正交小波变换的向量空间算法

本文揭示了一个事实，小波不仅可构成Ｌ２空间中的正交基，小波分解与重构滤波还可产生Ｎ维空间中的正交基．在本文提出修改的小波变换算法之下，Ｎ点信号的小波变换等价于Ｎ维空间中的正交变换．用该算法进行信号或图象压缩，无需对信号或图象进行周期延拓，可严格地在Ｎ维空间中进行．     

基于TMS320C 5410EVM 板FIR滤波器算法与设计方法研究

数字滤波器是语言、图象处理、模式识别以及谱分析中的基本运算的处理运算。本文研究DSP中有限冲击响应(FIR)滤波器的原理并结合TM320C5410EVM板介绍FIR滤波器设计方法以及DSP中FIR滤波嚣的实现方法。     

Das Elmikon,ein elektromechanischer Bildverstärker und Bildwandler

Summary Proceeding from some basic ideas of the known Eidophor System, the conception of the Elmicon, a new type of image amplified and converter, is derived. A picture signal influencesan electric field by its action on a photoconductor. The electric field itself produces deformations of a jellylike substance and controls in this way the light flux of a Schlieren system. Following a general discussion of the underlying ideas, the practical results hitherto obtained are reported.     

Arnol’d tongues for a resonant injection-locked frequency divider: Analytical and numerical results

In this paper we consider a resonant injection-locked frequency divider which is of interest in electronics, and we investigate the frequency locking phenomenon when varying the amplitude and frequency of the injected signal. We study both analytically and numerically the structure of the Arnol’d tongues in the frequency–amplitude plane. In particular, we provide exact analytical formulae for the widths of the tongues, which correspond to the plateaux of the devil’s staircase picture. The results account for numerical and experimental findings presented in the literature for special driving terms and, additionally, extend the analysis to a more general setting.     

董事会控制与盈余质量——中国证券市场的实证分析

基于我国沪深两市上市公司2002年至2005年的数据,对我国上市公司从董事会结构和董事会成员工作情况角度,对董事会在上市公司盈余质量上的控制作用进行了实证分析.实证发现:董事会规模较大、董事会中设立审计委员会对公司盈余质量的正面作用越大,且相对于基本盈余回报模型,有增量信息解释能力.董事会规模在13人时,董事会对盈余质量的正面效应最大.董事会成员工作情况(董事会开会的次数、独立董事的工作地点与公司所在地一致性、成立一年以上的审计委员会)对盈余质量的提高有一定的成效,且相对于基本盈余回报模型,有一定的增量信息解释能力.但实证不支持独立董事对盈余质量提高的正面作用.     

Integral geometry of complex space forms

We show how Alesker’s theory of valuations on manifolds gives rise to an algebraic picture of the integral geometry of any Riemannian isotropic space. We then apply this method to give a thorough account of the integral geometry of the complex space forms, i.e. complex projective space, complex hyperbolic space and complex Euclidean space. In particular, we compute the family of kinematic formulas for invariant valuations and invariant curvature measures in these spaces. In addition to new and more efficient framings of the tube formulas of Gray and the kinematic formulas of Shifrin, this approach yields a new formula expressing the volumes of the tubes about a totally real submanifold in terms of its intrinsic Riemannian structure. We also show by direct calculation that the Lipschitz-Killing valuations stabilize the subspace of invariant angular curvature measures, suggesting the possibility that a similar phenomenon holds for all Riemannian manifolds. We conclude with a number of open questions and conjectures.     

