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

Research on Performance Optimization for SSD-Based Storage Systems

数据量的激增给计算机存储系统带来严峻的性能挑战。固态盘作为新型存储介质，已被企业级存储系统和数据中心广泛使用，但简单地将传统存储软件应用于固态盘将带来一些新的问题，如将磁盘阵列技术应用于固态盘会加剧固态盘的垃圾回收操作所引发的性能波动性问题，将传统键值（KeyValue，简称KV）存储系统部署于固态盘上也可能造成存储效率低下等问题。本文分别以黑盒和白盒的使用角度，分别对固态盘阵列和基于固态盘的KV存储系统进行研究。 首先，对固态盘阵列的最优分块大小进行研究，理论分析和真实设备的性能测试结果表明，固态盘阵列的分块大小会对固态盘阵列的读写性能产生较大影响。基于分块大小与真实应用负载的读写密集特性...With rapidly increasing of data, computer storage systems encounter serious performance challenge. As new storage media, Solid State Drives (short for SSDs), have been widely used in enterprise storage systems and data centers. However, simply applying traditional storage software to SSDs will bring some new problems, such as the performance variability issue caused by Garbage Collection (short fo...学位：工学硕士院系专业：信息科学与技术学院_计算机科学与技术学号：2302014115316

Target Set Selection on Graphs

目标集选取问题~(TSS)~最初是由~Kempe~等提出的，用于研究信息、思想或影响在社交网络上的传播.\这类模型因其在经济、社会、医药和计算机科学等方面的广泛应用而备受关注. 在目标集选取问题的研究中，网络通常被抽象为一个无向图，且每个点都被赋予一个阈值函数\$\theta(v):V(G)\rightarrow\mathbb{N}$，其中\$V(G)\$是\$G\$的点集，\$\mathbb{N}\$是整数集.\$G$\中的点通过一个动态过程被依次激活:在初始步骤，选择\$G$\的一个顶点子集\$S$\作为初始激活集，在步骤\i\(i>0)，$G$\中未被激活的点遵行下面的原则激活...Target Set Selection (TSS) was initially proposed by Kempe et al. to study the social network analysis involving the problem of the spread of information, ideas or influence through a social network. This model can also formulate many problems arising in economy, sociology, medicine and computer science and, therefore, receives much attention from both theoretical and practical interests. For...学位：理学博士院系专业：数学科学学院_应用数学学号：1902013015417

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