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Articles 1741 - 1770 of 2584

Full-Text Articles in Engineering

Effects Of Different Microenvironmental Conditions On The Growth And Differentiation Of Dental Pulp Stem Cells, Matthew Cupelli May 2012

Effects Of Different Microenvironmental Conditions On The Growth And Differentiation Of Dental Pulp Stem Cells, Matthew Cupelli

All Theses

Human teeth are very complex structures that are susceptible to many different pathologies due to poor dental health. Currently, there are many restorative methods to reestablish some of the function that teeth have, but the materials used in these methods all have drawbacks and cannot fully mimic the native teeth. Tissue engineering research groups have begun to explore regenerating bone or dental tissue using mesenchymal stem cells derived from the bone marrow. However, our group focuses on regenerating dental tissues using multipotent stem cells from dental pulp.
Dental pulp stem cells (DPSCs) have shown similarities to bone marrow stem cells …

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Development And Calibration Of Central Pressure Filling Rate Models For Hurricane Simulation, Fangqian Liu May 2012

Development And Calibration Of Central Pressure Filling Rate Models For Hurricane Simulation, Fangqian Liu

All Theses

This study presents the development of a new central pressure filling rate model to characterize the rate at which hurricanes or tropical storms decay after landfall. It has been shown that the post landfall decay rate of hurricanes is closely related to the time after landfall, the size of hurricane and proximity of the hurricane eye to the coastline. In addition, it has been observed that the decay rates of hurricanes are geographically dependent. Based on these observations, a set of simple empirical models expressed in
terms of exponential and linear equations are utilized to characterize the decay rate of …

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Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak May 2012

Nanoparticles In Solution-Derived Chalcogenide Glass Films, Spencer Novak

All Theses

The results in this thesis are from our efforts to modify the optical properties of solution-derived chalcogenide glass films by the incorporation of nanomaterials. First, the composition Ge23Sb7S70 was selected as the appropriate glass matrix for testing because solution-derived films of this composition have been well-studied in our group. Additionally, this composition was found to be less sensitive to certain processing parameters than As2S3, another well-studied, candidate chalcogenide glass composition, making Ge23Sb7S70 more suitable for the addition of nanomaterials. Optimization of film process parameters was performed to obtain high-quality films appropriate for doping with nanomaterials. This consisted of determining the …

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Qualified Affordance-Based Design, Jun Hu May 2012

Qualified Affordance-Based Design, Jun Hu

All Theses

Function-based approaches are taught by the engineering design community and implemented in practice. The most significant advantage of these approaches is that they can guide the designers to abstract the essential problems from the design requirements, build the function-based models, and consequently provide the direction of the solution. However, due to the lack of a consistent scientific definition on the meaning of the function, these approaches may be contradictory when representing human-centered aspects, features, and non-physical purposes. To address this issue, design researchers have pursued two general directions: (1) broadening the meaning of function and (2) introducing an alternative scientific …

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A Case Study In Challenging And Validating Engineering Requirements With Value-Based Techniques, Seth Crouch May 2012

A Case Study In Challenging And Validating Engineering Requirements With Value-Based Techniques, Seth Crouch

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Requirements are an essential element to engineering design as they are used to focus idea generation during conceptual design, provide criteria for decision making during concept selection, and verify the chosen concept fulfills product needs. Because they are essential to the entire design process, great emphasis needs to be put on ensuring that they are correct. This research focuses on a value-based methodology useful for challenging and validating established requirements. A case study was conducted using this process on a project involving the design of a vehicle seat. This case study shows that this approach provides more persuasive evidence to …

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Remote Detection Of Ephemeral Wetlands In Mid- Atlantic Coastal Plain Ecoregions: Lidar And High-Throughput Computing, Paul Leonard May 2012

Remote Detection Of Ephemeral Wetlands In Mid- Atlantic Coastal Plain Ecoregions: Lidar And High-Throughput Computing, Paul Leonard

All Theses

Ephemeral wetlands are ecologically important freshwater ecosystems that occur frequently throughout the Atlantic coastal plain ecoregions of North America. Despite the growing consensus of their importance and imperilment, these systems historically have not been a national conservation priority. They are often cryptic on the landscape and methods to detect ephemeral wetlands remotely have been ineffective at the landscape scales necessary for conservation planning and resource management. Therefore, this study fills information gaps by employing high-resolution light detection and ranging (LiDAR) data to create local relief models that elucidate small localized changes in concavity. Relief models were then processed with local …

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Assessment Of A Safe Driving Program For Novice Drivers And Smart Jersey Barrier Design To Minimize Animal-To-Vehicle Collisions, Lance Clark May 2012

