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Articles 1 - 30 of 65
Full-Text Articles in Engineering
Eit, Slow Light, And Sealing Methods For Embedding Rubidium Into The Arrow System, Katherine Barnett Hurd
Eit, Slow Light, And Sealing Methods For Embedding Rubidium Into The Arrow System, Katherine Barnett Hurd
Theses and Dissertations
Light-matter interactions are fundamentally based on the quantum mechanical principles that govern photons, electrons and other fundamental particles. One very interesting phenomenon within all of light-matter interactions is Electromagnetically Induced Transparency(EIT). This phenomenon causes an otherwise absorbing atomic transition to stop absorbing through quantum mechanical interference of probability wave functions. Corresponding to that change in absorption, will be a sudden, large change in the index of refraction. This change in the index of refraction leads to another phenomenon in which the group velocity of light can be slowed down dramatically. In the past, many researchers have been able to achieve …
A Linear Combination Of Heuristics Approach To Spatial Sampling Hyperspectral Data For Target Tracking, Barry R. Secrest
A Linear Combination Of Heuristics Approach To Spatial Sampling Hyperspectral Data For Target Tracking, Barry R. Secrest
Theses and Dissertations
Persistent surveillance of the battlespace results in better battlespace awareness which aids in obtaining air superiority, winning battles, and saving friendly lives. Although hyperspectral imagery (HSI) data has proven useful for discriminating targets, it presents many challenges as a useful tool in persistent surveillance. A new sensor under development has the potential of overcoming these challenges and transforming our persistent surveillance capability by providing HSI data for a limited number of pixels and grayscale video for the remainder. The challenge of exploiting this new sensor is determining where the HSI data in the sensor's field of view will be the …
An Onboard Vision System For Unmanned Aerial Vehicle Guidance, Barrett Bruce Edwards
An Onboard Vision System For Unmanned Aerial Vehicle Guidance, Barrett Bruce Edwards
Theses and Dissertations
The viability of small Unmanned Aerial Vehicles (UAVs) as a stable platform for specific application use has been significantly advanced in recent years. Initial focus of lightweight UAV development was to create a craft capable of stable and controllable flight. This is largely a solved problem. Currently, the field has progressed to the point that unmanned aircraft can be carried in a backpack, launched by hand, weigh only a few pounds and be capable of navigating through unrestricted airspace. The most basic use of a UAV is to visually observe the environment and use that information to influence decision making. …
Mimo Channel Spatial Covariance Estimation: Analysis Using A Closed-Form Model, Yanling Yang
Mimo Channel Spatial Covariance Estimation: Analysis Using A Closed-Form Model, Yanling Yang
Theses and Dissertations
Multiple-input Multiple-output (MIMO) wireless communication systems allow increased spectral efficiency and therefore promise significant improvement in performance. However, because of the rapid variation in channel state information (CSI) in networks with mobile nodes or scatterers, it is difficult both to maintain high communication performance and to create channel models that effectively represent the time-varying behavior of the channels. The spatial covariance of the MIMO channel describes the average power gain on each transmit-receive antenna pair as well as the correlation between the complex link gains and thus provides critical information for understanding the performance of the system and for creating …
A Framework Based On Gaussian Mixture Models And Kalman Filters For The Segmentation And Tracking Of Anomalous Events In Shipboard Video, Ben Wenger
Theses and Dissertations
Anomalous indications in monitoring equipment on board U.S. Navy vessels must be handled in a timely manner to prevent catastrophic system failure. The development of sensor data analysis techniques to assist a ship's crew in monitoring machinery and summon required ship-to-shore assistance is of considerable benefit to the Navy. In addition, the Navy has a large interest in the development of distance support technology in its ongoing efforts to reduce manning on ships. In this thesis, algorithms have been developed for the detection of anomalous events that can be identified from the analysis of monochromatic stationary ship surveillance video streams. …
