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Articles 1 - 30 of 69
Full-Text Articles in Engineering
Highly Conductive Carbon Nanotube Fibers For Biomedical Applications, Vijoya Sa
Highly Conductive Carbon Nanotube Fibers For Biomedical Applications, Vijoya Sa
All Dissertations
We developed a wet spinning process for the formation of polymeric fibers with high loading of single walled carbon nanotubes. The dissertation consists of five chapters. In the first chapter, the research goals were formulated and the art and technologies of fiber spinning from carbon nanotubes were critically analyzed. The next three chapters report the original results. Last chapter summarizes all the findings.
In the second chapter, we describe a surfactant based method of stabilization of carbon nanotube dispersions. The conditions of stability of nanotube dispersions in aqueous solutions of sodium dodecyl sulfate were analyzed. Using surface tension isotherms, the …
Evaluating The Use Of Functional Representations For Ideation In Conceptual Design, Benjamin Caldwell
Evaluating The Use Of Functional Representations For Ideation In Conceptual Design, Benjamin Caldwell
All Dissertations
Functional representations are often used in the conceptual stages of design because they encourage the designer to focus on the intended use and purpose of a system rather than the physical solution. Function models have been proposed by many researchers as a tool to expand the solution search space and guide concept generation, and many design tools have been created to support function-based design. These tools require designers to create function models of new or existing artifacts, but there is limited published research describing what types of functions should be included in a model or the appropriate level of abstraction …
Accelerating Pattern Recognition Algorithms On Parallel Computing Architectures, Kenneth Rice
Accelerating Pattern Recognition Algorithms On Parallel Computing Architectures, Kenneth Rice
All Dissertations
The move to more parallel computing architectures places more responsibility on the programmer to achieve greater performance. The programmer must now have a greater understanding of the underlying architecture and the inherent algorithmic parallelism. Using parallel computing architectures for exploiting algorithmic parallelism can be a complex task. This dissertation demonstrates various techniques for using parallel computing architectures to exploit algorithmic parallelism. Specifically, three pattern recognition (PR) approaches are examined for acceleration across multiple parallel computing architectures, namely field programmable gate arrays (FPGAs) and general purpose graphical processing units (GPGPUs).
Phase-only filter correlation for fingerprint identification was studied as the first …
An Investigation Of The Application Of Phase Change Materials In Practical Thermal Management Systems, David Ewing
An Investigation Of The Application Of Phase Change Materials In Practical Thermal Management Systems, David Ewing
All Dissertations
This work investigates the application of alternative cooling techniques to thermal management. In the first section, this work presents models and extensive simulation studies on an alternative cooling strategy based upon phase change materials (PCMs) for the thermal management system of a LED headlight assembly. These studies have shown that properly chosen PCMs, when suspended in metal foam matrices, increased the thermal conductivity of the PCM. The increased thermal conductivity can enhance the cooling characteristics of a practical thermal management system for a LED headlight system. To further enhance the advantages of using PCMs, nanoparticle enhanced fluids (nanofluids) are desirable …
Automated Digital Machining For Parallel Processors, Joshua Tarbutton
Automated Digital Machining For Parallel Processors, Joshua Tarbutton
All Dissertations
When a process engineer creates a tool path a number of fixed decisions are made that inevitably produce sub-optimal results. This is because it is impossible to process all of the tradeoffs before generating the tool path. The research presents a methodology to support a process engineers attempt to generate optimal tool paths by performing automated digital machining and analysis. This methodology automatically generates and evaluates tool paths based on parallel processing of digital part models and generalized cutting geometry. Digital part models are created by voxelizing STL files and the resulting digital part surfaces are obtained based on casting …
Optimization-Based Power Management Of Hybrid Power Systems With Applications In Advanced Hybrid Electric Vehicles And Wind Farms With Battery Storage, Hoseinali Borhan
Optimization-Based Power Management Of Hybrid Power Systems With Applications In Advanced Hybrid Electric Vehicles And Wind Farms With Battery Storage, Hoseinali Borhan
All Dissertations
Modern hybrid electric vehicles and many stationary renewable power generation systems combine multiple power generating and energy storage devices to achieve an overall system-level efficiency and flexibility which is higher than their individual components. The power or energy management control, ``brain' of these ``hybrid' systems, determines adaptively and based on the power demand the power split between multiple subsystems and plays a critical role in overall system-level efficiency. This dissertation proposes that a receding horizon optimal control (aka Model Predictive Control) approach can be a natural and systematic framework for formulating this type of power management controls. More importantly the …
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
All Dissertations
Both petroleum pitches and pitches derived from pure polycyclic aromatic hydrocarbons (PAHs) are oligomeric materials that can serve as precursors for a wide variety of advanced carbon materials. The goal of this study was the structural characterization and quantitative analysis of the dominant constituent oligomers and species present in these pitches.
