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Navigation Of A Satellite Cluster With Realistic Dynamics, J. Timothy Middendorf
Navigation Of A Satellite Cluster With Realistic Dynamics, J. Timothy Middendorf
Theses and Dissertations
Previous work in the area of estimation of relative positions within a satellite cluster showed favorable results. However, the work was done using point mass orbits in the truth model. This thesis investigates the estimation of relative satellite positions operating in near circular orbit including the J2 term in Earth's geopotential. The iterated, extended Kalman filter is used as the on-board estimator in order to gain better performance in the face of the non-linearities. The dynamics in the estimator are based on the Clohessy- Wiltshire equations for relative orbital motion. Inputs to the host estimator are range measurements from …
Static Pressure Measurements Of A Low Power Arcjet, Kevin P. Talley
Static Pressure Measurements Of A Low Power Arcjet, Kevin P. Talley
Theses and Dissertations
The NASA Lewis 1.2 kilowatt arcjet has been used for a number of performance and lifetime studies. This design was modified to obtain static pressure measurements at several locations along the arcjet nozzle. These measurements were taken at various propellant flow rates over most of the operational envelope of the thruster. Measured static pressure distributions are considerably higher than predicted by ID models and are proportional to the arc power. A simple thermodynamic model is also compared to the data, and is shown to match the slope of the data while overpredicting the pressure.
Perturbation Theory For Restricted Three-Body Orbits, David A. Ross
Perturbation Theory For Restricted Three-Body Orbits, David A. Ross
Theses and Dissertations
A perturbation theory for restricted three-body orbits, using a periodic trajectory as a reference solution, is investigated. The nearly- periodic equations of motions are derived by analogy to a linearization about an equilibrium point. In this case, the linearization produces a set of time- periodic equations of motion that, according to Floquet, are completely solved by a periodic trajectory. The four-dimensional phase space of the restricted three-body problem is the first surveyed for regions of periodic motion, via the surface of section phase plot. Upon extraction of a periodic orbit, nearly- periodic orbits are integrated. The integrated state vector is …
Analysis Of Suborbital Launch Trajectories For Satellite Delivery, Mark R. Goodell
Analysis Of Suborbital Launch Trajectories For Satellite Delivery, Mark R. Goodell
Theses and Dissertations
A computer simulation program was used to analyse performance of suborbital launch trajectories using a hypersonic NASP derived vehicle for satellite deployment. The trajectory investigated for this project involved satellite deployment as suborbital speeds. To deploy a satellite in this manner, a booster motor is used to insert the payload into orbit while the launch vehicle reenters and returns to earth. A simplified energy analysis was also formulated and used to determine the sensitivity of suborbital trajectory performance to specific design parameters. Results show that suborbital launch trajectories can increase the useful payload to orbit capacity over an identical vehicle …
The Application Of Statistical Estimation Techniques To Terrain Modeling, Donald P. Duckett Jr.
The Application Of Statistical Estimation Techniques To Terrain Modeling, Donald P. Duckett Jr.
Theses and Dissertations
This thesis researches methods of generating accurate and realistic polygonal terrain models by reducing gridded sampled terrain elevation data such as DMA DTED. The terrain models generated should be applicable for use in flight simulators and other systems. Existing methods of terrain modeling are discussed, and limitations of these systems are presented. The geostatistical estimation technique known as kriging is presented as a method estimating terrain elevations at locations not provided in DMA DTED or other gridded terrain elevation data. Kriging is an optimal interpolation method based on statistical analysis of the data. It also provides a measure of accuracy, …
Formal Verification Of Digital Logic, Stuart L. Labovitz
Formal Verification Of Digital Logic, Stuart L. Labovitz
Theses and Dissertations
The most widely used technique for checking the correctness of digital circuits designs is simulation. As the complexity of digital circuits has continued to grow, however, circuit designers have become unable to perform complete simulations of their integrated circuits. Formal hardware verification provides an alternative approach, performing a series of mathematical proofs in order to show that the construction of the circuit from its submodules will result in the intended overall circuit behavior. Papers by Barrow in 1983 and 1984 discuss a PROLOG-based hierarchical formal circuit verification system named VERIFY. AFIT VERIFY, a simple, experimental reverse-engineered version of Barrow's VERIFY …
A Standardized Software Reliability Measurement Methodology, Joseph J. Stanko
A Standardized Software Reliability Measurement Methodology, Joseph J. Stanko
Theses and Dissertations
