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Articles 67921 - 67950 of 77979

Full-Text Articles in Engineering

Nested Fork-Join Queuing Networks And Their Application To Mobility Airfield Operations Analysis, Craig J. Willits Mar 1997

Nested Fork-Join Queuing Networks And Their Application To Mobility Airfield Operations Analysis, Craig J. Willits

Theses and Dissertations

A single-chain nested fork-join queuing network (FJQN) model of mobility airfield ground processing is proposed. In order to analyze the queuing network model, advances on two fronts are made. First, a general technique for decomposing nested FJQNs with probabilistic forks is proposed, which consists of incorporating feedback loops into the embedded Markov chain of the synchronization station, then using Marie's Method to decompose the network. Numerical studies show this strategy to be effective, with less than two percent relative error in the approximate performance measures in most realistic cases. The second contribution is the identification of a quick, efficient method …

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Numerical And Experimental Investigation Of The Flowfield Near A Wrap-Around Fin, Carl P. Tilmann Mar 1997

Numerical And Experimental Investigation Of The Flowfield Near A Wrap-Around Fin, Carl P. Tilmann

Theses and Dissertations

A wall-mounted semi-cylindrical model fitted with a single wrap-around fin (WAF) has been investigated both numerically and experimentally, with the objective of characterizing the mean and turbulent flowfield in the vicinity of the fin. Numerical and experimental results are used to determine the nature of the flowfield and quantify the effects of fin curvature on the character of the flow near WAFs. This research has been motivated by the need to identify possible sources of a rolling moment reversal observed at high speeds in sub-scale flight tests. Detailed mean flow and turbulence measurements were obtained in the AFIT Mach 3 …

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Advances In Time-Domain Electromagnetic Simulation Capabilities Through The Use Of Overset Grids And Massively Parallel Computing, Douglas C. Blake Mar 1997

Advances In Time-Domain Electromagnetic Simulation Capabilities Through The Use Of Overset Grids And Massively Parallel Computing, Douglas C. Blake

Theses and Dissertations

A new methodology is presented for conducting numerical simulations of electromagnetic scattering and wave propagation phenomena. Technologies from several scientific disciplines, including computational fluid dynamics, computational electromagnetics, and parallel computing, are uniquely combined to form a simulation capability that is both versatile and practical. In the process of creating this capability, work is accomplished to conduct the first study designed to quantify the effects of domain decomposition on the performance of a class of explicit hyperbolic partial differential equations solvers; to develop a new method of partitioning computational domains comprised of overset grids; and to provide the first detailed assessment …

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Modern Flight Control Design, Implementation, And Flight Test, Phillip T. Edwards Mar 1997

Modern Flight Control Design, Implementation, And Flight Test, Phillip T. Edwards

Theses and Dissertations

This thesis addresses the application issues raised implementing flight control designs derived from optimal control theory and the challenges in obtaining acceptable handling qualities when using these techniques. Using the USAF TPS FCS project as the controller architecture, four controllers were designed using classical methods, and H2, H3, and mixed H2/H optimal control theory. These designs were implemented in the Calspan VSS II Learjet, simulating unstable aircraft longitudinal dynamics and a limited handling qualities flight test evaluation was performed. The design phase found the optimal control techniques, as applied, difficult to design to handling qualities specifications. The H2, H3 and …

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The Effects Of Elevator Rate Limiting And Stick Dynamics On Longitudinal Pilot-Induced Oscillations, Patrick J. Peters Mar 1997

The Effects Of Elevator Rate Limiting And Stick Dynamics On Longitudinal Pilot-Induced Oscillations, Patrick J. Peters

Theses and Dissertations

This report presents the results of an investigation into the effects of elevator rate limiting and stick dynamics on longitudinal pilot-induced oscillations (PIO). A simulation study was conducted to prepare for the flight test, but also to gain insight into the effects of rate limiting and stick dynamics. Due to the non-numerical nature of the simulation results, a flexible three-phase flight test plan was developed, first varying the rate limits, then varying the stick dynamics, and finally flying a matrix determined in the first two phases. There were three major conclusions. First, the offset landing task flown was insufficient to …

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A Framework For An Automated Compilation System For Reconfigurable Architectures, George R. Roelke Iv Mar 1997

A Framework For An Automated Compilation System For Reconfigurable Architectures, George R. Roelke Iv

Theses and Dissertations

The advent of the Field Programmable Gate Array has allowed the implementation of runtime reconfigurable computer systems. These systems are capable of configuring their hardware to provide custom hardware support for software applications. Since these architectures can be reconfigured during operation, they are able to provide hardware support for a variety of applications, without removal from the system. The Air Force is currently investigating reconfigurable architectures for avionics and signal processing applications. This thesis investigates the problem of automating the application development process for reconfigurable architectures. The lack of automated development support is a major limiting factor in the use …

