Mechanical Engineering Commons^™

Simulation Of Wave Propagation In Granular Particles Using A Discrete Element Model, Syed Tahmid Hussan

Electronic Theses and Dissertations

The understanding of Bender Element mechanism and utilization of Particle Flow Code (PFC) to simulate the seismic wave behavior is important to test the dynamic behavior of soil particles. Both discrete and finite element methods can be used to simulate wave behavior. However, Discrete Element Method (DEM) is mostly suitable, as the micro scaled soil particle cannot be fully considered as continuous specimen like a piece of rod or aluminum. Recently DEM has been widely used to study mechanical properties of soils at particle level considering the particles as balls. This study represents a comparative analysis of Voigt and Best …

Heat Pump Integrated Thermal Storage For Building Demand Response And Decarbonization, Sara Sultan

Doctoral Dissertations

This work presents a novel thermal energy storage (TES) integrated with existing residential heat pump (HP). The research focuses on controls and configuration for energy, demand, cost and carbon emissions savings for residential buildings’ energy consumption. This work will be significant in developing a framework especially for reduced energy demand and carbon emissions associated with space heating and cooling in residential buildings. Since buildings account for about 40% primary energy consumption in U.S. and half of that is associated with HP.

An existing air source HP in integrated with a phase change material (PCM) based TES via active configuration where …

Characterization Of Mechanically Recycled Polylactic Acid (Pla) Filament For 3d-Printing By Evaluating Mechanical, Thermal, And Chemical Properties And Process Performance, Mahsa Shabani Samghabady

All Theses

Polylactic acid (PLA) is a biopolymer made from renewable resources such as sugar and corn. PLA filament is a popular material used in Fused Deposition Modeling (FDM) 3D-printing. While this material has many advantages, all the failed parts, support structures, rafts, nozzle tests, and the many prototype iterations during the 3D-printing process contribute to the plastic pollution and release of greenhouse gases. Although PLA is biodegradable, it can take years to degrade in landfills. Instead of throwing away PLA waste and buying new filaments, PLA can be recycled. Amongst the different recycling technologies, mechanical recycling is the most environmentally friendly. …

Developing And Testing Low-Cost Air Cleaners For Safer Spaces During Wildfires, Brett William Stinson

Dissertations and Theses

Air cleaning reduces indoor exposure to fine particulate matter (PM_2.5) during wildfire events. However, resource and cost restraints may limit access to air cleaning during such an event, as both commercial devices and the high-rated MERV filters that homemade assemblies typically rely upon tend to be expensive and in short supply. With these barriers in mind, we sought to develop and evaluate the potential for air cleaners that use common household fabrics as filtration media. Evaluated designs use a box fan to move air across fabric filters; box fans are inexpensive and readily available to many households. Ultimately, …

Fungi In Flux | Designing Regenerative Materials And Products With Mycelium, Arvind Bhallamudi

Masters Theses

As the world grapples with the escalating crisis of climate threats and environmental degradation, this research delves into the synergistic potential of design and biology, developing safe and sustainable materials for applications in prototyping, furniture and interior design. Harnessing the power of a unique organism - fungi, the study proposes an accessible, efficient, and resilient material resource system. It utilizes local waste streams and mycelium (the vegetative part of fungi) to grow functional structures. An experimental and small-scale protocol is modeled by testing bio-fabrication and bio-printing methods. The composites' performance qualities and characteristics are evaluated through mechanical testing and a …

Rattus Norvegicus As A Biological Detector Of Clandestine Remains And The Use Of Ultrasonic Vocalizations As A Locating Mechanism, Gabrielle M. Johnston

Master's Theses

In investigations, locating missing persons and clandestine remains are imperative. One way that first responder and police agencies can search for the remains is by using cadaver dogs as biological detectors. Cadaver dogs are typically used due to their olfactory sensitivity and ability to detect low concentrations of volatile organic compounds produced by biological remains. Cadaver dogs are typically chosen for their stamina, agility, and olfactory sensitivity. However, what is not taken into account often is the size of the animal and the expense of maintaining and training the animal. Cadaver dogs are typically large breeds that cannot fit in …

Trace Dna Detection Using Diamond Dye: A Recovery Technique To Yield More Dna, Leah Davis

Master's Theses

This study aspires to find a new screening approach to trace DNA recovery techniques to yield a higher quantity of trace DNA from larger items of evidence. It takes the path of visualizing trace DNA on items of evidence with potential DNA so analysts can swab a more localized area rather than attempting to recover trace DNA through the general swabbing technique currently used for trace DNA recovery. The first and second parts consisted of observing trace DNA interaction with Diamond Dye on porous and non-porous surfaces.

