Operations Research, Systems Engineering and Industrial Engineering Commons^™

Utilization Of Integer Programming For Scheduling Maintenance At Nuclear Power Plants, Timothy Gallacher

Doctoral Dissertations

This thesis develops a thought that naturally explores three specific motifs for solving the complexities of scheduling maintenance at Nuclear Power Plants (NPP). The first chapter of this paper will develop the initial thought around creating a schedule for a given work week, including all the various constraints inherent to this problem. Such constraints include but are not limited to personnel availability, allowable component out-of-service time, and the Plant Risk Assessment. The objective function being to minimize the total cost of worker’s compensation for that given week.

The second chapter addresses the question of whether this simple schedule can be …

Optimal Scheduling Of Aircraft Test And Evaluation Fleets To Balance Availability For Testing And Training, Sarah E. Hoops

Theses and Dissertations

The 96th Test Wing at Eglin Air Force Base manually schedules a fleet of approximately 26 aircraft to conduct a range of missions over a one-to-two year planning period. This study automates the scheduling process, does so in a manner that optimizes multiple planning goals related to aircraft availability for training, and provides the 96th Test Wing with a software tool for the implementation that can be used by operational analysts within the command. We formulate the scheduling problem as a multiobjective, nonlinear, binary integer math program that seeks to maximize both the lowest percent of time any aircraft is …

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

All Dissertations

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 …

Scheduling, Complexity, And Solution Methods For Space Robot On-Orbit Servicing, Susan E. Sorenson

Graduate Theses and Dissertations

This research proposes problems, models, and solutions for the scheduling of space robot on-orbit servicing. We present the Multi-Orbit Routing and Scheduling of Refuellable On-Orbit Servicing Space Robots problem which considers on-orbit servicing across multiple orbits with moving tasks and moving refuelling depots. We formulate a mixed integer linear program model to optimize the routing and scheduling of robot servicers to accomplish on-orbit servicing tasks. We develop and demonstrate flexible algorithms for the creation of the model parameters and associated data sets. Our first algorithm creates the network arcs using orbital mechanics. We have also created a novel way to …

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

All Dissertations

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 …

A Deep Reinforcement Learning Approach With Prioritized Experience Replay And Importance Factor For Makespan Minimization In Manufacturing, Jose Napoleon Martinez

LSU Doctoral Dissertations

In this research, we investigated the application of deep reinforcement learning (DRL) to a common manufacturing scheduling optimization problem, max makespan minimization. In this application, tasks are scheduled to undergo processing in identical processing units (for instance, identical machines, machining centers, or cells). The optimization goal is to assign the jobs to be scheduled to units to minimize the maximum processing time (i.e., makespan) on any unit.

Machine learning methods have the potential to "learn" structures in the distribution of job times that could lead to improved optimization performance and time over traditional optimization methods, as well as to adapt …

Quality And Productivity Improvements In Additive Manufacturing, Huseyin Kose

Doctoral Dissertations

Additive manufacturing (AM) is a relatively new manufacturing technology compared to the traditional manufacturing methods. Even though AM processes have many advantages, they also have a series of challenges that need to be addressed to adapt this technology for a wide range of applications and mass production.

AM faces a number of challenges, including the absence of methods/models for determining whether AM is the best manufacturing process for a given part. The first study of this thesis proposes a framework for choosing specific AM processes by considering the complexity level of a part. It has been proven that the method …

Bi-Objective Optimization For A Single Batch Processing Machine, Leena Omar Ghrayeb

Graduate Research Theses & Dissertations

This research proposes a methodology for solving the problem of scheduling jobs with unequal ready times, unequal processing times, and unequal sizes on a single batch processing machine, with the objectives of minimizing makespan and maximum tardiness. Jobs must be placed into batches and scheduled on the machine such that both objectives are minimized, and machine capacity is not violated. The problem under study can be denoted as 1|p-batch, sj, rj| Cmax,Tmax. Based on a review of relevant literature, this problem has not been considered before.

