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Determination Of The Optical Properties Of Organic Thin Films By Spectroscopic Ellipsometry, Mark L. Sward
Determination Of The Optical Properties Of Organic Thin Films By Spectroscopic Ellipsometry, Mark L. Sward
Theses and Dissertations
This thesis demonstrated the feasibility of determining the optical properties of organic and polymer thin films through the use of Spectroscopic Ellipsometry (SE). Tan Psi and cos Delta data from 300-800 nanometers (NM) were taken with a Rudolph Research s2000 spectroscopic ellipsometer four samples: indium tin oxide (ITO) coated glass; five layer poly-benzyl-L glutamate (PBLG) organic film on ITO coated glass; eight layer PBLG film on ITO coated glass; and a thiophene polymer film on a microscope slide. The data sets were fit to a choice of four computer models based on a paper written by Dwight Berreman in 1972. …
An Aluminum Salvage Station For The External Tank (Asset), James N. Haislip Jr., William C. Raynes Jr., David L. Van Matte, Roger E. Linscott, Michael A. Skinner
An Aluminum Salvage Station For The External Tank (Asset), James N. Haislip Jr., William C. Raynes Jr., David L. Van Matte, Roger E. Linscott, Michael A. Skinner
Theses and Dissertations
The external tank is currently the only non-reusable portion of the National Space Transportation System. The tank has 98% of the energy required to be placed in orbit at the point it is jettisoned. The purpose of this study is to develop techniques which would transform this throw-away item into a source of construction material at low earth orbit. A simulation is developed to verify the reduction timelines and peak power requirements for manual and automated reduction. The required tools to accomplish the tasks of initial cutting, product transport, spray on foam insulation removal, and product storage are developed. A …
Multidisciplinary Modeling And Design Of A Space Structure, Brian K. Cassiday, Lawrence L. Gatchet, John T. Tester, Stephen O. Gaines Ii, Mario N. Moya
Multidisciplinary Modeling And Design Of A Space Structure, Brian K. Cassiday, Lawrence L. Gatchet, John T. Tester, Stephen O. Gaines Ii, Mario N. Moya
Theses and Dissertations
A method is needed to simultaneously integrate several engineering disciplines into one complete model to determine the performance of the system as a whole during the design development. System engineering methodologies are particularly suited to this problem. These methods provide a structured approach to problem formulation and system parameter identification. Bond graphs are also well suited as bond graphs model power flow and energy relationships within subsystems, a characteristic inherent to all dynamic systems. The intent of this research was to demonstrate the use of concurrent engineering theory to systematically model a large flexible space structure involving several engineering disciplines. …
A Procedure For Performance Assessment Of Drugs Hypothesized To Be Effective In Controlling Motion Sickness, Zainab N. Ahmed
A Procedure For Performance Assessment Of Drugs Hypothesized To Be Effective In Controlling Motion Sickness, Zainab N. Ahmed
Theses and Dissertations
The Air Force Institute of Technology (AFIT) is conducting research into the effectiveness of certain drugs for controlling motion sickness. If the drugs are found to be useful, they must still be proven to have no harmful effects on the operator's performance abilities. There are many methods for assessing performance effects of drugs but very little standardization exists. The Unified Tri-Services Cognitive Performance Assessment Battery (UTC-PAB) is a performance assessment method designed to be used by all military branches. This will encourage standardization of drug testing, exchange of data, and comparability of methods. Five tests were chosen from the UTC-PAB …
Model-Based Reasoning In The Detection Of Satellite Anomalies, Ralph W. Dries
Model-Based Reasoning In The Detection Of Satellite Anomalies, Ralph W. Dries
Theses and Dissertations
Automatic fault detection and recovery would be a mandatory requirement for a satellite where some degree of autonomy is required. This thesis reviews some AI techniques used for the detection of satellite anomalies, and concludes that the model-based reasoning paradigm is best suited for automated on-board fault detection because it can cope with situations not necessarily programmed into the knowledge base. Using the Scheme language and its SCOOPS object oriented extension, development of software is described that models the pitch control channel in the attitude and velocity control subsystem of a typical geo-stationary communications satellite. This model is used by …
A Computer Model Of A Co2 Oscillator-Amplifier System, William F. Anderson
A Computer Model Of A Co2 Oscillator-Amplifier System, William F. Anderson
Theses and Dissertations
An existing CO2 laser amplifier simulation model developed for use on IBM-compatible personal computers has been improved through the redesign and addition of supplemental procedures from several models. The models and selected procedures which form the basis of the improved model are described. One procedure calculates the pumping rates of CO2 and N2 through calculation of the Boltzmann equation. Another procedure calculates the average vibrational temperatures of C2's vibrational modes. A third procedure replaces the Runge- Kutta integrator used in the original model with a faster, more accurate Adams- Bashforth-Moulton predictor-corrector integrator.
