Operations Research, Systems Engineering and Industrial Engineering Commons^™

Modeling And Solution Methodologies For Mixed-Model Sequencing In Automobile Industry, Ibrahim Ozan Yilmazlar

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The global competitive environment leads companies to consider how to produce high-quality products at a lower cost. Mixed-model assembly lines are often designed such that average station work satisfies the time allocated to each station, but some models with work-intensive options require more than the allocated time. Sequencing varying models in a mixed-model assembly line, mixed-model sequencing (MMS), is a short-term decision problem that has the objective of preventing line stoppage resulting from a station work overload. Accordingly, a good allocation of models is necessary to avoid work overload. The car sequencing problem (CSP) is a specific version of the …

Studying Pedestrian’S Unmarked Midblock Crossing Behavior On A Multilane Road When Interacting With Autonomous Vehicles Using Virtual Reality, Fengjiao Zou

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This dissertation focuses on the challenge of pedestrian interaction with autonomous vehicles (AVs) at unmarked midblock locations where the right-of-way is unspecified. A virtual reality (VR) simulation was developed to replicate an urban unmarked midblock environment where pedestrians cross a four-lane arterial roadway and interact with AVs. One research goal is to investigate the impact of roadway centerline features (undivided, two-way left-turn lane, and median) and AV operational schemes portrayed through on-vehicle signals (no signal, yellow negotiating indication, and yellow/blue negotiating/no-yield indications) on pedestrian crossing behavior. Results demonstrate that both roadway centerline design features and AV operations and signaling show …

Multiple Heat Exchanger Cooling System For Automotive Applications – Design, Mathematical Modeling, And Experimental Observations, Zaker Syed

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The design of the automotive cooling systems has slowly evolved from engine-driven mechanical to computer-controlled electro-mechanical components. With the addition of computer-controlled variable speed actuators, cooling system architectures have been updated to maximize performance and efficiency. By switching from one large radiator to multiple smaller radiators with individual flow control valves, the heat rejection requirements may be precisely adjusted. The combination of computer regulated thermal management system should reduce power consumption while satisfying temperature control objectives. This research focuses on developing and analyzing a multi-radiator system architecture for implementation in ground transportation applications. The premise is to use a single …

Essays On Perioperative Services Problems In Healthcare, Amogh S. Bhosekar

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One of the critical challenges in healthcare operations management is to efficiently utilize the expensive resources needed while maintaining the quality of care provided. Simulation and optimization methods can be effectively used to provide better healthcare services. This can be achieved by developing models to minimize patient waiting times, minimize healthcare supply chain and logistics costs, and maximize access. In this proposal, we study some of the important problems in healthcare operations management. More specifically, we focus on perioperative services and study scheduling of operating rooms (ORs) and management of necessary resources such as staff, equipment, and surgical instruments. We …

On Variants Of Sliding And Frank-Wolfe Type Methods And Their Applications In Video Co-Localization, Seyed Hamid Nazari

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In this dissertation, our main focus is to design and analyze first-order methods for computing approximate solutions to convex, smooth optimization problems over certain feasible sets. Specifically, our goal in this dissertation is to explore some variants of sliding and Frank-Wolfe (FW) type algorithms, analyze their convergence complexity, and examine their performance in numerical experiments. We achieve three accomplishments in our research results throughout this dissertation. First, we incorporate a linesearch technique to a well-known projection-free sliding algorithm, namely the conditional gradient sliding (CGS) method. Our proposed algorithm, called the conditional gradient sliding with linesearch (CGSls), does not require the …

Optimal Global Supply Chain And Warehouse Planning Under Uncertainty, Avnish Kishor Malde

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A manufacturing company's inbound supply chain consists of various processes such as procurement, consolidation, and warehousing. Each of these processes is the focus of a different chapter in this dissertation.

The manufacturer depends on its suppliers to provide the raw materials and parts required to manufacture a finished product. These suppliers can be located locally or overseas with respect to the manufacturer's geographic location. The ordering and transportation lead times are shorter if the supplier is located locally. Just In Time (JIT) or Just In Sequence (JIS) inventory management methods could be practiced by the manufacturer to procure the raw …

Adaptive Design And Flexible Approval Of Clinical Trials, Saeid Delshad Sisi

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Dose-finding clinical trials are among the most critical cornerstones of the healthcare system. In this broad research area, there are many decision making problems that are extremely challenging to address. However, a small improvement may result in significant benefits to the society. Dose-finding clinical trials are extremely expensive and require multiple time-consuming and complicated R&D phases. Despite all the costs and the long time these trials need to conclude (on average over ten years for each new drug/technology), only less than 15\% of these trials successfully end up in a new approved drug entering the market. This problem is even …

