Classification of Systems

Different Ways to Classify Systems

There are many different ways to classify systems: open versus closed, static versus dynamic, natural versus human-made, etc. Of course, a system may be classified along several dimensions, and few systems created by people are purely one type of system only, but thinking through the different types of systems involved in any enterprise can help develop plans for operations, including plans to respond to emergency or disaster situations.

A closed system has no significant interactions with its environment; one example is a chemical reaction in a closed glass container. The results of interactions within a closed system are deterministic and can be predicted from initial conditions. An open system, in contrast, interacts with its environment, allowing information, matter, and energy to cross its boundaries; examples of open systems include business organizations, ecological systems, and plants. A static system such as a bridge has structure but not activity, while a dynamic system such as a school has both structure and activity. Of course, any system is static only in a limited frame of reference: although a bridge does not move, it is constructed and will break down over time, both dynamic processes; in addition, it may be deliberately altered or maintained, both dynamic processes.

Natural systems are created through natural processes and have a high degree of order and equilibrium; examples include the food chain and the natural water cycle. Elements within a natural system adapt to their environment and to events within it, and materials are continually recirculated; natural systems survive if they adapt to changes in the environment; those that do not become extinct. Human-made systems are relatively recent in origin, as the rapid development of technology has multiplied the impact of modern humans on the environment. Human-made systems often produce unintended consequences; for instance, the construction of the High Aswan Dam on the Nile River achieved its goals of producing hydroelectricity and controlling flooding, but also produced negative, unanticipated consequences, including harming the fishing industry, increasing erosion in the Nile Delta, and fostering epidemics of bilharzia along the Nile. A systems view would have taken into account the side effects of the dam's creation and might have come up with a better solution or mitigated the problems.

...