Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

2002

Air Force Institute of Technology

Discipline
Keyword
Publication
Publication Type

Articles 31 - 60 of 105

Full-Text Articles in Engineering

Suppression Of Pilot-Induced Oscillation (Pio), Donald A. Johnson Mar 2002

Suppression Of Pilot-Induced Oscillation (Pio), Donald A. Johnson

Theses and Dissertations

Closed loop instability caused by excess phase lag induced by actuator rate limiting has been suspected in many pilot-induced oscillations (PIOs) and oscillatory departures from controlled flight. As part of the joint AFIT/TPS program, a longitudinal pilot command notch filter activated by a real-time oscillation verifier (ROVER) algorithm was developed to eliminate the PIO source for any developing, severe PIO. Closed loop computer simulations were conducted to prepare for the flight test. The HAVE ROVER flight test project was flown using the NF-16D Variable Stability In-flight Simulator Test Aircraft (VISTA). A programmable heads-up display (HUD) was used to generate a …

Go to article

Examination Of Contact Width On Fretting Fatigue, Russell S. Magaziner Mar 2002

Examination Of Contact Width On Fretting Fatigue, Russell S. Magaziner

Theses and Dissertations

The primary goal of this study was to find the effects on the fretting fatigue life when systematically holding the fretting fatigue variables, peak contact pressure, maximum/minimum nominal bulk stress, and the ratio of shear traction to pressure force constant while varying the contact semi-width through changes in pad radius and normal load. Experimental tests were performed on a test setup capable of independent pad displacement. Analytical and finite element simulations of the different experimental tests were performed. The local mechanistic parameters were inspected. Five different critical plane based fatigue predictive parameters lacked effectiveness in predicting changes in life with …

Go to article

How Can The Air Force Maximize The Value Of Reverse Auctioning As A Pricing Technique?, Cynthia L. Marion-Mullins Mar 2002

How Can The Air Force Maximize The Value Of Reverse Auctioning As A Pricing Technique?, Cynthia L. Marion-Mullins

Theses and Dissertations

This research examines the pricing tool reverse auctioning. In a reverse auction buyers state the item they wish to buy and the sellers compete with each other for the sale, driving the price steadily down until no seller is willing to go any lower. Darleen A. Druyun, Principal Deputy Assistant Secretary of the Air Force for Acquisition and Management, Washington, D.C., launched the Air Force acquisition reform "Lightning Bolts" initiatives. These initiatives jump-start acquisition reform to find processes leading towards a better, faster, and cheaper way of conducting business. A reverse auction is one of these processes. A review of …

Go to article

An Evaluation Of Public And Private Sector Housing Alternatives For Military Families, Lawrence P. Kokocha Jr. Mar 2002

An Evaluation Of Public And Private Sector Housing Alternatives For Military Families, Lawrence P. Kokocha Jr.

Theses and Dissertations

This study explored the three primary housing alternatives along with their associated benefits and costs for military members at Robins Air Force Base. Using a case study methodology, qualitative and quantitative data were collected from contract documents, cost records, statements and testimonies to Congress, literature, census data, and interviews with civil engineering, contracting, financial management and legal professionals. This data was analyzed to determine which housing alternative seems to provide the best benefits at the lowest costs for military members and the government. The results of the study indicated that private sector alternatives are less expensive than government provided housing. …

Go to article

The Analysis Of Sophisticated Direction Of Arrival Estimation Methods In Passive Coherent Locators, Ahmet Ozcetin Mar 2002

The Analysis Of Sophisticated Direction Of Arrival Estimation Methods In Passive Coherent Locators, Ahmet Ozcetin

Theses and Dissertations

In passive coherent locators (PCL) systems, noise and the precision of direction of arrival (DOA) estimation are key issues. This thesis addresses the implementation of sophisticated DOA estimation methods, in particular the multiple signal classification (MUSIC) algorithm, the conventional beam forming (CBF) algorithm, and the algebraic constant modulus algorithm (ACMA). The goal is to compare the ACMA to the MUSIC, and CBF algorithms for application to PCL. The results and analysis presented here support the use of constant modulus information, where available, as an important addition to DOA estimation. The ACMA offers many simple solutions to noise and separation related …

