Engineering Commons^™

Determining Production Capability In Aircraft Maintenance: A Regression Analysis, Charles R. Jung

Theses and Dissertations

This research analyzed twenty-three maintenance constraint and three production output performance measures for nine SAC aircraft systems. SAS System for Elementary Statistical Analysis is used to analyze twenty-one months of ex post facto maintenance data. Correlation analysis is used to identify maintenance constraints that assist in explaining aircraft maintenance production capability. Forward stepwise regression is used to build predictive models of maintenance production capability for each of the nine aircraft systems. The twenty-three maintenance constraint measures are regressed against three productivity output measures: Mission Capable Rate, Total Not Mission Capable Supply Rate and Total Not Mission Capable Maintenance Rate. The …

Challenges To United States Tactical Air Force Aircraft Maintenance Personnel: Past, Present And Future, Barbara L. Harris

Theses and Dissertations

This study assessed the challenges Tactical Air Force (TAF) aircraft maintenance personnel face as a result of the TAF reorganization. The goal was to provide aircraft maintenance managers a basis for evaluating and meeting those challenges. To accomplish this, emphasis was placed on documenting the concepts, events, and conditions which led to changes in military aircraft maintenance from the birth of aviation to the present. Current issues such as the proposed move to two-level maintenance and the formation of the TAF composite and Objective Wings were also addressed. Research was conducted through the review of available historical documents, complemented by …

Development Of An Operationally-Oriented Measure Of Sustainability, Moira D. Williams

Theses and Dissertations

This thesis proposes a framework for evaluating sustainability in the Air Force and for determining an appropriate measure of effectiveness that is both meaningful in a military sense and useful in planning and programming decisions. Following a literature review of organizational performance measures and strategy formulation, Michael Porter's Competitive Analysis model for strategy selection was presented. This model was then used to evaluate case studies in which organizations faced strategic decisions and to suggest measures by which these organizations could determine their effectiveness. The model was then shown to be applicable to the Air Force, and recommendations on implementing such …

An Analysis Of Fixed Wing Tactical Airlifter Characteristics Using An Intra-Theater Airlift Computer Model, Paul Pappas

Theses and Dissertations

This study used computer simulation to identify which tactical airlifter characteristics most significantly affected tactical airlift capability in a given scenario. The Generalized Air Mobility model was used to simulate a tactical airlift system. Aircraft characteristics within the model were grouped into six variables. A 2(6) two level full factorial experimental design was used to assess the effect of changes in aircraft characteristics on the effectiveness of the tactical airlift system. Yates algorithm was used to identify significant terms based upon the results of the factorial experiment. These significant terms were used to develop a parsimonious regression model that represented …

A Microcomputer Program For Estimating Production Costs Of Injection Molded Plastic Structures, Kyle F. Byard

Theses and Dissertations

The job of estimating the production costs of injection molded thermoplastic structures requires designers and analysts to produce detailed preliminary drawings and consult machinists with expertise in mold production. Interviews with injection molding experts produced a scale of part complexity and associated range of labor hours for mold production. This scale is incorporated into a cost estimating methodology which allows the analyst to estimate the cost of the structure without the aid of technicians. The resulting cost model for the injection molding process is then programmed into an interactive Pascal computer program for ease of use and documentation.

Higher-Order Thickness Expansions For Cylindrical Shells, Randy A. Smith

Theses and Dissertations

Eight variations of higher-order transverse shear deformation (HTSD) theory were developed for composite shells. Three attributes were varied to produce the eight variations. These attributes include the order of the thickness expansions used to approximate the shell shape factors and the assumed linear displacement field and the nonlinearity of transverse shear strain. Several cylindrical shell problems were investigated using SHELL, a finite- element code with a 36 degree of freedom cylindrical shell element. MACSYMA, a symbolic manipulation code, was used to formulate the element independent stiffness arrays for each variation of the theory. When all nonlinear strain- displacement terms for …

A Comparative Analysis Of Three Water Treatment Programs For Cooling Tower Systems, Jeffry W. Shea

Theses and Dissertations

This study investigated the cost and effectiveness of three cooling tower water treatment programs. The programs studied were an acid program developed at WPAFB, a commercial solubilizer program manufactured by Lombardi, Inc, and a crystal modifier program developed by Dias, Inc. The experiment ran for 60 days at which time cost and effectiveness data were collected. Cost comparison was evaluated on the basis of tower performance in MBtu. The costs considered in this experiment were water costs, sewer costs, and chemical costs. All costs were recorded and totaled, then divided by the tower's performance. The effectiveness of each treatment method …

Evaluation Of Managerial Challenges Created By Acceleration Of The Installation Restoration Program, Robert L. Vinson Iii

