TAILIEUCHUNG - Systems Design Engineer, The Foxboro Company

Continuing improvements led to the furnace and bellows and provided the ability to smelt and forge native metals (naturally occurring in relatively pure form).[38] Gold, copper, silver, and lead, were such early metals. The advantages of copper tools over stone, bone, and wooden tools were quickly apparent to early humans, and native copper was probably used from near the beginning of Neolithic times (about 8000 BC).[39] Native copper does not naturally occur in large amounts, but copper ores are quite common and some of them produce metal easily when burned in wood or charcoal fires. Eventually, the working of metals. | 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

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• The subject of rock mechanics
• Content of this book
• Geological setting
• Natural rock environments
• Stress as a point property