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Full-Text Articles in Engineering

Control And Optimization Of Power In Llc Converter Using Phase Control, Nagasri Kollipara Jan 2018

Control And Optimization Of Power In Llc Converter Using Phase Control, Nagasri Kollipara

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LLC resonant converters are popular among resonant topologies due to their high efficiency and ability to achieve ZVS and ZCS for wide input range. LLC resonant converters are controlled by frequency modulation (FM), which makes converter difficult to optimize the system in terms of achieving efficient power conversion. FM technique also generate wide range of harmonics which leads to a wide sweep in operating frequency, which can run into regulatory EMI test limits and cause electromagnetic compatibility issues. The performance of LLC topology extends to their poor efficiency at lighter loads, due to constant high magnetization current. In order to …

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Content-Based Clustering And Visualization Of Social Media Text Messages, Sydney A. Barnard Jan 2018

Content-Based Clustering And Visualization Of Social Media Text Messages, Sydney A. Barnard

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Although Twitter has been around for more than ten years, crisis management agencies and first response personnel are not able to fully use the information this type of data provides during a crisis or natural disaster. This thesis addresses clustering and visualizing social media data by textual similarity, rather than by only time and location, as a tool for first responders. This thesis presents a tool that automatically clusters geotagged text data based on their content and displays the clusters and their locations on the map. It allows at-a-glance information to be displayed throughout the evolution of a crisis. For …

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Measurement Of Unsteady Characteristics Of Endwall Vortices Using Surface-Mounted Hot-Film Sensors, Emma Michelle Veley Jan 2018

Measurement Of Unsteady Characteristics Of Endwall Vortices Using Surface-Mounted Hot-Film Sensors, Emma Michelle Veley

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High-lift low-pressure turbine blades produce significant losses at the junction with the endwall. The losses are caused by several complex three-dimensional vortical flow structures, which interact with the blade suction surface boundary layer. This study investigates the unsteady characteristics of these endwall flow structures on a highly loaded research profile and the adjacent endwall using surface-mounted hot-film sensors. Experiments were conducted in a low-speed linear cascade wind tunnel. The front-loaded blade profile was subjected to three different inlet conditions, consisting of two turbulence levels, and three incoming boundary layer thicknesses. Multiple surface-mounted hot-film sensors were installed throughout the passage. This …

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Electronic And Crystalline Characteristics Of Mixed Metal Halide Perovskite Semiconductor Films, Patrick Joseph Cleaver Jan 2018

Electronic And Crystalline Characteristics Of Mixed Metal Halide Perovskite Semiconductor Films, Patrick Joseph Cleaver

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Solar technology has a long history of incremental improvements in cost, reliability and efficiency. However, solar cells based on lead halide perovskite films have made more rapid leaps forward in the past 10 years, making it the fastest growing solar technology in terms of efficiency. Leaders in academia and industry continue to find success in overcoming manufacturability and stability issues, but have not yet discovered a high-efficiency perovskite film without the use of toxic lead. Probing less toxic analogs to the highly efficient lead halide, a series of thin films with perovskite structures, i.e. A2BB’X6 where A = Cs or …

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Examination Of Gain Scheduling And Fuzzy Controllers With Hybrid Reachability, Aaron W. Fifarek Jan 2018

Examination Of Gain Scheduling And Fuzzy Controllers With Hybrid Reachability, Aaron W. Fifarek

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Modern aircraft with nonlinear flight envelopes predominately utilize gain scheduled controllers to provide stability of flight. Using gain scheduled control techniques, nonlinear envelopes can be linearized into collections of linear systems that operate under various system dynamics. Linear controllers approximate the nonlinear response over setpoints of operating conditions which allow traditional linear theory to be applied to maintain stability. Techniques to prove linear stability are well understood and realized in control systems, but when controllers are switched, interpolation methods must be used. Interpolation is necessary as gain scheduled systems do not have foundational switching paradigms as part of their realization …

