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Articles 1 - 30 of 146
Full-Text Articles in Engineering
Synthesis And Characterization Of Polymer Brushes For Controlled Adsorption Of Proteins, Olha Hoy
Synthesis And Characterization Of Polymer Brushes For Controlled Adsorption Of Proteins, Olha Hoy
All Dissertations
Performance of biomedical devices to a large extent depends on the interactions between the device surface and the biological liquids/protein molecules. To achieve controllable interactions between the device and biomolecules and still retain the required mechanical strength on the whole, modification of the surface is often done.
In the present study surface properties were modified through a polymer brush approach. After the modification, surfaces gain tunability toward protein adsorption. Mixed polymer brushes consisting of protein repelling and protein attractive components were used, with a 'grafting to' method employed for the synthesis of polymer layers. First, poly(ethylene glycol), the protein repelling …
The Development Of Hyaluronic Acid Biomaterials For Vascular Tissue Engineering, Samir Ibrahim
The Development Of Hyaluronic Acid Biomaterials For Vascular Tissue Engineering, Samir Ibrahim
All Dissertations
Current vascular implant materials poorly interact with medial smooth muscle cells (SMCs) allowing the permanent loss of vascular elastin, eliminated by trauma or disease, a crucial element in maintaining the natural biomechanics of the blood vessel and overall vascular homeostasis. In addition, these materials insufficiently recruit vascular endothelial cells (ECs) to form a normally functional, confluent endothelium that acts as the interface between the blood and vascular tissue and regulates numerous vital vascular processes. As a result, the restenosis, or re-occlusion, rate within these devices has remained fairly high stimulating the investigation of numerous new materials capable of providing the …
Hydraulic Actuated Automotive Cooling Systems - Nonlinear Control And Test, John Wagner, M H. Salah, P M. Frick, D M. Dawson
Hydraulic Actuated Automotive Cooling Systems - Nonlinear Control And Test, John Wagner, M H. Salah, P M. Frick, D M. Dawson
Publications
The replacement of traditional automotive mechanical cooling system components with computer controlled servo-motor driven actuators can improve temperature tracking and reduce parasitic losses. The integration of hydraulic actuators in the engine cooling circuit offers greater power density in a smaller package space when compared with electric actuators. In this paper, a comprehensive nonlinear backstepping robust control technique is developed to regulate the engine coolant temperature by controlling a hydraulic coolant pump and radiator fan. An experimental test bench has been assembled to investigate the hydraulic automotive thermal system performance. Representative numerical and experimental results are presented and discussed. Overall, the …
Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno
Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno
All Theses
A data recorder was utilized to record in-flight vibration of a turbo propeller aircraft. The data recorded produced power spectral density (PSD) profiles which are currently used in laboratory settings to drive vibration tables in order to simulate a particular vehicle type. Overall Grms values from the averaged data were then statistically compared to published standards and other studies to determine if there were differences in overall Grms values.
The data recorder was rigidly mounted to the cargo area of the turbo propeller aircraft. Thirty flights were recorded which varied in flight time from less than one hour to greater …
Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora
Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora
All Dissertations
Restenosis remains a common problem affecting the patency of endovascular intervention such as balloon angioplasty and stent placement as treatments for atherosclerosis. Denudation of the endothelial layer and the increased injury from balloon deployment can cause phenotypic changes in surrounding vascular smooth muscle cells (SMCs) in vivo. The presented work modeled this mechanical environment in vitro to investigate the role of the altered mechanical environment on the phenotypic response of SMCs. Through the system design and CFD channel characterization, a six-independent-channel system providing low oscillating wall shear stress (WSS) was manufactured to apply concurrent shear and tensile forces with uniform …
Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash
Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash
All Dissertations
Piezoelectrically-driven (piezoactive) systems such as nanopositioning platforms, scanning probe microscopes, and nanomechanical cantilever probes are advantageous devices enabling molecular-level imaging, manipulation, and characterization in disciplines ranging from materials science to physics and biology. Such emerging applications require precise modeling, control and manipulation of objects, components and subsystems ranging in sizes from few nanometers to micrometers. This dissertation presents a comprehensive modeling and control framework for piezoactive micro and nano systems utilized in various applications.
