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思维导图是盛行于国外特别是欧美国家的一种教学形式。人们把思维导图应用到学习和工作中,大大的提高了学习和工作的效率。随着建构主义学习理论的发展和数字化学习的普及,思维导图的应用更加广泛,让更多的人去认识它们、使用它们更有意义。在信息技术教学中应用思维导图可以改变传统的教学模式,是一种有效的思维工具。 相似文献
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由于现行网络并没有提供标准化的机制来描述复合信息对象边界问题,当它们映射到Web图上,复合对象/组件之间的关系特征会消失,OAI-ORE试图用"命名图"机制来解决这个问题。本文主要介绍OAI-ORE的抽象数据模型,同时对OAI-ORE在数字图书馆的应用进行展望。 相似文献
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魏二玲 《中国科学院研究生院学报》2004,21(4):451-453
20世纪 70年代 ,刘彦佩通过构造图的辅助图 ,得到判定图是否平面的充分必要条件 .图的标号三元图刻画了图的内在结构 ,也可以刻画图是否平面 .证明了图的辅助图是否平衡以及标号三元图是否平衡是等价的 ;并进一步指出 ,用辅助图来判定要优于用标号三元图 . 相似文献
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在现代化的测绘工程当中,采用相关的应用软件来对成图的质量进行控制已经得到了比较好的应用和普及,但是在实际的测绘工作当中,对于内业成图的一些要点和技巧还是不能够忽视。而本文主要就结合了实际经验来对测绘内业成图的要点和技巧进行了一定的分析。 相似文献
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随着信息技术的快速发展,数控机床的功能结构越来越复杂,维修难度加大,这就要求加强实训教学,但实际数控维修教学中常会因设备不足不能满足每一个学生的要求,给数控维修教学带来了挑战。虚拟数控机床的出现,一定程度上满足了数控维修教学中学生的实际需求,运用到数控维修教学中,不仅能提高学生的数控操作水平,还能提高教学效果。那么,数控维修教学中如何运用虚拟数控机床,培养出合格的数控维修人才呢？本文主要结合自身教学实践,从虚拟数控机床概述入手,分析数控维修教学中存在的问题,探讨虚拟数控机床在数控维修教学中的运用。 相似文献
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According to the mathematical classification of topological band structures, there exist a number of fascinating topological states in dimensions larger than three with exotic boundary phenomena and interesting topological responses. While these topological states are not accessible in condensed matter systems, recent works have shown that synthetic systems, such as photonic crystals or electric circuits, can realize higher-dimensional band structures. Here, we argue that, because of its symmetry properties, the 4D spinless topological insulator is particularly well suited for implementation in these synthetic systems. We explicitly construct a 2D electric circuit lattice, whose resonance frequency spectrum simulates the 4D spinless topological insulator. We perform detailed numerical calculations of the circuit lattice and show that the resonance frequency spectrum exhibits pairs of 3D Weyl boundary states, a hallmark of the nontrivial topology. These pairs of 3D Weyl states with the same chirality are protected by classical time-reversal symmetry that squares to +1, which is inherent in the proposed circuit lattice. We also discuss how the simulated 4D topological band structure can be observed in experiments. 相似文献
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JingYipeng GerhardBorner 《中国科学院院刊(英文版)》2004,18(2):58-59
The Partner Group does research in cosmology, focussing on the quantitative modeling of the structure and evolution of galaxies and galaxy clusters, the pattern of galaxies and of larger structures. The usual approach in this field is the dark matter paradigm, i.e. the assumption that the basic structures are laid out in a matter component of particles which interact only gravitationally. Numerical simulations of large scale and high resolution are used to follow the evolution of condensations of dark matter particles during cosmological evolution. Analytic models and detailed statistical investigations of astronomical data sets supplement the numerical work. 相似文献
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运用M-P广义逆理论,研究了桁架结构的非线性homologous设计问题。将homologous变形约束条件引入结构基本方程,运用M-P广义逆矩阵的性质,将基本方程解的存在条件表示为含可变节点坐标变量的非线性方程组,通过求解该非线性方程组找到了满足homologous变形约束要求的解,并为此推导了AA (A为任意矩阵,A 为A的M-P广义逆矩阵)求偏导数的显式表达。最后的算例验证了本方法的正确性和有效性。 相似文献
