system

Articles

• Spatial diffusion
  15 December 2004, by Th. St.-J.

  Diffusion is as well the action as the result of action to spread, or to transmit and propagate in a uniform way. It is thus expressed by all moves which, whatever their driving force, are trying to spread something in a system in an homogeneous way, thus tending to bring it from one equilibrium state to another equilibrium state when, under certain conditions, the system is saturated because its absorbing potential is exhausted. The notion of diffusion, considered from the action (...)

• Spatial mobility
  21 June 2012, by N. C.

  Spatial mobility is an essential component of the way societies organise space. It has been defined in various ways, in reference to different registers of observation and conceptualisation. In its most frequent acceptation, mobility is movement or travel from one «place» to another. This movement can concern people, but also material and immaterial goods, and information. The unit of measurement naturally depends on what is travelling, and can for instance be in terms of numbers of (...)

• City system
  10 May 2016, by D. P.

  A city system; is a group of cities, which, in their evolution, have become interdependent because of the many relationship networks that they have and that interconnect them to a greater extent than other cities located in the environment. It is often the borders of a national territory that constitute the boundaries of a city system, because of the homogeneity of the norms the territory imposes, which contribute to forming some of their relationships. With time, city systems have indeed (...)

• Isotropy/anisotropy
  8 September 2010, by Th. St.-J.

  An environment or medium is said to be isotropic if its physical properties are identical in all directions. A «system» will be termed isotropic if its (macroscopic) properties are invariant in relation to a particular direction, and therefore none of these properties is directionally dependent. Should one of its properties be directional, the system is not isotropic, but anisotropic. A physical magnitude can also be said to be anisotropic or isotropic according to whether or not it is (...)

• Contingency
  18 October 2005, by F.D.-D.

  A philosophical notion that seems particularly useful for geographical reasoning. Lalande goes back to Aristotle for the general meaning of the term: "Est contingent tout ce qui est conçu comme pouvant être ou ne pas être à quelque égard et sous quelque réserve que ce soit [. . .] ( Si bien qu’) un événement futur est contingent si, toutes choses étant ce qu’elles sont, ce futur peut se produire ou ne pas se produire"1 . (The term is opposed in all its meanings to (...)

• Network
  6 October 2004, by L. C.

  A network is a set of elements that may be material, the infrastructure, and immaterial, electro-magnetic (waves) or informational, which ensure the establishment of relations between different places of a territory and between the entities that are occupying them.
  It comprises not only linear, permanent or temporary, elements which express the existence of relationships and ensure that they are possible, but also nodal elements needed in order to organise flows and to make the system in (...)

• Resilience
  6 October 2004, by C.A.-L.

  Resilience is a notion originally used in physics in order to designate resistance of a material to shock. In ecology, it takes a different meaning: in its traditional acceptation, it measures the time a system takes to return to balance after a perturbation. Since the years 1970, its definition has considerably changed. The one commonly admitted today is formulated by Holling (1973), who defines resilience as the ability of a system to integrate a perturbation in its working, without for (...)

• GEOGRAPHICAL CELLULAR AUTOMATON
  8 November 2013, by P. L.

  Cellular automata are as old as the computer. The concept was invented by Von Neumann and Ulam at the end of the 1940s while working at the Los Alamos National Laboratory on the first computers capable of performing the large calculations required in the construction and production of the atomic bomb. Cellular automatons were designed to resolve the problem of the auto-reproduction of living beings. Since then, this notion has been used in numerous fields, including Geography. In the 1950s (...)

• Equilibrium / Balance
  6 October 2004, by D. P.

  In physics, equilibrium is the state of a system subjected to opposite forces that balance each other, so that the variables describing the system stop evolving and any move is stopped. In geography, what may rather be observed are stationary states, when equality of incoming and outgoing flows of an open system implies that there is no variation of the system (interactions, internal exchanges however remain). So, a region which receives as many immigrants from other regions as it sends (...)

• Energy
  1 November 2005, by B. E., F.D.-D.

  The first scientific meaning for the word energy was elaborated within the discipline of Physics, and applies to the faculty that a body has to produce mechanical work. In geography, the notion of energy is used in three main fields: In its most commonly accepted meaning today, the notion of energy is likened to a resource used to meet human needs, and involves all the means that human societies have used to appropriate and transform natural elements. Energy is not limited to fossil (...)

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