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Articles 91 - 120 of 349
Full-Text Articles in Electrical and Electronics
Trade-Offs In A 1 Tbps Mimo Communication System Between An Airship And An Array Of Ground Receive Antennas, Adam R. Brueggen
Trade-Offs In A 1 Tbps Mimo Communication System Between An Airship And An Array Of Ground Receive Antennas, Adam R. Brueggen
Theses and Dissertations
As demand for higher data-rate wireless communications increases, so will the interest in multiple-input and multiple-output (MIMO) systems. In a single transmitter, single receiver communication system, there is a fundamental limit to the data-rate capacity of the system proportional to the systems bandwidth. Since increasing the bandwidth is expensive and limited, another option is increasing the system's capacity by adding multiple antennas at the transmitter and receiver to create a MIMO communication system. With a T transmitter, R receiver MIMO communication system, TR channels are created which allow extremely high data-rates. MIMO systems are attractive because they are extremely robust …
Electro-Luminescent Area Illumination Device, Michael E. Miller, Ronald S. Cok
Electro-Luminescent Area Illumination Device, Michael E. Miller, Ronald S. Cok
AFIT Patents
An electro-luminescent area illumination device that includes two or more area emitters formed on a substrate. Each of the two or more area emitters emit light having different area illumination profiles.
Sparsening Filter Design For Iterative Soft-Input Soft-Output Detectors, Raquel G. Machado, Andrew G. Klein, Richard K. Martin
Sparsening Filter Design For Iterative Soft-Input Soft-Output Detectors, Raquel G. Machado, Andrew G. Klein, Richard K. Martin
Faculty Publications
A large body of research exists around the idea of channel shortening, where a prefilter is designed to reduce the effective channel impulse response to some smaller number of contiguous taps. This idea was originally conceived to reduce the complexity of Viterbi-based maximum-likelihood equalizers. Here, we consider a generalization of channel shortening which we term "channel sparsening". In this case, a prefilter is designed to reduce the effective channel to a small number of nonzero taps which do not need to be contiguous. When used in combination with belief-propagation-based maximum a posteriori (MAP) detectors, an analogous complexity reduction can be …
Electroluminescent Area Illumination With Integrated Mechanical Switch, Ronald S. Cok, Michael E. Miller
Electroluminescent Area Illumination With Integrated Mechanical Switch, Ronald S. Cok, Michael E. Miller
AFIT Patents
An electroluminescent lam including a lamp substrate; a first electrode formed over the lamp substrate device side, one or more layers having light-emitting material formed over the first electrode, and a second electrode formed over the one or more layers, a chiplet having a chiplet substrate separate and independent from the lamp substrate and adhered to the lamp substrate device side, one or more connection pads, a mechanical switch, and a control circuit for controlling the mechanical switch, the mechanical switch electrically connected to one or more connection pads and at least one connection pad electrically connected to the first …
Method For Converting An Input Color Signal, Ronald S. Cok, Michael E. Miller
Method For Converting An Input Color Signal, Ronald S. Cok, Michael E. Miller
AFIT Patents
A white light-emitting microcavity light-emitting diode device, comprising a method for converting a red, green, and blue (RGB) input signal to a converted signal having RGB color signals and an additional saturated color signal, by calculating saturation of the additional saturated color in the RGB input signal to determine the proportion of the additional saturated color signal to the sum of the converted RGB color signals such that the proportion of the additional saturated color signal is constant or decreases as the saturation of the additional color in the RGB input signal increases.
Stereoscopic Display System With Flexible Rendering Of Disparity Map According To The Stereoscopic Fusing Capability Of The Observer, Elaine W. Jin, Michael E. Miller, Serguei Endrikhovski, Cathleen D. Cerosaletti
Stereoscopic Display System With Flexible Rendering Of Disparity Map According To The Stereoscopic Fusing Capability Of The Observer, Elaine W. Jin, Michael E. Miller, Serguei Endrikhovski, Cathleen D. Cerosaletti
AFIT Patents
A method is provided for customizing scene content, according to a user or a cluster of users, for a given stereoscopic display, including obtaining customization information about the user; obtaining a scene disparity map for a pair of given stereo images and/or a three-dimensional (3D) computer graphic model; and determining an aim disparity range for the user. The method of the present invention also generates a customized disparity map and/or rendering conditions for a three-dimensional (3D) computer graphic model correlating with the user's fusing capability of the given stereoscopic display; and renders or re-renders the stereo images for subsequent display.
