Systems engineering - Wikipedia
Definitions of Systems and Models by Michael Pidwirny, – Publications with the title "System" (–) by Roland Müller. Definitionen von "System" Systems science. Systems types. Anatomical. Science contributes to technology in at least six ways: (1) new knowledge which serves R.R. Nelson, N. RosenbergTechnical innovation and national systems. Fritjof Capra explores how Science & Spirituality can be fused in an integrated system that returns us to a sense of oneness with the natural.
First, they provided new tools for analyzing complex systems by means of extensive calculations or direct simulation. In the second place, they could be used to digest large amounts of data or as actual constituents of complex systems, especially those concerned largely with information transmission.
This opened up the possibility of processing information as well as simply transmitting it in such systems see also information processing. The impact of military weapons problems on systems engineering began soon after World War II. A landmark date waswhen the development of Nike Ajax, a U. In available rocket propulsion seemed barely sufficient to give the missile a satisfactory tactical range.
Control and feedback questions were also important aspects of the overall systems problem. The whole system was in fact a gigantic feedback loop because the missile was controlled by orders sent it from a ground computer, and the computer input included information on what the tracking radar observed the missile to be doing. Thus there was a closed feedback loop from missile to computer and back to the missile again.
In the s and s systems engineering also grew in other directions, largely as a result of weapons systems projects associated with the Cold War. Thus the Ajax study was concerned with the dynamics of a single isolated missile. On the other hand, the defense systems that grew up in the s involved the coordinated operation of a large number of missiles, guns, interceptors, and radar installations scattered over a considerable area.
These were all held together by a large digital computerwhich thus became the central element of the system. During the same years the systems approach also became increasingly identified with management functions. So-called planning, programming, and budgeting PPB techniques were developed to provide similar combinations of systems engineering and financial management.
In nonmilitary fields systems engineering has developed along similar though more modest lines. Early applications were likely to stress feedback control systems in large-scale automated production facilities, such as steel-rolling mills and petroleum refineries.
Later applications stressed computer-based management information and control systems somewhat like those that had earlier been developed for air defense. In more recent years the systems approach has occasionally been applied to much larger civilian enterprises, such as the planning of new cities.
Systems engineering techniques, tools, and procedures If a system is both large and complex in the sense in which these terms have been defined, it may be difficult to find out how it works. A large part of the content of systems engineering consists of techniques for the investigation of such relatively complex situations. Modeling and optimization Perhaps the most fundamental technique is the flow diagram, or flowcharta graphical display composed of boxes representing individual components or subsystems of the complete system, plus arrows from box to box to show how the subsystems interact.
Though such a representation is very useful in an initial study, it is, of course, essentially qualitative.Relationship Between Mathematics & Science Subjects : Easy-to-Intermediate Math
A more effective approach in the long run is construction of a so-called mathematical modelwhich consists of a set of equations, or sometimes simply of tables and curves, describing the interactions within the system in quantitative terms.
It is not necessary for the mathematical model to be exact, as long as it serves its purpose. It frequently consists of piecewise linear approximations to basically nonlinear situations i.
After the model has been constructed and checked, a number of mathematical techniques can be employed including straightforward enumeration and computing to find out what it says about the actual operation of the system. Often these calculations will have a probabilistic or statistical flavour.
When the components or subsystems interact significantly, it may be possible to achieve essentially the same final level of performance in many different ways. Limited performance by one subsystem may be offset by superior performance somewhere else. These optimization studies, called trade-offs, are important in suggesting how to achieve a given result in the most economical manner. They are equally valuable in suggesting whether or not the proposed result is in fact a reasonable goal to aim for.
It may be found, for example, that a modest reduction in performance will permit radical savings in overall cost or, conversely, that the postulated equipment is capable of much better performance than is asked of it, at only nominally greater expense. It may also turn out that the equipment can supply useful functions not originally contemplated.
Computing systems, for example, can usually perform extra chores of record keeping at little increased cost. For all of these reasons, studies of such variables are an important part of systems engineering, both in the early exploratory phases of a project and in the final design.