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Sensitivity Analysis Of A Combat Simulation Using Response Surface Methodology, William J. Berg Mar 1997

Sensitivity Analysis Of A Combat Simulation Using Response Surface Methodology, William J. Berg

Theses and Dissertations

This thesis provides a methodology to analyze the sensitivity of a combat simulation relative to the capabilities of the modeled weapon systems. Response Surface Methodology (RSM) was the primary technique used for analysis. A ground battle scenario was developed with a commercial PC wargame Empire II: The Art of War(TM). In the computer verses computer mode, the wargame was transformed into a combat simulation'. A screening experiment was used to determine which of an original 23 weapon factors were actually significant to this scenario. After analyzing the remaining five factors, only three ended up as truly significant to the battle …

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Ranking And Generating Alternatives For The National Air Intelligence Center's (Naic) Resource Allocation Strategy, Steven M. Cox Mar 1997

Ranking And Generating Alternatives For The National Air Intelligence Center's (Naic) Resource Allocation Strategy, Steven M. Cox

Theses and Dissertations

Allocating resources is never an easy task, especially when requirements call for more resources than those available. It gets more difficult when the availability of resources shrinks from year to year. This is the case at the National Air Intelligence Center (NAIC). In each of the past five years, NAIC has been forced to make their resource allocation decision with fewer dollars and less manpower. This decision has been time consuming, manpower intensive, and sometimes very heated. In an effort to lessen these three consequences, a resource allocation model, based upon the NAIC Commander's values and preferences, was developed. The …

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Modeling Mirv Footprint Constraints In The Weapons Assignment Model, Elliot T. Fair Mar 1997

Modeling Mirv Footprint Constraints In The Weapons Assignment Model, Elliot T. Fair

Theses and Dissertations

US Strategic Command (USSTRATCOM) is developing a new linear programming model called the Weapons Assignment Model (WAM) to perform weapons assignment for the Strategic Integrated Operations Plan (SIOP). One of the major improvements WAM will have over its predecessor is the ability to include Multiple Independently Targetable Reentry Vehicle (MIRV) footprinting constraints in the optimization process. In order to include MIRV footprint constraints in WAM, a methodology is needed to model the MIRV footprints in a manner that is consistent with the limitations of linear programming. Two techniques for modeling MIRV footprints were developed. The first, Geometric Approximation (GA), uses …

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Modeling A Chemical Battlefield And The Resulting Effects In A Theater-Level Combat Model, Todd M. Gesling Mar 1997

Modeling A Chemical Battlefield And The Resulting Effects In A Theater-Level Combat Model, Todd M. Gesling

Theses and Dissertations

This thesis describes the development of a methodology to model chemical weapons use in the Joint Staff's Joint Warfare Analysis Experimental Prototype (JWAEP) and to quantify the resulting effects. The methodology incorporates organic unit assets and theater-level chemical assets into JWAEP by using the three principles of nuclear, biological, and chemical defense (NBC) which reflect joint and Army doctrine, and combines them with the basic concepts already used in existing theater-level models. Other aspects of the problem include representing chemical 'packages' on the battlefield, determining attrition and time effects, adjusting unit effectiveness, determining chemical package intelligence acquisition procedures, identifying solution …

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Linking Procurement Dollars To An Alternative Force Structures' Combat Capability Using Response Surface Methodology, James B. Grier Mar 1997

Linking Procurement Dollars To An Alternative Force Structures' Combat Capability Using Response Surface Methodology, James B. Grier

Theses and Dissertations

A General Officer Steering Group, chaired by HQ USAF/XOM tasked action to develop and implement evaluation and analysis support to lead turn' the Program Objective Memorandum (POM) and Joint Warfare Capability Assessment (JWCA) process. This evaluation process should be designed to supply measures of the 'health' of the Air Force program in light of the Defense Planning Guidance (DPG) and the Chairman's Program Assessment (CPA). The Air Force needs to be able to quickly evaluate various alternative force structures with regards to its combat capability, measured in terms of theater level campaign objectives (CO). HQ USAF/XOM tasked HQ USAF/XPY to …

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A Decision Support System For Joint Force Air Component Commander (Jfacc) Combat Planning, Donald W. Hinton Mar 1997

A Decision Support System For Joint Force Air Component Commander (Jfacc) Combat Planning, Donald W. Hinton

Theses and Dissertations

This system allows assessment of the Master Air Attack Plan (MAAP) during construction and at completion. The system functions around a relational database management system providing a decision support tool for the Guidance, Apportionment, & Targeting (GAT) cell of Central Command's JFACC Combat Plans. A Microsoft Access application is programmed to provide PC-based, real time evaluation of air campaign goals and constraints. The decision support system was validated in February 1997 by the CENTAF combat plans staff at Blue Flag 97-1. The software and user's manual are maintained at HQ ACC/XP-Studies and Analysis Squadron.