Theses and Dissertations

This study investigates the distribution of managerial tasks related to the Installation Restoration Program (IRP). Initiated in 1986, the IRP is the DoD program to identify and clean-up hazardous waste sites. Study areas include current distribution of managerial tasks, changes in task distribution needed to accelerate the program, and potential resource constraints. Additionally, the study considers how acceleration of Army and Navy restoration programs could impact the Air Force IRP. The study reveals IRP management is heavily centralized at MAJCOM with most technical work being performed through contracts with service centers. Individual bases have little direct involvement in the program. …

The Operation Of Military Family Housing As A Business Enterprise. A Case Study At Langley Air Force Base, Virginia, Michael T. Ray

Theses and Dissertations

The focus of this research was to determine the feasibility of operating Military Family Housing (MFH) as a business enterprise, based on rental income. A case study of the Langley AFB Military Family Housing operation during FY 90 was used to determine if housing allowances forfeited by residents of base housing would provide sufficient rental income for the annual operations, maintenance and capital improvement of the MFH assets. It further compared the descriptive data from Langley AFB, Virginia, to USAF averages to determine if the findings at Langley were generalizable across the Air Force. The case study showed that Basic …

Applying The Theory Of Constraints To A Base Civil Engineering Operations Branch, Bryan K. Zachmeier

Theses and Dissertations

The purpose of this thesis is to introduce the Civil Engineering manager to the Theory of Constraints management philosophy and to show how to apply this process of ongoing improvement to the Operations Branch. One of the reasons for the success of Theory of Constraints in commercial firms is that it provides all levels of management the ability to find simple solutions for bridging the gap between local and global issues. This 'bridge' is built by clearly defining the goal of the organization and using performance measurements capable of predicting the effect of local decisions and actions on the goal. …

An Expert System Solution For The Quantitative Condition Assessment Of Electrical Distribution Systems In The United States Air Force, David O. Paine

Theses and Dissertations

Faced with a rapidly decreasing budget, the Air Force is in need of a method to objectively evaluate its aging utility infrastructure assets. This objective evaluation could be used to compare similar facility infrastructure systems for identification of possible problem areas and prioritization of major repair projects. This thesis developed a component model which can be used to objectively evaluate a typical electrical distribution system. The Delphi process was used to gather expert opinions regarding three areas: (1) the critical components which should be included in the model, (2) the relative importance of each selected critical component, and (3) the …

Industrial Wastewater Management Practices In Air Force Logistics Command, Patrick J. Smith

Theses and Dissertations

The selection of a model plant was based upon criteria established by a review of current literature. The criteria were permit compliance, plant performance, and the adoption of pollution prevention as a corporate environmental philosophy. In this study, private sector firms were examined to identify the best industrial wastewater management practices using a Total Quality Management (TQM) tool called benchmarking. The data gathering process consisted a survey of water pollution control organizations, and a survey of benchmark candidates. The purpose of surveying water pollution control organizations was to objectively identify possible benchmark candidates. A questionnaire was then used to gather …

Investigation Of Advanced Aircraft Performance Measures Of Merit Including New Agility Metrics, Bruce A. Fox

Theses and Dissertations

Advanced aircraft performance measures of merit have been proposed and individually analyzed by various researchers. These metrics have been consolidated into a single computer code as part of this research effort. This code was used to study the relationships between the advanced metrics, aircraft design metrics and an aircraft's trajectory performance. The study found a linear relationship existed between the advanced metrics and the design metrics. This relationship was used to quantify the required levels of the advanced metrics which would give desired changes in trajectory performance. The results showed that advanced metrics could be applied only to very specific …

Model Identification And Control System Design For The Lambda Unmanned Research Vehicle, Gerald A. Swift

Theses and Dissertations

Research for this thesis centered on the Lambda Unmanned Research Vehicle (URV), an asset of the Flight Dynamics Directorate, Wright Laboratory Patterson AFB. The following tasks were accomplished: (1) a linear, state-space, small perturbation model was developed for both the longitudinal and lateral directional dynamics of the vehicles, and (2) pitch rate roll rate, and yaw rate flight controllers were designed using classical and multivariable feedback methods. The parameters of the linear, state space, small perturbation model were estimated from actual flight test data. Digital Datcom was first used to estimate stability and control derivatives from the vehicle's geometry. Maximum …

Desert Express: An Analysis On Improved Customer Service, Thomas C. Thalheim

Theses and Dissertations

Operation Desert Shield/Storm provided an opportunity to test the planning for U.S. forces to operate in a low intensity conflict. Both operations provided the opportunity for the logistics community to observe how the support forces provided the required supplies to the forward combat forces. In response to customers' requests, the U.S. Transportation Command created Desert Express, a daily package express flight from Charleston, SC to Saudi Arabia. The research question addresses the how and why Desert Express came about. Additional investigative questions cover the following: mission objectives, planners' and customers' expectations, system performance, and implications on the Defense Transportation System. …

