异想天开——外星球之旅

我坐上我国自行研制的宇宙飞船，开始了我的太空旅行。     

Large solar flare radiation shielding requirements for manned interplanetary missions

As the 21st century approaches, there is an ever-increasing interest in launching manned missions to Mars. A major concern to mission planners is exposure of the flight crews to highly penetrating and damaging space radiations. Beyond the protective covering of the Earth's magnetosphere, the two main sources of these radiations are galactic cosmic rays and solar particle events. Preliminary analyses of potential exposures from galactic cosmic rays (GCR's) were presented elsewhere. In this Note, estimates of shielding thicknesses required to protect astronauts on interplanetary missions from the effects of large solar flare events are presented. The calculations use integral proton fluences for the February 1956, November 1960, and August 1972 solar particle events as inputs into the NASA Langley Research Center nucleon transport code BRYNTRN. This deterministic computer code transports primary protons and secondary protons and neutrons through any number of layers of target material of arbitrary thickness and composition. Contributions from target nucleus breakup (fragmentation) and recoil are also included. The results for each flare are presented as estimates of dose equivalent [in units of roentgen equivalent man (rem)] to the skin, eye, and bloodforming organs (BFO) behind various thicknesses of aluminum shielding. These results indicate that the February 1956 event was the most penetrating; however, the August 1972 event, the largest ever recorded, could have been mission- or life-threatening for thinly shielded (< or = 5 g/cm2) spacecraft. Also presented are estimates of the thicknesses of water shielding required to reduce the BFO dose equivalent to currently recommended astronaut exposure limits. These latter results suggest that organic polymers, similar to water, appear to be a much more desirable shielding material than aluminum.     

基于模型预测控制的非线性飞行控制系统研究

应用泰勒级数展开方法设计了飞行器六自由度非线性模型预测控制器.通过对控制向量和输出向量的有限泰勒级数展开,确定闭环形式的控制输入.仿真结果表明:该方法能够适应控制项不完全或缺少控制项的病态情况,适当选择控制器的泰勒展开阶数可得到最优的控制结果,所设计的模型预测控制器具有很好的跟踪效果.     

The relative role of visual and non-visual cues in determining the perceived direction of "up": experiments in parabolic flight

In order to measure the perceived direction of "up", subjects judged the three-dimensional shape of disks shaded to be compatible with illumination from particular directions. By finding which shaded disk appeared most convex, we were able to infer the perceived direction of illumination. This provides an indirect measure of the subject's perception of the direction of "up". The different cues contributing to this percept were separated by varying the orientation of the subject and the orientation of the visual background relative to gravity. We also measured the effect of decreasing or increasing gravity by making these shape judgements throughout all the phases of parabolic flight (0 g, 2 g and 1 g during level flight). The perceived up direction was modeled by a simple vector sum of "up" defined by vision, the body and gravity. In this model, the weighting of the visual cue became negligible under microgravity and hypergravity conditions.     

一种卫星IP交换系统中ICMP协议FPGA实现方法

卫星IP交换技术是实现星上IP网络的关键技术,在卫星IP交换系统中,通过ICMP协议可报告差错报文信息,并可对卫星IP网络中的不同节点进行连通性测试,因此ICMP协议在卫星IP交换系统中起着重要作用。针对星上模块化设计及处理能力有限的特点,提出一种星上ICMP协议的FPGA实现方法,将ICMP报文的判断和生成流程分开,判断部分可在各个端口处理模块完成,生成部分采用单独模块完成,不需要在每个端口模块都完成ICMP报文生成处理操作,不仅优化了星上ICMP协议处理流程,并且节约了星上存储及处理资源。     

基于智能信息融合的飞控系统故障检测隔离方法研究

利用小波时频信号分析技术来分离非平稳噪声,提高了残差中故障信息的信噪比.提出了智能信息融合故障检测新方法,应用模糊逻辑自适应调节无故障的模型参数,抑制残差中非平稳信号的增长;采用人工神经网络故障分类器来消除非线性故障信号偏差对残差判决的影响,扩大了故障检测与隔离算法的适用范围.仿真结果表明,该算法技术性能优越,改进效果明显.