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Evaluation Of The Thorax Of Manduca Sexta For Flapping Wing Micro Air Vehicle Applications, Brian C. Cranston
Evaluation Of The Thorax Of Manduca Sexta For Flapping Wing Micro Air Vehicle Applications, Brian C. Cranston
Theses and Dissertations
The tobacco hornworm hawkmoth (Manduca sexta) provides an excellent model from which to gather knowledge pertaining to the development of a Flapping Wing Micro Air Vehicle (FWMAV). One of the major challenges in design of a FWMAV is the energy demanding nature of low Reynolds number flapping flight. Therefore, an understanding of the power required by the flight muscles to actuate the wings is essential for the design of a FWMAV. The M.sexta wing/thorax mechanism was evaluated as a mechanical system in order to gain insight to the mechanical power required to produce the full natural wing stroke. A unique …
Application Of Finite Element To Evaluate Material With Small Modulus Of Elasticity, Boyce H. Dauby
Application Of Finite Element To Evaluate Material With Small Modulus Of Elasticity, Boyce H. Dauby
Theses and Dissertations
This thesis describes the development of a series of models utilizing the commercial finite element suite ABAQUS specifically to apply towards the study of biological tissue. The end goal is to be able to obtain the material properties of the Manducca Sexta, a biological inspiration for flapping wing micro-air vehicles. Two finite element models were used to analyze the results of two prior studies of other researchers. A flat punch elastic model examined boundary effects and confirmed that the point of indentation was far enough removed from the boundary. The hyperelastic spherical indentation experiment examined the effects of coefficient of …
Computational Simulation Of Explosively Generated Pulsed Power Devices, Mollie C. Drumm
Computational Simulation Of Explosively Generated Pulsed Power Devices, Mollie C. Drumm
Theses and Dissertations
Technology and size constraints have limited the development of the end game mechanisms of today's modern military weapons. A smaller, more efficient means of powering these devices is needed, and explosive pulsed power devices could be that answer. While most prior research has been in the experimental field, there is a need for more theory-based research and a computer modeling capability. The objective of this research was to use experimental data collected by the US Army at Redstone Arsenal from their ferroelectric generator (FEG) design in combination with the ALEGRA-EMMA code to develop a computer model that can accurately represent …
Dynamic Constellation Tasking And Management, Steven P. Ingraham
Dynamic Constellation Tasking And Management, Steven P. Ingraham
Theses and Dissertations
Responsive orbits have gained much attention in recent years and many AFIT theses have addressed this topic. Specifically, the following topics have been studied: phasing within an orbit, adjusting time of arrival, avoidance, and maneuver detection. This thesis seeks to determine the feasibility of maneuvering satellites from circular (600 km) orbits to eccentric (600 km by 175 km) orbits in order to collect high resolution images for Earth surveillance. Coverage is calculated for multiple 6-satellite constellations. Perturbations for the subject orbits are analyzed and compared to simulation results.
A Study Of The Thermal Environment Developed By A Traveling Slipper At High Velocity, Kathleen H. Le
A Study Of The Thermal Environment Developed By A Traveling Slipper At High Velocity, Kathleen H. Le
Theses and Dissertations
The research presented in this thesis is developed from the relative sliding motion of a traveling slipper and stationary rail at the Holloman High Speed Test Track located at Holloman AFB, NM. The high velocity condition of the slipper traveling down the rail creates a thermal environment that is of interest to the researchers at the Air Force Institute of Technology. The high temperatures coupled with high velocity leads to a non-linear problem known as melt wear. The goal of this research is to characterize the amount of heat flow going into the slipper as it traverses the rail and …
Laser Illuminated Imaging: Multiframe Beam Tilt Tracking And Deconvolution Algorithm, David J. Becker
Laser Illuminated Imaging: Multiframe Beam Tilt Tracking And Deconvolution Algorithm, David J. Becker
Theses and Dissertations
A laser-illuminated imaging system operating in the presence of atmospheric turbulence will encounter several sources of noise and diffraction induced errors. As the beam propagates, turbulence induced tilt will cause the beam to wander off axis from the target. This is especially troublesome when imaging satellites, since most turbulence is closer to the Earth's surface and greatly affects the beam in the early stages of propagation. Additionally, the returning beam convolved with the target will encounter turbulence induced tilt that appears as apparent movement of the target between image frames. This results in varying beam intensities at the target surface …