The problem under study is NP-hard. Consequently, meta-heuristics such as Simulated Annealing (SA) and …

Balancing Labor Requirements In A Manufacturing Environment, Patrick Bernard Dwyer

Doctoral Dissertations

“This research examines construction environments within manufacturing facilities, specifically semiconductor manufacturing facilities, and develops a new optimization method that is scalable for large construction projects with multiple execution modes and resource constraints. The model is developed to represent real-world conditions in which project activities do not have a fixed, prespecified duration but rather a total amount of work that is directly impacted by the level of resources assigned. To expand on the concept of resource driven project durations, this research aims to mimic manufacturing construction environments by allowing a non-continuous resource allocation to project tasks. This concept allows for resources …

A Bridge And Engine Room Staffing And Scheduling Model For Robust Mission Accomplishment In The Littoral Combat Ships, John P. Cordle

Engineering Management & Systems Engineering Projects for D. Eng. Degree

The Navy’s Littoral Combat Ships were designed to be relatively small surface vessels for operations near a littoral shore theater. These ships were envisioned to be highly automated, networked, agile, stealthy surface combatants capable of defeating anti-access and asymmetric threats in the littorals with minimum manpower. To date, however, some of these ships have experienced significant engineering and propulsion plant failures that impacted mission accomplishment and were attributable, at least in part, to under staffing and over scheduling the human component of the automation-human operational environment. The critical human components on the Littoral Combat Ship are bridge and engine room …

Sky Surveys Scheduling Using Reinforcement Learning, Andres Felipe Alba Hernandez

Graduate Research Theses & Dissertations

Modern cosmic sky surveys (e.g., CMB S4, DES, LSST) collect a complex diversity of astronomical objects. Each of class of objects presents different requirements for observation time and sensitivity. For determining the best sequence of exposures for mapping the sky systematically, conventional scheduling methods do not optimize the use of survey time and resources. Dynamic sky survey scheduling is an NP-hard problem that has been therefore treated primarily with heuristic methods. We present an alternative scheduling method based on reinforcement learning (RL) that aims to optimize the use of telescope resources for scheduling sky surveys.

We present an exploration of …

Minimizing Total Number Of Tardy Jobs In Parallel Batch Processing Machines Using Column Generation And Simulated Annealing, Sameer Neupane

Graduate Research Theses & Dissertations

This research considers a scheduling problem where jobs need to be grouped into batches and the batches need to be scheduled on parallel batch processing machines with an objective to minimize the total number of tardy jobs. The jobs are assigned to batches in such a way that machine capacity is not violated. This research considers jobs with unequal ready times, unequal processing times and unequal sizes. The machines are identical in processing capabilities; however, their capacities are different. This research aims to develop effective solution approaches to solve the problem under study. A Mixed Integer Linear Programming (MILP) model …

Pharmaceutical Scheduling Using Simulated Annealing And Steepest Descent Method, Bryant Jamison Spencer

Graduate Theses, Dissertations, and Problem Reports

In the pharmaceutical manufacturing world, a deadline could be the difference between losing a multimillion-dollar contract or extending it. This, among many other reasons, is why good scheduling methods are vital. This problem report addresses Flexible Flowshop (FF) scheduling using Simulated Annealing (SA) in conjunction with the Steepest Descent heuristic (SD).

FF is a generalized version of the flowshop problem, where each product goes through S number of stages, where each stage has M number of machines. As opposed to a normal flowshop problem, all ‘jobs’ do not have to flow in the same sequence from stage to stage. The …

Trade-Off Balancing For Stable And Sustainable Operating Room Scheduling, Amin Abedini

Theses and Dissertations--Mechanical Engineering

The implementation of the mandatory alternative payment model (APM) guarantees savings for Medicare regardless of participant hospitals ability for reducing spending that shifts the cost minimization burden from insurers onto the hospital administrators. Surgical interventions account for more than 30% and 40% of hospitals total cost and total revenue, respectively, with a cost structure consisting of nearly 56% direct cost, thus, large cost reduction is possible through efficient operation management. However, optimizing operating rooms (ORs) schedules is extraordinarily challenging due to the complexities involved in the process. We present new algorithms and managerial guidelines to address the problem of OR …

Methods To Support The Project Selection Problem With Non-Linear Portfolio Objectives, Time Sensitive Objectives, Time Sensitive Resource Constraints, And Modeling Inadequacies, Neil C. Ranly

Theses and Dissertations

The United States Air Force relies upon information production activities to gain insight regarding uncertainties affecting important system configuration and in-mission task execution decisions. Constrained resources that prevent the fulfillment of every information production request, multiple information requestors holding different temporal-sensitive objectives, non-constant marginal value preferences, and information-product aging factors that affect the value-of-information complicate the management of these activities. This dissertation reviews project selection research related to these issues and presents novel methods to address these complications. Quantitative experimentation results demonstrate these methods’ significance.

