一类组合投资问题的线性规划解法

根据选定总体风险的一个上界值使组合投资的收益率达到最大的原则，并在合理简化的基础上建立组合投资决策问题的线性规划模型。然后通过算例求解带有参数的线性规划问题，给出资产组合的风险控制值和相应的最大净收益率及投资比例向量的关系。     

On a generalization of the Kalman-Yakubovic lemma

In this paper we generalize the Kalman-Yakubovic lemma to infinite dimensions—or, more precisely, to semigroups of operators over a Hilbert space. The proof differs substantially from the finite-dimensional version and is based on the Paley-Wiener-Helson-Lowdenslager factorization theorem.     

漫反射物的实时互相关运算

发展一种价格便宜、体积小、操作方便的空间光调制器——液晶电视,完成非相干-相干转换.由BSO晶体构成的实时光学相关器完成漫反射物的实时互相关运算.     

实四元数矩阵的数值半径

本文定义了实四元数矩阵的数值半径,并讨论了它与矩阵迹、谱范数的关系,得到了一些等式与不等式.     

实对称矩阵的迹的几点性质

研究实对称矩阵的迹的几点性质，给出６个引理，推得３个定理     

基于系统调用的实时IDS方案

给出一种基于进程系统调用的实时IDS方案.该方案选择网络服务进程(特权进程)作为系统的代表进行监测,使用隐马尔可夫模型(HMM)对系统行为进行模拟和测试,使用实时P(O|λ)值和近期对“某些重要文件”的读、写频率这两个条件作为判断系统是否遭受入侵的标准.实验和分析表明,该方案有较高的预报准确率和较小的时间开销.     

Effects of pollution restrictions on dynamic investment policy of a firm

The purpose of this paper is to determine the effects of different pollution standards on the firm's resource allocation decisions. To do so, a dynamic model of the firm is developed in which it is assumed that production causes pollution as an inevitable byproduct. Concerning its investment policy, we suppose that the firm can choose between investing in productive capital goods and investing in abatement efforts.It is shown that, in some cases, future abatement expenses have a negative impact on the present level of productive investment, even if the pollution standard is not binding at the moment. This implies a really dynamic optimal investment policy for the firm, which cannot be obtained within a comparative static analysis.This research has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences. Comments by Frank van der Duyn Schouten and Piet Verheyen (Tilburg University) and by Raymond Gradus (Dutch Ministry of Finance, The Hague) are gratefully acknowledged.     

The numerical range of a nonnegative matrix

We offer an almost self-contained development of Perron–Frobenius type results for the numerical range of an (irreducible) nonnegative matrix, rederiving and completing the previous work of Issos, Nylen and Tam, and Tam and Yang on this topic. We solve the open problem of characterizing nonnegative matrices whose numerical ranges are regular convex polygons with center at the origin. Some related results are obtained and some open problems are also posed.     

Perpendicular Dissections of Space

For each pair (Q _i ,Q _j ) of reference points and each real number r there is a unique hyperplane h \perp Q _i Q _j such that d(P,Q _i ) ² - d(P,Q _j ) ² = r for points P in h . Take n reference points in d -space and for each pair (Q _i ,Q _j ) a finite set of real numbers. The corresponding perpendiculars form an arrangement of hyperplanes. We explore the structure of the semilattice of intersections of the hyperplanes for generic reference points. The main theorem is that there is a real, additive gain graph (this is a graph with an additive real number associated invertibly to each edge) whose set of balanced flats has the same structure as the intersection semilattice. We examine the requirements for genericity, which are related to behavior at infinity but remain mysterious; also, variations in the construction rules for perpendiculars. We investigate several particular arrangements with a view to finding the exact numbers of faces of each dimension. The prototype, the arrangement of all perpendicular bisectors, was studied by Good and Tideman, motivated by a geometric voting theory. Most of our particular examples are suggested by extensions of that theory in which voters exercise finer discrimination. Throughout, we propose many research problems. Received July 20, 2000, and in revised form September 29, 2001, and October 12, 2001. Online publication March 4, 2002.     

矩阵系统扰动后的稳定性问题

本文证明：若矩阵系统是广义各态历经的，则系统是稳定的；若矩阵系统是善真的，则系统是条件稳定的。