共查询到20条相似文献,搜索用时 109 毫秒
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在某些条件下共同驱动随机系统的乘法噪声和加法噪声可以相互关联,相关噪声驱动的随机微分系统具有独特的性质,而数值模拟是研究这类系统一种强有力的方法。研究相关噪声驱动系统的数值模拟算法,分别就白噪声情形和色噪声情形作了讨论,得到了一种一阶数值模拟算法,并与已有文献的解析结果进行了对比。 相似文献
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用Laplace变换法求解端点系有集中质量的弹性杆的振动问题 总被引:6,自引:2,他引:4
用Laplace变换法求解了一端为齐次边界条件,另一端系有集中质量的弹性杆的纵振动问题,推广了相关文献的结果。 相似文献
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采用第一原理分子动力学(QMD)方法模拟液体钚的输运性质.计算的粘性和扩散系数在较低温度时与文献有明显差异,在实验测量范围内,模拟结果与实验一致,温度升高时数值模拟结果趋于一致.利用QMD的模拟结果计算了应力自相关函数和速度自相关函数,结果表明:在温度较低时,液体钚呈现明显的强关联特性.对于具有强关联特性的液体,利用较短时间的QMD模拟结果,通过简单e指数拟合外推到t→∞得到的扩散系数和粘性具有较大偏差,这是造成本文模拟结果与文献结果出现差异的主要原因.通过增加QMD模拟时间步数,获得了更为准确的输运性质. 相似文献
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对卫星近日点旋进现象的分析——"地球的扁率对卫星运动的影响"一文的疏忽 总被引:1,自引:1,他引:0
指出了一篇相关文献中的疏漏,讨论了卫星近日点的旋进现象,得出了在一般情况下卫星近日点旋进的快慢程度与近日点本身所处的位置有关的结论. 相似文献
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本文首先指出文献[1]在推导过程中的欠妥之处,而后采用曲线坐标中的基向量导出狭义相对论中自由质点的拉格朗日函数,得到了与文献[1]完全相同的结果,不仅方法简捷,推导严密,且物理意义清晰. 相似文献
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利用狭义相对论对同时性的理解,指出了关于一种长度收缩佯谬解释的不妥之处,并解释了改进后的关于长度收缩佯谬的提法,证明了在不同参照系上的观测者观测所得到的结论相同. 相似文献
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也谈均匀带电细圆环的电场分布 总被引:1,自引:0,他引:1
用Mathematica研究均匀带电细圆环的电场的空间分布,准确地绘制出电场强度量值的分布图和电场方向的分布图,并纠正了最近文献中一幅场强量值分布图的失误. 相似文献
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D'Orazio D De Cesaris S Garai M 《The Journal of the Acoustical Society of America》2011,130(4):1954-1961
The "effective duration" of the autocorrelation function (ACF), τ(e), is an important factor in architectural and musical acoustics. For a general application, an accurate evaluation of τ(e) is relevant. This paper is focused to the methods for the extraction of τ(e) values from the ACF. Various methods have been proposed in literature for the extraction of the τ(e) from a given signal, but these methods are not unambiguously defined or may not work properly in case of particular signals. Therefore, the general use of these methods may sometimes give rise to questionable results. In the present work, the methods existing in literature for extracting τ(e) are analyzed, their advantages and drawbacks are summarized, and finally an alternative method is proposed. The proposed algorithm is compared to those found in previous literature, applying them on the same sound signals (classic literature references and other ones publicly available on the Internet). It is shown that the results obtained with the proposed method are consistent with the results of the previous literature; moreover the proposed method may overcome some of the limitations of the existing methods. 相似文献
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对无线电波绕球形地球的绕射这一经典问题作了很简要的综述,目的在于指出在这一般认为十分成熟的理论中在数学推导上存在一个错误。论述了正确的分析方法。 相似文献
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Narozhny NB Fofanov MS 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):3443-3449
We show that there is a mistake in the results recently published by An Yu and H. Takahashi [Phys. Rev. E 57, 2276 (1998)] for the probabilities of a photon emission by an electron and a pair production by a photon in the field of a two-frequency plane electromagnetic wave. In this paper we present the corrected expression for the probability of a photon emission which contains terms missed by Yu and Takahashi. We argue also that the effect of presence of the waves with combination frequencies in the external field proposed by the authors of the paper [Phys. Rev. E 57, 2276 (1998)] has no physical basis. 相似文献
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指出“悠悠球”或“滚轮摆”在“下落”和“上升”两个独立阶段,机械能守恒,但在最低点的“转折”处,由于未加考虑系统突变效应而产生的能量损耗,导致错误地认为机械能不变.这个错误在教学中、课本里以及各种丛书中长期存在,应该引起重视. 相似文献
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J. Gerardin N. Seiler P. Ruyer L. Trovalet P. Boulet 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(2):140-149
A numerical study has been conducted using the differential approximation and two modified versions of this method, known as MDA and IDA. The methods have been applied on a 3D geometry containing a participating, absorbing, emitting and anisotropically scattering medium. Comparisons have been carried out with some cases of the literature. It has been observed that the IDA can significantly improve the solution, where the classical P1 approximation is not able to reproduce accurately the actual flux or flux divergence in some of studied configurations. The MDA does not really improve the solution in the purely absorbing cases and when radiation is mainly coming from the medium. In other situations (scattering media, relevant influence of the boundaries), the MDA is more accurate than the P1 but the IDA still performs better, with uncertainties around a few percents for the literature cases studied in the present work. 相似文献