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Article Citation - WoS: 45Citation - Scopus: 48Refractive Index, Band Gap and Oscillator Parameters of Amorphous Gase Thin Films(Wiley-v C H verlag Gmbh, 2005) Qasrawi, AF; Department of Electrical & Electronics EngineeringGaSe thin films are obtained by evaporating GaSe crystals onto ultrasonically cleaned glass substrates kept at room temperature under a pressure of similar to 10(-5) Torr. The X-ray analysis revealed that these films are of amorphous nature. The reflectance and transmittance of the films are measured in the incident photon energy range of 1.1-3.0 eV. The absorption coefficient spectral analysis revealed the existence of long and wide band tails of the localized states in the low absorption region. The band tails width is calculated to be 0.42 eV. The analysis of the absorption coefficient in the high absorption region revealed an indirect forbidden band gap of 1.93 eV. The transmittance analysis in the incidence photon wavelength range of 500-1100 nm allowed the determination of refractive index as function of wave length. The refractive index-wavelength variation leads to the determination of dispersion and oscillator energies as 31.23 and 3.90 eV, respectively. The static refractive index and static dielectric constant were also calculated as a result of the later data and found to be 9.0 and 3.0, respectively.Article Citation - WoS: 5Citation - Scopus: 6Material Flow Control in High Pressure Sheet Metal Forming of Large Area Parts With Complex Geometry Details(verlag Stahleisen Mbh, 2005) Trompeter, M; Önder, E; Homberg, W; Tekkaya, E; Kleiner, MWorking media based forming processes show advantages compared to the conventional deep drawing in the range of sheet metal parts with complex geometry details. By High Pressure Sheet Metal Forming (HBU), complex parts can be formed with reduced tool costs, fewer process steps, and improved part properties, particularly by the use of high strength steels. In order to use these advantages to full capacity, the material flow into the area of the geometry details needs to be optimised. The key element for the material flow control is a multi-point blank holder. In combination with flange draw-in sensors, a closed loop flange draw-in control can be built up which guarantees a reproducible material flow and, consequently, defined part properties. Furthermore, a favourable pre-distribution of sheet metal material can be reached which leads to a widening of the process limits. Considering a large area sheet metal part with a complex door handle element as example, strategies for the material flow control will be discussed in this paper. The conclusions are based on FE-simulations as well as experimental findings.Article Citation - WoS: 5Citation - Scopus: 7Comparison of Nat1, Nat2 & Gstt2-2 Activities in Normal and Neoplastic Human Breast Tissues(Aepress Sro, 2006) Geylan-SU, YS; Isgör, B; Coban, T; Kapucuoglu, N; Aydintug, S; Iscan, M; Güray, T; Chemical EngineeringIn this study, arylamine N-acetyltransferases, NATs (E.C.2.3.1.5) and glutathione-S-transferase-T2-2, GSTT2-2 (E.C.2.5.1.18) enzyme activities in the breast tumor and surrounding tumor-free tissues of 22 female breast cancer patients with infiltrating ductal carcinoma were measured. The possible impacts of grade of malignancy, chemotherapy treatment, estrogen receptor status and menopausal status on all enzyme activities were evaluated. The results showed that, both NAT2 and GSTT2-2 display significant differences between tumor and tumor-free breast tissues, while no difference was observed in NAT1. Grade of malignancy seems to be positively associated with NAT1 and negatively associated with GSTT2-2. Though, both NAT2 and GSTT2-2 have increased mean tumor activities, the grade of malignancy, chemotherapy status, menopausal status or estrogen receptor status are not correlated statistically.Article Citation - WoS: 6Citation - Scopus: 4Some results related to the Laplacian on vector fields(Kossuth Lajos Tudomanyegyetem, 2006) Erkekoglu, Fazilet; Kupeli, Demir N.; Uebnal, BuelentA characterization of Euclidean spheres out of connected, compact, Einstein Riemannian manifolds of constant scalar curvature is made by a characterization of a vector field with an eigenvalue equation for the