基于计量芯片ADE7758的三相多功能电表设计

利用Analog公司2005年生产的电能计量专用芯片ADE7758设计一个三相电能表,采集数据准确,控制性能灵活且性价比高。本文阐述了基于ADE7758和STC89C52的电表的整体设计及工作原理,重点讲述ADE7758电能计量芯片的外围设计以及与STC89C52的通信连接。使用模块化思想和嵌套方法分别对硬件进行设计、对软件进行编程。     

影响糖厂于10月份开榨配套技术采纳因素的分析

为探讨制约糖厂10月开榨配套技术采纳因素,特进行本研究。主要研究方法有资料收集、个体访谈和排序打分。主要研究结果：影响糖厂10月开榨配套技术采纳的主要因素有甘蔗品种蔗糖分和成熟度,10月份市场糖价,蔗价及相关激励政策,甘蔗单产,原料蔗总产量,糖厂管理等因素。本研究结果对因地制宜推广糖厂10月开榨配套技术以促进蔗糖业生产可持续发展具有一定的指导意义。     

基于DFW的主动型校园网安全应用研究

为了解决校园网由于自身结构及使用群体等特殊性所带来的问题,该文在分析P2DR2主动型网络安全模型和DFW(Distributed Firewalls,分布式防火墙)技术的基础上,给出了更能满足校园网安全特点的MAP2DR2C主动型安全模型;并结合北京印刷学院的实际情况,提出了以分布式防火墙产品"蓝盾防火墙的校园网专业版"构筑主动校园网安全的解决方案.研究结果证明:以DFW构筑的主动型网络安全模型能够很好地解决当前网络安全中所面临的主要问题.     

实验室环境下的智能电表载波模块通信测试

随着智能电网的建设,智能电表在国内居民用户大批量推广并已开始全面挂网运行,而作为智能电表最主要的通信模块之一的低压电力线载波模块的通信性能将直接影响使用效果.本文在实验室内模拟居民用户用电情况搭建了一个低压电力线载波测试环境,采集了6种居民用户常用的用电设备电力线噪声,并在此环境下对国内6种载波模块进行了通信成功率测试,得到了载波信号在线路衰减和用电设备噪声干扰情况下的通信数据.通过测试有助于深入了解低压电力线载波通信的特点以及为现场通信方案的选择实施与故障分析提供了参考依据.     

Lead (II) detection and contamination routes in environmental sources, cookware and home-prepared foods from Zimatlán, Oaxaca, Mexico

An interdisciplinary investigation, involving environmental geochemists, epidemiologists, nurses, and anthropologists, was undertaken to determine the contamination source and pathway of an on-going outbreak of lead poisoning among migrants originating from Zimatlán, Oaxaca, Mexico and living in Seaside, California, and among their US-born children. An initial investigation in Seaside identified grasshopper foodstuff (“chapulines”) imported from Mexico and consumed as snacks, as containing alarmingly high lead concentrations (up to 2300 mg/kg). The focus in the present work concentrates on the Oaxacan area of origin of the problem in Mexico, and two potential sources of contamination were investigated: wind-borne dusts from existing mine residues as potential contaminants of soil, plant, and fauna; and food preparation practices using lead-glazed ceramic cookware.Over a three year period, sampling was conducted in Oaxaca using community-level sampling and also targeted sampling with families of cases with lead poisoning in California. In addition to fresh field chapulines, we analyzed for total lead: soil, water, mine residues, and plant materials, both from areas adjacent to or at an abandoned waste site containing mine tailings, and from fields where chapulines are collected; foodstuffs gathered in community markets or in a food transport business; and foodstuffs and cookware gathered from relatives of case families in California. Also, selected new and used lead-glazed clay cookware was extracted for lead, using 0.02 M citric acid and with 4% acetic acid.The results indicated significant presence of lead in mine wastes, in specific foodstuffs, and in glazed cookware, but no extensive soil contamination was identified. In-situ experiments demonstrated that lead incorporation in food is made very efficient through grinding of spices in glazed cookware, with the combination of a harsh mechanical action and the frequent presence of acidic lime juice, but without heating, resulting in high but variable levels of contamination.     

独栋住宅土壤源热泵系统冬季供暖实证研究

本文以1栋上海地区独栋住宅为对象,对土壤源热泵系统冬季供暖性能和能效进行了实证研究.通过对系统运行参数的连续监测,实证了地埋管换热器每米埋管取热量、机组与系统的COP及系统节能率等指标.结果表明:地埋管换热器出水温度及循环温差较为稳定,埋管换热量为27 ～ 32 W/m;系统能效受部分负荷率影响较大,整个测试期系统COP在3.3～3.9之间;在满足同等舒适性条件下,土壤源热泵系统比空气源热泵节能31.0％,节能效果明显.     

电子式单相电能表防窃电原理及误接线分析

介绍电子式单相电能表防窃电的工作原理,并对使用中的2种接线情况进行了分析。     

承钢炼铁3#风机计算机监控系统

介绍了“全可控涡”风机计算机监控系统的控制原理、系统组成及其功能,采用的新产品、新技术以及在承钢炼铁3#风机的应用情况。利用计算机监控系统进行风机监测;用DELPHI6作为开发平台,后台数据库采用InterBase7系统;首次采用阿牛巴流量计取代流量孔板,对风机出口流量进行检测;阐述了防喘振自动控制、轴振动和轴位移监测等几个风机运行关键问题。实际运行结果表明,该系统具有操作简便、控制精确、安全可靠等优点,提高了风机出风效率,降低了维护工作量和维护成本,具有较高的性价比。     

基于真空荧光管(VFD)的汽车组合仪表

,介绍了基于VFD汽车组合仪表的系统构成、硬件模块与软件流程设计方案;突出了系统技术的先进性,具有色彩鲜艳、可见度高等优点。该仪表已研制成功。     

手持式激光测距仪"测距标准偏差综合评定"的扩展不确定度

在确定的函数关系(数学模型)中,因变量(输出量)随自变量(输入量)的变化规律完全由数学逻辑所确定,自变量到因变量的传递系数(灵敏系数)也可由因变量的标准差和自变量的标准差之比所决定,而与自变量的来历(测量的或者给定的)没有关系[1].本文根据这一基本原理,采用模拟自变量随机变化的方法,成功计算了手持式激光测距仪的测距固定偏差和比例偏差系数的测量不确定度,从而计算出测距标准差综合评定的扩展不确定度,同时解决了复杂的数学模型中多个输入量到输出量的灵敏系数和输出量的不确定度的计算问题.