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Air Force Institute of Technology

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Articles 2851 - 2880 of 5700

Full-Text Articles in Engineering

Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary Mar 2009

Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary

Theses and Dissertations

Modernization in space systems requires employment of new light-weight, high performance composite materials that reduce bulk weight and increase structural integrity. This thesis explored the behavior of one such material prior to and following a 35-year simulated space radiation life-cycle. Select electrical properties of nickel nanostrandTM-carbon composites in seven configurations were characterized prior to electron irradiation via surface and bulk resistivity measurements and contact electrostatic discharge (ESD) measurements. Following irradiation at a fluence of 1016 e-/cm2 at an average energy of 500 keV, measurements were repeated and compared against pre-irradiation data. Configuration D is …

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Retroreflector For Photonic Doppler Velocimetry, Thomas J. Lagoski Mar 2009

Retroreflector For Photonic Doppler Velocimetry, Thomas J. Lagoski

Theses and Dissertations

In order to meet the goals of the Department of Defense (DoD) for smaller and more accurate weapons, the Munitions Directorate of the Air Force Research Laboratory (AFRL/RW) has numerous projects investigating the miniaturization of weapons and munition fuze components. One of these efforts is to characterize the performance of small detonators. The velocity of the flyer, the key component needed to initiate a detonation sequence, can be measured using a photonic Doppler velocimeter (PDV). The purpose of this research was to develop a microelectromechanical system (MEMS) device that would act as an optimal retroreflective surface for the PDV. Two …

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Micro-Scale Flapping Wings For The Advancement Of Flying Mems, Nicholas R. Coleman Mar 2009

Micro-Scale Flapping Wings For The Advancement Of Flying Mems, Nicholas R. Coleman

Theses and Dissertations

This research effort presents conceptual micro scale air vehicles whose total dimensions are less than one millimeter. The initial effort was to advance the understanding of micro aerial vehicles at sub-millimeter dimensions by fabricating and testing micro scale flapping wings. Fabrication was accomplished using a surface micromachining process called PolyMUMPs™. Both rigid mechanical structures and biomimetic devices were designed and fabricated as part of this effort. The rigid mechanical structures focused on out of plane deflections with solid connections and assembling a multiple hinge wing structure through the aid of residual stress. These devices were actuated by double hot arm …

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Surface Acoustic Wave Devices As Chemical Vapor Sensors, Daniel Gallagher Mar 2009

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 …

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Using Agent-Based Modeling To Evaluate Uas Behaviors In A Target-Rich Environment, Joseph A. Van Kuiken Mar 2009

Using Agent-Based Modeling To Evaluate Uas Behaviors In A Target-Rich Environment, Joseph A. Van Kuiken

Theses and Dissertations

The trade-off between accuracy and speed is a re-occurring dilemma in many facets of military performance evaluation. This is an especially important issue in the world of ISR. One of the most progressive areas of ISR capabilities has been the utilization of Unmanned Aircraft Systems (UAS). Many people believe that the future of UAS lies in smaller vehicles flying in swarms. We use the agent-based System Effectiveness and Analysis Simulation (SEAS) to create a simulation environment where different configurations of UAS vehicles can process targets and provide output that allows us to gain insight into the benefits and drawbacks of …

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A Hybrid Templated-Based Composite Classification System, Michael A. Turnbaugh Mar 2009

A Hybrid Templated-Based Composite Classification System, Michael A. Turnbaugh

Theses and Dissertations

An automatic target classification system contains a classifier which reads a feature as an input and outputs a class label. Typically, the feature is a vector of real numbers. Other features can be non-numeric, such as a string of symbols or alphabets. One method of improving the performance of an automatic classification system is through combining two or more independent classifiers that are complementary in nature. Complementary classifiers are observed by finding an optimal method for partitioning the problem space. For example, the individual classifiers may operate to identify specific objects. Another method may be to use classifiers that operate …

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The Hybrid Counterinsurgency Strategy: System Dynamics Employed To Develop A Behavioral Model Of Joint Strategy, Ferdinand Maldonado Mar 2009

The Hybrid Counterinsurgency Strategy: System Dynamics Employed To Develop A Behavioral Model Of Joint Strategy, Ferdinand Maldonado

