Akademik Veri Yönetim Sistemi
International IDU Engineering Symposium, İzmir, Türkiye, 15 - 17 Kasım 2023, ss.2
The manufacturing system of seismic
isolators has a project-based production process and therefore, it is generally
required to prepare a project plan or schedule for their production under
restricted resources such as machinery and manpower as well as uncertainty.
Based on this motivation, a well-known project scheduling problem in the
literature, which is named a single-mode resource-constrained project
scheduling (RCPS) problem is investigated in this study for the production
project of seismic isolators in large-sized manufacturing company. First, a
deterministic optimization model which is formulated as an integer program is
presented to solve the examined problem under certain environments. Then, the
uncertainties in the activity durations and the resource capacities (or
availabilities) are also considered by making use of hybridizing the fuzzy
mathematical programming and scenario-based stochastic programming approaches.
In addition to these uncertain project parameters/inputs, the project schedules/outputs
(i.e., completion times of the activities) are also considered as uncertain
decision variables and represented by triangular fuzzy numbers. First, the
previously mentioned deterministic optimization model is solved separately for
each scenario and then, its optimization results are also compared to the
results of a constraint programming model. Therefore, it is proven that both of
the integer programming and constraint programming models are able to generate
the same optimization results within reasonable computing times. Afterwards, a
fuzzy-stochastic programming model that integrates all of these scenarios
(i.e., pessimistic, most likely, and optimistic cases) in a single optimization
model is also formulated and then converted into its crisp equivalent form to
minimize the expected value of the total project duration (i.e., makespan) and to
obtain fuzzy project schedules under different probability values of these
scenarios. Therefore, different types of uncertainties can be handled
simultaneously by making use of this fuzzy-stochastic program. Finally, the
computational study has shown that efficient fuzzy-stochastic optimization
results/project schedules can be provided via the proposed fuzzy-stochastic
programming approach. Moreover, the generated fuzzy completion times of the
project activities are presented to the production project managers of the
seismic isolator manufacturing company for providing managerial insights.