多卜勒相位量化对定标信号的影响

在内定标设计中，生成的定标信号为模拟回波信号，与雷达射频信号相比，除了经过时延、衰减等处理之外，还加入定位向的相位信息。本文分析了进行多卜勒相位调制时，相位量化对信号匹配滤波器输出的影响，给出了量化ｂｉｔ数的下限。     

综合飞行/火力控制系统线性化设计及其仿真

首先简述了综合飞行／火力控制系统线性化设计的背景及其必要性,然后进行综合分析／火力控制系统（空－空机炮模态）的线性化建模及耦合器参数的设计,最后对非线性系统进行了仿真验证,仿真结果表明,线性化设计的参数经过微调后能够满足原系统性能要求。     

采用商用技术改进军用雷达

采用商用产品和技术有助于降低成本，降低风险并加快技术成果转化的步伐。然而，在高性能飞机电子设备领域，如果不能深入了解军事环境、规范／要求、以及商用产品满足它们的能力，那么就会限制采用商用技术改进航空电子设备的潜力。为了举例说明如何使航空工业向着这个方面转变，本文评述了Hughes飞机公司所开展的工作。Hughes公司正在用商用规范与技术对原有针对军事用途设计并采用军用规范和技术的合成孔径雷达系统进行了改进，以便降低成本并瞄准非军事市场（包括国外的市场）。令人好笑的是，军方已经把该产品供自己使用，并且该雷达第一次就卖给美国军方。Hughes综合合成孔径雷达（HISAR）是一种低成本、高性能SAR雷达，它具有实时侦察、监视和地球资源测绘的能力。HISAR采用了最初为美国空军开发的称作ASARS－2的先进的SAR技术，以便在日、夜及全天侯条件下，形成接近光学照片质量的图像。最初的ASARS－2采用了常规的高速可编程信号处理器，该处理器由数个机架组成，并且需要大功率和冷却。在七十年代中期正在开发ASARS－2时，商用处理器能实现相同的功能，但其硬件资源和软件复杂性要高一个数量级。随着以有效的高速数据总线为特征的信号处理的迅速发展，使人们能采用可靠的、成本显著降低的商用信号处理器代替原来的硬件。商用技术与产品也有可能用于其它雷达功能领域，并进一步降低成本和物理特性。现在HISAR是几个新的美国国防部计划的基础。本文论述了怎样广泛使用商用技术和规程来满足军事要求。     

Lessons learned from Mir--a payload perspective

Among the principal objectives of the Phase 1 NASA/Mir program were for the United States to gain experience working with an international partner, to gain working experience in long-duration space flight, and to gain working experience in planning for and executing research on a long-duration space platform. The Phase 1 program was to provide the US early experience prior to the construction and operation of the International Space Station (Phase 2 and 3). While it can be argued that Mir and ISS are different platforms and that programmatically Phase 1 and ISS are organized differently, it is also clear that many aspects of operating a long-duration research program are platform independent. This can be demonstrated by a review of lessons learned from Skylab, a US space station program of the mid-1970s, many of which were again “learned” on Mir and are being “learned” on ISS. Among these are optimum crew training strategies, on-orbit crew operations, ground support, medical operations and crew psychological support, and safety certification processes.     

Cardiorespiratory responses to exercise after bed rest in men and women

The purpose of this study was to compare cardiorespiratory responses of men and women to submaximal and maximal workloads before and after bed rest (BR). Fifteen male college students (19-23 yr) and 8 female nurses (23-34 yr) underwent 14 d and 17 d, respectively of bed rest. The maximal work capacity test was performed in the supine position on a bicycle ergometer just before and immediately after bed rest. The women's maximal O2 uptake (maximal VO2) was 41% lower (P<0.05) than the men's before bed rest and 42% lower (P<0.05) after bed rest. During bed rest the women's maximal VO2 decreased from 2.06 to 1.86 liter/min (-9.7%, P<0.05), and that of the men decreased from 3.52 to 3.20 liter/min (-9.1%, P<0.05). Compared with pre-BR values, after bed rest the maximal ventilatory volume was essentially unchanged in the men (+1.8%) and women (+ 2.3%), but maximal heart rate was elevated from 185 to 193 b/min (+ 4.3%, P<0.05) in the men and from 181 to 187 b/min (3.3%, P<0.05) in the women. Submaximal VO2 was unchanged after bed rest in the men but was significantly reduced in the women; the women's Hct and RBC levels were lower (P<0.05) than comparable male data. Mean corpuscular volume was unchanged in both groups pre- and post-bed rest. It is concluded that the proportional deterioration in maximal VO2 following prolonged bed rest was essentially the same in young men and women.     

Space product development: bringing the benefits of space down to Earth

In fulfilling the National Aeronautics and Space Administration's (NASA) responsibility to encourage the fullest commercial use of space the Space Product Development (SPD) Program, within the Microgravity Research Program Office (MRPO) located at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, is managing an organization of Commercial Space Centers (CSC's) that have successfully employed methods for encouraging private industries to exploit the benefits of space-based research. Unique research opportunities of the space environment are being made available to private industry in an effort to develop new, competitive products; create jobs; and enhance the country's quality of life. Over 200 commercial research activities have been conducted in space by the CSC's and their industrial partners during the last several years. The success of this research is evidenced by the increasing amount of industrial participation in commercial microgravity research and the potential products nearing marketability.