Linear-Quadratic Control Of A Mems Micromirror Using Kalman Filtering, Jamie P. Schnapp
Linear-Quadratic Control Of A Mems Micromirror Using Kalman Filtering, Jamie P. Schnapp
Theses and Dissertations
The deflection limitations of electrostatic flexure-beam actuators are well known. Specifically, as the beam is actuated and the gap traversed, the restoring force necessary for equilibrium increases proportionally with the displacement to first order, while the electrostatic actuating force increases with the inverse square of the gap. Equilibrium, and thus stable open-loop voltage control, ceases at one-third the total gap distance, leading to actuator snap-in. A Kalman Filter is designed with an appropriately complex state dynamics model to accurately estimate actuator deflection given voltage input and capacitance measurements, which are then used by a Linear Quadratic controller to generate a …
Flexible Multitouch Electroluminescent Display, Michael E. Miller, John W. Harmer
Flexible Multitouch Electroluminescent Display, Michael E. Miller, John W. Harmer
AFIT Patents
A display device including a touch sensitive EL display having a flexible substrate; one or more power busses and one or more EL elements disposed over the flexible substrate; and a plurality of distributed chiplets arranged so that at least two chiplets are associated with each of a plurality of touch sensitive areas on the EL display and for sensing stress or strain associated with bending of the flexible substrate or the chiplet substrate to provide respective displacement signals corresponding to the touch sensitive areas; each chiplet connected to one or more of the power busses and one or more …
Using Reputation Based Trust To Overcome Malfunctions And Malicious Failures In Electric Power Protection Systems, Jose E. Fadul
Using Reputation Based Trust To Overcome Malfunctions And Malicious Failures In Electric Power Protection Systems, Jose E. Fadul
Theses and Dissertations
This dissertation advocates the use of reputation-based trust in conjunction with a trust management framework based on network flow techniques to form a trust management toolkit (TMT) for the defense of future Smart Grid enabled electric power grid from both malicious and non-malicious malfunctions. Increases in energy demand have prompted the implementation of Smart Grid technologies within the power grid. Smart Grid technologies enable Internet based communication capabilities within the power grid, but also increase the grid's vulnerability to cyber attacks. The benefits of TMT augmented electric power protection systems include: improved response times, added resilience to malicious and non-malicious …
Critical Information Technology On Fpgas Through Unique Device Specific Keys, Miles E. Mcgee
Critical Information Technology On Fpgas Through Unique Device Specific Keys, Miles E. Mcgee
Theses and Dissertations
Field Programmable Gate Arrays (FPGAs) are being used for military and other sensitive applications, the threat of an adversary attacking these devices is an ever present danger. While having the ability to be reconfigured is helpful for development, it also poses the risk of its hardware design being cloned. Static random access memory (SRAM) FPGA's are the most common type of FPGA used in industry. Every time an SRAM-FPGA is powered up, its configuration must be downloaded. If an adversary is able to obtain that configuration, they can clone sensitive designs to other FPGAs. A technique that can be used …
Led Device Having Improved Light Output, Ronald S. Cok, Michael E. Miller
Led Device Having Improved Light Output, Ronald S. Cok, Michael E. Miller
AFIT Patents
A thin-film, white-light-emitting diode device includes a reflective, conductive thin-film structure and a semi-transparent, conductive thin-film structure. One or more thin-film layers are formed between the reflective and semi-transparent conductive thin-film structures to form two or more commonly-controlled microcavity structures. The thin-film layers emit white light in response to current provided by the conductive thin-film structure. Each of the two or more commonly-controlled microcavity structures has a different resonant frequency within one or more optical cavities and emits light with a smaller spectral range than the spectral range of the white-light-emitting thin-film layer(s). A combination of light emitted from the …
Passive Matrix Electro-Luminescent Display System, Michael E. Miller, John F. Hamilton Jr., Andrew D. Arnold
Passive Matrix Electro-Luminescent Display System, Michael E. Miller, John F. Hamilton Jr., Andrew D. Arnold
AFIT Patents