The development of a precise memory-based hysteresis model for feedforward tracking as well as a Lyapunov-based robust-adaptive controller for feedback tracking control of nanopositioning stages are …
Development And Characterization Of Moisture- And Heat- Activated Oxygen Scavenging Nanoparticle, Youngjae Byun
Development And Characterization Of Moisture- And Heat- Activated Oxygen Scavenging Nanoparticle, Youngjae Byun
All Dissertations
Alpha-tocopherol and a transition metal, iron, mixture was evaluated as a possible oxygen scavenger. The effects of moisture, amount of transition metal, and thermal processing on oxygen scavenging capability were also investigated. Results showed that alpha-tocopherol and transition metal had 6.72 cc oxygen per gram of oxygen scavenging capacity and 0.11 cc oxygen per gram per day of oxygen scavenging rate.
Nanoencapsulation technology was adopted for the possible oxygen scavenging activation system. Alpha-tocopherol-loaded poly caprolactone (PCL) nanoparticles were prepared by oil in water (O/W) emulsion solvent evaporation with ultrasonification. The effects of PCL concentration, solvent in oil phase, and ultrasonification …
'Fabrication And Characterization Of Polymer Blends And Composites Derived From Biopolymers', Suraj Sharma
'Fabrication And Characterization Of Polymer Blends And Composites Derived From Biopolymers', Suraj Sharma
All Dissertations
This research focuses on fabricating blends and composites from natural polymers especially from proteins and natural epoxy, and describing the properties of plastics made from them. Specifically, plastic samples from partially denatured feathermeal and bloodmeal proteins, derived from the animal co-products (rendering) industry, were successfully produced through a compression molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. Therefore, this study explored blending methods for …
Real-Time Automatic Linear Feature Detection In Images, Guang Zeng
Real-Time Automatic Linear Feature Detection In Images, Guang Zeng
All Dissertations
Linear feature detection in digital images is an important low-level operation in
computer vision that has many applications. In remote sensing tasks, it can be used
to extract roads, railroads, and rivers from satellite or low-resolution aerial images,
which can be used for the capture or update of data for geographic information and
navigation systems. In addition, it is useful in medical imaging for the extraction of
blood vessels from an X-ray angiography or the bones in the skull from a CT or MR
image. It also can be applied in horticulture for underground plant root detection in
minirhizotron images. …
Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui
Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui
All Dissertations
The current tissue engineering paradigm is that successfully engineered thick tissues must include vasculature. As biological approaches alone such as VGEF have fallen short of their promises, one may look for an engineering approach to build microvasculature. With the advent of cell printing, one may be able to build precise human microvasculature with suitable bio-ink. Human Microvascular Endothelial Cells (HMVEC) and fibrin were studied as bio-ink for microvasculature construction. Endothelial cells are the only cells to compose the human capillaries and also the major cells of blood vessel intima layer. Fibrin has been already widely recognized as tissue engineering scaffold …
Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer
Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer
All Dissertations
A working hypothesis within the Laboratory of Vascular Research is that mechanical loading on vascular smooth muscle cells (VSMCs), especially due to solid contact from endovascular devices, contributes to the development of restenosis. In order to better understand the role of mechanical loading on VSMCs in vascular disease development, it is imperative to understand the mechanical properties of VSMCs themselves. To measure the viscoelastic and frictional properties of living VSMCs in an in vitro setting, an atomic force microscope (AFM) was utilized, thereby allowing for mechanical testing of living cells in a fluid environment. In the first phase of research, …
Aperture Coupling And Penetration In Various Configurations, Jason Keen
Aperture Coupling And Penetration In Various Configurations, Jason Keen
All Dissertations
The problem of a slot in a perfectly conducting surface is addressed for a variety of configurations using both integral equation and transmission line techniques. The use of Bethe hole theory to model short slots is discussed and utilized where appropriate. Primary problems of discussion are a slot array, wires coupling through slots in a ground plane, and wires coupling through slots in a bent ground plane. Additionally, the use of the extended BLT formulation for incorporation of slot effects in a transmission line problem is addressed. In this manuscript, the work of Bethe is extended to include cross-aperture coupling …
Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy
Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy
All Dissertations
The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility.
Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to …
Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane
Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane
All Dissertations
Cardiovascular diseases are the leading cause of death worldwide. Blood vessel replacement is a common treatment for vascular diseases such as atherosclerosis, restenosis and aneurysm, with over 300,000 bypass procedures performed each year. However, vein grafts are limited due to their availability. Although synthetic vascular replacements have been successful for large diameter arteries, they have shown minimal success in arteries with diameters <6mm. This is because most synthetic materials induce thrombus formation which, within a few months of implantation, causes failure of the vascular graft due to occlusion. Tissue engineering is a promising approach to the fabrication of non-thrombogenic vascular grafts, but a reliable and expandable cell source for tissue-engineered vascular graft (TEVG) has not been established.
