Two Types Of Time-cost Trade-off Models And Their Applications Under Uncertain Environments

In actual projects,the completion time and total cost,for projects' managers,are the two basic goals which are usually mutually restricted.So it is necessary for them to balance the above goals.In traditional time-cost trade-off problem researches,some parameters of the optimization models,like the duration of activity and the amount of resources,are usually described as constants.However,the uncertainty of these parameters can be affected by a variety of unanticipated uncertain factors.The uncertain chance constraint time-cost trade-off model and the uncertain resource constraint timecost trade-off model are constructed based on uncertainty theory and applied to the main body decoration project of the international data center in Hengqin new district,Zhuhai city,Guangdong province in order to verify the availability of the models.The main research contents and innovative work are as follows:(1)Taking into account the impact of uncertain factors on activity duration,two time-cost trade-off models with uncertain chance constraints are built.First of all,the duration of an activity is divided into normal duration and variable duration,in which the normal duration is assumed as an uncertain variable and the variable duration is defined as a decision variable.Secondly,according to different objectives of managers,two uncertain chance optimization models are constructed under the constraints of completing the project as soon as possible and spending as little as possible.Thirdly,the equivalent forms of the above two models are transformed and proved based on the operation laws of uncertain variables.Finally,the single objective genetic algorithm and the NSGA-? algorithm are designed to solve the models.(2)Considering the impact of uncertain factors on resource supply,the singlemode and the multi-mode uncertain resource time-cost trade-off models are constructed.Firstly,the increase amount of resource supply is assumed to be an uncertain variable,and the finish time of each activity is defined as a decision variable.An uncertain resource time-cost trade-off model is built of which the goal is to minimize the duration and cost under the constraints such as resource constraint,priority rules and execution modes.Secondly,the equivalent forms of the above models are transformed and proved based on the operation laws of uncertain variables.Finally,the NSGA-? algorithm is designed to solve the models.(3)By taking the main decoration project of international data center in Hengqin new district,Zhuhai city,Guangdong province as an example,the effectiveness of the above models is verified.Through the comparison of the results,the application scope,advantages and disadvantages of the models are given.The research of this paper will further expand the application scope of uncertainty theory and enrich the model and method of project management.Then the theoretical support and decision basis can be provided for managers to make scientific decision.