Theses and Dissertations

Since the recent focus on the Global War on Terror, both military and civilian theorists have begun to “relearn” the intricacies of counterinsurgency warfare. We face difficult challenges when confronting non-state actors that tend to attack in the time between conventional battles and the establishment of stable governments. This research compares and contrasts current counterinsurgency strategies (Hearts and Minds and Cost Benefit Theory) by applying System Dynamics to provide insight into the influences and emergent behavior patterns of counterinsurgency systems. The information gained from the development of the models and from their simulation behaviors is used to construct a System …

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An Investigation Into The Feasibility Of Using A Modern Gravity Gradient Instrument For Passive Aircraft Navigation And Terrain Avoidance, Marshall M. Rogers Mar 2009

An Investigation Into The Feasibility Of Using A Modern Gravity Gradient Instrument For Passive Aircraft Navigation And Terrain Avoidance, Marshall M. Rogers

Theses and Dissertations

Recently, Gravity Gradient Instruments (GGIs) - devices which measure the spatial derivatives of gravity, have improved remarkably due to development of accelerometer technologies. Specialized GGIs are currently flown on aircraft for geological purposes in the mining industries. As such, gravity gradient data is recorded in flight and detailed gradient maps are created after post mission processing. These maps, if stored in a database onboard an aircraft and combined with a GGI, form the basis for a covert navigation system using a map matching process. This system is completely passive and essentially unjammable. To determine feasibility of this method, a GGI …

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Wind Tunnel Analysis And Flight Test Of A Wing Fence On A T-38, Michael D. Williams Mar 2009

Wind Tunnel Analysis And Flight Test Of A Wing Fence On A T-38, Michael D. Williams

Theses and Dissertations

A low-speed wind tunnel study and flight tests were performed to examine the effects of a wing fence on the T-38A. Wind tunnel results were based upon force and moment data collected with a six-component balance and flow visualization at Reynolds numbers up to 0.3 x 106, based on mean aerodynamic chord. The model did not include the last 7.79 feet of the aircraft, and the engine and exhaust were modeled as through-holes. Five fence geometries, placed at wing station 125 (± 0.825 semispan), were compared. The best performer of these designs, based on drag polar, was the …

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An Analysis Of Multiple Configurations Of Next-Generation Cathodes In A Low Power Hall Thruster, John E. Rotter Mar 2009

An Analysis Of Multiple Configurations Of Next-Generation Cathodes In A Low Power Hall Thruster, John E. Rotter

Theses and Dissertations

The research presented here is an effort to integrate an existing hollow cathode design with a low power production Hall thruster in multiple geometries. Both externally- and internally-mounted cathodes were fabricated and operated in conjunction with a Busek BHT-1500 Hall thruster. Three insert materials were evaluated; Cerium Hexaboride (CeB6), Lanthanum Hexaboride (LaB6), and impregnated tungsten. The thruster was operated at a single operating condition for all testing. The operating specifications for the discharge were 300 V and 2.25 A, giving a total power of 675 W. The boride-based cathodes were tested in both geometries while the tungsten-based cathode was only …

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Boundary Avoidance Tracking: Consequences (And Uses) Of Imposed Boundaries On Pilot-Aircraft Performance, Ryan D. Blake Mar 2009

Boundary Avoidance Tracking: Consequences (And Uses) Of Imposed Boundaries On Pilot-Aircraft Performance, Ryan D. Blake

Theses and Dissertations

This thesis presents the results of research into the Boundary Avoidance Tracking (BAT) theory, which states that often pilots control an aircraft not in an attempt to maintain some condition, but to avoid some real or perceived boundaries. This pilot modeling concept was studied using over 30 pilots in simulator and flight tests. The pilot-aircraft system was evaluated with 3 different lateral-directional control models. Pilots were given a roll angle tracking task in the presence of shrinking boundaries. Pilots were also given a secondary task in some of the profiles in order to measure workload. Approximately 42 hours of simulation …

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Abstracting Gis Layers From Hyperspectral Imagery, Torsten E. Howard Mar 2009

Abstracting Gis Layers From Hyperspectral Imagery, Torsten E. Howard

Theses and Dissertations

Modern warfare methods in the urban environment necessitates the use of multiple layers of sensors to manage the battle space. Hyperspectral imagers are one possible sensor modality to provide remotely sensed images that can be converted into Geographic Information Systems (GIS) layers. GIS layers abstract knowledge of roads, buildings, and scene content and contain shape files that outline and highlight scene features. Creating shape files is a labor-intensive and time-consuming process. The availability of shape files that reflect the current configuration of an area of interest significantly enhances Intelligence Preparation of the Battlespace (IPB). The solution presented in this thesis …

