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叠氮复合固体推进剂技术研究 总被引:7,自引:0,他引:7
分析了航天器和导弹武器系统对固体推进剂提出的新的要求和实现这些要求的技术途径。介绍了国外研制低特征信号叠氮固体推进剂的主要原材料叠氮粘合剂、含能增塑剂、高能高密度氧化剂的发展概况和关键技术。分析认为,由以上材料组成的叠氮复合固体推进剂具有含能量高、密度大、发动机排气羽烟对微波、激光和可见光的透过率高等特征,因此这是一种很有前途的新型推进剂。 相似文献
43.
本文介绍了数字签名技术的概念 ,数字签名技术的使用意义 ,及用JAVA实现数字签名的思想 相似文献
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Jet Vectoring Control Using a Novel Synthetic Jet Actuator 总被引:3,自引:1,他引:2
LUO Zhen-bing XIA Zhi-xun XIE Yong-gao 《中国航空学报》2007,20(3):193-201
A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems. 相似文献
46.
ACARS消息安全( AMS)以一种独立于底层通信机制的应用方式,通过安全机制及支持该机制的加密算法,提供数据机密性、消息认证和完整性的安全服务。介绍了AMS消息结构和处理过程,建议采用一种综合对称和非对称加密系统优势的航空通信方案,分析了安全会话过程,仿真试验证明, AMS在面对安全威胁时能保证ACARS消息的安全传输。 相似文献
47.
Pinliang Dong 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(11):1733-1743
A multiscale approach to hyperspectral image data analysis using fractal signatures was proposed and implemented in the Interactive Data Language (IDL). For 2-D hyperspectral curves, fractal signature measures the changes in curve length with changing scale. Using NASA’s Earth Observing-1 (EO-1) Hyperion image from a study area near Denton, Texas, USA, the capabilities of fractal signatures in discriminating different land cover types were presented in three different ways: (1) fractal signature curves, (2) distances between fractal signatures, and (3) fractal signature images. The asymmetry in length measurement was found to be effective in handling hyperspectral curves obtained from Hyperion radiance data. The contribution of fractal signature images was shown through comparison of image classification results. The results from the Hyperion radiance data suggest that fractal signatures at certain scales can reveal important differences in land cover types. 相似文献
48.
The infrared radiation signature of the plume from solid propellants with different energy characteristics is not the same. Three kinds of double-base propellants of different energy characteristics are chosen to measure the infrared spectral radiance from 1000 cm 1 to 4500 cm 1 of their plumes. The radiative spectrum is obtained in the tests. The experimental results indicate that the infrared radiation of the plume is determined by the energy characteristics of the propellant. The radiative transfer calculation models of the exhaust plume for the solid propellants are established. By including the chemical reaction source term and the radiation source term into the energy equation, the plume field and the radiative transfer are solved in a coupled way. The calculated results are consistent with the experimental data, so the reliability of the models is confirmed. The temperature distribution and the extent of the afterburning of the plume are distinct for the propellants of different energy characteristics, therefore the plume radiation varies for different propellants. The temperature of the fluid cell in the plume will increase or decrease to some extent by the influence of the radiation term. 相似文献
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对满足可信计算平台(TCP,Trusted Computing Platform)需求的代码管理问题,提出了以Java卡为核心,以代码签名技术为主要手段,以卡内的安全域(security domain)作为各个软件权威(Java卡设备发行方和应用提供方)安全策略执行者的可信代码管理框架.新机制支持设备发行方软件的装载和更新,完善了应用提供方安全域的装载和更新流程,并对下载命令数据结构进行了扩充.解决了在复杂应用环境中,多个软件权威相互独立的限制条件下,代码的免人工广播式发布问题,扩展了传统Java卡软件装载模式,提高了系统的安全性,为使用Java卡平台进行可信计算提供保障. 相似文献
50.
固体火箭发动机羽烟特征信号的分类及测试评估概述 总被引:2,自引:0,他引:2
介绍了国外低特征信号固体推进剂分类标准和固体火箭发动机羽烟特征信号分类及测试技术等方面的工作,主要内容涉及发动机羽烟特征信号的定义、产生根源、对使用的影响、理论预估及特征信号测试评估的各种实验方法和设施,并预示了羽烟特征信号测试与评估的发展方向。 相似文献