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Oracle中constraint的应用研究 被引量:1
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作者 徐洪丽 姜红花 +1 位作者 杨传栋 周倩 《中国新通信》 2019年第19期93-94,共2页
数据完整性是数据库管理系统中重要的技术指标。本文研究在大型数据库Oracle平台,如何构建三类完整性约束,分别是实体完整性约束、参照完整性约束、用户自定义完整性约束,并研究其注意问题及如何绘制模式中表间的关系。
关键词 大型数据库Oracle完整性约束 实体约束 参照约束 表之间联系
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Privacy-Preserving Strategyproof Auction Mechanisms for Resource Allocation
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作者 Yu-E Sun He Huang +4 位作者 Xiang-Yang Li Yang Du Miaomiao Tian hongli xu Mingjun Xiao 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2017年第2期119-134,共16页
In recent years, auction theory has been extensively studied and many state-of-the-art solutions have been proposed aiming at allocating scarce resources. However, most of these studies assume that the auctioneer is a... In recent years, auction theory has been extensively studied and many state-of-the-art solutions have been proposed aiming at allocating scarce resources. However, most of these studies assume that the auctioneer is always trustworthy in the sealed-bid auctions, which is not always true in a more realistic scenario. Besides the privacy-preserving issue, the performance guarantee of social efficiency maximization is also crucial for auction mechanism design. In this paper, we study the auction mechanisms that consider the above two aspects. We discuss two multi-unit auction models: the identical multiple-items auction and the distinct multiple-items auction.Since the problem of determining a multi-unit auction mechanism that can maximize its social efficiency is NPhard, we design a series of nearly optimal multi-unit auction mechanisms for the proposed models. We prove that the proposed auction mechanisms are strategyproof. Moreover, we also prove that the privacy of bid value from each bidder can be preserved in the auction mechanisms. To the best of our knowledge, this is the first work on the strategyproof multi-unit auction mechanisms that simultaneously consider privacy preservation and social efficiency maximization. The extensive simulations show that the proposed mechanisms have low computation and communication overheads. 展开更多
关键词 拍卖理论 机制设计 隐私保护 资源分配 社会效益 仿真结果 通信开销 最大化
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Hybrid Routing by Joint Optimization of Per-Flow Routing and Tag-Based Routing in Software-Defined Networks
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作者 Gongming Zhao Liusheng Huang +1 位作者 Ziqiang Li hongli xu 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2018年第4期440-452,共13页
In recent years, Software-Defined Networks(SDNs) have become a promising technology to improve network utilization. However, limited flow table size and long deployment delays may result in low network performance in ... In recent years, Software-Defined Networks(SDNs) have become a promising technology to improve network utilization. However, limited flow table size and long deployment delays may result in low network performance in large-scale networks and a poor user experience. While a typical solution to this issue is routing aggregation(i.e., wildcard routing), the aggregation feasibility problem and reduced network performance may be encountered. To address this dilemma, we first design a novel wildcard routing scheme, called the Tag-based Rule Placement Scheme(TRPS). We then formulate a Hybrid Routing by Joint optimization of Per-flow routing and Tagbased routing(HR-JPT) problem, and prove its NP-hardness. An algorithm with a bounded approximation factor is designed for this problem, and the proposed methods are implemented on a Mininet platform. Extensive simulation results show that our methods are efficient for wildcard/hybrid routing. For example, our proposed tag-based wildcard rule placement scheme can reduce the number of required rules by about 65% on average compared with previous wildcard routing methods. Our proposed hybrid routing algorithm can increase network throughput by about 43% compared with existing hybrid routing solutions. 展开更多
关键词 路由算法 网络性能 联合优化 标签 混合 流动 软件 定义
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Application of Bat Algorithm Based Time Optimal Control in Multi-robots Formation Reconfiguration 被引量:1
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作者 Guannan Li hongli xu Yang Lin 《Journal of Bionic Engineering》 SCIE EI CSCD 2018年第1期126-138,共13页
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