A key requirement for such work is the ability to fractionate these complex mixtures into samples of narrow molecular weight distribution (mol wt; MWD) that can be used as standards. To this end, semicontinuous (or semibatch) dense-gas/supercritical extraction (DGE/SCE) was used to produce monomer, dimer, and trimer fractions of …
Development Of A Design Method To Reduce Change Propagation Effects, Prabhu Shankar
Development Of A Design Method To Reduce Change Propagation Effects, Prabhu Shankar
All Dissertations
ABSTRACT
This dissertation presents a design method to reduce engineering changes caused due to change propagation effect. The method helps designers to systematically plan a verification, validation, and test (VV&T) plan. The rationale behind such a method is founded on a well-accepted principle that a robust validation plan can reduce design changes. However, such method has not yet been developed in mechanical engineering domain, so a method from software engineering has been adopted and extended to address the limitations in the existing design evaluation tools.
Tools extensively used in industry, such as FMEA, and in academia have been reviewed to …
Modeling And Synthesis Of Functionalized Meta-Poly(Phenylene Ethynylene) Helical Structures, Ha Nguyen
Modeling And Synthesis Of Functionalized Meta-Poly(Phenylene Ethynylene) Helical Structures, Ha Nguyen
All Dissertations
The ability of meta-poly(phenylene ethynylene) (mPPE) materials to undergo random coil to helix conformational changes under select conditions affords many opportunities for their use in sensor, separation, catalysis, and bio-related applications. Thus, to advance the development of these materials, a modeling procedure based on replica exchange molecular dynamics (REMD) simulation was developed to reliably assess factors affecting the folding behaviors of functionalized mPPE variants in solution. A combinational modeling study of 20 functionalized mPPEs in five solvent conditions provided insight into how mPPE secondary structure is impacted by the complex relationship between mPPE functional groups and solvent moieties. Further, these …
Probabilistic Approaches To Stability And Deformation Problems In Braced Excavation, Zhe Luo
Probabilistic Approaches To Stability And Deformation Problems In Braced Excavation, Zhe Luo
All Dissertations
This dissertation is aimed at applying probabilistic approaches to evaluating the basal-heave stability and the excavation-induced wall and ground movements for serviceability assessment of excavation in clays. The focuses herein are the influence of spatial variability of soil parameters and small sample size on the results of the probabilistic analysis, and Bayesian updating of soil parameters using field observations in braced excavations.
Simplified approaches for reliability analysis of basal-heave in a braced excavation in clay considering the effect of spatial variability in random fields are presented. The proposed approaches employ the variance reduction technique (or more precisely, equivalent variance method) …
Fabrication Of Grooved Hollow Fiber Membrane For Nerve Regeneration: Process Modeling And Performance Evaluation, Jun Yin
All Dissertations
Nerve injury is a general but intractable disease in traumatic injuries, leading to a significant reduction of functions in the nervous system. Extensive efforts are made on nerve injury rehabilitation. Since the appropriate connections between neurons and their targets are necessary, guiding axonal outgrowth is an essential step for neuron outgrowth in nervous system development, functioning, and regeneration. Besides the direct surgical nerve connection, an artificial means of guiding nerve regeneration called nerve conduits is widely applied in nerve injury rehabilitation. The main function of nerve conduits is to bridge the nerve gap, to help regenerating axons across damaged regions …
Spectral Engineering Of Optical Fiber Through Active Nanoparticle Doping, Tiffany Lindstrom-James
Spectral Engineering Of Optical Fiber Through Active Nanoparticle Doping, Tiffany Lindstrom-James
All Dissertations
The spectral engineering of optical fiber is a method of intentional doping of the core region in order to absorb/emit specific wavelengths of light therby providing enhanced performance over current fibers. Efforts here focused on developing an understanding of optically active nanoparticles based on alkaline earth fluorides that could be easily and homogeneously incorporated into the core of a silica based optical fiber preform and result in efficient and tailorable spectral emissions.
