WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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1995 - 199952000 - 2009197

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Now showing 1 - 10 of 202
  • Conference Object
    Problem of Cracked Infinite Hollow Cylinder With Two Rigid Inclusions
    (Civil Comp Press, 2000) Artem, HSA; Gecit, MR
    This paper is concerned with the fracture of an axisymmetric hollow cylindrical bar containing rigid inclusions. The cylinder is under the action of uniformly distributed axial tension applied at infinity. The hollow cylinder contains a ring-shaped crack at the symmetry plane whose surfaces are free of tractions and two ring-shaped rigid inclusions with negligible thickness symmetrically located on both sides of the crack. Geometry and the loading is symmetric about z-axis. Along the rigid inclusions displacements are constant and continuous whereas stresses have jumps. The inner and the outer surfaces of the cylinder are free of tractions It is assumed that the material of the cylinder is linearly elastic and isotropic. The mixed boundary conditions of the problem lead the analysis to a system of three singular integral equations for crack surface displacement derivative and normal and shear stress jumps on rigid inclusions. These integral equations are solved numerically and the stress intensity factors at the edges of the crack and at the edges of the inclusions are calculated. Results are presented in graphical form.
  • Conference Object
    Nanoscale Surface Modification of Ultrahigh Molecular Weight Polyethylene (UHMWPE) Samples With the W Plus C Ion Implantation
    (Materials Research Soc, 2007) Urkac, E. Sokullu; Oztarhan, A.; Tihminlioglu, F.; Kaya, N.; Budak, S.; Chhay, B.; Ila, D.
    In this work, Ultra High Molecular Weight Poly Ethylene (UHMWPE) samples Were implanted by W + C ions using Metal-Vapour Vacuum Arc (MEVVA) ion implantation system with a fluence of 10(17) ion/cm(2) and extraction voltage of 30 kV. Samples were characterized with Raman Spectra, ATR-FTIR, UV-VIS-NlR Spectrum and RBS. Surface morphology of implanted and unimplanted samples were examined in nanoscale with AFM.
  • Conference Object
    Citation - Scopus: 5
    Adaptive Visual Servo Regulation Control for Camera-In Configuration With a Fixed Camera Extension
    (Institute of Electrical and Electronics Engineers Inc., 2007) Tatlıcıoğlu, Enver; Dawson, Darren M.; Xian, B.
    In this paper, image-based regulation control of a robot manipulator with an uncalibrated vision system is discussed. To compensate for the unknown camera calibration parameters, a novel prediction error formulation is presented. To achieve the control objectives, a Lyapunov-based adaptive control strategy is employed. The control development for the camera-in-hand problem is presented in detail and a fixed-camera problem is included as an extension.
  • Article
    Citation - WoS: 2
    The Development of Western-Type Large-Scale Consumption Areas in Turkey and Legal and Structural Regulation Efforts in Urban Retail Environments
    (Yıldız Teknik Üniversitesi, 2009) Kompil, Mert; Celik, Murat
    The retail sector has been experiencing a rapid and continuous change worldwide. There have also been profound changes in Turkey, especially after the 1980s. Both the retail sector and the urban retail environments have been altered radically. One of the most significant indicators of this change is the proliferation of western-type large-scale retail developments. Past experiences in developed countries have shown that the uncontrolled development of large-scale retail areas results in some undesired socioeconomic and physical outcomes, such as decline in the cultural and commercial activities of city centers, damage in existing retail workforce structure, and change in local retail hierarchy, nearby land uses, traffic loads and original architectural identity. Many countries have put into practice restrictive and regulatory policies to prevent these negative effects. As similar transformations have also been realized in Turkish retail environments, many institutions think that similar legal regulations must be implemented in Turkey as well. The present study investigates the ongoing retail change within the Turkish context, explores the legal and structural regulatory policies of the Organization for Economic Co-operation and Development (OECD) countries, and critically discusses the appropriate retail regulation policies for Turkey.
