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Articles 1 - 30 of 48
Full-Text Articles in Engineering
Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington
Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington
Theses and Dissertations
This research outlines the development and simulation of a signal processing approach to real time wavefront curvature sensing in adaptive optics. The signal processing approach combines vectorized Charge Coupled Device (CCD) read out with a wavefront modal estimation technique. The wavefront sensing algorithm analyzes vector projections of image intensity data to provide an estimate of the wavefront phase as a combination of several low order Zernike polynomial modes. This wavefront sensor design expands on an existing idea for vector based tilt sensing by providing the ability to compensate for additional modes. Under the proposed wavefront sensing approach, the physical wavefront …
Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake
Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake
Theses and Dissertations
A new sensor, the Advanced Electro-Optical System (AEOS) Spectral Imaging Sensor (ASIS) has been developed at the Maui Space Surveillance Complex (MSSC). ASIS is capable of collecting resolved imagery of space objects in 10's-100's of spectral bands while using an adaptive optics system. However, the stringent requirements of collecting ground-based images requires a sensor that induces spectral blurring. Post-processing algorithms to remove this blurring are required to fully exploit these spectral images. This research focuses on developing the reconstruction algorithms, based on proven estimation theories, required to spectrally deblur the images collected from ASIS. Additionally, the research will expand the …
Blind Speaker Clustering, Ananth N. Iyer, Uchechukwu O. Ofoegbu, Robert E. Yantorno, Brett Y. Smolenski
Blind Speaker Clustering, Ananth N. Iyer, Uchechukwu O. Ofoegbu, Robert E. Yantorno, Brett Y. Smolenski
Ananth N Iyer
A novel approach to performing speaker clustering in telephone conversations is presented in this paper. The method is based on a simple observation that the distance between populations of feature vectors extracted from different speakers is greater than a preset threshold. This observation is incorporated into the clustering problem by the formulation of a constrained optimization problem. A modified c-means algorithm is designed to solve the optimization problem. Another key aspect in speaker clustering is to determine the number of clusters, which is either assumed or expected as an input in traditional methods. The proposed method does not require such …
Generic Modeling Applied To Speaker Count, Ananth N. Iyer, Uchechukwu O. Ofoegbu, Robert E. Yantorno, Brett Y. Smolenski
Generic Modeling Applied To Speaker Count, Ananth N. Iyer, Uchechukwu O. Ofoegbu, Robert E. Yantorno, Brett Y. Smolenski
Ananth N Iyer
The problem of determing the number of speakers participating in a conversation and building their models in short conversations, within an unknown group of speakers, is addressed in this paper. The lack of information about the number of speakers and the unavailability of sufficient data present a challenging task of efficiently estimating the speaker model parameters. The proposed method uses a novel generic speaker identification (GSID) system as a guide in the model building process. The GSID system is designed performing speaker identification where the speaker associated with the test data may not be enrolled. The models in the GSID …
Lightweight In-Plane Actuated Deformable Mirrors For Space Telescopes, Michael J. Shepherd
Lightweight In-Plane Actuated Deformable Mirrors For Space Telescopes, Michael J. Shepherd
Theses and Dissertations
This research focused on lightweight, in-plane actuated, deformable mirrors, with the ultimate goal of developing a 20- meter light gathering aperture for space telescopes. The 0.127 meter diameter deformable mirror small scale testbed was modelled infinite elements using MSC.Nastran software and then used as a basis for a quasi-static controller. Experimental tracking of Zernike tip, tilt, and defocus modes was accomplished. The analytical solutions to plate-membrane and beam-string ordinary differential equations were developed. A simplified approach to modelling the axisymmetric cases was also presented. A novel static control strategy, the Modal Transformation Method, was developed to form Zernike surfaces within …
