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Air Force Institute of Technology

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Network Security Versus Network Connectivity: A Framework For Addressing The Issues Facing The Air Force Medical Community, Franklin E. Cunningham Jr. Dec 1999

Network Security Versus Network Connectivity: A Framework For Addressing The Issues Facing The Air Force Medical Community, Franklin E. Cunningham Jr.

Theses and Dissertations

The Air Force has instituted Barrier Reef to protect its networks. The Air Force medical community operates network connections that are incompatible with Barrier Reef. To overcome this problem, OASD(HA) directed the Tri-Service Management Program Office (TIMPO) to develop an architecture that protects all military health systems and allows them to link with all three services and outside partners. This research studied the underlying networking issues and formed a framework based on data from network experts from the Air Force's medical centers and their base network organizations. The findings were compared TIMPO and a composite framework was developed that more …

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Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii Dec 1999

Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii

Theses and Dissertations

Thin rectangular samples of Ti-6Al-4V were damaged by four methods to represent foreign object damage found in turbine engine blades: 1) impact with 2 mm and 5 mm diameter glass spheres at 305 m/s, 2) impact with 2 mm and 4 mm diameter steel spheres at 305 m/s, 3) quasi-static displacement controlled indentation using steel chisels with 1 mm, 2 mm and 5 mm diameter tips and 4) shearing notches with a 2 mm diameter chisel point under a quasi-static loading condition. Finite element analysis was used to study the relationship between the stress state created by the plastic damage …

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Application Of The Interaction Picture To Reactive Scattering In One Dimension, Michael J. Maclachlan Dec 1999

Application Of The Interaction Picture To Reactive Scattering In One Dimension, Michael J. Maclachlan

Theses and Dissertations

The interaction picture is used together with the channel-packet method in a new time-dependent approach to compute reactive scattering matrix elements. The channelpacket method enables the use of the interaction picture for computing reactive S-matrix elements by splitting the computational effort into two parts. First, asymptotic reactant and product wavepackets are individually propagated into the interaction region of the potential to form Moller states. The interaction picture, in contrast to the usual Schrödinger picture of quantum mechanics, is so constructed that a wavefunction that experiences no change in potential (that is, a free-particle wavefunction) remains always fixed, with no translation …

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Collisional Dynamics Of Bi2 A(0U+). I. Quantum-Resolved Vibrational Energy Transfer For V′=0–4, Robert E. Franklin, Glen P. Perram Oct 1999

Collisional Dynamics Of Bi2 A(0U+). I. Quantum-Resolved Vibrational Energy Transfer For V′=0–4, Robert E. Franklin, Glen P. Perram

Faculty Publications

Vibrational-to-translational energy transfer between the lowest vibrational levels (v′=0–4) of the A(0+u) state of Bi2 has been investigated using spectrally resolved, laser-induced fluorescence techniques. The small vibrational spacing (ω′e≃132 cm−1) leads to highly nonadiabatic conditions, particularly for the Bi2(A)–He collision pair. However, the Δv=−1 transition probabilities for collisions with the rare gases range from 0.75% to 1.75% per collision, considerably lower than would be anticipated from standard vibrational energy transfer theory. Multiquantum (Δv′=±2) transfer rates are low, consistent with the low anharmonicity of the A(0+u) state. The rates for …

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Efficient Simulation Via Validation And Application Of An External Analytical Model, Thomas H. Irish Sep 1999

Efficient Simulation Via Validation And Application Of An External Analytical Model, Thomas H. Irish

Theses and Dissertations

This research makes significant contributions towards improving the efficiency of simulation studies using an external analytical model. The foundation for this research is the analytical control variate (ACV) method. The ACV method can produce significant variance reduction, but the resulting point estimate may exhibit bias. A Monte Carlo sampling method for resolving the bias problem is developed and demonstrated through a queueing network example. The method requires knowledge of the parameters and approximate distributions of the random variables used to produce the ACV. Often, some of these parameters or distributions are not known. Both parametric and non-parametric alternatives to the …