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Simulation Model Of Fighter Pilot Assignment Process, Anthony J. Hutfles Mar 1997

Simulation Model Of Fighter Pilot Assignment Process, Anthony J. Hutfles

Theses and Dissertations

This thesis analyzes the effect Continental United States (CONUS) Time on Station (TOS) has on filling critical rated assignments. A SIMSCRIPT II.5 simulation model of the F15 and F16 pilots assignment process was developed. The simulation tested the effect of changing CONUS TOS from 3 years to 6 years in half year increments. Analysis of the number of unfilled rated assignments from simulation runs of 10 years in length indicated that changing CONUS TOS by itself has no statistically significant effect on model's output. The analysis was expanded to a 2(2) factorial experimental design using CONUS TOS and Total Active …

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Tool Condition Monitoring: A Computational Approach, Anthony Clinch Mar 1997

Tool Condition Monitoring: A Computational Approach, Anthony Clinch

Dissertations and Theses

Tool Condition Monitoring offers a new approach to reducing the costs associated with catastrophic tool failure. The manufacturing process is becoming more computationally oriented all the time. Computational methods of determining the condition of cutting tools will lend themselves to easy integration with current and forthcoming manufacturing techniques. Coupling the results of this computational approach with a cost analysis will provide a means of maximizing the investment in cutting tools, while minimizing the damage caused by tool failure. Tool Condition Monitoring, as defined here, is a method of computationally determining the condition of a cutting tool. The problem of determining …

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Selecting A Health Care Option For Military Beneficiaries That Minimizes Health Care Costs While Maintaining Personal Desires For Choice, Norman H. Pallister Mar 1997

Selecting A Health Care Option For Military Beneficiaries That Minimizes Health Care Costs While Maintaining Personal Desires For Choice, Norman H. Pallister

Theses and Dissertations

Tricare, the triservice, triple-option, managed care plan for the uniformed services, incorporates a managed care support contract to complement Military Treatment Facilities. Currently being implemented throughout the CONUS, Tricare provides more equitable health care service to all military beneficiaries, improved access to care, a reduction in health care costs, and provides beneficiaries with an expanded choice of medical-care providers. This thesis examines the Tricare program and reviews relevant health care literature, both military and civilian. Using these inputs, the author presents a deterministic decision analysis model that allows a military beneficiary to select a health care option that minimizes his …

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An Object Oriented Simulation Of The C-17 Wingtip Vortices In The Airdrop Environment, Hans J. Petry Mar 1997

An Object Oriented Simulation Of The C-17 Wingtip Vortices In The Airdrop Environment, Hans J. Petry

Theses and Dissertations

This thesis effort focuses on the development of an object-oriented simulation of C-17 personnel airdrop operations and provides a tool for risk assessment of jumper and wingtip vortex interaction. Using the initial modeling efforts of the Wright Laboratory, this model expands those efforts to include random aircraft, wind and jumper movement within the simulation using MODSIM III as its language. Once the model was built, verified, and calibrated, it helped perform a preliminary analysis of jumper risk with varying element spacing and no crosswind. The results of the simulation provided 15 data points with which linear and logistic regression provided …

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A Comparison Of Circular Error Probable Estimators For Small Samples, Charles E. Williams Mar 1997

A Comparison Of Circular Error Probable Estimators For Small Samples, Charles E. Williams

Theses and Dissertations

Several previous studies investigated the performance of competing circular error probable (CEP) estimators for small samples. This estimation is important in ICBM analysis because, due to expense, there are a limited number of ICBM test launches. In the most recent previous study (1993), Tongue considered five CEP estimators in a simulation test, attempting to determine the behavior of these estimators for populations of various bias, ellipticity, correlation, and sample size. In this paper, we build on Tongue's findings in three ways: (1) The number of estimators compared is expanded to eight. (2) Different factors and factor levels are used. (3) …

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Space Object Identification Using Feature Space Trajectory Neural Networks, Neal W. Bruegger Mar 1997

Space Object Identification Using Feature Space Trajectory Neural Networks, Neal W. Bruegger