Detection Of A Third Speaker In Telephone Conversations, Uchechukwu O. Ofoegbu, Ananth N. Iyer, Robert E. Yantorno, Stanley J. Wenndt
Detection Of A Third Speaker In Telephone Conversations, Uchechukwu O. Ofoegbu, Ananth N. Iyer, Robert E. Yantorno, Stanley J. Wenndt
Ananth N Iyer
Differentiating speakers participating in telephone conversations is a challenging task in speech processing because only short consecutive utterances can be examined for each speaker. Research has shown that, given only brief utterances (1 second or less), humans can recognize speakers with an accuracy of about 54% on average. The task becomes even more challenging when no information about the speakers is known a priori. In this paper, a technique for determining whether there are two or three speakers participating in a telephone conversation is presented. This approach assumes no knowledge or information about any of the participating speakers. The technique …
Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy
Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy
Theses and Dissertations
Maintaining a precision navigation solution both in a GPS hostile jamming environment and also in a GPS non-compatible terrain area is of great importance. To that end, this thesis evaluates the ability to navigate using signals from the AM band of the electromagnetic spectrum (520 to 1710 kHz). Navigation position estimates are done using multi-lateration techniques similar to GPS. However, pseudoranges are created using Time Difference of Arrival (TDOA) distances between a reference receiver and a mobile receiver, allowing the mobile receiver to obtain absolute position estimates over time. Four methods were developed for estimating the cross-correlation peak within a …
Fast Scene Based Nonuniformity Correction With Minimal Temporal Latency, Christopher A. Rice
Fast Scene Based Nonuniformity Correction With Minimal Temporal Latency, Christopher A. Rice
Theses and Dissertations
The focus of this research was to derive a new algorithm for correction of gain nonuniformities in LIDAR focal plane arrays using as few frames as possible. Because of the current low production rate of LIDAR focal plane arrays there is a natural tendency for extreme nonuniformities to exist on a pixel by pixel basis as the manufacturing technique has not yet been perfected. Generally, nonuniformity correction techniques require a large number of frames and/or have obscure requirements on the translational shifts in the input image frames. This thesis presents a solution for finding multiplicative nonuniformities that exist in a …
Laser Covariance Vibrometry For Unsymmetrical Mode Detection, Michael C. Kobold
Laser Covariance Vibrometry For Unsymmetrical Mode Detection, Michael C. Kobold
Theses and Dissertations
Simulated cross - spectral covariance (CSC) from optical return from simulated surface vibration indicates CW phase modulation may be an appropriate phenomenology for adequate classification of vehicles by structural mode. The nonlinear structural to optical relationship is close to unity, avoiding nulls and high values; optical return contains sufficient spectral ID information necessary for data clustering. The FE model has contact between the homogeneous rolled armor and vehicle hull, a simple multi - layer skin model typical of most vehicles. Most of the high frequency energy moved to lower frequencies. This nonlinearity segments contact vibration modes into two classes: symmetrical …
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Theses and Dissertations
The motivation of this research is to address the limitations of satellite-based navigation by fusing imaging and inertial systems. The research begins by rigorously describing the imaging and navigation problem and developing practical models of the sensors, then presenting a transformation technique to detect features within an image. Given a set of features, a statistical feature projection technique is developed which utilizes inertial measurements to predict vectors in the feature space between images. This coupling of the imaging and inertial sensors at a deep level is then used to aid the statistical feature matching function. The feature matches and inertial …
Generalized Perceptual Linear Prediction (Gplp) Features For Animal Vocalization Analysis, Patrick J. Clemins, Michael T. Johnson
Generalized Perceptual Linear Prediction (Gplp) Features For Animal Vocalization Analysis, Patrick J. Clemins, Michael T. Johnson
Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations