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Analyzing A Shopper’S Visual Experience In A Retail Store And The Impact On Impulse Profit, Bradley Robert Guthrie Jan 2018

Analyzing A Shopper’S Visual Experience In A Retail Store And The Impact On Impulse Profit, Bradley Robert Guthrie

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The retail industry in the U.S. contributed 1.14 trillion in value added (or 5.9%) to the GDP in 2017, an increase of 3.7% from the previous year. While store closures have dominated the news in the recent past (e.g., Toys-R-Us, Sears, and Bon-Ton) due to ineffective supply chain practices, inadequate in-store experiences, and competition from e-tailers, other retailers such as Ross, T. J. Maxx, Burlington Coat Factory, and Kroger have been expanding their footprint. Brick-and-mortar stores are unique as they allow shoppers the ability to see, touch, and try products, in addition to exploring new products. Kohl’s CEO has even …

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Influence Of Fdm Build Parameters On Tensile And Compression Behaviors Of 3d Printed Polymer Lattice Structures, Sai Avinash Yadlapati Jan 2018

Influence Of Fdm Build Parameters On Tensile And Compression Behaviors Of 3d Printed Polymer Lattice Structures, Sai Avinash Yadlapati

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This research focuses on the compression and tensile behavior of three-dimensional printed polymer lattice structures with different printing parameters such as build orientation, infill density, and layer thickness. The body-centered cubic (BCC) lattice unit cell, which has been extensively investigated for energy absorption applications, is considered here to create compression and tensile specimens. Special test fixture was designed and developed to perform the tensile tests. The specimens were printed using Acrylonitrile Butadiene Styrene (ABS) polymer material on a Stratasys uPrint 3D printer. The printing parameters considered in this case are: (a) Three different build orientations (0, 45 and 90 degrees); …

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Verifying Data-Oriented Gadgets In Binary Programs To Build Data-Only Exploits, Zachary David Sisco Jan 2018

Verifying Data-Oriented Gadgets In Binary Programs To Build Data-Only Exploits, Zachary David Sisco

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Data-Oriented Programming (DOP) is a data-only code-reuse exploit technique that "stitches" together sequences of instructions to alter a program's data flow to cause harm. DOP attacks are difficult to mitigate because they respect the legitimate control flow of a program and by-pass memory protection schemes such as Address Space Layout Randomization, Data Execution Prevention, and Control Flow Integrity. Techniques that describe how to build DOP payloads rely on a program's source code. This research explores the feasibility of constructing DOP exploits without source code-that is, using only binary representations of programs. The lack of semantic and type information introduces difficulties …

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A Semantically Enhanced Approach To Identify Depression-Indicative Symptoms Using Twitter Data, Ankita Saxena Jan 2018

A Semantically Enhanced Approach To Identify Depression-Indicative Symptoms Using Twitter Data, Ankita Saxena

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According to the World Health Organization, more than 300 million people suffer from Major Depressive Disorder (MDD) worldwide. PHQ-9 is used to screen and diagnose MDD clinically and identify its severity. With the unprecedented growth and enthusiastic acceptance of social media such as Twitter, a large number of people have come to share their feelings and emotions on it openly. Each tweet can indicate a user's opinion, thought or feeling. A tweet can also indicate multiple symptoms related to PHQ-9. Identifying PHQ-9 symptoms indicated by a tweet can provide crucial information about a user regarding his/her depression diagnosis. The current …

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Hierarchical Hybrid Architectures For Robust And Reusable Nano-Devices, Sharmila M. Mukhopadhyay Jan 2018

Hierarchical Hybrid Architectures For Robust And Reusable Nano-Devices, Sharmila M. Mukhopadhyay

Mechanical and Materials Engineering Faculty Publications

No abstract provided.

