Bilgisayar Mühendisliği Bölümü Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/45
Browse
Browsing Bilgisayar Mühendisliği Bölümü Koleksiyonu by browse.metadata.publisher "Elsevier Science Bv"
Now showing 1 - 9 of 9
- Results Per Page
- Sort Options
Article Citation - WoS: 29Citation - Scopus: 31Electrochromic Properties of Heat-Treated Thin Films of Ceo2-Tio2 Prepared by Sol-Gel Route(Elsevier Science Bv, 2008) Ghodsi, Farhad E.; Tepehan, Fatma Zehra; Tepehan, Galip GültekinCeO2-TiO2-ZrO2 thin films were prepared using the sol-gel process and deposited on glass and ITO-coated glass substrates via dipcoating technique. The samples were heat treated between 100 and 500 degrees C. The heat treatment effects on the electrochromic performances of the films were determined by means of cyclic voltammetry measurements. The structural behavior of the film was characterized by atomic force microscopy and X-ray diffraction. Refractive index extinction coefficient and thickness of the films were determined in the 350-1000nm wavelength using nkd spectrophotometry analysis. Heat treatment temperature affects the electrochromic optical and structural properties of the film. The charge density of the samples increased from 8.8 to 14.8 mC/cm(2) with increasing heat-treatment temperatures from 100 to 500 degrees C. It was determined that the highest ratio between anodic and cathodic charge takes place with increase of temperature up to 500 degrees C. (c) 2007 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 12Citation - Scopus: 15Improving Opencl Programmability With the Heterogeneous Programming Library(Elsevier Science Bv, 2015) Vinas, Moises; Fraguela, Basilio B.; Bozkuş, Zeki; Andrade, DiegoThe use of heterogeneous devices is becoming increasingly widespread. Their main drawback is their low programmability due to the large amount of details that must be handled. Another important problem is the reduced code portability as most of the tools to program them are vendor or device-specific. The exception to this observation is OpenCL which largely suffers from the reduced programmability problem mentioned particularly in the host side. The Heterogeneous Programming Library (HPL) is a recent proposal to improve this situation as it couples portability with good programmability. While the HPL kernels must be written in a language embedded in C++ users may prefer to use OpenCL kernels for several reasons such as their growing availability or a faster development from existing codes. In this paper we extend HPL to support the execution of native OpenCL kernels and we evaluate the resulting solution in terms of performance and programmability achieving very good results.Article Citation - WoS: 19Citation - Scopus: 19Influence of Ph on the Optical and Structural Properties of Spin Coated Ceo2-Tio2 Thin Films Prepared by Sol-Gel Process(Elsevier Science Bv, 2007) Ghodsi, Farhad E.; Tepehan, Fatma Zehra; Tepehan, Galip GültekinOptical and structural properties of mixed CeO2-TiO2 thin films have been investigated by varying the pH of the coating sol. The films were prepared by sol-gel process using spin-coating technique with a spin speed of 2500 rpm. The optical and structural properties of films were examined by a spectrophotometer AFM and XRD. Optical constants and thickness of the CeO2-TiO2 thin films have been determined with respect to the pH of the coating bath before deposition. The refractive index at 550 nm wavelength increases from 1.49 to 1.60 when the pH of the sol increases from 2.22 to 2.92. The thickness increases from 46.6 nm to 96.1 nm in this pH range. The XRD measurements show that the films have amorphous structure. The AFM analysis shows that the pH of sol prior to deposition changes the uniformity and porosity of the films. (C) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 18Modeling the Optical Properties of Wo(3) and Wo(3)-Sio(2) Thin Films(Elsevier Science Bv, 2008) Saygin-Hinczewski, Dursen; Hinczewski, Michael; Sorar, İdris; Tepehan, Fatma Zehra; Tepehan, Galip GültekinThe optical properties and surface morphology of sol-gel spin coated WO(3) and WO(3)-SiO(2) composite films annealed at 250 and 400 degrees C are