Research On Fuzzy Network Planning Technique

Network planning technique is an effective tool in project planning and control. There are many uncertain and unforeseen factors in project management. There appear many problems and limitations when traditional network planning technique is applied in the analysis of network progress chart. Critical path method assumes that activities in the network planning have determinate duration. Indeed, the duration of activity in the project is fuzzy number. Program evaluation and review technique suppose the duration to obey certain probability distribution, but it cannot be proved precisely by mathematics. Because of the fuzzy characteristic of the duration, it is necessary to solve the problem with the help of fuzzy set theory. There have been some efforts in using fuzzy set theory in network planning to make it more realistic and better dealing with uncertainties that is intrinsic in estimating duration of activities. Consequently, the application of fuzzy network planning technique in project is researched.Firstly, based on analysis of contradiction between inherent relativity of network topology structure and independent requirement of activity's time parameters during fuzzy network planning calculation, a new method is applied to the new definitions of fuzzy number operations, which first converts fuzzy parameters to determinate ones and then puts forward the principle of judging the size of two fuzzy numbers. A new fuzzy network planning model is proposed in contrast with existing models. With the help of Visual C++ program, functions of the model are realized which include time parameters calculation, criticality analysis and project period analysis.Secondly, based on analysis of network planning under influence of the potential uncertain factors in the project, the method of building the membership function of fuzzy critical path is presented, the relationship between fuzzy critical paths and fuzzy uncritical paths is built, and the new definitions of probable fuzzy critical path are presented. In order to solve the problems of complicated processes and tremendous calculation, two new methods of finding fuzzy critical path are given, which can obtain the fuzzy critical path and probable fuzzy critical path quickly and efficiently.Finally, the dynamic characteristics of fuzzy network planning are researched. Considering the threefold representation of activity time parameters under normal circumstance, exception circumstance and abnormal circumstance, a new expression of activity time parameters is put forward, which synthetically take one thing with another.