Doped and undoped calcium, strontium and barium fluoride nanoparticles were successfully synthesized and characterized for their physical, chemical, and optical behavior. Distinct spectroscopic differences as a result of …
Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp
Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp
All Dissertations
Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available.
In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M–50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order …
Performance Analysis And Fitness Of Gpgpu And Multicore Architectures For Scientific Applications, Mohammad Bhuiyan
Performance Analysis And Fitness Of Gpgpu And Multicore Architectures For Scientific Applications, Mohammad Bhuiyan
All Dissertations
Recent trends in computing architecture development have focused on exploiting task- and data-level parallelism from applications. Major hardware vendors are experimenting with novel parallel architectures, such as the Many Integrated Core (MIC) from Intel that integrates 50 or more x86 processors on a single chip, the Accelerated Processing Unit from AMD that integrates a multicore x86 processor with a graphical processing unit (GPU), and many other initiatives from other hardware vendors that are underway.
Therefore, various types of architectures are available to developers for accelerating an application. A performance model that predicts the suitability of the architecture for accelerating an …
Interfacial Force Field Parameterization Using The Dual Force Field Charmm Program For The Accurate Simulation Of Peptide-Surface Interaction, Nadeem Vellore
Interfacial Force Field Parameterization Using The Dual Force Field Charmm Program For The Accurate Simulation Of Peptide-Surface Interaction, Nadeem Vellore
All Dissertations
Protein adsorption to solid material surfaces is a complex phenomenon and various factors play a role in controlling these processes. Inherent limitations to understand these biological interactions using experimental approaches alone have led to the possibility of exploring these systems using computational molecular simulation methodologies. Before confidence can be placed on these computational protocols, however, rigorous validation of the applicability of these methods to accurately represent protein adsorption processes is needed. In this research, we evaluated the use of all-atom empirical force field (FF) based simulations using the CHARMM simulation program and FF for the study of peptide adsorption processes …
A Formal Representation Of Mechanical Functions To Support Physics-Based Computational Reasoning In Early Mechanical Design, Chiradeep Sen
A Formal Representation Of Mechanical Functions To Support Physics-Based Computational Reasoning In Early Mechanical Design, Chiradeep Sen
All Dissertations
The lack of computational support to the conceptual phase of mechanical engineering design is well recognized. Function-based modeling and thinking is widely recommended in design texts as useful means for describing design concepts and using them in tasks such as solution search, problem decomposition, and design archival. Graph-based function structure models that describe a product as a network of transformative actions of material, energy, and information, are discussed as a potential tool for this purpose, but in the current state of the art, function structures are not formalized as a computational representation. Consequently, no computer tool exists with which a …
Fluid Mud Underflows In Coastal Dredge Disposal, Mijanur Chowdhury
Fluid Mud Underflows In Coastal Dredge Disposal, Mijanur Chowdhury
All Dissertations
This manuscript presents the results of a thorough theoretical and experimental investigation on fluid mud underflows generated in a typical coastal dredge disposal operation. The main goal of this investigation is to understand the propagation dynamics of fluid mud underflows that depends upon a number of factors, including: concentrations, rheological properties and released configurations of fluid mud. Laboratory experiments were conducted with different initial fluid mud concentrations in three different experimental set-ups: rectangular flume for constant volume release, rectangular flume for constant flux release, and a square pool for radial constant flux release of fluid mud. The experiments in the …
Development Of A Dynamic In Vitro Model Of A Stented Blood Vessel To Evaluate The Effects Of Stent Strut Material Selection And Surface Coating On Smooth Muscle Cell Response, Bradley Winn
All Dissertations
Cardiovascular disease is the leading cause of mortality in The United States and Europe, accounting for approximately half of all deaths. The most common form of cardiovascular disease is atherosclerosis, which is characterized by the formation of fatty atheromatous plaques that can grow to occlude the vessel lumen, thus causing ischemia distal to the occlusion. This is commonly treated using balloon angioplasty, which is usually done in conjunction with the deployment of a stent. Stent deployment helps hold the vessel open following the local injury caused by balloon inflation and prevents elastic recoil and subsequent negative remodeling. Stenting has been …
Electrical Coupling Between Micropatterned Cardiomyocytes And Stem Cells, Zhen Ma
Electrical Coupling Between Micropatterned Cardiomyocytes And Stem Cells, Zhen Ma
All Dissertations
To understand how stem cells functionally couple with native cardiomyocytes is crucial for cell-based therapies to restore the loss of cardiomyocytes that occurs during heart infarction and other cardiac diseases. Due to the complexity of the in vivo environment, our knowledge of cell coupling is heavily dependent on cell-culture models. However, conventional in vitro studies involve undefined cell shapes and random length of cell-cell contacts in addition to the presence of multiple homotypic and heterotypic contacts between interacting cells. Thus, it has not been feasible to study electrical coupling corresponding to isolated specific types of cell contact modes.