An Analysis Of The Effects Of Phenytoin In Treating Motion Sickness And The Effects Of Motion Sickness On The Human Electroencephalogram, Todd M. Banducci
An Analysis Of The Effects Of Phenytoin In Treating Motion Sickness And The Effects Of Motion Sickness On The Human Electroencephalogram, Todd M. Banducci
Theses and Dissertations
This research had two goals: to continue the ongoing research at AFIT to determine the efficacy of the anticonvulsant drug phenytoin in combating the onset and progression of motion sickness; and to note whether or not there is a discernable similarity in the brains of the test subjects to indicate a common point of origin (epicenter) and propagation pattern of the effects of motion sickness in the brain. Eight male DOD personnel were used as subjects to complete twelve trials. Four subjects completed the phenytoin verses placebo double-blind crossover experiment. These four subjects experienced a 99% mean increase in their …
Development Of An Image Registration Technique For Polar-Orbiting Satellites, Jerry L. Mehlberg
Development Of An Image Registration Technique For Polar-Orbiting Satellites, Jerry L. Mehlberg
Theses and Dissertations
In this thesis, a means to perform spatial registration (gridding) of meteorological satellite data is developed. It is applicable to Automatic Picture Transmission (APT) data from the TIROS-N series polar-orbiting satellites operated by the National Oceanic and Atmospheric Administration (NOAA). This technique does not require the use of ground control points. Registration is accomplished using an advanced orbital model to precisely compute the satellite's location based on NORAD two-line element sets and the time of the image. This technique is examined for accuracy and sensitivity to errors in the element set and satellite attitude control. This study involves over 70 …
Improving Reliability In A Stochastic Communication Network, William L. Gaught
Improving Reliability In A Stochastic Communication Network, William L. Gaught
Theses and Dissertations
This research investigated the behavior of increasing the reliability of components in stochastic communication networks. A stochastic communication network is one in which the components, links and nodes, are not 100 percent reliable. In addition the reliability value, each component also has a capacity value that limits the flow through the component. The throughput in a stochastic communication network can be improved by increasing the capacity or the reliability of the individual components. A set of linear and nonlinear models was developed to determine the best investment strategy for increasing the reliability of individual components. Once the models were developed, …
A Limited Antiballistic Missile System, Jay H. Payne
A Limited Antiballistic Missile System, Jay H. Payne
Theses and Dissertations
This investigation examines the possibilities of deploying a limited ABM system to counter launches from Third World regions. It is a systems analysis of the entire concept, with the objective of determining if the existing missile warning network could detect launches from Third World regions, and if an ABM component could be integrated into the network. A computer model was used to determine if launches would be detected, and examine the warning time provided. Based on sample data, the warning network appears capable of detecting Third World launches. Warning times provided by the network appears to provide adequate time to …
Debris Production In Hypervelocity Impact Asat Engagements, Stephen K. Remillard
Debris Production In Hypervelocity Impact Asat Engagements, Stephen K. Remillard
Theses and Dissertations
This study reviews laboratory experiments on hypervelocity impacts and applies the results from those experiments to predict the mass of debris produced, the number of particles, and the size distribution of the debris particles produced in an ASAT engagement using kinetic energy weapons. The three possible types of hypervelocity collisions are discussed and parameters are provided that will help predict what type of collisions will occur between a given projectile and a target satellite. Once the collision type is determined, various equations are supplied which can be used to calculate debris mass, etc. Next, a notional attack between a miniature …
Proposed Design Of A Tactical Reconnaissance Satellite System, John D. T. Severance
Proposed Design Of A Tactical Reconnaissance Satellite System, John D. T. Severance
Theses and Dissertations
Tactical reconnaissance is a much needed wartime asset, yet with the deactivation of all active-duty RF-4C squadrons world-wide there appears to be a gap in this country's war-fighting capability. This study proposes a system which utilizes a constellation of small tactical satellites and mobile ground receiving stations that can fulfill the tactical reconnaissance mission. A literature review gives background information on resolution variables, the RF-4C, space reconnaissance, and sensing technologies. After defining system requirements and constraints, a basic system concept is determined. Three alternative systems, separated mostly by threat scenario, technology, and cost, are evaluated using Athey's Systematic Systems Approach. …
