The Research Of Time-Cost Trade-Off Optimization And Risk Analysis Under Activity Network

The research of time-cost trade-off optimization and risk analysis under activity network are core issues in the analysis of network technology. The goal of these issues is to apply the fewest resources to ensure that the project can be finished within the required duration and to make the decision-maker evaluate the completion probability more precisely. Through these researches, the decision-maker can improve their design ability in scheduling, resource constraint and risk analysis of activity network, which meaningfully lead to the efficient use of resources and avoid the emergency of project risk in modern project management.This thesis puts its emphasis on the research of time-cost trade-off optimization problem by the application of linear programming model when the principle of time-cost trade-off principle under activity network has been introduced. By analyzing the current situation and characters of risk analysis, it focuses on the study of risk analysis from the level of activities.Firstly, this thesis establishes the linear programming model of time-cost trade-off model under activity network based on its traditional steps. Besides that, the thesis develops a method to solve the proposed model. In relation to the slack theory and minimal flow principle, this method translates the duality problem of the original model to classical minimal flow problem, which can be solved by the available out-of-kilter methods. The algorithm is inserted to a large scale activity network because of its polynomial-time complexity.Secondly, the thesis studies on the risk analysis of activity network. Based on the Monte Carlo theory and project risk analysis principle, it develops the concept of Activity Critically Probability and Activity Critically Index, which is a new approach for managers to judge the criticality of an activity. Furthermore, the thesis brings forward the idea of Project Critically Index based on risk theory, which incorporates the criticality of all activities within an activity network and is in quantitative relationship to both Activity Critically Probability and Activity Critically Index. In addition, the thesis models an activity network and calculated its Activity Critically Probability, Activity Critically Index, and Project Critically Index based on Monte Carlo Simulation. The conclusion shows that the most critical activities designated by the Activity Critically Probability are unusually the bottleneck activities influencing the project duration, while the most critical activities determined by the Activity Critically Index should be focused in risk precaution and management. The project manager should combine both of these two concepts to evaluate the criticality of an activity network exactly. The result also shows that Project Critically Index is valuable in the comparison of different projects.Finally, the thesis discovers some questions which need to be further studied.