We present a new method for computing intersections of two parametric B-Spline curves. We use an intersection of the control polygons as an approximation for an intersection of the curves in combination with knot insertion. The resulting algorithm is asymptotically Newton-like, but without the need of a starting value. Like Newton’s method, it converges quadratically at transversal intersection...

The present research investigates the implementations of different computational geometry technologies in isogeometric analysis framework for computational fracture mechanics. NURBS and T-splines are two different computational geometry technologies which are studied in this work. Among the features of B-spline basis functions, the possibility of enhancing a B-spline basis with discontinuities ...

Knot-related defects are the major cause of timber quality degradation, and diminishing this kind of defects is an important issue in forest management. For the purpose of clear-wood production, knot attributes and branch occlusion of Betula alnoides under natural pruning were investigated in a 14-year-old experimental plantation with five planting densities ranging from 500 to 3333 stems per h...

OBJECTIVES To determine risk factors for short and long umbilical cord, entanglement and knot. Explore their associated risks of adverse maternal and perinatal outcome, including risk of recurrence in a subsequent pregnancy. To provide population based gestational age and sex and parity specific reference ranges for cord length. DESIGN Population based registry study. SETTING Medical Birth ...

The authors present their experience in prenatal diagnosis of placental and umbilical cord pathologies, using three-dimensional ultrasound (3DUS) in the rendering and tomography ultrasound imaging (TUI) modes, associated with color Doppler in some cases. Cases of placenta accreta/placenta previa, circumvallate placenta, succenturiate lobe, true knot of the umbilical cord, nuchal cord, and margi...

The construction of weighted splines by knot insertion techniques such as deBoor and Oslo type algorithms leads immediately to the problem of evaluating integrals of polynomial splines with respect to the positive measure possessing piecewise constant density. It is for such purposes that we consider one possible way for simple and fast evaluation of primitives of products of a polynomial B-spl...

Background: True knot of the umbilical cord is an uncommon finding, which is difficult to diagnose antenatally. The appropriate management of patients with a sonographically identified true knot is yet to be determined. Case: We present a twin pregnancy, in which antenatal diagnosis of a true knot of the umbilical cord was made at 33 weeks’ gestation. Fetal Doppler examination showed an absence...

We have read with interest the article by Cohen et al. entitled “Twelve-month contraceptive continuation and repeat pregnancy among young mothers choosing post-delivery contraceptive implants or postplacental intrauterine devices” [1]. What strikes us time and time again in articles published on postplacental/postpartum insertion of IUDs is the unacceptable high total expulsion as well as the h...

This paper proposes a simple approach to the affine motion interpolation problem, where an affine spline motion is generated that interpolates a given sequence of affine keyframes and satisfies approximately rigidity constraints and certain optimization criteria. An affine spline motion is first generated so as to interpolate the given keyframes; after that, it is progressively refined via knot...

Subdivision surfaces would be useful in a greater number of applications if an arbitrary-degree, non-uniform scheme existed that was a generalisation of NURBS. As a step towards building such a scheme, we investigate non-uniform analogues of the Lane-Riesenfeld ‘refine and smooth’ subdivision paradigm. We show that the assumptions made in constructing such an analogue are critical, and conclude...