Torsional Models of Two - ply Yarn

In this paper,the vector equation of a generaliseddoubly wound helix was derived.Treloar's pliedyarn geometry could be obtained as a special case ofthe generalised doubly wound helix.The shortest fi-bre length around the surface of a helical tube(formed by fibre helices)was determined by apply-ing variational principles.The fibre length as calcu-lated by using Treloar's geometry was compared in-directly with the shortest possible fibre length at dif-ferent levels of yarn deformation when some of Tre-loar's rigid geometrical constraints were relaxed.Anew idea based on non-concentric circles was intro-duced to approximate the fibre helix movement in atwo-ply yarn.A torsional model of two-ply yarnwas developed and the theoretical predictions werecompared with some preliminary experimental re-sults.     

AN ANALYSIS OF SPLITTING EXTRAPOLATION FOR MULTIDIMENSIONAL PROBLEMS

The splitting extrapolation is an important technique for solving multidimensionalproblems.In the case that error u~h-u has an asymptotic expansion of form Σc_αh~(2α),whereα=(α_1,…,α_s) and h~α=h_1~(α_1),…h_s~(α_s),the method gives an approximation involving less computerstorage and less computational work in comparison with the classical Richardson extrapolation.In this paper we present a recurrence rule of the splitting extrapolation and discuss itsapplications in the fields of multiple integrals,multidimensional integral equations,partialdifferential equations and singular perturbation problems.