The Optimization Method Of Network Planning With Optional Active Path

Network planning technique is a very effective scientific method in project planning and management. Traditional critical path method assumes each activity duration of network planning is a known determined value. But in many cases the actual project, the duration of the activitie is uncertain. Using the critical path method can not solve this problem. Program evaluation and review technique solve the weighted average time or expectation of duration using theory of probability and statistics. This calculation is quite complex. The uncertainty of project duration has fuzzy features. Fuzzy network planning technique applies fuzzy theory into the duration of the activities planned of network planning for the calculation. It is very important value in theory and in application.According to fuzzy features of the duration in network planning, contradiction between time parameters during fuzzy network planning calculation analysed in this paper. Because of network topology, there is some inherent relativity between processes. It has some independent requirement of activity's time parameters during fuzzy network planning calculation. In response to this contradiction, a new method is given and a model of fuzzy network planning is built to the new definitions of fuzzy number operations, which fuzzy number is quantized and comparison principle of the size of fuzzy numbers is given. An algorithm to computing the duration's membership function and the criticalities of paths in fuzzy network planning is presented. This algorithm seek for the fuzzy cut of activities by using fuzzy decomposition theorem, converts the fuzzy network to a series of interval network. Based on the cut of the total, membership function of the fuzzy total duration is constructed. Using the key between critical path of interval network and critical degree of the fuzzy network path, a method of calculating critical degree of the path is proposed, and a example for verifying feasibility of the method is presented.In addition, in order to play the fuzzy network planning in project management advantages more splendid, time-cost optimization of fuzzy network planning is researched in this paper. A fuzzy optimal model of duration-cost by integrating fuzzy theory and genetic algorithms is proposed in this paper. The duration is described by fuzzy numbers, an acceptable level of risk is given as a minimum condition to choose fuzzy numbers and find the optimal or approximate optimal solution in the fuzzy solution set using the genetic algorithm. An example for verifying feasibility of the method is presented.