基于工序逻辑关系的关键链缓冲确定方法研究

Buffer Sizing of Critical Chain Based on Activities’ Precedence Relationships

经典关键链缓冲确定研究假设,项目工序只有在紧前工序完成后才能开始,且立即开始,没有考虑不同逻辑关系对缓冲确定的影响。为确定合理有效的缓冲尺寸,本文基于工序间逻辑关系进行安全时间估计和缓冲大小调整。以PERT中的三时估计法为基础,提取工序中的安全时间;按照不同逻辑关系的特点,对工序间的时距提取安全时间。通过综合改进资源紧张度、搭接网络复杂度和相邻工序联系度3个影响因子对缓冲进行调整。使用Matlab软件进行案例仿真,将本文方法与经典方法进行比较分析。研究结果表明,与根方差法相比,本文方法可使项目工期缩短9.01%,成本减少5.18%。

The classical study of critical chain buffer determination assumes that the activity can only be started immediately after the preceding activity is completed, without considering the influence of different precedence relations on buffer determination. In order to determine the reasonable and effective buffer size, the safe time estimation and buffer size adjustment are carried out based on activities’ precedence relationships. Firstly, the safe time in the activity is extracted based on the three-point estimation method in PERT;according to the characteristics of different precedence relations, the safe time is extracted from the time interval between activities. Secondly, the buffer is adjusted by the improved resource tension, the complexity of lap network and the connection degree of adjacent activities. Finally, Matlab software is used for case simulation, and the proposed method is compared with the classical method. The results show that compared with the root-variance method, the proposed method can shorten the project duration by 9.01% and reduce the cost by 5.18%.