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Articles 1 - 30 of 45
Full-Text Articles in Engineering
On The Stability Of Region Count In The Parameter Space Of Image Analysis Methods, Li Yu
On The Stability Of Region Count In The Parameter Space Of Image Analysis Methods, Li Yu
All Dissertations
In this dissertation a novel bottom-up computer vision approach is proposed. This approach is based upon quantifying the stability of the number of regions or count in a multi-dimensional parameter scale-space. The stability analysis comes from the properties of flat areas in the region count space generated through bottom-up algorithms of thresholding and region growing, hysteresis thresholding, variance-based region growing. The parameters used can be threshold, region growth, intensity statistics and other low-level parameters. The advantages and disadvantages of top-down, bottom-up and hybrid computational models are discussed. The approaches of scale-space, perceptual organization and clustering methods in computer vision are …
Investigation Into Mitigation Of Alkali-Silica Reaction Using Selected Scms In Presence Of Potassium Acetate Deicer, Jigar Desai
Investigation Into Mitigation Of Alkali-Silica Reaction Using Selected Scms In Presence Of Potassium Acetate Deicer, Jigar Desai
All Dissertations
Alkali-silica reaction (ASR) is one of the most recognized durability problems in concrete leading to premature deterioration of different types of concrete structures. Recent investigation into premature deterioration of airfield concrete pavements indicated the aggressive effects of alkali-acetate and alkali-formate based deicers on concrete containing marginal aggregates, in particular on their potential to induce ASR.. This dissertation presents the results and analysis from a research study conducted to evaluate the effectiveness of selected supplementary cementitious materials-SCMs (fly ash and slag) as ASR mitigation measures in presence of potassium acetate based deicer.
Five aggregates that encompass a range of mineralogies and …
Ultrahydrophobic Surface Modification Of Polymeric Fibers And Inorganic Substrates, Karthik Ramaratnam
Ultrahydrophobic Surface Modification Of Polymeric Fibers And Inorganic Substrates, Karthik Ramaratnam
All Dissertations
The wettability of a solid surface is a very important property, and is governed by both the chemical composition and the geometrical microstructure of the surface. Wettability and repellency are important properties of solid surfaces from both fundamental and practical aspects. The wettability of the solid surface is a characteristic property of materials and strongly depends on both the surface energy and the surface roughness. These properties may be approached by mimicking hydrophobic structures created by nature on lotus leaf surface. The lotus effect is based on surface roughness caused by different microstructures together with the hydrophobic properties of the …
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
All Dissertations
Film casting is a common industrial process used to produce polymeric films. During film casting, a polymer melt is extruded through a flat die before rapid cooling on a chill roll. The chill roll velocity is faster than the velocity at which the melt exits the die, thus the polymer melt is stretched and oriented in an extensional flow. The material properties and processing conditions have a significant impact on the process and the final thermal/mechanical properties of the film produced.
Optimization of industrial scale film casting processes is still greatly dependent on trial and error methods. Therefore, this work …
Investigation Of Structure And Properties Of Novel Multi-Layer Clay Nanocomposite Films Produced Controllably By Continuous Chaotic Advection Blending, Chaitra Mahesha
Investigation Of Structure And Properties Of Novel Multi-Layer Clay Nanocomposite Films Produced Controllably By Continuous Chaotic Advection Blending, Chaitra Mahesha
All Dissertations
Polymer nanoclay composites have been studied extensively in the past decade due to the excellent combination of properties they can offer at low loadings of clay. Despite robust research, the potential enhancements that nanoclays are theoretically predicted to offer have not been achieved. Such potential improvements in mechanical and gas barrier properties are realized only when the internal structure of the nanocomposite is optimized in terms of arrangement and orientation of nanoclay within the matrix. The mixing-based approach and the accompanying complex flow fields of conventional processing techniques widely used to produce nanoclay composites are unable to control the internal …
Sediment Transport Upstream Of Orifices, David Powell
Sediment Transport Upstream Of Orifices, David Powell
All Dissertations
Sediment transport upstream of orifices has not been studied outside the realm of the restoration of reservoir storage capacity. This experimental study used a large basin with a circular orifice outlet and a movable sand bed leveled with the invert of the orifice. Three sizes of non-cohesive, uniform sand were used with d50 values of 0.29mm, 0.72mm, and 0.89mm. Bed profiles at equilibrium scour conditions were measured for three different head levels for each sediment size. The maximum scour depth, length, and scour width were related to the particle size and the available head. The longitudinal and lateral extents …
