计算机教学方法的探讨

第三次科技革命是人类文明史上继蒸汽技术革命和电力技术革命之后科技领域里的又一次重大飞跃。它以原子能、电子计算机和空间技术的广泛应用为主要标志,涉及信息技术、新能源技术、新材料技术、生物技术、空间技术和海洋技术等诸多领域的一场信息控制技术革命。这次科技革命不仅极大地推动了人类社会经济、政治、文化领域的变革,而且也影响了人类生活方式和思维方式,使人类社会生活和人的现代化向更高境界发展。正是从这个意义上讲,第三次科技革命是迄今为止人类历史上规模最大、影响最为深远的一次科技革命,是人类文明史上不容忽视的一个重大事件。[1]21世纪是个计算机与通讯不断完善的阶段。计算机作为一门大学的基础课程,应当承担它应当担负的历史使命。如何进行计算机这门学科的建设就成为一个必要的、重要的议题。笔者都是大学的教师。由于亲自在第一线进行计算机教学工作,得到一些心得体会,这里与大家共同分享和讨论。     

基于欧姆龙PLC设备的故障诊断解析方法

本文针对PLC控制的电动机在正反转时发生故障,通过观察故障现象和分析其故障原因,提出设定故障检查次序,综合利用假设验证法、替换法、对比法和测量法等故障诊断方法,排除设备的故障,通过实践证明合理设定故障检查次序对设备故障排除的重要性.     

A comparative analysis of algorithms for fast computation of Zernike moments

This paper details a comparative analysis on time taken by the present and proposed methods to compute the Zernike moments, Z_pq. The present method comprises of Direct, Belkasim's, Prata's, Kintner's and Coefficient methods. We propose a new technique, denoted as q-recursive method, specifically for fast computation of Zernike moments. It uses radial polynomials of fixed order p with a varying index q to compute Zernike moments. Fast computation is achieved because it uses polynomials of higher index q to derive the polynomials of lower index q and it does not use any factorial terms. Individual order of moments can be calculated independently without employing lower- or higher-order moments. This is especially useful in cases where only selected orders of Zernike moments are needed as pattern features. The performance of the present and proposed methods are experimentally analyzed by calculating Zernike moments of orders 0 to p and specific order p using binary and grayscale images. In both the cases, the q-recursive method takes the shortest time to compute Zernike moments.     

On the generalisation of the basic iterative methods for the solution of linear systems

For the solution of the linear system Ax=b many iterative methods based on a splitting of A exist. Among them the Jacobi, the Gauss-Seidel and the Successive Overrelaxation (SOR) methods as well as their extrapolated counterparts are the most popular. This paper presents a new general method such that the aforementioned methods become special cases of it. Besides its four degrees of freedom, which make it a very flexible method, another of its main characteristics is that it is well-defined even when some elements on the diagonal of A are zero. The first results concerning the new method show that a proper exploitation of its basic properties will make it a very powerful technique.     

Implementation of parallel three-point block codes for solving large systems of ordinary differential equations

The three-point fully implicit block methods are developed for solving large systems of ordinary differential equations using variable step size on a parallel shared memory computer. The methods calculate the numerical solution at three points simultaneously and are suitable for parallelization across the method. The methods are in a simple form as Adams Moulton method with the specific aim of gaining efficiency. For large problems, the parallel implementation produced a good speed-up with respect to the sequential timing and hence better efficiency for the methods developed.     

一种求解鞍点问题的广义预条件对称一反对称分裂迭代法

鞍点问题的来源和应用都很广泛，如计算流体力学，约束最优化，约束加权最小二乘问题等。寻求快速有效地求解这类问题的算法具有很重要的现实意义．在白中治，Golub和潘建瑜提出的预条件对称／反对称分裂迭代法（PHSS）的基础上，通过引入新的待定参数对原有迭代算法进行加速的思想，本文提出了一种解鞍点问题的具有两个待定参数的广义预条件对称／反对称分裂迭代法（GPHSS），并给出了该算法收敛性的条件．数值例子表明：通过最优参数值的选择，新算法比PHSS算法具有更快的收敛速度和更小的迭代次数，选择了最优参数值后，可以提高算法的收敛效率．     

冗余度机械手的一种新的控制方法

本文以冗余度机械手为研究对象,在梯度投影法和变量约束法的基础上给出了一种新的控制方法,即混合法.并利用该方法以平面三自由度机械手为例进行了仿真.     

