Now showing items 41-60 of 733

    • Structural results for average‐cost inventory models with Markov‐modulated demand and partial information 

      Avcı, Harun; Gökbayrak, Kağan; Nadar, Emre (Wiley-Blackwell, 2020)
      We consider a discrete‐time infinite‐horizon inventory system with non‐stationary demand, full backlogging, and deterministic replenishment lead time. Demand arrives according to a probability distribution conditional on ...
    • 4-generated pseudo symmetric monomial curves with not Cohen–Macaulay tangent cones 

      Şahin, Nil (TUBITAK, 2020)
      In this article, standard bases of some toric ideals associated to 4-generated pseudo symmetric semigroups with not Cohen-Macaulay tangent cones at the origin are computed. As the tangent cones are not Cohen-Macaulay, ...
    • Balance in resource allocation problems: a changing reference approach 

      Karsu, Özlem; Erkan, Hale (Springer, 2020)
      Fairness is one of the primary concerns in resource allocation problems, especially in settings which are associated with public welfare. Using a total benefit-maximizing approach may not be applicable while distributing ...
    • Lower cone distribution functions and set-valued quantiles form galois connections 

      Ararat, Çağın; Hamel, A. H. (SIAM, 2020)
      It is shown that a recently introduced lower cone distribution function, together with the set-valued multivariate quantile, generates a Galois connection between a complete lattice of closed convex sets and the interval ...
    • OM forum: innovative online platforms: research opportunities 

      Chen, Y.-J.; Dai, T.; Körpeoğlu, C. Gizem; Körpeoğlu, E.; Şahin, Ö.; Tang, C. S.; Xiao, S. (INFORMS: Institute for Operations Research and the Management Sciences, 2020)
      Economic growth in many countries is increasingly driven by successful startups that operate as online platforms. These success stories have motivated us to define and classify various online platforms according to their ...
    • Safety stock placement for serial systems under supply process uncertainty 

      Urlu, B.; Erkip, Nesim K. (Springer, 2020)
      In this study, we address safety stock positioning when demand per period is a known constant but supply is uncertain. The supply is either available or not available, while the setting is that of a periodically reviewed, ...
    • Codon optimization: A mathematical programing approach 

      Şen, Alper; Kargar, Kamyar; Akgün, E.; Pınar, Mustafa Ç. (Oxford University Press, 2020-04)
      Motivation: Synthesizing proteins in heterologous hosts is an important tool in biotechnology. However, the genetic code is degenerate and the codon usage is biased in many organisms. Synonymous codon changes that are ...
    • A thermo-mechanical model of drill margin-borehole surface interface contact conditions in dry drilling of thick CFRP laminates 

      Karpat, Yiğit; Karagüzel, U.; Bahtiyar, O. (Elsevier, 2020)
      Dry drilling of thick carbon fiber reinforced polymer (CFRP) laminates requires careful selection of process parameters in order to obtain acceptable borehole surface quality. Complex contact conditions between the drill ...
    • Multi-stage stochastic programming for demand response optimization 

      Şahin, Munise Kübra; Çavuş, Özlem; Yaman, Hande (Elsevier, 2020-02-19)
      The increase in the energy consumption puts pressure on natural resources and environment and results in a rise in the price of energy. This motivates residents to schedule their energy consumption through demand response ...
    • Codon optimization by 0-1 linear programming 

      Arbib, C.; Pınar, Mustafa Ç.; Rossi, F.; Tessitore, A. (Elsevier, 2020-02)
      The problem of choosing an optimal codon sequence arises when synthetic protein-coding genes are added to cloning vectors for expression within a non-native host organism: to maximize yield, the chosen codons should have ...
    • Competitive location and pricing on a line with metric transportation costs 

      Arbib, C.; Pınar, Mustafa Ç.; Tonelli, M. (Elsevier, 2020-04-01)
      Consider a three-level non-capacitated location/pricing problem: a firm first decides which facilities to open, out of a finite set of candidate sites, and sets service prices with the aim of revenue maximization; then a ...
    • An exact analysis on age-based control policies for perishable inventories 

