@article {1421, title = {Randomized trees for time series representation and similarity}, journal = {Pattern Recognition}, volume = {120}, year = {2021}, pages = {108097}, abstract = {

Most of the temporal data mining tasks require representations to capture important characteristics of time series. Representation learning is challenging when time series differ in distributional characteristics and/or show irregularities such as varying lengths and missing observations. Moreover, when time series are multivariate, interactions between variables should be modeled efficiently. This study proposes a unified, flexible time series representation learning framework for both univariate and multivariate time series called Rand-TS. Rand-TS models density characteristics of each time series as a time-varying Gaussian distribution using random decision trees and embeds density information into a sparse vector. Rand-TS can work with time series of various lengths and missing observations, furthermore, it allows using customized features. We illustrate the classification performance of Rand-TS on 113 univariate, 19 multivariate along with 15 univariate time series with varying lengths from UCR database. The results show that in addition to its flexibility, Rand-TS provides competitive classification performance.

}, keywords = {Classification, Random trees, Representation learning, Time series}, issn = {0031-3203}, doi = {https://doi.org/10.1016/j.patcog.2021.108097}, url = {https://www.sciencedirect.com/science/article/pii/S0031320321002843}, author = {Berk G{\"o}rg{\"u}l{\"u} and Mustafa Gokce Baydogan} } @article {1448, title = {The r-interdiction selective multi-depot vehicle routing problem}, journal = {International Transactions in Operational Research}, volume = {27}, year = {2020}, pages = {835-866}, abstract = {

Abstract The protection of critical facilities has been attracting increasing attention in the past two decades. Critical facilities involve physical assets such as bridges, railways, power plants, hospitals, and transportation hubs among others. In this study we introduce a bilevel optimization problem for the determination of the most critical depots in a vehicle routing context. The problem is modeled as an attacker{\textendash}defender game (Stackelberg game) from the perspective of an adversary agent (the attacker) who aims to inflict maximum disruption on a routing network. We refer to this problem as the r-interdiction selective multi-depot vehicle routing problem (RI-SMDVRP). The attacker is the decision maker in the upper level problem (ULP) who chooses r depots to interdict with certainty. The defender is the decision maker in the lower level problem (LLP) who optimizes the vehicle routes in the wake of the attack. The defender has to satisfy all customer demand either using the remaining depots or through outsourcing to a third party logistics service provider. The ULP is solved through exhaustive enumeration, which is viable when the cardinality of interdictions does not exceed five among nine depots. For the LLP we implement a tabu search heuristic adapted to the selective multi-depot VRP. Our results are obtained on a set of RI-SMDVRP instances synthetically constructed from standard MDVRP test instances.

}, keywords = {bilevel programming, interdiction, multi-depot vehicle routing problem, outsourcing, tabu search}, doi = {https://doi.org/10.1111/itor.12669}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/itor.12669}, author = {Sadati, Mir Ehsan Hesam and Aksen, Deniz and Necati Aras} } @article {1438, title = {Rectangle blanket problem: Binary integer linear programming formulation and solution algorithms}, journal = {European Journal of Operational Research}, volume = {277}, year = {2019}, pages = {62-83}, abstract = {

A rectangle blanket is a set of non-overlapping axis-aligned rectangles, used to approximately represent the two-dimensional image of a shape. The use of a rectangle blanket is a widely considered strategy for speeding-up the computations in many computer vision applications. Since neither the rectangles nor the image have to be fully covered by the other, the blanket becomes more precise as the non-overlapping area of the image and the blanket decreases. In this work, we focus on the rectangle blanket problem, which involves the determination of an optimum blanket minimizing the non-overlapping area with a given image subject to an upper bound on the total number of rectangles the blanket can include. This problem has similarities with rectangle covering, rectangle partitioning and cutting/packing problems. The image replaces an irregular master object by an approximating set of smaller axis-aligned rectangles. The union of these rectangles, namely, the rectangle blanket, is neither restricted to remain entirely within the master object, nor required to cover the master object completely. We first develop a binary integer linear programming formulation of the problem. Then, we introduce four methods for its solution. The first one is a branch-and-price algorithm that computes an exact optimal solution. The second one is a new constrained simulated annealing heuristic. The last two are heuristics adopting ideas available in the literature for other computer vision related problems. Finally, we realize extensive computational tests and report results on the performances of these algorithms.

