“奖状”560xls发动机无法正常自动启动故障分析

介绍了"奖状"560xls飞机发动机启动系统的组成结构及基本原理,分析了该型发动机无法按正常程序自动启动的原因,可供今后该型号飞机的维护借鉴。     

Calcium influx through stretch-activated channels mediates microfilament reorganization in osteoblasts under simulated weightlessness

We have explored the role of Ca²⁺ signaling in microfilament reorganization of osteoblasts induced by simulated weightlessness using a random positioning machine (RPM). The RPM-induced alterations of cell morphology, microfilament distribution, cell proliferation, cell migration, cytosol free calcium concentration ([Ca²⁺]_i), and protein expression in MG63 osteoblasts were investigated. Simulated weightlessness reduced cell size, disrupted microfilament, inhibited cellular proliferation and migration, and induced an increase in [Ca²⁺]_i in MG63 human osteosarcoma cells. Gadolinium chloride (Gd), an inhibitor for stretch-activated channels, attenuated the increase in [Ca²⁺]_i and microfilament disruption. Further, the expression of calmodulin was significantly increased by simulated weightlessness, and an inhibitor of calmodulin, W-7, aggravated microfilament disruption. Our findings demonstrate that simulated weightlessness induces Ca²⁺ influx through stretch-activated channels, then results in microfilament disruption.     

T cell regulation in microgravity – The current knowledge from in vitro experiments conducted in space,parabolic flights and ground-based facilities

Dating back to the Apollo and Skylab missions, it has been reported that astronauts suffered from bacterial and viral infections during space flight or after returning to Earth. Blood analyses revealed strongly reduced capability of human lymphocytes to become active upon mitogenic stimulation. Since then, a large number of in vitro studies on human immune cells have been conducted in space, in parabolic flights, and in ground-based facilities. It became obvious that microgravity affects cell morphology and important cellular functions. Observed changes include cell proliferation, the cytoskeleton, signal transduction and gene expression. This review gives an overview of the current knowledge of T cell regulation under altered gravity conditions obtained by in vitro studies with special emphasis on the cell culture conditions used. We propose that future in vitro experiments should follow rigorous standardized cell culture conditions, which allows better comparison of the results obtained in different flight- and ground-based experiment platforms.     

递归投影方法(RPM)及其在流场数值模拟中的加速收敛性能研究

随着计算流体力学中的物理模型的日益复杂和数据运算量的增大,人们越来越重视提高数值方法的计算效率。本文在研究RPM方法的基础上,提出了一种更易于保证实施精度的具有良好加速收敛性能的改型的RPM方法。一方面,通过构造的一维迭代格式研究了几个控制参数如Krylov接受比、Krylov向量维数等对RPM方法的加速收敛性能的影响。另一方面,研究了在流场数值模拟中即使采用了常规的加速收敛措施如当地时间步长和隐式残值光顺以后,改型的RPM方法的加速收敛性能;结果表明,此时,RPM方法仍然能使总体上的收敛速度提高近1/3。