Perpetual Exploration Of Relational Information And Enhanced Star Glyphs For Multi-Source Data Visualization, Andrew Crowell
Perpetual Exploration Of Relational Information And Enhanced Star Glyphs For Multi-Source Data Visualization, Andrew Crowell
Theses and Dissertations
Information Visualization is an area of research concerned with the presentation of abstract data in a visual format. It has many diverse applications in fields of software engineering, information sciences, biology, chemistry, and medical, among others. This thesis is primarily concerned with the application of information visualization to the display of directed graphs and to the display of multivariate data for analysis. Two novel applications will be presented that are both advancements in the field of information visualization. The first application applies to the visualization and navigation of large or infinite graphs and networks. The quality of a graph drawing …
Scatterometer Contamination Mitigation, Michael Paul Owen
Scatterometer Contamination Mitigation, Michael Paul Owen
Theses and Dissertations
Microwave scatterometers, which use radar backscatter measurements to infer the near-surface wind vector, are unique in their ability to monitor global wind vectors at high resolutions. However, scatterometer observations which are contaminated by land proximity or rain events produce wind estimates which have increased bias and variability, making them unreliable for many applications. Fortunately, the effects of these sources of contamination can be mitigated. Land contamination of backscatter measurements occurs when land partially fills the antenna illumination area. This reduces and masks the wind-induced backscatter signal. Land contamination is mitigated by quantifying the amount of contamination in a single observation …
Improving Range Estimation Of A 3d Flash Ladar Via Blind Deconvolution, Jason R. Mcmahon
Improving Range Estimation Of A 3d Flash Ladar Via Blind Deconvolution, Jason R. Mcmahon
Theses and Dissertations
The purpose of this research effort is to improve and characterize range estimation in a three-dimensional FLASH LAser Detection And Ranging (3D FLASH LADAR) by investigating spatial dimension blurring effects. The myriad of emerging applications for 3D FLASH LADAR both as primary and supplemental sensor necessitate superior performance including accurate range estimates. Along with range information, this sensor also provides an imaging or laser vision capability. Consequently, accurate range estimates would also greatly aid in image quality of a target or remote scene under interrogation. Unlike previous efforts, this research accounts for pixel coupling by defining the range image mathematical …
Determining The Index Of Refraction Of An Unknown Object Using Passive Polarimetric Imagery Degraded By Atmospheric Turbulence, Milo W. Hyde Iv
Determining The Index Of Refraction Of An Unknown Object Using Passive Polarimetric Imagery Degraded By Atmospheric Turbulence, Milo W. Hyde Iv
Theses and Dissertations
In this research, an algorithm is developed to estimate the index of refraction of an unknown object using passive polarimetric images degraded by atmospheric turbulence. The algorithm uses a variant of the maximum-likelihood blind-deconvolution algorithm developed by LeMaster and Cain to recover the true object (i.e., the first Stokes parameter), the degree of linear polarization, and the polarimetric-image point spread functions. Nonlinear least squares is then used to find the value of the complex index of refraction which best fits the theoretical degree of linear polarization, derived using a polarimetric bidirectional reflectance distribution function, to the turbulence-corrected degree of linear …
Applying Image Matching To Video Analysis, Adam J. Behring
Applying Image Matching To Video Analysis, Adam J. Behring
Theses and Dissertations