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An Uncertainty-Aware Visual System For Image Pre-Processing, Christina Gillmann, Pablo Arbelaez, Jose Tiberio Hernandez, Hans Hagen, Thomas Wischgoll Jan 2018

An Uncertainty-Aware Visual System For Image Pre-Processing, Christina Gillmann, Pablo Arbelaez, Jose Tiberio Hernandez, Hans Hagen, Thomas Wischgoll

Computer Science and Engineering Faculty Publications

Due to image reconstruction process of all image capturing methods, image data is inherently affected by uncertainty. This is caused by the underlying image reconstruction model, that is not capable to map all physical properties in its entirety. In order to be aware of these effects, image uncertainty needs to be quantified and propagated along the entire image processing pipeline. In classical image processing methodologies, pre-processing algorithms do not consider this information. Therefore, this paper presents an uncertainty-aware image pre-processing paradigm, that is aware of the input image’s uncertainty and propagates it trough the entire pipeline. To accomplish this, we …

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Towards An Image-Based Indicator For Pad Classification And Localization, Christina Gillmann, Johh H. Matsuura, Hans Hagen, Thomas Wischgoll Jan 2018

Towards An Image-Based Indicator For Pad Classification And Localization, Christina Gillmann, Johh H. Matsuura, Hans Hagen, Thomas Wischgoll

Computer Science and Engineering Faculty Publications

Peripheral Artery Disease (PAD) is an often occurring problem caused by narrowed veins. With this type of disease, mostly the legs receive an insufficient supply of blood to sustain their functions. This can result in an amputation of extremities or strokes. In order to quantify the risks, doctors onsult a classification table which is based on the pain response of a patient. This classification is subjective and does not indicate the exact origin of the PAD symptoms. Resulting from this, complications can occur unprompted. We present the first results for an image-based indicator assisting medical doctors in estimating the stage …

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In Vitro Assessment Of The Effects Of Valvular Stenosis On Aorta Hemodynamics And Left Ventricular Function, Ashish Madan Jan 2018

In Vitro Assessment Of The Effects Of Valvular Stenosis On Aorta Hemodynamics And Left Ventricular Function, Ashish Madan

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Calcific aortic stenosis (CAS) is the most common valvular heart disease and is associated with aortopathy and ventricular dysfunction. Hemodynamic alterations due CAS could affect the aorta lining (endothelium), that is in direct contact with the blood, triggering adverse biological responses that may possibly cause aortic dilation and dissection. Also, CAS could impose excessive ventricular load leading to ventricular wall thickening, thus putting an individual at a higher risk of heart attack or stroke. These pathophysiological effects of CAS are highly dependent on the degree of calcification. However, the impact of CAS development on aorta flow and left ventricular workload …

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Chaotic Based Self-Synchronization For Rf Steganography Radar/Communication Waveform, Michael A. Gonnella Jan 2018

Chaotic Based Self-Synchronization For Rf Steganography Radar/Communication Waveform, Michael A. Gonnella

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In this project, we continue previous CSR project entitled RF Steganography based Joint Radar/Communication Waveform Design to develop a bio-inspired secure low probability detection (LPD) radio frequency (RF) waveform that can serve multiple purposes simultaneously. Previously, we have developed an RF steganography based RF waveform to conceal a secure digital communication within a linear frequency modulated (LFM) chirp radar signal. By exploiting novel reduced phase shift keying modulation and variable symbol duration, the new waveform is resistant to time domain analysis, frequency domain analysis and cyclostationary analysis. However, to demodulate the hidden communication message, the intended receiver has to know …

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Caregiver Assessment Using Smart Gaming Technology: A Preliminary Approach, Garrett Goodman, Tanvi Banerjee, William Romine, Cogan Shimizu, Jennifer Hughes Jan 2018

Caregiver Assessment Using Smart Gaming Technology: A Preliminary Approach, Garrett Goodman, Tanvi Banerjee, William Romine, Cogan Shimizu, Jennifer Hughes

Computer Science and Engineering Faculty Publications

As pre-diagnostic technologies are becoming increasingly accessible, using them to improve the quality of care available to dementia patients and their caregivers is of increasing interest. Specifically, we aim to develop a tool for non- invasively assessing task performance in a simple gaming application. To address this, we have developed Caregiver Assessment using Smart Technology (CAST), a mobile application that personalizes a traditional word scramble game. Its core functionality uses a Fuzzy Inference System (FIS) optimized via a Genetic Algorithm (GA) to provide customized performance measures for each user of the system. With CAST, we match the relative level of …

