Engineering Commons^™

Modeling And Minimization Of Integrated Circuit Packaging Parasitics At Radio Frequencies, Christopher Benedik

Browse all Theses and Dissertations

Many integrated circuits are connected to their packaging pins through bondwires. Due to the low cost of bondwires, there is interest in extending operating frequencies or negating their effects in order to keep the price of packaged integrated circuits as low as possible. Bondwires function as lumped circuits consisting of inductors, capacitors, and resistors which can be modeled based on wire geometry. Knowing this, models can be created which approximate the effects of bondwires. With the knowledge of these models, compensation techniques can be implemented which will match the bondwire impedance to the signal line impedance. The effects of these …

Visualizing Confusion Matrices For Multidimensional Signal Detection Correlational Methods And Semantic Cluster Based Visualization In Virtual Environments, Yue Zhou

Browse all Theses and Dissertations

General Recognition Theory (GRT) is a multidimensional signal detection theory framework for capturing sources of perceptual and decisional dependence. The primary type of data for GRT models is an identification-confusion matrix derived in a complete factorial identification task. This confusion matrix plots the responses of study participant for a given signal. The responses may reveal that participants were unable to recognize the signal properly. Such violations of any type of independence in the GRT framework result in response patterns that reflect some form of correlation in the GRT space. While an individual confusion matrix is rather small and relatively easy …

Distributed Fault Diagnosis Of Interconnected Nonlinear Uncertain Systems, Qi Zhang

Browse all Theses and Dissertations

Fault diagnosis is crucial in achieving safe and reliable operations of interconnected control systems. This dissertation presents a distributed fault detection and isolation (FDI) method for interconnected nonlinear uncertain systems. The contributions of this dissertation include the following: First, the detection and isolation problem of process faults in a class of interconnected input-output nonlinear uncertain systems is investigated. A novel fault detection and isolation scheme is devised, and the fault detectability and isolability conditions are rigorously investigated, characterizing the class of faults in each subsystem that are detectable and isolable by the proposed distributed FDI method. Second, a distributed sensor …

Cooperative Interactive Distributed Guidance On Mobile Devices, Gregory Burnett

Browse all Theses and Dissertations

Mobiles device are quickly becoming an indispensable part of our society. Equipped with numerous communication capabilities, they are increasingly being examined as potential tools for civilian and military usage to aide in distributed remote collaboration for dynamic decision making and physical task completion. With an ever growing mobile workforce, the need for remote assistance in aiding field workers who are confronted with situations outside their expertise certainly increases. Enhanced capabilities in using mobile devices could significantly improve numerous components of a task's completion (i.e. accuracy, timing, etc.). This dissertation considers the design of mobile implementation of technology and communication capabilities …

Streamsurface Smoke Effect For Visualizing Dragon Fly Cfd Data In Modern Opengl With An Emphasis On High Performance, Jordan Sipes

Browse all Theses and Dissertations

Visualizing 3D, time dependent velocity vector fields is a difficult topic. Streamlines can be used to visualize 3D vector fields. A smoke effect where the streamline is faded out as time progresses can provide a better visualization of a time dependent flow. This work uses modern OpenGL to create a smoke trail effect with streamsurfaces in the dragon fly data set. Many aspects affecting performance are tested to determine the best options or approach.

Natural Language Document And Event Association Using Stochastic Petri Net Modeling, Michael Thomas Mills

Browse all Theses and Dissertations

The purpose of this research is to design and implement a new methodology that captures the natural language understanding of events from English natural language text and model it using Stochastic Petri Nets. To establish a baseline of recent natural language processing (NLP) and understanding (NLU) research, two surveys are presented. One is a general survey in NLP and NLU methodologies for processing multi-documents. It summarizes and presents methodologies in terms of their features, capabilities, and maturity. The second survey focuses on graph-based methods for NL text processing and understanding and analyzes them in terms of their functional descriptions, capabilities …

Shock Correlation Investigation In A Gaseous Fueled Axisymmetric Scramjet Flowpath, Jaime Omar Larios-Barbosa