Identifying objectives The formulation of suitable objectives for the final system is so important a part of the systems engineering process that it deserves special attention. It is, of course, always possible to state the general objectives of a system in vague or perfectionist terms. A sufficiently clear, precise, and comprehensive statement to serve as a basis for engineering studieshowever, is another matter.
Unless the situation has been well explored in the past, the real choices are not likely to be obvious when the work begins. Thus, the first task of the systems engineer is to develop as clear a formulation of objectives as possible.
This usually involves computations and consultation with others interested in the system. Because the final statement must reflect value judgments as well as purely technical considerations, the systems engineer does not try to do this thinking alone but attempts to serve as a working focus and catalyst.
Although issues of this sort naturally present themselves with particular force near the beginning of a systems study, they may recur in subsequent steps. The principal reason why a satisfactory statement of objectives may present such a problem is simply that most systems have multiple objectives, often in conflict with one another. In the design of transport aircraft, for example, there are a multitude of desirable characteristics, such as range, speed, payload, and safety, to be maximized, as well as undesirable characteristics, such as noise generation and air pollutionto be minimized.
Because the same design cannot do the best job in all of these directions, a compromise achieving the most desirable overall performance is required.
The most attractive compromise, which may require both study and ingenuity, is not likely to be found at all until some hard thinking has been done about what characteristics are really needed. Especially difficult problems in defining objectives may arise when an existing technology is transplanted to some new disciplinary area. An example is the application of electronics such as computer techniques to medicine and education.
It seldom happens in such cases that the best system is based on a simple one-for-one substitution, such as direct replacement of a classroom teacher by electronic hardware and computer-assisted instruction materials. It is much more likely that the most effective plan will turn out to be a rather complicated mixture of the old and the new. This conclusion, however, is likely to raise basic issues about the actual objectives of the new system, issues made no simpler by the interdisciplinary nature of the situation.
A design example The design of the commercial transport plane mentioned above is an example of a systems engineering problem. In such a design the aerodynamic liftthe drag of fuselage and wings, the control apparatus, the propulsion system, and such auxiliary hardware as the landing gear all interact substantially. One element cannot be disturbed without affecting the others; all elements and aspects of the total system, and the interactions among them, must be considered. Thus, if designers make the fuselage fatter and the wings smaller in an effort to carry more payload at the same or higher speeds, a new control system might be needed because of the changes produced in the overall mechanical and aerodynamic characteristics of the vehicle.
Stronger and heavier landing gear might be needed to withstand higher landing speeds.
Almost surely, the new design would call for larger engines and fuel tanks to compensate for greater aerodynamic drag. Thus the designers would have lost ground in some respects and gained in others.
The new plane might be more useful for short flights when not much fuel must be carried but less useful for long ones. Obviously, the system objective—the kind of airplane actually wanted—must control the direction of any such study. The study becomes more interesting if a possible advance in basic technology is considered, such as an improvement in propulsion or aerodynamics, and it is desired to determine how it might best be applied in a new airplane design. The central systems engineering question then would probably encompass the relation between the available new plane characteristics and the needs of the existing air transportation system.
Clearly, such an investigation can be made only by going to one of the upper levels in the systems hierarchy. Though, under normal circumstances, these might readily be handled by the existing operating staff, it is part of the user orientation of the systems approach that the systems engineer is expected to anticipate any new requirements and make sure they are properly planned for. To make adequate comparisons between competing objectives, a logical frame of referencebroad enough to include both, is needed.
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Thus, the systems engineer may study many situations in the framework of more than one system or a whole hierarchy of systems of steadily increasing generality. Though the simplest system—the airplane itself—is a satisfactory reference for specific design problems, a more general framework may be needed to approach broader problems.
Thus the individual airplane designer may seek to ameliorate air-traffic congestion by improving airplane takeoff and landing characteristics, permitting better utilization of existing airports. The airlines in turn may suggest construction of more and better airports. From the point of view of the transportation system as a whole, the best step might be to invest more money in high-speed rail facilities to carry part of the air-traffic load.