Techniques For Improving The Performance Of Coupled Oscillator Arrays, Venkatesh Seetharam
Techniques For Improving The Performance Of Coupled Oscillator Arrays, Venkatesh Seetharam
All Dissertations
Coupled oscillator arrays (COAs) have excellent synchronization properties that can be utilized to develop a low cost alternative to phased array systems for beam steering applications. The primary concerns in implementing the COA architecture are the sensitivity to cell-to-cell component variation and poor phase noise performance. Wide injection locking range oscillators reduce the sensitivity to component variation but degrade the array phase noise performance. The objective of this dissertation is to alleviate the concerns hindering the application of COAs by employing techniques to realize COAs with wide mutual injection locking ranges (MILR), improved phase noise characteristics and beam steering capabilities. …
A Comparative Fault Diagnosis Methodology Based On Time Series Analysis Of System's Signals, Hany Bassily
A Comparative Fault Diagnosis Methodology Based On Time Series Analysis Of System's Signals, Hany Bassily
All Dissertations
The detection of system anomalies represents an important task in safety critical systems. Over the past two decades, advances in data manipulation techniques and sensor technology have contributed to the widespread application of signal processing concepts for fault diagnosis. However, the majority of these signal processing, or data driven, diagnostics do not possess the redundancy level exhibited in conventional model-based methods. Among signal processing methods, time series analysis is advantageous since it offers insight into the underlying dynamics and forecasts system behavior. Furthermore, the data driven method allows the depiction of system dynamics with an increased level of redundancy. This …
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
All Dissertations
Nano-modifiers are typically three orders of magnitude smaller in size than their micro-counterparts. At this scale, interactions between matrix molecules and the nano-modifiers can lead to novel physical and chemical properties of the resulting nanocomposites. Carbon nanofibers (CNFs) are a class of nano-modifiers that has received significant attention recently because they have superior electrical conductivity and mechanical properties with a high aspect ratio (length over diameter). Several recent research studies have focused on enhancing electrical and mechanical performance of composites in the presence of CNFs. However, the influence of CNFs on the structure of the polymer matrix is important in …
Development Of An In Vitro Test System For Breast Cancer Research, Chih-Chao Yang
Development Of An In Vitro Test System For Breast Cancer Research, Chih-Chao Yang
All Dissertations
In the United States, breast cancer is the third most common cause of cancer death (after lung cancer and colon cancer). In 2007, breast cancer is expected to cause 40,910 deaths (7% of cancer deaths; almost 2% of all deaths) in the U.S. The long term goal of this project is to develop an in vitro test system that can be used to develop breast cancer vaccine or screen breast cancer chemotherapy. This dissertation was driven by four objectives and it can be thought as a toolbox that provides practical experimental design and lab work for the development of an …
Multi-Objective Generation Scheduling With Hybrid Energy Resources, Manas Trivedi
Multi-Objective Generation Scheduling With Hybrid Energy Resources, Manas Trivedi
All Dissertations
In economic dispatch (ED) of electric power generation, the committed generating units are scheduled to meet the load demand at minimum operating cost with satisfying all unit and system equality and inequality constraints. Generation of electricity from the fossil fuel releases several contaminants into the atmosphere. So the economic dispatch objective can no longer be considered alone due to the environmental concerns that arise from the emissions produced by fossil fueled electric power plants. This research is proposing the concept of environmental/economic generation scheduling with traditional and renewable energy sources. Environmental/economic dispatch (EED) is a multi-objective problem with conflicting objectives …
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
All Dissertations
ABSTRACT Thermotoga neapolitana can use different sources of carbon and nitrogen for growth and produces biological hydrogen. Sources of carbon (glucose, sucrose, xylose, xylan, cellulose, cellobiose, starch, corn starch, beet bulp pellet, and rice flour) and nitrogen (yeast extract, fish meal, cottonseed meal, canola meal, linseed meal, and soybean meal) were compared. In the carbon studies, glucose, sucrose, rice flour, and xylan produced similar levels of hydrogen. In the nitrogen studies, Trypticase combined with alternative nitrogen sources can efficiently increases the yield of hydrogen produced by Thermotoga neapolitana. Yeast extract with trypticase as the dual nitrogen sources produced significantly increased …