Dealing with the volume of multimedia collected on a daily basis for intelligence gathering and digital forensics investigations requires significant manual analysis. A component of this problem is that a video may be reanalyzed that has already been analyzed. Identifying duplicate video sequences is difficult due to differences in videos of varying quality and size. This research uses a kd-tree structure to increase image matching speed. Keypoints are generated and added to a kd-tree of a large dimensionality (128 dimensions). All of the keypoints for the set of images are used to construct a global kd-tree, which allows nearest neighbor …
Analysis Of Alternative Methods For Long-Term Wind Speed And Initial Site Assessment For Purposes Of Wind Energy Production Estimation, Ryan Mcdevitt
Analysis Of Alternative Methods For Long-Term Wind Speed And Initial Site Assessment For Purposes Of Wind Energy Production Estimation, Ryan Mcdevitt
Theses and Dissertations
A need exists for identification and evaluation of viable sites for wind energy. However, this is made difficult by the site-specific nature of the wind. A review of current industry practices shows that linear regression is the preferred method, although little work has been done to investigate alternative approaches. To address this, various methods were tested on 23 target sites with data measured over a long-term period. Each site was analyzed with the chosen best reference station, across 10 data periods for each method with results classified as mean absolute percentage error in energy density between the projected and measured …
Low-Loss Hollow Waveguide Platforms For Optical Sensing And Manipulation, Evan J. Lunt
Low-Loss Hollow Waveguide Platforms For Optical Sensing And Manipulation, Evan J. Lunt
Theses and Dissertations
This dissertation presents a method for fabricating integrated hollow and solid optical waveguides on planar substrates. These waveguides are antiresonant reflecting optical waveguides (ARROWs), where high-index cladding layers confine light to hollow cores through optical interference. Hollow waveguides that can be filled with liquids or gases are an important new building block for creating highly-integrated optical sensors. The method developed for fabricating these integrated waveguides employs standard processes and materials used in the microelectronics industry, allowing for parallel, low-cost fabrication. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD). After the lower cladding layers …
Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin
Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin
Theses and Dissertations
Lab-on-a-chip devices, also known as micro total analysis systems (μTAS), are implementations of chemical analysis systems on microchips. These systems can be fabricated using standard thin film processing techniques. Microfluidic and nanofluidic channels are fabricated in this work through sacrificial etching. Microchannels are fabricated utilizing cores made from AZ3330 and SU8 photoresist. Multi-channel electroosmotic (EO) pumps are evaluated and the accompanying channel zeta potentials are calculated. Capillary flow is studied as an effective filling mechanism for nanochannels. Experimental departure from the Washburn model is considered, where capillary flow rates lie within 10% to 70% of theoretical values. Nanochannels are fabricated …
Growth And Characterization Of Non-Polar Gan Materials And Investigation Of Efficiency Droop In Ingan Light Emitting Diodes, Xianfeng Ni
Theses and Dissertations
General lighting with InGaN light emitting diodes (LEDs) as light sources is of particular interest in terms of energy savings and related environmental benefits due to high lighting efficiency, long lifetime, and Hg-free nature. Incandescent and fluorescent light sources are used for general lighting almost everywhere. But their lighting efficiency is very limited: only 20-30 lm/W for incandescent lighting bulb, approximately 100 lm/W for fluorescent lighting. State-of-the-art InGaN LEDs with a luminous efficacy of over 200 lm/W at room temperature have been reported. However, the goal of replacing the incandescent and fluorescent lights with InGaN LEDs is still elusive since …
System Development And Integration Of An Airborne Laser Communications Payload For Unmanned Aircraft Systems, Mariusz Czarnomski
System Development And Integration Of An Airborne Laser Communications Payload For Unmanned Aircraft Systems, Mariusz Czarnomski
Theses and Dissertations
