共查询到20条相似文献,搜索用时 140 毫秒
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以流体比容方法和三阶PPM方法为基础,给出了适用于三级气炮超高速发射过程数值模拟的多流计算方法和计算代码MFPPM。利用Sandia实验室一系列的实验装置及其结果对计算代码进行了验证和确认,获得了较好的数值模拟结果(其中最大相对误差为1.07%),同时对冲击波物理与爆轰物理实验室设计的实验装置进行了数值模拟,计算结果与实验结果相差1.04%。为了更好地满足超高压下材料状态方程的测量,提出了一种带汇聚型的改进装置设计,并给出了相应的数值模拟结果。 相似文献
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利用线性自旋波方法并结合Hellmann-Feynman定理引入一种计算量子磁性系统临界磁场的方法.计算两种特殊模型的临界磁场,并将理论结果与数值结果进行比较,理论值与数值结果高度吻合,验证了理论方法的准确性. 相似文献
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本文研究了二维轴对称中子输运(包括各向同性散射和各向异性散射)问题的一种有限元数值方法。给出了一系列的数值计算结果,并与国内外的SN、间断有限元方法的数值结果及实验结果进行比较,取得了令人满意的结果。 相似文献
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K.S PEAT 《Journal of sound and vibration》2002,256(2):271-285
This paper presents an analytical investigation of the direct method of measurement of the source impedance of a linear time-variant source. The direct method yields a frequency-dependent effective source impedance which is routinely used in a time-invariant analysis to determine the insertion loss of two different acoustic loads applied to the same source. In such an analysis the strength of the source is assumed to be invariant with load. It is shown here that there is generally no precise correspondence between the effective source impedance as given by the direct method and the characteristics of the actual source. Furthermore, it is shown that the effective source impedance values given by the direct method are functions of the acoustic load and the location of the injected signal as used in the measurement. However, the effective source resistance is always found to be positive, in accordance with experimental measurements. In this regard the direct method is an improvement on the indirect method, where physically implausible negative resistance values are often found. Finally, it is shown that the effective impedance values as given by the direct method when used with a time-invariant analysis give rise to very accurate predictions of insertion loss, even when the strength of the actual time-variant source is allowed to vary with the acoustic load. 相似文献
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本文讨论了Ландау二级相变理论中的稳定性条件,阐明了Лифшиц提出的对称改变限制条件是不必要的,从而可以讨论过去认为无法讨论的镧系金属镝(Dy)等在Neél点的二级相变,解释了镧系金属镝等在Neél点以下螺旋磁结构的螺距与温度成线性关系。同时,利用空间羣表示论和热力势极小条件,建立了一个讨论磁结构的新方法,用这方法分析了镧系金属的磁结构,所得的结果与中子衍射实验相符合。 相似文献
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P. K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky B. Lehnert M. Mészáros P. R. Molnár J. P. Vigier S. Roy 《Foundations of Physics Letters》2000,13(2):179-184
It is shown that the Lehnert field equations in vacuum, with concomitant space charge and current, can be derived straightforwardly from standard gauge theory applied in vacuum, using the concept of covariant derivative and Feynman's universal influence. The Lehnert and Proca field equations are shown to be inter-related through the well-known de Broglie theorem, in which the photon mass can be interpreted as finite. These ideas go some way towards addressing the inconsistency inherent in Maxwell's famous displacement current, which has no concomitant vacuum space charge. 相似文献
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A space charge lens has been designed and tested which can be used to focus intense ion beams at several tens of keV. The experimental results obtained can be interpreted with a simplified physical model. The existence of a space charge field and its strong focusing properties are tested experimentally. And it is shown that the relaxation time for the formation of space charge field is much less than 10 μs under our experimental conditions, thus the lens can be used to focus pulsed beams with length of several hundereds of μs of longer. 相似文献
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In this paper we construct the lattice formulation of the pure gauge fields in a coset space in the cases of a group G with non-trivial topological property and of a chiral group G, and present a local gauge invariant action of a quark system on a fourdimensional Euclidean space lattice, which has the continuum limit as usual. For non-chiral group with trivial topological property, it is shown that the coset pure gauge fields have no influence on the confinement properties of the quark system by calculating latt-ice current-current propagztor when the coset pure gauge fields are retained manifest1y. 相似文献
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《Physics letters. [Part B]》1987,197(4):524-530
The purely cubic action in the string field theory is shown to provide a set of equations of motion for background fields which agree to those obtained by the vanishing condition of ß-functions in the non-linear sigma model. Using the sigma model as an auxiliary tool, a systematic method for solving the string field theory in curved space is proposed. 相似文献
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In this paper we construct a lattice formulation of the pure gauge fields on a coset space in the cases of a group G with non-trivial topological property and of a chiral group G, and present a local gauge invariant action of a quark system on a four-dimensional Euclidean space lattice, which has the continuum limit as usual. For non-chiral group with trivial topological property, it is shown that the coset pure gauge fields have no influence on the confinement properties of the confinement properties of the quark system by calculating lattice current-current propagator when the coset pure gauge fields remain manifest. 相似文献