Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Operations Research, Systems Engineering and Industrial Engineering (26)
- Aerospace Engineering (22)
- Physical Sciences and Mathematics (15)
- Operational Research (13)
- Electrical and Computer Engineering (11)
-
- Civil and Environmental Engineering (8)
- Aviation (7)
- Business (7)
- Computer Engineering (6)
- Computer Sciences (6)
- Other Operations Research, Systems Engineering and Industrial Engineering (6)
- Environmental Engineering (4)
- Environmental Sciences (4)
- Human Resources Management (4)
- Aviation Safety and Security (3)
- Digital Communications and Networking (3)
- Materials Science and Engineering (3)
- Operations and Supply Chain Management (3)
- Civil Engineering (2)
- Electrical and Electronics (2)
- Engineering Science and Materials (2)
- Graphics and Human Computer Interfaces (2)
- Management and Operations (2)
- Mechanics of Materials (2)
- Meteorology (2)
- Oceanography and Atmospheric Sciences and Meteorology (2)
- Physics (2)
- Signal Processing (2)
- Space Vehicles (2)
- Keyword
-
- United States. Air Force (5)
- Global Positioning System (4)
- #antcenter (3)
- Civil engineers (3)
- Combat (3)
-
- Drone aircraft (3)
- Flight control (3)
- Military airlift (3)
- Airplanes--Piloting (2)
- Logistics (2)
- Meteorology in aeronautics (2)
- Reconnaissance aircraft (2)
- United States. Air Force--Transportation (2)
- Weather forecasting (2)
- Aerodynamics (1)
- Aerospace industries--Estimates and cost (1)
- Aircraft accidents (1)
- Aircraft industry (1)
- Airdrop (1)
- Airplanes--Air refueling--United States (1)
- Airplanes--Cockpits--Design (1)
- Airplanes--Computer-aided design (1)
- Airplanes--Control systems (1)
- Airplanes--Design and construction (1)
- Airplanes--Turbine-propeller engines (1)
- Airtankers (Military science)--United States (1)
- Aluminum compounds--Spectra (1)
- Amplitude modulation (1)
- Analog electronic systems--Testing (1)
- Antennas (Electronics)--Design (1)
Articles 1 - 30 of 84
Full-Text Articles in Engineering
Computer-Based Methods For Constructing Two-Level Fractional-Factorial Experimental Designs With A Requirement Set, Steven L. Forsythe
Computer-Based Methods For Constructing Two-Level Fractional-Factorial Experimental Designs With A Requirement Set, Steven L. Forsythe
Theses and Dissertations
This dissertation developed four methodologies for computer-aided experimental design of two-level fractional factorial designs with requirement sets (DOE/RS). The requirement sets identify all the experimental factors and the appropriate interaction terms to be evaluated in the experiment. Taguchi graphs and similar manual methods provide techniques for solving the DOE/RS problem. Unfortunately, these methods are limited because they become difficult to use as the number of factors or interaction terms exceeds ten. This research showed that the DOE/RS problem belongs to a class of difficult-to-solve problems known as NP-Complete. It is the combinatorial nature of NP-Complete problems that causes them to …
Estimating Budget Relationships With A Leontief Input-Output Model, Guenever L. R. Shariff
Estimating Budget Relationships With A Leontief Input-Output Model, Guenever L. R. Shariff
Theses and Dissertations
Forty years ago, the Office of the Secretary of Defense proposed using the Leontief input-output model to assess tradeoffs in the Department of Defense's (DoD) budget. We demonstrate that the Leontief input-output model can assess tradeoffs in the Air Force's budget. To increase one part of the Air Force's budget, we need to know the interrelationships between that budget area and the other areas. In this research, we look at different methods of how the functional areas might interact. We demonstrate our methodology on two data sets - DoD and the Air Force aggregate budget data. By looking at how …
Covalidation Of Dissimilarly Structured Models, Samuel A. Wright
Covalidation Of Dissimilarly Structured Models, Samuel A. Wright
Theses and Dissertations
A methodology is presented which allows comparison between models constructed under different modeling paradigms. Consider the following situation: Two models are constructed to study different aspects of the same system. One model simulates a fleet of aircraft moving a given combination of cargo and passengers from an onload point to an offload point. A second model is a linear programming model that optimizes the aircraft and route selection required for the same scenario. We develop a methodology to structure the comparison between large-scale models such as these. Models that compare favorably using this methodology are deemed covalid. Models that perform …
