基于PLC的物料包装输送监控系统

物料输送广泛应用于产品包装、流水作业、检测等相关行业中,对监控系统的准确性、可靠性以及自动化水平都有很高的要求.根据物料输送系统的实际需要提出了基于PLC和WinCC人机界面软件的硬件结构、控制思想和软件设计.系统已在内蒙古天野化工化肥传输自动控制中使用,整个系统组网方便、运行可靠,达到并满足设计的目的和要求.     

Towards a classification of energy aware MAC protocols for wireless sensor networks

Power management is an important issue in wireless sensor networks (WSNs) because wireless sensor nodes are usually battery powered, and an efficient use of the available battery power becomes an important concern specially for those applications where the system is expected to operate for long durations. This necessity for energy efficient operation of a WSN has prompted the development of new protocols in all layers of the communication stack. Provided that, the radio transceiver is the most power consuming component of a typical sensor node, large gains can be achieved at the link layer where the medium access control (MAC) protocol controls the usage of the radio transceiver unit. MAC protocols for sensor networks differ greatly from typical wireless networks access protocols in many issues. MAC protocols for sensor networks must have built‐in power conservation, mobility management, and failure recovery strategies. Furthermore, sensor MAC protocols should make performance trade‐off between latency and throughput for a reduction in energy consumption to maximize the lifetime of the network. This is in general achieved through duty cycling the radio transceiver. Many MAC protocols with different objectives were proposed for wireless sensor networks in the literature. Most of these protocols take into account the energy efficiency as a main objective. There is much more innovative work should be done at the MAC layer to address the hard unsolved problems. In this paper, we first outline and discuss the specific requirements and design trade‐offs of a typical wireless sensor MAC protocol by describing the properties of WSN that affect the design of MAC layer protocols. Then, a typical collection of wireless sensor MAC protocols presented in the literature are surveyed, classified, and described emphasizing their advantages and disadvantages whenever possible. Finally, we present research directions and identify open issues for future medium access research. Copyright © 2009 John Wiley & Sons, Ltd.     

GPS系统在长途干线光缆设计中的应用

随着科技的发展,GPS系统在各个领域已经得到了越来越广泛的应用。本文阐述GPS系统的基本原理,并着重介绍了GPS系统在长途干线光缆工程中的应用,与传统勘察设计方法的比较,并总结出GPS系统应用在干线光缆勘察设计中的优势。     

论携号转网行为的私法规制

以电信用户入网协议为切入点,电信用户的携号转网行为应受到《合同法》《消费者权益保护法》等私法规范的保护与限制。该行为引起的格式条款解释、合同终止、违约责任、损失赔偿等问题,不能仅靠《电信条例》等公法规范来调整。应当积极引导广大消费者用户以私法领域相关规定为依据,转变争议解决思维,拓宽纠纷处理途径,合理选择维权手段,以保护自身合法民事权益,与行业监管部门共同推动电信行业有序发展。     

航空放射性遥感技术应用研究

航空放射性遥感系统采用航空γ能谱仪,在空中飞行探测地表放射性,能够快速进行大面积环境放射性调查。结合已经开始进行的首次大面积航空放射性遥感调查工作,简要介绍了航空放射性遥感系统构成、核探测γ能谱测量和数据处理技术。对系统转换因子刻度和剥离系数刻度方法进行了讨论,并对初步应用情况进行了总结。     

国内甚高频水情遥测系统

本文阐述了国内甚高频水情遥测系统的结构特点、功能、组成与工作原理，并对遥测系统普遍存在的问题提出了建设性的见解。文中所述的水情遥测系统是国内近２０年来研制出的典型实例，它得到了广泛地应用。     

天津市城市居民用水行为调查及影响因素识别

基于天津市中心城区108个典型生活小区的居民生活用水的截面调查数据,探讨了天津市城市居民生活用水现状,对影响居民生活用水的主要因素进行了识别,并计算了天津市居民生活的节水潜力。结果表明,天津市家庭人均日生活用水量约为80L/(人·d),这与天津市水资源公报公布结果相吻合;从用水习惯上来看,马桶是否节水、每周洗浴和拖地次数等都是影响家庭用水的主要因素,此外,家庭收入水平也会对家庭用水产生影响;现状年天津市居民生活用水节水潜力为13.13%。     

无烟煤流化床燃烧中热破碎现象的研究综述

归纳用于衡量破碎程度的参数,分析产生破碎的机理,研究影响热破碎的因素,讨论破碎现象对燃烧的作用。总结认为。流化床燃烧中。无烟煤的破碎具有较大随机性,受煤质影响极大,粒径、炉床温度、停留时间、流化介质及流化速度等对破碎也有重要影响。煤的破碎有利于提高煤焦颗粒的燃烧速率,但同时也会增加炉床内可扬析颗粒数量,导致飞灰未燃碳含量增加的后果。实现破碎物料的准确快速取样和建立破碎前后颗粒平均粒径之间的关系是今后破碎研究工作尚待解决的问题。     

居住建筑耗能设备的相关调查和统计分析

为全面了解建筑能耗水平、建筑终端商品能耗结构、建筑用能模式,于2005年4月在无锡市范围内进行了一次住宅建筑能耗的问卷调查,应用统计分析方法,对被调查家庭用能设备的拥有量、家庭用能分布情况、房间空调器拥有量的分布、空调使用习惯及空调消费趋势、室内热环境及空气品质等内容进行了统计和分析,得出了每户月均能耗指标。其结论可为政府制定能源政策,挖掘建筑节能潜力提供依据。     

Thermal comfort standards for air conditioned buildings in hot and humid Thailand considering additional factors of acclimatization and education level

This paper presents the result of a large thermal comfort survey conducted using 1520 Thai volunteers from different climatic regions of Thailand. The survey was conducted using different types of air-conditioned buildings from the private and public sectors.Apart from common thermal comfort factors such as air dry bulb temperature, relative humidity and air velocity, two non-quantifiable factors were considered. These are the acclimatization to the use of air conditioner at home and the education level, i.e., post graduate, graduate and scholar. A general database for thermal comfort studies in Thailand was created, and different thermal comfort standards were developed for the three climatic regions of Thailand. Twenty six degree Celsius and 50–60% relative humidity could be used as a comfortable environment condition for the whole country. The data was then used to generalize an earlier concept we developed for setting thermal comfort standard using data from non air-conditioned buildings.