计划评审技术（Program Evaluation and Review Technique，简称PERT）是项目进度管理的一项常用技术。在编制项目进度计划时，当项目的某些工作任务或者所有工作任务的历时估算事先不能完全肯定时，常常需要综合运用关键路径法和加权...计划评审技术（Program Evaluation and Review Technique，简称PERT）是项目进度管理的一项常用技术。在编制项目进度计划时，当项目的某些工作任务或者所有工作任务的历时估算事先不能完全肯定时，常常需要综合运用关键路径法和加权平均历时估算法来对项目历时进行估算。这种方法通常选取三组事先估算的数据：最乐观或最短的时间、最悲观或最长的时间、最有可能的时间，然后加权平均，从而得到完成该任务需要的时间。这种网络分析技术适用于那些不可预知因素较多，展开更多
A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of fl...A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly,the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacityflow rates are pretreated; Secondly, several rules are proposed to establish the superstructuremodel of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly,the improving genetic algorithm is applied to solve the mathematical model established at the secondstep effectively, and the original optimal structure of HEN based on the maximum operation limitingcondition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat loadof heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operationcondition between the upper and down bounds of supply temperature and heat capacity flow rates canbe obtained based on the original optimal structure of HEN by means of these rules. A case studydemonstrates the method presented in this paper is effective展开更多
The use of social network analysis to examine the behavior of social animals has grown rapidly in the past decade. Highly accessible books introducing network analysis techniques to the animal behavior research commun...The use of social network analysis to examine the behavior of social animals has grown rapidly in the past decade. Highly accessible books introducing network analysis techniques to the animal behavior research community （Croft et al., 2008; Whitehead, 2008） provide a gateway to the field. Furthermore, periodical reviews outlining the progress of the field and introducing both new biological questions and new analysis techniques （Krause et al., 2007; Wey et al., 2008; Sih et al., 2009; Croft et al,, 2011; Blonder et al., 2012; McDonald and Shizuka, 2013; Pinter-Wollman et al., 2014） fertilize the growth of the use of social network analysis to study animal social behavior.展开更多
文摘计划评审技术（Program Evaluation and Review Technique，简称PERT）是项目进度管理的一项常用技术。在编制项目进度计划时，当项目的某些工作任务或者所有工作任务的历时估算事先不能完全肯定时，常常需要综合运用关键路径法和加权平均历时估算法来对项目历时进行估算。这种方法通常选取三组事先估算的数据：最乐观或最短的时间、最悲观或最长的时间、最有可能的时间，然后加权平均，从而得到完成该任务需要的时间。这种网络分析技术适用于那些不可预知因素较多，
基金Supported by the State Major Basic Research Department Program of China (No. G20000263) and the Deutsche Forschungs- gemeinschaft(DFG)(No. RO294/9).
文摘A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly,the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacityflow rates are pretreated; Secondly, several rules are proposed to establish the superstructuremodel of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly,the improving genetic algorithm is applied to solve the mathematical model established at the secondstep effectively, and the original optimal structure of HEN based on the maximum operation limitingcondition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat loadof heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operationcondition between the upper and down bounds of supply temperature and heat capacity flow rates canbe obtained based on the original optimal structure of HEN by means of these rules. A case studydemonstrates the method presented in this paper is effective
文摘The use of social network analysis to examine the behavior of social animals has grown rapidly in the past decade. Highly accessible books introducing network analysis techniques to the animal behavior research community （Croft et al., 2008; Whitehead, 2008） provide a gateway to the field. Furthermore, periodical reviews outlining the progress of the field and introducing both new biological questions and new analysis techniques （Krause et al., 2007; Wey et al., 2008; Sih et al., 2009; Croft et al,, 2011; Blonder et al., 2012; McDonald and Shizuka, 2013; Pinter-Wollman et al., 2014） fertilize the growth of the use of social network analysis to study animal social behavior.
