震后重建推进住宅产业化模式研究

技术和经济相结合,先采用有限元软件建立了典型多层轻钢结构模型,通过计算分析了抗震性能、较优跨度和经济用钢量。再将该模型的全寿命周期成本与传统住宅造价进行比较分析,旨在为灾后重建以及住宅产业化的推广提供参考。     

输油管布局的优化模型

根据多元函数求最值的方法,运用数形结合的思想,巧妙解出了问题最优解的解析式,并针对不同情况,给出了管线的铺设方案和最低费用.     

中强钢断裂韧性和冲击功关系的研究

测试50Mn中强钢880℃淬火不同温度回火后的力学性能,探讨断裂韧性JIC与V型缺口冲击功AKV和预裂纹冲击功AE 之间的关系,认为JIC与AE之间有较好的线性关系.     

双辊铸轧高速钢薄带退火制度的实验研究

文章主要介绍了双辊铸轧W9Mo3Cr4V高速钢薄带的退火实验。通过实验的研究找出了铸轧高速钢薄带合理的退火工艺制度。     

视讯业务新热点--视频会议系统

视频会议系统集语音、数据、图像为一体，可帮助相隔千里之外的人们实现面对面的实时沟通，它分为软件视频会议系统和硬件视频会议系统。硬件视频会议系统价格昂贵，但稳定性强，视频质量可靠；软件视频会议系统价格低廉，实现方便，易于升级维护，是视频会议系统今后的发展方向。     

难加工材料的切削加工及刀具材料的选用

随着科学技术的发展和机加工工艺水平的提高,不锈钢、淬火钢、高温合金钢等特殊材料在生产中的应用越来越广泛。难加工材料的切削加工效果与切削刀具材料的合理选用有着密切的关系。正确选用合适的切削刀具材料,合理选择加工规范,对提高工作效率,改善加工工艺性,更好的适应机械制造生产需求具有重要的意义。     

In and out of the STEM pipeline – a longitudinal study of a misleading metaphor

ABSTRACT

The metaphor of the leaking pipeline is sometimes used to suggest that some students are lost for STEM as they advance through the educational system. This paper follows a cohort of upper-secondary school students with an interest in STEM from 18 months before their completion of upper-secondary until three years after their completion. Adopting a mixed-methods design, it follows the students' reflections and interests concerning their choice of higher education programme within and/or outside STEM. Only 22% of the students expressed the same interest during the whole period, and 56% changed between different groups of studies, e.g. between STEM and HEALTH. The students' trajectories showed that the leaking-pipeline metaphor is misleading because it suggests a linear and one-way movement, while there were students moving in as well as out of STEM trajectories. The students’ reflections showed identity issues at the level of ego identity, the personal identity and the social identity (Coté and Levine). Particular incidents in the students’ lives and in the outreach programme they were involved in sparked interests and reflections. These incidents should be considered as elements in a continuous reflection concerning who they are and where they would like to go rather than as critical moments.     

两系粳杂70优04高产制种技术

通过对两系杂交粳稻 70优 0 4制种实施“父本栽插苗数”、“父母本栽插行比”、“生物激素使用”和“父本偏施氮肥”四项试验 ,明确了该组合制种父本适宜栽插苗数为穴栽 2粒种子苗 ,行比以 2∶1 2为宜 ,九二○最佳用量为 2 40 g/hm2 。分析了父本适当偏施氮肥应注意的问题     

刚玉类砂轮对轴承钢工件磨削表面质量的影响

针对生产中存在的轴承钢工件淬火处理后磨削表面质量不易保证这一实际问题,分别使用刚玉系列的几种砂轮磨削淬火轴承钢工件,测量出了工件表层的显微硬度、表面粗糙度和波纹度,并且以此来评定了各种刚玉砂轮磨出的工件表面质量的状况。同时,在每种砂轮的磨削过程中,还测量了磨削力、砂轮表面形貌和磨损的变化情况,分析了各种刚玉砂轮影响轴承钢工件磨削表面质量的机理。