Simulation And Analysis Of Wing Rock Physics For A Generic Fighter Model With Three Degrees-Of-Freedom, Ahmed Saad
Simulation And Analysis Of Wing Rock Physics For A Generic Fighter Model With Three Degrees-Of-Freedom, Ahmed Saad
Theses and Dissertations
Modern fighter designs have been associated with lateral self-excited oscillations own as "Wing Rock". Simulations of wing rock by flow visualization utilities have been encouraged to develop a complete understanding of the fluid mechanism that drives the motion as well as for prediction purposes. Previous wind/water tunnel simulations have been limited to a single degree-of freedom (DoF) in roll. In this study, for the first time, wing rock is computationally simulated in three DoF: roll, sideslip, and vertical motion to study the effect of adding file sideslip and vertical motion. The results are for a generic fighter model consisting of …
Three-Dimensional Dynamic Stress Analysis Of Sandwich Panels, Victor Y. Perel
Three-Dimensional Dynamic Stress Analysis Of Sandwich Panels, Victor Y. Perel
Theses and Dissertations
A layerwise geometrically nonlinear theory for a thick sandwich plate was developed by introducing assumptions on a variation of transverse strains in the thickness direction of the faces and the core of the plate. An effect of transverse extensibility or compressibility of the core and the face sheets is taken into account, and the terms associated with transverse shear strain of the face sheets and the core are included into the expression for the strain energy. Displacements, obtained by integration of the strain-displacement relations, depend nonlinearly on a coordinate in the thickness direction, and are continuous at the boundaries between …
Turbo Codes For Wireless Mobile Communication Systems Applications, Moataz M. Salah
Turbo Codes For Wireless Mobile Communication Systems Applications, Moataz M. Salah
Theses and Dissertations
Research in coding theory has seen many proposals aimed at the construction of powerful codes using block and convolutional codes. Recently, a new forward error control code, known as turbo code, was introduced. This new code yields very good performance (near the Shannon limit) with relatively simple component codes and large interleavers in combination with an iterative decoding process. Among the most important applications of turbo codes are wireless mobile communication systems. A significant performance metric for this application is the minimization of end-to-end delay. In this dissertation, different ways to enhance the performance of turbo codes with short frames …
Analysis Of The Air Force Iso 14001 Pilot Study Conducted By Dod, Rodney C. Harris
Analysis Of The Air Force Iso 14001 Pilot Study Conducted By Dod, Rodney C. Harris
Theses and Dissertations
The Department of Defense (DoD) conducted an ISO 14001 pilot study with the primary goal of determining how ISO 14001 could help DoD organizations reduce risks, improve compliance with environmental regulations, enhance stewardship, contain costs, and meet emerging regulatory requirements. This thesis analyzed the pilot study, specifically looking at the ISO 14001 implementation at three Air Force installations participating in the study. The research objectives were to identify factors that affect implementation of ISO 14001, compare the implementation strategies used by the bases, and develop propositions for Air Force managers to consider when implementing ISO 14001. Interviews of key personnel, …
Finite Element Model Updating Using Antiresonant Frequencies, Keith W. Jones
Finite Element Model Updating Using Antiresonant Frequencies, Keith W. Jones
Theses and Dissertations
The applications of antiresonant frequencies to finite element (FE) model updating are few and usually limited to numerical examples. This work uses antiresonant frequencies in the model updating of an experimental structure and analyzes the physical correctness of the updated model by using it to detect damage. Antiresonant frequencies were used in the FE model updating of a six-meter aluminum truss. The model used rigid links to model welded and bolted joints. Rigid link dimensions were used as parameters in an iterative update based on eigenvalue and antiresonance sensitivities. The first update used 11 natural frequencies and 21 antiresonant frequencies …
A Methodology For Integrating Tools In A Web-Based Environment, Musa Serdar Arslan
A Methodology For Integrating Tools In A Web-Based Environment, Musa Serdar Arslan
Theses and Dissertations
