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Articles 1 - 30 of 65
Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering
Nursing Interruption Dynamics: The Impact Of Work System Factors, Yushi Yang
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
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 ...
A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid
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 ...
Studies Of Imbalance Difference Theory In Modeling Conversion Between Differential Mode And Common Mode Signals, Li Niu
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 ...
Modeling Sustainability In Renewable Energy Supply Chain Systems, Fei Xie
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 ...
Two-Stage Methodology For Managing And Controlling Material Flow Between Multiple Construction Projects, Fatmah Almazkoor
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 ...
Integrating Visual Mnemonics And Input Feedback With Passphrases To Improve The Usability And Security Of Digital Authentication, Kevin Juang
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 ...
Strategies To Improve The Efficiency Of Emergency Medical Service (Ems) Systems Under More Realistic Conditions, Kanchala Sudtachat
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 ...
Predicting Surgical Flow Disruption Recovery In Cardiothoracic Operating Rooms, Gary Palmer Ii
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 ...
Characteristics And Contributing Factors Of Emergency Vehicle Crashes, Naji Abdelwanis
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 ...
Hybrid Low-Order Modeling For Conceptual Vehicle Design, Robert Mau
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
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 ...
Robust Parameter Design In Complex Engineering Systems:, Gregory Boylan
Robust Parameter Design In Complex Engineering Systems:, Gregory Boylan
Many industrial firms seek the systematic reduction of variability as a primary means for reducing production cost and material waste without sacrificing product quality or process efficiency. Despite notable advancements in quality-based estimation and optimization approaches aimed at achieving this goal, various gaps remain between current methodologies and observed in modern industrial environments. In many cases, models rely on assumptions that either limit their usefulness or diminish the reliability of the estimated results. This includes instances where models are generalized to a specific set of assumed process conditions, which constrains their applicability against a wider array of industrial problems. However ...
Evolution Of Medication Administration Workflow In Implementing Electronic Health Record System, Yuan-Han Huang
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 ...
Adaptive Model Based Combustion Phasing Control For Multi Fuel Spark Ignition Engines, Baitao Xiao
This research describes a physics-based control-oriented feed-forward model, combined with cylinder pressure feedback, to regulate combustion phasing in a spark-ignition engine operating on an unknown mix of fuels. This research may help enable internal combustion engines that are capable of on-the-fly adaptation to a wide range of fuels. These engines could; (1) facilitate a reduction in bio-fuel processing, (2) encourage locally-appropriate bio-fuels to reduce transportation, (3) allow new fuel formulations to enter the market with minimal infrastructure, and (4) enable engine adaptation to pump-to-pump fuel variations. These outcomes will help make bio-fuels cost-competitive with other transportation fuels, lessen dependence on ...
Prediction Of Subsurface Damage During Machining Nickel-Based Superalloys, Yujie Chen
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 ...
Managing Elective And Non-Elective Case Assignments For An Operating Room Suite, Narges Hosseini
The success of operating room management depends on all levels of decision making, from strategic to tactical and operational decisions. One key decision in systems with block booking is to assign sufficient amount of block time to surgeons and surgery groups. While the typical method of block assignment identifies the share of surgery groups from OR times based on average of past usage, this method does not count for the difference between cost of under and overtime. One of the goals of this research is to develop a decision framework for block assignment. This work is presented in chapter two ...
A Process Analysis Of Engineering Problem Solving And Assessment Of Problem Solving Skills, Sarah Grigg
In the engineering profession, one of the most critical skills to possess is accurate and efficient problem solving. Thus, engineering educators should strive to help students develop skills needed to become competent problem solvers. In order to measure the development of skills, it is necessary to assess student performance, identify any deficiencies present in problem solving attempts, and identify trends in performance over time. Through iterative assessment using standard assessment metrics, researchers/instructors are able to track trends in problem solving performance across time, which can serve as a gauge of students' learning gains.
This research endeavor studies the problem ...
