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51.
Y. D. Kolekar S. B. Kulkarni Keka Chakraborty A. Das S. K. Paranjpe P. B. Joshi 《Pramana》2004,63(2):189-197
Nd2Sn2O7 pyrochlores with the substitution of Zr4+ were prepared by conventional ceramic double sintering technique. The single-phase formation was confirmed by X-ray diffraction
and neutron diffraction techniques. Relative intensity calculations for X-ray diffraction analysis were performed for oxygen
positional parametersx = 0.331 and 0.375, while Rietveld refinements were employed for neutron diffraction data. The neutron diffraction study revealed
that there are only two anion sites with 48f and 8b positions. This indicates that the 8a site, i.e. O(3) sublattice, is completely
vacant and the structure is a perfect cubic pyrochlore with space group Fd3m (O
h
7
). From the conductivity measurements, it is observed that the electronic conductivity dominates from room temperature up
to about 525 K and forT > 525 K, the oxygen ion conduction dominates the charge transport in these compositions. Complex impedance spectroscopy indicates
the existence of grain and grain boundary as two separate elements. 相似文献
52.
J. M. Kumpula J. Saramäki K. Kaski J. Kertész 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):41-45
According to Fortunato and Barthélemy, modularity-based community detection
algorithms have a resolution threshold such that small communities in a large
network are invisible. Here we generalize their work and show that the q-state
Potts community detection method introduced by Reichardt and Bornholdt
also has a resolution threshold. The model contains a parameter by which this threshold can be tuned, but no a priori principle
is known to select the proper value.
Single global optimization criteria do not seem capable for detecting all
communities if their size distribution is broad. 相似文献
53.
54.
By using the tools of statistical physics and recent investigations of the scaling properties of different complex networks,
the structural and evolving properties of the Chinese railway network (CRN) is studied. It has been verified that the CRN
has the same small-world properties of the Indian railway network (IRN). According to the class of small-world networks, we
believe the CRN is a single scale. In addition, a novel result is obtained. Measurements on the CRN indicate that the rate
at which nodes acquire links depends on the node’s degree and follows a power law.
相似文献
55.
Jiangen Huang Guiqin Zhang Yuanhe Huang Decai Fang Deqing Zhang 《Journal of magnetism and magnetic materials》2006
A one-dimensional (1D) silver (I) complex of nitronyl nitroxide with fairly strong antiferromagnetic interaction, in which the metal ions are diamagnetic, is investigated by means of the ab initio crystal orbital method based on the density functional theory. The calculated values of the magnetic coupling constant (J) are close to the experimental measured J value in the periodic system. The magneto-structural correlation reveals that the existence of an antiferromagnetic coupling pathway along nitronyl nitroxide units via silver (I) ion in this system. The spin population distribution also shows the existence of spin delocalization along the ONCNO–Ag–ONCNO, which affords a rational interpretation for the antiferromagnetic interaction mechanism. 相似文献
56.
In this paper we develop the fundamental elements and results of a new theory of regular functions of one quaternionic variable. The theory we describe follows a classical idea of Cullen, but we use a more geometric formulation to show that it is possible to build a rather complete theory. Our theory allows us to extend some important results for polynomials in the quaternionic variable to the case of power series. 相似文献
57.
58.
L.B.Magalas 《物理学进展》2006,26(3):258-276
本文广泛地收集了有关内耗,力学谱,超声衰减方面的专著及会议文集。反映了20世纪在此领域的英文,俄文出版的书籍。也列出了历次国际会议及前苏联,乌克兰,中国的国内会议。文中包括了点缺陷,电,声子,位错,晶界,电畴等诸方面在内的内耗与力学谱工作。 相似文献
59.
60.
非对称三态叠加多模泛函叠加态光场的高次压缩——广义电场分量的不等幂次和压缩效应研究 总被引:2,自引:0,他引:2
多模真空态|{0j}〉q与两个空间强度分布特征不同的多模复共轭泛函相干态|{f(j a)*(x,y,z)}〉q和|{f(j b)*(x,y,z)}〉q的线性叠加组成的三态叠加多模泛函叠加态光场|ψ(f3)〉q,利用多模压缩态理论,研究了态|ψ(f3)〉q中广义电场分量的不等幂次高次和(H)压缩特性.结果表明:在一定的条件下,态|ψ(f3)〉q的广义电场分量可呈现出周期性变化的任意奇数次和任意偶数次的不等幂次高次H压缩效应;光场的经典振幅和经典初始相位的任意非对称空间分布特征对其压缩程度和压缩深度等压缩特性将产生直接的影响. 相似文献