Priority-based message forwarding and query processing in opportunistic wireless sensor network

提出了机会无线传感器网络中一种基于查询优先级的查询分发和处理(PbQ)算法。算法根据用户定义的查询优先级合理选取消息转发的中间节点,并控制查询消息的转发和拷贝量;同时,动态地调整查询消息的优先级,使得查询结果能快速回传到查询发起者并清理网络中查询的残留消息,避免了不必要的消息传输并提高查询处理的整体效用。模拟实验表明PbQ算法能有效提高机会网络中查询处理的成功率,降低查询的开销和时间延迟。A priority-based algorithm called PBQ was proposed for the query forwarding and processing in opportunistic wireless sensor network.Through the user-defined query priorities, the proposed algorithm properly selects the relay nodes and controlls the forwarding and the amount of messages.Meanwhile, the query priorities were adjusted dynamically so that the query results could be forwarded back to the source node of the query quickly and the residual query request messages could be cleaned up from the network, saving lots of unnecessary transmissions and improving the overall utility of query processing.Simulating results show that PBQ could effectively improve the success rate of queries, and reduce the cost and delay of query processing in opportunistic wireless sensor network.国家自然科学基金资助项目(61202012;61303004); 福建省自然科学基金资助项目(2011J05156;2013J05099); 中央高校基本科研业务费专项基金资助项目(2012121030)~

Survey of location-centric target tracking with mobile elements in wireless sensor networks

介绍目标跟踪的过程以及移动跟踪的特点;通过区分目标定位为主的方法和目标探测为主的方法,介绍定位为主的移动式目标跟踪方法(称为目标的移动式定位跟踪; )的研究现状;分析和比较不同方法的特点和应用领域,发现现有方法虽然可以提高跟踪质量、降低网络整体能耗,但是还存在一些问题。基于此,总结目标的移动; 式定位跟踪方法在方法类型、网络结构和节点模型等方面可能存在的研究热点,指出其研究和发展趋势。The basic process of target tracking and the properties of tracking; solutions with mobile elements were introduced. By distinguishing; location-centric methods and detection-centric methods, the current; research status of the location-centric target tracking methods were; reviewed. The properties and application fields of different solutions; were analyzed and compared. Although the existing solutions can; significantly improve tracking quality and reduce energy consumption of; the whole network, there are also some problems. Based on these; discoveries, some possible research hotspots of mobile solutions were; summarized in many aspects, such as method types, network architecture,; node model, and so on, indicating the future direction of research and; development.国家自然科学基金资助项目; 国家科技支撑计划项

Research Advance of Target Tracking with Mobile Elements in Heterogeneous Wireless Sensor Networks

传统固定无线传感器网络在进行目标跟踪过程中面临跟踪质量较低、网络能耗较高等问题.引入移动节点后所组成的异构无线传感器网络提供了新的解决方法,即移; 动式目标跟踪.目前的研究大多对被跟踪目标的探测和定位混为一谈,本文区分了以探测为主和以定位为主的两类方法,着重介绍以探测为主的移动式目标跟踪方法; 的研究现状.通过对比现有方法在跟踪质量和网络能耗等方面的优缺点,揭示了现有研究存在的问题.总结了移动式目标跟踪领域存在的研究热点和趋势.Traditional stationary wireless sensor networks usually encounter some; problems during the process of target tracking,such as low tracking; quality, high energy consumption and so on. More and more mobile; elements, i. e., mobile sensors, are used to build up heterogeneous; wireless sensor networks and thus bring new solutionsfor target; tracking. Existing researches usually misidentify detecting the target; with locating the target. After distinguishing between detection-centric; and localization-centric methods,we review specifically the current; research status of the detection-centric target tracking methods. By; comparing existing methods'merit and demeritin aspects like tracking; quality, energy consumption, etc.,their problems are revealed.; Therefore, we summarize some possible research hotspotsand tendency of; mobile solutions in many aspects.国家自然科学基金重点项目; 国家科技支撑计划项目; 国家自然科学基金项目; 福建省自然科学基金计划项

