Some Properties of the Optimal Preconditioner and the Generalized Superoptimal Preconditioner

The optimal preconditioner and the superoptimal preconditioner were proposed in 1988 and 1992 respectively. They have been studied widely since then. Recently, Chen and Jin [6] extend the superoptimal preconditioner to a more general case by using the Moore-Penrose inverse. In this paper, we further study some useful properties of the optimal and the generalized superoptimal preconditioners. Several existing results are extended and new properties are developed.

A COMPARISON OF FOUR RUN-IN PREDICTION METHODS IN RASCHEL WARP KNITTING

In this paper, the run-in values predicted by four methods are compared with the measuredvalues, and some suggestions have been made. The negative let-off motion is different from thepositive let-off motion, so that in the machine with negative let-off device, fabric structure is animportant factor determining the run-in value.

BIFURCATIONS OF AIRFOIL IN INCOMPRESSIBLE FLOW

Bifurcations of an airfoil with nonlinear pitching stiffness in incompressible flow are investigated. The pitching spring is regarded as a spring with cubic stiffness. The motion equations of the airfoil are written as the four dimensional one order differential equations. Taking air speed and the linear part of pitching stiffness as the parameters, the analytic solutions of the critical boundaries of pitchfork bifurcations and Hopf bifurcations are obtained in 2 dimensional parameter plane. The stabilities of the equilibrium points and the limit cycles in different regions of 2 dimensional parameter plane are analyzed. By means of harmonic balance method, the approximate critical boundaries of 2-multiple semi-stable limit cycle bifurcations are obtained, and the bifurcation points of supercritical or subcritical Hopf bifurcation are found. Some numerical simulation results are given.

A Precise Asymptotic Behaviour of the Large Deviation Probabilities for Weighted Sums

Let {Xn, n ≥ 1} be a sequence of independent and identically distributed positive valued random variables with a common distribution function F. When F belongs to the domain of partial attraction of a semi stable law with index α, 0 < α < 1, an asymptotic behavior of the large deviation probabilities with respect to properly normalized weighted sums have been studied and in support of this we obtained Chover’s form of law of iterated logarithm.

A LIL and Limit Distributions for Trimmed Sums of Random Vectors Attracted to Operator Semi-stable Laws

Let θ∈^d be a unit vector and let X, X1, X2,…… be a sequence of i.i.d. Xd-valued random vectors attracted to operator semi-stable laws. For each integer n ≥1, let X1,≤……≤ Xn,n denote the order statistics of X1, X2,..., Xn according to priority of index, namely ｜（X1,nθ）｜≥…≥ [（Xn,n,θ）1, where （., .） is an inner product on Rd. For all integers r ≥ 0, define by （r）Sn =∑n-r i=1Xi,n the trimmed sum. In this paper we investigate a law of the iterated logarithm and limit distributions for trimmed sums （r）Sn. Our results give information about the maximal growth rate of sample paths for partial sums of X when r extreme terms are excluded. A stochastically compactness of （r）Sn is obtained.

On Monodromy of Semi-stable Fibres

The fibration is one of the fundamental methods in the study of algebraic surfaces. In the early years, fibration was studied by using the method of complete classification of singular fibres, which was obtained through studying the combinatorical properties of singular fibres. But with the rising of the genus of fibration, this method will not work now. In 1977, a more essential classification of singular fibres of genus two was given by Eiji Horikawa by using relative canonical maps. Prof. Xiao Gang has successfully improved the classification of Horikawa and effectively studied some algebra.ic surfaces by using his classification. We know that, ordinarily, through the classification of singular fibres, parameters of fibration can be obtained. Based on this, we study the properties of surfaces. But for some parameters, we can effectively describe them only by the study of combinatorical properties and topological

Semi-stable distributions in free probability theory

Semi-stable distributions, in classical probability theory, are characterized as limiting distributions of subsequences of normalized partial sums of independent and identically distributed random variables. We establish the noncommutative counterpart of semi-stable distributions. We study the characterization of noncommutative semi-stability through free cumulant transform and develop the free semi-stability and domain of semi-stable attraction in free probability theory.

Log Structures on Generalized Semi-Stable Varieties

In this paper, a class of morphisms which have a kind of singularity weaker than normal crossing is considered. We construct the obstruction such that the so-called semi-stable log structures exists if and only if the obstruction vanishes. In the case of no power, if the obstruction vanishes, then the semi-stable log structure is unique up to a unique isomorphism. So we obtain a kind of canonical structure on this family of morphisms.

A Note on Bogomolov-Type Inequality for Semi-stable Parabolic Higgs Bundles

In this paper,we prove a Chern number inequality for Higgs bundles over some Kähler manifolds.As an application,we get the Bogomolov inequality for semi-stable parabolic Higgs bundles over smooth projective varieties.

Canonical Metrics on Holomorphic Filtrations over Compact Hermitian Manifolds

The purpose of this paper is twofold.We first solve the Dirichlet problem forτ-Hermitian-Einstein equations on holomorphic filtrations over compact Hermitian manifolds.Secondly,by using Uhlenbeck-Yau’s continuity method,we prove the existence of approximateτ-Hermitian-Einstein structure on holomorphic filtrations over closed Gauduchon manifolds.