Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Physical Sciences and Mathematics (8798)
- Engineering (5209)
- Education (2939)
- Computer Sciences (2742)
- Chemistry (1408)
-
- Electrical and Computer Engineering (1204)
- Physics (1154)
- Social and Behavioral Sciences (1144)
- Aerospace Engineering (847)
- Life Sciences (839)
- Earth Sciences (835)
- Operations Research, Systems Engineering and Industrial Engineering (776)
- Mechanical Engineering (710)
- Geology (630)
- Arts and Humanities (618)
- Statistics and Probability (571)
- Psychology (557)
- Mathematics (548)
- Environmental Sciences (515)
- Business (504)
- Medicine and Health Sciences (460)
- Civil and Environmental Engineering (439)
- Operational Research (420)
- Computer Engineering (401)
- Oceanography and Atmospheric Sciences and Meteorology (374)
- Curriculum and Instruction (362)
- Educational Leadership (349)
- Applied Mathematics (324)
- Educational Administration and Supervision (317)
- Teacher Education and Professional Development (316)
- Institution
-
- Air Force Institute of Technology (4801)
- Brigham Young University (3515)
- University of North Dakota (2686)
- University of South Carolina (1982)
- Mississippi State University (1684)
-
- Rowan University (1561)
- Virginia Commonwealth University (1537)
- Florida Institute of Technology (786)
- University of Texas Rio Grande Valley (723)
- University of Arkansas Little Rock (631)
- University for Business and Technology in Kosovo (426)
- American University in Cairo (392)
- Illinois State University (381)
- Pepperdine University (339)
- St. John's University (292)
- Columbus State University (288)
- Nova Southeastern University (165)
- City University of New York (CUNY) (159)
- SASTRA Deemed to be University (94)
- Texas A&M International University (23)
- Seattle Pacific University (3)
- Utah State University (3)
- Keyword
-
- Education (262)
- Machine learning (257)
- #antcenter (234)
- Mathematics (153)
- Optimization (138)
-
- Deep learning (107)
- Simulation (103)
- Machine Learning (102)
- Dissertations (EdD) -- Organizational leadership (95)
- STEM (85)
- Physical Sciences and Mathematics, Chemistry (84)
- Technology (77)
- Algorithms (76)
- Geology (74)
- Remote sensing (74)
- Modeling (73)
- Artificial intelligence (72)
- Professional development (71)
- Computer vision (70)
- North Dakota (70)
- Self-efficacy (69)
- Image processing (67)
- Leadership (67)
- #csra (64)
- Academic achievement (62)
- Motivation (62)
- Education, Curriculum and Instruction (61)
- Pure sciences (61)
- Decision making (60)
- Chemistry (57)
- Publication Year
- File Type
Articles 20341 - 20370 of 22471
Full-Text Articles in Entire DC Network
Investigation Of The Effects Of Increased Order Compensators In Mixed H2/H∞ Optimization, Scott R. Wells
Investigation Of The Effects Of Increased Order Compensators In Mixed H2/H∞ Optimization, Scott R. Wells
Theses and Dissertations
The problem of minimizing the 2-norm of one transfer function subject to an infinity-norm bound on another transfer function is examined for increased order controllers. In particular, the theoretical results of the full order case are extended to the higher order case, and SISO and MIMO numerical examples are given for increasingly higher order compensators. Some of the key proofs for higher order compensators include: the global minimum 2-norm is unachievable under output feedback for certain levels of gamma regardless of compensator order; the solution to the mixed H2/H infinity problem lies on the boundary of the infinity-norm constraint for …
Ground Collision Avoidance Using A Variable Incidence Altitude Measurement System For The A-7 Aircraft, Thomas A. Hartung
Ground Collision Avoidance Using A Variable Incidence Altitude Measurement System For The A-7 Aircraft, Thomas A. Hartung
Theses and Dissertations
This study examines the use of a forward looking sensor in the implementation of an automatic terrain following system. The effect of the incidence angle is studied as well as methodologies to include dynamic motion in the pointing of the sensor beam. The methods examined include fixed angle with respect to the aircraft, dynamics driven by a simple gain, and dynamics directed to gather the terrain information a fixed time interval ahead of the aircraft. Incidence angles of 25, 50, 75, and 90 are examined. The terrain obstacles include a single parabolic hill, a step change is terrain, and a …
Effective Design Of Strategic Control Systems For Air Force Information Management: A Program Evaluation, B. Bruce Cowser