Delay-Constrained Mobile Energy Charging in Wireless Sensor Networks

为了延长无线传感网的生存期,基于可充电的移动设备,研究设计了一种无线传感网中移动式能量补充的方法,移动节点可以在为传感器节点补充能量的同时收集数; 据.首先,通过将无线传感器网络监测区域分割为大小相同的子区域,该子区域内的节点组成一个簇;其次,以一个簇内的总能量为计算依据,设计移动节点的路径; 生成算法以确定能量高效的移动路线;最后,使用10种不同的随机网络拓扑图进行了仿真实验,以节点移动速度和时延为限制条件分别得到了对比数据.结果表明; ,本文提出的算法与NJNP( nearest-job-next with preemption)算法相比在时延相同的条件下( 800; s),生存期提升了6 000 s左右,在节点速度5 m/s条件下生存期提升了将近14 000; s.证明本文所提方法有效地提高了充电效率,延长了网络的生存期,可用于大规模的无线传感器网络.In order to prolong the lifetime of wireless sensor networks by using; energy-rechargeable mobile devices,this paper designs a mobile energy; replenishment method wherein a mobile element gathers data and recharges; sensors simultaneously. Firstly,the whole sensor network is divided into; several sub-regions equally and the sensors in each sub-region are; formed into a cluster. Secondly, considering the energy in a whole; cluster,the mobility path is designed to find the energy-efficient; mobile trace of the mobile element. Finally,in the simulation; experiment,we used ten different random network topologies to show the; comparisons with extensive simulation experiments under different; velocities and deadlines. The results indicate that the proposed; algorithm increases lifetime by approximately 6 000 s compared with; Nearest-Job-Next with Pre-emption( NJNP) under the deadline of 800 s.; Moreover,the proposed algorithm increases lifetime by approximately 14; 000 s compared with NJNP at velocity of 5 m/s. Thus,the proposed; algorithm can improve recharging efficiency and prolong the lifetime of; wireless sensor networks,which can be used in large-scale sensor; networks.国家自然科学基金资助项目; 福建省高等学校杰出青年科研人才培育计划资助项

Research on Cloud Databases

随着云计算的发展,云数据库的重要性和价值日益显现;介绍了云数据库的特性、影响、相关产品;详细讨论了云数据库领域的研究问题,包括数据模型、系统体系架构、事务一致性、编程模型、数据安全、性能优化和测试基准等;最后讨论了云数据库的未来研究方向。With the recent development of cloud computing, the importance of cloud databases has been widely acknowledged. Here the features, influence and related products of cloud databases are first discussed. Then research issues of cloud databases are presented in detail, which include data model, architecture, consistency, programming model, data security, performance optimization, benchmark, and so on. Finally, some future trends in this area are discussed.国家自然科学基金(61001013, 61102136); 福建省自然科学基金(2011J05156, 2011J05158); 厦门大学基础创新科研基金(中央高校基本科研业务费专项资金)(2011121049, 2010121066

DB&IR System: A Survey

介绍了从DB、IR到DB&IR的发展历程；阐述了DB&IR系统的设计考虑因素；讨论了DB&IR系统的体系架构设计问题；介绍了DB&IR系统所采用的基于关键词的查询技术；最后总结并展望未来的研究方向。The development process from DB, IR to DB&IR is presented first, followed by the detailed description of the consideration factors for the design and architecture of DB&IR system. Then keyword search in DB&IR system is discussed. Finally, some future trends in this area are discussed.国家自然科学基金No. 5060401