Assessment Of A Safe Driving Program For Novice Drivers And Smart Jersey Barrier Design To Minimize Animal-To-Vehicle Collisions, Lance Clark

All Theses

Each year, the total number of vehicles, motorists, highway infrastructures, and distance traveled by drivers increases on a global basis. This rise in personal and commercial ground vehicle usage brings with it the advantages of the modern age, but it is not without societal cost. Vehicular incidents result in tens of thousands of deaths each year in the United States alone. For this reason, research has been performed to advance driver safety while simultaneously providing wildlife with means to avoid animal-to-vehicle collisions (AVC). In this thesis, two solutions are proposed: a driver education program with classroom experiences, in-vehicle resources, and …

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Evaluation Of A Bisphosphonate Enriched Ultra-High Molecular Weight Polyethylene For Enhanced Total Joint Replacement Bearing Surface Functionality, Cassandra Wright-Walker May 2012

Evaluation Of A Bisphosphonate Enriched Ultra-High Molecular Weight Polyethylene For Enhanced Total Joint Replacement Bearing Surface Functionality, Cassandra Wright-Walker

All Dissertations

Each year in the United States there is an increasing trend of patients receiving total joint replacement (TJR) procedures. Approximately a half million total knee replacements (TKRs) are performed annually in the United States with increasing prevalence attributed to baby-boomers, obesity, older, and younger patients. This trend is also seen for total hip replacements (THRs) as well. The use of ultra high molecular weight polyethylene (UHMWPE) inserts in TJRs results in wear particle-induced osteolysis, which is the predominant cause for prosthesis failure and revision surgery. Sub-micron size particle generation is inevitable despite the numerous efforts in improving this bearing material. …

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Applying Chaotic Advection To Rheology: An In Situ Structuring Rheometer, Ramaswami Subrahmanian May 2012

Applying Chaotic Advection To Rheology: An In Situ Structuring Rheometer, Ramaswami Subrahmanian

All Dissertations

A prototype In Situ Structuring Rheometer (ISSR) was designed and implemented to study changes in shear viscosity of polymer blends and composites while processing them in such a way as to control the evolution of microstructure. The ISSR is based on a regime of fluid mechanics known as chaotic advection, in which simple time-periodic flow fields can cause fluid particles to move chaotically. Chaotic advection is also the basis of Smart Blending, a technology employed to process polymer blends having a variety of morphologies at a fixed composition, and polymer composites in which the additives have been arranged into layered …

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Computational Representation And Reasoning Support For Requirements Change Management In Complex System Design, Beshoy Morkos May 2012

Computational Representation And Reasoning Support For Requirements Change Management In Complex System Design, Beshoy Morkos

All Dissertations

Requirements play a critical role within any design process and the activity of identifying and maintaining a system's requirements is essential to. However, design is a complex and iterative process, where requirements are continuously evolving and are volatile. This change, if not managed, may result in undesired uncertainty within the design process leading to monetary losses and time delays, as the changing of requirements has been recognized as a major cause of project failure. In order to mitigate issues that arise due to requirement change propagation, this research presents a computational reasoning tool to help designers and engineers predict change …

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Assessing Ongoing Sources And Fate Of Dissolved Polychlorinated Biphenyls (Pcbs) In A Stream, Viet Dang May 2012

Assessing Ongoing Sources And Fate Of Dissolved Polychlorinated Biphenyls (Pcbs) In A Stream, Viet Dang

All Dissertations

Polychlorinated biphenyls (pcbs) contamination remains a concern due to their persistence and the risk to human health associated with them. Once released into the environment, these substances are mainly associated with sediment particles and sediment organic carbon matter. They bioaccumulate in organisms via contaminated food and only a small faction is desorbed from sediment into the water column. Given the discontinuity of active discharge, pcbs are currently entering the water via groundwater inputs, soil erosion, and/or ongoing leakage from the point source. It is the dissolved form that 1) can be either absorbed by biofilm attached to stream leaves, which …

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Expert System Based Approach For Material Selection Of Automobile Body-In-White Structural Panels Using Numerical Ranking And Sustainability Indices, Ahmad Mayyas May 2012

Expert System Based Approach For Material Selection Of Automobile Body-In-White Structural Panels Using Numerical Ranking And Sustainability Indices, Ahmad Mayyas

All Dissertations

The goal of this work is to establish a set of quantifiable measures for design for sustainability (DFS) that can be applied to automotive applications in terms of environmental, social, economic and technical aspects. In this study, a comprehensive analysis was made in order to develop a methodology that can evaluate different body-in-white designs in terms of major sustainability aspects. Besides the complete life cycle analysis, environmental impacts and cost factors will be analyzed over vehicle's entire life-cycle (fuel extraction and refining, Pre-manufacturing, Manufacturing, Use, and
Post-use stages). The considered material options include: conventional steel, high strength steel, aluminum, magnesium, …

