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Articles 1 - 30 of 148
Full-Text Articles in Engineering
Reliability Analysis Of Nanocrystal Embedded High-K Nonvolatile Memories, Chia-Han Yang
Reliability Analysis Of Nanocrystal Embedded High-K Nonvolatile Memories, Chia-Han Yang
Doctoral Dissertations
The evolution of the MOSFET technology has been driven by the aggressive shrinkage of the device size to improve the device performance and to increase the circuit density. Currently, many research demonstrated that the continuous polycrystalline silicon film in the floating-gate dielectric could be replaced with nanocrystal (nc) embedded high-k thin film to minimize the charge loss due to the defective thin tunnel dielectric layer.
This research deals with both the statistical aspect of reliability and electrical aspect of reliability characterization as well. In this study, the Zr-doped HfO2 (ZrHfO) high-k MOS capacitors, which separately contain the nanocrystalline zinc …
Extending Depth Of Field Via Multifocus Fusion, Harishwaran Hariharan
Extending Depth Of Field Via Multifocus Fusion, Harishwaran Hariharan
Doctoral Dissertations
In digital imaging systems, due to the nature of the optics involved, the depth of field is constricted in the field of view. Parts of the scene are in focus while others are defocused. Here, a framework of versatile data-driven application independent methods to extend the depth of field in digital imaging systems is presented. The principal contributions in this effort are the use of focal connectivity, the direct use of curvelets and features extracted by Empirical Mode Decomposition, namely Intrinsic Mode Images, for multifocus fusion. The input images are decomposed into focally connected components, peripheral and medial coefficients and …
Processing, Microstructures, And Properties Of Aluminide-Strengthened Ferritic Steels, Zhenke Teng
Processing, Microstructures, And Properties Of Aluminide-Strengthened Ferritic Steels, Zhenke Teng
Doctoral Dissertations
NiAl-strengthened ferritic steel is a material of interest for steam turbine applications due to their promising creep resistance, high thermal conductivity, low cost and thermal expansion coefficient. However, there are two critical issues restricting their applications: low room temperature ductility and limited creep resistance at temperatures higher than 600°C. The reasons for these behaviors have not been fully understood, especially the processing-microstructure-property relationship has not been clearly identified.
The alloys were designed, fabricated, and processed, according to the required microstructures and properties. The matrix and precipitates can be thoroughly characterized by a combination of techniques, including atom probe tomography, neutron …
Computational And Experimental Study Of Structure-Property Relationships In Nial Precipitate-Strengthened Ferritic Superalloys, Shenyan Huang
Computational And Experimental Study Of Structure-Property Relationships In Nial Precipitate-Strengthened Ferritic Superalloys, Shenyan Huang
Doctoral Dissertations
Ferritic superalloys strengthened by coherent ordered NiAl B2-type precipitates are promising candidates for ultra-supercritical steam-turbine applications, due to their superior resistance to creep, coarsening, oxidation, and steam corrosion as compared to Cr ferritic steels at high temperatures. Combined computational and experimental tools have been employed to investigate the interrelationships among the composition, microstructure, and mechanical behavior, and provide insight into deformation micromechanisms at elevated temperatures.
Self and impurity diffusivities in a body-centered-cubic (bcc) iron are calculated using first-principles methods. Calculated self and impurity diffusivities compare favorably with experimental measurements in both ferromagnetic and paramagnetic states of bcc Fe. The calculated …
Wide Baseline Stereo Image Rectification And Matching, Wei Hao
Wide Baseline Stereo Image Rectification And Matching, Wei Hao
Doctoral Dissertations
Perception of depth information is central to three-dimensional (3D) vision problems. Stereopsis is an important passive vision technique for depth perception. Wide baseline stereo is a challenging problem that attracts much interest recently from both the theoretical and application perspectives. In this research we approach the problem of wide baseline stereo using the geometric and structural constraints within feature sets.