A new feature extraction model, generalized perceptual linear prediction (gPLP), is developed to calculate a set of perceptually relevant features for digital signal analysis of animalvocalizations. The gPLP model is a generalized adaptation of the perceptual linear prediction model, popular in human speech processing, which incorporates perceptual information such as frequency warping and equal loudness normalization into the feature extraction process. Since such perceptual information is available for a number of animal species, this new approach integrates that information into a generalized model to extract perceptually relevant features for a particular species. To illustrate, qualitative and quantitative comparisons are made …
Blind Deconvolution Of Anisoplanatic Images Collected By A Partially Coherent Imaging System, Adam Macdonald
Blind Deconvolution Of Anisoplanatic Images Collected By A Partially Coherent Imaging System, Adam Macdonald
Theses and Dissertations
Coherent imaging systems offer unique benefits to system operators in terms of resolving power, range gating, selective illumination and utility for applications where passively illuminated targets have limited emissivity or reflectivity. This research proposes a novel blind deconvolution algorithm that is based on a maximum a posteriori Bayesian estimator constructed upon a physically based statistical model for the intensity of the partially coherent light at the imaging detector. The estimator is initially constructed using a shift-invariant system model, and is later extended to the case of a shift-variant optical system by the addition of a transfer function term that quantifies …
Fast Video Stabilization Algorithms, Mohammed A. Alharbi
Fast Video Stabilization Algorithms, Mohammed A. Alharbi
Theses and Dissertations
A fast and robust electronic video stabilization algorithm is presented in this thesis. It is based on a two-dimensional feature-based motion estimation technique. The method tracks a small set of features and estimates the movement of the camera between consecutive frames. It is used to characterize the motions accurately including camera rotations between two imaging instants. An affine motion model is utilized to determine the parameters of translation and rotation between images. The determined affine transformation is then exploited to compensate for the abrupt temporal discontinuities of input image sequences. Also, a frequency domain approach is developed to estimate translations …
A Novel Approach To Automated Source Separation In Multispeaker Environment, Robert M. Nickel, Ananth N. Iyer
A Novel Approach To Automated Source Separation In Multispeaker Environment, Robert M. Nickel, Ananth N. Iyer
Ananth N Iyer
We are proposing a new approach to the solution of the cocktail party problem (CPP). The goal of the CPP is to isolate the speech signals of individuals who are concurrently talking while being recorded with a properly positioned microphone array. The new approach provides a powerful yet simple alternative to commonly used methods for the separation of speakers. It is based on the observation that the estimation of the signal transfer matrix between speakers and microphones is significantly simplified if one can assure that during certain periods of the conversation only one speaker is active while all other speakers …
Emotion Detection From Infant Facial Expressions And Cries, Pritam Pal, Ananth N. Iyer, Robert E. Yantorno
Emotion Detection From Infant Facial Expressions And Cries, Pritam Pal, Ananth N. Iyer, Robert E. Yantorno
Ananth N Iyer
A new system for translating the infant cries from its facial image and cry sounds is presented in this paper. The system is designed to analyze the facial image and sound of the crying infant to derive the reason why the infant is crying. The image and the sound represent the same cry event. The image processing module determines the state of certain facial features, certain combinations of which determine the reason for crying. The sound processing module analyzes the data for the fundamental frequency and the first two formants and uses k-means clustering to determine the reason of the …
Multiple Masks-Based Pixel Comparison Steganalysis Method For Mobile Imaging, Sos S. Agaian, Gilbert L. Peterson, Benjamin M. Rodriguez
Multiple Masks-Based Pixel Comparison Steganalysis Method For Mobile Imaging, Sos S. Agaian, Gilbert L. Peterson, Benjamin M. Rodriguez
Faculty Publications
No abstract provided.
