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Performance modeling and optimization of sparse matrix-vector multiplication on NVIDIA CUDA platformXu, S. (author), Xue, W. (author), Lin, H.X. (author)In this article, we discuss the performance modeling and optimization of Sparse Matrix-Vector Multiplication (SpMV) on NVIDIA GPUs using CUDA. SpMV has a very low computation-data ratio and its performance is mainly bound by the memory bandwidth. We propose optimization of SpMV based on ELLPACK from two aspects: (1) enhanced performance for the...journal article 2011
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Xu, M. (author), Van Overloop, P.J. (author), Van de Giesen, N.C. (author)Due to land subsidence and sea level rise, salt intrusion in delta areas increases. This is a potential thread for agriculture in these areas. To investigate this thread and measures that can counteract on it, numerical models are developed to mimic the behavior of the water system under different strategies and scenarios. This behavior is...conference paper 2011
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Ji, L. (author), Xu, Y. (author)In (Xu and Shu in J. Sci. Comput. 40:375–390, 2009), a local discontinuous Galerkin (LDG) method for the surface diffusion of graphs was developed and a rigorous proof for its energy stability was given. Numerical simulation results showed the optimal order of accuracy. In this subsequent paper, we concentrate on analyzing a priori error...journal article 2011
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Sivapalan, M. (author), Yaeger, M.A. (author), Harman, C.J. (author), Xu, X. (author), Troch, P.A. (author)This paper presents analysis of annual water balance variability, (1) regional (between-catchment) variability and (2) between-year (interannual) variability and the symmetry between the two. This involved analysis of the annual water balance in terms of a two-stage partitioning, first, of annual precipitation into quick flow and soil wetting...journal article 2011
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Xu, Y.C. (author), Lei, B. (author), Hendriks, E.A. (author)This paper studies how to improve the field of view (FOV) coverage of a camera network. We focus on a special but practical scenario where the cameras are randomly scattered in a wide area and each camera may adjust its orientation but cannot move in any direction. We propose a particle swarm optimization (PSO) algorithm which can efficiently...journal article 2011
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Xu, J. (author), Yazicioglu, Refet Firat (author), Grundlehner, Bernard (author), Harpe, Pieter (author), Makinwa, K.A.A. (author), Van Hoof, Chris (author)This paper presents an active electrode system for gel-free biopotential EEG signal acquisition. The system consists of front-end chopper amplifiers and a back-end common-mode feedback (CMFB) circuit. The front-end AC-coupled chopper amplifier employs input impedance boosting and digitally-assisted<br/>offset trimming. The former increases the...journal article 2011
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Nikookar, H. (author), Xu, T. (author), Lu, H. (author)Signal fading due to multi-path propagation is one of the major impairments to meet the demands of next generation wireless networks for high data rate services. To mitigate the fading effects, time, frequency, and spatial diversity techniques or their hybrid can be used. Among different types of diversity techniques, spatial diversity is of...book chapter 2010
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Giang, N. (author), Xu, Q. (author), Hor, Y.S. (author), Williams, A.J. (author), Dutton, S.E. (author), Zandbergen, H.W. (author), Cava, R.J. (author)The structural misfit compound (PbSe)1.16(TiSe2)2 is reported. It is a superconductor with a Tc of 2.3 K. (PbSe)1.16(TiSe2)2 derives from a parent compound, TiSe2, which shows a charge-density wave transition and no superconductivity. The crystal structure, characterized by high-resolution electron microscopy and powder x-ray diffraction,...journal article 2010
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Xu, M. (author), De Boer, D.K.G. (author), Van Heesch, C.M. (author), Wachters, A.J.H. (author), Urbach, H.P. (author)Polarization gratings can be realized by polarization holographic recording in photoanisotropic materials. In this paper, we study two types of polarization gratings. One is recorded with two orthogonally circularly (OC) polarized beams and the other one with two orthogonally linearly (OL) polarized beams. The interference of both cases is...journal article 2010
