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591.
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
592.
本文在二维情况下针对SUS 310S型奥氏体不锈钢焊接接头,利用非线性热弹塑性有限元分析方法建立了焊缝在凝固时所受应力应变的计算模型。计算结果表明:焊缝金属在凝固过程中受到横向拉伸应变的作用;起始端部所受的应变较大;离端部一定距离后的焊缝所受的应变基本上相同;焊缝金属凝固结束时受到的拉伸应变约为0.4%。 相似文献
593.
Formation tracking control for time-delayed multi-agent systems with second-order dynamics 总被引:1,自引:0,他引:1
In this paper, formation tracking control problems for second-order multi-agent systems (MASs) with time-varying delays are studied, specifically those where the position and velocity of followers are designed to form a time-varying formation while tracking those of the leader. A neigh-boring relative state information based formation tracking protocol with an unknown gain matrix and time-varying delays is presented. The formation tracking problems are then transformed into asymptotically stable problems. Based on the Lyapunov-Krasovskii functional approach, condi-tions sufficient for second-order MASs with time-varying delays to realize formation tracking are examined. An approach to obtain the unknown gain matrix is given and, since neighboring relative velocity information is difficult to measure in practical applications, a formation tracking protocol with time-varying delays using only neighboring relative position information is introduced. The proposed results can be used on target enclosing problems for MASs with second-order dynamics and time-varying delays. An application for target enclosing by multiple unmanned aerial vehicles (UAVs) is given to demonstrate the feasibility of theoretical results. 相似文献
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利用田口稳健性设计方法的思想,从复杂铸件桥壳铸造工艺的系统设计入手,确定其浇注、激冷及补缩系统,并选定了七个全面且合适的可控因素完成了参数设计,确定了桥壳铸造工艺的最佳设计方案,而后利用质量损失函数对该最佳方案进行评价,通过华铸CAE/InteCAST模拟仿真手段及实际铸造生产的验证,进一步确认了该最佳工艺方案的稳定性和可靠性。 相似文献
596.
Development of a SAR digital system 总被引:1,自引:0,他引:1
Yeo T.S. Zhang C.B. Lu Y.H. Ren T. 《Aerospace and Electronic Systems Magazine, IEEE》1999,14(5):37-41
A data acquisition system for an airborne SAR (Synthetic Aperture Radar) was designed and implemented. DSP is used for the first time in the implementation of a SAR data acquisition system. A novel precision programmable timer using the DDS (Direct Digital Synthesis) technique was designed, built, and successfully tested to provide increased flexibility, reliability and stability 相似文献
597.
强化质量意识,搞好工程质量控制,工程质量的好坏,一定程度上反映出基建管理工作的水准,抓质量一刻不能忽视和松懈,本文重点介绍了我校近几年来保持建一个项目,创一个优良成绩的做法和体会。 相似文献
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