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Flushing Of A Dense Fluid From An Isolated Urban Canyon, Zahra Baratian-Ghorghi May 2012

Flushing Of A Dense Fluid From An Isolated Urban Canyon, Zahra Baratian-Ghorghi

All Dissertations

The mechanics of shear-driven flushing of a dense fluid from a canyon is investigated through a series of laboratory experiments. Such a flow has many environmental applications including the removal of dense pollutants trapped in urban canyons and the purging of salt water from bed depressions at river mouths. While there is an extensive literature on flow in canyons and cavities for the neutrally buoyant case, the problem of flushing a dense fluid from canyon has received considerably less attention. To understand the dynamics of the mixing and to quantify the buoyant contaminant flushing rate, a broad range of experimental …

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Glottal Excitation Extraction Of Voiced Speech - Jointly Parametric And Nonparametric Approaches, Yiqiao Chen May 2012

Glottal Excitation Extraction Of Voiced Speech - Jointly Parametric And Nonparametric Approaches, Yiqiao Chen

All Dissertations

The goal of this dissertation is to develop methods to recover glottal flow pulses, which contain biometrical information about the speaker. The excitation information estimated from an observed speech utterance is modeled as the source of an inverse problem.
Windowed linear prediction analysis and inverse filtering are first used to deconvolve the speech signal to obtain a rough estimate of glottal flow pulses. Linear prediction and its inverse filtering can largely eliminate the vocal-tract response which is usually modeled as infinite impulse response filter. Some remaining vocal-tract components that reside in the estimate after inverse filtering are next removed by …

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Design Of Meta-Materials Outside The Homogenization Limit Using Multiscale Analysis And Topology Optimization, Christopher Czech May 2012

Design Of Meta-Materials Outside The Homogenization Limit Using Multiscale Analysis And Topology Optimization, Christopher Czech

All Dissertations

The field of meta-materials engineering has largely expanded mechanical design possibilities over the last two decades; some notable design advances include the systematic engineering of negative Poisson's ratio materials and functionally graded materials, materials designed for optimal electronic and thermo-mechanical performances, and the design of materials under uncertainty. With these innovations, the systematic engineering of materials for design-specific uses is becoming more common in industrial and military uses. The motivation for this body of research is the design of the shear beam for a non-pneumatic wheel. Previously, a design optimization of a finite element model of the non-pneumatic wheel was …

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A Study Of Environment Noise In Ultra-Wideband Indoor Position Tracking, William Suski May 2012

A Study Of Environment Noise In Ultra-Wideband Indoor Position Tracking, William Suski

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This work is motivated by the problem of improving the accuracy of indoor ultra-wideband (UWB) position tracking through the study of the environment noise that affects such a system. Current systems can provide accuracy in the range of 30-100 cm in a small building, suitable for applications that require rough room-level precision such as asset tracking and surveillance. Our long-term goal is to improve the accuracy to 1 cm or better, expanding potential applications to telepresence, augmented reality, training and entertainment.
This work investigates the possibility of systematically observing the measurement noise of an UWB position tracking system and building …

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Quantitative, Spatial Imaging Based Measurements To Assess Cellular Health And Oxygenation In A Tissue Engineered Test System, Erik Bland May 2012

Quantitative, Spatial Imaging Based Measurements To Assess Cellular Health And Oxygenation In A Tissue Engineered Test System, Erik Bland

All Dissertations

Three-dimensional in vitro tissue test systems are employed to examine cell behavior, test responses to drugs and vaccines, and answer basic biological questions. These systems are more physiologically relevant than two-dimensional cell cultures, and are more relevant, easier and less expensive to maintain than animal models. However, methods used to measure cell behavior and viability have been developed specifically for two-dimensional cell cultures or animal models, and are often not optimally translated to three-dimensional in vitro test systems. The purpose of this work was to aid in the development of three-dimensional, spatially controlled in vitro test systems, and to develop …

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Grain Boundaries Structures And Wetting In Doped Silicon, Nickel And Copper, Kaveh Meshinchi Asl May 2012

Grain Boundaries Structures And Wetting In Doped Silicon, Nickel And Copper, Kaveh Meshinchi Asl

