Search Results

Now showing 1 - 10 of 23
  • Article
    On the Definition of Sequential Consistency
    (Elsevier Science Bv, 2005) Sezgin, A; Gopalakrishnan, G
    The definition of sequential consistency is compared with an intuitive notion of correctness. That the definition is not strong enough is illustrated through a hypothetical memory system which is clearly incorrect, yet sequentially consistent. It is claimed that the reason for this is the absence of a relation between what actually happens (temporal order) and what seems to happen (logical order). A stronger version of sequential consistency is proposed. (c) 2005 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 15
    Global asymptotic stability of 2-D state-space digital filters with saturation arithmetic: Modified approach
    (Elsevier Science Bv, 2008) Singh, Vimal
    A criterion for the global asymptotic stability of 2-D state-space digital filters described by the Roesser model employing state saturation arithmetic is presented. The criterion is a modified form of a recently reported criterion. An example shows the effectiveness of the modified criterion. (C) 2007 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 42
    Citation - Scopus: 47
    A Novel Global Robust Stability Criterion for Neural Networks With Delay
    (Elsevier Science Bv, 2005) Singh, V
    A criterion based on the intervalised network parameters for the global robust stability of Hopfield-type neural networks with delay is presented. The criterion is compared with an earlier criterion. (c) 2005 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 79
    Citation - Scopus: 77
    Doubly Warped Products
    (Elsevier Science Bv, 2001) Ünal, B
    In this paper we study geodesic completeness of Riemannian doubly warped products and Lorentzian doubly warped products. We give necessary conditions for generalized Robertson-Walker spacetimes with doubly warped product spacial parts to be globally hyperbolic. We also state some results about killing and conformal vector fields of doubly warped products.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Sets of Random Variables With a Given Uncorrelation Structure
    (Elsevier Science Bv, 2001) Ostrovska, S
    Let xi (1),...,xi (n) be random variables having finite expectations. Denote i(k) := # {(j(1),...,j(k)): 1 less than or equal to j(1) < ... < j(k) less than or equal to n and E (l=1)pi (k) xi (fi) = (l=1)pi (k) E xi (h)}, k = 2,...,n. The finite sequence (i(2),...,i(n)) is called the uncorrelation structure of xi (1),...,xi (n). It is proved that for any given sequence of nonnegative integers (i(2),...,i(n)) satisfying 0 less than or equal to i(k) less than or equal to ((n)(k))and any given nondegenerate probability distributions P-1,...,P-n there exist random variables eta (1),...,eta (n) with respective distributions P-1,...,P-n such that (i(2),...,i(n)) is their uncorrelation structure. (C) 2001 Elsevier Science B.V. All rights reserved.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Electrical Behavior of Pb1.83mg0.29< Pyrochlore Ceramics
    (Elsevier Science Bv, 2004) Mergen, A; Kayed, TS
    Pb1.83Mg0.29Nb1.71O6.39 pyrochlore was produced via a simple partial oxalate method. It was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Single phase, belonging to the cubic pyrochlore structure, with a lattice parameter of a = 10.60125 +/- 0.001 Angstrom and grain size that varies from 5 to 10 mum was obtained. The electrical properties were measured at different temperatures in the range 15-320 K without and with applied magnetic field of 1.4 T. Current-voltage characteristics data were fitted to a power law expression V=I-beta(T) in which the exponential parameter beta takes values around 1 at all temperatures except at 300 K. Resistance starts from 3.3 x 10(10) Omega at 15 K and increases gradually to 4.8 x 10(10) Omega at 240 K. It drops to approximately 1.2 x 10(10) Omega at 300 K, after which it increases again to around 1.6 x 10(10) Omega at 320 K. (C) 2004 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 45
    Citation - Scopus: 45
    An Ambipolar Low Band Gap Material Based on Bodipy and Edot
    (Elsevier Science Bv, 2009) Algi, Fatih; Cihaner, Atilla
    A novel donor-acceptor type conducting polymer based on BODIPY dye as acceptor and EDOT units as donor parts is synthesized electrochemically. The unique combination of BODIPY and EDOT units provides an ambipolar (n- and p-doping processes) low band gap material (4). This is the first example of p-n junction in an organic pi-conjugated material where BODIPY unit is incorporated directly in the main chain. Furthermore, the polymer film exhibits electrochromic behavior upon p-doping: a color change from light violet (neutral) to indigo (oxidized). (C) 2009 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 24
    Chaotic Dynamics of Resistively Coupled Dc-Driven Distinct Josephson Junctions and the Effects of Circuit Parameters
    (Elsevier Science Bv, 2009) Kurt, Erol; Canturk, Mehmet
    Two distinct Josephson junctions (JJs) connected with a constant coupling resistance R(cp) are theoretically considered to investigate the overall dynamics below and above the critical current I(c). The circuit model of the device is driven by two DC current sources, I(1) and I(2). Each junction is characterized by a nonlinear resistive-capacitive junction (NRCSJ). Having constructed the circuit model, time-dependent simulations are carried out for a variety of control parameter sets. Common techniques such as bifurcation diagrams, two-dimensional attractors and Lyapunov exponents are applied for the determination of chaotic as well as periodic dynamics of the superconducting junction devices. According to the findings, two states (namely superconducting and ordinary conducting) are determined as functions of the source currents. The chaotic current which flows through Rcp exhibits a very rich behavior depending on the source currents I(1) and I(2) and junction capacitances C(1) and C(2). The device characteristics are summarized by a number of three-dimensional phase diagrams in the parameter space. In addition, for certain parameters, hyper-chaotic cases with two positive Lyapunov exponents are encountered. In contrast to earlier studies claiming the need for a sinusoidal feeding current for generating a chaotic signal, our circuitry can easily generate one via a DC source. (C) 2009 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 19
    Soccer, Stock Returns and Fanaticism: Evidence From Turkey
    (Elsevier Science Bv, 2009) Berument, M. Hakan; Ceylan, Nildağ Başak; Ceylan, Nildag Basak; Ogut-Eker, Gulin; Ceylan, Nildağ Başak; Tourism Management; Tourism Management
    This paper assesses the effect of three major soccer teams' wins on the returns of the Istanbul Stock Exchange (ISE). We argue that the effect of soccer wins on ISE returns increases with the fanaticism of the teams' supporters. (C) 2009 Western Social Science Association. Published by Elsevier Inc. All rights reserved.
  • Article
    Citation - WoS: 32
    Citation - Scopus: 32
    Temperature Dependence of the Band Gap, Refractive Index and Single-Oscillator Parameters of Amorphous Indium Selenide Thin Films
    (Elsevier Science Bv, 2007) Qasrawi, A. F.
    InSe thin films are obtained by evaporating InSe crystal onto ultrasonically cleaned glass substrates under pressure of similar to 10(-5) Torr. The structural and compositional analysis revealed that these films are of amorphous nature and are atomically composed of similar to 51% In and similar to 49% Se. The reflectance and transmittance of the films are measured at various temperatures (300-450 K) in the incident photon energy range of 1.1-2.1 eV. The direct allowed transitions band gap - calculated at various temperatures - show a linear dependence on temperature. The absolute zero value band gap and the rate of change of the band gap with temperature are found to be (1.62 +/- 0.01) eV and -(4.27 +/- 0.02) x 10(-4) eV/K, respectively. The room temperature refractive index is estimated from the transmittance spectrum. The later analysis allowed the identification of the static refractive index, static dielectric constant, oscillator strength and oscillator energy. (c) 2006 Elsevier B.V. All rights reserved.