审计委员会的设立与公司治理——基于审计收费的实证研究

采用非参数检验方法和回归分析方法,本文从审计费用率视角研究了审计委员会的设立对上市公司治理的影响。本文发现,在设立审计委员会的样本和未设立审计委员会的样本之间,董事会的规模和独立性、独立董事规模和报酬存在显著差异,且这些变量及独立董事规模、审计任期与审计费用率的相关性不同。结果表明,审计委员会在加强独立董事责任和董事会、外部审计师独立性的同时,也改善了公司内部控制系统,但整体上并没有改变审计师的任期。     

Partial Decomposition of a Domain Containing Thin Tubes for Solving the Heat Equation

An initial–boundary value problem for the heat equation in a three-dimensional domain containing thin cylindrical tubes is considered. The Neumann condition is set on the lateral boundaries of the tubes. The original three-dimensional problem is reduced to a hybrid-dimensional one in which the heat equation in the tubes is replaced by the one-dimensional heat equation in shorter cylinders (subtubes), and the three- and one-dimensional equations are matched on the bases of the subtubes. The difference between the solutions of the original and hybrid-dimensional problems is estimated using two geometric characteristics: the distance between the bases of the tubes and subtubes and the reciprocals of the minimal positive eigenvalues of the Neumann problem for the Laplace operator in the tube cross sections.     

Effect of fiber orientation and cross section of composite tubes on their energy absorption ability in axial dynamic loading

The crushing behavior of composite tubes in axial impact loading is investigated. Tubes of circular and rectangular cross section are simulated using an LS-DYNA software. The effect of fiber orientation on the energy absorbed in laminated composite tubes is also studied. The results obtained show that rectangular tubes absorb less energy than circular ones, and their maximum crushing load is also lower. The composite tubes with a [+θ/ -θ] lay-up configuration absorb a minimum amount of energy at θ = 15°. The simulation results for a rectangular composite tube with a [+30/–30] lay-up configuration are compared with available experimental data. Cylindrical composite tubes fabricated from woven glass/polyester composites with different lay-ups were also tested using a drop-weight impact tester, and very good agreement between experimental and numerical results is achieved.     

Diffusion and convection in a family of tubes

Global existence theorems are given for the solutions of the renal flow equations for a system of parallel tubes. In the system, a solute moves in a fluid through the tubes by diffusion and convection and the tubes exchange fluid and solute with each other through the tube walls. The proofs use a fixed point argument. It is shown that the hypotheses of the theorems include the passive and convective flux formulas used in renal models.     

Array P systems with permitting features

The biologically inspired model, known as P system, has proved to be a general framework for investigating several problems related to computing in different fields. Two-dimensional picture array languages is one such area in which different kinds of P systems have been constructed for picture array generation. Incorporating the feature of permitting symbols in the rules, a new variety of array P system is constructed here for generating picture languages consisting of picture arrays. The advantage of this approach is that there is a reduction in the number of membranes used in the construction, in comparison to the existing array P system models.     

The effectiveness of corporate governance: board structure and business technical efficiency in Spain

This study seeks to determine the effectiveness of corporate governance by analyzing the impact of board structure on firm technical efficiency. Resampling methods and bootstrapping techniques applied in Data Envelopment Analysis are used to evaluate firm performance. Truncated regressions are estimated to determine the effect of five board characteristics—board size, board independence, board reputation, board diversity and board activity—on efficiency. The result of this empirical study shows that business technical efficiency increases with a heterogeneous board with a limited number of directorships per director and with a limited activity specified in a reduced number of annual board meetings with a higher number of specialized committees.     

Board structure and firm technical efficiency: Evidence from Canadian state-owned enterprises

The objective of the study is to analyze the board–performance relationship for a group of 14 Canadian SOEs. This context is unique because SOEs do not have major control devices other than the board. As the interaction effect, if any, between the board and other corporate governance structures is expected to be low, we do not have to fully control for the potential impact of different control devices, or to disentangle them completely from influencing board composition. The performance is also measured using data envelopment analysis (DEA), a linear programming method used for the first time in this research area. As such, this study contributes to the operational research literature while applying DEA method to untraditional fields of research.     

Diamond折纸管状结构轴向冲击性能分析

为了降低薄壁管状结构受轴向冲击时的初始峰值载荷,将diamond刚性折纸模型引入到薄壁管状结构的设计中.利用有限元分析方法,以方形截面为例,分析了diamond折纸管状结构的轴向冲击性能.结果表明:相比于传统方形薄壁管,diamond折纸管状结构具有较低的初始峰值载荷和更加平稳的变形过程.得出了diamond折纸管状结构按折纸预折形式变形的临界条件.分析了diamond折纸管状结构在轴向冲击载荷作用下,底角对初始峰值载荷和平均冲击载荷的影响.     