Free space laser communications provides wide bandwidth and high security capabilities to Unmanned Aircraft Systems (UAS) in order to successfully accomplish Intelligence, Surveillance, Target Acquisition, and Reconnaissance (IST AR) missions. A practical implementation of a laser-based video communications payload flown by a small U AS aircraft is described as a proof-of-concept. The two-axis gimbal pointing control algorithm calculates the line-of-sight vector in real-time by using Differential Global Positioning System (DGPS) and Inertial Measurement Unit (IMU) information gathered from the UAS vehicle's autopilot so that the laser transmitter in the airborne payload can accurately track a ground-based photodiode array receiver with …
Impedance Imaging And Measurements By Micro Probes In Aqueous Environments, Tao Shang
Impedance Imaging And Measurements By Micro Probes In Aqueous Environments, Tao Shang
Theses and Dissertations
The dissertation presented here describes two research projects that may, at first glance, seem unrelated. Their unifying principle is the measurement of electrical impedance for the detection and analysis of biological materials. Impedance measurements have long been employed and studied in scientific fields, and the dissertation begins with a summary of historical methodology, applications, and terminology. Utilizing impedance measurements for microscopic imaging is the driving motivation for Scanning Impedance Imaging (SII). This technique manifests the distribution of electrical impedance inside biological tissues and is described after the dissertation's introduction. SII can provide micron-scale imaging resolution by scanning a shielded microprobe …
Wireless Sensor Network Approach To Aeronautical Telemetry, Oluwasegun Babatunde Tinubi
Wireless Sensor Network Approach To Aeronautical Telemetry, Oluwasegun Babatunde Tinubi
Theses and Dissertations
Wireless sensor networks have become a rapidly growing research field in recent years. They are envisioned to have a wide range of applications in military, environmental and many other fields. We examine the performance of wireless sensor network applications to aeronautical telemetry. To date, test ranges have relied on a single telemetry ground station for the reception of packets from all air borne transmitters. We researched an alternate means of achieving this same goal with fewer resources. It is a well known fact that communication power and bandwidth are the most expensive commodities in wireless communications. The telemetry world is …
Attaining Realistic Simulations Of Mobile Ad-Hoc Networks, Derek J. Huber
Attaining Realistic Simulations Of Mobile Ad-Hoc Networks, Derek J. Huber
Theses and Dissertations
Mobile Ad-hoc Networks (MANET) are comprised of wireless systems that communicate without the assistance of centrally managed routers or base stations. MANET research and development has increased due to computing technologies offering smaller, faster, smarter, and more power efficient platforms to operate on. Largely the testing and evaluation of new and existing MANET protocols has resided in simulation environments. This is due in part to the complexities and expenses incurred when conducting real world tests. Many researchers have come to recognize that these current simulations tend to assume away critical components of the MANET domain. These assumptions are made either …
Architectural Considerations For Single Operator Management Of Multiple Unmanned Aerial Vehicles, Gabriel T. Bugajski
Architectural Considerations For Single Operator Management Of Multiple Unmanned Aerial Vehicles, Gabriel T. Bugajski
Theses and Dissertations
Recently, small Unmanned Aircraft Systems (UAS) have become ubiquitous in military battlefield operations due to their intelligence collection capabilities. However, these unmanned systems consistently demonstrate limitations and shortfalls with respect to size, weight, range, line of sight and information management. The United States Air Force Unmanned Aircraft Systems Flight Plan 2009-2047 describes an action plan for improved UAS employment which calls out single operator, multi-vehicle mission configurations. This thesis analyzes the information architecture using future concepts of operations, such as biologically-inspired flocking mechanisms. The analysis and empirical results present insight into the engineering of single-operator multiple-vehicle architectures.
