Digital Commons Network^™

Development And Evaluation Of An Interface Aid To Support Web Based Information Seeking For The Blind Research Study, Carissa Ann Brunsman-Johnson

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Information seeking on websites has become more and more challenging for people who are blind. Screen readers attempt to make that task easier by introducing new commands and functionality but there still exists a fundamental gap in the difficulty for people who are blind compared to their sighted counterparts. This research identifies the strategies used by people who are blind and sighted to create an information seeking model, develop the Keywords Expected for Your Search (KEYS) conceptual model for assisting task performance and evaluate a KEYS prototype of this concept for information search and retrieval.

This information seeking model was …

Real-Time Fault Diagnosis Of Automotive Electrical Power Generation And Storage System, Luis Farfan-Ramos

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Automobiles depend more and more on electric power. Analysis of warranty data by automotive OEMs shows that faults in the automotive electrical power generation and storage (EPGS) system are often misdiagnosed. Therefore, monitoring of the state of health (SOH) of the automotive EPGS system is vital for early and correct diagnosis of faults in it, ensuring a reliable supply of electric power to the vehicle and reducing maintenance costs. In this research project, a model-based SOH monitoring method for the EPGS system is developed without the requirement of an alternator current sensor. A model representing the dynamic relationship between the …

Graphene Based Anode Materials For Lithium-Ion Batteries, Sree Lakshmi Cheekati

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Improvements of the anode performances in Li-ions batteries are in demand to satisfy applications in transportation. In comparison with graphitic carbons, transition metal oxides as well as graphene can store over twice amount of lithium per gram. Recently, graphene-based anodes for Li-ion batteries are under extensive development. In this research, lithium storage characteristics in graphene oxide (GO), GO/Manganese acetate (GO/MnAc), GO/manganese oxide (GO/MnOx) composites and Nano Graphene Platelets (NGP) were studied. The prepared GO delivered reversible capacities of 706mAh/g with an average columbic efficiency of 87%. Reversible capacities of 533 mAh/g were observed for GO/MnAc composite. GO/MnOx nanocomposite thermal annealed …

Cognitive Cyber Weapon Selection Tool Empirical Evaluation, Preethi Vinayak Ponangi

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Keeping in pace with the latest technological innovations in the cyber world, the misuse of this powerful infrastructure has also increased proportionally. Although a lot of recent attacks have been documented in the mainstream media, counter measures for cyber defense mechanism have only received some attention in the recent research literature. Most of the global attacks in the cyber space have proved to be carefully planned premeditated attacks. Considering that most of these attacks are co-coordinated by humans, a new area of psychological weaponry is being investigated by the research community. This study aims to empirically evaluate the effectiveness of …

Design Of A Low Power And Area Efficient Digital Down Converter And Sinc Filter In Cmos 90-Nm Technology, Steven John Billman

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A digital down converter (DDC) typically receives a digital input that has been generated by an analog to digital converter (ADC) operating at intermediate frequency (IF) in an RF receiver chain. The function of the DDC is to down convert the IF signal to baseband in phase (I) and quadrature (Q) signals and is a very important component in wireless receivers. A Digital Down Converter (DDC) is developed based on square wave local oscillators facilitating a multiplier-less implementation with no constraints on the sampling frequency. The DDC includes a pseudo multi-rate SINC low pass filter which exhibits better performance compared …

Framework For Cohesive Zone Model Based Multiscale Damage Evolution In A Fatigue Environment, Michael Andrew Thomas

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The focus of this research is to develop a framework to track damage evolution in a structural model subjected to a fatigue environment. This framework incorporates a micromechanical approach of continuous damage modeling, where damage in a homogenized representative microstructure is introduced at the continuum scale through the material constitutive matrix. In this research, damage in the representative microstructure is simulated utilizing cohesive zone models (CZM) whose properties are a function of the magnitude of applied stresses and the resulting separation. In order to minimize the mesh dependence of the cohesive zone model an adaptive meshing technique is employed. A …

