Mekatronik Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/255

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  • Conference Object
    Citation - Scopus: 2
    An Optimization Model To Coordinate Scheduling and Controling in Projects: Case With Instantaneous Control Constraints
    (National Technical University of Athens, 2014) Schmıdt, Klaus Werner; Hazir, Ö.; Schmidt, K.W.; Eryilmaz, U.; Mekatronik Mühendisliği
    Today, many enterprises in different industries take part in various projects, and organizational performances depend more and more on project performances. In order to maximize performance, effective management of project functions is crucial. In this regard, we focus on scheduling and control functions and their relation. Characteristics of data sharing among them and possible integration strategies are theoretically investigated. A model base for a decision support framework that accounts for these interdependencies and supports managers is developed. To solve the formulated integrated project scheduling and control problem, a tabu search algorithm is combined with optimal control techniques. As a result, a project schedule as well as the means and timing of interventions are determined such that the project cost is minimized. The obtained results are supported by computational experiments. Integrated models and algorithms to be developed aim to fill an important theoretical gap in project management.
  • Article
    Citation - WoS: 102
    Robust Scheduling and Robustness Measures for the Discrete Time/Cost Trade-Off Problem
    (Elsevier Science Bv, 2010) Hazir, Oencue; Haouari, Mohamed; Erel, Erdal
    Projects are often subject to various sources of uncertainties that have a negative impact on activity durations and costs. Therefore, it is crucial to develop effective approaches to generate robust project schedules that are less vulnerable to disruptions caused by uncontrollable factors. In this paper, we investigate the robust discrete time/cost trade-off problem, which is a multi-mode project scheduling problem with important practical relevance. We introduce surrogate measures that aim at providing an accurate estimate of the schedule robustness. The pertinence of each proposed measure is assessed through computational experiments. Using the insights revealed by the computational study, we propose a two-stage robust scheduling algorithm. Finally, we provide evidence that the proposed approach can be extended to solve a complex robust problem with tardiness penalties and earliness revenues. (C) 2010 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 65
    Citation - Scopus: 67
    Robust Optimization Models for the Discrete Time/Cost Trade-Off Problem
    (Elsevier Science Bv, 2011) Hazir, Oncu; Erel, Erdal; Gunalay, Yavuz
    Developing models and algorithms to generate robust project schedules that are less sensitive to disturbances are essential in today's highly competitive uncertain project environments. This paper addresses robust scheduling in project environments; specifically, we address the discrete time/cost trade-off problem (DTCTP). We formulate the robust DTCTP with three alternative optimization models in which interval uncertainty is assumed for the unknown cost parameters. We develop exact and heuristic algorithms to solve these robust optimization models. Furthermore, we compare the schedules that have been generated with these models on the basis of schedule robustness. (C) 2010 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 10
    Citation - Scopus: 10
    An Integrated Scheduling and Control Model for Multi-Mode Projects
    (Springer, 2013) Hazir, Oncu; Schmidt, Klaus Werner
    In today's highly competitive uncertain project environments, it is of crucial importance to develop analytical models and algorithms to schedule and control project activities so that the deviations from the project objectives are minimized. This paper addresses the integrated scheduling and control in multi-mode project environments. We propose an optimization model that models the dynamic behavior of projects and integrates optimal control into a practically relevant project scheduling problem. From the scheduling perspective, we address the discrete time/cost trade-off problem, whereas an optimal control formulation is used to capture the effect of project control. Moreover, we develop a solution algorithm for two particular instances of the optimal project control. This algorithm combines a tabu search strategy and nonlinear programming. It is applied to a large scale test bed and its efficiency is tested by means of computational experiments. To the best of our knowledge, this research is the first application of optimal control theory to multi-mode project networks. The models and algorithms developed in this research are targeted as a support tool for project managers in both scheduling and deciding on the timing and quantity of control activities.