A survey of variants and extensions of the resource-constrained project scheduling problem <s> Further Activity Concepts <s> In this paper we present three new models for the resource constrained project scheduling problem, using two objective functions: minimizing the makespan and maximizing the net present value of the cash flows of the activities. In these models, compared to the models in the literature, we relax one of the most constraining assumptions about the integrality of the activity durations and the project time line. Furthermore resources are assumed to be partially-renewable. These models have multiple uses in Operations Management in that they can be used to solve resource constrained MRP problems. The models are found to be amenable to solution using the Optimization Subroutine Library (OSL). Extensive computational experiments with OSL on a total of 1400 problems with different parameter settings are reported. Detailed analysis is done to determine the factors that affect the computational efficiency of the code and the models. In general, results demonstrate that OSL is a powerful tool for solving the models with either objective function. Optimal solutions are obtained with reasonable computational effort. A discussion of the application of several special features of OSL is also given. <s> BIB001 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Further Activity Concepts <s> Abstract Project scheduling has long been an area of intensive research, but until recently most efforts have been dedicated to developing solution procedures and generalizing models, with little work done on generating problem instances. Additionally, if labor time regulations have to be taken into consideration, the classical resource-constrained project scheduling problem (RCPSP) cannot be used for many problems in manpower scheduling. This paper introduces several extensions to the RCPSP aimed at modeling such problems, and a problem instance generator based on the project generator ProGen incorporating these extensions. Thus, it becomes possible to thoroughly test solution procedures for, e.g., audit-staff scheduling, crew scheduling and timetabling problems. Preliminary computational results are given that were obtained with a greedy randomized solution method using priority rules specifically tailored to the generalized model. <s> BIB002 </s> A survey of variants and extensions of the resource-constrained project scheduling problem <s> Further Activity Concepts <s> One of the most difficult tasks in a job shop manufacturing environment is to balance schedule and capacity in an ongoing basis. MRP systems are commonly used for scheduling, although their inability to deal with capacity constraints adequately is a severe drawback. In this study, we show that material requirements planning can be done more effectively in a job shop environment using a resource constrained project scheduling model. The proposed model augments MRP models by incorporating capacity constraints and using variable lead time lengths. The efficacy of this approach is tested on MRP systems by comparing the inventory carrying costs and resource allocation of the solutions obtained by the proposed model to those obtained by using a traditional MRP model. In general, it is concluded that the proposed model provides improved schedules with considerable reductions in inventory carrying costs. <s> BIB003
Drexl et al. BIB002 introduce the concept of forbidden periods. Each activity is associated with a set of periods in which the activity may not be carried out. In the classical RCPSP, the activity durations are assumed to be integer-valued. Icmeli and Rom BIB001 and Rom et al. BIB003 allow the durations to be continuous. They present a mathematical model with a continuous timeline that is not partitioned into periods of equal length.