The major contribution of this dissertation is that we proposed and implemented a more efficient paradigm to handle the challenges introduced by perspective distortion in wide baseline stereo, compared to the state-of-the-art. To facilitate the paradigm, a new feature-matching algorithm …
Robust Multichannel Functional-Data-Analysis Methods For Data Recovery In Complex Systems, Jian Sun
Robust Multichannel Functional-Data-Analysis Methods For Data Recovery In Complex Systems, Jian Sun
Doctoral Dissertations
In recent years, Condition Monitoring (CM), which can be performed via several sensor channels, has been recognized as an effective paradigm for failure prevention of operational equipment or processes. However, the complexity caused by asynchronous data collection with different and/or time-varying sampling/transmission rates has long been a hindrance in the effective use of multichannel data in constructing empirical models. The problem becomes more challenging when sensor readings are incomplete. Traditional sensor data recovery techniques are often prohibited in asynchronous CM environments, not to mention sparse datasets. The proposed Functional Principal Component Analysis (FPCA) methodologies, e.g., nonparametric FPC model and semi-parametric …
Shear-Band Formation And Thermal Activation In Metallic Glasses, Lu Wang
Shear-Band Formation And Thermal Activation In Metallic Glasses, Lu Wang
Doctoral Dissertations
Metallic glasses (MGs) usually have high strength, high hardness and high elastic strain limit. However, the deformation mode and mechanism in metallic glasses are radically different from those in conventional crystalline materials with a long-range ordered structure. For crystalline materials, the intrinsic relationship between their mechanical properties and crystal structures has been well described by dislocation theory. In contrast, for amorphous materials, theories on the structures and controlling factors of localized shear-band formation are far from being complete.
In this thesis, shear-banding behavior of MGs under nanoindentation was first reviewed. The hardness of MGs was found to be independent on …
Micromechanical Studies Of Intergranular Strain And Lattice Misorientation Fields And Comparisons To Advanced Diffraction Measurements, Lili Zheng
Doctoral Dissertations
Inhomogeneous deformation fields arising from the grain-grain interactions in polycrystalline materials have been evaluated using a crystal plasticity finite element method and extensively compared to neutron diffraction measurements under fatigue crack growth conditions. The roles of intergranular deformation anisotropy, grain boundary damage, and non-common deformation mechanisms (such as twinning for hexagonal close packed crystals) are systematically evaluated. The lattice misorientation field can be used to determine the intragranular deformation behavior in polycrystals or to describe the deformation inhomogeneity due to dislocation plasticity in single crystals. The study of indentation-induced lattice misorientation fields in single crystals sheds lights on the understanding …
Nanoscale Metal Thin Film Dewetting Via Nanosecond Laser Melting: Understanding Instabilities And Materials Transport In Patterned Thin Films, Yueying Wu
Doctoral Dissertations
Nanoscale metal thin film dewetting via laser treatment is studied in this dissertation. The purpose is to understand: 1) the spatial and temporal nature of intrinsic instabilities; and 2) mass transportation involved in dewetting pattern evolution in metal thin films as well as in lithographically patterned nanostructures; and finally 3) to explore advanced control of metallic nanostructure fabrication via the confluence of top down nanolithography and pulsed laser induced dewetting. This study includes three sections. In first section, thin film Cu-Ni alloys ranging from 2-8nm were synthesized and laser irradiated. The evolution of the spinodal dewetting process is investigated as …
Design And Control Of High Power Density Motor Drive, Dong Jiang
Design And Control Of High Power Density Motor Drive, Dong Jiang
Doctoral Dissertations
This dissertation aims at developing techniques to achieve high power density in motor drives under the performance requirements for transportation system. Four main factors influencing the power density are the main objects of the dissertation: devices, passive components, pulse width modulation (PWM) methods and motor control methods.
Firstly, the application of SiC devices could improve the power density of the motor drive. This dissertation developed a method of characterizing the SiC device performance in phase-leg with loss estimation, and claimed that with SiC Schottky Barrier Diode the advantage of SiC JFET could benefit the motor drive especially at high temperature. …
Wide-Area Situational Awareness Application Developments, Yanzhu Ye
Wide-Area Situational Awareness Application Developments, Yanzhu Ye
Doctoral Dissertations
This dissertation expands the topics from the wide-area situational awareness application development, system architecture design, to power system disturbance analysis. All the works are grounded on the wide-area Frequency Monitoring Network (FNET). The FNET system takes GPS-synchronized wide-area measurements in a low-cost, easily deployable manner at 120V single-phase power outlet. These synchronized observations enables the monitoring of bulk power systems, and provides critical information for understanding power system disturbances and system operations.