Current Air Force practice is to perform Operational Test and Evaluation (OT and E) for each new weapons system. In support of this, Headquarters Air Force Operational Test and Evaluation Center (HQ AFOTEC) is responsible for measuring both suitability and effectiveness. While suitability is adequately measured, the current effort only addresses hardware effectiveness, or at best, system effectiveness. Since tools and metrics are in place for software suitability assessments related to OT and E (for example, software maintainability), there should be some effective way of measuring the operational effectiveness of software. Currently, HQ AFOTEC/LG5 has a data collection tool for …
Frequency Domain Speech Coding, Shane Switzer
Frequency Domain Speech Coding, Shane Switzer
Theses and Dissertations
The major goal of this research was to investigate speech coding techniques in an attempt to achieve high quality speech transmittable at 4800 bits per second. The approach taken to achieve this goal was to code the frequency domain representation of speech. Speech was represented by a sparse set of frequency components. Four frequency selections schemes were implemented, and the resulting frequency coefficients (magnitude and phase) were coded in an efficient manner for transmission. Specific techniques involved in the speech coder included: (1) a recurrent neural architecture to make a periodic/noiselike decision, (2) the use of variable length windows for …
Requirements Analysis For A Hardware, Discrete-Event, Simulation Engine Accelerator, Paul J. Taylor Jr.
Requirements Analysis For A Hardware, Discrete-Event, Simulation Engine Accelerator, Paul J. Taylor Jr.
Theses and Dissertations
An analysis of a general Discrete Event Simulation (DES), executing on the distributed architecture of an eight mode Intel PSC/2 hypercube, was performed. The most time consuming portions of the general DES algorithm were determined to be the functions associated with message passing of required simulation data between processing nodes of the hypercube architecture. A behavioral description, using the IEEE standard VHSIC Hardware Description and Design Language (VHDL), for a general DES hardware accelerator is presented. The behavioral description specifies the operational requirements for a DES coprocessor to augment the hypercube's execution of DES simulations. The DES coprocessor design implements …
Implementation Of An Object-Oriented Flight Simulator D.C. Electrical System On A Hypercube Architecture, Guy R. Booth
Implementation Of An Object-Oriented Flight Simulator D.C. Electrical System On A Hypercube Architecture, Guy R. Booth
Theses and Dissertations
The Software Engineering Institute developed an Object-Oriented Paradigm for Flight Simulators based on the concept of mapping the behavior of physical objects from an aircraft into an object-oriented software architecture. This mapping is a semi-formal method that maps objects to a hierarchy that has three logical layers: objects, systems, and executives. The paradigm was developed with the idea of implementing the derived simulation design on a parallel or distributed computer architecture, but no explicity design features are provided for implementing the design on a parallel computer. This research addresses the issue of determining what extensions (if any) are required to …
Parallel Implementation Of Vhdl Simulations On The Intel Ipsc/2 Hypercube, Ronald C. Comeau
Parallel Implementation Of Vhdl Simulations On The Intel Ipsc/2 Hypercube, Ronald C. Comeau
Theses and Dissertations
VHDL models are executed sequentially in current commercial simulators. As chip designs grow larger and more complex, simulations must run faster. One approach to increasing simulation speed is through parallel processors. This research transforms the behavioral and structural models created by Intermetrics' sequential VHDL simulator into models for parallel execution. The models are simulated on an Intel iPSC/2 hypercube with synchronization of the nodes being achieved by utilizing the Chandy Misra paradigm for discrete-event simulations. Three eight-bit adders, the ripple carry, the carry save, and the carry-lookahead, are each run through the parallel simulator. Simulation time is cut in at …
Analysis Of A Decision Support System For Case Tool Selection And The Specification Of An Ada To Sql Abstract Interface, Tina M. Deangelis
Analysis Of A Decision Support System For Case Tool Selection And The Specification Of An Ada To Sql Abstract Interface, Tina M. Deangelis
Theses and Dissertations
Information overload has long been a problem in the fast moving technical field of software development. Yet quality information is needed to make informed decisions about buying software tools that help in software development. Computer Aided Software Engineering (CASE) tools help to coordinate and control information in large software developments. Many CASE tool purchases, however, are being based on ad hoc tool evaluation and selection methods which depend on biased vendor information. To capture specific knowledge about how to pick a tool for a given software development effort, a historical database that identifies important tool characteristics needed to be maintained …
An Event Driven State Based Interface For Synthetic Environments, Mark J. Gerken
An Event Driven State Based Interface For Synthetic Environments, Mark J. Gerken
