喷气燃料中的固体颗粒杂质污染

喷气燃料固体颗粒杂质污染问题近几年越来越引起关注，由于固体颗粒杂质所引发的事故也不断增加。美国联邦航空局（FAA）、国际航协（IATA）和联营系统（AFQRJOS）规定加入到飞机油箱的燃料中固体颗粒含量不得超过1mg／L，然而喷气燃料中固体颗粒含量是动态的，因此了解喷气燃料中固体颗粒含量的来源及存在的状态，运输、储存和加注过程中如何控制固体颗粒污染是有益的。在航空油料质量管理中，除去中固体颗粒含量和检测中固体颗粒含量是一个很重要的技术步骤。     

装备研制中的并行工程方法

对装备开发中所采用的两种不同的组织形式进行了分析对比,介绍了"并行工程"的基本概念,并从管理角度出发论述了利用并行工程方法进行装备开发的几个关键过程.     

散射干扰自适应对消

一、引言本文是研究自适应对消散射干扰方法的一个总结报告。报告内容涉及到对雷达主瓣的散射干扰,和来自地面或干扰体照射的箔条对通讯系统的散射干扰。这些方法也能用于接收天线附近的散射源对接收天线旁瓣或主瓣的散射干扰,也就是说,适用于解决某些自适应弱信号系统中的多路问题(多路问题的应用,原来受到很大限制)。用辅助天线所接收的干扰延迟复制信号作为对消散射干扰的技术,如第二节所述。在应用某些散射对消器时,需要大量的自适应加权。当干扰机干扰大片区域时、或在主瓣内有大     

空间站通信和跟踪系统

本文将对空间站通信和跟踪系统的现有要求、结构和设计思想进行全面描述,着重阐述那些需要用新方法才能构成高成本—效率飞行系统的领域。其中包括空对空线路、确定自由飞行器相对位置的差分全球定位系统、多目标雷达、数据包/等时信号处理和激光对接系统。另外,本文还将概述预先研制、试验和分析的重要性。     

公众演示表明远现技术大有希望

上星期,坐在温暖舒适的美国航空航天博物馆控制站内的操作手,与数千公里以外水下机器人进行电气连接,通过广角镜头观看了南极冰层下面的水下生命,并且自引导观看了冰土边沿。该演示透露了一种将来用于遥控机器人探索遥远世界表面的技术。 目前,随着高速数据网,交互性电视和计算机软、硬件的发展,已能操作远距离的地面远控车辆,反映未来机器人星际探测的希望。该技术称为远现(telepresence),人类借助它能探测各种遥远和危险的环境。     

航天轴承摩擦力矩的最大熵概率分布与bootstraP推断

滚动轴承摩擦力矩具有不确定的波动和趋势变化,属于概率分布与趋势规律都未知的乏信息系统。这是一个重要问题,它阻碍了对轴承摩擦力矩的小样本分析与总体把握。为了解决这个问题,根据最大熵原理,从小样本入手建立航天轴承摩擦力矩的概率密度函数。以此为基础,在讨论了摩擦力矩的时域特征与概率分布特征后,用bootstrap对摩擦力矩总体的分布参数进行统计推断。试验研究表明,推断结果和试验结果之间的误差很小,满足工程要求。因此,用小样本可以描述航天轴承摩擦力矩总体的统计特征。     

Adaptive environmental control for optimal results during plant microgravity experiments

The SVET Space Greenhouse (SG)--the first and the only automated plant growth facility onboard the MIR Space Station in the period 1990-2000 was developed on a Russian-Bulgarian Project in the 80s. The aim was to study plant growth under microgravity in order to include plants as a link of future Biological Life Support Systems for the long-term manned space missions. An American developed Gas Exchange Measurement System (GEMS) was added to the existing SVET SG equipment in 1995 to monitor more environmental and physiological parameters. A lot of long-duration plant flight experiments were carried out in the SVET+GEMS. They led to significant results in the Fundamental Gravitational Biology field--second-generation wheat seeds were produced in the conditions of microgravity. The new International Space Station (ISS) will provide a perfect opportunity for conducting full life cycle plant experiments in microgravity, including measurement of more vital plant parameters, during the next 15-20 years. Nowadays plant growth facilities for scientific research based on the SVET SG functional principles are developed for the ISS by different countries (Russia, USA, Italy, Japan, etc.). A new Concept for an advanced SVET-3 Space Greenhouse for the ISS, based on the Bulgarian experience and "know-how" is described. The absolute and differential plant chamber air parameters and some plant physiological parameters are measured and processed in real time. Using the transpiration and photosynthesis measurement data the Control Unit evaluates the plant status and performs adaptive environmental control in order to provide the most favorable conditions for plant growth at every stage of plant development in experiments. A conceptual block-diagram of the SVET-3 SG is presented.