共查询到20条相似文献，搜索用时 109 毫秒
1.
文中综述了微分方程模型在种群问题中的发展现状,总结了近些年来国内外一些知名学者在种群系统的边界控制方面的研究情况,为进一步深入研究种群系统的最优边界控制奠定了基础. 相似文献
2.
韩晓茹 《广东技术师范学院学报》2004,(4):14-18
本文研究了在一维有限区域上物体的凝固问题 .在这个问题中 ,我们需要确定固体的温度和它的两条自由边界的位置 .本文的结果包括两部分 :(1)证明了当边界固定时解的存在性 ;(2 )利用不动点定理证明了自由边界问题整体解的存在性 相似文献
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胡旭光 《数理天地(高中版)》2008,(10):7-8
解决非线性规划的问题,关键是理解非线性目标函数的几何意义,并利用图形及非线性目标函数的几何意义求出最优解及目标函数的最大值或最小值.本文归纳了"三类"线性规划 相似文献
4.
牛潇萌 《赤峰学院学报(自然科学版)》2014,(6):1-3
互补问题是一类重要的优化问题,它在工程、经济和交通平衡等领域都有重要应用.本文给出了非线性互补问题的光滑化拟牛顿算法,并给出证明此算法全局收敛性的几个重要定理. 相似文献
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本文所介绍的开关电源并联模块供电系统,解决了均流问题.调节输出电流的大小实际上就是调节DC-DC模块的输出电压,输出电压变化电流也就跟着变化,从而实现了电流的调节.要实现电流的分配就需要对三个点的电流进行采集.最后输出总电流.本电路采用差分输入运放,经过一系列的处理输出直接控制DC-DC的反馈端从而实现了电流的分配. 相似文献
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修正的Helmhotz方程柯西问题是一类典型的不适定问题,给数值处理带来了极大的困难.本文给出了边界加扰动的方法,恢复了解对数据的连续依赖性,并给出了误差估计.通过提高先验界的光滑性可以得到x=1时的收敛性. 相似文献
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本文讨论Dirichlet外问题的边界元法。给出了三维问题的一个数例以及它的一个特殊剖分。 相似文献
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求解非线性互补问题的一种方法是将其转化为非光滑方程组。本文通过引进一个基于Fischer-Burmeister函数的光滑NCP函数[8],建立了求解P0函数非线性互补问题的一个新的光滑牛顿算法。这个算法在每步迭代中只需要解一个光滑方程且不要求给出具体光滑因子下降的过程。在一定的条件下,证明了该算法的全局收敛性。数值试验表明该算法是有效的. 相似文献
9.
这篇文章我们考虑了非线性抛物型微分方程组问题在非局部边界条件的解的比较性原理,在对解假设存在的情况下,对完全非线性的抛物型方程组的非局部问题进行唯一性的探讨.本文主要应用了上下解的方法对一般的非线性抛物型微分方程组非局部问题进行了分析,并在满足一定的条件下得出了解的唯一性.在这篇文章中,我们建立了一类完全非局部边界问题非线性抛物型方程组的一般的比较的原理. 相似文献
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从“猜测和检验”看中美中学数学教育观之差异 总被引：1，自引：0，他引：1
猜测和检验是美国数学教科书中采用的一种问题解决策略,具有重要的数学教育价值,而我国数学教科书中使用这种策略进行问题解决的教学内容很少,由此看出中美教学教育观的差异,美国猜测和检验的问题解决策略值得我国数学教育借鉴。 相似文献
12.
Rafael Cortell 《浙江大学学报(A卷英文版)》2008,9(5):648-653
In this paper a numerical analysis is carried out to obtain the temperature distribution within a single fin. It is assumed that the heat transfer coefficient depends on the temperature. The complete highly non-linear problem is solved numerically and the variations of both, dimensionless surface temperature and dimensionless surface temperature gradient as well as heat transfer characteristics with the governing non-dimensional parameters of the problem are graphed and tabulated. 相似文献
13.
钱学明 《温州大学学报(社会科学版)》2014,(3):1-11
讨论了一类离散时间的时滞耦合神经网络的同步问题.在参教不确定的离散时间耦合神经网络中,考虑了变时滞和有限分布时滞.同时,细胞激活函数假设为较Lipschitz奈件更为一般的扇形非线性函数,该函数可以既不可微又不严格单调.通过构造Lyapunov-Krasovskii泛函,运用线性矩阵不等式(LMI)技术,并结合Kronecker积来获得耦合神经网络鲁棒全局指数同步的充分性判据,并且所获得的判据依赖于时滞.最后,对一个实例进行仿真,说明结论的有效性. 相似文献
14.
