Results 41 to 50 of about 159,936 (305)
Characterization of rational ruled surfaces
Journal of Symbolic Computation, 2014 The ruled surface is a typical modeling surface in computer aided geometric design. It is usually given in the standard parametric form. However, it can also be in the forms than the standard one. For these forms, it is necessary to determine and find the standard form.
Li-Yong Shen, Sonia Pérez-Díaz
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Tori and surfaces violating a local-to-global principle for rationality
Comptes Rendus. MathématiqueWe show that even within a class of varieties where the Brauer–Manin obstruction is the only obstruction to the local-to-global principle for the existence of rational points (Hasse principle), this obstruction, even in a stronger, base change invariant ...
Kunyavskiĭ, Boris
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Rational Parametrization of Surfaces
Journal of Symbolic Computation, 1998 A rational surface is an algebraic surface birationally isomorphic to \( {\mathbb P}^{2} \). The author investigates the computational problems of rational parametrization of algebraic surfaces and formulates several algorithms for the purpose. He describes preliminary techniques (quadratic surfaces, inversion of birational maps, parametrization of a ...
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A Green's function for diffraction by a rational wedge
, 1989 In this paper we derive an expression for the point source Green's function for the reduced wave equation, valid in an angular sector whose angle is equal to a rational multiple of 77.
Rawlins, AD
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Journal of High Energy Physics, 2018 We constructed several families of elliptic K3 surfaces with Mordell-Weil groups of ranks from 1 to 4. We studied F-theory compactifications on these elliptic K3 surfaces times a K3 surface.
Yusuke Kimura
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Implicitization of Rational Parametric Surfaces
Journal of Symbolic Computation, 1996 Let \(S\subset \mathbb{C}^3\) be a surface parametrized by a map \(F_a(s,t)= (f_1(s,t),\;f_2(s,t),\;f_3(s,t))\), where \(f_i\) are polynomials in \(s\) and \(t\). The implicitization process would find an equation \(f(x,y,z)=0\) such that the zero locus of the equation, \(W=\{(x,y, z)\mid f(x,y,z) =0\}\), is the smallest subset \(W\subset \mathbb{C}^3\)
George J. Fix +2 more
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Progressive surface modeling scheme from unorganised curves
, 2006 This paper presents a novel surface modelling scheme to construct a freeform surface progressively from unorganised curves representing the boundary and interior characteristic curves.
Wright, David +3 more
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Computation of the degree of rational surface parametrizations [PDF]
, 2004 A rational affine parametrization of an algebraic surface establishes a rational correspondence of the affine plane with the surface. We consider the problem of computing the degree of such a rational map. In general, determining the degree of a rational
Sendra, J.Rafael +5 more
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Phosphatidylinositol 4‐kinase as a target of pathogens—friend or foe?
FEBS Letters, EarlyView.This graphical summary illustrates the roles of phosphatidylinositol 4‐kinases (PI4Ks). PI4Ks regulate key cellular processes and can be hijacked by pathogens, such as viruses, bacteria and parasites, to support their intracellular replication. Their dual role as essential host enzymes and pathogen cofactors makes them promising drug targets.
Ana C. Mendes +3 more
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Nonnegativity Preserving Interpolation by C1 Bivariate Rational Spline Surface
Journal of Applied Mathematics, 2012 This paper is concerned with the nonnegativity preserving interpolation of data on rectangular grids. The function is a kind of bivariate rational interpolation spline with parameters, which is C1 in the whole interpolation region.
Xingxuan Peng, Zhihong Li, Qian Sun
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