Systems Engineers

"All that can be done pedagogically is to show the student how some phenomena have been modeled, let him model some phenomena under supervision, and then hope he will be successful on his own—or know enough to secure assistance."

"Only if mathematical rigor is adhered to, can systems problems be dealt with effectively, and so it is that the systems engineer must, at least, develop an appreciation for mathematical rigor if not also considerable mathematical competence."

"If all the theories pertinent to systems engineering could be discussed within a common framework by means of a standard set of nomenclature and definitions, many separate courses might not be required."

"Every author has several motivations for writing, and authors of technical books always have, as one motivation, the personal need to understand; that is, they write because they want to learn, or to understand a phenomenon, or to think through a set of ideas."

"The problem of the design of a system must be stated strictly in terms of its requirements, not in terms of a solution or a class of solutions."

"[The word system is often defined in a way] that seems the most appropriate for the purpose of any given discussion."

"[The process of system design is]... consisting of the development of a sequence of mathematical models of systems, each one more detailed than the last."

"Derek Hitchins has had several careers. He served as an engineer officer in the RAF for 22 years, retiring as a wing commander. He worked in industry for some 17 years, variously as systems design manager, future projects manager, technical director, marketing director and business development director for systems companies. For five years, he taught integrated science and physics (plus singing and trampoline) in a grammar school. And he was a university professor for seven years, before being obliged to retire from full time academia on health grounds. Presently: author, consultant and occasional lecturer on systems, systems thinking, chaos and systems engineering – contemporary and ancient."

"Architecture is defined as the art and science of creating buildings. Systems engineering may be similarly defined as the art and science of creating systems."

"“The term (system-of-systems) is being applied to the creation of new systems by bringing together existing operational systems under a single umbrella and, presumably, creating or adapting links and interactions between the operational systems, which become subsystems of the higher level umbrella system.”"

"System engineering is the art and science of creating effective systems, using whole system, whole life principles."

"The motives for conceiving modern systems engineering are to be found, at least in part, in past disasters. Arthur D. Hall III [1989] cites: the chemical plant leakage in Bhopal (1986); the explosion of the NASA Challenger space shuttle (1986) and the Apollo fire (1967); the sinking of the Titanic (1912); the nuclear explosion in Chernobyl (1986) and the disaster at Three Mile Island power plant (1979). He cites, too, the capture of markets by Japan from the U.S., the decline in US productivity and the failure of the US secondary school system. He identifies the millions of people dying of starvation every year while other nations stockpile surplus food, medical disasters such as heart disease, while governments subsidize grains used to produce high cholesterol meat, milk and eggs; and many more. One implication is clear: systems engineering faces challenges well beyond the sphere of engineering."

"Emergence is not really mysterious, although it may be complex. Emergence is brought about by the interactions between the parts of a system. The galloping horse illusion depends upon the persistence of the human retina/brain combination, for instance. Elemental gases bond in combination by sharing outer electrons, thereby altering the appearance and behavior of the combination. In every case of emergence, the source is interaction between the parts — sometimes, as with the brain, very many parts — so that the phenomenon defies simple explanation."

"Emergence is the phenomenon of properties, capabilities and behaviours evident in the whole system that are not exclusively ascribable to any of its parts. Classic examples of emergence include: self awareness from the human brain; the pungent smell of ammonia emerging from two colorless, odorless gases-nitrogen and hydrogen; and so on."

"For continued system cohesion, the mean rate of system adaptation must equal or exceed the mean rate of change of environment."

"Soft systems viewpoints are those held by behavioural, management, social anthropology, social psychology and other science students concerned with observing the living world, and in particular the human world. Human activity systems (HASs) are messy, in that they do not exhibit a clear need or purpose - if they can be said to exhibit purpose at all. Indeed, so complex is the real world of people that the idea of driving towards optimal solutions may be a non-starter - perhaps we should see if we can simply understand and concern ourselves with improving the situation."

"Hard systems viewpoints are basically those held by designers and engineers who are trying to create systems to meet an understood need in an effective and economic manner. Those in the soft camp caricature the approach as head-down, concerned with optimization, obsessed with quantitative metrics and highly pragmatic. So much so, in fact, that the term system thinking has been purloined by the soft camp as though they alone thought! The soft camp use the term engineer’s philosophy, not too endearingly, to describe the hard approach, in which the requirement is stated by a customer and the engineer satisfies the requirement without question."

"There seem to be two fundamental schisms in thinking: the hard/soft and the open/closed."

"The world about us can be looked at in a variety of ways. One way is to see the world as made up from many interacting systems: weather, societal, economic, ecological, floral, faunal, tectonic plate, oceanic, and so on. This is very much a connected view of the world: nothing is isolated and totally independent; everything is part of something bigger, and everything comprises many interacting parts — subsystems."

"The real world is made from open, interacting systems, behaving chaotically."

"The Holy Grail of systems engineering, a generic systems methodology has been the subject of the author’s ongoing research for over 20 years."

