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A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius
A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius
Theses and Dissertations
This study investigates magnus effects on a non-firmed missile model which had three axially rotating sections that span at different rates. Five spin cases are examined; the mid section spinning only; the front and rear sections spinning only; all section spinning at the same speed; all sections spinning in the same direction with the mid section spinning at an additional ten revolutions per second; and all sections spinning with the mid sections spinning the opposite direction at an additional ten revolutions per second. These five cases are tested at three different spin rates for two different wind tunnel velocities. Since …
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Under Tension-Tension And Tension-Compression Loading, Frank A. Opalski
Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Under Tension-Tension And Tension-Compression Loading, Frank A. Opalski
Theses and Dissertations
A study was conducted which investigated the behavior of a cross-ply [0/90]2S Nicalon/Calcium-Aluminosilicate (Nicalon/CAS) ceramic matrix composite at room temperature under tension-compression fatigue loading. Material behavior and damage was recorded by stress-strain curves, elastic modulus, hysteretic energy density, and acetate replication techniques. Tension-tension fatigue tests at a load ratio R of 0.1 (R = σmin/σmax) were completed which determined that 140 MPa was the maximum stress allowable in which cycle runout (1,000,000 cycles) would occur. Above this value, transverse crack density increased with respect to cycles and failure ultimately occurred. Tension-compression tests were then performed …
Open And Filled Hole Static Tensile Strength Characterization Of Metal Matrix Composite Scs-9/Β21s, Jacob T. Roush
Open And Filled Hole Static Tensile Strength Characterization Of Metal Matrix Composite Scs-9/Β21s, Jacob T. Roush
Theses and Dissertations
SCS-9/β21s has a reduced gauge thickness, in comparison with other metal matrix composites, due to a smaller diameter fiber. This reduced gauge thickness makes it an attractive candidate for the skin of hypersonic vehicles. Tensile testing of (0/90)2s and (O/±45/90)s laminates was performed at room temperature, 482°C, and 650°C. Both notched and unnotched specimens were tested. Notched specimens, open and filled hole, had a width-to-diameter ratio of six. Materials 7075-T6 and Mar-m-246 were used as pins in the filled hole tensile testing. Analytical work was completed to predict material properties, elastic and plastic stress concentration factors, residual stresses, …
Application Of The Program Profile For The Design Of Low-Speed, Low- Observable Configuration Airfoils, Gregory A. Sharp
Application Of The Program Profile For The Design Of Low-Speed, Low- Observable Configuration Airfoils, Gregory A. Sharp
Theses and Dissertations
This study investigated-the use of the program PROFILE for the design of low-speed, low-observable configuration airfoils. For our purposes, low- observable configuration is defined as being characterized by a small leading- edge radius of less than 1.18 percent chord and a thickness-to-chord ratio of 2. 5 to 5.5 percent. A methodology was developed whereby the input parameters to prescribe the velocity distribution over the airfoil could be determined by a power law relationship. This relationship enables the designer to develop symmetric airfoils with the desired thickness-to-chord and leading-edge radius within the stated constraints. The resulting symmetric airfoils compared very well …
Helicopter Flight Control System Design Using The Linear Quadratic Regulator For Robust Eigenstructure Assignment, Dempsey D. Solomon
Helicopter Flight Control System Design Using The Linear Quadratic Regulator For Robust Eigenstructure Assignment, Dempsey D. Solomon
Theses and Dissertations
This thesis applied modern, multi-variable control design techniques, via a FORTRAN computer algorithm, to U.S. Army helicopter models in hovering flight conditions. Eigenstructure assignment and Linear Quadratic Regulator (LQR) theory are used to achieve enhanced closed loop performance and stability characteristics with full state feedback. The addition of cross coupling weights to the standard LQR performance index is specifically addressed. A desired eigenstructure is chosen with a goal of reduced pilot workload via performance qualities requirements. Cross coupling weighting is shown to provide greater flexibility in achieving a desired closed loop eigenstructure. While the addition of cross coupling weighting is …
Computational And Experimental Investigation Into Fracture Of Brittle Fiber - Brittle Matrix Composite Systems, James P. Solti
Computational And Experimental Investigation Into Fracture Of Brittle Fiber - Brittle Matrix Composite Systems, James P. Solti
Theses and Dissertations
Experimental and computational analyses provided an improved understanding of quasi-static fracture in model composite systems. Constant displacement compression tests using borosilicate glass double cleavage drilled compression test templates provided qualitative assessments of localized toughening for crack growth near cylindrical inclusions. Large crack-tip stress fields induced interfacial slip and separation prior to arrival of the main crack. Debonding and the proliferation of secondary matrix cracks characterized the role of bridging fibers along weak interfaces. Strong residual normal compressive interfacial stresses diminished the influence of crack-tip stresses; however, slip was still observed. VHS tape and computer enhanced photos record a history of …
