Bubble detector characterization for space radiation

In light of the importance of the neutron contribution to the dose equivalent received by space workers in the near-Earth radiation environment, there is an increasing need for a personal dosimeter that is passive in nature and able to respond to this neutron field in real time. Recent Canadian technology has led to the development of a bubble detector, which is sensitive to neutrons, but insensitive to low linear energy transfer (LET) radiation. By changing the composition of the bubble detector fluid (or “superheat”), the detectors can be fabricated to respond to different types of radiation. This paper describes a preliminary ground-based research effort to better characterize the bubble detectors of different compositions at various charged-particle accelerator facilities, which are capable of simulating the space radiation field.     

欧空局,日本和俄罗斯1999年航天预算

１欧空局１９９９年预算增加２．２％□□１９９８年１２月１６日～１７日，由１４国航天局局长组成的欧空局（ＥＳＡ）管理委员会批准了ＥＳＡ１９９９年的预算。新预算总计２６．５亿欧元（合３１亿美元），比１９９８年的预算增长２．２％（见表１）。表１欧空局１９９...     

印度航天预算增长16%

印度今年2月27日在议会宣布的1999～2000年度财政预算中,印度航天部的预算为175.5亿卢比(合4.129亿美元),占印度所有科学机构总经费的17%。1999～2000财年的航天预算比已批准的1998～1999财年航天预算(151.1亿卢比)增长了16%,但如把4.8%的通货膨胀率考虑在内,实际增长11%。1998～1999财年的预算已在1998年10月做了一次中期估算,结果表明,到1999年3月31日财政年度结束,航天总预算的估算值为151.6亿卢比。印度财政部的预算分配方案必须在4月1日财政年度开始之前经议会批准。预算分配情况见表1。从表1中可以看出,拨款的重点是“地球静止轨道运…     

光学系统的偏振分析

对于大多数光学系统，一般都假设透射波面具有均匀的振幅（或高斯型振幅）和恒定的偏振态。这是几何光学的不完善假设。文中讨论的方法，适合于分析这种假设不能成立的系统。文中所讨论的偏振分析法包括了偏振光线追迹和偏振像差论。文中还讨论了偏振现象的基本分类定义，并述评了琼斯（Ｊｏｎｅｓ）计算法，以此作为讨论的基础。     

基于数字全息的活体细胞动态相衬显微观察

针对生物活体细胞的观测要求,研究了一种基于数字全息的动态相衬显微实验方法.利用光纤器件和分立光学元件搭建了一套预放大离轴数字全息实验系统,采用无穷远校正显微物镜提高了成像分辨率,同时通过曲率匹配透镜和构造数字相位掩模对相位畸变进行了校正.对小鼠活体骨细胞样品进行了连续动态观察,得到了反映细胞运动和形态变化的相衬显微图像,证明了此方法的可行性.     

工业以太网EtherCAT冗余和热插拔技术

EtherCAT是一种实时工业以太网协议,使用冗余技术是实现热插拔和提高通信可靠性的重要手段.首先介绍了实时工业以太网EtherCAT的组成、工作原理和报文结构,研究了使用环型网络拓扑结构实现基于EtherCAT的工业自动化控制系统故障容错及热插拔技术,分别规划了在网口故障、链路故障和节点故障时冗余帧传播机制、故障点定位和恢复策略.开发了链路冗余EtherCAT主站驱动程序,将常规EtherCAT主站驱动程序做了修改,加入链路冗余机制,对上层应用屏蔽了冗余信息和操作.最后完成了冗余和热插拔的性能测试实验,结果表明系统性能优越,运行稳定.     

Using Spacelab as a precursor of science operations for the Space Station

For more than 15 years, Spacelab, has provided a laboratory in space for an international array of experiments, facilities, and experimenters. In addition to continuing this important work, Spacelab is now serving as a crucial stepping-stone to the improved science, improved operations, and rapid access to space that will characterize International Space Station. In the Space Station era, science operations will depend primarily on distributed/remote operations that will allow investigators to direct science activities from their universities, facilities, or home bases. Spacelab missions are a crucial part of preparing for these activities, having been used to test, prove, and refine remote operations over several missions. The knowledge gained from preparing these Missions is also playing a crucial role in reducing the time required to put an experiment into orbit, from revolutionizing the processes involved to testing the hardware needed for these more advanced operations. This paper discusses the role of the Spacelab program and the NASA Marshall Space Flight Center- (MSFC-) managed missions in developing and refining remote operations, new hardware and facilities for use on Space Station, and procedures that dramatically reduce preparation time for flight.     

高职高专"机械设计基础"课教学改革探讨

在课内学时大幅削减的情况下,对“机械设计基础”课程进行教学改革的基本思路是：重新整合课程内容;合理安排自学内容;增加感性认识环节;更新教学手段等措施,提高学生的综合设计能力、创新能力和解决实际工程问题的能力.