A Study Of Pilot Attitudes Regarding The Impact On Mission Effectiveness Of Using New Cockpit Automation Technologies To Replace The Navigator/Weapon System Officer/Electronic Warfare Officer, William K. Starr, Donald A. Welch

Theses and Dissertations

This study analyzed the self-reported survey responses of 404 Air Force pilots concerning their perceptions of using advanced cockpit technologies to replace the Navigator, Weapon System Officer, and Electronic Warfare Officer (Nav/WSO/EWO) and the impact of advanced cockpit technologies on combat mission effectiveness. The first objective of this study was to compare, by aircraft type, the mission effectiveness factors that are always critical and almost always critical to the success of a combat mission. The second objective was to examine, from the pilot's point of view, the Nav/WSO/EWO's contribution (NAVCRIT) to enhancing the combat mission effectiveness factors. The third objective …

A Comparison Of The Air Force, Army, And Navy Test And Evaluation Reliability And Maintainability Data Base Systems, Donald L. Scantlan Jr.

Theses and Dissertations

This study was conducted to create a single source document which could be used by test and evaluation personnel involved in joint programs for translating reliability and maintainability terms. The comparison begins by describing the forms, data elements, and data items, as collected by the Air Force's System Effectiveness Data System, the Army's Reliability, Availability, Maintainability Logistics System, and the Navy's Maintenance and Material Management, Maintenance Data System. The Findings paragraph is a stand-alone document which could serve as a translating dictionary for reliability and maintainability data elements between the different service's data systems. Upon the conclusion of this study, …

An Analysis Of Total Quality Management In Aeronautical Systems Division, Mark D. Caudle

Theses and Dissertations

This study investigated the major schools of thought on various aspects of quality management and quality improvement. Areas covered included definitions of waste and quality, views on the cost of quality, tools and techniques used for quality improvement, and management philosophies and frameworks for continuous improvement. In addition, this study analyzed the structure and training content of the current Total Quality Management program at Aeronautical Systems Division (ASD). Pre- and post-test surveys on employee attitudes toward organizational effective were analyzed from the Advanced Cruise Missile System Program Office (SPO), the F-15 SPO, and the ASD Deputy Chief of Staff for …

Efficient Aircrew Scheduling In An Operational Test And Evaluation Organization, Charles P. Modrich

Theses and Dissertations

The original intent of this research was to locate or develop tools which would improve the efficiency of the aircrew scheduling process in the 4950 Test Wing. However, late in the research it became apparent that several factors observed by the researcher complicate the implementation of more efficient methods. Therefore, the focus of the research became the documentation of those factors. A case study methodology was used in answering the investigative questions. This was an exploratory study conducted in a field setting environment. Direct observation and the use of structural interviews with scheduling personnel were the methods of data collection. …

Crystallization Kinetics And Polyblends Of Poly(Ethylene Terephthalate) Recycled From Post-Consumer Beverage Bottles, Peming Peter Hsu

Dissertations

In order to reduce waste generation, and comply with state and federal laws, plastic beverage bottles are usually undergoing recycling. Poly(ethylene terephthalate) [PET], which is the main component the bottles are made of, cannot be used for manufacturing new food containers, and has to be used for manufacturing other end consumer products. The recycled PET is a cheap material, but its use is problematic due to the low crystallization rates of PET. The present study investigates ways of accelerating PET crystallization by using inorganic carbonate salts as nucleating agents. This study also explores the possibility of forming polymer blends based …

Performance Of The Extended Token Bus Network With Asymmetric Load Distribution, Hong Lin

Theses

The Token Bus, IEEE 802.4, provides high priority message options. The delay of high priority messages becomes an important criterion in the design and management of computer communication networks. A goal of the protocol is to allocate sufficient bandwidth and frequency of access to minimize of the high priority message delay. In this study, a simulation model of a priority based network, consisting of two token bus networks interconnected by a bridge is implemented. The load distribution among stations is asymmetric and the messages are divided into two priorities, high and low. Both fixed and variable token token holding times …

Implementation Of An Integrated High Energy Beam Workcell, Varadaraj Souda

Theses

This study is an effort to advance the technology of machining by High energy beams. Investigation of the Waterjet, Plasma and the Oxyfuel beams was carried out to explore novel machining techniques. The study was focussed on three major objectives.