Improving The Performance Of Software Defined Radio By Employing Digital Feedback Of Radio Frequency Properties, Joel Simoneau
Improving The Performance Of Software Defined Radio By Employing Digital Feedback Of Radio Frequency Properties, Joel Simoneau
All Dissertations
This dissertation provides tools for the analysis and integration of the hardware and software components of a software defined radio for optimum radio frequency performance. A device is introduced that is able to give baseband feedback of radio frequency properties suitable for analysis in software. Three applications for the device are devised. The first is an image rejection upconverter that achieves greater than 65 dB of image rejection over a broad frequency range without the use of a radio frequency filter. The second application is a baseband correction scheme for extending the bandwidth and improving the magnitude and phase match …
Wind Effects On Monosloped And Sawtooth Roofs, Bo Cui
Wind Effects On Monosloped And Sawtooth Roofs, Bo Cui
All Dissertations
Wind is one of the significant forces of nature that must be considered in the design of buildings. The actual behavior of wind is influenced not only by the surface (or boundary-layer) conditions, but also by the geometry of the building. All sorts of turbulent effects occur, especially at building corners, edges, roof eaves. Some of these effects are accounted for by the wind pressure coefficient. Wind pressure coefficients used in practice have usually been obtained from experimentally by testing models of different type of structures in wind tunnels.
In this study, a series of wind tunnel tests with scale …
Measurement And Analysis Of Hydromechanical Effects In Fractured Rock, Todd Schweisinger
Measurement And Analysis Of Hydromechanical Effects In Fractured Rock, Todd Schweisinger
All Dissertations
Fractures in rock hold important stores of water and petroleum, and slight changes in fracture aperture accompanying drawdown from pumping wells play a key role in recovering these resources. Four accomplishments are described that advance insight into the behavior and characterization of fractured crystalline rock.
First was the development of two removable borehole extensometers that enable small axial displacements to be measured during hydraulic well tests. The extensometers consist of four major components: 1.) a pair of anchors; 2.) a displacement transducer 3.) a registration system, and; 4.) a temperature-compensated reference rod. One extensometer uses an axial reference rod with …
Evaluation Of Lithium Based Deicing Chemicals For Mitigating Asr In Concrete Pavement, Senthil Soundarapandian
Evaluation Of Lithium Based Deicing Chemicals For Mitigating Asr In Concrete Pavement, Senthil Soundarapandian
All Dissertations
Deicing and anti-icing chemicals such as alkali-acetate and alkali-formate based formulations are increasingly being used on airfield pavements. Among these new deicers, potassium acetate-based formulations are widely used due to their environmentally friendly nature and effectiveness in melting and undercutting ice at low temperatures. Recent research on premature deterioration of airfield pavements due to alkali-silica reaction (ASR) has indicated that alkali-acetate and alkali-formate deicers such as potassium acetate and sodium formate may have been responsible for the observed distress. In an effort to develop a deicing chemical that is benign to concrete from an ASR standpoint, a new deicing formulation …
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
All Dissertations
Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model …
Manufacturable Process And Tool For High Performance Metal/High-K Gate Dielectric Stacks For Sub-45 Nm Cmos & Related Devices, Aarthi Venkateshan
Manufacturable Process And Tool For High Performance Metal/High-K Gate Dielectric Stacks For Sub-45 Nm Cmos & Related Devices, Aarthi Venkateshan
All Dissertations
Off state leakage current related power dominates the CMOS heat dissipation problem of state of the art silicon integrated circuits. In this study, this issue has been addressed in terms of a low-cost single wafer processing (SWP) technique using a single tool for the fabrication of high-κ dielectric gate stacks for sub-45 nm CMOS. A system for monolayer photoassisted deposition was modified to deposit high-quality HfO2 films with in-situ clean, in-situ oxide film deposition, and in-situ anneal capability. The system was automated with Labview 8.2 for gas/precursor delivery, substrate temperature and UV lamp. The gold-hafnium oxide-aluminum (Au-HfO2-Al) stacks processed in …
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
All Dissertations
