(739b) Analysis, Design and Operation of Complex Agriculture Based Process Systems By Programmable Structures

Agriculture based process systems are inherently embedded in the vulnerable ecosystem, soil and water resources, as well as they are connected with non-agricultural technologies, producing food, energy and raw materials. Having recognized this highly increasing complexity, the international mainstream of process modeling engineers tries to implement the well established and new methodologies for agro-environmental systems. The challenge is to develop unified modeling and simulation methods, which help to evolve cooperation between natural ecosystems and human operated technologies.

Recently, computer assisted decisions about design and operation of complex agro-environmental systems are supported by new generations of sensors and data acquisition methodologies. However, the integrated development of agriculture related holistic process networks need also the consideration of the causally determined balances of the complex (multiscale and nonlinear) interactions. The decisions require also the involvement of the 'first principles' based, simplified predictive dynamic models, considering the conservation laws controlled relationships of the underlying processes.

The development of Programmable Structures has been motivated by the fact that modeling and dynamic simulation of agriculture-based complex processes require easily modifiable, extensible and connectible models, with unified representation of functional and structural features.

The locally programmable structure of the process models can be generated from two meta-prototypes and from the standardized description of the actual process network, automatically, resulting the dynamic structure of unified state and transition elements Functionalities (prototype elements) of the model can also be derived and edited from the general meta-prototypes. The actual prototype elements contain symbolic input, parameter and output variables, as well as local program codes. In various applications many state and transition elements can be modeled with the same or similar, re-usable local programs.

The state and transition elements of the actual model can be parameterized and initialized concerning their case-specific prototypes. The actual model elements are executed by the associated prototypes. The execution, as the connection-based communication amongst the state and transition elements of the programmed structure is solved by the general purpose kernel program of the method. During the simulation, the actual elements start with the initial conditions and parameters, and the output values are recalculated stepwise with the knowledge of input and parameter data, according to the associated local program prototype. The distinguished input and output connections for the extensive/intensive properties and for signals make the combined execution of the balance-based and signal-based functionalities possible.

The well-developed PSE methods usually embed simplified models in an optimizer of mathematical programming. On the contrary, Programmable Structures, similarly to the engineering way of thinking, support to utilize the available, necessarily simplified, but possibly detailed multi-scale, non-linear knowledge about the elementary processes. The generic elements of the structural and functional possibility space (design space) can be integrated into the automatically generated elements of the executable Programmable Structure, while it can communicate with various external tools via specific links. This makes possible to build plausible "evaluation feedback" between the simulator and the optionally multi-objective external reasoning (e.g. sub-optimization).

The application of the methodology will be illustrated by examples for some recently investigated complex agro-environmental process models (e.g. agro-forestry and fishpond aquaculture related process networks, producing food, energy and raw materials from renewable resources).