The color image segmentation problem has two main issues to be solved. The proper choice of a color model and the choice of an appropriate image model are the key issues in color image segmentation. In this work, Ohta...The color image segmentation problem has two main issues to be solved. The proper choice of a color model and the choice of an appropriate image model are the key issues in color image segmentation. In this work, Ohta (I<sub>1</sub>, I<sub>2</sub>, I<sub>3</sub>) is taken as the color model and different variants of Markov Random Field (MRF) models are proposed. In this regard, a Compound Markov Random Field (COMRF) model is porposed to take care of inter-color-plane and intra-color-plane interactions as well. In continuation to this model, a Constrained Compound Markov Random Field Model (CCOMRF) has been proposed to model the color images. The color image segmentation problem has been formulated in an unsupervised framework. The performance of the above proposed models has been compared with the standard MRF model and some of the state-of-the-art methods, and found to exhibit improved performance.展开更多
Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the compu...Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.展开更多
针对小波域多尺度马尔科夫随机场模型(Markov random field,MRF)对信息利用不充分的特点,在模型中引入模糊理论,提出了一种新的小波域多尺度MRF模型。新模型定义了相应的模糊概率场,通过模糊概率场描述每个小波域各尺度上像素的类别隶属...针对小波域多尺度马尔科夫随机场模型(Markov random field,MRF)对信息利用不充分的特点,在模型中引入模糊理论,提出了一种新的小波域多尺度MRF模型。新模型定义了相应的模糊概率场,通过模糊概率场描述每个小波域各尺度上像素的类别隶属度;根据模糊概率场估计了对应的特征场模型参数,参数的估计考虑了同尺度所有位置的特征信息;根据特征场模型导出了对应的示性场模型,用其反映每个像素的类别能量。利用贝叶斯准则给出了3步交互迭代算法,获得了分割结果。展开更多
超分辨率图像复原是当今一个重要的热门研究课题.鉴于双边滤波优良的噪声抑制性和鲁棒的边缘保持性,提出一种双边滤波导出的广义MRF(Markov random field)图像先验模型.广义MRF模型不仅继承了双边滤波在阶数大邻域中的双重异性加权机制...超分辨率图像复原是当今一个重要的热门研究课题.鉴于双边滤波优良的噪声抑制性和鲁棒的边缘保持性,提出一种双边滤波导出的广义MRF(Markov random field)图像先验模型.广义MRF模型不仅继承了双边滤波在阶数大邻域中的双重异性加权机制,且简洁地建立了双边滤波与Bayesian MAP(maximum a posterior)方法之间的理论联系.同时,由广义MRF模型导出了一种各向异性扩散PDE(partial differential equation)的改进数值解法.随后,在MRF-MAP框架下分别考虑高斯噪声和脉冲噪声两种情形,提出一种基于广义Huber-MRF模型的超分辨率复原算法,理论上保证具有严格全局最优解,并且利用半二次正则化思想和最速下降法求解相应的最小能量泛函.不论是视觉效果方面,还是峰值信噪比(PSNR)方面,实验结果都验证了广义Huber-MRF模型在超分辨图像复原中具有更强的噪声抑制性和边缘保持能力.展开更多
文摘The color image segmentation problem has two main issues to be solved. The proper choice of a color model and the choice of an appropriate image model are the key issues in color image segmentation. In this work, Ohta (I<sub>1</sub>, I<sub>2</sub>, I<sub>3</sub>) is taken as the color model and different variants of Markov Random Field (MRF) models are proposed. In this regard, a Compound Markov Random Field (COMRF) model is porposed to take care of inter-color-plane and intra-color-plane interactions as well. In continuation to this model, a Constrained Compound Markov Random Field Model (CCOMRF) has been proposed to model the color images. The color image segmentation problem has been formulated in an unsupervised framework. The performance of the above proposed models has been compared with the standard MRF model and some of the state-of-the-art methods, and found to exhibit improved performance.
基金Scientific Research Deanship,Taibah University Grant No.6363/436
文摘Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.
文摘针对小波域多尺度马尔科夫随机场模型(Markov random field,MRF)对信息利用不充分的特点,在模型中引入模糊理论,提出了一种新的小波域多尺度MRF模型。新模型定义了相应的模糊概率场,通过模糊概率场描述每个小波域各尺度上像素的类别隶属度;根据模糊概率场估计了对应的特征场模型参数,参数的估计考虑了同尺度所有位置的特征信息;根据特征场模型导出了对应的示性场模型,用其反映每个像素的类别能量。利用贝叶斯准则给出了3步交互迭代算法,获得了分割结果。
基金Supported by the Key Science-Technology Project of Trigonal Yangtse River of China under Grant No.BE2004400 (长三角联合攻关重 大科技项目)the National Natural Science Foundation of China under Grant No.60672074 (国家自然科学基金)+3 种基金the National High-Tech Research and Development Plan of China under Grant No.2007AA12E100 (国家高技术研究发展计划(863))the National Research Foundation for the Doctoral Program of Higher Education of China under Grant No.M200606018 (国家教育部博士点基金)the Natural Science Foundation of Jiangsu Province of China under Grant No.BK2006569 (江苏省自然科学基金)the Science- Technology Creation Plan for Graduate Students of Jiangsu Province of China (江苏省高校研究生科技创新计划)
文摘超分辨率图像复原是当今一个重要的热门研究课题.鉴于双边滤波优良的噪声抑制性和鲁棒的边缘保持性,提出一种双边滤波导出的广义MRF(Markov random field)图像先验模型.广义MRF模型不仅继承了双边滤波在阶数大邻域中的双重异性加权机制,且简洁地建立了双边滤波与Bayesian MAP(maximum a posterior)方法之间的理论联系.同时,由广义MRF模型导出了一种各向异性扩散PDE(partial differential equation)的改进数值解法.随后,在MRF-MAP框架下分别考虑高斯噪声和脉冲噪声两种情形,提出一种基于广义Huber-MRF模型的超分辨率复原算法,理论上保证具有严格全局最优解,并且利用半二次正则化思想和最速下降法求解相应的最小能量泛函.不论是视觉效果方面,还是峰值信噪比(PSNR)方面,实验结果都验证了广义Huber-MRF模型在超分辨图像复原中具有更强的噪声抑制性和边缘保持能力.