The work presented here is motivated by the current unavailability of an ideal tissue engineered blood vessel replacement. Our overall goal is to create a living tissue engineered vascular graft that is biodegradable, non-thromobogenic, presents low antigenicity and …
Investigation Of The Merging Of Two Axisymmetric Turbulent Jets, Jeffrey Smith
Investigation Of The Merging Of Two Axisymmetric Turbulent Jets, Jeffrey Smith
All Theses
A study was done to determine the converging distance of two axisymmetric turbulent jets and to compare the experimental results with the Reichardt hypothesis. This experiment consisted of measuring the velocity profiles of the two jets and manipulating the momentum ratio between the jets. Through testing, it was determined that the Reichardt hypothesis while efficient, over predicts the converging distance of the jets by up to 25% in some cases.
An Acoustic Doppler Velocimeter (ADV) was used to take measurements across the path of the jets and monitored the velocity and the turbulent kinetic energy. After observing the velocity profiles, …
Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober
Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober
All Theses
The South Carolina Department of Transportation (SCDOT) dedicates a large portion of its budget and other resources to the maintenance of the State's transportation infrastructure. In order to maximize the efficiency and productivity of the State's highway maintenance workforce, the SCDOT partnered with Clemson University to research the performance of these maintenance crews. The goal of this research is to identify optimal crew compositions, if possible, and to suggest potential crew productivity enhancement methods.
Data was collected from the SCDOT Highway Maintenance Management System (HMMS) and crew rankings were developed based on several pre-determined performance criteria. These rankings were then …
Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li
Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li
All Theses
Broadband signal generator is an indispensable module for broadband Six-Port Reflectometer (SPR). To integrate a whole SPR system on a chip, the source must be compact. In this thesis, a three-stage voltage-controlled oscillator (VCO), using two parallel weak invertor-chain oscillators and sense amplifiers, is proposed and designed in a 0.13 µm CMOS process. These two parallel weak inverter-chain oscillators extend the low frequency operating range and the sense amplifiers expand the high frequency operation. The measurement results show that the oscillator can be tuned from 430 MHz to 12 GHz, which satisfies the targeted SPR operating frequency range.
In order …
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
All Theses
An energy dissipation system is proposed for use on consumer passenger automotive vehicles and auto racing stock cars. This system will be utilized to protect the occupants from frontal impacts with stationary or near stationary objects. The system will be affixed to the front of the car's primary structure. It is proposed to replace the traditional steel bumper currently in use. This system will not increase the weight of the car, nor will it adversely affect the aerodynamics of the body. The system will improve the crashworthiness of the vehicle. Advanced composites will be the primary sacrificial element in the …
An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan
An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan
All Theses
In order to design car body structures which are safe during crash, modern automotive manufacturers perform both full-scale experimental crash tests and computer simulation of vehicle crash events using commercially available Finite Element Analysis (FEA) packages such as ABAQUS or LS-DYNA. Use of crash simulations significantly reduces the number of real time crash experiments needed and reduces the time required for design changes. However, in order to capture accurately crash behavior during high-speed impact, a large amount of detailed FEA modeling features such as number and types of elements, mesh element size, number of components, different types of connectors, material …
Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam
Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam
All Dissertations
In this dissertation, research in two parallel directions is presented; the first involves the prediction of the final size and shape of a glass lens during a precision glass lens molding process and the second introduces a method to compute and quantify the importance of higher order terms in fracture mechanics for different modes of fracture.
The process of precision lens molding has received attention in recent years due to its potential to mass produce aspherical lenses. Aspherical lenses have significantly better optical properties and conventional lens making techniques are limited to manufacturing of spherical lenses only. The conventional technique …
Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan
Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan
All Dissertations
Increased emphasis on aircraft inspection to ensure aviation safety has resulted in the need for a better trained workforce of aircraft maintenance personnel. Aircraft inspection is mostly visual in nature. Thus it has led to the development of computer simulators to train human inspectors performing the inspection task. However, the lack of immersion and interaction in such simulators has led to limited effectiveness and adoption. Using advances in graphics and virtual reality technology, there is an increase the sense of involvement in using these simulators. Though technology is available to provide higher levels of immersion, it is expensive. It is …
Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee
Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee
All Dissertations
Attempts to control sediment-containing runoff and associated water quality problems have involved the establishment of many small to medium sediment retention ponds and the injection of nonionic and anionic polyacrylamide (PAM) flocculants to enhance colloid removal. However, to date use has been driven more by practicing engineers and trial-and-error approaches than by logical and consistent design approaches. Therefore, the purpose of this research was to optimize colloidal clay removal in PAM-aided sediment retention ponds by applying experimental and theoretical methodologies.
