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Theses/Dissertations

2014

Purdue University

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Articles 1 - 30 of 298

Full-Text Articles in Engineering

Advanced Iii-V / Si Nano-Scale Transistors And Contacts: Modeling And Analysis, Seung Hyun Park Oct 2014

Advanced Iii-V / Si Nano-Scale Transistors And Contacts: Modeling And Analysis, Seung Hyun Park

Open Access Dissertations

The exponential miniaturization of Si CMOS technology has been a key to the electronics revolution. However, the continuous downscaling of the gate length becomes the biggest challenge to maintain higher speed, lower power, and better electrostatic integrity for each following generation. Hence, novel devices and better channel materials than Si are considered to improve the metal-oxide-semiconductor field-effect transistors (MOSFETs) device performance. III-V compound semiconductors and multi-gate structures are being considered as promising candidates in the next CMOS technology. III-V and Si nano-scale transistors in different architectures are investigated (1) to compare the performance between InGaAs of III-V compound semiconductors and …


Acrolein As A Novel Therapeutic Target For Spinal Cord Injury Induced Neuropathic Pain, Jonghyuck Park Oct 2014

Acrolein As A Novel Therapeutic Target For Spinal Cord Injury Induced Neuropathic Pain, Jonghyuck Park

Open Access Dissertations

Despite years of research, post-spinal cord injury (SCI) chronic neuropathic pain remains refractory to treatment and drastically impairs quality of life for SCI victims beyond paralysis. Although inflammation and free radicals contribute to neuropathic pain in SCI, the mechanism is not completely clear. We have recently demonstrated that acrolein, a product and catalyst of lipid peroxidation, induces a vicious cycle of oxidative stress, amplifying its effects and perpetuating oxidative stress and inflammation. In the current study, we have confirmed that acrolein is elevated significantly at least two weeks post-SCI which coincides with the emergence of hyperalgesia (mechanical, cold and thermal). …


Structural Characterization Of Multimetallic Nanoparticles, Vineetha Mukundan Oct 2014

Structural Characterization Of Multimetallic Nanoparticles, Vineetha Mukundan

Open Access Dissertations

Bimetallic and trimetallic alloy nanoparticles have enhanced catalytic activities due to their unique structural properties. Using in situ time-resolved synchrotron based x-ray diffraction, we investigated the structural properties of nanoscale catalysts undergoing various heat treatments. Thermal treatment brings about changes in particle size, morphology, dispersion of metals on support, alloying, surface electronic properties, etc. First, the mechanisms of coalescence and grain growth in PtNiCo nanoparticles supported on planar silica on silicon were examined in detail in the temperature range 400-900°C. The sintering process in PtNiCo nanoparticles was found to be accompanied by lattice contraction and L10chemical ordering. …


Solid Amine-Boranes As High Performance Hypergolic Hybrid Rocket Fuels, Mark A. Pfeil Oct 2014

Solid Amine-Boranes As High Performance Hypergolic Hybrid Rocket Fuels, Mark A. Pfeil

Open Access Dissertations

Hypergolic hybrid rockets have the potential of providing systems that are simple, reliable, have high performance, and allow for energy management. Such a propulsion system can be applied to fields that need a single tactical motor with flexible mission requirements of either high speed to target or extended loitering. They also provide the possibility for alternative fast response dynamic altitude control systems if ignition delays are sufficiently short. ^ Amines are the traditional fuel of choice when selecting a hypergolic combination as these tend to react readily with both nitric acid and dinitrogen tertroxide based oxidizers. It has been found …


Development Of A Static Bioactive Stent Prototype And Dynamic Aneurysm-On-A-Chip(Tm) Model For The Treatment Of Aneurysms, Lisa M. Reece Oct 2014

Development Of A Static Bioactive Stent Prototype And Dynamic Aneurysm-On-A-Chip(Tm) Model For The Treatment Of Aneurysms, Lisa M. Reece

Open Access Dissertations

Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. While these procedures can be effective, it would be advantageous to design a biologically active stent, modified with magnetic stent coatings, allowing cells to be manipulated to heal the arterial lining. Further, velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, but the shear force mechanisms effecting wound closure is elusive. Due to these factors, there is a definite need to cultivate …


