Open system (systems theory) Open System Model (basics) In system theory, an open system is a system which continuously interacts with its environment or surroundings.
The interaction can take the form of information, energy, or material transfers into or out of the system boundary, depending on the discipline which defines the concept.
SYSTEM DYNAMICS. Systems theory. Ludwig von Bertalanffy. Karl Ludwig von Bertalanffy (September 19, 1901, Atzgersdorf near Vienna – June 12, 1972, Buffalo, New York) was an Austrian-born biologist known as one of the founders of general systems theory (GST).
GST is an interdisciplinary practice that describes systems with interacting components, applicable to biology, cybernetics, and other fields. Bertalanffy proposed that the classical laws of thermodynamics applied to closed systems, but not necessarily to "open systems," such as living things. His mathematical model of an organism's growth over time, published in 1934, is still in use today. Ludwig von Bertalanffy, General System Theory (1968) Bertalanffy's General Systems Theory: The Topology of Mind Development. By Gregory Mitchell Systems theory studies the structure and properties of systems in terms of relationships, from which new properties of wholes emerge.
It was established as a science by Ludwig von Bertalanffy, Anatol Rapoport, Kenneth E. Systems thinking. Impression of systems thinking about society A system is composed of interrelated parts or components (structures) that cooperate in processes (behavior).
Natural systems include biological entities, ocean currents, the climate, the solar system and ecosystems. Designed systems include airplanes, software systems, technologies and machines of all kinds, government agencies and business systems. Systems Thinking has at least some roots in the General System Theory that was advanced by Ludwig von Bertalanffy in the 1940s and furthered by Ross Ashby in the 1950s. The term Systems Thinking is sometimes used as a broad catch-all heading for the process of understanding how systems behave, interact with their environment and influence each other. Systems thinking has been applied to problem solving, by viewing "problems" as parts of an overall system, rather than reacting to specific parts, outcomes or events and potentially contributing to further development of unintended consequences.
Hard systems. In systems science Hard systems is a title sometimes used to differentiate between different types of systems problems.
It is opposing soft systems. Overview While Soft systems thinking treats all problems as ill-defined or not easily quantified, Hard systems approaches (Systems analysis (structured methods), Operations research and so on) assume that: the problems associated with such systems are well-definedthey have a single, optimum solutiona scientific approach to problem-solving will work welltechnical factors will tend to predominate Methodology In hard systems approaches (or Structured Systems Analysis and Design Methodology (SSADM)), rigid techniques and procedures are used to provide unambiguous solutions to well-defined data and processing problems. Soft systems methodology. Overview It is a common misunderstanding that SSM is a methodology for dealing solely with ‘soft problems’ (i.e., problems which involve psychological, social, and cultural elements).
SSM does not differentiate between ‘soft’ and ‘hard’ problems, it merely provides a different way of dealing with situations perceived as problematic. The ‘hardness’ or ‘softness’ is not the intrinsic quality of the problem situation to be addressed, it is an aspect of the way those involved address the situation. Each situation perceived as problematic has both ‘hard’ and ‘soft’ elements. The very notion of a problem is contingent on a human being perceiving it as such. e.g. Dynamic equilibrium. A dynamic equilibrium exists once a reversible reaction ceases to change its ratio of reactants/products, but substances move between the chemicals at an equal rate, meaning there is no net change.
It is a particular example of a system in a steady state. In thermodynamics a closed system is in thermodynamic equilibrium when reactions occur at such rates that the composition of the mixture does not change with time. Reactions do in fact occur, sometimes vigorously, but to such an extent that changes in composition cannot be observed. Equilibrium constants can be expressed in terms of the rate constants for elementary reactions. Examples System dynamics. Dynamic stock and flow diagram of model New product adoption (model from article by John Sterman 2001) System dynamics is an approach to understanding the behaviour of complex systems over time.
It deals with internal feedback loops and time delays that affect the behaviour of the entire system. What makes using system dynamics different from other approaches to studying complex systems is the use of feedback loops and stocks and flows. These elements help describe how even seemingly simple systems display baffling nonlinearity.
Overview Open system (systems theory) Closed system. The term closed system refers to a physical system which does not allow certain types of transfers (such as transfer of mass) in or out of the system.
The specification of what types of transfers are excluded, is different in different contexts. In physics In classical mechanics In nonrelativistic classical mechanics, a closed system is a physical system which doesn't exchange any matter with its surroundings, and isn't subject to any force whose source is external to the system. A closed system in classical mechanics would be considered an isolated system in thermodynamics. Transient state. In chemical and electrical engineering, a system is said to be in a transient state when a process variable has been changed and the system has not yet reached steady-state.
(Transient effect). When a chemical reactor is being brought into operation, the concentrations, temperatures, species compositions, and reaction rates are changing with time until operation reaches it nominal process variables. Steady state. In systems theory, a system in a steady state has numerous properties that are unchanging in time. This means that for those properties p of the system, the partial derivative with respect to time is zero: Homeostasis. Homeostasis, also spelled homoeostasis (from Greek: ὅμοιος homœos, "similar" and στάσις stasis, "standing still"), is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.
Examples of homeostasis include the regulation of temperature and the balance between acidity and alkalinity (pH). It is a process that maintains the stability of the human body's internal environment in response to changes in external conditions. The concept was described by French physiologist Claude Bernard in 1865 and the word was coined by Walter Bradford Cannon in 1926. Although the term was originally used to refer to processes within living organisms, it is frequently applied to automatic control systems such as thermostats. Homeostasis requires a sensor to detect changes in the condition to be regulated, an effector mechanism that can vary that condition; and a negative feedback connection between the two. Biological Biosphere "The Macroscope", a book on the systems approach.
International Society for the Systems Sciences. The International Society for the Systems Sciences (ISSS) is a world-wide organization for systems sciences. The overall purpose of the ISSS is: "to promote the development of conceptual frameworks based on general system theory, as well as their implementation in practice. It further seeks to encourage research and facilitate communication between and among scientists and professionals from various disciplines and professions at local, regional, national, and international levels. " International Society for the Systems Sciences. The International Society for the Systems Sciences (ISSS) is among the first and oldest organizations devoted to interdisciplinary inquiry into the nature of complex systems, and remains perhaps the most broadly inclusive.
The Society was initially conceived in 1954 at the Stanford Center for Advanced Study in the Behavioral Sciences by Ludwig von Bertalanffy, Kenneth Boulding, Ralph Gerard, and Anatol Rapoport. In collaboration with James Grier Miller, it was formally established as an affiliate of the American Association for the Advancement of Science in 1956. Originally founded as the Society for General Systems Research, the society adopted its current name in 1988 to reflect its broadening scope.