Web-based technologies are evolving very rapidly. New technologies are introduced very frequently in the realm of the Web and Internet. This evolution also affects database management systems (DBMSs). Almost all DBMS vendors are making their systems "Web-enabled." The Internet and the World Wide Web are getting more important and bigger than ever. Because of the increase in the importance of the Internet and the Web, migrating old applications and tools to a web-based environment is becoming more important. When migrating old applications or tools to the web-based environment, integration of tools becomes an important issue. In this research, a step-by-step …
Investigation Into The Adaptation Of A Steam Injector For Use On A Liquid Rocket Engine, Charles B. Mcfarland
Investigation Into The Adaptation Of A Steam Injector For Use On A Liquid Rocket Engine, Charles B. Mcfarland
Theses and Dissertations
This thesis investigated the properties of a steam injector to see if the concept might be suitable for use on a liquid rocket engine. A steam injector is a device developed in the 1850's to inject feedwater into the boiler on a steam locomotive without any moving parts. The injectors uses a small portion of the steam generated in the boiler to increase the pressure of the feedwater to a level high than the pressure in the boiler. Previous experiments claim that condensation of steam to water was necessary for an injector to work. This experiment tested injection without condensation …
Comparative Analysis Of Mobility Management Schemes In A Low Earth Orbit Satellite Network, Stephen R. Conkling
Comparative Analysis Of Mobility Management Schemes In A Low Earth Orbit Satellite Network, Stephen R. Conkling
Theses and Dissertations
In the 60's the United States and the Union of Soviet Socialist Republics engaged in a "space race" to be the first to put a man on the moon. Today, the space race is between large multinational telecommunication corporations with the winner receiving the financial rewards by providing communication services to the billions without even a simple telephone. Many entrants are using Low Earth Orbit (LEO) satellites to provide the communications infrastructure, but the number of customers a satellite can support is limited by bandwidth available. This resource must be used efficiently, and this involves reducing the management overhead. This …
Realtime Color Stereovision Processing, Byron P. Formwalt
Realtime Color Stereovision Processing, Byron P. Formwalt
Theses and Dissertations
Recent developments in aviation have made micro air vehicles (MAVs) a reality. These featherweight palm-sized radio-controlled flying saucers embody the future of air-to-ground combat. No one has ever successfully implemented an autonomous control system for MAVs. Because MAVs are physically small with limited energy supplies, video signals offer superiority over radar for navigational applications. This research takes a step forward in real time machine vision processing. It investigates techniques for implementing a real time stereovision processing system using two miniature color cameras. The effects of poor-quality optics are overcome by a robust algorithm, which operates in real time and achieves …
Monotonic And Fatigue Loading Behavior Of An Oxide/Oxide Ceramic Matrix Composite, Steven G. Steel
Monotonic And Fatigue Loading Behavior Of An Oxide/Oxide Ceramic Matrix Composite, Steven G. Steel
Theses and Dissertations
This thesis evaluates an oxide/oxide ceramic matrix composite, N720/A, for high temperature aerospace applications. The composite consists of a porous alumina matrix reinforced by ten plies of Nextel 720 fibers in a balanced 8 harness satin weave. Monotonic tensile and fatigue tests were performed at room temperature and 1200 °C. The effect of moisture on 1200 °C fatigue life was also examined. Modulus, maximum and minimum strain, and stress-strain hysteresis were monitored to characterized fatigue damage. Retained strength of all specimens that survived 100000 fatigue cycles was tested. Microscopy and fractography were used to examine damage and fracture surfaces. N720/A …
Simulation Evaluation Of The Combat Value Of A Standoff Precision Airdrop Capability, Michael W. Varner
Simulation Evaluation Of The Combat Value Of A Standoff Precision Airdrop Capability, Michael W. Varner
Theses and Dissertations
This project is a simulation evaluation of the developmental standoff precision airdrop (SOPAD) capability. SOPAD is a new technology under consideration to deliver supplies to forward-deployed units using either a semi-rigid wing or a guided parafoil. These delivery systems allow airdrop of supplies from altitudes of 25,000 feet and distances 25 miles from the delivery point. Using global positioning system guidance, on board navigational computers, and automatic steering mechanisms, the delivery system flies to the target following a designated flight plan. The concept includes delivering supplies to remote and potentially hostile areas without endangering the supply aircraft. In addition, supplies …
