Operations Research, Systems Engineering and Industrial Engineering Commons^™

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 …

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, …

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 …