Go to article

Robust Sensitivity Analysis For Multi-Attribute Deterministic Hierarchical Value Models, Yucel R. Kahraman Mar 2002

Robust Sensitivity Analysis For Multi-Attribute Deterministic Hierarchical Value Models, Yucel R. Kahraman

Theses and Dissertations

The Air Force's ability to deploy, employ, and sustain operations in forward locations is a key to mission success. An integral part of this strategy is equipment pre-positioning, to include: vehicles, aircraft support, consumable inventory, and munitions. This research focuses on defining and developing a model to aid decision makers with the afloat pre-positioning and deployment of munitions in an effort to ensure that the right weapons are available when, and where needed. This research places a particular focus on the strategic, global pre-positioning of the Afloat Pre-positioning Fleet (APF) in an effort to minimize the overall response time involved …

Go to article

Investigation Of Cooperative Behavior In Autonomous Wide Search Munitions, Robert E. Dunkel Iii Mar 2002

Investigation Of Cooperative Behavior In Autonomous Wide Search Munitions, Robert E. Dunkel Iii

Theses and Dissertations

The purpose of this research is to investigate the effectiveness of wide-area search munitions in various scenarios using different cooperative behavior algorithms. The general scenario involves multiple autonomous munitions searching for an unknown number of targets of different priority in unknown locations. Three cooperative behavior algorithms are used in each scenario: no cooperation, cooperative attack only, and cooperative classification and attack. In the cooperative cases, the munitions allocate tasks on-line as a group, using linear programming techniques to determine the optimum allocation. Each munition provides inputs to the task allocation routine in the form of probabilities of successfully being able …

Go to article

Space Time Adaptive Processing And Clutter Classification Integration And Evaluation, Nathan A. Jensen Mar 2002

Space Time Adaptive Processing And Clutter Classification Integration And Evaluation, Nathan A. Jensen

Theses and Dissertations

Radar is a fundamental technology in today's military and civilian environment, and continuing development of this technology is of utmost importance to maintaining technological advantages this realm. Current radar technologies suffer from jamming and clutter limitations. STAP is a statistical method to remove this noise, however it is extremely computationally intensive, and presents several real time processing hurdles. Clutter Classification is another method to classify the radar returns that are found according to the best fit statistical distribution that the return follows. This research investigation attempts to use this clutter classification technology to aid in the detection of targets by …

Go to article

Ambiguity Function Analysis And Direct-Path Signal Filtering Of The Digital Audio Broadcast (Dab) Waveform For Passive Coherent Location (Pcl), Abdulkadir Guner Mar 2002

Ambiguity Function Analysis And Direct-Path Signal Filtering Of The Digital Audio Broadcast (Dab) Waveform For Passive Coherent Location (Pcl), Abdulkadir Guner

Theses and Dissertations

This research presents an ambiguity function analysis of the digital audio broadcast (DAB) waveform and one signal detection approach based on signal space projection techniques that effectively filters the direct-path signal from the receiver target channel. Currently, most Passive Coherent Location (PCL) research efforts are focused and based on frequency modulated (FM) radio broadcasts and analog television (TV) waveforms. One active area of PCL research includes the search for new waveforms of opportunity that can be exploited for PCL applications. As considered for this research, one possible waveform of opportunity is the European digital radio standard DAB. For this research, …

Go to article

Wavelet Domain Communication System (Wdcs): Packet-Based Wavelet Spectral Estimation And M-Ary Signaling, Marion Jay F. Lee Mar 2002

Wavelet Domain Communication System (Wdcs): Packet-Based Wavelet Spectral Estimation And M-Ary Signaling, Marion Jay F. Lee

Theses and Dissertations

A recently proposed Wavelet Domain Communication System (WDCS) using transform domain processing demonstrated excellent interference avoidance capability under adverse environmental conditions. This work extends previous results by: 1) incorporating a wavelet packet decomposition technique, 2) demonstrating M-Ary signaling capability, and 3) providing increased adaptivity over a larger class of interference signals. The newly proposed packet-based WDCS is modeled and its performance characterized using MATLAB®. In addition, the WDCS response to two scenarios simulating Doppler effects and physical separation of transceivers are obtained. The fundamental metric for analysis and performance evaluation is bit error rate (Pb). Relative to …

