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2001

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Articles 1111 - 1140 of 1795

Full-Text Articles in Engineering

Computational Investigation Of Aeromechanical Hcf Effects In A Compressor Rotor, Andrew L. White Mar 2001

Computational Investigation Of Aeromechanical Hcf Effects In A Compressor Rotor, Andrew L. White

Theses and Dissertations

High-Cycle Fatigue is a major problem facing the gas turbine industry today. It has been investigated by many researchers, using many different methods. Due to its highly complex nature, designers still do not have adequate tools to accurately predict the onset of high-cycle fatigue. A three-dimensional Navier-Stokes program was used to perform a study of the unsteady aerodynamics on a compressor rotor. The effect of aerodynamic detuning on the forced response of a rotor blade was compared to a baseline tuned rotor case. Detuning consisted of a ten percent decrease in circumferential spacing between alternate pairs of blades. The high-cycle …

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Microdot-A 4-Bit Synchronous Microcontroller For Space Applications, Kirby M. Watson Mar 2001

Microdot-A 4-Bit Synchronous Microcontroller For Space Applications, Kirby M. Watson

Theses and Dissertations

Satellites have limited power budgets due to the amount of power collected by the satellite's solar panels. The goal is to have a wide range of functionality, while running off a limited power source. Large microprocessors use large amounts of power to report back temperature and chemical sensor data to ground stations. By using small micro controllers to perform the data collection and minimizing the usage of the larger microprocessors, the satellites will save power. A prototype design of the Microdot 4-bit micro controller for space applications is presented. Requirements for the Microdot, such as microwatt power consumption and 23 …

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Identifying Demand Indicators For Air Force Recruiting Service With Discriminant Analysis, Jason L. Williams Mar 2001

Identifying Demand Indicators For Air Force Recruiting Service With Discriminant Analysis, Jason L. Williams

Theses and Dissertations

A changing public disposition towards military service has all four military branches rethinking recruiting practices. This Air Force is reacting to this new recruiting climate by increasing the bonuses for new recruits, pumping up advertising budgets, and bolstering recruiting personnel levels. This thesis provides a new tool for assessing how to allocate these new resources. Discriminant Analysis is used to identify population characteristics that categorize recruiting locations. A methodology is constructed that can discriminate between communities where interest is high in military service and where recruiting efforts will not be productive.

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Routing Unmanned Aerial Vehicles While Considering General Restricted Operating Zones, Darin T. Brown Mar 2001

Routing Unmanned Aerial Vehicles While Considering General Restricted Operating Zones, Darin T. Brown

Theses and Dissertations

U.S. military forces employ unmanned aerial vehicles (UAVs) to conduct intelligence-gathering missions worldwide. For a typical mission, commanders may task UAV operators to gather imagery on 100 or more sites or targets. UAV operators must quickly prepare mission plans that meet the needs of their commanders while dealing with real-world constraints such as time windows, site priorities, imagery requirements, UAVs with different capabilities (i.e. imagery equipment, speed, and range), and UAVs departing from different bases. Previous AFIT research provided the UAV Battlelab with a tool, AFIT Router, for generating high-quality routes to aid mission planning. This research enhances the AFIT …

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Image Registration Using Redundant Wavelet Transforms, Richard K. Brown Mar 2001

Image Registration Using Redundant Wavelet Transforms, Richard K. Brown

Theses and Dissertations

Imagery is collected much faster and in significantly greater quantities today compared to a few years ago. Accurate registration of this imagery is vital for comparing the similarities and differences between multiple images. Since human analysis is tedious and error prone for large data sets, we require an automatic, efficient, robust, and accurate method to register images. Wavelet transforms have proven useful for a variety of signal and image processing tasks, including image registration. In our research, we present a fundamentally new wavelet-based registration algorithm utilizing redundant transforms and a masking process to suppress the adverse effects of noise and …

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A Multi-Objective Decision Support Model For The Turkish Armed Forces Personnel Assignment System, Zubeyir Cimen Mar 2001

A Multi-Objective Decision Support Model For The Turkish Armed Forces Personnel Assignment System, Zubeyir Cimen

Theses and Dissertations

The Turkish Armed Forces (TAF) assign more than 25,000 active duty personnel annually. TAF wants to obtain maximum utilization of its personnel by assigning the right person to the right job at the right time, To accomplish this task, decision-makers and personnel assignment staff should consider conflicting multiple objectives that create the widely known problem called "personnel assignment problem". To assist in this complicated task from a quantitative perspective, a preemptive goal programming approach was used to develop an integer programming (IP) model to capture the multiple objectives flexibly and interactively. A realistic size IP problem with random data was …