Laplacian on vector fields.Article Citation - WoS: 9Citation - Scopus: 9Electrical Properties of Bi1.5znsb1.5< Pyrochlore Ceramics(Wiley-v C H verlag Gmbh, 2003) Kayed, TS; Mergen, ABi1.5ZnSb1.5O7 pyrochlore samples were prepared by solid state reaction method. They were examined by x-ray diffraction and scanning electron microscopy. Single phase, belongs to the cubic pyrochlore structure, with a lattice parameter of 10.442 Angstrom and grain size that varies from 16 to 20 mum was obtained. The electrical properties were measured at different temperatures in the range 15-330 K under different applied magnetic fields up 1.4 T. In our measurements for Hall coefficient, Hall resistivity, and mobility; we noticed an anomalous behavior at two temperatures (around 250 and 310 K) which was supported by the I-V measurements (double transition of the slope of I-V characteristics (beta) at the same temperatures). This was discussed in terms of polarization phenomenon and mixed ionic-electronic conduction. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Review Citation - Scopus: 7Yielding of long concentric tubes under radial pressure based on von Mises criterion;(2005) Akiş,T.; Eraslan,A.N.The classical problem of a plain strain tube with free ends, subject to either internal or external pressure is extended to tightly fitted long concentric tubes with axially constrained ends. Making use of von Mises yield criterion, critical values of pressure leading to plastic flow are determined in terms of material properties and tube dimensions.Article Citation - WoS: 6Citation - Scopus: 6A Boundary Value Problem for Second Order Nonlinear Difference Equations on the Semi-Infinite Interval(Taylor & Francis Ltd, 2002) Guseinov, GSIn this paper, we consider a boundary value problem (BVP) for nonlinear difference equations on the discrete semi-axis in which the left-hand side being a second order linear difference expression belongs to the so-called Weyl-Hamburger limit-circle case. The BVP is considered in the Hilbert space l(2) and is formed via boundary conditions at a starting point and at infinity. Existence and uniqueness results for solutions of the considered BVP are established.Conference Object Citation - WoS: 16Modified Cognitive Complexity Measure(Springer-verlag Berlin, 2006) Misra, SanjayIn cognitive functional size measure, the functional size is proportional to weighted cognitive complexity of all internal BCS's and number of input and output. This paper proposes the modification in cognitive functional size complexity measure. The proposed complexity measure is proportional to total occurrence of operators and operands and all internal BCS's. The operators and operands are equally important in design consideration. Thus, the contribution of the operators, operands and cognitive aspects complete the definition of a complexity measure in terms of cognitive. Accordingly, a new formula is developed for calculating the modified cognitive complexity measure. An attempt has also been made to evaluate modified cognitive complexity measure in terms of nine Weyuker's properties, through examples. It has been found that seven of nine Weyuker's properties have been satisfied by the modified cognitive complexity measure and hence establishes as a well-structured one.Conference Object Citation - WoS: 1On Euler's differential methods for continued fractions(Kent State University, 2006) Khrushchev, Sergey; MathematicsA differential method discovered by Euler is justified and applied to give simple proofs to formulas relating important continued fractions with Laplace transforms. They include Stieltjes formulas and some Ramanujan formulas. A representation for the remainder of Leibniz's series as a continued fraction is given. We also recover the original Euler's proof for the continued fraction of hyperbolic cotangent.Article Citation - WoS: 62Citation - Scopus: 65A curvature condition for a twisted product to be a warped product(Springer-verlag, 2001) Fernández-López, M; García-Río, E; Kupeli, DN; Ünal, BIt is shown that a mixed Ricci-flat twisted product semi-Riemannian manifold can be expressed as a warped product semi-Riemannian manifold. Asa consequence, any Einstein twisted product semi-Riemannian manifold is in fact, a warped product serni-Riemannian manifold.
