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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

Explanatory factors for Marine Corps aviation maintenance performance

Chesterton, Gregory L. 09 1900 (has links)
The thesis identifies F/A-18 squadron characteristics that are important predictors of maintenance performance and draws insights on the linkage between the utilization of engineering and technical services (ETS) and maintenance performance measures. Statistical analysis is conducted to identify squadron characteristics that have a detectable contribution to the variability of the performance measure man-hours per maintenance action, and how much additional variability is explained by the squadron that is not accounted for by the squadron characteristics already considered. Thirty months of data were collected for thirteen active duty Marine Corps F/A-18 squadrons. Regression is used to model man-hours per maintenance action as a linear combination of explanatory variables that describe the squadrons in terms of manpower, inventory, and ETS metrics. The test for significance indicates that the model developed in this study is highly likely to have better explanatory power than an intercept-only (average) estimate of the response variable. The study concludes with recommendations for data collection methods that would facilitate the correlation of squadron characteristics to ETS utilization. Critical to the success of this approach is the linkage of ETS utilization to specific squadron maintenance activities, and the development of methods to quantify maintainer training currency.
212

Systems analysis of alternative architectures for Riverine Warfare in 2010

Oliveria, Tristan V., Beaver, James W., Mercado, Pedro R., Bucher, Andrew D., Free, Jennifer M., Byers, Richard W. 12 1900 (has links)
Student Integrated Project / Includes supplementary material. / This thesis analyzed the Navy's proposed Riverine Force (RF) structure and capabilities of 2006. Systems Engineering and Analysis cohort 10 (SEA10) developed a cost-effective system of systems which increased battlespace awareness and situational responsiveness for 2010. Riverine missions were decomposed into their functional, physical, and operational architectures using the detect-to-engage sequence. This analysis determined critical RF functions. Critical functions detect and engage were then physically represented by feasible force package alternatives that augmented the baseline RF. SEA10 analyzed these alternatives using agent based models to identify baseline RF capability gaps and provide insights into possible solutions. Reduction of modeling data indicated the baseline force was as effective as some upgraded force packages depending on the measure of performance (MOP) or scenario structure under scrutiny. Sensor augmentation demonstrated significant improvements to baseline performance by increasing battlespace awareness. Weapon augmentation alone did not significantly improve baseline performance by increasing situational responsiveness. Combined sensor-weapon augmentation performed well across all MOP and scenarios. The Unmanned Surface Vehicle (USV) was the most cost-effective alternative. Dedicated helicopter support demonstrated the best performance overall, but was the most costly alternative.
213

Extending orthogonal and nearly orthogonal Latin hypercube designs for computer simulation and experiments

Ang, Keng-Ern Joshua. 12 1900 (has links)
Efficient Designs (SEED) Center website (http://harvest.nps.edu).
214

Application of neural networks to predict UH-60L electrical generator condition using (IMD-HUMS) data

Tourvalis, Evangelos. 12 1900 (has links)
In 2003, the US Army began using the Integrated Mechanical Diagnostics Health and Usage Management System (IMD-HUMS), an integrated airborne and ground-based system developed by Goodrich Corporation, to support maintenance of the UH-60L. IMD-HUMS is responsible for collecting, processing, analyzing, and storing an enormous amount of vibratory and flight regiime data obtained from sensors located throughout the aircraft. The purpose of this research is to predict failures of the UH-60L's electrical generators, applying Airtificial Neural Networks (ANN) on the IMD-HUMS-produced data. Artificial NNs are data based vice rule based, thereby possessing the potential capability to operate where analytical solutions are inadequate. They are reputed to be robust and highly tolerant of noisy data. Software tools such as Clementine 10.0, S-Plus 7.0, and Excel are used to establish these predictions. This research has verified that ANNs have a position in machinery condiiton monitoring and diagnostics. However, the limited nature of these results indicates that ANNs will not solve all machinery condition monitoring and diagnostics problems by themselves. They certainly will not completely replace conventional rule-based expert systems. Ultimately, it is anticipated that a symbiotic combination of these two technologies will provide the optimal solution to the machinery condition monitoring and diagnostics problem.
215