Browse all Theses and Dissertations

A pressure-based investigation was conducted on a gaseous fueled axisymmetric scramjet flowpath in Research Cell 22 located at Wright Patterson AFB. The investigation followed the work performed by Waltrup and Billig using combustion data to validate the form of the correlation in an attempt to achieve a good predictive tool for isolator length. Two years of axial wall pressure data using Mach values of 1.8 and 2.2 were analyzed in this investigation. The combustion data was shown to follow the same quadratic distribution show in Waltrup and Billig's work with the data being shifted to the right relative to the …

Timing And Power Optimization Using Mixed-Dynamic-Static Cmos, Hao Xue

Browse all Theses and Dissertations

An effective approach to timing and power optimization for single clocking and multiple clocking dynamic CMOS designs is presented in this thesis. For the single-clocking scheme dynamic CMOS sub-blocks can be replaced by static CMOS and mixed-dynamic-static CMOS for power minimization. For the multiple-clocking scheme the delay of data ready for use plays more important role than its clock pulse in timing optimization. Power minimization can be achieved by implementing dynamic CMOS sub-blocks with static or mixed-dynamic-static CMOS. In comparison with the benchmark 16-bit carry select adder in dynamic CMOS, the critical path delay is reduced by 41.1% using the …

Computational Modeling Of Nanosensors Based On Graphene Nanoribbons Including Electron-Phonon Effects, Kirti Kant K. Paulla

Browse all Theses and Dissertations

We investigate detection mechanisms of real time sensors, based on ultra-thin (single and bi-atomic layer thick) and ultra-narrow (~1nm) graphene nanoribbons (GNRs), using first principle based theoretical methods. In the first part of this study we study the electronic and magnetic structures of bilayer graphene nanoribbons (BGNRs) beyond the conventional AA and AB stackings, by using density functional theory within both local density and generalized gradient approximations (LDA and GGA). Our results show that, irrespective of the method chosen, stacking arrangements other than the conventional ones are most stable, and result in significant modification of BGNRs characeristics. The most stable …

Carbon-Based Nanostructured Materials As Electrode In Lithium-Ion Batteries And Supercapacitors, Zhuo Yao

Browse all Theses and Dissertations

Carbon-based nancomposites attract much attention as electrode materials in electrochemical energy storage systems due to their low-cost, extraordinary high electrical and thermal conductivity, super high surface area etc. In this research, graphene nanosheets (GNS) and their nanocomposites with manganese oxides (GNS/MnOx) or silicon nanowires (GNS/SiNWs/CF) are studied for their applications in Li-ion batteries and supercapacitors. GNS powders are synthesized via a chemical oxidation of nature graphite followed by appropriate reduction process. GNS/MnOx composites are synthesized rendering MnOx nanoparticles embedded on the surfaces of GNS. SiNWs grown in carbon fibers are mechanically mixed with GNS powders. The impacts of the manganese …

Wing Damage Effect On Dragonfly's Aerodynamic Performance During Takeoff, Kuo Gai

Browse all Theses and Dissertations

Insect wing damage resulted from living environment or predation commonly happens in nature. This usually results in deterioration of insect's flight performance and as a consequence, the insect needs adjustment of flapping wings to compensate the effect from the wing loss. In this study, a dragonfly (Erythemis simpliciolis) with and without wing loss is chosen to study the change of aerodynamic performance of flapping wings. Three cases including flight with intact wings (IW), flight with one-sided forewing damage (OFD), and flight with double-side forewing damage (DFD) are determined. An integrated study using high-speed photogrammetry, three-dimensional surface reconstruction, and direct numerical …

Effect Of Process Variables On Sub-Melt Thermal Behavior And Solid-State Phase Transformations In Beam-Based Additive Manufacturing Of Ti-6al-4v, Heather N. Doak

Browse all Theses and Dissertations

The success of laser and electron beam-based fabrication processes for additive manufacture and repair applications requires the ability to control melt pool geometry while maintaining a consistent and desirable microstructure. Previous work has employed a process map approach to link melt pool geometry to solidification microstructure (grain-size and morphology) in beam-based fabrication of Ti-6Al-4V. The current work extends the approach to investigate the effects of process variables on solid-state phase transformations below the solidification temperature through Finite Element Modeling, the 3-D Rosenthal Solution, and experimentation. Process maps for solid-state microstructure could be used to help maintain consistent and reliable mechanical …

