Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: This study strives to improve two current industrial processes by making them more cost effective through the use of hydrolytic enzymes or microbial systems. The first process targeted is the industrial conversion of starch to ethanol. In the second process, hydrolytic enzymes are applied to the manufacturing of instant coffee. The engineering of microbial systems to convert starch to bio-ethanol in a one-step process may result in large cost reductions in current industrial processes. These reductions will be due to decreased heating energy requirements, as well as a decrease in money spent on the purchase of commercial enzymes for liquefaction and saccharification. In this study, a recombinant Saccharomyces cerevisiae strain was engineered to express the wild-type Aspergillus awamori glucoamylase (GA I) and α-amylase (AMYL III) as well as the Aspergillus oryzae glucoamylase (GLAA) as separately secreted polypeptides. The recombinant strain that secreted functional GA I and AMYL III was able to utilise raw corn starch as carbon source, and converted raw corn starch into bio-ethanol at a specific production rate of 0.037 grams per gram dry weight cells per hour. The ethanol yield of 0.40 gram ethanol per gram available sugar from starch translated to 71% of the theoretical maximum from starch as substrate. A promising raw starch converter was therefore generated. In the second part of this study, soluble solid yields were increased by hydrolysing spent coffee ground, which is the waste generated by the existing coffee process, with hydrolytic enzymes. Recombinant enzymes secreted from engineered Aspergillus strains (β-mannanase, β-endoglucanase 1, β-endo-glucanase 2, and β-xylanase 2), enzymes secreted from wild-type organisms (β-mannanases) and commercial enzyme cocktails displaying the necessary activities (β-mannanase, cellulase, and pectinase) were applied to coffee spent ground to hydrolyse the residual 42% mannan and 51% cellulose in the substrate. Hydrolysis experiments indicated that an enzyme cocktail containing mainly β-mannanase increased soluble solids extracted substantially, and a soluble solid yield of 23% was determined using the optimised enzyme extraction process. Soluble solid yield increases during the manufacturing of instant coffee will result in; (i) an increase in overall yield of instant coffee product, (ii) a decrease in amount of coffee beans important for the production of the product, and (iii) a reduction in the amount of waste product generated by the process. / AFRIKAANSE OPSOMMING: Hierdie studie poog om twee huidige industriële prosesse te verbeter deur die prosesse meer kosteeffektief met behulp van hidroltiese ensieme en mikrobiese sisteme te maak. Die eerste industrie wat geteiken word, is die omskakeling van rou stysel na etanol, en die tweede om hidrolities ensieme in die vervaardiging van kitskoffie te gebruik. Die skep van mikrobiese sisteme om rou-stysel in ’n ’een-stap’ proses om te skakel na bio-etanol sal groot koste besparing tot gevolg hê. Hierdie besparings sal te wyte wees aan die afname in verhittingsenergie wat tydens die omskakelingsproses benodig word, asook ’n afname in die koste verbonde aan die aankoop van duur kommersiële ensieme om die stysel na fermenteerbare suikers af te breek. In hierdie studie is ’n rekombinante Saccharomyces cerevisiae-gis gegenereer wat die glukoamilase (GA I) and α-amilase (AMYL III) van Aspergillus awamori, asook die glukoamilase van Aspergillus oryzae (GLAA) as aparte polipeptide uit te druk. Die rekombinante gis wat die funksionele GA I en AMYL III uitgeskei het, was in staat om op die rou-stysel as koolstofbron te groei, en het roustysel na bio-etanol teen ’n spesifieke tempo van 0.037 gram per gram droë gewig biomassa per uur omgeskakel. Die etanolopbrengs van 0.40 gram per gram beskikbare suiker vanaf stysel was gelykstaande aan 71% van die teoretiese maksimum vanaf stysel as substraat. ’n Belowende gis wat roustysel kan omskakel na bio-etnaol was dus geskep. In die tweede deel van hierdie studie