Object Orientated Programmable Integrated Circuit (OOPIC) upgrade and evaluation for Autonomous Ground Vehicle (AGV)

Hoffman, Andrew J. 12 1900 (has links)
A small, low-power Object-Oriented Programmable integrated circuit (OOPic) microcontroller was integrated and tested with the architecture for an autonomous ground vehicle (AGV). Sensors with the OOPic, and the XBee Wireless Suite were included in the integration. Tests were conducted, including range and time operation analysis for wireless communications for comparison with the legacy BL2000 microcontroller. Results demonstrated long battery life for the electronics of the robot, as well as communication ranges exceeding high power modems. The OOPic was limited by processing power and an ability to interpret some incoming form data. Consequently its use as a one for one replacement for the BL2000 is limited. However combined use with the BL2000 shows promise as a replacement for sensor monitoring and a hardware substitute for the legacy Pulse Width Modulator.
216

Investigating ground swarm robotics using agent based simulation

Ho, Sze-Tek Terence 12 1900 (has links)
Approved for public release; distribution is unlimited / The concept of employing ground swarm robotics to accomplish tasks has been proposed for future use in humanitarian de-mining, plume monitoring, searching for survivors in a disaster site, and other hazardous activities. More importantly in the military context, with the development of advanced explosive detectors, swarm robotics with autonomous search and detection capability could potentially address the improvised explosive device (IED) problem faced by foot patrols, and aid in the search for hidden ammunition caches and weapons of mass destruction (WMDs). The intent of this research is to leverage on agent based simulation to model a ground robotic swarm on a search and detection mission in a semi-urban environment rigged with stationary IEDs. Efficient design of experiment (DOE) techniques and data farming are engaged to help identify controllable factors and capabilities that have the most impact on overall effectiveness. The focus of this thesis is to explore agent based simulation applied to swarm robotics; the technological and algorithmic aspects are not delved on. Results from the simulations provide several insights on the impact of both decision and noise factors on the performance of the swarm. Incorporation of virtual pheromones as a shared memory map is modeled as an additional capability that is found to enhance the robustness and reliability of the swarm. / Outstanding Thesis
217

Flight regime recognition analysis for the army UH-60A IMDS usage

DERE, Ahmet Murat. 12 1900 (has links)
Approved for public release; distribution is unlimited / Usage Monitoring requires accurate regime recognition. For each regime, there is a usage assigned for each component. For example, the damage accumulated at a component is higher if the aircraft is undergoing a high G maneuver than in level flight. The objective of this research is to establish regime recognition models using classification algorithms. The data used in the analysis are the parametric data collected by the onboard system and the actual data, consisting of the correct regime collected from the flight cards. This study uses Rpart (with a tree output) and C5.0 (with a ruleset output) to establish two different models. Before model fitting, the data was divided into smaller datasets that represent regime families by subsetting using important flight parameters. Nonnormal tolerance intervals are constructed on the uninteresting values; then these values in the interval are set to zero to be muted (e.g. excluded). These processes help reduce the effect of noise on classification. The final models had correct classification rates over 95%. The number of bad misclassifications were minimized (e.g. the number of bad misclassifications of a level flight regime as a hover regime was minimized), but the models were not as powerful in classifying the low-speed regimes as in classifying high-speed regimes. / Outstanding Thesis
218

Determining the number of reenlistments necessary to satisfy future force requirements

Raymond, Jonathan D. 09 1900 (has links)
RA requested that these models be examined in an effort to combine the functionality of each. This thesis builds a model that does just that. The fundamental concept of the model involves taking the current inventory of Marines (by military occupational specialty [MOS] and grade) and applying transition rates to each of them in order to determine how many are in what state at the end of the upcoming year. The necessary number of reenlistments is then calculated by subtracting the forecasted inventory from a desired force structure known as the Grade Adjusted Recapitulation. Manpower planners can use the results of this model to establish the number of boat spaces for each of the first-term MOSs as well as recommended reenlistment goals for the subsequent-term MOSs.
219

