The Toyota manufacturing system, aptly referred to as Lean manufacturing, has received a reasonable appreciation and awareness over the past decade in South African industry. This production phenomenon constitutes an organizational culture that encourages world-class production success through the liberation of factory resources, while employees are empowered and encouraged to contribute ideas for the improvement of processes and products. However, despite lean awareness and the crucial role of employee participation in the suggestion of ideas in world-class organizations, the performance level of lean manufacturing in South African industry is largely devoid of the Kaizen suggestion tool, particularly in the automotive companies of the Eastern Cape. The aim of this research was to proffer appropriate recommendations, improved awareness, understanding and practice for the improvement of the Kaizen suggestion principle in the automotive companies of the Eastern Cape. The research primarily focused on the ‘management/employees’ paradigm within the organisational context. The methodology employed in the study included a thorough review of the relevant literature and a questionnaire, which was developed and administered to both the management and employees of the thirty automotive components suppliers in Eastern Cape. The target companies constituted the units of analyses and therefore provided the opportunity for a detailed investigation of the links between management and employees as well as a submission of ideas for operational and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically, positivist. However, some qualitative aspects of the data were relevant to the study and, therefore, were used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources while the sampling technique was sequential, involving both purposive and stratified random sampling. The study reveals the apparent lack of a systematic mechanism for the practice and administration of the Kaizen suggestion tools in most Eastern Cape automotive companies. This demerit is found to have negatively affected maximum employee participation and involvement in organizational decision making within the Province. The study has established a basic level of awareness and understanding among employees / employers relations that the Kaizen suggestion scheme is a vital tool for delivering strategic objectives in the management of decision making and organizational growth. The study strongly advocates the inclusion of employee suggestion systems as part of the organizational process.

The lean manufacturing system that evolved in Japan since World War II has leapt across the globe to North America and Europe. The secret success of Japan’s manufacturing machine has been shared. In Europe and America, lean has been identified as a manufacturing best practice that should be adopted to ensure competitive manufacturing efficiency. Many success stories have been told of American companies adopting the Japanese lean tools and techniques. Now, South African manufacturers are implementing the lean manufacturing philosophy, some with more success than others. This research paper explores lean manufacturing implementations at two South African automotive component manufacturers and identifies the critical success factors that have driven the implementation process forward. Commitment from top company executives, extensive training, worker empowerment and other critical success factors for implementing lean manufacturing into a South African environment are identified as a result of the research conducted.

A practical method to utilize carbon nanotubes (CNTs) in structural applications is to fabricate them into buckypapers (BPs), a thin film containing two-dimensional CNT networks, and combine them with a polymer matrix to make BP-polymer (BPP) composites. It has been demonstrated that BPP composites have very good mechanical properties with multi-functional capabilities. However, due to the uncertainties involved in different manufacturing stages, the resulting BPP composites exhibit larger property variations when compared with traditional metal or ceramic materials. As such, there is need for an improved modeling strategy that can provide rapid property predictions and variation quantifications for BPP composites through measurable buckypaper nanostructures and processing conditions. Due to high material costs and long production cycle times, it is nearly impossible to construct a statistical-based model for BPP composites purely from physical experiments. Theoretical (micromechanical) models are more cost effective, but they also have some drawbacks. Namely, they are computationally intensive, deterministic in nature, and have questionable accuracy due to underlying simplified assumptions. Different sources of variations in BPP composite manufacturing also build on the inadequacy of these micromechanical models for providing reasonable predictions without further adjustments. Therefore, the main objective of this study is to provide a better modeling strategy for the prediction of BPP composite stiffness. By integrating a series of statistical methods with traditional micromechanical models, the variations observed in different stages were quantified, and a better predictive surrogate modeling strategy was constructed as a result. The statistical dispersions of buckypaper nanostructures (nanotube bundle length, diameter, orientation and waviness) were first analyzed and characterized by applying image analysis to microscopic images of buckypaper surface. It was found that the distribution of bundle length and diameter can be reasonably described by a two-parameter Weibull distribution, and the orientation of nanotubes can be represented by a periodic Fourier series. A stochastic based model was then constructed to predict the theoretical dispersions of BPP composite stiffness through experimentally measured nanostructure distributions by combining micromechanics with a Monte-Carlo simulation. It was found that the distribution of BP nanostructures would bias the resultant BPP composite modulus if a non-symmetric nanostructure distribution was present. The degree of nanostructure effects and interactions was analyzed using polynomial modeling and sensitivity analysis. The diameter and waviness of nanotube bundles were found to be the most influential factors for BPP composite modulus in most cases. The intra/inter buckypaper variations were studied using an Analysis of Variance (ANOVA) test. Both variations were tested as insignificant and can thus be statistically combined using the "mean nanostructure distribution" with pooled mean and variance. Lastly, two different sets of BPP composite experiments were used to validate the predictive capability of the constructed model. Preliminary results exhibited a noticeable discrepancy between theoretical predictions and physical observations due to the imperfections of the CNT-polymer interface. Therefore, statistical two-stage sequential modeling was applied to calibrate the original micromechanical model, and the resultant surrogate model was demonstrated to possess improved predictive capabilities. Recently functionalized BPP composite data also showed a very good correspondence to the theoretical predictions after the CNT-polymer interface was improved. / A Dissertation submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2010. / May 17, 2010. / Buckypaper, Nanocomposites, Micromechanics, Variation Quantification / Includes bibliographical references. / Chuck Zhang, Professor Directing Dissertation; William Oates, University Representative; Ben Wang, Committee Member; O. Arda Vanli, Committee Member.

