Engineering Commons^™

Examination And Utilization Of Rare Features In Text Classification Of Injury Narratives, Hsin-Ying Huang

Open Access Dissertations

Thanks to the advances in computing and information technology, analyzing injury surveillance data with statistical machine learning methods has grown in popularity, complexity, and quality over recent years. During that same time, researchers have recognized the limitations of statistical text analysis with limited training data. In response to the two primary challenges for statistical text analysis, dimensionality reduction and sparse data, many studies have focused on improving machine learning algorithms. Less research has been done, though, to examine and improve statistical machine learning methods in text classification from a linguistic perspective.

This study addresses this research gap by examining the …

Impact Of Rfid Information-Sharing Coordination Over A Supply Chain With Reverse Logistics, Juan Jose Nativi Nicolau

Open Access Dissertations

Companies have adopted environmental practices such as reverse logistics over the past few decades. However, studies show that aligning partners inside the green supply chain can be a substantial problem. This lack of coordination can increase overall supply chain cost. Information technology such as Radio Frequency Identification (RFID) has the potential to enable decentralized supply chain coordinate their information. Even though there are research that address RFID on traditional supply chain, few researches address how to coordinate RFID information sharing in a green supply chain. We study, through simulation experiments, two types of RFID information-sharing coordination under different configurations related …

Adaptive Sampling Trust-Region Methods For Derivative-Based And Derivative-Free Simulation Optimization Problems, Sara Shashaani

Open Access Dissertations

We consider unconstrained optimization problems where only “stochastic” estimates of the objective function are observable as replicates from a Monte Carlo simulation oracle. In the first study we assume that the function gradients are directly observable through the Monte Carlo simulation. We propose ASTRO, which is an adaptive sampling based trust-region optimization method where a stochastic local model is constructed, optimized, and updated iteratively. ASTRO is a derivative-based algorithm and provides almost sure convergence to a first-order critical point with good practical performance. In the second study the Monte Carlo simulation is assumed to provide no direct observations of the …

Metrics Of Critical Pair Identification, Zixu Zhang

Open Access Theses

Critical Pair Identification works as a potential assistive tool for human air traffic controllers by identifying potentially dangerous situations that are not detected by proposed automated separation assurance systems. This concept specifically considers conflicts that might arise if aircraft unexpectedly deviate from their planned flight path in the near future. Five metrics of the critical pair concept, Critical Pair Count, Time to Risk Exposure, Lead Time, Risk Exposure Duration and Blunder Sensitivity Index, have been developed and mathematically defined to characterize the safety level of an aircraft pair or a volume of air space. Algorithm that computes proposed metrics is …

Taming Tail Latency For Erasure-Coded, Distributed Storage Systems, Jingxian Fan

Open Access Theses

Nowadays, in distributed storage systems, long tails of responsible time are of particular concern. Modern large companies like Bing, Facebook and Amazon Web Service show that 99.9th percentile response times being orders of magnitude worse than the mean. With the advantages of maintaining high data reliability and ensur- ing enough space eciency, erasure code has become a popular storage method in distributed storage systems. However, due to the lack of mathematical models for analyzing erasure-coded based distributed storage systems, taming tail latency is still an open problem.

In this research, we quantify tail latency in such systems by deriving a …

Parametric Approaches To Fractional Programs: Analytical And Empirical Study, Chong Hyun Park

Open Access Dissertations

Fractional programming is used to model problems where the objective function is a ratio of functions. A parametric modeling approach provides effective technique for obtaining optimal solutions of these fractional programming problems. Although many heuristic algorithms have been proposed and assessed relative to each other, there are limited theoretical studies on the number of steps to obtain the solution. In this dissertation, I focus on the linear fractional combinatorial optimization problem, a special case of fractional programming where all functions in the objective function and constraints are linear and all variables are binary that model certain combinatorial structures. Two parametric …

Best Matching Processes In Distributed Systems, Mohsen Moghaddam

Open Access Dissertations

The growing complexity and dynamic behavior of modern manufacturing and service industries along with competitive and globalized markets have gradually transformed traditional centralized systems into distributed networks of e- (electronic) Systems. Emerging examples include e-Factories, virtual enterprises, smart farms, automated warehouses, and intelligent transportation systems. These (and similar) distributed systems, regardless of context and application, have a property in common: They all involve certain types of interactions (collaborative, competitive, or both) among their distributed individuals—from clusters of passive sensors and machines to complex networks of computers, intelligent robots, humans, and enterprises. Having this common property, such systems may encounter common …

Service-Level Based Response By Assignment And Order Processing For Warehouse Automation, Zijian He

Open Access Theses

Along with tremendous growth of online sales in this Internet era, unprecedented intensive competition in shortening the delivery time of orders has been occurring among several major online retailers. On the other hand, the idea of customer-oriented service creates a trend of diversified pricing strategy. Different price options are offered to cater to diversified needs of customers. It has become an urgent need for online sales industries to provide the differentiated service levels for different classes of customers with different priorities based on the charging prices and resource constraints of the supply network.