  • Article
    Efficient Design of Nursing Unit Floors
    (Yıldız Teknik Üniversitesi, 2009) Kazanasmaz, Z. Tugce; Duzgunes, Arda
    Hospital designs aim to obtain the lowest possible construction, maintenance and operational costs together with patient satisfaction, comfort and privacy. To satisfy these needs, the efficient design of nursing unit areas becomes considerably important. This study was thus conducted to analyze planimetric design efficiency of nursing unit floors by defining certain floor areas and floor area ratios. To test existing nursing unit floors, quantitative assessments were noted in regard to their planimetric efficiency: the utility value of the built floor area, both in terms of its allocation to patient space (served), support (serving) and circulation space and the relative proportions of these. Results were presented in a comparative table. Of the 15 hospital floor plans analyzed, five satisfied minimum space requirements for patient areas, while another five were in the optimum range for circulation areas. Two were defined as the least efficient, having the lowest patient-to-circulation area ratio.
  • Conference Object
    Native and Light Induced Defect States in Wide Band Gap Hydrogenated Amorphous Silicon-Carbon (a-Si1 : H) Alloy Thin Films
    (Springer, 1997) Güneş, Mehmet
    In this study, wide band gap a-Si1-x C-x:H alloy thin films prepared with and without hydrogen diluation of (SiH4, CH4) were characterized using optical absorption, dark conductivity, steady-state photoconductivity, sub-bandgap absorption obtained with both photothermal deflection spectroscopy (PDS) and dual beam photoconductivity (DBP), and electron spin resonance (ESR) techniques. Experimental results of steady-state photoconductivity and sub-bandgap absorption for different generation rates were analyzed using a detailed numerical model based on Simmons-Taylor statistics. The densities, energy location and nature of the native and light induced defect states in diluted and undiluted a-Si1-xCx:H alloy thin films were derived from the best fits to the experimental data. The extracted parameters for defect states were compared with those of a-Si:H films both in the annealed and light degraded states.
  • Conference Object
    Effect of Some Physical, and Chemical Variables on Flocculation and Sediment Behaviour
    (A.A. Balkema Publishers, 2000) Polat, Hürriyet; Polat, Mehmet; İpekoğlu, Üner
    Effect of some chemical and physical variables on the settling rate, final sediment height, sediment viscosity and supernatant turbidity of a clay sample was studied using various polyacrylamide type flocculants. Increasing flocculant concentration significantly increased both the settling rate and sediment viscosity. More importantly, changes in the final sediment, height, hence the packing density, was minimal for all the conditions tested once the sediment was allowed to consolidate. Also, the mode of addition of the polymer, at once or continuous, did not seem to affect any of the parameters measured. Conditioning time seemed to alter the settling rate at low polymer concentrations, but had no effect at high polymer concentrations. However, increasing the conditioning time caused a decrease in the sediment viscosity. Different types of the polyacrylimides generated different settling rates at a given concentration, but the final sediment height was nearly independent of polymer type.
  • Conference Object
    All-Optical Switching Based on Grating Written Photorefractive Slab/Fiber Waveguide Coupler
    (Institute of Electrical and Electronics Engineers Inc., 2002) Dinleyici, Mehmet Salih
    Since all optical switching is a key element for all kinds of optical networks, great amount of works have been dedicated either for material researches or various waveguide structures. Generally speaking the switching time of devices based on photorefractive effect are rather slow for today's high capacity optical fiber networks. In the field of waveguide architecture various geometries have been proposed and investigated for grating assisted or guided optical coupling for the purpose of designing all-optical switch, adddrop multiplexers, filters etc.
  • Conference Object
    Can Cpt Be Violated Through Extended Time Reversal?
    (World Scientific Publishing, 2001) Erdem, Recai; Ufuktepe, Ünal
    We consider the implications of the extension of time reversal through Wigner types and group extensions. We clarify its physical content and apply the results in a toy model. Finally we point out the possibility of violation of CPT in this framework.
  • Conference Object
    Upscaling Surface Flow Equations Depending Upon Data Availability at Different Scales
    (Springer Verlag, 2003) Tayfur, Gökmen
    St. Venant equations, which are used to model sheet flows, are point-scale, depth-averaged equations, requiring data on model parameters at a very fine scale. When data are available at the scale of a hillslope transect, the point equations need to be upscaled to conserve the mass and momentum at that scale, Hillslope-scale upscaled model must be developed if data are available at that scale. The performance of the three models applied to simulate flows from non-rilled surfaces revealed that the hillslope-scale upscaled model performs as good as the point-scale model though it uses far less data. The transectionally-upscaled model slightly underestimates the observed data.