Theses and Dissertations
Previous research at the Air Force Institute of Technology (AFIT) has produced synthetic environments using head mounted displays (HMDs) and hand measurement devices. This thesis is a continuation of AFIT synthetic environment research. Hand measurement data from a VPL DataGlove is combined with hand orientation and translational data to define a set of valid gestures. These gestures form the basis of an input language for class of finite automata known as finite state machines. Using the input symbols from this language, the user may define a finite state machine which associates a stream of input symbols with one or more …
Design And Implementation Of A Graphical User Interface And Database Management System For The Saber Wargame, Andrew M. Horton
Design And Implementation Of A Graphical User Interface And Database Management System For The Saber Wargame, Andrew M. Horton
Theses and Dissertations
Saber is a theater level, multi-sided, airpower employment computerized wargame that can be programmed to simulate any combat scenario. The model simulates theater level combat between air and land forces, and takes into account the effects of logistics, resupply, and both theater nuclear and chemical warfare. The major objective of the Saber model is to provide a suitable educational platform to allow users to apply basic, tactical employment concepts to multiple combat units, each having a specialized mission, and incorporating every branch of the armed services. This thesis documents a graphical user interface and data management system that has been …
An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design System, Timothy M. Jacobs
An Object-Oriented Database Implementation Of The Magic Vlsi Layout Design System, Timothy M. Jacobs
Theses and Dissertations
This thesis attempts to prove that the commercially available Object Store data management system provide the performance and functionality necessary to support a complex engineering design system. This is accomplished by modifying the Magic VLSI circuit layout design system to eliminate its current Unix file data management system and replace it with Object Store. The approach to this research effort includes a design recovery of the Magic system and identification of its ket data management functions. These functions are then modified to take advantage of the database management facilities of Object Store. Additional code is added to instrument performance measurement …
Enhanced Animation Of Parallel Algorithms, Michael D. Lack
Enhanced Animation Of Parallel Algorithms, Michael D. Lack
Theses and Dissertations
Algorithm animation is a visualization method used to enhance understanding of the functioning of an algorithm or program. Visualization is used for many purposes, including education, algorithm research, performance analysis, and program debugging. This research, which follows from previous work, examines algorithm animation requirements for the various visualization purposes and extends the capabilities of an existing facilities, the AFIT algorithm Animation Research Facility (AAARF). The structure of AAARF is summarised and its visualization capabilities presented, analysed and compared with other similar packages. This research focuses on the parallel data requirements of the AAARF users, and the meaningful display of large …
Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss
Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss
Theses and Dissertations
This research develops and implements Visual Refine, a graph-based visualization system, for the Refine wide-spectrum formal specification language and environment developed and marketed by Reasoning Systems, Inc. Refine specifications are represented in the Refine object base as abstract syntax trees (AST). Using these AST representations, one-to-one mappings are defined between nodes of the AST and the graphical icons of Visual Refine. Visual Refine uses these mappings to implement a set of formal transformations. Each transformation is encapsulated within a Refine rule, and this set of rules form the Visual Refine transformation system. The Visual Refine transformation system, in conjunction with …
Establishing A Methodology For Evaluation And Selecting Computer Aided Software Engineering Tools For A Defined Software Engineering Environment At The Air Force Institute Of Technology School Of Engineering, Jody L. Mattingly
Theses and Dissertations
This thesis identifies the software engineering environment (SEE) as it exists at the Air Force Institute of Technology (AFIT) School of Engineering. It also describes the software process model employed and the software development methods presented as part of the curriculum. Based on this information, criteria was established to evaluate computer aided software engineering (CASE) tools being considered for integration into the SEE. Each criterion was weighted to indicate its importance when selecting CASE tools. The criteria were further used to establish a methodology to be used to evaluate and select the CASE tools under consideration as well as future …
Improved Task Scheduling For Parallel Simulations, Andrew E. Mcnear
Improved Task Scheduling For Parallel Simulations, Andrew E. Mcnear
Theses and Dissertations