In systems engineering the error of studying the problem within too narrow a framework is called the error of suboptimization. User orientation The stress on systems objectives has one further consequence worth mentioning; i. This results naturally enough from the fact that systems objectives usually relate to overall performance, which is what the final user is interested in.
The identity of technical interest between the systems engineer and the final user is usually marked; systems engineering is likely to give special consideration to such qualities as reliability, ease of maintenance, and convenience in operation. Moreover, the final step of a systems engineering project is typically an evaluation that attempts to find out how well the system works in the hands of the user.
Tools The most obvious aspect of systems engineering tools is their great diversity. To this list might also be added decision theorynonlinear programming, some elements of econometrics, and communications theory as related to random processes. In spite of this diversity, many of the tools of systems theory can be grouped under a few major headings. The analytic problems associated with optimization, for example, are a recurrent theme. Probability and statistics are also major areas that carry with them numerous more specialized topics, such as queuing theory and much of communications theory.
Finally, computing is a major field for the systems engineer. If all else fails, direct calculation or simulation may produce the desired results. These fields are all essentially mathematical in nature. The trade study in turn informs the design, which again affects graphic representations of the system without changing the requirements.
In an SE process, this stage represents the iterative step that is carried out until a feasible solution is found. A decision matrix is often populated using techniques such as statistical analysis, reliability analysis, system dynamics feedback controland optimization methods.
Other tools[ edit ] Systems Modeling Language SysMLa modeling language used for systems engineering applications, supports the specification, analysis, design, verification and validation of a broad range of complex systems. The following areas have contributed to the development of systems engineering as a distinct entity: Cognitive systems engineering Cognitive systems engineering CSE is a specific approach to the description and analysis of human-machine systems or sociotechnical systems.
CSE has since its beginning become a recognized scientific discipline, sometimes also referred to as cognitive engineering. The concept of a Joint Cognitive System JCS has in particular become widely used as a way of understanding how complex socio-technical systems can be described with varying degrees of resolution.
The more than 20 years of experience with CSE has been described extensively. Control engineering Control engineering and its design and implementation of control systemsused extensively in nearly every industry, is a large sub-field of systems engineering. The cruise control on an automobile and the guidance system for a ballistic missile are two examples.
Control systems theory is an active field of applied mathematics involving the investigation of solution spaces and the development of new methods for the analysis of the control process. Industrial engineering Industrial engineering is a branch of engineering that concerns the development, improvement, implementation and evaluation of integrated systems of people, money, knowledge, information, equipment, energy, material and process.
Industrial engineering draws upon the principles and methods of engineering analysis and synthesis, as well as mathematical, physical and social sciences together with the principles and methods of engineering analysis and design to specify, predict, and evaluate results obtained from such systems.
Interface design Interface design and its specification are concerned with assuring that the pieces of a system connect and inter-operate with other parts of the system and with external systems as necessary. Interface design also includes assuring that system interfaces be able to accept new features, including mechanical, electrical and logical interfaces, including reserved wires, plug-space, command codes and bits in communication protocols.
This is known as extensibility. Systems engineering principles are applied in the design of network protocols for local-area networks and wide-area networks. Mechatronic engineering Mechatronic engineeringlike systems engineering, is a multidisciplinary field of engineering that uses dynamical systems modeling to express tangible constructs.
System - Wikipedia
In that regard it is almost indistinguishable from Systems Engineering, but what sets it apart is the focus on smaller details rather than larger generalizations and relationships. As such, both fields are distinguished by the scope of their projects rather than the methodology of their practice.
Operations research Operations research supports systems engineering. The tools of operations research are used in systems analysis, decision making, and trade studies. Several schools teach SE courses within the operations research or industrial engineering department,  highlighting the role systems engineering plays in complex projects. Operations researchbriefly, is concerned with the optimization of a process under multiple constraints.
Performance is usually defined as the speed with which a certain operation is executed, or the capability of executing a number of such operations in a unit of time. Performance may be degraded when operations queued to execute is throttled by limited system capacity. For example, the performance of a packet-switched network is characterized by the end-to-end packet transit delay, or the number of packets switched in an hour.