A passive matrix, electro-luminescent display system has a passive matrix, electro-luminescent display having an orthogonally oriented array of column and row electrodes and an electro-luminescent layer located between the electrodes at the intersection of each column and row electrode forming an individual light-emitting element. Drivers provide separate signals at different times to different groups of row electrodes within the array of row electrodes; wherein the row electrodes of each group simultaneously receive at least two different level signals. A display driver receives and processes the input image signal to provide a presharpened image control signal. Column drivers respond to the …
Characteristics Of A High Intensity, Pulsed, Potassium Vapor Laser In A Heat Pipe, Edward J. Hurd
Characteristics Of A High Intensity, Pulsed, Potassium Vapor Laser In A Heat Pipe, Edward J. Hurd
Theses and Dissertations
This thesis research paper presents the results of experiments using an optically pumped, pulsed potassium vapor laser in a heat pipe. The absorption on the potassium D2 line, output laser characteristics, and Raman scattering in potassium vapor are discussed. The spectral full width at half maximum (FWHM) of the D2 absorption line was much greater than predicted values for pressure broadening due to the high number density of potassium atoms and the long path length. At 320°C and 0 torr of helium, the FWHM was 765 GHz. At 100 torr it was 968 GHz. At 200 torr it …
Radiation Induced Fault Detection, Diagnosis, And Characterization Of Field Programmable Gate Arrays, Thomas B. Getz
Radiation Induced Fault Detection, Diagnosis, And Characterization Of Field Programmable Gate Arrays, Thomas B. Getz
Theses and Dissertations
The development of Field Programmable Gate Arrays (FPGAs) has been a great achievement in the world of micro-electronics. One of these devices can be programmed to do just about anything, and replace the need for thousands of individual specialized devices. Despite their great versatility, FPGAs are still extremely vulnerable to radiation from cosmic waves in space and from adversaries on the ground. Extensive research has been conducted to examine how radiation disrupts different types of FPGAs. The results show, unfortunately, that the newer FPGAs with smaller technology are even more susceptible to radiation damage than the older ones. This research …
High Frequency Direction Finding Using Structurally Integrated Antennas On A Large Airborne Platform, Clair F. Corbin
High Frequency Direction Finding Using Structurally Integrated Antennas On A Large Airborne Platform, Clair F. Corbin
Theses and Dissertations
Estimating the angle of arrival (AOA) of a high frequency (HF) signal, 2-32 MHz, is challenging, especially if the antenna array is installed on a platform with dimensions on the order of one wavelength. Accurate AOA estimates are necessary for search and rescue operations and geolocating RF emitters of interest. This research examines the performance of a direction finding (DF) system using structurally integrated (SI) antennas installed on an airborne platform which allows the aircraft structure to become the receiving element. Two simulated DF systems are analyzed at 4 and 11 MHz. The relationship between the number of SI antennas …
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 …
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 …
Spectral Domain Rf Fingerprinting For 802.11 Wireless Devices, Sheldon A. Munns
Spectral Domain Rf Fingerprinting For 802.11 Wireless Devices, Sheldon A. Munns
Theses and Dissertations
The increase in availability and reduction in cost of commercial communication devices (e.g. IEEE compliant such as 802.11, WiFi, 802.16, Bluetooth etc.) has increased wireless user exposure and the need for techniques to properly identify/classify signals for increased security measures. Communication device emissions include intentional modulation that enables correct device operation. Hardware and environmental factors alter the ideal response and induce unintentional modulation effects. If these effects (features) are sufficiently unique, it becomes possible to identify a device using its fingerprint, with potential discrimination of not only the manufacturer but possibly the serial number for a given manufacturer. Many techniques …
Pulse Shape Correlation For Laser Detection And Ranging (Ladar), Brian T. Deas
Pulse Shape Correlation For Laser Detection And Ranging (Ladar), Brian T. Deas
Theses and Dissertations
Radar systems provide an important remote sensing capability, and are crucial to the layered sensing vision; a concept of operation that aims to apply the right number of the right types of sensors, in the right places, at the right times for superior battle space situational awareness. The layered sensing vision poses a range of technical challenges, including radar, that are yet to be addressed. To address the radar-specific design challenges, the research community responded with waveform diversity; a relatively new field of study which aims reduce the cost of remote sensing while improving performance. Early work suggests that the …