All Dissertations

This thesis reports a series of fundamental investigations of grain boundary wetting, adsorption and structural (phases) transitions in doped Ni, Cu and Si with technological relevance to liquid metal embrittlement, liquid metal corrosion and device applications. First, intrinsically ductile metals are prone to catastrophic failure when exposed to certain liquid metals, but the atomic level mechanism for this effect is not fully understood. A nickel sample infused with bismuth atoms was characterized and a bilayer interfacial phase that is the underlying cause of embrittlement was observed. In a second related study, we showed that addition of minor impurities can significantly …

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First Generation College Students In Engineering: A Grounded Theory Study Of Family Influence On Academic Decision Making, Denise Simmons May 2012

First Generation College Students In Engineering: A Grounded Theory Study Of Family Influence On Academic Decision Making, Denise Simmons

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This work develops a constructivist grounded theory describing the influence of family and those that serve a role similar to family on the academic decision making of undergraduate first generation in college (FGC) students majoring in engineering. FGC students, in this study, are students with neither parent having attained a bachelor's degree.
FGC students are an untapped talent pool with the potential to diversify and increase the number of engineers, which are both urgent national priorities. Much is known about FGC students with respect to their academic preparation, transition to postsecondary education, and progress toward degree attainment. However, the literature …

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Algebraic Approaches To Stochastic Optimization, Katherine Hastings May 2012

Algebraic Approaches To Stochastic Optimization, Katherine Hastings

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The dissertation presents algebraic approaches to the shortest path and maximum flow problems in stochastic networks. The goal of the stochastic shortest path problem is to find the distribution of the shortest path length, while the goal of the stochastic maximum flow problem is to find the distribution of the maximum flow value. In stochastic networks it is common to model arc values (lengths, capacities) as random variables. In this dissertation, we model arc values with discrete non-negative random variables and shows how each arc value can be represented as a polynomial. We then define two algebraic operations and use …

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Further Investigation On Magnetically Induced Subsequent Fault And Study On Electromagnetic Scattering Of Objects Buried Below A Random Rough Surface, Haiyan Yang May 2012

Further Investigation On Magnetically Induced Subsequent Fault And Study On Electromagnetic Scattering Of Objects Buried Below A Random Rough Surface, Haiyan Yang

All Dissertations

This dissertation contains two subjects: further development of numerical
technique for the analysis of magnetically induced subsequent fault (MISFault) in overhead power lines and its implementation into a software upgrade; and first-phase of study on the electromagnetic scattering from objects buried below a random rough surface making use of the multidomain pseudospectral time domain (PSTD) method and Monte-Carlo simulation. An initial electric fault can result in strong magnetic torque on the overhead power line conductors, which will make them swing and may bring them to close proximity or in contact with one another, causing a subsequent fault. In Chapter 2, …

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Assembly And Disassembly Of Myofibrils In Dissociated Cardiomyocytes, Honghai Liu May 2012

Assembly And Disassembly Of Myofibrils In Dissociated Cardiomyocytes, Honghai Liu

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Significance
1) We have developed a hybrid TPEF-SHG imaging system with an onstage incubator for long-term living-cell imaging. Using the imaging system, the assembly of myosin filaments onto the myofibrils can be investigated without fluorescently labeling the specific proteins, which enabled us to study the dynamic process of the assembly and dedifferentiation of myofibrils in living cardiomyocytes without labeling any sarcomeric proteins for long time.
2) We observed the addition of new sarcomeres during myofibrillogenesis while neonatal cardiomyocytes were spreading on the substrate for up to 10 hours under the customized TPEF-SHG imaging system. New-sarcomere addition at both the ends …

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Surface Damage In Retrieved Total Knee Replacement Femoral Components, Estefania Alvarez May 2012

Surface Damage In Retrieved Total Knee Replacement Femoral Components, Estefania Alvarez

All Dissertations

The metallic femoral components of total knee replacements are subject to in vivo surface damage and roughening that can severely limit the service lifetime of the bearing system. To date, there are no national standards by which to characterize the severity and damage modes of these critical bearing surfaces, and therefore it remains difficult to accurately assess how femoral damage influences total joint replacement bearing longevity. In vitro and in vivo studies have shown that severe surface damage of the femoral component can occur, however, there is still no defined test methodology that can identify or replicate the types of …

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A Comprehensive Human Factors Analysis Of Off-Duty Motor Vehicle Crashes In The United States Military, Rebecca Iden May 2012

A Comprehensive Human Factors Analysis Of Off-Duty Motor Vehicle Crashes In The United States Military, Rebecca Iden

All Dissertations

Researchers have always had great interest in traffic safety and the phenomenon of motor vehicle crashes (MVCs). Though scores of service members are severely injured or killed in off-duty MVCs each year, few studies have addressed the MVC phenomenon within the military population and none have conducted a comprehensive evaluation of the causal factors associated with MVCs involving military personnel.
The main purpose of this dissertation was to gain a greater understanding of the causal factors associated with serious and fatal off-duty personal MVCs for military service members with the ultimate goal of preventing future losses. The HFACS-MVC framework was …

