Engineering Commons^™

The Effects Of Blue Light From Digital Displays On Visual Fatigue, Victor Taboadela

Theses

With the ever-increasing viewing time of digital displays, the potential effects of blue light emitted from these displays on eye health and eye fatigue are a real concern. This study presents a literature review of six laboratory studies conducted between 2014 and 2022 on the effect of using filters to attenuate the harmful effects of blue light. The review delves into smartphone and computer screen effects, recent literature reviews on blue light, and potential hazards associated with short-wavelength light. Although the majority of the studies recommended blue light filters, only three of the six laboratory studies (Shi et al. 2021, …

Integrated Machine Learning And Optimization Approaches, Dogacan Yilmaz

Dissertations

This dissertation focuses on the integration of machine learning and optimization. Specifically, novel machine learning-based frameworks are proposed to help solve a broad range of well-known operations research problems to reduce the solution times. The first study presents a bidirectional Long Short-Term Memory framework to learn optimal solutions to sequential decision-making problems. Computational results show that the framework significantly reduces the solution time of benchmark capacitated lot-sizing problems without much loss in feasibility and optimality. Also, models trained using shorter planning horizons can successfully predict the optimal solution of the instances with longer planning horizons. For the hardest data set, …

Computation Of Risk Measures In Finance And Parallel Real-Time Scheduling, Yajuan Li

Dissertations

Many application areas employ various risk measures, such as a quantile, to assess risks. For example, in finance, risk managers employ a quantile to help determine appropriate levels of capital needed to be able to absorb (with high probability) large unexpected losses in credit portfolios comprising loans, bonds, and other financial instruments subject to default. This dissertation discusses the computation of risk measures in finance and parallel real-time scheduling.

Firstly, two estimation approaches are compared for one risk measure, a quantile, via randomized quasi-Monte Carlo (RQMC) in an asymptotic setting where the number of randomizations for RQMC grows large, but …

Optimizing Incentives For Systems With Heterogeneous Agents, Chen Chen

Dissertations

This dissertation explores new models and applications based on the game theory of incentives. This exploration starts with controlling an invasive insect problem to address one of the most significant challenges facing our forests, the invasion of the Emerald ash borer (EAB), a non-native, wood-boring insect that threatens to kill most ash trees in North America, through designing two new cost-sharing programs between the landowners and local governments. Ash trees are one of North America’s most widely distributed tree genera and a vital part of the green infrastructure of cities, where they provide residents with numerous social, economic, and ecological …

Multi-Stage Stochastic Optimization And Reinforcement Learning For Forestry Epidemic And Covid-19 Control Planning, Sabah Bushaj

Dissertations

This dissertation focuses on developing new modeling and solution approaches based on multi-stage stochastic programming and reinforcement learning for tackling biological invasions in forests and human populations. Emerald Ash Borer (EAB) is the nemesis of ash trees. This research introduces a multi-stage stochastic mixed-integer programming model to assist forest agencies in managing emerald ash borer insects throughout the U.S. and maximize the public benets of preserving healthy ash trees. This work is then extended to present the first risk-averse multi-stage stochastic mixed-integer program in the invasive species management literature to account for extreme events. Significant computational achievements are obtained using …

Stochastic Programming And Agent-Based Simulation Approaches For Epidemics Control And Logistics Planning, Xuecheng Yin

Dissertations

This dissertation addresses the resource allocation challenges of fighting against infectious disease outbreaks. The goal of this dissertation is to formulate multi-stage stochastic programming and agent-based models to address the limitations of former literature in optimizing resource allocation for preventing and controlling epidemics and pandemics. In the first study, a multi-stage stochastic programming compartmental model is presented to integrate the uncertain disease progression and the logistics of resource allocation to control a highly contagious infectious disease. The proposed multi-stage stochastic program, which involves various disease growth scenarios, optimizes the distribution of treatment centers and resources while minimizing the total expected …

Constructive Solution Methodologies To The Capacitated Newsvendor Problem And Surrogate Extension, Pinyuan Shan

Dissertations

The newsvendor problem is a single-period stochastic model used to determine the order quantity of perishable product that maximizes/minimizes the profit/cost of the vendor under uncertain demand. The goal is to fmd an initial order quantity that can offset the impact of backlog or shortage caused by mismatch between the procurement amount and uncertain demand. If there are multiple products and substitution between them is feasible, overstocking and understocking can be further reduced and hence, the vendor's overall profit is improved compared to the standard problem. When there are one or more resource constraints, such as budget, volume or weight, …

Electric Field Induced Self-Assembly Of Mesoscale Structured Materials And Smart Fluids, Suchandra Das

Dissertations

This dissertation aims to study the forces that drive self-assembly in binary mixtures of particles suspended in liquids and on fluid-liquid interfaces when they are subjected to a uniform electric or magnetic field. Three fluid-particle systems are investigated experimentally and theoretically : (i) Suspensions of dielectric particles in dielectric liquids; (ii) Suspensions of ferromagnetic and diamagnetic particles in ferrofluids; and (iii) Dielectric particles on dielectric fluid-liquid interfaces. The results of these studies are then used to estimate the parameter values needed to assemble materials with desired mesoscale microstructures.