YANG Sheng-tian ZHAO Min-jian QIU Pei-liang 《浙江大学学报(A卷英文版)》2007,8(8):1263-1270
The Wyner-Ziv Problem for general sources with average distortion under fixed-length coding is investigated in this paper. To solve the problem,an enhanced covering lemma for a Markov chain is first established. Then based on the lemma,a general formula for the rate-distortion function of the problem is derived,where the distortion is only assumed uniformly bounded and may be nonadditive. Finally,it is further pointed out that such methods can be used to establish more general results on multiterminal source coding problems. 相似文献
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Various studies suggest that French students (grades 7 to 10) may solve geometric problems within a paradigmatic framework
that differs from that assumed by teachers, a situation prone to misunderstandings. In this paper, we study the extent to
which secondary school teachers recognise the conflicting paradigms and how they handle the geometric work conducted, in sometimes
unintended ways, by their students. This is done by analysing teachers’ reactions to specific answers students offered to
the Charlotte and Marie problem, an “ambiguous” problem with various solutions depending on the paradigm adopted. As a result
of the study, we found that, beyond similarities due to a shared mathematical background, the way secondary schoolteachers
handle students’ answers varies with their conceptions of geometric work. Implications are drawn regarding the teaching of
geometry and the training of teachers. 相似文献
17.
R. M. Garrett 《International Journal of Science Education》2013,35(2):125-137
In this paper the author explores the concept of problem‐solving as generally employed in the science education literature and suggests that a useful distinction can be drawn between puzzles, for which solutions are known or assumed to exist, and problems, for which no solution may be possible. The ability to recognize a problem, it is suggested, is possibly more important than its solution and this is dependent upon the experience, knowledge and interests of the individual. Successful encountering of problems and puzzles and the relationship of this activity to originality and creativity is also discussed. It is proposed that both puzzle and problem‐solving activities are important to provide in school science but that too little attention is paid to real problem‐solving with the result that the specific skills required are not practised. 相似文献
18.
角色规定了CSCL中学习者所承担的权限和任务,是CSCL研究关注的核心要素。本研究将角色引入问题解决协作学习中,从协作任务和问题解决认知加工两个维度构建了角色设计框架。研究将角色设计框架应用于具体问题解决协作学习中,部分验证了框架包含角色的有效性。研究结论认为,问题解决协作学习活动所采用的三类角色能够增强学习者在线问题解决学习的效果,并提升学习者对学习的主观感知。 相似文献
19.
Whether fading support for problems affects accuracy of hypertext navigation and problem performance is investigated in this study. In a student-centered e-learning environment conceptual support is added to help domain novices get an overview of the problem domain, while strategic support is provided to help domain novices get insight into the problem demands. It is assumed that such support helps learners because it lowers the cognitive load of navigation. This frees up cognitive capacity for learning provided that the support fades and becomes less intrusive as a function of learner expertise. It is hypothesized that fading support during practice helps learners navigate more accurately during practice and achieve a higher practice and test performance as compared to learners receiving full support or no support during practice. This study confirms the beneficial effects of fading support on navigation but no effects of fading were found on practice and test performance. 相似文献
20.
Parallel machine scheduling problems, which are important discrete optimization problems, may occur in many applications. For example, load balancing in network communication channel assignment, parallel processing in large-size computing, task arrangement in flexible manufacturing systems, etc., are multiprocessor scheduling problem. In the traditional parallel machine scheduling problems, it is assumed that the problems are considered in offline or online environment. But in practice, problems are often not really offline or online but somehow in-between. This means that, with respect to the online problem, some further information about the tasks is available, which allows the improvement of the performance of the best possible algorithms. Problems of this class are called semi-online ones. In this paper, the semi-online problem P2|decr|lp (p＞1) is considered where jobs come in non-increasing order of their processing times and the objective is to minimize the sum of the lp norm of every machine's load. It is shown that LS algorithm is optimal for any lp norm, which extends the results known in the literature. Furthermore, randomized lower bounds for the problems P2|online|lp and P2|decr|lp are presented. 相似文献