Monte-Carlo simulation of surface crack growth rate for offshore structural steel E36-Z35

The Monte- Carlo method is used to simulate the surface fatigue crack growth rate for offshore structural steel E36-Z35, and to determine the distributions and relevance of the parameters in the Paris equation. By this method, the time and cost of fatigue crack propagation testing can be reduced. The application of the method is demonstrated by use of four sets of fatigue crack propagation data for offshore structural steel E36-Z35. A comparison of the test data with the theoretical prediction for surface crack growth rate shows the application of the simulation method to the fatigue crack propagation tests is successful.

Growth of Silicon Carbide Bulk Crystals by Physical Vapor Transport Method and Modeling Efforts in the Process Optimization

Silicon carbide bulk crystals were grown in an induction-heating furnace using the physical vapor transport method. Crystal growth modeling was performed to obtain the required inert gas pressure and temperatures for sufficiently large growth rates. The SiC crystals were expanded by designing a growth chamber having a positive temperature gradient along the growth interface. The obtained 6H-SiC crystals were cut into wafers and characterized by Raman scattering spectroscopy and X-ray diffraction, and the results showed that most parts of the crystals had good crystallographic structures.

Formation Of Dendritic Nanostructures In Pyrex Glass Anodically Bonded To Silicon Coated With An Aluminum Thin Film

Anodic bonding with thin films of metal or alloy as an intermediate layer, finds increasing applications in micro/nanoelectromechanical systems. At the bonding temperature of 350 degrees C, voltage of 400 V, and 30 min duration, the anodic bonding is completed between Pyrex glass and crystalline silicon coated with an aluminum thin film with a thickness comprised between 50 and 230 nm. Sodium-depleted layers and dendritic nanostructures were observed in Pyrex 7740 glass adjacent to the bonding interface. The sodium depletion width does not increase remarkably with the thickness of aluminum film. The dendritic nanostructures result from aluminum diffusion into the Pyrex glass. This experimental research is expected to enhance the understanding of how the depletion layer and dendritic nanostructures affect the quality of anodic bonding. (C) 2007 Elsevier B.V. All rights reserved.

纳米铜团簇扩散性质研究

本文通过分子动力学模拟研究了纳米铜团簇的自扩散性质,结果表明Nc8949铜团簇自扩散系数随温度的升高而增大,在温度为1000 K时纳米铜团簇的扩散系数随团簇半径的倒数基本呈线性增加.同时指出在常温下团簇几乎无扩散行为,而某些文献中关于常温下晶粒扩散分子动力学模拟结果是模拟体系宏观转动造成的虚假现象.

第24届国际激波学术会议简介

国际激波学术会议（International Symposium on Shock Waves,ISSW）是国际上激波研究领域的重要系列学术会议.从1957年第一届会议在美国波士顿召开起,每隔两年召开一次,至今已召开24次.

加卸载响应比理论用于矿震预测的初步研究

加卸载响应比(LURR)理论是～种前景很好的中期地震预测方法，通常在强烈地震发生前的数月至l～2年I．URR出现高值，因而I。URR可以作为强烈天然地震的前兆，用此方法曾经成功地预测过Northridge地震(1 994年1月17日，M6．7，美国加州)，Nanto地震(1 996年9月11日，M6．6，日本)及不少发生在中国的天然地震。用房山煤矿1 992年8月至1993年7月的微震资料,计算了全年内7组M>2．1矿震前的加卸载响应比γ值，其中5组矿震前γ值均明显大于l(γ≥2 9)。以上结果表明，加卸载响应比理论有可能用于矿震的预测。

Performance of a small high-speed liquid jet apparatus

The performance of a small high-speed liquid jet apparatus is described. Water jets of 200m/s to 700m/s have been obtained by firing a deformable lead slug from an air rifle into a stainless steel nozzle containing water sealed with a rubber diaphragm. Nozzle devices of using the impact extrusion (IE) method and cumulation (CU) method are designed to generate jets. The injection sequences are visualized using schlieren photography. The difference between the IE and CU methods in the jet generation is found.

Formation of dendritic nanostructures in Pyrex glass anodically bonded to silicon coated with an aluminum thin film

Anodic bonding with thin films of metal or alloy as an intermediate layer, finds increasing applications in micro/nanoelectromechanical systems. At the bonding temperature of 350 degrees C, voltage of 400 V, and 30 min duration, the anodic bonding is completed between Pyrex glass and crystalline silicon coated with an aluminum thin film with a thickness comprised between 50 and 230 nm. Sodium-depleted layers and dendritic nanostructures were observed in Pyrex 7740 glass adjacent to the bonding interface. The sodium depletion width does not increase remarkably with the thickness of aluminum film. The dendritic nanostructures result from aluminum diffusion into the Pyrex glass. This experimental research is expected to enhance the understanding of how the depletion layer and dendritic nanostructures affect the quality of anodic bonding. (C) 2007 Elsevier B.V. All rights reserved.

高压深层裂缝性油气藏中不定常渗流的数值研究

根据实验结果和裂缝性压力敏感地层的特性,建立了适合于不同外边界条件下裂缝性压力敏感地层的不定常渗流模型.推导出了裂缝性压力敏感地层的不定常渗流模型的有限元方程.在对区域进行非结构化网格自动划分的基础上,利用有限元计算方法计算出了无限大地层、圆形有界地层以及线性组合边界地层的裂缝性压力敏感地层的井底压力的理论曲线,并对理论曲线特征进行了分析和对比.确定了压力敏感系数以及有效井径组合参数对理论曲线的影响,得到了确定压力敏感油气藏的地层参数的方法.通过某气田高温高压深层气井的实例分析,得到了较好的分析结果,同时也验证该文所建立的裂缝性压力敏感地层的不定常渗流模型的正确性.

激光光束实时监测与自动准直系统设计

设计了一个激光光斑实时监测与光路自动准直装置,能够实时监测激光光斑并自动准直激光输出方向。基于透镜成像原理,使用CCD探测器获得光斑的二维成像,并根据两点确定一条直线原理和使用压电陶瓷电动调整架实现光路自动准直;监测控制程序采用虚拟仪器开发软件Lab View编写,可以实时监测激光光斑模式与光斑位置抖动情况,并进行反馈控制。经测试,设计装置的调整精度达0.5μrad,反馈控制频率约1 Hz,完全可降低或消除抖动周期在1 s以上的光斑飘移。

Fabrication of microfluidic optical waveguides on glass chips with femtosecond laser pulses

We describe the fabrication of microfluidic channel structures on the surface of a borosilicate glass slide by femtosecond laser direct writing for optical waveguide application. Liquid with a variable refractive index is fed into the microchannel, serving as the core of the waveguide. We demonstrate that either a multimode or a single-mode waveguide can be achieved by controlling the refractive index of the liquid. (C) 2007 Optical Society of America