Taulo_John_Revised Dissertation for Examination 2016.11.22.pdf - A multi-objective optimization tool for the Malawian tea industry with sustainability

Taulo_John_Revised Dissertation for Examination 2016.11.22.pdf

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Unformatted text preview: A multi-objective optimization tool for the Malawian tea industry with sustainability considerations by John Loti Taulo Dissertation presented for the degree of Doctor of Philosophy in the Faculty of Engineering at Stellenbosch University Supervisor: Prof. Albert Groenwold Co-supervisor: Prof. Adoniya Ben Sebitosi March 2017 Departement Meganiese en Megatroniese Ingenieurswese Department of Mechanical and Mechatronic Engineering Declaration By submitting this thesis electronically, I declare that the entirety of the work contained therein is my own, original work, that I am the sole author thereof (save to the extent explicitly otherwise stated), that reproduction and publication thereof by Stellenbosch University will not infringe any third party rights and that I have not previously in its entirety or in part submitted it for obtaining any qualification. 22nd November 2016 Copyright © 2017 Stellenbosch University All rights reserved i Abstract Corporate social responsibility (CSR) is fast becoming imperative for corporate governance in industry and business worldwide and is assuming an increasing role in the general discourse on globalization and sustainable development. The World Business Council for Sustainable Development has defined CSR “as the continuing commitment by business to behave ethically and contribute to economic development while improving the quality of life of the workforce and their families as well as of the local community and society”. Different countries and organizations agree on the fundamental principles and spirit embedded in this definition. The major challenge, however, is that there are currently no standardised modalities by which it should be achieved nor a yardstick by which compliance can be graded. Differing perceptions of CSR have resulted in many disparate codes where they exist. In Africa, this problem is further exacerbated by a lack of awareness. In addition, there is an absence of a comprehensive management framework that would address, balance and integrate triple bottom line considerations. This dissertation primarily aims to address this gap. A tool to support this objective has been proposed, designed and tested in the field. The Malawian tea industry has been identified as a case study. A multitude of challenges in this industry include child labour and deforestation on one hand as well as dwindling product quality and profit margins. These objectives have conflicting demands. The primary objective of this dissertation is to develop a multi-objective optimization tool to support decision-making processes in the Malawian tea industry. This work presents a novel decision support tool, called MOISAT (multi-objective optimization and integrated sustainability assessment tool), for optimally operating production processes while minimizing cost impacts and maximizing the long-term sustainability. MOISAT is based on a combination of life cycle analysis (LCA), multi-criteria analysis (MCA), particularly, the analytic hierarchy process (AHP), and nondominated sorting genetic algorithm (NSGA-II). LCA–based framework methodology is used to quantify the environmental, social and economic sustainability performance of tea production. AHP is applied to evaluate and rank different alternatives based on the judgment of decision makers. NSGA-II, an increasingly popular multi-objective optimization technique is employed to obtain a set of Pareto- optimal solutions. The developed tool is empirically tested on a case study of three tea companies in Malawi. Moreover, the applicability of the developed tool has been validated using usability testing, conducted through questionnaire survey and in-depth semistructured interviews with eight decision makers as well as face–to–face discussion ii with experts. The results have demonstrated the usefulness of the tool in pinpointing environmental and social sustainability hot spots within the tea production life cycle stages that needs further improvement. Furthermore, the results from this study have shown that the proposed algorithm is effective and has great potential for solving multi-objective optimization problem in the tea industry. Finally, the findings of this study will help decision makers in the tea industry to incorporate sustainability considerations into tea products, processes and activities. iii Opsomming Korporatiewe sosiale verantwoordelikheid (KSV) is vinnig besig om noodsaaklik vir korporatiewe bestuur in die industriële- en besigheidswêreld te word en neem ʼn toenemende rol in die algemene diskoers oor globalisering en volhoubare ontwikkeling in. Die Wêreld Besigheidsraad vir Volhoubare Ontwikkeling het KSV gedefinieer as die voortgesette verbintenis deur ʼn besigheid om eties op te tree en by te dra tot ekonomiese ontwikkeling, terwyl die lewensgehalte van die arbeidsmag, hul gesinne, die plaaslike gemeenskap asook die samelewing in die algemeen verbeter word. Verskillende lande en organisasies stem saam oor die grondbeginsels en goeie gees wat in hierdie definisie omsluit word. Die groot uitdaging is egter dat daar tans geen gestandaardiseerde modaliteite waardeur dit bereik kan word asook geen maatstaf waarteen nakoming kan gegradeer word bestaan nie. Verskillende persepsies van KSV het tot gevolg gehad dat baie uiteenlopende kodes bestaan. In Afrika, is hierdie probleem verder vererger deur 'n gebrek aan bewustheid. Daarbenewens is daar is 'n gebrek aan 'n omvattende bestuursraamwerk wat drievoudige oorwegings aanspreek, balanseer en integreer. Dit verhandeling is hoofsaaklik daarop gemik om hierdie gaping aan te spreek. 