Integrated Production And Distribution Problem With Single Perishable Product, Wennian Li
This dissertation investigated the extension of the Integrated Production and Distribution Scheduling Problem (IPDSPP) using a variety of perishable products, applying the JIP principle and make-to-order strategy to integrate the production and distribution schedules. A single perishable product with a constant lifetime after production was used in the model discussed here. The objective of the problem was to find the solution that results in minimal system total transportation costs while satisfying customer demand within a fixed time horizon. In the solution, the fleet size, vehicle route and distribution schedule, plant production batch size and schedule were determined simultaneously. This research ...
Flow Behavior Modeling And Process Control Of Electrically-Assisted Forming (Eaf) For Sheet Metals In Uniaxial Tension, Joshua Jones
This work studies the influence of an applied electrical current on magnesium sheet metal and introduces models which are successful in predicting the deformation behavior (i.e. material flow stress, local material strain, and thermal response). Also, this work examined the theory of electroplasticity by studying prior proposed theories and by quantifying the prior theories potential for improved dislocation mobility. From this analysis, a single dominant mechanism is determined and the theory of electroplasticity is explained using this single mechanism. The theory discussed in this work is supported by experimental testing and microstructure analysis.
In addition to studying the exact ...
Supply Chain Network Design: Risk-Averse Vs. Risk-Neutral Decision Making, Alireza Madadi
Recent events, such as the Heparin tragedy, highlight the necessity for designers and planners of supply chain networks to consider the risk of disruptions in spite of their low probability of occurrence. One effective way to hedge against supply chain network disruptions is to have a robustly designed supply chain network. This involves strategic decisions, such as choosing which markets to serve, which suppliers to source from, the location of plants, the types of facilities to use, and tactical decisions, such as production and capacity allocation. In this dissertation, we focus on models for designing supply chain networks that are ...
Updated Force Model For Milling Nickel-Based Superalloys, Andrew Henderson
Updated Force Model For Milling Nickel-Based Superalloys, Andrew Henderson
Nickel-based superalloys are commonly used in applications which require high strength and resistance to creep and oxidation in extreme conditions. All nickel-based superalloys are considered difficult to machine; however, cast gamma-prime-strengthened nickel-based superalloys are more difficult to machine than common nickel-based superalloys. Machining comprises a significant portion of manufacturing processes and with advancements in technology and material properties, the methods and models used must be adapted in order to keep pace.
In this research, correlations are made, using fundamental principles, between measurements made with on-machine touch probes and the cutting tool's wear state, those correlations are used in an ...
Districting And Dispatching Policies To Improve The Efficiency Of Emergency Medical Service (Ems) Systems, Damitha Bandara
The major focus of Emergency Medical Service (EMS) systems is to save lives and to minimize the
effects of emergency health incidents. The efficiency of the EMS systems is a major public concern. Thus,
over the past three decades a significant amount of research studies have been conducted to improve the performance
of EMS systems. The purpose of this study is also to improve the performance of EMS system.
The contribution of this research towards improving the performance of EMS systems is twofold. One area
is to implement optimal or near optimal dispatching strategies for EMS systems and the other ...
Prognostic And Health-Management Oriented Fuel Cell Modeling And On-Line Supervisory System Development, Xian Zhang
Of the fuel cells being studied, the proton exchange membrane fuel cell (PEMFC) is viewed as the most promising for transportation. Yet until today, the commercialization of the PEMFC has not been widespread in spite of its large expectation. Poor long term performances or durability, and high production and maintenance costs are the main reasons. For the final commercialization of fuel cells in the transportation field, durability issues must be addressed, while costs should be further brought down. At the same time, health-monitoring and prognosis techniques are of great significance in terms of scheduling condition-based maintenance (CBM) to minimize repair ...
Thermo-Mechanical Modeling Of The Electrically-Assisted Manufacturing (Eam) Technique During Open Die Forging, Wesley Salandro
This thesis contains all of the steps which allow the Electrically-Assisted Manufacturing (EAM) technique to be experimentally explored and analytically modeled for an electrically-assisted forging operation. Chapter 1 includes the problem statement, proposed solution, and literature reviews on EAM. Chapter 2 describes a thorough background on the EAM technique, highlights prior EAM research, and explains the research approach taken for this thesis. The coupled thermo-mechanical modeling strategy, along with the introduction of the Electroplastic Effect Coefficient (EEC) is provided in Chapter 3. Chapter 4 explains the two different approaches to determine the EEC profiles when modeling a particular metal. The ...