The first fluid-particle system studied is an electrorheological (ER) fluid formed using …

Service Quality Assessment And Improvement Methods And Tools, Kevin M. Moriarty

Dissertations

The nucleus of this research concept and system is being applied to turret lathe and milling machine Computer Numerical Control (CNC) tool systems. The research has a generic application to the service of broad array of sophisticated computer controlled / integrated machines, devices / equipment such as industrial robotics, medical equipment, surgical robots, and similar types of engineered system. Quality design review for quality service systems is a unique concept. Standard product service systems are qualitative and subjective in nature. The quantitative system identifies Key Predictive Attributes (KPAs) and applies quantitative methods to these attributes to develop a systematic process …

Online Fulfillment: F-Warehouse Order Consolidation And Bops Store Picking Problems, Wen Zhu

Dissertations

Fulfillment of online retail orders is a critical challenge for retailers since the legacy infrastructure and control methods are ill suited for online retail. The primary performance goal of online fulfillment is speed or fast fulfillment, requiring received orders to be shipped or ready for pickup within a few hours. Several novel numerical problems characterize fast fulfillment operations and this research solves two such problems. Order fulfillment warehouses (F-Warehouses) are a critical component of the physical internet behind online retail supply chains. Two key distinguishing features of an F-Warehouse are (i) Explosive Storage Policy – A unique item can be …

A Comprehensive And Absolute Corporate Sustainability Assessment And Enhanced Input Output Life Cycle Assessment, Joseph M. Wright

Dissertations

Stresses due to economic activity are threatening to exceed environmental and societal limits with the potential to jeopardize local communities and create global crises. This research proposes new methodologies and analytic techniques to comprehensively assess corporate sustainability and enhance the efficiency of estimating environmental and social impacts with Input Output Life Cycle Assessment (IOLCA).

Sustainability assessments and management require consideration of both social and environmental impacts as outflows of economic activity. There are a number of assessment tools available to gain insight into environmental and social impacts; but in most cases, these approaches lack essential components for a comprehensive and …

Interventions Of Waterjet Technology In Skin Incisions, Nadi Atalla

Dissertations

This research explores the use of waterjet (WJ) technology in performing skin incisions. The study defines the analytical relationships between the skin properties and the operating parameters of the WJ which include the skin thickness, its elastic modulus, the WJ pressure, the nozzle’s orifice diameter, its stand-off distance and the traverse speed of the WJ as well as the duration of applying the WJ pressure. An analytical model is developed to measure the depth incision of the skin, the water pressure and the water velocity, while using a WJ. Systemization and optimization models that determine the optimal operating parameters levels …

Design And Implementation Of An Automated Oil Distribution System For A Homogenizer Machine In Gea Mechanical Equipment – Niro Soavi, Luca Gandolfi

Theses

This thesis shows the steps that have been followed and done in order to improve a critical operation of a technological process of the GEA Mechanical Equipment. The critical operation was the filling with different types of oils the homogenizing machine because it was characterized by a lot of inefficiencies and, in particular, by huge risks for job security. These critical issues gave the opportunity and the chance to realize a project in order to give a process optimization and security improvement.

After having faced all the aspects and steps needed for this project, it has been realized a system …

Assignment Of E-Commerce Orders To Fulfillment Warehouses, Ahmad Basem Zamka

Theses

For large e-commerce companies such as Amazon, when an order comes, this order might be available at more than one fulfillment centers. Therefore, the question of which fulfillment center this order should be fulfilled from would arise.

In a typical situation, customer demand is fulfilled from the closest fulfillment center. However, this approach does not always provide the optimal solution since there are so many factors that could be involved in making such a decision. These factors might include inventory balance, product correlations, and future demand.

Our decision model focuses on putting future orders in consideration while assigning orders to …

Evaluating The Impact Of Adopting 3d Printing Services On The Retailers, Sharareh Rajaei Dehkordi

Dissertations

As additive manufacturing technology becomes more responsive to consumers’ demand, one important question for the retailers is whether they should provide 3D printing services in their brick-and-mortar store in addition to the traditional off-the-shelf product? If so, what should be the retailers pricing scheme to achieve a higher profit? What should be the optimal inventory level of off-the-shelf products? What is the optimal capacity of 3D printers? In this study, stochastic models are examined to capture the joint optimal 3D product price and capacity of 3D printers to maximize retailer’s expected profit while considering consumer product choices. Moreover, a stochastic …

Appointment Planning And Scheduling In Primary Care, Babak Hoseini

Dissertations

The Affordable Care Act (ACA) puts greater emphasis on disease prevention and better quality of care; as a result, primary care is becoming a vital component in the health care system. However, long waits for the next available appointments and delays in doctors offices combined with no-shows and late cancellations have resulted in low efficiency and high costs.