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Multiple Comparison Pruning Of Neural Networks, Donald E. Duckro Sep 1999

Multiple Comparison Pruning Of Neural Networks, Donald E. Duckro

Theses and Dissertations

Reducing a neural network's complexity improves the ability of the network to be applied to future examples. Like an overfitted regression function, neural networks may miss their target because of the excessive degrees of freedom stored up in unnecessary parameters. Over the past decade, the subject of pruning networks has produced non-statistical algorithms like Skeletonization, Optimal Brain Damage, and Optimal Brain Surgery as methods to remove connections with the least salience. There are conflicting views as to whether more than one parameter can be removed at a time. The methods proposed in this research use statistical multiple comparison procedures to …

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The Development Of Laser Cost Estimating Relationships (Cers) From Commercial Data, Michael J. Nolette, Steven L. Seeley Sep 1999

The Development Of Laser Cost Estimating Relationships (Cers) From Commercial Data, Michael J. Nolette, Steven L. Seeley

Theses and Dissertations

The Post Cold War acquisition environment has been marked by significant budget reductions and the greater use of commercial practices. In this austere and rapidly changing acquisition environment, accurate cost estimates are paramount to maximize the use of the DoD's critical resources. The advancement of laser technology has spawned a large variety of military laser applications such as the Airborne Laser (ABL), Space Based Laser (SBL) and a host of other smaller programs. Furthermore, the Air Force Laboratory's Directed Energy Applications for Tactical Airborne Combat (DEATAC) Study (the sponsoring activity of this thesis research) is considering a host of airborne …

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Formal Representation And Application Of Software Design Information, Thomas M. Schorsch Sep 1999

Formal Representation And Application Of Software Design Information, Thomas M. Schorsch

Theses and Dissertations

Formal methods for developing software use mathematical frameworks to specify, develop and verify software systems, especially safety critical systems where error free software is a necessity. A transformation system is a formal method that refines a requirement specification into an implementation by successively adding design decisions in the form of precisely verified design information. Current algebraic representations of design information (specifications, morphisms, and interpretations) and methods for applying algebraic specification design information (diagram refinement) cannot correctly represent and apply design information involving higher level design information. This investigation develops innovative methods for constructing and refining structured algebraic requirement specifications, as …

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Workplace Violence: Exploring The Dangers For Air Force Leadership, Shawn R. Jones Sep 1999

Workplace Violence: Exploring The Dangers For Air Force Leadership, Shawn R. Jones

Theses and Dissertations

The repeated occurrences of workplace violence throughout society today require the Air Force to evaluate its own workplaces and determine if a threat exists. This research explored violence in the workplace and established the possibility that workplace violence can affect the Air Force. Additionally, Air Force Climate Assessment Surveys were evaluated to find information that could be useful in detecting early warning signs of potential workplace violence. A number of examples of violence that occurred within Air Force workplaces highlighted the threat for Air Force leadership. With over 1,680 incidents of workplace violence reported to the AFOSI in a 5-year …

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A Methodology For The Analysis And Prediction Of Air Force Enlisted Aircraft Maintenance Personnel Retention Rates Using Economic Statistics, Peter D. Lommen Sep 1999

A Methodology For The Analysis And Prediction Of Air Force Enlisted Aircraft Maintenance Personnel Retention Rates Using Economic Statistics, Peter D. Lommen

Theses and Dissertations

The purpose of this study is to investigate the effects of certain national economic indicators on enlisted aircraft maintenance personnel retention rates. To fulfill this purpose, this study builds a linear regression equation that can predict the retention rate using the civilian unemployment rate and the index of 11 leading economic indicators as the independent variables. Journal literature and economic texts were reviewed to identify the indicators as good predictors for changes in employee turnover. The method of linear regression was used to build the model needed to predict the changes in the retention rate. The equation developed with this …

