Qian-Qian Hu

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Conic section is one of the geometric elements most commonly used for shape expression and mechanical accessory cartography. A rational quadratic Bézier curve is just a conic section. It cannot represent an elliptic segment whose center angle is not less than. However, conics represented in rational quartic format when compared to rational quadratic format,(More)
PURPOSE We investigated the therapeutic effects and underlying mechanisms of topical doxycycline in a benzalkonium chloride (BAC)-induced mouse dry eye model. METHODS Eye drops containing 0.025%, 0.1% doxycycline or solvent were administered to a BAC-induced dry eye model four times daily. The clinical evaluations, including tear break-up time (BUT),(More)
This paper derives an approximation algorithm for multi-degree reduction of a degree n triangular Bézier surface with corners continuity in the norm L 2. The new idea is to use orthonormality of triangular Jacobi polynomials and the transformation relationship between bivariate Jacobi and Bernstein polynomials. This algorithm has a very simple and explicit(More)
Theoretical study shows that Said-Bézier generalized Ball curves (SBGB curves) are distinctly superior to Bézier curves in evaluation, degree elevation and reduction. However in practical engineering, there is no effective algorithm for explicit multi-degree reduction of SBGB curves with endpoints constraints in the world. It is going against designing and(More)
This paper applies inequality skill, degree elevation of triangular Bézier surfaces and difference operators to deduce the bounds on first and second partial derivatives of rational triangular Bézier surfaces. Further more, we prove that the new bounds are tighter and more effective than the known ones. All the results are obviously helpful for further(More)
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