An Accuracy Improvement Method For Cricket Indoor Location System, Anall Vijaykumar Gandhi

Browse all Theses and Dissertations

The effective deployment of Automated Guided Vehicles (AGV) in indoor hostile environment demands high precision localization for navigation purposes. The cricket system, based on Time Difference of Arrival (TDoA) approach, provides precise localization. It calculates TDoA between radio and ultrasonic signal to estimate distance between two cricket motes. The position, in the referenced coordinate system, is estimated by multilateration using estimated distances from multiple motes. Therefore, the position accuracy depends on the distance estimation which in turn depends on the TDoA calculation. Ultrasonic transducer, a component of cricket mote hardware, has highly directive radiation pattern which affects ultrasonic signal detection. …

Design And Improve Energy Efficiency And Functionalities Of Electrical Wheelchairs, Dewei Guan

Browse all Theses and Dissertations

There are millions of people who have lost their abilities to walk and wheelchairs offer the ONLY opportunities for their interactions with people and environments outside their houses. These individuals are becoming more and more eager to adapt modern technologies on their wheelchairs to improve quality of social life and the life of freedom. However, most available electric wheelchairs, driven by traditional lead-acid batteries and gear motors, are heavy and bulky in design with low energy efficiency, limited travel radius, and scarce communication/navigation functionalities. This project is to design and prototype an electric wheelchair that is lighter, more flexible in …

An Experimental Investigation On The Control Of Tip Vortices From Wind Turbine Blade, Zhe Ning

Browse all Theses and Dissertations

Wind turbine dynamics, wake effects and environmental impacts have been identified the most significant research topics needed for wind resource characterization and wind power generation. Among these issues, tip vortices generated from the blade tip have been recognized as a substantial resource for the turbulent wake flow as well as the aerodynamic noise emission from a wind turbine. An experimental study is conducted to characterize the evolution of the tip vortices downstream of a well-designed horizontal axis wind turbine (HAWT) model. In addition to measuring dynamic wind loads (both aerodynamic forces and moments) and power output from the wind turbine …

Adaptive Semantic Annotation Of Entity And Concept Mentions In Text, Pablo N. Mendes

Browse all Theses and Dissertations

The recent years have seen an increase in interest for knowledge repositories that are useful across applications, in contrast to the creation of ad hoc or application-specific databases.

These knowledge repositories figure as a central provider of unambiguous identifiers and semantic relationships between entities. As such, these shared entity descriptions serve as a common vocabulary to exchange and organize information in different formats and for different purposes. Therefore, there has been remarkable interest in systems that are able to automatically tag textual documents with identifiers from shared knowledge repositories so that the content in those documents is described in a …

Spectrally Modulated Spectrally Encoded Framework Based Cognitive Radio In Mobile Environment, Xue Li

Browse all Theses and Dissertations

Radio spectrum has become a precious resource, and it has long been the dream of wireless communication engineers to maximize the utilization of the radio spectrum. Dynamic Spectrum Access (DSA) and Cognitive Radio (CR) have been considered promising to enhance the efficiency and utilization of the spectrum. Since some of the spectrum bands are occupied by primary users (PUs), the available spectrum for secondary users (SUs) are non-contiguous, and multi-carrier transmission technologies become the natural solution to occupy those non-contiguous bands. Non-contiguous multi-carrier based modulations, such as NC-OFDM (non-contiguous Orthogonal Frequency Division Multiplexing), NC-MC-CDMA (non-contiguous multi-carrier code division multiple access) …

Fundamental Understanding Of Blisk Analytical Response, Joseph A. Beck

Browse all Theses and Dissertations

This effort seeks to increase the reduced-order model fidelity for mistuned Integrally Bladed Rotor (IBR) and Dual Flow-path Integrally Bladed Rotor (DFIBR) response prediction by explicitly accounting for blade geometric and material property deviations. These methods are formulated in a component mode synthesis (CMS) framework utilizing secondary modal reductions in a cyclic symmetry format. The resulting reduced-order models (ROMs) capture perturbations to both blade natural frequencies and mode shapes resulting from geometric deviations. Furthermore, the secondary modal reductions and cyclic symmetry format offer significant computational savings over traditional component mode synthesis methods that give a further reduction in model size. …

