喷射沉积Al-Zn-Mg-Cu合金GP区应变场的定量测试

为定量测试喷射沉积合金GP区周围的晶格应变的分布,利用喷射成形技术制备了Al12Zn2.4Mg1.1Cu合金。随后对合金进行热挤压、758K固溶2小时和393K时效20小时处理。利用高分辨透射电子显微镜(High Resolution Transmission Electron Microscopy,HRTEM)和几何相位分析(Geometric Phase Analysis,GPA)软件对GP区的结构和应变场进行了测量和分析。结果表明,GP区附近的应变值在各方向差别较大,沿GP区惯习面法线方向的应变最大(εxx=-0.092),与惯习面平行方向上的应变最小(εyy=-0.004)。该项结果可解释GP区附近位错运动的差异:由于应变场在各方向上存在较大差别,产生的应变强化效果不同,导致阻碍位错运动的能力也有所不同。     

Exact Temporal Evolution of Two-Species Bose–Einstein Condensates

We construct exact stationary solutions to the one-dimensional coupled Gross–Pitaevskii equations for the two-species Bose–Einstein condensates with equal intraspecies and interspecies interaction constants.Three types of complex solutions as well as their soliton limits are derived.By making use of the SU(2)unitary symmetry,we further obtain analytical time-evolving solutions.These solutions exhibit spatiotemporal periodicity.     

盐酸替罗非班的合成

以L-酪氨酸为原料,经过酯化、磺酰化、mitsunobu反应、水解、催化氢化等几步反应制得盐酸替罗非班,目标产物的化学结构经1H-NMR、IR、MS等确证,总收率为33%。     

Matter wave interference pattern in the collision of bright solitons

We investigate the dynamics of Bose–Einstein condensates in a quasi one-dimensional regime in a time-dependent trap and show analytically that it is possible to observe matter wave interference patterns in the intra-trap collision of two bright solitons by selectively tuning the trap frequency and scattering length.     

Optimization of probabilistic multiple response surfaces

Response surface methodology (RSM) is a statistical-mathematical method used for analyzing and optimizing the experiments. In analysis process, experts usually face several input variables having effect on several outputs called response variables. Simultaneous optimization of the correlated response variables has become more important in complex systems. In this paper multi-response surfaces and their related stochastic nature have been modeled and optimized by Goal Programming (GP) in which the weights of response variables have been obtained through a Group Decision Making (GDM) process. Because of existing uncertainty in the stochastic model, some stochastic optimization methods have been applied to find robust optimum results. At the end, the proposed method is described numerically and analytically.     

Reversible nonlinear conduction behavior for high‐density polyethylene/graphite powder composites near the percolation threshold

The reversible nonlinear conduction (RNC) behavior of high‐density polyethylene/graphite powder composites with various graphite powder volume concentrations slightly above the threshold has been studied. The relationships between the current density (J) and electric field (E) of the composites, as shown in J(E) curves, can be well described by the scaling functions of J/J_c ～ (E/E_c) when E < E_c and J/J_c ～ (E/E_c) when E > E_c, where J_c is the crossover current density and E_c is the crossover electric field. The results indicate that J_c scales with the linear conductivity σ₀ as J_c ～ σ. It is believed that the macroscopic RNC is a combined result of the microscopic conduction processes, involving electronic transporting along carbon chains and tunneling or hopping across thin polymer bridges. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2833–2842, 2001     

Contribution of the Guinier-Preston zones to the hardening of Al-5%Ag alloy and its photo-electrochemical protection in seawater using n-CdS

The contributions of the GP zones and the matrix to the alloy hardening have been studied in the alloy Al-5% at. Ag aging at 150 °C. They were determined separately using a method based on the hardness measurement which obeys the relation ΔHv_SS = 19.72x^2/3 + 0.218 (Gpa), where x is the means atomic concentration of the matrix. The GP zones follows the relationship (ΔHv _GP = 18.4 f_v^0.94 kg/mm²), f_v is the volume fraction of GP zones. In a second part, the photo-electrochemical properties of n-CdS were exploited for the cathodic protection of the alloy Al-5% at.Ag in one of the most corrosive environments namely seawater. The corroded surface was rough and the corrosion product contains divided particles. However, the corrosion was significantly hindered by contacting the alloy to n-CdS (E_g = 2.40 eV) irradiated by visible light with different intensities (42–103 mW cm^-2). Under illumination, the electrode potential of the alloy is cathodically shifted when short-circuited to n-CdS, indicating a photo cathodic protection while the corrosion current falls from 2.67 (in the dark) down to 1.73 mA cm^-2 under a light flux of 103 mW cm^-2. Conversely, when the alloy is short-circuited to p-type CuO (E_g = 1.46 eV), the corrosion current increased by 26% under illumination, due to the activated dissolution by photoholes.     

Nonlinear Waves in a Cigar-Shaped Bose-Einstein Condensate with Dissipation

We discuss the possible nonlinear waves of atomic matter waves in a cigar-shaped Bose-Einstein condensatewith dissipation. The waves can be described by a KdV-type equation. The KdV-type equation has a solitary wave solution. The amplitude, speed, and width of the wave vary exponentially with time t. The dissipative term of ~/ plays an important role for the wave amplitude, speed, and width. Comparisons have been given between the analytical solutions and the numerical results. It is shown that both are in good agreement.     

激光选区熔化增材制造GP1不锈钢动态拉伸力学响应与层裂破坏

采用选择性激光熔化增材制造技术,制备了GP1不锈钢单轴拉伸板条试样和层裂圆片试样,并对材料微观结构进行了表征。借助Zwick-HTM5020高速拉伸试验机,并结合数字图像相关性全场应变测量技术,开展了增材制造GP1不锈钢材料的轴向拉伸力学性能实验研究,得到了不同应变率下材料的拉伸应力-应变曲线,结果显示:(1)GP1不锈钢流动应力具有比较显著的应变强化效应;(2)通过回收试样的电子背散射衍射表征,发现GP1不锈钢在拉伸变形过程中会发生奥氏体与马氏体之间的相变;(3)GP1不锈钢的屈服应力随着应变率呈幂指数增大,断裂应变在中低应变率下保持不变,但在高应变率下则显著减小。采用一级轻气炮实验装置和激光干涉粒子速度测量技术,开展了增材制造GP1不锈钢的层裂实验,发现GP1不锈钢的层裂强度随着飞片撞击速度增大而减小。单轴拉伸试样断口和层裂试样断口的显微分析结果表明:随着应变率增大,单轴拉伸断裂模式和断裂机理都发生了转变;层裂损伤易成核于激光熔池边界线的交汇处,断口韧窝形貌明显区别于单向拉伸断口。