Structure and Characteristics of the Fracturing of Layered Ni-Al Composites

Layered composite materials with alternating layers of a solid solution of aluminum in nickel and intermetallic Ni-Al compounds are obtained. The evolution of the composite structures depending on the heat-treatment conditions is discussed. The mechanical tests of materials highlight a fracture toughness of up to 23 MPa m^1/2, a strength of up to 1800 MPa at room temperature and 150–480 MPa in the range 1000–1150°C.     

Numerical Analysis of the Rebellious Voter Model

The rebellious voter model, introduced by Sturm and Swart (2008), is a variation of the standard, one-dimensional voter model, in which types that are locally in the minority have an advantage. It is related, both through duality and through the evolution of its interfaces, to a system of branching annihilating random walks that is believed to belong to the ‘parity-conservation’ universality class. This paper presents numerical data for the rebellious voter model and for a closely related one-sided version of the model. Both models appear to exhibit a phase transition between noncoexistence and coexistence as the advantage for minority types is increased. For the one-sided model (but not for the original, two-sided rebellious voter model), it appears that the critical point is exactly a half and two important functions of the process are given by simple, explicit formulas, a fact for which we have no explanation.     

Self-Consistent Model and Numerical Analysis of VCSEL''s Laser Diodes

A self-consistent model of vertical-cavity surface-emitting lasers (VCSEL's) is presented in this paper, in which the carrier diffusion rate equation, the photon density rate equation, and the thermal conduction equation are considered simultaneously. The nonuniform heat flux density distribution in the active region due to the current-spreading effect is taken into account. The effects of temperature on gain and transparency carrier density are also included in this model. It is nonlinearly and self-consistently solved in the Matlab environment. The transient and lateral distribution characteristics of the carrier and photon densities and the junction temperature are investigated. Some interesting results are gotten and analyzed.     

Numerical Analysis of Electromagnetic Fields in Multiscale Model

Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.     

Analytical Study of the Layered XY Model with VCE Method

Motivated by experiments on liquid-crystal films, we study the development of specific heat anomaly of finite layer system. With the VCE method, we introduce the strong surface interaction into the layered XY model and get the results of the forth-order analytical expansion. The results show that when the strong surface interaction becomes strong enough, the order trend defeats the quantum noise and the specific heat peak moves abnormally to the high temperature with the number of layers decreasing.     

Numerical Study of Shock-Wave Loading of the W- and WC-Based Metal Composites

Technical Physics - Shock-wave loading of metal composites (Elkonites) that represent sintered refractory materials (tungsten, tungsten carbide, or molybdenum) in combinations with low-melting...     

Numerical Study of the Kneading Theory for the Lorenz Model

To a good approximation, the Lorenz attractor in the Poincark section may be viewed as a one-dimensional object. A family of maps proposed by Sparrow models the Lorenz system very well. Such maps are numerically constructed. Under the guide of the kneading theory for the maps a numerical study of the Lorenz system is conducted.     

Three-Stage Evolution of the Structure and the Effect of Nonadditive Hardening of Layered Composites of Amorphous Alloys under High-Pressure Torsion

JETP Letters - The local chemical composition of composites consisting of alternating layers of Co28.2Fe38.9Cr15.4Si0.3B17.2 and Fe53.9Ni26.5B20.2 amorphous alloys subjected to torsion with...     

New Semiclassical and Numerical Approaches to Locate Zeros of Wave Functions

A new semiclassical method is presented for evaluating zeros of wave functions. In this method, locating zeros of the wave functions of Schrodinger equation is converted to finding roots of a polynomial. The coefficients of this polynomial are evaluated using WKB and semi quantum action variable methods. For certain potentials WKB expressions for moments are obtained exactly. Almost explicit formulae for moments are obtained for the potential V(x)=x^N. Examples are given to illustrate both methods. Using semi quantum action variable method, complex zeros of the wave functions of the PT symmetric complex system V(x)=x^4 iAx are obtained. These zeros exhibit complex version of in terlacing.     

