We present a model for generalized Newtonian fluid flow through a porous medium. In the model the dependence of the fluid viscosity on the velocity is replaced by a dependence on a smoothed (locally averaged) velocity. With appropriate assumptions on the smoothed velocity, existence of a solution to the model is shown. Two examples of smoothing operators are presented in the appendix. A numeric...

diffusion equations using a nine-point compact difference scheme. implementation with multigrid, and carry out a Fourier We test the efficiency of the algorithm with various smoothers and smoothing analysis of the Gauss–Seidel operator. In Secintergrid transfer operators. The algorithm displays a grid-indepention 3 we present numerical experiments that demonstrate dent convergence rate and prod...

We present a framework to extract line-type features from unstructured two-manifold meshes. Our method computes a collection of piecewise linear curves describing the salient features of the mesh, such as edges and ridge lines. Our algorithms are semiautomatic, that is, they require the user to input a few control parameters and to select the operators to be applied to the mesh. Our mesh edge d...

An evolutionary method is proposed for the constrained optimization of chemical engineering processes. Apart from the classical mutation, crossover and creep (small mutation), it makes use of several novel reproductive operators: shift, smoothing, extrapolation and swapping. An adaptive mutation rate is used to guard against stalling at local peaks. The method was able to solve dynamic optimiza...

We provide a new estimator of integral operators with smooth kernels, obtained from a set of scattered and noisy impulse responses. The proposed approach relies on the formalism of smoothing in reproducing kernel Hilbert spaces and on the choice of an appropriate regularization term that takes the smoothness of the operator into account. It is numerically tractable in very large dimensions. We ...

In several image processing applications one has to deal with noisy images defined on surfaces, like electric impulsions or diffusion tensors on the cortex. We propose a new regularization technique for data defined on triangulated surfaces: the Beltrami flow over intrinsic manifolds. This technique overcomes the over smoothing of the L2 and the stair-casing effects of the L1 flow for strongly ...

This paper describes a technique for characterization and segmentation of anisotropic patterns that exhibit a single local orientation. Using Gaussian derivatives we construct a gradient-square tensor at a selected scale. Smoothing of this tensor allows us to combine information in a local neighborhood without canceling vectors pointing in opposite directions. Whereas opposite vectors would can...

In this paper, Fourier analysis is used for finding efficient multigrid components. The individual multigrid components for several discrete partial differential operators are chosen automatically by a genetic optimization method. From a set of multigrid components, such as different smoothers, coarse grid correction components, cycle types, number of smoothing iterations, and relaxation parame...

Many stream-processing systems enforce an order on data streams during query evaluation to help unblock blocking operators and purge state from stateful operators. Such in-order processing (IOP) systems not only must enforce order on input streams, but also require that query operators preserve order. This orderpreserving requirement constrains the implementation of stream systems and incurs si...

We investigate the dependence of QSO Lyα absorption features on the temperature of the absorbing gas and on the amplitude of the underlying dark matter fluctuations. We use high-resolution hydrodynamic simulations in cold dark matter dominated cosmological models. In models with a hotter intergalactic medium (IGM), the increased temperature enhances the pressure gradients between low and high d...