结构布局几何可调的优化设计

对于结构优化设计问题其中X是设计变量;K是刚度矩阵;U是结构位移;F是外荷载;σ是应力.如果X分量含有结构布局的几何参数(如杆的长度、钣的面积、梁的长度等),则称为结构布局几何可调的优化设计问题.在上述问题中,h(X)=0是含有结构布局几何参数的等式关系.对于结构进行布局可调的优化设计,通常可以取得更为合理和良好的效果,然而为达到     

关于Jacobi矩阵的特征值反问题可解的充分必要条件的一个注记 (英)

本文讨论一类具有特殊结构的Jacobi矩阵的特征值反问题,该问题由描述变截面杆的微分方程离散化得到．我们得到了这个问题有解的一些必要条件,并且通过一些数值例子,说明了L．Lu和K．Michael给出的充分条件和算法在矩阵的阶数高于3的时候是错误的。     

带多重右边的不定最小二乘问题的条件数

本文研究了带多重右边的不定最小二乘问题的条件数,给出了范数型、混合型及分量型条件数的表达式,同时,也给出了相应的结构条件数的表达式.所考虑的结构矩阵包含Toeplitz 矩阵、Hankel矩阵、对称矩阵、三对角矩阵等线性结构矩阵与Vandermonde矩阵、Cauchy矩阵等非线性结构矩阵.数值例子显示结构条件数总是紧于非结构条件数.     

多杆空间柔性机器人递推Lagrange动力学建模和仿真

研究了多杆空间柔性机器人的动力学问题.运用Lagrange方法,结合齐次变换矩阵,推导得到了多杆空间柔性机器人动力学方程,在推导过程中采用了运动学递推策略以提高计算效率.建模时除考虑柔性构件的横向弯曲变形外,还计及了构件的扭转变形.基于上述理论研制了多杆空间柔性机器人动力学仿真软件,并对一空间柔性机器人进行了动力学仿真计算,验证了理论和软件的先进性能.     

考虑几何非线性的杆系结构弯曲变形样条有限点法

研究了杆系结构考虑几何非线性的大挠度弯曲变形问题,推算并验证了一种考虑几何非线性的杆系结构弯曲变形计算新方法.以三次B样条函数为基函数,采用广义参数法,构造出梁的样条基函数,通过最小势能原理,建立了杆系结构考虑几何非线性的刚度方程,对处于弹性范围内的杆系结构的大变形弯曲问题进行了计算,提出了考虑几何非线性时杆系结构弯曲变形计算的样条有限点法.结果表明:方法不用进行单元坐标变换、划分等分数少、收敛速度快且计算精度较高,是一种较传统有限元法更简单且可行的方法.     

空间杆系结构内力与变位的一种新解析法

本文以有限元法的思想为基础,引用Diracδ函数和Heaviside step函数,将梁的弯曲问题的初参数法推广应用到杆系结构,并据此改进超静定结构分析中的混合法,提出空间杆系结构内力与变位分析的一种新方法.采用本文提供的新方法分析杆系结构的内力与变位的问题,可使整个推导过程与所得解答更加简洁精确.     

求解结构矩阵低秩逼近的交替投影方法

结构矩阵低秩逼近在图像压缩、计算机代数和语音编码中有广泛应用.首先给出了几类结构矩阵的投影公式,再利用交替投影方法计算结构矩阵低秩逼近问题.数值试验表明新方法是可行的.     

对非对称有理细分矩阵的改进

在图形图像显示中,运算次数的多少直接影响图像的显示速度.通过对非对称细分矩阵的运算量较大的因素进行分析,并在分析的基础上对细分矩阵加以改进,简化细分矩阵结构减少一些不必要的运算与重复运算,构造出一种结构比较简单、运算量比较少的细分矩阵.新构造的细分矩阵可以有效的提高运算速度.应用新构造的细分矩阵生成细分曲线,对所生成的细分曲线进行比较,得出改进细分矩阵使得运算量明显减少,提高图形的显示速度.     

跳行范德蒙矩阵的三角分解

跳行范德蒙矩阵是一种重要的矩阵,在函数插值等方面有着重要的应用.根据跳行范德蒙矩阵的特殊结构,将跳行范德蒙矩阵分解为一系列下三角矩阵与一系列上三角矩阵的乘积.进一步给出了其逆矩阵分解为一系列上三角矩阵与一系列下三角矩阵的乘积的表达式.     

M-矩阵的性质与Hadamard-Fisher不等式的注记

主要研究了两个M-矩阵的比较性质与不等式,给出了M-矩阵与逆M-矩阵Hadamard-Fisher不等式等式成立的矩阵结构.     

Vibration control of micro-scale structures using their reduced second order bilinear models based on multi-moment matching criteria

This paper deals with vibration control of micro-scale structures; i.e. MEMS devices. For modeling of the structures, finite element method which is a distinguished and accurate technique will be used. This method, however, leads to a model with high number of degrees of freedom which may cause computational costs especially for control problems. Hence, we will apply the second order Krylov subspace method based on multi-moment matching to obtain a reduced order model which is in the form of a second order bilinear system. For vibration suppression of the corresponding micro-structure, a quadratic feedback controller and also a linear state feedback controller using linear matrix inequality (LMI) will be designed. Finally, a micro-cantilever beam will be considered as a practical case study and simulation results of applying the proposed method will be presented.     

The Harsanyi value for nontransferable utility games with restricted cooperation

A nontransferable utility (NTU) game assigns a set of feasible pay-off vectors to each coalition. In this article, we study NTU games in situations in which there are restrictions on coalition formation. These restrictions will be modelled through interior structures, which extend some of the structures considered in the literature on transferable utility games for modelling restricted cooperation, such as permission structures or antimatroids. The Harsanyi value for NTU games is extended to the set of NTU games with interior structure.     

