Distributional radius of curvature

We show that any continuous plane path that turns to the left has a well‐defined distribution that corresponds to the radius of curvature of smooth paths. We show that the distributional radius of curvature determines the path uniquely except for a translation. We show that Dirac delta contributions in the radius of curvature correspond to facets, that is, flat sections of the path, and show how a path can be deformed into a facet by letting the radius of curvature approach a delta function. Copyright © 2005 John Wiley & Sons, Ltd.     

The number of edges of radius-invariant graphs

The eccentricity e(υ) of vertex υ is defined as a distance to a farthest vertex from υ. The radius of a graph G is defined as r(G) = {e(u)}. We consider properties of unchanging the radius of a graph under two different situations: deleting an arbitrary edge and deleting an arbitrary vertex. This paper gives the upper bounds for the number of edges in such graphs. Supported by VEGA grant No. 1/0084/08.     

两部雷达部署的研究

本文研究了两部雷达联合发现目标概率 ,采用特征尺度的分析方法解决了最佳部署问题 ,得到了极其简单 ,计算量很小的关于确定最佳距离的有效公式 ,并用实际算例进行了验证     

The Inner Radius of Univalency of the Rhom busDom ain

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绿地喷浇设施的节水构想

为解决公共绿地浇灌的节水问题 ,在圆半径可变的条件下讨论正方形、等腰三角形、一般三角形区域的最优圆覆盖 .对正方形取以其四个顶点和中心点为圆心的五个扇形进行覆盖 ,从而使广阔绿地的有效浇灌率达到 84.88% .对三角形取以其三个顶点为圆心的三个扇形进行覆盖 ,计算出各扇形的最优半径 ,并证明对任意等腰三角形 ,本覆盖法的有效率不小于 82 .70 % .     

On the Radius of Spatial Analyticity for the Inviscid Boussinesq Equations

In this paper, we study the problem of analyticity of smooth solutions of the inviscid Boussinesq equations. If the initial datum is real-analytic, the solution remains real-analytic on the existence interval. By an inductive method we can obtain a lower bound on the radius of spatial analyticity of the smooth solution.     

Relations among five radii of circles in a triangle,its sides and other segments

Students use GeoGebra to explore the mathematical relations among different radii of circles in a triangle (circumcircle, incircle, excircles) and the sides and other segments in the triangle. The more formal mathematical development of the relations that follows the explorations is based on known geometrical properties, different formulas relating the radii to the sides and the inequalities between the different averages. The activities described were conducted with pre-service teachers of mathematics, with empirical investigation of the relations using dynamical geometry software, and formal presentation of proofs.     

Bounds and Majorization Relations for the Zeros of a Class of Fibonacci-Type Polynomials

We apply certain matrix inequalities involving eigenvalues, the numerical radius, and the spectral radius to obtain new bounds and majorization relations for the zeros of a class of Fibonacci-type polynomials. Our results improve upon some earlier bounds for the zeros of these polynomials.     

相容矩阵范数的延拓

利用构造性的方法证明了实方阵空间上的相容矩阵范数均可延拓到复方阵空间上。     

Maps preserving numerical radius or cross norms of products of self-adjoint operators

Let H be a complex Hilbert space with dimH ≥3, Bs（H） the （real） Jordan algebra of all self-adjoint operators on H. Every surjective map Ф ： Bs（H）→13s（H） preserving numerical radius of operator products （respectively, Jordan triple products） is characterized. A characterization of surjective maps on Bs （H） preserving a cross operator norm of operator products （resp. Jordan triple products of operators） is also given.     

关于实四元数矩阵的数值半径

本文在[1]的基础上研究了实四元数矩阵的数值半径。得到了关于数值半径幂的不等式。C-数值半径的不等式也给出了。因此我们推广了曹重光教授的结果。     

一个几何不等式的一般形式

文 [1 ]建立了关于 n维单形的棱长、体积与外接球半径的一个不等式 ,本文给出了这一结论的一般形式     

m重似星树的谱半径

仅有一个顶点的度大于2的树称为似星树.
在一棵似星树的每个一度点粘接一棵似星树构成的图称为$m$重似星树.
Gutman 和L. Shi给出了似星树谱半径的一个界.
在本文中我们给出了另外一个更简洁的证明方法并做了深入的讨论,
同时给出了$m$重似星树谱半径的一个最好界.     

Spectral radii and eigenvalues of subdivision operators

This paper discusses the spectra of matrix subdivision operators. We establish some formulas for spectral radii of subdivision operators on various invariant subspaces in . A formula for the spectral radius of a subdivision operator, in terms of the moduli of eigenvalues, is derived under a mild condition. The results are even new in the scalar case. In this case, we show that the subdivision operator has no eigenvector in if the corresponding subdivision scheme converges for some .

     

Radius of Starlikeness for Class S(a,n)and Its Extension

This paper obtain that the radius of starlikeness for class S(α,n)in [1] is,tespectivety,where α_ is unique solution of equation (αα)~(1/2)=σwith a in (0.1),and α-[1+(1-2α)r~(2n)]/(1-r~(2n)),σ=[1-(1-2α)r~]/(1+r~).Futhermore,we consider an extension of class S(α,n):Let S(α、β、n)denote the class of functions f(z)=z+α_z~(n+1)+…(n≥1)that are analytie in |z|<1 such that f(z)/g(z)∈p(α,n)[1],where g(z)∈S~*(β)[2].This paper prove that the radius of starlikeness of class S(α,β,n) is given by the smallest positive root(less than 1)of the following equations(1-2α)(1-2β)r~(2)-2[1-α-β-n(1-α)]r~+1=0.0≤α≤α_0,(1-α)[1-(1-2β)r~]-n[r~(1+r~)=0.,α_0≤α<1.where α=[1+(1-2α)r~(2)]/(1-r~(2)(0≤r<1),α_0(?(0,1) is some fixed number.This result is also thecxtension of well-known results[T.Th3] and [8,Th3]     

带有对称函数的实四数矩阵的广义数值半径

本文定义了带有对称函数的实四无数矩阵的广义数值半径并得到了它们所满足的不等式。     

张量对称类上诱导线性算子的数值半径

设V是一个n维线性空间,V_x~m(G)为V上的张量对称类.A为V的线性算子T的矩阵,K(A)为V_x~m(G)上的诱导线性算子K(T)的矩阵.本文从K(A)的数值半径Υ(K(A))和可分数值半径Υ_x(K(A))定义出发,研究了Υ(K(A))、Υ_x(K(A))与范数||A||_p(1≤p≤2)、广义矩阵函数d_x~G(A)的关系,得到了它们之间的两个不等式.     

一族Bloch函数的单叶半径与覆盖半径

研究了Bloch函数族B中的一个子族Bg,给出了Bg中函数的单叶半径.作为应用建立了Bg中函数的覆盖定理,从而刻画了Bg中函数的有关性质.