基于GPS跟踪技术的TDRS星测轨

本文评述了利用GPS和GPS有关技术确定TDRS星轨道的二种不同方法。第一种TDRS星上装GPS接收机,直接测得到GPS卫星的距离,以此确定TDRS星历,不需要地面测控网;第二种TDRS星发一适当的信标信号,地面多台接收机同时跟踪GPS和TDRS卫星。这两种方法都能满足未来TDRS—Ⅱ的测轨精度要求。     

弹道靶中超高速发射弹的流场及空气动力特性研究

本文描述的是研究爆炸成型发射弹(EFP)模型的流场及超高速空气动力特性所用的弹道试验设备;简要报导了记录全尺寸干涉图形的技术;对径向密度分布再现的方法进行了讨论;在零攻角实验时不同模型的空气动力阻力是采用简化方法来计算的;对各种不同EFP型式的气动稳定性提出了定性估计的方法;并阐述了用于组合体超高速飞行特性研究的数值计算技术的基本原理.     

三维固体推进剂药柱中的气流分析

推进剂药柱形状朝着三维几何形状发展,这就导致我们去寻求和采用三维的内气流计算机程序。     

数字力传感器

本文叙述一种数字力传感器装置,更准确地定义为间接数字装置。该装置保持模拟力传感器的大部分优点,并具有数字系统的稳定性和与计算机的相容性。数字力传感器可处理700克以内的力,用普遍采用的敏感元件,二进制8位,分辨率4克。询问率为7仟赫,可识别频率大大超过1仟赫的力。线性度优于±0.1％±二进制最低位的1/2,重复率优于满量程的±0.25％。所述的装置在三年内几乎每天使用,经考核是十分可靠的。此传感器用作全数字张力测试仪的总体部分,其性能超过测试系统的需要。与联结大批生产的模一数硬件的模拟传感器相比,此传感器在设计和制造上是经济的。     

高温合金的高速定向结晶

本文论述了高温合金定向结晶工艺的发展方向及对定向结晶装置进行的研究和改进。研究结果表明,所研制的定向结晶装置可使高温合金的结晶速度达到4～8mm/min(一般定向结晶)和16～80mm/min(液体金属冷却的高速定向结晶)。高速定向结晶工艺可显著提高铸件的主要使用性能及铸件生产率。     

Deuterium-free water (1H2O) in complex life-support systems of long-term space missions

Heavy water containing deuterium displays toxic property. It is stated that any quantity of a heavy isotope of hydrogen--deuterium--is undesirable to animals and plants. It was earlier shown by us that physical-chemical life support systems on board the "MIR" station fractionate (change) isotopes of hydrogen, oxygen and carbon. Therefore, the problem of regenerative systems in habitable space objects should include removal, from water, of a heavy stable isotope of hydrogen--deuterium. In this article we consider one method of obtaining deuterium-free water--decomposition of distillate water in an electrolyser to hydrogen and oxygen with subsequent synthesis in a catalytic or high-temperature reactor. The influence of deuterium-free water on the growth and development of Arabidopsis thaliana and Japanese quail is investigated. It is shown that with the help of the electrolysis method it is possible to fabricate water containing 80% less deuterium in comparison with SMOW. Experimentally, it is proved on a culture of Arabidopsis thaliana and Japanese quail that water with reduced contents of deuterium (80%) displays positive biological activity.     

Induction of vascular endothelial phenotype and cellular proliferation from human cord blood stem cells cultured in simulated microgravity

Recent studies have demonstrated that stem cells derived from adult hematopoietic tissues are capable of trans-differentiation into non-hematopoietic cells, and that the culture in microgravity (microg) may modulate the proliferation and differentiation. We investigated the application of microg to human umbilical cord blood stem cells (CBSC) in the induction of vascular endothelial phenotype expression and cellular proliferation. CD34+ mononuclear cells were isolated from waste human umbilical cord blood samples and cultured in simulated microg for 14 days. The cells were seeded in rotary wall vessels (RWV) with or without microcarrier beads (MCB) and vascular endothelial growth factor was added during culture. Controls consisted of culture in 1 G. The cell cultures in RWV were examined by inverted microscopy. Cell counts, endothelial cell and leukocyte markers performed by flow cytometry and FACS scan were assayed at days 1, 4, 7 and at the termination of the experiments. Culture in RWV revealed significantly increased cellular proliferation with three-dimensional (3D) tissue-like aggregates. At day 4, CD34+ cells cultured in RWV bioreactor without MCB developed vascular tubular assemblies and exhibited endothelial phenotypic markers. These data suggest that CD34+ human umbilical cord blood progenitors are capable of trans-differentiation into vascular endothelial cell phenotype and assemble into 3D tissue structures. Culture of CBSC in simulated microg may be potentially beneficial in the fields of stem cell biology and somatic cell therapy.     

GEOS-3相参C波段跟踪数据的处理和分析

一、引言 1975年4月10日号发射的GEOS-3号卫星是第一个载有相参C波段应答机的轨道飞行器。GEOS序列中前面的卫星都装载非相参C波段应答机,这种应答机不适合于双程多卜勒距离变化率测量。用于GEOS-3任务的现有C波段雷达中,大约三分之一的雷达具有相参工作的能力,即雷达备有相参信号处理器(CSP)或者速度信息提取分系统(VESS)。这些分系统能输出目标距离变化率(沿斜距矢量方向)的数字量。这种测量分系统做成Ⅱ型伺服系统(其模型项为R和R),由正比于回波信号频率相对于本振频率偏移的误差信号来驱动,并备有相应的消除谐波模糊的措施。