Operational Research Commons^™

Waiting-Time Paradox In 1922, Naoki Masuda, Takayuki Hiraoka

Northeast Journal of Complex Systems (NEJCS)

We present an English translation and discussion of an essay that a Japanese physicist, Torahiko Terada, wrote in 1922. In the essay, he described the waiting-time paradox, also called the bus paradox, which is a known mathematical phenomenon in queuing theory, stochastic processes, and modern temporal network analysis. He also observed and analyzed data on Tokyo City trams to verify the relevance of the waiting-time paradox to busy passengers in Tokyo at the time. This essay seems to be one of the earliest documentations of the waiting-time paradox in a sufficiently scientific manner.

A Data-Driven Framework For Decision Making Under Uncertainty: Integrating Markov Decision Processes, Hidden Markov Models And Predictive Modeling, Hossein Kamalzadeh

Operations Research and Engineering Management Theses and Dissertations

The problem of decision making under uncertainty can be broken down into two parts. First, how do we learn about the world? This involves the problem of modeling the system and its uncertainty. Secondly, given what we currently know about the world, how should we decide what to do, taking into account uncertainty of future events and observations that may change our conclusions. Many systems evolve over time and often the next state of the system is not known with certainty, often modeled as a probability distribution over system states. Dealing with such systems especially when we can make a …

Product Realization Capstone: Element Proof Safety Steps For Willie Price Lab School, Catherine Thomas, Allan Heuerman, Jared Mumme

Honors Theses

The purpose of this document is to describe the process we took to complete our capstone which paired the Center for Manufacturing Excellence with the Willie Price Lab School. The goal of the capstone was to remake step stools for the students of Willie Price, as the last stools failed to withstand weather damage. However, with the COVID-19 pandemic, plans were hindered, shifting the goal from actually producing the steps to creating instructions so that a younger Center for Manufacturing class could complete the production at a later date. Standardized Work Instructions, a detailed production plan, and engineering drawings were …

Joint Location And Inventory Models And Algorithms For Deployment Of Hybrid Electric Vehicle Charging Stations., Jie Zhang

Electronic Theses and Dissertations

This thesis describes a study of a novel concept of hybrid electric vehicle charging stations in which two types of services are offered: battery swapping and fast level-3 DC charging. The battery swapping and fast-charging service are modeled by using the M/G/s/s model and the M/G/s/$\infty$ model, respectively. In particular, we focus on the operations of joint battery swapping and fast charging services, develop four joint locations and inventory models: two for the deployment of battery swapping service, two for the deployment of hybrid electric vehicle charging service. The first model for each deployment system considers a service-level constraint for …

Optimization And Simulation Models To Improve Access To Organ Transplantation In The United States., Fatemeh Karami

Electronic Theses and Dissertations

Organ allocation in the U.S. is administrated by the United Network of Organ Sharing (UNOS). UNOS’s mission is to ensure fair and equitable allocation of organs as stated in the Code of Federal Regulations, which reads "neither place of residence nor place of listing shall be a major determinant of access to transplant". Despite the regulations, there has been endless controversy surrounding the disparity in access to organ transplants. In this context, the primary research goal in this dissertation was to reduce geographic disparity in access to transplants in the U.S., with a focus on heart and kidney transplants. To …

Locating Relay Nodes To Maximize Wireless Sensor Network Lifetime: A Numerical Study, Maria Rene Arandia Jimenez

Industrial Engineering Undergraduate Honors Theses

A wireless sensor network (WSN) is a group of sensors deployed over an area, which monitor changes in the environment, collects them as data and forwards it between sensors through wireless links. Data is routed, either in a single-hop or multi-hop manner, with the goal of getting this collected data to the sink nodes, which have higher computational capabilities and connects the network with a user interface. Studies have determined that multi-hop WSNs that integrate relay nodes, which function is to only receive and forward data, can maximize lifetime network. A linear programming model, created by Chang and Tassiulas in …

