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Articles 170551 - 170580 of 198086

Full-Text Articles in Engineering

Analysis Of Cost Growth In Us Air Force Base Support Function Contracts, James S. Romasz Mar 1999

Analysis Of Cost Growth In Us Air Force Base Support Function Contracts, James S. Romasz

Theses and Dissertations

The United States Air Force (USAF) has outsourced a significant portion of their activities defined as commercial activities and plans to aggressively outsource more in the future. The USAF outsources its commercial activities in the form of multi-year contracts to the private sector. Cost growth (either negative or positive) has been experienced by most of these contracts. This research effort performed a review of current literature and used statistical analysis to clarify the issue: what are the causes, and extent of cost growth in USAF base-support-function contracts?. From the literature, it can be concluded that changes to the statement of …

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Natural Attenuation Of Chlorinated Ethenes By Anaerobic Reductive Dechlorination Coupled With Aerobic Cometabolism, Derek D. Veerkamp Mar 1999

Natural Attenuation Of Chlorinated Ethenes By Anaerobic Reductive Dechlorination Coupled With Aerobic Cometabolism, Derek D. Veerkamp

Theses and Dissertations

Chlorinated solvents and their daughter products are the most common contaminants of groundwater at industrial and military facilities in the United States. Limitations of conventional technologies have intensified efforts to find alternative methods to remediate contaminated sites to regulatory goals set by CERCLA. Natural attenuation of chlorinated solvents is a promising alternative to traditional pump and treat methods but has not been well understood or widely accepted. This modeling study investigated the ability of TCE to completely degrade under various aquifer conditions and rate order constants. It also examined a case study of a former landfill site at Moody AFB. …

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Analysis Of Radio Frequency Interference Effects On A Modern Coarse Acquisition Code Global Positioning System (Gps) Receiver, Kenneth D. Johnston Mar 1999

Analysis Of Radio Frequency Interference Effects On A Modern Coarse Acquisition Code Global Positioning System (Gps) Receiver, Kenneth D. Johnston

Theses and Dissertations

The purpose of this thesis was to investigate the performance of a twelve channel Standard Positioning Service (SPS) based (Global Positioning System (GPS) receiver using an eight state Kalman filter in a hostile radio frequency (RF) environment and to develop instructional tools for teaching RF interference on GPS receivers. The two types of jamming signals generated included Continuous Wave (CW) and Swept CW. Actual GPS and jamming signals were used in the research. The signals received from GPS satellites exhibit a Doppler shift which vary between approximately plus six Kilohertz. The Doppler shift frequency can be reasonably predicted for a …

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Visualizing Early-Stage Breast Cancer Tumors In A Mammographic Environment Through A 3-Dimensional Mathematical Model, Christopher B. Bassham Mar 1999

Visualizing Early-Stage Breast Cancer Tumors In A Mammographic Environment Through A 3-Dimensional Mathematical Model, Christopher B. Bassham

Theses and Dissertations

In response to the insidious and deadly nature of breast cancer and the less-than-perfect detection ability of mammography, we develop a mathematical model as a foundation to the long-term goal of improving early breast cancer detection. By using modeling and simulation to construct an accurate breast cancer tumor model, we hope to solve the problems associated with mammogram misdiagnosis and, perhaps as a by-product, lend insight to tumor development dynamics. The final tumor model, written in MATLAB, provides realistic tumor growth and 2-dimensional visualization of 3-dimensional structures. Earlier modeling attempts capture slices of the tumor in the 2-dimensional growth spaces. …

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A Bayesian Decision Model For Battle Damage Assessment, Daniel W. Franzen Mar 1999

A Bayesian Decision Model For Battle Damage Assessment, Daniel W. Franzen

Theses and Dissertations

Battle damage assessment (BDA) is critical to success in any air campaign. However, Desert Storm highlighted numerous deficiencies in the BDA process, and operations since Desert Storm continue to point out weaknesses. We present a review of the Phase I BDA decision, or physical damage assessment, and model the decision process using a Bayesian belief network. Through subject matter expert (i.e., the targeteers) elicitation sessions, imagery was found to be critically important to the BDA process yet this information is generally not retained. This use of "perfect information" is delineated in the BDA process models. We proposed a methodology based …

