Mechanical Engineering Commons^™

Modeling Portfolios Of Low Carbon Energy Generation Under Deep Uncertainty, Franklyn Kanyako

Doctoral Dissertations

In the 2015 Paris Agreement, nearly every country pledge through the Nationally Determined Contributions (NDCs) increased adoption of low carbon energy technologies in their energy system. However, allocating investments to different low carbon energy technologies under rising demand for energy and budget constraints, uncertain technical change in these technologies involves maneuvering significant uncertainties among experts, models, and decision-makers. We examine the interactions of low carbon energy sources (LCES) under the condition of deep uncertainty. Deep uncertainty directly impacts the understanding of the role of low carbon energy technologies in climate change mitigation and how much R&D investment should be allocated …

Robust And Sustainable Energy Pathways To Reach Mexico’S Climate Goals, Rodrigo Mercado Fernandez

Doctoral Dissertations

As countries set climate change goals for adaptation and mitigation efforts, there are many questions regarding to how to reach these targets. These efforts will necessitate the transition of our electricity infrastructure from relying on conventional electricity generation technologies including natural gas, coal and oil, to clean energy generation with renewables. Through the three essays presented in this dissertation, we explore various pathways of development for the electricity system to reach long term climate change goals. We are interested in identifying: Is there a unique optimal development option or are there various? How do different mixes of electricity generation technologies …

Three Essays On Data-Driven Optimization For Scheduling In Manufacturing And Healthcare, Ekin Koker

Doctoral Dissertations

This dissertation consists of three essays on data-driven optimization for scheduling in manufacturing and healthcare. In Chapter 1, we briefly introduce the optimization problems tackled in these essays. The first of these essays deals with machine scheduling problems. In Chapter 2, we compare the effectiveness of direct positional variables against relative positional variables computationally in a variety of machine scheduling problems and we present our results. The second essay deals with a scheduling problem in healthcare: the team primary care practice. In Chapter 3, we build upon the two-stage stochastic integer programming model introduced by Alvarez Oh (2015) to solve …

Freeform Extrusion Fabrication Of Advanced Ceramics And Ceramic-Based Composites, Wenbin Li

Doctoral Dissertations

"Ceramic On-Demand Extrusion (CODE) is a recently developed freeform extrusion fabrication process for producing dense ceramic components from single and multiple constituents. In this process, aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle to print each layer sequentially. Once one layer is printed, it is surrounded by oil to prevent undesirable water evaporation from the perimeters of the part. The oil level is regulated just below the topmost layer of the part being fabricated. Infrared radiation is then applied to uniformly and partially dry the top layer so that the yield stress of the paste increases to avoid part deformation. By repeating the above steps, the part is printed in a layer-wise fashion, followed by post-processing. Paste extrusion precision of different extrusion mechanisms was compared and analyzed, with an auger extruder determined to be the most suitable paste extruder for the CODE system. A novel fabrication system was developed based on a motion gantry, auger extruders, and peripheral devices. Sample specimens were then produced from 3 mol% yttria stabilized zirconia using this fabrication system, and their properties, including density, flexural strength, Young's modulus, Weibull modulus, fracture toughness, and hardness were measured. The results indicated that superior mechanical properties were achieved by the CODE process among all the additive manufacturing processes. Further development was made on the CODE process to fabricate ceramic components that have external/internal features such as overhangs by using fugitive support material. Finally, ceramic composites with functionally graded materials (FGMs) were fabricated by the CODE process using a dynamic mixing device"--Abstract, page iv.

Graphical Display And Data Structure For Virtual Prototyping, David William Manry

Doctoral Dissertations

One of the goals of engineering firms is to bring better products to market faster. Although concurrent engineering can aid in this endeavor, it requires that all areas of an organization work simultaneously. Thus, current product data must be accessible to everyone.

Virtual prototyping allows this simultaneous exchange of information. Virtual prototyping not only replaces the physical model in product development with a virtual model, but also it goes further by allowing data associated with each part of the model to be accessed. This data is not limited to just geometric properties but could contain other quantifiable properties, such as …

Development And Realization Of A Single-Mode Optical Fiber Ferrule Mold Insert With Twelve Channels, Hsiharng William Yang

Doctoral Dissertations

A manufacturing process for an optical fiber ferrule mold insert with twelve channels has been established. This research project presents mask design, mask fabrication, deep X-ray lithography exposure, resist developing, nickel electroforming, as well as surface finishing to attain the final result. Deep X-ray mask fabrication methods are explored, including mechanically machined masks, micro-EDM masks, and E-beam written masks. The exposures to pattern resists and electroforming to fabricate nickel molds up to 500 $\mu$m thickness are reported in this study. Nickel structures for the optical fiber ferrule insert with twelve channels made by electroforming are the final products. A practical …