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Spare Parts On Demand Using Additive Manufacturing : A Simulation Model For Cost Evaluation., Stefan Jedeck Dec 2015

Spare Parts On Demand Using Additive Manufacturing : A Simulation Model For Cost Evaluation., Stefan Jedeck

Electronic Theses and Dissertations

Little is known about the impact of additive manufacturing in the spare part supply chain. A few studies are available, but they focus on specific parts and their applications only. A general model, which can be adapted to different applications, is nonexistent. This dissertation proposes a decision making framework that enables an interested practitioner/manager to decide whether using additive manufacturing to make spare parts on demand is economical when compared to conventional warehousing strategy. The framework consists of two major components: a general discrete event simulation model and a process of designing a wide range of simulation scenarios. The goal …


Guidelines For Scheduling In Primary Care: An Empirically Driven Mathematical Programming Approach, Hyun Jung Alvarez Oh Aug 2015

Guidelines For Scheduling In Primary Care: An Empirically Driven Mathematical Programming Approach, Hyun Jung Alvarez Oh

Doctoral Dissertations

Primary care practices play a vital role in healthcare delivery since they are the first point of contact for most patients, and provide health prevention, counseling, education, diagnosis and treatment. Practices, however, face a complex appointment scheduling problem because of the variety of patient conditions, the mix of appointment types, the uncertain service times with providers and non-provider staff (nurses/medical assistants), and no-show rates which all compound into a highly variable and unpredictable flow of patients. The end result is an imbalance between provider idle time and patient waiting time. To understand the realities of the scheduling problem we analyze …


Toward A Theory Of Multi-Method Modeling And Simulation Approach, Mariusz A. Balaban Apr 2015

Toward A Theory Of Multi-Method Modeling And Simulation Approach, Mariusz A. Balaban

Computational Modeling & Simulation Engineering Theses & Dissertations

The representation via simulation models can easily lead to simulation models too simple for their intended purpose, or with too much detail, making them hard to understand. This problem is related to limitations of the modeling and simulation methods. A multi-method Modeling and Simulation (M&S) approach has the potential for improved representation by taking advantage of methods' strengths and mitigating their weaknesses. Despite a high appeal for using multiple M&S methods, several related problems should be addressed first. The current level of theoretical, methodological, and pragmatic knowledge related to a multi-method M&S approach is limited. It is problematic that there …


Experimental And Numerical Study Of High-Speed Friction Stir Spot Welding Of Advanced High-Strength Steel, Utsab Karki Mar 2015

Experimental And Numerical Study Of High-Speed Friction Stir Spot Welding Of Advanced High-Strength Steel, Utsab Karki

Theses and Dissertations

With the desire to lighten the frame while keeping or increasing the strength, Advanced High-Strength Steels (AHSS) have been developed for use in the automotive industry. AHSS meet many vehicle functional requirements because of their excellent strength and acceptable ductility. But joining AHSS is a challenge, because weldability is lower than that of mild steels. Friction stir spot welding (FSSW) is a solid state joining process that can provide a solution to the weldability issues in AHSS, but FSSW has not been studied in great detail for this application. In this work, Si3N4 tools were used for FSSW experiments on …


The Programmatic Generation Of Discrete-Event Simulation Models From Production Tracking Data, Christopher Rand Smith Mar 2015

The Programmatic Generation Of Discrete-Event Simulation Models From Production Tracking Data, Christopher Rand Smith

Theses and Dissertations

Discrete-event simulation can be a useful tool in analyzing complex system dynamics in various industries. However, it is difficult for entry-level users of discrete-event simulation software to both collect the appropriate data to create a model and to actually generate the base-case simulation model. These difficulties decrease the usefulness of simulation software and limit its application in areas in which it could be potentially useful. This research proposes and evaluates a data collection and analysis methodology that would allow for the programmatic generation of simulation models using production tracking data. It uses data collected from a GPS device that follows …


Compressibility Measurement And Modeling To Optimize Flow Simulation Of Vacuum Infusion Processing For Composite Materials, Paul Hannibal Feb 2015

Compressibility Measurement And Modeling To Optimize Flow Simulation Of Vacuum Infusion Processing For Composite Materials, Paul Hannibal

Theses and Dissertations

Out-of-autoclave manufacturing processes for composite materials are increasing in importance for aerospace and automotive industries. Vacuum Infusion processes are leading the push to move out of the autoclave. An understanding of the various process parameters associated with resin infusion is necessary to produce quality product. Variance in compaction, resin, and vacuum pressures are studied, concentrating on developing a compaction pressure profile as it relates to fiber volume fraction. The purpose of this research is twofold: (1) to show and quantify the existence of a resin pressure gradient in compression testing using rigid tooling, and (2) to use measured test data …


A Framework For Safety Training Using Virtual Reality Software, Rana Riad Jan 2015

A Framework For Safety Training Using Virtual Reality Software, Rana Riad

Electronic Theses and Dissertations

Safety training is a vital component to the well-being of individuals in all industries. With technology advancing at the current pace, conventional training methods are no longer the most effective way to communicate information. There is a strong need for safety training that incorporates new methods and forms of communication to obtain higher levels of comprehension. Virtual reality systems offer a highly customizable and interactive form of delivering information to users. This research addresses major gaps in the field of safety training using virtual reality systems and provides a design framework for creating a virtual safety-training system. A model for …


Using The Delta-Model For End-Stage Liver Disease To Improve The Decision-Making Process For The Donor Liver System, Joanne Chin Jan 2015

Using The Delta-Model For End-Stage Liver Disease To Improve The Decision-Making Process For The Donor Liver System, Joanne Chin

Walden Dissertations and Doctoral Studies

The purpose of this experimental research was to determine whether using delta-MELD as a criterion for the liver transplant patient selection process could improve the U.S. liver allocation system. This research closed a gap in current literature on the utility of delta-MELD for liver transplant patient selection. The frameworks of systems theory, the analytic hierarchy process, and the Kalman filter contributed to the development of 2 simulation models of the liver allocation system: one that used delta-MELD and one that did not use delta-MELD. The research question examined whether using delta-MELD could improve the liver allocation system by reducing the …