@article {1452, title = {Performance analysis of an aggregation and disaggregation solution procedure to obtain a maintenance plan for a partially observable multi-component system}, journal = {Reliability Engineering \& System Safety}, volume = {167}, year = {2017}, pages = {652-662}, abstract = {

We analyze the performance of an aggregation and disaggregation procedure in giving the optimal maintenance decisions for a multi-component system under partial observations in a finite horizon. The components deteriorate in time and their states are hidden to the decision maker. Nevertheless, it is possible to observe signals about the system status and to replace components in each period. The aim is to find a cost effective replacement plan for the components in a given time horizon. The problem is formulated as a partially observable Markov decision process (POMDP). We aggregate states and actions in order to reduce the problem space and obtain an optimal aggregate policy which we disaggregate by simulating it using dynamic Bayesian networks (DBN). The procedure is statistically compared to an approximate POMDP solver that uses the full state space information. Cases where aggregation performs relatively better are isolated and it is shown that k-out-of-n systems belong to this class.

}, keywords = {Aggregation, Disaggregation, Dynamic Bayesian networks, Maintenance, Multi-component systems, Partially observable Markov decision processes}, issn = {0951-8320}, doi = {https://doi.org/10.1016/j.ress.2017.04.013}, url = {https://www.sciencedirect.com/science/article/pii/S095183201730443X}, author = {Demet {\"O}zg{\"u}r-{\"U}nl{\"u}ak{\i}n and Taner Bilgi{\c c}} } @article {1174, title = {Innovation race under revenue and technology uncertainty of heterogeneous firms where the winner does not take all}, journal = {IIE Transactions}, volume = {48}, year = {2016}, pages = {527{\textendash}540}, author = {Taner Bilgi{\c c} and Refik G{\"u}ll{\"u}} } @article {guler2015joint, title = {Joint pricing and inventory control for additive demand models with reference effects}, journal = {Annals of Operations Research}, volume = {226}, number = {1}, year = {2015}, pages = {255{\textendash}276}, publisher = {Springer US}, author = {G{\"u}ler, M G{\"u}ray and Taner Bilgi{\c c} and Refik G{\"u}ll{\"u}} } @article {guler2014joint, title = {Joint inventory and pricing decisions when customers are delay sensitive}, journal = {International Journal of Production Economics}, volume = {157}, year = {2014}, pages = {302{\textendash}312}, publisher = {Elsevier}, author = {G{\"u}ler, M G{\"u}ray and Taner Bilgi{\c c} and Refik G{\"u}ll{\"u}} } @article {GBG2014a, title = {Joint inventory and pricing decisions with reference effects}, journal = {IIE Transactions}, volume = {46}, number = {4}, year = {2014}, pages = {330{\textendash}343}, publisher = {Taylor \& Francis Group}, author = {G{\"u}ler, M G{\"u}ray and Taner Bilgi{\c c} and Refi̇k G{\"u}ll{\"u}} } @article {ozgur2014replacement, title = {Replacement policies for a complex system with unobservable components using dynamic Bayesian networks}, journal = {International Journal of Computational Intelligence Systems}, volume = {7}, number = {sup1}, year = {2014}, pages = {68{\textendash}83}, publisher = {Taylor \& Francis}, author = {{\"O}zg{\"u}r-{\"U}nl{\"u}akin, Demet and Taner Bilgi{\c c}} } @inbook {bilgicc2013membership, title = {The Membership Function and Its Measurement}, booktitle = {On Fuzziness}, year = {2013}, pages = {47{\textendash}53}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, author = {Taner Bilgi{\c c}}, editor = {Seising R, Trillas E, Moraga C, Termini S} } @article {fas2013two, title = {A two-period dynamic game for a substitutable product inventory control problem}, journal = {International Journal of Inventory Research}, volume = {2}, number = {1-2}, year = {2013}, pages = {108{\textendash}126}, publisher = {Inderscience Publishers Ltd}, author = {Fas, Genco and Taner Bilgi{\c c}} } @inbook {bilgicc2010operational, title = {Operational Research Society of Turkey}, booktitle = {Wiley Encyclopedia of Operations Research and Management Science}, year = {2010}, publisher = {John Wiley \& Sons, Inc.}, organization = {John Wiley \& Sons, Inc.}, author = {Taner Bilgi{\c c} and Refik G{\"u}ll{\"u}} } @article {guler2009coordinating, title = {On coordinating an assembly system under random yield and random demand}, journal = {European Journal of Operational Research}, volume = {196}, number = {1}, year = {2009}, pages = {342{\textendash}350}, publisher = {Elsevier}, author = {G{\"u}ler, M G{\"u}ray and Taner Bilgi{\c c}} } @article {oner2008economic, title = {Economic lot scheduling with uncontrolled co-production}, journal = {European Journal of Operational Research}, volume = {188}, number = {3}, year = {2008}, pages = {793{\textendash}810}, publisher = {Elsevier}, author = {{\"O}ner, Selma and Taner Bilgi{\c c}} } @article {kayics2008note, title = {A note on the can-order policy for the two-item stochastic joint-replenishment problem}, journal = {IIE Transactions}, volume = {40}, number = {1}, year = {2008}, pages = {84{\textendash}92}, publisher = {Taylor \& Francis}, author = {Kayi{\c s}, Enis and Taner Bilgi{\c c} and Karabulut, Deniz} } @article {ccanakouglu2007analysis, title = {Analysis of a two-stage telecommunication supply chain with technology dependent demand}, journal = {European Journal of Operational Research}, volume = {177}, number = {2}, year = {2007}, pages = {995{\textendash}1012}, publisher = {North-Holland}, author = {Canako{\u g}lu, Ethem and Taner Bilgi{\c c}} }