BP神经网络训练算法的分析与比较

BP神经网络被广泛应用于模式识别、信号处理和自动控制等领域,其广泛性是由于它能实现任何连续映射,但由于BP网络训练所固有的复杂性,目前尚没有任何一种完全的算法能适用于任何BP网络的训练。本文介绍了MATLAB神经网络工具箱中各种训练算法的特点及其函数的参数形式,并对它们的收敛速度和内存消耗情况进行了比较,说明了其各自适用的网络。     

Do children with mathematics learning disability in Hong Kong perceive word problems differently?

The current study aimed at identifying the difficulties experienced by children with mathematics learning disability (MLD) in the problem representation phase of arithmetic word problem solving using a novel problem types identification task. An MLD group (n = 66) and a typically achieving control group (n = 139) were recruited for an assessment on problem type identification as well as some domain-general and mathematics-related cognitive abilities. Results from ANCOVA showed that the MLD group scored significantly lower than the typically achieving control group on this assessment, after controlling for the effect of cognitive correlates, reading achievement and arithmetic performance. Furthermore, this assessment significantly predicted MLD membership even after taking children's arithmetic competency into account. The current study confirmed the difficulties in problem representation of arithmetic word problems experienced by students with MLD and provided evidence for the need to introduce schema instructions in mathematics classes.     

代数学发展中的运算

本文考虑运算在代数学发展的各个阶段的情况,从算术运算到初等代数运算,再到高等代数运算,再到一般的代数运算,对代数学的运算作了比较详细的介绍分析．     

基于可进化硬件的FIR数字滤波器设计

本文介绍了可进化硬件的机理和相关技术,阐述了一种基于进化论中遗传算法的大规模电子电路设计方法,用可进化硬件设计出了有限冲击响应数字滤波FIR系统,利用VHDL语言在QUARTUSII对设计进行仿真,得到了较好的效果关键词:遗传算法;可进化硬件;FIR;EHW;FPGA;VHDL     

Spontaneous focusing on numerosity and the arithmetic advantage

Children show individual differences in their tendency to focus on the numerical aspects of their environment. These individual differences in ‘Spontaneous Focusing on Numerosity’ (SFON) have been shown to predict both current numerical skills and later mathematics success. Here we investigated possible factors which may explain the positive relationship between SFON and symbolic number development. Children aged 4–5 years (N = 130) completed a battery of tasks designed to assess SFON and a range of mathematical skills. Results showed that SFON was positively associated with children's symbolic numerical processing skills and their performance on a standardised test of arithmetic. Hierarchical regression analyses demonstrated that the relationship between SFON and symbolic mathematics achievement can be explained, in part, by individual differences in children's nonsymbolic numerical processing skills and their ability to map between nonsymbolic and symbolic representations of number.     

提高自学考试答题卡识别准确率的探讨及实践

自学考试的客观题机器阅卷因容易受到内外各方面因素的影响而会产生一定概率的误判。为了更好地维护自学考试作为国家考试的公平和公正性,需要分析可能存在的误判原因。本文描述了如何使用数字图像识别技术来提高答题卡的识别准确率,最大程度地降低识别误判率,以提高客观题的阅卷质量。     

在Direct 3D程序中运用碰撞检测

本文分析了三维场景中的物体之间的碰撞和干涉的原因,提出了一个针对物体与场景之间的碰撞检测的算法,并阐述了它的原理及其如何具体实现,为编写程序代码做了充分准备。     

分形插值曲线的MATLAB实现

自然界中存在的许多现象具有分形特征,传统的Euclid 空间对具有分形特征的自然界形态仿真具有一定困难.对此可以用分形插值来拟合自然界形态.分形插值函数是由迭代函数系统(IFS)实现的.通过离散的数据点构成分形插值函数,可以证明分形插值函数是这个IFS唯一的吸引子.利用MATLAB矩阵运算与图形绘制功能,实现离散数据点的分形插值拟合.试验结果表明.该算法具有简捷直观的特点.     

A comparison of updating processes in children good or poor in arithmetic word problem-solving

This study examines the updating ability of poor or good problem solvers. Seventy-eight fourth-graders, 43 good and 35 poor arithmetic word problem-solvers, performed the Updating Test used in Palladino et al. [Palladino, P., Cornoldi, C., De Beni, R., and Pazzaglia F. (2002). Working memory and updating processes in reading comprehension. Memory and Cognition, 29, 344–354.]. The participants listened to wordlists, each comprising 12 words referring to objects or animals of different sizes. At the end of each list participants were asked to recall the 3 or 5 words denoting the smallest objects/animals in the list. Results show that poor problem-solvers recalled fewer correct words and made more intrusion errors (recall of non-target words) than good problem-solvers. Results support the hypothesis that the ability to select and update relevant, and suppress irrelevant information, is related to problem-solving, even when the influence of reading comprehension is controlled for. With reference to Baddeley's, and other recent WM models [Miyake, A., and Shah, P. (Eds.), (1999). Models of working memory: Mechanisms of active maintenance and executive control. New York: Cambridge University Press.], our results point to the idea that problem-solving relies on the central executive for processing and updating information contained in the problems.     

Facilitating preservice teachers’ development of mathematics knowledge for teaching arithmetic operations

Mathematical tasks, centered on arithmetic word problems, are discussed as the basis of an approach to facilitate preservice elementary teachers’ development of mathematical knowledge for teaching arithmetic operations. The approach consists of three groups of tasks that allow students to reflect on their initial knowledge, explore arithmetic word problem situations from multiple perspectives, and apply their resulting knowledge, respectively. Findings from the investigation of the approach indicate that the tasks can provide an effective and meaningful basis to help preservice teachers to develop deeper understandings of the arithmetic operations and their relationships and pedagogical-mathematical knowledge for teaching the arithmetic operations conceptually.