An Experimental Investigation Of A Finite Circulation Control Wing, John M. Tallarovic
An Experimental Investigation Of A Finite Circulation Control Wing, John M. Tallarovic
Theses and Dissertations
This wind tunnel investigation examined the lift, drag, and pitching moment of a 20% thick, 8.5% camber, partial elliptical cross-section, single blowing slot, rectangular, circulation control wing. The aspect ratios tested were 3.71 and 3.99. Variables included three differently shaped trailing edge Coanda surfaces and steady blowing and pulsed blowing. The test Reynolds number, based on the chord was 500,000. The-angle of attack was varied from minus 6 degrees to the inception of stall. The maximum lift coefficient measured was 3. 17 with an equivalent drag coefficient of 1.85. Results also show a limit to increasing lift by increasing the …
Behavior Of A Centrally Notched Cross-Ply And Unidirectional Ceramic Matrix Composite In Tension-Compression Fatigue, William A. Weidenaar
Behavior Of A Centrally Notched Cross-Ply And Unidirectional Ceramic Matrix Composite In Tension-Compression Fatigue, William A. Weidenaar
Theses and Dissertations
Centrally notched (hole), cross-ply, ((0/90)2)s, and unidirectional, (0)8 laminates of Silicon Carbide fiber-reinforced Aluminosilicate glass, SiC/1723, were fatigue tested under tension-compression loading with a load ratio of -1. Damage accumulated continuously for both lay- ups, leading to eventual failure and a reduced fatigue life. Critical damage in the cross-ply consisted of longitudinal cracks in the 90° plies growing and combining with transverse cracks to effectively eliminate the 90° plies' load carrying capability and allowing the specimen to buckle. Critical damage in the unidirectional lay-up consisted of longitudinal cracks which initiated at the shear stress concentration …
A Comparison Of Computational Fluid Dynamics Computer Programs For Hypersonic Propulsive Nozzle Flowfields, Kennedy B. Wilson Jr.
A Comparison Of Computational Fluid Dynamics Computer Programs For Hypersonic Propulsive Nozzle Flowfields, Kennedy B. Wilson Jr.
Theses and Dissertations
This study compared the results of two computer programs, a flux- difference-splitting (FDS) Godunov-based scheme and the SCPAMjet Hypersonic Nozzle (SCHNOZ) paraobolized Navier-Stoke's code using MacCormack's method, applied to a hypersonic nozzle flowfield. Two different nozzle geometries were investigated at three Mach numbers along a typical hypersonic flight trajectory. A direct compariosn between the SCHNOZ and FDS programs was made by numerically solving the steady Euler equations using a frozen flow assumption in the nozzle. The frozen flow SCHNOZ code is currently 6 to 10 times more efficient in terms of computational time than the FDS frozen flow code. The …
Object-Oriented Analysis, Design, And Implementation Of The Saber Wargame, David S. Douglass
Object-Oriented Analysis, Design, And Implementation Of The Saber Wargame, David S. Douglass
Theses and Dissertations
Saber is a two-sided, air and land war game that simulates decisions made of commanders at the theater-level. It is being developed by the Air Force Institute of Technology for the Air Force Wargaming center at Maxwell AFB, Alabama. Saber models conventional, chemical, and nuclear warfare between aggregated air and land forces. It also portrays the effects of logistics, satellites, weather, terrain, and intelligence which add to the realism of the Saber war game. The Saber war game has three main components, the preprocessor. which is responsible for scenario development and pregame activities, the simulation. the guts of the war …
A Vhdl Interpreter For Model-Based Diagnoses, David R. Griffin
A Vhdl Interpreter For Model-Based Diagnoses, David R. Griffin
Theses and Dissertations
Model-based reasoning permits diagnostic applications to be written without waiting for someone to become an 'expert' of the system. For model-based diagnostics, there must be a model to reason from. This thesis explores using a VHDL description of the system as that model. A system based around a VHDL interpreter was written specifically for a model-based diagnostic algorithm. Currently, the diagnostic system uses an algorithm by Dries. This algorithm was derived from Scarl's Full Consistency Algorithm. The system was designed to be modular so that different diagnostic techniques could be implemented. It is divided into three parts: a VHDL parser, …
Design And Development Of A High-Speed Winograd Fast Fourier Transform Processor Board, James F. Herron
Design And Development Of A High-Speed Winograd Fast Fourier Transform Processor Board, James F. Herron
Theses and Dissertations
Since 1985, the Air Force Institute of Technology has pursued a project to develop a 4080-point Discrete Fourier Transform processor using the Winograd Fourier Transform Algorithm (WFTA) and Good-Thomas Prime Factoring Algorithm (PFA). In the first attempt to build a working system, this research effort designed and constructed, in part, a modified single processor architecture in order to demonstrate the proof of concept of the WFTA system design. This prototype architecture is simpler in implementation but uses the same principles and procedures as those of the 4080-point WFTA design. The design developed in this thesis was validated using the Very …
Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii
Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii
Theses and Dissertations
