在偏序集上引入测度拓扑和全测度概念,研究其性质以及与其它内蕴拓扑间的众多关系。主要结果有:连续偏序集的测度拓扑实际上是由其上的任一全测度所决定且可由它的定向完备化上的测度拓扑和全测度分别限制得到;当连续偏序集还是D om a i...在偏序集上引入测度拓扑和全测度概念,研究其性质以及与其它内蕴拓扑间的众多关系。主要结果有:连续偏序集的测度拓扑实际上是由其上的任一全测度所决定且可由它的定向完备化上的测度拓扑和全测度分别限制得到;当连续偏序集还是D om a in时,其上的测度拓扑与μ拓扑一致;连续偏序集有可数基当且仅当其上的测度拓扑是可分的;一个网如果测度收敛则存在最终上确界;任一ω连续偏序集上都存在全测度。展开更多
针对低阶马尔科夫随机场(Markov random field, MRF)模型难以有效表达自然图像中复杂的先验知识而造成误分割问题,提出一种基于多节点拓扑重叠测度高阶MRF模型(Higher-order MRF model with multi-node topological overlap measure, MT...针对低阶马尔科夫随机场(Markov random field, MRF)模型难以有效表达自然图像中复杂的先验知识而造成误分割问题,提出一种基于多节点拓扑重叠测度高阶MRF模型(Higher-order MRF model with multi-node topological overlap measure, MTOM-HMRF)的图像分割方法.首先,为描述图像局部区域内多像素蕴含的复杂空间拓扑结构信息,利用多节点拓扑重叠测度建立图像局部区域的高阶先验模型;其次,利用较大的局部区域包含更多的标签节点信息能力,基于Pairwise MRF模型建立基于局部区域的部分二阶Potts先验模型,提高分割模型的抗噪能力;再次,为有效描述观察图像场与其标签场的似然特征分布,研究利用局部区域内邻接像素的Hamming距离引入图像局部空间相关性,建立局部空间一致性约束的高斯混合分布;最后,基于MRF框架建立用于图像分割的多节点拓扑重叠测度高阶MRF模型,采用Gibbs采样算法对提出模型进行优化.实验结果表明,提出模型不仅能有效抵抗图像强噪声和复杂的纹理突变干扰,鲁棒性更好,而且具有更准确的图像分割结果.展开更多
Because SQL for querying data from spatial databa se s is ineffective, the query based on natural or visual language becomes an attra ctive research field gradually. However, how to define and represent natural lan gu...Because SQL for querying data from spatial databa se s is ineffective, the query based on natural or visual language becomes an attra ctive research field gradually. However, how to define and represent natural lan guages related to spatial data are still gigantic problems. Because existing mod els of direction relations can’t describe by use of some common concepts. First of all, detailed direction relations are proposed to describe the directions re lated to the interior of spatial objects, such as "east part of a region","ea st boundary of a region", and so on. Secondly, by integrating the detailed dire ctions with exterior direction relations and topological relations, several NLSR s are defined, such as "a road goes across the east part of a lake", "a river goes along the east boundary of a province", etc. Finally, based on the NLSRs abovementioned, a natural spatial query language (NSQL) is formed to retrieve da ta from spatial databases.展开更多
In order to study the response of collision speed caused by the large bus to new flexible barrier,in this paper,with the large bus as the carrier,the full-scale impact tests between flexible barrier and vehicle with t...In order to study the response of collision speed caused by the large bus to new flexible barrier,in this paper,with the large bus as the carrier,the full-scale impact tests between flexible barrier and vehicle with the impact velocities of 40 km/h and 60 km/h were carried out separately,following the procedures of the test preparation,test processing,data acquisition, etc,which were based on the test platform of the Large Structure Crash Testing Laboratory of Changsha University of Science and Technology. The important test results which contain the damage of vehicles and barrier,the moving locus of vehicle,the occupant risk index,the maximum dynamic deformation, etc,were obtained through the analysis under the different collision speeds. These provide the necessary reference basis for the further research on the structure topology optimization and improve the comprehensive constraint performance to the flexible barrier.展开更多
We introduce and study the relation between Pesin-Pitskel topological pressure on an arbitrary subset and measure theoretic pressure of Borel probability measure for nonautonomous dynamical systems,which is an extensi...We introduce and study the relation between Pesin-Pitskel topological pressure on an arbitrary subset and measure theoretic pressure of Borel probability measure for nonautonomous dynamical systems,which is an extension of the classical definition of Bowen topological entropy.We show that the Pesin-Pitskel topological pressure can be determined by the local pressures of measures in nonautonomous case and establish a variational principle for Pesin-Pitskel topological pressure on compact subsets in the context of nonautonomous dynamical systems.展开更多
A quantum-spin-Hall （QSH） state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Two- dimensional topological insulators are critically important...A quantum-spin-Hall （QSH） state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Two- dimensional topological insulators are critically important for realizing novel topological applications. Using density functional theory （DFT）, we demonstrated that hydrogenated GaBi bilayers （HGaBi） form a stable topological insulator with a large nontrivial band gap of 0.320 eV, based on the state-of-the-art hybrid functional method, which is implementable for achieving QSH states at room temperature. The nontrivial topological property of the HGaBi lattice can also be confirmed from the appearance of gapless edge states in the nanoribbon structure. Our results provide a versatile platform for hosting nontrivial topological states usable for important nanoelectronic device applications.展开更多