Power-Efficient High-Speed Interface Circuit Techniques, Elkim Felipe Roa Fuentes Oct 2014

Power-Efficient High-Speed Interface Circuit Techniques, Elkim Felipe Roa Fuentes

Open Access Dissertations

Inter- and intra-chip connections have become the new challenge to enable the scaling of computing systems, ranging from mobile devices to high-end servers. Demand for aggregate I/O bandwidth has been driven by applications including high-speed ethernet, backplane micro-servers, memory, graphics, chip-to-chip and network onchip. I/O circuitry is becoming the major power consumer in SoC processors and memories as the increasing bandwidth demands larger per-pin data rate or larger I/O pin count per component. The aggregate I/O bandwidth has approximately doubled every three to four years across a diverse range of standards in different applications. However, in order to keep pace …


Trajectory Design In The Spatial Circular Restricted Three-Body Problem Exploiting Higher-Dimensional Poincare Maps, Amanda F. Haapala Oct 2014

Trajectory Design In The Spatial Circular Restricted Three-Body Problem Exploiting Higher-Dimensional Poincare Maps, Amanda F. Haapala

Open Access Dissertations

In this investigation, the role of higher-dimensional Poincaré maps in facilitating trajectory design is explored for a variety of applications. To begin, existing strategies to implement Poincaré maps for trajectory design applications in the spatial CR3BP are evaluated. New applications for these strategies are explored, including an analysis of the natural motion of Jupiter-family comets that experience temporary capture about Jupiter, and the search for periodic orbits in the vicinity of the primary bodies in the spatial problem. Because current strategies to represent higher-dimensional maps, generally, lead to a loss of information, new approaches to represent all information contained in …


Investigation And Modeling Of Uranium Polarization For The Electrorefining Of Scrap U-Mo Foils, Melissa Rose Oct 2014

Investigation And Modeling Of Uranium Polarization For The Electrorefining Of Scrap U-Mo Foils, Melissa Rose

Open Access Dissertations

A uranium molybdenum alloy fuel has been proposed to convert research and test reactors from highly enriched uranium to low enriched uranium to increase the proliferation resistance at such reactors. Pyroprocessing has been selected to recover uranium from the scrap produced in the manufacture of this novel fuel type. Electrorefining, the main separation process of pyroprocessing, is modeled through a novel approach using corrosion theory. To use corrosion theory, knowledge of uranium polarization and kinetic parameters such as Tafel constant, transfer coefficient and exchange current density are required. Uranium polarization was investigated at five temperatures and three scan rates in …


Silica Nanoparticles As Vehicles For Therapy Delivery In Neurological Injury, Desiree Schenk Oct 2014

Silica Nanoparticles As Vehicles For Therapy Delivery In Neurological Injury, Desiree Schenk

Open Access Dissertations

Acrolein, a very reactive aldehyde, is a culprit in the biochemical cascade after primary, mechanical spinal cord injury (SCI), which leads to the destruction of tissue initially unharmed, referred to as "secondary injury". Additionally, in models of multiple sclerosis (MS) and some clinical research, acrolein levels are significantly increased. This aldehyde overwhelms the natural anti-oxidant system, reacts freely with proteins, and releases during lipid peroxidation (LPO), effectively regenerating its self. Due to its ability to make more copies of itself in the presence of tissue via lipid peroxidation, researchers believe that acrolein plays a role in the increased destruction of …


Simulations Of Diffusion Driven Phase Evolution In Heterogenous Solids, Subramanya Gautam Sadasiva Oct 2014

Simulations Of Diffusion Driven Phase Evolution In Heterogenous Solids, Subramanya Gautam Sadasiva

Open Access Dissertations

With reduction in size, ever greater operational demands are placed on electronics components at all levels of the device, starting from the transistor level to the level of the package and the solder interconnects. Concurrently, there has been a move to more complicated materials systems in order to meet health and environmental guidelines. These trends of reducing size, increasing loads have increased the necessity to understand the mechanisms of the failure. ^ As the length scales are reduced, it becomes increasingly important to consider interfacial and micro-structural effects that can be safely ignored at larger length scales owing to the …