Self-Calibrating Cricket Motes For Indoor Navigation, Yogendra Jayant Patil

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Global Positioning System (GPS) plays a vital role for providing localization to the autonomous robots. But the quality of the GPS signal degrades in an indoor location and hence GPS cannot be used for indoor localization. Cricket motes are location-aware system that can provide localization service to its users in an indoor location. Cricket motes apply the acoustic ranging technique to find distance between two points. But before a user can use this localization system, assigning coordinate system to the motes requires manual assistance. This project presents a novel algorithm for self-calibration of the cricket motes to a coordinate system …

Influence Of Design Parameters On Cup-Stem Orientations For Impingement Free Range Of Motion In Hip Implants, Dishita Prakashbhai Patel

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The objective of this investigation is to determine the optimum positions of the prosthesis in total hip arthroplasty that produce least amount of impingement. Theoretical ranges of six basic hip motions were determined under walking, stumbling, internal rotation at 90 flexion and external rotation at 0 extension with 15 abduction, using mathematical models and validated for impingement using finite element analysis. A generalized approach, where impingement does not occur, was developed in this study to understand influence of design parameters such as head-neck ratio, neck-shaft angle, oscillation angle, and stem offset on cup-stem orientations such as cup inclination, cup anteversion, …

Multidisciplinary Optimization Framework For High Speed Train Using Robust Hybrid Ga-Pso Algorithm, Veera Venkata Sunil Kumar Vytla

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High speed trains are the most efficient means of public transportation. However the speed of the train needs to be increased (> 350 km/hr) to cover large distances in a short time to make it accessible to large population. With the increase in speed, number of issues related to efficiency, safety and comfort like the aerodynamic drag, structural strength, as well as the noise levels inside and outside of the train etc. need to be considered in the design of the high speed trains. Hence making it a multi disciplinary design problem. There are a large number of parameters from …

Surface Stress Sensors For Closed Loop Low Reynolds Number Separation Control, Christopher R. Marks

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Low Reynolds number boundary layer separation causes reduced aerodynamic performance in a variety of applications such as MAVs, UAVs, and turbomachinery. The inclusion of a boundary layer separation control system offers a way to improve efficiency in conditions that would otherwise result in poor performance. Many effective passive and active boundary layer control methods exist. Active methods offer the ability to turn on, off, or adjust parameters of the flow control system with either an open loop or closed loop control strategy using sensors. This research investigates the use of a unique sensor called Surface Stress Sensitive Film (S3F) in …

Anthropometric Analysis Of The Cervical Spine, Susan Hueston

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An understanding of the dimensional anatomy of the cervical spine is necessary in order to help diagnose disease, deformity, injury, and device development. Previous investigation has been completed utilizing cadavers, X-rays and other imaging techniques. This research utilized computer tomography images from the trauma registry at Miami Valley Hospital in Dayton, Ohio to complete an anthropometric study of the cervical spine. Linear mathematical models were developed to investigate the relationships present in the dimensional anatomy of the cervical spine. New measurements were completed on subjects of both Caucasian and African American descent and of both genders. An approximation of the …

A Study Of The Aerodynamic Behavior Of A Nrel Phase Vi Wind Turbine Using The Cfd Methodology, Yen-Pin Chen

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Wind energy is an abundant natural resource that people have been trying to tap in recent decades. More and more wind turbines are being built to solve the world's energy shortage problem. For a wind turbine, power extracted from the wind by the rotor and the torque applied to the wind turbine blades are important issues in the design process. Thus there is a need to predict the performance of wind turbine blades using computer modeling. This work shows the results of a computational fluid dynamic simulation developed to predict the air flow field and associated aerodynamic quantities around the …

Investigation Of Variability In Cognitive State Assessment Based On Electroencephalogram-Derived Features, Samantha Lokelani Crossen