文摘在偏序集上引入测度拓扑和全测度概念,研究其性质以及与其它内蕴拓扑间的众多关系。主要结果有:连续偏序集的测度拓扑实际上是由其上的任一全测度所决定且可由它的定向完备化上的测度拓扑和全测度分别限制得到;当连续偏序集还是D om a in时,其上的测度拓扑与μ拓扑一致;连续偏序集有可数基当且仅当其上的测度拓扑是可分的;一个网如果测度收敛则存在最终上确界;任一ω连续偏序集上都存在全测度。
文摘针对低阶马尔科夫随机场(Markov random field, MRF)模型难以有效表达自然图像中复杂的先验知识而造成误分割问题,提出一种基于多节点拓扑重叠测度高阶MRF模型(Higher-order MRF model with multi-node topological overlap measure, MTOM-HMRF)的图像分割方法.首先,为描述图像局部区域内多像素蕴含的复杂空间拓扑结构信息,利用多节点拓扑重叠测度建立图像局部区域的高阶先验模型;其次,利用较大的局部区域包含更多的标签节点信息能力,基于Pairwise MRF模型建立基于局部区域的部分二阶Potts先验模型,提高分割模型的抗噪能力;再次,为有效描述观察图像场与其标签场的似然特征分布,研究利用局部区域内邻接像素的Hamming距离引入图像局部空间相关性,建立局部空间一致性约束的高斯混合分布;最后,基于MRF框架建立用于图像分割的多节点拓扑重叠测度高阶MRF模型,采用Gibbs采样算法对提出模型进行优化.实验结果表明,提出模型不仅能有效抵抗图像强噪声和复杂的纹理突变干扰,鲁棒性更好,而且具有更准确的图像分割结果.
文摘Because SQL for querying data from spatial databa se s is ineffective, the query based on natural or visual language becomes an attra ctive research field gradually. However, how to define and represent natural lan guages related to spatial data are still gigantic problems. Because existing mod els of direction relations can’t describe by use of some common concepts. First of all, detailed direction relations are proposed to describe the directions re lated to the interior of spatial objects, such as "east part of a region","ea st boundary of a region", and so on. Secondly, by integrating the detailed dire ctions with exterior direction relations and topological relations, several NLSR s are defined, such as "a road goes across the east part of a lake", "a river goes along the east boundary of a province", etc. Finally, based on the NLSRs abovementioned, a natural spatial query language (NSQL) is formed to retrieve da ta from spatial databases.
基金National Natural Science Foundation of China(No.51175050)
文摘In order to study the response of collision speed caused by the large bus to new flexible barrier,in this paper,with the large bus as the carrier,the full-scale impact tests between flexible barrier and vehicle with the impact velocities of 40 km/h and 60 km/h were carried out separately,following the procedures of the test preparation,test processing,data acquisition, etc,which were based on the test platform of the Large Structure Crash Testing Laboratory of Changsha University of Science and Technology. The important test results which contain the damage of vehicles and barrier,the moving locus of vehicle,the occupant risk index,the maximum dynamic deformation, etc,were obtained through the analysis under the different collision speeds. These provide the necessary reference basis for the further research on the structure topology optimization and improve the comprehensive constraint performance to the flexible barrier.
基金Supported by NSFC(Nos.11971236,11901419)the Foundation in Higher Education Institutions of Henan Province(No.23A110020)。
文摘We introduce and study the relation between Pesin-Pitskel topological pressure on an arbitrary subset and measure theoretic pressure of Borel probability measure for nonautonomous dynamical systems,which is an extension of the classical definition of Bowen topological entropy.We show that the Pesin-Pitskel topological pressure can be determined by the local pressures of measures in nonautonomous case and establish a variational principle for Pesin-Pitskel topological pressure on compact subsets in the context of nonautonomous dynamical systems.
文摘A quantum-spin-Hall （QSH） state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Two- dimensional topological insulators are critically important for realizing novel topological applications. Using density functional theory （DFT）, we demonstrated that hydrogenated GaBi bilayers （HGaBi） form a stable topological insulator with a large nontrivial band gap of 0.320 eV, based on the state-of-the-art hybrid functional method, which is implementable for achieving QSH states at room temperature. The nontrivial topological property of the HGaBi lattice can also be confirmed from the appearance of gapless edge states in the nanoribbon structure. Our results provide a versatile platform for hosting nontrivial topological states usable for important nanoelectronic device applications.
