Information extraction from thematic mapper data

The Landsat-4 spacecraft, launched on July 9, 1982, is equipped with a new electro-optical sensor expected to advance the remote sensing capabilities of Earth resources satellites. An experimental instrument, the thematic mapper (TM), provides data in seven discrete energy bands with greatly improved spectral, spatial and radiometric resolution, relative to previous Landsat satellite systems. Scientists at NASA, National Space Technology Laboratories (NSTL), Earth Resources Laboratory (ERL) conducted an evaluation of Landsat-4 TM data, soon after its launch, to examine the potential of this new electro-optical sensor for providing improved information for renewable resources and land cover studies. Investigations of TM data included forested wetland, urban and agricultural land covers using a scene of data collected over Arkansas and Tennessee on August 22, 1982. Standard digital information extraction techniques were employed, and the classification accuracies achieved with a single date TM data set exceeded a 90% correct confidence level. While only spectral analysis techniques were utilized for this initial evaluation, the results clearly indicate the improved performance provided by the experimental TM sensor over previous Earth observing capabilities.     

Beamspace ML bearing estimation incorporating low-angle geometry

A problem in low-angle radar tracking, namely, bearing estimation in the presence of a strong specular multipath component that arrives within the beamwidth of the direct path signal, is studied. Three-dimensional beamspace domain maximum likelihood (3D-BDML) is a computationally simple ML bearing estimation algorithm applicable in this scenario which operates in a 3-D beamspace. A variation of 3D-BDML incorporating the multipath geometry as a priori information is presented. In symmetric 3D-BDML the pointing angle of the center beam is equal to the bisector angle between the direct path ray and the image ray, which may be estimated a priori given only the radar height and the target range. The effect of the inclusion of a priori information on the performance of 3D-BDML is analyzed in terms of the dependence on the relative phase difference between the direct and specular path signals, the sensitivity to error in the bisector angle estimate, and the results of operation when no specular multipath component is present in the data. In addition, computationally simple schemes for coherently incorporating multifrequency data into 3D-BDML are investigated     

航空航天复合材料应用的最新进展

文章介绍了先进复合材料的最新进展情况,内容包括用于最新复合材料体系的各种增强纤维、树脂基体,及复合材料结构设计的一些新概念。重点介绍了低成本和高效的制造技术。复合材料重要结构件的制造技术在不断改进,制造出的部件不仅精度和强度更高,而且更显成本效益。文章还介绍了航空航天领域一些新研发的复合材料结构件。     

The cost benefits of the Spacelab system to scientific investigations and space applications

In the past, one of the major problems in performing scientific investigations in space has been the high cost of developing, integrating, and transporting scientific experiments into space. The limited resources of unmanned spacecraft, coupled with the requirements for completely automated operations, was another factor contributing to the high costs of scientific research in space. In previous space missions after developing, integrating and transporting costly experiments into space and obtaining successful data, the experiment facility and spacecraft have been lost forever, because they could not be returned to earth. The objective of this paper is to present how the utilization of the Spacelab System will result in cost benefits to the scientific community, and significantly reduce the cost of space operations from previous space programs.The following approach was used to quantify the cost benefits of using the Spacelab System to greatly reduce the operational costs of scientific research in space. An analysis was made of the series of activities required to combine individual scientific experiments into an integrated payload that is compatible with the Space Transportation System (STS). These activities, including Shuttle and Spacelab integration, communications and data processing, launch support requirements, and flight operations were analyzed to indicate how this new space system, when compared with previous space systems, will reduce the cost of space research. It will be shown that utilization of the Spacelab modular design, standard payload interfaces, optional Mission Dependent Equipment (MDE), and standard services, such as the Experiment Computer Operating System (ECOS), allow the user many more services than previous programs, at significantly lower costs. In addition, the missions will also be analyzed to relate their cost benefit contributions to space scientific research.The analytical tools that are being developed at MSFC in the form of computer programs that can rapidly analyze experiment to Spacelab interfaces will be discussed to show how these tools allow the Spacelab integrator to economically establish the payload compatibility of a Spacelab mission.The information used in this paper has been assimilated from the actual experience gained in integrating over 50 highly complex, scientific experiments that will fly on the Spacelab first and second missions. In addition, this paper described the work being done at the Marshall Space Flight Center (MSFC) to define the analytical integration tools and techniques required to economically and efficiently integrate a wide variety of Spacelab payloads and missions. The conclusions reached in this study are based on the actual experience gained at MSFC in its roles of Spacelab integration and mission managers for the first three Spacelab missions. The results of this paper will clearly show that the cost benefits of the Spacelab system will greatly reduce the costs and increase the opportunities for scientific investigation from space.     

Seismo-ionospheric anomalies in total electron content of the GIM and electron density of DEMETER before the 27 February 2010 M8.8 Chile earthquake

In this paper we examine the pre-earthquake ionospheric anomalies by the total electron content (TEC) extracted from GIM (global ionospheric map) and the electron density (Ne) observed by the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite during the 2010 M8.8 Chile earthquake. Temporal variations show the nighttime TEC and Ne simultaneously increase 9–19 days before the earthquake. A cross-comparison of data recorded during the period of 1 February to 3 March in 2006–2010 confirms the above temporal anomalies specifically appear in 2010. The spatial analyses show that the anomalies tend to appear over the epicenter.     

ISO 9000 认证所带来的利益及质量管理之发展(英文)

本文总结了９项有关ＩＳＯ９０００认证的研究,主要论述了这套国际标准为实施者所带来之利益。这９项研究分别在英国、新西兰、澳大利亚、中国香港特区、美国、巴西、加拿大、法国、德国、日本、韩国、瑞典和荷兰等地进行。研究发现,ＩＳＯ９０００的主要优点有：令运作方式系统化、减少损耗、增加效率和减少顾客投诉。取得ＩＳＯ９０００认证的公司,大多采取较严格的方法去控制分供方。不少取得证书的公司还表示,他们会进一步采用其他的质量管理方法,例如全面优质管理,ＩＳＯ９０００,ＩＳＯ１４０００和优质奖的规格。     

关于航空公司对OEM客户服务满意度的调查

<正>2018年,《航空周刊》和AeroD ynamic咨询公司首次联合开展了《对OEM客户服务满意度的调查》,在给OEM的工作带来一定压力的同时,也为OEM在售后服务方面的改进指出了明确的方向,反响很好。今年,这一调查仍在继续并得出了一些不一样的结果,如空客的整体得分较去年有所提高、巴航工业的