Browsing by Author "Akcay, Mehmet Berkehan"

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    Article
    Citation - WoS: 4
    Citation - Scopus: 4
    All Colors Shortest Path Problem on Trees
    (Springer, 2018) Akcay, Mehmet Berkehan; Akcan, Hüseyin; Evrendilek, Cem
    Given an edge weighted tree T(V, E), rooted at a designated base vertex , and a color from a set of colors assigned to every vertex , All Colors Shortest Path problem on trees (ACSP-t) seeks the shortest, possibly non-simple, path starting from r in T such that at least one node from every distinct color in C is visited. We show that ACSP-t is NP-hard, and also prove that it does not have a constant factor approximation. We give an integer linear programming formulation of ACSP-t. Based on a linear programming relaxation of this formulation, an iterative rounding heuristic is proposed. The paper also explores genetic algorithm and tabu search to develop alternative heuristic solutions for ACSP-t. The performance of all the proposed heuristics are evaluated experimentally for a wide range of trees that are generated parametrically.
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    Review Article
    Citation - WoS: 406
    Citation - Scopus: 623
    Speech Emotion Recognition: Emotional Models, Databases, Features, Preprocessing Methods, Supporting Modalities, and Classifiers
    (Elsevier, 2020) Akcay, Mehmet Berkehan; Oguz, Kaya
    Speech is the most natural way of expressing ourselves as humans. It is only natural then to extend this communication medium to computer applications. We define speech emotion recognition (SER) systems as a collection of methodologies that process and classify speech signals to detect the embedded emotions. SER is not a new field, it has been around for over two decades, and has regained attention thanks to the recent advancements. These novel studies make use of the advances in all fields of computing and technology, making it necessary to have an update on the current methodologies and techniques that make SER possible. We have identified and discussed distinct areas of SER, provided a detailed survey of current literature of each, and also listed the current challenges.