Go to article

An Evaluation Of The Hazard Prediction And Assessment Capability (Hpac) Software's Ability To Model The Chornobyl Accident, Dirk E. Plante Mar 2002

An Evaluation Of The Hazard Prediction And Assessment Capability (Hpac) Software's Ability To Model The Chornobyl Accident, Dirk E. Plante

Theses and Dissertations

A parameter study was conducted for a space nuclear reactor radiation shield. The focus of this research was to explore alternatives to current radiation shield designs to reduce the mass while maintaining the same shielding performance. MCNP4C was used to determine the parameters necessary to build an optimum shield. A design known as the split scatter shield offered some potential for reductions in shield mass. In theory, less material is required for this type of shield, which uses thin shield sections to scatter radiation away from the dose plane. The parameters for this shield design are the shield geometry, number …

Go to article

Estimating Engineering Cost Risk Using Logistic And Multiple Regression, Vincent P. Sipple Mar 2002

Estimating Engineering Cost Risk Using Logistic And Multiple Regression, Vincent P. Sipple

Theses and Dissertations

This study explores a two-step procedure for assessing defense acquisition program cost growth using historical data. Specifically, we seek to predict whether a program will experience cost growth and, if applicable, how much costs will increase. We compile programmatic data from the Selected Acquisition Reports (SARs) between 1990 and 2000 for programs from all defense departments. We focus our analysis on cost growth in research and development dollars for the Engineering Manufacturing Development phase of acquisition. We further limit our study to only one of the seven SAR categories of cost growth engineering cost growth. We explore the use of …

Go to article

Admissions Criteria And Academic Performance In The Afit Graduate Cost Analysis Program, Kenneth R. Garwood Mar 2002

Admissions Criteria And Academic Performance In The Afit Graduate Cost Analysis Program, Kenneth R. Garwood

Theses and Dissertations

This research examined the admissions criteria used by the Air Force Institute of Technology (AFIT) to determine academic eligibility for the in-residence Graduate Cost Analysis (GCA) master's degree program. Using the cumulative graduate grade point average earned at AFIT as the measure of academic performance, comparisons were made between the predictive capability of the current criteria and other potential factors. Factors considered included scores from the Graduate Record Examination (GRE) and the Graduate Management Admissions Test (GMAT), undergraduate cumulative and math grade point averages, applicant's age and gender, ratings of the undergraduate school's admissions competitiveness, undergraduate degree type, and various …

Go to article

Evaluation Of Civil Engineering Operations Flight Competitive Sourcing Standards And Metrics, Ty A. Randall Mar 2002

Evaluation Of Civil Engineering Operations Flight Competitive Sourcing Standards And Metrics, Ty A. Randall

Theses and Dissertations

The Performance Work Statement (PWS), which defines the requirements and shapes the outcome of the activity under contract, and the Quality Assurance Surveillance Plan (QASP), which is vital in identifying what is to be evaluated, become critical documents as the Air Force enters into more competitive sourcing contracts. Currently, contractors and Most Efficient Organizations (MEO) are evaluated by the QASP based upon the requirements found in the PWS. It is imperative the PWS and QASP documents have adequate performance metrics and that they are applied appropriately to evaluate the contractor or MEO. This research collected PWS and QASP documents from …

Go to article

Performance Tradeoff Study Of A Gps-Aided Ins For A Rocket Trajectory, Muhittin Istanbulluoglu Mar 2002

Performance Tradeoff Study Of A Gps-Aided Ins For A Rocket Trajectory, Muhittin Istanbulluoglu

Theses and Dissertations

The Turkish Air Force (TuAF) has started a project to launch a satellite using only Turkish resources. Primary motivation behind this research is to assist TuAF's project by keeping up with these innovations in the navigational arena. The basic challenge in navigation system design is to decide which navigation system (or systems) and implementation techniques will be used, depending on accuracy requirements. The two primary navigation systems that will be integrated in this research are the Inertial Navigation System (INS), and the Global Positioning System (GPS). The Kalman filter algorithm is used to integrate INS and GPS. The rocket (Atlas …

