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试论简单随机抽样的随机原则 被引量:1
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作者 焦振勇 《统计与信息论坛》 2000年第4期19-21,共3页
抽样调查选择调查单位要遵守随机原则 ,这是抽样调查和其它非全面调查方法的重大区别。对于在抽样理论中随机原则的不同理解以及叙述 ,文章对目标总体与作业总体、不同抽样方法形成样本的形式阐述了随机原则的涵义。提出抽样调查抽选调... 抽样调查选择调查单位要遵守随机原则 ,这是抽样调查和其它非全面调查方法的重大区别。对于在抽样理论中随机原则的不同理解以及叙述 ,文章对目标总体与作业总体、不同抽样方法形成样本的形式阐述了随机原则的涵义。提出抽样调查抽选调查单位要遵守随机原则 ,保证总体每一单位进入样本的机会均等 ,而且总体每一单位第一次被抽中的机会也是均等的。 展开更多
关键词 抽样调查 随机原则 抽样方法 目标总体 作业总体
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Study on the general layout of semi-submersible offshore drilling platforms based on process flow 被引量:2
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作者 岳吉祥 綦耀光 +2 位作者 肖文生 杨磊 杨轶普 《Journal of Marine Science and Application》 2009年第2期117-122,共6页
The general layout of 6th generation semi-submersible drilling platforms is the main factor impacting the efficiency of their drilling operations. This paper provides a compound/integrated algorithm based on process f... The general layout of 6th generation semi-submersible drilling platforms is the main factor impacting the efficiency of their drilling operations. This paper provides a compound/integrated algorithm based on process flow that is aimed at improving efficiency, while giving attention to stability and safety at the same time. The paper describes the process flow of dual drilling centers and a hierarchical division of rigs based on the different modes of transportation of various drilling support systems. The general layout-centripetal overall arrangement spatially was determined based on drilling efficiency. We derived our modules according to drilling functionality; the modules became our basic layout units. We applied different layout algorithm to mark out the upper and lower decks. That is, the upper deck was designed based on the lowest transportation cost while the lower deck's calculations were based on the best-fit scope. Storage configurations in columns and pontoons were also considered for the layout design. Finally the center of gravity was taken into consideration and the general layout was adjusted accordingly, to result in an optimal center of gravity. The methodology of the general layout can provide a reference for implementation of domestic designs of semi-submersible rigs. 展开更多
关键词 semi-submersible drilling platform general layout drilling process flow layout optimization group technology
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