Tool-Based Integration And Code Generation Of Object Models, Michael Ray Ashby
Tool-Based Integration And Code Generation Of Object Models, Michael Ray Ashby
Theses and Dissertations
Today many organizations are faced with multiple large legacy data stores in different formats and the need to use data from each data store with tools based on the other data stores' formats. This thesis presents a tool-based methodology for integrating object-oriented data models with automatic generation of code. The generated code defines a global data format, generates views of global data in individual integrated data formats, and parses data from individual formats to the global formats and from the global format to the individual formats. This allows for legacy data to be translated into the global format, and all …
A Java Universal Vehicle Router In Support Of Routing Unmanned Aerial Vehicles, Robert W. Harder
A Java Universal Vehicle Router In Support Of Routing Unmanned Aerial Vehicles, Robert W. Harder
Theses and Dissertations
Unmanned Aerial Vehicles (UAVs) help the military gather information in times of peace and war. During a mission, typically 100 sites or more, a UAV will frequently be re-tasked to visit a pop-up threat, leaving the operator to determine the best way to finish the day's list of sites after the re-tasking. I develop a prototype application to serve the needs of a specific customer, the 11th Reconnaissance Squadron, by helping them preplan missions and dynamically re-task UAVs. This prototype application is built on a reusable airframe router called the core AFIT Router, which can later be added to more …
Cost Analysis Between Saber And Design Bid Build Construction, Elwood Henry
Cost Analysis Between Saber And Design Bid Build Construction, Elwood Henry
Theses and Dissertations
The purpose of this research was to perform a cost analysis between DBB and SABER construction. The research involved traveling to Wright-Patterson and Holloman Air Force Bases to gather project information on comparable projects completed by both methods. There were a total of 46 projects collected from both bases. A methodology was developed to compare the projects completed. Projects were divided into categories containing similar types of construction. Data from the project was then used to calculate a unit cost for the project. Project comparability was demonstrated by showing the projects constructed by each method completed a similar type and …
Measurements Of The Effects Of Tunnel Wall Proximity On The Velocity Field Upstream Of A Rod With Vortex Shedding In Low-Speed Flow, David R. Hopper
Measurements Of The Effects Of Tunnel Wall Proximity On The Velocity Field Upstream Of A Rod With Vortex Shedding In Low-Speed Flow, David R. Hopper
Theses and Dissertations
High cycle fatigue is an important consideration in blade design for turbomachinery. Blades in an engine undergo countless loading cycles in a lifetime, the result of pressure waves that propagate upstream and downstream from disturbances in the flow. Better understanding of these effects would allow blade designers to reduce the effects of high cycle fatigue, such as costly recurring maintenance or catastrophic engine failure. An experimental study was undertaken to determine the unsteady flow field upstream of a single cylinder in a subsonic flow. Von Karman vortex shedding from the cylinder produced a forcing function much like periodic blade passage …
Active And Adaptive Control For Payload Launch Vibration Isolation, Julian R. Jarosh
Active And Adaptive Control For Payload Launch Vibration Isolation, Julian R. Jarosh
Theses and Dissertations
The Department of Defense has identified launch vibration isolation as a major research interest. Reducing the loads a satellite experiences during launch will greatly enhance its reliability and lifetime, and reduce payload structural mass. DoD space programs stand to benefit significantly from advances in vibration isolation technology. This study explores potential hybrid vibration isolation using active and adaptive control with a passive vibration isolator. The active control methods are Proportional-Integral-Derivative (PID) control and a skyhook damper. Lyapunov analysis is used to develop the structural adaptive control scheme. Simulink and Matlab simulations investigate these control methodologies on a lumped mass dynamic …
Nonuniformly Spaced Array Elements, Daniel R. Richards Jr.
