Digital Commons Network^™

Determination Of Structure From Motion Using Aerial Imagery, Paul R. Graham

Theses and Dissertations

The structure from motion process creates three-dimensional models from a sequence of images. Until recently, most research in this field has been restricted to land-based imagery. This research examines the current methods of land-based structure from motion and evaluates their performance for aerial imagery. Current structure from motion algorithms search the initial image for features to track though the subsequent images. These features are used to create point correspondences between the two images. The correspondences are used to estimate the motion of the camera and then the three-dimensional structure of the scene. This research tests current algorithms using synthetic data …

Design And Simulation Of A Permanent-Magnet Electromagnetic Aircraft Launcher, Dean Patterson, Antonello Monti, Charles W. Brice, Roger A. Dougal, Robert O. Pettus, Srinivas Dhulipala, Dilip Chandra Kovuri, Tiziana Bertoncelli

Faculty Publications

This paper describes the basic design, refinement, and verification using finite-element analysis, and operational simulation using the Virtual Test Bed, of a linear machine for an electromagnetic aircraft launcher, for the aircraft carrier of the future. Choices of basic machine format and procedures for determining basic dimensions are presented. A detailed design for a permanent-magnet version is presented, and wound-field coil and induction machine versions are briefly discussed. The long armature-short field geometry is justified, and in particular the impact of this geometry on the scale of the power electronic drive system is examined.

Study Of Behavior Of Digital Modulations For Beam Steerable Reflectarray Antennas, Fuqin Xiong, Robert R. Romanofsky

Electrical and Computer Engineering Faculty Publications

This paper investigates the bit error rate (BER) performance of digital modulations in a system with a scanning reflectarray antenna. A reflectarray causes intersymbol interference (ISI) in a digitally modulated signal, its phase shifters' phase errors cause signal distortion, and its phase shifters' phase transient causes beam pattern degradation during direction switching. In this paper, composite signal models of the reflectarray are established for both static and transient states. Due to different feed-to-element distances and the element-to-observation distances, different delays exist in signal components. These delays cause ISI whose effect is analyzed and evaluated. Effects of phase shifters' phase errors …

The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii

Theses and Dissertations

This research proposes the use of an existing "signal of opportunity" - namely x-ray pulsars - to improve the accuracy and robustness of the GPS satellite and clock estimation algorithm. Improvement in satellite and clock accuracy results in a direct benefit to the user. A simulation has been developed to determine the effects of using x-ray pulsar measurements on the GPS Operational Control Segment. The epoch-specific position, velocity, and clock errors of all GPS satellites in the constellation were estimated using both pseudoranges and time-difference-of-arrival (TDOA) measurements from pulsars. The primary measure of accuracy is a constellation Signal-In-Space Range Error …

An Examination Of Range And Doppler Mismatch And Their Effects On Radar Modeling, Gregory L. Izdepski

Theses and Dissertations

A commonly accepted airborne phased array radar model simplifies the analytical derivation by assuming a waveform is perfectly matched in range and Doppler shift. This assumption means the matched filter output is effectively constant for all possible received scatterer Doppler and range mismatches, greatly simplifying the analytical development from that point forward. This research removes the matched Doppler and range assumption and examines the effects of several common waveforms on the model's fidelity along with the associated impact on radar performance, both non-adaptive and adaptive. Analysis is completed using power spectral density comparisons and the fully adaptive output signal to …

Using Multiple Mems Imus To Form A Distributed Inertial Measurement Unit, Ryan D. Hanson

Theses and Dissertations

MEMS IMUs are readily available in quantity and have extraordinary advantages over conventional IMUs in size, weight, cost, and power consumption. However, the poor performance of MEMS IMUs limits their use in more demanding military applications. It is desired to use multiple distributed MEMS IMUs to simulate the performance of a single, more costly IMU, using the theory behind Gyro-Free IMUs. A Gyro-Free IMU (GF-IMU) uses a configuration of accelerometers only to measure the three accelerations and three angular rotations of a rigid body in 3-D space. Theoretically, almost any configuration of six distributed accelerometers yields sufficient measurements to solve …