The objective of this investigation is to design, analyze, and validate the generation of optimal schedules for simulation systems. Improved performance in simulation execution times can greatly improve the return rate of information provided by such simulations resulting in reduced development costs of future computer/electronic systems. Optimal schedule generation of precedence-constrained task systems including iterative feedback systems such as VHDL or war gaming simulations for execution on a parallel computer is known to be N P-hard. Efficiently parallelizing such problems takes full advantage of present computer technology to achieve a significant reduction in the search times required. Unfortunately, the extreme …
A Spatially Partitioned Parallel Simulation Of Colliding Objects, Robert S. Moser
A Spatially Partitioned Parallel Simulation Of Colliding Objects, Robert S. Moser
Theses and Dissertations
This study investigated the application of a conservative synchronization paradigm to the classical, distributed pool balls simulation executed on an eight node, Intel iPSC/2 hypercube. Wieland's concept of spatial partitioning and limited data replication was used. Analysis has shown that 100% parallelization of execution is possible in a conservative environment via assignment of multiple sectors to nodes. Two conservative formulations for minimum safe time were derived. A tradeoff exists between scalability and efficiency. Optimum sectoring prediction has been shown possible through application of linear regression techniques. The results of this research reveal that a conservative approach to distributed, discrete event …
Speech Recognition Using Multiple Features And Multiple Recognizers, Thomas F. Rathbun
Speech Recognition Using Multiple Features And Multiple Recognizers, Thomas F. Rathbun
Theses and Dissertations
The purpose of this thesis is to demonstrate the feasibility of using multiple features and multiple recognizers to perform isolated word recognition. This is accomplished by performing multiple independent recognition tests and fusing the results together to get a single recognition result. The speech data is recorded and each word is extracted into a separate file. Eight features are calculated for each word. The features are calculated on 512 sample time slices and produce 16 component vector output. The three recognizers use the eight features to produce a total of 24 error distance lists. These lists are then fused together …
Three-Dimensional Medical Image Registration Using A Patient Space Correlation Technique, Patrick J. Rizzuto Jr.
Three-Dimensional Medical Image Registration Using A Patient Space Correlation Technique, Patrick J. Rizzuto Jr.
Theses and Dissertations
The routine clinical use of three-dimensional data provided by modern medical imaging procedures is often impeded by the difficulty in accurately correlating the resultant volume datasets. These data are frequently obtained at different times using the same modality, or images of the same patient are sometimes produced using more than one imaging modality. In order to analyze the similarities and differences between such images, it is necessary for the medical imaging data to be spatially aligned using a process known as image registration. This research investigated a structure-based image registration technique based upon simple, three-dimensional relationships among user identified landmarks. …
Design Of Style-V — A Translator To Convert Standard Vhdl Into A Stylized Form For Automated Microcode Generation, Dennis A. Rumbley
Design Of Style-V — A Translator To Convert Standard Vhdl Into A Stylized Form For Automated Microcode Generation, Dennis A. Rumbley
Theses and Dissertations
This thesis provides an analysis and preliminary design of Style V, a source-to-source computer language translator. Style-V converts IEEE standard VHDL into a special style of VHDL defined for a commercial tool, the Integrated Design Automation System (IDAS). Thirteen mappings between standard VHDL and the IDAS subset were identified. The mappings were analyzed using Domain Analysis and Modern Structured Analysis techniques. Four processes covering several of the mappings were completely analyzed. One mapping to convert CASE statements to IF statements was implemented. Since the IDAS restricts designs to bit logic, a method for representing multilevel logic with bit logic was …
Effect Of Spatial Locality Prefetching On Structural Locality, Dirk D. Schalch
Effect Of Spatial Locality Prefetching On Structural Locality, Dirk D. Schalch
Theses and Dissertations
The purpose of this research was to analyze the effect that spatial locality prefetching in cache memory has on the structural locality of program memory referencing behavior. To examine this, a software simulator was built to model a proposed two-level cache memory subsystem. The proposed subsystem was designed to use spatial locality prefetching to exploit the structural locality contained in executing computer workloads. New memory referencing models were developed to incorporate the combined use of structural locality and spatial locality prefetching. From these models, equations were derived to predict the hit rates for both caches. Combined with the state transition …
An Application Of The Object-Oriented Paradigm To A Flight Simulator, Dennis J. Simpson
