变电站安全作业管理系统WSN网关设计

为了能够实时跟踪进入变电站巡检的工作人员或外来参观人员的移动轨迹,并在他们靠近危险区域时发出报警提示信号,提出了基于无线传感网络的变电站安全作业管理系统。设计了应用在基于WSN的变电站安全作业管理系统的网关,网关通过串口与WSN连接、通过以太网口与TCP/IP网相连接;设计了WSN与网关、网关与TCP/IP网之间通信的帧格式,实现了定位信息的上传以及控制命令的下达。现场运行表明,该网关稳定可靠,满足实际要求。     

适配多终端的物联网网关设计与实现

针对物联网网关统一标准尚未制定,无线传感网络(Wireless Sensor Networks,WSN)异构性大,应用场景受限,开发成本高等现状,提出一种应用于农业监控的物联网系统,设计并实现了一种适配多种WSN终端的物联网网关。该网关可以通过GPRS、Wi Fi、以太网多种远程通信模式进行通信,适配ZigBee和Wi Fi传感网络类型终端,满足不同场合和环境的需求。以python集成的Sqlite3作为嵌入式数据库,编程实现数据互操作、数据管理、WSN和传统互联网之间的数据传输,最终形成了一个高集成度的轻量级农业物联网网关。最后给出系统运行结果验证,该网关系统性能稳定、通用性和扩展性强、易于开发和维护。     

校园网上的数据安全

采用以广播为技术基础的以太网,任何两个节点之间的通信数据包,不仅为这两个节点的网卡所接收,也同时为处在同一以太网上的任何一个节点的网卡所截取。因此,黑客只要接入以太网上的任一节点进行侦听,就可以捕获发生在这个以太网上的所有数据包,对其进行解包分析,从而窃取关键信息,这就是以太网所固有的安全隐患。对此,可以采用网络分段、交换式集线器代替共享集线器和VLAN的划分措施来实现其数据传输的安全。     

基于遗传算法的Ad-hoc网络安全多目标优化认证机制研究

节点的安全性是Ad-hoc网络面临的重要问题,因为通过非安全节点可以窃取、篡改网络中的数据包,甚至对网络造成致命性的破坏。通常情况下,Ad-hoc网络是借助于基于密钥的认证算法来实现节点的安全性保障的,但是这些认证算法并不适用于Ad-hoc的特殊网络环境。将遗传算法应用于节点安全性认证领域,通过基于多目标优化的认证机制,取代了密钥认证机制。通过模拟实验表明,基于多目标优化的认证机制,在Ad-hoc网络环境中,性能较为优越。     

基于能耗最小化的WSN时间同步算法研究

时间同步是无线传感器网络(WSNs)的重要支撑技术。介绍了分簇路由算法与WSN时间同步之间的关系,针对网络节点中能量消耗不均匀问题,提出了一种新的基于分簇的时间同步解决方案,在簇头节点与基站之间以及簇内节点之间分别采用DMTS以及FTSP单向同步模式,以达到在保证足够同步精度的同时降低能耗的目的。     

移动无线网相邻节点间匿名通信策略

由于移动无线网相邻节点间通信的匿名安全性未被专门而全面地研究,因此提出一种新型移动无线网相邻节点间匿名通信策略是有必要的。首先采用信息签名算法设计了广播式匿名认证方案;其次基于节点伪名设计了任意相邻节点间非交互的一对多密钥共享方案;最后采用Bloom filter隐藏消息接收者,并对算法的匿名性与通信效率进行了分析。     

基于C#的无线传感网络软件升级技术研究

随着嵌入式技术的不断发展,智能设备逐渐成为研究热点,解决智能设备软件版本升级问题至关重要。节点软件升级系统一般分为主计算机、网关节点和传感器节点3个部分。主计算机通过串口将要更新的软件代码发送到网关节点,网关节点通过无线传感器网络传递软件代码到传感器节点并控制节点,以完成新版本升级。研究了CC2430芯片所适用的软件升级系统。主计算机使用基于C#语言的窗体应用程序,将代码的iHex文件分割成可变长数据包,提高主机和网关节点之间的代码传输速率。实验证明,该方法有效减少了主机与网关节点的代码传输时间,提高了写数据效率,可广泛应用于智能家居及医疗监测等领域。     

基于克隆选择机理的无线传感网络故障诊断算法

故障诊断是无线传感器网络(WSN)可靠运行的保证.针对WSN特点及故障诊断需求,文章提出一种基于克隆选择机理的无线传感网络故障诊断算法.该算法结合集中式算法和分布式算法,后台管理节点执行分簇算法和优化免疫算法训练和更新抗体库,簇头节点利用小包波法收集普通节点的状态特征、执行故障检测和分类.实验仿真表明:该算法在历史数据较少的情况下,诊断准确率较高,效率好,硬件资源开销小,并具有自学习特征.     

电力专用纵向加密认证网关的技术应用

电力专用纵向加密认证网关用于生产控制大区的广域边界防护,为电力网关机之间的广域通信提供认证与加密功能,实现数据传输的机密性和完整性保护.     

基于生成树的WSN溯源数据压缩方法

在无线传感器网络(WSN)中溯源数据(Provenance)记录了一个数据从产生至被传输到基站(BS)途经的所有节点以及在这些节点上对数据的操作。提出一种基于生成树的溯源数据压缩方法,其基本思想是在字典中存放WSN拓扑图的生成树并对其建立索引,在数据包传输过程中传输的是生成树的索引而不是完整的生成树。仿真实验结果表明,在大规模稀疏WSN中采用该方法,溯源数据在文件大小和传输能耗等方面都优于已知的其它溯源数据编码技术,而且该方法对线性溯源数据和聚合溯源数据采用完全相同的处理方式,算法实现简单、一致性好。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.