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描述液晶向列相和胆甾相弹性性质的自由能密度,其形式为其中n(r)为空间r处之指向(director),代表分子的平均取向,|n|=1.2π/q0为胆甾相的螺距.在向列相中,q0=0.K1—K3为弹性常数.有关这些物理量的进一步讨论,参看文献[1-4].这个简单的自由能的具体形式(从1933年起Oseen[1]和Zocher[2]初步考虑,其后1958年Frank[3]比较完备的处理,以至后人?... 相似文献
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本文讨论仿射Kac-Moody李代数的生成元配对问题.对任意的xl(k)型仿射Kac—Moody李代数g(A)以及任意的非零虚根向量x,也证明了:存在某个y∈g(A),使得g’(A)包含在由x和y所生成的李代数之中. 相似文献
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1965年,Suzuki[1]导出适用于Ising模型及其他经典系统关联函数的严格公式.近年来,作者之一[2,3]将Suzuki的公式展开后用在液晶中,解释了向列相(N)-各向同性液相(I)相变前行为的一些实验.最近,张昭庆等[4]又将Suzuki公式作了推广.本文在文献[l,4]的基础上,把Suzuki公式作进一步的推广.新的公式既适用于纯系统,也适用于混合系统.我们简单地讨论了这?... 相似文献
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An all-reflective self-referenced spectral interferometry based on the transient grating(TG)effect is proposed for single-shot measuring of the amplitude and phase of ultrashort pulses in a broadband spectral range.Except for a thin third-order nonlinear medium,which was used to generate the TG signal,no transmitted optics were used in the proposed device,and few-cycle pulses in a broad spectral range from deep UV to mid-IR can be characterized.With a homemade compact and alignment-free device,a 5.0 fs pulse at 800 nm corresponding to about two cycles and a 14.3 fs pulse at 1800 nm corresponding to less than three cycles were successfully characterized. 相似文献
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活性行走是描述复杂 (或简单 )系统的图样形成和自组织的一个范式 (paradigm) .一个活性行走者的每一步都改变地形 ,其如何选择下一步受改变后地形的影响 .活性行走模型已经成功地应用于很多生物、物理与社会科学系统中 ,其中包括视网膜神经细胞和液体薄层表面反应的图样形成、玻璃中离子的异常传输、蚂蚁群的觅食、高科技经济学中产品的市场竞争 ,等等 . 相似文献
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The samples Fe0.4Cu0.6 and Fe0.5Cu0.5 ball milled for 50 h are investigated by X-ray diffraction, M?ssbauer spectra, as well as magnetic measurement. The experiments show that the structure of the samples is fcc, with lattice constant 0.361 nm and there are fcc Fe-rich phase and fcc Cu-rich phase in the samples. Most of Fe atoms (91%) are in the fcc Fe-rich phase, which is a ferromagnetic phase. The M-H curve at 1.5 K shows the saturation magnetization of the samples are 80.5 emu/g and 101.6 emu/g for Fe0.4Cu0.6 and Fe0.5Cu0.5 respectively. The average magnetic moment of Fe atoms is deduced to be 2.40 μB . Compared with theoretical predication, the Fe atoms in the fcc phase are in high spin state. 相似文献
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