Browsing by Author "Kayış, Enis"
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A CART-based genetic algorithm for constructing higher accuracy decision trees
Ersoy, Elif; Albey, Erinç; Kayış, Enis (SciTePress, 2020)Decision trees are among the most popular classification methods due to ease of implementation and simple interpretation. In traditional methods like CART (classification and regression tree), ID4, C4.5; trees are constructed ... -
Delegation vs. control of component procurement under asymmetric cost information and simple contracts
Kayış, Enis; Erhun, F.; Plambeck, E. L. (Informs, 2013)A manufacturer must choose whether to delegate component procurement to her tier 1 supplier or control it directly. Because of information asymmetry about suppliers’ production costs and the use of simple quantity discount ... -
Demand and supply planning for Covid-19 vaccine in Turkey with an anti-vaccine survey
The Covid-19 virus, which affects many people, continues in a very contagious state. Vaccination is necessary to end this pandemic period, which everyone wants to end as soon as possible. The studies in the literature ... -
Digital oil refinery: utilizing real-time analytics and cloud computing over industrial sensor data
Khodabakhsh, Athar (2018-12-14)This thesis addresses big data challenges seen in large-scale, mission-critical industrial plants such as oil refineries. These plants are equipped with heavy machinery (boilers, engines, turbines, etc.) that are continuously ... -
Effective training methods for automatic musical genre classification
Atsız, Eren; Albey, Erinç; Kayış, Enis (SciTePress, 2019)Musical genres are labels created by human and based on mutual characteristics of songs, which are also called musical features. These features are key indicators for the content of the music. Rather than predictions by ... -
An extension to the classical mean–variance portfolio optimization model
Ötken, Çelen Naz; Organ, Zeynel Batuhan; Yıldırım, Elif Ceren; Çamlıca, Mustafa; Cantürk, Volkan Selim; Duman, Ekrem; Teksan, Zehra Melis; Kayış, Enis (Taylor & Francis, 2019-07)The purpose of this study is to find a portfolio that maximizes the risk-adjusted returns subject to constraints frequently faced during portfolio management by extending the classical Markowitz mean-variance portfolio ... -
A gradient descent based heuristic for solving regression clustering problems
Kayış, Enis (SciTePress, 2020)Regression analysis is the method of quantifying the effects of a set of independent variables on a dependent variable. In regression clustering problems, the data points with similar regression estimates are grouped into ... -
An investigation into mechanical and thermal characteristics of synthetic jet actuators with compact packaging
Işıl, Onuralp (2021-01-05)Cooling systems have been one of the most important elements in packaged electronics due to their inseparable relation with performance. Processors, light emitting diodes (LED), servers, advanced communication systems, ... -
A longitudinal model for song popularity prediction
Çimen, Ahmet; Kayış, Enis (SciTePress, 2021)Usage of new generation music streaming platforms such as Spotify and Apple Music has increased rapidly in the last years. Automatic prediction of a song's popularity is valuable for these firms which in turn translates ... -
N-hop influence maximization problem under deterministic linear threshold model
The Influence Maximization Problem (IMP) finds a set of highly influential nodes within a social network in order to maximize the spread of influence. We consider that people can have influence on their direct (1-hop), ... -
Next-day operating room scheduling with uncertain surgery durations: Exact analysis and heuristics
Khaniyev, T.; Kayış, Enis; Güllü, R. (Elsevier, 2020-10-01)Operating rooms are units of particular interest in hospitals as they constitute more than 40% of total expenses and revenues. Managing operating rooms is challenging due to conflicting priorities and preferences of various ... -
Parametric and non parametric models for stochastic next day operating room scheduling
Sevindik, Ömer Hikmet (2018-01)Operating rooms are the resources that generate the most part of the revenue of hospitals. On the other hand, they generate the most part of the expenses, as well. Because of the uncertainty of surgery durations, scheduling ... -
A real life operating room scheduling problem
Alper, Gülşah (2015-08)A real life operating room scheduling problem is studied using a data set from a leading hospital, Hospital X, in Turkey. After analyzing the real data, we solve daily operating room scheduling problems by mixed integer ... -
A robust estimation model for surgery durations with temporal, operational, and surgery team effects
Kayış, Enis; Khaniyev, T. T.; Suermondt, J.; Sylvester, K. (Springer Science+Business Media, 2015-09)For effective operating room (OR) planning, surgery duration estimation is critical. Overestimation leads to underutilization of expensive hospital resources (e.g., OR time) whereas underestimation leads to overtime and ... -
A robust longitudinal model for song popularity: a cross-cultural study
Çimen, Ahmet Can (2021-08-16)Usage of new generation music streaming platforms such as Spotify and Apple Music has increased rapidly in the last years. Understanding the music preferences of the user base is valuable for these firms, translating into ... -
Rolling look-ahead approaches for optimal classification trees
Classification trees have gained tremendous attention in machine learning applications due to their inherently interpretable nature. Current state-of-the-art formulations for learning optimal binary classification trees ... -
A smart cloud platform service for socialized travel and transportation with mobile support
Yazıcı, Yaprak Ayazoğlu (2013-09)It is now clear that social networking services are evolving towards mobile web applications and continuous location sharing is also becoming a trend. In this evolution, we believe that the next step will be complete and ... -
Solving a modified TSP problem by a greedy heuristic for cost minimization
Çal, Murat (2017-06)Photographing a large area in an instant is only made possible by satellites. Satellites are able to help reducing the time required for the photographing/monitoring process, however, satellite images are not available all ... -
Speaker adaptation with deep learning for text-to-speech synthesis systems
End-to-end (e2e) speech synthesis systems have become popular with the recent introduction of letter-to-spectrogram conversion systems, such as Tacotron, that use encoder-decoder-based neural architectures. Even though ... -
Stochastic scheduling of operating rooms and reusable medical devices: a simulation optimization approach
Farajkhah, Seyyed Kian (2019-08-08)Health care expenditures are expected to grow every year, and more than 40% of a hospital's total expenses and revenues are generated by surgical surgeries. One of the major resources required during surgeries are reusable ...
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