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This paper presents current accomplishments in the development of a high performance, high g, tactical accelerometer for use in the Advanced Kinetic Energy Missile (AdKEM) development program being conducted by the US Army Missile Command. The design goals of the accelerometer are to provide strapdown tactical navigation quality acceleration information throughout a 20 g soft launch phase, 1200 g boost phase, and low-g coast phase environment. The accelerometers must be able to provide acceleration measurements accurate enough to provide a navigational accuracy of 0.5 meter CEP at 500 meters. This translates to an accelerometer capable of measuring a 1200 g acceleration with a resolution of 1 milli-g. The AdKEM missile accelerometer and gyro outputs are used for control stability and midcourse guidance. The successful demonstration of this device offers a myriad of opportunities in both the commercial and military arenas. The operational environment and performance characteristics of the AdKEM accelerometer are presented. Crystalline quartz vibrating beam technology has been chosen for this accelerometer application to take advantage of solid state device characteristics. A solid state device with inherently digital output characteristics is desirable for strapdown navigation applications because of interface circuitry simplification, potential lower cost, inherent stability and longer storage life 相似文献
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Hsuan Ren Qian Du Jing Wang Chein-I Chang Jensen J.O. Jensen J.L. 《IEEE transactions on aerospace and electronic systems》2006,42(4):1372-1385
Due to recent advances in hyperspectral imaging sensors many subtle unknown signal sources that cannot be resolved by multispectral sensors can be now uncovered for target detection, discrimination, and identification. Because the information about such sources is generally not available, automatic target recognition (ATR) presents a great challenge to hyperspectral image analysts. Many approaches developed for ATR are based on second-order statistics in the past years. This paper investigates ATR techniques using high order statistics. For ATR in hyperspectral imagery, most interesting targets usually occur with low probabilities and small population and they generally cannot be described by second-order statistics. Under such circumstances, using high-order statistics to perform target detection have been shown by experiments in this paper to be more effective than using second order statistics. In order to further address a challenging issue in determining the number of signal sources needed to be detected, a recently developed concept of virtual dimensionality (VD) is used to estimate this number. The experiments demonstrate that using high-order statistics-based techniques in conjunction with the VD to perform ATR are indeed very effective 相似文献
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This document outlines the objectives, strategy guidelines, and the approach for the harmonisation of European space technology activities, in line with and in support of the resolution “Shaping of the Future of Europe in Space”, adopted at the ESA Ministerial Council in May 1999.Under an overall ESA co-ordination, the European space sector is elaborating a technology strategy based on top-level priorities (Dossier 0), on the mapping of European development and competences and on a co-ordinated Space Technology Master Plan (ESTMP). This plan shall take into account the various European developments, industry capacities and budgets and shall enhance the complementary role of the various partners towards common objectives.The proposed strategy includes selection of priority activities as pilot projects for harmonisation. For these pre-selected pilot projects, agreements are required on responsibilities, leaderships, partnerships and budget commitments. 相似文献
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R S Bandurski A Schulze P Jensen M Desrosiers B Epel S Kowalczyk 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(1):203-210
Zea mays (sweet corn) seedlings attain an asymmetric distribution of the growth hormone indole-3-acetic acid (IAA) within 3 minutes following a gravity stimulus. Both free and esterified IAA (that is total IAA) accumulate to a greater extent in the lower half of the mesocotyl cortex of a horizontally placed seedling than in the upper half. Thus, changes in the ratio of free IAA to ester IAA cannot account for the asymmetric distribution. Our studies demonstrate there is no de novo synthesis of IAA in young seedlings. We conclude that asymmetric IAA distribution is attained by a gravity-induced, potential-regulated gating of the movement of IAA from kernel to shoot and from stele to cortex. As a working theory, which we call the Potential Gating Theory, we propose that perturbation of the plant's bioelectric field, induced by gravity, causes opening and closing of transport channels in the plasmodesmata connecting the vascular stele to the surrounding cortical tissues. This results in asymmetric growth hormone distribution which results in the asymmetric growth characteristics of the gravitropic response. 相似文献