从明暗恢复形状（SFS）的几类典型算法分析与评价

从明暗恢复形状（shape from shading,简称SFS）是计算机视觉中三维形状恢复问题的关键技术之一,其任务是利用单幅图象中物体表面的明暗变化来恢复其表面三维形状。为了使人们对SFC研究现状及求解SFS问题的各种算法的优缺点有个概略了解,首先介绍了求解传统SFS问题的4类方法中几个典型算法的基本原理及求解方法,并给出了实验结果,然后从算法解的唯一性、对真解的逼近程度、求解效率及适用范围等方面对这4类算法进行了比较和评价。     

极大熵条件下的动态搜索优化图象重建方法

提出一种满足多种准则的动态搜索优化图象重建方法。从图象场的本质出发，设立了３个准则函数。熵函数的导数是非线性的，本文将其变换为近似的线性公式以获得迭代公路。动态搜索则尽可能避免很多算法在迭代过程中对图象校正过量或不足的问题。     

wMPS测量原理算法及优化

wMPS测量基本原理算法适用于两台wMPS基站测量,存在精度低、稳定性差的问题。为了满足工业现场应用需求,提高wMPS的测量精度和wMPS系统在工业应用中的可靠性、稳定性,需要采用多发射站测量。通过数学分析,采用矢量法与最小二乘法相结合的方法,实现了多发射站同时测量某一待测点坐标的求解算法。该算法将矢量法应用在多个发射站测某一待测点算法中,从而提高测量精度及稳定性等,同时避免了原始算法中先求解水平角和垂直角,再根据两个发射站之间的距离进行待测点坐标解算,降低了运算量。     

Combinations of collocation and finite-element methods for Poisson''s equation

In this paper, we provide a framework of combinations of collocation method (CM) with the finite-element method (FEM). The key idea is to link the Galerkin method to the least squares method which is then approximated by integration approximation, and led to the CM. The new important uniformly V⁰_h-elliptic inequality is proved. Interestingly, the integration approximation plays a role only in satisfying the uniformly V⁰_h-elliptic inequality. For the combinations of the finite-element and collocation methods (FEM-CM), the optimal convergence rates can be achieved. The advantage of the CM is to formulate easily linear algebraic equations, where the associated matrices are positive definite but nonsymmetric. We may also solve the algebraic equations of FEM and the collocation equations directly by the least squares method, thus, to greatly improve numerical stability. Numerical experiments are also carried for Poisson's problem to support the analysis. Note that the analysis in this paper is distinct from the existing literature, and it covers a large class of the CM using various admissible functions, such as the radial basis functions, the Sinc functions, etc.     

Finite element analysis of nonlocal coupled parabolic problem using Newton’s method

In this article, we propose finite element method to approximate the solution of a coupled nonlocal parabolic system. An important issue in the numerical solution of nonlocal problems while using the Newton’s method is related to its structure. Indeed, unlike the local case the Jacobian matrix is sparse and banded, the nonlocal term makes the Jacobian matrix dense. As a consequence computations consume more time and space in contrast to local problems. To overcome this difficulty we reformulate the discrete problem and then apply the Newton’s method. We discuss the well-posedness of the weak formulation at continuous as well as at discrete levels. We derive a priori error estimates for both semi-discrete and fully-discrete formulations. Results based on usual finite element method are provided to confirm the theoretical estimates.     

High-Order Mixed Current Basis Functions for Electromagnetic Scattering of Curved Surfaces

We construct high-order mixed current vector basis (unctions on an arbitrary curved surface which can be subdivided as a union of curved triangles and quadrilaterals. The objective is to construct vector basis (a) which consists of high-order polynomials of the surface parameterization variables on triangles and quadrilaterals, (b) part of the basis will have vanishing moments on the triangles and quadrilaterals. The first property will enable us to represent the current distribution over scatter surface with much less number of unknowns and larger patches of either triangular or quadrilateral shapes. The second property will achieve what wavelet basis does on an interval, but on a more general domain, namely, a sparse matrix representation for some integral operators.     