Predicting Lubrication Performance Between The Slipper And Swashplate In Axial Piston Hydraulic Machines, Andrew T. Schenk Oct 2014

Predicting Lubrication Performance Between The Slipper And Swashplate In Axial Piston Hydraulic Machines, Andrew T. Schenk

Open Access Dissertations

Engineering of the sliding interfaces within swashplate type axial piston machines represents the most complex and difficult part of the design process. The sliding interfaces are subject to significant normal loads which must be supported while simultaneously preventing component wear to ensure long lasting operation. Proper lubrication design is essential to separate the solid bodies from each other, but the complexity of the physics involved makes this a difficult problem. This work focuses on lubrication and the resulting energy losses at the sliding interface between the slipper and swashplate. ^ To better understand the slipper lubrication performance, a numerical model …


A New Passive Surface Water Flux Meter For Simultaneous Measurement Of Contaminant And Water Fluxes In Streams And Rivers, Stephen A. Sassman Oct 2014

A New Passive Surface Water Flux Meter For Simultaneous Measurement Of Contaminant And Water Fluxes In Streams And Rivers, Stephen A. Sassman

Open Access Dissertations

A passive surface water flux meter (PSFM) for measurement of contaminant concentration/flux in rivers and streams is described and tested. The novel PSFM design was developed for portability and ease of adaptability for a variety of contaminant classes. Although previous designs have been evaluated under constant flow conditions, the PSFM has never been used for measurement of pesticides or hormones and this is the first time that it has been tested under transient flow. Discharge through the PSFM is assessed by measuring miscible displacement of alcohol tracers from granular activated carbon (GAC). The tracer retardation factors (R) measured by miscible …


Structure And Activity Relationships Of Bimetallic Catalysts For Aqueous Phase Reforming And The Water-Gas Shift Reaction, Fred Gerald Sollberger Oct 2014

Structure And Activity Relationships Of Bimetallic Catalysts For Aqueous Phase Reforming And The Water-Gas Shift Reaction, Fred Gerald Sollberger

Open Access Dissertations

As the existing deposits of petroleum and non-renewable energy resources are exhausted, become more difficult to extract, and remain in politically unstable regions of the world, the search for long term alternatives for fuels and chemicals from renewable sources such as biomass continues. One promising process for the production of renewable hydrogen to use in conversion of biomass to fuels and chemicals is aqueous phase reforming (APR) of cellulose-derived carbohydrates. In the first study Pt/MWCNT catalysts have been promoted by addition of transition metal promoters Cu, Ni, Co, Fe, Mn, Mo, W, and Re in Pt:M 1:1 atomic ratios to …


Digital Provenance - Models, Systems, And Applications, Salmin Sultana Oct 2014

Digital Provenance - Models, Systems, And Applications, Salmin Sultana

Open Access Dissertations

Data provenance refers to the history of creation and manipulation of a data object and is being widely used in various application domains including scientific experiments, grid computing, file and storage system, streaming data etc. However, existing provenance systems operate at a single layer of abstraction (workflow/process/OS) at which they record and store provenance whereas the provenance captured from different layers provide the highest benefit when integrated through a unified provenance framework. To build such a framework, a comprehensive provenance model able to represent the provenance of data objects with various semantics and granularity is the first step. In this …


Shape From Inconsistent Silhouette: Reconstruction Of Objects In The Presence Of Segmentation And Camera Calibration Error, Amy Tabb Oct 2014

Shape From Inconsistent Silhouette: Reconstruction Of Objects In The Presence Of Segmentation And Camera Calibration Error, Amy Tabb

Open Access Dissertations

Silhouettes are useful features to reconstruct the object shape when the object is textureless or the shape classes of objects are unknown. In this dissertation, we explore the problem of reconstructing the shape of challenging objects from silhouettes under real-world conditions such as the presence of silhouette and camera calibration error. This problem is called the Shape from Inconsistent Silhouettes problem. A psuedo-Boolean cost function is formalized for this problem, which penalizes differences between the reconstruction images and the silhouette images, and the Shape from Inconsistent Silhouette problem is cast as a psuedo-Boolean minimization problem. We propose a memory and …


