Browsing by Author "Bilen, C."

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    Move based heuristics for the unidirectional loop network layout problem
    (Elsevier, 1998-07-01) Tansel, B. C.; Bilen, C.
    We consider the loop network layout problem in a manufacturing system where n machines must be placed in n available locations around a loop to minimize the total flow distance. The formulation of the problem results in a quadratic assignment problem which is computationally a very hard problem. We discuss the idea of positional moves and local improvement algorithms based on moves or k-way (particularly 2-way) interchanges. Even though the concept of moves has not found its way into algorithmic design in the existing literature, our computational experimentation with two-move based heuristics indicates uniformly superior performance in comparison to the well known pairwise interchange heuristic. © 1998 Elsevier Science B.V.
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    Rate-distortion optimized layered stereoscopic video streaming with raptor codes
    (IEEE, 2007) Tan, A. Serdar; Aksay, A.; Bilen, C.; Bozdağı-Akar, G.; Arıkan, Erdal
    A near optimal streaming system for stereoscopic video is proposed. Initially, the stereoscopic video is separated into three layers and the approximate analytical model of the Rate-Distortion (RD) curve of each layer is calculated from sufficient number of rate and distortion samples. The analytical modeling includes the interdependency of the defined layers. Then, the analytical models are used to derive the optimal source encoding rates for a given channel bandwidth. The distortion in the quality of the stereoscopic video that is caused by losing a NAL unit from the defined layers is estimated to minimize the average distortion of a single NAL unit loss. The minimization is performed over protection rates allocated to each layer. Raptor codes are utilized as the error protection scheme due to their novelty and suitability in video transmission. The layers are protected unequally using Raptor codes according to the parity ratios allocated to the layers. Comparison of the defined scheme with two other protection allocation schemes is provided via simulations to observe the quality of stereoscopic video.