In structural health monitoring, detection of localized damage can be achieved by exploiting recorded signals at a limited number of sensors within the structure. Here we propose the localization of damage using an ar...
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In structural health monitoring, detection of localized damage can be achieved by exploiting recorded signals at a limited number of sensors within the structure. Here we propose the localization of damage using an array of sensors as a computational time-reversal mirror (TRM). Time reversal (TR) is a physical process that exploits the time reversibility of wave equations and achieves re-focusing of the wave on the source of its origin by sending back, reversed in time, the signals recorded on an array of transducers. TR was originally introduced by Mathias Fink and his group and has several applications ranging from medical imaging to telecommunications [14]. In the present work, we perform time reversal numerically in order to effectively detect and localize defects in a bounded two-dimensional elastic domain. This is a generalization of a respective time-reversal implementation in an acoustic medium [12]. The solid contains a number of Nr sensors which can act as sources as well. Our data is the response matrix of the scattered field, that is, the difference between the total field obtained in the damaged structure and the incident field corresponding to the response in the healthy structure. Numerical solution of the wave propagation problem is performed using a mixed finite element formulation in terms of the velocity and stress fields [6]. In order to dissociate the response caused by Nd different defects, we apply the singular value decomposition (SVD) of the response matrix, while back-propagation of the projection of each singular vector corresponding to a non-zero singular value is performed in order to highlight each defect separately.
We discuss the development,verification,and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water *** shallow water equations are hyperbolic partia...
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We discuss the development,verification,and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water *** shallow water equations are hyperbolic partial differential equations and are widely used in the simulation of tsunami wave *** algorithms are tailored to take advantage of the single instruction multiple data(SIMD)architecture of graphic processing *** time integration is accelerated by local time stepping based on a multi-rate Adams-Bashforth scheme.A total variational bounded limiter is adopted for nonlinear stability of the numerical *** limiter is coupled with a mass and momentum conserving positivity preserving limiter for the special treatment of a dry or partially wet element in the ***,robustness and performance are demonstrated with the aid of test ***,we developed a unified multi-threading model *** kernels expressed in OCCA model can be cross-compiled with multi-threading models OpenCL,CUDA,and *** compare the performance of the OCCA kernels when cross-compiled with these models.
Petri nets are gaining increased popularity among the scientific community during the last few years. They provide a simple and very intuitive graphical model for concurrency, parallelism and synchronization, and have...
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This work explores a family of two-block nonconvex optimization problems subject to linear *** first introduce a simple but universal Bregman-style improved alternating direction method of multipliers(ADMM)based on th...
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This work explores a family of two-block nonconvex optimization problems subject to linear *** first introduce a simple but universal Bregman-style improved alternating direction method of multipliers(ADMM)based on the iteration framework of ADMM and the Bregman ***,we utilize the smooth performance of one of the components to develop a linearized version of *** to the traditional ADMM,both proposed methods integrate a convex combination strategy into the multiplier update *** each proposed method,we demonstrate the convergence of the entire iteration sequence to a unique critical point of the augmented Lagrangian function utilizing the powerful Kurdyka–Łojasiewicz property,and we also derive convergence rates for both the sequence of merit function values and the iteration ***,some numerical results show that the proposed methods are effective and encouraging for the Lasso model.
The geodesics and the curvature of a metric representing an isolated tachyon are investigated. It is argued that the properties are unphysical and inconsistent with observation, thus providing further evidence against...
The geodesics and the curvature of a metric representing an isolated tachyon are investigated. It is argued that the properties are unphysical and inconsistent with observation, thus providing further evidence against the existence of tachyons.
It is shown that certain similarity solutions relating to axisymmetric vortices in a viscous fluid over a plane wall can be associated with a point source or sink of vorticity at the origin and a line vortex along the...
It is shown that certain similarity solutions relating to axisymmetric vortices in a viscous fluid over a plane wall can be associated with a point source or sink of vorticity at the origin and a line vortex along the symmetry axis of the system. The rotationality of the nonlinear terms in the momentum equation, due to the radial vorticity and the azimuthal flow field, induces a poloidal flow which relates to one-cell or two-cell configurations. It is shown that a small imput of radial vorticity into a strong line vortex can induce an intense up-draught. There are ranges of values of the parameters yielding two solutions. The extremeties of these ranges are associated with values that yield velocity breakdown.
Similarity equations relating to steady and unsteady vortices in a stratified atmosphere are shown to possess more general solutions than hitherto reported. Solutions with n cells, where n = 1, 2, 3,..., are possible ...
Similarity equations relating to steady and unsteady vortices in a stratified atmosphere are shown to possess more general solutions than hitherto reported. Solutions with n cells, where n = 1, 2, 3,..., are possible such that the axial and radial velocities tend to zero far from the axis of the vortex. For solutions with a finite number of cells, far from the axis the radial mass flow is directed towards the axis, with the exception of a subclass of solutions relating to one-cell and two-cell vortices associated with the unsteady configuration where the radial velocity is directed outwards.
Purpose: This study aims to develop a mathematical model to understand and control the spread of lumpy skin disease in cattle populations, incorporating blood-sucking insects as vectors. Research Question: How can the...
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Regularity criteria in terms of bounds for the pressure are derived for the 3D MHD equations in a bounded domain with slip boundary conditions.A list of three regularity criteria is shown.
Regularity criteria in terms of bounds for the pressure are derived for the 3D MHD equations in a bounded domain with slip boundary conditions.A list of three regularity criteria is shown.
J. Chem. SOC.,Faraday Trans. 2, 1986,82,789-794 A Modified Poisson-Boltzmann Equation for the Ionic Atmosphere around a Cylindrical Wall Christopher W. Outhwaite department of applied and computationalmathematics, Th...
J. Chem. SOC.,Faraday Trans. 2, 1986,82,789-794 A Modified Poisson-Boltzmann Equation for the Ionic Atmosphere around a Cylindrical Wall Christopher W. Outhwaite department of applied and computationalmathematics, The University, Shefield SlO 2TN A modified Poisson-Boltzmann equation has been derived for the mean electrostatic potential in the neighbourhood of an isolated infinite cylinder immersed in a restricted primitive model electrolyte. The asymptotic solution is similar to that found for the modified Poisson-Boltzmann equation in the planar and spherically symmetric situations. A standard model in the theory of polyelectrolyte solutions is a system of uniformly charged rigid cylinders immersed in a restricted primitive model electrolyte. Of import- ance in understanding this model is the knowledge of the ionic atmosphere in the neighbourhood of an isolated infinite *** ionic atmosphere around a single cylindrical polyion has been thoroughly analysed using the Poisson-Boltzmann equation’-9 and recently analysed using integral equation methods. One of the most successful theories of the electric double layer for a uniformly charged plane wall is the modified Poisson-Boltzmann (MPB) theory.I4 Bratko and Vlachy” have successfully applied an approximate version of the planar MPB theory to study the counterion distribution around a cylindrical polyion. We present here the MPB equation for cylindrical geometry with no imaging at the comparable level of accuracy of the MPB equation used in the planar and spherically symmetric *** We consider a uniformly charged isolated infinite cylinder so that there is cylindrical symmetry. The cylinder is taken to have cross-sectional radius 6 and a point in the electrolyte is given by cylindrical polar coordinates (R, 4, z) with the z axis along the axis of the cylinder. The restricted primitive model electrolyte is specified by charged hard spheres of charge ei and common diameter a moving in a uniform dielec
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