tailieunhanh - Application F. G. SHINSKEY Systems Design Engineer

Technology is often a consequence of science and engineering — although technology as a human activity precedes the two fields. For example, science might study the flow of electrons in electrical conductors, by using already-existing tools and knowledge. This new-found knowledge may then be used by engineers to create new tools and machines, such as semiconductors, computers, and other forms of advanced technology. In this sense, scientists and engineers may both be considered technologists; the three fields are often considered as one for the purposes of research and reference.[14]. | Application Design Adjustment F. G. SHINSKEY Systems Design Engineer The Foxboro Company McGRAW-HILL BOOK COMPA N New York San Francisco Toronto London Sydney FACULTAD DE 1NGENIERIA u. DE G. 4-2 ó- ị. j iM ị r .ệ í Preface ỉ Consistent quality increased productivity and reduced operating costs can all accrue from effective control of major plant variables. But effective control is not an accident nor docs it come into being simply by implementing postulated theories. To be truly effective a control system must be designed to lit the needs of the particular process to which it will be applied. The more process intelligence the designer can put into a system the greater are its chances of success. The fact that many control systems have been operating satisfactorily indicates that plant engineers are capable of such design work. It also indicates that successful design is not necessarily contingent on graduate-level mathematics. Ziegler ami Nichols made this evident with the derivation of their simple rules for setting automatic controllers first presented in 1941 this derivation is still being used today. Many scientists are busily at work in laboratories and universities searching for more advanced control concepts. The principles they are discovering however could never realize their full worth if they J. J. Ziegler and N. B. Nichols Optimum Settings for Automatic Controllers Trans. ASMS December 1941. vii viìì I Preface are not communicated to the people who must apply them. Control problems arise in the plant and must be solved in the plant. Until plant engineers and control designers are able to communicate with each other their mutual problems await solution. I do not mean to imply that abstract mathematics is not capable of solving control problems but it is striking how often the same solution can be reached by using good common sense. High-order equations and high-speed computers can be manipulated to the point where common sense is dulled. Some months ago