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数值分析课程教学的改革迫在眉睫,本文分析了数值分析课程教学的特点和在教学中的不足,结合自己在该课程的具体教学实践中的体会,对该课程的教学方法和教学手段提出了几点意见。 相似文献
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M.M. Mortula 《Journal of The Franklin Institute》2011,348(7):1627-1637
An innovative hydraulic structure was proposed for passage of fish in surface water. The structure consisted of identical ‘cells’ throughout its length and was designed to create coupled spatially varied flow for optimization of depth and velocity of water. The objective of this paper was to simulate the hydraulics of a single cell of this fish passage structure. A numerical model was developed to simulate the water surface profiles and longitudinal variation of 1-D velocity through one cell. The transition in the water surface profile between longitudinally adjacent cells (chamber) was also investigated. It was found that numerical convergence was usually achieved after three iterations with 2% discretization. The difference in depth arising from cell vs. chamber analysis was found to be small. The experimental results indicated turbulence in the water surface. The water surface profile matched the results obtained from numerical results. However, there were errors observed in estimation of flow rate. It is concluded that the mathematical approach used for the numerical simulation is reliable and can be used to analyze coupled spatially varied flow for any hydraulic structures aimed at controlling depth and velocity of water. Innovative approach to the interface between can potentially be used to achieve hydraulic goal of any structure. 相似文献
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本文采用交错排列和反对称排列共同组合的离散涡模型模拟圆柱湍流远尾迹区的平均流场,应用局部化自诱导近似处理旋涡的自诱导运动,通过数值方法研究尾迹区中无穷长直线涡受到初始小扰动后的三维演化,所得结果有助于说明湍流尾迹中的相干涡结构. 相似文献
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以一个零部件供应商和一个成品制造商组成的两层供应链系统为研究对象,通过引入参与决策主体的竞争性公平关切行为倾向,分析了在考虑决策者公平关切偏好时供应链最优的产品质量与市场零售定价策略.在供应链参与双方均具有公平关切偏好的框架下,分别就Nash博弈、供应商Stackelberg、制造商Stackelberg和纵向一体化四种博弈结构建立了产品质量水平和零售定价的博弈决策模型,讨论了公平关切和供应链博弈结构对产品质量与零售定价优化决策的影响;并结合数值算例探讨了决策者的公平关切程度对其运作效用和利润的影响. 相似文献
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海啸灾害的数值模拟研究 总被引：4，自引：0，他引：4
海啸的数值模拟研究在帮助理解海啸自然灾害的物理特性及预防减灾方面具有重要意义．总结了当前海啸数值模拟的常用方法,包括对它们物理特性的描述,物理过程的划分,不同过程所采用的控制方程,常用的数值模拟方法,及模拟的重点和难点．在此基础上,介绍了当 前国际上有影响力的一些海啸数值模型,及其实现方法与特点,对于研究者开展自己的研究具有借鉴意义． 相似文献
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《Journal of The Franklin Institute》2001,338(2-3):241-254
Building structures represent complex distributed-parameter systems. The motion of such systems is described by partial differential equations complemented by suitable boundary conditions. For control design purposes, distributed-parameter systems must be discretized in the spatial variables. But, if the discrete model is not sufficiently accurate, controls designed on the basis of the discrete model can destabilize the actual distributed structure, in which case the controls are said to be sensitive to discretization errors. This paper presents a new approach to the discretization of distributed structures yielding accurate discrete models of relatively low order. A numerical example illustrates how controls can be designed for a complex structure subjected to earthquake excitations. 相似文献