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An Evaluation And Comparison Of The Ace And Brace Airfield Models, David W. Wiliams Mar 1999

An Evaluation And Comparison Of The Ace And Brace Airfield Models, David W. Wiliams

Theses and Dissertations

Airfields are a critical aspect of our military's ability to project power or respond to crises throughout the world. It is crucial that mobility planners have an effective means to estimate the capacity of these airfields. The objective of this research is to examine common mobility metrics and evaluate existing means of measuring them. Currently, Air Mobility Command has two models, the Airfield Capacity Estimator (ACE) and the Base Resource and Capabilities Estimator (BRACE), that were designed to estimate the resource requirements and capacities of an airfield. This study offers a critical evaluation and comparison of the two models. Discrepancies …

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The Quota Allocation Model: The Linear Optimization Of A Markov Decision Process, David A. Brown Mar 1999

The Quota Allocation Model: The Linear Optimization Of A Markov Decision Process, David A. Brown

Theses and Dissertations

One of the many needs of the Air Force is advanced technical degrees. These degrees can be acquired in three ways: the Air Force can directly recruit personnel with the required degrees; Air Force personnel can obtain them during off duty time from local civilian colleges near their base; or the Air Force can provide advanced academic degrees (AADs) through the Air Force Institute of Technology (AFIT) or AFIT-sponsored programs. In 1995, the AFIT Commandant initiated a re-engineering study to review the AFIT mission. One of the initiatives of that study was the Quota Allocation Model (QuAM). The QuAM model …

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Development Of Site Characterization Simulator, Neil W. Kassel Mar 1999

Development Of Site Characterization Simulator, Neil W. Kassel

Theses and Dissertations

The purpose of this study was to develop a tool for Remedial Project Managers (RPMs) to learn and practice the site characterization process. One of the key difficulties encountered by RPMs during site characterization is the need to develop a model of the site based on limited data. These limited data are used to determine parameters that describe hydrogeologic and contaminant properties (aquifer hydraulic conductivity, contaminant concentration, etc.) and are obtained using sampling techniques that interrogate a very small volume, usually much smaller than node spacing of the computer model used to simulate site conditions. The value of the parameter …

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Individual Housing Choices Among Air Force Members, Michael J. Johnson Mar 1999

Individual Housing Choices Among Air Force Members, Michael J. Johnson

Theses and Dissertations

Air Force members have three different housing choices: live in MFH, rent in the local community, or buy a house in the local community. A set of six constructs (Housing Attributes, Safety, Pet Importance, Location, Military Housing Perception, and Community) that encompass members' considerations is developed and analyzed. The data was extracted from a survey that was specifically designed to illicit the relative importance of each construct during the housing decision making process. Each construct was measured using a Likert scale score. Statistical analysis was performed to determine the overall Likert mean score for each construct. Using the Likert mean …

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Modeling And Analysis Of Aerial Port Operations, Timothy W. Albrecht Mar 1999

Modeling And Analysis Of Aerial Port Operations, Timothy W. Albrecht

Theses and Dissertations

The focus of this thesis effort is gaining useful insight into aerial port operations by employing an animated simulation. Understanding airfield capacity, resources, and functioning allows greater accuracy and efficiency in both planning for future force structures and matching mobility assets with commanders' objectives. Two current simulations, ACE (Airfield Capacity Estimator) and BRACE (Base Resource Allocation and Capabilities Estimator), model mobility activities at the base level with some deficiencies. The model proposed by this thesis, APOM (Aerial Port Operations Model), will provide the mobility analyst an animated simulation with two, new measures of aerial port operations; a real-time estimate of …

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Dynamic Unmanned Aerial Vehicle (Uav) Routing With A Java-Encoded Reactive Tabu Search Metaheuristic, Kevin P. O'Rourke Mar 1999