Nonuniformly Spaced Array Elements, Daniel R. Richards Jr.
Theses and Dissertations
This thesis provides a method to reduce physical resource requirements along with cost reduction in Space Based Radar (SBR) platforms, and provides a rule of thumb for randomization effects on arrays. A trend analysis is performed on 4, 8, 12, and 16 square meter arrays. Three aperiodic thinning approaches are examined. They are an equal current density element distribution, a random periodic grid of elements, and random element distribution based a peak sidelobe indicator. According to the metrics used, the statistical and deterministic array thinning approaches performed best for these small arrays. However, the statistical arrays have a scan angle …
The Distributor’S Three-Dimensional Pallet-Packing Problem: A Mathematical Formulation And Heuristic Solution Approach, Brian P. Ballew
The Distributor’S Three-Dimensional Pallet-Packing Problem: A Mathematical Formulation And Heuristic Solution Approach, Brian P. Ballew
Theses and Dissertations
It is through practice and experience Air Force loadmasters are able to pack the Air Force standard HCU-6/E (463L) pallets efficiently. Although the loadmasters perform their jobs exceptionally well, the Air Force is in search of a model that will more efficiently pack the pallets. We have developed a mathematical formulation of the three-dimensional pallet-packing problem which minimizes the amount of unused space on a pallet. The formulation ensures each box is packed with the correct volume and dimensions, and ensures the volume of all the boxes packed is less than the available pallet volume. Additionally, the formulation ensures that …
Locating Search And Rescue Stations In The Aegean And Western Mediterranean Regions Of Turkey, Melih M. Basdemir
Locating Search And Rescue Stations In The Aegean And Western Mediterranean Regions Of Turkey, Melih M. Basdemir
Theses and Dissertations
The service of present Search and Rescue (SAR) stations in the Aegean and the Western Mediterranean regions of Turkey are not sufficient to meet the demands of the Turkish Air Force. This research seeks to find the optimum location of new SAR stations. The number of SAR stations required to cover all areas of operation becomes a very decisive element in finding the optimal coverage of the operation area by these stations. The problem of finding the optimum SAR locations can he modeled as a maximal covering location problem (MCLP). Additional constraints are added to set standards on various issues …
Finite Element Analysis Of A Composite Cylindrical Shell With A Cutout Under A Fatigue Load, Joshua T. Boatwright
Finite Element Analysis Of A Composite Cylindrical Shell With A Cutout Under A Fatigue Load, Joshua T. Boatwright
Theses and Dissertations
A higher-order shell theory is used to analyze compressive and tensile loads on a graphite/epoxy laminated cylinder containing a square cutout. The Hashin failure criterion is used to determine failure in the fiber, matrix, or lamination. Once failure occurs, the appropriate stiffness terms are reduced. This failure causes a redistribution of stress, leading to further failure. In order to account for the loss of residual strength due to cyclic loading, the stiffness matrix is further reduced at each new increment of load or displacement. The objective is not to determine the S-N curve for the material, but rather to determine …
Navigation Of Satellite Clusters, Jeffrey S. Davis
Navigation Of Satellite Clusters, Jeffrey S. Davis
Theses and Dissertations
The relative position determination of a cluster of satellites in near circular orbit was investigated in previous thesis work. The purpose of this thesis is to extend the concept to cover absolute position determination. A Bayes filter is used for the estimator with dynamics based on the two-body problem extended to account for J2 perturbations. Measurements consist of combining Global Positioning System (GPS) data for each satellite and range data between the satellites. Simulations were conducted investigating the accuracy obtainable when combining the measurements for input into the filter. Performance results consist of comparing the magnitude of the time error …
Effects Of Moisture Content In Solid Waste Landfills, Craig P. Eck
Effects Of Moisture Content In Solid Waste Landfills, Craig P. Eck
Theses and Dissertations
Solid waste landfills are an extremely complex and heterogeneous environment. Modeling the biodegradation processes within a landfill must involve an understanding of how environmental factors affect these processes. Arguably, the most important environmental factor influencing biodegradation processes is solid waste moisture content. This research effort, which is an extension of a system dynamics model previously presented by Colborn (1997) and amended by Benter (1999), attempts to understand and model the effects of moisture content on waste degradation and landfill gas generation. The new moisture structure that was added to the previous models provides a better representation of the impact of …