Performance-Metric Driven Atmospheric Compensation For Robust Free-Space Laser Communication, Peter N. Crabtree
Performance-Metric Driven Atmospheric Compensation For Robust Free-Space Laser Communication, Peter N. Crabtree
Theses and Dissertations
The effect of turbulence on laser propagation is a significant challenge to current electro-optical systems. While atmospheric compensation techniques in space object imaging and high-energy laser weapons have been thoroughly investigated, optimizing these techniques for Laser Communication (LaserCom) has not been examined to the same degree. Average Strehl ratio is the typical design metric for current atmospheric compensation systems. However, fade probability is the relevant metric for LaserCom. This difference motivated the investigation into metric-driven atmospheric compensation. Metric-based tracking techniques for fade mitigation is the first major focus of this research. In a moderate range air-to-air scenario, focal plane spot …
Adaptive Illumination Patterns For Radar Applications, Phillip M. Corbell
Adaptive Illumination Patterns For Radar Applications, Phillip M. Corbell
Theses and Dissertations
The fundamental goal of Fully Adaptive Radar (FAR) involves full exploitation of the joint, synergistic adaptivity of the radar's transmitter and receiver. Little work has been done to exploit the joint space time Degrees-of-Freedom (DOF) available via an Active Electronically Steered Array (AESA) during the radar's transmit illumination cycle. This research introduces Adaptive Illumination Patterns (AIP) as a means for exploiting this previously untapped transmit DOF. This research investigates ways to mitigate clutter interference effects by adapting the illumination pattern on transmit. Two types of illumination pattern adaptivity were explored, termed Space Time Illumination Patterns (STIP) and Scene Adaptive Illumination …
Uncertainty Estimation For Target Detection System Discrimination And Confidence Performance Metrics, David R. Parker
Uncertainty Estimation For Target Detection System Discrimination And Confidence Performance Metrics, David R. Parker
Theses and Dissertations
This research uses a Bayesian framework to develop probability densities for target detection system performance metrics. The metrics include the receiver operating characteristic (ROC) curve and the confidence error generation (CEG) curve. The ROC curve is a discrimination metric that quantifies how well a detection system separates targets and non-targets, and the CEG curve indicates how well the detection system estimates its own confidence. The degree of uncertainty in these metrics is a concern that previous research has not adequately addressed. This research formulates probability densities of the metrics and characterizes their uncertainty using confidence bands. Additional statistics are obtained …
Radiometric Analysis Of Daytime Satellite Detection, Katherine B. Lilevjen
Radiometric Analysis Of Daytime Satellite Detection, Katherine B. Lilevjen
Theses and Dissertations
A radiometric model for daylight satellite detection is developed and used to evaluate the effects of various parameters on signal-to-noise ratio (SNR). Detection of reflected sunlight from a low-earth orbit, diffuse, planar satellite by a single-pixel infrared photovoltaic detector is considered. Noise considered includes photon noise from the background and signal, as well as thermal noise. Parameters considered include atmospheric conditions, optical parameters, and detector parameters. The Phillips Laboratory Expert-assisted User System, an atmospheric modeling tool that employs the MODTRAN and FASCODE transmission codes, is used to model wavelength-dependent atmospheric transmission and background radiance. The SNR is found to increase …
Estimation Of Lyapunov Spectra From A Time Series, S. Srinivasan, Sanjay A. Patil, Saurabh Prasad, G. Lazarou, Joseph Picone
Estimation Of Lyapunov Spectra From A Time Series, S. Srinivasan, Sanjay A. Patil, Saurabh Prasad, G. Lazarou, Joseph Picone
Sanjay A. Patil
No abstract provided.
Sequential State-Space Filters For Speech Enhancement, Sanjay A. Patil, Ryan Irwin, Sundar Srinivasan, Saurabh Prasad, G. Lazarou, Joseph Picone
Sequential State-Space Filters For Speech Enhancement, Sanjay A. Patil, Ryan Irwin, Sundar Srinivasan, Saurabh Prasad, G. Lazarou, Joseph Picone
Sanjay A. Patil
No abstract provided.
Least Squares Support Vector Machine Based Classification Of Abnormalities In Brain Mr Images, S. Thamarai Selvi, D. Selvathi, R. Ramkumar, Henry Selvaraj
Least Squares Support Vector Machine Based Classification Of Abnormalities In Brain Mr Images, S. Thamarai Selvi, D. Selvathi, R. Ramkumar, Henry Selvaraj
Electrical & Computer Engineering Faculty Research
The manual interpretation of MRI slices based on visual examination by radiologist/physician may lead to missing diagnosis when a large number of MRIs are analyzed. To avoid the human error, an automated intelligent classification system is proposed. This research paper proposes an intelligent classification technique to the problem of classifying four types of brain abnormalities viz. Metastases, Meningiomas, Gliomas, and Astrocytomas. The abnormalities are classified based on Two/Three/ Four class classification using statistical and textural features. In this work, classification techniques based on Least Squares Support Vector Machine (LS-SVM) using textural features computed from the MR images of patient are …
Space-Time Adaptive Processing For Side-Looking Arrays With Platform Maneuver, John T. Buckreis
Space-Time Adaptive Processing For Side-Looking Arrays With Platform Maneuver, John T. Buckreis