"Interest in the human-operator problem was stimulated by Prof. Arnold Tustin of the University of Birmingham, England, who suggested the application of the delay-line synthesizer to the study of some tracking records which he had brought with him from England. His experimental setup from which data were obtained consisted of a movable handle unit whose output was integrated once and then made to position a mechanical pointer. A second pointer, located next to the handle-driven pointer, was given an input motion consisting of a number of sinusoidal components of a nature sufficiently involved to prevent anticipation by an operator. The operator, upon noticing an error or difference between the two pointers, was required to move the handle in such a way as to reduce this error to a minimum value..."

"The fellow who is able to get the grants and contracts is the fellow who gets the doctoral students. Each student publishes two or three papers on his thesis, in each of which he cites his professor's work. Then he goes on and does his own subsequent work, in which, of course, he cites those thesis papers which were coauthorised by his professor."

"The lack of formal definition does not prevent us from noting the characteristics which are frequently present in large scale systems. Each such system has a certain integrity. It may or may not be rigidly controlled from some central point, but in every case, all the parts of the system have some common purpose; in some sense, they all contribute to the production of a single set of optimum outputs from the given set of inputs, with respect to some appropriate measure of effectiveness."

"A new concept and a new method were needed. The concept from the engineering standpoint is the evolution of the engineering scientist, i.e., the scientific generalist who maintains a broad outlook. The method is that of the team approach. On large-scale-system problems, teams of scientists and engineers, generalists as well as specialists, exert their joint efforts to find a solution and physically realize it. We are led to the concept of the system-design team, a small group of engineers or scientists, to lead a large project and organize the system effort. Such men have been variously called engineering scientists, system engineers, system analysts, or large-scale-system designers. The technique has been variously called the systems approach or the team development method. It is toward this man and his teammates that these discussions are directed. With the realization that not enough can be learned in all the required fields to make him a specialist, enough is introduced to make him aware of the language and problems of the specialist. This generalist is a new quantity in the engineering world, and his education must be begun."

"There are four distinct bases on which a system-design book might be organized. First are the chronological phases through which the system-design effort passes, such as organization and preliminary design. Second are the logical steps such as analysis of the single thread (operation on a single input) and high traffic (methods of handling multiplex inputs). Third are the parts of the system, such as communications and displays. Fourth are the tools of system design, such as information theory and queueing theory."

"[Systems should be classified] on the basis of the types of inputs with which they must cope."

"[This set of inputs [can be defined] as 1) input which is always the same or is of many types, 2) input which occurs periodically (or very infrequently), and 3) input which does or does not seek to destroy the system. Their rationale for developing the classification was to aid in the definition of steps to be followed in order to find the] solution of the problem of a large-scale or complex system."

"Every large-scale system is an . The automatic factory, the vehicular-traffic system, any military system- in the design of all these systems, primary attention should be given to the flow of information about the elements of the system."

"Management has a design and operation function, as does engineering. The design is usually done under the heading of organization. It should be noted first that the performance of a group of people is a strong function of the capabilities of the individuals and a rather weak function of the way they are organized. That is, good people do a fairly good job under almost any organization and a somewhat better one when the organization is good. Poor talent does a poor job with a bad organization, but it is still a poor job no matter what the organization. Repeated reorganizations are noted in groups of individuals poorly suited to their function, though no amount of good organization will give good performance. The best architectural design fails with poor bricks and mortar. But the payoff from good organization with good people is worthwhile."

"In April of 1959, ten of this country's leading scholars forgathered on the campus of Purdue University to discuss the nature of information and the nature of decision... What interests do these men have in common?... To answer these questions it is necessary to view the changing aspect of the scientific approach to epistemology, and the striking progress which has been wrought in the very recent past. The decade from 1940 to 1950 witnessed the operation of the first stored- program digital computer. The concept of information was quantified, and mathematical theories were developed for communication (Shannon) and decision (Wald). Known mathematical techniques were applied to new and important fields, as the techniques of complex- variable theory to the analysis of feedback systems and the techniques of matrix theory to the analysis of systems under multiple linear constraints. The word "cybernetics" was coined, and with it came the realization of the many analogies between control and communication in men and in automata. New terms like "operations research" and "system engineering" were introduced; despite their occasional use by charlatans, they have signified enormous progress in the solution of exceedingly complex problems, through the application of quantitative ness and objectivity."

"At this time it is difficult to put one's finger on any single contribution in the decade 1950 - 1960 which is comparable to those above, and yet progress has probably been even greater. From the point of view of an educator, one cannot overlook the wide distribution which has been given to these ideas. There has been remarkable progress from analysis to synthesis, always a sign of maturity in a field of analytic endeavour. There has been consolidation, for example in the establishment of a more rigorous basis for information theory; there has been unification, for example in the demonstration of the formal similarity between game theory and ; there has been application to mathematically more difficult situations, for example nonlinear servo systems and information channels with memory; there has been implementation, as in commercially available computers which by any reasonable measure are hun- dreds of times more powerful than the primitive devices of 1950; there has been de-limitation of the boundaries of many of these fields."

