The development of generic modelling software for citrus packing processes

[摘要] ENGLISH ABSTRACT: This study was initiated in October 2004 when Vizier Systems (Pty) Ltd approached the Department ofIndustrial Engineering at the University of Stellenbosch with a concept. They proposed that a fruitpacking line be represented as a series of unit operations and suggested that the concept could be usedto create a generic model that can be used to represent any packing line. After further discussions withVizier about the concept and their reasons for requiring a generic model, a formal client requirement wasformulated. It was decided that the generic modelling concept had to be tested in the citrus industry.Modelling theory was investigated and a generic modelling methodology was formulated by adapting anexisting modelling methodology. The first few steps of the developed methodology led to industry databeing gathered and several role-players in the citrus export industry being visited. An analysis of thedata enabled the development of the necessary techniques to do distribution estimation and forecastingof the system input, which is fruit. The various processes were grouped into generic groups and detailedcapacity calculations were developed for each process.The fruit parameter estimation techniques and capacity calculations were integrated into a five stepmodelling procedure. Once the generic model was set up to represent a specific packing line, themodelling procedure provided optimum flow rates, equipment setups and personnel allocations fordefined production runs. The modelling procedure was then translated into a computer model. Thisallowed a complete capacity analysis of a packing line by incrementally varying the characteristics of thefruit input.The developed generic model was validated by comparing its predictions to the results of two productionruns at an existing packing line. It was found that the generic model is able to adequately represent thepacking line and that the fruit inputs and outputs can be accurately estimated. The concept proposed byVizier, that a packing line can be generically modelled as a series of unit operations, was shown to bevalid.

[发布机构] Stellenbosch University