Survey on Coverage Control with Mobile Elements in Wireless Sensor Networks

在无线传感器网络中,节点能量限制、硬件以及通信链路故障等问题,造成网络空洞的产生且影响了网络的正常运作,因此如何确保网络覆盖率成为传感器网络中需; 要解决的重要问题.近年来,通过引入移动节点来进行覆盖控制,提高传感器网络的覆盖率成为一个新的研究趋势.本文通过充分调研利用移动节点进行网络覆盖控; 制的方法,并对其进行了分类和比较,归纳了移动式网络覆盖的各种方法的特点,分析这些方法的性能和适用范围,总结存在的主要问题,并指出未来的研究方向.Due to the existence problems of energy depletion,hardware failure and; communication link failure and so on,which causes network holes and; affects the normal network operation. The insurance of coverage becomes; an urgent issue in wireless sensor networks. In recent years, a new; research trend is to utilize mobile nodes for coverage control, which; increases the coverage of wireless sensor networks. In this paper, we; have a comprehensive investigation about the current major topology; control methods with mobile nodes,and summarize the characteristics of; mobile topology control methods via classification and comparison of; these methods. Finally,we analyze the performances and the application; scopes of these methods, summarize the main problems,and point out the; future research directions.国家自然科学基金重点项目; 国家科技支撑计划项目; 国家自然科学基金项目; 福建省科技计划重点项

Survey on Connectivity with Mobile Elements in WSNs

节点连通性是无线传感器网络研究的热点问题之一,然而由于节点能量耗尽、硬件故障以及通信链路失效等问题的存在,造成网络分割,因此如何确保网络连通成为; 无线传感器网络亟待解决的关键性问题.近年来,一个新的研究趋势是通过引入计算能力较强且能量较为充足的移动性节点来进行连通控制,提高无线传感器网络的; 整体性能.本文对目前利用移动性节点的主流连通控制方法进行了充分调研,通过对这些方法的详细分类和比较,归纳了移动式连通控制的各类方法的特点,分析了; 这些方法的性能和适用范围,总结了研究中存在的主要问题与挑战,并指出了未来可能的研究方向.The connectivity of sensors is one of the main research problems in; wireless sensor networks (WSNs).Data can be forwarded through connected; sensor nodes.However,becauseof energy depletion,hardware failure and; communication link failure,the network may be partitioned.How to; guarantee the connectivity becomes an urgent issue in wireless sensor; networks.Traditional work usually focuses on maximizing the connectivity; with minimum sensors.In recent years,a new research trend is to utilize; mobile elements for connectivity control.Since the mobile element is; more powerful than normal sensors,it improves the performance of many; aspectsin wireless sensor networks.In this paper,we makea comprehensive; investigation about the current major connectivity control methods with; mobile elements.We first summarize the characteristics of mobile; topology control methods via a new classification.Based on the; classification,these methods are compared to each other according to a; serial parameters.Finally,we analyze the performances and the; application scopes of these methods,summarize the main problems,and; point out the future research directions.国家"九七三"重点基础研究发展计划项目; 国家科技支撑计划项目; 国家自然科学基金项目; 福建省科技计划重点项目; 福建省自然科学基金计划项

一种基于Gradient Boosting的公交车运行时长预测方法

目前,我国公交公司主要依靠经验丰富的工作人员估计车辆回场时间,进而进行车辆调度,此方式缺乏辅助的预测方法,常常造成较大的误差与错误的调度决策。从公交公司的实际需求出发,提出了一种基于动态特征选择的预测方法R-GBDT。R-GBDT利用特征选择组件和模型调参组件为预测组件提供符合线路特征的特征组合与参数,由融合组件对其他组件的结果进行融合,形成一个用于预测最终时间间隔的框架。结果表明,相对于其他算法,所提方法能大大提高公交运行时长预测的准确度。国家自然科学基金资助项目(No.61672441,No.61872154)深圳市基础研究计划基金资助项目(No.JCYJ20170818141325209)福建省自然科学基金资助项目(No.2018J01097)~

Maintaining Internal Consistency of Report for Real-time OLAP with Layer-based View

Maintaining internal consistency of report is an important aspect in the field of real-time data warehouses. OLAP and Query tools were initially designed to operate on top of unchanging, static historical data. In a real-time environment, however, the results they produce are usually negatively influenced by data changes concurrent to query execution, which may result in some internal report inconsistency. In this paper, we propose a new method, called layer-based view approach, to appropriately and effectively maintain report data consistency. The core idea is to prevent the data involved in an OLAP query from being changed through using lock mechanism, and avoid the confliction between read and write operations with the help of layer mechanism. Our approach can effectively deal with report consistency issue, while at the same time avoiding the query contention between read and write operations under real-time OLAP environment