共查询到20条相似文献，搜索用时 171 毫秒
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《西安文理学院学报》2020,(3)
针对刚柔耦合多体系统动力学模型数值求解的相关问题进行分析与探讨,为解决当前刚性常微分方程组求解中存在的高频振荡以及计算量大问题.尝试对显式Runge-Kutta法进行改进,应用Gill法对动力学微分方程组进行求解,并通过应用实例证实:基于改进的Gill法在应用于刚柔耦合多体系统动力学模型数值求解的过程中截断误差小,且积分速度快,计算量小,能够给后续算法改进优化提供重要依据. 相似文献
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本文用准直线性理论,从负阻观点出发提出了一种,对晶体管 LC 自激振荡器振荡条件的分析具有普遍意义的简捷的分析方法。并把常用的三种 LC 振荡器的振荡条件表示式统一为一个公式,便于理论分析和工程计算。 相似文献
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(本讲适合高中) 涉及整数的问题,既形式简单又意义明确,虽所用知识不多但却富于技巧性,因而在数学竞赛中备受青睐。求解此类问题的一个关键即为选用整数的适当表示方法。本文以整数的表示方法为主线和工具,结合一些典型例题的分析,介绍数学竞赛中整数问题的 相似文献
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随着船舶工业的不断发展,人们对船舶尤其是高速船舶的兴波阻力越来越关注。而船舶与海洋工程专业船舶阻力课程中目前对兴波阻力的介绍偏于简略。本文针对这一现状,对船舶阻力课程中增加兴波阻力的新内容提出了一点建议。 相似文献
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顾永跟 《湖州师范学院学报》1999,(5)
讨论了棋盘和棋盘多项式,及其在图论中的对应表示方法;用棋盘的形式表示和解决图论中关于对集的结论和方法,把完美对集和最大对集求法归结为棋盘多项式的求解问题;详细讨论了棋盘多项式的求解算法,并给出一种用棋盘多项式求完美对集的算法. 相似文献
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本文中,在假设矩阵A的奇异值大于1的条件下,给出了求解绝对值方程的一个新的光滑化梯度型算法.通过引入极大熵函数对绝对值方程进行光滑化处理,得到一个非线性光滑方程组,再引入适当的目标函数,把绝对值方程转化为无约束优化问题,进而利用共轭梯度算法对其求解,从而获得原问题的解.数值实验表明了新方法的有效性. 相似文献
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In this paper, on the basis of the variational principles developed the finite element method (FEM) is employed for numerical solution of the inverse problem of 2-D unsteady compressible flow around oscillating airfoils by incorporating the non-reflecting far-field boundary conditions and a new unsteady Kutta condition. All unknown boundary (airfoil contour) and discontinuities(shocks and free trailing vortex sheets) are determined via the functional variation with variable domain and artificial density concept. For the numerical realization of the variable-domain variation, a special finite element with self-adjusting nodes is also suggested herein. The numerical results show that the present method is effective for the design of unsteady airfoil. 相似文献
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Cognitive load and mental rotation: structuring orthographic projection for learning and problem solving 总被引：1，自引：0，他引：1
Hitendra K. Pillay 《Instructional Science》1994,22(2):91-113
Cognitive load theory was used to generate a series of three experiments to investigate the effects of various worked example formats on learning orthographic projection. Experiments 1 and 2 investigated the benefits of presenting problems, conventional worked examples incorporating the final 2-D and 3-D representations only, and modified worked examples with several intermediate stages of rotation between the 2-D and 3-D representations. Modified worked examples proved superior to conventional worked examples without intermediate stages while conventional worked examples were, in turn, superior to problems. Experiment 3 investigated the consequences of varying the number and location of intermediate stages in the rotation trajectory and found three stages to be superior to one. A single intermediate stage was superior when nearer the 2-D than the 3-D end of the trajectory. It was concluded that (a) orthographic projection is learned best using worked examples with several intermediate stages and that (b) a linear relation between angle of rotation and problem difficulty did not hold for orthographic projection material. Cognitive load theory could be used to suggest the ideal location of the intermediate stages. 相似文献
