为解决传统聚类算法构建工况初始中心易陷入局部最优、执行时耗长的问题,提出了一种改进全局k均值聚类(improved global k-means clustering,IGKM)算法,以缩小作为候选下一簇的初始中心点集,减少算法的迭代次数;采用小波分层阈值降噪和...为解决传统聚类算法构建工况初始中心易陷入局部最优、执行时耗长的问题,提出了一种改进全局k均值聚类(improved global k-means clustering,IGKM)算法,以缩小作为候选下一簇的初始中心点集,减少算法的迭代次数;采用小波分层阈值降噪和小波分解域量化压缩对原始数据进行预处理,结合改进主成分分析(improved principal component analysis,IPCA)对片段进行降维和分类;最后,合成汽车行驶工况。实验结果表明,所提方法构建行驶工况的速度-加速度联合分布差异值仅为0.87%,聚类平均耗时仅为83.35 s,行驶工况拟合度较高,更能综合反映实际车辆的运行状况。展开更多
Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic ...Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence （LHS） of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite- slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic-Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here： （1） the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; （2） the older deformation and metamorphism relate to a Pacific type accretionary orogen which affected the northern margin o展开更多
文摘为解决传统聚类算法构建工况初始中心易陷入局部最优、执行时耗长的问题,提出了一种改进全局k均值聚类(improved global k-means clustering,IGKM)算法,以缩小作为候选下一簇的初始中心点集,减少算法的迭代次数;采用小波分层阈值降噪和小波分解域量化压缩对原始数据进行预处理,结合改进主成分分析(improved principal component analysis,IPCA)对片段进行降维和分类;最后,合成汽车行驶工况。实验结果表明,所提方法构建行驶工况的速度-加速度联合分布差异值仅为0.87%,聚类平均耗时仅为83.35 s,行驶工况拟合度较高,更能综合反映实际车辆的运行状况。
文摘Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence （LHS） of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite- slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic-Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here： （1） the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; （2） the older deformation and metamorphism relate to a Pacific type accretionary orogen which affected the northern margin o