Scatterometer Image Reconstruction Tuning And Aperture Function Estimation For Advanced Microwave Scanning Radiometer On The Earth Observing System, Brian Adam Gunn
Scatterometer Image Reconstruction Tuning And Aperture Function Estimation For Advanced Microwave Scanning Radiometer On The Earth Observing System, Brian Adam Gunn
Theses and Dissertations
AMSR-E is a space-borne radiometer which measures Earth microwave emissions or brightness temperatures (Tb) over a wide swath. AMSR-E data and images are useful in mapping valuable Earth-surface and atmospheric phenomena. A modified version of the Scatterometer Image Reconstruction (SIR) algorithm creates Tb images from the collected data. SIR is an iterative algorithm with tuning parameters to optimize the reconstruction for the instrument and channel. It requires an approximate aperture function for each channel to be effective. This thesis presents a simulator-based optimization of SIR iteration and aperture function threshold parameters for each AMSR-E channel. A comparison of actual Tb …
An Ensemble-Based Computational Approach For Incremental Learning In Non-Stationary Environments Related To Schema- And Scaffolding-Based Human Learning, Ryan Elwell
Theses and Dissertations
The principal dilemma in a learning process, whether human or computer, is adapting to new information, especially in cases where this new information conflicts with what was previously learned. The design of computer models for incremental learning is an emerging topic for classification and prediction of large-scale data streams undergoing change in underlying class distributions (definitions) over time; yet currently, they often ignore significant foundational learning theory that has been developed in the domain of human learning. This shortfall leads to many deficiencies in the ability to organize existing knowledge and to retain relevant knowledge for long periods of time. …
An Efficient Implementation Of An Exponential Random Number Generator In A Field Programmable Gate Array (Fpga), Smitha Gautham
An Efficient Implementation Of An Exponential Random Number Generator In A Field Programmable Gate Array (Fpga), Smitha Gautham
Theses and Dissertations
Many physical, biological, ecological and behavioral events occur at times and rates that are exponentially distributed. Modeling these systems requires simulators that can accurately generate a large quantity of exponentially distributed random numbers, which is a computationally intensive task. To improve the performance of these simulators, one approach is to move portions of the computationally inefficient simulation tasks from software to custom hardware implemented in Field Programmable Gate Arrays (FPGAs). In this work, we study efficient FPGA implementations of exponentially distributed random number generators to improve simulator performance. Our approach is to generate uniformly distributed random numbers using standard techniques …
Design And Feasibility Testing For A Ground-Based, Three-Dimensional, Ultra-High-Resolution, Synthetic Aperture Radar To Image Snowpacks, Stephen Joseph Preston
Design And Feasibility Testing For A Ground-Based, Three-Dimensional, Ultra-High-Resolution, Synthetic Aperture Radar To Image Snowpacks, Stephen Joseph Preston
Theses and Dissertations
This thesis works through the design of a radar-based system for imaging snowpacks remotely and over large areas to assist in avalanche prediction. The key to such a system is the ability to image volumes of snow at shallow, spatially-varying angles of incidence. To achieve this prerequisite, the design calls for a ground-based Synthetic Aperture Radar (SAR) capable of generating three-dimensional, ultra-high-resolution images of a snowpack. To arrive at design parameters for this SAR, the thesis works through relevant principles in avalanche mechanics, alpine-snowpack geophysics, and electromagnetic scattering theory. The thesis also works through principles of radar, SAR, antenna, and …
Secret Key Establishment Using Wireless Channels As Common Randomness In Time-Variant Mimo Systems, Chan Chen
Secret Key Establishment Using Wireless Channels As Common Randomness In Time-Variant Mimo Systems, Chan Chen
Theses and Dissertations
Encryption of confidential data with a secret key has become a widespread technique for securing wireless transmissions. However, existing key distribution methods that either deliver the secret key with a key distribution center or exchange the secret key using public-key cryptosystems are unable to establish perfect secret keys necessary for symmetric encryption techniques. This research considers secret key establishment, under the broad research area of information theoretic security, using the reciprocal wireless channel as common randomness for the extraction of perfect secret keys in multiple-input multiple-output (MIMO)communication systems. The presentation discusses the fundamental characteristics of the time-variant MIMO wireless channel …
Signal Processing Methods For Ultra-High Resolution Scatterometry, Brent A. Williams
Signal Processing Methods For Ultra-High Resolution Scatterometry, Brent A. Williams
Theses and Dissertations