The objectives of this research are to develop lightweight high-performance nanotube composite actuators that can be operated in open air and to study their actuation mechanisms. We successfully demonstrated solid electrolyte-based buckypaepr actuators. Long MWNT and dopped SWNT BP actuators showed significant improvement of actuation performance. A constitutive structure-stimulation-performance model has been developed to analyze and predict actuation performance. The modeling results can be further used to improve the actuation performance through parameter studies. Lightweight all-solid-state nanotube composite actuators developed in this research were a bimorph configuration with a high conductive solid electrolyte layer sandwiched by two nanotube buckypaper electrode layers. The effects of driving voltages and frequencies were studied. The nanotube buckypaper composite actuators demonstrated consistent responses to electrical stimulation frequencies up to 40 Hz. Different types of nanotube buckypapers were tested to determine their actuation performance, including randomly dispersed single-walled carbon nanotubes (SWNT), aligned SWNT, randomly dispersed multi-walled carbon nanotubes (MWNT), randomly dispersed long MWNT and SWNT-MWNT mixed nanotube buckypapers. Dynamic mechanical analysis (DMA) and tensile tests were conducted to determine actuator mechanical properties. A Young's modulus of 2.17 GPa from long MWNT buckypaper composite actuator was one of the highest reported values among electro-active polymer composite actuators. The research also realized significant performance improvements by using long MWNT nanotube buckypapers and lithium ion doped SWNT buckypapers as electrode layers. The resultant actuators can achieve more than 20 mm displacements, which is about 10 times greater than untreated SWNT buckypaper composite actuators. Ionic doped SWNT buckypaper actuators are especially promising because they consume 70% less power to perform the same amount of actuation compared to long MWNT buckypaper actuators. The maximum strain and blocking force of the long MWNT BP composite actuators were 0.77% and 8.7 mN, respectively. The research indicated two actuation mechanisms of nanotube buckypaper actuators co-exist: 1) carbon-carbon (C-C) bond extensions when an electrical charge applied, as previously reported in the literature, and 2) an ionic current flow effect in the solid electrolytes. The developed structure-stimulation-performance model was able to predict the displacement of nanotube buckypaper actuators based on both mechanisms. Modeling results indicate that ionic current flow effect was the dominant effect in the devices. By conducting parameter studies, we can reveal the influential factors for actuation performance. The modeling results for the SWNT BP/Nafion actuator were in good agreement with experimental data. The resultant actuators are promising for lightweight morphing structure applications. / A Dissertation submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2010. / December 23, 2009. / Actuator, Nanotube / Includes bibliographical references. / Zhiyong Liang, Professor Directing Dissertation; William Oates, University Representative; Ben Wang, Committee Member; Chuck Zhang, Committee Member.