Steps In The Development Of A Full Particle-In-Cell, Monte Carlo Simulation Of The Plasma In The Discharge Chamber Of An Ion Engine, Bryan James Penkal

Browse all Theses and Dissertations

The design and development of ion engines is a difficult and expensive process. In order to alleviate these costs and speed ion engine development, it is proposed to further develop a particle-in-cell (PIC), Monte-Carlo collision (MCC) model of an ion engine discharge chamber, which has previously been worked on by the Wright State Ion Engine Modeling Group. Performing detailed and accurate simulations of ion engines can lead to millions of dollars in savings in development costs.

In order to recognize these savings more work must be done on the present day models used to simulate ion engine performance. The work …

Selective Free-Standing Through-Wafer Porous Silicon Membrane (Sftpsm) For Integrated Meta-Material Devices, Bella Liu Yao

Browse all Theses and Dissertations

Meta-materials have attracted considerable attention due to their unique electromagnetic properties, such as negative permittivity (ε), negative magnetic permeability (μ), and negative index of refraction. These devices have shown broad flexibility in compact phase shifter, backward leaky-wave antenna, and high-directivity coupled-line coupler applications; however, integrated devices utilizing meta-material structures have not yet surfaced due to a lack of integration technology.

In this work, a novel concept of integrated meta-materials is presented, using free-standing porous silicon (PS) membranes of periodic magnetic wire arrays (PMWA). The free-standing PS membranes were fabricated on p-type silicon substrates through electrochemical anodization. Systematic investigations have been …

Solar-Powered Wireless Sensor Nodes With Dynamic Power Management For Indoor Use, Ethan Charles Humphrey

Browse all Theses and Dissertations

Indoor environment monitoring, such as medical monitoring and home automation, is achieved through wireless sensor networks that collect data through wireless sensor nodes. These nodes are typically powered by exhaustible power sources that could be difficult or impossible to maintain regularly. A solution to the need for frequent maintenance is to collect the solar power in the environment. This project shows how collecting the solar energy in the environment can extend the lifetime of a sensor node and limit the maintenance required. Along with charging the battery with a solar panel, a dynamic power management scheme can also be implemented. …

Evaluating The E-Consult Process For Diabetes Care Delivery At An Outpatient Care Clinic, Brian M. Zoll

Browse all Theses and Dissertations

The occurrence of one of the most common chronic conditions in the U.S., diabetes, is expected to rise 53% from 24 million cases in 2003 to 37 million cases in 2023. The U.S. Veterans Health Administration (VHA) is not immune to this. The VHA has experienced an $820 million increase spending on diabetes patients between 2000 and 2008. The VHA has tried to keep the growth of chronic care costs in check through improvements in patient access to care by expanding its network of community-based outpatient clinics. Other methods the VHA has used to curb chronic care spending costs are …

Effect Of A Graded Layer On The Plastic Dissipation During Mixed-Mode Fatigue Crack Growth On Ductile Bimaterial Interfaces, Craig M. Baudendistel

Browse all Theses and Dissertations

An energy-based theory for predicting mode I fatigue crack growth rates in ductile metals based on the total plastic dissipation ahead of a crack tip was proposed in 2003. Since then, this theory has been extended to layered material systems that typically include mixed-mode loading and elastic/plastic mismatch. Previous research by the author first extended this theory to include a graded layer (i.e., no step change in material properties across the crack plane) with which to more accurately model a crack interface between two materials with a mismatch in plastic properties only. In the current research, the graded layer model …

Analysis Of Human Echolocation Waveform For Radar Target Recognition, Kandarp Patel

Browse all Theses and Dissertations

Some blind humans have developed the remarkable capability of echolocation, similar to the type used by mammals such as the bat, dolphin and whale. This population of human has shown the ability to classify targets based on their location, size, shape and material in diverse environmental conditions simply by listening to the reflected echoes of tongue clicks generated by their mouth. To date, much of the research into human echolocation has been confined exclusively to behavioral science and the analysis is inconsistent with the approaches used in engineering. The waveforms used in current radar systems appear different to those typical …