The Developmental Test Scheduling Problem, Joseph E. Schoenbeck

Theses and Dissertations

Developmental testing of aircraft systems in the United States Air Force requires a complex set of resources for each test. The optimal scheduling of those resources is the job of the 412th Test Wing at Edwards Air Force Base. With more than 20 different Combined Task Forces requesting resources for roughly 300 flying missions each week, manual scheduling is a difficult task. The current process takes a team of schedulers several days to get a workable result from which they can start tailoring the final schedule. While concepts and techniques can be taken from industry scheduling problems, the body of …

Methodologies For Solving Integrated Transportation And Scheduling Problems, Fereydoun Adbesh

Graduate Theses and Dissertations

This research proposes novel solution techniques to optimize two real-world problems in the area of scheduling and transportation. We first consider a model for optimizing the operations of dredges. In this problem, scheduling and assignment decisions are integrated across a finite planning horizon. Additional constraints and problem elements explicitly considered include, but are not limited, to environmental work window restrictions, budget limitations, dredge operation rates and schedule-dependent dredge availability. Our approach makes use of Constraint Programming (CP) to obtain quality and robust solutions within an amount of time small enough to be useful to practitioners. The expanded feature set of …

Decision Support Models For A Few Critical Problems In Transportation System Design And Operations, Ran Zhang

USF Tampa Graduate Theses and Dissertations

Transportation system is one of the key functioning components of the modern society and plays an important role in the circulation of commodity and growth of economy. Transportation system is not only the major influencing factor of the efficiency of large-scale complex industrial logistics, but also closely related to everyone’s daily life. The goals of an ideal transportation system are focused on improving mobility, accessibility, safety, enhancing the coordination of different transportation modals and reducing the impact on the environment, all these activities require sophisticated design and plan that consider different factors, balance tradeoffs and maintaining efficiency. Hence, the design …

Scheduling Strategies For Construction Project Managers Toward On Time Delivery, Paul Shamp

Walden Dissertations and Doctoral Studies

Construction management projects involve complex, dynamic environments resulting in uncertainty and risk, compounded by demanding time constraints. Research indicated project managers have struggled to identify best practices for scheduling construction projects via critical path methodologies while searching for tools to increase timely job completions and budget profits. The purpose of this single case study was to explore the strategies that construction project managers used to manage scheduled construction project delivery on time. The constructivist philosophical worldview was used as the framework for this study. Data were collected from semistructured interviews from 7 project managers from 5 different construction companies selected …

Sortie Generation Simulation Of A Fighter Squadron, Abdurrahman Sevimli

Theses and Dissertations

The Turkish Air Force utilizes several fighter squadrons to enhance its military capabilities. One of the most critical challenges for these squadrons is generating sorties to meet the currency and demand during both peacetime and wartime. This sortie generation process directly affects the success of both training and operations. In this study, this process is assessed using a discrete event simulation. Air Force decision makers require a simulation tool to conduct “what-if” analysis on how potential changes in the environment affect an F-16 fighter squadron’s sortie generation process. Creating a usable simulation provides decision makers with a flexible tool to …

Increased Capacity Utilizing Aggregation And Consolidation Of Contingency Cargo, Cassidy L. Wilson

Theses and Dissertations

Maximizing use of limited airlift assets is a common problem during large contingency operations. Requirements often exceed airlift capacity and fiscal constraints driving the need to aggregate conveyance loads both within and across business lines (Unit Line Number (ULN), Special Assignment Airlift Mission (SAAM), and sustainment). Current methods of consolidation are completed by planners at the 618th Air Operations Center. This process is completed by piecing email correspondence and making individual localized decisions which are not always consistent with big picture efficiency. United States Transportation Command requested a study to create standard business rules or a methodology that can benefit …

Heuristic Solution For Separated Manufacturing Process, James Dee Davis

Masters Theses

Downtime is a major issue for manufactures. Downtime may occur from breakdowns, quality issues, lack of manpower, lack of materials, or in this case a lack of storage containers. A manufacturing system was studied that consists of an injection machine that supplies two assembly lines. The injection machine suffered from frequent downtime from lack of containers. The process was analyzed for root cause of downtime. After analysis of the system it was found that the injection process had high variability in production quantity and quality. The scheduling scheme called for production until all available containers were full regardless of actual …

Operational Planning In Combined Heat And Power Systems, Hariharan Gopalakrishnan

Doctoral Dissertations

This dissertation presents methodologies for operational planning in Combined Heat and Power (CHP) systems. The subject of experimentation is the University of Massachusetts CHP system, which is a 22 MWe/640 MBh system for a district energy application. Systems like this have complex energy flow networks due to multiple interconnected thermodynamic components like gas and steam turbines, boilers and heat recovery steam generators and also interconnection with centralized electric grids. In district energy applications, heat and power requirements vary over 24 hour periods (planning horizon) due to changing weather conditions, time-of-day factors and consumer requirements. System thermal performance is highly dependent …

