Each system is unique. However, by capitalizing on similarities we can — Harold Chestnut

"Engineers should press forward with development to meet the diversified needs of people."

"The term closed loop-learning process refers to the idea that one learns by determining what s desired and comparing what is actually taking place as measured at the process and feedback for comparison. The difference between what is desired and what is taking place provides an error indication which is used to develop a signal to the process being controlled."

"A model may be pictorial, descriptive, qualitative, or generally approximate in nature, or it may be mathematical and quantitative in nature and reasonably precise."

"Models are used essentially for evaluation and prediction purposes as well as for the analysis and study of the different parts of the system so that the systems engineer or designer may arrive at sound engineering decisions regarding the system design."

"In addition to technical problems, systems also have organizational and logistical problems. Many different people may be involved over a wide physical or geographic coverage and over a long period of time. Many may work for different companies or organizations with different rules and methods of operating. Very many data and much knowledge are involved. The organizational problem concerns itself with the question of how all these people can work together most effectively for the common purpose."

"Knowledge about the process being modeled starts fairly low, then increases as understanding is obtained and tapers off to a high value at the end."