Computing With Spintronics: Circuits And Architectures, Rangharajan Venkatesan Oct 2014

Computing With Spintronics: Circuits And Architectures, Rangharajan Venkatesan

Open Access Dissertations

This thesis makes the following contributions towards the design of computing platforms with spintronic devices. 1) It explores the use of spintronic memories in the design of a domain-specific processor for an emerging class of data-intensive applications, namely recognition, mining and synthesis (RMS). Two different spintronic memory technologies — Domain Wall Memory (DWM) and STT-MRAM — are utilized to realize the different levels in the memory hierarchy of the domain-specific processor, based on their respective access characteristics. Architectural tradeoffs created by the use of spintronic memories are analyzed. The proposed design achieves 1.5X-4X improvements in energy-delay product compared to a …


Estimating Toner Usage With Laser Electrophotographic Printers, And Object Map Generation From Raster Input Image, Lu Wang Oct 2014

Estimating Toner Usage With Laser Electrophotographic Printers, And Object Map Generation From Raster Input Image, Lu Wang

Open Access Dissertations

Accurate estimation of toner usage is an area of on-going importance for laser, electrophotographic (EP) printers. In Part 1, we propose a new two-stage approach in which we first predict on a pixel-by-pixel basis, the absorptance from printed and scanned pages. We then form a weighted sum of these pixel values to predict overall toner usage on the printed page. The weights are chosen by least-squares regression to toner usage measured with a set of printed test pages. Our two-stage predictor significantly outperforms existing methods that are based on a simple pixel counting strategy in terms of both accuracy and …


Model-Based Powertrain Design And Control System Development For The Ideal All-Wheel Drive Electric Vehicle, Haotian Wu Oct 2014

Model-Based Powertrain Design And Control System Development For The Ideal All-Wheel Drive Electric Vehicle, Haotian Wu

Open Access Dissertations

The transfer case based all-wheel drive electric vehicle (TCAWDEV) and dual-axle AWDEV have been investigated to balance concerns about energy consumption, drivability and stability of vehicles. However, the mentioned powertrain architectures have the torque windup issue or the wheel skidding issue. The torque windup is an inherent issue of mechanical linked all-wheel drive systems. The hydraulic motor-based or the electric motor-based ideal all-wheel drive powertrain can provide feasible solutions to the mentioned issues. An ideal AWDEV (IAWDEV) powertrain architecture and its control schemes were proposed by this research; the architecture has four independent driving motors in powertrain. The IAWDEV gives …


Role Of Group Ii Metabotropic Glutamate Receptor Subtype 2 (Mglur2) In Appetitive And Consummatory Aspects Of Ethanol Reinforcement, Kyle Allyson Windisch Oct 2014

Role Of Group Ii Metabotropic Glutamate Receptor Subtype 2 (Mglur2) In Appetitive And Consummatory Aspects Of Ethanol Reinforcement, Kyle Allyson Windisch

Open Access Dissertations

Background: Group II metabotropic glutamate receptors (mGluR2/3) are predominately presynaptically located Gi/o coupled receptors that are highly expressed in the cortex, nucleus accumbens, amygdala, and hippocampus. Previous studies suggest that group II mGluRs are involved in regulating ethanol (EtOH) consumption and seeking following extinction (Backstrom and Hyytia, 2005; Kufahl, et al., 2011). The sipper tube model, which allows for procedural separation of seeking and consumption, was used to further clarify the role of mGluR2/3 in EtOH-seeking and consumption. The non-selective group II mGluR agonist LY379268 (LY37) and selective mGluR2 positive allosteric modulator (PAM) BINA were used to determine the …


Crossflow Instability And Transition On A Circular Cone At Angle Of Attack In A Mach-6 Quiet Tunnel, Christopher A. C Ward Oct 2014

Crossflow Instability And Transition On A Circular Cone At Angle Of Attack In A Mach-6 Quiet Tunnel, Christopher A. C Ward

