This thesis focuses on the use of a knowledge-based computer aided system for the task of bare printed circuit board (PCB) process planning. To achieve this task, a knowledge-based computer system has been developed in which process plans can be generated automatically. The planning decisions are based on board requirements, customer general specifications and product quality standards.

Lean manufacturing is the method to drive the costs down. Thesis concerns historic development of lean manufacturing methods giving special attention to Taylor's scientific management, husbands Gilbreth motion studies and Ford's production schema for "T" model. From today praxis the thesis is considering TPS (Toyota Production System) developed by Toyota Motor Corporation as an application of lean manufacturing. It was further developed by James Womack and Daniel Jones in their lean manufacturing theory analysis. The thesis introduces the example about fictitious HAD Corporation that is constructed on the bases of three real IT global companies. Analysis applies Womack's and Jones theory of lean manufacturing including five steps: value, value stream, flow, pull, perfection. The thesis can serve as an overview of lean manufacturing history, current methods and case study.

The diploma thesis covers principles, history, implementation process and selected real MES systems. First part is focused theoretically and covers an introduction to topic of MES systems based on current literature. In this part main terms, principles and historical evolution are covered. Next the thesis describes implementation process in more detail and identifies its critical factors. This process is compared with implementation process of general applications and main differences are identified. In next part of the thesis metrics system for measuring of MES systems is established. Based on these metrics selected MES systems are introduced and are evaluated. Then these systems are compared and their main differences are identified with an explanation. Last part of the thesis is focused on system Apriso FlexNet (hereinafter FlexNet). In this part FlexNet is described in more detail and critical evaluation is made according to identified principles in theoretical part and characteristics of other presented systems. Trough fulfilling its aims the thesis provides introduction to the topic of MES systems, presents several selected systems and compares them. Last but not least FlexNet system is introduced in more detail with its critical evaluation.

No abstract available. / Dissertation (MBA)--University of Pretoria, 2010. / Graduate School of Management / Unrestricted

Since the discovery of carbon nanotubes in 1991 alongside their superior performance in mechanical and electrical properties, carbon nanotubes have been widely considered to be one of the most promising next generation materials. They have been frequently used in polymer composites due to their high strength-to-weight and modulus-to-weight ratios. Yet despite their promising qualities in manufacturing, carbon nanotube based composites still have many issues that need to be resolved before they can be used for industrial applications. In order to more cost effectively produce nanocomposites and improve their quality, it is necessary to accurately observe and understand the variations in their raw material properties. The variability of the raw material in nanotube based composites usually has a large impact on the properties of the eventual product. However, physical experimentation for the purpose of quantifying variability in nanomaterial properties is usually expensive and sometimes not feasible or accurate enough. This paper presents a constrained nonlinear programming approach for the quantification of raw material variability while also examining the impact of raw material variability on the properties of buckypaper polymer (BPP) composites. The proposed approach suggests conducting small physical experiments to collect data on raw material properties and final composite part properties before employing an inverse uncertainty propagation approach to estimate the parameters of the probability distribution of the material properties. Both univariate and multivariate probability distributions are considered. A case study based on data from a real buckypaper manufacturing process is used to illustrate the approach. It is shown that simultaneously modeling the material properties with a multivariate distribution improves the quality of the identified model. / A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2010. / June 11, 2010. / Uncertainty Quantification, Monte Carlo Simulation, Nonlinear Programming, Nanocomposites / Includes bibliographical references. / Arda Vanli, Professor Directing Thesis; Joseph Pignatiello, Committee Member; Chad Zeng, Committee Member; Ben Wang, Committee Member; Chuck Zhang, Committee Member.

