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.

Electrically conductive polymers (ECPs), offering capabilities such as electrostatic discharge protection and electromagnetic interference shielding, have been the subject of intensive research and development both in academia and industry. The emergence of new conductive nano-fillers in recent decades, particularly carbon nanotubes (CNTs), further fuels more enthusiasm. Thanks to CNTs' excellent mechanical, thermal, and electrical/electronic properties, CNT-filled polymers possess not only conductive properties, but a range of other properties desirable for multi-functional and high performance applications. In order to fully exploit the benefits of CNT-based conductive polymers (CNT-ECPs), researchers have conducted diverse studies primarily to characterize the electrical conductivity of the composites. A crucial area that is less studied is the piezoresitive behaviors of CNT-ECPs, that is, the change in material conductive properties due to an applied stress or strain. Given broad usage of ECPs, it would be reasonable to assume that ECP products commonly operate under certain stress or strain conditions. For instance, an electrostatic discharge (ESD)-protected conductive coating for spacecraft would be affected by strain induced by mechanical or aerodynamic loads. A more systematic understanding of the materials' piezoresistivity, therefore, is instrumental in ensuring satisfactory conductive performance of those material applications. Additionally, knowledge of conductive characteristics of the CNT-ECPs against stress/strain can open the door to newer material applications, e.g., strain gage or multifunctional conductive coating with strain-sensing capability. This research aims to achieve a more fundamental understanding of the mechanism of piezoresistive property of CNT-ECPs, and to develop a model that permits quantifying the structure-property relationships of CNT-ECPs' piezoresistivity. In this research, expanded experimental studies with various thermoplastic CNT-ECPs revealed that piezoresistivity in CNT-ECPs is dominated by changes in inter-tube resistances. Additionally, the gauge (sensitivity) factors of the CNT-ECPs follow an exponential relationship with (v – vc), where v is the volume concentration of CNT in the composite and vc is the tube volume concentration at its percolation threshold. The model development effort yielded a semianalytical piezoresistivity model capable of analyzing and predicting piezoresistivity in three-dimensional CNT-ECP samples. The model is most applicable to systems with straight short MWNTs randomly dispersed in thermoplastic polymers. / A Dissertation Submitted to the Industrial & Manufacturing Engineering Department in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Fall Semester, 2008. / November 07, 2008. / Nanocomposite, Sensor, Percolation Theory / Includes bibliographical references. / Zhiyong (Richard) Liang, Professor Directing Dissertation; Chuck Zhang, Committee Member; Joseph J. Pignatiello, Jr., Committee Member; Young-Bin Park, Committee Member; Petru Andrei, Outside Committee Member.

Most of the Federal Motor Vehicle Safety Standards applicable to school buses do not specifically cover the cutaway type of buses assembled on ladder-type chassis, for which a production process is split into two stages. In the first stage, the chassis and cab section are assembled by automobile manufacturers. In the second stage, the vehicle is shipped to another company where the bus body and additional equipment are installed. Lack of strict structural standards for transit bus body builders necessitates the crashworthiness and safety evaluation of this category of vehicles. Such an assessment process is imperative since these transit buses are often used to transport disabled passengers. A full scale crash test is considered the most reliable source of information regarding structural integrity and safety of motor vehicles. However, the high cost of such tests and difficulties in collecting data results in an increasing interest in the analytical and computational methods of evaluation. Theses methods allow for extensive safety studies once the finite element model is validated. A reliable analytical investigation can reduce the cost dramatically and allow faster introduction of the new solutions. This thesis research work presents the procedure for development of a finite element (FE) model of a public transit bus and the results of its crashworthiness and structural integrity analysis. The finite element model was developed based on the geometry obtained by disassembling and digitizing all major parts of the actual bus. The FE model consists of 73,600 finite elements, has 174 defined property sets (groups of elements with the same features) and 23 material models. All parts are connected using different multi point constraints and special links with failure to model actual types of structural connections such as bolts and spot welds. LS-DYNA non-linear, explicit, 3-D, dynamic FE computer code was used to simulate behavior of the transit bus under different impact scenarios, such as frontal impact and side impact at various velocities. / A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2003. / November 10, 2003. / Analysis, Element, Finite, FEM, FEA / Includes bibliographical references. / Okenwa Okoli, Professor Directing Thesis; Jerry Wekezer, Committee Member; Robert Braswell, Committee Member.

