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221.
The static and evolutionary properties of two-dimensional cellular structures, or froths, are discussed in the light of recent work on structuring of the froth into concentric shells. Of interest is the dual role of a topological dislocation (defect) in an otherwise uniform froth, considered both as a source of disorder and also as a source generating a shell-structured froth. We present simulations on an initially uniform hexagonal froth. A defect is introduced by forcing either a T1 or T2 process in the stable structure, after which the froth is allowed to evolve according to von Neumann's law. In the first case, topological inclusions are found in the first few layers early in the evolution. In the second case, no inclusions appear over the entire evolutionary period. The growing disorder (as measured by the second moment of the side distribution,
2) is isotropic. For the special case of a T2-formed froth in a uniform network, the SSI structure is retained with
20 only for the zeroth, first, and second layers. The ratio between topological perimeter and radius of the shells is close to 6, the value for a hexagonal froth. 相似文献
222.
热强子质量的有效手征拉氏量近似 总被引:1,自引:0,他引:1
从再现QCD标度反常的线性化手征拉氏量出发,使用热场动力学理论,计算了单圈近似下强子的热质量,并发现组分夸克质量和标量场质量在单圈近似下比在平均场近似下随温度的增加更快地下降,而在手征极限下,π介子在所有温度保持无质量. 相似文献
223.
Wolfram Just 《Journal of statistical physics》1998,90(3-4):727-748
A simple construction is presented which generalizes piecewise linear one-dimensional Markov maps to an arbitrary number of dimensions. The corresponding coupled map lattice, known as a simplicial mapping in the mathematical literature, allows for an analytical investigation. In particular, the spin Hamiltonian which is generated by the symbolic dynamics is accessible. As an example, a formal relation between a globally coupled system and an Ising mean-field model is established. The phase transition in the limit of infinite system size is analyzed and analytical results are compared with numerical simulations. 相似文献
224.
采用分子动力学模拟的方法研究了Cu50Ni50合金在不同冷却速度下的凝固过程,利用均方位移、径向分布函数和结构可视化等方法分析其微观结构.并对凝固模型进行拉伸模拟,通过应力应变曲线和直观结构变化分析其性能.研究表明:冷却速度对Cu50Ni50合金凝固形成的结构有较大影响,随着冷却速度的升高,凝固形成的结构中晶体含量减少,在较低的冷却速度下,如冷却1×1012K/s时,Cu50Ni50合金凝固形成晶体结构;在较高的冷却速度下,如1×1014K/s时,Cu50Ni50合金凝固形成非晶体结构,且非晶Cu50Ni50合金的抗拉性能要优于晶体Cu50Ni50合金. 相似文献
225.
A low power density single-pulse laser irradiation of the Si surface has been used for the study of formation and self-organization of silicon nanotips. A two dimensional regular array of hillock-like nanotips has been created in the central region, a disturbed array comprising crossed lines of hillocks in the near-central region, and the “V”-shaped array in the peripheral region. Therefore, the long-range organization of hillocks changes from the center toward the periphery, following the Gaussian-like laser power profile. The evolution of hillocks due to the flow instability of molten silicon is equivalent to the instability of a liquid layer falling down a vertical plate. The novel result is that the hillock-like soliton structures can be identified with the lump solitons resulting from the nonlinear hydrodynamic instability evolution. 相似文献
226.
227.
对SU(N)情形, 应用法捷耶夫和尼米的非阿贝尔规范势的拓扑分解, 在路径积分中, 将除拓扑自由度以外的其它自由度积掉, 求出单圈和低能近似下的有效作用量. 结果支持由对偶迈斯纳效应造成色禁闭的图像. 也讨论了费米子场的效应. In the SU(N) case we use the Fadeev Niemi topological decomposition of nonabelian gauge potentials to derive the low energy effective Lagrangian under one loop approximation by integrating all degrees of freedom except the topological ones in its path integral. The result supports a mechanism on color confinment which comes from the dual Misner Effect. The effect from fermion fields is also discussed. 相似文献
228.
F. Rodrigues G. Ferru L. Berthon N. Boubals P. Guilbaud C. Sorel 《Molecular physics》2014,112(9-10):1362-1374
This paper presents the methodology developed in order to thoroughly characterise a solvent extraction system containing high solute concentrations. The chemical system selected is N,N-(2-ethylhexyl)isobutyramide (DEHiBA) diluted in one alkane with increasing concentration of uranium(VI). Combining experiments with theoretical calculations allowed a deeper understanding of the extraction mechanism. A thermodynamic study was performed by the classical van't Hoff method and also by direct calorimetry to provide the enthalpies of extraction and specific heats. Dedicated methods like vapour pressure osmometry and electrospray ionisation mass spectrometry analysis provide information about the stoichiometry of the extracted species. Spectroscopic investigations with ultraviolet–visible and Fourier transform infrared probed the uranium coordination. Finally, a combination of molecular dynamics simulations, and small and wide-angle X-ray scattering experiments investigated the organisation in the organic phase beyond the molecular scale. It was shown that the high concentrations of uranium extracted have no influence on the stoichiometry of the complexes and the coordination of uranium in the inner sphere. The thermodynamic properties related to the extraction process and obtained with a fine consideration of the activity coefficients showed to be the same as those found with trace concentration. However, an unexpected organisation beyond the molecular scale was observed with an important role of nitrates as bridging ligands which could explain some physico-chemical properties. This approach could be applied to other chemical systems (other N,N-dialkylamides or other cations) to identify the origin of the different affinities between ligands and the difference of selectivity between cations. 相似文献
229.
A theorem proved by R. Høegh-Krohn in Comm. Math. Phys. 38(1974), 195–224, which yields a possibility to define states of systems of quantum particles by their values on the products
, where \mathfraka
t
, t
are time automorphisms and F
j
are multiplication operators, is generalized and extended. In particular, it is shown that the algebras generated by such products with F
j
taken from the families of multiplication operators satisfying certain conditions are dense in the algebras of observables in the -weak topology, in which normal states are continuous. This result was obtained for the systems with two types of kinetic energy: the usual one expressed by means of the Laplacian; the relativistic kinetic energy defined by a pseudo-differential operator. 相似文献
230.