共查询到17条相似文献，搜索用时 62 毫秒
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在本论文中,设计了一种低功耗、多参数的复合火灾探测节点,该节点可以检测温度、烟雾浓度和CO气体浓度,并结合无线传感器网络(WSN),建立了一套实时无线火灾监控系统.该系统应用于以古建筑为代表的特殊情况下的火灾检测.其中,系统的硬件和软件实现基于2.4GHz无线通信芯片CC2430.系统中采用ZigBee协议,形成可靠的... 相似文献
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基于ZigBee技术矿井安全监测系统的设计 总被引：1，自引：0，他引：1
本文采用基于ZigBee网络协议无线传感器网络能够保证数据无线传输的可靠性、准确性弥补了传统的有线网络的不足与缺陷,提高了煤矿井下瓦斯监测的精确性,并随着矿井生产过程中新工作面的开采和旧巷道的废弃,只需要增加、减少或移动无线传感器节点,无线传感器网络的拓扑结构基本不受其影响。同时也提高了煤炭生产安全性,加快煤矿信息化、智能化进程。 相似文献
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近年来,由于室内环境污染而引起的人口健康问题越来越突出,已经引起广大人民群众的广泛关注。本文提出了以ZigBee星型网络为核心,采用CC2430芯片为传感器控制核心的室内环境监测方案。试验证明,系统能够实时监测室内环境变化,工作稳定可靠、具有较高的实用性和市场价值。 相似文献
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本文就如何提高人体寄生虫学实验课的教学质量,从应用多媒体课件、组织活体实验教学、开展病例分析、改进实验准备等方面进行了改进和探讨。 相似文献
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本文分析了女性的躯干形状,以及体表凸点形成的关键点在结构设计中的对应方位。研究短裙结构线的确定和设计的依据,介绍省道转移、分割线和增量设计的运用手法。进一步阐明了短裙结构应该遵循人体为基础进行设计的合理性。 相似文献
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介绍了 IEEE80 2 .1 1协议的主要内容 ,阐述了直接序列扩频 (DSSS)技术在无线局域网中的重要作用及优点。介绍了支持 80 2 .1 1协议的全数字化直接序列扩频处理芯片 ,分析了目前无线局域网中采用的 DBPSK,DQPSK,BMBOK,QMBOK,CCK扩频调制方式及性能。 相似文献
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为了解决高校在建设实验室过程中面临的设备管理非自动化程度高、传感器传输信号异构化程度高、资源管理共享程度低和智慧化程度低等问题,以满足实验教学、管理、服务的开放性、可持续性和协同化需求,运用物联网和大数据技术提出了数据共享的智慧实验室解决方案,设计了感知层、网络层、大数据层、应用层和用户层等技术架构,并对模型中各层功能结构的设计方案进行了讨论;利用ZigBee具有的容纳节点数量大,增减节点灵活等特点,设计了基于ZigBee协议的海量感知数据传输的实现方案,通过对感知节点、网关设计等技术的融入,实现了海量数据的实时采集。基于物联网技术的智慧实验室将实现信息数据海量感知化、实时控制远程化、系统运行自动化、智慧感知分析,可为智慧校园建设提供借鉴。 相似文献
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《Telecommunications Policy》2014,38(8-9):827-837
While Wi-Fi has enjoyed explosive growth and deployment for use in residential homes, the rollout of commercial Wi-Fi service has been more limited. Part of the holdback on large-scale commercial deployment has been the strategic concern that the commons model to spectrum management lacks the incentives for service providers to invest due to the limited ability to manage interference in the unlicensed band. Today, however, this situation appears to have changed. To explain the new confidence by service providers in commercial Wi-Fi, the activities of the Wi-Fi Alliance and IEEE 802.11 standards body are analyzed to show how these groups essentially replicate many, but not all, of the functions traditionally employed by an effective band manager that is optimizing efficiency on a licensed spectrum block more typically associated with the deployment of commercial services. Consequently, with the Wi-Fi ecosystem functioning as an effective spectrum manager, it is concluded that the service provider investment in Public Wi-Fi networks is rational and the risk posed by saturation or overuse has been reduced to an acceptable level. The strategic implications of this finding on the Wi-Fi platform are the examined. How the requirements from service providers are already significantly influencing the evolution of the Wi-Fi standard is discussed, and an attempt is made to address the risks and liabilities associated with the unlicensed spectrum management model. Thus, service providers increasingly need functionality in Wi-Fi technology to manage interference, and monitor and improve network performance. The current ideas under discussion are elaborated for the next version of Wi-Fi to support both commercial Wi-Fi requirements, which address the interference concerns, but only up to a point, as the unlicensed model intrinsically leaves some risk to participants of spectrum saturation through overuse. 相似文献
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污染源工况在线监测及分析系统的设计与实现 总被引：1，自引：0，他引：1
针对目前企业治污现场环境恶劣,数据存在信息孤岛,采集的数据稳定性、准确性不佳,企业排污违法取证难的问题,对企业治污全过程监控进行深入研究,提出了一种基于ZigBee终端技术来实现对排污源头、治污过程、治污结果各工艺点数据的采集和传输,选用基于.NET的组态软件来实现对采集数据的深入挖掘和分析,并集成了远程视频取证功能,实现对排污违法的取证,最终实现以污染治理工艺为基础的集采集、传输、监测、控制、应用于一体的全过程智能监控系统。系统的实现帮助企业改进了生产工艺、提高了效率,有效地减少了资源消耗和污染排放,产生了良好的社会效益。研究方法为促进环保监测的数据化、精细化管理,提高政府监督执法效率提供了思路。 相似文献
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增强Linux系统安全性的措施 总被引：2，自引：0，他引：2
L inux系统的安全取决于系统管理员如何来管理它。本文探讨了一系列可以增强安全性的技巧与策略 ,包括 :系统安装原则、BIOS安全、口令安全策略、设计帐户自动注销功能、文件系统和日志安全策略、使用 SSH及 TCP-WRAPPERS,隐藏系统信息、删除所有特殊帐户、关闭控制台程序、限制系统中的 SUID/ SGID程序等。本文最后向 L inux系统管理员提出了一些安全管理方面的建议 相似文献
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Chemical, petrochemical, and refinery sectors have been facing tougher safety, environmental and mechanical integrity regulations as well as challenges associated with the need for cost reduction to improve competitiveness. Risk-based Inspection (RBI) is a cost-effective approach to manage operational risks by making an informed decision on inspection frequency, extent of inspections, and types of non-destructive testing. This paper presents a comprehensive practical risk model that can simulate all components of liquefied petroleum gas (LPG) tanks, that is, roof, shell, nozzles, and bottom plates. The probability of failure (PoF) model was developed based on failure frequency data from four different sources to determine the adequate general failure frequencies, moreover, it addresses the fatigue effect due to cyclic loading. Reviewing past losses of containment incidents revealed that fires and explosion are the most likely outcomes, therefore, this risk model introduced area affected consequence of failure (CoF) simulation. The CoF model addresses all the main components of the LPG tank and deploys a practical gas dispersion model to estimate the vapor cloud explosion (VCE) and flash fire consequence affected areas. Furthermore, modified mass release equations are presented to account for the decline in the release rate with time to determine the pool fire area and leak duration. Consequence areas are determined based on serious personnel injuries and component damage from thermal radiation and explosions. To validate the risk model, a proof of concept assessment was performed on seven tanks. 相似文献