Poisson count process are often used to model the number of occurrences over some interval unit. In an industrial quality control setting, these processes are often used to model the number of nonconformities per unit of product. Current methods used for monitoring and estimating changes in Poisson count processes assume that the magnitude and type of change are known a priori. Since rarely in practice are these known, this dissertation reports on the development and evaluation of several methods for detecting and estimating change points when the magnitude and type of change are unknown. Instead, the only assumption requires that the type of change belongs to a family of monotonic change types. Results indicate that the methodologies proposed throughout this dissertation research provide robust detection and estimation capabilities (relative to current methods) with regard to the magnitude and type of monotonic change that may be present. / A Dissertation Submitted to the Department of Industrial Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. / Summer Semester, 2004. / May 28, 2004. / Maximum Likelihood Estimation, Hypothesis Testing, Quality Control, Special Cause Identification, Statistical Process Control, Poisson Count Processes, Process Improvement, Change Point Estimation, Likelihood Ratio, Change Point Detection, Average Run Length, Order-Restricted Inference, CUSUM Control Chart, PAV Algorithm / Includes bibliographical references. / Joseph J. Pignatiello, Jr., Professor Directing Dissertation; Anuj Srivastava, Outside Committee Member; James R. Simpson, Committee Member; Chuck Zhang, Committee Member.

Proper function of traffic photometric devices such as traffic signal modules is crucial for safe operation in the traffic environment. The Traffic Engineering Research Lab (TERL) of Florida Department of Transportation (FDOT) has a significant role in ensuring that these devices perform in accordance to specified standards at all times. Therefore it is necessary that this lab is equipped with the right kind of test facility and procedures, thus enabling device performance verification be done periodically in addition to new device qualifications. The Institute of Transportation Engineers (ITE) specification is used as one of the governing documents. This research will describe an investigation performed upon the test procedure for light emitting diode (LED) signal modules. The purpose of the investigation was to identify variability in procedure activities and to determine the overall test procedure primarily using design of experiments methodology and other statistical analysis approaches. Data analysis by this methodology was essential to characterize process variability because the test procedure execution requires management of six input factors which were not previously tested for significance. Findings from this work are also used to recommend to the lab management on issues about potential facility upgrades. Recommendations were also provided to the ITE to explore the validity of their data from statistical perspective. This research improved the test procedure for testing LED signal modules which will permit further determination of other photometric devices test procedures. / A Thesis Submitted to the Department of Industrial Engineering in Partial Fulfillment of the Requirements for the Degree of Masters of Science. / Summer Semester, 2006. / July 10, 2006. / Test Procedure, Design of Experiments, LED Signal Module, Spectrascan Colorimeter / Includes bibliographical references. / James R. Simpson, Professor Directing Thesis; Joseph J. Pignatiello, Jr., Committee Member; Okenwa Okoli, Committee Member.

Buckypapers are thin films of nanostructured membranes made from carbon nanotubes (CNTs), which are amazingly strong nanomaterials that measure 1/50,000th the diameter of a human hair. Buckypapers have outstanding thermal, electrical and physical properties that can be used for numerous applications such as de-icing, lightning-strike protection, miniaturization of electrical connections, smart-materials, etc. Buckypaper is a relatively new material that still needs to be produced more efficiently in order to create bulk nanostructured composites with desirable dispersion and in-plane alignment nanotubes. The current batch-production method has its own associated limitations and problems, including overheating suspensions with small volumes, as well as spilling and improper sonication operation. Manufacturing buckypapers through an automated continuous process will significantly increase their quality, success rates, production rates and processing efficiency. More importantly, this type of process will provide the much-needed continuity of buckypapers for use in composite automation production and the enhancement of electrical conducting properties. This thesis developed a continuous suspension production process, examined effective filtering methods and discussed the integration of the two main processes to form a complete continuous and automated manufacturing process. The work also presented quality control methods and procedures developed specifically for continuous buckypaper using UV-vis spectroscopy techniques. This thesis concludes with the characterization of the resultant continuous buckypaper products to examine their nanostructures and properties. The success of developing the prototype of an automated continuous process provides critical techniques for further realizing industrial production of quality nanotube buckypapers for various applications. / A Thesis Submitted to the Department of Industrial and Manufacturing Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Spring Semester, 2008. / April 9, 2008. / Dispersion, Ultrasonic, Suspension, Buckypaper SWNT, UV-vis, Nanotubes, Quality / Includes bibliographical references. / Zhiyong Liang, Professor Directing Thesis; Ben Wang, Committee Member; Irinel Chiorescu, Committee Member.