Automatic Modulation Classification Of Common Communication And Pulse Compression Radar Waveforms Using Cyclic Features, John A . Hadjis
Automatic Modulation Classification Of Common Communication And Pulse Compression Radar Waveforms Using Cyclic Features, John A . Hadjis
Theses and Dissertations
This research develops a feature-based MAP classification system and applies it to classify several common pulse compression radar and communication modulations. All signal parameters are treated as unknown to the classifier system except SNR and the signal carrier frequency. The features are derived from estimated duty cycle, cyclic spectral correlation, and cyclic cumulants. The modulations considered in this research are BPSK, QPSK, 16-QAM, 64-QAM, 8-PSK, and 16-PSK communication modulations, as well as Barker coded, Barker coded, Barker coded, Frank coded, Px49 coded, and LFM pulse compression modulations. Simulations show that average correct signal modulation type classification %C 90% is achieved …
Mobile Network Defense Interface For Cyber Defense And Situational Awareness, James C. Hannan
Mobile Network Defense Interface For Cyber Defense And Situational Awareness, James C. Hannan
Theses and Dissertations
Today's computer networks are under constant attack. In order to deal with this constant threat, network administrators rely on intrusion detection and prevention services (IDS) (IPS). Most IDS and IPS implement static rule sets to automatically alert administrators and resolve intrusions. Network administrators face a difficult challenge, identifying attacks against a vast number of benign network transactions. Also after a threat is identified making even the smallest policy change to the security software potentially has far-reaching and unanticipated consequences. Finally, because the administrator is primarily responding to alerts they may lose situational awareness of the network. During this research a …
Improving Bandwidth Utilization In A 1 Tbps Airborne Mimo Communications Downlink, Jonathan D. Hill
Improving Bandwidth Utilization In A 1 Tbps Airborne Mimo Communications Downlink, Jonathan D. Hill
Theses and Dissertations
FEC techniques are compared for different MIMO configurations of a high altitude, extremely wide bandwidth radio frequency downlink. Monte Carlo simulations are completed in MATLAB® with the aim of isolating the impacts of turbo codes and LDPC codes on system throughput and error performance. The system is modeled as a transmit-only static array at an altitude of 60,000 feet, with no interferers in the channel. Transmissions are received by a static receiver array. Simulations attempt to determine what modulation types should be considered for practical implementation, and what FEC codes enable these modulation schemes. The antenna configurations used in this …
Information Encoding On A Pseudo Random Noise Radar Waveform, Joshua A . Hardin
Information Encoding On A Pseudo Random Noise Radar Waveform, Joshua A . Hardin
Theses and Dissertations
Navigation requires knowledge of current location and a planned destination. This is true with manned vehicles and unmanned vehicles. There are many ways to acquire the current location, including global positioning system (GPS), triangulation, radar, and dead reckoning. Today GPS is the most reliable and accurate navigation technique when there is a clear, unobstructed view of the satellite constellation. Various sensors can be used to perform indoor navigation; however, when the vehicle is autonomous the sensors need to provide the exact location to the system. This research determined if using a template replay strategy has the same RNR performance as …
A Study Of Dim Object Detection For The Space Surveillance Telescope, Stephen D. Maksim
A Study Of Dim Object Detection For The Space Surveillance Telescope, Stephen D. Maksim
Theses and Dissertations
Current methods of dim object detection for space surveillance make use of a Gaussian log-likelihood-ratio-test-based detector that only considers the probability that a single point in an image resulted from the propagation of a point source through space. This paper proposes the application of a correlating Gaussian log-likelihood-ratio-test-based detector, which makes use of all the pixels in the window, to the arena of dim object detection. The requirements for comparing these detectors using the same threshold of detection are established. The performance of the detectors is compared using images taken by the Space Surveillance Telescope in New Mexico of a …
Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam
Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam
Theses and Dissertations