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Combat Identification Modeling Using Neural Network Techniques, Changwook Lim Mar 2009

Combat Identification Modeling Using Neural Network Techniques, Changwook Lim

Theses and Dissertations

The purposes of this research were: (1) validating Kim’s (2007) simulation method by applying analytic methods and (2) comparing the two different Robust Parameter Design methods with three measures of performance (label accuracy for enemy, friendly, and clutter). Considering the features of CID, input variables were defined as two controllable (threshold combination of detector and classifier) and three uncontrollable (map size, number of enemies and friendly). The first set of experiments considers Kim’s method using analytical methods. In order to create response variables, Kim’s method uses Monte Carlo simulation. The output results showed no difference between simulation and the analytic …

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Numerical Analysis For Relevant Features In Intrusion Detection (Narfid), Jose Andres Gonzalez Mar 2009

Numerical Analysis For Relevant Features In Intrusion Detection (Narfid), Jose Andres Gonzalez

Theses and Dissertations

Identification of cyber attacks and network services is a robust field of study in the machine learning community. Less effort has been focused on understanding the domain space of real network data in identifying important features for cyber attack and network service classification. Motivations for such work allow for anomaly detection systems with less requirements on data “sniffed” off the network, extraction of features from the traffic, reduced learning time of algorithms, and ideally increased classification performance of anomalous behavior. This thesis evaluates the usefulness of a good feature subset for the general classification task of identifying cyber attacks and …

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Voice Traffic Over Mobile Ad Hoc Networks: A Performance Analysis Of The Optimized Link State Routing Protocol, Lady Noreen P. Santos Mar 2009

Voice Traffic Over Mobile Ad Hoc Networks: A Performance Analysis Of The Optimized Link State Routing Protocol, Lady Noreen P. Santos

Theses and Dissertations

This thesis investigates the performance of the Optimized Link State Routing (OLSR) protocol on Voice over Internet Protocol (VoIP) applications in Mobile Ad hoc Networks (MANETs). Using VoIP over MANETs takes advantage of the mobility and versatility of a MANET environment and the flexibility and interoperability a digital voice format affords. Research shows that VoIP-like traffic can be routed through an ad hoc network using the Ad hoc On-demand Distance Vector routing protocol. This research determines the suitability of OLSR as a routing protocol for MANETs running VoIP applications. Representative VoIP traffic is submitted to a MANET and end-to-end delay …

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Dynamic Interactions For Network Visualization And Simulation, Cigdem Yetisti Mar 2009

Dynamic Interactions For Network Visualization And Simulation, Cigdem Yetisti

Theses and Dissertations

Most network visualization suites do not interact with a simulator, as it executes. Nor do they provide an effective user interface that includes multiple visualization functions. The subject of this research is to improve the network visualization presented in the previous research [5] adding these capabilities to the framework. The previous network visualization did not have the capability of altering specific visualization characteristics, especially when detailed observations needed to be made for a small part of a large network. Searching for a network event in this topology might cause large delays leading to lower quality user interface. In addition to …

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Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver Mar 2009

Using Predictive Rendering As A Vision-Aided Technique For Autonomous Aerial Refueling, Adam D. Weaver

Theses and Dissertations

This research effort seeks to characterize a vision-aided approach for an Unmanned Aerial System (UAS) to autonomously determine relative position to another aircraft in a formation, specifically to address the autonomous aerial refueling problem. A system consisting of a monocular digital camera coupled with inertial sensors onboard the UAS is analyzed for feasibility of using this vision-aided approach. A three-dimensional rendering of the tanker aircraft is used to generate predicted images of the tanker as seen by the receiver aircraft. A rigorous error model is developed to model the relative dynamics between an INS-equipped receiver and the tanker aircraft. A …

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Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan Mar 2009

Tools For The Conceptual Design And Engineering Analysis Of Micro Air Vehicles, Mustafa Turan

