Dynamic crystal plasticity: An Eulerian approach

In this paper an Eulerian rate-dependent single crystal model that accounts for high-strain rates, large strains and rotations is developed. The viscoplastic law as well as the evolution equations for the lattice are written in terms of vectorial and tensorial quantities associated with the current configuration. The viscoplastic law is obtained from Schmid law using an overstress approach. Such an expression for the viscoplastic law is motivated by the microdynamics of crystal defects. A general analysis of the plane-strain response of the proposed rigid-viscoplastic single crystal model is presented. It is shown that only one differential equation, involving the orientation of one composite in-plane slip system, is necessary to describe the lattice evolution. Several two-dimensional boundary value problems, such as equal-channel die extrusion and channel die compression are selected to illustrate the predictive capabilities of the model. The results show that even at relatively low strain rates the viscosity plays an important role in the development of localized deformation modes. At high crosshead velocity, the plastic properties and crystal anisotropy are less important while inertia effects are dominant. Finally, the grains interaction is investigated by analyzing the compression of a grains multicrystal.     

（2＋2）-Dimensional Discrete Soliton Equations and Integrable Coupling System

In this paper, we extend a （2＋2）-dimensional continuous zero curvature equation to （2＋2）-dimensional discrete zero curvature equation, then a new （2＋2）-dimensional cubic Volterra lattice hierarchy is obtained. Fhrthermore, the integrable coupling systems of the （2＋2）-dimensional cubic Volterra lattice hierarchy and the generalized Toda lattice soliton equations are presented by using a Lie algebraic system sl（4）.     

Numerical Simulation of Two-Dimensional Flow over Three Cylinders by LatticeBoltzmann Method

The numerical simulation using the multiple relaxation time lattice Boltzmann method (MRT-LBM) is carried out for the purpose of investigating the two-dimensional flow around three circular cylinders. Among these three circular cylinders, one of the three cylinders on which a forced in-line vibrating is used to do this research and attempt to find out the effects of the movingcylinder and the other two rigid cylinders on the wake characteristics and vortex formation. As a benchmark problem to discuss the problem of lift coefficient r.m.s for these cylinders with spacing ratios T/D between other rigid side-by-side cylinders, and the calculation is carried out with two compared cases at Reynolds number of 100, two of the cylinders are rigid and the other one is an in-line vibrated cylinder lying downstream, in addition, forced vibrating amplitude and frequency are A/D= 0.5 and f_ν=0.4 (where A is the forced amplitude, D is the cylinder diameter, and f_ν stands for the vibrating frequency, respectively). The calculated results not onlyindicate that the spacing ratios T/D (T is the center-to-center spacing between the two upstream cylinders) have influence on the wake patterns and the formation of vortex shedding, but also analyze the lift coefficient r.m.s for the three cylinders with the spacing ratios S/D (where S is the center-to-center spacing between the center of upstream two side-by-side cylinders and downstream cylinder).     

Metric Expansion from Microscopic Dynamics in an Inhomogeneous Universe

Theories with ingredients like the Higgs mechanism, gravitons, and inflatonfields rejuvenate the idea that relativistic kinematics is dynamicallyemergent. Eternal inflation treats the Hubble constant H as depending onlocation. Microscopic dynamics implies that H is over much smaller lengthsthan pocket universes to be understood as a local space reproduction rate.We illustrate this via discussing that even exponential inflation inTeV-gravity is slow on the relevant time scale. In our on small scalesinhomogeneous cosmos, a reproduction rate H depends on position. We therefore discuss Einstein-Strauss vacuoles and a Lindquist-Wheeler like lattice to connect the local rate properly with the scaling of an expanding cosmos. Consistency allows H to locally depend on Weyl curvature similar to vacuum polarization. We derive a proportionality constant known from Kepler's third law and discuss the implications for the finiteness of the cosmological constant.     

Security analysis of a multiple pseudorandom-bit generator based on a spatiotemporal chaotic map

<正>In this paper we analyse the security of a multiple pseudorandom-bit generator based on the coupled map lattice and suggest an improved model.Utilizing the error function attack,the multiple pseudorandom-bit generators which can be realized by the three digitization methods are analysed and the effective key spaces are estimated.We suggest an improved multiple pseudorandom-bit generator with 128-bit secret key,and analyse the key sensitivity and statistical properties of the system.     

强伪Ockham代数与剩余格

引入了伪Ockham代数的概念,讨论了伪Ockham代数与剩余格的关系.进一步引入强伪Ockham代数概念,并给出了它的基本性质.然后,将著名的R0蕴涵和R0算子推广到伪Ockham代数上,证明了添加广义R0蕴涵和广义R0算子后的伪Ockham代数L成为剩余格的充要条件是L为强伪Ockham代数.最后给出注记,以此说明强伪Ockham代数的条件是独立的.     

μ+SR Study of Ordering Phenomena in the Heavy-Fermion State of Ce3Pd20Ge6

Magnetic and quadrupolar ordering phenomena in a Ce₃Pd₂₀Ge₆ single crystal have been investigated by muon spin rotation/relaxation (μ⁺SR) spectroscopy. We have observed spontaneous precession of muons in zero-field below T _N =0.7 K in the antiferromagnetic state. The precession frequency follows the power law: ν(T)=ν(0)(1−T/T _N ) ⁿ . The exponent n=0.43(2) is close to the mean-field value of 0.5. The muon longitudinal spin relaxation rate 1/T ₁ is found to be nearly independent of temperature in the range of 0.3 to 2 K, i.e., across either T _N or T _Q =1.2 K, the quadrupolar ordering temperature. Two likely mechanisms for the temperature independent behavior of 1/T ₁ are suggested. This revised version was published online in September 2006 with corrections to the Cover Date.     

Brute-force NMR-ON on 90NbCu, 101mRhCu and110mAgAg

Brute-force nuclear magnetic resonance on oriented nuclei (BF-NMRON) experiments have been performed for ⁹⁰NbCu, ^101m RhCu and ^110m AgAg at about 10mK. Narrow resonance spectra were detected. Using the known values of the g-factors, the Knight shift has been deduced: K(⁹⁰NbCu) = 0.62(24) %, K(^101m RhCu) = 0.87(27)%. The effective spin–lattice relaxation times were also measured.     

Site Preference Model for Hyperfine Impurities in Compounds

A thermodynamic model for site preferences of solute atoms in ordered binary phases is applied in this paper for substitutional and interstitial sites of the Cu₃Au, or L1₂, structure. Site preferences are found to depend on formation energies of combinations of elementary point defects and on energies for transfer of solutes among different sites. The composition dependence in compounds having a wide phase field is examined in detail. A phenomenology of site preference behavior is outlined for regular lattice sites as well as for non-lattice sites such as grain boundaries. This revised version was published online in September 2006 with corrections to the Cover Date.     

用改进的格点哈密顿量计算2+1维QCD 0++胶球质量

用改进的格点哈密顿量和截断本征方程法计算2＋1维QCD 0^ 胶球质量,结果显示较好的标度行为。