Waves in periodic structures with imperfections

The study of wave propagation in structures and media has a significant history which follows from the examination of the dynamics of atomic and molecular lattices. Relatively recently, some of these ideas have been transferred and applied to the dynamic behavior of engineered structures. In particular, structures with periodic and almost periodic topologies and material properties have been extensively studied and important conclusions drawn regarding their energy-transmission properties. The attraction to wave propagation models is due to the efficient nature of the analytical tools available to study how energies of different frequency content are propagated or filtered by the structure. Such properties of a structure are profoundly affected by any imperfections or “near-periodicities”. It has been found that imperfections will have the effect of localizing energies about them, thus not allowing the development of normal modes of vibration as would be observed when assuming a perfect structure. It is envisioned that such understanding will permit the analyst to take advantage of localization effects to isolate locations experiencing loading. Additional applications possibly include the modeling of composite and layered structures and cracks. Also, one expects that structures with periodic boundary conditions will experience some sort of localization of energies in certain frequency ranges.     

On componentwise condition numbers for eigenvalue problems with structured matrices

We give explicit expressions for the componentwise condition number for eigenvalue problems with structured matrices. We will consider only linear structures and show a general result from which expressions for the condition numbers follow. We obtain explicit expressions for the following structures: Toeplitz and Hankel. Details for other linear structures should follow in a straightforward manner from our general result. Copyright © 2008 John Wiley & Sons, Ltd.     

Structures preserved by the QR-algorithm

In this paper we investigate some classes of structures that are preserved by applying a (shifted) QR-step on a matrix A. We will handle two classes of such structures: the first we call polynomial structures, for example a matrix being Hermitian or Hermitian up to a rank one correction, and the second we call rank structures, which are encountered for example in all kinds of what we could call Hessenberg-like and lower semiseparable-like matrices. An advantage of our approach is that we define a structure by decomposing it as a collection of ‘building stones’ which we call structure blocks. This allows us to state the results in their natural, most general context.     

Knowledge structure,knowledge granulation and knowledge distance in a knowledge base

One of the strengths of rough set theory is the fact that an unknown target concept can be approximately characterized by existing knowledge structures in a knowledge base. Knowledge structures in knowledge bases have two categories: complete and incomplete. In this paper, through uniformly expressing these two kinds of knowledge structures, we first address four operators on a knowledge base, which are adequate for generating new knowledge structures through using known knowledge structures. Then, an axiom definition of knowledge granulation in knowledge bases is presented, under which some existing knowledge granulations become its special forms. Finally, we introduce the concept of a knowledge distance for calculating the difference between two knowledge structures in the same knowledge base. Noting that the knowledge distance satisfies the three properties of a distance space on all knowledge structures induced by a given universe. These results will be very helpful for knowledge discovery from knowledge bases and significant for establishing a framework of granular computing in knowledge bases.     

Multi-adjoint algebras versus non-commutative residuated structures

Adjoint triples and pairs are basic operators used in several domains, since they increase the flexibility in the framework in which they are considered. This paper introduces multi-adjoint algebras and several properties; also, we will show that an adjoint triple and its “dual” cannot be considered in the same framework.Moreover, a comparison among general algebraic structures used in different frameworks, which reduce the considered mathematical requirements, such as the implicative extended-order algebras, implicative structures, the residuated algebras given by sup-preserving aggregations and the conjunctive algebras given by semi-uninorms and u-norms, is presented. This comparison shows that multi-adjoint algebras generalize these structures in domains which require residuated implications, such as in formal concept analysis, fuzzy rough sets, fuzzy relation equations and fuzzy logic.     

典型非线性模型的模糊辨识逼近精度分析

人们根据非线性系统的复杂特性归结了几种具有代表性的非线性模型.而模糊辨识方法是辨识非线性系统的有力工具,本文采用T-S模糊模型对三种常见的非线性模型:Hammerstein模型,Wiener模型和双线性模型进行逼近,并根据仿真数据研究不同的非线性结构对模糊模型逼近精度的影响.仿真实例是在训练和检验数据组数、模型阶数相同的情况下,采用三角形隶属函数,聚类型隶属函数和高斯型隶属函数分别对这三种非线性模型进行逼近能力的研究.     

Algebras in the Positive Cone of po-Groups

We systemize a number of algebras that are especially known in the field of quantum structures and that in particular arise from the positive cones of partially ordered groups. Generalized effect algebras, generalized difference posets, cone algebras, commutative BCK-algebras with the relative cancellation property, and positive minimal clans are included in the text.All these structures are conveniently characterizable as special cases of generalized pseudoeffect algebras, which we introduced in a previous paper. We establish the exact relations between all mentioned structures, thereby adding new structures whenever necessary to make the scheme of order complete.Generalized pseudoeffect algebras were under certain conditions proved to be representable by means of a po-group. From this fact, we will easily establish representation theorems for all of the structures included in discussion.     

李代数W(2,2)上的Hom-李代数结构

李代数W（2，2）是一类重要的无限维李代数，它是在研究权为2的向量生成的顶点算子代数的过程当中提出来的.Hom-李代数是指同时具备代数结构和李代数结构的一类代数，并且乘法与李代数乘法运算满足Leibniz法则.本文确定了李代数W（2，2）上的Hom-李代数结构.主要结论是李代数W（2，2）上没有非平凡的Hom-李代数结构.本文的研究结果对于W（2，2）代数的进一步研究有一定的帮助作用.