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Compressive Strength Of Continuous Fiber Unidirectional Composites, Ronald Thompson May 2012

Compressive Strength Of Continuous Fiber Unidirectional Composites, Ronald Thompson

All Dissertations

Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. …

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Nanopillar Based Electrochemical Biosensor For Monitoring Microfluidic Based Cell Culture, Rajan Gangadharan May 2012

Nanopillar Based Electrochemical Biosensor For Monitoring Microfluidic Based Cell Culture, Rajan Gangadharan

All Dissertations

In-vitro assays using cultured cells have been widely performed for studying many aspects of cell biology and cell physiology. These assays also form the basis of cell based sensing. Presently, analysis procedures on cell cultures are done using techniques that are not integrated with the cell culture system. This approach makes continuous and real-time in-vitro measurements difficult. It is well known that the availability of continuous online measurements for extended periods of time will help provide a better understanding and will give better insight into cell physiological events.
With this motivation we developed a highly sensitive, selective and stable microfluidic …

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Reasons For Change Propagation: A Case Study In An Automotive Oem, Prabhu Shankar, Beshoy Morkos, Joshua D. Summers Apr 2012

Reasons For Change Propagation: A Case Study In An Automotive Oem, Prabhu Shankar, Beshoy Morkos, Joshua D. Summers

All CEDAR Publications

This paper focuses on identifying the reasons for change propagation during the production phase of the product life cycle. Unlike the traditional change propagation study where the focus is within the product, this study is focused to understand the propagation effects of change on other functional silos in the manufacturing firm. First, the reasons for the changes are identified using archival analysis through which it is found that 77.0 % of changes are due to internal reasons while 23.0 % are external. Second, these changes are distinguished into genesis, and propagated changes using a matrix-based modeling approach from which the …

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Predicting Requirement Change Propagation Using Higher Order Design Structure Matrices: An Industry Case Study, Beshoy Morkos, Prabhu Shankar, Joshua D. Summers Feb 2012

Predicting Requirement Change Propagation Using Higher Order Design Structure Matrices: An Industry Case Study, Beshoy Morkos, Prabhu Shankar, Joshua D. Summers

All CEDAR Publications

This research examines higher order design structure matrices as requirements change modelling tools to predict requirement change propagation through two large-scale industry design projects. Due to the iterative nature of design, requirements will evolve and change. Changes in requirements can propagate to other requirements on different subsystems leading to possible increases in the project cost and lead-time. Predicting these requirement changes enables the designers to foresee unanticipated changes and maximises the probability for the project's success. These studies reveal that second-order relationships are influential in predicting requirement change propagation. Unforeseen propagation occurring in first-order form was rare, rather it was …

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Dynamic Endothelialization Of Aortic Heart Valve Scaffolds, Richard Pascal Jan 2012

Dynamic Endothelialization Of Aortic Heart Valve Scaffolds, Richard Pascal

All Theses

Cardiovascular disease is the number one killer worldwide affecting both the heart and blood vessels. Valvular heart disease can arise from calcification, and structural deterioration resulting in a stenotic or regurgitant valve incapable of proper function. With approximately 275,000 valve replacements performed annually worldwide, the need for replacement heart valves is well established. Currently, treatment of valvular heart disease is limited to two options (mechanical and bioprosthetic). Both replacement valves have their own drawbacks, which have driven research in the bioengineering field to focus on the development of a tissue engineered heart valve (TEHV) capable of growth and self-repair.
A …

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Manufacturing Process Modeling And Application To Intelligent Control, M. Laine Mears, Parakshit Mehta, Mathew Kuttolamadom, Carlos Montes, Joshua Jones, Wesley Salandro, Drew Werner Jan 2012

Manufacturing Process Modeling And Application To Intelligent Control, M. Laine Mears, Parakshit Mehta, Mathew Kuttolamadom, Carlos Montes, Joshua Jones, Wesley Salandro, Drew Werner

Publications

This paper reviews the major findings and intellectual contributions made over the past five years through research in the laboratory of Dr. Laine Mears at Clemson University. The focus of the laboratory’s work is in modeling of traditional and novel manufacturing processes, and application of such models to process control through model-based control strategies. Introducing intelligence to the manufacturing process through physical descriptions of the phenomena being controlled allows for more precise control as compared with reactive systems or those with simple feed-forward control schemes. For traditional processes, new approaches to process characterization allow for more precise control. For novel …

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