Theses and Dissertations

Micro Air Vehicles (MAV) are a subset of Unmanned Aircraft (UAS) that are up to two orders of magnitude smaller than manned systems. Near-Earth environments, such as forests, caves, tunnels and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Therefore, MAVs are considered ideal for these types of missions. However, the data using full size aircraft is inadequate to characterize miniature aircraft parameters due to the lower Reynolds numbers and low aspect ratio (LAR) wings and impact of wing-propeller interactions. The main objectives of this research were to: collect and synthesize the available data/tools; create …

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Optimized Robust Adaptive Networks In Supervisory Control And Data Acquisition Systems, Luis A. Oquendo Class Mar 2009

Optimized Robust Adaptive Networks In Supervisory Control And Data Acquisition Systems, Luis A. Oquendo Class

Theses and Dissertations

This thesis investigates the application of a Exponential Weighted Moving Average (EWMA) to be used as a memory buffer in conjunction with Special Protection Schemes (SPS) using the Electric Power and Communication Synchronizing Simulator (EPOCHS). It is proposed that using an SPS incorporating EWMA can compensate for the network layer lack of guarantee of packet delivery and provide for the stability and integrity of the power grid under a catastrophic event. The performance of the proposed SPS is evaluated using a discrete event computer simulation developed using the NS2 network simulator and the Power System Simulator for Engineering (PSS/E) power …

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Stochastic Estimation And Control Of Queues Within A Computer Network, Mingook Kim Mar 2009

Stochastic Estimation And Control Of Queues Within A Computer Network, Mingook Kim

Theses and Dissertations

Captain Nathan C. Stuckey implemented the idea of the stochastic estimation and control for network in OPNET simulator. He used extended Kalman filter to estimate packet size and packet arrival rate of network queue to regulate queue size. To validate stochastic theory, network estimator and controller is designed by OPNET model. These models validated the transient queue behavior in OPNET and work of Kalman filter by predicting the queue size and arrival rate. However, it was not enough to verify a theory by experiment. So, it needed to validate the stochastic control theory with other tools to get high validity. …

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A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston Mar 2009

A Feasibility Study Of A Persistent Monitoring System For The Flight Deck Of U.S. Navy Aircraft Carriers, Jeffrey S. Johnston

Theses and Dissertations

This research analyzes the use of modern Real Time Locating Systems (RTLS), such as the Global Positioning System (GPS), to improve the safety of aircraft, equipment, and personnel onboard a United States Navy (USN) aircraft carrier. The results of a detailed analysis of USN safety records since 1980 show that mishaps which could potentially be prevented by a persistent monitoring system result in the death of a sailor nearly every other year and account for at least $92,486,469, or 5.55% of the total cost of all flight deck and hangar bay related mishaps. A system to continually monitor flight deck …

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The Evaluation Of Rekeying Protocols Within The Hubenko Architecture As Applied To Wireless Sensor Networks, Cory J. Antosh Mar 2009

The Evaluation Of Rekeying Protocols Within The Hubenko Architecture As Applied To Wireless Sensor Networks, Cory J. Antosh

Theses and Dissertations

This thesis investigates the impact of using three different rekeying protocols–pair-wise, hierarchical, and Secure Lock within a wireless sensor network (WSN) under the Hubenko architecture. Using a Matlab computer simulation, the impact of the three rekeying protocols on the number of bits transmitted across the network and the amount of battery power consumed in WSN nodes during rekey operations is investigated. Baseline pair-wise rekeying performance can be improved by using either Secure Lock or hierarchical rekeying. The best choice depends on the size of the WSN and the size of the key used. Hierarchical rekeying is the best choice for …

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Enhancing The Ns-2 Network Simulator For Near Real-Time Control Feedback And Distributed Simulation Breaks, John S. Weir Mar 2009

Enhancing The Ns-2 Network Simulator For Near Real-Time Control Feedback And Distributed Simulation Breaks, John S. Weir

Theses and Dissertations

A network simulator coupled with a visualization package enables the human visual system to analyze the results of network modeling as a supplement to analytical data analysis. This research takes the next step in network simulator and visualization suite interaction. A mediator (or run-time infrastructure (RTI) in the literature) provides researchers the potential to interact with a simulation as it executes. Utilizing TCP/IP sockets, the mediator has the capability to connect multiple visualization packages to a single simulation. This new tool allows researchers to change simulation parameters on the y without restarting the network simulation.