Go to article

An Integrated Architecture And Feature Selection Algorithm For Radial Basis Neural Networks, Timothy D. Flietstra Mar 2002

An Integrated Architecture And Feature Selection Algorithm For Radial Basis Neural Networks, Timothy D. Flietstra

Theses and Dissertations

There are two basic ways to control an Unmanned Combat Aerial Vehicle (UCAV) as it searches for targets: allow the UCAV to act autonomously or employ man-in-the-loop control. There are also two target sets of interest: fixed or mobile targets. This research focuses on UCAV-based targeting of mobile targets using man-in-the-loop control. In particular, the interest is in how levels of satellite signal latency or signal degradation affect the ability to accurately track, target, and attack mobile targets. This research establishes a weapon effectiveness model assessing targeting inaccuracies as a function of signal latency and/or signal degradation. The research involved …

Go to article

An Interactive Decision Support System For Scheduling Fighter Pilot Training, Cuong T. Nguyen Mar 2002

An Interactive Decision Support System For Scheduling Fighter Pilot Training, Cuong T. Nguyen

Theses and Dissertations

The U.S. Air Force is developing Modular Aircraft Support System (MASS) program to replace the current Aerospace Ground Equipment (AGE). AGE supplies electricity, nitrogen, hydraulics and other support equipment to maintenance activities at the flight line. Current AGE makes up one-third of the deployment footprint. AGE is also mostly aircraft specific, and has reliability problems. The MASS alternative focuses on modularity based on a plug-and-play approach. The technological improvements and possible reduction in the footprint make MASS a good alternative. The AF has to determine now, whether MASS can supply similar functionality and decrease the deployment footprint to theater, while …

Go to article

Spectrum Management And The Global Positioning System: A Case Study In Interagency Coordination, John A. Enis Mar 2002

Spectrum Management And The Global Positioning System: A Case Study In Interagency Coordination, John A. Enis

Theses and Dissertations

At the 2000 World Radio Conference (WRC), a European initiative resulted in the approval of resolutions 605 and 606 (agenda item 1.15), which the United States opposed. These resolutions established provisional power flux density (PFD) limits on the L2 and L5 frequencies of the Global Positioning System. These limits will negatively affect the $1.2B GPS modernization. The United States will have to present its positions and rationale regarding the PFD limits to international meetings, including the 2003 World Radio Conference, to persuade the international community to adopt that U.S. view. Developing the U.S. view and conducting the supporting technical work …

Go to article

A System Dynamics Approach To Modeling Aircraft System Production Break Costs, John J. Dubelko Mar 2002

A System Dynamics Approach To Modeling Aircraft System Production Break Costs, John J. Dubelko

Theses and Dissertations

This research effort employs a System Dynamics methodology to model Air Force aircraft production break costs. The Air Force currently used the Anderlohr, Modified Anderlohr, and Retrograde methods for the estimation of aircraft production breaks. These methods offer little insight into the dynamic behavior of an aircraft production break. System Dynamics offers a unique way of capturing expert opinions in this area and dynamically presenting behaviors of an Air Force aircraft production line during a production break. Development of this model followed a four-step process of conceptualization, formulation, testing, and implementation. Five Air Force aircraft production break experts in were …

Go to article

The Management Of Energy Savings Performance Contracts (Espcs), Ericka M. Dailey Mar 2002

The Management Of Energy Savings Performance Contracts (Espcs), Ericka M. Dailey

Theses and Dissertations

Energy Savings Performance Contracts (ESPCs) originated to accomplish several objectives: (1) to meet energy efficiency goals mandated by executive orders and energy policies; (2) to improve federal government facilities using funds allocated for utility bills; and (3) to receive repayment of expenditures through energy savings reflected in reduced utility bills. In ESPC's, the contractor guarantees savings to the federal government agency. 10 CFR 436 limits the time necessary for payback. However, this regulation and others were written prior to the deregulation of utility companies. This theory is based on the underlying premise that the contractor payback is a direct result …