Since their discovery in 1991, carbon nanotubes have undergone intensive research. The single-walled carbon nanotube, or SWNT, has a unique electronic structure. According to their chirality, they can be either metallic or semiconductors with various band gaps. These different electronic structures influence their electrical and thermal properties. Studies have been conducted to understand, model and measure their electrical and thermal properties by computer simulation and experimental measurements. Even though current research shows inconsistent results, all studies show that SWNTs have phenomenal electrical and thermal properties. To take advantage of these unique properties of nanotubes requires properly incorporating SWNTs into a matrix as a reinforcement or filler to form nanocomposites with desired properties. Carbon nanotube reinforced composites are still under development. The mechanical properties of these materials have been intensively explored; however, the electrical and thermal properties still require further study. The main objective of this thesis was to measure and understand the thermal behavior of SWNT-reinforced composites. This thesis focuses on 1) the thermal conductivity of buckypapers (aligned or random SWNT network from filtration of well-dispersed nanotube suspension) and the nanocomposites produced from the buckypapers, and 2) the influence of nanotubes on thermal expansion by direct mixing and casting samples of SWNT/epoxy nanocomposites. Thermal conductivity was measured using a comparative method, with a constantan foil as a reference. The temperature dependence of the thermal conductivity was measured from 115 K to room temperature. Magnetically aligned buckypapers produced with 17.3 Tesla magnetic field showed the highest thermal conductivity at room temperature, with a maximum value of 41.5 W/mK in the aligned direction. The coefficient of thermal expansion (CTE) was measured using the Thermomechanical Analyzer (TMA). The influence of nanotube functionalization and loading on the CTE of the epoxies revealed that adding 1 wt% nanotubes in the epoxy resin could reduce the CTE of the resin as much as 35.5%. The mechanisms of thermal conductivity variation and CTE reduction in the buckypapers and nanocomposites are also discussed. / A Thesis submitted to the Department of Industrial Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2004. / July 12, 2004. / Carbon Nanotube, Buckypaper, Thermal Conductivity, CTE / Includes bibliographical references. / Zhiyong Liang, Professor Directing Thesis; James Brooks, Committee Member; Ben Wang, Committee Member; Chuck Zhang, Committee Member.

Carbon nanotubes (CNTs) have drawn interest for many applications since their discovery. While they provide exceptional mechanical, physical and chemical properties, several technical barriers must be overcome before these properties can be fully used. Some of such drawbacks concern length control, lack of good dispersion and poor interfacial bonding. Currently, CNTs such as single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) and carbon nanofibers (CNFs) are produced in lengths ranging between several to hundreds micrometers and are usually bounded into macroscopically entangled networks. This contradicts with the requirements of some applications, which in the end will benefit with short and highly dispersed CNTs in lengths of a few hundred nanometers or less, such as drug delivering and energy storage carriers. Short CNTs (s-CNTs) and CNFs (s-CNFs) can enhance the mechanical properties of a composite due to the increased interaction with the polymer matrix, through the improvement of the interfacial bonding and resin encapsulation, which is possible with existing open ends of nanotubes. Ultimately this influences the matrix's properties by affecting its chain entanglements, morphology, and crystallinity in the nanocomposite. This research is a continuous effort on nanoscale cutting and characterization of s-CNTs and s-CNFs. Moreover, this research used s-MWNTs and s-CNFs in the lengths of 200 and 500 nm to manufacture the nanocomposites. The mechanical properties of the resultant nanocomposties were characterized. The interactions of the s-MWNT and s-CNTs with epoxy resin matrix were observed using high-resolution SEM and atomic-resolution TEM. The results were compared to nanocomposites with pristine MWNTs and CNFs. In the study, four case studies were explored: 1) 200 nm s-MWNT/epoxy composites; 2) 500 nm s-MWNTs/epoxy composites; 3) 200 nm s-CNF/epoxy composites; 4) 500 nm s-CNF/epoxy composites. For all four cases the MWNT and CNF concentrations were 0.05 wt%, 0.10 wt%, and 1.00 wt%, respectively. Significant mechanical improvements were observed. The strength of the s-MWNT nanocomposite at 1.00 wt% gave a 64% improvement compared to the control sample. The highest young's modulus was also obtained in the 1.00 wt% s-MWNT (200 nm) nanocomposite, and it showed an increase of 44%. In general, the most significant improvements were seen with the s-MWNTs (200 nm) nanocomposites due to their smaller diameters and shorter length. Glass transition temperature was also studied. Finally, the interfacial bonding and interactions of the nanotube's opened ends with the resin matrix were observed through HR-SEM and atomic-resolution TEM analysis, which validated the creation of MWNT and CNF opened ends and the actual resin encapsulation inside the nanotubes' hollow structures. / A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester, 2011. / April 27, 2011. / short carbon nanotubes, open ends nanocomposites / Includes bibliographical references. / Zhiyong Richard Liang, Professor Directing Thesis; Tao Liu, Committee Member; Chun Chuck Zhang, Committee Member.

