Research On Multi-objective Optimization Problem Of Resource Constraint Projects

Resource-constrained Project Multi-objective Optimization Problem aims to achieve the Pareto solution of multiple objective functions by optimizing schedule of project under the sequence and resource constraints.However,recently most researchers still focus more on the research on time–cost,time-robustness etc.rather than single-objective research.At the same time,the project scheduling problems have the natural characteristics of multi-objective,the project is often expected to achieve optimal multiple target item during construction process.Therefore the research of Resource-constrained Multi-objective Optimization Problem not only has important theoretical significance,but also has important practical application value.This paper expands single objective optimization problem of resource-constrained project to multi-objective optimization one and make innovation on resource leveling metric.The modeling and solving method of Resource-constrained Multi-objective Optimization Problem is studied based on the new resource leveling metric-NPC.The main research points and innovation are listed as follows:First of all,an innovative resource equilibrium metrics-Nonproductive Cost is put forward solve the problem on how to improve the efficiency of resource utilization and measure resources fluctuation problem directly.This metric can measure and minimize the unexpected resource fluctuation on the negative impact of construction productivity and cost of the project by taking a consideration of adopting two different resource usage strategy-resources idle(RID)and allow resource rehire and hire(RRH)whose unit costs are difference,which can directly measure and minimizing resource fluctuations.Second,Resource-constrained Project Multi-objective Optimization Model is constructed based on the Nonproductive Cost.Two objective functions is mainly considered: one is the objective to minimize the makespan,while the other one is used to minimize the resources leveling based on Nonproductive Cost metric.Finally,in view of the solution method to Multi-objective Optimization Model,the algorithm is improved to make it more suitable for resource-constrained project multi-objective optimization problem.In order to improve the NSGA-II algorithm,combined with the practical characteristics,an improved non dominated sorting genetic algorithm-the NSGA-II algorithm is designed based on chaos and differential evolution.Eventually,the rationality of the model and the effectiveness of the algorithm is testified by an application.