的空间对象需要不断地查询和更新空间数据库的索引,经典R树空间索引结构的静态管理空间对象的方法并不适合移动环境,从而导致系统执行效率非常低下。根据对移动对象运动模式的分析,文中提出了一种称为ASI(Adaptive Spatial Index based on Motion Characteristic of Moving Objects)的移动空间对象索引结构,阐述了该索引结构的核心算法、构造方法、具体的数据存储方案,最后给出了该索引结构的试验分析结果。
基金This work was supported by the National Key Research and Development Project of China(No.2017YFD0800305).
文摘Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determined in six sizes of aggregates(>2,2-1,1-0.6,0.6-0.25,0.25-0.053,<0.053 mm).Significantly high(p<0.05)structural stability indexes(SSI)and ag-gregate stability indexes(ASI)were recorded in the topsoil horizon,which may be attributed to the high soil organic matter(SOM)content in aggregates from topsoil.In addition,ASI and SSI were positively correlated(r=0.569,p<0.05)with each other,which indicated that the stability of soil aggregates could contribute to the structural stability of bulk soil.Moreover,accumulation factors(AF),principal component analysis(PCA)and Pearson's correlation co-efficients were used for metal element assessment.The results indicated that SOM was not a key factor affecting the accumulation of Ca,Mg,Al,Fe,Mn,Pb,Cd and Cu in soil aggre-gates.In general,AF values for metal elements in microaggregates(<0.25 mm)were high,which showed that metals preferred to accumulate in fine soil aggregates.The PCA and Pearson's correlation coefficients indicated that soil parent materials primarily controlled the distribution of Al,Ca,Fe,Mg and Mn,while materials derived from technogenic sources have important impacts on the distribution of Cd,Cu and Pb in soil aggregates along the soil profile.
文摘FTIR spectrum data can not only be used to indicate kerogen type and maturity, but also to determine organic facies of source rock. Aliphatic chain structure indices (ACSI) and an aromatic structure index (ASI) are introduced to divide sedimentary organic facies of different source rocks into three types: swamp, swamp_lacustrine and lacustrine facies. The indices also reveal the fine difference of the organic matters, such as kerogen types, petroleum potential and nature of hydrocarbon products.
