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Articles 31 - 45 of 45
Full-Text Articles in Engineering
The Differential Effects Of Two Critical Osteoclastogenesis Stimulating Factors On Bone Biomechanics, Yuyu Yuan
The Differential Effects Of Two Critical Osteoclastogenesis Stimulating Factors On Bone Biomechanics, Yuyu Yuan
All Dissertations
Many skeletal diseases, such as osteoporosis and malignant bone metastases, are generally osteolytic and associated with increased bone resorption and decreased bone strength. Within a complex cytokine environment, the proteins RANKL and M-CSF are critical for osteoclast differentiation and activation, and thus fundamental effectors of osteolytic disorders. Previous studies showed that M-CSF stimulates the proliferation and early differentiation of osteoclast progenitors to osteoclast lineage, while RANKL targets the later stages of fusion and activation, and stimulates the formation of functional active osteoclasts. However, impacts of artificially elevated levels of these proteins on the skeleton system have not been fully characterized. …
Numerical And Physical Modeling Of Turbulent Shear Flows, John Raiford
Numerical And Physical Modeling Of Turbulent Shear Flows, John Raiford
All Dissertations
This dissertation is an evaluation of popular turbulence schemes; both three dimensional and depth-averaged, and also includes an experimental study on shallow near bed jets. The three dimensional and RNG turbulent closure schemes are evaluated for free and bounded shear flows. For free shear flows (circular and plane turbulent jets), the scheme with standard coefficient performs equally well and in some cases better than the renormalized group scheme in predicting growth rate, decay of centerline velocity and longitudinal velocity profiles. For turbulent kinetic energy across the jet, the inner region is better predicted by the RNG scheme.
The second case …
Spatial Sensors For Quantitative Assessment Of Retrieved Arthroplasty Bearings, Melinda Harman
Spatial Sensors For Quantitative Assessment Of Retrieved Arthroplasty Bearings, Melinda Harman
All Dissertations
Evaluation of retrieved joint arthroplasty bearings provides unique evidence related to the physiological environment in which bearing materials are expected to perform. This dissertation describes the development of novel spatial sensors and measurement strategies for standardized, quantitative assessments of arthroplasty bearings, including total knee replacements, unicompartmental knee replacements, and total hip replacements. The approach is to assess bearings that endured a finite duration of function in patients, with particular emphasis on expanding our understanding of the biomechanical conditions specific to bearing function and wear in the physiological environment. Several quantifiable parameters are identified that prove comparable to pre-clinical in vitro …
Development Of Prediction Models To Measure Vendor Performance In Surveillance And Auditing Of Aircraft Maintenance, Nikhil Iyengar
Development Of Prediction Models To Measure Vendor Performance In Surveillance And Auditing Of Aircraft Maintenance, Nikhil Iyengar
All Dissertations
Elimination of aviation accidents is one of the primary goals of the Federal Aviation Administration (FAA) and the airline industry. A leading cause of aviation accidents is lack of oversight of various organizational issues, in particular, the organization's maintenance operation performance. The technologies used in the industry generate multiple risks, mostly from three domains: systems, hardware and people. Maintenance performance analyses identify the inherent risk in distributed, large-scale systems. Analysis of existing aviation maintenance data is a crucial step in meeting the aviation industry's need to improve aviation safety. Presently, we lack suitable tools to analyze large bodies of maintenance …
Evaluating The Impacts Of Accelerated Incident Clearance Tools And Strategies By Harnessing The Power Of Microscopic Traffic Simulation , Ryan Fries
All Dissertations
Traffic incidents cause Americans delay, waste fuel, cause injuries, and create toxic emissions. Transportation professionals have implemented a variety of tools to manage these impacts and researchers have studied their effectiveness, illustrating a wide range between different tools and locations. To improve this state of knowledge, this dissertation sought to 1) identify prominent and effective incident management strategies, 2) model six selected incident management strategies within five highway corridors in South Carolina, and 3) apply benefit-cost analysis to evaluate the impact of various combinations of these strategies.
To meet these objectives, the author evaluated published literature of the selected strategies, …
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
All Dissertations
The focus of this research is to understand the kinetic and mechanistic aspects of surface-initiated photoiniferter-mediated photopolymerization (SI-PMP) and exploit the robustness of SI-PMP to synthesize stimuli-responsive polymer brushes. The 'living' characteristics of dithiocarbamate-based photoiniferter-mediated photopolymerization are well documented. However, in this dissertation I show that the growth of poly(methyl methacrylate) (PMMA) brushes by SI-PMP is nonlinear, suggesting loss of radicals during SI-PMP and, in turn, non-living characteristics. Results from kinetic models in conjunction with experimental results suggest that irreversible bimolecular termination reactions are a primary culprit for the loss of radicals during SI-PMP. To overcome this problem of irreversible …
Development And In Vitro Examination Of Materials For Osseointegration, Sahil Jalota
Development And In Vitro Examination Of Materials For Osseointegration, Sahil Jalota
All Dissertations
Bone is a connective tissue with nanosized particles of carbonated apatitic calcium phosphate dispersed in a hydrated collagen matrix. With the ageing of the baby boomer population, an increasing number of people sustain bone fractures and defects. Hence, efforts are underway to develop materials to hasten the healing and repairing of such defects. These materials are termed as artificial bone substitutes.
