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Articles 1 - 11 of 11
Full-Text Articles in Engineering
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, …
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
Theses and Dissertations
As a result of previous efforts [Pachter, Barba, 2007] a tight control loop was designed to meet performance specifications while minimizing the feedback control system’s gains of a spacecraft mounted flexible antenna. Emphasis is now shifted to on orbit system identification of the antenna dynamics in order to increase nominal plant knowledge, estimate plant uncertainty bounds, as well as determine the disturbance band. Non-parametric system identification is undertaken. Knowledge of the plant dynamics along with the corresponding uncertainty bounds will provide for the design of a control system which meets the specifications (tracking and disturbance rejection) while at the same …
Full-Wave Based Validation Of Stripline Field Applicator For Low Frequency Material Measurements, James H. Crane Ii
Full-Wave Based Validation Of Stripline Field Applicator For Low Frequency Material Measurements, James H. Crane Ii
Theses and Dissertations
This research presents the analysis and verification of a stripline designed by Air Force Research Laboratory for use in measuring the electrical properties of materials at low frequencies and high temperature. It is designed to operate in the TEM mode up to 4 Ghz and have a characteristic impedance of 50 ohms. A full wave base method is used to analyze the structure. The parallel plate waveguide dyadic Green's function is developed for a current immersed in a PEC parallel plate environment. It is used to formulate a pair of coupled electric field integral equations (CIE). These CIEs are solved …
Characterization Of Hardening By Design Techniques On Commercial, Small Feature Sized Field-Programmable Gate Arrays, Thomas E. Simmons
Characterization Of Hardening By Design Techniques On Commercial, Small Feature Sized Field-Programmable Gate Arrays, Thomas E. Simmons
Theses and Dissertations
In this thesis, a methodology is developed to experimentally test and evaluate a programmable logic device unde r gamma irradiation. The purpose of which is to determine the radiation effects and characterize the improvements of various hardening by design techniques. The techniques analyzed in this thesis include Error Correction Coding (ECC) and Triple Modular Redundancy (TMR). The TMR circuit includes three different functional implementations of adders compared to TMR voted circuits of those same adders. The TMR is implemented with the same functional adders and as a Functional TMR (FTMR) with three different function adders that are voted on. The …
Implementation Of Collaborative Rf Localization Using A Software-Defined Radio Network, Augustine A. Honore
Implementation Of Collaborative Rf Localization Using A Software-Defined Radio Network, Augustine A. Honore
Theses and Dissertations
This thesis investigates the use of collaboration between sensor nodes that were tasked with localizing a radio frequency emitter. Localization is a necessary component for dynamic spectrum access. Using a set of software-defined radios as our sensors and a received signal strength-based maximum likelihood localization algorithm, we successfully localized transmitting nodes based on their received signal strength. Our experiment was conducted outdoors using a flexible topology that could be shaped into 21 sub-topologies that varied in size, and orientation with respect to the transmitters. This was made possible through application of a time shift concept and a post-processing technique. We …
Using Shadows To Detect Targets In Synthetic Aperture Radar Imagery, Brian P. Donnell
Using Shadows To Detect Targets In Synthetic Aperture Radar Imagery, Brian P. Donnell
Theses and Dissertations
Synthetic Aperture Radar (SAR) can generate high resolution imagery of re- mote scenes by combining the phase information of multiple radar pulses along a given path. SAR based Intelligence, Surveillance, and Reconnaissance (ISR) has the advantage over optical ISR that it can provide usable imagery in adverse weather or nighttime conditions. Certain radar frequencies can even result in foliage or limited soil penetration, enabling imagery to be created of objects of interest that would otherwise be hidden from optical surveillance systems. This thesis demonstrates the capability of locating stationary targets of interest based on the locations of their shadows and …
Electron Multipactor: Theory Review, Comparison And Modeling Of Mitigation Techniques In Icepic, Neil G. Rogers
Electron Multipactor: Theory Review, Comparison And Modeling Of Mitigation Techniques In Icepic, Neil G. Rogers
Theses and Dissertations
Mitigation approaches for single surface multipactor at dielectric windows are investigated using Particle-In-Cell (PIC) simulations. Initially baseline susceptibility diagrams are constructed analytically and compared with self-consistent, dynamic system trajectories. The power deposited on the surface of a dielectric window in an HPM system is considered using three different methods and the results of PIC simulations. Geometric mitigation is then considered by varying the window orientation with respect to the HPM electric held. Small angular deviations, less than 20 degrees, from the nominal case of normal incidence show dramatic changes in the susceptibility diagram. A materials approach to mitigation is then …
Surface Acoustic Wave Devices As Chemical Vapor Sensors, Daniel Gallagher
Surface Acoustic Wave Devices As Chemical Vapor Sensors, Daniel Gallagher
Theses and Dissertations
In order to effectively neutralize non-traditional threats to US forces and population such as improvised explosive devices (IED) and chemical, biological, radio- logical, nuclear, and explosive (CBNRE) weapons, a flexible vapor sensor platform is proposed. This work involves the design, fabrication, and testing of coated surface acoustic wave devices for vapor sensing ability. Devices were fabricated in-house using MEMS fabrication techniques, then coated with a thin layer of a Nafion polymer. The frequency response of coated devices displayed 2 MHz frequency shifts around the resonance frequency upon introduction of ethanol vapors into the nitrogen vapor stream. This indicates strong sensing …
Power Generation By Harvesting Ambient Energy With A Micro-Electromagnetic Generator, James H. Shields
Power Generation By Harvesting Ambient Energy With A Micro-Electromagnetic Generator, James H. Shields
Theses and Dissertations
This thesis investigated the potential power output of a micro-electromagnetic generator fabricated using typical microfabrication materials and techniques. The design was based on a desire to free bio-implanted or remote electronic devices from batteries and their finite power supplies. A micro-electromagnetic generator could harvest energy from the ambient environment and power such devices indefinitely. Designs for the stator coil and rotor magnet components of the generator were optimized to produce maximum current density based upon electromagnetic theory. The relative orientation of the coil to the rotor and material selection for each component were considered. Coils were fabricated using low-resistance gold. …
A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus
A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus
Theses and Dissertations
Negative refractive index materials are an example of metamaterials that are becoming increasingly popular. Research into these metamaterials could possibly be the first steps toward bending electromagnetic radiation (i.e., microwaves, light, etc.) around an object or person. Split ring resonators (SRR) are classified as metamaterials that create an artificial magnetic response from materials with no inherent magnetic properties. Once fabricated, an SRR has a specific resonant frequency due to its permanent geometry. This research introduces a new concept of using a variable capacitive micro- electro-mechanical system (MEMS) device located at the gap of an SRR to mechanically alter the capacitance …