Model for the production of circular polarization via beam-foil interaction

Electron capture by protons in the tail of the electron density at a metal surface is investigated. The ion velocity is assumed to be large compared to the velocity of an electron in the lowest orbit of hydrogen. Electron transition probabilities into the 2p states of hydrogen are calculated, analogous to the first Born approximation by extending a model of Trubnikov and Yavlinskii [1] to tilted foils and nonzero angular momentum of the captured electron. From the density matrix the Stokes parameters are calculated. The results give partial agreement with experimental data, especially for the sinusoidal dependence of circular polarization on foil tilt angle.     

金属锡Rayleigh-Taylor不稳定性对模型参数敏感性的数值分析

利用自研的爆轰与冲击动力学欧拉计算程序和Steinberg-Guinan(SG)本构模型,数值模拟分析了样品初始参数(初始振幅、初始波长、样品初始厚度)和SG本构模型初始参数对爆轰驱动锡Rayleigh-Taylor(RT)不稳定性增长的影响。结果表明金属锡样品的初始参数对其RT不稳定性增长有很大的影响。RT不稳定性增长随着初始振幅的减小而减小,且存在一个截止初始振幅;存在一个最不稳定的模态(波长),当初始波长大于该波长时,RT不稳定性增长随着初始波长的减小而增大,反之,RT不稳定性增长随着初始波长的减小而减小;样品厚度的增大可以抑制RT不稳定性增长,而且存在一个样品截止厚度。金属锡的RT不稳定性增长对其SG本构模型应变硬化系数和应变硬化指数的变化不敏感,而对压力硬化系数和热软化系数比较敏感。从采用扰动增长法预估材料强度的角度来说,修正压力硬化系数以获得锡合理的材料强度是合理的途径。     

A Mathematical Model for Prediction of the Tribological Properties of Oil-Filled Composites under Vibration

Doklady Physics - The tribological properties of an oil-filled composite material are studied. The dynamic contact problem of the vibration of a rigid punch on a heterogeneous half-space is solved...     

Qualitative and Numerical Analysis of a Cosmological Model Based on an Asymmetric Scalar Doublet with Minimal Connections. IV. Numerical Modeling and Types of Behavior of the Model

Russian Physics Journal - On the basis of a qualitative and numerical analysis of a cosmological model based on an asymmetric scalar doublet of nonlinear, minimally interacting scalar fields...     

混凝土HJC模型抗侵彻参数敏感性数值模拟研究

 混凝土是一种应用广泛的复合材料,其动态性能及抗侵彻毁伤效应的研究越来越依赖于数值模拟,其中混凝土HJC模型是应用最广泛的本构模型之一。在介绍HJC模型的基础上,应用LS-DYNA数值模拟方法进行HJC本构模型抗侵彻性能的参数敏感性研究,通过大量数值模拟得出HJC模型的抗侵彻敏感参数有：无侧限单轴抗压强度f_c、压实点压力p_lock、特征化粘性强度A、特征化压力硬化因子B和压力硬化指数N。在混凝土的抗侵彻数值模拟过程中,重点是确定敏感参数的取值,以提高数值模拟的精度和质量,做到合理地选择试验方法和安排试验量。     

Unpolarized Fragmentation Function for the Pion and Kaon via the Nonlocal Chiral-Quark Model

In this talk we present our recent studies for the unpolarized fragmentation functions for the pion and kaon, employing the nonlocal chiral quark model, which manifests the nonlocal interaction between the quarks and pseudoscalar mesons, in the light-cone frame. It turns out that the nonlocal interaction produces considerable differences in comparison to typical local-interaction models.     

Layered Superconductor in a Magnetic Field: Breakdown of the Effective Mass Model

JETP Letters - We theoretically study the upper critical magnetic fields at zero temperature in a quasi-two-dimensional (Q2D) superconductor in the parallel and perpendicular fields,...     

激光与靶相互作用体汽化模型的数值计算方法

利用克劳修斯-克拉珀龙(Clausius Clapeyron)方程描述相变过程,利用von Neumann差分方法构造辐射流体动力学方程组的计算方法,数值求解了激光辐照金属材料的热效应、汽化过程和激光维持爆震波,并同作者前期的工作作了比较.结果说明,该计算方法对激光与靶材料相互作用体汽化模型的数值计算是行之有效的,且该汽化模型为相关问题的二维、三维问题的数值计算提供了简便有效的途径.