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存储容量可扩展区块链系统的高效查询模型 被引量:38
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作者 贾大宇 信俊昌 +2 位作者 王之琼 郭薇 王国仁 《软件学报》 EI CSCD 北大核心 2019年第9期2655-2670,共16页
区块链技术是目前计算机领域的研究热点,其实现了去中心化,并且能够安全地存储数字信息,有效降低现实经济的信任成本.提出一种区块链存储容量可扩展模型的高效查询方法 ElasticQM.此查询模型由用户层、查询层、存储层和数据层这 4 个模... 区块链技术是目前计算机领域的研究热点,其实现了去中心化,并且能够安全地存储数字信息,有效降低现实经济的信任成本.提出一种区块链存储容量可扩展模型的高效查询方法 ElasticQM.此查询模型由用户层、查询层、存储层和数据层这 4 个模块组成.在用户层,模型将查询结果缓存,加快再次查询相同数据时的查询速度;在查询层,模型采用容量可扩展区块链模型的全局查询优化算法,增加了查询超级节点、查询验证节点和查询叶子节点这 3 种节点角色,提高了查询效率;在存储层,模型改进了区块链的容量可扩展模型 ElasticChain 的数据存储过程,实现了存储的可扩展性,并减少了占用的存储空间;在数据层,提出一种基于 B-M 树的区块链存储结构,并给出了B-M 树的建立算法和基于 B-M 树的查找算法,基于 B-M 树的存储结构,区块链会在进行块内局部查找时提高区块链的查询速度.最后,通过在多节点不同数据量的区块链中查询的实验结果表明,ElasticQM 查询方法具有高效的查询效率. 展开更多
关键词 区块链 查询算法 容量可扩展 B-M ElasticQM
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基于区块链技术的钢铁企业全流程数据管理 被引量:2
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作者 胡悦嫣 黄敏 +1 位作者 贾大宇 高哲明 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2022年第11期1552-1560,共9页
钢铁企业全流程数据的有效管理是实现实时决策的保障.现有全流程数据管理系统中心化严重,导致容灾性和安全性弱、效率低.本文利用区块链技术,对其账户机制进行改进,设计了钢铁全流程数据管理方案.首先,描述了全流程数据管理的业务需求... 钢铁企业全流程数据的有效管理是实现实时决策的保障.现有全流程数据管理系统中心化严重,导致容灾性和安全性弱、效率低.本文利用区块链技术,对其账户机制进行改进,设计了钢铁全流程数据管理方案.首先,描述了全流程数据管理的业务需求和难点;其次,采用实用拜占庭容错(practical Byzantine fault tolerance, PBFT)共识机制和智能合约技术,设计了基于联盟链的全流程数据管理系统结构模型;然后,针对传统区块链账户只有一种资产的弊端,提出了一种新的资产账户管理机制——多种资产账户,进而提出了相应的账户内资产转化算法和账户间资产交易算法;最后,对系统特征和效率进行了对比分析.结果表明,该系统与传统的中心化系统相比,安全性和容灾性较强,效率较高. 展开更多
关键词 钢铁全流程数据管理 联盟链 多种资产账户 账户内资产转化算法 账户间资产交易算法
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Research on Split Augmented Largrangian Shrinkage Algorithm in Magnetic Resonance Imaging Based on Compressed Sensing 被引量:2
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作者 ZHENG Qing-bin DONG En-qing +3 位作者 YANG Pei LIU Wei jia da-yu SUN Hua-kui 《Chinese Journal of Biomedical Engineering(English Edition)》 2014年第3期108-120,共13页
This paper aims to meet the requirements of reducing the scanning time of magnetic resonance imaging (MRI), accelerating MRI and reconstructing a high quality image from less acquisition data as much as possible. MR... This paper aims to meet the requirements of reducing the scanning time of magnetic resonance imaging (MRI), accelerating MRI and reconstructing a high quality image from less acquisition data as much as possible. MRI method based on compressed sensing (CS) with multiple regularizations (two regularizations including total variation (TV) norm and L1 norm or three regularizations consisting of total variation, L1 norm and wavelet tree structure) is proposed in this paper, which is implemented by applying split augmented lagrangian shrinkage algorithm (SALSA). To solve magnetic resonance image reconstruction problems with linear combinations of total variation and L1 norm, we utilized composite spht denoising (CSD) to split the original complex problem into TV norm and L1 norm regularization subproblems which were simple and easy to be solved respectively in this paper. The reconstructed image was obtained from the weighted average of solutions from two subprohlems in an iterative framework. Because each of the splitted subproblems can be regarded as MRI model based on CS with single regularization, and for solving the kind of model, split augmented lagrange algorithm has advantage over existing fast algorithm such as fast iterative shrinkage thresholding(FIST) and two step iterative shrinkage thresholding (TWIST) in convergence speed. Therefore, we proposed to adopt SALSA to solve the subproblems. Moreover, in order to solve magnetic resonance image reconstruction problems with linear combinations of total variation, L1 norm and wavelet tree structure, we can split the original problem into three subproblems in the same manner, which can be processed by existing iteration scheme. A great deal of experimental results show that the proposed methods can effectively reconstruct the original image. Compared with existing algorithms such as TVCMRI, RecPF, CSA, FCSA and WaTMRI, the proposed methods have greatly improved the quality of the reconstructed images and have better visual effect. 展开更多
关键词 magnetic resonance imaging (MRI) compressed sensing (CS) splitaugmented lagrangian total variation(TV) norm L1 norm
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