Comparison between Newton and response-surface methods

A supporting-point placement scheme is presented that is used for calculating function derivatives by the method of differences as well as a quadratic response-surface approximation. The placement scheme unifies the Newton (NM) and response-surface (RSM) methods in the limiting case when the point-set distance parameter for the RSM is chosen as small as that for obtaining the derivatives needed by the NM. Two new RSM minimization strategies with and without line searches are presented. The numerical performance of the algorithms is studied by using well-known test functions and the paths through the two-dimensional variables space are plotted for easier interpretation of the performance results. The results are compared with results of numerical experiments found in the literature.     

Reliable algorithms for solving integro-differential equations with applications

This paper suggests four different methods to solve nonlinear integro-differential equations, namely, He's variational iteration method, Adomian decomposition method, He's homotopy perturbation method and differential transform method. To assess the accuracy of each method, a test example with known exact solution is used. The study outlines significant features of these methods as well as sheds some light on advantages of one method over the other. The results show that these methods are very efficient, convenient and can be adapted to fit a larger class of problems. The comparison reveals that, although the numerical results of these methods are similar, He's homotopy perturbation method is the easiest, the most efficient and convenient. Moreover, we applied modified forms of He's variational iteration method and differential transform method to solve a mathematical model, which describes the accumulated effect of toxins on populations living in a closed system.     

高职服装设计与工艺专业运用项目教学法的实践体会

项目教学法以提升高职学生的职业发展能力为目标,着力探索学生全面发展的新思路、新途径。项目教学法有利于培养学生关键能力,有利于提高教育效率,有利于深化课程改革,有效地建立了课堂与社会生活的联系,充分展示了现代职业教育"以能力为本"的价值方向。     

基于Web的网络旅游服务系统的形式化B开发

形式化B方法支持从规格说明到代码生成的全部软件开发过程。结合网络旅游服务系统模型，讨论了形式化B方法的具体运用，在分析服务器端和客户端状态表示的基础上，给出了该系统的抽象机模型及其精化过程。     

Cloud screening in IRS-P4 OCM satellite data: potential of spatial coherence method in the absence of thermal channel information

Cloud screening of satellite data for the remote sensing of atmospheric aerosols, ocean sediments, chlorophyll, and phytoplankton in the marine environment is a major problem in the absence of information from thermal channel. This is particularly the case with the data from some of the highly potential satellite sensors such as the Ocean Colour Monitor (OCM—on board the Indian Remote Sensing Satellite, IRS-P4) and the SeaWiFS. Two main tests conventionally used for cloud screening of data from such satellite sensors are the threshold method applied to visible and near-IR bands and the visible to near-IR channel ratio method. These methods do not have the potential to eliminate the pixels with small cloud fractions, leading to overestimation of the aerosol optical depth (AOD) derived from satellite data, and might also identify the pixels with high values of AOD as cloudy. The purpose of this paper is to study the potential of Spatial Coherence Test (SCT) applied to the data from the near-IR bands for cloud screening of satellite data over the oceanic environment. We use here the data from IRS-P4 OCM. Though more computationally intensive, the SCT does not suffer from the serious limitations of the threshold and channel ratio methods and is found to be superior in identifying the clear sky pixels that are not affected by clouds. Although the SCT applied to near-IR channel data may be overestimating the number of cloud affected pixels, it neither leads to overestimation of AOD nor identifies the pixels with high AOD values as cloudy.     

基于任意多边形拉氏网格的有限体积方法研究及应用

本文提出了结构与非结构拉氏网格联合使用的网格策略,采用了邻域关系、线性表和指针的数据结构,研制并实现了基于任意多边形拉氏网格的有限体积方法及程序．数值实验显示了其很强的模拟实力．     

煤矿巷道围岩松动圈测试方法探讨

介绍了目前测试巷道围岩松动圈的不同方法及其测试原理,讨论和分析了不同测试方法的优缺点及适用范围。通过对比可以看出,声波测试法技术成熟、方法简单,但在软岩层中很难适用;多点位移计和多点应力计法可以实时监测巷道围岩的位移或应力变化,但其测试精度有限;地震波法测试精度高,但设备昂贵且安装复杂;地质雷达法不需钻孔,是一种无损测试方法,但测试成本较高;电阻率法对仪器测量精度要求较高,且对电极布置也有较高的技术要求;钻孔摄像法的图像清晰度受限于钻孔内恶劣的环境条件及摄像头的像素。因此,每一种测试方法都有其局限性,实际应用时应充分考虑巷道围岩的性质,选用适宜的方法以便准确测定巷道松动圈大小。