Dynamic Unmanned Aerial Vehicle (Uav) Routing With A Java-Encoded Reactive Tabu Search Metaheuristic, Kevin P. O'Rourke

Theses and Dissertations

In this paper we consider the dynamic routing of unmanned aerial vehicles (UAVs) currently in operational use with the US Air Force. Dynamic vehicle routing problems (VRP) have always been challenging, and the airborne version of the VRP adds dimensions and difficulties not present in typical ground-based applications. Previous UAV routing work has focused on primarily on static, pre-planned situations; however, scheduling military operations, which are often ad-hoc, drives the need for a dynamic route solver that can respond to rapidly evolving problem constraints. With these considerations in mind, we examine the use of a Java-encoded metaheuristic to solve these …

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Decision Analysis Methodology To Evaluate Organization, Shawn C. Thompson Mar 1999

Decision Analysis Methodology To Evaluate Organization, Shawn C. Thompson

Theses and Dissertations

The organizational structure of the civil engineer squadron's operations flight has undergone numerous changes over the last fifty years. Today the structure of the flight to the element level is mandated by Air Force Instructions; however, each unit is given the flexibility to organize below the element level. Most civil engineer units are struggling through the decision of how to organize their flights without a sound methodology to guide their efforts. Providing such a methodology is the objective of this thesis. To accomplish the objective, the history behind the operations flight structure was researched. In addition to this historical research, …

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Strategic Effects Of Airpower And Complex Adaptive Agents: An Initial Investigation, Thomas R. Tighe Mar 1999

Strategic Effects Of Airpower And Complex Adaptive Agents: An Initial Investigation, Thomas R. Tighe

Theses and Dissertations

US airpower theory and doctrine depend on the concept that the destruction of a few key targets or centers of gravity can unravel the enemy's physical ability to wage war or break his will to prosecute the war. This synergistic decimation of the enemy's effectiveness and resistance to our political will is known as Strategic Effects. These strategic effects are very difficult to quantify and are not directly accounted for in current DoD computer models. Since these computer models are used to aid with decisions about force structure and budget priorities, many believe that the Air Force's greatest potential contribution …

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Sorption Of The Aircraft Deicing Fluid Component Methyl-Benzotriazole In Soil, David L. Kellner Mar 1999

Sorption Of The Aircraft Deicing Fluid Component Methyl-Benzotriazole In Soil, David L. Kellner

Theses and Dissertations

The air transportation industry requires deicing/anti-icing (ADAF) fluids to maintain flight operations in cold weather conditions. Additives to the ADAF aid in the performance of these agents. Approximately 52M liters of concentrated aircraft deicing fluid are used in North America per year in an attempt to correct this safety problem. Among the additives to ADAF are corrosion inhibitors flame retardants, wetting agents, and thickening agents. Some of these agents are known to be toxic to microorganisms. Identification of the transport processes of these agents in the environment is a necessary first step to understanding how to remediate ADAF. Methyl-Benzotriazole (MeBT) …

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Implementation Of The Metaheuristic Tabu Search In Route Selection For Mobility Analysis Support System, David M. Ryer Mar 1999

Implementation Of The Metaheuristic Tabu Search In Route Selection For Mobility Analysis Support System, David M. Ryer

Theses and Dissertations

This thesis employs a reactive tabu search heuristic implemented in the Java programming language to solve a real world variation of the vehicle routing problem with the objective of providing quality routes to Mobility Analysis Support System (MASS). MASS is a stochastic simulation model used extensively by Air Mobility Command (AMC) to analyze strategic airlift capabilities and future procurement decisions. This dynamic real world problem of strategic and tactical airlift possesses a number of side constraints such as vehicle capacities, route length and time windows in a sizeable network with multiple depots and a large fleet of heterogeneous vehicles. Finding …

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Pilot Inventory Complex Adaptive System (Picas): An Artificial Life Approach To Managing Pilot Retention, Martin P. Gaupp Mar 1999