Go to article

An Analysis Of The Knowledge And Skill Levels Required To Effectively Support Analytical Cost Decisions In Source Selections, Anthony L. Smith Mar 2002

An Analysis Of The Knowledge And Skill Levels Required To Effectively Support Analytical Cost Decisions In Source Selections, Anthony L. Smith

Theses and Dissertations

We analyze these three factors (education, experience, and training) in an effort to identify the knowledge and skills necessary for cost analysts to possess to be effective members of cost panel evaluation teams during source selections. This research effort assesses whether the cost panel members and senior Air Force acquisition military and civilian personnel associate the levels of education, experience, and training as being key factors in fulfilling cost analysts duties while supporting the selection of a source in the government procurement process. To accomplish this objective, a literature review, personal interviews, and questionnaires were utilized. Descriptive statistics and hypothesis …

Go to article

Groundwater Flow Through A Constructed Treatment Wetland, Andrew C. Entingh Mar 2002

Groundwater Flow Through A Constructed Treatment Wetland, Andrew C. Entingh

Theses and Dissertations

This study examines the flow of groundwater through one of the treatment cells. A major goal of the study is to determine whether the system design facilitates uniform vertical flows through the subsurface soil sediments or if preferential flows occur. Conceptually, uniform flows will achieve the most efficient degree of contaminant removal possible by evenly dispersing the groundwater contaminants throughout the full volume of the subsurface media. A three-dimensional grid of piezometers is used to generate potentiometric contour maps, and in-situ tests of hydraulic conductivity facilitate construction of a numerical computer model. The contours of hydraulic head, measured conductivities, and …

Go to article

An Evaluation Of Geobest Contingency Beddown Planning Software Using The Technology Acceptance Model, Shawn J. Jensen Mar 2002

An Evaluation Of Geobest Contingency Beddown Planning Software Using The Technology Acceptance Model, Shawn J. Jensen

Theses and Dissertations

GeoBEST is a software program designed to simplify the contingency beddown planning process through application of geographic information technology. The purpose of this thesis was to thoroughly evaluate GeoBEST using prospective GeoBEST users in a realistic beddown planning scenario. The Technology Acceptance Model (TAM) was applied, which measures a prospective user's perceptions of the technology's usefulness and ease-of-use and predicts their intentions to use the software in the future. The evaluations also included a qualitative evaluation of specific software features. The test group for this thesis was seventy-one Civil Engineering students attending contingency skills training at the Silver Flag training …

Go to article

Hexavalent Chromium Dissociation From Overspray Particles Into Fluid For Three Aircraft Primers, Richard A. Schilke Mar 2002

Hexavalent Chromium Dissociation From Overspray Particles Into Fluid For Three Aircraft Primers, Richard A. Schilke

Theses and Dissertations

DOD and industry use chromate-containing primers extensively to inhibit corrosion on metal assets. Chromate contains Cr6+, a human carcinogen, but there is little epidemiological evidence of increased lung cancer among spray painters. Using bio-aerosol impingers, overspray particles from three primers (solvent-borne epoxy, water-borne epoxy, and solvent-borne polyurethane) were collected into water to test the hypothesis that the paint matrix inhibits Cr6+ release into water, under the premise that this simulates Cr6+ release from particles into lung fluid. Particles were allowed to reside in water for 1 or 24 hours, then separated from the water by centrifugation, …

Go to article

A Direct Sequence Code-Division Multiple-Access Local Area Network Model, James R. Rapallo Jr. Mar 2002

A Direct Sequence Code-Division Multiple-Access Local Area Network Model, James R. Rapallo Jr.

