将基于像素MRF分割方法拓展到基于地物目标几何约束的区域MRF分割,提出了一种基于区域和统计的纹理影像分割方法,其基本思想是利用Voronoi划分技术将影像域划分为若干子区域。在此基础上,采用二值高斯马尔科夫随机场(BGMRF,bivariate Ga...将基于像素MRF分割方法拓展到基于地物目标几何约束的区域MRF分割,提出了一种基于区域和统计的纹理影像分割方法,其基本思想是利用Voronoi划分技术将影像域划分为若干子区域。在此基础上,采用二值高斯马尔科夫随机场(BGMRF,bivariate Gaussian Markov random field)模型,静态随机场模型和Potts模型从邻域、区域及全局层次描述影像的纹理结构,并将该纹理结构模型纳入贝叶斯框架;依据贝叶斯定理构建纹理影像分割模型;利用metropolis-hastings(M-H)算法进行模型参数估计,并依据最大后验概率(MAP,maximum a posterior)准则进行优化,从而完成纹理影像分割。为了验证所提出方法的正确性,分别对合成纹理影像,真实纹理影像及遥感影像进行了分割实验,定性和定量的测试结果验证了提出方法的有效性、可靠性和准确性。展开更多
随着现代移动通信技术的发展以及智能手机、平板电脑的普及,移动GIS近年来成为GIS领域的技术热点。基于快速、高效、低成本的开发移动GIS系统的目的,采用以WeX5作为前端开发工具,ArcGIS Server为后端GIS平台,ArcGIS API for JavaScript...随着现代移动通信技术的发展以及智能手机、平板电脑的普及,移动GIS近年来成为GIS领域的技术热点。基于快速、高效、低成本的开发移动GIS系统的目的,采用以WeX5作为前端开发工具,ArcGIS Server为后端GIS平台,ArcGIS API for JavaScript作为前后端交互接口的开发方法,解决了地图的发布与调用,属性数据的统计、分析和展示,定位和导航等关键技术。在此基础上开发出了农村公路综合管理APP实例。展开更多
AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory ...AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.展开更多
文摘将基于像素MRF分割方法拓展到基于地物目标几何约束的区域MRF分割,提出了一种基于区域和统计的纹理影像分割方法,其基本思想是利用Voronoi划分技术将影像域划分为若干子区域。在此基础上,采用二值高斯马尔科夫随机场(BGMRF,bivariate Gaussian Markov random field)模型,静态随机场模型和Potts模型从邻域、区域及全局层次描述影像的纹理结构,并将该纹理结构模型纳入贝叶斯框架;依据贝叶斯定理构建纹理影像分割模型;利用metropolis-hastings(M-H)算法进行模型参数估计,并依据最大后验概率(MAP,maximum a posterior)准则进行优化,从而完成纹理影像分割。为了验证所提出方法的正确性,分别对合成纹理影像,真实纹理影像及遥感影像进行了分割实验,定性和定量的测试结果验证了提出方法的有效性、可靠性和准确性。
文摘随着现代移动通信技术的发展以及智能手机、平板电脑的普及,移动GIS近年来成为GIS领域的技术热点。基于快速、高效、低成本的开发移动GIS系统的目的,采用以WeX5作为前端开发工具,ArcGIS Server为后端GIS平台,ArcGIS API for JavaScript作为前后端交互接口的开发方法,解决了地图的发布与调用,属性数据的统计、分析和展示,定位和导航等关键技术。在此基础上开发出了农村公路综合管理APP实例。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61874161 and 11474105)the Science and Technology Program of Guangdong Province,China(Grant Nos.2017B010127001 and 2015B010105011)+4 种基金the Education Department Project of Guangdong Province,China(Grant No.2017KZDXM022)the Science and Technology Project of Guangzhou City,China(Grant No.201607010246)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(Grant No.IRT13064)the Science and Technology Project of Shenzhen City,China(Grant No.GJHZ20180416164721073)the Science and Technology Planning of Guangdong Province,China(Grant No.2015B010112002)
文摘AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.