is die opbrengs in oplosbare vastestowwe vermeerder deur die koffie-afval wat tydens die huidige industrieële proses genereer word, met hidrolitiese ensieme te behandel. Rekombinante ensieme afkomstig vanaf Aspergillus-rasse (β-mannanase, β-endoglukanase 1, β-endo-glukanase 2 en β-xilanase 2), ensieme deur wilde-tipe organismes uitgeskei (β-mannanase), asook kommersiële ensiempreparate wat die nodige ensiemaktiwiteite getoon het (β-mannanase, sellulase en pektinase) is gebruik om die oorblywende 42% mannaan en 51% sellulose in koffie-afval te hidroliseer. Hidrolise eksperimente het getoon dat ’n ensiempreparaat wat hoofsaaklik mannanase bevat, die oplosbare vastestofopbrengs grootliks kan verbeter, met ’n verhoogde opbrengs van 23% tydens geöptimiseerde ensiembehandelings. ’n Verhoogde opbrengs in oplosbare vastestowwe tydens die vervaardiging van kitskoffie sal die volgende tot gevolg hê: (i) ’n toename in totale opbrengs van kitskoffie produk, (ii) ’n afname in die hoeveelheid koffiebone wat vir die produksie ingevoer moet word, en (iii) ’n afname in die hoeveelheid afval wat tydens die vervaardigingsproses produseer word.

published_or_final_version / abstract / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

This research examined the relationship between manufacturing input parameters and factory performance in a cellular manufacturing environment.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / This research report addresses the question: Is BRM (Benefits Realisation Management) a valid method for MES (Manufacturing Execution Systems) development and implementation? While the technical aspect of implementing MES is standardised and well documented, a clear approach to tackling the activity on a company specific level is missing. Literature shows that there is ambiguity in where ownership should lie and further details common organisational problems that companies experience. Limited guidance is given to how these problems can be tackled. An evaluative case study is conducted at the WMMEA (WEIR Minerals Middle East and Africa) machine shop to determine whether BRM methodology is able to improve the MES system and its implementation by adding a previously unexplored structure to the undertaking. The research method focuses on two aspects of the case. The initiative, where the researcher aims to identify whether BRM methodology is able to specify a complete set of requirements for MES implementation. The outcomes, where the researcher quantifies the benefits gained from the implementation. This report describes an adapted BRM methodology and the outcomes of its application. These outcomes consist of the issues faced by the company, the enablers developed to overcome these issues, and the benefits derived from MES. The BRM methodology is shown to be valid in the case of WMMEA by the confirmed realisation of predicted benefits. The business objectives achieved are an improved on-time delivery to customers and an increased part value. / MT2017

A project report submitted to the Faculty of Engineering. University of the Witwatersrand, Johannesburg, in Partial fulfilment of the requirements for the. degree of Master of Science in Engineering, Johannesburg. 1991 / In order to analyse and optimize the design and Operation of Advanced Manufacturing Systems (AMS) various simulation techniques are currently in use. However, these methods are' generally inflexible and are used off-line in this project report, a modular, modelling approach is adopted to investigate the requirements of shop floor device models which operate in real-time. The models when connected together, simulate the Operation of the AMS. A suitable technique for the development of these models is proposed. A simulation architecture to support the models is discussed. It is intended that the models are connected on-line to the AMS control system via a local Area Network (LAN). [Advantages and - applications of this approach to AMS simulation are discussed. / MT2017

