Bilgisayar Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/45

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    Citation - WoS: 13
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    Contraction and Deletion Blockers for Perfect Graphs and H-Free Graphs
    (Elsevier Science, 2018) Diner, Öznur Yaşar; Paulusma, Daniel; Picouleau, Christophe; Ries, Bernard
    We study the following problem: for given integers d k and graph G can we reduce some fixed graph parameter pi of G by at least d via at most k graph operations from some fixed set S? As parameters we take the chromatic number chi clique number omega and independence number alpha and as operations we choose edge contraction ec and vertex deletion vd. We determine the complexity of this problem for S = {ec} and S = {vd} and pi is an element of{chi omega alpha} for a number of subclasses of perfect graphs. We use these results to determine the complexity of the problem for S = {ec} and S = {vd} and pi is an element of{chi omega alpha} restricted to H-free graphs. (C) 2018 Elsevier B.V. All rights reserved.
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    Citation - WoS: 2
    Citation - Scopus: 3
    The Effect of a Bump in an Elastic Tube on Wave Propagation in a Viscous Fluid of Variable Viscosity
    (Elsevier Science, 2007) Demiray, Hilmi
    In the present work treating the arteries as a thin walled prestressed elastic tube with a bump and the blood as a Newtonian fluid of variable viscosity we have studied the propagation of weakly nonlinear waves in such a medium by employing the reductive perturbation method in the longwave approximation. Korteweg-deVries-Burgers equation with variable coefficients is obtained as the evolution equation. Seeking a progressive wave type of solution to this evolution equation it is observed that the wave speed is variable. The numerical calculations show that the wave speed reaches to its maximum value at the center of the bump but it gets smaller and smaller as we go away from the center of the bump. Such a result seems to be reasonable from physical considerations. © 2006 Elsevier Inc. All rights reserved.