A Study on the Strength Surplus Coefficient of Cement

This study considers P.O42.5 cement from different sources and evaluates the related surplus coefficient(defined as the proportionality factor linking the measured compressive strength value of the cement after 28 days to the“standard”value of cement strength).The needed tests have been conducted using a mixer,a pressure testing machine,a flexural testing machine,a vibrating table a ramming rod,a feeder and a metal ruler.The average value of the measured cement strength surplus coefficient of cement produced by five distinct cement manufacturers has been found to be 1.16.These results can be used as the basis to reduce the production cost and improve the performance of commercial concrete.

中国国际收支双顺差与货币供给动态关系:1994-2007——基于抵消系数和冲销系数模型的分析

文章采用1994～2007年的季度数据计量检验了基于抵消系数和冲销系数模型的中国国际收支双顺差与央行货币供给动态关系，采用递归参数方法估计了中国的动态冲销系数，并讨论了央行冲销政策工具的有效性，得出结论：自2001年以来，央行净国外资产的增加成为国内流动性过剩的绝对重要来源；2004年以来，我国央行的冲销系数发生了结构性变化，2004年前维持在一0.6左右，2004年后央行的冲销干预接近于完全冲销（-1），这在一定程度上保证了货币供给的独立性，实现了货币政策的数量目标；受限于利率尚未市场化、资本市场不发达等影响，央行票据成为冲销流动性的最重要工具，法定存款准备金率成为央行常规工具，且还具有一定的操作空间。