Low Cost Open Source Modal Virtual Environment Interfaces Using Full Body Motion Tracking And Hand Gesture Recognition, Matthew J. Marangoni

Browse all Theses and Dissertations

Virtual environments provide insightful and meaningful ways to explore data sets through immersive experiences. One of the ways immersion is achieved is through natural interaction methods instead of only a keyboard and mouse. Intuitive tracking systems for natural interfaces suitable for such environments are often expensive. Recently however, devices such as gesture tracking gloves and skeletal tracking systems have emerged in the consumer market. This project integrates gestural interfaces into an open source virtual reality toolkit using consumer grade input devices and generates a set of tools to enable multimodal gestural interface creation. The AnthroTronix AcceleGlove is used to augment …

Investigation Of The Utility Of Center Frequency In Electroencephalographic Classification Of Cognitive Workload Transitions, Jones Melissa

Browse all Theses and Dissertations

Successful classification of human cognitive workload is a vital component in identifying and avoiding potential performance deficits resulting from operator work overload. Previous research suggests that electroencephalogram (EEG) derived features, including center frequency, provide a robust signal which may be used to obtain highly accurate workload classification. The purpose of this work is to investigate evidence of physiological hysteresis and determine if center frequency improves a classifier's ability to correctly identify workload level. Results confirmed that including spectral data creates the most robust feature sets, while center frequency across all bands is equally reliable for classifying workload in the case …

The Effects Of Text And Hybrid Graphic-Text Formats On Pilot Performance Using Flight Deck Data Communication Displays, Ricardo Daniel Muñoz Da Costa

Browse all Theses and Dissertations

Air Traffic has shown a steady increase since the institution of commercial aviation in the first quarter of the last century, and the use of the United States National Airspace System (NAS) is expected to increase by 45 percent more passengers by the year 2015 (Smith, 2004). The increasing demands of the NAS require preventive measures in order to preserve the safety of operations. NextGen is a transformative program expected to enhance the safety and effectiveness of NAS operations. One of the ways that it will achieve these goals is by improving air-ground communications.

In the current system, communications between …

Software-Defined Radio Based Blind Hierarchical Modulation Detector Via Second-Order Cyclostationary And Fourth-Order Cumulant, Yang Qu

Browse all Theses and Dissertations

Modulation detection is very important to many communication and electronic warfare applications. Recent developments in cognitive radio (CR) and dynamic spectrum access (DSA) network have also brought much attention to modulation detection of unknown radio frequency (RF) signals. It is well known that using second-order cyclostationary features, e.g., spectral correlation function (SCF) and spectral coherent function (SOF), BPSK modulation can be easily distinguished from higher order modulations such as QPSK and QAM modulations. However, QPSK and higher order modulations exhibit similar second-order cyclostationary features, thus these features cannot be employed to distinguish among higher order modulations. To classify higher order …

Non-Contact Probes For Characterization Of Thz Devices And Components, Mads Jacob Hedegaard Larsen

Browse all Theses and Dissertations

One of the challenges in developing semiconductor devices and integrated circuits for the terahertz (THz) region is their electrical characterization. The most common technology for their characterization is presently metal-to-metal, DC-coupled contact probes, which operate up to 750 GHz but are expensive and fragile.

/

In this Master's Thesis, we investigate through numerical simulation and analysis the electromagnetic properties of a novel, AC-coupled probe. The new probe couples radiation from the device or circuit-under-test (DUT) via polarization current, which is then transformed to conduction current in the probe and down-converted in frequency to baseband by an optically-pumped photomixer. Finite-element simulations …

The Effectiveness Of Pilot Response To Generate Concatenated Downlink Messages After Evaluation Of Hybrid Graphic-Text Clearances, Steven Brent Kiss

Browse all Theses and Dissertations

Data-Link Communication, or DataComm, is a digital text messaging system providing a means of communication between Air Traffic Control (ATC) and pilots. Current Pilot/ATC communication is via voice radio, but the number of ATC operators and voice channels are finite, which limits the number of aircraft voice transmission can accommodate. The number of aircraft within the National Airspace System (NAS) is expected to double between 2004 and 2025, and a transition from voice to DataComm is a necessity. DataComm is an integral part of the NAS and is implemented in incremental phases increasing its functions and capability. There are many …