In response to the challenges mentioned above, …

Markov-Based Ranking Methods, Baback Vaziri

Open Access Dissertations

Ranking methods are an essential tool to help make decisions. This dissertation document examines different aspects of the theory and application of pairwise comparison ranking methods, specifically those that use Markov chains. First, a new method is developed to solve a traditional recruiting problem, and is shown to improve the predictive power of its ranking. Next, modifications are made to an existing method that theoretically improves the reliability, while maintaining the rank integrity. Last, a framework is developed that defines a fair and comprehensive ranking method, and several popular methods are evaluated in their ability to adhere to the said …

The Casualty Transportation Of Ebola Outbreak In Liberia: A Simulation Study, Hyejin Cho

Open Access Theses

In this paper, we have solved the unique problem of casualty transportation problem under Ebola by developing dynamic policies for vehicle routing in order to provide practical decision support. The objective of the proposed model is to minimize the total transmission risk. We describe the problem with real- constraints and parameters based on the empirical data of the 2014 Ebola outbreak in Liberia. The casualty transportation problem is a variant of Dynamic Pick-up and Delivery Problems (DPDP), in which a vehicle is dispatched to demand location in real time and it then transports the demands to the aimed area (destination). …

Developing Agent-Based Simulation Models Of Task Performance Of Cognitively Diverse Teams, Megan Marie Nyre

Open Access Theses

Team-oriented work dominates industry, government, and academic areas with the goal of solving increasingly complex problems. However, the scope and external validity of traditional human factors research is inherently limited by the time and resources required to conduct laboratory studies. The model described in this thesis integrates simulation with human factors by providing an operationalized model that incorporates cognitive diversity and domain expertise. Convergence and functionality of the model have been established through a series of analyses, and a clear path for future research has been identified. By integrating simulation methods into human factors subject areas, researchers may be able …

A Case Study Of Two-Echelon Multi-Depot Vehicle Routing Problem, Tianqi Yu

Open Access Theses

The Vehicle Routing Problem (VRP) is a classic combinatorial optimization problem and a topic still studied for practical applications. Current research focuses on single echelon distribution systems such as distribution centers serving customers. However, in typical distribution, goods flows among regional distribution centers, local warehouses and customers, defined as a two-echelon network. The two-echelon multiple depot VRP problem is documented and applied to two stages illustrated by a small scale computational example. In the first stage, the simulated annealing algorithm is employed to determine the routes between local warehouses and final customers. For the second stage, trial-and-error is applied to …

Enhancing A Flight Dispatcher Display For Safer Flight Operations, Jeongjoon Boo

Open Access Theses

This study assesses capability of flight dispatchers to adopt enhancements on their display that enables detection of flights in abnormal activities and investigation of the causes. Three approaches were used. First, the expected function for enhancements was designed by collecting information from different places about what technologies are available for consideration. Second, hierarchical task analysis was conducted based on data collected by interviewing a former flight dispatcher in order to assess operational capability to handle the enhancement. Third, based on the results of first two approaches, a display prototype that includes the enhancement was developed and evaluated for usability and …

A Dynamic Stochastic Model For Converging Inbound Air Traffic, Jun Chen

Open Access Theses

Weather accounts for the majority of congestion in the National Airspace System which highlights the importance of addressing weather uncertainty to mitigate delays, and this paper presents an effort in this direction. Firstly, a new dynamic stochastic 0-1 Integer Programming (IP) model is proposed, which models the Single Airport Ground Holding Problem (SAGHP) with respect to uncertainty in the separation between flights instead of Airport Acceptance Rate (AAR) or landing capacity. Uncertainty in separation according to different weather conditions is represented through the scenario tree by using stochastic linear programming. Considering time separation constraints instead of AAR constraints, our model …

Designing A Sustainable And Transferable Inventory Management System For Small Healthcare Facilities, Shree Frazier

Open Access Theses

Managing the costs of supplies within healthcare facilities has been a task that has plagued the health industry for many years. Many facilities are accustomed to using a par system approach. This involves bringing an inventory item to an amount sufficient for daily operation. This method often requires daily inspection by a healthcare worker, which reduces his/her time spent performing value added tasks. Employees at small healthcare facilities have multiple responsibilities, therefore they cannot afford to spend much time on inventory management. A proposed approach is the Kanban method, which allows for strict monitoring of inventory items without the need …