investigated. For the purpose of extracting the optical parameters of the films a novel form for the dielectric function is introduced consisting of two Tauc-Lorentz oscillators and an Urbach tail component which is suited for amorphous multi-transition materials with substantial subgap absorption. The evolution of the refractive indices transmittances and band gaps with doping is marked by sizable shifts at 2.0-2.5% SiO(2) doping for the 250 degrees C films and 4.0-4.5% doping for the 400 degrees C films. In addition pronounced changes in the surface roughness of the films occur at these doping values. (c) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 12Optical and Structural Properties of Sol-Gel Made Ce/Ti Mixed Oxide Thin Films as Transparent Counter Electrode for Electrochromic Devices(Elsevier Science Bv, 2008) Ghodsi, Farhad E.; Tepehan, Fatma Zehra; Tepehan, Galip GültekinCe/Ti/Zr mixed oxide thin films were prepared using sol-gel process with mole ratios from 45/5 to 5/45 of Ti/Zr and 50 of Cc and deposited by dip coating technique. Optical electrochromic and structural properties of such films were investigated. The thickness refractive index and extinction coefficient of the films were calculated through transmission and reflection measurement by an nkd spectrophotometer. The surface morphology and structural behaviors of the films were characterized by atomic force microscopy and X-ray diffraction. Cyclic voltammetry measurements also were used to study electrochromic properties of these films. The best counter electrode Ce/Ti/Zr oxide thin film is achieved for the sample with a mole ratio of 40/10 of Ti/Zr. The ratio between anodic and cathodic charge is about 0.95 for this sample with a surface roughness of 1.8 nm. (C) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 21Optical and Structural Properties of Ta2o5-Ceo2 Thin Films(Elsevier Science Bv, 2007) Saygın-Hinczewski, Dursen; Koç, Kenan; Sorar, İdris; Hinczewski, Michael; Tepehan, Fatma Zehra; Tepehan, Galip GültekinIn this study the sol-gel spin-coating method has been used to make Ta2O5-CeO2 thin films. These films have been prepared in various composition ratios to observe changes in their optical and structural properties. Reflectance and transmittance spectra were collected in the spectral range of 300-1000 nm and were accurately fit using the Tauc-Lorentz model. Film thicknesses refractive indices absorption coefficients and optical band gaps were extracted from the theoretical fit. The highest refractive index value was found at 5% CeO2 doping. The structure of the films was characterized by X-ray diffractometry and Fourier transform infrared spectrometry while the surface morphology was examined through atomic force microscopy. (C) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Orthogonal Projection and Liftings of Hamilton-Decomposable Cayley Graphs on Abelian Groups(Elsevier Science Bv, 2013) Alspach, Brian; Çalışkan, Cafer; Kreher, Donald L.In this article we introduce the concept of (p alpha)-switching trees and use it to provide sufficient conditions on the abelian groups G and H for when CAY (G x HEditorial Citation - WoS: 3Citation - Scopus: 2Seventh International Meeting on Electrochromism (ime-7) Istanbul Turkey 3-7 September 2006(Elsevier Science Bv, 2008) Özer, Nilgün M.; Tepehan, Galip Gültekin[Abstract Not Available]Article Citation - WoS: 6Citation - Scopus: 9Three-fast-searchable graphs(Elsevier Science Bv, 2013) Dereniowski, Dariusz; Diner, Öznur Yaşar; Dyer, DannyIn the edge searching problem searchers move from vertex to vertex in a graph to capture an invisible fast intruder that may occupy either vertices or edges. Fast searching is a monotonic internal model in which at every move a new edge of the graph G must be guaranteed to be free of the intruder. That is once all searchers are placed the graph G is cleared in exactly vertical bar E(G)vertical bar moves. Such a restriction obviously necessitates a larger number of searchers. We examine this model and characterize graphs for which 2 or 3 searchers are sufficient. We prove that the corresponding decision problem is NP-complete. (C) 2013 Elsevier B.V. All rights reserved.