振动轮式硅微陀螺自动增益控制电路研究

为了提高硅微陀螺仪的检测精度,稳定硅微陀螺仪的标度因数,驱动信号的振幅和频率都需要稳定。采用自激驱动方式能使驱动频率自动稳定在陀螺仪驱动模态的谐振频率上;同时,采取自动增益控制电路（AGC）可以保持驱动振幅的恒定。本文根据场效应管的可变电阻特性,提出一种硅微陀螺仪自动增益控制方法。经试验证明此方法可以有效的稳定驱动电压幅值,达到恒幅的目的。     

环境试验数据和控制系统技术:过去、现在、将来

Michellich先生毕业于堪萨斯大学,获得博士学位。他1966年进入波音公司。他曾搞过土星V的仪表系统试验,S—IC级靜态点火数据处理,研究随机和瞬态数据处理程序、研究振动控制系统软件。现在他在波音航空工程实验室负责研制新的数据收集,试验控制和数据处理系统。     

Cell-to-cell interactions in changed gravity: ground-based and flight experiments

Cell-to-cell interactions play an important role in all physiological processes and are mediated by humoral and mechanical factors. Mechanosensitive cells (e.g., osteocytes, chondrocytes, and fibroblasts) can be studied ex vivo to understand the effects of an altered gravity environment. In particular, cultured endothelial cells (EC) are very sensitive to a broad spectrum of mechanical and biochemical stimuli. Earlier, we demonstrated that clinorotation leads to cytoskeletal remodeling in cultured ECs. Long-term gravity vector changes also modulate the expression of surface adhesion molecules (ICAM-1, E-selectin, VCAM-1) on cultured ECs. To study the interactions of geterological cells, we cocultured endothelial monolayers and human lymphocytes, immune cells and myeloleucemic (K-560) cells. It was found that, although clinorotation did not alter the basal adhesion level of non-activated immune cells on endothelial monolayers, the adhesion of PMA-activated lymphocytes was increased. During flight experiments onboard the Russian segment of the International Space Station, we measured the cytotoxic activity of natural killer (NK) cells incubated with labeled target cells. It was found that immune cells in microgravity retained their ability to contact, recognize, and destroy oncogenic cells in vitro. Together, our data concerning the effects of simulated and real microgravity suggest that, despite changes in the cytoskeleton, cell motility, and expression of adhesion molecules, cell-cell interactions are not compromised, thus preserving the critical physiological functions of immune and endothelial cells.     

Production of oxidants by ion irradiation of water/carbon dioxide frozen mixtures

We present new experimental results on the formation of oxidants, such as hydrogen peroxide, ozone, and carbonic acid, under ion irradiation of icy mixtures of water/carbon dioxide at different ratios and temperatures (16 and 80 K). Pure water ice layers and mixtures with carbon dioxide were irradiated by 200 keV He+ ions. We found that the CO(2)/H(2)O ratio progressively decreased to a value of about 0.1, the H(2)O(2) production increased with increasing CO(2) abundance at both 16 and 80 K, and the CO and H(2)CO(3) production increased with increasing CO(2) abundance at 16 K. At 80 K, the synthesis of CO was less efficient because of the high volatility of the molecule that partially sublimed from the target. The production of carbonic acid was connected with the production of CO(3). O(3) was detected only after ion irradiation of CO(2)-rich mixtures. The experimental results are discussed with regard to the relevance they may have in the production of an energy source for a europan or a martian biosphere.     

用于空间舱火灾预警的气体检测技术研究

针对空间舱火灾的风险和早期预警需求,提出了一种用于空间舱火灾预警的气体检测装置设计方案。该方案首先基于微重力条件下燃烧特征和相关非金属材料燃烧试验,提出了适用空间舱火灾预警的目标气体类型和对应的指标要求以及组分气体火灾报警策略,并以此为根据设计了基于激光吸收光谱技术用于火灾探测的四通道气体检测系统,同时搭建了单通道气体检测装置。试验结果显示:单通道气体检测装置的T90响应时间约为1 s,且在-30～60℃范围内温度对浓度测量的影响小于1%,响应快速性及免标定功能均得到了试验验证。     

新型机体结构材料——碳纤维棒

这种由美国Neptco公司研制的碳纤维/环氧树脂棒材料因具有较高的强度和能降低制造成本和加快制造速度的潜力,有希望用来制造飞机的机体结构部件.这种材料被称之为“石墨石”(Graphlite),可用来代替通常在复合材料铺层中所使用的纤维及带形材料.贝尔直升机公司最近组装了一个3.66米(12英尺)长的翼盒,盒上的桁条便由这种材料制成.这项工作是在美国的一个设计与制造低成本复合材     

面向对象技术在压气机叶片造型设计中的应用研究—通用压气机叶片造型系统

本文通过对实际的应用系统,通用压气机叶片造型系统的功能特点的讨论,介绍了面向对象(Object Oriented)技术在解决工程实际问题中的意义和作用,并对如何把这一技术应用于工程设计领域做了初步的探讨。     

强迫振荡理论

本文给出了基于基本守恒方程的一维轴向稳定分析。分析方法与经典方法不同,区别在于利用一些显式关系项来说明在固体推进剂火箭发动机中声学系统与各种结构、燃烧和呈现的流动现象之间的相互作用。此外,本文处理控制方程的方式也与经典的方法不同,即得到声学系统正态模型的稳定性余量和固有频率的方法与经典方法不一样。本文给出了用这种分析方法研究相互作用的一个例子。这就是试验台轴向振动与声学系统压力振荡之间的相互作用。结果表明,如果振荡频率和振幅需要精确地确定的话,各单个系统即声学和试验台结构不能再单独地考虑。