PLC冗余配置在锅炉灭火保护系统中的应用

铁煤集团热电厂锅炉灭火保护系统采用SLC500型PLC+触摸屏构成冗余控制系统,实现锅炉灭火保护功能,监控现场采集所有参数.结合1997年投产的四台无锡锅炉厂130t/h锅炉灭火保护系统的技术改造,从根本上实现了PLC系统的冗余配置,确保燃烧系统锅炉灭火保护系统投入闭环运行,解决了许多技术难题,提高了锅炉的安全性和可靠性.     

操作系统实验在Windows环境下的设置与实现

操作系统实验一般有两个系列:其一是应用高级语言设计操作系统的模拟程序;其二是基于Linux系统下的实验.前者实验的目的是巩固与加深对原理的理解,后者大课时量的要求是一般本科院校无法满足的.而windows环境下的实验是查看、记录操作系统内部的结构,手工操作验证其管理功能.     

NTFS文件系统的DBR恢复研究与实践

NTFS文件系统的DBR扇区存储着文件系统的重要信息,由于病毒、断电、误操作等各种原因引起DBR损坏,出现未格式化现象。通过分析NTFS文件系统结构,提出了一种通过寻找MFT表和计算DBR中BPB重要参数的方法,利用磁盘编辑工具WinHex对NTFS文件系统的DBR信息损坏进行恢复实践,实践证明该方法可行。     

A study of the light sensitivity of birch bark

Birch bark is commonly found in indigenous collections in Canadian museums. It is empirically known that light can cause the cambium side of birch bark to change colour. The purpose of this research is to better assess the light sensitivities of various colours of birch barks, and the manner, degree, and rate of colour change during light exposure. Six barks with different colours were used: beige, yellow, orange, orange-brown, red, and brown. Samples were exposed to daylight through a north-facing window (window), LED light from an enclosed chamber (LED), and the Newport-Oriel microfade tester (MFT). Window and MFT samples received a total light dose of approximately 25 Mlux-hours, and LED samples, 182 Mlux-hours. Colour monitoring of the samples showed that almost all barks initially darkened and then faded. Daylight through window caused the most rapid and extensive darkening and fading. Bluewool (BW) ratings for window samples were the lowest (most light sensitive). The MFT and LED samples showed a similar degree of colour change, with the same dose, despite the difference in intensity. Ratings of MFT samples are within one BW step difference compared to LED samples. The rate and extent of initial darkening depended on the colour of the bark; the middle range orange-toned barks showed the most rapid and extensive darkening followed by fading.