For conventional imaging systems, GEO space objects cannot be resolved due to their 40 Mm distance. There exists a strong need to obtain high resolution images of GEO objects and to accomplish this task, investigation into the suitability of ISAL is currently underway. A critical component in determining this suitability is to accurately model the atmospheric impacts on LADAR pulses. Conventional knowledge says that while the atmosphere churns, wind is the predominant cause of temporal evolution which simplifies all modeling and simulation into the frozen flow hypothesis. The concern is that the frozen flow hypothesis based phase screen generation techniques …
Inertial Navigation System Aiding Using Vision, James O. Quarmyne
Inertial Navigation System Aiding Using Vision, James O. Quarmyne
Theses and Dissertations
The aiding of an INS using measurements over time of the line of sight of ground features as they come into view of an onboard camera is investigated. The objective is to quantify the reduction in the navigation states' errors by using bearings-only measurements over time of terrain features in the aircraft's field of view. INS aiding is achieved through the use of a Kalman Filter. The design of the Kalman Filter is presented and it is shown that during a long range, wings level cruising flight at constant velocity and altitude, a 90% reduction in the aided INS-calculated navigation …
Modeling Cyber Situational Awareness Through Data Fusion, Evan L. Raulerson
Modeling Cyber Situational Awareness Through Data Fusion, Evan L. Raulerson
Theses and Dissertations
Cyber attacks are compromising networks faster than administrators can respond. Network defenders are unable to become oriented with these attacks, determine the potential impacts, and assess the damages in a timely manner. Since the observations of network sensors are normally disjointed, analysis of the data is overwhelming and time is not spent efficiently. Automation in defending cyber networks requires a level of reasoning for adequate response. Current automated systems are mostly limited to scripted responses. Better defense tools are required. This research develops a framework that aggregates data from heterogeneous network sensors. The collected data is correlated into a single …
A Multi Agent System For Flow-Based Intrusion Detection, David A . Ryan
A Multi Agent System For Flow-Based Intrusion Detection, David A . Ryan
Theses and Dissertations
The detection and elimination of threats to cyber security is essential for system functionality, protection of valuable information, and preventing costly destruction of assets. This thesis presents a Mobile Multi-Agent Flow-Based IDS called MFIREv3 that provides network anomaly detection of intrusions and automated defense. This version of the MFIRE system includes the development and testing of a Multi-Objective Evolutionary Algorithm (MOEA) for feature selection that provides agents with the optimal set of features for classifying the state of the network. Feature selection provides separable data points for the selected attacks: Worm, Distributed Denial of Service, Man-in-the-Middle, Scan, and Trojan. This …
Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer
Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer
Theses and Dissertations
A new method for characterization of unknown targets using passive multispectral polarimetric imagery is presented. Previous work makes use of a pBRDF derived equation for the degree of linear polarization and with the aid of measurements at multiple incident angles estimates refractive index and reflection angle. This work uses known incident and reflection angles along with dispersion equations and polarimetric data at multiple wavelengths to recover the index of refraction. Although imagery is collected with a division of time polarimeter and a spectral filter wheel in iterative, manual steps, the new algorithm could be applied to any set of registered …
Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler
Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler
Theses and Dissertations
Engineers have attempted to improve reliability and lifecycle performance using novel micro-contact metals, unique mechanical designs and packaging. Contact resistance can evolve over the lifetime of the micro-switch by increasing until failure. This work shows the fabrication of micro-contact support structures and test fixture which allow for micro-contact testing, with an emphasis on the fixture's design to allow the determination and analysis of the appropriate failure mode. The other effort of this investigation is the development of a micro-contact test fixture which can measure contact force and resistance directly and perform initial micro-contact characterization, and two forms of lifecycle testing …
Adaptations And Analysis Of The Afit Noise Radar Network For Indoor Navigation, Russell D. Wilson Iv
Adaptations And Analysis Of The Afit Noise Radar Network For Indoor Navigation, Russell D. Wilson Iv
Theses and Dissertations
After several years of development, the AFIT Noise Radar Network (NoNET) has proven to be an extremely versatile system for many standard radar functions. This pallet of capabilities includes through the wall target tracking capabilities due to its wide bandwidth and UHF operations. Utilizing White Gaussian Noise as its waveform, the NoNET can operate at much lower power levels than other comparable systems while remaining extremely covert. In an effort to explore new applications, the question arose could the NoNET provide a viable option for navigation capability in GPS denied and indoor environments? This research aims to provide proof of …