Effective Design Of Strategic Control Systems For Air Force Information Management: A Program Evaluation, B. Bruce Cowser
Theses and Dissertations
Strategic planning and implementation and strategic controls offer organizations powerful and essential tools for proactive management. In Information Management (IM), they hold the key to successfully navigating the current turbulent environment. This study was conducted in order to evaluate strategic controls in Air Force Information Management, and to recommend ways to improve them. A model for strategic controls was developed from the literature to serve as a standard for evaluating current programs. Interviews were conducted at three major commands to gather data on the current state of strategic controls. A qualitative analysis methodology was selected, and recommendations include the following …
Application Of Finite Element Modeling And Analysis To The Design Of Positive Pressure Oxygen Masks, Bruce H. Bitterman
Application Of Finite Element Modeling And Analysis To The Design Of Positive Pressure Oxygen Masks, Bruce H. Bitterman
Theses and Dissertations
This study investigated tools and techniques for performing finite element analysis of the MBU-20/P pilot's oxygen mask. The problem which was investigated was the fit of the mask to the face at Positive Pressure Breathing (PPB) pressures. Deformed geometry of the mask and reaction forces on the face were calculated to provide a measure of the fit. The MBU-20/P mask was first digitized by 3-D digitizer. A computer program was written to translate the digitized coordinate data to a finite element format for two commercial packages. The packages targeted were SDRC I-DEAS and PDA PATRAN. Other supplementary programs were written …
A Comparison Of Fractional Order Time Derivative Models Of The Viscoelastic Stress Relations In Thermorheologically Complex Materials, Victor B. Chambers
A Comparison Of Fractional Order Time Derivative Models Of The Viscoelastic Stress Relations In Thermorheologically Complex Materials, Victor B. Chambers
Theses and Dissertations
The purpose of this thesis was to examine the viscoelastic behavior of thermorheologically complex materials, a typical example of which is a soft, rubbery material. Materials such as these are very useful in damping vibrations in structures, but the relaxation moduli of these materials change significantly with temperature and frequency. In the case of space structures applications where temperatures vary greatly and a stable platform is necessary, a method to predict this changing modulus is needed. The original approach was to validate a previously developed viscoelastic model, but the task expanded to include extending the model to materials with two …
An Algorithm For Robust Eigenstructure Assignment Using The Linear Quadratic Regulator, Thomas C. Huckabone
An Algorithm For Robust Eigenstructure Assignment Using The Linear Quadratic Regulator, Thomas C. Huckabone
Theses and Dissertations
The Linear Quadratic Regulator (LQR) can guarantee a robust closed loop eigenstructure for full state feedback. The algorithm developed here takes advantage of the stability guarantees of LQR to achieve an eigenstructure close to desired but within the allowable region of LQR. The algorithm selects the LQR weighting matrices, Q and R, that minimize the distance between the elements of the desired and LQR achievable eigenstructures. The minimization is accomplished by using a simplex based optimization routine. Specific weightings placed on the elements of the desired eigenstructure define the relative importance of each element. The algorithm is programmed in FORTRAN …
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 …
Logic Programming In Digital Circuit Design, Joseph W. Eicher
Logic Programming In Digital Circuit Design, Joseph W. Eicher
Theses and Dissertations
The design of large, complex digital circuitry requires highly skilled engineers. Much of the time spent by these engineers in the design phase involves tasks that are repetitive, tedious, and slow. If these repetitive tasks are automated, the engineer can spend more time managing the design process and produce a better-quality design in less time. Logic programming can be used to automate design tasks, even those that require a high degree of skill. This thesis investigates several aspects of the digital circuit design process that involve pattern-matching paradigms suitable for encoding in the logic programming language Prolog.