Application Of Bayesian Networks In Consumer Service Industry, Yuan Gao

Open Access Theses

Gao, Yuan. M.S.I.E., Purdue University. December 2014. Application of Bayesian Networks in Consumer Service Industry. Major professor: Vincent G. Duffy The purpose of the present study is to explore the application of Bayesian networks in the consumer service industry to model causal relationships within complex risk factor structures using aggregate data. An analysis of the Hawaii tourism market was conducted to find out how visitor characteristics affect their behavior and experience as consumers during the trips, and influence the tourism market outcomes represented by measurable factors. Two hypotheses were proposed regarding the use of aggregate data and the influence of …

Designing Sustainable Mentoring Programs: Examining The Role Of Social Community In The Stem College Student Experience, Joi-Lynn Mondisa

Open Access Theses

In order to begin to understand how to design programs that promote community development and produce beneficial outcomes for community members, we must first define the elements and functions of such a community. In this thesis, I define social community as an environment where like-minded individuals engage indynamic, multidirectional interactions that facilitate social support . Using a human-integrated systems approach, I propose a social community model for STEM minority mentoring programs to understand how a community's design plays a role in the learning and enrichment of its members. The social community model is comprised of three main components: program …

Dissolution Rate And Mechanism Of Metals In Molten Aluminum Alloy A380, Hengyu Zhu

Open Access Theses

Shot sleeve is a very easily worn out part in a high-pressure die-casting machine due to serious dissolution of the area underneath the pouring hole. It is because during a normal pouring process, the high temperature molten aluminum will impact and dissolve that area of the shot sleeve by complex chemical and physical process. Rotation experiment was carried out to H13 and four kinds of refractory metal samples. SEM and EDS pictures were taken in order to investigate the microstructure and the dissolution mechanism of these materials. This suggests a high strength niobium is an ideal material for that area …

Evaluating Intensity As A Controller Function For Nextgen Scenarios With Increased Capacity, Caitlin Anne Surakitbanharn

Open Access Theses

Automated separation assurance is the most mature concept to handle increasing airspace traffic and capacity needs, yet the system lacks a way to pre-emptively identify aircraft separation problems. The intensity control measure looks to find situations where if an aircraft pair makes an unplanned change in heading or altitude at the wrong moment, an unrecoverable situation arises. This research analyzes static, open loop air traffic data in an en-route sector to determine how many high intensity aircraft pairs (HIP) exist per minute, and if the intensity measure is a safely manageable function for air traffic controllers. It is found that …

The Multi-Depot Minimum Latency Problem With Inter-Depot Routes, Timothy W. Duket

Open Access Theses

The Minimum Latency Problem (MLP) is a class of routing problems that seeks to minimize the wait times (latencies) of a set of customers in a system. Similar to its counterparts in the Traveling Salesman Problem (TSP) and Vehicle Routing Problem (VRP), the MLP is NP-hard. Unlike these other problem classes, however, the MLP is customer-oriented and thus has impactful potential for better serving customers in settings where they are the highest priority. While the VRP is very widely researched and applied to many industry settings to reduce travel times and costs for service-providers, the MLP is a more recent …

Exploratory Study In Container Loading Embraer 190 Aircraft, Ryan H. Auyeung

Open Access Theses

Since the dawn of aviation, cargo loading on aircraft has remained virtually constant. A person and a baggage cart together have been the primary method of loading baggage on to aircraft, and this practice has virtually remained unchanged, especially for narrow body aircraft. This study explores the question of whether a loading device, designed for Embraer 190 aircraft, can increase economic efficiency by reducing aircraft turnaround times, increasing aircraft utilization and reducing work hours. In the course of designing a theoretical loading device for an Embraer 190, various literature ranging from elaborate articulating conveyor belts, to the use of LD3-45W …

Characterizing Habituation Using The Time-On-Task Metric In An Iris Recognition System, Jacob A. Hasselgren

Open Access Theses

This thesis presents a characterization of biometric habituation in an iris recognition study using qualitative analysis of a distributed habituation survey and quantitative analysis of iris images collected in 2010 and 2012. The performed analyses answered the following two questions: a) How consistently does the biometric community define habituation?; and b) Does the time-on-task variable provide enough evidence to indicate the existence of habituation in an iris recognition system? The qualitative analysis examined responses to 12 habituation-related questions from 13 biometric experts to identify common themes that not only determined definition consistency but also characterized critical components often omitted from …

Detecting Air Traffic Controller Interventions In Recorded Air Transportation System Data, Yul Kwon

