改善20CrMnTiH淬透性的研究

莱钢特钢厂20CrMnTiH钢材成分波动较大,淬透性带HRC8～10,范围较大,制约了齿轮钢质量的进一步提高.通过研究,发现铸坯中心偏析尤其是碳偏析为主要问题.通过工艺优化采取各项措施,尤其增加电磁搅拌后,中心碳偏析得到明显改善;C控制在0.19%～0.20%的炉次达到了95.6%;淬透性带控制在HRC6内的达到了92.1%;在HRC4内的达到了86.2%;提高了产品质量,满足了用户需求.     

The Difference of the Pulmonary-Artery Pressure of the Migrants from Difference Elevation at the 4636 - 4907 m Altitude

Study Objective： To compare and analyze the changes of the pulmonary-artery pressure of the migrants coming from different elevation in the hypoxic environment of 4636 - 4907 m extreme altitude. To explore the susceptibility to hypoxic pulmonary-artery hypertension （PH） in the subjects from different altitude and profession. Methods： By using Color Doppler Ultmsonography （CDU）, measuring the pulmonary-artery pressure of 207 healthy men, who had continuously being lived and worked at the extreme altitude for more than six months, and then were divided into three groups according to their profession and the altitude of original living place. Results： There was a significant difference in the outcomes of pulmonary-artery pressure from the 3 groups. Conclusions： Altitude of original living place, labor intensity are some of factors that impact the pulmonary-artery pressure of the people who exposure to a hypoxic environment. The pulmonary- artery pressure of person without strenuously physical work experience was more sensitive to hypoxic surroundings than that of labor workers. It was not always the fact at an extreme altitude that the moderate altitude mountaineers were superior to other migrants from a lower altitude or plain. The higher PH was found in the groups of the moderate altitude mountaineers and labor workers. It is unlikely certain that one with PH would surfer from HAPE.     

Prof. Zhu Zuoyan Met with the INRA Delegation

Prof. Zhu Zuoyan, Vice President of NSFC, met with the National Institute of Agricultural Research (INRA) delegation led by its Deputy Director General, Prof. Guy Riba on Jan. 18, 2007.     

共轭斜量法在某些特征向量上收敛速度的估计

设 Ａ是对称正定矩阵，λ_1是 Ａ 的最大或最小特征值，χ_1是对应的特征向量．｛zk｝是用共轭斜量法求解方程组 Αχ＝ｂ时的近似解序列，ｅi＝Ａ～(_1)b-zi,本文给出了|x_1～Tei|较合理的上界估计式。从而为分析预处理共轭斜量法提供了进一步的理论基础。     

CGPSS-F仿真系统数据的采集与分析

本文详细地叙述了“医院门诊部为门诊病人服务的CGPSS-F仿真系统”数据采集与分析的方法.利用CGPSS-F仿真系统的驻留在队列中的实体数和资源处于繁忙状态的单元数,合理调整实体在系统的时间.根据资源容量的利用,实体排队的长度和实体在系统的时间,确定实用的系统参数.