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, …
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 …
An Investigation Of Optimally Robust Structural Damping Through Fractional Order Feedback, Mark T. Leonard
An Investigation Of Optimally Robust Structural Damping Through Fractional Order Feedback, Mark T. Leonard
Theses and Dissertations
The purpose of this investigation was to determine if introducing fractional order states in a feedback system was beneficial to overall system performance. Fractional order differential equations have been used in the past primarily to model viscoelastic damping in structures. this study examined the use of fractional order differential equations in formulating a control algorithm with additional degrees of freedom. The algorithm presented is best suited for active structural damping. Including the fractional order time derivatives in the state allowed some additional flexibility in choosing relevant control parameters in the system. Optimization with respect to robustness was examined to determine …
Propulsive Capability Of A Reel-In Tether With Safe Separation Between Payload And Orbiter, Jay H. Rothhaupt
Propulsive Capability Of A Reel-In Tether With Safe Separation Between Payload And Orbiter, Jay H. Rothhaupt
Theses and Dissertations
This study investigates the use of a massless reel-in tether for propulsion of a payload following deployment from an orbiter. The distance between the payload and orbiter at closest passage is addressed. A literature review revealed several tether concepts, extensive tether research, and numerous mathematical models. However, previous work in the area of reel-in tethers is limited to propulsion feasibility. The reel-in tether is operated following optimum ejection of the payload from the orbiter using a free arc and subsequent full arc. The free arc of zero tether tension provides initial separation. Switching to a full arc of continuously-maximum tension …
Investigation Of The Influence Of Rotary Aerodynamics On The Study Of High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Ralph D. Fero
Theses and Dissertations
The purpose of this research was to use bifurcation analysis to investigate the effectiveness of rotary balance data in the prediction of aircraft spin behavior as both a stand alone representation of a model's aerodynamic data and in a conventional hybrid model. using the foundation of a previously developed model of the F-15B, the rotary balance aerodynamic force and moment data were implemented as a function of angle of attack, angle of sideslip, non-dimensional rotation steady state rate and the control surface deflections. Bifurcation diagrams were developed as a function of alpha vs. deflection angles of, the rudder, stabilator, and …
Discrete Simulation Of Fractional Order Systems, Jeffrey A. Blank
Discrete Simulation Of Fractional Order Systems, Jeffrey A. Blank
Theses and Dissertations
Fractional calculus has been shown useful for describing many real world systems, and studies are currently underway to generalize control theory to incorporate fractional states. This investigation derives a method for simulating the time response of fractional order systems using a recursive difference equation. The technique used effectively approximates a simple fractional order integrator as a summation of integer order terms. The discrete transfer function is also derived and the frequency response of the discrete algorithm is compared to the exact continuous case. Using 20 or more retained past values in the difference equation, the discrete half-order integrator demonstrates a …
The Application Of Kriging For Controlled Minimization Of Large Data Sets, Christopher Brodkin
The Application Of Kriging For Controlled Minimization Of Large Data Sets, Christopher Brodkin
Theses and Dissertations
Frequently, the quantity of data available is much greater than that which can be manipulated in an efficient and timely manner. This can cause several problems. The first, and probably most critical, problem is the excessive on-line storage needs of these huge data sets. Secondly, in the computer animation field, huge data sets may require excessive computational time for generation of each frame of a computer animation. Thirdly, computer screens have a limited resolution and need too much computational time removing excessive detail from images generated with a higher resolution than can be displayed. Lastly, too much time is required …
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 …
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 …
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 …
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 …
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 …
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 Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde
An Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde
Theses and Dissertations
One of the most cost effective ways to learn and home the skills necessary to conduct and win a war is through the use of realistic computer simulations of conflict, or wargames. The Saber wargame was developed for just this purpose. Saber is a multisided, theater-level simulation developed by the Air Force Institute of Technology for the Air Force Wargaming Center. It models conventional, nuclear, and chemical warfare between aggregated air and ground forces. To aid in the realism, the effects of logistics, satellites, weather, and intelligence are represented. Saber provides an avenue for senior level joint service officers to …
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 …