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An Identification And Discussion Of Key Success Factors In The Acquisition Of Commercial-Off-The-Shelf (Cots-) Based Systems, John F. Corbett Mar 2001

An Identification And Discussion Of Key Success Factors In The Acquisition Of Commercial-Off-The-Shelf (Cots-) Based Systems, John F. Corbett

Theses and Dissertations

The purpose of this research was to explore COTS-based systems as they are acquired by the Air Force. Current guidance related to the acquisition of COTS-based systems is explored. Based upon the literature reviewed, the research targeted the specific area of acquisition plans. A multiple case study of acquisition plans from several COTS-based systems was performed. Current guidance related to the acquisition plan has not been specifically tailored to COTS-based systems. The results of the analysis of the COTS-based systems showed that the use total ownership cost (TOC) and cost as an independent variable (CAIV) enabled a system to he …

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An Analysis Of Civil Engineer Officer Contingency Training, Rusty J. Vaira Mar 2001

An Analysis Of Civil Engineer Officer Contingency Training, Rusty J. Vaira

Theses and Dissertations

The primary objective of this research was to investigate the current overall civil engineer officer contingency training program and determine if civil engineer officers think it is adequately preparing them to perform in a contingency environment. In accomplishing this objective, this research explored the perceptions that officers have about the contingency training that is available through three primary training programs (Home Station Training, Silver Flag training, and Civil Engineer and Services School training). The overall intent of the author was to gauge how the officers feel about their contingency training and offer some suggestions on how to improve the training. …

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Assessment Of The Effects Of Entrainment And Wind Shear On Nuclear Cloud Rise Modeling, Daniel E. Zalewski Mar 2001

Assessment Of The Effects Of Entrainment And Wind Shear On Nuclear Cloud Rise Modeling, Daniel E. Zalewski

Theses and Dissertations

The Missile Defense Agency (MDA) plans to construct, during a two-week period, an X-Band Radar (XBR) on Shemya, AK. Wind speeds must not, at any time during the construction, exceed a 25 knot limit set by the MDA for lifting the massive dome panels into place. The goal of this research was to explore the possibilities of long-range forecasts to determine the feasibility of predicting any upcoming two-week windows of opportunity, well in advance, that will ensure the successful completion of constructing the XBR on Shemya. In order to reach this goal, the following objectives were achieved; (1) a climatological …

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Fatigue Response Of Thin Stiffened Aluminum Cracked Panels Repaired With Bonded Composite Patches, Jason B. Avram Mar 2001

Fatigue Response Of Thin Stiffened Aluminum Cracked Panels Repaired With Bonded Composite Patches, Jason B. Avram

Theses and Dissertations

This research investigated the fatigue response of precracked and patched 2024-T3 Aluminum panels with stiffeners. Patches were single-sided, unidirectional three ply boron/epoxy. Stiffeners were 2024-T3 aluminum and were riveted and bonded on. Disbonds were introduced into the repair bondline by inserting teflon strips. Three disbond configurations were investigated rack tip disbond (CTD) located at the edge of the patch in the path of crack propagation, full-width disbond (FWD) covering the entire crack, and end disbond (ED) located at each end of the patch and covering the full width. Each repaired panel was subjected to tension/tension cyclic fatigue with a maximum …

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A Process For Vectoring Offensive Information Warfare As A Primary Weapon Option Within The United States Air Force, Sheila G. Bennett Mar 2001

A Process For Vectoring Offensive Information Warfare As A Primary Weapon Option Within The United States Air Force, Sheila G. Bennett

Theses and Dissertations

Consistently and comprehensively using Information Operations (IO) capabilities as primary weapon option within the Air Force is the next step to operationalizing IO within the Air Force. Doctrine and official guidance has set the variables of mission and concepts of operations, organizational structure, and IW players in place. The missing variable to operationalizing IO and probably the most difficult is the 'how' or process of the equation. This research will introduce a useable process that can be incorporated within the Air Force for integrating offensive IW activities into the current and given environment. The process is the basis for further …

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Estimation Of Relative Satellite Formation Elements In Near Circular Orbits, Ralph E. Bordner Iii Mar 2001

Estimation Of Relative Satellite Formation Elements In Near Circular Orbits, Ralph E. Bordner Iii

Theses and Dissertations

Precise relative position determination of satellite formation elements in near circular orbits is the focus of this thesis. A Bayes filter is used for the estimator with the dynamics solution obtained by solving the time periodic, linearized system via Floquet theory. This approach is similar to that of the traditional Clohessy-Wiltshire treatment, however much more of the system's behavior is retained by using a linear, time periodic system. The dynamics model includes all zonal harmonics of the Earth as well as sectoral, tesseral, and air drag perturbations. The filter algorithm was fed three types of simulated measurements: relative Carrier-Phases Differential …

