System Concept

•         Environment and boundaries: Systems theory views the world as a complex system of interconnected parts. We scope a system by defining its boundary; this means choosing which entities are inside the system and which are outside - part of the environment. We then make simplified representations (models) of the system in order to understand it and to predict or impact its future behavior. These models may define the structure and/or the behavior of the system.

•         Natural and human-made systems: There are natural and human-made (designed) systems. Natural systems may not have an apparent objective but their outputs can be interpreted as purposes. Human-made systems are made with purposes that are achieved by the delivery of outputs. Their parts must be related; they must be “designed to work as a coherent entity” - else they would be two or more distinct systems.

•         Theoretical Framework: An open system exchanges matter and energy with its surroundings. Most systems are open systems; like a car, coffeemaker, or computer. A closed system exchanges energy, but not matter, with its environment; like Earth or the project Biosphere2 or 3. An isolated system exchanges neither matter nor energy with its environment. A theoretical example of such system is the Universe.

•         Process and transformation process : A system can also be viewed as a bounded transformation process, that is, a process or collection of processes that transforms inputs into outputs. Inputs are consumed; outputs are produced. The concept of input and output here is very broad. E.g., an output of a passenger ship is the movement of people from departure to destination.

•         Subsystem: A subsystem is a set of elements, which is a system itself, and a component of a larger system.

•         System Model :  A system comprises multiple views. For the man-made systems it may be such views as planning, requirement (analysis), design, implementation, deployment, structure, behavior, input data, and output data views. A system model is required to describe and represent all these multiple views.

•         System Architecture : A system architecture, using one single integrated model for the description of multiple views such as planning, requirement (analysis), design, implementation, deployment, structure,behavior, input data, and output data views, is a kind of system model.