Firstly, the work addresses the viability of angle measurement to serve different types of situational awareness applications, including the development of new angle-based event location estimation methods, the …
Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar
Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar
Doctoral Dissertations
The ionomer-membrane interface in a membrane electrode assembly connects the catalyst and membrane and allows hydrated protons to move between the catalyst and membrane. The continuous operation of the polymer membrane electrolyte fuel cell at high temperature and/or in frequent freeze/thaw cycles leads to membrane degradation and delamination of the interface, which lower the proton conductivity. In this dissertation, we modeled the chemical degradation and proton conductivity of perfluorosulfonic acid (PFSA) ionomers by ab initio calculations and macroscopic modeling. All ab initio calculations were performed using Gaussian 03 suites of program by employing B3LYP/6-311++G** method/basis set. The macroscopic modeling involves …
Wide-Area Measurement Application And Power System Dynamics, Lang Chen
Wide-Area Measurement Application And Power System Dynamics, Lang Chen
Doctoral Dissertations
Frequency monitoring network (FNET) is a GPS-synchronized distribution-level phasor measurement system. It is a powerful synchronized monitoring network for large-area power systems that provides significant information and data for power system situational awareness, real time and post-event analysis, and other important aspects of bulk systems. This work explored FNET measurements and utilized them for different applications and power system analysis.
An island system was built and validated with FNET measurements to study the stability of the OTEC integration. FNET measurements were also used to validate a large system model like the U.S. Eastern Interconnection. It tries to match the simulation …
Packaging Design Of Igbt Power Module Using Novel Switching Cells, Shengnan Li
Packaging Design Of Igbt Power Module Using Novel Switching Cells, Shengnan Li
Doctoral Dissertations
Parasitic inductance in power modules generates voltage spikes and current ringing during switching which cause extra stress in power electronic devices, increase electromagnetic interference (EMI), and degrade the performance of the power converter system. As newer power devices have faster switching speeds and higher power ratings, the effect of the parasitic inductance of the power module is more pronounced. This dissertation proposes a novel packaging method for power electronics modules based on the concepts of novel switching cells: P-cell and N-cell. It can reduce the stray inductance in the current commutation path in a phase-leg module and hence improve the …
Building Effective Ontology For Semantic Web: A Discussion Based On Practical Examples, Tianmu Zhang
Building Effective Ontology For Semantic Web: A Discussion Based On Practical Examples, Tianmu Zhang
School of Information Sciences -- Faculty Publications and Other Works
The study aims to investigate semantic web and create useful ontology as a teaching and educational tool for others interested in learning more about Semantic web. This paper discussed several emerging issues about the semantic web and ontology building. This paper combines ontology implementation examples with research topics to identify current issues and potential solution in both application and theoretical level. It concludes that although semantic web and ontology technology are not mature enough currently, there is a clear tendency for them to be integrated into various applications to exert synergies.
Design Of Wireless Power Transfer And Data Telemetry System For Biomedical Applications, Ashraf Bin Islam
Design Of Wireless Power Transfer And Data Telemetry System For Biomedical Applications, Ashraf Bin Islam
Doctoral Dissertations
With the advancement of biomedical instrumentation technologies sensor based remote healthcare monitoring system is gaining more attention day by day. In this system wearable and implantable sensors are placed outside or inside of the human body. Certain sensors are needed to be placed inside the human body to acquire the information on the vital physiological phenomena such as glucose, lactate, pH, oxygen, etc. These implantable sensors have associated circuits for sensor signal processing and data transmission. Powering the circuit is always a crucial design issue. Batteries cannot be used in implantable sensors which can come in contact with the blood …
Introducing Water Vapor Into A High Vacuum Chamber At Aedc., James Philip Rogers
Introducing Water Vapor Into A High Vacuum Chamber At Aedc., James Philip Rogers
Masters Theses
A powdered form of calcium sulfate dihydrate (CaSO42H2O) was heated to provide water vapor in a vacuum chamber for an experiment seeking to study cryodeposit thin films of ice at the Arnold Engineering Development Center (AEDC) in Tullahoma, TN. However, after the test was conducted, calcium sulfate deposits were found on all surfaces inside the vacuum chamber. It became clear that a new procedure for introducing the water vapor into the vacuum chamber needed to be developed. Calcium sulfate dihydrate, cobalt(II) chloride hexahydrate and 3 angstrom zeolite molecular sieves were investigated to determine how they could …
Automating Real-Time Fault Detection For The University Of Tennessee Space Institute, Aviation Systems’ Flight Testing And Airborne Science Applications, Samuel Vivek Williams
Automating Real-Time Fault Detection For The University Of Tennessee Space Institute, Aviation Systems’ Flight Testing And Airborne Science Applications, Samuel Vivek Williams
Masters Theses
The UTSI Aviation Systems program has conducted many successful airborne science campaigns in collaboration with premier research organizations including NASA and NOAA. Each airborne science mission requires dedicated FTEs to monitor the various instruments onboard the aircraft. A typical mission requires aircraft to be instrumented with a wide range of sensors (with approximately 145 data parameters). Monitoring the instruments requires highly skilled personnel who have a thorough understanding of the system.
