置氢对TA15钛合金的变形及切削机理影响

为研究置氢处理对TA15钛合金变形及切削机理的影响,利用拉伸试验和车削测力试验对比不同置氢量下该合金的力学行为、切削力、锯齿切屑显微组织特征的差异.结果表明,高置氢量合金的屈强比减小,塑性提高,加工硬化严重;置氢促进了热软化效应的发生,氢含量越高,引起切削力下降的临界切削速度越低;同时从未置氢和低置氢组的锯齿切屑内能够...     

Testability evaluation using prior information of multiple sources

Testability plays an important role in improving the readiness and decreasing the lifecycle cost of equipment. Testability demonstration and evaluation is of significance in measuring such testability indexes as fault detection rate（FDR） and fault isolation rate（FIR）, which is useful to the producer in mastering the testability level and improving the testability design, and helpful to the consumer in making purchase decisions. Aiming at the problems with a small sample of testability demonstration test data（TDTD） such as low evaluation confidence and inaccurate result, a testability evaluation method is proposed based on the prior information of multiple sources and Bayes theory. Firstly, the types of prior information are analyzed. The maximum entropy method is applied to the prior information with the mean and interval estimate forms on the testability index to obtain the parameters of prior probability density function（PDF）, and the empirical Bayesian method is used to get the parameters for the prior information with a success-fail form. Then, a parametrical data consistency check method is used to check the compatibility between all the sources of prior information and TDTD. For the prior information to pass the check, the prior credibility is calculated. A mixed prior distribution is formed based on the prior PDFs and the corresponding credibility. The Bayesian posterior distribution model is acquired with the mixed prior distribution and TDTD, based on which the point and interval estimates are calculated.Finally, examples of a flying control system are used to verify the proposed method. The results show that the proposed method is feasible and effective.     

航天器AIT保障技术——环境数据多点、实时、自动监测及显示技术

航天器AIT厂房的温、湿、洁净度直接影响航天产品的寿命及可靠性。厂房密闭性、空调系统性能、天气变化、人员和设备进出等因素都会导致环境参数超标。因此,如何在第一时间根据厂房环境数据的变化采取有效的控制措施,就成为避免环境参数超标的关键。高可靠的环境数据监测系统有效地解决了这一难题。文章主要介绍了航天器AIT厂房环境数据多点、实时、自动监测及显示系统的建设方案。     

SARS-CoV-2疫苗研发进展与挑战

2020 年，一场突如其来的新型冠状病毒(SARS-CoV-2)的流行，让全世界的公共卫生体系经受了严峻的考验。 因此，获得有效预防和治疗 SARS-CoV-2 的疫苗是全世界共同的期待。目前，全球已经有两百多种疫苗处于临床前研究和临床试验阶段，但由于 SARS-CoV-2 首次肆虐人类，目前对其诱导免疫应答的规律及机制尚不完全清楚，且各类疫苗开发时间及临床应用数据有限， 尚不能确定哪一款 SARS-CoV-2 疫苗具有更好的保护性及安全性。本文从 SARS-CoV-2 关键结构、 免疫应答特征、现有的 SARS-CoV-2 疫苗研发技术路线及目前疫苗开发面临的挑战等方面进行综述，以期为 SARS-CoV-2 疫苗研发提供理论基础及思考。     

脉冲爆震发动机中温度和组分浓度测量技术的发展

脉冲爆震发动机内部工作条件极其恶劣,测量爆震波温度和某组分浓度十分困难。本文回顾了近几年国内外在爆震温度场测量方面的技术发展,特别是应用激光诊断技术测量爆震波的温度和某些组分浓度。总结了国内外应用光学诊断技术测得的爆震波火焰温度,结果发现:对气体燃料/氧气而言,在化学恰当比下一般其爆震波温度大约为3900K,与CJ理论值非常接近;然而对液态燃料JP-10而言,当氧化剂为氧气时,爆震波温度为2500K;当氧化剂为空气时,爆震波温度仅仅约为1500K。