To address …
Analyzing Of Tort Claims And Lawsuits Against South Carolina Department Of Transportation Through Classification And Regression Tree Analysis, Sara Familian
All Dissertations
After losing sovereign immunity in 1985, SCDOT employees now focus a significant amount of time in processing tort claims and lawsuits filed against the agency. This is an important issue for transportation agencies considering the fact that money spent defending tort claims and lawsuits, is no longer available for safety and mobility improvements on the state highway system.
The South Carolina Department of Transportation (SCDOT) processes approximately one thousand claims per year and is engaged in nearly one hundred lawsuits per year. SCDOT has paid just over a half million ($523,607) to settle on 1007 claims - approximately 1/3 of …
Influence Of Warm Mix Additives Upon High Rap Asphalt Mixes, William Rogers
Influence Of Warm Mix Additives Upon High Rap Asphalt Mixes, William Rogers
All Dissertations
This study was conducted to determine the effect of warm mix (WMA) modifiers on asphalt mixes containing high percentages of reclaimed asphalt pavement (RAP). Mixes were created using three aggregate sources, four RAP percentages (0%, 20%, 35%, and 50%), and three warm mix modifiers (HMA, zeolite, and Sasobit®). Base binders from the same source (PG 64 -22, 58 -28, 52 -28) and one rejuvenator were used for each mix to ensure the final blended binder grade was at least PG 64 -10.
Specimens were created at HMA or suggested WMA temperatures and tested for rut depth, indirect tensile strength (ITS), …
Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson
Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson
All Dissertations
Polymeric optical materials generally are comprised of amorphous polymers that are transparent in at visible wavelengths but exhibit strong absorption bands in the near-infrared making them less useful for many optical applications. Attenuation, which is the absorption per unit length, largely results from the high vibrational energy associated with carbon-hydrogen bonds contained in the polymer backbone. Attenuation can be mitigated by optical amplification utilizing light emitting additives. Investigated in this dissertation are synthesis techniques for the fabrication of light-emitting polymer nanocomposites and their resultant thermal and rheological characteristics for potential use as polymer optical fibers or films.
Inorganic nanocrystals doped …
Effect Of Relative Humidity And Temperature Control On In-Cabin Thermal Comfort State, Ali Alahmer
Effect Of Relative Humidity And Temperature Control On In-Cabin Thermal Comfort State, Ali Alahmer
All Dissertations
This dissertation discusses the effect of manipulating the relative humidity RH levels inside vehicular cabins on the thermal comfort and human occupants' thermal sensation. Three different techniques are used to investigate this effect. Firstly, thermodynamic and psychometric analyses are used to incorporate the effect of changing RH along with the dry bulb temperature on the human comfort window. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. …
Radio Frequency Micro/Nano-Fluidic Devices For Microwave Dielectric Property Characterizations, Chunrong Song
Radio Frequency Micro/Nano-Fluidic Devices For Microwave Dielectric Property Characterizations, Chunrong Song
All Dissertations
In this dissertation, a number of different topics in microwave dielectric property measurements have been covered by a systematic approach to the goals of development of dielectric spectroscopy and study of its high electric field effects with integrated on-chip microwave microfluidic / nanofluidic devices.