}, keywords = {Branch-and-price, Computer vision, Cutting /Packing, Heuristics, integer programming}, issn = {0377-2217}, doi = {https://doi.org/10.1016/j.ejor.2019.02.004}, url = {https://www.sciencedirect.com/science/article/pii/S0377221719301158}, author = {Bar{\i}{\c s} Evrim Demir{\"o}z and I. Kuban Altinel and Lale Akarun} } @article {1442, title = {Robust supply chain network design with multi-products for a company in the food sector}, journal = {Applied Mathematical Modelling}, volume = {60}, year = {2018}, pages = {526-539}, abstract = {

The paper aims to solve a problem faced by a company competing in the snacks market in Turkey. In line with the growth in this market, the company needs to make important decisions over the next few years about the timing and location of a new plant, its initial capacity, the timing and amount of additional capacity to be installed at the new and existing plants, the assignment of demand points to plants and the amount of raw materials to be shipped from suppliers to the plants in each period. The objective is to minimize the total cost of various components. The problem is formulated as a multi-period supply chain network design model with multi products. The resulting mixed-integer linear programming model is solved by the commercial solver CPLEX. This model enables us to carry out all analyses requested by the company in an efficient way. After this deterministic model is solved on the basis of a 9\% annual increase in demand, it is extended to a minimax regret model to deal with uncertainty in demand quantities. The results suggest that opening the new plant in the city of {\.I}zmir is indeed a robust solution that is unaffected in different scenarios that are based on three distinct demand increase rates. Even though the location of the new plant remains unchanged with respect to scenarios, the optimal robust solution differs from the optimal solution of each scenario in terms of the capacity expansion decisions. After all obtained results had been communicated to the company managers and executives, the new plant construction was started in 2016 very close to the city that the mathematical model had determined. The new plant is expected to start operating in 2018.

}, keywords = {Demand uncertainty, Facility location-allocation, Mixed-integer linear programming, Robust optimization, Supply chain network design}, issn = {0307-904X}, doi = {https://doi.org/10.1016/j.apm.2018.03.034}, url = {https://www.sciencedirect.com/science/article/pii/S0307904X18301586}, author = {Necati Aras and {\"U}mit Bilge} } @proceedings {1183, title = {Recent results on equimatchable graphs}, journal = {Combinatorial Potlatch}, year = {2017}, author = {Ekim, Tinaz} } @article {1458, title = {Reliability and mean residual life functions of coherent systems in an active redundancy}, journal = {Naval Research Logistics (NRL)}, volume = {64}, year = {2017}, pages = {19-28}, abstract = {

Abstract In this article, the reliability and the mean residual life (MRL) functions of a system with active redundancies at the component and system levels are investigated. In active redundancy at the component level, the original and redundant components are working together and lifetime of the system is determined by the maximum of lifetime of the original components and their spares. In the active redundancy at the system level, the system has a spare, and the original and redundant systems work together. The lifetime of such a system is then the maximum of lifetimes of the system and its spare. The lifetimes of the original component and the spare are assumed to be dependent random variables. {\textcopyright} 2017 Wiley Periodicals, Inc. Naval Research Logistics, 64: 19{\textendash}28, 2017

}, keywords = {active redundancy, bivarite order statistics, coherent system, MRL functions, reliability function}, doi = {https://doi.org/10.1002/nav.21729}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/nav.21729}, author = {K{\"o}n{\"u}l Bayramo{\u g}lu Kavlak} } @article {1176, title = {Regional opportunities for China to go low-carbon: results from the REEC model}, journal = {The Energy Journal}, volume = {37}, year = {2016}, author = {Duan, Hongbo and Zhu, Lei and G{\"u}rkan Kumbaro{\u g}lu and Fan, Ying and others} } @article {1496, title = {Results of a beer game experiment: Should a manager always behave according to the book?}, journal = {Complexity}, volume = {21}, year = {2016}, pages = {190-199}, abstract = {

We investigate the effect of the literature suggested optimal values of the parameters of a dynamic decision-making heuristic in the presence of semirationally managed supply chain echelons using a soft coded one-to-one version of The Beer Game as an experimental platform. According to the counterintuitive results obtained in this study, it is possible for a {\textquotedblleft}rational manager{\textquotedblright} to obtain higher costs than the costs generated by a {\textquotedblleft}semirational manager.{\textquotedblright} Thus, the results do not support the use of the well-established decision parameter values for the echelon of concern if the other echelons{\textquoteright} inventories are managed suboptimally. {\textcopyright} 2015 Wiley Periodicals, Inc. Complexity 21: 190{\textendash}199, 2016