Network Intrusion Dataset Assessment, David J. Weller-Fahy
Network Intrusion Dataset Assessment, David J. Weller-Fahy
Theses and Dissertations
Research into classification using Anomaly Detection (AD) within the field of Network Intrusion Detection (NID), or Network Intrusion Anomaly Detection (NIAD), is common, but operational use of the classifiers discovered by research is not. One reason for the lack of operational use is most published testing of AD methods uses artificial datasets: making it difficult to determine how well published results apply to other datasets and the networks they represent. This research develops a method to predict the accuracy of an AD-based classifier when applied to a new dataset, based on the difference between an already classified dataset and the …
Electronic Characteristics Of Rare Earth Doped Gan Schottky Diodes, Aaron B. Blanning
Electronic Characteristics Of Rare Earth Doped Gan Schottky Diodes, Aaron B. Blanning
Theses and Dissertations
The Schottky barrier height (SBH) was measured on GaN based diodes with three different dopant types; Gd, Er and Yb. Two methods were used to determine the SBH. The first method was the Juergen Werner method to evaluate the I-V characteristics. The calculated SBH of the diodes using this method was 1.41 ± 0.20eV, 1.71 ± 0.25eV and 1.75 ± 0.28eV for the Gd-, Er- and Yb-doped diodes respectively. It was observed that using an ad-hoc effective Richardson constant value of 0.006Axcm-2xK-2 to calculate the SBH rendered results that were in no greater than 2% disagreement (neglecting …
Crystal Growth And Characterization Of Tho2 And UXTh1-XO2, Jacob G. Castilow
Crystal Growth And Characterization Of Tho2 And UXTh1-XO2, Jacob G. Castilow
Theses and Dissertations
Hydrothermal synthesis of ThO2 and UxTh1-xO2, and UOx at temperatures between 670°C and 700°C has been demonstrated. Synthesis at these temperatures is 50-80°C below prior crystal growths and represents a new lower bound of successful growth. Hydrothermal synthesis represents a cost effective, environmentally friendly way of growing bulk actinide materials of optical quality. These refractory oxide single crystals offer potential applications in thorium nuclear fuel technology, wide-band-gap uranium-based direct-conversion solid state neutron detectors, and understanding how actinide fuels age with time. ThO2 single crystals of dimensions 6.49mm x 4.89mm x 3.89 …
Three Dimensional Positron Annihilation Momentum Spectroscopy Of Lithium Tetraborate Crystals, Stefan B. Fagan-Kelly
Three Dimensional Positron Annihilation Momentum Spectroscopy Of Lithium Tetraborate Crystals, Stefan B. Fagan-Kelly
Theses and Dissertations
Previous endeavors in positron annihilation spectroscopy (PAS) at AFIT have resulted in the design and characterization of a second-generation three-dimensional positron annihilation momentum spectroscopy system (3DPAMSS) which combines two-dimensional angular correlation of annihilation radiation (2D ACAR) and coincident Doppler broadening of annihilation radiation (CDBAR) in order to measure electron momentum distributions in samples and thus characterize material defects. The focus of this particular research is to nondestructively measure negative defects in the crystal lattice of copper-doped, silver-doped, and undoped lithium tetraborate by 3DPAMSS spectroscopy using a Na-22 source and two high-purity germanium (HPGe) position-resolvable strip detectors. Lithium tetraborate is a …
Neutron Spectroscopy Using Lif Thin-Film Detectors, Michael A. Ford
Neutron Spectroscopy Using Lif Thin-Film Detectors, Michael A. Ford
Theses and Dissertations
A stacked array of segmented micro-structured semiconductor neutron detectors (MSNDs) has been fabricated to perform as a neutron spectrometer simultaneously capable of differentiating fast and thermal neutrons. The MSND devices consist of thin-film perforated diodes constructed from LiF powder back-filled into an etched silicon wafer. Geant4 simulations demonstrate than an eight-layer spectrometer consisting of alternating layers of MSND and hydrogenous moderator can successfully resolve neutron energies at a resolution dependent upon the number of layers and the thickness of the adjacent moderating materials. The simulated spectrometer response was compared to that obtained experimentally with mono-energetic neutrons from a D+D neutron …
Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey
Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey
Theses and Dissertations
