The development of generic modelling software for citrus packing processes

Kritzinger, Chris (Cornelis Christiaan) (2007-03)

Thesis (MSc)--University of Stellenbosch, 2007.

Thesis

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

AFRIKAANSE OPSOMMING: Hierdie studie is in Oktober 2004 geïnisieer toe Vizier Systems (Pty) Ltd die Departement van Bedryfsingenieurswese aan die Universiteit van Stellenbosch met ’n konsep genader het. Hulle het aan die hand gedoen dat ’n vrugtepaklyn voorgestel kan word as ’n reeks eenheidsprosesse en dat die konsep gebruik kan word om ’n generiese model te skep om enige vrugtepaklyn te verteenwoordig. Na verdere samesprekings met Vizier oor die konsep en hul redes vir die noodsaaklikheid van ’n generiese model, is ’n formele kliëntebehoefte geformuleer. Daar is besluit dat die generiese modelleringskonsep in die sitrusbedryf getoets gaan word. Modelleringsteorie is ondersoek en ’n generiese modelleringsmetodologie is geformuleer deur ’n bestaande modelleringsmetodologie aan te pas. Die stappe van die ontwikkelde metodologie het gelei tot die insameling van data vanuit die industrie en verskeie rolspelers in die sitrus-uitvoerindustrie is besoek. ’n Analise van die data het die ontwikkeling van die tegnieke moontlik gemaak wat nodig was om verspreidingsberamings en voorspelling van die stelselinset – die vrugte – te doen. Die onderskeie prosesse is gegroepeer in generiese groepe en gedetailleerde kapasiteitsberekeninge is vir elke proses ontwikkel. Die vrugparameter beramingstegnieke en kapasiteitsberekeninge is geïntegreer in ’n vyf-stapmodelleringsprosedure. Nadat die generiese model opgestel is om ’n spesifieke paklyn voor te stel, het die modelleringsprosedure optimum vloeitempo’s, toerustingopstellings en personeeltoedelings vir die spesifieke produksielopie gegee. Die modelleringsprosedure is toe herlei tot ’n rekenaarmodel. Dit het ’n volledige kapasiteitsanalise van die paklyn moontlik gemaak, deur die eienskappe van die vruginset inkrementeel te varieer. Die ontwikkelde generiese model is gestaaf deur sy voorspellings te vergelyk met die resultate van twee produksielopies van ’n bestaande paklyn. Daar is bevind dat die generiese model in staat is om die paklyn voldoende voor te stel en dat dit die vruginsette en -uitsette akkuraat kon beraam. Die geldigheid van die konsep wat voorgestel is deur Vizier, naamlik dat ’n paklyn generies gemodelleer kan word as ’n reeks eenheidsprosesse, is bevestig.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/21669
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