Open Access Dissertations

To investigate the effect of roughness on the stationary crossflow vortices, roughness elements 2 inches from the nosetip were created in a Torlon insert section of a 7-deg half-angle cone at 6-deg angle of attack in the Boeing/AFOSR Mach-6 Quiet Tunnel. Roughness elements with depths and diameters on the order of 500 microns were found to have a significant effect on the generation of the stationary vortices and the location of crossflow-induced transition under quiet flow. Crossflow-induced transition was measured under fully quiet flow. The controlled roughness elements also appeared to dominate the generation of the vortices, overwhelming the effect …


Image Analysis Using Visual Saliency With Applications In Hazmat Sign Detection And Recognition, Bin Zhao Oct 2014

Image Analysis Using Visual Saliency With Applications In Hazmat Sign Detection And Recognition, Bin Zhao

Open Access Dissertations

Visual saliency is the perceptual process that makes attractive objects "stand out" from their surroundings in the low-level human visual system. Visual saliency has been modeled as a preprocessing step of the human visual system for selecting the important visual information from a scene. We investigate bottom-up visual saliency using spectral analysis approaches. We present separate and composite model families that generalize existing frequency domain visual saliency models. We propose several frequency domain visual saliency models to generate saliency maps using new spectrum processing methods and an entropy-based saliency map selection approach. A group of saliency map candidates are then …


Ultrashort Laser Pulse-Matter Interaction: Fundamentals And Early Stage Plasma Dynamics, Xin Zhao Oct 2014

Ultrashort Laser Pulse-Matter Interaction: Fundamentals And Early Stage Plasma Dynamics, Xin Zhao

Open Access Dissertations

Despite extensive studies for many years, the detailed mechanisms of ultrashort laser pulse (USLP)-matter interaction are still not fully understood and further fundamental investigation is required. This study seeks to provide an improved understanding of the USLP-material interaction by both theoretical and experimental investigations and to find ways to enhance laser energy coupling with different materials.^ A two-dimensional comprehensive hydrodynamic model for USLP ablation of metals and semiconductors is developed in this study. The model comprises a two-temperature model and a hydrodynamic model supplemented with a quotidian equation of state model, considering the relevant multiphysical phenomena during the laser-matter interaction. …


Nano-Engineered Polymers In Drug Delivery: Potential Approaches For Attenuation Of Secondary Injury After Spinal Cord Trauma, Wen Gao Oct 2014

Nano-Engineered Polymers In Drug Delivery: Potential Approaches For Attenuation Of Secondary Injury After Spinal Cord Trauma, Wen Gao

Open Access Dissertations

Secondary injury elicits a complex series of pathophysiological events after the primary spinal cord trauma and even after its implantation treatment for neural functional recovery. These secondary injuries include an up-regulation of glial cells associated reactive oxygen species, nitrogen species, and reactive astrogliosis, and they can result in various levels of cellular and tissue damage. The inhibition of them has been proved to lead to functional recovery of the spinal cord. In this study, we concentrated on developing polymers and nano-techniques based drug delivery strategies to eliminate these secondary injuries. ^ To maintain and improve the performance of the implants …


Impact Of Anthropogenic Activities On Hydro-Climatological Variables, Kuk Hyun Ahn Oct 2014

Impact Of Anthropogenic Activities On Hydro-Climatological Variables, Kuk Hyun Ahn

Open Access Dissertations

The natural environment has been significantly affected by anthropogenic activities. Between 1700s and 2000s, agricultural land area had quintupled and the extent of natural vegetation was globally reduced by half. Furthermore many scientists argue that the recent rise in CO2 levels in the atmosphere is mainly due to anthropogenic activities. Anthropogenic activities may also play a crucial role in the change of the hydro-climatologic variables. In this study, impact of anthropogenic activities on two representative hydro-climatologic variables, temperature and streamflow, is investigated. The variations in temperature occur over larger spatial and time scale, and hence the United States is adopted …


Tunable Impedance Matching Network Fundamental Limits And Pracitical Considerations, Wesley N. Allen Oct 2014

Tunable Impedance Matching Network Fundamental Limits And Pracitical Considerations, Wesley N. Allen

Open Access Dissertations

As wireless devices continue to increase in utility while decreasing in dimension, design of the RF front-end becomes more complex. It is common for a single handheld device to operate on a plethora of frequency bands, utilize multiple antennae, and be subjected to a variety of environments. One complexity in particular which arises from these factors is that of impedance mismatch. Recently, tunable impedance matching networks have begun to be implemented to address this problem. ^ This dissertation presents the first in-depth study on the frequency tuning range of tunable impedance matching networks. Both the fundamental limitations of ideal networks …


Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz Oct 2014

Integrating Pro-Environmental Behavior With Transportation Network Modeling: User And System Level Strategies, Implementation, And Evaluation, Husain M. Abdul Aziz

Open Access Dissertations

Personal transport is a leading contributor to fossil fuel consumption and greenhouse (GHG) emissions in the U.S. The U.S. Energy Information Administration (EIA) reports that light-duty vehicles (LDV) are responsible for 61\% of all transportation related energy consumption in 2012, which is equivalent to 8.4 million barrels of oil (fossil fuel) per day. The carbon content in fossil fuels is the primary source of GHG emissions that links to the challenge associated with climate change. Evidently, it is high time to develop actionable and innovative strategies to reduce fuel consumption and GHG emissions from the road transportation networks. This dissertation …


Nano-Modification For High Performance Cement Composites With Cellulose Nanocrystals And Carbon Nanotubes, Yizheng Cao Oct 2014

Nano-Modification For High Performance Cement Composites With Cellulose Nanocrystals And Carbon Nanotubes, Yizheng Cao

Open Access Dissertations

One of the new engineering frontiers is the exploration of infrastructure materials with novel combinations of properties that break traditional paradigms. The goal of this study is to utilize two different nano-fibers, cellulose nanocrystals (CNCs) and carbon nanotubes (CNTs) to modify the nanoscale structures of cement composites and thereby improve the performance at the macro-level. This study also evaluates the mechanism behind the modification, since fiber bridging, the most common reinforcing mechanism for fiber-reinforced composites, cannot be simply applied because CNCs are too short to bridge cracks in cement composites. ^ The mechanical tests show an increase in the flexural …


Effects Of Energetic Irradiation On Materials And Devices Based On Graphene And Topological Insulators, Isaac Childres Oct 2014

Effects Of Energetic Irradiation On Materials And Devices Based On Graphene And Topological Insulators, Isaac Childres

Open Access Dissertations

This report focuses on the optical and electronic properties of graphene and topological insulators and how these Dirac fermion systems interact with energetic irradiation. We first present data exploring the effects of electron-beam and oxygen plasma induced disorder on the electronic properties and Raman spectra of graphene. These initial investigations were important for relating Raman peak intensities and weak localization features to each other and to an average disorder length in graphene, LD. ^ We then integrate gate-effect measurements into the Raman spectroscopy study to fully explore the relationships between carrier density, disorder and Raman spectrum signatures. We …


Irrigation With Treated Wastewater: Potential And Limitations, Anne Dare Oct 2014

Irrigation With Treated Wastewater: Potential And Limitations, Anne Dare

Open Access Dissertations

As the world population increases and resources become more coveted, water emerges as a key component to global food security. The Middle East and North Africa (MENA) is among the driest regions in the world: containing just one percent of the world's freshwater resources. An increasing population creates greater quantities of wastewater and demands greater quantities of food, so an obvious connection arises. However logical wastewater reuse may be for bridging the irrigation supply-demand gap in this arid region, significant limitations prevent widespread adoption. The overall goal of this research is to take a holistic view of the limitations facing …


Probabilistic Uncertainty Quantification And Experiment Design For Nonlinear Models: Applications In Systems Biology, Vu Cao Duy Thien Dinh Oct 2014

Probabilistic Uncertainty Quantification And Experiment Design For Nonlinear Models: Applications In Systems Biology, Vu Cao Duy Thien Dinh

Open Access Dissertations

Despite the ever-increasing interest in understanding biology at the system level, there are several factors that hinder studies and analyses of biological systems. First, unlike systems from other applied fields whose parameters can be effectively identified, biological systems are usually unidentifiable, even in the ideal case when all possible system outputs are known with high accuracy. Second, the presence of multivariate bifurcations often leads the system to behaviors that are completely different in nature. In such cases, system outputs (as function of parameters/inputs) are usually discontinuous or have sharp transitions across domains with different behaviors. Finally, models from systems biology …