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The Calibration Of Bistatic Radar Cross Section Measurements, Christopher J. Bradley Mar 2001

The Calibration Of Bistatic Radar Cross Section Measurements, Christopher J. Bradley

Theses and Dissertations

Recent advances in signal processing and remote sensing have highlighted the importance of bistatic radar systems for the purposes of environmental monitoring, surveillance, and tracking radar. The calibration of such systems has been problematic-much more so than similar monostatic systems, primarily as a result of the lack of reference objects suitable for calibrating at any given bistatic angle. This research deals with the problems of calibrating full-polarimetric laboratory-environment bistatic radar systems, including the lack of suitable calibration targets and procedures, and operational considerations such as alignment and mounting. Several popular bistatic calibration techniques are classified, evaluated, and comparisons are made …

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 17, Number 6, March 2001, College Of Engineering And Computer Science, Wright State University Mar 2001

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 17, Number 6, March 2001, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

An eight page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Bending Instability In Electrospinning Of Nanofibers, A. L. Yarin, S. Koombhongse, Darrell Hyson Reneker Mar 2001

Bending Instability In Electrospinning Of Nanofibers, A. L. Yarin, S. Koombhongse, Darrell Hyson Reneker

College of Polymer Science and Polymer Engineering

A localized approximation was developed to calculate the bending electric force acting on an electrified polymer jet, which is a key element of the electrospinning process for manufacturing of nanofibers. Using this force, a far reaching analogy between the electrically driven bending instability and the aerodynamically driven instability was established. Continuous, quasi-one-dimensional, partial differential equations were derived and used to predict the growth rate of small electrically driven bending perturbations of a liquid column. A discretized form of these equations, that accounts for solvent evaporation and polymer solidification, was used to calculate the jet paths during the course of nonlinear …

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Yield Moment Of Cold-Formed Steel Beams Under Different Strain Rates, Chi Ling Pan, Wei Wen Yu Mar 2001

Yield Moment Of Cold-Formed Steel Beams Under Different Strain Rates, Chi Ling Pan, Wei Wen Yu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

It has been recognized that the mechanical properties of sheet steels and the structural strength of cold-formed steel members can be influenced by strain rate. For studying the local and post buckling behavior of stiffened and unstiffened compression elements under a dynamic loading condition, 60 beams, which were assembled from the same material, have been tested under different strain rates. To study the structural behavior of hybrid cold-formed steel beams, a total of 72 specimens was investigated. The results showed that the strength of beams increases with increasing strain rates. The amount of increase was found to be dependent on …

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Value Of Research: Spr Projects From 1995 To 1999, Donald L. Hartman Mar 2001

Value Of Research: Spr Projects From 1995 To 1999, Donald L. Hartman

Kentucky Transportation Center Research Report

This report provides summary documentation of the 45 “SPR” research projects funded at the Kentucky Transportation Center (University of Kentucky) from 1995 through 1999. Eleven of these projects were selected for highlighting with up-to-date information regarding results and benefits. They represent a diverse range of research and demonstrate considerable breadth in the implementation of results. Abstracts for all the projects are include in the appendix. A brief discussion of the need/purpose of research, the research process, and the program areas of research at the Kentucky Transportation Center is included.

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Report On County Road Finance And Fhwa Biennial Form 1998-1999, Doug Kreis Mar 2001

Report On County Road Finance And Fhwa Biennial Form 1998-1999, Doug Kreis

Kentucky Transportation Center Research Report

This report shows the revenues and expenditures associated with county and city resources for fiscal year 1998-1999 within the state of Kentucky. Federal Highway Form 536, which is included as the primary product of this project, shows where all revenues were generated as well as all allocations of the local highway funds. Also included within this report is a detailed report on county road finance, which is widely used within government throughout Kentucky to determine where allocated funding has been spent.

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Bistable Operation Of A Two-Section 1.3-Mm Inas Quantum Dot Laser—Absorption Saturation And The Quantum Confined Stark Effect, Xiaodong Huang, A. Stintz, Hua Li, Audra Rice, G. T. Liu, L.F. Lester, Julian Cheng, K.J. Malloy Mar 2001

Bistable Operation Of A Two-Section 1.3-Mm Inas Quantum Dot Laser—Absorption Saturation And The Quantum Confined Stark Effect, Xiaodong Huang, A. Stintz, Hua Li, Audra Rice, G. T. Liu, L.F. Lester, Julian Cheng, K.J. Malloy

Faculty Publications

Room temperature, continuous-wave bistability was observed in oxide-confined, two-section, 1.3- m quantum-dot (QD) lasers with an integrated intracavity quantum-dot saturable absorber. The origin of the hysteresis and bistability were shown to be due to the nonlinear saturation of the QD absorption and the electroabsorption induced by the quantum confined Stark effect.

