An algorithm for reconstructing the decision rule that is used for classifying scene images under the theoretically-possible problem definition is generated and illustrated by means of a computing experiment. The algo...
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An algorithm for reconstructing the decision rule that is used for classifying scene images under the theoretically-possible problem definition is generated and illustrated by means of a computing experiment. The algorithm can be used in geophysics for analyzing the shape of acoustic signals [1], for interpreting satellite imagery [2], etc.
For purposes of this review, springback is the elastically driven change of shape of a metal sheet during unloading and following forming. Scientific advances related to this topic have accelerated dramatically over r...
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For purposes of this review, springback is the elastically driven change of shape of a metal sheet during unloading and following forming. Scientific advances related to this topic have accelerated dramatically over roughly the last decade, since the publication of two reviews in the 2004-2006 timeframe (Wagoner, 2004;Wagoner et al., 2006). The current review focuses on the period following those publications, and on work in the first author's laboratory. Much of this recent work can be categorized into five main topics. (1) Plastic constitutive equations (2) Variable Young's modulus (3) Through-thickness integration of stress (4) Magnesium (5) Advanced high strength steels (AHSS) The first two subjects are related to accurate material representation, the third to numerical procedures, and the last two to particular classes of sheet materials. The principal contributions in these areas were summarized and put into context. (C) 2012 Elsevier Ltd. All rights reserved.
This paper concerns sequential checkpoint placement problems under two dependability measures: steady-state system availability and expected reward per unit time in the steady state. We develop numerical computation a...
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This paper concerns sequential checkpoint placement problems under two dependability measures: steady-state system availability and expected reward per unit time in the steady state. We develop numerical computation algorithms to determine the optimal checkpoint sequence, based on the classical Brender's fixed point algorithm and further give three simple approximation methods. numerical examples with the Weibull failure time distribution are devoted to illustrate quantitatively the overestimation and underestimation of the sub-optimal checkpoint sequences based on the approximation methods. (C) 2008 Elsevier B.V. All rights reserved.
The Japanese-french FP3C (Framework and Programming for Post-Petascale Computing) Project ANR/JST-2010- JTIC-003 aims at studying the software technologies, languages and programming models on the road to exascale com...
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ISBN:
(纸本)9781479924608
The Japanese-french FP3C (Framework and Programming for Post-Petascale Computing) Project ANR/JST-2010- JTIC-003 aims at studying the software technologies, languages and programming models on the road to exascale computing. The ability to efficiency exploit these future systems is challenging because of their ultra large-scale and highly hierarchical architecture with computational nodes including many-core processors and accelerators. We give an overview of some of the main issues explored within the project.
Population equations with more than one structuring attribute play an essential role in modeling cell populations important for the process of erythropoiesis. Attributes in this case are cell age, iron content of cell...
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Population equations with more than one structuring attribute play an essential role in modeling cell populations important for the process of erythropoiesis. Attributes in this case are cell age, iron content of cells and number of transferrin receptors on the cell membrane. The system is controlled via a feedback control using the oxygen carrying capacity of blood (which is determined by the number of red blood cells) as input for the controller and erythropoietin secreted by the kidneys as control for the system. The numerical algorithm is based on Trotter-Kato type approximations of the system state by system states of high order ordinary differential equations on finite dimensional subspaces of the state space of the system. These finite dimensional subspaces are generated by Legendre polynomials.
In this paper, we present algorithms to solve a complex system of partial integro-differential equations (PIDE's) of parabolic type. The system is motivated by applications in finance where the solution of the sys...
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In this paper, we present algorithms to solve a complex system of partial integro-differential equations (PIDE's) of parabolic type. The system is motivated by applications in finance where the solution of the system gives the price of European options in a regime-switching jump diffusion model. The new algorithms are based on theoretical analysis in Florescu et al. (2012) where the proof of convergence of the algorithms is carried out. The problems are also solved using a more traditional approach, where the integral terms (but not the derivative terms) are treated explicitly. Another contribution of this work details a novel type of jump distribution. Empirical evidence suggests that this type of distribution may be more appropriate to model jumps as it makes them more clearly distinguishable from the signal variability.
Cosmic dust is present in many astrophysical objects, and recent observations across the electromagnetic spectrum show that the dust distribution is often strongly three-dimensional (3D). Dust grains are effective in ...
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Cosmic dust is present in many astrophysical objects, and recent observations across the electromagnetic spectrum show that the dust distribution is often strongly three-dimensional (3D). Dust grains are effective in absorbing and scattering ultraviolet (UV)/optical radiation, and they re-emit the absorbed energy at infrared wavelengths. Understanding the intrinsic properties of these objects, including the dust itself, therefore requires 3D dust radiative transfer (RT) calculations. Unfortunately, the 3D dust RT problem is nonlocal and nonlinear, which makes it one of the hardest challenges in computational astrophysics. Nevertheless, significant progress has been made in the past decade, with an increasing number of codes capable of dealing with the complete 3D dust RT problem. We discuss the complexity of this problem, the two most successful solution techniques [ray-tracing (RayT) and Monte Carlo (MC)], and the state of the art in modeling observational data using 3D dust RT codes. We end with an outlook on the bright future of this field.
The Allen-Cahn equation is a simple model of a nonlinear reaction-diffusion process. It is often used to model interface motion in time, e.g. phase separation in alloys. It has applications in many areas including mat...
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The Allen-Cahn equation is a simple model of a nonlinear reaction-diffusion process. It is often used to model interface motion in time, e.g. phase separation in alloys. It has applications in many areas including material sciences, biology, geology, as well as image processing. We will consider a simple scalar Allen-Cahn equation subject to distributed control. Here, the nonlinear reaction term is obtained from using the standard double-well potential, leading to a cubic nonlinearity. We will describe a nonlinear feedback control strategy based on the concept of Model Predictive Control (MPC). We also show how to obtain the open-loop trajectory and control using numerical techniques for PDE-constrained optimization. The feedback control scheme is then applied to the spatially semi-discretized nonlinear optimal control problem. For the prediction and control step within the MPC scheme, we apply a linear-quadratic regulator/Gaussian design problem. The arising computational challenge consisting in solving the associated large-scale algebraic Riccati equations has already been shown in the literature to be feasible using reasonably fine discretizations.
A nonlinear inverse problem of pharmacokinetics for the dual-compartment model with extravascular route of the drug administration is considered. The problem is significantly ill-posed: its solution is not unique and ...
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A nonlinear inverse problem of pharmacokinetics for the dual-compartment model with extravascular route of the drug administration is considered. The problem is significantly ill-posed: its solution is not unique and is unstable. We discuss nonuniqueness of the inverse problem and the degree of ill-posedness. The initial problem is reduced to a linear operator equation by linearization. It is demonstrated that the resolving ability of the inverse problem can be improved by varying of the location of measurement data points. Results of numerical experiments are presented. The question of choosing the initial approximations is considered.
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