      Poormoaied, S.; Gürler, Ülkü; Berk, E. (Taylor and Francis, 2020-09-01)
      We investigate the impact of effective lifetime of items in an age-based control policy for perishable inventories, a so-called (Q, r, T) policy, with positive lead time and fixed lifetime. The exact analysis of this control ...
    • Portfolio optimization with two coherent risk measures 

      Aktürk, T. D.; Ararat, Çağın (Springer, 2020)
      We provide analytical results for a static portfolio optimization problem with two coherent risk measures. The use of two risk measures is motivated by joint decision-making for portfolio selection where the risk perception ...
    • Minimizers of sparsity regularized huber loss function 

      Akkaya, Deniz; Pınar, Mustafa Ç. (Springer, 2020)
      We investigate the structure of the local and global minimizers of the Huber loss function regularized with a sparsity inducing L0 norm term. We characterize local minimizers and establish conditions that are necessary and ...
    • Sustainable transportation system design 

      Utku, İ. Y.; Çolak, M.; Özmısır, D.; Boz, A.; Aydoğdu, T.; Didiş, M. C.; Nadar, Emre (Springer, 2020)
      As reducing the carbon footprint became one of the topmost concerns of the firms, Company X Turkey has a goal of transforming all of its operations in environmentally sustainable manner. Therefore, they specified their ...
    • Review of the six-sigma methodology and its case studies 

      Çuhacı, Z. Gülce; Purutçuoğlu, V. (Selçuk University, 2011)
      The six-sigma is one of the most effective and recently developed business strategies to reduce process variability, keep on continuous improvement for the process, and to decrease cost and waste. Thanks to its popularity ...
    • Rasyonel bir maliyetlendirme sistemi risk faktörlerini göz önüne almalı; koroner anjiyografi paket fiyat uygulamasının değerlendirilmesi 

      Yılmaz, M. B.; Büyükkaramıklı, N. Çağdaş; Çakan, Nesrin; Kalem, Övgü; Karan, Sultan; Koçak, F. Orçun; Korkmaz, Ş.; Çobanoğlu, A. (Kare Yayıncılık, 2005)
      Paket fiyat uygulaması, diğer branşlarda olduğu gibi, kardiyovasküler hastalıkların tanı ve tedavisindeki işlemlere de uygulanmaktadır. Bu çalışmada, Türkiye Yüksek İhtisas Hastanesi Kardiyoloji Kliniği’nde uygulanan koroner ...
    • Tepe Mobilya' da hücresel üretimle teslimat sürelerinin kısaltılması 

      Bozkurt, C. Halil; Çınar, Yüce; Kayayurt, Bade; Sevinçli, Berna; Tamer, Ş. Okan; Usluoğlu, A. Deniz; Aktürk, M. Selim (TMMOB, 2006)
      Tepe Mobilya Fabrikası'nda döşemeli ürünlerin teslimat sürelerinin azaltılması fabrika ve ürünlerin satışlarını gerçekleştiren Tepe Home için büyük önem taşımaktadır. Bu projede fabrikanın hücresel üretime geçişi için bir ...
    • Toz deterjan için üretim planlama ve çizelgeleme sistemi tasarımı 

      Sepin, Tardu Selim; Yatkın, Mehmet Diyar; Eralp, Merve Nazlı; Memişoğlu, Gökhan; Taner, Mehmet Rüştü; Özcan, Mehmet; Akdemir, Deniz (TMMOB Makina Mühendisleri Odası, 2009)
      Unilever Gebze Fabrikasının toz deterjan üretimi planlama sürecinde çizelgeleme işlemi için karar destek sisteminin eksikliği, ürün değişikliklerinin neden olduğu kurulum sayısının ve fırsat maliyetlerinin artmasına sebep ...
    • Tüketici davranışlarının zamanla değiştiği kapalı devre tedarik zincirlerinde satış planı eniyilemesi 

      Nadar, Emre (Gazi Üniversitesi , Fen Bilimleri Enstitüsü, 2019)
      Bu çalışmada, yeni ve yeniden imal edilen olmak üzere iki farklı şekilde satılabilen ürünlerin satış planını eniyileme problemi ele alınmaktadır. Ürün talep eğrisi, literatürde yaygın olarak kullanılan ve gerçek verilerle ...