One of the major objectives was to set up an Integrated beam workcell consisting of the three beams. A hydroabrasive waterjet workcell was modified to install the three cutting tools to be along the same line of traverse. An integrated beam consisting of the thermal and the waterjet beams was produced because of this arrangement. The feasibility of using the …

A Biomechanical Analysis Of Three Humeral Fracture Fixation Systems, Alina Michelle Waite

Theses

Often, humeral fractures requiring internal fixation can be a challenging orthopaedic procedure. Each method of treatment possesses clinical and biomechanical advantages and disadvantages. Rigid plate fixation is highly successful in treating a large variety of long bone fractures. Nevertheless, excessive soft tissue dissection is necessary, and vascular and neural anatomy of the humerus can make plate application and removal difficult. An intramedullary nail offers a relatively simple procedure, thereby reducing these anatomical concerns. However, rotational instability at the fracture site is a common complication with a conventional intramedullary nail. Thus, a study was conducted to evaluate a new interlocking intramedullary …

An Approach To Improving The Antithrombogenesis Of Pneumatic Diaphragm Artificial Ventricle : Fabrication And Design Considerations, Hui-Sun Wang

Theses

Thrombus formation is one of the major problems in artificial heart development and its clinical applications. In order to improve the antithrombogenesis in the artificial ventricles, three aspects of investigation have been done in the laboratory.

1] the surface features and the surface defects on specially prepared samples made of polyurethane and silicon rubber were studied and analyzed by scanning electron microscopy ( SEM ), light microscopy and KEVEX Feature Analysis for understanding and controlling the blood contacting surface.

2] the polyurethane blood contacting surface with smooth surface fabricated by solution cast process, the material treatment, and the fabrication procedure …

Graded Buried Channel Charge Coupled Device Design, Zengjing Wu

Theses

A process and device simulation study has been made to optimize a new type of buried channel CCD (BCCD) structure to be referred to as Graded BCCD (GBCCD) whose buried channel is formed by multiple implantations for achieving higher charge transfer efficiency. The 2-D process simulation tool SUPREM4 and 2-D device simulation tool PISCES2 were used in this research. The simulation results of the GBCCD with double channel implants are compared with the previously obtained experimental results.

Triple channel implants under the conditions of various process parameters were also simulated and the optimized case was chosen on the base of …

A Three-Dimensional Finite Element Stress Analysis Of Interface Conditions In Porous Coated Hip Prosthesis, Siu-For Yau

Theses

A three-dimensional finite element model of a collar-type hip stem and both the cortical and cancellous bones is used to investigate the stress distributions on an implanted femoral stem, adjacent bone, and specifically at the bone/implant interface for various amounts of porous coating and different stem materials. The finite element model consists of 909 nodes comprising 536 linear eight-node solid brick elements and 176 two-node interface elements. The finite element analysis code employed is SUPERTAB from SDRC. The interface elements consist of coincident-node spring elements and gap elements which model the rigidly bonded and loose interfaces respectively. Local coordinate systems …

Mobile Manipulator Path Planning By A Genetic Algorithm, Min Zhao

Theses

The thesis addresses the path planning problem for a mobile manipulator system which is used to perform a sequence of tasks specified by locations and minimum oriented force capabilities. The problem is to find an optimal sequence of base positions and manipulator configurations for performing a sequence of tasks given a series of task specifications. The formulation of the problem is nonlinear. The feasible regions for the problem are nonconvex and unconnected. Genetic algorithms applied to such problems appear to be very promising while traditional optimization methods cause difficulties. Computer simulation is carried out on a three degrees-of-freedom manipulator mounted …

Mobile Robot Path Planning Based On Hierarchical Hexagonal Decomposition, Dan Zheng

Theses

In this thesis, a new algorithm based on hierarchical cell decomposition and artificial potential field is developed to solve the find-path problem for a mobile robot. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented.

Nontraditional Machining Techniques With Emphasis On Waterjet Milling, Shiv K. Kunapuli

Theses

The rapid growth of harder and difficult-to-machine materials over the past two decades necessitates the development of compatible nonconventional machining techniques, as detailed in this work, with special emphasis on one of the most recent machining method, the abrasive-waterjet technique(AWJ).

The feasibility of using AWJ for milling on glass is investigated. Due to the large number of parameters involved in the AWJ technique, and the multitude of machining requirements, optimization of performance is the focus. These parameters include waterjet pressure, particle size, abrasive flow rate, traverse rate and number of passes.

Surface topography is found to be a function of …

The Performance Evaluation Of A New Neural Network Based Traffic Management Scheme For A Satellite Communication Network, Dequan Liu

Theses

The thesis describes a new neural network based traffic management scheme for a satellite communication network. The scheme consists of two levels of management. The front end of the scheme is a derivation of the Kohonen's self-organization model to configure maps for the satellite communication network dynamically, The model consists of three stages. The first stage is the pattern recognition task which selects an exemplar map that best meets the current network requirements. The second stage analyzes the discrepancy between the chosen exemplar map and the state of the network, and adaptively modifying the chosen exemplar map to conform closely …