Efficient Electromagnetic Material Characterization Via 2-D Rectangular Waveguide Reduction, Derek R. Dwyer

Theses and Dissertations

A new, low-frequency, rectangular waveguide-based electromagnetic material characterization technique is developed that will reduce the test sample size in two dimensions realizing up to 75 percent reduction in sample cross-sectional area. To achieve this, custom made, reduced aperture, sample holder flanges were used that reduce the waveguide’s excessive cross-sectional dimensions, resulting in reduced sample fabrication costs. Additionally, MatLab® code was developed to implement the rigorously derived modal-analysis solution that accommodates induced, higher-order transverse electric and transverse magnetic modes and accurately extract the reduced test sample’s constitutive parameters. Experimental results using various test samples are compared to known, full-aperture measurements for …

Modification Of A Modulation Recognition Algorithm To Enable Multi-Carrier Recognition, Angela M. Waters

Theses and Dissertations

Modulation recognition is important for both military and commercial communication applications, particularly in cases where enhanced situation awareness and/or channel assessment is required to mitigate intentional or collateral interference. Modulation recognition via template matching or statistical analysis is a key aspect of non-cooperative (nonmatched filtering) signal interception, classification, and exploitation. This research concerns the evaluation and modification of a conventional Digitally Modulated Signal Recognition Algorithm (DMRA) to enable multi-carrier, Orthogonal Frequency Division Multiplexing (OFDM), waveform recognition. The original DMRA architecture was developed to classify communication signals for three fundamental data modulations, i.e., Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), …

Finite Difference Time Domain (Fdtd) Analysis Of A Leaky Traveling Wave Microstrip Antenna, Gregory M. Zelinski

Theses and Dissertations

This thesis provides the groundwork that will enable the development of a lightweight, inexpensive, aerodynamic, and broadband antenna. Whether for radar or communication, an antenna with these properties would be a force multiplier for the smaller, limited payload air vehicles the United States Air Force will pursue in the coming years. Several microstrip antennas using the first higher order mode were simulated with the Finite-Difference Time-Domain (FDTD) method. The propagation constant of each antenna was extracted from the resulting field distribution for comparison with a transverse resonance approximation, measured far-field patterns, and other simulated antennas. Variations of the geometry were …

Head Tracking For 3d Audio Using A Gps-Aided Mems Imu, Jacque M. Joffrion

Theses and Dissertations

Audio systems have been developed which use stereo headphones to project sound in three dimensions. When using these 3D audio systems, audio cues sound like they are originating from a particular direction. There is a desire to apply 3D audio to general aviation applications, such as projecting control tower transmissions in the direction of the tower or providing an audio orientation cue for VFR pilots who find themselves in emergency zero-visibility conditions. 3D audio systems, however, require real-time knowledge of the pilot's head orientation in order to be effective. This research describes the development and testing of a low-cost head …

Multiple Model Adaptive Estimator Target Tracker For Maneuvering Targets In Clutter, Brian D. Smith

Theses and Dissertations

The task of tracking a target in the presence of measurement clutter is a two-fold problem: one of handling measurement association uncertainty (due to clutter), and poorly known or significantly varying target dynamics. Measurement association uncertainty does not allow conventional tracking algorithms (such as Kalman filters) to be implemented directly. Poorly known or varying target dynamics complicate the design of any tracking filter, and filters using only a single dynamics model can rarely handle anything beyond the most benign target maneuvers. In recent years, the Multiple Hypothesis Tracker (MHT) has gained acceptance as a means of handling targets in a …

Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using A Linear Frequency Modulated Random Stepped-Frequency Waveform, Jason R. Mcmahon