An Application Of The Object-Oriented Paradigm To A Flight Simulator, Dennis J. Simpson
Theses and Dissertations
This thesis describes the object-oriented software development techniques that were used to analyze, design and implement a flight simulator. The objective of this thesis was to present a comprehensive object-oriented software development methodology and show how it was used in constructing an actual application. An extensive review of current object-oriented practices is presented along with the methods that were used to take the flight simulator from analysis to design and through to implementation. The description of the methodology concentrates upon the design and implementation phases of the object-oriented software lifecycle. Examples from the design of the flight simulator demonstrate how …
A Hybrid Approach To Battlefield Parallel Discrete Event Simulation, Steven R. Soderholm
A Hybrid Approach To Battlefield Parallel Discrete Event Simulation, Steven R. Soderholm
Theses and Dissertations
This thesis describes a method of parallelizing a battlefield discrete event simulation. The method combines elements of conservative time synchronization together with elements of optimistic computation and local rollback on a message passing hardware architecture. The battle simulation features aircraft moving in a battle area and launching missiles at enemy aircraft. Aircraft are randomly grouped into logical process (LPs), and a single LP is assigned to each processor. Aircraft state information is replicated across all LPs. Only the LP with the minimum next event time can execute safely. While one LP is executing safely all other LPs are precomputing their …
Parallelizing Serial Code For A Distributed Processing Environment With An Application To High Frequency Electromagnetic Scattering, Paul R. Work
Theses and Dissertations
This thesis investigates the parallelization of existing serial programs in computational electromagnetics for use in a parallel environment. Existing Algorithms for calculating the radar cross section of a object are covered, and a ray-tracing code is chosen for implementation on a parallel machine. Current parallel architectures are introduced and a suitable parallel machine is selected for the implementation of the chosen ray tracing algorithm. The standard techniques for the parallelization of serial code are discussed, including load balancing and decomposition considerations, and appropriate methods for the parallelization effort are selected. A load balancing algorithm is modified to increase the efficiency …
Formalization And Validation Of An Sadt Specification Through Executable Simulation In Vhdl, Daniel L. Eickmeier
Formalization And Validation Of An Sadt Specification Through Executable Simulation In Vhdl, Daniel L. Eickmeier
Theses and Dissertations
Formalizing an informal requirements specification, such as SADT, and executing the formal specification in a simulation environment, such as VHDL, provides a requirements analyst a means to validate the behavior of a specification early in the development life cycle. This research effort investigated and demonstrated the feasibility and benefit of transforming an SADT specification of a system into an equivalent VHDL executable simulation. Both non-time related behavior and concurrent, real-time related behavior is addressed. First, a decision table extension to SADT is created so that detailed, executable behavior can be specified. Next a mapping from SADT to VHDL is defined. …
Proportional Plus Integral Control Of Aircraft For Automated Maneuvering Formation Flight, John L. Dargan
Proportional Plus Integral Control Of Aircraft For Automated Maneuvering Formation Flight, John L. Dargan
Theses and Dissertations
In this study an automated formation control system for a lead and wing aircraft flight is developed. The proposed formation control system is capable of controlling like or dissimilar aircraft in maneuvering formation flight. Thus, two versions of the C-130 aircraft, the C-130A and the C-130B, are modelled. The C-130B has superior performance characteristics to that of the C- 130A. The wing aircraft continuously measures lead aircraft position with an ideal on-board relative position sensor, maneuvering to maintain relative position. External formation guidance is assumed to be released in a single data burst, consisting of formation geometry and nominal separation …
Electrically Erasable Programmable Integrated Circuits For Replacement Of Obsolete Ttl Logic, Joseph V. Breen
Electrically Erasable Programmable Integrated Circuits For Replacement Of Obsolete Ttl Logic, Joseph V. Breen
Theses and Dissertations
Two microcircuits with electrically erasable programmable logic arrays, which use Fowler-Nordheim (F-N) tunneling for both programming and erasing, were designed to demonstrate the use of programmable logic for obsolete TTL logic replacement. Each microcircuit was fabricated in the Orbit 2-micron double-poly low noise analog CMOS process through MOSIS. Software to generate VHDL structural models from a pin list was developed and the logic of both designs was verified by simulation using the Zycad VHDL simulator. The first microcircuit included a simple programmable logic circuit and test cells that allowed measurement of the programming characteristics of the floating gate transistors. Test …