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Ad Hoc网中的移动数据库应用 被引量:2
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作者 范俊 李晓宇 《计算机工程》 CAS CSCD 2012年第17期49-51,55,共4页
传统的移动数据库模型应用到Ad Hoc网中,会带来通信代价增大等问题。为此,对传统的移动数据库模型进行改进,加入本地服务器作为中介,形成由移动主机、本地服务器和主服务器3类结点构成的移动数据库模型,并提出2个算法用来解决模型中本... 传统的移动数据库模型应用到Ad Hoc网中,会带来通信代价增大等问题。为此,对传统的移动数据库模型进行改进,加入本地服务器作为中介,形成由移动主机、本地服务器和主服务器3类结点构成的移动数据库模型,并提出2个算法用来解决模型中本地服务器与主服务器上的数据同步和事务重做问题,从而使移动主机能够高效正确地访问数据库。实验结果证明,该移动数据库模型具有较好的稳定性。 展开更多
关键词 AD HOC网 移动数据库模型 本地服务器 主服务器 过时数据 事务重做
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Real-time reliability evaluation based on damaged measurement degradation data 被引量:16
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作者 王小林 蒋平 +1 位作者 郭波 程志君 《Journal of Central South University》 SCIE EI CAS 2012年第11期3162-3169,共8页
A method was proposed to evaluate the real-time reliability for a single product based on damaged measurement degradation data.Most researches on degradation analysis often assumed that the measurement process did not... A method was proposed to evaluate the real-time reliability for a single product based on damaged measurement degradation data.Most researches on degradation analysis often assumed that the measurement process did not have any impact on the product's performance.However,in some cases,the measurement process may exert extra stress on products being measured.To obtain trustful results in such a situation,a new degradation model was derived.Then,by fusing the prior information of product and its own on-line degradation data,the real-time reliability was evaluated on the basis of Bayesian formula.To make the proposed method more practical,a procedure based on expectation maximization (EM) algorithm was presented to estimate the unknown parameters.Finally,the performance of the proposed method was illustrated by a simulation study.The results show that ignoring the influence of the damaged measurement process can lead to biased evaluation results,if the damaged measurement process is involved. 展开更多
关键词 degradation analysis damaged measurement real-time reliability expectation maximization algorithm
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Bitmap lattice index in road networks
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作者 Doohee Song Keun-Ho Lee Kwangjin Park 《Journal of Central South University》 SCIE EI CAS 2014年第10期3856-3863,共8页
A novel technique called the bitmap lattice index(BLI) is proposed, which combines the advantages of a wireless broadcasting environment with a road network. Existing road networks are based on the on-demand method: a... A novel technique called the bitmap lattice index(BLI) is proposed, which combines the advantages of a wireless broadcasting environment with a road network. Existing road networks are based on the on-demand method: a server's workload increases as the query request increases when a server sends a client information. To solve this problem, we propose the BLI. The BLI denotes an object and a node as 0 and 1 in the Hilbert curve(HC) map. The BLI can identify the position of a node and an object through bit information; it can also reduce the broadcasting frequency of a server by reducing the size of the index, thereby decreasing the access latency and query processing times. Moreover, the BLI is highly effective for data filtering, as it can identify the positions of both an object and a node. In a road network, if filtering is done via the Euclidean distance, it may result in an error. To prevent this, we add another validation procedure. The experiment is conducted by applying the BLI to kNN query, and the technique is assessed by a performance evaluation experiment. 展开更多
关键词 road network wireless broadcast spatial query bitmap lattice index(BLI)
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