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The Effect Of Action Workouts On Aircraft Mission Capability Measurements, Michael P. Allison Sep 1999

The Effect Of Action Workouts On Aircraft Mission Capability Measurements, Michael P. Allison

Theses and Dissertations

Previous studies concerning quality improvement and the Action Workout Process attempted to define and describe the difficult concept of quality. A logical next step is to study to what extent implementation of a quality improvement program, such as ACC's Action Workout Process, positively or negatively affects performance factors within an Air Force organization. This study focused on exploring the fundamental question of whether there was, as a result of the Action Workout, a noticeable, statistically verifiable, positive or negative change in the mission capability of aircraft assigned to the units carrying out this quality improvement initiative. Research questions were developed …

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Pollution Prevention Cost Savings Using Supply Chain Reengineering, Gregory S. Webb Sep 1999

Pollution Prevention Cost Savings Using Supply Chain Reengineering, Gregory S. Webb

Theses and Dissertations

Supply chain management was explored as a tool to prevent hazardous waste and reduce operating costs. Previous research had shown that pollution prevention measures were often costly and no expectation of cost savings could be realized. The reengineering of the Air Force hazardous material supply chain brought about by the Hazardous Material Pharmacy Program was tested to evaluate if hazardous waste had been precluded in this effort and if costs had also been avoided. To date, no research had explored the use of supply chain management as a source reducer of hazardous waste. Consequently, little was known or understood of …

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An Ex Post Facto Analysis Of E-3 Maintenance Indicators In The 552d Air Control Wing Since Reorganization Under An Aircraft Generation Squadron Concept, Larry J. Stetz Sep 1999

An Ex Post Facto Analysis Of E-3 Maintenance Indicators In The 552d Air Control Wing Since Reorganization Under An Aircraft Generation Squadron Concept, Larry J. Stetz

Theses and Dissertations

Organizational restructuring sometimes occurs in the aircraft maintenance field, yet seldom are in-depth analyses performed after the fact to see if productivity improved. In December 1995, the 552D Air Control Wing restructured its flight line maintenance into an aircraft generation squadron concept. This study looked at before and after maintenance indicators to see if productivity improved. Maintenance data was collected from December 1993 to December 1997. Nineteen maintenance indicators were identified, and the key indicators were analyzed using means comparison and regression analysis to determine if efficiency and effectiveness had increased. The variables Mission Capable rate and Man-hours per Flying …

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Logistic Regression Modeling Of Diminishing Manufacturing Sources For Integrated Circuits, Michael J. Gravier Sep 1999

Logistic Regression Modeling Of Diminishing Manufacturing Sources For Integrated Circuits, Michael J. Gravier

Theses and Dissertations

The problem of Diminishing Manufacturing Sources and Material Shortages (DMSMS) afflicts the Air Force and other armed services in a way unforeseen in the past. The costs of DMSMS manifest themselves both in terms of monetary expense and diminished mission readiness. The current environment of limited defense spending and high operations tempo exacerbates this problem. This thesis draws on available data from the electronics integrated circuit industry to attempt to assess whether statistical modeling offers a viable method for predicting the presence of DMSMS. The research identified logistic regression as a powerful tool for analysis of DMSMS and further developed …

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Air Force Institute Of Technology Research Report 1998, Air Force Institute Of Technology Jul 1999

Air Force Institute Of Technology Research Report 1998, Air Force Institute Of Technology

AFIT Documents

This report summarizes the research activities of the Air Force Institute of Technology's Graduate School of Engineering and the Graduate School of Logistics and Acquisition Management. It describes research interests and faculty expertise; list student theses/dissertations; identifies research sponsors and contributions; and outlines the procedure for contacting either school.

