Science in China Series B-Chemistry, Life Sciences & Earth Sciences (in Chinese), 1995

Zhongguo kexue, 2011

Chinese Science Bulletin, 2009

SCIENTIA SINICA Terrae, 2014

SCIENTIA SINICA Physica, Mechanica & Astronomica

Dynamic behavior under cyclic loading conditions and creep behavior under quasi-static loading conditions were investigated by instrumented indentation of pure aluminum to reveal the influence of loading conditions (e.g., load, loading rate, and holding time) on indentation responses. The results of cyclic indentation show that, with the increase in the holding time, load, and loading rate of the pre-cyclic loading segment, the effect of creep on the subsequent cyclic indentation can be weakened, and the measured mechanical properties (e.g., contact depth, indentation hardness, and elastic modulus) can reach constant levels more rapidly with the increase in cycle number. The results of the creep tests show that the elastic modulus and indentation hardness decrease with the increase in holding time, the steady-state creep stress exponent obtained by instrumented indentation is independent of load, and a long holding time is not suggested for the creep tests. Indentation hardness and steady-state creep resistance measured within the inner grains are higher than those measured near the grain boundary regions.

2015

北京工业大学学报, 2017

为有效地获取滚珠丝杠副精度寿命特征,利用滚珠丝杠副磨损特征建立加速退化模型,并且根据设计的试验装置和试验过程的摩擦力矩值变化情况,采用参数估计方法进行退化数据的统计分析,获得不同应力水平下的滚珠丝杠副加速退化参数模型.同时,根据不同应力条件下实测的滚珠丝杠副摩擦力矩退化数据,计算出滚珠丝杠副定位反向变动量,为滚珠丝杠副的定位精度退化提供一种新的评价方法.建立的滚珠丝杠副加速退化模型针对其磨损进程极为缓慢的特性,利用该退化方法能较准确地推算出滚珠丝杠副精度寿命,能节约滚珠丝杠副试验费用、试验时间和指导滚珠丝杠副的设计.

Acta Ecologica Sinica, 2014

Seed germination and early seedling growth are the stages in a plant忆s life cycle during which it is most sensitive to environmental stresses. The adaptability of an alien plant at this stage to unfavorable environmental conditions is one of the key factors determining its invasiveness. In this study, experiments were conducted to evaluate the effects of dormancy features, storage time, pericarp, temperature, pH, osmotic stress, salt stress and seed burial depth on seed germination, seedling growth and seedling emergence in Gaura parviflora. Although the four seeds of each capsule were found to differ significantly with respect to weight (P < 0.01) , their vigor and germination rates were similar to one another. Seed vigor was greater than 96%, and germination was higher than 98% after release from dormancy. The pericarp of G. parviflora affected seed germination via physical obstruction, and was the major cause of seed dormancy. After storage at room temperature, G. parviflora seed germination initially increased; at longer storage times, however, it decreased. Prior to

Zhong guo ke xue, 1993