This dissertation approaches high resolution scatterometry from a new perspective. Three related general topics are addressed: high resolution σ^0 imaging, wind estimation from high resolution σ^0 images over the ocean, and high resolution wind estimation directly from the scatterometer measurements. Theories of each topic are developed, and previous approaches are generalized and formalized. Improved processing algorithms for these theories are developed, implemented for particular scatterometers, and analyzed. Specific results and contributions are noted below. The σ^0 imaging problem is approached as the inversion of a noisy aperture-filtered sampling operation-extending the current theory to deal explicitly with noise. A maximum aposteriori …
Composite Kernel Feature Analysis For Cancer Classification, Sindhu Myla
Composite Kernel Feature Analysis For Cancer Classification, Sindhu Myla
Theses and Dissertations
Computed tomographic (CT) colonography, or virtual colonoscopy, is a promising technique for screening colorectal cancers by use of CT scans of the colon. Current CT technology allows a single image set of the colon to be acquired in 10-20 seconds, which translates into an easier, more comfortable examination than is available with other screening tests. Currently, however, interpretation of an entire CT colonography examination is time-consuming, and the reader performance for polyp detection varies substantially. To overcome these difficulties while providing a high detection performance of polyps, researchers are developing computer-aided detection (CAD) schemes that automatically detect suspicious lesions in …
Tuning Of Electrical Properties In Inaln/Gan Hfets And Ba0.5sr0.5tio3/Yig Phase Shifters, Jacob H. Leach
Tuning Of Electrical Properties In Inaln/Gan Hfets And Ba0.5sr0.5tio3/Yig Phase Shifters, Jacob H. Leach
Theses and Dissertations
Engineers know well from an early point in their training the trials and tribulations of having to make design tradeoffs in order to optimize one performance parameter for another. Discovering tradeoff conditions that result in the elimination of a loss associated with the enhancement of some other parameter (an improvement over a typical tradeoff), therefore, ushers in a new paradigm of design in which the constraints which are typical of the task at hand are alleviated. We call such a design paradigm “tuning” as opposed to “trading off”, and this is the central theme of this work. We investigate two …
Investigation Of Rf Curing Parameters In Resin Infusion Molding, Christopher K. Love
Investigation Of Rf Curing Parameters In Resin Infusion Molding, Christopher K. Love
Theses and Dissertations
The purpose of this study is to investigate RF or Radio Frequency energy as a viable alternative to traditional heating methods for the purpose of curing resins used in resin infusion molding, a molding system for polymeric composites. Traditional heating/curing methods include technologies such as room temperature, oven, microwave, infrared, and ultraviolet. Although RF curing provides far more advantages than disadvantages, its implementation into a manufacturing process can be challenging. Specifically, three critical elements must be present in order for RF to function in a manner that is profitable to the manufacturer. Those elements are: (1) the proper generator (voltage …
Automatic Identification And Tracking Of Retraction Fibers In Time-Lapse Microscopy, Meher Talat Shaikh
Automatic Identification And Tracking Of Retraction Fibers In Time-Lapse Microscopy, Meher Talat Shaikh
Theses and Dissertations
Digital image processing is widely used in the field of time-lapse microscopy and biological research to provide statistical data of cellular dynamics. The data can provide more comprehensive understanding of the molecular phenomenon. Further, digital image processing enables rapid and consistent quantification of qualitative observations. The image processing model examined here provides a study to identify structures called retraction fibers (RFs) that are formed during epithelial-mesenchymal transition (EMT) [1], an important developmental process which also occurs during cancer metastasis. Quantifying RF formation is an important task for biologists studying cellular regulation of EMT. This thesis work uses digital image processing …
Generalized Image Formation For Pulsed And Lfm-Cw Synthetic Aperture Radar, Evan C. Zaugg
Generalized Image Formation For Pulsed And Lfm-Cw Synthetic Aperture Radar, Evan C. Zaugg
Theses and Dissertations
Approximations made in the traditional signal model for synthetic aperture radar (SAR) processing cause defocusing of the radar images when the system operates under conditions where the approximations lose validity. This dissertation investigates a number of these approximations and presents algorithmic improvements based on generalizations of the approxmations of the SAR signal model. These improvements result in better focused imagery from SAR systems with varied designs and parameters. Among the advancements presented is the development of a generalized chirp-scaling algorithm and a generalized frequency scaling algorithm to address the problems caused by approximations based on a Taylor series expansion of …