A method of parasitic effects cancellation for dielectric property measurement is proposed, analyzed, and experimentally evaluated for microwave characterization of small devices and materials that yield low intensity signals. The method dramatically reduces parasitic effects to uncover the otherwise buried signals. A high-sensitive radio frequency (RF) device is then developed and fabricated to detect small dielectric …
Characterizing Mechanical Heterogeneity In Cardiovascular Cells, Sandra Deitch
Characterizing Mechanical Heterogeneity In Cardiovascular Cells, Sandra Deitch
All Dissertations
Most tissue-level mechanical models assume homogeneous mechanical properties within a single cell type. However, measurements of cellular mechanical properties show large variability in whole-cell mechanical properties between cells from a single population. This heterogeneity has been observed in many cell populations and with several measurement techniques but the sources are not yet fully understood. Cell mechanical properties are directly related to the composition and organization of the cytoskeleton, which is physically coupled to neighboring cells through adherens junctions and to underlying matrix scaffolds through focal adhesion complexes. As such, we believe that this high level of heterogeneity can be attributed …
Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere
Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere
All Dissertations
High strength aluminum alloys with superior blast/ballistic resistance against armor piercing (AP) threats and with high vehicle light-weighing potential are being increasingly used as military-vehicle armor. Due to the complex structure of these vehicles, they are commonly constructed through joining (mainly welding) of the individual components. Unfortunately, these alloys are not very amenable to conventional fusion based welding technologies (e.g. Gas Metal Arc Welding (GMAW)) and in-order to obtain high-quality welds, solid-state joining technologies such as Friction Stir Welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced …
The Effects Of Fundamental Mixture Parameters On Hot-Mix Asphalt Performance Properties, Wenbin Zhao
The Effects Of Fundamental Mixture Parameters On Hot-Mix Asphalt Performance Properties, Wenbin Zhao
All Dissertations
Asphalt pavements are composed of three components: aggregate, asphalt binder, and air. In the process of plant production and on-site construction, the construction quality can vary in the three component and the variability can further affect a pavement's future performance.. This research identifies aggregate gradation, binder content, and air voids content as the fundamental parameters. Understanding the fundamental parameters' influence on the HMA mixture's performance properties can provide valuable information on how to improve the current quality insurance practice. The objective of this study is to conduct well-controlled experiments to investigate how mix gradation, air voids and small range binder …
Social Sustainability Considerations During Planning And Design: A Framework Of Processes For Construction Projects, Rodolfo Valdes Vasquez
Social Sustainability Considerations During Planning And Design: A Framework Of Processes For Construction Projects, Rodolfo Valdes Vasquez
All Dissertations
With increased awareness of issues such as global resource shortages and climate change, sustainability efforts are becoming more common in the construction industry. While these efforts often consider economic and environmental factors, a truly sustainable construction project also needs to include such social considerations as its impact on the surrounding community and the safety, health, and education of the workforce. For the construction industry, social sustainability requires integrating processes for improving safety, health and well-being over the project life cycle. However, an empirical and comprehensive framework defining these social sustainability processes in construction projects has yet to be clearly delineated. …
Metaheuristics For Hub Location Models, Ornurai Sangsawang
Metaheuristics For Hub Location Models, Ornurai Sangsawang
All Dissertations
In this research, we propose metaheuristics for solving two p-hub median problems.. The first p-hub median problem, which is NP-hard, is the uncapacitated single p-hub median problem (USApHMP). In this problem, metaheuristics such as genetic algorithms, simulated annealing and tabu search, are applied in different types of representations. Caching is also
applied to speed up computational time of the algorithms. The results clearly demonstrate that tabu search with a permutation solution representation, augmented with caching is the highest performing method, both in terms of solution quality and computational time among these algorithms for the USApHMP. We also investigate the performance …
Contaminant Mass Transfer During Boiling In Fractured Geologic Media, Fei Chen
Contaminant Mass Transfer During Boiling In Fractured Geologic Media, Fei Chen
All Dissertations
Remediation of fractured geologic media contaminated with chlorinated volatile organic compounds that diffuse into the matrix is challenging using isothermal methods. Due to the low permeability of the matrix material and uncertainty of fracture networks, it is difficult to flush the system with any type of fluid or deliver remediation agents into the matrix. However, thermal methods have some promises. When the matrix is heated above water boiling temperature, depressurization in the fractures may trigger water boiling in the matrix, which, as a result, generates a large volumetric steam flow toward adjacent fractures, stripping the adsorbed or dissolved volatile contaminants …