Application Of Influence Diagrams In Identifying Soviet Satellite Missions, Cary C. Chun
Application Of Influence Diagrams In Identifying Soviet Satellite Missions, Cary C. Chun
Theses and Dissertations
This thesis investigates the feasibility of applying influence diagrams to capture expert knowledge and incorporate decision theory to construct a Soviet satellite mission prediction model. Before a Soviet launch occurs, formulations of the model's prior probability distribution allows the input of expert knowledge and any available information. As the predictive variables of the model become known, the information is used to successively refine the estimate of the probable mission, thereby, reducing the uncertainty in the model. Discretizing is used to approximate continuous variables as discrete variables which successfully allows the combination of both variable types in a single influence diagram …
A Comparison Of Human-Computer Interfaces In Air Force Organizations, Michael G. Morris
A Comparison Of Human-Computer Interfaces In Air Force Organizations, Michael G. Morris
Theses and Dissertations
This thesis investigated differences in organizational efficiency and effectiveness for users of graphical user interfaces and text-based interfaces on personal computers in Air Forces offices. Areas of interest included amount of time required to learn the basic system, amount of time required to learn new application, users' ratings of user-friendliness, users' perceptions of the extent that their system help them perform in their job, the number of software packages used on the job by users of each system, user satisfaction, responsible authorities' ratings of quality of output, and the relationship between user job experience level and interface used on the …
A Study Of The Air Force's Current Method Of Training Individuals To Use Contractor Developed Software In Information Management And The Perceived Effectiveness Of Training, Bruce F. Harmon
Theses and Dissertations
The purpose of this research was to determine if the Air Force's current method of training untrained individuals to use contractor developed automated information management software is producing the desired levels of productivity and the effectiveness of the training. The study found that greater emphasis must be placed on developing and supporting the use of a standardized training program for the managers and users of automated information management software. Due to the lack of quality training, the majority of survey respondents felt they could perform their jobs more efficiently and be more productive if they had some/more training. The study …
Investigating The Application Of The Theory Of Constraints To The Scheduling Environment Of The Iaf's Depots, Lewis S. Trigger
Investigating The Application Of The Theory Of Constraints To The Scheduling Environment Of The Iaf's Depots, Lewis S. Trigger
Theses and Dissertations
This research investigated the application and merits of the Theory of Constraints (TOC) to the scheduling environment of the Israeli Air Force's (IAF) maintenance depots. TOC was extensively reviewed including an elaboration of the TOC paradigm and the scheduling procedures developed for a commercial manufacturing setting. Background information was also presented on the IAF depots and traditional scheduling rules. An experiment was designed and conducted that simulated a simplified version of the process flow of the armaments depot. the simulation compared the terms of lower inventory and makespan. The experiment did not conclusively show any difference in standard throughput hours …
Nato Armaments Cooperation: The Case Of The European Fighter Aircraft, Carlos J. Sancho Gonzalez
Nato Armaments Cooperation: The Case Of The European Fighter Aircraft, Carlos J. Sancho Gonzalez
Theses and Dissertations
Difficulties faced by cooperative acquisition programs are identified as the inability to agree on common requirements and the existence of economic or political interests of the partner nations which conflict with or impinge on the program. These are the causes of failure of many of the past cooperative projects undertaken by NATO countries for the purpose of standardization. The study investigated the European Fighter Aircraft (EFA) program in order to find if the same holds true for the EFA and the impact that those difficulties had in the program. The EFA has been subject to the same problems. All the …
Development Of A Piezoelectric Polymer Film Pressure Transducer For Low Frequency And Dynamic Pressure Measurement, Ted H. Halley
Development Of A Piezoelectric Polymer Film Pressure Transducer For Low Frequency And Dynamic Pressure Measurement, Ted H. Halley
Theses and Dissertations
The purpose of this research was to investigate the characteristics of a small and inexpensive pressure transducer made from piezoelectric film. The pressure transducer was designed to be small and surface mountable so that the pressure distribution could be measured on an aerodynamic body. A charge reset technique was used to overcome the traditional limitations, low frequency measurements and charge decay, of a piezoelectric device.
