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有限元方法 总被引:1,自引:0,他引:1
冯康 《数学的实践与认识》1974,(4)
有限元方法是在生产实践基础上发展起来的,用于解椭圆型方程问题的一类数值方法,特别适合于几何上、物理上比较复杂的问题.在弹性力学领域内已经广泛应用,成效显著.由于方法是高度通用的,对于其它领域的应用发展前景亦是很宽广的.本文将对这个方法的要点作一初步介绍. 相似文献
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1引 言
单位球面上的插值问题一直是三元插值问题中比较受关注的部分.近年来,球面上的 Lagrange插值问题已经得到了很好地解决.例如[1]中给出了构造单位球面上的Lagrange 插值适定结点组的一种方法:添加圆周法.[2]和[3]中研究了单位球面上的多项式插值问题,给出了构造单位球面上的插值适定结点组的另外两种方法. 相似文献
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表矩阵为初等阵之积的问题,是矩阵论中基本问题之一.一些矩阵方法能够具体操作也是赖于此问题的结论,但是一般环上,此问题尚无结果.本文对局部环,探讨此问题的解决. 相似文献
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用乘法半群上的线性方程组来求解晶体原子间对势反演的逆问题.这种方法是解决此类问题的一般性方法.本文还给出了一个计算实例. 相似文献
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求平面上动点的轨迹方程问题,是解析几何要解决的两大问题之一,也是高考考察的重点和学生学习解析几何时的一个难点.由于给出平面上动点的条件往往各异,因此求其相应轨迹方程的方法也不尽相同.本文将结合实例,谈谈在不同条件下求轨迹方程的几种常方法. 相似文献
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Boping Jin 《Journal of Number Theory》2005,110(1):120-135
A subgroup cover of the integer lattice in two or more dimensions is a presentation of that lattice as a finite union of proper subgroups, no two of the same index. In an earlier paper, Cochrane and Myerson constructed subgroup covers in two dimensions and asked several questions about other methods of construction and about higher dimensions. We answer those questions. 相似文献
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In problem structuring methods, facilitators often ask of themselves questions such as: what makes a ‘good’ problem structuring group (PSG) and indeed what does ‘good’ mean? How can group dynamics be improved and does it matter in terms of the quality of the problem structuring that that group engages in? On the surface these questions seem to be straightforward. Indeed, those who have helped facilitate many participatory workshops will think they intuitively know the answers to these questions; they can, from their professional practice, ‘feel’ which PSGs are doing well and producing novel insights and those which are functioning less well and perhaps generating something that is less imaginative and more routine as a consequence. The intuitive, practice-learned insight will depend upon a rich array of visual signals that become more obvious with experience. This paper asks whether there is value in being much more open and analytical about these questions and answers. If so, then how can we make the unwritten processes and outcomes of PSGs written? Indeed, open to whom? Finally, how much of any insights learned by facilitators should be shared with those engaged in workshops? 相似文献
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Jin-Chang Wang 《International Journal of Approximate Reasoning》1994,10(4):287-309
In many applications of knowledge-based systems, initial facts are insufficient to lead to any conclusion, and the systems need to ask users to provide more information. A question-asking strategy decides the questions to ask and their sequence. We present a question-asking strategy for Horn clause knowledge bases under uncertainties. The strategy selects questions quickly by considering both conclusion certainties and costs of reaching conclusions. The experiments on randomly generated knowledge bases show that the proposed strategy is significantly better than the contingent strategies being used with forward-chaining or backward-chaining procedures. 相似文献
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本篇首次将关于半鞅的随机微分方程的解过程引入平稳型脉冲控制的状态结构, 建立了一种新的模型,从而实质性地推广了此前的各类平稳型脉冲随机控制模型.本篇 通过新的分析手法证明了与新模型相关的变分方程解的存在性,这种新方法比以前类似 问题的分析方法更直接、更明快. 相似文献
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一类与半鞅有关的推广型脉冲控制(I) 总被引:2,自引:0,他引:2
本篇首次将关于半鞅的随机微分方程的解过程引入平稳型脉冲控制的状态结构,建立了一种新的模型,从而实质性地推广了此前的各类平稳型脉冲随机控制模型.本篇通过新的分析手法证明了与新模型相关的变分方程解的存在性,这种新方法比以前类似问题的分析方法更直接、更明快. 相似文献
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Mark Wildon 《Discrete Mathematics》2010,310(21):2974-2983
This paper solves the Knights and Spies Problem: In a room there are n people, each labelled with a unique number between 1 and n. A person may either be a knight or a spy. Knights always tell the truth, while spies may lie or tell the truth as they see fit. Each person in the room knows the identity of everyone else. Apart from this, all that is known is that strictly more knights than spies are present. Asking only questions of the form: ‘Person i, what is the identity of person j?’, what is the least number of questions that will guarantee to find the true identities of all n people? We present a questioning strategy that uses slightly less than 3n/2 questions, and prove that it is optimal by solving a related two-player game. The performance of this strategy is analysed using methods from the famous ballot-counting problem. We end by discussing two questions suggested by generalisations of the original problem. 相似文献
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Patterson P 《OR manager》1990,6(8):14-15
Rising costs and a new emphasis on outcomes are stimulating closer scrutiny of traditional OR practices such as draping. What is truly necessary? What is proven? What makes sense? This is the second of a two-part article on draping. In the July issue, we examined draping for clean-contaminated procedures, total body draping, and adherent drapes. In this issue, we tackle three more draping questions. 相似文献
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Markus Hähkiöniemi 《International Journal of Mathematical Education in Science & Technology》2017,48(7):973-987
Previous studies have produced several typologies of teacher questions in mathematics. Probing questions that ask students to explain are often included in the types of questions. However, only rare studies have created subtypes for probing questions or investigated how questioning differs depending on whether technology is used or not. The aims of this study are to elaborate on different ways of asking students to give explanations in inquiry-based mathematics teaching and to investigate whether questioning in GeoGebra lessons differs from questioning in other lessons. Data was collected by video recording 29 Finnish mathematics student teachers’ lessons in secondary and upper secondary schools. The lesson videos were coded for the student teachers’ probing questions. After this, categories for the types of probing questions were created, which is elaborated in this paper. It was found that the student teachers who used GeoGebra emphasized conceptual probing questions during the explore phase of a lesson slightly more than the other student teachers. 相似文献
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本把Botsko于1986年首先提出的关于多元函数f(x)于点x^#取极小值的一阶充分条件加以改进,并推广到具有等式约束的情形。得到的若干成果将为解决经济优化问题提供方便。 相似文献