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Presentation of my projects in modeling domain
Presentation of my projects in modeling domain
- Aggregates exploitation and transport flow (France)
- Artisanal Gold Mining (Burkina Faso)
**    Paper Award
- Ultra-pure Quartz exploitation (Madagascar)
- Collective management of animal wastes (La Réunion)

Collective management of animal wastes (La Réunion)

(Photos: © CIRAD/IREMIA)

1- Introduction

biomas breedingDue to environmental risks and governmental regulations that weigh heavily on the livestock industry, the management of wastes has become an urgent necessity, particularly in the Reunion Island.

biomas cropThe organization of transfers of these organic materials (OM) between surplus-producing farms (i.e. farms where livestock raising activity dominates) and deficit farms (i.e. predominately crop production) is foreseen. With this in view, our work aims at modeling management on a territorial scale in order to simulate the possible transfers of OM between farms, and thus, to test the alternatives of organization open to the agricultural industry.

2- Mas modeling

The resulting MAS, called Biomas was developed as an application of the development platform Geamas. In Biomas, a territory is viewed in regard to waste management. The territory is composed of several farms possessing livestock farming activities, crops, types of transportation and storage units. Possibly, to this are added collective waste treatment facilities (WTF) that function by means of several processes.

These units are positioned in space. Livestock farms create a supply of OM and crop farms create a demand that must be met and that is conditional upon satisfying quality, quantity and availability conditions. The process enabling the matching of the characteristics of supply and demand that leads to a transfer is called a negotiation. Any negotiation can be initiated either by supplier or client-user. The transportation from the place of storage (livestock farming buildings) to the place of use (plots) can be effected if and only if a shipper can be found whose characteristics are compatible with the terms of the contract concluded between supplier and client-user (capability of transporting the OM, availability). The shipment is thus the result of a negotiation between supplier of the OM and shippers.

Since such a system may be conceptually described in terms of (possibly numerous) interacting entities endowed with a certain autonomy, The multi-agent paradigm came naturally to the fore as the most indicated modeling approach.

Our aim is thus to simulate the circulation of OM amongst some set of farms in order to perform "What-If" analyses such as:
- What would occur if some waste treatment facility is shared by a subset of farms?
- What if such livestock farmers are assigned some set of management rules?

biomas geamas correspondance

The principal objective is to provide agronomists with help to explore the effect of various modes of interaction within such a system. In conformity with the Geamas agent model, Biomas differentiates between three categories of agents:
- the executants and the physical entities pertaining to the Micro level;
- the groups of executants pertaining to the Medium level;
- The Biomas system as a whole as Macro-agent

3- Simulations Results

The general objective that we attain with Biomas is twofold:
- analysis of the impact of scenarios elaborated on the basis of real life situations;
- testing of alternative scenarios in order to eliminate weaknesses (for example, risks of environmental pollution as depicted by the state of the IDZ agent, insufficient agricultural exploitation of OM as depicted by the degrees of crop satisfaction)

The next figure presents data describing an illegal dumping zone (IDZ) obtained by simulation - Duration 10 months: (A) without WTF; (B) with WTF 

biomas simulation result

This scenario includes a total of 195 agents: the 186 agents of the base scenario, augmented by one Group agent, 1 WTF Executive agent, 1 WTF agent, 1 Shipper of treated wastes, and 5 Storage Units (1 per OMP group member). The two scenarios differ only in regard to the existence of a WTF and its associated agents. We note that a sole OMP role agent can possess 1, 2, or 3 livestock installations and that only 5 of these agents are affiliated with the WTF. This is initialized at 60 m3 ,the maximal value of the entry reservoir.

Experimentation and interpretation

The figure above indicates the state of the illegal dumping zone (in m3 of dumped OM) at the end of the simulated base scenario (without WTF). For each type of OM, the inspector that gives the properties of the illegal dumping zone (IDZ) yields the volumes transferred between installations and the volumes dumped illegally. We observe an abundant dumping of manure and slurry into the environment, and very little OM exchange (respectively, less than 10% or 25% of their totals). The absence of OM client-users that these results manifest may be due to different reasons:
- a too limited OMP acquaintanceship network for OM marketing;
- too much incompatibility between the OM produced by the OMPs and the crops of the OMCs (for example, slurry is not used for truck farming);
- unavailable or non-adapted shipping (type, capacity).

Discussion and outlook

The design of the Biomas application raised problems relative to the creation of a reliable methodology for the conception of Agent applications. Work aimed at defining a reproducible method of obtaining reliable results is presently being conducted by many Agent environment development research scientists. Different facets are being approached: How should one model and construct a MAS? How should one manipulate the models while defining well-adapted languages and graphics? What are the rules of conception that should be used?

If Biomas has permitted us to enrich certain aspects of Geamas (role, time management), the fundamental modeling elements were nevertheless already well established (architecture, communication, environment, etc.). For notations (diagrams of inter-agent cooperation, sequences, etc.) we have relied in great part upon the achievements of object approaches (Object Management Group UML Resource Page http://www.omg.org/uml) in defining graphic specialization for agents. On the other hand the "know-how" of model conception has not been clearly formulated which makes it difficult to reproduce.

In the Biomas experience, we were also confronted with a recurring problem: How far must one take the individual level in order to enable a MAS representative of a collective level to function? The risk of error was amplified in Biomas, because even if we have agronomic knowledge on an individual level (agricultural activities), we have very little on a collective level (the set of activities and their interchanges). In parallel, we have developed a dynamic system, Magma that enables us to represent the internal processes of farms. Therefore, Magma is representative of the individual level, modeled in Biomas by a single Executant agent and subordinate agents. This leads us to envision the coupling of the different Magma instances through a multi-agent platform, in order to represent the collective level. Presently, we are putting this into effect using the Cormas multi-agent platform in an application that enables us, through a blackboard structure, to join the two levels, individual and collective.

(Photos: © CIRAD/IREMIA)