MagmaS

Coupling a hybrid dynamical system with a multi-agent system to model animal wastes management in Reunion island

Manuel Martin, Eric Piquet, Christophe Le Page, François Guerrin (Cirad)

 

MagmaS is a simulation framework aiming at helping animal wastes management at the farmer communities level and at minimising the environmental impact of animal production activities. It is made of two models

  • A hybrid dynamical system called Magma (Guerrin 2000a,b) standing for the internal dynamics of a set of individual farming systems (waste production and usel at the farm level)
  • The coupling is achieved by using the Windows DLL communication facility
  • An agent-based model called Mens representing the different ways the farmers (i.e. Magma instances) can transfer wastes from one to one another.

 

The use of Magma is justified by the acknowledged adequacy of hybrid dynamical system models to farming systems and the use of Mens by the adequacy of multi-agents systems to model interacting agents.

Mens works at the collective level, since it models information and organic matter (OM) exchanges among the farmers. Conversely, Magma works at the individual level since it models OM management at the farm level: production by possibly various animal production units, spreading on crops, possible transformation into other kinds of OM (e.g. compost) and potentially hazardous flows towards the environment as a result of stock overflowing or unlawful spreading.

Linking Magma (implemented with the Vensim software ) and Mens (implemented with the Cormas software ) within MagmaS was done using the Vensin interactive simulation facility (called "gaming") procedures: at each time step Magma simulates the farm internal stocks dynamics during one day resulting in OM surplus or OM deficit (to meet crop fertilisation requirements). Every seven time steps (e.g. every week), Mens is then used to simulate OM transactions, which depends on the supply/demand balance of OM of each farmer previously simulated with Magma. When transactions are closed, simulation enters next time step, and the results of transactions simulated by Mens (import or export of MO) are used as inputs by Magma.

For more information, contact the author.

References

Guerrin, F. (2000a). Simulation of actions to help animal wastes management atthe farm level. In: MCPL'2000, IFAC / IFIP / IEEE 2nd Conf. on Management and Control of Production and Logistics. Grenoble (F), 5-8 July 2000, CD Rom : Session R6, P135.

Guerrin,F. (2000b). Magma : a model to help animal manure management at the farm level. In: Agricontrol'2000, Int. Conf. On Modelling and Control in Agriculture, Horticulture and Post-Harvest Processing. Wageningen (NL), 10-12 July 2000, p.159-164.

Piquet, E. et Le Page C. (2001). Couplage des logiciels VisualWorks etVensim sous Windows : DDE ou DLL ? Rapport Cirad TERA n° 18/01, June 2001, 14 pages.


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