应用自定位技术提供高精度的弹道位置参数

本文介绍了对连续波雷达的多普勒频率信息,用自定位技术获得高精度的弹道位置参数的一种方法。通过一些试验弹道的仿真计算,其结果表明当观测误差噪声为白噪声时,该方法所提供的弹道位置参数将比目前由连续波雷达定位信息提供的位置参数,其精度有明显的提高。     

带有参考信号的直接序列扩频系统

扩频通信系统中码同步的精度及其电路的复杂程度直接影响系统的性能、体积和成本。采用发射参考信号法可以简化接收机端的码同步电路 ,从而大大减小遥控遥测系统及无线局域网中扩频接收机的体积和成本。本文给出了采用 MAXIM芯片组实现 UHF频段带有发射参考信号的直接序列扩频系统 ,并通过 System View软件进行了仿真 ,结果表明该方法可获得较好的通信性能 ,易于工程实现     

Buffer Capacity Failure Analysis and Improvement Measures for L/Gs of a Certain Type of Aircraft

起落架是飞机的重要部件之一,其重要功能是减少飞机在起飞和着陆过程中地面对机体的冲击,保护机体结构免受损伤.本文详述了某型飞机起落架落震试验中出现的问题,并通过对试验数据和缓冲器结构的分析,找到了产生故障的原因,提出了改进措施,可为今后解决类似问题提供参考.     

数据链试飞电波传播衰减计算

数据链作用距离的试飞结果受试验区电波传播衰减影响很大,需要对其进行精确计算,为分析试飞结果提供支持.Fock级数法是计算电波衰减的一种精确方法,本文详细讨论了应用该方法求解试验区电波传播衰减的工程计算问题.     

异面压缩下六边形铝蜂窝平均塑性坍塌应力研究

为了研究铝蜂窝在准静态异面压缩下的平均塑性坍塌应力，基于简化的基本折叠单元理论，以单个完整铝蜂窝六边形单元为研究对象，根据能量守恒定律，形成一个基本折叠单元外力所做的功等于屈曲能和膜能的总和，由此分别假设铝蜂窝材料服从Tresca屈服准则或Mises屈服准则，给出了两个准静态异面压缩下铝蜂窝平均塑性坍塌应力的理论计算公式，试验结果验证了理论推导的正确性。提出的公式对研究铝蜂窝的异面压缩性能具有一定的工程指导意义。     

白炽灯色温测量装置电路设计

介绍利用单片单板机接口电路完成对６Ｖ、３０Ｗ白炽灯光源与其对应的标准白炽灯光源的色温比对标定工作。     

Simulated microgravity induce apoptosis and down-regulation of erythropoietin receptor of UT-7/EPO cells

Hematopoietic progenitor cell proliferation can be alternated on either spaceflight or under simulated microgravity experiments on the ground; however, the underlying mechanism remains largely unknown. In the present study, we have demonstrated that exposure of human erythropoietin (EPO)-dependent leukemia cell line UT-7/EPO cells to conditions of simulated microgravity with a rotary culture instrument significantly inhibited the cellular proliferation rate. Adding higher concentrations of EPO to the culture medium failed to improve the inhibitory status. Cell apoptosis was detected by fluorescence staining of cell nuclei and a flow cytometry assay using Annexin V/PI double staining. This microgravity-induced apoptosis in UT-7/EPO cells could be blocked by a pancaspase inhibitor Z-VAD-FMK. Immunoblotting demonstrated that rotary culture resulted in a reduction of the expression of Bcl-xL, an anti-apoptotic protein, and the cleavage of caspase-3. Furthermore, rotary culture reduced surface localization and protein content, as well as the mRNA expression of erythropoietin receptor (EPOR) of UT-7/EPO. Take together, the findings indicated that simulated microgravity may induce mitochondrial related apoptosis of UT-7/EPO cell through depressing the EPO–EPOR pathway.     

Mutations in cauliflower and sprout broccoli grown from seeds flown in space

Cauliflower and sprout broccoli are widely planted vegetables particularly in Fujian Province, China. To study the mutation in these two types of vegetables induced from spaceflight, we flew the seeds on the 20th Chinese recoverable satellite which orbited the Earth for 18 days. After returning to the Earth, the cauliflower seeds were planted for two generations and the sprout broccoli seeds for one generation at the Xiamen Agriculture Research Institute. Of the 12 cauliflowers planted for the first generation, two showed significant phenotypical changes in both the size of the plant and the weight of the flower head. In addition, most of the space flown plants were found to be resistant to the black rot attack in the field. Cauliflowers planted for the second generation from the seeds in one of the two plants that displayed phenotypical changes in the first generation showed similar mutations. For the first generation of sprout broccoli, the rate of emergence from the flown seeds was lower than that of the control by 30%. No significant changes in the phenotype between the sprout broccolis planted from the flown seeds and the control were observed except one of the mutated sprout broccolis showed a change in the appearance in the lesser bud of the chief flower head. Results of the study demonstrated that DNA damages in some of the genes may have occurred in the seeds flown in space, and some of the changes in the genes may have inherited from the first to the second generation. The improved resistance to the black rot attack and increased size of the flower head are apparently beneficial.     

Sun Storage整合性解决方案

作为存储市场的领先者,Sun比全球其他企业都保护和管理着更多的数字归档数据.可以为用户提供整合的解决方案,帮助简化IT基础设施、降低成本、安全方便地实现从创建到删除的数据管理.     

地面站远程监控系统的设计与实现

以国际某全球卫星测控网络为例,介绍了测控网与卫星测控地面站远程监控体制的设计与实现,包括通信链路、控制中心以及测控站远程监控网络的设计,为国内测控网全网IP化改造提供了一个有效的范例。