Optimizing Boat Hull And Deck Mold Storage Scheduling With Linear Programming, Tron Bjorn Dareing

Masters Theses

With a wide range of products, Sea Ray uses a vast amount of large boat molds for each of the different boat models. Storing and transporting these molds can be an issue with introducing high variability in the production process. One of the largest problems deals with the utilization of the employees’ time with the large amount of boat production. Having the boat molds being ready for production is a critical part of the manufacturing of quality boats. There is non-value added time spent on preparing the molds for the lamination process and storing them in various areas. This problem …

Large-Scale Solution Approaches For Healthcare And Supply Chain Scheduling, Ridvan Gedik

Graduate Theses and Dissertations

This research proposes novel solution techniques for two real world problems. We first consider a patient scheduling problem in a proton therapy facility with deterministic patient arrivals. In order to assess the impacts of several operational constraints, we propose single and multi-criteria linear programming models. In addition, we ensure that the strategic patient mix restrictions predetermined by the decision makers are also enforced within the planning horizon. We study the mathematical structures of the single criteria model with strict patient mix restrictions and derive analytical equations for the optimal solutions under several operational restrictions. These efforts lead to a set …

A Set Union Based Formulation For Course Scheduling And Timetabling, Jesse Paul Bukenberger

Master's Theses

The Course Timetabling Problem is a widely studied optimization problem where a number of sections are scheduled in concert with the assignment of students to sections in order to maximize the desirability of the resulting schedule for all stakeholders. This problem is commonly solved as a linear program with variables for each student or group of students with identical schedules. In this paper we explore an alternative formulation that aggregates binary student variables into integer variables denoting the number of students enrolled in a course. Our solution method assumes decomposition of the general schedule into time blocks, and applies a …

Scheduling And Resource Allocation In Wireless Sensor Networks, Yosef Alayev

Dissertations, Theses, and Capstone Projects

In computer science and telecommunications, wireless sensor networks are an active research area. Each sensor in a wireless sensor network has some pre-defined or on demand tasks such as collecting or disseminating data. Network resources, such as broadcast channels, number of sensors, power, battery life, etc., are limited. Hence, a schedule is required to optimally allocate network resources so as to maximize some profit or minimize some cost. This thesis focuses on scheduling problems in the wireless sensor networks environment. In particular, we study three scheduling problems in the wireless sensor networks: broadcast scheduling, sensor scheduling for area monitoring, and …

Algorithmic And Mathematical Programming Approaches To Scheduling Problems With Energy-Based Objectives, Kan Fang

Open Access Dissertations

This dissertation studies scheduling as a means to address the increasing concerns related to energy consumption and electricity cost in manufacturing enterprises. Two classes of problems are considered in this dissertation: (i) minimizing the makespan in a permutation flow shop with peak power consumption constraints (the PFSPP problem for short) and (ii) minimizing the total electricity cost on a single machine under time-of-use tariffs (the SMSEC problem for short). We incorporate the technology of dynamic speed scaling and the variable pricing of electricity into these scheduling problems to improve energy efficiency in manufacturing.The challenge in the PFSPP problem is to …

Improved Photolithography Scheduling In Semiconductor Manufacturing, Sreenath Chalil Madathil

All Theses

Photolithography is typically the bottleneck process in semiconductor manufacturing. In this thesis, we present a model for optimizing photolithography job scheduling in the presence of both individual and cluster tools. The combination of individual and cluster tools that process various layers or stages of the semiconductor manufacturing process flow is a special type of flexible flowshop. We seek separately to minimize total weighted completion time and maximize on-time delivery performance. Experimental results suggest that our mathematical- and heuristic-based solution approaches show promise for real world implementation as they can help to improve resource utilization, reduce job completion times, and decrease …

An Optimization Model For Class Scheduling At A Dance Studio, Chirag Ojha

All Theses

Scheduling has been a large area of research for decades. A substantial amount of work has been done to express, classify, and solve scheduling problems. Most of these problems are computationally difficult to solve and require complex algorithms. In this thesis, we develop a mixed-integer linear program for a real world optimization problem at a dance studio. Similar to a university, the students in this studio request a particular class and instructors teach the classes under constrained resources such as a limited number of classrooms. The priorities of instructors as well as dancers are included to further mimic reality. Experimental …