The discovery of carbon nanotubes (CNTs) by Iijima in 1991 has initiated a great deal of scientific research on exploring their unique properties and potential applications. One of the promising applications is integrating CNTs into polymer or polymer/fiber composites to form nanocomposite or multi-scale composites. High temperature polymer composites are required for use in structural components in advanced high speed aircraft, weapon systems and space vehicles. Motivated by the potential of significantly improving thermal, electrical, mechanical and properties and fire retardancy of polymer matrix composites at relatively low concentration, this research focuses on integrating CNTs into high temperature fiber-reinforced composites aiming at matrix enhancement at the inter-fiber level, z-direction reinforcement and multi-functionality such as thermal and electrical conductivity, fire retardancy or resistance. High temperature vacuum-assisted resin transfer molding was designed and successfully demonstrated with in-plane and through-thickness resin flow methods. Polyimide based PETI-330/carbon fabric T650-35 laminates were manufactured with fiber volume fraction of ~60% and void contents of 3-4%. The tensile strengths of PETI-330/T650-35 laminates fabricated by in-plane and through-thickness processes are 834 and 799 MPa, respectively. Short beam strengths of the laminates via both processes are 43 and 52 MPa, which are ~77% and ~93% of that processed via RTM using an injection pressure of 2.75 MPa. CNT/carbon fiber/PETI-330 multi-scale composites were fabricated using prepreg-assisted RTM process. Homogeneous dispersion of CNTs in the PETI-330 matrix were achieved using the solution processing method. Using this method, multi-scale composite laminates with various concentrations of CNTs were manufactured. Comprehensive characterizations were carried out to investigate the thermal stability, thermal mechanical properties, micro-structure and morphologies of the CNT/PETI-330/T650 multi-scale composite laminates. As a result, we found that: (1) the incorporation of small amounts of CNTs can significantly improve the high-temperature thermal mechanical properties of the PETI-330 resin; (2) after postcuring the room temperature storage modulus of 1 wt% CNT/PETI-330/T650 composite increased from ~60 GPa to ~71GPa, the glass transition temperature increased from 331°C to 350°C; (3) the existence of CNT induces hindered cure kinetics of PETI-330. Multiscale composites were also fabricated using buckypapers made of mixed SWNTs/MWNTs integrated onto polyimide/carbon fibre composite surface and their fire retardancy was characterized. Compared to the control sample (CP), buckypaper incorporated sample produced further delayed ignition, 40% lower peak heat release rate, 26% lower heat release, 82% less smoke release and 33% less mass loss. Further, buckypaper effectively increases the thermal conductivity of PETI-330/carbon fiber composite; the thermal conductivity improves 13% at 25°C and 27% at 300°C. The buckypaper is more efficient as fire retardant in polyimide/carbon fiber composites than direct mixing CNTs into polymer matrix. The effect of CNTs on the cure kinetics of imide oligomer was studied using differential scanning calorimetry. During isothermal cure, the neat resin begins to cure first. As the reaction proceeds, the enthalpy of reaction decreases for the nanocomposites. As the samples vitrify and the reaction is completed, the neat PETI-330 vitrifies faster than the 1% CNT/PETI-330 nanocomposite sample. The adding of 1 wt% CNTs caused lower enthalpy, slightly lower activation energy. The cure kinetics of neat PETI-330 and the PETI-330/CNT systems can be modeled as first-order reactions, meaning the reactions are mainly ethynyl-ethynyl addition polymerization to form carbon-carbon double bonds. Comparison of the activation energies, rate constant and cure times suggests that the cure mechanisms of the neat PETI-330 resin and CNTs embedded nanocomposites are similar. Last but not least, the molecular models of the PETI-330 imide oligomer and CNTs were constructed. Molecular dynamics simulations showed that molecular interaction energy of imide/ CNT system is -37.5 kcal/mol. The major contributor of the interactions between CNT and the imide oligomer is van de Waals energy which is due to the Ĉ-stacking effect between similar molecular structure of CNT surface and the phenyl rings in the backbone and side-groups. The attractive energy between CNT and imide oligomer can explain why the glass transition temperature shifts toward higher temperature in multi-scale composites manufactured in this study. / A Dissertation submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2010. / September 28, 2010. / Multifunctionality, Cure Kinetics, Processing, Multiscale Composites, Polyimide, Carbon Nanotube, High Temperature Composites / Includes bibliographical references. / Chuck Zhang, Professor Directing Dissertation; Tao Liu, Professor Co-Directing Dissertation; Sachin Shanbhag, University Representative; Zhiyong Liang, Committee Member.