Open Access Theses

In this study, I propose a systematic method of detecting aircraft deviation due to air traffic controller (ATC) intervention. The aircraft deviations associated with ATC interventions are detected using a heuristic algorithm developed from analyzing the actual positions of an aircraft to its filed flight plan when the aircraft trajectories were identified as having an encounter in a loss-of-separation incident. An actual (closed-loop) flight trajectory of the Cleveland Air Route Traffic Control Center (ZOB ARTCC) was collected from the FlightAware database. This was compared with the corresponding planned (open-loop) trajectory dataset generated by the Microsoft© Flight Simulator X (FSX). I …

Modeling And Optimization Of Care Transitions, Yuming Mo

Open Access Theses

More than 145 million people live with at least one chronic condition, and almost half of them have multiple conditions. As a result, many managed care and integrated delivery systems have taken a great interest in alleviating the many deficiencies in managing the current care system that spans across various care delivery settings. In addition, many Americans have to rely on some social health insurance plan to cover her care expenses. As a result, these patients often may not been sufficiently cured but have to be transitioned to less expensive but less medically intensive facilities, due to the increasing pressure …

Probabilistic Fault Detection And Diagnostics For Packaged Air-Conditioner Outdoor-Air Economizers, Andrew L. Hjortland

Open Access Theses

Poor economizer control, economizer damper failure, and excess outdoor-air contribute to these performance degradations. In order to promote optimal rooftop air-conditioner (RTU) performance and reduce operating costs, an automated fault detection and diagnostics (AFDD) tool has been designed for RTUs with integrated economizers. Based on previously proposed methods, the proposed method advances the economizer fault detection and diagnosis components by using statistical classifiers in order to provide more robust, probabilistic fault outputs. A set of air-side virtual sensors has also been added to the method in order to expand the applicable range of conditions fault detection and diagnostics can be …

A Comparative Analysis Of An Original And A Post-Hoc Application Of Lean Six Sigma Methodology, Jin Qiu

Open Access Theses

Current society develops faster and faster every day with customers' demands increasing rapidly. Decreasing time for product development and enhancing customer satisfaction are becoming more significant. In the business world, there is no industry that could exist without an efficient supply chain. In the fierce competitive environment of today, the supply chain must address potential problems and risks that may exist and assure continuous improvement.

One common supply chain management practice in many industries is to apply lean methodology to the supply chain model in order to maximize the customers' value and eliminate waste. By eliminating waste, the process can …

A Lean Logistics Assessment Tool For Smes In The Manufacturing Sector, Diana Lorena Sanchez Ramirez

Open Access Theses

This study developed an assessment tool to rate the maturity of the current and desired states of lean logistics operations in small and medium enterprises. The tool consists of 48 best practices classified into 8 critical factors: Inventory, Transportation, Administration, Information Systems, Warehouse, Forecasting, Packaging and Supplier Network. Each of the best practices and critical factors were identified throughout a thorough literature review and comparative analysis between authors to define commonalities among them. Using gap analysis; this tool results in a SWOT matrix providing a roadmap for lean implementation. The resulting model was evaluated by subject matter experts in different …

The Effect Of Job Performance Aids On Quality Assurance, Erik David Fosshage

Open Access Theses

Job performance aids (JPAs) have been studied for many decades in a variety of disciplines and for many different types of tasks, yet this is the first known research experiment using JPAs in a quality assurance (QA) context. The objective of this thesis was to assess whether a JPA has an effect on the performance of a QA observer performing the concurrent dual verification technique for a basic assembly task. The JPA used in this study was a simple checklist, and the design borrows heavily from prior research on task analysis and other human factors principles. The assembly task and …

Nanohub Database Analysis: Using Anomaly Detection Method And Principal Component Analysis, Mengyang Qi

Open Access Theses

This thesis analyzes usage data from nanoHUB.org, which is a web-based infrastructure for e-collaboration among nanotechnology simulation community. Previous analysis of nanoHUB database showed he nanoHUB usage data follows an unknown, heavy-tailed distributions. This thesis extends the analysis and develops an automatic anomaly detection method based on piece-wise linear approximation. The anomaly here refers to collective user behaviors different from others. The result shows that the method can accurately detect the anomalies in the unknown, heavily detailed distribution. This thesis also applies anomaly detection method and principal component analysis to other databases in nanoHUB and successfully reveals differences between different …

Modeling Preventive Maintenance In Complex Systems, Jessica Rivas

Open Access Theses

This thesis presents an explicit consideration of the impacts of modeling decisions on the resulting maintenance planning. Incomplete data is common in maintenance planning, but is rarely considered explicitly. Robust optimization aims to minimize the impact of uncertainty--here, in contrast, I show how its impact can be explicitly quantified. Doing so allows decision makers to determine whether it is worthwhile to invest in reducing uncertainty about the system or the effect of maintenance. The thesis consists of two parts. Part I uses a case study to show how incomplete data arises and how the data can be used to derive …