'n Instrument om hierdie doelwit te ondersteun is voorgestel, ontwerp en getoets in die praktyk. Die Malawiese tee bedryf is as gevallestudie geïdentifiseer. Menigte uitdagings in die bedryf sluit kinderarbeid en ontbossing aan die een kant in en kwynende kwaliteit van die produk en winsmarges aan die ander kant. Hierdie doelwitte het botsende eise. Die primêre doel van hierdie verhandeling is om ʼn veeldoelige optimalisering instrument om besluitnemingsprosesse te ondersteun in die Malawiese tee bedryf te ontwikkel. Hierdie werk bied 'n nuwe besluit ondersteuningsgereedskap, genaamd MOISAT (Multi-objective Optimization and Integrated Sustainability Assessment Tool), vir optimale werksproduksie prosesse terwyl die minimering van koste impak en die maksimering van die langtermynvolhoubaarheid plaasvind. Die instrument is gebaseer op 'n kombinasie van lewensiklus ontleding (LSO), multi-kriteria analise (MKA), veral die analitiese hiërargiese proses (AHP), en veeldoelige optimeringsmetodes. LSO gebaseerde raamwerk metodes word gebruik om die omgewings-, maatskaplike en ekonomiese volhoubaarheidsprestasie van tee produksie te kwantifiseer. AHP word toegepas om te evalueer en lys volgens rang verskillende alternatiewe gebaseer op die oordeel van besluitnemers. Nie-gedomineerde sorterings genetiese algoritme (NSGA-II), is 'n toenemende gewilde veeldoelige optimiseringstegniek en word gebruik om 'n stel van Pareto optimale oplossings te kry. Die ontwikkelde instrument is empiries getoets op 'n gevallestudie van drie tee maatskappye in Malawi. Daarbenewens is die toepaslikheid van die ontwikkelde instrument goedgekeur met behulp van ʼn gebruikers toets wat deur middel van vraelyste en in-diepte semi-gestruktureerde onderhoude met agt besluitnemers, asook iv aangesig tot aangesig gesprekke met kundiges. Die resultate het die nut van die instrument gedemonstreer deur die vasstelling van omgewings- en sosiale volhoubaarheid brandpunte binne die tee produksie lewensiklus stadiums wat verdere verbetering nodig het. Verder het die resultate van hierdie studie getoon dat die voorgestelde algoritme effektief is en 'n groot potensiaal het vir die oplossing van 'n veeldoelige optimeringsprobleem in die tee-industrie. Die bevindinge van hierdie studie sal besluitnemers in die tee-industrie help om volhoubaarheidsoorwegings te neem in tee produkte, prosesse en aktiwiteite. v Acknowledgements I would like to thank a number of individuals, companies and organizations that so generously contributed to the work presented in this dissertation. First and foremost, I wish to express my profound gratitude to my PhD advisors, Prof. A.B. Sebitosi and Prof. A.A. Groenwold for being a source of continuous support and influence; for their patience, advice and guidance. Particularly, their ideas, stimulating comments, and suggestions increased my cognitive awareness and helped me considerably. Their dedication, enduring encouragement and enthusiasm for my research were truly remarkable. The tremendous amount of time they spent and their valuable insights are greatly appreciated. I owe a great debt of gratitude to both supervisors for their help and able guidance throughout the duration of this study and the preparation of this dissertation. Moreover, their forensic scrutiny of my technical writing has been invaluable. It is no overstatement to say that without their support, consistent guidance, tutelage, insightful comments and unparalleled knowledge, this dissertation would never have existed. I am very grateful for all the tea companies and organizations for the collaboration in providing first-hand information and data used in this study: Eastern Produce Malawi (EPM), Lujeri Tea Estates, Makandi Tea & Coffee Estate (MTCE), Namingómba Tea Estate (NTE), Smallholder Tea Authority (STECO), Conforzi Plantations, Tea Research Foundation Central Africa (TRFCA), and Tea Association of Malawi (TAML). Special mention goes to Rick Tilley and Jim Merlose, Managing Directors for EPM and Lujeri, respectively, for allowing me to access and collect data from all their factories. Most important, I express my deepest appreciation to group managers, production managers, and factory engineers in these companies for sparing their valuable time to complete the questionnaires. I am particularly indebted to Clement Thindwa- Chief Executive Officer (TAML), and Dr Albert Changaya-Director General (TRFCA) for our insightful and detailed discussions about the tea industry. I would also like to extend my gratitude to the Department of Mechanical and Mechatronic Engineering for giving me the opportunity to carry out my doctoral research and for the financial support. It would not have been possible for me even to start my study had they not given me a partial bursary in my first three years. I gratefully acknowledge the financial support from the Malawi Government, through the Malawi Government Scholarship Fund (MGSF), without which I could not have completed the last two years of my study. I am indebted to all my friends Brian Ssebabi, Johnnah Mundike, Craig Omotoyosi, Moses Malinda, Tsepo Morokeng, Darlington Masendeke and many others for the stimulating discussions, for the sleepless nights we were working together, for their valuable help and support, for providing friendship that I needed, and with whom I vi have shared moments of deep anxiety but also of big excitement. I also recognize the support and help from Richard Banda and Nervous Kaunda for contributing significantly towards implementation of a database management system for the developed tool. They helped me greatly and have been a source of knowledge with real world programming skills, specifically in Visual Studio. To my mum and dad, beloved children Ian, Tithokoze and Tadala thank you for your love, undeniable support, and unwavering belief in me. Without your motivation, I would not be the person I am today. I owe everything to you and I dedicate this dissertation to you. Finally, I would like to acknowledge my dear wife, Chisomo. She has been a constant source of strength and inspiration. There were times during the past four years when everything seemed hopeless and the future looked bleak. I can honestly say that it was only her determination and constant encouragement that ultimately made it possible for me to see this research through to the end. Above all, I express my indebtedness to the Almighty God for all his blessings and kindness. vii Dedication To Chisomo, Ian, Tadala, and Tithokoze To my parents Loti Taulo and Elida Mphepo viii Table of Contents Declaration ............................................................................................................i Abstract ............................................................................................................... ii Opsomming.........................................................................................................iv Acknowledgements .............................................................................................vi Dedication ........................................................................................................ viii Table of Contents ................................................................................................ix List of Figures .................................................................................................... xv List of Tables ....................................................................................................xvi List of Publications ......................................................................................... xvii Nomenclature ................................................................................................. xviii Chapter-1 Background and Motivation ................................................................... 