自动化专业英语翻译解析.pdf

1.1 In recent years the performance requirements for process plant have become increasingly difficult to satisfy. Stronger competition, tougher ( 更加严苛的 ) environmental and safety regulations ( 法 规), and rapidly changing economic conditions have been key factors in the tightening of plant product quality specifications (产品质量规范 ).A further complication (复杂 ) is that modern processes have become more difficult to operate because of the trend toward larger, more highly integrated plants with smaller surge capacities (谐振能力 ) between the various processing units. Such plants give the operators little opportunity to prevent upsets ( 扰乱 ) from propagating from one unit to other interconnected units. In view of ( 考虑到， 由于 ) the increased emphasis placed on safe, efficient plant operation, it is only natural that the subject of process control has become increasingly important in recent years. In fact, without process control it would not be possible to operate most modern processes safely and profitably ( 有利的 ), while satisfying plant quality standards. 近年来，对过程系统的性能改善需求变得越来越困难 . 更为激烈的竞争，更加严格的环境 和安全规范， 以及快速变化的经济条件都是加强工厂产品质量规范的关键因素更为复杂的情 况是，由于现代制造业朝着规模更大 ,集成度更高的方向发展 ,而使不同的加工环节之间的应 变能力更低 , 所以加工过程更难控制近年来，考虑到工业制造逐渐加强的安全、高效需求， 过程控制这个课题变得越来越受重视 . 实际上，对于大多数现代工业，要满足安全、高效， 产品质量的要求，没有控制系统是不可能的 . It is assumed that the inlet and outlet flow rates are identical ( 相同的 ) and that the liquid density ρ (rho) remains consant, that is, the temperature variations are small enough that the temperature dependence of ρcan be neglected. Under these conditions the volu me V of liquid in the tank remains constant. 假设输入和输出流量是相等的， 并且液体密度保持恒定， 也就是说温度变化足够小， 密度对 温度的影响可以忽略不计 . 在这些条件下，槽内液体的体积保持恒定 Use a larger tank. If a larger tank is used, fluctu