Study Of Discounted Flow "Time-Cost" Model Considering Subcontract Payment And Ant Colony Optimization

The implementation of the construction project is a huge and complex system engineering,involving the impact of various factors.In order to make the project efficiently,favoringly and successfully complet,project managers need to schedule the project activities reasonably,actualizing the construction time,the project costs,and the amount of resources coordinate with each other,to achieve the best interests of the construction unit and create greater value for the community.In view of this problem,on the basis of summarizing and analyzing the current situation and development of the theory and method of engineering project management at home and abroad,this paper has made the following research on the resource-limited "time-cost" optimization problem:The model of Multi-mode Resourced-Constraints Times/cost Trade-offs Project Scheduling Problems,which makes the optimization goal for achieving the maximization of net present value,has comprehensively considered the cash flow of the activities in the process of project implementation,and calculated the inflow and outflow of funds for each activity to the initial moment of the project as a net profit for the activity.This model has a good guiding value for the management of the actual project.But in engineering practice,whereas the general contractor tends to subcontract the non-subject profession to the professional project construction unit,but the time cost of the subcontracting mode has not yet been received the attention of the researcher,furthermore the original model of the general contracting activities in the variable fee payment method is not reasonable enough,which does not meet the actual needs of the project site.For these reasons,this paper establish the IMRCTCTPDF model,and using the comparative analysis method to compare the results of the solution,accordingly to determine the best project optimization program.Ant colony algorithm in solving the combinatorial optimization problem,its unique population heuristic bionic evolutionary positive feedback parallel computing mechanism characteristics,providing the idea of solving the IMRCTCTPDF model for this paper.Based on the ant colony algorithm,and combined with the profit of time window to collect traveler problem solving method,this paper studies the similarities and differences between the traveling seller problem with the time windowand the IMRCTCTPDF problem.Accordingly,the theoretical basis of the model been solved optimization by the improved ant colony algorithm is discussed,and then to determine the improvement of the ant colony algorithm implementation steps,state transition probability formula and pheromone update formula.And design the improved ant colony algorithm program,preparing for the following example model to been optimized.Comparing the results in the literature,and analyzing the optimization results under different resource constraints,then discussing the difference between the net present value of the item when the subcontract is paid and the subcontract is not considered,and draws the conclusion that the net present value of the project when the subcontract payment has been considered is improved.That is,in the actual project scheduling on the subcontract payment time value of the consideration is a reference value.Therefore,the IMRCTCTPDF improved model proposed in this paper is engineering applicability.In summary,the optimization method of this paper provides an example for the optimization of project management in engineering practice.The research results enriched the project management theory and have important application value to the project management practice.