冷库温度控制系统的设计外文翻译.doc

大连交通大学信息工程学院 毕业设计(论文)外文翻译 学生姓名 1111 专业班级 自动化0111班 指导教师 1111 职 称　 11111 所在单位 电气工程系 教研室主任 　 完成日期 1111 年 4 月 13 日 Date Acquisition Date acquisition systems are used to acquire process operating data and store it on secondary storage devices for later analysis. Many of the data acquisition systems acquire this data at very high speeds and very little computer time is left to carry out any necessary, or desirable, data manipulations or reduction. All the data are stored on secondary storage devices and manipulated subsequently to derive the variables of interest. It is very often necessary to design special purpose data acquisition systems and interfaces to acquire the high speed process data. This special purpose design can be an expensive proposition. Powerful mini- and mainframe computers are used to combine the data acquisition with other functions such as comparisons between the actual output and the desirable output values, and to then decide on the control action which must be taken to ensure that the output variables lie within pre-set limits. The computing power required will depend upon the type of process control system implemented .Software requirements for carrying out proportional, ratio or three term control of process variables are relatively trivial , and microcomputers can be used to implement such process control systems . It would not be possible to use many of the currently available microcomputers for the implementation of high speed adaptive control systems which require the use of suitable process models and considerable on-line manipulation of data. Microcomputer based data loggers are used to carry out intermediate functions such as data acquisition at comparatively low speeds, simple mathematical manipulations of raw data and some forms of data reduction. The first generation of data loggers, without any programmable computing facilities, were used simply for slow speed data acquisition f