Picture Books as an Impetus for Kindergartners' Mathematical Thinking

Although there is evidence that the use of picture books affects young children's achievement scores in mathematics, little is known about the cognitive engagement and, in particular, the mathematical thinking that is evoked when young children are read a picture book. The focus of the case study reported in this article is on the cognitive engagement that is facilitated by the picture books themselves and not on how this engagement is prompted by a reader. The book under investigation, Vijfde zijn [Being Fifth], is a picture book of high literary quality that was not written for the purpose of teaching mathematics. The story is about a doctor's waiting room and touches on backwards counting and spatial orientation only tacitly as part of the narrative. Four 5 year olds were each read the book by one of the authors without any questioning or probing. The reading sessions took place in school, outside the classroom. A detailed coding framework was developed for analyzing the children's utterances that provided an in-depth picture of the children's spontaneous cognitive engagement. Surprisingly, almost half the utterances were mathematics-related. The findings of the study support the idea that reading children picture books without explicit instruction or prompting has large potential for mathematically engaging children.     

Heat Conduction of Structures with a System of Capillary Tubes

We obtain equations that describe heat conduction of bodies spatially reinforced by a system of capillary tubes filled with a moving heat-tapping fluid. The corresponding initial boundary-value problem of heat conduction is formulated and qualitatively analyzed. For thin-walled structures, we present an algorithm for reduction of the three-dimensional problem to a two-dimensional one. Specific calculations in solving the formulated problem are performed in the stationary and axisymmetric cases for a conic shell of revolution. The influence of the reinforcement parameters (intensity and direction), velocity of fluid motion in thermal tubes, dimensions of the inner sections of the tubes, and cone angle of a shell on the temperature field is investigated.     

公司盈余质量:董事会微观治理绩效之考察——来自我国独立董事制度强制性变迁的经验证据

本文选用我国上市公司董事会结构变迁背景下的经验数据,系统地考察了董事会特征对公司盈余信息披露质量的治理效应问题.研究结果表明,董事会的独立性、专业性特征是影响我国上市公司财务呈报质量的重要因素,即:公司拥有更高比例的独立董事、拥有财务独立董事、或者设立审计委员会,均能更好地抑制公司的盈余管理行为;但作为表征董事会行为特征的变量,如董事会持股水平、董事会年度会议频率和兼任控股股东职务等,却与公司盈余质量之间没有显著关系;而且,在认同审计委员会与独立董事制度能够发挥财务报告监督作用的同时,亦要避免其形式上的装饰现象。     

Formal description,compression and transformation of digital pictures

In an earlier paper (Part I) we described the construction of Hermite code for multiple grey-level pictures using the concepts of vector spaces over Galois Fields. In this paper a new algebra is worked out for Hermite codes to devise algorithms for various transformations such as translation, reflection, rotation, expansion and replication of the original picture. Also other operations such as concatenation, complementation, superposition, Jordan-sum and selective segmentation are considered. It is shown that the Hermite code of a picture is very powerful and serves as a mathematical signature of the picture. The Hermite code will have extensive applications in picture processing, pattern recognition and artificial intelligence.     

Generalizations of the Taut String Method

The taut string method is classically used in statistical applications to obtain a sparse estimation for a density given by point measurements. Mostly, a discrete formulation is employed that interpretes the data and the output as piecewise constant splines. This paper deals with the continuous formulation of this algorithm. We show that it is able to deal with continuous data as well as with discrete data interpreted as Dirac measures. In fact, any one-dimensional finite signed Radon measure is suited as input for the method. Moreover, we study the usage of tubes of nonconstant diameter. Examples indicate that such tubes can be useful in various applications. An existence and uniqueness theorem is given for the continuous formulation of the taut string algorithm with arbitrary tubes of nonnegative diameter.