}, keywords = {anchor-and-adjust heuristic, artificial agents, beer game, stock management, supply chain management}, doi = {https://doi.org/10.1002/cplx.21731}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/cplx.21731}, author = {Edali, Mert and Yasarcan, Hakan} } @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}} } @article {becsikci2013resource, title = {Resource dedication problem in a multi-project environment}, journal = {Flexible Services and Manufacturing Journal}, volume = {25}, number = {1-2}, year = {2013}, pages = {206{\textendash}229}, publisher = {Springer}, author = {Be{\c s}ikci, Umut and {\"U}mit Bilge and Ulusoy, G{\"u}nd{\"u}z} } @article {1465, title = {Residual Lifetime of Consecutive $k$-out-of- $n$ Systems Under Double Monitoring}, journal = {IEEE Transactions on Reliability}, volume = {61}, year = {2012}, pages = {792-797}, doi = {10.1109/TR.2012.2206272}, author = {ERYILMAZ, SERKAN and K{\"o}n{\"u}l Bayramo{\u g}lu Kavlak} } @article {ekim2010recognizing, title = {Recognizing line-polar bipartite graphs in time O (n)}, journal = {Discrete Applied Mathematics}, volume = {158}, number = {15}, year = {2010}, pages = {1593{\textendash}1598}, publisher = {Elsevier}, author = {Ekim, Tinaz and Huang, Jing} } @article {1481, title = {A real options evaluation model for the diffusion prospects of new renewable power generation technologies}, journal = {Energy Economics}, volume = {30}, year = {2008}, pages = {1882-1908}, abstract = {

This study presents a policy planning model that integrates learning curve information on renewable power generation technologies into a dynamic programming formulation featuring real options analysis. The model recursively evaluates a set of investment alternatives on a year-by-year basis, thereby taking into account that the flexibility to delay an irreversible investment expenditure can profoundly affect the diffusion prospects of renewable power generation technologies. Price uncertainty is introduced through stochastic processes for the average wholesale price of electricity and for input fuel prices. Demand for electricity is assumed to be increasingly price-sensitive, as the electricity market deregulation proceeds, reflecting new options of consumers to react to electricity price changes (such as time-of-use pricing, unbundled electricity services, and choice of supplier). The empirical analysis is based on data for the Turkish electricity supply industry. Apart from general implications for policy-making, it provides some interesting insights about the impact of uncertainty and technical change on the diffusion of various emerging renewable energy technologies.

}, keywords = {Dynamic programming, Investment planning, Learning curve, Real options, Renewable energy technology diffusion, Turkey}, issn = {0140-9883}, doi = {https://doi.org/10.1016/j.eneco.2006.10.009}, url = {https://www.sciencedirect.com/science/article/pii/S0140988306001241}, author = {G{\"u}rkan Kumbaro{\u g}lu and Reinhard Madlener and Mustafa Demirel} } @article {eksioglu2004relative, title = {Relative optimum grip span as a function of hand anthropometry}, journal = {International Journal of Industrial Ergonomics}, volume = {34}, number = {1}, year = {2004}, pages = {1{\textendash}12}, publisher = {Elsevier}, author = {Mahmut Ek{\c s}io{\u g}lu} } @article {14552513, title = {{Reducing the integrality gap with a modified re-formulation linearization approach}}, journal = {Computers \& Chemical Engineering}, volume = {23}, year = {1999}, doi = {10.1016/S0098-1354(99)80133-1}, author = {Seza Or{\c c}un and I. Kuban Altinel and {\"O}ner Horta{\c c}su} } @article {1489, title = {Rescheduling on a single machine with part type dependent setup times and deadlines}, journal = {Annals of Operations Research}, volume = {70}, year = {1997}, month = {Jan}, pages = {93{\textendash}113}, issn = {02545330}, author = {Ali Tamer {\"U}nal and Uzsoy, Reha and Kiran, Ali} } @article {Hoermann;Derflinger:1996a, title = {Rejection-Inversion to Generate Variates from Monotone Discrete Distributions}, journal = {ACMTOMACS}, volume = {6}, number = {3}, year = {1996}, pages = {169{\textendash}184}, keywords = {monotone discrete distributions, Poisson distribution, random number generation, rejection-inversion, T-concave, universal algorithm, Zipf distribution}, author = {Wolfgang H{\"o}rmann and Derflinger, Gerhard} } @article {Hoermann:1995a, title = {A Rejection Technique for Sampling from {T}-Concave Distributions}, journal = {ACMTOMS}, volume = {21}, number = {2}, year = {1995}, pages = {182{\textendash}193}, keywords = {black box, log-concave, nonuniform RNG, rejection algorithm, rejection method, T-concave, t-distribution, transformed density rejection, unimodal distributions}, author = {Wolfgang H{\"o}rmann} }