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Analysis Of Microdamage Evolution Histories In Composites, Yuris A. Dzenis, Jie Qian Mar 2001

Analysis Of Microdamage Evolution Histories In Composites, Yuris A. Dzenis, Jie Qian

Department of Engineering Mechanics: Faculty Publications

Evolution of microdamage in advanced composites was experimentally studied in this paper. A new method of acoustic emission (AE) analysis of histories of different damage mechanisms was formulated based on a combination of transient AE classification and multiparameter filtering. The capabilities of the method were illustrated on examples of damage evolution in several graphite/epoxy composites. Three characteristic AE waveforms with different frequency spectra were identified based on the transient analysis. Regions occupied by these waveforms in the amplitude–rise time parametric space were identified for the [0]8 and [90]16 unidirectional composites. Multiparameter filtering was applied to extract evolution histories …

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Moving Towards Massively Scalable Video-Based Sensor Networks, Wu-Chi Feng, Jonathan Walpole, Calton Pu, Wu-Chang Feng Mar 2001

Moving Towards Massively Scalable Video-Based Sensor Networks, Wu-Chi Feng, Jonathan Walpole, Calton Pu, Wu-Chang Feng

Computer Science Faculty Publications and Presentations

Networking and computing technologies are becoming advanced enough to enable a wealth of diverse applications that will drastically change our everyday lives. Some past examples of these developments include the World Wide Web and wireless data networking infrastructures. As is quite obvious, the World Wide Web has enabled a fundamental change in the way many people deal with day-to-day tasks. Through the web, one can now make on-line reservations for travel, pay bills through on-line banking services, and view personalized on-line newscasts. More recently, developments in wireless technologies have enabled anywhere, anytime access to information over wireless medium. As wireless …

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An Evaluation Of Age Effects On Driver Comprehension Of Flashing Traffic Signal Indications Using Multivariate Multiple Response Analysis Of Variance Models, Alexander Drakopoulos, Richard W. Lyles Mar 2001

An Evaluation Of Age Effects On Driver Comprehension Of Flashing Traffic Signal Indications Using Multivariate Multiple Response Analysis Of Variance Models, Alexander Drakopoulos, Richard W. Lyles

Civil and Environmental Engineering Faculty Research and Publications

Objective: The objective of this experiment was to identify whether drivers comprehended traffic signals differently when turning left at signalized intersections where traffic signals were in “flashing mode” operation. Method:Multivariate multiple response analysis of variance models were used to analyze the simultaneous effects of displayed color combination, age, and geographical location on signal message interpretation. Data were gathered in a laboratory environment. Results: Left-turn and through-signal color combination had a significant effect on subject comprehension. Comprehension was found to be lowest for displays flashing red only, followed by displays flashing red on the left-turn, and yellow on the through-signal, …

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Bs News Mar 2001

Bs News

Building Services Engineering

No abstract provided.

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A Mechanistic Model For Internal Bone Remodeling Exhibits Different Dynamic Responses In Disuse And Overload, Scott J. Hazelwood, R. Bruce Martin, Mark M. Rashid, Juan J. Rodrigo Mar 2001

A Mechanistic Model For Internal Bone Remodeling Exhibits Different Dynamic Responses In Disuse And Overload, Scott J. Hazelwood, R. Bruce Martin, Mark M. Rashid, Juan J. Rodrigo

Biomedical Engineering

Bone is a dynamic tissue which, through the process of bone remodeling in the mature skeleton, renews itself during normal function and adapts to mechanical loads. It is, therefore, important to understand the effect of remodeling on the mechanical function of bone, as well as the effect of the inherent time lag in the remodeling process. In this study, we develop a constitutive model for bone remodeling which includes a number of relevant mechanical and biological processes and use this model to address differences in the remodeling behavior as a volume element of bone is placed in disuse or overload. …

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Dopant Structural Distortions In High-Temperature Superconductors: An Active Or A Passive Role?, Daniel Haskel, Edward A. Stern, Fatih Dogan, Arnie R. Moodenbaugh Mar 2001

Dopant Structural Distortions In High-Temperature Superconductors: An Active Or A Passive Role?, Daniel Haskel, Edward A. Stern, Fatih Dogan, Arnie R. Moodenbaugh