A Combined Inventory And Delivery Model For Repairable Items, Bahtiyar Eren
A Combined Inventory And Delivery Model For Repairable Items, Bahtiyar Eren
Theses and Dissertations
Traditionally, logistics analysts have treated the delivery problem separate from the inventory and repair problems. In other words, each of these three problems-delivery, inventory, and repair-are treated individually. We combine the vehicle routing problems and inventory allocation problems in a single formulation. Furthermore, lateral re-supply is considered, in that supplies are not only available from the main depot, but also from other bases. After we get the lateral re-supply information, we set a delivery allocation plan out of the main depot. Such allocations are then delivered via vehicles stationed at the main depot. There is a repair capability for each …
Modeling The Effect Of Nonlinear And Rate-Limited Sorption On The Natural Attenuation Of Chlorinated Ethenes, Peter P. Feng
Modeling The Effect Of Nonlinear And Rate-Limited Sorption On The Natural Attenuation Of Chlorinated Ethenes, Peter P. Feng
Theses and Dissertations
Chlorinated solvents like tetrachloroethene (PCE) and trichloroethene (TCE) are the most common detected groundwater contaminants at Department of Defense installations in the United States. Unfortunately, technologies conventionally used to remediate chlorinated solvent-contaminated groundwater often fall short of achieving regulatory goals. Natural attenuation of chlorinated solvents offers an alternative remediation strategy that may achieve goals. However, the processes involved with natural attenuation are not fully understood, and this lack of understanding has hindered acceptance of natural attenuation by regulatory agencies. This study involved use of a numerical model that incorporated the physical, chemical, and biological processes thought to be relevant to …
Global Positioning System (Gps) Error Source Prediction, Marcus G. Ferguson
Global Positioning System (Gps) Error Source Prediction, Marcus G. Ferguson
Theses and Dissertations
With the initiation of the navigation accuracy prediction algorithm used to estimate the amount of GPS solution (location and time) error for receivers, the capability to accurately predict solution errors due to the major GPS error sources is growing. Although some sources of error within the GPS solution have been previously analyzed, modeled, and/or accounted for within various modeling efforts, a formal evaluation of the seven major error sources that distort GPS activity has not been officially conducted up until this point. This research offers a logical assessment of all the major GPS error sources and their definitive impact on …
In Situ Treatment Of Chlorinated Ethene-Contaminated Groundwater Using Horizontal Flow Treatment Wells, Derek R. Ferland
In Situ Treatment Of Chlorinated Ethene-Contaminated Groundwater Using Horizontal Flow Treatment Wells, Derek R. Ferland
Theses and Dissertations
The limitations of conventional containment technologies for groundwater contaminated with chlorinated solvents have motivated development of innovative technologies to achieve national groundwater remediation objectives. One inn9vative technology that is currently under development involves metal reductants or catalysts to chemically destroy the dissolved chlorinated solvent. Models are important tools that can be used to help transition this technology to the field. Model studies can be used to gain understanding about the technology, help determine when the prospective technology might work for a given site, and design full-scale field applications.
Attitude Control And Multimedia Representation Of Air Force Institute Of Technology’S (Afit’S) Simulation Satellite (Simsat), Joseph M. Fulton
Attitude Control And Multimedia Representation Of Air Force Institute Of Technology’S (Afit’S) Simulation Satellite (Simsat), Joseph M. Fulton
Theses and Dissertations
This document describes the systematic construction of the AFIT-sponsored program to develop a laboratory-based satellite simulator. The simulation satellite (SIMSAT) system will provide a useful tool for resident staff while teaching attitude control concepts. A brief overview of attitude control theory is provided as well as a discussion of the benefits of multimedia use in education. A detailed discussion of the satellite's components allows the reader to become familiar with each piece of SIMSAT. Software control models are provided as well as a multimedia lesson plan on satellite attitude control. Also included in this document are potential experimental uses in …