Pilots select routes based on factors such as threats, fuel, time on target, distance, and refueling points. This is a time consuming task. This thesis presents the software engineering synthesis of a software tool, based on a parallelized A* search algorithm, to select routes. For simplicity only threats and distance are used. A centralized open list is used with one processor managing the list while the other processors perform the node expansions. This decomposition result in a dynamically load balanced system. A number of parameters are changed to study their impact on the execution time. The use of a branch …
A User Interface To A True 3-D Display Device, Bruce A. Hobbs
A User Interface To A True 3-D Display Device, Bruce A. Hobbs
Theses and Dissertations
This thesis describes an interactive interface to a true three dimensional, real-dm dynamic graphic display, the TI Omniview™. The system generates true 3-D images of volumetric data and objects. The TI Omniview is a cylindrical volumetric laser display that uses a rotating double-helix translucent disk to fill the display cylinder. Voxels are illuminated on the 2-D surface. The rotational speed of the disk allows the viewer to fuse the 2-D images into a true 3-D image. The interface provides the user with a quick and flexible means of manipulating the image generated, the sub-volume displayed, and the resulting 3-D image. …
An Investigation Of Discovery-Based Learning In The Route Planning Domain, Freeman A. Kilpatrick Jr.
An Investigation Of Discovery-Based Learning In The Route Planning Domain, Freeman A. Kilpatrick Jr.
Theses and Dissertations
This thesis presents MAVERICK, a Discovery-Based learning (DBL) system designed to learn maneuvers in the route planning domain. DBL was originally designed to learn in domains for which little domain knowledge exists. This thesis proposes using it in domains for which knowledge exists, but the acquisition of this knowledge is difficult or time-consuming because of the knowledge acquisition bottleneck. The operation of the DBL process in MAVERICK was investigated to determine the potential utility of such a system to a real- world Air Force problem in the domain of aircraft route planning. MAVERICK worked well in its limited domain, and …
Generalization And Parallelization Of Messy Genetic Algorithms And Communication In Parallel Genetic Algorithms, Laurence D. Merkle
Generalization And Parallelization Of Messy Genetic Algorithms And Communication In Parallel Genetic Algorithms, Laurence D. Merkle
Theses and Dissertations
Genetic algorithms (GA) are highly parallelizable, robust semi- optimization algorithms of polynomial complexity. The most commonly implemented GAs are 'simple' GAs (SGAs). Reproduction, crossover, and mutation operate on solution populations. Deceptive and GA-hard problems are provably difficult for simple GAs. Messy GAs (MGA) are designed to overcome these limitations. The MGA is generalized to solve permutation type optimization problems. Its performance is compared to another MGA's, an SGA's, and a permutation SGA's. Against a fully deceptive problem the generalized MGA (GMGA) consistently performs better than the simple GA. Against an NP-complete permutation problem, the GMGA performs better than the other …
A Radiosity Approach To Realistic Image Synthesis, Richard L. Remington
A Radiosity Approach To Realistic Image Synthesis, Richard L. Remington
Theses and Dissertations
The Air Force Institute of Technology (AFIT) has not had the capability to generate photorealistic images. This thesis is a research effort to implement such a system at AFIT, and to apply knowledge from the particle transport community to this problem. Investigation into various techniques for generating photorealistic images led to the conclusion that the radiosity method would serve as the foundation for development. This is because of the increased accuracy of the diffuse reflections with the radiosity method and the fact that the images produced with radiosity axe view-independent. Two distinct tools to generate photorealistic images axe described. The …
Examining A Layered Approach To Function And Design Representation For Reusable Software Components, Paul D. Siebels
Examining A Layered Approach To Function And Design Representation For Reusable Software Components, Paul D. Siebels
Theses and Dissertations
This effort examined ways to improve the effectiveness of reusable software libraries. The main area of investigation was in improving the user interface by finding better ways to present the software components to potential re-users. The first aspect which was considered was finding an effective representation for reusable software components. A set of criteria was developed for evaluating the effectiveness of software representations. The criteria consisted of generality, expressiveness, understandability, consistency, and resolution. The second aspect which was considered was how to present the software component information to the user to facilitate finding the appropriate component for reuse. A representation …
An Intelligent Real-Time System Architecture Implemented In Ada, Michael A. Whelan
An Intelligent Real-Time System Architecture Implemented In Ada, Michael A. Whelan
Theses and Dissertations
Conventional real-time systems are fully deterministic allowing for off-line, optimal, task scheduling under all circumstances. Real-time intelligent systems add non-deterministic task execution times and non- deterministic task sets for scheduling purposes. Non-deterministic task sets force intelligent real-time systems to trade-off execution time with solution quality during run-time and perform dynamic task scheduling. Four basic design considerations addressing those tradeoffs have been identified: control reasoning, focus of attention, parallelism, and algorithm efficacy. Non-real- time intelligent systems contain an environment sensor, a model of the environment, a reasoning process, and a large collection of procedural processes. Real-time intelligent systems add to these …