Theses and Dissertations

The Feature Space Trajectory Neural Network (FSTNN) is a simple yet powerful pattern recognition tool developed by Neiberg and Casasent for use in an Automatic Target Recognition System. Since the FSTNN was developed, it has been used on various problems including speaker identification and space object identification. However, in these types of problems, the test set represents time series data rather than an independent set of points. Since the distance metric of the standard FSTNN treats each test point independently without regard to its position in the sequence, the FSTNN can yield less than optimal results in these problems. Two …

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Decision Boundary Analysis Feature Selection For Breast Cancer Diagnosis, Daniel W. Gregg Mar 1997

Decision Boundary Analysis Feature Selection For Breast Cancer Diagnosis, Daniel W. Gregg

Theses and Dissertations

The general pattern recognition problem always involves the extraction of features to be used in pattern classification. There are no theoretical limitations to the number of features which can be obtained for a given pattern recognition problem. This research will develop a correlation procedure for screening a large feature set without the use of a trained classifier. The results will be compared to established saliency metrics such as the Fisher ratio and derivative-based techniques such as Ruck's saliency.

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A Methodology For Evaluating And Enhancing C4i Networks, Christine C. Davis Mar 1997

A Methodology For Evaluating And Enhancing C4i Networks, Christine C. Davis

Theses and Dissertations

This effort focuses on expanding the bottleneck links of an existing C4I network to meet projected demands. The minimum cost-maximum flow algorithm is used to identify bottlenecks. A decision analysis approach enables the mapping of performance objectives for a network expansion into measurable attributes within the structure of a value hierarchy. A multi-attribute value function combines these measures into an overall system effectiveness measure. This allows for an evaluation of the impact of potential upgrade components on the system. A knapsack model imposes budgetary constraints on the selection of components. This methodology allows for the design of an optimized system …

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Transportation Modeling Of Remote Radar Sites And Support Depots, Sonia E. Leach Mar 1997

Transportation Modeling Of Remote Radar Sites And Support Depots, Sonia E. Leach

Theses and Dissertations

The North Warning System (NWS), a joint program of the United States Air Force (USAF) and the Royal Canadian Air Force (RCAF), is responsible for the maintenance of 47 remote radar sites across northern Canada. NWS's current airlift operations, which support the radar maintenance activities, consist of both helicopters and fixed wing aircraft positioned at five support depots. This thesis considers whether a reconfiguration of these support depots and the assignment of radar sites to them can result in either an airlift or total cost savings for NWS. Mixed integer linear programming models were formulated to address the questions surrounding …

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The Application Of Statistical Process Control To Departure Reliability Improvement, Liu W. Chieh Mar 1997

The Application Of Statistical Process Control To Departure Reliability Improvement, Liu W. Chieh

Theses and Dissertations

This research effort focuses on applying statistical process control (SPC) techniques to the departure reliability improvement process for Air Mobility Command, Mission Reliability Office. Basic SPC methods, including Pareto analysis, cause and effect diagrams, and control charts are determined to be effective tools for analyzing and assessing departure reliability. In addition, two more alternative measures of effectiveness for departure reliability are evaluated and compared using AMC's data. SPC methods are also shown to be useful in assessing in performance and in determining the reporting frequency for on-time performance information. Additional statistical analyses are conducted, including on-way analyses of variance, hypothesis …

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Analyzing And Improving Stochastic Network Security: A Multicriteria Prescriptive Risk Analysis Model, David L. Lyle Mar 1997

Analyzing And Improving Stochastic Network Security: A Multicriteria Prescriptive Risk Analysis Model, David L. Lyle

Theses and Dissertations

This research optimized two measures of network security by hardening components and improving their reliability. A common measure of effectiveness (MOE) for networks is statistical reliability, which ignores the effects of hostile actions. A new MOE which includes hostile actions was developed. Both measures require component reliability functions, derived using fault trees. Fuzzy Logic and Monte Carlo simulation were used to quantify uncertainty. Results from the model are compared to traditional Risk Assessment results.

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System Comparison Procedures For Automatic Target Recognition Systems, Anne E. Catlin Mar 1997

System Comparison Procedures For Automatic Target Recognition Systems, Anne E. Catlin

Theses and Dissertations

Estimating the performance of an automatic target recognition (ATR) system in terms of probability of successful target identification involves extensive image collection and processing, which can be very time-consuming and expensive. We investigate the Wald sequential test for the difference in two proportions as a sample size-reducing alternative to ranking and selection and the classical method of comparing binomial confidence intervals. The test is modified for the multiple pairwise comparison of four systems, and is applied to actual data to compare different configurations of the Moving and Stationary Target Acquisition and Recognition (MSTAR) System.