Theses and Dissertations

This research examines the theory, application, and results of using Random Stepped-Frequency (RSF) waveforms to mitigate Doppler aliasing in a wide-angle Synthetic Aperture Radar (SAR) imaging scenario. Severe Doppler aliasing typically occurs in this scenario since range extent requirements force the pulse repetition frequency to a value violating the lower bound for Doppler aliasing. Building on previous research, this work expands upon RSF waveform analysis using a Linear Frequency Modulated RSF (LFM-RSF) waveform. The RSF waveform suppresses Doppler aliasing by positioning nulls at the aliased scatterer location. Applying LFM with RSF processing theoretically provides greater frequency coverage and aliased scatterer …

Analysis And Design Of Switched Capacitor Converters, Jonathan W. Kimball, Philip T. Krein

Electrical and Computer Engineering Faculty Research & Creative Works

Switched capacitor converters have become more common in recent years. Crucial to understanding the maximum power throughput and efficiency is a model of the converter's equivalent resistance. A new form for equivalent resistance is derived and discussed in a design context. Quasi-resonant operation is also explored and compared to non-resonant operation. Several capacitor technologies are evaluated and compared.

Sea Ice Mapping Method For Seawinds, David G. Long, Hyrum S. Anderson

Faculty Publications

A sea ice mapping algorithm for SeaWinds is developed that incorporates statistical and spatial a priori information in a modified maximum a posteriori (MAP) framework. Spatial a priori data are incorporated in the loss terms of a Bayes risk formulation. Conditional distributions and priors for sea ice and ocean statistics are represented as empirical histograms that are forced to conform to a set of expected histograms via principal component filtering. Tuning parameters for the algorithm allow adjustments in the algorithm's performance. Results of the algorithm exhibit high correlation with the Remund-Long sea ice mapping algorithm for SeaWinds and the Special …

Multi-Aoi-System For Easy Changing Angles Of Incidence In Ellipsometer, Polarimeter And Reflectometer Systems, Blaine D. Johs, Ping He, Martin M. Liphardt, Christopher A. Goeden, John A. Woollam, James D. Welch

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed is a system for enabling easy sequential setting of different Angles-of-Incidence of a beam of electromagnetic radiation to a surface of a sample system, and to regression based methodology for evaluating and compensating the effects of the presence of electromagnetic beam intercepting angle-of-incidence changing systems, including where desired, parameterization of calibration parameters.

Implicit Indicators For Interesting Web Pages, Hyoung-Rae Kim, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

A user's interest in a web page can be estimated by unobtrusively (implicitly) observing his or her behaviour rather than asking for feedback directly (explicitly). Implicit methods are naturally less accurate than explicit methods, but they do not waste a user's time or effort. Implicit indicators of a user's interests can also be used to create models that change with a user's interests over time. Research has shown that a user's behavior is related to his/her interest in a web page. We evaluate previously studied implicit indicators and examine the time spent on a page in more detail. For example, …

Learning Rules For Time Series Anomaly Detection, Matthew V. Mahoney, Philip K. Chan

Electrical Engineering and Computer Science Faculty Publications

We describe a multi-dimensional time series anomaly detection method in which each point in a test series is required to match the value, slope, and curvature of a point seen in training (with an optional sequential constraint), and a method of generating a model in the form of concise, human-comprehensible, and editable rules. Training time complexity is O(n log n), and testing is O(n). The method generalizes to multiple training series by allowing test points to fall within the range bounded by the training data. We use this approach to detect test failures in Marotta fuel control valves used on …

A Virtual Environment For Remote Testing Of Complex Systems, Loredana Cristaldi, Alessandro Ferrero, Antonello Monti, Ferdinanda Ponci, William Mckay, Roger A. Dougal

Faculty Publications

Complex systems, realized by integration of several components or subsystems, pose specific problems to simulation environments. It is, in fact, desirable to simulate the complex system altogether, and not component by component, since the operation of the single part depends on the surrounding system and an early verification can prevent damages and save time for modifications. The availability of detailed and validated models of the single parts is therefore critical. This task may be difficult to achieve. In fact, in industrial applications, where a system can be a mix of different devices produced by different manufacturers, the physical device may …