H2 And H∞ Optimization With A Restricted Region Of Stability, Michael J. Mares
H2 And H∞ Optimization With A Restricted Region Of Stability, Michael J. Mares
Theses and Dissertations
Many modern control design methods, such as H2 and H∞ optimization, guarantee that the closed-loop system will be stable. To make further use of this guarantee, the portion of the s-plane considered to be stable is restricted to a region left of a vertical line some distance alpha from the imaginary axis. This alpha shift was accomplished in the state space equations, so standard computational tools still work. now the system is not only guaranteed to be stable, but also has some guaranteed speed for the time response. The equations for guaranteeing some arbitrary damping ratio were also …
Numerical Analysis Of An Axisymmetric Thrust Augmenting Ejector, Kenneth R. Gage
Numerical Analysis Of An Axisymmetric Thrust Augmenting Ejector, Kenneth R. Gage
Theses and Dissertations
Use of an ejector is an effective way to increase the thrust produced by a jet. In this thesis project an axisymmetric ejector concept which had been previously explored by experiment was numerically modeled. An existing axisymmetric, internal flow code based on the explicit MacCormack method was modified to incorporate primary nozzle structure and flow injection within the flowfield. Results were compared qualitatively and quantitatively with experimental results to verify the validity of the model. Internal flow structure, difficult to obtain in experiment, is easily examined. This code may be used for parametric analysis of such ejector performance parameters as …
Robustness Of H2 And H∞ Design Techniques In The Design Of A Guided Missile Controller, Steven R. Kolbow
Robustness Of H2 And H∞ Design Techniques In The Design Of A Guided Missile Controller, Steven R. Kolbow
Theses and Dissertations
This work follows Capt. R.L. Riddle's 1989 thesis (ADA216147) which compared conventional, H2 and H∞ controlled guided missiles in simulated flyouts against an airborne target. The simulation results did not clearly demonstrate the H2 and H∞ controller advantages. In this study the missile model and simulation were refined. In addition to simulation runs, performance, noise attenuation, and μ (structural singular value) robustness analyses were conducted. Results showed areas where improvement was needed in the H2 and H∞ controllers used in the study. An H2 and H∞ controller redesign is recommended using the …
An Experimental Study Of A Sting-Mounted Single-Slot Circulation Control Wing, Michael E. Pelletier
An Experimental Study Of A Sting-Mounted Single-Slot Circulation Control Wing, Michael E. Pelletier
Theses and Dissertations
This wind tunnel study investigated the feasibility of using a sting and force balance to measure the aerodynamic forces and moments on a circulation control wing. A 20% this, 8.5% camber, single blowing slot, rectangular wing was designed, built, and tested in the AFIT 5-ft wind tunnel. Lift and drag coefficients were referenced to the stability axis. The Reynolds number for all tests was 950,000; angle of attack was varied from -6 to +6 degrees. Trends in the data were similar to two dimensional data, with the exception of high drag coefficients with increased blowing. Results show it is feasible …
Modeling And Analysis Of Orthotropic Plate With Circular Cutout And Adhesive Bonded Patch, Mark W. Hunter
Modeling And Analysis Of Orthotropic Plate With Circular Cutout And Adhesive Bonded Patch, Mark W. Hunter
Theses and Dissertations
The purpose of this study was to investigate a modeling technique to simply and adequately model an adhesive bonded patch on an orthotropic plate. This report is limited to linear material behavior. This thesis is also the basis for further work into nonlinear material range and three-dimensional stress states. To further advance aerospace battle damage repair techniques for composite repairs, a finite element model of an orthotropic plate with a hole and patch was constructed to investigate the accuracy of such a model. The fundamental problem in this model is the development of a simple and accurate method of modeling …
Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox
Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox
Theses and Dissertations
Bifurcation analysis was used to investigate the nonlinear behavior of a simple powered lifting hypersonic vehicle in circular orbit about a spherical nonrotating Earth with gradients in atmospheric density and pressure and an inverse square law for gravity. Vehicle motion is constrained to a vertical plane so only longitudinal dynamics were modeled. Bifurcation analysis was conducted using the AUTO software package. A simple five-state model with three different thrust laws was derived to describe an unaugmented vehicle whose geometric and aerodynamic characteristics follow those of the literature. A parameter representing a body flap deflection was used to conduct one set …
Turbulence Scales In The Passage Of A Linear Turbine Cascade, James L. Acree
Turbulence Scales In The Passage Of A Linear Turbine Cascade, James L. Acree
Theses and Dissertations