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To implement adaptive aiding in modern aviation systems there is a need for accurate and reliable classification of cognitive workload. Using electroencephalogram (EEG)-derived features, it has been reported that an Artificial Neural Network (ANN) can achieve 95% or higher classification accuracy on the same day for an individual operator, but only 70% or less on a different day. To gain a further insight into this discrepancy, data from a previous study was utilized to study the classification variability. The EEG-derived features were first calculated by spectral power estimation. The variability was then analyzed by performing cognitive workload classification in which …

Large Scale Distributed Semantic N-Gram Language Model, Yuandong Jiang

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Language model is a crucial component in statistical machine translation system. The basic language model is N-gram which predicts the next word based on previous N-1 words. It has been used in the state-of-the-art commercial machine translation systems over years. However, the N-gram model ignores the rich syntactic and semantic structure in natural languages. We propose a composite semantic N-gram language model which combines probabilistic latent semantic analysis model with N-gram as a generative model. We have implemented the proposed composite language model in a super-computer with thousand processors that is trained by 1.3 billion tokens corpus. Comparing with simple …

Process Sequencing For Fatigue Life Extension Of Large Scale Laser Peened Components, Thomas Joshua Spradlin

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Mechanical surface enhancement techniques have been used to successfully increase the fatigue life of metallic components. These techniques impart compressive surface residual stresses that reduce the tensile stresses experienced during service loading. Laser Peening (LP) is a surface enhancement technique that uses high intensity, short duration laser pulses to create plastic shockwaves in metallic components. Experimental investigations and limited simulation studies have been conducted to determine the effects on the fatigue life of simple coupons when key LP parameters are varied. Used primarily in the aerospace and biomedical engineering fields, LP has been limited to industries that can afford its …

An Exploratory Study Of Mixed-Width Aisle Layouts For Order Picking In Distribution Centers, Corinne H. Mowrey

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Order picking is arguably the most expensive operational activity for a distribution center (DC), constituting upwards of 50% of total operating costs. Designing an optimum order picking system (OPS) for a DC depends on several system parameters, such as aisle layout, storage system configuration, storage policy, picking method, and picking strategy. From an aisle layout standpoint, traditional DCs utilize either entirely wide or entirely narrow aisles in their picking systems. Wide aisles allow pickers to pass each other, reducing blocking and requiring fewer pickers. However, the space required for wide-aisle systems is high. Narrow aisles utilize less space than wide …

Lithium-Ion Battery Anodes Of Randomly Dispersed Carbon Nanotubes, Nanofibers, And Tin-Oxide Nanoparticles, Gerard Klint Simon

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Lithium-ion battery anodes with a nanostructure of randomly dispersed carbon nanofibers (CNFs), carbon nanotubes (CNTs), and nanoparticles of tin-oxide or silicon were fabricated and tested in order to develop high capacity, easily manufactured anodes. In these anodes, a mesh of CNTs and CNFs form a conductive network within which the nanoparticles of tin-oxide are suspended. The CNT network directs electron flow to and from the nanoparticles while accommodating their volume changes. The CNFs were intended to aid electron transport by serving as conduction channels between the CNTs and the current collector. Secondarily, the CNFs reinforce the physical structure of the …

Performance Analysis Of Radar Waveforms For Congested Spectrums, Shaun W. Frost

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With more users populating the RF spectrum and hence less available contiguous bandwidth, radar and communication waveforms are slowly forced to become more efficient at using their available frequencies. Two scenarios are considered: operation in a colored interference environment and operation in discontiguous spectral bands. Unconstrained algorithms for designing transmit waveforms and receive filters are evaluated, wherein varying a convex weight trades performance between spectral flatness and side lobe levels. An empirical study provides performance bounds for constrained radar waveform designs for an instantiation of the interference spectrum.