Initially, simple measurement techniques for the molecular weight (MW) and charge density (CD) of various PAMs were tested and their …
Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan
Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan
All Dissertations
Abstract
Approximately 85,000 heart valve replacement surgeries are performed every year in United States and about 300,000 surgeries worldwide. It is estimated that half of them are mechanical valve replacements and the other half bioprosthetic valve replacements. The use of bioprosthetic heart valves is slowly increasing. Bioprosthetic heart valves are made from porcine aortic valves or bovine pericardium. Commercially these bioprostheses are currently crosslinked using glutaraldehyde (GLUT) to prevent tissue degradation and reduce tissue antigenicity. GLUT crosslinks these bioprostheses by stabilizing the collagen present in the tissue via a Schiff base reaction of the aldehyde with the hydroxylysine / lysine …
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
All Theses
A distributed parameters modeling and control framework for flexible solid-state hysteretic actuator is presented in this work. For the simplicity of analysis, the actuator dynamic behavior is decoupled and treated separately from the hysteresis nonlinearity. To include the effects of widely-used flexural mechanisms, a mass-spring-damper boundary condition is considered for system. Moreover, the effect of electromechanical actuation is included as a concentrate force at the boundary. The problem is then divided into two parts: first part deals with free motion analysis of system in order to obtain eigenvalues and eigenfunctions using the expansion theorem and a standard eigenvalue problem procedure. …
P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson
P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson
All Theses
This manuscript presents two parametric studies which were performed to evaluate a provision which originated in the 1994 Uniform Building Code (UBC). This provision states that if gravity-induced axial loads carried by a reinforced concrete member are greater than 35% of the pure axial load-carrying capacity (Po) of that member, then the member cannot be used as part of the lateral force resisting system (LRFS). Along with the UBC provision, the Structural Engineers Association of California's (SEAOC) Blue Book states that the value of 0.35Po corresponds to the level of axial load representing a balanced state of strain, i.e., the …
Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu
Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu
All Theses
Safety in general is defined as 'the absence of unintended harm to living creatures or inanimate objects' (Evans, 2004). Traffic safety is measured in terms of motor vehicle crashes. A crash is an unplanned event which results in either fatality, or injury or property damage. Of all the factors that contribute to a crash, speed is a major issue, as more than 31 percent of all fatal crashes involve speeding (NHTSA, 2007). The speed-safety relationship can be determined by knowing the effect of speed on the frequency and severity of crashes. The relationship between speed and frequency of crashes is …
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
All Theses
Vehicle Dynamics Control (VDC) systems, also called Electronic Stability Control (ESC) systems, are active on-board safety systems intended to stabilize the dynamics of vehicle lateral motion. In so doing, these systems reduce the possibility of the driver's loss of control of the vehicle in some critical or aggressive maneuvers. One approach to vehicle dynamics control is the use of appropriate drive torque distribution to the wheels of the vehicle. This thesis focuses on particular torque distribution management systems suitable for vehicles with independently driven wheels.
In conducting this study, a non-linear seven degree-of-freedom vehicle model incorporating a non-linear tire model …
Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam
Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam
All Theses
We have studied the optimal server allocation policies for a tandem queueing system under different system settings. Motivated by an industry project, we have studied a two stage tandem queueing system with arrival to the system and having two flexible servers capable of working at either of the stations. In our research, we studied the system under two different circumstances: modeling the system to maximize throughput without cost considerations, modeling the system to include switching and holding costs along with revenue for finished goods. In the maximizing throughput scenario, we considered two different types of server allocations: collaborative and non-collaborative. …
The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller
The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller
All Theses
Starch is an interesting biodegradable polymer due to its excellent film forming properties, availability, and low cost. On the other hand, starch films are often limited by their poor mechanical properties, and water resistance. The addition of montmorillonite clays have improved these properties in both petroleum and biodegradable films.
The objective of the research was to determine the effect of montmorillonite clay on the mechanical and barrier properties on mung bean starch films.
The addition of 5% clay yielded the optimum balance between mechanical and barrier properties of these composite films with improved tensile strength (TS) of 20.8763± 0.789 MPa, …
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
All Theses
Advances in micromachining technology have enabled the design and development of high performance microelectromechanical systems (MEMS). There is a pressing need for control techniques that can be used to improve the dynamic behavior of MEMS such as the response speed and precision. In MEMS applications, open-loop control is attractive as it computes a priori the required system input to achieve desired dynamic behavior without using feedback, thus eliminating the problems associated with closed-loop MEMS control. While the input-shaping control is attractive due to its simplicity, the effectiveness of this control approach depends on the accuracy of the model that is …