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Analysis Of N-Tier Architecture Applied To Distributed-Database Systems, Alexandre G. Valente Jun 1999

Analysis Of N-Tier Architecture Applied To Distributed-Database Systems, Alexandre G. Valente

Theses and Dissertations

N-tier architecture has been more commonly used as a methodology for developing large database applications. This work evaluates the use of this architecture instead of the classical Client/Server architecture in developing corporate applications based on distributed databases. The comparison between architectures is performed using applications that execute transactions similar to those defined in the Transaction Process Council Type C benchmark (TPC-C). The environment used for development and testing was the AFIT Bimodal Cluster (ABC); a heterogeneous cluster of PCs, running Microsoft Windows NT 4.0 OS. The comparative experimental analysis demonstrated that the N-tier architecture allows more efficient bandwidth utilization between …

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Scan-It: A Computer Vision Model Motivated By Human Physiology And Behavior, John G. Keller Jun 1999

Scan-It: A Computer Vision Model Motivated By Human Physiology And Behavior, John G. Keller

Theses and Dissertations

This dissertation details the development of a new computational vision model motivated by physiological and behavioral aspects of the human visual system. Using this model, intensity features within an artificial visual field of view are extracted and transformed into a simulated cortical representation, and a saccadic guidance system scans this field of view over an object within an image to memorize that object. The object representation is thus stored as a sequence of feature matrices describing sub-regions of the object. A new image can then be searched for the object (possibly scaled and rotated), where evidence of its presence is …

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Timed Safety Automata And Logic Conformance, Frank C. D. Young Jun 1999

Timed Safety Automata And Logic Conformance, Frank C. D. Young

Theses and Dissertations

Timed Logic Conformance (TLC) is used to verify the behavioral and timing properties of detailed digital circuits against abstract circuit specifications when both are modeled as Timed Safety Automata (TSA) with real-valued clocks. TLC is a bisimulation-style partial order relationship defined over TSA state space. In contrast to timed simulation, Calculus of Timed Refinement, and time-abstracted bisimulation, TLC defines when one system is an acceptable implementation of another by asymmetric action-matching requirements for specification inputs and implementation outputs. TLC intuitively and pragmatically supports writing abstract specifications and verifying them against implementations. TLC scales up by substituting verified specifications for implementations …

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Methodology For Integrating The Scenario Databases Of Simulation Systems, Emilia M. Colonese Jun 1999

Methodology For Integrating The Scenario Databases Of Simulation Systems, Emilia M. Colonese

Theses and Dissertations

The use of many different simulation systems by the United States Department of Defense has resulted in many different scenario data representations contained in heterogeneous databases. These heterogeneous databases all represent the same data concept, but have different semantics due to intrinsic variations among the data models. In this research, I describe a unified scenario database to allow interoperability and reuse of the scenario data components while avoiding the problems of data redundancy. Using the object oriented approach, the data and schema of the scenario databases, represented in an object oriented model, are integrated into a global database also represented …

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Dual Channel Matched Filtering And Space-Time Adaptive Processing, Scott D. Berger Jun 1999

Dual Channel Matched Filtering And Space-Time Adaptive Processing, Scott D. Berger

Theses and Dissertations

We propose a dual channel matched filtering system that addresses two key challenges in the practical implementation of a single channel matched filtering system: secondary data support and computational cost. We demonstrated that the dual channel system requires half the secondary data to achieve nearly the same signal-to-interference plus noise ratio (SINR) as an equivalent single channel system. The key to the dual channel system is the block diagonalization of the interference plus noise correlation matrix with a fixed transformation. We investigated the application of this dual channel concept to the problem of space-time adaptive processing (STAP), referring to the …

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Estimation And Goodness-Of-Fit In The Case Of Randomly Censored Lifetime Data, David M. Reineke Jun 1999

Estimation And Goodness-Of-Fit In The Case Of Randomly Censored Lifetime Data, David M. Reineke