This dissertation develops an innovative stochastic model for patient planning and scheduling in order to reduce patients’ waiting time and optimize primary care providers’ utility. In order to facilitate access to patients who request a same-day appointment, a new appointment system is …

Decision Models For Fast-Fashion Supply And Stocking Problems In Internet Fulfillment Warehouses, Jingran Zhang

Dissertations

Internet technology is being widely used to transform all aspects of the modern supply chain. Specifically, accelerated product flows and wide spread information sharing across the supply chain have generated new sets of decision problems. This research addresses two such problems. The first focuses on fast fashion supply chains in which inventory and price are managed in real time to maximize retail cycle revenue. The second is concerned with explosive storage policies in Internet Fulfillment Warehouses (IFW).

Fashion products are characterized by short product life cycles and market success uncertainty. An unsuccessful product will often require multiple price discounts to …

Airspace Analysis For Greener Operations: Towards More Adoptability And Predictability Of Continuous Descent Approach (Cda), Emad Ali Alharbi

Dissertations

Continuous Descent Approach (CDA), also known as Optimized Profile Descent (OPD), is the advanced flight technique for commercial aircraft to descend continuously from cruise altitude to Final Approach Fix (FAF) or touchdown without level-offs and with- or near-idle thrust setting. Descending using CDA, aircraft stays as high as possible for longer time thereby expanding the vertical distance between aircraft's sources of noise and ground, and thus significantly reducing the noise levels for populated areas around airports. Also, descending with idle engines, fuel burn is reduced resulting in reduction of harmful emissions to the environment and fuel consumption to air carriers. …

Design And Optimization Of An Explosive Storage Policy In Internet Fulfillment Warehouses, Sevilay Onal

Dissertations

This research investigates the warehousing operations of internet retailers. The primary physical process in internet retail is fulfillment, which typically involves a large internet fulfillment warehouse (IFW) that has been built and designed exclusively for online sales and an accompanying parcel delivery network. Based on observational studies of IFW operations at a leading internet retailer, the investigations find that traditional warehousing methods are being replaced by new methods which better leverage information technology and efficiently serve the new internet retail driven supply chain economy. Traditional methods assume a warehouse moves bulk volumes to retail points where the bulks get broken …

Collaborative Rescheduling Of Flights In A Single Mega-Hub Network, Sufian Ikhmeis

Dissertations

Traditionally, airlines have configured flight operations into a Hub and Spoke network design. Using connecting arrival departure waves at multiple hubs these networks achieve efficient passenger flows. Recently, there has been much growth in the development of global single mega-hub (SMH) flight networks that have a significantly different operating cost structure and schedule design. These are located primarily in the Middle East and are commonly referred to as the ME3. The traditionalist view is that SMH networks are money losers and subsidized by sovereign funds.

This research studies and analyzes SMH networks in an attempt to better understand their flight …

Extracting Product Development Intelligence From Web Reviews, Ismail Artun Yagci

Dissertations

Product development managers are constantly challenged to learn what the consumer product experience really is, and to learn specifically how the product is performing in the field. Traditionally, they have utilized methods such as prototype testing, customer quality monitoring instruments, field testing methods with sample customers, and independent assessment companies. These methods are limited in that (i) the number of customer evaluations is small, and (ii) the methods are driven by a restrictive structured format. Today the web has created a new source of product intelligence; these are unsolicited reviews from actual product users that are posted across hundreds of …

Performance Analysis And Scheduling Strategies For Ambulatory Surgical Facilities, Xuanqi Zhang

Dissertations

Ambulatory surgery is a procedure that does not require an overnight hospital stay and is cost effective and efficient. The goal of this research is to develop an ASF operational model which allows management to make key decisions. This research develops and utilizes the simulation software ARENA based model to accommodate: (a) Time related uncertainties – Three system uncertainties characterize the problem (ii) Surgery time variance (ii) Physician arrival delay and (iii) Patient arrival delay; (b) Resource Capture Complexities – Patient flows vary significantly and capture/utilize both staffing and/or physical resources at different points and varying levels; and (c) Processing …