Thermospheric density impacts satellite position and lifetime through atmospheric drag. More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model (HASDM), can decrease model density errors. Building on Burke et al. s driven-dissipative model (2009) the arithmetic mean temperature, T1/2 , defined by Jacchia, 1977 (J77), is modeled using the magnetospheric electric field as a driver. Three methods of treating the UV contribution to T1/2 (T1/2UV) are tested. Two model parameters, the coupling and relaxation constants, are adjusted for 38 storms from 2002 - 2008 to …
Depth-Resolved Cathodoluminescence Of Tho2, Michael G. Lee
Depth-Resolved Cathodoluminescence Of Tho2, Michael G. Lee
Theses and Dissertations
Single crystal thorium dioxide (ThO2) samples were hydrothermally grown and studied using depth-resolved cathodoluminescence (CL) to characterize the surface and bulk electronic states. X-ray diffraction (XRD) measurements were collected to confirm that these crystals were ThO2 in the fluorite structure. Understanding the chemical and structural quality of ThO2 will aid in the fabrication of better neutron detectors as well as in the power production with thorium breeder reactors. Monte Carlo simulations predicted the expected energy-dependent electron interaction depths in the ThO2 crystals. CL was conducted with electron energy range of 1.5 - 12 keV, a …
Mirrorless Lasing In Optically Pumped Rubidium Vapor, Ryan M. Richards
Mirrorless Lasing In Optically Pumped Rubidium Vapor, Ryan M. Richards
Theses and Dissertations
Mirrorless lasing has been successfully demonstrated in a Rubidium heat pipe. Lasing was observed on the 62P3/2-62S1/2 energy transition at 2.73 µm and on the 62P1/2-62S1/2 transition at 2.79 µm. The transitions were optically pumped from 52S1/2-62P3/2 at 420.2 nm and from 52S1/2-62P1/2 at 421.7 nm, respectively. The 52S1/2-62P3/2 transition was excited over a 36 GHz band, while the 52S1/2-62 …
Neutron Shielding Effectiveness Of Multifunctional Composite Materials, Anthony D. Marchand
Neutron Shielding Effectiveness Of Multifunctional Composite Materials, Anthony D. Marchand
Theses and Dissertations
Composite materials offer a greater degree of flexibility in design and engineering of specialized space vehicle shielding applications compared to aluminum. A new design for shielding materials has been developed by including specific neutron absorbers and conductive materials into the composite structure. In this research, the neutron shielding capability of two types of custom-designed nanocomposite materials are compared to that of T6061 aluminum.
Optimization Of Coronal Mass Ejection Ensemble Forecasting Using Wsa-Enlil With Coned Model, Jack A . Shepherd Iii
Optimization Of Coronal Mass Ejection Ensemble Forecasting Using Wsa-Enlil With Coned Model, Jack A . Shepherd Iii
Theses and Dissertations
The combination of the Wang-Sheeley-Arge (WSA) coronal model, ENLIL version 2.7, and the Coned model version 1.4 was utilized to form ensemble forecast for 21 coronal mass ejections (CMEs). The Coned model was improved by adding a weight for the associated flare location to push the propagation axis towards the flare location and an additional image was used. Fifteen CMEs were used from previous research using the Coned model version 1.3 and the results were compared to determine the improvement. The model was used again with six additional CMEs and compared to the old Coned model version 1.3 to verify …
Changes To Tensile Strength And Electromagnetic Shielding Effectiveness In Neutron Irradiated Carbon Nanocomposites, James F. Shinn
Changes To Tensile Strength And Electromagnetic Shielding Effectiveness In Neutron Irradiated Carbon Nanocomposites, James F. Shinn
Theses and Dissertations
Electromagnetic interference shielding effectiveness (EMI-SE) and tensile strength of nanocomposites containing multi-walled carbon nanotubes (MWNTs) are investigated following neutron irradiation. This nanocomposite material consists of two plies of MWNTs in an epoxy resin, and 4 plies of an E-glass substrate. EMI-SE measurements over the X-band frequency spectrum and monotonic tension tests to determine Young’s Modulus were performed before and after irradiation on the nanocomposite material. The nanocomposite and the MWNT plies were irradiated to a total fluence of 1.4 × 1014 1 MeV (Si-eq) n/cm2. The nanocomposites showed an average increase of 8 dB in shielding effectiveness …
Solving Point-Reactor Kinetics Equations Using Exponential Moment Methods, Paul M. Thelen
Solving Point-Reactor Kinetics Equations Using Exponential Moment Methods, Paul M. Thelen
Theses and Dissertations
A robust method of solving the reactor point kinetic equations was designed using exponential moment methods. Although the method requires a relatively large number of calculations to complete, the accuracy ensured by each individual step calculation allows larger time steps to be used. The algorithm designed was verified to converge to the correct value as step size was reduced. Additionally, the algorithm can take steps much larger than the average neutron lifetime while maintaining some precision. An error control scheme was designed based on changes observed in the results as a function of time step size. The error control adaptively …