零间隙压气机失稳机理的全通道数值模拟研究

为了探究零间隙压气机流动失稳机理,采用全通道非定常数值模拟方法研究了一台零间隙斜流压气 机转子的失稳机理,数值模拟过程中在转子出口施加了随时间动态变化的背压模拟压气机转子节流,非定常 数值计算结果表明零间隙斜流压气机转子仍然表现为典型突尖流动失稳特征。通过详细地分析斜流压气机 转子节流过程中不同阀系数对应的压气机内部流场结构,结果表明:尽管零间隙斜流压气机无叶顶泄漏特 征,但随着对压气机节流,转子叶片尾缘率先出现流动分离,进一步节流,尾缘流动分离表现为一方面在周向 范围加剧,另一方面分离点逐渐向上游移动,造成通道严重堵塞,最终引发相邻叶片通道尾缘回流和叶片前 缘流动溢出进而诱发叶片通道内部出现径向涡结构,从而形成压气机突尖失速先兆。     

Photorefractive effect in triphenylamine-based monolithic molecular glasses with low Tg

A novel series of triphenylamine-based photorefractive molecules M1–M5 with the different push-pull structures were designed and prepared. These molecules can form stable glasses with low glass transition temperature and their optical absorptions as well as photoconductivities at 633 nm increase systematically with increasing acceptor strength and conjugation length. As an unambiguous evidence, the two-beam-coupling experiment was performed to prove the photorefractive effect in each compound with or without an additional sensitizer. Obvious two-beam-coupling effects were obtained for the molecules with good film-forming ability and long-term stability, and among them single-component M1 which has a highly asymmetric structure using both a nitrobenzene and a cyano group as the acceptor showed the best PR performance with a gain coefficient of 52 cm⁻¹ at 0 V μm⁻¹ and 165 cm⁻¹ at 40 V μm⁻¹. Fast response time of 0.025–0.23 s were also obtained at low electric field for these glasses. The correlation of the molecular structure with the PR property was discussed, and a possible explanation for the unique energy transfer observed in M1 and M2 under zero field was proposed.     

我国辐射环境监测网络质量管理现状及发展对策

"十五"期间,环境保护部组建了全国辐射环境监测网络,在网络运行过程中,加强监测数据的质量管理至关重要,从而要求各网络成员单位从监测方法、仪器设备、分析试剂、人员素质、数据处理及信息管理等方面做好质量保证工作,使监测结果具有较好的科学性、代表性和准确性。本文简单介绍了我国辐射环境监测网络的建设过程,在总结我国辐射环境监测网络质量管理现状的基础上,通过分析其中存在的问题,提出了我国环境监测质量管理体系改进的建议和对策。