Microcantilevers are one the most commonly utilized microelectromechanical systems in a variant of the ultra-precise scanning and characterization application. Of particular interest, the problem of vibrations of microcantilevers has recently received considerable attention due to its application in several nanotechnological instruments such as atomic force microscopy, nanomechanical cantilever sensors and friction force microscopy. For applications such as these, the problem of coupled flexural-torsional nonlinear vibrations of a piezoelectrically-actuated microcantilever beam is considered in this dissertation. The actuation and sensing are both facilitated through bonding a piezoelectric layer (here, ZnO) on the microcantilever surface. The beam is considered to have simultaneous …
Differentiation Modulation Of Adult Stem Cells In An Adipose System, Aditya Chaubey
Differentiation Modulation Of Adult Stem Cells In An Adipose System, Aditya Chaubey
All Dissertations
The need for soft tissue reconstruction or augmentation has increased continuously over the years. This need is compounded by patients suffering from post-traumatic repair and congenital soft-tissue deformities. All the current options available to treat the soft tissue deformities have inherent difficulties associated with them. Hence, more research is needed to come up with a better solution to this problem which is only going to increase in magnitude. Tissue engineering is a relatively new technique which has the potential to deliver a cell-based device which can overcome the problems associated with traditional therapies. However, before it becomes clinically viable we …
Activation Of Systemic Adhesion Molecules And C Reactive Protein In Response To Biomaterial Particle Induced Cytokine Production, Robin Graham
All Dissertations
Chronic inflammation has been identified as a major contributor to many diseases including, atherosclerosis, osteoporosis, dementia, Alzheimer's disease and type 2 diabetes, to name a few. Many of the same markers of inflammation found in the diseases listed above, including IL-1, IL-6, TNF-α, NF-B and adhesion molecules, have also been found in wear debris induced osteolysis. While the local response to biomaterial wear debris has been characterized quite extensively, very little is known about the systemic effect of biomaterial wear debris on the inflammatory system. The objectives of this study were to evaluate the in vitro and in vivo inflammatory …
Nonlinear Control Strategies For Advanced Vehicle Thermal Management Systems, Mohammad Salah
Nonlinear Control Strategies For Advanced Vehicle Thermal Management Systems, Mohammad Salah
All Dissertations
Advanced thermal management systems for internal combustion engines can improve coolant temperature regulation and servo-motor power consumption to positively impact the tailpipe emissions, fuel economy, and parasitic losses by better regulating the combustion process with multiple computer controlled components. The traditional thermostat valve, coolant pump, and clutch-driven radiator fan are upgraded with servo-motor actuators. When the system components function harmoniously, desired thermal conditions can be accomplished in a power efficient manner. Although the vehicle's mechanical loads can be driven by electric servo-motors, the power demands often require large actuator sizes and electrical currents. Integrating hydraulically-driven actuators in the cooling circuit …
Characterization Of Recycled Aged Crm Binders, Soon-Jae Lee
Characterization Of Recycled Aged Crm Binders, Soon-Jae Lee
All Dissertations
The incorporation of conventional reclaimed asphalt pavement (RAP) in hot-mix asphalt (HMA) pavements has become routine in many states around the United States and many other countries all over the world. In addition, the recycling of crumb rubber modified (CRM) materials has been an area of interest since CRM was first used in asphalt paving materials over 40 years ago. Previous research on the recycling of rubberized asphalt concrete (RAC) materials have been limited and focused mainly on the mixture properties at the location of in-field paving. However, for the long-term performance characterizations, it is needed to investigate the aging …
In Situ Photopolymerized Hydrogels For Enhancing Protein Delivery, Chien-Chi Lin
In Situ Photopolymerized Hydrogels For Enhancing Protein Delivery, Chien-Chi Lin
All Dissertations
In recent years, there has been immense interest in the utilization of photopolymerized hydrogels as carriers for controlled protein delivery and cell scaffolds for tissue engineering applications. Although poly(ethylene glycol) (PEG)-based hydrogels formed from mild photopolymerization methods have been suggested as biocompatible matrices that allow for safely encapsulating biomolecules including proteins, peptides, DNA, and cells, the adverse effects of photopolymerization reactions on the encapsulated proteins have largely been overlooked. In addition, conventional hydrophilic hydrogels fail to effectively control protein delivery rates due to their high permeability. These two problems are critical since the delivery of protein therapeutics from hydrogel matrices …
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
All Dissertations
Biodiesel, defined as 'a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats', is finding favor commercially worldwide. The objective of this study is to evaluate the use of solid catalysts for triglyceride transesterification and carboxylic acid esterification to produce biodiesel fuel.