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Sluijter, M. (author), Xu, M. (author), Urbach, H.P. (author), De Boer, D.K.G. (author)We study the applicability of geometrical optics to inhomogeneous dielectric nongyrotropic optically anisotropic media typically found in in-plane liquid-crystal configurations with refractive indices no=1.5 and ne=1.7. To this end, we compare the results of advanced ray- and wave-optics simulations of the propagation of an incident plane wave...journal article 2010
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Superconductivity in CuxBi2Se3 and its Implications for Pairing in the Undoped Topological InsulatorHor, Y.S. (author), Williams, A.J. (author), Checkelsky, J.G. (author), Roushan, P. (author), Seo, J. (author), Xu, Q. (author), Zandbergen, H.W. (author), Yazdani, A. (author), Ong, N.P. (author), Cava, R.J. (author)Bi2Se3 is one of a handful of known topological insulators. Here we show that copper intercalation in the van der Waals gaps between the Bi2Se3 layers, yielding an electron concentration of ?2×1020??cm-3, results in superconductivity at 3.8 K in CuxBi2Se3 for 0.12?x?0.15. This demonstrates that Cooper pairing is possible in Bi2Se3 at accessible...journal article 2010
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- Xu, W. (author) doctoral thesis 2009
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Holman, K.L. (author), McQueen, T.M. (author), Williams, A.J. (author), Klimczuk, T. (author), Stephens, P.W. (author), Zandbergen, H.W. (author), Xu, Q. (author), Ronning, F. (author), Cava, R.J. (author)Although many materials display the transition from insulating to metallic behavior on doping, only a few, such as VO2, have the right combination of crystal structure and physical properties to serve as model systems. Here we report the electronic and structural characteristics of the insulator to metal transition in V1?xMoxO2, which we have...journal article 2009
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Xu, M. (author)Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization selective gratings is to use birefringent...doctoral thesis 2009
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McQueen, T.M. (author), Huang, Q. (author), Ksenofontov, V. (author), Felser, C. (author), Xu, Q. (author), Zandbergen, H. (author), Hor, Y.S. (author), Allred, J. (author), Williams, A.J. (author), Qu, D. (author), Checkelsky, J. (author), Ong, N.P. (author), Cava, R.J. (author)The recently discovered iron arsenide superconductors appear to display a universal set of characteristic features, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+?Se, which can be considered the parent compound of the...journal article 2009
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Xu, M. (author), De Sio, L. (author), Caputo, R. (author), Umeton, C.P. (author), Wachters, A.J.H. (author), De Boer, D.K.G. (author), Urbach, H.P. (author)Recently, a novel holographic diffraction grating made of polymer slices alternated to homogeneous films of nematic liquid crystal (POLICRYPS) was realized. We study the optical performance of the POLICRYPS gratings by both numerical simulations and experiments. Characterization of the grating at normal and conical reading mount are performed....journal article 2008
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Xu, Q. (author)This thesis is the summary of the development of electron diffraction into a mature method for ab initio structure determination. The progress is illustrated with the structure determination of some complicated unknown inorganic materials. The main step forwards is that it is now possible to apply electron crystallography method on solving the...doctoral thesis 2008
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Xu, M. (author), Urbach, H.P. (author), De Boer, D.K.G. (author)A color and polarization separating backlight can be obtained by using a surface-relief grating made of birefringent material as an outcoupling structure on top of the lightguide. A rigorous finite element diffraction model was applied to study the polarization effect of such a grating. The diffraction of plane waves by the anisotropic grating...journal article 2007
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Klimczuk, T. (author), Xu, Q. (author), Morosan, E. (author), Thompson, J.D. (author), Zandbergen, H.W. (author), Cava, R.J. (author)Mg10Ir19B16, a previously unreported compound in the Mg-Ir-B chemical system, is found to be superconducting at temperatures near 5 K. The fact that the compound exhibits a range of superconducting temperatures between 4 and 5 K suggests that a range of stoichiometries is allowed, though no structural evidence for this is observed. The compound...journal article 2006
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De Boer, D.K.G. (author), Urbach, H.P. (author), Xu, M. (author)Poster presentation Optics Research Group TU Delft in cooperation with Philips and STWjournal article 2006