Analysis on Observing Results ofVacuum Degree in Soft Groundby Vacuum-Surcharge Preloading

This paper analyzes the observing results of vacuum degree in the the Jialichen bridge-head experimental site .The cause of vacuum degree developing below groundwater table is pointed out. The influence of vacuum degree above the ground water table on pore water pressure is discussed. The results show that vacuum degree decreases along the depth because resistance. The resistance in the PVDS is lowest, in the silt is highest. Vacuum degree below groundwater table is produced mainly by dewatering or by escaping of sealed air from the end of flexible pipe. Vacuum degree above the ground water table in the sand drains makes great effect on pore water pressure. In the silt the pore water pressure does not change with the variation of vacuum degree under membrane in a short time.

国家高新区产业积聚度的测算与分析

单独对国家高新区或产业集群的研究已经很多,但用产业集群的思想和理论研究国家高新区产业积聚度的文献却很少。本文首先回顾产业集群测算的常用方法,然后根据高新区的产业特点和测算目的,选择并修正了产业集群的识别方法——区位熵系数法LQ(Location Quotient)。随后,分四步对高新区产业集聚度进行测算:1)选定测算聚集度的产业范围;2)明确四类测算产业的权重;3)计算产业积聚度;4)采用0-1方法处理,并排序。最后,根据积聚度的计算结果,把高新区分为四个等级,在每个等级中选择比较典型的高新区,重点分析影响高新区排序的相关因素。

基于砂支撑FDM 3D打印的堆砂规律研究

将颗粒(后面统称砂粒)作为3D打印的支撑材料,避免了传统3轴FDM中因去除支撑而损伤工件的后果。为了归纳出该新型FDM 3D打印技术中的堆砂规律,首先采用Plackett-Burman设计物理实验,选取漏斗孔径X_(1)、漏斗高度X_(2)、漏斗水平移动速度X_(3)以及玻璃砂尺寸X_(4)为参数,研究了砂粒的堆积角规律,其次通过DEM仿真分析了不同漏斗孔径下的砂粒的聚集程度变化。结果表明,参数X_(1)和X_(3)显著影响堆积角,且影响为负效应。随着漏斗孔径的增大,砂粒聚集程度提高。因此在砂作支撑的FDM 3D打印中,增大漏斗孔径可以达到抑制砂道堆积角,提高砂粒堆积聚集性的效果,从而提高工件成型质量。