To get the high compression ratio as well as the high-quality reconstructed image, an effective image compression scheme named irregular segmentation region coding based on spiking cortical model（ISRCS） is presented...To get the high compression ratio as well as the high-quality reconstructed image, an effective image compression scheme named irregular segmentation region coding based on spiking cortical model（ISRCS） is presented. This scheme is region-based and mainly focuses on two issues. Firstly, an appropriate segmentation algorithm is developed to partition an image into some irregular regions and tidy contours, where the crucial regions corresponding to objects are retained and a lot of tiny parts are eliminated. The irregular regions and contours are coded using different methods respectively in the next step. The other issue is the coding method of contours where an efficient and novel chain code is employed. This scheme tries to find a compromise between the quality of reconstructed images and the compression ratio. Some principles and experiments are conducted and the results show its higher performance compared with other compression technologies, in terms of higher quality of reconstructed images, higher compression ratio and less time consuming.展开更多
An improved approach for J-value segmentation （JSEG） is presented for unsupervised color image segmentation. Instead of color quantization algorithm, an automatic classification method based on adaptive mean shift ...An improved approach for J-value segmentation （JSEG） is presented for unsupervised color image segmentation. Instead of color quantization algorithm, an automatic classification method based on adaptive mean shift （AMS） based clustering is used for nonparametric clustering of image data set. The clustering results are used to construct Gaussian mixture modelling （GMM） of image data for the calculation of soft J value. The region growing algorithm used in JSEG is then applied in segmenting the image based on the multiscale soft J-images. Experiments show that the synergism of JSEG and the soft classification based on AMS based clustering and GMM overcomes the limitations of JSEG successfully and is more robust.展开更多
针对在GPS信号弱/拒止和环境感知欠缺的环境下可重构海洋浮体的协同控制问题,本文提出了一种基于定相对位姿(Determined relative pose,DRP)视觉伺服模型的鲁棒非线性模型预测控制(Nonlinear model predictive control,NMPC)方案。可重...针对在GPS信号弱/拒止和环境感知欠缺的环境下可重构海洋浮体的协同控制问题,本文提出了一种基于定相对位姿(Determined relative pose,DRP)视觉伺服模型的鲁棒非线性模型预测控制(Nonlinear model predictive control,NMPC)方案。可重构海洋浮体的视觉伺服问题难点主要包括环境干扰强、系统非线性程度高、视觉伺服易陷入局部极值和可见性约束强。为应对这些难题,该视觉伺服控制策略需要实现:被控船仅依靠视觉信息进行多船协同控制;视觉伺服模型收敛性好;控制器具有一定鲁棒性且处理非线性系统和约束条件的能力强。为此,本研究首先建立了单浮体的动力学模型;然后将视觉模型、被控船艏摇信息及相机云台转角信息整合到系统状态中,形成了DRP模型,从而保证了双浮体视觉伺服控制结束后相对位姿的唯一性;接着结合浮体动力学模型和DRP模型,建立了基于图像的视觉伺服(Image based visual servo,IBVS)的系统模型,并对该系统模型进行分析,进而据此设计了鲁棒的NMPC控制器,以保证视觉伺服任务可以在强外界干扰的环境下进行;最后通过大量数值仿真实验验证了该方案的有效性。这些实验结果不仅证明了控制策略的稳定性和准确性,还展示了其在复杂环境下的鲁棒性能。展开更多
为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接...为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接口来构建包含软件功能、运行流程、数据处理等内容的应用程序。应用低代码软件平台,降低了软件开发的复杂性,满足装备快速升级的需求,研制时间较传统方法缩短了近45%。展开更多
基金supported by the National Science Foundation of China(60872109)the Program for New Century Excellent Talents in University(NCET-06-0900)
文摘To get the high compression ratio as well as the high-quality reconstructed image, an effective image compression scheme named irregular segmentation region coding based on spiking cortical model（ISRCS） is presented. This scheme is region-based and mainly focuses on two issues. Firstly, an appropriate segmentation algorithm is developed to partition an image into some irregular regions and tidy contours, where the crucial regions corresponding to objects are retained and a lot of tiny parts are eliminated. The irregular regions and contours are coded using different methods respectively in the next step. The other issue is the coding method of contours where an efficient and novel chain code is employed. This scheme tries to find a compromise between the quality of reconstructed images and the compression ratio. Some principles and experiments are conducted and the results show its higher performance compared with other compression technologies, in terms of higher quality of reconstructed images, higher compression ratio and less time consuming.
文摘An improved approach for J-value segmentation （JSEG） is presented for unsupervised color image segmentation. Instead of color quantization algorithm, an automatic classification method based on adaptive mean shift （AMS） based clustering is used for nonparametric clustering of image data set. The clustering results are used to construct Gaussian mixture modelling （GMM） of image data for the calculation of soft J value. The region growing algorithm used in JSEG is then applied in segmenting the image based on the multiscale soft J-images. Experiments show that the synergism of JSEG and the soft classification based on AMS based clustering and GMM overcomes the limitations of JSEG successfully and is more robust.
文摘针对在GPS信号弱/拒止和环境感知欠缺的环境下可重构海洋浮体的协同控制问题,本文提出了一种基于定相对位姿(Determined relative pose,DRP)视觉伺服模型的鲁棒非线性模型预测控制(Nonlinear model predictive control,NMPC)方案。可重构海洋浮体的视觉伺服问题难点主要包括环境干扰强、系统非线性程度高、视觉伺服易陷入局部极值和可见性约束强。为应对这些难题,该视觉伺服控制策略需要实现:被控船仅依靠视觉信息进行多船协同控制;视觉伺服模型收敛性好;控制器具有一定鲁棒性且处理非线性系统和约束条件的能力强。为此,本研究首先建立了单浮体的动力学模型;然后将视觉模型、被控船艏摇信息及相机云台转角信息整合到系统状态中,形成了DRP模型,从而保证了双浮体视觉伺服控制结束后相对位姿的唯一性;接着结合浮体动力学模型和DRP模型,建立了基于图像的视觉伺服(Image based visual servo,IBVS)的系统模型,并对该系统模型进行分析,进而据此设计了鲁棒的NMPC控制器,以保证视觉伺服任务可以在强外界干扰的环境下进行;最后通过大量数值仿真实验验证了该方案的有效性。这些实验结果不仅证明了控制策略的稳定性和准确性,还展示了其在复杂环境下的鲁棒性能。
文摘为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接口来构建包含软件功能、运行流程、数据处理等内容的应用程序。应用低代码软件平台,降低了软件开发的复杂性,满足装备快速升级的需求,研制时间较传统方法缩短了近45%。