Convective heat transfer in a turbine cascade is examined for turbulence effects. Turbulence in the free stream is varied by injection of air through a jet-grid device upstream of the cascade. Pressure and flow patterns on the blade surface, and flow velocity in two components, are examined to determine the effect of the jet-grid. Velocity and velocity fluctuation in two components are measured. Local turbulence scales through the cascade passage are determined, and local turbulent energy dissipation rate is determined. Results indicate injection of air through the jet-grid changes the angle of incidence, and therefore changes the surface pressures and …
A Linear Quadratic Regulator Weight Selection Algorithm For Robust Pole Assignment, Jeffrey D. Robinson
A Linear Quadratic Regulator Weight Selection Algorithm For Robust Pole Assignment, Jeffrey D. Robinson
Theses and Dissertations
An advantage of linear quadratic regulator (LQR) design is that it gives a robust system by guaranteeing stability margins. This property is used to develop an algorithm for placing robust poles. The algorithm chooses the positive semidefinite weighting matrix Q and positive definite weighting matrix R by attempting to place closed loop poles at a set of desired poles. If the desired poles lie outside the allowable LQR region, the algorithm finds the achievable poles inside the region that are closest to the desired poles. The solution requires using a gradient search technique to minimize a weighted eigenvalue difference cost …
Micromechanical Modeling Of The Fiber/Matrix Interface Region In A Metal Matrix Composite, David D. Robertson
Micromechanical Modeling Of The Fiber/Matrix Interface Region In A Metal Matrix Composite, David D. Robertson
Theses and Dissertations
In order to develop reasonable analytical models and to better understand how the integrity of the fiber/matrix interface in high temperature titanium based metal matrix composites effects the overall transverse normal characteristics, a parametric study of various fiber/matrix interface conditions was performed. Analysis methods included both a simplified one-dimensional mathematical model and a finite element analysis using MSC/NASTRAN. First, both strong and weak interfacial bonds were examined. Subsequently, to provide for partial bonding, a model that used an elastic-plastic interphases zone between the fiber and matrix was examined.
A Comparison Of Molecular Vibration Modeling For Thermal Nonequilibrium Airflow, Kenneth J. Moran
A Comparison Of Molecular Vibration Modeling For Thermal Nonequilibrium Airflow, Kenneth J. Moran
Theses and Dissertations
The effects of thermal nonequilibrium on flows about blunt-bodies have not been studied numerically in isolation from chemical reactions. Typically, air is modeled as a perfect gas or as a chemically reacting mixture. In the former case, significant errors result at Mach numbers exceeding about 5. However, below Mach numbers around 8, the effects of chemical reactions are negligible. This study analyzes flow about a simple axisymmetric blunt-body at moderate hypersonic speeds (Mach numbers between 5-8). A first-order-accurate Roe scheme was used to compute solutions of the Euler equations assuming different gas models: perfect gas, thermal equilibrium, and thermal nonequilibrium. …
Impact Damage In Curved Graphite/Epoxy Panels With Clamped Edges, Ronald B. Perry
Impact Damage In Curved Graphite/Epoxy Panels With Clamped Edges, Ronald B. Perry
Theses and Dissertations
Graphite/epoxy curved cylindrical panels were impacted in the center by an impact machine capable of measuring load during the test. Load, deflection and strain as functions of time were measured for six symmetric layup configurations for impact energies of 0.5 to 4.5 ft-lb. Damage was produced in all panels for certain impact energies. The extent and location of damage was determined from C-scans and optical microscopy of panel cross-sections. The cross-sections indicated that both delamination and transverse cracking contribute to internal damage. An in-house nonlinear finite element code was used to predict the panel deflections and stresses. The analysis produced …
Modelling And Analysis Of Kernel Function And Development Of Equivalent Theodorsen Function For Three-Dimensional Aeroelastic Analysis, John K. Ryder
Modelling And Analysis Of Kernel Function And Development Of Equivalent Theodorsen Function For Three-Dimensional Aeroelastic Analysis, John K. Ryder
Theses and Dissertations
A fractional calculus model is developed for the kernal function under incompressible subsonic flow conditions for rectangular planform airfoils with small aspect ratio. A model valid for restricted regions of the kernel function for compressible subsonic flow conditions is also developed. Additionally, a method for numerically solving the pressure-downwash integral equation for rectangular planform wings of aspect ratio two through ten in incompressible flow is developed. An equivalent Theodorsen function for three- dimensional unsteady flow is developed, enabling the use of simpler two- dimensional aeroelastic equations of motion to fully capture the more complicated three-dimensional effects.