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对于高中物理力学中的动态平衡问题,本文总结了几种处理方法,有动态图解法、相似三角形法、正交分解法、整体法和隔离法、正弦定理法、极值法,且指明了每种方法的原理和适用条件。 相似文献
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介绍了模拟自适应光学系统中受大气湍流影响的光学波前的四种方法,即基于Zernike多项式的K—L函数展开法、小波法、Fourier法以及ARMA法。分析比较了四种方法模拟精度和速度。结果表明,前两种方法不论是精度还是速度上都比较好,更适合湍流波前的模拟。 相似文献
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将重构核粒子法(RKPM)和边界积分方程方法结合,提出了一种新的边界积分方程无网格方法——重构核粒子边界无单元法(RKP-BEFM).对弹性力学问题,推导了其重构核粒子边界无单元法的公式,研究其数值积分方案,建立了重构核粒子边界无单元法离散化边界积分方程,并推导了重构核粒子边界无单元法的内点位移和应力积分公式.重构核粒子法形成的形函数具有重构核函数的光滑性,且能再现多项式在插值点的精确值,所以本方法具有更高的精度.最后给出了数值算例,验证了本方法的有效性和正确性.
关键词:
重构核粒子法
弹性力学
边界无单元法 相似文献
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在ICP-AES中,卡尔曼滤波是一种有效的光谱干扰校正方法,它在强背景、谱线重叠严重的情况下,仍可得到很好的分析结果;并且有比传统分析线法在纯组分试样条件下更低的检出限。然而,噪声的存在影响了卡尔曼滤波的准确度。小波变换因其多分辨分析的特性,近年来被用于分析信号的去噪,而且该方法简单、快速,是一种很有效的去噪方法。本文首先用仿真数据研究了噪声对卡尔曼滤波法的影响;其次,将小波变换引入卡尔曼滤波法,提出了基于小波变换的卡尔曼滤波法,仿真实验结果表明,该方法能有效提高卡尔曼滤波法的分析准确度。 相似文献
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本文首先论述厅堂声场控制的各种方法,然后利用混响反馈法和卷积法分别进行了实验研究,其中着重对卷积法的实验系统进行阐述,指出卷积法具有混响时间调节方便、控制范围大等优点,混响时间可提高三倍以上. 相似文献
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G. Shirkov 《辐射效应与固体损伤》2013,168(10-12):483-493
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Transported probability density function (PDF) methods have been applied widely and effectively for modelling turbulent reacting flows. In most applications of PDF methods to date, Lagrangian particle Monte Carlo algorithms have been used to solve a modelled PDF transport equation. However, Lagrangian particle PDF methods are computationally intensive and are not readily integrated into conventional Eulerian computational fluid dynamics (CFD) codes. Eulerian field PDF methods have been proposed as an alternative. Here a systematic comparison is performed among three methods for solving the same underlying modelled composition PDF transport equation: a consistent hybrid Lagrangian particle/Eulerian mesh (LPEM) method, a stochastic Eulerian field (SEF) method and a deterministic Eulerian field method with a direct-quadrature-method-of-moments closure (a multi-environment PDF-MEPDF method). The comparisons have been made in simulations of a series of three non-premixed, piloted methane–air turbulent jet flames that exhibit progressively increasing levels of local extinction and turbulence-chemistry interactions: Sandia/TUD flames D, E and F. The three PDF methods have been implemented using the same underlying CFD solver, and results obtained using the three methods have been compared using (to the extent possible) equivalent physical models and numerical parameters. Reasonably converged mean and rms scalar profiles are obtained using 40 particles per cell for the LPEM method or 40 Eulerian fields for the SEF method. Results from these stochastic methods are compared with results obtained using two- and three-environment MEPDF methods. The relative advantages and disadvantages of each method in terms of accuracy and computational requirements are explored and identified. In general, the results obtained from the two stochastic methods (LPEM and SEF) are very similar, and are in closer agreement with experimental measurements than those obtained using the MEPDF method, while MEPDF is the most computationally efficient of the three methods. These and other findings are discussed in detail. 相似文献
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R. Kirby 《Journal of sound and vibration》2009,325(3):565-582
Identifying an appropriate method for modelling automotive dissipative silencers normally requires one to choose between analytic and numerical methods. It is common in the literature to justify the choice of an analytic method based on the assumption that equivalent numerical techniques are more computationally expensive. The validity of this assumption is investigated here, and the relative speed and accuracy of two analytic methods are compared to two numerical methods for a uniform dissipative silencer that contains a bulk reacting porous material separated from a mean gas flow by a perforated pipe. The numerical methods are developed here with a view to speeding up transmission loss computation, and are based on a mode matching scheme and a hybrid finite element method. The results presented demonstrate excellent agreement between the analytic and numerical models provided a sufficient number of propagating acoustic modes are retained. However, the numerical mode matching method is shown to be the fastest method, significantly outperforming an equivalent analytic technique. Moreover, the hybrid finite element method is demonstrated to be as fast as the analytic technique. Accordingly, both numerical techniques deliver fast and accurate predictions and are capable of outperforming equivalent analytic methods for automotive dissipative silencers. 相似文献