Issues relating to civilian and military dual uses of GNSS

This paper discusses the civilian and military dual uses of Global Navigation Satellite Systems (GNSS). Its focus is on the primary GNSS provider: the United States dual use Global Positioning System (GPS). The Russian Glonass is also dual use but this is used much less than GPS. It is difficult for the US Department of Defense to accommodate the requirements of all the civilian users. Resolution of some dual use problems is accomplished through pressure and negotiation. International civilian users exacerbate the dual use problem by demanding service guaranties and a share of control over GPS. Additionally, Europeans seek to obtain a share of the promising GNSS industry and employment by building their own GNSS provider Galileo.     

北美波音747维修业务进退维谷

在北美,波音747-400运营商到海外进行机体的重维修似乎成为其唯一的选择。根据《航空周刊》5月1日的数据,美国有10家公司运营着125架波音747飞机,其中93架为波音747-400。在这些飞机中,有51架从事客运服务,主要由美联航和达美航空公司运营,其余42架用作货机。北美其他国家不运营波音747。     

对未发现故障的新见解

在飞行员报告的航空电子部件故障中,大约有三分之一在维修车间不能复现,因而无法进行故障的隔离和修理,这就是所谓的未发现故障(NFF),它是航空电子部件维修中极为常见的一个问题.     

Observations of the Galilean satellites of Jupiter from Earth orbit

In April 1972 OAO-2 obtained broadband filter measurements of the Galilean satellites from 2100 to 4300 Å. All four bodies were shown to have low albedos declining towards shorter wavelengths, thus constraining the proportions of their surfaces that could be covered by reflective frosts. Although the vast data return from Voyager spacecraft has for the first time permitted a detailed comparison of Galilean satellites with terrestrial planets, it has not removed the need for continuing long time-base observations of the former. Since January 1978, IUE has repeatedly obtained Galilean spectra within the range 1150 to 3200 Å. Observations of Io have placed an upper limit on the global abundance of SO₂ in its atmosphere. Spectral variations with phase have allowed spatial mapping of surface reflectance in the case of Io, and may enable volcanic activity to be monitored.     

Software assisted authoring and viewing of ISS crew procedures

The European Space Agency (ESA) initiated a joint project with the National Aeronautics and Space Administration (NASA) and industry partners for improved authoring and execution of Operations Data File (ODF) procedures. The system consists of an authoring tool and a viewer. The authoring tool is currently used by NASA and ESA to write/convert ODF procedures. The viewer will be used onboard the International Space Station (ISS) starting from Flight Increment 11. The new system, thanks to its interaction capability, will help astronauts and operators in the execution of checklist and logic flow procedures that ensure precise performance of experiments and smooth operation of the various systems.     

结构健康监控技术的发展现状

正使用传感器监测飞机结构的健康状况从原理上分析是一种非常有效的途径,而且如桑迪亚国家实验室和SMS公司等机构已经对一些真空比较监测传感器开展了广泛的飞行试验,因此,业内人士认为这种监测技术极具应用潜力,如可将非计划维修转化为计划性维修,或者代替耗时耗力的无损检测等。但无论开展哪种应用,均需获得局方的批准,而目前的形势是局方仍较为谨慎。