Optimization Method For Project Scheduling And Multi-skilled Workforce Allocation

Effective project management is an important way to improve enterprise competitiveness,and the core contents are project planning,scheduling and control.Project scheduling is the activity that research and solve how to arrange the resources according to the time to achieve the predetermined optimization objectives.Resource-constrained project scheduling problem(RCPSP)is a kind of important problem in scheduling problem.It requires that meeting the project schedule constraints and resource constraints,and arranges the starting time of the task to achieve the optimal objectives,such as the minimum makespan period,the lowest cost,resource balance,maximum net present value,etc.In theory,RCPSP belongs to NP-hard problem,and the models are rich.Many combinatorial optimization problems are special cases of RCPSP,such as flow shop scheduling problem,machine scheduling problem,etc.Therefore,the study of RCPSP not only meets the needs of reality but also has theoretical significance.Based on the analysis and reviews of the related research results,this paper studys RCPSP and its extension problems.The main research contents and achievements of this paper are as follows:(1)A Memetic algorithm(MA)for RCPSP is proposed.The MA employs the task list representation,makes use of one-point crossover as recombination operator and five local search procedures to improve each off-spring individual.A detailed computational experiment is set up using standard instances sets J30,J60 and J120 from the problem instance library PSPLIB.Computational results show that,the proposed MA has stronger competitiveness.(2)A MA for the multi-mode resource-constrained project scheduling problem(MRCPSP)is proposed.A new fitness function and two very effective local search procedures are proposed in this paper.The fitness function makes use of a mechanism called "strategic oscillation" to make the search process have a higher probability to visit solutions around a"feasible boundary".One of the local search procedures aims at improving the lower bound of project makespan to be less than a known upper bound,and the other aims at improving the solutions of MRCPSP.A detailed computational experiment is set up using instances from the problem instance library PSPLIB.Computational results show that the proposed MA is very competitive with the state-of-the-art algorithms.The MA obtains improved solutions for one instance of set J30.(3)According to the characteristics of the project scheduling problems with multi-skilled workforce constraints(PSPMSWC)a two-stage heuristic algorithm is proposed,which is based on "tasks-skills-workforce" three layers and the goal is to get the minimum makespan.The algorithm provides different choices to the same problem,and the computational results show that the algorithm is satisfactory.(4)According to the characteristics of PSPMSWC a rule-based Memetic algorithm(PRBMA)is proposed.The performance of the algorithm is tested using large number of simulation instances,and the experimental results are compared with CPLEX and several rule-based heuristic algorithms.Results show that combining the strength of MA with rules can get the near optimal solution of the project scheduling problem and workforce assignment effectively.(5)According to the characteristics of multi-project scheduling problems with multi-skilled workforce constraints problem,a mixed-integer program model aiming at minimuzing the total workforce cost is established.Several groups of simulation instances are designed in the test experiment,and are solved by using CPLEX.The experimental results verify the validity of the model.(6)From the perspectives of MRO(maintenance,repair and overhaul)service provider,the optimal problem of scheduling multi-skilled workforce working for customers'equipments is studied.An optimization model of scheduling multi-skilled workforce is established to get the minimum total maintenance cost and the model is a nonlinear integer programming model.According to the characteristics of the variables,the nonlinear model is linearized.The practicability and performance of the model are tested by the simulation experiments with different parameters.The research results of this paper not only extends the research field of RCPSP,but also have some guidance to the project management.