Pilot Inventory Complex Adaptive System (Picas): An Artificial Life Approach To Managing Pilot Retention, Martin P. Gaupp

Theses and Dissertations

The retention of skilled pilots continues to be a problem that plagues the United States Air Force. After spending millions of dollars on training and education, it is disheartening to see the mass exodus of experienced aviators from the Air Force that has been occurring in the past decade. Many blame the economy, others the Air Force itself but few are able to accurately predict how or why they are all leaving. The current personnel models do not adequately determine retention rates. Complex adaptive systems theory, however, might provide some insight. By modeling the system at the pilot's level, allowing …

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An Approach For Tasking Allocated Combat Resources To Targets, David A. Koewler Mar 1999

An Approach For Tasking Allocated Combat Resources To Targets, David A. Koewler

Theses and Dissertations

Tasking allocated combat aircraft to strike targets is a complicated and time-consuming process for combat planners. Currently, the process of scheduling missions is a two to four day process. To be able to respond quickly to the changing conditions of the battlefield, the military needs to compress the time that this process requires. Despite efforts to develop computer-based tools to automatically plan missions, combat planners still manually perform most of the tasking and scheduling of aircraft and targets. Unfortunately some of the tools currently available are perceived to be complicated and time consuming to use by the planners. They also …

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A Comparison Of Genetic Algorithm Parametrization On Synthetic Optimization Problems, Mehmet Eravsar Mar 1999

A Comparison Of Genetic Algorithm Parametrization On Synthetic Optimization Problems, Mehmet Eravsar

Theses and Dissertations

Meta-heuristics have been deployed to solve many hard combinatorial and optimization problems. Parameterization of meta-heuristics is an important challenging aspect of meta-heuristic use since many of the features of these algorithms cannot be explained theoretically. Experiences with Genetic Algorithms (GA) applied to Multidimensional Knapsack Problems (MKP) have shown that this class of algorithm is very sensitive to parameterization. Many studies use standard test problems, which provide a firm basis for study comparisons but ignore the effect of problem correlation structure. This thesis applies GA to MKP. A new random repair operator, which projects infeasible solutions into feasible region, is proposed. …

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Selection Of Psychophysiological Features Across Subjects For Classifying Workload Using Artificial Neural Networks, Trevor I. Laine Mar 1999

Selection Of Psychophysiological Features Across Subjects For Classifying Workload Using Artificial Neural Networks, Trevor I. Laine

Theses and Dissertations

The issue of pilot workload is important to the United States Air Force because pilot overload or task saturation leads to decreases in mission effectiveness. Additionally, in the most extreme cases, pilot overload may lead to the loss of aircraft and crewmember lives. Current research efforts are utilizing psychophysiological data including electroencephalography (EEG), cardiac, eye-blink, and respiration measures in an attempt to identify workload levels. The primary focus of this effort is to determine if a single parsimonious set of psychophysiological features exists for accurately classifying workload levels between multiple test subjects. To accomplish this objective, the signal-to-noise (SNR) saliency …

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Using Simulation To Model The Army Recruiting Station With Multi-Quality Prospects, Edward L. Mclarney Mar 1999

Using Simulation To Model The Army Recruiting Station With Multi-Quality Prospects, Edward L. Mclarney

Theses and Dissertations

This thesis explores the application of simulation to the Army Recruiting Station. Included are the effects of leadership styles and policies, the effects of recruiters with different personality types, and differences in processing for varying types of recruits. Research included heavy emphasis into determining the effects of leadership on recruiter productivity. In addition, major changes were made to a previous simulation model. The changes allowed current research to be implemented into the simulation. This research is intended to help the United States Army Recruiting Command better understand how changes in the recruiting process and in leadership policies affect productivity.

