强激光加载铝材料动态损伤特性及其微介观结构观测

在神光-Ⅱ装置上利用强激光加载铝材料进行高应变率（高于106 s-1）层裂实验,研究不同初始温度下高纯铝材料的动态损伤特性。采用任意反射面速度干涉仪测量样品自由面速度剖面,由自由面速度剖面计算纯铝样品层裂强度与屈服应力。结果表明:随着温度升高,材料层裂强度减小,屈服应力增大。对激光加载前后样品进行金相分析,观察不同初始温度下纯铝材料的微介观结构变化及其损伤特性。结果表明：随着温度升高,样品晶粒尺度缓慢增大,但在873 K（近熔点）时晶粒尺度急剧增加;层裂面附近小孔洞数目较多,孔洞尺寸也较大,而远离层裂面处,孔洞数目相对较少,且尺寸也较小;材料的断裂方式随温度升高由沿晶断裂为主逐渐变为穿晶断裂为主。     

Dependence of enhanced Kerr nonlinearity on coupling power in a three-level atomic system

We study the enhanced Kerr-nonlinear coefficient in a three-level A-type atomic system for various coupling-beam powers. The Kerr-nonlinear coefficient behaves very differently in the strong and the weak coupling power regions and changes sign when the coupling or probe frequency detuning changes sign. Comparisons of Kerr-nonlinear coefficients as functions of probe frequency detuning, coupling power, and coupling frequency detuning are presented.     

应用微机数模转换接口控制小直流电机的转速

介绍了采用微机数模转换器接口技术实现对小直流电机转速控制的实验方案，并对实验结果进行了讨论．     

Effects and Corrections for Mobile NMR Measurement

Nuclear magnetic resonance (NMR) under motion has drawn significant attention in recent years. Motion of the NMR probe has serious effects on NMR measurement. For example, NMR logging normally runs at downhole condition with tool motion at a speed of 30 ft/min. We propose here methods for motion corrections of NMR data based on the quantitative analysis of motion effects on polarization and echo acquisition. We also produced a multi-functional NMR scanning system to verify the theoretical analysis. Presented experiments demonstrate that the theoretical and experimental results match very well.     

Multifractal Analysis of Dimension Spectrum in Non-uniformly Hyperbolic Systems

Mediterranean Journal of Mathematics - We study the multifractal analysis of dimension spectrum for almost additive potentials in a class of one-dimensional non-uniformly hyperbolic dynamic systems.     

A Note on the Uniqueness of Koebe–Andreev–Thurston Theorem

In this paper, we present a new proof of the uniqueness of Koebe-Andreev-Thurston theorem. Our method is based on the argument principle in complex analysis and reviews the connection between the circle packing theorem and complex analysis.     

A decomposition-related throughput property of tandem queueing networks with blocking

A general throughput property of tandem queueing networks with blocking that relates existing decomposition methods to throughput bounds is discussed using the sample path approach.     

Crystal structure,dielectric and piezoelectric properties of Ta/W codoped Bi3TiNbO9 Aurivillius phase ceramics

Aurivillius phase Bi₃Ti_1−xTa_xNb_1−xW_xO₁₂ high temperature piezoceramics were prepared by a conventional solid state reaction method. The crystal structure, dielectric, electrical conduction and piezoelectric properties were systematically studied. Pure or modified Bi₃TiNbO₉ ceramics revealed the presence of only two-layered Aurivillius phase, indicating that Ta/W doping entered into the B-site of pseudo-perovskite structure and formed solid solutions. The Curie temperature had a strong reliance on the structural distortion. Furthermore, Ta/W dopants act as a donor doping, decrease the number of oxygen vacancies and facilitate the domain wall motion. As a result, Ta/W modifications significantly increase the DC resistivity and piezoelectric properties. Bi₃Ti_0.98Ta_0.02Nb_0.98W_0.02O₁₂ ceramics possess the optimum d₃₃ value (∼12.5 pC/N) together with a high T_C point (∼893 °C). Moreover, the resonance–antiresonance spectra demonstrate that the Ta/W-BTN ceramics are indeed piezoelectric in nature at 600 °C. The d₃₃ value of BTTNW-2 ceramic remains ∼12.2 pC/N after annealing at 700 °C. These factors suggest that the BTTNW-based ceramic is a promising candidate for ultra-high temperature sensor applications.     

Focused ion beam fabrication and magneto-electrical transport properties of La0.67Ca0.33MnO3 nanobridge

La_0.67Ca_0.33MnO₃ particle films with an average particle size of ~150 nm were grown on single-crystal silicon substrate using pulsed electron deposition technique and then focused ion beam was introduced to fabricate nanobridge in size of 300 × 900 nm on the particle film. The magneto-transport properties of both samples were studied. For the film, there is only one resistance peak at 182 K in temperature-dependent resistance (R–T) curves, which is far lower than ferromagnetic–paramagnetic transition temperature (T _C) of 250 K. When compared to the film, double peaks were observed in both R–T curves and magnetoresistance dependent on temperature (MR–T) curves of the nanobridge, one peak is at 186 K, which is very close to metal–insulator transition temperature (T _P) of film, the other one is at 250 K, which is close to the T _C of film, and these two peaks caused separately by grain and grain boundary (GB), which demonstrated that the electrical transport behavior of grain was separated from that of GB.     

The impact of human activity patterns on asymptomatic infectious processes in complex networks

The study of the impact of human activity patterns on network dynamics has attracted a lot of attention in recent years. However, individuals’ knowledge of their own physical states has rarely been incorporated into modeling processes. In real life, for certain infectious processes, infected agents may not have any visible or physical signs and symptoms; therefore, they may believe that they are uninfected even when they have been infected asymptomatically. This infection awareness factor is covered neither in the classical epidemic models such as SIS nor in network propagation studies. In this article, we propose a novel infectious process model that differentiates between the infection awareness states and the physical states of individuals and extend the SIS model to deal with both asymptomatic infection characteristics and human activity patterns. With regards to the latter, we focus particularly on individuals’ testing action, which is to determine whether an individual is infected by an epidemic. The simulation results show that less effort is required in controlling the disease when the transmission probability is either very small or large enough and that Poisson activity patterns are more effective than heavy-tailed patterns in controlling and eliminating asymptomatic infectious diseases due to the long-tail characteristic.