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Coupling Of Mechanical And Electromagnetic Fields Stimulation For Bone Tissue Engineering, Alyaa I. Aldebs Jan 2018

Coupling Of Mechanical And Electromagnetic Fields Stimulation For Bone Tissue Engineering, Alyaa I. Aldebs

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Alternative bone regeneration strategies that do not rely on harvested tissue or exogenous growth factors and cells are badly needed. However, creating living tissue constructs that are structurally, functionally and mechanically comparable to the natural bone has been a challenge so far. A major hurdle has been recreating the bone tissue microenvironment using the appropriate combination of cells, scaffold and stimulation to direct differentiation. This project presents a bone regeneration formulation that involves the use of human adipose-derived mesenchymal stems cells (hASCs) and a 3D scaffold based on a self-assembled peptide hydrogel doped with superparamagnetic nanoparticles (NPs). Osteogenic differentiation of …

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Mechanical Annealing Of Model Glasses: Effects Of Strain Amplitude And Temperature, Nikolai V. Priezjev Jan 2018

Mechanical Annealing Of Model Glasses: Effects Of Strain Amplitude And Temperature, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

Molecular dynamics simulations are performed to examine the dynamic response of amorphous solids to oscillatory shear at finite temperatures. The data were collected from a poorly annealed binary glass, which was deformed periodically in the elastic regime during several hundred shear cycles. We found that the characteristic time required to reach a steady state with a minimum potential energy is longer at higher temperatures and larger strain amplitudes. With decreasing strain amplitude, the asymptotic value of the potential energy increases but it remains lower than in quiescent samples. The transient decay of the potential energy correlates well with a gradual …

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Feed-Forward Compensation Of Non-Minimum Phase Systems, Venkatesh Dudiki Jan 2018

Feed-Forward Compensation Of Non-Minimum Phase Systems, Venkatesh Dudiki

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Due to inherent limitations posed by existence of zeros of a transfer function in the righthalfof the complex plane, known as non-minimum phase zeros, the issue of dealing withsuch zeros is extremely important in control of linear systems. Considerable literatureexists in control theory to try and minimize or eliminate the effect of non-minimum phasezeros. These include pole-zero cancellation, feedforward compensation, among others.These methods are only limited only to stable systems (systems with poles in the left halfof the complex plane); and will fail for systems that are unstable as well as non-minimumphase.This research focuses in designing feedforward compensators for unstable …

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Divergent Scaling Of Miniature Excitatory Post-Synaptic Current Amplitudes In Homeostatic Plasticity, Amanda L. Hanes Jan 2018

Divergent Scaling Of Miniature Excitatory Post-Synaptic Current Amplitudes In Homeostatic Plasticity, Amanda L. Hanes

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Synaptic plasticity, the ability of neurons to modulate their inputs in response to changing stimuli, occurs in two forms which have opposing effects on synaptic physiology. Hebbian plasticity induces rapid, persistent changes at individual synapses in a positive feedback manner. Homeostatic plasticity is a negative feedback effect that responds to chronic changes in network activity by inducing opposing, network-wide changes in synaptic strength and restoring activity to its original level. The changes in synaptic strength can be measured as changes in the amplitudes of miniature post-synaptic excitatory currents (mEPSCs). Together, the two forms of plasticity underpin nervous system functions such …

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Temperature Robust Longwave Infrared Hyperspectral Change Detection, Nicholas A. Durkee Jan 2018

Temperature Robust Longwave Infrared Hyperspectral Change Detection, Nicholas A. Durkee