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Analysis Of A Methodology For Linear Programming Optimality Analysis, Chanseok Jeong Mar 1997

Analysis Of A Methodology For Linear Programming Optimality Analysis, Chanseok Jeong

Theses and Dissertations

The methodology of Johnson, Baner, Moore, and Grant can be applied to large scale linear programming models. A methodology for optimality analysis of linear programs was developed to create metamodels using response surface methodology techniques such as experimental design and least squares regression. A metamodel consists of a simple equation which is able to predict the optimal objective function value of a linear program. What is needed is some large scale application of the techniques to verify how accurate they are. In the research, I plan to use the large scale LP model, STORM. I use the "Hot Start" idea …

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A Cercla-Based Decision Support System For Environmental Remediation Strategy Selection, Brian J. Grelk Mar 1997

A Cercla-Based Decision Support System For Environmental Remediation Strategy Selection, Brian J. Grelk

Theses and Dissertations

The Idaho National Environmental Engineering Laboratory (INEEL), operating in conjunction with the Department of Energy (DOE), faces with the complex decision of selecting an environmental remediation strategy for the Subsurface Disposal Area (SDA) of the Radioactive Waste Management Complex (RWMC). This research uses value-focused thinking and multiattribute preference theory techniques to produce a decision analysis model to aid the decisionmakers as they select a remediation strategy. A deterministic analysis using expert opinion and the best available engineering data demonstrates the model's capabilities. The model ranks 27 specific remediation strategies based on how well they meet CERCLA's five balancing criteria: implementability, …

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Turkish Air Mobility Modeling, Huseyin Topcuoglu Mar 1997

Turkish Air Mobility Modeling, Huseyin Topcuoglu

Theses and Dissertations

The aim of this research is to provide a tactical mobility model which is user friendly and flexible so the user is able to change the inputs, and evaluate the situation with the projected data for an operational plan. Thus, the users can analyze their system by using the model to see whether or not mobility requirements can be met within a definite time frame, and how long it takes to satisfy the requirements. Generalized Air Mobility Model (GAMM) was chosen to model TAMC's airlift system and has been found suitable for application to TUAF mobility problems. The software enables …

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Decision Support Model To Select The Optimal Municipal Solid Waste Management Policy At United States Air Force Installations, Johnathon L. Dulin Mar 1997

Decision Support Model To Select The Optimal Municipal Solid Waste Management Policy At United States Air Force Installations, Johnathon L. Dulin

Theses and Dissertations

The United States Air Force has recently defined three objectives in developing strategies regarding the management of municipal solid waste at the base level. They are: (1) 50 percent reduction in total waste generated, from a 1992 baseline amount, by 1999; (2) 50 percent recycling of all waste generated, beginning in 1999; and, (3) a minimum cost program. With these objectives in mind, base environmental engineers must take appropriate actions in an effort to develop a program that meets these goals. Through consultations with base environmental managers, as well as research of the available literature, a decision support model was …

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Analyzing Remediation Technologies For Department Of Energy Sites Contaminated With Dnapl Pollutants, Anthony F. Papatyi Mar 1997

Analyzing Remediation Technologies For Department Of Energy Sites Contaminated With Dnapl Pollutants, Anthony F. Papatyi

Theses and Dissertations

The Department of Energy is in the process of conducting a Remedial Investigation/Feasibility Study for a site contaminated with Dense Non-Aqueous Phase Liquid (DNAPL) pollutants at their Paducah Kentucky facility. A major part of this effort is the screening of alternative technologies. This thesis effort focuses on acquiring insight into a number of remediation technology trains that are candidates for the Paducah site. This insight is used to recommend and justify the screening of candidate technology trains. The research makes use of two decision analysis models (one is deterministic, the other is probabilistic) built to provide a quantitative assessment of …

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C-17/Paratrooper Risk Assessment Analysis, Jose C. Belano Mar 1997

C-17/Paratrooper Risk Assessment Analysis, Jose C. Belano

Theses and Dissertations

The C-17 test and evaluation community has been testing different aircraft formation geometries in search of a configuration which minimizes paratrooper encounter with the wake vortices of upstream aircraft. This thesis develops a simulation tool that the C-17 test and evaluation community can utilize as an advanced risk assessment model to use on proposed formation geometries prior to live testing. The model is developed under the architecture of object-oriented simulation using MODSIM III and parallels similar efforts by the Aerodynamic Decelerator Technology community in creating object-oriented counterparts to already developed trajectory models of various degrees of freedom. This thesis develops …

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