This research focuses on the third-order response surface designs for global optimization and mapping of systems or processes. The current second-order response surface designs may not be accurate and efficient enough to describe the true model of the systems or processes in terms of multiple design criteria. This research addresses the needs for third-order designs by identifying corresponding inaccuracy issues and attempts to create efficient designs by investigating different ways of building third-order models. This research proposes functionality as a new design property to guide the comparison of practicability and ease of use of different designs. Furthermore, it looks into generating multiple criteria optimal third-order designs for continuous cuboidal region using NSGA-II algorithm. IV-optimality and space filling have been selected as the two primary objectives for this multiple criteria third-order design problem. This research shows that the NSGA-II does not provide the results as expected for third-order designs, and nested faced centered design is the best overall design in IV-optimality, space filling, orthogonality and functionality. A Pareto-optimal front is given to satisfy different practitioners' needs. / A Thesis Submitted to the Department of Industrial and Manufacturing in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Fall Semester, 2008. / October 31, 2008. / Third-Order Response Surface Design, Mutiple Objective Optimization, Evolutionary Algorithm / Includes bibliographical references. / Joseph J. Pignatiello, Jr., Professor Directing Thesis; Samuel. Awoniyi, Committee Member; Arda Vanli, Committee Member; Okenwa Okoli, Committee Member.

Since the discovery of Carbon Nanotubes in 1991, nanotechnology has come to a new episode. One of the new applications of single walled carbon nanotubes (SWNTs) is to develop high performance actuators. Nanotube actuation mechanism relies on quantum chemical expansion of graphitic carbon lattice if an additional electrical charge was applied. By electrochemical charging and discharging, a motion of carbon nanotubes can be generated. The phenomenon can be easily demonstrated on a free standing film of SWNT buckypaper in an aqueous electrolyte. In this research, a setup was first established to accurately monitor actuation performance of SWNT buckypaper actuators. From a series of designed experiments, we found that the maximum deformation and applied voltage have a linear relationship. The actuation performance in varied electrolyte was also investigated. For alignment effect of SWNTs, it is the first time that we successfully performed a detailed characterization of the actuation performance of magnetically aligned buckypaper actuators. The aligned buckypaper actuators can demonstrate good response to electrical signal, showing very good repeatability and reversibility. In the experiments of using actuators with different dimensions, we found that larger surface area of SWNT actuators can create more deformation capacity, but it also made the actuator tip deflection unstable. In the high frequency response experiments, all of our SWNT actuator samples demonstrated good response to 1Hz and 10HZ square wave. The tip deflection of SWNT actuators decreased with the increases of electrical frequency. Finally, we developed a SWNT buckypaper/silver paint composite actuator for the first time. It can successfully respond to electrical signals. The results of this research provide essential data and information for further development and optimization of SWNT actuators. / A Thesis Submitted to the Department of Industrial Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Summer Semester, 2005. / July 6, 2005. / Actuator, Swnt / Includes bibliographical references. / Zhiyong Liang, Professor Directing Thesis; Ben Wang, Committee Member; Chuck Zhang, Committee Member; Young-Bin Park, Committee Member.