Curriculum Optimization Via Activity-On-Node Network Modeling, Caroline Rhomberg

Industrial Engineering Undergraduate Honors Theses

University degree plans must be carefully planned so that they allow students the best chance of succeeding. Although for the better, with the advancement of technology and its incorporation into the classroom, it can be argued that the complexity and difficulty of some long-established engineering core classes has changed. With this trend certain combinations of engineering courses have become unfavorable in terms of course withdrawal and fail rates stemming from the interaction of course challenges. A wealth of data has been collected on this topic and will be utilized in this project. As one can imagine, the probability of success …

Optimal Emergency Response Shelter Placement Based On Population Vulnerabilities, Alexander Johnson

Industrial Engineering Undergraduate Honors Theses

Hurricane Florence was a category 4 storm which caused an estimated $24 billion in damages and the loss of 53 lives. During and immediately following Florence, there were 235 shelters operating in and around the North Carolina (NC) area. These were used as temporary housing for storm victims and by emergency responders to distribute relief supplies and provide medical services. Emergency officials consider several factors when deciding where to open shelters, including, for example, proximity of victims and their levels of medical needs. Access disparities, or factors creating barriers that limit entry to shelters, put certain populations and regions at …

Re-Evaluating Coverage Metrics For Wireless Sensor Network Border Security Applications, Kevin Haney

Industrial Engineering Undergraduate Honors Theses

Wireless sensor networks are an emerging technology used to monitor an environment over time. One specific application of the wireless sensor network is the border security application. Researchers have adapted coverage metrics from general wireless sensor network literature to fit the border security application. While some of the adapted metrics count the number of sensors detecting a potential target, others measure the distance between a potential target and its nearest sensor. No existing metric accounts for both of these factors. To take advantage of this gap and to attempt to increase the accuracy to which coverage is measured in this …

Improvement Of Geometric Quality Inspection And Process Efficiency In Additive Manufacturing, Yu Jin

Graduate Theses and Dissertations

Additive manufacturing (AM) has been known for its ability of producing complex geometries in flexible production environments. In recent decades, it has attracted increasing attention and interest of different industrial sectors. However, there are still some technical challenges hindering the wide application of AM. One major barrier is the limited dimensional accuracy of AM produced parts, especially for industrial sectors such as aerospace and biomedical engineering, where high geometric accuracy is required. Nevertheless, traditional quality inspection techniques might not perform well due to the complexity and flexibility of AM fabricated parts. Another issue, which is brought up from the growing …

Simulation Modeling Of Cross-Dock And Distribution Center Based Supply Chains, Ghewa Al Chall

Graduate Theses and Dissertations

Companies are implementing new strategies to meet the customer requirements in terms of quality, timing, and cost. One of these strategies is cross-docking, which can be defined as the process of consolidating the products coming from different suppliers, but having the same destination, with minimal handling and almost no storage between loading and unloading of the goods. The purpose of this research is to investigate the benefits of having a cross-docking facility in a supply chain. In this research, we focus on developing discrete event simulation models using the opensource Java Simulation Library (JSL). Also, we work on augmenting an …

Locating Emergency Shelters While Incorporating Spatial Factors, Justin Taylor

Graduate Theses and Dissertations

In the immediate response phase of a natural disaster, local governments and nonprofit agencies often establish shelters for affected populations. Decisions regarding at which locations to open shelters are made ad hoc based on available building inventory, and may result in high travel impedance to reach shelters and congestion. This thesis presents a shelter location optimization model based on the two-step floating catchment area (2SFCA) method. The 2SFCA method creates a shelter accessibility score for each areal unit (e.g., census block group) which represents the ability for persons in the unit to access shelter capacity with low travel impedance, relative …

Cardiovascular Surgery Practice Remodel: Increasing Job Satisfaction And Reducing Turnover Rates Of Advanced Practice Providers, Christian Brooks

Doctor of Nursing Practice Scholarly Project

Cardiovascular Surgery Practice Remodel: Increasing Job Satisfaction and Reducing Turnover Rates of Advanced Practice Providers

Background: The CVS practice in a Midwestern state had a shift in morale and job satisfaction in their advanced practice providers (APPs). This shift lead to the high turnover rate of 35% in 2018. In an effort to bring a halt to the high turnover rate, and to continue the excellent patient care for which the hospital is known, hospital administration became involved and set up a committee to guide the development of a new CVS APP practice model. The goal was to develop …