Pulse Regulation Control Technique For Integrated High-Quality Rectifier-Regulators, Mehdi Ferdowsi, Ali Emadi

Electrical and Computer Engineering Faculty Research & Creative Works

The pulse regulation control scheme is presented and applied to the boost integrated flyback rectifier/energy storage dc/dc (BIFRED) converter as the most popular member of the integrated high-quality rectifier-regulators (IHQRR). In contrast to the conventional control techniques, the principal idea of pulse regulation is to regulate the output voltage using a series of high- and low-power pulses generated by the current of the input inductor, which is operating in discontinuous conduction mode (DCM). Analysis of the BIFRED converter operating in DCM is presented. Fundamentals of pulse regulation as well as its stability analysis and the estimation of the output voltage …

Improving Voltage Stability By Reactive Power Reserve Management, Feng Dong, Badrul H. Chowdhury, Mariesa Crow, Levent Acar

Electrical and Computer Engineering Faculty Research & Creative Works

The amount of reactive reserves at generating stations is a measure of the degree of voltage stability. With this perspective, an optimized reactive reserve management scheme based on the optimal power flow is proposed. Detailed models of generator limiters, such as those for armature and field current limiting must be considered in order to utilize the maximum reactive power capability of generators, so as to meet reactive power demands during voltage emergencies. Participation factors for each generator in the management scheme are predetermined based on the voltage-var (V-Q) curve methodology. The Bender's decomposition methodology is applied to the reactive reserve …

Microwave Backscatter Modeling Of Erg Surfaces In The Sahara Desert, David G. Long, Haroon Stephen

Faculty Publications

The Sahara desert includes large expanses of sand dunes called ergs. These dunes are formed and constantly reshaped by prevailing winds. Previous study shows that Saharan ergs exhibit significant radar backscatter (σ˚) modulation with azimuth angle (∅). We use σ˚ measurements observed at various incidence angles and ∅ from the NASA Scatterometer (NSCAT), the SeaWinds scatterometer, the ERS scatterometer (ESCAT), and the Tropical Rainfall Measuring Mission's Precipitation Radar to model the σ˚ response from sand dunes. Observations reveal a characteristic relationship between the backscatter modulation and the dune type, i.e., the number and orientation of the dune slopes. Sand dunes …

Turbo Space-Time Coding For Mimo Systems : Designs And Analyses, Hangjun Chen

Dissertations

Multiple input multiple output (MIMO) systems can provide high diversity, high data rate or a mix of both, for wireless communications. This dissertation combines both modes and suggests analyses and techniques that advance the state of the art of MIMO systems. Specifically, this dissertation studies turbo space-time coding schemes for MIMO systems.

Before the designs of turbo space-time codes are presented, a fundamental tool to analyze and design turbo coding schemes, the extrinsic information transfer (EXIT) chart method, is extended from the binary/nonbinary code case to coded modulation case. This extension prepares the convergence analysis for turbo space-time code.

Turbo …

Detection Of Network Anomalies And Novel Attacks In The Internet Via Statistical Network Traffic Separation And Normality Prediction, Jun Jiang

Dissertations

With the advent and the explosive growth of the global Internet and the electronic commerce environment, adaptive/automatic network and service anomaly detection is fast gaining critical research and practical importance. If the next generation of network technology is to operate beyond the levels of current networks, it will require a set of well-designed tools for its management that will provide the capability of dynamically and reliably identifying network anomalies. Early detection of network anomalies and performance degradations is a key to rapid fault recovery and robust networking, and has been receiving increasing attention lately.

In this dissertation we present a …

Image Data Hiding, Zhicheng Ni

Dissertations

Image data hiding represents a class of processes used to embed data into cover images.

Robustness is one of the basic requirements for image data hiding. In the first part of this dissertation, 2D and 3D interleaving techniques associated with error-correction-code (ECC) are proposed to significantly improve the robustness of hidden data against burst errors.