Improving Patient Safety, Patient Flow And Physician Well-Being In Emergency Departments, Vishnunarayan Girishan Prabhu

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Over 151 million people visit US Emergency Departments (EDs) annually. The diverse nature and overwhelming volume of patient visits make the ED one of the most complicated settings in healthcare to study. ED overcrowding is a recognized worldwide public health problem, and its negative impacts include patient safety concerns, increased patient length of stay, medical errors, patients left without being seen, ambulance diversions, and increased health system expenditure. Additionally, ED crowding has been identified as a leading contributor to patient morbidity and mortality. Furthermore, this chaotic working environment affects the well-being of all ED staff through increased frustration, workload, stress, …

Design And Operations Of A New Facility In A Next Generation Logistic System Based On Horizontal Collaboration, Dilhani Marasinghe

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The growing amount of freight combined with systemic inefficiencies are stressing current logistic systems. Including horizontal collaboration in the future could provide significant help but this strategy will require several new types of facilities. The most flexible type of horizontal collaboration, however, required freight routing decisions to be made dynamically, in real time, and based on last minute information. This research explores one new facility type operating in this environment that handles a high throughput of pallets or pallet-like containers. A key design feature is how much storage these facilities should have to better coordinate outbound loads. The approach taken …

Examining The Impact Of Design Features Of Electronic Health Records Patient Portals On The Usability And Information Communication For Shared Decision Making, Rong Yin

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The use of the Electronic Health Records (EHR) patient portal has been shown to be effective in generating positive outcomes in patients’ healthcare, improving patient engagement and patient-provider communication. Government legislation also required proof of its meaningful use among patients by healthcare providers. Typical patient portals also include features such as health information and patient education materials. However, little research has examined the specific use of patient portals related to individuals with specific diseases such as inflammatory bowel diseases (IBDs). IBDs are life-long, not curable, chronic diseases that can impact the whole population. Individuals with IBDs may have higher needs …

Double Tolerance Design In Stochastic Production Environments, Di Liu

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In a production process, it is impossible to produce parts with exact specifications. Thus, specific ranges, i.e., tolerances, are commonly employed to define intervals for the quality characteristics of conforming products (Wu & Tang (1998)). Usually, a product is deemed conforming when the measurement of the quality characteristic falls within the tolerance. If the measurement falls outside the tolerance, the product is nonconforming and it can be reworked or scrapped. One of the important engineering problems commonly faced by practitioners is to determine optimal engineering tolerances to be used in production. As a result, tolerance design techniques are widely used …

Design And Analysis Of Efficient Freight Transportation Networks In A Collaborative Logistics Environment, Vishal Badyal

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The increase in total freight volumes, reducing volume per freight unit, and delivery deadlines have increased the burden on freight transportation systems of today. With the evolution of freight demand trends, there also needs to be an evolution in the freight distribution processes. Today's freight transportation processes have a lot of inefficiencies that could be streamlined, thus preventing concerns like increased operational costs, road congestion, and environmental degradation. Collaborative logistics is one of the approaches where supply chain partners collaborate horizontally or/and vertically to create a centralized network that is more efficient and serves towards a common goal or objective. …

Selected Interdiction Games With Uncertain, Risk-Averse, And Simultaneous Play Considerations, Di H. Nguyen

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This dissertation examines two network interdiction problems: a shortest-path interdiction problem under uncertainty and a network interdiction problem in a simultaneous game. Both problems happen in two stages over a directed network, and involve a leader and a follower who have opposing interests.

In the first problem, the leader acts first to lengthen a subset of arcs, and a follower acts second to select a shortest path across the network. The cost for a follower’s arc consists of a base cost if the arc is not interdicted, plus an additional cost that is incurred if the arc is interdicted. The …

A Study Of Scheduling Problems With Sequence Dependent Restrictions And Preferences, Nitin Srinath

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In some applications like fabric dying, semiconductor wafer processing, and flexible manufacturing, the machines being used to process jobs must be set up and serviced frequently. These setup processes and associated setup times between jobs often depend on the jobs and the sequence in which jobs are placed onto machines. That is, the scheduling of jobs on machines must account for the sequence-dependent setup times as well. These setup times can be a major factor in operational costs. In fabric dyeing processes, the sequence in which jobs are processed is also important for quality, i.e., there is a strong preference …

An Algorithm For Biobjective Mixed Integer Quadratic Programs, Pubudu Jayasekara Merenchige

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Multiobjective quadratic programs (MOQPs) are appealing since convex quadratic programs have elegant mathematical properties and model important applications. Adding mixed-integer variables extends their applicability while the resulting programs become global optimization problems. Thus, in this work, we develop a branch and bound (BB) algorithm for solving biobjective mixed-integer quadratic programs (BOMIQPs). An algorithm of this type does not exist in the literature.