The current research studied the idea of introducing energy-absorbing polymers – specifically high-density viscoelastic polyurethanes – to reduce the blunt trauma from residual impact energy. This work investigated the material properties of viscoelastic polyurethane foams and the efficacy of the addition of an energy absorbing material to protective garments for reducing blunt trauma under low-velocity impact. The research also provided a methodology for testing composite plates backed by soft materials during low-velocity impact tests. The thickness of the backing material was proven the most influential factor in energy absorption during impact. Finally, using optimization tools, a suggested thickness and bonding condition was given for the implementation of viscoelastic foam in protective garments. / A Thesis Submitted to the Department of Industrial Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2008. / November 21, 2007. / Polyurethane Foam, Impact, Blunt Trauma, Composite / Includes bibliographical references. / Okenwa O. I. Okoli, Professor Directing Thesis; Samuel Awoniyi, Committee Member; James Simpson, Committee Member; Ben Wang, Committee Member.

This research presents a study on an innovative composite manufacturing process called Resin Infusion between Double Flexible Tooling (RIDFT). In this process, resin is infused between two flexible tools through fiber reinforcements in a two-dimensional flat shape. The wetted reinforcements and flexible tooling are then formed over a mold into a specified part shape by use of vacuum. The RIDFT process has potentials for rapidly and affordably producing large composite parts. This research details the development of the industrial RIDFT machine from its design to its fabrication and to the demonstration of its use. This new machine uses new techniques, integrating vacuum sealing, dynamic supporting and temporary resin distribution channels to achieve industrial application requirements. A design of experiment (DOE) approach is used to perform testing and analysis to validate the ability of the RIDFT process to form various geometries and identify limitations in formability and issues with wrinkling. Four specific fiber textile structures were studied in their ability to form over a half sphere of varying radii and a rectangular mold of varying corner radii. The number of fiber layers was also studied to understand the effects on forming. Fiber textile structure and fiber layers were shown to be significant for their influence on formability and wrinkling. To better understand the forming mechanics within the RIDFT process and to predict the formability of a desired geometry, a simulation model was required. The PAMFORM software was chosen for modeling because it is a general-purpose finite element package for the industrial virtual manufacturing of non-metallic sheet forming. PAMFORM is unique in its ability to model a variety of forming processes. This research details the development of the simulation model for the RIDFT process based on PAMFORM and describes the validation of the model through experimental methods. This development includes the modeling of multiple layers of resin-wetted reinforcements, silicone diaphragms and part geometries, as well as the modeling of contact interfaces and forming pressures. The systematic investigation has been done for characterizing fabric drapability, rubber deformation and friction interactions for developing the simulation model. The model results are then compared against experimental results for model validation. This validated model will allow the ability to predict drapability and fiber deformation during the process forming. The results of the simulation reveal mechanisms and influence factors of the drapability and wrinkling of the RIDFT process. / A Dissertation Submitted to the Department of Industrial Engineering & Manufacturing Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Fall Semester, 2003. / November 10, 2003. / RIDFT, Resin Infusion, Drapability, Manufacturing, Composites, Simulation / Includes bibliographical references. / Zhiyong Liang, Professor Directing Dissertation; Ching-Jen Chen, Outside Committee Member; Ben Wang, Committee Member; Chuck Zhang, Committee Member; James Simpson, Committee Member.

General augmentation techniques such as foldover and semifold have been a common practice in industrial experimentation for many years. Even though these techniques are extremely effective in maintaining balance and orthogonality, they possess serious disadvantages such as the inability to decouple specific terms and a high level of inefficiency. This dissertation aims for a sequential experimentation approach capable of improving the drawbacks of the general methods while maintaining some of its benefits. Chapter 3 begins with proposing an algorithm for sequential augmentation of fractional factorial designs resolution III. The proposed algorithm is compared with its competitors, semifold and foldover using simulated data under 3 noise level conditions. Advantages, limitations, and potential benefits of the new method are provided. Chapter 4 explores new possibilities for augmentation of efficient mixed-level designs (EAs). Current augmentation methods for mixed-level designs include only the optimal foldover plans developed by Guo (2006). Semifold plans for several mixed-level designs are developed by selecting half of the treatment combinations of the foldover fraction using the general balance metric criterion and an exhaustive search approach. Chapter 5 complements this research by providing a methodology for sequential augmentation of mixed resolution robust designs. The work presented here extends the current limits of sequential experimentation for resolution III, mixed-level and robust designs and provides a viable alternative for the experimenter in situations in which financial restrictions do not allow the implementation of a general method. / 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, 2008. / July 11, 2008. / Semifold, Foldover, Level, Mixed, Robust, Resolution, Sequential, Experimental Design / Includes bibliographical references. / James R. Simpson, Professor Directing Dissertation; Fred Huffer, Outside Committee Member; Joseph J. Pignatiello, Jr., Committee Member; Marcus Perry, Committee Member.