An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal ...An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.展开更多
This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecb...This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecbnology. HSCF, based on a file system filter driver, protects computer data and ensures their integrity and consistency with following three steps： access to open files, synchronization and copy on-write. Its strategies for improving system performance are analyzed including priority setting, incremental snapshot and load balance. HSCF is a new kind of snapshot technology to solve the data integrity and consistency problem in online backup, which is different from other storage-level snapshot and Open File Solution.展开更多
针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加...针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加入指针构成的凸点概念的基础上,分析了凸点集合具有的基本性质,并给出了利用凸点集合储存快照的相关算法,同时还给出了一种使用逆行代价改进CSNAP的方法.最后通过在实际工作负载和随机合成工作负载下的模拟实验说明了,在平均情况下,使用改进的CSNAP技术,可以将快照占用的储存空间减少到传统方法的10%以下.展开更多
动态地理信息系统(Spatial-Temporal Geographical Information System)是GIS的必然发展趋势,是实现动态数字地球的关键技术。静态3D GIS的技术已经成熟,而将时间维加上后形成4D的TGIS还处于数据模型研究阶段,主要原因是超海量数据的存...动态地理信息系统(Spatial-Temporal Geographical Information System)是GIS的必然发展趋势,是实现动态数字地球的关键技术。静态3D GIS的技术已经成熟,而将时间维加上后形成4D的TGIS还处于数据模型研究阶段,主要原因是超海量数据的存取和查询问题仍然没有完全解决。在对已存在的数据模型进行探讨并在此基础上进行深度综合研究,提出了新的观点:结合快照模型的简单易行性和面向对象模型的方便灵活性,同时避开快照模型的不一致性和冗余性,以及面向对象的复杂性,形成复合的基于快照方式的面向对象模型。它将是一种实用的TGIS数据模型,在对时间属性的处理方面采用独到的方法:首先按照时间片进行分层,建立一个基数据,然后通过快照方式产生缓冲数据,经过比较形成一个以对象变化为主的带有时间戳的新数据层,最后再通过其变化函数将离散的时间层连接起来,形成一个有机连续的数据库。这样,在数据存储方面,节省了很多空间;在查询分析方面,使以对象变化分层的数据算法更容易实现,同时可以实现对象的历史回放功能。此理论方法有效地对TGIS难点进行大胆探讨并通过自动元胞机理论(CA)予以证明。展开更多
文摘An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.
基金Supported by the National Natural Science Foun-dation of China (60473023) National Innovation Foundation forSmall Technology Based Firms(04C26214201280)
文摘This paper describes a method for building hot snapshot copy based on windows-file system （HSCF）. The architecture and running mechanism of HSCF are discussed after giving a comparison with other on-line backup tecbnology. HSCF, based on a file system filter driver, protects computer data and ensures their integrity and consistency with following three steps： access to open files, synchronization and copy on-write. Its strategies for improving system performance are analyzed including priority setting, incremental snapshot and load balance. HSCF is a new kind of snapshot technology to solve the data integrity and consistency problem in online backup, which is different from other storage-level snapshot and Open File Solution.
文摘针对传统连续数据保护技术中使用的快照存储技术难以高效存储足够多快照的问题,提出了一种新的快照存储技术,即基于凸点集合的快照存储技术(convex point SNAPshot,简称CSNAP).在讨论了CSNAP技术使用的数据结构,并引进了在数据结构中加入指针构成的凸点概念的基础上,分析了凸点集合具有的基本性质,并给出了利用凸点集合储存快照的相关算法,同时还给出了一种使用逆行代价改进CSNAP的方法.最后通过在实际工作负载和随机合成工作负载下的模拟实验说明了,在平均情况下,使用改进的CSNAP技术,可以将快照占用的储存空间减少到传统方法的10%以下.
文摘动态地理信息系统(Spatial-Temporal Geographical Information System)是GIS的必然发展趋势,是实现动态数字地球的关键技术。静态3D GIS的技术已经成熟,而将时间维加上后形成4D的TGIS还处于数据模型研究阶段,主要原因是超海量数据的存取和查询问题仍然没有完全解决。在对已存在的数据模型进行探讨并在此基础上进行深度综合研究,提出了新的观点:结合快照模型的简单易行性和面向对象模型的方便灵活性,同时避开快照模型的不一致性和冗余性,以及面向对象的复杂性,形成复合的基于快照方式的面向对象模型。它将是一种实用的TGIS数据模型,在对时间属性的处理方面采用独到的方法:首先按照时间片进行分层,建立一个基数据,然后通过快照方式产生缓冲数据,经过比较形成一个以对象变化为主的带有时间戳的新数据层,最后再通过其变化函数将离散的时间层连接起来,形成一个有机连续的数据库。这样,在数据存储方面,节省了很多空间;在查询分析方面,使以对象变化分层的数据算法更容易实现,同时可以实现对象的历史回放功能。此理论方法有效地对TGIS难点进行大胆探讨并通过自动元胞机理论(CA)予以证明。