Materials Science and Engineering Faculty Research & Creative Works

The parent compounds of high-temperature superconductors, such as YBa2Cu3O6 and La2CuO4, are strongly interacting electron systems, rendering them insulators with Mott-Hubbard gaps of a few electronvolts. Charge carriers (holes) are introduced by chemical doping, causing an insulator-metal (IM) transition and, at low temperatures, superconductivity. the role of dopants is widely seen as limited to the introduction of holes into the CuO2 planes (i.e. occupying electronic states derived from Cu and O 2px,y atomic orbitals). Most theories of high-Tc superconductivity deal with pairing interactions between these planar holes. Local distortions around dopants are poorly understood, because of the experimental difficulty in …

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Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler Mar 2001

Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Using published experimental data on the thermal conductivity, mutual diffusivity, and heats of transport, the degree of coupling between heat and mass flows has been calculated for binary and ternary nonideal liquid mixtures. The binary mixtures consist of two types: the first is six systems of six-to-eight-carbon straight and branched chain alkanes in chloroform and in carbon tetrachloride; and the second is mixtures of carbon tetrachloride with benzene, toluene, 2-propanone, n-hexane, and 11-octane. The ternary mixture considered is toluene-chlorobenzene-bromobenzene. The published data are available at 35°C, 30°C, and 35°C and ambient pressure. Using the linear nonequilibi-ium thermodynainics (LNET) and the …

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Rigex: Preliminary Design Of A Rigidized Inflatable Get-Away-Special Experiment, John D. Disebastian Iii Mar 2001

Rigex: Preliminary Design Of A Rigidized Inflatable Get-Away-Special Experiment, John D. Disebastian Iii

Theses and Dissertations

As space structures grow in size and complexity, their weight and cost increase considerably. The use of inflatable and rigidizable structures offers drastic improvements in all areas of spacecraft design. The goal of this experiment is to verify and validate ground testing of inflation and rigidization methods for inflatable space structures. The Rigidized Inflatable Get-Away-Special Experiment is an autonomous, self-contained space shuttle experiment that will inflate and rigidize several structures. After inflation, the experiment will perform a structural analysis by exciting the rigidized structures and collecting vibration data. A systems engineering approach is utilized to make design decisions based on …

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Solar Radiation Pressure Modeling Issues For High Altitude Satellites, Dayne G. Cook Mar 2001

Solar Radiation Pressure Modeling Issues For High Altitude Satellites, Dayne G. Cook

Theses and Dissertations

Current satellite orbit propagation techniques employ a solar radiation pressure model that makes simplifying assumptions concerning the satellite and its orbital geometry. Solar radiation pressure, a non-gravitational perturbation, significantly affects satellite motion at high altitudes. The model currently in use by the Air Force for orbit determination includes the following assumptions: a constant cross-sectional area projected to the Sun, cylindrical Earth shadow for eclipse, and specular reflection. In reality, the satellite's cross-sectional area with respect to the Sun constantly changes, the Earth's shadow is conical, and reflection is both specular and diffuse. Additionally, the solar flux received at the Earth …

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Award Term Incentive Contracting: An Investigation Of United States Air Force Strategic Purchasing, Rachael A. Harris Mar 2001

Award Term Incentive Contracting: An Investigation Of United States Air Force Strategic Purchasing, Rachael A. Harris

Theses and Dissertations

This research explored implementing a best commercial practice of establishing strategic purchasing relationships within the Department of Defense (DOD) procurement environment. The research was sparked by Air Force Material Command's (AFMC) instituting a commercial style acquisition strategy using an award term incentive on several programs. The award term incentive provides for extensions or reductions to the term of the contract based on contractors' level of performance. Forthcoming implementation of Air Force FAR supplement 5317.7X Incentive Term Extension, will likely increase the number of acquisitions using an award term incentive. Research findings indicate that management should consider expanding the AFMC award …

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Modification Of Position And Attitude Determination Of A Test Article Through Photogrammetry To Account For Structural Deformation, Sean A. Krolikowski Mar 2001

Modification Of Position And Attitude Determination Of A Test Article Through Photogrammetry To Account For Structural Deformation, Sean A. Krolikowski

Theses and Dissertations

This study improved the current method of position and attitude determination to account for structural deformation of the wind tunnel test article due to aerodynamic loading. To account for deformation, parabolic bending and linear twisting coefficients were added into the Levenberg-Marquardt multi-parameter solver. By accounting for deformation, the accuracy of position and attitude determination was greatly improved. This study also takes a qualitative look at the optimum number of wind tunnel cameras and model targets. Optimal configuration was found to be around 50 targets and 2 cameras offset by 90 degrees.

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