一类具独立子系统的退化时滞控制系统的能控性

讨论退化时滞微分控制系统的能控性问题.首先将退化时滞微分控制系统化为标准形式,除去关联项,得到具独立子系统的退化时滞微分控制系统.然后就一般的退化时滞微分控制系统,得到其能控的充要条件为其可达集等于全空间.对于具独立子系统的广义时滞控制系统,给出其能控的充要条件为每个子系统的可达集等于其相应的子空间,并给出其能控的代数判据,最后举例说明主要结果的应用.     

关于凸函数的一个分析性质的充要条件

凸函数是一类重要的函数,其等价命题很多,但没有揭示其分析性质,本文给出凸函数的一个分析性质的充要条件.     

一个不等式的三种证明

针对某教材中关于凹函数不等式的一道证明题,分别采用单调性、泰勒公式和中值定理给出三种证明方法,旨在帮助学生拓展其思维广度,培养其综合能力,提高其数学素质．     

角的二次变换与角范围的隐含条件

在高中数学必修四第三章三角恒等变换中,我们重点是围绕和差倍半角的变换公式的推导和应用,培养运算能力和推理能力,从而体现其数学价值,同时,也是利用三角函数解决问题的工具,体现其应用价值.这一章虽只有8课时,但其在培养思维品质和高考中的重     

角的二次变换与角范围的隐含条件

在高中数学必修四第三章三角恒等变换中,我们重点是围绕和差倍半角的变换公式的推导和应用,培养运算能力和推理能力,从而体现其数学价值,同时,也是利用三角函数解决问题的工具,体现其应用价值．这一章虽只有8课时,但其在培养思维品质和高考中的重要性是不言而喻的．     

具有广义FGM相依结构的复合泊松过程的Esscher定价泛函

本文考虑索赔额与等待时间具有广义FGM相依结构的复合泊松过程,仿照文献[5]的方法,求出了其矩母函数的显式表达式,给出了其矩母函数的n阶导数的计算方法,并最终求出了其Esscher定价泛函．     

截面代数的Hochschild上同调

计算了任意域上的截面代数的Hochschild上同调群的维数, 并证明了其Hochschild上同调代数是有限维的当且仅当其整体维数有限、其Gabriel箭图没有定向圈.     

加快迭代收敛速度的两个命题

定义了单调收敛函数和交错收敛函数,并根据其收敛特点,提出并证明了加快其收敛速度的两个命题.算例表明其效果较好.     

具分布时滞的广义系统周期解的存在性

研究了一类具分布时滞的广义系统模型,用矩阵测度和Krasnoselskii不动点定理获得了其周期解存在的若干充分条件,并举例说明其应用.     

计及边缘效应的平行板电容器单位长度电容的计算

将保角变换法与格林函数法相结合,研究计及边缘效应的平行板电容器的电场,得到其电势和场强分布,利用软件MATLAB对场分布进行数值模拟,给出其单位长度电容量的计算公式,并与忽略边缘效应的电容量的计算公式进行比较,得到两计算公式产生的相对误差随其宽与板间距之比变化的函数关系.     

星体径向弦长积分

我们引入星体的径向弦长积分的概念,并研究了它的性质．作为它的应用,建立了径向弦长积分的循环不等式、Brunn-Minkowski型不等式和对偶Bieberbach型不等式．     

DIMENSION AND DIFFERENTIABILITY OFA CLASS OF FRACTAL INTERPOLATION FUNCTIONS

Abstract. In this paper, a new iterated function system consisting of non-linear affine maps is constructed. We investigate the fractal interpolation functions generated by such a system and get its differentiabillty, its box dimension, its packing dimension,and a lower bound of its Hausdorff dimension.     

Hochschild cohomology of truncated quiver algebras

For a truncated quiver algebra over a field of an arbitrary characteristic, its Hochschild cohomology is calculated. Moreover, it is shown that its Hochschild cohomology algebra is finitedimensional if and only if its global dimension is finite if and only if its quiver has no oriented cycles.     

A generalization of Lelieuvre’s formula to equiaffine immersions of general codimension

A non-degenerate equiaffine immersion of codimension one into an equiaffine space is locally expressed in terms of its conormal map and its affine fundamental form. The expression is called the Lelieuvre’s formula. We recently defined the notions of an equiaffine immersion of general codimension and its transversal volume element map. In this paper, we locally express a non-degenerate equiaffine immersion of general codimension into an equiaffine space in terms of its transversal volume element map and its affine fundamental form.     

关于分布重尾程度的一类刻画

针对应用概率研究的需要,提出了较重尾分布的概念,以失效函数为工具,着重探讨并得到了一些利用相互比较重尾程度来确定分布族的方法.     

Mathematical features of the Calculus

The fundamental theorems of the calculus describe the relationships between derivatives and integrals of functions. The value of any function at a particular location is the definite derivative of its integral and the definite integral of its derivative. Thus, any value is the magnitude of the slope of the tangent of its integral at that position, and any two subtracted values are the area under its derivative. The slope formula of secant lines actually is the mean value theorem for the derivative function in addition to representing the well-known Fermat definition of the derivative. The sine and other functions are discussed.     

Flatness Properties of S-Posets

We investigate the Galois coverings of weakly shod algebras. For a weakly shod algebra not quasi-tilted of canonical type, we establish a correspondence between its Galois coverings and the Galois coverings of its connecting component. As a consequence we show that a weakly shod algebra which is not quasi-tilted of canonical type is simply connected if and only if its first Hochschild cohomology group vanishes.     

Non-primitive number fields of degree eight and of signature with small discriminant

We give the lists of all non-primitive number fields of degree eight having two, four and six real places of discriminant less than 6688609, 24363884 and 92810082, respectively, in absolute value. For each field in the lists, we give its discriminant, the discriminant of its subfields, a relative polynomial generating the field over one of its subfields and its discriminant, the corresponding polynomial over , and the Galois group of its Galois closure.

     

The contribution of mathematical modelling to the practice of project management

This paper looks at the contribution that mathematical modellinghas made to project management over the past 50 years, and thecontribution it is currently making and can make in the future.Project Management started with well-defined foundations posingprecise, well-defined problems. In its growing phase, modellersplayed an essential role in taking the problems defined by theproject-management world and offering solutions, from the originalPERT, through resource allocation and levelling procedures,Monte Carlo simulation models, criticality analyses and so on.Since then, however, while the project management field itselfhas tried to establish its procedures, keeping to its philosophicalstance, much of the mathematical-modelling world has continuedalong its trajectory, producing ever more complex solutionsto ever more complex models, motivated by mathematical impressivenessrather than the need to solve real-world problems. This paperoutlines much of this work, some of which does find its wayinto project-network software but much of which languishes injournals. However, over the last decade or so, Operational Researchershave begun to build models of projects that are systemic anddynamic and explain many of the behaviours of projects thatconventional decomposition models do not; and at the same time,some of the Project Management world has started to realizethe limitations of its philosophical stance and started lookingto build new theory for modern, complex, dynamic projects. Asthese two trends come together, it is essential that modellersare at the forefront of building this new theory.     

Generalized expression of exergy in the thermodynamics

Exergy is the ability of the maximum work done to the objective (relative) outside when the system changes from any state to its dead state. Exergy stems from the gaps of intensive properties between its present state and its dead state. Generalized differential expression of exergy is advanced without any premise conditions, which is composed of generalized intensive and extensive (additive) properties. Any form of exergy can be deduced out from this generalized expression, only if its characteristic intensive and extensive parameters are known. That the exergy of any closed system is never below zero has been proved.