This study represents innovative techniques for development of bone implant materials and improving the existing substitute materials. Emphasis was on three different kinds of materials: Metals (titanium and alloys), Ceramics (calcium phosphates), and Polymers (collagen). The bioactivity of titanium …
Models Of Semi-Systematic Visual Search, Sourav Das
Models Of Semi-Systematic Visual Search, Sourav Das
All Dissertations
Visual search is an important aspect of many examination and monitoring tasks. As a result, visual search performance has been the topic of many empirical investigations. These investigations have reported that individual search performance depends on subject factors such as search behavior, which has motivated the development of models of visual search that incorporate this behavior. Search behavior ranges from random to strictly systematic; variation in behavior is commonly assumed to be caused by differences in memory retrieval and search strategy. Accordingly, a mathematical model of semi-systematic search is proposed here that can account for both memory retrieval and other …
Low-Complexity Iterative Detection Techniques For Slow-Frequency-Hop Spread-Spectrum Communications With Reed-Solomon Coding., Harish Ramchandran
Low-Complexity Iterative Detection Techniques For Slow-Frequency-Hop Spread-Spectrum Communications With Reed-Solomon Coding., Harish Ramchandran
All Dissertations
Slow-frequency-hop (SFH) spread-spectrum communications provide a high level of robustness in packet-radio networks for both military and commercial applications. The use of a Reed-Solomon (R-S) code has proven to be a good choice for use in a SFH system for countering the critical channel impairments of partial-band fading and partial-band interference. In particular, it is effective when reliability information of dwell intervals and individual code symbols can be obtained and errors-and-erasures decoding (EE) can be employed at the receiver.
In this dissertation, we consider high-data-rate SFH communications for which the channel in each frequency slot is frequency selective, manifesting itself …
Analytical And Intelligent Techniques For Dynamically Secure Dispatches, Aftab Alam
Analytical And Intelligent Techniques For Dynamically Secure Dispatches, Aftab Alam
All Dissertations
The NERC August 14th Blackout report brought out by the task force cited 'failure to ensure operation within secure limits' as one of the main reasons. Many of the numerous recommendations focused on the need for better real-time tools for operators and reliability coordinators. In the absence of such tools the operators are limited to operating in conservative secure operating regions established using offline studies. At the same time, with the fast inception of deregulation, the need to ensure a reliable and secure power system has become all the more vital. The success of a competitive market is dependent upon …
Information Flow To Support Front End Planning, Ryan George
Information Flow To Support Front End Planning, Ryan George
All Dissertations
Previous research has demonstrated the value of front end planning as it impacts project performance. This dissertation summarizes the findings of a research project which examined ways to improve information flow through the front end planning process. The front end planning process was carefully diagrammed as consisting of 33 distinct information flow activities, each with its own information flow entities and interactions. Fifty-one questionnaire survey forms were analyzed to obtain data for the 33 information flow activities that included activity duration, resources expended, and other supplemental insights such as the extent of information availability. The 51 projects were then grouped …
Domination And Decomposition In Multiobjective Programming, Alexander Engau
Domination And Decomposition In Multiobjective Programming, Alexander Engau
All Dissertations
During the last few decades, multiobjective programming has received much attention for both its numerous theoretical advances as well as its continued success in modeling and solving real-life decision problems in business and engineering. In extension of the traditionally adopted concept of Pareto optimality, this research investigates the more general notion of domination and establishes various theoretical results that lead to new optimization methods and support decision making.
After a preparatory discussion of some preliminaries and a review of the relevant literature, several new findings are presented that characterize the nondominated set of a general vector optimization problem for which …
Dynamic Measurements Of Lubrication Film Thickness Of Uhmwpe Contacts For Total Joint Replacements, Andrew Clark
Dynamic Measurements Of Lubrication Film Thickness Of Uhmwpe Contacts For Total Joint Replacements, Andrew Clark
All Dissertations
A new contact sensing technology previously developed in the Biotribology Laboratory at Clemson University was further studied, evaluated, and characterized to extend its use to the measurement of lubricating film thickness. First, the laboratory's force-controlled knee joint simulator was used while dynamic contact pressure measurements under both dry and lubricated conditions were made using the sensor technology employed in two different artificial knee implant geometries. Each implant was machined by the manufacturer from custom blocks of ultra high molecular weight polyethylene (UHMWPE) containing a grid of discrete sensing regions. The difference between the dry and lubricated contact areas measured at …
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
All Dissertations
Highly layered structures are important to micro- and nanofabrication technologies for understanding and controlling surface structures through manipulation of chemical and physical interactions. The objective of this work was to develop a new approach to create micro- and nanopatterned surfaces using multilayer polymer films of commercially available and inexpensive polymers instead of inorganic substrates. As an example, linear low density polyethylene (LLDPE) and ethylene-co-acrylic acid copolymer (EAA) were used as alternating inert and reactive polymers, respectively. Thin cross-sections of the multilayer molded sheets were prepared by ultra-microtoming.
As a precursor to the multilayer work, surface modification of EAA was conducted …
Wall And Ground Movements In A Braced Excavation In Clays And Serviceability Reliability Of Adjacent Buildings, Cheng Liang Hsiao
Wall And Ground Movements In A Braced Excavation In Clays And Serviceability Reliability Of Adjacent Buildings, Cheng Liang Hsiao
All Dissertations
The goal of this dissertation research is to establish an improved procedure for evaluating the excavation-induced ground settlement and building serviceability. This research covers several closely related topics. Firstly, a simplified small strain soil model developed by Hsieh et al. (2003), called the Modified Pseudo Plasticity (MPP) model, is evaluated for its capability and performance in the prediction of the excavation-induced ground deformation behavior using Finite Element Method (FEM). Secondly, for the development of the envisioned empirical models for estimating the excavation-induced wall and ground responses, a database of excavation case histories are compiled. To complement the database of excavation …