为了解决机器至机器(machine-to-machine,M2M)业务接入对传统长期演进(long term evolution,LTE)网络造成的冲击,针对大量时延敏感M2M设备同时发起随机接入的场景,基于一种时延特性较优的Tree-splitting算法,通过估计信道负载量,引入动...为了解决机器至机器(machine-to-machine,M2M)业务接入对传统长期演进(long term evolution,LTE)网络造成的冲击,针对大量时延敏感M2M设备同时发起随机接入的场景,基于一种时延特性较优的Tree-splitting算法,通过估计信道负载量,引入动态前导码分配算法,提出了一种基于Tree-splitting的随机接入冲突解决动态算法。仿真时通过与静态算法对比,结果验证了所提出算法优良的时延、吞吐量特性和资源利用率。展开更多
We propose an efficient hybrid algorithm WDHP in this paper for mining frequent access patterns. WDHP adopts the techniques of DHP to optimize its performance, which is using hash table to filter candidate set and tri...We propose an efficient hybrid algorithm WDHP in this paper for mining frequent access patterns. WDHP adopts the techniques of DHP to optimize its performance, which is using hash table to filter candidate set and trimming database. Whenever the database is trimmed to a size less than a specified threshold, the algorithm puts the database into main memory by constructing a tree, and finds frequent patterns on the tree. The experiment shows that WDHP outperform algorithm DHP and main memory based algorithm WAP in execution efficiency.展开更多
R Tree is a good structure for spatial searching. But in this indexing structure, either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibil...R Tree is a good structure for spatial searching. But in this indexing structure, either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R tree (PBAR tree).展开更多
本文针对高校财务报销流程中存在的信任缺失、报销效率低下等问题,提出了一种以项目为导向的区块链高校报销平台模型。针对多项目环境下参与者角色的动态性,引入基于属性的访问控制(attribute-based access control,ABAC)模型,实现了细...本文针对高校财务报销流程中存在的信任缺失、报销效率低下等问题,提出了一种以项目为导向的区块链高校报销平台模型。针对多项目环境下参与者角色的动态性,引入基于属性的访问控制(attribute-based access control,ABAC)模型,实现了细粒度的权限管理。针对传统单链结构难以有效处理项目和发票之间的复杂逻辑关系,设计了主链-副链的双链存储结构以及对应的逻辑交易算法,解决了不同报销状态及与项目之间复杂的对应关系。为提高查询效率,设计了一种基于Merkle树索引表(Merkle tree index table,MTIT)的查询算法。实验结果表明,本设计在不同交易量下均展现出良好的性能稳定性,能够满足高校日常财务管理的需求。展开更多
理想格上的加密方案具有密钥尺寸小、加密效率高的优势,利用理想格环上带误差学习(R-LWE,ring learning with error)问题,构造一种可以保护用户属性隐私的属性基加密方案,支持灵活的访问策略,提供用户隐私保护,并且提高方案效率,缩短密...理想格上的加密方案具有密钥尺寸小、加密效率高的优势,利用理想格环上带误差学习(R-LWE,ring learning with error)问题,构造一种可以保护用户属性隐私的属性基加密方案,支持灵活的访问策略,提供用户隐私保护,并且提高方案效率,缩短密钥尺寸。该方案通过采用半策略隐藏方式,保护用户的隐私,从而避免用户的敏感属性值泄露给其他任何第三方。另外,将扩展的Shamir门限秘密共享技术应用于构造方案的访问结构,从而实现用户属性的"与""或""门限"这3种操作,具有更高的灵活性。经安全性分析证明,该方案在标准模型下满足自适应选择明文攻击安全。通过与其他方案的对比,该方案系统公钥、系统私钥、用户私钥长度以及密文长度都有所优化,在实际应用中更加有效。展开更多
文摘为了解决机器至机器(machine-to-machine,M2M)业务接入对传统长期演进(long term evolution,LTE)网络造成的冲击,针对大量时延敏感M2M设备同时发起随机接入的场景,基于一种时延特性较优的Tree-splitting算法,通过估计信道负载量,引入动态前导码分配算法,提出了一种基于Tree-splitting的随机接入冲突解决动态算法。仿真时通过与静态算法对比,结果验证了所提出算法优良的时延、吞吐量特性和资源利用率。
文摘We propose an efficient hybrid algorithm WDHP in this paper for mining frequent access patterns. WDHP adopts the techniques of DHP to optimize its performance, which is using hash table to filter candidate set and trimming database. Whenever the database is trimmed to a size less than a specified threshold, the algorithm puts the database into main memory by constructing a tree, and finds frequent patterns on the tree. The experiment shows that WDHP outperform algorithm DHP and main memory based algorithm WAP in execution efficiency.
基金This work is supported by University IT Research Center ProjectKorea.
文摘R Tree is a good structure for spatial searching. But in this indexing structure, either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R tree (PBAR tree).
文摘本文针对高校财务报销流程中存在的信任缺失、报销效率低下等问题,提出了一种以项目为导向的区块链高校报销平台模型。针对多项目环境下参与者角色的动态性,引入基于属性的访问控制(attribute-based access control,ABAC)模型,实现了细粒度的权限管理。针对传统单链结构难以有效处理项目和发票之间的复杂逻辑关系,设计了主链-副链的双链存储结构以及对应的逻辑交易算法,解决了不同报销状态及与项目之间复杂的对应关系。为提高查询效率,设计了一种基于Merkle树索引表(Merkle tree index table,MTIT)的查询算法。实验结果表明,本设计在不同交易量下均展现出良好的性能稳定性,能够满足高校日常财务管理的需求。
文摘理想格上的加密方案具有密钥尺寸小、加密效率高的优势,利用理想格环上带误差学习(R-LWE,ring learning with error)问题,构造一种可以保护用户属性隐私的属性基加密方案,支持灵活的访问策略,提供用户隐私保护,并且提高方案效率,缩短密钥尺寸。该方案通过采用半策略隐藏方式,保护用户的隐私,从而避免用户的敏感属性值泄露给其他任何第三方。另外,将扩展的Shamir门限秘密共享技术应用于构造方案的访问结构,从而实现用户属性的"与""或""门限"这3种操作,具有更高的灵活性。经安全性分析证明,该方案在标准模型下满足自适应选择明文攻击安全。通过与其他方案的对比,该方案系统公钥、系统私钥、用户私钥长度以及密文长度都有所优化,在实际应用中更加有效。