Algebraic Approaches To Stochastic Optimization, Katherine Hastings
Algebraic Approaches To Stochastic Optimization, Katherine Hastings
The dissertation presents algebraic approaches to the shortest path and maximum flow problems in stochastic networks. The goal of the stochastic shortest path problem is to find the distribution of the shortest path length, while the goal of the stochastic maximum flow problem is to find the distribution of the maximum flow value. In stochastic networks it is common to model arc values (lengths, capacities) as random variables. In this dissertation, we model arc values with discrete non-negative random variables and shows how each arc value can be represented as a polynomial. We then define two algebraic operations and use ...
Research And Development Effort In Developing The Optimal Formulations For New Tablet Drugs, Zhe Li
Seeking the optimal pharmaceutical formulation is considered one of the most critical research components during the drug development stage. It is also an R&D effort incorporating design of experiments and optimization techniques, prior to scaling up a manufacturing process, to determine the optimal settings of ingredients so that the desirable performance of related pharmaceutical quality characteristics (QCs) specified by the Food and Drug Administration (FDA) can be achieved. It is widely believed that process scale-up potentially results in changes in ingredients and other pharmaceutical manufacturing aspects, including site, equipment, batch size and process, with the purpose of satisfying the clinical and market demand. Nevertheless, there has not been any single comprehensive research work on how to model and optimize the pharmaceutical formulation when scale-up changes occur. Based upon the FDA guidance, the documentation tests for scale-up changes generally include dissolution comparisons and bioequivalence studies. Hence, this research proposes optimization models to ensure the equivalent performance in terms of dissolution and bioequivalence for the pre-change and post-change formulations by extending the existing knowledge of formulation optimization. First, drug professionals traditionally consider the mean of a QC only; however, the variability of the QC of interest is essential because large variability may result in unpredictable safety and efficacy issues. In order to simultaneously take into account the mean and variability of the QC, the Taguchi quality loss concept is applied to the optimization procedure. Second, the standard 2×2 crossover design, which is extensively conducted to evaluate bioequivalence, is incorporated into the ordinary experimental scheme so as to investigate the functional relationships between the ...
A Comprehensive Human Factors Analysis Of Off-Duty Motor Vehicle Crashes In The United States Military, Rebecca Iden
Researchers have always had great interest in traffic safety and the phenomenon of motor vehicle crashes (MVCs). Though scores of service members are severely injured or killed in off-duty MVCs each year, few studies have addressed the MVC phenomenon within the military population and none have conducted a comprehensive evaluation of the causal factors associated with MVCs involving military personnel.
The main purpose of this dissertation was to gain a greater understanding of the causal factors associated with serious and fatal off-duty personal MVCs for military service members with the ultimate goal of preventing future losses. The HFACS-MVC framework was ...
Extending Origami Technique To Fold Forming Of Sheet Metal Products, Ala Qattawi
This dissertation presents a scientific based approach for the analysis of folded sheet metal products. Such analysis initializes the examination in terms of topological exploration using set of graph modeling and traversal algorithms. The geometrical validity and optimization are followed by utilizing boundary representation and overlapping detection during a geometrical analysis stage, in this phase the optimization metrics are established to evaluate the unfolded sheet metal design in terms of its manufacturability and cost parameters, such as nesting efficiency, total welding cost, bend lines orientation, and maximum part extent, which aides in handling purposes. The proposed approach evaluates the design ...
The Effects Of Weather Recognition Training On General Aviation Pilot Situation Assessment And Tactical Decision Making When Confronted With Adverse Weather Conditions, Chansik Kim
Previous general aviation (GA) accident studies showed that decision errors were more associated with fatal GA accidents than other kinds of human errors, and weather related accidents, especially continued visual flight rules (VFR) flight into instrument meteorological conditions (IMC), remained the major cause of fatal GA accidents. Thus, finding the underlying causes of GA pilots' decision errors and continued VFR flight into adverse weather conditions are needed to reduce weather related GA accidents as well as fatal GA accidents.
Causal factors and hypotheses of weather related GA accidents show that knowledge, experience, motivation, and weather information frequently have been referred ...