The algorithm relies on five fundamental components of the BB scheme: calculating an initial set of efficient solutions with associated Pareto points, solving node problems, fathoming, branching, and set dominance. Considering the properties of the Pareto set of …

Multistage Stochastic Programming: Algorithms, Modelling And Applications, Murwan Siddig

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This dissertation comprises four di˙erent topics related to multistage stochastic program-ming (MSP) algorithms, modeling, and applications.

First, we extend the adaptive partition-based approach for solving two-stage stochastic programs with a fixed recourse matrix and a fixed cost vector to the MSP setting, where the stochastic process is assumed to be stage-wise independent. The proposed algorithms integrate the adaptive partition-based strategy with a popular approach for solving multistage stochastic programs, the stochastic dual dynamic programming (SDDP) algorithm, according to two main strategies. These two strategies are distinct from each other in the manner by which they refine the partitions during the …

Nursing Interruption Dynamics: The Impact Of Work System Factors, Yushi Yang

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Interruptions occur frequently in healthcare work systems. Hands-free Communication Devices (HCDs) were implemented in healthcare work systems to support the interruption process. However, from a sociotechnical systems perspective, HCDs may introduce new complications and unintended consequences to the work system. Research gaps exist in investigating the complexity of HCD interruptions in the real-world context. This dissertation aims to understand HCD interruption dynamics in the nursing work systems, using qualitative research methods. The first study examined the major differences between face-to-face and HCD-mediated interruptions, based on 30 hours of field observations in the acute care setting. Three major differences included: (1) …

Linear Programming Methods For Identifying Solvable Cases Of The Quadratic Assignment Problem, Lucas Waddell

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This research effort is concerned with identifying and characterizing families of polynomially solvable instances of the celebrated NP-hard quadratic assignment problem (qap). The approach is novel in that it uses polyhedral methods based on an equivalent mixed 0-1 linear reformulation of the problem. The continuous relaxation of this mixed 0-1 form yields a feasible region having extreme points that are both binary and fractional. The solvable instances of concern essentially possess objective function structures that ensure a binary extreme point must be optimal, so that the linear program solves the qap. The ultimate contribution of this work is the unification …

Modeling Sustainability In Renewable Energy Supply Chain Systems, Fei Xie

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This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate 'environmental thinking' into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain …

Studies Of Imbalance Difference Theory In Modeling Conversion Between Differential Mode And Common Mode Signals, Li Niu

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This dissertation describes three related studies regarding the imbalance difference theory in modeling the conversion between differential mode and common mode/antenna mode signals. The topics covered are: rigorous derivation of imbalance difference theory for modeling radiated emission problems, modeling the conversion between differential mode and common mode propagation in transmission lines, and modeling the loading impedance on differential mode signals due to radiated emissions. The imbalance difference theory describes a method for calculating the coupling between differential mode signals and common mode signals due to changes in electrical balance on a transmission line. It provides both physical insight and a …

A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid

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This dissertation presents a novel comprehensive assessment methodology for using on-board photovoltaic (PV) solar technologies in vehicle applications. A well-to-wheels life cycle analysis based on a unique energy, greenhouse gas (GHG) emission, and economic perspective is carried out in the context of meeting corporate average fuel economy (CAFE) standards through 2025 along with providing an alternative energy path for the purpose of sustainable transportation. The study includes 14 different vehicles, 3 different travel patterns, in 12 U.S. states and 16 nations using 19 different cost analysis scenarios for determining the challenges and benefits of using on-board photovoltaic (PV) solar technologies …

Integrating Visual Mnemonics And Input Feedback With Passphrases To Improve The Usability And Security Of Digital Authentication, Kevin Juang

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The need for both usable and secure authentication is more pronounced than ever before. Security researchers and professionals will need to have a deep understanding of human factors to address these issues. Due to their ubiquity, recoverability, and low barrier of entry, passwords remain the most common means of digital authentication. However, fundamental human nature dictates that it is exceedingly difficult for people to generate secure passwords on their own. System-generated random passwords can be secure but are often unusable, which is why most passwords are still created by humans. We developed a simple system for automatically generating mnemonic phrases …

Two-Stage Methodology For Managing And Controlling Material Flow Between Multiple Construction Projects, Fatmah Almazkoor