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我国的教育技术学目前面临的主要问题是理论研究和实践应用分离,文章分别从分析教育技术人才培养现状、教育技术的理论研究主体和教学实践主体的"实践"隔阂、教育技术理论应用于教学实践的哲学文化背景障碍入手,对这一主要问题进行了论证。并分别从教育技术实践场中研究主体、实践主体、行政主体、学生主体的角度出发,提出了改善的建议,最后提出培养学科教育技术人才是解决现有问题的一个途径。 相似文献
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多项式曲线拟合振荡现象的抑制 总被引：2，自引：0，他引：2
多项式曲线拟合是解决工程应用问题中曲线拟合最常用的方法。多项式次数较高时 ,拟合曲线在两端点附近出现的振荡现象一定程度上影响了曲线拟合的实际应用。本文介绍的拟合数据端点增权法 ,较好地解决了高次多项式曲线拟合的振荡问题 相似文献
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3-D scattering of obliquely incident plane p waves by alluvial valley embedded in layered half-space
The indirect boundary element method(IBEM) was established to solve the problem of 3-D seismic responses of 2-D topographies,by calculating the free-field responses with the direct-stiffness method and simulating the scattering wave fields with the dynamic Green’s functions of moving distributed loads.The proposed method yields accurate results,because the 3-D dynamic stiffness matrixes used are exact and the fictitious moving distributed loads can be acted directly on the interface between the alluvial valley and the layered half-space without singularity.The comparison with the published methods verifies the validity of the proposed method.And the numerical analyses are performed to give some beneficial conclusions.The study shows that 3-D scattering by an alluvial valley is essentially different from the 2-D case,and that the presence of soil layer affects not only the amplitude value of surface displacements but also the distribution of surface displacements. 相似文献
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卢义玉 《重庆大学学报(英文版)》2002,1(1):11-15
A new type jet, the oscillating & deflecting jet, is put forward and its oscillating and deflecting characteristics are investigated. The nozzle of the self-oscillating & deflecting water jet consists of an upstream nozzle, a downstream nozzle, an oscillating chamber and two switches. It is experimentally shown that the deflective angle may reach 9.53 degree. The generated pressure fluctuation is very regular and the jet can efficiently increase the ability for breaking and cutting by eliminating the water cushion effect associated with a continuous jet. 相似文献
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Research in non-equalization machining method for spatial cam 总被引：1，自引：0，他引：1
Many kinds of devices with cam have been widely used in various mechanical equipments. However, non-equalization machining for spatial cam trough remains to be a difficult problem. This paper focuses on the analysis of running conditions and machining processes of spatial cam with oscillating follower. We point out the common errors in the biased distance cutting. By analyzing the motion of oscillating follower of spatial cam, we present a new 3D curve expansion model of spatial cam trough-outline. Based on this model, we have proposed a machining method for trochoidal milling with non-equalization diameter cutter. This new method has led to a creative and effective way for non-equalization diameter machining for spatial cam with oscillating follower. 相似文献
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苗曼 《辽宁师范大学学报(社会科学版)》2011,34(4):46-49
心体关系问题是心理学学科中具有门槛意义的基础理论问题。对心体关系问题的回答中始终有一个无形的认识裂缝难以弥合,即：有形的物质载体是如何与无形的心理现象密不可分地嵌合为一体的？脑科学与基因科学的前沿进展为我们重新回答这一经典问题提供了新的契机。 相似文献
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利用二维贴片法对人体胫骨进行测试实验,用二维光路同步记录了x、y方向的云纹图像,据此图像测定胫骨的弹性常数、应变及位移,测试结果与电测法相比,误差小,灵敏度高． 相似文献