Toward A Mobile Agent Relay Network, Hyon H. Kwak
Toward A Mobile Agent Relay Network, Hyon H. Kwak
Theses and Dissertations
Although wireless communication provides connectivity where hardwired links are difficult or impractical, it is still hindered by the environmental conditions where the communicators reside. Signal loss over large distances or because of intervening obstacles can be mitigated by increasing the user's transmission power or adding repeater nodes between the users. Unfortunately, increasing the signal strength strains limited power resources and increases the likelihood of eavesdropping. Stationary repeaters are impractical for highly mobile users in dangerous environments. While mobile relay nodes might be a preferred solution, a centralized control scheme saps bandwidth from important traffic and introduces a single point of …
Improved Multispectral Skin Detection And Its Application To Search Space Reduction For Dismount Detection Based On Histograms Of Oriented Gradients, Adam L. Brooks
Theses and Dissertations
Due to the general shift from conventional warfare to terrorism and urban warfare by enemies of the United States in the late 20th Century, locating and tracking individuals of interest have become critically important. Dismount detection and tracking are vital to provide security and intelligence in both combat and homeland defense scenarios including base defense, combat search and rescue (CSAR), and border patrol. This thesis focuses on exploiting recent advances in skin detection research to reliably detect dismounts in a scene. To this end, a signal-plus-noise model is developed to map modeled skin spectra to the imaging response of an …
Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson
Monocular Passive Ranging By An Optical System With Band Pass Filtering, Joel R. Anderson
Theses and Dissertations
An instrument for monocular passive ranging based on atmospheric oxygen absorption near 762 nm has been designed, built and deployed to track emissive targets, including the plumes from jet engines or rockets. An intensified CCD array is coupled to variable band pass liquid crystal display filter and 3.5 – 8.8 degree field of view optics to observe the target. By recording sequential images at 7 Hz in three 6 nm width bands, the transmittance of the R-branch of the O2 (X-b) (0,0) band is determined. A metric curve for determining range from transmittance is developed using the HITRAN spectral …
Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris
Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris
Theses and Dissertations
Investigation of the optical and electrical behavior of some semiconductors at very high temperatures has not been an area of much study, at least not experimentally. The importance of such research becomes obvious due to the effects of high temperatures on semiconductor devices such as infrared detectors and light emitters. Besides the destructive effects of thermal stress and melting, changes in the optical properties of the material can greatly affect device performance. In this research, the infrared absorption of Si, Ge, GaAs, GaSb, InAs, and InP was measured from 0.6 to 25 μm at temperatures ranging from 295 up to …
Flexible Computing Architecture For Real Time Skin Detection, Matthew P. Hornung
Flexible Computing Architecture For Real Time Skin Detection, Matthew P. Hornung
Theses and Dissertations
In both the Air Force and Search and Rescue Communities, there is a current need to detect and characterize persons. Existing methods use red-green-blue (RGB) imagery, but produce high false alarm rates. New technology in multi-spectral skin detection is better than the existing RGB methods, but lacks a control and processing architecture to make them efficient for real time problems. We hypothesize that taking a minimalistic approach to the software design, we can perform image preprocessing, feature computation, and skin detection in real time. A number of applications require accurate detection and characterization of persons, human measurement and signature intelligence …
Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady
Frequency Diverse Array Radar: Signal Characterization And Measurement Accuracy, Steven H. Brady
Theses and Dissertations