In most cases, the cover image cannot be inverted back to the original image after the hidden data are retrieved. In this dissertation, one novel reversible (lossless) data hiding technique is then introduced. This technique is based on the histogram modification, which can embed a …

Photocontrol Data Acquisition System For Lamp Life Prediction In High Pressure Sodium Lighting, Jeffrey William Tisa

Theses and Dissertations

This thesis begins with a brief historical account of high intensity discharge (HID) lighting. It begins in the seventeenth century and concludes with the modem high pressure sodium (HPS) lamp, which has become the most widespread HID lighting source due to its high efficacy (Lumens/Watt) and acceptable color rendition. Following a more in-depth discussion on the HPS lamp, a means of estimating the arc tube voltage of an HPS lamp from the confines of a photocontrol is introduced. This technique is implemented as part of a 'smart' photocontrol data acquisition unit that functions as part of a proposed practical asset …

Study Of Steganalysis Methods, Wen Chen

Theses

Steganography is the art and science of hiding the presence of conmunication by embedding secret message into digital images. The steganographic techniques can be applied in many areas. On one hand, people can benefit from their application. For example, they can be used for copyright protection. On the other hand, these techniques may be used by criminals or terrorists for malicious purposes. For example, terrorists may use the techniques to transmit the secret plan of terror attacks. Law enforcement and security authorities have concerns about such activities. It is necessary to devise the methods to detect steganographic systems. The detection …

A Digital Signature And Watermarking Based Authentication System For Jpeg2000 Images, Rui Jing

Theses

In this thesis, digital signature based authentication system was introduced, which is able to protect JPEG2000 images in different flavors, including fragile authentication and semi-fragile authentication. The fragile authentication is to protect the image at code-stream level, and the semi-fragile is to protect the image at the content level.

The semi-fragile can be further classified into lossy and lossless authentication. With lossless authentication, the original image can be recovered after verification. The lossless authentication and the new image compression standard, JPEG2000 is mainly discussed in this thesis.

Publicly Verifiable Private Credentials - A Technique For Privately Signing Citizen Initiatives, Kishore R. Kattamuri, Marius C. Silaghi

Electrical Engineering and Computer Science Faculty Publications

Besides voting, another way of practicing democracy is by signing popular / citizen initiatives or optional referendums of certain types. We address the problems related to the electronic remote signing of support for referendums and popular initiatives (e-referendums). We propose, publicly verifiable private credentials (PVPCs) , a type of certified pseudonym digital signatures for which one can publicly prove that only eligible users (belonging to a specified group) got them and that no user got two of them. They can be used to sign citizen initiatives. Our technique generates PVPCs that can be publicly proven to belong to an unknown …

Supporting Debates Over Citizen Initiatives, Kishore R. Kattamuri, Marius C. Silaghi

Electrical Engineering and Computer Science Faculty Publications

Popular / citizen initiatives provide a way for the inclusion of constitutional or statutory proposals on the ballot (e.g., at an election) if enough signatures are collected in support of the proposal. Once citizens are enabled to digitally sign such initiatives remotely, the next challenge will be to provide support for verified eligible citizens to debate on running initiatives. Intelligent ways of structuring information for easy access and cooperation is a major research interest in computer science, with results like WWW, Semantic Web, Forums, Blogs, Slashdot. We propose here a new interaction paradigm for debates in the setting where participants …

A Study Of Style Effects On Ocr Errors In The Medline Database, Penny Garrison, Diane Davis, Tim Andersen, Elisa Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

The National Library of Medicine has developed a system for the automatic extraction of data from scanned journal articles to populate the MEDLINE database. Although the 5-engine OCR system used in this process exhibits good performance overall, it does make errors in character recognition that must be corrected in order for the process to achieve the requisite accuracy. The correction process works by feeding words that have characters with less than 100% confidence (as determined automatically by the OCR engine) to a human operator who then must manually verify the word or correct the error. The majority of these errors …