• 제목/요약/키워드: National Defense and Aerospace

검색결과 241건 처리시간 0.023초

Modified nonlinear force density method for form-finding of membrane SAR antenna

  • Xu, Rui;Li, DongXu;Liu, Wang;Jiang, JianPing;Liao, YiHuan;Wang, Jie
    • Structural Engineering and Mechanics
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    • 제54권6호
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    • pp.1045-1059
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    • 2015
  • Form-finding for cable-membrane structures is a delicate operation. During the last decades, the force density method (FDM) was considered to be an efficient method to address the problem. Many researchers were devoted to improving this method and proposed many methods such as natural force density method (NFDM), improved nonlinear force density method (INFDM), et al. In this paper, a modified nonlinear force density method (MNFDM) is proposed. In this method, the stresses of membrane elements were transformed to the force-densities of cable nets by an equivalent relationship, and then they can be used as initial conditions. By comparing with the forming finding results by using the FDM, NFDM, INFDM and MNFDM, it had demonstrated that the MNFDM presented in this paper is the most efficient and precise.

On an Air-To-Sea Guided Bomb

  • Takano, Hiroyuki;Baba, Yoriaki;Takao, Kichiro
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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    • pp.462-467
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    • 1993
  • Even nowadays ships on the sea are important strategic base for aircraft and missiles. Thus we have been studying an unmanned attack system against ships recently. We experienced severa problems when this system was simulated on the computer. In this paper, problems and solutions of an Air-To-Sea Guided Bomb for this system are presented.

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FLIGHT TRAJECTORY CONTOLLER FOR NONLINEAR MANEUVER(GENERATION OF A DESIRED TRAJECTORY BY SPLINE THEORY)

  • Baba, Yoriaki;Takano, Hiroyuki;Sano, Masaki
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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    • pp.376-379
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    • 1995
  • To force an aircraft to track the specified path, the generation of the smooth desired trajectory is essential. In this paper, the cubic spline function is used to generate the trajectory which passes through the specified intercept points. The simulation results show that the desired trajectory generated by the spline interpolation is very smooth and the aircraft tracks it with small position errors.

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비디오 비트율 제어 기술의 최신 동향 분석과 국방 및 항공우주 영상시스템의 비트율 제어 기술 발전 방향 전망 (A Study on the Latest Trends of Video Bit-Rate Control Technology and Prospects for the Development of Bit-Rate Control Technology in Defense and Aerospace Imaging Systems)

  • 현명한
    • 한국군사과학기술학회지
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    • 제27권6호
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    • pp.703-713
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    • 2024
  • Video bit-rate control techniques are essential for efficiently transmitting videos over communication networks. These techniques have been pivotal in broadcasting and internet streaming services, and they could significantly enhance defense capabilities if applied to defense and aerospace imaging systems. Therefore, this paper first reviews the history and standard technologies of video coding, then describes the standard trends of the latest video coding technologies. Finally, it outlines the features of the latest video bit-rate control techniques and discusses their applicability in the defense and aerospace fields.

Size Aware Correlation Filter Tracking with Adaptive Aspect Ratio Estimation

  • Zhu, Xiaozhou;Song, Xin;Chen, Xiaoqian;Bai, Yuzhu;Lu, Huimin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제11권2호
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    • pp.805-825
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    • 2017
  • Correlation Filter-based Trackers (CFTs) gained popularity recently for their effectiveness and efficiency. To deal with the size changes of the target which may degenerate the tracking performance, scale estimation has been introduced in existing CFTs. However, the variations of the aspect ratio were usually neglected, which also influence the size of the target. In this paper, Size Aware Correlation Filter Trackers (SACFTs) are proposed to deal with this problem. The SACFTs not only determine the translation and scale variations, but also take the aspect ratio changes into consideration, thus a better estimation of the size of the target can be realized, which improves the overall tracking performance. And competing results can be achieved compared with state-of-the-art methods according to the experiments conducted on two large scale datasets.