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There is a strong connection between managing and controlling material flow in a supply chain and its performance. While this is true in all supply chains, it is particularly true in the construction supply chain (CSC) where the total demand for parts is finite, the storage space available can be small, and the variability in consumption is high. On the other hand, effectively controlling the CSC can have a significant impact on controlling risk and buffering their impact so that projects stay on schedule and within budget. Currently, a common control of the CSC is with a push-based material ordering …

Strategies To Improve The Efficiency Of Emergency Medical Service (Ems) Systems Under More Realistic Conditions, Kanchala Sudtachat

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Emergency medical service (EMS) systems provide medical care to pre-hospital patients who need rapid response and transportation. This dissertation proposes a new realistic approach for EMS systems in two major focuses: multiple unit dispatching and relocation strategies. This work makes recommendations for multiple-unit dispatch to multiple call priorities based on simulation optimization and heuristics. The objective is to maximize the expected survival rate. Simulation models are proposed to determine the optimization. A heuristic algorithm is developed for large-scale problems. Numerical results show that dispatching while considering call priorities, rather than always dispatching the closest medical units, could improve the effectiveness …

Characteristics And Contributing Factors Of Emergency Vehicle Crashes, Naji Abdelwanis

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The purpose of this study is to determine the contributing factors and characteristics associated with emergency vehicle(EV) crashes in order to generate insights about the emergency crashes. This dissertation consists of three approaches to address the purpose. In the first analysis a binary logistic regression model was used to identify the critical factors associated with EV crashes that resulted in fatality compared to those that did not. In the second analysis, an ordered regression model was used to identify critical factors that contributed to the severity of injuries that EV occupants experience in crashes as well as the effect of …

Predicting Surgical Flow Disruption Recovery In Cardiothoracic Operating Rooms, Gary Palmer Ii

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Disruptions are common occurrences in a variety of healthcare settings and early research has shown that they are likely contributors to medical errors. For this reason, healthcare researchers have focused on studying and understanding the nature of Surgical Flow Disruptions (SFDs) to increase patient safety and quality of care within the operating room (OR). Many researchers have used simplistic taxonomies to collect and categorize the types of SFD that occur within the OR. Others have gone further to study SFD recovery and have link unrecovered and recovered SFD to minor and major adverse events experienced by patients. This dissertation, focused …

Hybrid Low-Order Modeling For Conceptual Vehicle Design, Robert Mau

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Design freedom, and particularly the freedom to incorporate innovative designs and strategies, is greatest at the very beginning of vehicle conceptual design. Conversely, this is when the least knowledge of the product exists. As product content decisions are made the level of freedom in the design decreases and the design becomes "locked in." The majority of vehicle lifecycle cost is also set by the end of vehicle conceptual design. This makes it critical to make well-informed and validated decisions in the concept design phase to avoid expensive iterations and redesign in the detailed design phase. Parametric vehicle modeling permits rapid …

Joint Location And Dispatching Decisions For Emergency Medical Service Systems, Hector Toro-Diaz

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Emergency Medical Service (EMS) systems are a service that provides acute care and transportation to a place for definitive care, to people experiencing a medical emergency. The ultimate goal of EMS systems is to save lives. The ability of EMS systems to do this effectively is impacted by several resource allocation decisions including location of servers (ambulances), districting of demand zones and dispatching rules for the servers. The location decision is strategic while the dispatching decision is operational. Those two decisions are usually made separately although both affect typical EMS performance measures. The service from an ambulance is usually time …

Evolution Of Medication Administration Workflow In Implementing Electronic Health Record System, Yuan-Han Huang

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This study focused on the clinical workflow evolutions when implementing the health information technology (HIT). The study especially emphasized on administrating medication when the electronic health record (EHR) systems were adopted at rural healthcare facilities. Mixed-mode research methods, such as survey, observation, and focus group, were used to investigate insightful interventions to compensate potential errors during the medication administration process. Research data were collected from three South Carolina small-scale rural hospitals over several clinical departments.
The major purposes of this study were two folds: (1) to assess medical staff's computer competency for the new IT system, and (2) to investigate …

Prediction Of Subsurface Damage During Machining Nickel-Based Superalloys, Yujie Chen

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Nickel-based superalloys are widely utilized in hostile environments such as jet engines and gas turbines due to their high resistance to oxidation, high corrosion resistance, good thermal fatigue-resistance and fracture toughness. Subsurface damage is typically generated during the machining of these materials, and in particular, ã'-strengthened nickel-based superalloys. The depth of the subsurface damage is a critical requirement specified by the customer. Therefore, it is critical to predict, measure and control subsurface damage.
This research specifically targets the development of a model to predict subsurface damage during the machining of ã'-strengthened nickel-based superalloys. To accomplish this, a modified Johnson-Cook model …