A abertura de mercado no Brasil, na década de 1990, aumentou a concorrência na indústria automobilística local e a busca por novos produtos, tecnologias e principalmente por processos de manufatura mais enxutos e viáveis economicamente. Dentro deste contexto, a pressão pela redução do tempo de desenvolvimento de novos produtos, fez com que fosse necessário reduzir também o tempo de desenvolvimento dos novos processos de manufatura. O desenvolvimento e planejamento de uma manufatura são processos complexos, pois envolvem diferentes áreas da empresa, demanda altos investimentos e envolve diferentes tecnologias. A Engenharia de Manufatura é a área da empresa responsável pelo planejamento, projeto e implantação de novas manufaturas para novos produtos. O objetivo central deste trabalho é a conceituação e aplicação da Simulação de Processos aplicada nas fases de planejamento e projeto para linhas de produção manuais e automatizadas através da utilização de ferramentas computacionais. O foco será na área de armação de carroceria onde se encontram o maior grau de automação e complexidade. As vantagens obtidas com sua utilização, nas fases de planejamento e projeto, são a redução de investimentos, redução no tempo de introdução de um novo processo, observação prematura de gargalos de produção, definição da quantidade necessária de estoques intermediários, os quais influenciam diretamente os tempos de processo e custos variáveis. Os conceitos apresentados são validados a partir de estudos de casos na Volkswagen do Brasil envolvendo veículos em lançamento como o novo Gol e Voyage e veículos em série como o Polo. / The market opening to newcomers in Brazil during the 1990s has increased the local automotive industry competition and the search for new products, technologies and mainly for leaner and financially feasible processes. Within that context, the need to reduce new product development timing has made it necessary to minimize the development period for manufacturing processes. Planning and developing manufacturing operations are complex processes, once they involve different areas in a company and they demand high investment and peculiar technologies. The Manufacturing Engineering is the area in the company that takes over the responsibility for planning, designing and implementing new manufacturing processes for new products. The main objective of that work is define concepts and apply the process simulation on the planning and designing steps of manual and automatic production lines by using computer tools. The target will be the body shop area where the automation and complexity degrees are higher. The advantages of using such tools during the planning and designing phases are not only the reduction of investment and process introduction timing but also the early identification of production bottlenecks, as well as the definition of line buffers that directly affect the process cycles and variable costs. The presented concepts are validated through cases of Volkswagen of Brazil and involving the launching of vehicles such as the new Gol and Voyage and series models like the Polo.

Corpos de prova de ferro fundido foram usinados com altíssima velocidade de corte. Tiveram diversos parâmetros de sua rugosidade medida e os valores foram descritos em gráficos de rugosidade versus profundidade de corte. Pode-se verificar uma dependência entre estes valores, mas não o clássico aumento da rugosidade conforme o aumento da profundidade de corte. Realizou-se ainda a inspeção metalográfica dos corpos de prova na busca de mudanças de fase na estrutura ferro carbono que indiquem temperaturas elevadas no local, causadas pela alta velocidade de corte. / Cast iron test parts were high-speed machined. They had several roughness parameters measured and these values were plotted on roughness versus depth of cut charts. It could be noticed a relation between these values, but not the classical roughness increase due to the increase of depth of cut. Moreover, the metalographical analisys was performed for these test parts, in a search for phase changes on the carbon-iron structure which indicate high temperatures at the region, caused by the high cutting speed.

