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  2. Thermodynamic system - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_system

    The presence of reactants in an open beaker is an example of an open system. Here the boundary is an imaginary surface enclosing the beaker and reactants. It is named closed , if borders are impenetrable for substance, but allow transit of energy in the form of heat, and isolated , if there is no exchange of heat and substances.

  3. Closed system - Wikipedia

    en.wikipedia.org/wiki/Closed_system

    Properties of isolated, closed, and open systems in exchanging energy and matter. In thermodynamics, a closed system can exchange energy (as heat or work) but not matter, with its surroundings. An isolated system cannot exchange any heat, work, or matter with the surroundings, while an open system can exchange energy and matter.

  4. Open and closed maps - Wikipedia

    en.wikipedia.org/wiki/Open_and_closed_maps

    This function from the unit circle to the half-open interval [0,2π) is bijective, open, and closed, but not continuous. It shows that the image of a compact space under an open or closed map need not be compact. Also note that if we consider this as a function from the unit circle to the real numbers, then it is neither open nor closed.

  5. Closed-form expression - Wikipedia

    en.wikipedia.org/wiki/Closed-form_expression

    The quadratic formula =. is a closed form of the solutions to the general quadratic equation + + =. More generally, in the context of polynomial equations, a closed form of a solution is a solution in radicals; that is, a closed-form expression for which the allowed functions are only n th-roots and field operations (+,,, /).

  6. Control loop - Wikipedia

    en.wikipedia.org/wiki/Control_loop

    There are two common classes of control loop: open loop and closed loop. In an open-loop control system, the control action from the controller is independent of the process variable. An example of this is a central heating boiler controlled only by a timer. The control action is the switching on or off of the boiler.

  7. Closed system (control theory) - Wikipedia

    en.wikipedia.org/wiki/Closed_system_(control_theory)

    The terms closed system and open system have long been defined in the widely (and long before any sort of amplifier was invented) established subject of thermodynamics, in terms that have nothing to do with the concepts of feedback and feedforward. The terms 'feedforward' and 'feedback' arose first in the 1920s in the theory of amplifier design ...

  8. Open system (systems theory) - Wikipedia

    en.wikipedia.org/wiki/Open_system_(systems_theory)

    In the social sciences an open system is a process that exchanges material, energy, people, capital and information with its environment. French/Greek philosopher Kostas Axelos argued that seeing the "world system" as inherently open (though unified) would solve many of the problems in the social sciences, including that of praxis (the relation of knowledge to practice), so that various social ...

  9. System - Wikipedia

    en.wikipedia.org/wiki/System

    Systems can be isolated, closed, or open. A system 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 its environment, is described by its boundaries, structure and purpose and is expressed in its functioning.