Hosx: Hospital Operations Excellence Model, Shivon S. Boodhoo

Dissertations

Hospital performance can be evaluated in four categories: (i) quality of care, (ii) process of care (iii) financial and (iv) operations productivity. Of these, ‘quality of care’ is the most widely reported and studied measure of performance, and focuses primarily on the clinical outcomes of the patient. In contrast, operations productivity and efficiency is the least studied measure, and currently there is limited ability to evaluate how efficiently the hospital has used its resources to deliver healthcare services. Cost containment in the healthcare industry is a challenging problem, and there is a lack of models and methods to benchmark hospital …

The Floating Contract Between Risk-Averse Supply Chain Partners In A Volatile Commodity Price Environment, Mojisola Kike Otegbeye

Dissertations

In this dissertation, two separate but closely related decision making problems in environments of volatile commodity prices are addressed. In the first problem, a risk-averse commodity user's purchasing policy and his risk-neutral supplier's pricing decision, where the user can purchase his needs through contract with his supplier as well as directly from the spot market, are analyzed. The commodity user is assumed to be the supplier's sole client, and the supplier can always expand capacity, at a cost to the user, to accommodate the user's demand in excess of initially reserved capacity.

In the more generalized second problem, both parties …

Resource Assignment In Short Life Technology Intensive (Slti) New Product Development (Npd), Randy A. Reagan

Dissertations

Enterprises managing multiple concurrent New Product Development (NPD) projects face significant challenges assigning staff to projects in order to achieve launch schedules that maximize financial returns. The challenge is increased with the class of Short Life Technology Intensive (SLTI) products characterized by technical complexity, short development cycles and short revenue life cycles. Technical complexity drives the need to assign staffing resources of various technical disciplines and skill levels. SLTI products are rapidly developed and launched into stationary market windows where the revenue life cycle is short and decreasing with any time-to-market delay. The SLTI-NPD project management decision is to assign …

End-Of-Life Analysis Of Nanotechnology Products, Sun Olapiriyakul

Dissertations

Previous research has shown that thermodynamic properties including melting point and specific heat capacity of nanomaterials may be higher than that of their corresponding bulk materials. The melting point elevation and specific heat capacity enhancement of nanomaterials may result in increased energy consumption and waste gases emission at the end-of-life (EOL) stage where the products containing nanomaterials are recycled by high temperature metal recovery (HTMR) process.

In this dissertation, the effect of physical characteristics of nanomaterials, referred to as physicochemical parameters, on their melting temperature and specific heat capacity was investigated. In addition, physical, chemical, and thermodynamic properties of nanomaterials …

Optimizing Replenishment Order Quantities In Uncoordinated Supply Chains, Atipol Kanchanapiboon

Dissertations

Many modern supply chains can be described as a series of uncoordinated suppliers. That is each supplier establishes their individual inventory and production policies on both the input and output sides. In these supply links there is minimal coordination between suppliers, and typically only prices and delivery guarantees are contracted. As a consequence, the inventory behavior and associated costs do not exhibit standard patterns. This makes it difficult to model and optimize these chains using classical inventory models. The common approach, therefore, for evaluating uncoordinated supply chains is to use Supply Chain Analytics software. These retrieve operational data from Enterprise …

Service Supply Chain Management : A Hierarchical Decision Modeling Approach, Roger Angel Solano-Cayama

Dissertations

A Service Supply Chain (SSC) may be described as a network of service provider facilities (in-house or outsourced), each of which is able to process one or more service tasks on an as needed basis. Two key characteristics of a SSC are (i) the business service is decomposable into several sequential tasks that can be processed by different service providers, and (ii) the primary capacity resource is skilled labor. SSCs are increasingly being developed by companies that experience a high variability of demand for their services (e.g., loan processing, analytical consulting services, emergency repair crews, claims processing, etc.). Typically, the …

Modeling Inventory And Responsiveness Costs In A Supply Chain, Robert Nearier

Dissertations

Evaluation of supply chain performance is often complicated by the various interrelationships that exist within the network of suppliers. Currently many supply chain metrics cannot be analytically determined. Instead, metrics are derived from monitoring historical data, which is commonly referred to as Supply Chain Analytics. With these analytics it is possible to answer questions such as: What is the inventory cost distribution across the chain? What is the actual inventory turnover ratio? What is the cost of demand changes to individual suppliers? However, this approach requires a significant amount of historical data which must be continuously extracted from the associated …

On The Design For Flexibility Of Manufacturing Systems : A Stochiastic Approach, Nathapol Areeratchakul

Dissertations

Flexibility has emerged as one of the most strategic imperatives for company viability in today's fast paced economy. This realization has stimulated extensive research efforts in this area most of which have focused mainly on defining flexibility and its attributes, the need for flexibility and how to measure it. Nevertheless, despite the considerable amount of publications regarding flexibility and its related subjects, insufficient attention has been given to the optimality of the design for flexibility and the inherent needs to meet uncertainty. Bridging this gap is the intent of this work.

In this dissertation, developed analytical models are for the …