"We have discovered in this past decade that thinking, and decision, are not solely the province of the metaphysicist, but are appropriate subjects for scientific inquiry."

"We assert that it is possible to describe analytically any human function which can be reasonably defined in objective terms and we specifically include in such functions "thinking" insofar as that term is definable. If by "thinking" one means being able to do arithmetic, or play a good game of chess, or learn from experience, or make optimal decisions in exceedingly complex situations, then we assert that thinking can be described analytically. And there are two important corollaries: if It can be described analytically, it can be simulated; and if it can be simulated, it can be performed mechanically."

"[There is a] basic problem … of building a mathematical model of thought processes, and in particular of those aspects of thought which are concerned with information and decision processes. The perceptron is one type of model -- a set of memory devices connected in random fashion-- which has not yet achieved useful results but certainly seems to be a promising approach. The self-adaptive feedback control system which goes beyond the normal servo function of controlling its output, and in addition controls the parameters by which it controls its output is another which has already achieved pragmatic results in equipment control. It may be that the question of self-adaptation is a key to the whole question of how the human functions in a decisioning situation. For in many cases the ability of the human mind to adapt itself to a changing and complex environment is beyond our present aims in model construction."

"Sometimes it is more difficult to formulate the criterion for a problem than to state the question itself."

"Everyone knows what engineering is. All that's left is to define systems, and I'm not fool enough to do that."

"The purpose and real value of systems engineering is... to keep going around the loop; find inadequacies and make improvements."

"Mathematicians are there to find the constraints and to eliminate those things that aren't constraints... I know this will surprise many of you, but they are useful!"

"Scientists possess healthy skepticism. They realize that you've got to know the answer before you measure it."

"The ideal system engineer is an engineer thoroughly versed in his field but conversant with and knowledgeable of other fields. You have to have the capability and desire to become a 'six-month expert'... You've got to want to become a generalist, too."

"The conclusions of most good operations research studies are obvious."

"If the assumptions are wrong, the conclusions aren't likely to be very good."

"There comes a time when one must stop suggesting and evaluating new solutions, and get on with the job of analyzing and implementing one pretty good solution."

"Sometimes, where a complex problem can be illuminated by many tools, one can be forgiven for applying the one he knows best."

"Most accidents in well-designed systems involve two or more events of low probability occurring in the worst possible combination."

"The pressure to generate the ideas and methods attributed to Systems Engineering stems directly from the needs of 20th century society. As our frontiers have disappeared, man has turned to technology to furnish the "good life" in a rapidly shrinking, crowded world. Our interdependence upon one another has increased in direct proportion to the population increase. The race to maintain or improve the operating efficiency of society has required that the systems and mechanisms that serve the society also become increasingly complex and interdependent. Goode and Machal have provided statistics to illustrate the above. They note that the world population increased from 800 million in 1750, to 1200 million in 1850, and 2400 million in 1950. Maximum transportation speeds went from 40 mph in 1850, and 100 mph in 1900, to commercial transport speed of 350 mph in 1950 and supersonic transport planes of over 1200 mph in the 1960's. Our communication systems are a good indication of increasing complexity. U.S. telephones jumped from 350,000 in 1900, to 55 million in 1955."

"At an age when many people consider retiring, Robert E. Machol stopped teaching at Northwestern University and started a new career as chief scientist for the Federal Aviation Administration. There, while in his 70s, he predicted "catastrophe" after studying the turbulence created by the jet engines of 757 airplanes--work that predicted fatal crashes and eventually led to a change in federal aviation policy... "I was the first guy within the agency who got up and said, `We're likely to have a catastrophe, a real catastrophe … if we don't do something," Mr. Machol told the Los Angeles Times in 1994. Eventually, the agency ordered landing aircraft to maintain a greater distance behind 757s to avoid the jet's dangerous "wake vortex." But the policy change came only after crashes in Billings, Mont., and Santa Ana, Calif., that killed 13 people."

"Bob Machol's life involved a number of strands — aviation, scientific writing, systems engineering, chemistry, research, applying OR to sports, computing and mushrooms — that intertwined over the years. Consider his involvement with aviation. It started in 1940 when, fresh out of Harvard, Bob enlisted in the Marines, intent on becoming an aviator. Although Bob didn't earn his pilot's wings, he did emerge from World War II holding the rank of lieutenant commander. Following the war, Bob became involved with research organizations (the Operations Evaluation Group and the University of Michigan's Willow Run Laboratories) that were looking for improved ways of defending the United States against air attack. This work led to Bob's groundbreaking book, "Systems Engineering," co-authored with the late Harry H. Goode."

"I recount this as it reminds me of some of the lessons Bob preached and practiced throughout his professional career:"