With the advent of UTSI Aviation Systems program increasing capabilities to conduct multiple missions, using multiple airborne platforms, the requirement of a skilled FTE for each mission could effectively …
Failure Analysis Of Leaking Stainless Steel Pump Casing, Mary E. Parker
Failure Analysis Of Leaking Stainless Steel Pump Casing, Mary E. Parker
Chancellor’s Honors Program Projects
No abstract provided.
Residential Attic Ventilation In A Hot And Humid Climate: Effects Of Increased Ventilation On Thermal Performance And Moisture Control, Stanley Arthur Atherton
Residential Attic Ventilation In A Hot And Humid Climate: Effects Of Increased Ventilation On Thermal Performance And Moisture Control, Stanley Arthur Atherton
Masters Theses
The reality of the effect of natural ventilation in a residential attic cavity has been the topic of many debates and scholarly reports since the 1930’s. The purpose of ventilating an attic cavity is to prevent collection of condensate on the structural surfaces, and to create a thermal buffer between the conditioned space and the ambient air. The current standards are not specific to climate zone, despite the fact that each climate zone may require ventilation for very different reasons.
To address the issue of ventilation effects in a hot and humid climate, a Natural Exposure Testing facility was constructed …
Development Of An Environmental Monitoring System For Greenhouse Disease Management, Crystal Marie Kelly
Development Of An Environmental Monitoring System For Greenhouse Disease Management, Crystal Marie Kelly
Masters Theses
A commercial African violet (Saintpaulia ionantha) grower experiences yield loss due to a leaf spot disease known as Corynespora casssiicola. Spotted leaves make the plants unmarketable. Outbreaks of the disease are costly and difficult to prevent. Greenhouse monitoring systems currently available on the commercial market do not have sufficient spatial or temporal resolution to be able to correlate the environmental conditions of the greenhouse with disease outbreaks. A new system was designed specifically to monitor for disease favorable conditions. The system developed for this project consists of several sensor stations and a coordinator station. The coordinator station …
Distributed Data Aggregation For Sparse Recovery In Wireless Sensor Networks, Shuangjiang Li
Distributed Data Aggregation For Sparse Recovery In Wireless Sensor Networks, Shuangjiang Li
Masters Theses
We consider the approximate sparse recovery problem in Wireless Sensor Networks (WSNs) using Compressed Sensing/Compressive Sampling (CS). The goal is to recover the $n \mbox{-}$dimensional data values by querying only $m \ll n$ sensors based on some linear projection of sensor readings. To solve this problem, a two-tiered sampling model is considered and a novel distributed compressive sparse sampling (DCSS) algorithm is proposed based on sparse binary CS measurement matrix. In the two-tiered sampling model, each sensor first samples the environment independently. Then the fusion center (FC), acting as a pseudo-sensor, samples the sensor network to select a subset of …
Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang
Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang
Masters Theses
Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for patients with cerebral palsy; however, a crouched posture may afford biomechanical advantages that lead some patients to adopt a crouch gait.
To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle. A series of optimizations were performed for each posture to maximize ground reaction forces for the …
Aeolian Simulations: A Comparison Of Numerical And Experimental Results, With Projections For Titan., Oscar Lee Mathews
Aeolian Simulations: A Comparison Of Numerical And Experimental Results, With Projections For Titan., Oscar Lee Mathews
Masters Theses
Aeolian processes are major determinants of geomorphology on bodies in the Solar System possessing an atmosphere-surface interface and transportable sediment, including Earth, Mars, Venus, and Titan. Substantial efforts have been made over the last few decades to understand these processes using specialized wind tunnels, field studies, and, more recently, numerical simulations. This thesis describes a model of aeolian sediment transport using computational fluid dynamics (CFD), and compares the results with those obtained in the Martian Surface Wind Tunnel (MARSWIT) testing conducted in the Planetary Aeolian Laboratory at NASA Ames Research Center. The ultimate goal of the thesis was to develop …
Thermocouple Temperature Measurements For Twin Jet Thermal Mixing, Spero Michael Peters
Thermocouple Temperature Measurements For Twin Jet Thermal Mixing, Spero Michael Peters
Masters Theses
Thermocouples are commonly used devices for temperature measurement. This study concerns the implementation of thermocouples to collect thermal mixing data in an environment in which two parallel water jets are mixing. The measurements are taken with the purpose of modeling the jet mixing region so that Computational Fluid Dynamics (CFD) models can be validated against the test data. This thesis covers the design, construction, implementation and evaluation of a thermocouple system for immersion in a water environment to measure the thermal mixing of twin jets.
