搜索:2007年第一季度利润

仿佛昨天我们还在庆祝2007年的到来,但是,现在又到了我们一起来看看各大科技公司在2007年第一季度的利润成绩单的时候了。     

IBM双机经验谈

随着企业信息系统的普及和整个社会电子商务的发展,现代企业的运作日益依赖于信息技术。越来越多的关键数据被存储在计算机系统中,这些数据的丢失和损坏将对企业造成难以估量的损失。因此企业对于数据可用性的要求也大为提高,因为即使是短时间的系统停机也将造成业务停顿和经济损失。双机容错是计算机应用系统稳定、可靠、有效、持续运行的重要保证。双机热备的目的在于保证数据永不丢失和系统永不停机。本文以IBM双机为例,结合作者的经验,对双机系统的细节展开论述,以便读者更好的理解双机系统。     

Relative Flow Analysis around Passing-Train in the Single-Bore Subway Tunnel with Vertical Ventilation Using Moving IBM

Moving IBM （immersed boundary method） is applied to analyze the relative motion of railway car flow in the single-bore subway tunnel with vertical ventilation. The tested car body is modeled by cylinder type body. The subway tunnel is assumed to be the single-car-passing straight type （single-bore tunnel）. The modeled car is relatively moved forward. On the other hand, the tunnel and vertical ventilation are fixed. The momentum equations are solved by LES （large eddy simulation） method. The initial condition of fluid in the subway tunnel is stationary. The Reynolds number is 1,500 based on the cylinder radius. The turbulent flow field in the subway tunnel and vertical ventilation shaft are to be qualitatively investigated.     

从UNIX到IBM主机系统的程序移植探讨

本文介绍了UNIX平台与IBM主机系统平台之间的差异,并对跨平台移植过程中应考虑的主要问题和解决方法进行了探讨。     

Linux日志文件系统故障处理策略的研究

研究了三种广泛应用的Linux日志文件系统Ext3、ReiserFS和IBMJFS在磁盘写失效情况下的故障处理机制,分析了它们在处理磁盘写失效时存在的设计不足,并对文件系统磁盘故障处理的改进进行了总结和研究。     

Immersed-boundary/soft-sphere method for particle–particle-fluid interaction in a viscous flow: An OpenFOAM solver

We developed a stable OpenFOAM solver for Immersed Boundary Method based on direct forcing and regularized delta function. The soft-sphere model and a lubrication model were implemented to consider particle–particle collision in a viscous flow. We proposed a fluid–structure interaction (FSI) coupling method to accurately calculate the fluid forcing term and particle velocity. Our solver was validated for fixed and moving bodies, including rotation. The accuracy of various FSI schemes was evaluated in predicting the solid and fluid flow behavior in a viscous flow. It was demonstrated that neglecting or simplifying the fluid momentum change affects the accuracy of the solid velocity and fluid flow dynamic; for higher solid-to-fluid density ratios, a larger deviation was predicted. Furthermore, the FSI schemes highly influenced the behavior of the formed vortices.The solver was validated to predict the effective restitution coefficient of particles in a viscous flow as a function of the Stokes number. We also thoroughly analyzed the dynamic flow behavior of colliding particles through the pressure and velocity field and fluid force. This analysis helped us accurately determine the rebound velocity of particles in case of high Stokes numbers when the effect of viscous force is significant.     

汉英统计机器翻译中A*搜索算法研究与实现*

分析了基于IBM Model 4的A*搜索算法和启发函数，由于仅靠启发函数难以找到最优译文，因此在搜索中采用了部分宽度搜索，以扩大搜索的范围。将该算法应用于汉英统计机器翻译中，实验结果表明改进后的算法获得了较好的翻译质量和效率。