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In this thesis, we develop and evaluate change detection algorithms for longwave infrared (LWIR) hyperspectral imagery. Because measured radiance in the LWIR domain depends on unknown surface temperature, care must be taken to prevent false alarms resulting from in-scene temperature differences that appear as material changes. We consider fewer variables. Examples using synthetic and measured data quantify the computational complexity of the proposed methods and demonstrate orders of magnitude reduction in false alarm rates relative to existing methods. Four strategies to mitigate this effect. In the first, pre-processing via traditional temperatureemissivity separation yields approximately temperature-invariant emissivity vectors for use in …

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A Stochastic Petri Net Reverse Engineering Methodology For Deep Understanding Of Technical Documents, Giorgia Rematska Jan 2018

A Stochastic Petri Net Reverse Engineering Methodology For Deep Understanding Of Technical Documents, Giorgia Rematska

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Systems Reverse Engineering has gained great attention over time and is associated with numerous different research areas. The importance of this research derives from several technological necessities. Security analysis and learning purposes are two of them and can greatly benefit from reverse engineering. More specifically, reverse engineering of technical documents for deeper automatic understanding is a research area where reverse engineering can contribute a lot. In this PhD dissertation we develop a novel reverse engineering methodology for deep understanding of architectural description of digital hardware systems that appear in technical documents. Initially, we offer a survey on reverse engineering of …

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Augmenting Incident Command System For Improved Emergency Response, Meenakshi Nagarajan Jan 2018

Augmenting Incident Command System For Improved Emergency Response, Meenakshi Nagarajan

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Incident Command System provides a framework for commanders to manage an incident. However, maintaining good situation awareness in an emergency situation is often challenging to the Incident Commander. Stress may result in task fixation which may cause the commander to miss critical information and can eventually lead to poor decisions. The proposed augmented decision support system, with an integrated knowledge base, enhances the commander's decision making and situation awareness by presenting the information that may have been missed. The system has been evaluated to investigate its utility in chemical hazard scenarios. The system was used by experienced Incident Commanders to …

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Building An Abstract-Syntax-Tree-Oriented Symbolic Execution Engine For Php Programs, Jin Huang Jan 2018

Building An Abstract-Syntax-Tree-Oriented Symbolic Execution Engine For Php Programs, Jin Huang

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This thesis presents the design, implementation, and evaluation of an abstract-syntax-tree-oriented symbolic execution engine for the PHP programming language. As a symbolic execution engine, our system emulate the execution of a PHP program by assuming that all inputs are with symbolic rather than concrete values. While our system inherits the basic definition of symbolic execution, it fundamentally differs from existing symbolic execution implementations that mainly leverage intermediate representation (IRs) to operate. Specifically, our system directly takes the abstract syntax tree (AST) of a program as input and subsequently interprets this AST. Performing symbolic execution using AST offers unique advantages. First, …

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Slim Embedding Layers For Recurrent Neural Language Models, Zhongliang Li Jan 2018

Slim Embedding Layers For Recurrent Neural Language Models, Zhongliang Li

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Recurrent neural language (RNN) models are the state-of-the-art method for language modeling. When the vocabulary size is large, the space taken to store the model parameters becomes the bottleneck for the use of these type of models. We introduce a simple space compression method that stochastically shares the structured parameters at both the input and output embedding layers of RNN models to significantly reduce the size of model parameters, but still compactly represents the original input and the output embedding layers. The method is easy to implement and tune. Experiments on several data sets show that the new method achieves …

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Fpga-Based Ir Localization Sensor, Samuel I. Susanto Jan 2018

Fpga-Based Ir Localization Sensor, Samuel I. Susanto

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Pursuit-evasion scenarios are common in both natural and man-made systems. Often times, the pursuer and evader maneuver in response to each others actions using relative information based on the geometry of the agents and potential obstacles within the environment. The pursuer needs the target's bearing angle in order to plan a trajectory or path to capture it. We propose an FPGA-based infrared sensor array to detect up to 6 agents' bearing angles simultaneously. The final output of the sensor is the bearing angle of other agents. The sensor was tested and validated experimentally. Implementing the sensor and transmitter pair on …

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Design Optimization Of A Non-Axisymmetric Endwall Contour For A High-Lift Low Pressure Turbine Blade, Jacob Allen Dickel Jan 2018