Carbon nanotubes (CNTs) demonstrate extraordinary properties and show great promise in enhancing in-plane and out-of-plane properties of traditional polymer/fiber composites and enabling functionality. However, current manufacturing challenges hinder the realization of their potential. In the dissertation research, both experimental and computational efforts have been conducted to investigate effective manufacturing techniques of CNT integrated multiscale composites. The fabricated composites demonstrated significant improvements in physical properties, such as tensile strength, tensile modulus, inter-laminar shear strength, thermal dimension stability and electrical conductivity. Such multiscale composites were truly multifunctional with the addition of CNTs. Furthermore, a novel hierarchical multiscale modeling method was developed in this research. Molecular dynamic (MD) simulation offered reasonable explanation of CNTs dispersion and their motion in polymer solution. Bi-mode finite-extensible-nonlinear-elastic (FENE) dumbbell simulation was used to analyze the influence of CNT length distribution on the stress tensor and shear-rate-dependent viscosity. Based on the simulated viscosity profile and empirical equations from experiments, a macroscale flow simulation model on the finite element method (FEM) method was developed and validated to predict resin flow behavior in the processing of CNT-enhanced multiscale composites. The proposed multiscale modeling method provided a comprehensive understanding of micro/nano flow in both atomistic details and mesoscale. The simulation model can be used to optimize process design and control of the mold-filling process in multiscale composite manufacturing. This research provided systematic investigations into the CNT-based multiscale composites. The results from this study may be used to leverage the benefits of CNTs and open up new application opportunities for high-performance multifunctional multiscale composites. / 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. / June 17, 2008. / Multifunctional Materials, Multiscale Composites, Carbon Nanotubes / Includes bibliographical references. / Chuck Zhang, Professor Co-Directing Dissertation; Ben Wang, Professor Co-Directing Dissertation; Subramanian Ramakrishnan, Outside Committee Member; Zhiyong Liang, Committee Member; David Jack, Committee Member.

Many researchers proposed the use of carbon nanotubes as an advanced metal catalyst support for electrocatalysis applications. In this research, buckypaper (thin film of preformed nanotube network) electrodes with different weight ratios of carbon nanomaterials, including SWNT, MWNT, CNF, and Vulcan XC-72 (CB), were fabricated and compared by their electrochemical properties using cyclic voltammetry (CV) test. Platinum (Pt) nanoparticles were successfully electrodeposited on the mixed buckypapers in mixed ethylene glycol, H2PtCl6, and H2SO4 aqueous solutions by applying a potential pulse at 0.2 and -0.25 V, forming Pt/mixed buckypaper electrodes. The dispersion and particle size of Pt nanoparticles on the buckypapers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The average diameter of Pt nanoparticles on the buckypapers was 10 nm. Surface areas of the Pt nanoparticles on the mixed buckypapers were determined by cyclic voltammogram measurements in 0.5 M H2SO4 solution, and electrocatalytic performances of the resultant buckypaper electrodes were observed. Compared to the Pt/CB electrodes, the Pt/SWNT+MWNT buckypaper electrode exhibits higher electrocatalytic performance. The highest electrochemical surface area (ECSA) of Pt/SWNT+MWNT (1:3) electrodes reaches 43.7m2/g and is about 1.6 times higher than that of the Pt/CB electrode. This may be attributed to the small particle size and good dispersion of platinum, high conducting property of carbon nanotubes, special deposition phenomenon, and unique three–dimension electrode structure. The research results suggest that mixed buckypapers are good candidates for catalyst supports in fuel cell applications because of their high electrocatalytic performance. The reduction of the amount of precious metal catalyst (Pt) needed is important for real-world applications. Further research into the optimization of Pt deposition and nanostructure of mixed buckypapers could lead to highly efficient and potentially affordable electrodes for fuel cell applications. / A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2007. / November 06, 2007. / Electrode, Buckypaper, PEMFC / Includes bibliographical references. / Zhiyong Liang, Professor Directing Thesis; Jim P. Zheng, Outside Committee Member; Ben Wang, Committee Member; Chuck Zhang, Committee Member.