Unsupervised Single Moving Object Detection Based on Coarse-to-Fine Segmentation

  • Zhu, Xiaozhou;Song, Xin;Chen, Xiaoqian;Lu, Huimin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권6호
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    • pp.2669-2688
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    • 2016
  • An efficient and effective unsupervised single moving object detection framework is presented in this paper. Given the sparsely labelled trajectory points, we adopt a coarse-to-fine strategy to detect and segment the foreground from the background. The superpixel level coarse segmentation reduces the complexity of subsequent processing, and the pixel level refinement improves the segmentation accuracy. A distance measurement is devised in the coarse segmentation stage to measure the similarities between generated superpixels, which can then be used for clustering. Moreover, a Quadmap is introduced to facilitate the refinement in the fine segmentation stage. According to the experiments, our algorithm is effective and efficient, and favorable results can be achieved compared with state-of-the-art methods.

Flexible camera series network for deformation measurement of large scale structures

  • Yu, Qifeng;Guan, Banglei;Shang, Yang;Liu, Xiaolin;Li, Zhang
    • Smart Structures and Systems
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    • 제24권5호
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    • pp.587-595
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    • 2019
  • Deformation measurement of large scale structures, such as the ground beds of high-rise buildings, tunnels, bridge, and railways, are important for insuring service quality and safety. The pose-relay videometrics method and displacement-relay videometrics method have already presented to measure the pose of non-intervisible objects and vertical subsidence of unstable areas, respectively. Both methods combine the cameras and cooperative markers to form the camera series networks. Based on these two networks, we propose two novel videometrics methods with closed-loop camera series network for deformation measurement of large scale structures. The closed-loop camera series network offers "closed-loop constraints" for the camera series network: the deformation of the reference points observed by different measurement stations is identical. The closed-loop constraints improve the measurement accuracy using camera series network. Furthermore, multiple closed-loops and the flexible combination of camera series network are introduced to facilitate more complex deformation measurement tasks. Simulated results show that the closed-loop constraints can enhance the measurement accuracy of camera series network effectively.

One optimization on the flight trajectories of re-entry vehicle

  • Takano, Hiroyuki;Nakamura, Kazuki;Baba, Yoriaki
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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    • pp.307-310
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    • 1996
  • In this paper, we deal with some numerical analyses of a re-entry vehicle in a 2-dimensional plane as an optimal control problem. To reduce the dynamic load, the heat load and the oscillation in the trajectory, we researched the trajectories in which the load factor or the rate of flight path angle was minimized during re-entry. In addition to that, taking advantage of the monotonous subarc method and the folded time-axis method, we tried to find the heat-less and load-less trajectory with combinations of some sectional functionals so that we can achieve more comfortability.

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On the 3-dimensional low speed yo-yo maneuver

  • Takano, Hiroyuki;Sato, Masaya;Baba, Yoriaki
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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    • pp.653-658
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    • 1994
  • This paper presents numerical analyses of the low speed yo-yo maneuver of an aircraft to determine controls of thrust, bank-angle and angle-of-attack in the subsonic region in terms of the optimal control theory. Minimum-time flight paths are numerically calculated to overtake an opponent aircraft flying in some steady-state level turnings under several assumptions: both of aircraft are point masses and maneuver in the 3-Dimensional space. Their weights are considered constant in the maneuver. As a result of the analyses, the effectiveness of the low speed yo-yo maneuver is shown.

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Development of MATLAB GUI Based Software for Monitoring Ionospheric Disturbances

  • Kim, Bu-Gyeom;Kang, Seonho;Han, Deokhwa;Song, Junesol;So, Hyoungmin;Kim, Kap Jin;Kee, Changdon
    • Journal of Positioning, Navigation, and Timing
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    • 제8권2호
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    • pp.69-77
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    • 2019
  • This study introduces MATLAB Graphical User Interface (GUI)-based software to monitor ionospheric disturbances. This software detects ionospheric disturbances using Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) measurements, and estimates a location of the disturbance source through the detected disturbance. In addition, this software includes a sky plot making function and frequency analysis function through wavelet transform. To evaluate the performance of the developed software, data of 2011 Tohoku earthquake in Japan were analyzed by using the software. The analysis results verified that the ionospheric disturbances were detected through GPS and GLONASS measurements, and the location of the disturbance source was estimated through the detected disturbance.