Radar systems provide an important remote sensing capability, and are crucial to the layered sensing vision; a concept of operation that aims to apply the right number of the right types of sensors, in the right places, at the right times for superior battle space situational awareness. The layered sensing vision poses a range of technical challenges, including radar, that are yet to be addressed. To address the radar-specific design challenges, the research community responded with waveform diversity; a relatively new field of study which aims reduce the cost of remote sensing while improving performance. Early work suggests that the …
Characterization And Measurement Of Passive And Active Metamaterial Devices, Christopher A. Lundell
Characterization And Measurement Of Passive And Active Metamaterial Devices, Christopher A. Lundell
Theses and Dissertations
This document addresses two major obstacles facing metamaterial development: uncertainty in the characterization of electromagnetic field behavior in metamaterial structures and the relatively small operational bandwidth of metamaterial structures. To address the first obstacle, a new method to characterize electromagnetic field behavior in a metamaterial is presented. This new method is a bistatic radar cross section (RCS) measurement technique. RCS measurements are well-suited to measuring bulk metamaterial samples because they show frequency dependence of scattering angles and offer common postprocessing techniques that can be useful for visualizing results. To address the second obstacle, this document characterizes the effectiveness of an …
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman
Theses and Dissertations
The ability to manipulate a complex impedance sheet about a PEC or general dielectric cylinder of arbitrary diameter to control the overall scattering characteristics at particular angles for shielding or scattering applications is presented. It is shown that with the capability to readily control both the real and imaginary components of a percolated lossy film's effective impedance, specific impedance distributions can be obtained to effectively direct the overall nulls in the bistatic scattering pattern. The exact approach only requires negligible truncation error of the matrix solution and can be applied to cylinders of arbitrary size. This approach relies on general …
Wireless Sensor Network Radio Power Management And Simulation Models, Michael I. Brownfield, Theresa Nelson, Scott Midkiff, Nathaniel J. Davis Iv
Wireless Sensor Network Radio Power Management And Simulation Models, Michael I. Brownfield, Theresa Nelson, Scott Midkiff, Nathaniel J. Davis Iv
Faculty Publications
Wireless sensor networks (WSNs) create a new frontier in collecting and processing data from remote locations. The IEEE 802.15.4 wireless personal area network-low rate (WPAN-LR) WSNs rely on hardware simplicity to make sensor field deployments both affordable and long-lasting without maintenance support. WSN designers strive to extend network lifetimes while meeting application-specific throughput and latency requirements. Effective power management places sensor nodes (or motes) into one of the available energy-saving modes based upon the sleep period duration and the current state of the radio. The newest generation of WPAN-LR-based sensor platform radios operates at a 250 kbps data rate and …
Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane
Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane
AFIT Patents
A MEMS switch fabrication process and apparatus inclusive of a bulbous rounded surface movable contact assembly that is integral with the switch movable element and achieving of long contact wear life with low contact electrical resistance. The disclosed process is compatible with semiconductor integrated circuit fabrication materials and procedures and includes an unusual photoresist reflow step in which the bulbous contact shape is quickly defined in three dimensions from more easily achieved integrated circuit mask and etching-defined precursor shapes. A plurality of differing photoresist materials are used in the process. A large part of the contact and contact spring formation …
Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith
Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith
Theses and Dissertations
When a camera is affixed on a dynamic mobile robot, image stabilization is the first step towards more complex analysis on the video feed. This thesis presents a novel electronic image stabilization (EIS) algorithm for small inexpensive highly dynamic mobile robotic platforms with onboard camera systems. The algorithm combines optical flow motion parameter estimation with angular rate data provided by a strapdown inertial measurement unit (IMU). A discrete Kalman filter in feedforward configuration is used for optimal fusion of the two data sources. Performance evaluations are conducted by a simulated video truth model (capturing the effects of image translation, rotation, …