Research and implementation of cooperative cache for PVFS

At present, there are many effective ways to achieve high performance in cluster system storage management, including server-end disk, server-end caching, local caching and cooperative caching. The cooperative caching mechanism shares caches among different clients so as to avoid expensive disk access costs and to improve overall throughput of cluster system. In this paper, a Single Copy Cooperative Cache model is proposed together with block lookup algorithm, block replacement algorithm and the consistency algorithm based on the model. Meanwhile, the prototype system of the model is implemented in PVFS file system. Finally, the performance of this system is tested in InfiniBand Framework, the result of which shows that in contrast to the original PVFS system, read performance of PVFS file system is improved by about two times, while write performance is reduced by nearly ten percent.     

基于遗传算法收敛特性的停机准则

关于遗传算法及改进遗传算法收敛问题的研究表明,理论上分析各类不同结构遗传算法的收敛性是可行的.对已被证明收敛的遗传算法,在计算过程中最突出的问题便是如何判断当前计算结果已经到达最优解从而停止迭代.文中从遗传算法收敛特点及不同种群中最优个体适应值的一致性、种群的多样性出发,提出判断算法自动停止迭代的依据.     

Management considerations for accreting shorelines

Abstract

Natural coastal accretion in the United States occurs at river mouths, spits across embayments, inlets, capes and cuspate forelands, and pocket beaches. Human‐induced accretion occurs updrift of groins and jetties, landward of breakwaters, and in locations which are artificially nourished. Coastal accretion is usually temporary (years to tens of years). Erosion may occur due to deflection of streams and tidal current channels or to changes in sea level, weather patterns, or sediment budgets. A focus on ownership disputes or use of accreted land draws attention away from the long‐term problem of the development of land which may be subject to future erosion. Control mechanisms should be in place to direct development on accreting shorelines to make more effective use of the resource.     

浅谈混凝土减水剂之减水率测定方法的实际应用

通过测定掺减水剂水泥净浆标准稠度的方法来计算减水剂的减水率,为按GB 8076-2008标准测定减水剂减水率提供一种简捷的估算依据,从而快速判断混凝土减水剂的减水率以及和水泥的适应性问题,较好地配合混凝土配合比设计,以降低做配合比时劳动强度。     

双缸推动型船舶电动舵机的同步控制技术

为解决当前液压伺服操控滞后、精度不足等缺点,提出了基于双交流同步伺服电机的船舶电动舵机操控模式,并给出了实现其一致性操控方法,最后通过采用原理样机操控方法对系统的精确性与有效性进行了验证,结果显示该双摆缸同步操控模式及其一致性控制方法已具备了实船装配的工程基础与工程价值。     

大型空间桁架制作安装技术

简要介绍了上横梁吊装方案的比选,重点介绍了某斜拉桥主塔上横梁大型空间桁架结构的加工、运输、吊装等关键施工技术,并进行了安全性检算。实践证明,运用上横梁连续千斤顶悬吊安装方案,切实解决了无支撑大吨位钢横梁高空吊装及对位焊接难题,可为类似工程提供借鉴。     

宇通客车用松芝空调器控制面板接口功能及检测

介绍宇通客车用松芝空调器控制面板接口每个引脚的功能接线及检测方法。     

轴向力逼近法在圆形截面偏心受压构件承载力复核中的应用

介绍了圆形截面偏心受压构件正截面承载力复核的轴向力逼近法,和传统算法相比,该方法更直观易懂,逼近目标明确,计算速度更快些。     

汽车废气自动检测技术与研究

文中介绍废气分析仪的结构和工作原理,提出了利用废气分析仪检测汽车尾气中的HC及CO含量,并对测量数据进行分析,判断出电子燃油喷射发动机产生断缸的故障。     

桥梁支座检测方法的探讨

随着交通基础设施工程建设的飞速发展和公路等级的不断提高,大型互通桥梁、高架桥梁日益增多．支座被广泛地使用于桥梁中。故加强支座的现场检测,提高支座的使用寿命,是保证桥梁质量的关键。