Validation Risk Across Hierarchical Models, John B. Young

Computational Modeling & Simulation Engineering Theses & Dissertations

Modeling and simulation are applied in a great many methods across a variety of topics. Model developers and users alike have a professional duty to understand the complexities of the tools and methods they are used. Oftentimes, models that have been independently constructed and executed are used to inform one another for an analytic purpose and the compatibility of the models is not always addressed. In the literature, great attention has been paid to model validation. When using models constructively with one another, analysts must understand the bounds of model validity and ensure that the combination of models does not …

Engineering Management Competencies: A Framework For Present And Future Engineering Environments, Christopher Vaughn Barrett

Engineering Management & Systems Engineering Theses & Dissertations

Managing and directing engineering requires engineering management competencies. Although perspectives may differ concerning competencies for engineering management, identifying competencies can direct and improve management. The purpose of this research is to develop a framework of competencies for engineering managers using an inductive research design. Development of this engineering management competency framework involves an exploration of three primary research questions. The first question is ‘What are the current competencies for engineering managers?’ The response to this question provides a basis for the current state of competencies for engineering managers. The second research question, ‘What are future engineering management competencies based on …

Game Theory Approaches For Transportation Problems, Mahdi Takalloo

USF Tampa Graduate Theses and Dissertations

This dissertation considers three separate game theory problems in transportation. In the first problem, a combinatorial auction market has been proposed for fractional ownership of autonomous vehicles. The proposed combinatorial auction has two unique features. First, the items are continuous time slots defined by bidders and second, the spatial information of bidders has been incorporated so that sharing becomes a viable plan. A conflict-based formulation of the winner determination problem has been proposed, for which an effective solution approach based on a heuristic and a maximal-clique based relaxation has been presented. The second part of the dissertation examines a pessimistic …

Database Analysis To Improve U.S. Transportation Command Forecasting Processes, Maxwell C. Thompson

Theses and Dissertations

The United States Transportation Command (USTRANSCOM) facilitates air, land, and sea transportation for the DOD. On a periodic basis, a myriad of different agencies within USTRANSCOM project future workload to facilitate resource planning, budgeting, and reimbursable rate identification. Within USTRANSCOM, there are a variety of databases and metrics utilized for workload forecasts; neither a standard nor a preferred technique is prescribed. Currently, USTRANSCOM faces challenges in producing accurate workload forecasts [1]. These challenges can lead to unreliable budget requests and, ultimately, hinder the effectiveness and efficiency of USTRANSCOM [1]. For the purpose of routine aircraft movements of cargo and personnel, …

A Metamodel Recommendation System Using Meta-Learning, Megan K. Woods

Theses and Dissertations

The importance and value of statistical predictions increase as data grows in availability and quantity. Metamodels, or surrogate models, provide the ability to rapidly approximate and predict information. However, selection of the appropriate metamodel for a given dataset is often arduous, and the choice of the wrong metamodel could lead to considerably inaccurate results. This research proposes and tests the framework for a metamodel recommendation system. The implementation allows for virtually any dataset and preprocesses data, calculates meta-features, evaluates the performance of various metamodels, and learns how the data behaves via meta-learning, thus preparing and bettering itself for future recommendations. …

Change Management Processes In Model-Based Systems Engineering, Isabeta Rountree, Victor Lopez

Research Horizons Day Posters

No abstract provided.

Explaining Weapon System Sustainment's Impact To Aircraft Availability, Michael D. Ingram

Theses and Dissertations

This research focused on understanding the phenomena behind the cost growth of Weapon System Sustainment (WSS) and the simultaneous degradation in USAF aircraft system availability. The primary modelling technique used was Ordinary Least Squares (OLS) while incorporating temporal effect. Other studies have looked at cost factors related to the Flying Hour Program, flying conditions and age. This study found empirical relationships between each of the four WSS business processes and the lead time in months it takes to realize improvements in system aircraft availability.