Theses and Dissertations
This research effort develops a space-time adaptive processing (STAP) radar data model for the side-looking (SL) array with platform maneuver. A primary assumption of most STAP models is the absence of platform maneuver during the coherent processing interval (CPI). This research abandons the platform stationarity assumption, allowing platform pitch, roll, and yaw during the CPI. The model developed characterizes platform maneuver effects on the clutter spectrum, examines Matched Filter (MF) output Signal-to-Interference-plus-Noise-Ratio (SINR), and investigates maneuver impact on sample support homogeneity. The introduction of pitch marginally impacts MF SINR due to the lack of achieved azimuth resolution in this research, …
Forward-Looking Radar Clutter Suppression Using Frequency Diverse Arrays, Piotr Baizert
Forward-Looking Radar Clutter Suppression Using Frequency Diverse Arrays, Piotr Baizert
Theses and Dissertations
This thesis introduces a new array structure, the Frequency Diverse Array (FDA), where each channel transmits and receives at a different frequency. The resulting range-dependent FDA antenna pattern is proposed to improve forward-looking clutter suppression. The planar FDA radar data model is derived and analytically verified to be equivalent to the constant frequency data model when each element frequency is set to the same value. The linear FDA at high platform altitude provides significant benefits? by reducing the range ambiguous clutter contribution, improving target detection by up to 10 dB. At low altitudes without range ambiguous clutter the linear FDA …
Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks
Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks
Theses and Dissertations
The depth of absorption bands in observed spectra of distant, bright sources can be used to estimate range to the source. A novel approach is presented and demonstrated using observations of the oxygen absorption band near 762 nm. Range is estimated by comparing observed values of band-average absorption against curves derived from either historical data or model predictions. Curves are based on fitting a random band model to the data, which reduces average range error by 67% compared to the Beer's Law model used in previous work. A new modification to existing band models for long, inhomogeneous paths is presented …
Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson
Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson
Theses and Dissertations
This research effort examines side-looking airborne radar operation in hot clutter. In this context, hot clutter is an electronic counter-measure used to degrade airborne radar performance. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. This research uses a simplifying assumption where the bistatic hot clutter radar cross section (RCS) scattering statistics are identical to the monostatic clutter RCS scattering statistics. When the airborne jammer waveform scattered returns are perfectly coherent with the radar waveform, the radar cannot distinguish between the returns transmitted by the jammer and …
Characterization And Design Of High-Level Vhdl I/Q Frequency Downconverter Via Special Sampling Scheme, Jesse P. Somann
Characterization And Design Of High-Level Vhdl I/Q Frequency Downconverter Via Special Sampling Scheme, Jesse P. Somann
Theses and Dissertations
This study explores the characterization and implementation of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) down conversion utilizing top-level, portable design strategies. The SSS is an under-developed signal sampling methodology that can be used with military and industry receiver systems, specifically, United States Air Force (USAF) video receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and down converts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, there are three main objectives that will be accomplished: characterization of the effects of input, …
Image Processing Resource Allocation Methods For Multi-Target Tracking Of Dismounted Targets In Urban Environments, Jonathan P. Champion
Image Processing Resource Allocation Methods For Multi-Target Tracking Of Dismounted Targets In Urban Environments, Jonathan P. Champion
Theses and Dissertations
Dismounted targets can be tracked in urban environments with video sensors. Real-time systems are unable to process all of the imagery, demanding some method for prioritization of the processing resources. Furthermore, various segmentation algorithms exist within image processing, each algorithm possesses unique capabilities, and each algorithm has an associated computational cost. Additional complexity arises in the prioritization problem when targets become occluded (e.g., by a building) and when the targets are intermixed with other dismounted entities. This added complexity leads to the question "which portions of the scene warrant both low cost and high cost processing?" The approach presented in …
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt
Theses and Dissertations
This research effort examines the theory, application and results of side-looking airborne radar operation in hot clutter. Hot clutter is an electronic counter-measure used to degrade the performance of airborne radar. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. When the received RCS scattered hot clutter waveform is perfectly coherent with the radar waveform, the radar believes the returns created by the hot clutter jammer resulted from the transmitting radar. Hot clutter degrades radar performance at locations in azimuth and Doppler. The effect of hot clutter …