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Quality Function Deployment From An Operations Research Perspective, Eve M. Burke Mar 1999

Quality Function Deployment From An Operations Research Perspective, Eve M. Burke

Theses and Dissertations

The methodology of Quality Function Deployment (QFD) is compared to operations analysis standards. Of special concern is how Air Combat Command (ACC) uses QFD for the Modernization Planning Process (MPP). ACC digresses from the traditional use of QFD for incorporating quality into manufacturing processes to use it as a planning tool. ACC's goal in implementing QFD is to incorporate the demands of the Air Force mission into the modernization planning effort. ACC's use of QFD to identify and quantify current deficiencies and quantify the value of alternative future solutions has led to the investigation of inconsistencies with QFD, both generally …

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A Validation Assessment Of Thunder 6.5'S Intelligence, Surveillance, And Reconnaissance Module, Francine N. Nelson Mar 1999

A Validation Assessment Of Thunder 6.5'S Intelligence, Surveillance, And Reconnaissance Module, Francine N. Nelson

Theses and Dissertations

A validation assessment of THUNDER 6.5's Intelligence, Surveillance, and Reconnaissance (ISR) module is accomplished using formulational and experimental validation techniques. A comparison of ISR purposes and processes according to military doctrine is made with the purposes and processes of ISR implemented within THUNDER 6.5. This comparison provides an overview of the process, an understanding of the level of aggregation within THUNDER, insight into possible problem areas in THUNDER, and a basis for improving THUNDER ISR processes. Sensitivity analysis of the ISR parameters as they relate to the Quality, Quantity, and Timeliness of ISR is also presented to provide insight into …

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Portfolio Selection Of Innovative Technologies Via Life Cycle Cost Modeling, Scott C. Naylor Mar 1999

Portfolio Selection Of Innovative Technologies Via Life Cycle Cost Modeling, Scott C. Naylor

Theses and Dissertations

High technology firms are faced with the dilemma of deciding which products to develop, which generations of technology to pass over, and which products to skip entirely. As competition among these firms increases and the life cycles of technological products shorten, there exists a great deal of pressure to bring products rapidly to the market. As a result, recouping the costs of research and development (R & D) and earning a profit becomes increasingly uncertain. Traditional life cycle cost models do not directly address shortened life cycles, time to market, or learning curve issues; all are critical factors in the …

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Solving The Multidimensional Multiple Knapsack Problem With Packing Constraints Using Tabu Search, Jonathan M. Romaine Mar 1999

Solving The Multidimensional Multiple Knapsack Problem With Packing Constraints Using Tabu Search, Jonathan M. Romaine

Theses and Dissertations

This paper presents a methodology for solving military aircraft load-scheduling problems modeled as a multidimensional multiple knapsack problem, Because of the computational time associated with applying conventional algorithms to this type of problem, we employ tabu search to determine how much cargo a heterogeneous group of aircraft can carry. This study extends the previous work of Chocolaad in two areas. First, we modify Chocolaad's algorithms to solve the multiple (rather than the single) knapsack problem under the constraints he defined for the Airlift Loading Problem. Second, we drop his assumption of a homogeneous group of aircraft. We validate our model …

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A Value Focused Approach To Determining The Top Ten Hazards In Army Aviation, Brian K. Sperling Mar 1999

A Value Focused Approach To Determining The Top Ten Hazards In Army Aviation, Brian K. Sperling

Theses and Dissertations

The United States Army Safety Center is challenged with identifying the top ten most severe hazards in Army Aviation. This research utilizes value-focused thinking and multiattribute preference theory concepts to produce a decision analysis model designed to aid decision-makers in their analysis process. The severity model is based on the Army's Risk Management doctrinal manual and has been tailored specifically for aviation related accidents and hazards. The model determines the severity and risk ranking for 65 categories of accidents and 24 existing hazards. A sensitivity analysis is conducted to examine the effects of variations in the weights of the top-level …

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Unmanned Aerial Vehicle Mission Level Simulation, Jennifer G. Walston Mar 1999