1 1.1 Introduction .................................................................................................... 1 1.2 Background to the study ................................................................................ 1 1.3 Research problem .......................................................................................... 3 1.4 Motivation for study ...................................................................................... 3 1.5 Purpose of the study....................................................................................... 5 1.6 Research questions ......................................................................................... 5 1.7 Scope of the study .......................................................................................... 6 1.8 Research methodology ................................................................................... 6 1.9 Significance of the research ........................................................................... 7 1.10 Contributions ............................................................................................... 8 1.11 Limitations of the study ............................................................................... 9 1.12 Structure of the thesis .................................................................................. 9 1.13 Chapter summary ....................................................................................... 11 Chapter-2 Background of the Malawian tea industry ............................................ 13 2.1 Introduction .................................................................................................. 13 2.2 The global tea industry ................................................................................ 13 2.3 Tea in perspective ........................................................................................ 14 2.3.1 The science of tea ................................................................................. 15 2.3.2 Origin and history ................................................................................. 16 2.3.3 Health benefits of tea ............................................................................ 17 2.4 Malawian tea industry overview .................................................................. 19 2.4.1 Overview ............................................................................................... 19 ix 2.4.2 A brief history of the Malawian tea industry ........................................ 19 2.4.3 Tea’s growing importance in Malawi’s economy ................................ 21 2.4.4 Structure of the Malawian tea industry ................................................. 21 2.5 Challenges and opportunities ....................................................................... 23 2.6 Environmental and social impacts ............................................................... 26 2.6.1. Environmental impacts ........................................................................ 26 2.6.2. Social impacts ...................................................................................... 29 2.7 Chapter summary ......................................................................................... 31 Chapter-3 Theoretical Framework and Literature Review .................................... 34 3.1 Introduction .................................................................................................. 34 3.2 Sustainable tea production: a new manufacturing paradigm ....................... 34 3.3 The concept of sustainability ....................................................................... 35 3.4 Drivers and benefits towards sustainable production .................................. 35 3.5 Sustainability measurement tools ................................................................ 37 3.5.1 Life Cycle Assessment (LCA) .............................................................. 37 3.5.2 Analytical Hierarchy Process................................................................ 39 3.6 Sustainability indicators and metrics ........................................................... 42 3.7 Manufacturing Productivity ......................................................................... 44 3.8 The concept of productivity ......................................................................... 45 3.9 Measuring productivity ................................................................................ 48 3.10 Productivity measurement models ............................................................. 49 3.11 Productivity and environmental sustainability .......................................... 49 3.12 Productivity and social sustainability ........................................................ 50 3.13 Chapter summary ....................................................................................... 51 Chapter-4 Multi-objective optimization ................................................................ 52 4.1 Introduction .................................................................................................. 52 4.2 Multi-objective optimization problems in tea industry................................ 52 4.3 An introduction to multi-objective optimization ......................................... 53 4.4 Basic multi-objective optimization concepts ............................................... 54 4.4.1 Definitions ............................................................................................ 54 4.4.2 Multi-objective optimization problem formulation .............................. 54 4.4.3 Pareto optimality ................................................................................... 55 4.4.4 Classification of methods in multi-objective optimization ................... 58 4.5 Classical optimization methods ................................................................... 59 x 4.5.1 Weighted Sum Method ......................................................................... 59 4.5.2 Goal programming ................................................................................ 60 4.5.3 -constraint method .............................................................................. 61 4.6 Genetic algorithms ....................................................................................... 62 4.6.1 Basic concepts of genetic algorithms...............................................
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