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Utilizing Microelectromechanical Systems (Mems) Micro-Shutter Designs For Adaptive Coded Aperture Imaging (Acai) Technologies, Mary M. Ledet Mar 2009

Utilizing Microelectromechanical Systems (Mems) Micro-Shutter Designs For Adaptive Coded Aperture Imaging (Acai) Technologies, Mary M. Ledet

Theses and Dissertations

The Air Force has long relied on surveillance for intelligence and strategic purposes. Most surveillance systems rely on a lensing system to acquire their images, most of which are in either the visible or infrared wavelengths. Because lensing systems can be expensive, obtrusive, or hard to maintain, researchers have designed adaptive coded aperture imaging (ACAI) as a replacement system. Coded aperture imaging (CAI) has been used in both the astronomical and medical communities for years due to its ability to image light at short wavelengths and thus replacing conventional lenses. Where CAI is limited, researchers have discovered that adaptive coded …

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An Analysis Of Construction Contractor Performance Evaluation System, Rebecca S. Brown Mar 2009

An Analysis Of Construction Contractor Performance Evaluation System, Rebecca S. Brown

Theses and Dissertations

A rigorous system for rating construction contractor performance does not exist for the USAF as identified by the Air Force Civil Engineer (USAF CE), Major General Del Eulberg (Eulberg, 2007). The United States Army Corp of Engineers (USACE) uses DD Form 2626 for contractor performance evaluation and contractor selection. The objective of this research is to strengthen the USAF contractor rating system by exploring USACE‘s use of DD Form 2626. Using data from DD Form 2626, statistical analysis was conducted to determine if the measured performance sub-items reflect their respective performance elements, whether the resulting performance elements relate to the …

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Evaluation Of Performance Of A Maximum Likelihood Estimator For Tracking Purposes In The Presence Of Speckle Noise, Adrian Brett Monz Mar 2009

Evaluation Of Performance Of A Maximum Likelihood Estimator For Tracking Purposes In The Presence Of Speckle Noise, Adrian Brett Monz

Theses and Dissertations

In many cases, optical tracking systems do not have cooperative beacons avail- able. This is particularly true for the case involving tracking a laser illuminated target such as a missile seeker head, where the object of interest is an extended source. Furthermore the extended source is often observed in the presence of noise such as shot and speckle noise as well as atmospheric turbulence which further degrades the signal. This research effort presents the evaluation of an existing algorithm based on the maximum-likelihood technique for tilt estimation in the presence of extended sources and speckle noise, with particular application to …

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Modernizing A Preventive Maintenance Strategy For Facility And Infrastructure Maintenance, Ross E. Dotzlaf Mar 2009

Modernizing A Preventive Maintenance Strategy For Facility And Infrastructure Maintenance, Ross E. Dotzlaf

Theses and Dissertations

Preventive maintenance (PM) is defined as regularly scheduled maintenance actions based on average failure rates. A properly implemented PM strategy can provide many benefits to an organization in terms of extending equipment life, optimizing resource expenditures, and balancing work schedules. Periodic evaluation of a PM strategy can help identify ways to improve efficiencies and maximize effectiveness. This research effort was accomplished by performing a case study of the United States Air Force’s infrastructure and facility PM program known as the Recurring Work Program (RWP). The methodology consisted of two phases. The first phase, intended to develop an understanding of the …

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Ohio River Denial As A Transportation Corridor And Its Economic Impacts On The Energy Industry, Caglar Utku Guler Mar 2009

Ohio River Denial As A Transportation Corridor And Its Economic Impacts On The Energy Industry, Caglar Utku Guler

Theses and Dissertations

What if the Ohio River is disrupted or denied partially or completely as a transportation corridor? A disruption may be either a natural or man-made disaster or a planned outage on the river’s lock and dam structures. Recent history is full of water transport disruption events having significant economic effects on the waterside industries. To assess coal-based economic impacts, we developed a network flow model to represent waterside coal-fired power plants situated along the Ohio River, their respective coal supplying mines, and the various transportation modes that connect them. We show that significant transportation-centric insights can be derived by using …

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Power Generation By Harvesting Ambient Energy With A Micro-Electromagnetic Generator, James H. Shields Feb 2009

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. …

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A Mems Multi-Cantilever Variable Capacitor On Metamaterial, Luke A. Rederus Feb 2009

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 …

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