Polymer composites are in a period of significant growth due to the increased use in the automobile, marine and aerospace application. Some of the advantages of using composites over other materials are weight savings, corrosion resistance and functional integration. However, long cycle times and higher tooling costs of the available manufacturing processes make it difficult to mass-produce composite products. Resin infusion double flexible tooling (RIDFT) is a novel process developed by the Florida Advanced Center for Composite Technologies (FAC2T) at FAMU-FSU College of Engineering aimed at tackling some of the above-mentioned problems. The use of one-sided mold provides a huge cost advantage over Resin Transfer Molding (RTM). However, using cost effective materials can reduce the cost further. In this thesis research, the various steps involved in the manufacture of the RIDFT mold were identified. The seven steps to manufacture a RIDFT mold are, Initial Graphics Exchange Standard (IGES) file tooling import/repair, mold design, material selection and preparation, NC programming, machine setup, machining and finishing and polishing. The problems at each of these stages were identified. The solutions to some of the problems, which might result in decrease in the tool manufacturing time, were found. To tackle with IGES file import problems some guidelines are presented. The various steps involved in the mold design stage are: compensation of permeable layer thickness, compensation of silicone layer thickness compensation of thickness of part and addition of draft surface. The tooling parameters compensation part of the mold design process was implemented by using both offset and scaling methods using C programming. The materials used for tooling until now are reviewed for pros and cons. Some of the tooling materials, that can be used in future, are also suggested. In order to help the mold manufacturer with the selection of machining parameters a macro was written in Microsoft Excel. Three cases were studied to show how the objectives of thesis are met. / 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 11, 2003. / CAD Errors, RIDFT, NURBS, Mold Design / Includes bibliographical references. / Chuck Zhang, Professor Directing Thesis; Okenwa Okoli, Committee Member; Zhiyong Liang, Committee Member.

Nanomaterials have attracted a great deal of research efforts due to the potential unprecedented properties these materials may provide. Carbon nanotubes (CNTs) are of particular interest because of their exceptional mechanical, thermal and electrical properties. The purpose of this research is to develop poly (methyl methacrylate) (PMMA) carbon nanotubes (CNTs) nanocomposite foams with improved energy dissipation capabilities (toughness). PMMA CNTs nanocomposites were first synthesized by anti-solvent precipitation process (ASP). Nanocomposites with different CNTs concentrations were prepared. The dispersion of the CNTs in the polymer matrix was observed by scanning electron microscopy (SEM). Nanocomposite foams were prepared by a batch process using carbon dioxide as the foaming agent. The foaming was conducted from the retrograde phase that enabled high CO2 solubility and facilitated formation of foams of high bubble density and small bubble size. The effects of foaming temperature, foaming time and CNTs concentration on the foam expansion ratio was investigated. The morphology of the prepared foams was studied by SEM. The compressive properties of the foams were measured and toughness determined. The nanocomposite foams with 0.5% CNT show improvement in energy absorbing capabilities. Upon further increasing CNT concentration, the capability decreases. Further analysis revealed that this was due to the non-uniform foam morphology in those nanocomposite foams. This in turn resulted in from the mixed nucleation mechanisms because of the insufficient CNT dispersion when foamed from the retrograde phase. Enhancement of CNT dispersion in the matrix is needed in order to improve the uniformity of the foams and realize the potential of these materials. / 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. / June 30, 2011. / PMMA Nanocomposite Foams, Compressive Properties, Energy Absorbtion, Multi-walled Carbon Nanotubes / Includes bibliographical references. / Changchun Zeng, Professor Directing Thesis; Okenwa Okoli, Committee Member; Arda Vanli, Committee Member.