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3D monolithic finite element approach for aero-thermics processes in industrial furnaces⋆

E. Hachem, E. Massoni, T. Coupez (2011)

ESAIM: Proceedings

We consider in this paper a mathematical and numerical model to design an industrial software solution able to handle real complex furnaces configurations in terms of geometries, atmospheres, parts positioning, heat generators and physical thermal phenomena. A three dimensional algorithm based on stabilized finite element methods (SFEM) for solving the momentum, energy, turbulence and radiation equations is presented. An immersed volume method (IVM) for thermal coupling of fluids and solids is introduced...

A counterexample in comonotone approximation in L p space

Xiang Wu, Song Zhou (1993)

Colloquium Mathematicae

Refining the idea used in [24] and employing very careful computation, the present paper shows that for 0 < p ≤ ∞ and k ≥ 1, there exists a function f C [ - 1 , 1 ] k , with f ( k ) ( x ) 0 for x ∈ [0,1] and f ( k ) ( x ) 0 for x ∈ [-1,0], such that lim supn→∞ (en(k)(f)p) / (ωk+2+[1/p](f,n-1)p) = + ∞ where e n ( k ) ( f ) p is the best approximation of degree n to f in L p by polynomials which are comonotone with f, that is, polynomials P so that P ( k ) ( x ) f ( k ) ( x ) 0 for all x ∈ [-1,1]. This theorem, which is a particular case of a more general one, gives a complete solution...

A Korovkin type approximation theorems via -convergence

Oktay Duman (2007)

Czechoslovak Mathematical Journal

Using the concept of -convergence we provide a Korovkin type approximation theorem by means of positive linear operators defined on an appropriate weighted space given with any interval of the real line. We also study rates of convergence by means of the modulus of continuity and the elements of the Lipschitz class.

A new exceptional polynomial for the integer transfinite diameter of [ 0 , 1 ]

Qiang Wu (2003)

Journal de théorie des nombres de Bordeaux

Using refinement of an algorithm given by Habsieger and Salvy to find integer polynomials with smallest sup norm on [0, 1] we extend their table of polynomials up to degree 100. For the degree 95 we find a new exceptionnal polynomial which has complex roots. Our method uses generalized Müntz-Legendre polynomials. We improve slightly the upper bound for the integer transfinite diameter of [0, 1] and give elementary proofs of lower bounds for the exponents of some critical polynomials.

A new H(div)-conforming p-interpolation operator in two dimensions

Alexei Bespalov, Norbert Heuer (2011)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

In this paper we construct a new H(div)-conforming projection-based p-interpolation operator that assumes only Hr(K) 𝐇 ˜ -1/2(div, K)-regularity (r &gt; 0) on the reference element (either triangle or square) K. We show that this operator is stable...

A new H(div)-conforming p-interpolation operator in two dimensions

Alexei Bespalov, Norbert Heuer (2011)

ESAIM: Mathematical Modelling and Numerical Analysis

In this paper we construct a new H(div)-conforming projection-based p-interpolation operator that assumes only Hr(K) 𝐇 ˜ -1/2(div, K)-regularity (r > 0) on the reference element (either triangle or square) K. We show that this operator is stable with...

A note on polynomial approximation in Sobolev spaces

Rüdiger Verfürth (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

For domains which are star-shaped w.r.t. at least one point, we give new bounds on the constants in Jackson-inequalities in Sobolev spaces. For convex domains, these bounds do not depend on the eccentricity. For non-convex domains with a re-entrant corner, the bounds are uniform w.r.t. the exterior angle. The main tool is a new projection operator onto the space of polynomials.

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