Supply chain optimization is a set of approaches utilized to efficiently integrate suppliers, manufacturers, warehouses, and stores, so that merchandise is produced and distributed at the right quantities, to the right locations, and at the right time, in order to minimize system-wide costs, while satisfying service level requirements. The proposed study addresses the issue of supply chain optimization amongst three companies: Vistakon, which sources the cartons to package ACUVUE contact lens; North State Cartons, which is the carton supplier; and Durango Paper Company, which is the paperboard supplier. An effort is made to integrate the production and information flow and ensure timely production and distribution of the cartons, which reduced the lead-times and inventory levels at Vistakon's, North State Carton's, and Durango Paper Company's site location. The complete supply chain solution to optimize the existing system is provided and the ordering process solution is presented in the form of service level models. As a result of optimized supply chain management, the overall lead-time of the complete cartons manufacturing and procurement process is enormously reduced. The supply chain member organizations are benefited by reduced carton inventory levels, effective demand forecasting system, better inventory management system, improved information sharing system, decreased annual setup cost, and increased annual savings. / A Thesis Submitted to the Department of Industrial Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Fall Semester, 2003. / November 03, 2003. / Supply Chain Management, Process Re-engineering, Operations Research, Lean Manufacturing, Just-in-time philosophy, Purchasing, Single member three-echelon supply chain, Carton manufacturing, Process improvement, System Design, Order process solution, Demand forecast, Lean supply chain, Supply chain optimization, Three echelon system / Includes bibliographical references. / James Simpson, Professor Co-Directing Thesis; Larry Giunipero, Professor Co-Directing Thesis; Okenwa Okoli, Committee Member.

A dissertation submitted in fulfilment of the requirements for the degree of Masters of Science in Engineering (Electrical) to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, 2017 / The Travelling Salesman Problem (TSP) is an important NP-hard combinatorial optimisation problem that forms the foundation of many modern-day, practical problems such as logistics or network route planning. It is often used to benchmark discrete optimisation algorithms since it is a fundamental problem that has been widely researched. The Flower Pollination Algorithm (FPA) is a continuous optimisation algorithm that demonstrates promising results in comparison to other well-known algorithms. This research proposes the design, implementation and testing of two new algorithms based on the FPA for solving discrete optimisation problems, more specifically the TSP, namely the Discrete Flower Pollination Algorithm (DFPA) and the iterative Discrete Flower Pollination Algorithm (iDFPA). The iDFPA uses two proposed update methods, namely the Best Tour Update (BTU) and the Rejection Update (RU), to perform the iterative update process. The two algorithms are compared to the Ant Colony Optimisation’s (ACO) MAX−MIN Ant System (MMAS) as well as the Genetic Algorithm (GA) since they are well studied and developed. The DFPA and iDFPA results are significantly better than the GA and the iDFPA is able to outperform the ACO in all tested instances. The iDFPA with 300 iterations was able to achieve the optimal solution in the Berlin52 benchmark TSP problem as well as have improvements of up to 4.56% and 41.87% compared to the ACO and GA respectively. An analysis of how the RU and the annealing schedule used in the RU impacts on the overall results of the iDFPA is given. The RU analysis demonstrates how the annealing schedule can be manipulated to achieve certain results from the iDFPA such as faster convergence or better overall results. A parameter analysis is performed on both the DFPA and iDFPA for different TSP problem sizes and the suggested initial parameters for these algorithms are outlined. / XL2018

Yes / Manufacturing is a global activity that started during the industrial revolution in the late 19th century to cater for the large-scale production of products. Since then, manufacturing has changed tremendously through the innovations of technology, processes, materials, communication and transportation. The major challenge facing manufacturing is to produce more products using less material, less energy and less involvement of labour. To face these challenges, manufacturing companies must have a strategy and competitive priority in order for them to compete in a dynamic market. A review of the literature on the decomposition of manufacturing processes outlines three main processes, namely: high volume, medium volume and low volume. The decomposition shows that each sub process has its own characteristics and depends on the nature of the firm’s business. Two extreme processes are continuous line production (fast extreme) and project shop (slow extreme). Other processes are in between these two extremes of the manufacturing spectrum. Process flow patterns become less complex with cellular, line and continuous flow compared with jobbing and project. The review also indicates that when the product is high variety and low volume, project or functional production is applied. / The financial support by the Malaysian Government, Universiti Malaysia Pahang and Bradford University for this research is gratefully acknowledged.