Closed-form predictions for integrated sidelobe ratio (ISLR) and peak-to-sidelobe ratio (PSLR) for …

Analytical And Experimental Vibration Analysis Of Variable Update Rate Waveform Generation, Joshua F. Mark

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Typical vibration analysis of turbine engine components incorporates the use of a function generator to produce a signal that is routed to an excitation source as the forcing function of the test specimen. These waveforms are constructed by varying the amplitude of the signal over time with a fixed update rate (time increment between samples). This research investigates generating chirp waveforms by storing only one sinusoid of points and using an external timing signal to repetitively send out these stored data points. This results in varying the amplitude of the signal over time as well as the update rate. The …

Dynamic Footed With Clock Overlapping And Load Balancing In Multiple Paths For Noise Tolerance In Dynamic Cmos Circuits, Ramadan U. Buzakuk

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Dynamic CMOS circuits are used in microprocessors as well as in circuits that require high speed and small areas. Dynamic CMOS circuits have many advantages but are not robust in noise tolerance in comparison with the legacy static CMOS circuits. In this thesis several noise tolerance techniques that can be implemented with Dynamic CMOS circuits for robust noise tolerance are studied. A dynamic footed with clock overlapping technique integrated with a load balancing multiple-path transistor sizing algorithm for optimizing performance of noise tolerance and speed while in consideration of process variations is presented. Using the 2-bit weighted binary-to-thermometric converter implemented …

Commercial Program Development For A Ground Loop Geothermal System: Energy Loads, Gui, Turbulent Flow, Heat Pump Model And Grid Study, Paul A. Gross Ii

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The use of the earth's thermal energy to heat and cool building space is nothing new; however, the heat transfer approximations used in modeling geothermal systems, leave uncertainty and lead to over sizing. The present work is part of a Wright State effort to improve the computer modeling tools used to simulate ground loop geothermal heating and cooling systems. The modern computer processor has equipped us with the computation speed to use a finite volume technique to solve the unsteady heat equation with hourly time steps for multi-year analyses in multiple spatial dimensions. Thus we feel there is more need …

Commercial Program Development For A Ground Loop Geothermal System: G-Functions, Commercial Codes And 3d Grid, Boundary And Property Extension, Kyle L. Hughes

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The rise in fossil fuel consumption and green house gas emissions has driven the need for alternative energy and energy efficiency. At the same time, ground loop heat exchangers (GLHE) have proven capable of producing large reductions in energy use while meeting peak demands. However, the initial cost of GLHEs sometimes makes this alternative energy source unattractive to the costumer. GLHE installers use commercial programs to determine the length of pipe needed for the system, which is a large fraction of the initial cost. These commercial programs use approximate methods to determine the length of pipe mainly due to their …

Direct Digital Frequency Synthesizer Architecture For Wireless Communication In 90 Nm Cmos Technology, Tri Trong Nguyen

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Software radio is one promising field that can meet the demands for low cost, low power, and high speed electronic devices for wireless communication. At the heart of software radio is a programmable oscillator called a Direct Digital Synthesizer (DDS). DDS has the capabilities of rapid frequency hopping by digital software control while operating at very high frequencies and having sub-hertz resolution. Nevertheless, the digital-to-analog converter (DAC) and the read-only-memory (ROM) look-up table, building blocks of the DDS, prevent the DDS to be used in wireless communication because they introduce errors and noises to the DDS and their performances deteriorate …

Analysis And Comparison Of Popular Models For Current-Mode Control Of Switch Mode Power Supplies, Ramchandra M. Kotecha

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Current-mode control is the most popular scheme used for the operation of SMPS (Switch Mode Power Supplies). Current-mode control, also known as current-programmed mode or current-injected control is a multi-loop control scheme that has an inner loop and an outer voltage loop. The current loop controls the inductor peak current while the voltage loop controls the output voltage. The inner loop follows a set program by the outer loop. Some of the most popular small-signal models that predict the small-signal characteristics of current-mode control scheme have been analyzed and compared in this thesis. A PWM dc-dc buck converter in CCM(Continuous …