Processes using mainly homogeneous alkali catalysts (such as NaOH, KOH, and methoxides) have been shown to be effective for biodiesel synthesis when dealing with virgin oil feedstocks. Use of acid catalysts (e.g., H2SO4) becomes important when processing low quality feedstocks that contain appreciable amounts of free fatty acids, such as …
Thermodynamic Adsorption Studies Of Peptides On Well-Defined, Surface-Confined Polymers With Applications In Membrane Bioseparations, Nripen Singh
All Dissertations
This dissertation deals with the fundamental studies of peptide adsorption on surfaces modified by surface-confined polymer films, with an application emphasis on membrane bioseparations. In order to understand protein adsorption at a fundamental level, it is important to study the specific residue-level interactions with surfaces. Keeping this idea in view, the present work describes experimental measurements of submolecular-level interaction energies involved in the process of peptide adsorption on polymer films using surface plasmon resonance spectroscopy. Gibbs energy change on adsorption (ΔGad) for tyrosine, phenylalanine, and glycine homopeptides were measured at 25 °C and pH 7 on highly uniform, nanothin polymer …
Control Techniques For Robot Manipulator Systems With Modeling Uncertainties, David Braganza
Control Techniques For Robot Manipulator Systems With Modeling Uncertainties, David Braganza
All Dissertations
This dissertation describes the design and implementation of various nonlinear control strategies for robot manipulators whose dynamic or kinematic models are uncertain. Chapter 2 describes the development of an adaptive task-space tracking controller for robot manipulators with uncertainty in the kinematic and dynamic models. The controller is developed based on the unit quaternion representation so that singularities associated with the otherwise commonly used three parameter representations are avoided. Experimental results for a planar application of the Barrett whole arm manipulator (WAM) are provided to illustrate the performance of the developed adaptive controller.
The controller developed in Chapter 2 requires the …
Control Of Nonlinear Mechatronic Systems, Enver Tatlicioglu
Control Of Nonlinear Mechatronic Systems, Enver Tatlicioglu
All Dissertations
This dissertation is divided into four self-contained chapters. In Chapter 1, an adaptive nonlinear tracking controller for kinematically redundant robot manipulators is presented. Past research efforts have focused on the end-effector tracking control of redundant robots because of their increased dexterity over their non-redundant counterparts. This work utilizes an adaptive full-state feedback quaternion based controller developed in [1] and focuses on the design of a general sub-task controller. This sub-task controller does not affect the position and orientation tracking control objectives, but instead projects a preference on the configuration of the manipulator based on sub-task objectives such as the following: …
Non-Boltzamann Sampling For The Accurate Calculation Of Peptide-Surface Adsorption Free Energy, Feng Wang
Non-Boltzamann Sampling For The Accurate Calculation Of Peptide-Surface Adsorption Free Energy, Feng Wang
All Dissertations
%Abstract
The objectives of this project are 1) the setup and refinement of peptide-SAM surface model systems with explicit water using CHARMM and 2) the development of up-to-date simulation protocols for the accurate calculation of adsorption free energy by incorporating the recent development of non-Boltzmann sampling methods in molecular dynamics and applying it for the calculation of adsorption free energy of short peptides onto well-characterized self-assembled monolayers, which is important for understanding protein/surface interactions.
A software package called the Simulation Template Engine for Peptides at Surfaces (STEPS) was developed for the fulfillment of the first objective. It facilitates the automatic …
Heuristics For Scheduling Reentrant Flexible Job Shops With Sequence-Dependent Setup Times And Limited Buffer Capacities, Jakrawarn Kunadilok
Heuristics For Scheduling Reentrant Flexible Job Shops With Sequence-Dependent Setup Times And Limited Buffer Capacities, Jakrawarn Kunadilok
All Dissertations
This research addresses the problem of scheduling complex job shops with minimizing total weighted tardiness as the objective. The complex job shop is characterized by reentrant job flow through a number of different work centers that contain one or more identical parallel machines. The processing restrictions for the complex job shop include possible non-zero ready times and sequence-dependent setup times. We categorize the complex job shop into two classes: the complex job shop with infinite or finite buffer capacities. We propose three solution methodologies for scheduling the problem with infinite buffer capacities. The first method is the use of mixed …