Theses and Dissertations

A new continuous distribution function estimator for randomly censored data is developed, discussed, and compared to existing estimators. Minimum distance estimation is shown to be effective in estimating Weibull location parameters when random censoring is present. A method of estimating all 3 parameters of the 3-parameter Weibull distribution using a combination of minimum distance and maximum likelihood is also given. Cramer-von Mises and Anderson-Darling goodness-of-fit test statistics are modified to measure the discrepancy between the maximum likelihood estimate and the Kaplan-Meier product-limit estimate of the distribution function of the random variable of interest. These modified test statistics are used to …

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Evolving Compact Decision Rule Sets, Robert E. Marmelstein Jun 1999

Evolving Compact Decision Rule Sets, Robert E. Marmelstein

Theses and Dissertations

While data mining technology holds the promise of automatically extracting useful patterns (such as decision rules) from data, this potential has yet to be realized. One of the major technical impediments is that the current generation of data mining tools produce decision rule sets that are very accurate, but extremely complex and difficult to interpret. As a result, there is a clear need for methods that yield decision rule sets that are both accurate and compact. The development of the Genetic Rule and Classifier Construction Environment (GRaCCE) is proposed as an alternative to existing decision rule induction (DRI) algorithms. GRaCCE …

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Multiobjective Evolutionary Algorithms: Classifications, Analyses, And New Innovations, David A. Van Veldhuizen Jun 1999

Multiobjective Evolutionary Algorithms: Classifications, Analyses, And New Innovations, David A. Van Veldhuizen

Theses and Dissertations

This research organizes, presents, and analyzes contemporary Multiobjective Evolutionary Algorithm (MOEA) research and associated Multiobjective Optimization Problems (MOPs). Using a consistent MOEA terminology and notation, each cited MOEAs' key factors are presented in tabular form for ease of MOEA identification and selection. A detailed quantitative and qualitative MOEA analysis is presented, providing a basis for conclusions about various MOEA-related issues. The traditional notion of building blocks is extended to the MOP domain in an effort to develop more effective and efficient MOEAs. Additionally, the MOEA community's limited test suites contain various functions whose origins and rationale for use are often …

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Implementation Of A Two-Dimensional Hydrodynamic Shock Code Based Upon The Weighted Average Flux Method, Mark P. Wittig Jun 1999

Implementation Of A Two-Dimensional Hydrodynamic Shock Code Based Upon The Weighted Average Flux Method, Mark P. Wittig

Theses and Dissertations

Numerical modeling of shock propagation and reflection is of interest to the Department of Defense (DoD). Propriety state-of-the-art codes based upon E. F. Toro's weighted average flux (WAF) method are being used to investigate complex shock reflection phenomena. Here we develop, test, and validate a one-dimensional hydrodynamic shock code. We apply WAF to Gudonov's first-order upwind method to achieve second-order accuracy. Oscillations, typical of second-order methods, are then removed using adaptive weight limiter functions based upon total variation diminishing (TVD) flux limiters. An adaptive Riemann solver routine is also implemented to improve computational efficiency. This one-dimensional code is then extended …

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Parallel Digital Signal Processing On A Network Of Personal Computers Case Study: Space-Time Adaptive Processing, Fernando Silva Jun 1999

Parallel Digital Signal Processing On A Network Of Personal Computers Case Study: Space-Time Adaptive Processing, Fernando Silva

Theses and Dissertations

Network based parallel computing using personal computers is currently a popular choice for concurrent scientific computing. This work evaluates the capabilities and the performance of the AFIT Bimodal Cluster (ABC); a heterogeneous cluster of PCs connected by switched fast Ethernet and using MPICH 1.1 for interprocess communication for parallel digital signal processing using Space Time Adaptive Processing (STAP) as the case study. The MITRE RT_STAP Benchmark version 1.1 is ported and executed on the ABC, as well as on a cluster of six Sun SPARC workstations connected by a Myrinet network (the AFIT NOW), and on a IBM SP for …