Design Optimization Of A Non-Axisymmetric Endwall Contour For A High-Lift Low Pressure Turbine Blade, Jacob Allen Dickel

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Various approaches have been used to shape the geometry at the junction of the endwall and the blade profile in high-lift low-pressure turbine passages in order to reduce the endwall losses. This thesis will detail the workflow to produce an optimized non-axisymmetric endwall contour design for a front-loaded high-lift research turbine profile. Validation of the workflow was performed and included a baseline planar and test contour case for a future optimization study. Endwall contours were defined using a series of Bezier curves across the passage to create a smooth surface. A parametric based approach was used to develop the test …

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3d Visualization And Interactive Image Manipulation For Surgical Planning In Robot-Assisted Surgery, Mohammadreza Maddah Jan 2018

3d Visualization And Interactive Image Manipulation For Surgical Planning In Robot-Assisted Surgery, Mohammadreza Maddah

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Robot-assisted surgery, or "robotic" surgery, has been developed to address the difficulties with the traditional laparoscopic surgery. The da Vinci (Intuitive Surgical, CA and USA) is one of the FDA-approved surgical robotic system which is widely used in the case of abdominal surgeries like hysterectomy and cholecystectomy. The technology includes a system of master and slave tele-manipulators that enhances manipulation precision. However, inadequate guidelines and lack of a human-machine interface system for planning the ports on the abdomen surface are some of the main issues with robotic surgery. Unreachable target and mid-surgery collisions between robotic arms are the major problems …

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Coupling Computational Fluid Dynamics Analysis And Optimization Techniques For Scramjet Engine Design, Nathan T. Mcgillivray Jan 2018

Coupling Computational Fluid Dynamics Analysis And Optimization Techniques For Scramjet Engine Design, Nathan T. Mcgillivray

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Various aspects of hypersonic vehicles are being rapidly explored for improved functionality. One of the main areas of consideration is the fueling of a Supersonic Combusting Ramjet (scramjet) engine. Using Computational Fluid Dynamics (CFD), computer simulations can be performed to analyze the flow physics of a scramjet. In this research, an optimization code, Dakota, is integrated with the CFD to optimize a set of parameters to maximum thrust. In this study, the fuel injection and combustion is replaced with heat sources. This simplification greatly reduces the computational requirements. Additionally, the 3D geometry is reduced to an axisymmetric 2D geometry because …

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Analysis Of Evolutionary Algorithms In The Control Of Path Planning Problems, Pavlos Androulakakis Jan 2018

Analysis Of Evolutionary Algorithms In The Control Of Path Planning Problems, Pavlos Androulakakis

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The purpose of this thesis is to examine the ability of evolutionary algorithms (EAs) to develop near optimal solutions to three different path planning control problems. First, we begin by examining the evolution of an open-loop controller for the turn-circle intercept problem. We then extend the evolutionary methodology to develop a solution to the closedloop Dubins Vehicle problem. Finally, we attempt to evolve a closed-loop solution to the turn constrained pursuit evasion problem. For each of the presented problems, a custom controller representation is used. The goal of using custom controller representations (as opposed to more standard techniques such as …

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Leveraging 3d Models For Sar-Based Navigation In Gps-Denied Environments, Zachary A. Reid Jan 2018

Leveraging 3d Models For Sar-Based Navigation In Gps-Denied Environments, Zachary A. Reid

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This thesis considers the use of synthetic aperture radar (SAR) to provide absolute platform position information in scenarios where GPS signals may be degraded, jammed, or spoofed. Two algorithms are presented, and both leverage known 3D ground structure in an area of interest, e.g. provided by LIDAR data, to provide georeferenced position information to airborne SAR platforms. The first approach is based on the wide-aperture layover properties of elevated reflectors, while the second approach is based on correlating backprojected imagery with digital elevation imagery. Both of these approaches constitute the system we have designated: SARNAV. Building on 3D backprojection, localization …

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