摘要
PERT技术中工序作业时间是不确定的,因而需要求解不确定性工序时间的概率分布问题,这也是PERT应用的核心问题.为此本文将极大熵模型引入PERT中来.根据极大熵原理—熵达到最大并且满足约束条件的概率分布是偏差最小、最符合客观实际的,求解工序时间概率分布的关键问题就是寻找客观的约束条件.首先根据施工经验可假定工序作业时间的3个估计值(最大值、最小值、平均值),然后根据已知量建立可约束工序作业时间的条件,最后应用极大熵模型,通过数学运算,由客观的约束条件求解出工序作业时间概率分布问题.本文求解出的概率分布结果与数理统计中假设检验的求证结果一致,从而验证了PERT技术的概率分布假定是符合客观实际的.
In PERT(program evaluation and review technique) ,the process time is indefinite, so it is necessary to solve the probability distribution of process time, and to solve the problem is also the core of PERT. According to the maximum entropy rule--the result of probability distribution is in line with the truth, when the variable engages itself into certain conditions, and at the same time the entropy arrives the maximum, so it is crucial to find the restricted conditions. At first, find three values about the process time(the maximum,the minimum,the mean value) on the basis of construction experience; second, build the conditions to restrict the variable(process time) based on known quantities; at last, use the maximum entropy model and mathematics operation and transform the restricted conditions expressed by mathematics formulas to solve the problem of probability distribution. The result of probability distribution in the paper is consistent with outcome of Hypothesis test, so verify the assumption of PERT technology is objective.
出处
《中原工学院学报》
CAS
2006年第4期23-25,共3页
Journal of Zhongyuan University of Technology
关键词
熵
极大熵原理
计划评审技术
概率分布
entropy
the maximum entropy rule
program evaluation and rerie technique
probability distribution