航天光学遥感器光学装调技术现状与展望

航天光学遥感器工作于太空中,长期恶劣的空间环境及短暂发射入轨时的状态对光学系统的设计与装调提出了苛刻的要求,确保光学系统在轨像质优异是航天光学遥感器研制的关键技术.文章结合国际上航天光学遥感器的发展需求对光学系统装调技术及发展现状进行了分析、总结,提出了中国后续航天光学遥感器装调与测试技术的突破方向.     

新型电工钢片磁性能无损检测传感器及应用

介绍了一种新型电工钢片磁性能无损检测传感器及其测量原理 ,同时讨论了该传感器的设计原则并给出了典型数据及仿真测试结果     

ZnCr2O4-V2O5-Li2O-ZnO湿敏材料的气体选择性研究

测试了ZnCr2O4-V2O5-Li2O-ZnO感湿体在H2、CO2、煤气、酒精蒸汽等气体环境中电阻的变化情况.结果表明,电阻值明显随环境温度变化但基本不受气体影响.     

论航空产品质量改进

航空产品质量改进针对旧的质量标准．建立新的质量标准，可以不断提高产品技术水平，克服存在的缺陷,改善使用性能。为保证质量改进取得预期效果，应从程序、方法和管理控制等多方面着手。     

民机燃油箱防爆闪电防护新适航要求研究

民用飞机燃油箱系统防爆设计是飞机设计的一个重要方面,其中适航对燃油箱系统闪电防护设计要求作为燃油箱防爆设计及验证的一个重要组成部分,历来受到航空工业界及美国联邦航空局(FAA)的普遍关注。通过研究FAA 关于民用飞机燃油箱系统防爆方面闪电防护的最新适航要求,总结了相关条款的变化内容及相应的符合性验证方法,并预判了未来航空工业界由此产生的影响,对民用飞机适航验证有一定借鉴意义。     

Top-level modeling of an ALS system utilizing object-oriented techniques.

The possible configuration of an Advanced Life Support (ALS) System capable of supporting human life for long-term space missions continues to evolve as researchers investigate potential technologies and configurations. To facilitate the decision process the development of acceptable, flexible, and dynamic mathematical computer modeling tools capable of system level analysis is desirable. Object-oriented techniques have been adopted to develop a dynamic top-level model of an ALS system.This approach has several advantages; among these, object-oriented abstractions of systems are inherently modular in architecture. Thus, models can initially be somewhat simplistic, while allowing for adjustments and improvements. In addition, by coding the model in Java, the model can be implemented via the World Wide Web, greatly encouraging the utilization of the model. Systems analysis is further enabled with the utilization of a readily available backend database containing information supporting the model. The subsystem models of the ALS system model include Crew, Biomass Production, Waste Processing and Resource Recovery, Food Processing and Nutrition, and the Interconnecting Space. Each subsystem model and an overall model have been developed. Presented here is the procedure utilized to develop the modeling tool, the vision of the modeling tool, and the current focus for each of the subsystem models.     

传统审计模式与现代风险导向审计模式的比较分析

注册会计师审计发展到今天,经历了传统审计模式与现代风险导向审计模式,而这两种审计模式无论是在产生背景、审计理念还是采用的技术方法等方面都存在诸多不同,可以说,现代风险导向审计模式是审计人员为了适应审计环境的变化而做出的理性选择。论文试图通过对传统审计模式与现代风险导向审计模式的比较,认识和了解现代风险导向审计模式的具体情况,从而对促进我国审计职业界的发展产生一些有益的启示。     

凝胶点官能度是重均官能度,还是数均官能度

Flory和Stockmayer等的凝胶化理论用重均官能度表示凝胶点或凝胶生成的临界条件,虽已有50多年的历史,并为各国学者所公认,但从分析凝胶点定义的物理意义出发,只要用简单的数学分析,即可证明用重均官能度而不用数均官能度表示凝胶点,与反应程度定义的物理意义和Flory的两个基本假设不符。凝胶化理论新概念用数均官能度表示凝胶点,则不存在不符的问题。     

空间飞行器交会对接相对位置和姿态的在轨自检校光学成像测量算法

空间飞行器交会对接的最后逼近阶段，通常采用光学成像敏感器来测量跟踪飞行器和目标飞行器之间的相对位置和姿态。考虑到飞行器在轨运行期间，CCD相机受空间环境的影响，其内参数会发生变化的实际情况，提出了一种单CCD在轨自检校光学测量方案，其主要特点是飞行器在执行测量任务时，可同时进行相机内参数的自检校。首先根据严格的中心投影共线条件方程，推导出目标飞行器光学特征点坐标和对应的像点坐标与内参数及相对位置和姿态的严格解析关系；然后建立了内参数及相对位置和姿态的解析表达式；提出了目标航天器上光学特征点的布设要求。通过严格的理论分析和数值仿真，单CCD在轨自检校光学测量方案具有可靠性高、精度高、算法易实现、适应能力强等优点。     

High-Order Intermodulation Effects in Digital Satellite Channels

The phenomenon of intermodulation generation due to passive and normally linear components is sometimes called passive intermodulation. A unique characteristic of passive intermodulation interference in communications satellites is that the products causing trouble are of high orders. Due to the immense combinatorial complexity of the problem, both exact analysis and direct simulation are almost impossible. In this paper the problem is simplified by considering a composite interference model consisting of 1) the lowest order intermodulation product (of those high-order ones) at a frequency of interest, 2) a constant-envelope carrier with random phase to account for all other intermodulation interferences by direct overlap or spectrum spreading in the vicinity, and 3) white Gaussian noise (receiver noise). An approximation of the tail statistics of this composite interference is derived, and numerical results (checked by simulation) show that the tail distribution may be very different from Gaussian; careful consideration must be rendered before resorting to the a priori Gaussian assumption.