Analysis And Design Of Pulse-Width Modulated Two-Switch Forward Dc-Dc Converter For Universal Laptop Adapter, Venkata Sai Aditya Kumar Choragudi

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The objective of this research is to analyze, design and simulate a two-switch forward pulse-width modulated (PWM) DC-DC converter. The Forward PWM DC-DC converter is originally derived from the buck converter by the addition of a transformer. The transformer is mainly used as a safety feature to electrically isolate input and output stages of the power converter and also to scale the voltage or current. The steady-state analysis is presented for the two-switch PWM DC-DC forward converter in continuous conduction mode (CCM). Based on the analysis, the design equations for two-switch PWM forward DC-DC converter are derived. A design example …

Dc-Dc Power Converter Design For A Portable Affordable Welder System (Paws), Curt Stephen Zackiewicz

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Arc welding machines are typically large, heavy devices that transform an alternating current (AC) input into a low-voltage, direct current (DC) output. Traditionally these high power devices have required steel and copper transformers that account for their bulky size and weight. While the cost of raw materials in electromagnetic components has been increasing the cost of high-power silicon devices has been decreasing. This disparity creates an opportunity for a cost-effective DC-DC switching welder in the consumer market. While DC-DC power electronics are not new to the welding industry, this study, under the commission of a welding equipment manufacturer, aims to …

Observer-Based Fault Diagnosis Of Wind Turbines, Songling Zhao

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Because wind is a clean and renewable energy, it is in high demand as an alternative resource of fossil fuels for our daily power supply. Thus, wind turbine technology is wildly applied to convert the wind energy to electrical power. With the size of the wind turbines increased, the maintenance cost of the wind turbines also goes up. Fault diagnosis can significantly help wind turbines to: reduce the maintenance cost, the machinery breakdown, spare parts inventories, total machine downtime, and overtime expenses, and increase machine life, overall productivity, and profit. The technical challenges for fault diagnosis of the wind turbine …

Predicting Vigilance Performance Under Transcranial Direct Current Stimulation, Nathaniel Reese Bridges

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A brain stimulation technology called transcranial direct current stimulation (tDCS) may potentially mitigate the vigilance decrement. To practically use such technology, however, a model is necessary that indicates vigilance performance, both when stimulation is being applied and not applied. To address this issue, the author developed models capable of predicting vigilance performance in real and control stimulation conditions using previous tDCS-study data. The "all possible combinations" regression method produced over 200 models, later screened to 10. The model with the best average %error (11.49 ± 0.10) used left hemispheric cerebral blood flow velocity (CBFVL) as its sole input term-accounting for …

The Functionalization And Characterization Of Adherent Carbon Nanotubes With Silver Nanoparticles For Biological Applications, Adam A. Maleszewski

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The purpose of this project is to form silver nanoparticles (Ag-NP) attached to a hierarchical substrate for possible use in biological applications. The effectiveness of these Ag-NP-containing devices, including biofilters and biosensors, may be dramatically enhanced by the use of hierarchical structures such as carbon nanotubes (CNT), as they offer a high surface area surface suitable for cell-device interactions, while Ag-NP would be a suitable component in many such devices due to its plasmonic surface properties (e.g. in sensor and directed energy applications) and its anti-microbial properties (desirable for fluid filtration due to its low weight. Meaningful control over the …

Semi-Automated Dental Cast Analysis Software, Mathew Thomas

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Dental casts have been used extensively to study almost all aspects of the human dentition. These aspects varied from the study of tooth form and morphology, inheritance and genetics, growth and development, occlusion, arch alignment and crowding to mathematical determination of dental arch form.

The aim of this project was to develop a tool to semi-automate the measurement of dental casts that would be precise, accurate and efficient. Measurements include tooth widths, arch lengths and widths, angle of rotation and crown area for each tooth.

The task was divided into two different parts: first, the development of semi-automatic software to …