Theses and Dissertations

The United States Air Force relies heavily on computer networks for every-day operations. The medium access control (MAC) protocol currently used by most local area (LAN) permits a single station to access the network at a time (e.g. CSMA/CD or Ethernet). This limits network throughput to, at most, the maximum transmission rate of a single node with overhead neglected. Significant delays are observed when a LAN is overloaded by multiple users attempting to access the common medium. In CSMA/CD, collisions are detected and the data sent by the nodes involved are delayed and transmitted at a later time. The retransmission …

Go to article

Statistical Error Analysis Of A Doa Estimator For A Pcl System Using The Cramer-Rao Bound Theorem, Kerim Say Mar 2002

Statistical Error Analysis Of A Doa Estimator For A Pcl System Using The Cramer-Rao Bound Theorem, Kerim Say

Theses and Dissertations

Direction of Arrival (DOA) estimation of signals has been a popular research area in Signal Processing. DOA estimation also has a significant role in the object location process of Passive Coherent Location (PCL) systems. PCL systems have been in open literature since 1986 and their applications are not as clearly understood as the DOA estimation problem. However, they are the focus of many current research efforts and show much promise. The purpose of this research is to analyze the DOA estimation errors in a PCL system. The performance of DOA estimators is studied using the Cramer-Rao Bound (CRB) Theorem. The …

Go to article

Using The Gps To Collect Trajectory Data For Ejection Seat Design, Validation, And Testing, Brian R. Tredway Mar 2002

Using The Gps To Collect Trajectory Data For Ejection Seat Design, Validation, And Testing, Brian R. Tredway

Theses and Dissertations

The dynamic characteristics of an aircraft ejection seat are a crucial concern when evaluating aircraft ejection systems and their ability to separate aircrew members safely from disabled aircraft. Every ejection seat model undergoes real-time dynamic tests to determine potential injury to aircrew members during ejection. Ejection seat tests are conducted at high-speed test tracks. The test track facilities provide the required telemetry and high-speed photography to monitor and validate the aircraft escape system performance. Ejection seat test and evaluation requires very accurate position and velocity determination during each test run to determine the relative positions between the aircraft, ejection seat, …

Go to article

Microdot - A Four-Bit Microcontroller Designed For Distributed Low-End Computing In Satellites, Anthony R. Woodcock Mar 2002

Microdot - A Four-Bit Microcontroller Designed For Distributed Low-End Computing In Satellites, Anthony R. Woodcock

Theses and Dissertations

Many satellites are an integrated collection of sensors and actuators that require dedicated real-time control. For single processor systems, additional sensors require an increase in computing power and speed to provide the multi-tasking capability needed to service each sensor. Faster processors cost more and consume more power, which taxes a satellite's power resources and may lead to shorter satellite lifetimes. An alternative design approach is a distributed network of small and low power microcontrollers designed for space that handle the computing requirements of each individual sensor and actuator. The design of microdot, a four-bit microcontroller for distributed low-end computing, is …

Go to article

Development And Characterization Of An Emergency Communications System Using Near Vertical Incident Skywave Antennas, Richard A. Allnutt Mar 2002

Development And Characterization Of An Emergency Communications System Using Near Vertical Incident Skywave Antennas, Richard A. Allnutt

Theses and Dissertations

The NVIS system characterized in this work was designed to eliminate skip propagation by optimizing the design for contiguous coverage. The NVIS technique involves use of transmission and receiving antennas that create nearly vertical propagation and continuous coverage from the transmitter to a distance of 200 miles. Man portable, very low power transceivers (5 watts maximum) and horizontal dipole antennas five feet above the ground are used in an NVIS communication system for this work. The system is designed for the purpose of supporting communication with emergency workers in areas where other communication is difficult. Digital and analog effectiveness are …

Go to article

Comparative Analysis Of Leasing Versus Buying General Purpose Vehicles (Sedan) In The Korean Air Force, Jung J. Kim Mar 2002

Comparative Analysis Of Leasing Versus Buying General Purpose Vehicles (Sedan) In The Korean Air Force, Jung J. Kim

Theses and Dissertations

Elmendorf Air Force Base (AFB) is one of the two key ERS airfields for the Pacific Theater. The condition of en route airfields has recently come to the attention of the DoD and the GAO. Delays at these airfields may cause personnel and equipment to arrive late in theater. Fuel systems at Elmendorf AFB are currently being improved, but the GAO questions whether these improvements will help the throughput. As well as being an en route airfield, Elmendorf is also an important Interim Brigade Combat Team (IBCT) APOE for Fort Richardson. The IBCT is designed to operate in small-scale contingency …

Go to article

First Prev Next Last