Creating And Manipulating Formalized Software Architectures To Support A Domain-Oriented Application Composition System, Cynthia G. Anderson
Creating And Manipulating Formalized Software Architectures To Support A Domain-Oriented Application Composition System, Cynthia G. Anderson
Theses and Dissertations
This research investigated technology which enables sophisticated users to specify, generate, and maintain application software in domain-oriented terms. To realize this new technology, a development environment, called Architect, was designed and implemented. Using canonical formal specifications of domain objects, Architect rapidly composes these specifications into a software application and executes a prototype of that application as a means to demonstrate its correctness before any programming language specific code is generated. Architect depends upon the existence of a formal object base (or domain model) which was investigated by another student in related research. The research described in this thesis relied on …
A Model For Determining Task Set Schedulability In The Presence Of System Effects, Rusty O. Baldwin
A Model For Determining Task Set Schedulability In The Presence Of System Effects, Rusty O. Baldwin
Theses and Dissertations
This research developed a parameterized model that accounts for system overhead and determines when an Ada runtime environment can no longer successfully execute a given Ada task set and still meet all deadlines. The Ada Compiler Evaluation Capability benchmark was used to characterize an actual runtime environment. Using that data, a generic model of a preemptive, rate monotonic priority based runtime system was developed which accounts for overhead due to clock updates, context switching, task suspension, and synchronization. Validation was based on the Hartstone benchmark. First, the benchmark was executed using, the actual runtime environment. Then, those results were compared …
Spatial Partitioning Of A Battlefield Parallel Discrete-Event Simulation, Kenneth C. Bergman
Spatial Partitioning Of A Battlefield Parallel Discrete-Event Simulation, Kenneth C. Bergman
Theses and Dissertations
This thesis describes a method for spatially partitioning a battlefield into units known as sectors to achieve speedup two ways: through the reduction of each battlefield object's next event search space, and lowering the amount of message-passing required. Each sector is responsible for tracking and controlling access to all objects within its boundaries. A distributed proximity detection algorithm employing boundary-crossing events is used to control player movement between sectors. Each object's state information is replicated in all sectors it has sensor capability for the minimum time required; -this ensures that each object's next event is properly determined based upon interactions …
Formalization And Transformation Of Informal Analysis Models Into Executive Refine™ Specifications, Mary M. Boom, Bradley D. Mallare
Formalization And Transformation Of Informal Analysis Models Into Executive Refine™ Specifications, Mary M. Boom, Bradley D. Mallare
Theses and Dissertations
This research developed and implemented an automated technique for translating informal specifications into formal, executable specifications. A unified Abstract Model (UAM) was developed to combine the information contained in Entity Relationship, State Transition, and Data Flow Models into a concise, object-based representation. The UAM forms the basis for defining a formal language, the Object Modeling Language (OML), used to capture the information contained in the UAM. By using OML, we were able to develop an automated translation process to convert informal specifications into executable, formal specifications. The Software Refinery Development Environment enabled us to easily develop a parser that translates …
Version And Transaction Management In Osmagic: An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design Tool, Gary M. Lightner
Version And Transaction Management In Osmagic: An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design Tool, Gary M. Lightner
Theses and Dissertations
The goal of this thesis was to study the feasibility of using an object-oriented database management system to provide the functionality and performance needed to support a complex computer-aided design tool. We do this by modifying OSMagic, a prototype system of the Magic very large scale integrated (VLSI) circuit design tool implemented on the ObjectStore object- oriented database management system. OSMagic was changed to support three different interfaces to ObjectStore and to work in a networking environment. We then designed and examined the use of version and transaction management models as a means of addressing the weaknesses of the prototype …
Efficient Derivation And Approximations Of Cepstral Coefficients For Speech Coding, Kimberly A. Limcangco
Efficient Derivation And Approximations Of Cepstral Coefficients For Speech Coding, Kimberly A. Limcangco
Theses and Dissertations
A new formulation is presented for the calculation of cepstral coefficients directly from measured sine wave amplitudes and frequencies of speech waveforms. Approximations to these cepstral coefficients are shown to be suitable for operation in a real-time speech coding environment. These results were encoded in the C programming language and then evaluated through experiments that were conducted on the McAulay-Quatieri Sinusoidal Transform Coder (STC).
