Asystem is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole.[1] A system, surrounded and influenced by itsenvironment, is described by its boundaries,structure and purpose and is expressed in its functioning. Systems are the subjects of study ofsystems theory and othersystems sciences.
Systems have several common properties and characteristics, including structure, function(s), behavior and interconnectivity.
The termsystem comes from theLatin wordsystēma, in turn fromGreekσύστημαsystēma: "whole concept made of several parts or members, system", literary "composition".[2][3]
In the 19th century, the French physicistNicolas Léonard Sadi Carnot, who studiedthermodynamics, pioneered the development of the concept of asystem in thenatural sciences. In 1824, he studied the system which he called theworking substance (typically a body of water vapor) insteam engines, in regard to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a boiler, a cold reservoir (a stream of cold water), or a piston (on which the working body could do work by pushing on it). In 1850, the German physicistRudolf Clausius generalized this picture to include the concept of thesurroundings and began to use the termworking body when referring to the system.
The biologistLudwig von Bertalanffy became one of the pioneers of thegeneral systems theory. In 1945 he introducedmodels, principles, and laws that apply to generalized systems or their subclasses, irrespective of their particular kind, the nature of their component elements, and the relation or 'forces' between them.[4]
In the 1960s,Marshall McLuhan applied general systemstheory in an approach that he called afield approach andfigure/ground analysis, to the study ofmedia theory.[7][8]
Systems theory views the world as acomplex system of interconnected parts. One scopes a system by defining itsboundary; this means choosing whichentities are inside the system and which are outside—part of theenvironment. One can 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 behavior of the system.
There are natural and human-made (designed) systems. Natural systems may not have an apparent objective but their behavior can be interpreted as purposeful by an observer. Human-made systems are made with various purposes that are achieved by some action performed by or with the system. The parts of a system must be related; they must be "designed to work as a coherent entity"—otherwise they would be two or more distinct systems.
Open systems have input and output flows, representing exchanges of matter, energy or information with their surroundings.
Most systems areopen systems, exchanging matter and energy with their respective surroundings; like a car, acoffeemaker, orEarth. Aclosed system exchanges energy, but not matter, with its environment; like a computer or the projectBiosphere 2. Anisolated system exchanges neither matter nor energy with its environment. A theoretical example of such a system is theUniverse.
Anopen system can also be viewed as a bounded transformation process, that is, ablack box that is a process or collection of processes that transform inputs into outputs. Inputs are consumed; outputs are produced. The concept of input and output here is very broad. For example, an output of a passenger ship is the movement of people from departure to destination.
A system comprisesmultiple views. Human-made systems may have such views as concept,analysis,design,implementation, deployment, structure, behavior, input data, and output data views. Asystem model is required to describe and represent all these views.
Asubsystem is a set of elements, which is a system itself, and a component of a larger system. The IBM MainframeJob Entry Subsystem family (JES1,JES2,JES3, and theirHASP/ASP predecessors) are examples. The mainelements they have in common are the components that handle input, scheduling, spooling and output; they also have the ability to interact with local and remote operators.
A subsystem description is a system object that contains information defining the characteristics of an operating environment controlled by the system.[9] The data tests are performed to verify the correctness of the individual subsystem configuration data (e.g. MA Length, Static Speed Profile, …) and they are related to a single subsystem in order to test its Specific Application (SA).[10]
There are many kinds of systems that can be analyzed bothquantitatively andqualitatively. For example, in an analysis of urbansystems dynamics, A . W. Steiss defined five intersecting systems, including the physical subsystem and behavioral system. For sociological models influenced by systems theory,[11]Kenneth D. Bailey defined systems in terms ofconceptual,concrete, and abstract systems, eitherisolated,closed, oropen.[12]Walter F. Buckley defined systems in sociology in terms ofmechanical,organic, andprocess models.[13]Bela H. Banathy cautioned that for any inquiry into a system understanding its kind is crucial, and definednatural anddesigned, i. e. artificial, systems.[14] For example, natural systems includesubatomic systems,living systems, theSolar System,galaxies, and theUniverse, while artificial systems include man-made physical structures, hybrids of natural and artificial systems, and conceptual knowledge. The human elements of organization and functions are emphasized with their relevant abstract systems and representations.