Neste trabalho, é apresentada uma metodologia de fabricação de transistores de filmes finos orgânicos. Foram fabricadas células solares de heterojunção de poli(3- hexiltiofeno) (P3HT) e [6,6]-fenil-C61-butirato de metila (PCBM) por apresentarem máxima conversão de potência (PCE) de cerca 5 %. Partindo de rendimentos de 10-6 até atingir 1,7 %, são mostradas as dificuldades no processamento de filmes orgânicos e na caracterização destes dispositivos. Destacam-se dentre outros, a importância da geometria dos eletrodos, da preparação da solução de blendas orgânicas e dos cuidados na utilização de substratos flexíveis (e.g. polietileno tereftalato PET). A estrutura empregada é composta por vidro, óxido de índio dopado com estanho (ITO), poli(3,4- etilenodioxitiofeno) complexado com poli(ácido estireno-sulfônico) (PEDOT:PSS), P3HT:PCBM, fluoreto de lítio (LiF) e alumínio. PET coberto por In2O3/Au/Ag em substituição ao vidro-ITO é utilizado devido à busca da indústria eletrônica por materiais alternativos de baixo custo. Estrutura semelhante é empregada para caracterização da mobilidade dos portadores de carga em filmes orgânicos. Técnicas tais como Time of Flight (ToF), Charge Extraction in Linearly Increasing Voltage (CELIV), além da interpretação de curvas estacionárias de densidade de corrente por tensão (JxV) foram empregadas para estudo de derivados de poli(para-fenileno vinileno) (PPV). Foram obtidas mobilidades de 10-810-6 cm2/Vs para modelos de corrente limitada por carga espacial (SCLC) com armadilhas rasas e profundas. Mobilidades de efeito de campo caracterizadas em TFTs bottom gate bottom contact com porta comum são pelo menos duas ordens de grandeza superiores às obtidas através das técnicas anteriormente citadas. Foram utilizados diversos substratos (e.g. silício monocristalino e vidro-ITO), dielétricos (e.g. oxinitreto de silício (SiOxNy) por PECVD e SiO2 térmico), tratamentos de superfície (e.g. vapor de hexametildissilazana HMDS), semicondutores (derivados de PPV, P3HT, pentaceno) e eletrodos (e.g. camada de aderência de titânio). Definiu-se assim uma metodologia de seleção de novos semicondutores orgânicos para a indústria eletrônica. / In this work, it is presented a methodology for organic thin-film transistor (OTFT) fabrication. Poly(3-hexylthyophene) (P3HT):[6,6]-phenyl-C61-butyric acidmethyl ester (PCBM) bulk heterojunction solar cells were studied for their maximum power conversion efficiency (PCE) around 5 %. Efficiencies evolution in time from 10-6 to 1.7 % show the difficulties involved in organic thin-film processing and device characterization. It is of remarkable importance the electrodes geometry, the organic blend solution preparation and the extra-care while processing on flexible substrates (e.g. polyethylene terephthalate PET). Devices are composed of indium tin oxide covered glass, poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT:PSS), P3HT:PCBM active layer, lithium fluoride (LiF) and aluminum. PET covered with In2O3/Au/Ag substituting glass-ITO was employed due to the electronic industry research for low cost alternative materials. Similar structure is used for charge carrier mobility characterization. Techniques such as Time of Flight (ToF), Charge Extraction in Linearly Increasing Voltage (CELIV), and charge transport modeling of current density vs. voltage (JxV) stationary curves were applied on semiconductors like poly(para-phenylene vinylene) (PPV) derivatives. Mobilities around 10-810-6 cm2/Vs for space charge limited current (SCLC) with shallow and deep traps were obtained. Field effect mobilities characterized in bottom gate bottom contact TFTs with common gate are at least two orders higher than previous values. During this work, it was tested different substrates (e.g. monocrystalline silicon and glass-ITO), insulators (e.g. PECVD silicon oxynitride and thermal SiO2), surface treatments (e.g. hexamethyldisilazane vapor), semiconductors (PPV derivatives, P3HT, pentacene) and electrodes (e.g. titanium adhesion layer). It was defined that way a methodology of new semiconducting material selection for the electronic industry.

