Experimental Study on Flow and Sediment Movement in Cavity Circulations

This paper reports a flume experiment of flow and sediment movement in a cavity. The flow velocity, sediment concentration and the mechanism of hydraulic sorting in the circulation flow are discussed. The quantity and patterns of sediment deposition in the circulation area are studied as well.

海洋平台动力分析的一个简化方法

本文提供了一个分析结构——基础耦合响应的简化方法。用SAPV计算上部固端悬臂结构后,将它变换为一个随频率变化的等价刚性质量,使问题简化为位于柔性基础上的刚体振动问题。用本法计算了一个简化的平台模型的随机响应。

二维扫描法测量连续型激光器的远场分布

<正>本文提出用二维扫描法测量连续型激光器远场分布.其原理是:被测激光束先经衰减器将功率密度衰减至10~(-2)～10~(-4)瓦/(厘米)~2然后经聚焦镜及平镜反射,聚焦于扫描筒内壁之上,扫描筒壁上有一系列螺旋状分布小孔,各相邻两孔间夹角及轴向距离都相同,首末两孔间轴向距离及相邻两孔圆心间弧线在圆筒横截面上的投影长度均应稍大于欲测光斑直径,当圆筒用电动机带动旋转时,各小孔依次扫过光斑.透过小孔的光线用聚焦镜会聚于探测器上,探测器输出信号经放大器放大后由示波器记录,经整理后可得到“三维”远场分

The plastic instability behaviour of laser-textured steel sheet

As the production of a new technique that can offer both good formability and high image clarity for texturing metal sheet, laser-textured sheet has attracted the attention of many manufacturers and users. Among the many subjects to be studied, plastic instability behaviour of the laser-textured sheet is one of most important to understand its ability in extending material ductility and to appropriately control this technique. Experimental investigations are carried out in this paper to study the macroscopic behaviour and microstructural mechanism of the laser-textured sheet, and comparison is made with the normal sheet taken from the same coil of metal sheet. It is demonstrated that, the difference in the behaviour of plastic instability obviously shows tendency to delay strain localization and the onset of thickness necking. Shear banding and internal void damage are spread to a much wider region in the sheet being laser-textured. The prestrained microcraters enforced on the surface of the textured sheet act as hardening spots, which are likely to share out deformation and inhibit the increasing rate of voiding, and eventually favouring the ductility of the material used.

激光毛化技术对18-8不锈钢疲劳性能影响的研究

通过模拟分析 ,对激光毛化 18 8不锈钢的疲劳寿命与毛化覆盖率的关系进行研究 ,预测结果与相关实验结果进行对比。结果显示 ,由于激光毛化处理的影响 ,18 8不锈钢的疲劳寿命得到改善 ,而且在毛化覆盖率为 2 0 %左右时 ,材料疲劳性能最好

用高速阴影技术研究K9玻璃中的失效波

用高速阴影摄影技术研究了爆轰加载下K9玻璃样品中波的传播和压缩区内损伤破坏的物理图象和规律。实验中观测到冲击波阵面后有一个移动速度为2.1mm/μs～2.2mm/μs的黑色阴影区边界，即失效波(Failure wave)；实验发现只有当冲击载荷接近材料的HEL时，在冲击波 和失效波之间的区域才有少量的微裂纹成核和长大，而在冲击载荷较低时却没有观察到；同时实验中观测到失效波萌生于被撞击面，并在两块玻璃的交界面上观测到失效波的再生。这些结果表明失效波的产生基本与冲击相变无关，主要与玻璃样品表面的初始损伤有关。

湍流射流理论与计算

Adiabatic shear localization: occurrence, theories, and applications

Micro-scale Plasticity Mechanics=微尺度塑性力学

本书系统地介绍了材料微尺度力学行为的尺寸效应实验现象，重点介绍了几种代表性的微尺度应变梯度塑性理论及对微尺度实验现象的解释；以及对裂纹尖端微尺度范围内解理断裂的应用。融会贯通的介绍了国内外学者的原创性工作和创新性学术思想。 全书共8章。第1章介绍了应变梯度塑性理论的应用背景及经典微极理论；第2章介绍了金属材料典型的微尺度力学实验现象；第3～7章介绍了几种典型的应变梯度理论及其应用；第8章介绍了应变梯度理论在微观断裂力学中的应用。 本书适合从事固体微尺度力学、先进材料的微结构设计与力学性能优化、微机电和微电子元件力学行为研究的科技工作者及工程师使用和参考，也可供力学专业及材料专业的高年级本科生和研究生阅读参考。

Self-organized generation of transverse waves in diverging cylindrical detonations

Self-organized generation of transverse waves associated with the transverse wave instabilities at a diverging cylindrical detonation front was numerically studied by solving two-dimensional Euler equations implemented with an improved two-step chemical kinetic model. After solution validation, four mechanisms of the transverse wave generation were identified from numerical simulations, and referred to as the concave front focusing, the kinked front evolution, the wrinkled front evolution and the transverse wave merging, respectively. The propagation of the cylindrical detonation is maintained by the growth of the transverse waves that match the rate of increase in surface area of the detonation front to asymptotically approach a constant average number of transverse waves per unit length along the circumference of the detonation front. This cell bifurcation phenomenon of cellular detonations is discussed in detail to gain better understanding on detonation physics.

Electron acceleration by an intense short-pulse laser in underdense plasma

Electron acceleration from the interaction of an intense short-pulse laser with low density plasma is considered. The relation between direct electron acceleration within the laser pulse and that in the wake is investigated analytically. The magnitude and location of the ponderomotive-force-caused charge separation field with respect to that of the pulse determine the relative effectiveness of the two acceleration mechanisms. It is shown that there is an optimum condition for acceleration in the wake. Electron acceleration within the pulse dominates as the pulse becomes sufficiently short, and the latter directly drives and even traps the electrons. The latter can reach ultrahigh energies and can be extracted by impinging the pulse on a solid target. (C) 2003 American Institute of Physics.

轴向为烷氧基配位的萘酞菁硅配合物的光谱及光稳定性

研究了4种轴向为烷氧基配位的萘酞菁硅配合物（NcSi（OR）2，R为CH3、C2H3、C3H7和C4H9）在DMSO、DMF、CH2Cl2中的Q带吸收光谱和光降解动力学及其稳定性。研究结果表明，这4种萘酞菁配合物在相同溶剂中随着轴向配位烷氧基碳链的增长其最大吸收波长逐渐增加，并且在DMSO、CH2Cl2溶剂中随着轴向配位烷氧基碳链的增长光稳定性逐渐增强；对于同一配合物，溶剂对其光稳定性影响顺序为：DMSO〉CH2Cl2〉DMF。