Plasma Transport In A Magnetic Multicusp Negative Hydrogen Ion Source, Ricky G. Jones
Plasma Transport In A Magnetic Multicusp Negative Hydrogen Ion Source, Ricky G. Jones
Theses and Dissertations
An analysis of plasma transport through the magnetic filter in tandem magnetic multicusp negative hydrogen ion sources was conducted to determine the mechanism of thermal electron diffusion, explain thermal electron cooling, describe the transport of primary electrons through the filter, and model positive ion species transport. The thermal electron flux was shown to exceed its classical value by one to three orders of magnitude. The flux variation with temperature was best described using a Coulomb-like temperature gradient drag term, consistent with diffusion due to ion-sound-like turbulence. Thermal electron energy flux loss was shown to be dominated by inelastic collisions at …
High-Resolution Tvd Schemes For The Analysis Of 1. Inviscid Supersonic And Transonic Flows. 2. Viscous Flows With Shock-Induced Separation And Heat Transfer, Mark A. Driver
Theses and Dissertations
Application of TVD schemes to both inviscid and viscous flows is considered. The mathematical and physical bases of TVD schemes are discussed. First and second-order accurate TVD schemes and a second-order accurate Lax- Wendroff scheme are used to compute solutions to the Riemann problem in order to investigate the capability of each to resolve shocks, rarefactions, and contact surfaces. Second-order finite-volume and finite-difference TVD schemes are used to obtain solutions to inviscid supersonic and transonic cascade flow problems. TVD schemes are shown to be superior to the Lax-Wendroff family of schemes for both transient and steady-state computations. TVD methodology is …
Multi-Layered Feedforward Neural Networks For Image Segmentation, Gregory L. Tarr
Multi-Layered Feedforward Neural Networks For Image Segmentation, Gregory L. Tarr
Theses and Dissertations
Artificial neural network image segmentation techniques are examined. The biological inspired cortex transform is examined as a means to preprocess images for segmentation and classification. A generalized neural network formalism is presented as a means to produce common pattern recognition processing techniques in a single iterable element. Several feature reduction preprocessing techniques, based on feature saliency, Karhunen-Loeve transformation and identity networks are tested and compared. The generalized architecture is applied to a problem in image segmentation, a tracking of high- value fixed tactical targets. A generalized architecture for neural networks is developed based on the second order terms of the …
A Delphi Forecast Of 1996 Roles: Air Force Institute Of Technology Information Resource Management Graduates Assigned To Base Level, David O. Block
A Delphi Forecast Of 1996 Roles: Air Force Institute Of Technology Information Resource Management Graduates Assigned To Base Level, David O. Block
Theses and Dissertations
Graduates of the Air Force Institute of Technology's Information Resource Management master's degree program who are subsequently assigned to base-level positions believe their IRM expertise is wasted in base administration roles that preclude the use of their up-to-date technical educations in managing automated information resources. This research forecasts the role AFIT IRM graduates assigned to base-level positions will need to fill by the year 1996. The research further determined what changes are necessary to resolve the perceived differences between current and forecast roles for these graduates. The Delphi survey method of forecasting was selected as an effective method of discovering …
An Expert System For Measuring, Interpreting, And Managing System Performance Factors For The Work Information Management System, Billy J. C. Irwin
An Expert System For Measuring, Interpreting, And Managing System Performance Factors For The Work Information Management System, Billy J. C. Irwin
Theses and Dissertations
This study develops an expert system for measuring, interpreting, and managing the Wang VS operating system performance factors for the Work Information Management System. The system's performance concerns least known to system administrators are identified. Of these, SHARER buffers and VTOC cache are identified as factors that can significantly impact system performance with little effort. A six step process is used in developing the expert system. Concept maps representing the structure of the Wang VS Disk Input/Output problem domain are provided. The expert system provides information about the system parameters, SHARER buffers and VTOC cache, and recommends main memory allocations. …
An Analysis Of The Information Requirements Of Conus Based Deputy Commanders For Maintenance, Daniel J. Green
An Analysis Of The Information Requirements Of Conus Based Deputy Commanders For Maintenance, Daniel J. Green
Theses and Dissertations
The purpose of this research was to identify the information requirements of Air Force Deputy Commanders for Maintenance. It had three basic objectives: (1) identify the critical success factors that they monitor on a continuous basis, (2) identify similarities in those requirements for all DGMs and across major commands, and (3) determine if the application of information technology would enhance their decision making. Surveys were sent to all CONUS based Deputy Commanders for Maintenance. The study found that there were nine critical success factors that were used by a majority of all respondents. In addition, nine command-specific critical success factors …