Layered manufacturing plays important role in industry. Conventional pro-cess planning takes polygon soup as input and has high quality requirements on these polygonal model such as no self-intersection, no degenerate polygon et al. A growing number of models, especially for those in complex shape are acquired from reverse engineering. Implicit representation always serves as intermediate representation and ¯nally need to be tesselated into polygonal mesh for layered manufacturing applications. However, the present tessellation techniques have difficulties to provide topologically faithful and self-intersection free polygonal mesh from implicit model. On the other hand, implicit representation are mathematically compact and robust, which is important for presenting complex freeform models. / I develop a robust and efficient approach to directly slicing implicit solids. Different from prior slicing techniques that reconstruct contours on the slicing plane by tracing the topology of intersected line segments, which is actually not robust, I generate contours through a topology guaranteed contour extraction on binary images sampled from given solids and a subsequent contour simplification algorithm which has the topology preserved and the geometric error controlled. The resultant contours are free of self-intersection, topologically faithful to the given r-regular solids and with shape error bounded; therefore, correct objects can be fabricated from them by layered manufacturing. Moreover, since I do not need to generate the tessellated B-rep of given solids, my direct slicing approach is memory efficient - only the binary image and the finest contours on one particular slicing plane need to be stored in-core. My method is general and can be applied to any implicit representations of solids. / Moreover, I also investigate techniques for support generation for layered manufacturing in image space. Region subtraction is a crucial operation for support generation. I develop a robust and reliable region subtraction method on implicit solid slicing. Compared with the conventional approach in which support regioncontours are produced from part slicing contours by polygonal operations, my approach calculates reasonable support region on binary image for each layer. I investigate a conservative growing-swallow technique to remove as much as possible the support material for self-support region while still guarantee the safety of building process. My region subtraction can serve as core technique for many layered manufacturing processes. In my research, I demonstrate region subtraction technique in both Fused Decomposition Modeling(FDM) and Stereolithography(SLA). A region cleaning technique which can reduce topology complexity of calculated support structure region is developed to fulfil specific requirement of FDM. With all the operations involved being discrete on binary image, my approach is more robust compared with the polygonal operations which are based on numerical computation. Moreover, processing on binary image makes my approach highly parallelizable. My self-intersection free contour extraction technique used in direct slicing can also be adopted to extract support structure contour on binary image if necessary. / Huang, Pu. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 80-84). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract --- p.i / Chinese Abstract --- p.iii / Acknowledgements --- p.iv / List of Figures --- p.vii / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Contribution --- p.4 / Chapter 1.3 --- Organization --- p.5 / Chapter 2 --- Literature Review --- p.7 / Chapter 2.1 --- Direct Slicing on Implicit Solid --- p.7 / Chapter 2.2 --- Slicing based Support Generation --- p.9 / Chapter 3 --- Problem Definition --- p.10 / Chapter 4 --- Topologically Faithful Slicing Contour Generation --- p.12 / Chapter 4.1 --- Introduction --- p.12 / Chapter 4.2 --- Sampling and Contour Generation --- p.15 / Chapter 4.2.1 --- Sampling --- p.16 / Chapter 4.2.2 --- Topologically faithful contouring --- p.17 / Chapter 4.2.3 --- r-Regularity and Accuracy in Layered Manufacturing --- p.19 / Chapter 4.3 --- Constrained Smoothing --- p.20 / Chapter 4.4 --- Contour Simplification --- p.24 / Chapter 4.4.1 --- Variational segmentation --- p.25 / Chapter 4.4.2 --- Topology and distortion verification --- p.27 / Chapter 4.4.3 --- Hausdorff Error Analysis --- p.31 / Chapter 4.5 --- Results and Discussion --- p.33 / Chapter 5 --- Reliable and Robust Region Subtraction for Support Generation --- p.43 / Chapter 5.1 --- Introduction --- p.43 / Chapter 5.2 --- Preliminary --- p.46 / Chapter 5.3 --- Region Subtraction --- p.48 / Chapter 5.3.1 --- Binary Image Grid-width and Self-support Feature Threshold --- p.48 / Chapter 5.3.2 --- Conservative Growing-swallow Method --- p.50 / Chapter 5.4 --- Region Cleaning Technique for FDM --- p.53 / Chapter 5.5 --- Anchor Support Generation for SLA --- p.57 / Chapter 5.6 --- Result and Discussion --- p.60 / Chapter 6 --- Conclusion --- p.71 / Chapter 6.1 --- Summary and Discussion --- p.71 / Chapter 6.2 --- Future Work --- p.73 / Chapter A --- Inconsistent Contouring Problem Analysis --- p.76 / Bibliography --- p.80

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / by Peter Thompson. / B.S.