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Cobol Reengineering Using The Parameter Based Object Identification (Pboi) Methodology, Sonia De Jesus Rodrigues Jun 1999

Cobol Reengineering Using The Parameter Based Object Identification (Pboi) Methodology, Sonia De Jesus Rodrigues

Theses and Dissertations

This research focuses on how to reengineer Cobol legacy systems into object oriented systems using Sward's Parameter Based Object Identification (PBOI) methodology. The method is based on relating categories of imperative subprograms to classes written in object oriented language based on how parameters are handled and shared among them. The input language of PBOI is a canonical form called the generic imperative model (GIM), which is an abstract syntax tree (AST) representation of a simple imperative programming language. The output is another AST, the generic object model (GOM), a generic object oriented language. Conventional languages must be translated into the …

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Bistatic Radar Cross Section (Rcs) Characterization Of Complex Objects, Robert L. Eigel Jr. Jun 1999

Bistatic Radar Cross Section (Rcs) Characterization Of Complex Objects, Robert L. Eigel Jr.

Theses and Dissertations

This research addresses some phenomenological aspects of bistatic scattering from a complex object with an emphasis on specular, shadowing, dihedral, and cavity effects. Five targets are investigated for their simplicity and ability to highlight certain scattering phenomena. Direct measurements of scattered electromagnetic energy and simulation data is gathered for a frequency bandwidth of 6-18 GHz. Both ray tracing and scattering center approaches are used to describe the bistatic mechanisms. An appraisal of the effectiveness and utility of the monostatic-to-bistatic equivalence theorems (Kell's and Crispin's) and several commercial scattering prediction codes is also accomplished. Simulation data is generated from two different …

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Positive Anisotropic Group Scattering Cross Sections For Radiation Transport, J. Mark Delgrande May 1999

Positive Anisotropic Group Scattering Cross Sections For Radiation Transport, J. Mark Delgrande

Theses and Dissertations

In solving the Boltzmann transport equation, most discrete ordinates codes calculate the source term by first approximating the scattering cross section using a Legendre polynomial expansion. Such expansions are insufficient when scattering is anisotropic and the Legendre expansion is truncated prematurely. This can lead to nonphysical negative cross sections, negative source terms and negative angular fluxes. While negative sources are problematic for standard discrete ordinates methods leading to poor convergence or convergence to incorrect results, they are of particular concern to exponential methods, causing such calculations to fail. We've developed and tested a new technique to solve this problem called …

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Image Fusion Using Autoassociative-Heteroassociative Neural Networks, Claudia V. Kropas-Hughes May 1999

Image Fusion Using Autoassociative-Heteroassociative Neural Networks, Claudia V. Kropas-Hughes

Theses and Dissertations

Images are easily recognized, classified, and segmented; in short, analyzed by humans. The human brain/nervous system; the biological computer, performs rapid and accurate image processing. In the current research the concepts of the biological neural system provide the impetus for developing a computational means of fusing image data. Accomplishing this automatic image processing requires features be extracted from each image data set, and the information content fused. Biologically inspired computational models are examined for extracting features by transformations such as Fourier, Gabor, and wavelets, and for processing and fusing the information from multiple images through evaluation of autoassociative neural networks …

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Close Formation Flight Control, Andrew W. Proud May 1999

Close Formation Flight Control, Andrew W. Proud

Theses and Dissertations

In this research the close formation flight control problem is addressed. The formation consists of a lead and wing aircraft, where the wing flies in close formation with the lead, such that the lead's vortices produce aerodynamic coupling effects, and a reduction in the formation's drag is achieved. A controller, i.e., a formation-hold autopilot for the wing aircraft, is designed such that the formation's geometry is maintained in the face of lead aircraft maneuvers. In the formation flight control system, the wing and lead aircraft dynamics are coupled due to kinematic effects, and, in the case of close formations, additional …

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