A Unified Model Of Program Behavior, Douglas T. Michel
A Unified Model Of Program Behavior, Douglas T. Michel
Theses and Dissertations
This thesis is an attempt to account for and unify the three types of locality: temporal, spatial, and structural. A diverse sample of traces are used in measuring program behavior with respect to these localities and a model is presented which represents the memory references a program generates as it goes through execution. The model is validated by estimating, the entropy of a synthetically generated trace and comparing it with actual traces. The results indicate that there is more predictability contained in the original trace than what the model was able to capture. Different variations of the model were tried …
An Enhanced User Interface For The Saber Wargame, Donald R. Moore
An Enhanced User Interface For The Saber Wargame, Donald R. Moore
Theses and Dissertations
This thesis is part of an on-going effort by the Air Force Institute of Technology to develop a computer-based, theater-level wargame for the Air Force Wargaming Center at Maxwell AFB, AL. The wargame, Saber, is intended to augment the education the students receive at the Air War College and the Air Command and Staff College in the employment of air and ground power. This thesis documents the integrated design and implementation of the two components of the Saber user interface: the pre-processor and the post-processor. Although previous thesis students designed and implemented substantial portions of the user interface, a fully …
Ada Implementation Of An Object Data Repository, Stephen P. Perucca
Ada Implementation Of An Object Data Repository, Stephen P. Perucca
Theses and Dissertations
The many benefits of object-oriented software development such as encapsulation and extendibility have inspired numerous models of the object- oriented paradigm. Rumbaugh's Object Modeling Technique (OMT) is an object- oriented model that uses three submodels. The object, dynamic, and functional submodels of the OMT describe the data, behavioral, and processing aspects of a system by using entity-relationship, state-transition, and data flow models. Cross-links relate how the three submodels tie together. Two metamodels (models of models) of the OMT are developed using the OMT methodology and notation. The essential data elements of the OMT are abstracted into a data metamodel, and …
A Synthetic Environment For Satellite Modeling And Satellite Orbital Motion, David L. Pond
A Synthetic Environment For Satellite Modeling And Satellite Orbital Motion, David L. Pond
Theses and Dissertations
Analysts tasked to study satellites moving in space must often rely on photographs to conduct their analysis. Often these photographs do not adequately represent how satellites move in space, their spatial relationships, or their interaction with other satellites. What analysts need is a three- dimensional synthetic environment that depicts satellites as they actually move and interact in space. This thesis addresses the early development of the Satellite Modeler (SM), a system that allows analysts to study, satellite motion and maneuvering of computer aided design (CAD) models of those satellites in a three-dimensional orbit. The system contains equipment that allows analysts …
Creating And Manipulating A Domain-Specific Formal Object Base To Support A Domain-Oriented Application Composition System, Mary Anne Randour
Creating And Manipulating A Domain-Specific Formal Object Base To Support A Domain-Oriented Application Composition System, Mary Anne Randour
Theses and Dissertations
This research investigated technology which enables sophisticated users to specify, generate, and maintain application software in domain-oriented terms. To realize this new technology, a development environment, called Architect, was designed and implemented. Using canonical formal specifications of domain objects, Architect rapidly composes these specifications into a software application and executes a prototype of that application as a means to demonstrate is correctness before any programming language specific code is generated. This thesis investigated populating and manipulating the formal object base required by Architect. This object base is built using a domain- specific language (DSL) which serves as an interface between …