Unmanned Aerial Vehicle Mission Level Simulation, Jennifer G. Walston

Theses and Dissertations

We develop an object-oriented simulation that models the surveillance and Active Suppression of Enemy Air Defense (SEAD) missions of the Unmanned Aerial Vehicle (UAV) RQ-1A Predator. The simulation, written in Java using the Silk simulation package, interfaces with a Reactive Tabu Search routing algorithm to provide optimal UAV routes. The routing algorithm is called by the simulation to account for changes in weather conditions and to provide a means of dynamically retasking the UAV. The simulation and analysis support a UAV Battlelab initiative to test the operational effects of proposed changes in Predator performance and UAV capability to perform in …

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A Comparative Analysis Of The Iridium® And Globalstar® Satellite Transmission Paths, Kenneth E. Crowe Mar 1999

A Comparative Analysis Of The Iridium® And Globalstar® Satellite Transmission Paths, Kenneth E. Crowe

Theses and Dissertations

Globalstar and Iridium will provide valuable global communications assets for business, humanitarian aid and military operations. However, the level of coverage and the quality of the transmission path of these systems are strongly dependent on the latitude of the user and, due to their orbital characteristics, both systems provide reduced levels of coverage at low latitudes. Additionally, the L- and S-Band frequencies utilized by these systems are prone to ionospheric interference at low latitudes. The results of extensive simulation analysis indicate that the Globalstar constellation architecture provides a considerably better transmission path than Iridium's in several important areas, including path …

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Technology Selection For The Air Force Research Laboratory Air Vehicles Directorate: An Analysis Using Value Focused Thinking, Michael F. Winthrop Mar 1999

Technology Selection For The Air Force Research Laboratory Air Vehicles Directorate: An Analysis Using Value Focused Thinking, Michael F. Winthrop

Theses and Dissertations

A technology selection model was developed for the Air Vehicles Directorate of Air Force Research Laboratory. The model was developed and demonstrated to aid in addressing the question of what technologies Air Vehicles' should invest in to remain consistent with Air Force values. Both Value-Focused Thinking and optimization approaches were used to identify the value of Air Vehicles technology, to provide insights to Air Vehicles' decision-makers, to determine where value gaps might exist with the scored alternatives, and to determine how sensitive the model was to changes. As a demonstration of the approach, seven technologies were scored, representing all three …

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A New Sequential Goodness-Of-Fit-Test For The Three-Parameter Weibull Distribution With Known Shape Parameter Value Based On Skewness And Q-Statis G.O.F. Test Statistics, Tibet Memis Mar 1999

A New Sequential Goodness-Of-Fit-Test For The Three-Parameter Weibull Distribution With Known Shape Parameter Value Based On Skewness And Q-Statis G.O.F. Test Statistics, Tibet Memis

Theses and Dissertations

Due to its flexibility, the Weibull distribution has very wide applicability in a lot of disciplines and is very prevalent in reliability theory. Thus, a lot of statistical tests that generally have a substantial degree of computational complexity have been developed to determine if the data at hand can be represented with this distribution. This research presents a new omnibus goodness-of-fit test (G.O.F.) that has less computational complexity than the existing tests for the three-parameter Weibull distribution using a sequential application of two individual tests, sample skewness and Q-Statistic. A Monte Carlo procedure has been employed to generate critical values …

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A New Sequential Goodness Of Fit Test For The Three-Parameter Gamma Distribution With Known Shape Based On Skewness And Kurtosis, Chil Ho Park Mar 1999

A New Sequential Goodness Of Fit Test For The Three-Parameter Gamma Distribution With Known Shape Based On Skewness And Kurtosis, Chil Ho Park

Theses and Dissertations

This research presents a new sequential goodness of fit test for the three-parameter gamma distribution with a known shape. The test is accomplished by employing two new tests, sample skewness and sample kurtosis, sequentially as test statistics. Unlike the typical goodness of fit test, using parameter estimation methods such as maximum likelihood estimation and minimum distance estimation, this test using the two test statistics above does not involve a substantial degree of computational complexity. Large Monte Carlo simulation has been used to determine critical values and overall significance levels for all combinations of the two tests, and to conduct extensive …

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