一类周期FC-群中的两种广义Frattini性质   总被引：1，自引：0，他引：1  

王伟 《成都信息工程学院学报》2008,23(1):101-103

设π是一个非空的素数集合。对任意群G,定义πFrattini子群为所有指数为π-数的极大子群的交,简记为πFrat（G）。得到如下结果：在任意局部π-可分的周期FC-群G中,设H为G的正规子群,如果H/πFrat（G）为局部π-幂零（局部π-超可解）,那么H为局部π-幂零（局部π-超可解）的。  相似文献   

嵌入式GIS中多尺度道路网路径规划方法的研究     

邹方磊  崔铁军 《测绘软科学研究》2008,(1):67-72

针对大区域路径规划问题,论述了道路层次划分模型和多尺度道路网数据库的建立,提出了构建多级道路网拓扑结构的方法,利用层次空间推理和改进的启发式A^＊算法进行最优路径的选取。  相似文献   

Geochemical characteristics of Holocene sediments from Chuadanga district,Bangladesh: Implications for weathering,climate, redox conditions,provenance and tectonic setting     

Ismail Hossain  Krisna Kanta Roy  Pradip Kumar Biswas  Mahbubul Alam  Md. Moniruzzaman  Farah Deeba 《中国地球化学学报》2014,33(4):336-350

The present research deals with the geochemical characteristics of the Holocene sediments from Alamdanga area, Chuadanga district, Bangladesh. Main goals of the study are to delineate source rock characteristics, degree of chemical weathering and sorting processes and behavior of redox conditions during deposition of the sediments. Geochemical characteristics of the sediments show comparatively a wide variation in accordance with stratigraphy in their major element contents （e.g. SiO2 69.46-82.13, A1203 2.28-8.88 in wt%）, reflecting the distinctive provenance and in part an unstable period in terms of tectonic activity. Geochemical classification of the sediments shows mostly sub-arkose with few sub-litharenites. Some major and trace elements display comprehensible correlation with A1203 confirming their possible hydraulic fraetionation. The chemical index of alteration （CIA＊）, W＊ index, index of compositional variability （ICV）, plagioclase index of alteration （PIA＊） values and the ratio of SIO2/Al2O3, suggest low degrees of chemical weathering in the source areas as well as immature to moderately mature the sediments. The sediments suggest semi-arid climatic trends within oxic deltaic depositional conditions during the Holocene, at 3-12 ka. Whole rock geochemistry and discrimination diagrams demonstrate the continental signature derivatives, which might have been derived from the felsic to intermediate igneous rocks （granitic plutonic rocks） as well as from quartzose sedimentary/metamorphic provenance. These typical sources are present in a vast region of the Himalayan belt and catchment areas of Ganges. The tectonic setting of the sediments demarcates typically passive margin with slightly continental arc system.  相似文献