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91.
Herbert Spohn 《Journal of statistical physics》1981,26(2):285-305
For a system of hard spheres we prove the convergence of the second moment of the fluctuation field in the low-density limit. This extends a previous result by van Beijeren, Lanford, Lebowitz and Spohn(1) to nonequilibrium states. 相似文献
92.
采用微面模型理论和损伤力学方法,建立了节理岩体的弹塑性损伤耦合微面模型. 在节理岩体的微
面上,将岩体视为由节理面与岩石组成的二元介质,以节理连通率作为岩体沿该方向的面积
损伤变量,考虑微面法向拉应力和压应力下的不同塑性变形和损伤耦合作用机制,基于塑性
理论建立了节理岩体的微面塑性损伤增量本构关系. 采用微面物理量与宏观物理量的几何约
束模型,根据微面方向积分导出了节理岩体的宏观弹塑性增量本构关系. 编制了节理岩体微
面模型的MARC有限元子程序,对节理岩体的单轴拉伸、压缩试验和泥浆压力作用下的井壁稳
定问题进行了数值模拟研究. 数值计算结果表明,该模型能很好地揭示载荷作用下节理岩体
的各向异性非弹性变形和次生节理演化过程. 相似文献
93.
嵌段聚酯型聚脲氨酯硬段微区中氢键化的红外光谱研究 总被引:1,自引:0,他引:1
用红外光谱法对基于4,4′二苯基甲烷二异氰酸酯(MDI)、乙二胺(ED)和聚己二酸丁二醇酯(PBA)(分子量分别为1975和1228)的两系列嵌段聚酯型聚脲氨酯(PUU)硬段微区的氢键化进行了研究。发出脲C=0基随着硬段含量增国出现双峰吸收,提出了PUU不同长度硬段序列中脲C=0基的两种平面氢键化的模型。认为这些平面氢键可以通过进一步键合来形成硬段微区中的三维氢键。 相似文献
94.
95.
郑永真 《核聚变与等离子体物理》2005,25(3):203-206
使用一维数值模型, 推断了逃逸能量εr与逃逸约束时间τr的关系。模拟结果给出能量εr 和放电参数的定标律。在HL- 1M 装置中不同实验条件下测量了硬X 射线谱, 研究了逃逸电子能量 εr模拟的定标律, 并推导出HL- 1M 装置放电的逃逸电子的约束时间与逃逸电子扩散系数。 相似文献
96.
《Physics and Chemistry of Liquids》2012,50(4):211-215
Abstract In this note, we utilize the recently calculatd long wavelength limit of the “liquid virtual crystal” model of binary alloy liquid structure factor at the melting temperature, STM AB (0), to estimate the long-volume binary liquid alloys. We compare the calculate sound velocities to the available experimental sound velocities in these liquid binary alloys and find reasonable agreement. 相似文献
97.
We prove the existence of a weak solution to the compressible Navier–Stokes system with hard sphere possibly non-monotone pressure law involving, in particular, the Carnahan–Starling model [2] largely employed in various physical and industrial applications. We take into account large velocities prescribed at the boundary of a bounded piecewise domain and large densities prescribed at the inflow boundary without any restriction neither on the shape of the inflow/outflow boundaries nor on the shape of the domain. 相似文献
98.
This paper reviews recent advances (mostly after year 2000) in shock and vibration analysis of hard disk drives (HDD) considering
the presence of nonlinearities and discontinuities. Components and dynamic phenomena in HDD where effects of mechanical nonlinearity
and discontinuities are significant are discussed, e.g., head actuator suspension, dimple and slider, head–disk interface,
fluid dynamic bearing, spinning disks, and load/unload dynamics. Ways to model these nonlinearities and discontinuities are
reviewed in detail. Our research on modeling an entire HDD in operating mode subject to shock and vibration using a flexible
multibody dynamics formulation is also presented. The numerical simulation of the shock response of a 1-in. form factor HDD
is presented. A half-sinusoidal acceleration shock is applied at the base of the HDD. Response of the flying height for different
shock amplitudes and duration times is simulated. 相似文献
99.
Andreas Galanis Qi Ge Daniel Štefankovič Eric Vigoda Linji Yang 《Random Structures and Algorithms》2014,45(1):78-110
We study the computational complexity of approximately counting the number of independent sets of a graph with maximum degree Δ. More generally, for an input graph and an activity , we are interested in the quantity defined as the sum over independent sets I weighted as . In statistical physics, is the partition function for the hard‐core model, which is an idealized model of a gas where the particles have non‐negligible size. Recently, an interesting phase transition was shown to occur for the complexity of approximating the partition function. Weitz showed an FPAS for the partition function for any graph of maximum degree Δ when Δ is constant and . The quantity is the critical point for the so‐called uniqueness threshold on the infinite, regular tree of degree Δ. On the other side, Sly proved that there does not exist efficient (randomized) approximation algorithms for , unless , for some function . We remove the upper bound in the assumptions of Sly's result for , that is, we show that there does not exist efficient randomized approximation algorithms for all for and . Sly's inapproximability result uses a clever reduction, combined with a second‐moment analysis of Mossel, Weitz and Wormald which prove torpid mixing of the Glauber dynamics for sampling from the associated Gibbs distribution on almost every regular graph of degree Δ for the same range of λ as in Sly's result. We extend Sly's result by improving upon the technical work of Mossel et al., via a more detailed analysis of independent sets in random regular graphs. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 45, 78–110, 2014 相似文献
100.
The propagation of transverse surface waves in a piezoelectric layer/metal substrate system with one or multiple hard metal interlayer(s) is investigated analytically. The general dispersion equations for the existence of the waves are obtained in a simple mathematic form for class 6 mm piezoelectric materials. The presence of a hard metal interlayer can not only get rid of the undesired mode appearing in the case without an interlayer but shorten the existence range of the phase velocity within which a nonleaky but dispersive mode exists. The effects of the hard interlayer on the phase velocity can be used to manipulate the behavior of the waves and has implications in acoustic wave devices. 相似文献