Artificial systems inherently have a major defect: they must be premised on one or more fundamental assumptions upon which additional knowledge is built. This is in strict alignment withGödel's incompleteness theorems. The Artificial system can be defined as a "consistent formalized system which contains elementary arithmetic".[15] These fundamental assumptions are not inherently deleterious, but they must by definition be assumed as true, and if they are actually false then the system is not as structurally integral as is assumed (i.e. it is evident that if the initial expression is false, then the artificial system is not a "consistent formalized system"). For example, ingeometry this is very evident in the postulation oftheorems and extrapolation of proofs from them.
George J. Klir maintained that no "classification is complete and perfect for all purposes", and defined systems as abstract, real, andconceptualphysical systems, bounded andunbounded systems, discrete to continuous, pulse tohybrid systems, etc. The interactions between systems and their environments are categorized as relatively closed andopen systems.[16] Important distinctions have also been made betweenhard systems—–technical in nature and amenable to methods such assystems engineering, operations research, and quantitative systems analysis—andsoft systems that involve people and organizations, commonly associated with concepts developed byPeter Checkland andBrian Wilson throughsoft systems methodology (SSM) involving methods such asaction research and emphasis of participatory designs.[17] Where hard systems might be identified as morescientific, the distinction between them is often elusive.
The international sphere of interacting states is described and analyzed in systems terms by several international relations scholars, most notably in theneorealist school. This systems mode of international analysis has however been challenged by other schools of international relations thought, most notably theconstructivist school, which argues that an over-large focus on systems and structures can obscure the role of individual agency in social interactions. Systems-based models of international relations also underlie the vision of the international sphere held by theliberal institutionalist school of thought, which places more emphasis on systems generated by rules and interaction governance, particularly economic governance.
There are systems of counting, as withRoman numerals, and various systems for filing papers, or catalogs, and various library systems, of which theDewey Decimal Classification is an example. This still fits with the definition of components that are connected together (in this case to facilitate the flow of information).
System can also refer to a framework, akaplatform, be itsoftware or hardware, designed to allow software programs to run. A flaw in a component or system can cause the component itself or an entire system to fail to perform its required function, e.g., an incorrectstatement ordata definition.[18]
Inengineering andphysics, a physical system is the portion of the universe that is being studied (of which athermodynamic system is one major example). Engineering also has the concept of a system referring to all of the parts and interactions between parts of a complex project.Systems engineering is the branch of engineering that studies how this type of system should be planned, designed, implemented, built, and maintained.[18]
Sociology, cognitive science and management research
Social andcognitive sciences recognize systems in models of individual humans and in human societies. They include human brain functions and mental processes as well as normative ethics systems and social and cultural behavioral patterns.
There is also such a thing as alogical system. An obvious example is the calculus developed simultaneously byLeibniz andIsaac Newton. Another example isGeorge Boole's Boolean operators. Other examples relate specifically to philosophy, biology, or cognitive science.Maslow's hierarchy of needs applies psychology to biology by using pure logic. Numerous psychologists, includingCarl Jung andSigmund Freud developed systems that logically organize psychological domains, such as personalities, motivations, or intellect and desire.
In 1988, military strategistJohn A. Warden III introduced theFive Ring System model in his book,The Air Campaign, contending that any complex system could be broken down into five concentric rings. Each ring—leadership, processes, infrastructure, population and action units—could be used to isolate key elements of any system that needed change. The model was used effectively byAir Force planners in theIran–Iraq War.[21][22][23] In the late 1990s, Warden applied his model to business strategy.
^1945,Zu einer allgemeinen Systemlehre, Blätter für deutsche Philosophie, 3/4. (Extract in: Biologia Generalis, 19 (1949), 139–164.
^1948,Cybernetics: Or the Control and Communication in the Animal and the Machine. Paris, France: Librairie Hermann & Cie, and Cambridge, MA: MIT Press.Cambridge, MA: MIT Press.
^Warden, John A. III (September 1995)."Chapter 4: Air theory for the 21st century".Battlefield of the Future: 21st Century Warfare Issues. United States Air Force. Archived fromthe original(inAir and Space Power Journal) on July 4, 2011. RetrievedDecember 26, 2008.
^Warden, John A. III (1995)."Enemy as a System".Airpower Journal. Spring (9):40–55. Archived fromthe original on 2009-01-13. Retrieved2009-03-25.
