问题 问答题 简答题

什么叫集散控制系统?

答案

参考答案:集中控制系统又称分散型控制系统,简称集散系统。它以分散的控制适应分散的过程对象,同时又以集中的监视、操作和管理达到控制全局的目的,既发挥了计算机高智能、速度快的特点,又大大提高了整个系统的安全可靠性。集散系统可在分散控制的基础上,将大量信息通过数据通讯电缆传送到中央控制室,控制室用以微处理机为基础的屏幕显示操作站,将送来的信息集中显示和记录,同时可与上位监控计算机配合,对生产过程实行集中控制监视和管理,构成分级控制系统。集散系统不仅可完成任一物理量的检测,进行自动和手动调节控制,而且可向用户提供多种应用软件,如工艺流程显示、各种报表的制作,还提供过程控制语言,可完成顺序程序控制、数据处理、自适应控制、优化控制等程序编制。系统可采用积木组件式结构,根据用户规模任意组合,从只控制一个回路到控制几百个回路。采用集散控制系统不仅使生产过程实行安全、稳定、长周期运行,而且可实现优化控制和管理。

多项选择题
阅读理解

Grant Wood’s American Gothic caused a stir (轰动)in 1930 when it was exhibited for the first time at the Art Institute of Chicago and awarded a prize of 300 dollars. Newspapers across the country carried the story, and the painting of a farmer and a younger woman posed before a white house brought the artist instant fame.

In 1930, Grant Wood, an American painter with European training, noticed a small white house built in the small southern Iowa town of Eldon. Wood was so fascinated by it that he decided to paint the house along with the kind of people he thought should live in that house. In the painting, the farmer is modeled on his dentist. Dr. Byron McKeeby. His younger sister Nan served as a model for the woman (imagined to be the farmer’s wife or daughter). Wood wanted to give a description of the traditional roles of men and women as the man is holding a pitchfork symbolizing hard labor. Each element was painted separately; the models sat separately and never stood in front of the house. The Gothic style of the house inspired the painting’s title.

American Gothic remains one of the most famous paintings in the history of American art. The painting has become part of American popular culture. Some believe that Wood used it to satirize(讽刺) the narrow-mindedness that has been said to characterize Midwestern culture. The painting may also be read as a praise of the moral virtue or rural America or even as a mixture of praise and satire. American Gothic is one of the few images to reach the status of cultural symbol, along with Leonardo da Vinci’s Mona Lisa.

小题1:Which of the following is true about American Gothic?

A.It won a prize of £ 300.

B.The two characters in it posed before the White House.

C.It was the first painting by Grant Wood.

D.It was on show at the Art Institute of Chicago in 1930.小题2:From the passage we can infer Iowa is in __________.

A.the southern town of Eldon

B.the Midwest of the United States

C.a European country

D.the city of Chicago小题3:Grant Wood chose the two models __________.

A.to describe traditional roles of men and women

B.to praise the moral virtue of rural America

C.to make his dentist and his sister famous

D.to carry the story across the country小题4:The title of the painting is based on __________.

A.the name of a small town

B.the man and the woman

C.the Gothic style of the house

D.the pitchfork symbolizing hard labor