Analysis of the assignment scheduling capability for Unmanned Aerial Vehicles (ASC-U) simulation tool

Nannini, Christopher J. 06 1900 (has links)
Approved for public release; distribution is unlimited / The U.S. Army Training and Doctrine Command (TRADOC) Analysis Center (TRAC) and the Modeling, Virtual Environments, and Simulations Institute (MOVES) at the Naval Postgraduate School, Monterey, California developed the Assignment Scheduling Capability for UAVs (ASC-U) simulation to assist in the analysis of unmanned aerial vehicle (UAV) requirements for the current and future force. ASC-U employs a discrete event simulation coupled with the optimization of a linear objective function. At regular intervals, ASC-U obtains an optimal solution to a simplified problem that assigns available UAVs to missions that are available or will be available within a future time horizon. This thesis simultaneously explores the effects of 26 simulation and UAV factors on the mission value derived when allocating UAVs to mission areas. The analysis assists in defining the near term (2008) UAV force structure and the investment strategy for the mid term (2013), and far term (2018). We combine an efficient experimental design, exploratory modeling, and data analysis to examine 514 variations of a scenario involving five UAV classes and over 21,000 mission areas. The conclusions suggest the following: the optimization interval significantly influences the quality of the solution, percent mission coverage may depend on a few UAV performance factors, small time horizons increase percent mission coverage, and carefully planned designs assist in the exploration of the outer and interior regions of the response surface. / Outstanding Thesis
220

Dynamic Facility Relocation and Inventory Management for Disaster Relief

Richter, Amber Rae 02 September 2016 (has links)
<p> Disasters strike suddenly and cause destruction which disrupts the availability of basic survival supplies for people living in affected areas. The efficiency of humanitarian organizations in providing relief has a direct and crucial impact on the survival, health, and recovery of affected people and their communities. To better prepare to respond to disasters, many relief organizations use supply pre-positioning. However, the real and potential needs of different locations change over time and when an organization uses traditional warehouse pre-positioning, relief operations are limited by set inventory locations that are difficult to alter. For this reason, a well known organization recently considered including a large supply holding ship in its operations. By holding inventory on a ship, the organization would be able to dynamically relocate its inventory over time in response to changing relief supply demand forecasts. </p><p> To our knowledge, the research contained herein is the first to examine dynamic inventory relocation for responding to disasters over time. Specifically, we examine how to optimally relocate and manage inventory for a single mobile inventory to serve stochastic demand at a number of potential disaster sites over time. While we keep in mind the motivating example of a supply holding ship in the disaster relief setting throughout this dissertation, the model and most of the results are applicable to any type of mobile inventory, facility, or server in any setting. </p><p> We first examine the dynamic relocation problem. We model the problem using dynamic programming and develop analytical and numerical results regarding optimal relocation policies, the optimal path and speed of relocation decisions, and the value of inventory mobility over traditional warehouse pre-positioning. To help overcome the computational complexity of the problem, we develop a heuristic which solves relatively large problem instances in our numerical experiments within 0.5% of optimality in less than 0.1% of the time required by an exact algorithm. </p><p> As it is suboptimal to consider relocation decisions and inventory management decisions separately, we also examine the joint dynamic relocation and inventory management problem. To our knowledge, we are the first to examine the dynamic relocation and inventory management problem with stochastic demand. Similarly to the dynamic relocation problem, we model this problem using dynamic programming. We develop a number of analytical results characterizing the optimal relocation and inventory management policies. </p><p> As the first to examine these problems, we hope this research serves as a catalyst for other research in this area; accordingly, we conclude this dissertation by discussing a number of areas for future research.</p>

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