The measurement system being used is a thermocouple rake whose design and fabrication is covered. …
Automated Visual Monitoring Of Machining Equipment, Timothy Wayne Ragland
Automated Visual Monitoring Of Machining Equipment, Timothy Wayne Ragland
Masters Theses
Metalworking equipment is designed to modify a sheet, rod, or block of metal material in order to shape it for a specific application. This equipment can operate on the metal by bending it, drilling through it, or by cutting it. For small-scale operations, many tools require a significant amount of manual input. Unless the operator has extensive training and experience, the manual input may not be precise enough for fine details that may be needed in some applications. For example, with a bending brake, obtaining an accurate angle for the bend may be quite difficult. For a particular application, an …
U.S Inflight Icing Accidents And Incidents, 2006 To 2010., Philip Appiah-Kubi
U.S Inflight Icing Accidents And Incidents, 2006 To 2010., Philip Appiah-Kubi
Masters Theses
Through its recommendations, the National Transportation Safety Board (NTSB) has helped the Federal Aviation Administration (FAA) introduce regulations that have helped to curtail icing accidents1 (an occurrence associated with the operation of an aircraft where as a result of the operation of an aircraft, any person receives fatal or serious injury or any aircraft receives substantial damage) and incidents1 (an occurrence, other than an accident, associated with the operation of an aircraft that affects or could affect the safety of operations). However, "the only acceptable safety goal of zero accident," proposed by former Secretary of Transportation, Federico Fabian Pena, has …
Potential Impacts Of Climate Change On Water Resources And Water Quality Of Norris Lake, Tennessee, Yong-Gil Choi
Potential Impacts Of Climate Change On Water Resources And Water Quality Of Norris Lake, Tennessee, Yong-Gil Choi
Masters Theses
This study assessed the potential impacts of climate change on hydrology, water resources operation, and water quality of the Norris Lake area in Tennessee. To project future climate conditions, the simulation outputs for 2030s, 2050s, and 2070s from six general circulation models (GCMs) were extracted under two Intergovernmental Panel on Climate Change (IPCC) greenhouse gases emissions scenarios (A2 and B1 for high and low emissions, respectively) to consider the range of uncertainty. The outputs of the six GCMs were weighted by considering their accuracy to simulate the climate conditions observed from 1961 to 1990 to suggest an ensemble average. A …
Particle Shielding For Human Spaceflight: Electrostatic Potential Effects On The Störmer Magnetic Dipole Exclusion Region, Benjamin Alan Klamm
Particle Shielding For Human Spaceflight: Electrostatic Potential Effects On The Störmer Magnetic Dipole Exclusion Region, Benjamin Alan Klamm
Masters Theses
A basic hybrid radiation shield concept, consisting of both a monopole positive electrostatic potential barrier and a current-carrying superconducting solenoid, was predicted to provide a more effective method of shielding a habitable torus region than a solenoid acting alone. A randomized position and velocity vector simulation of equal-energy iron ions using a Lagrangian reference frame was performed on the exact magnetic field integral for the solenoid and a discrete summation electrostatic field for a toroidal monopole array approximating a potential surface. Each particle is injected at a specific energy (100, 150 MeV and 1 GeV). Two cases were evaluated at …
Power Management For Gpu-Cpu Heterogeneous Systems, Xue Li
Power Management For Gpu-Cpu Heterogeneous Systems, Xue Li
Masters Theses
In recent years, GPU-CPU heterogeneous architectures have been increasingly adopted in high performance computing, because of their capabilities of providing high computational throughput. However, current research focuses mainly on the performance aspects of GPU-CPU architectures, while improving the energy efficiency of such systems receives much less attention. There are few existing efforts that try to lower the energy consumption of GPU-CPU architectures, but they address either GPU or CPU in an isolated manner and thus cannot achieve maximized energy savings. In this paper, we propose GreenGPU, a holistic energy management framework for GPU-CPU heterogeneous architectures. Our solution features a two-tier …