The third part involved applying the Diamond Dye solution by spraying it onto …

A One-Dimensional Analysis Of A Microbial Fuel Cell For Efficient Acetate Removal And Power Density Output, David Rouhani

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microbial fuel cells (MFCs) are electrochemical devices that utilize microorganisms to convert organic matter into electrical energy. MFCs have been discussed to have potential application for sustainable wastewater treatment due to their ability to generate electricity while simultaneously treating contaminated water. To optimize MFC performance, numerical models can be used to understand the complex electrochemical and biological processes occurring in the system. In this study, a numerical model was developed to simulate the performance of MFCs under varying operating conditions and to investigate the performance of a MFC for treating wastewater fuel. More specifically, the MFC was modeled to oxidize …

Metastability And Degradation In Cu(In,Ga)Se2 Thin-Film Solar Cells, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cu(In,Ga)(S,Se)2 or CIGS is a thin-film semiconductor that has shown a device efficiency of 23.35% and 24.2% for single-junction and perovskite/CIGS tandem solar cells, respectively. CIGS offers promising properties such as tunable bandgap and ease of processing making them great candidates for thin-film tandem devices. However, knowledge of the effect of material defects, buffer materials, and post-deposition treatment (PDT) on degradation and metastability behavior in these devices is not well understood.In this dissertation, metastability and long-term degradation of CIGS thin-film solar cells have been investigated under combinatorial stress factors of heat, light, and voltage bias to systematically understand the effect …

Fabrication Of Solid Oxide Fuel Cell Components Using Stereolithography 3d Printing, Hannah Dyer

Mechanical & Aerospace Engineering Theses & Dissertations

Transitioning from fossil fuel supplied energy to renewable technology must meet cost efficient parameters throughout the manufacturing process while possessing the characteristics of a functioning and reliable power source. With a significant demand in renewable energy products, developmental techniques require adaptive approaches and procedures for novel materials in the manufacturing phase. This report proposes how a solid oxide fuel cell (SOFC), a renewable energy system, can employ additive manufacturing for directly 3D printing its components by utilizing stereolithography (SLA) 3D printing techniques. Fabrication of the printed components from the mixtures were first mixed with varying concentrations of ceramic powder and …

The Qualification Of Sealability And Creep Relaxation Of Additively Manufactured Zytel Gaskets For Pem Fuel Cells, Robert Lazarin

Open Access Theses & Dissertations

The purpose of this thesis is to study the feasibility of low-cost additive manufacturing of gaskets for proton exchange membrane fuel cells exposed to extreme temperature conditions ranging from -55°C to 100°C. With the growing popularity and decreasing costs of additive manufacturing technologies, specifically Material Extrusion (ME), research is being conducted to determine the feasibility of ME components. Thermally cycled PEMFCs may exhibit accelerated gasket deterioration, therefore, the mechanical stability of material extruded gaskets following a harsh thermal cycle must be assessed. The feasibility of the material extruded gaskets will be proven by manufacturing optimization and mechanical testing. The target …

Fabrication And Characterization Of Iron-Based Catalysts For The Dehydrogenation Of Fossil Fuels, Victoria Isabel Reyes

Open Access Theses & Dissertations

For a prosperous and sustainable future, hydrogen is an encouraging solution due to its simple transition for industrial decarbonization and synergy for economic development. Paradoxically, current hydrogen production pathways release substantial amount of greenhouse gases into the atmosphere contributing to climate change. To keep up with increasing demand, hydrogen could be produced through microwave-assisted thermocatalytic dehydrogenation of fossil fuels without emitting carbon dioxide. This requires specified catalysts to meet the requirements of hydrogen yield and selectivity. The objective of the present research is to fabricate, characterize, and compare iron-based alumina (FeAl_x O_y) catalysts produced via solution combustion synthesis and iron-based …

Characterization Of A Flex-Fuel Oxy-Combustion System Through Experimental Investigation And Computational Modeling, Md Mohieminul I. Khan

Open Access Theses & Dissertations

Oxy-fuel combustion has the potential to offer high thermal efficiency and lower pollutants emission compared to other existing combustion technologies. More than 63% of the worldâ??s electricity is produced by fossil fuel combustion which also is the major reason for greenhouse gas emissions. Oxy combustion offers a solution to it. Oxy combustion uses pure oxygen as an oxidizer instead of air which eliminates the NOx and SOx products from the exhaust. In oxy-combustion flue gas mainly consists of CO2 and water vapor. Furthermore, combustion in presence of pure oxygen results in higher flame temperature and hence promises higher thermal efficiency. …

Developing A Miniature Smart Boat For Marine Research, Michael Isaac Eirinberg

Computer Engineering

This project examines the development of a smart boat which could serve as a possible marine research apparatus. The smart boat consists of a miniature vessel containing a low-cost microcontroller to live stream a camera feed, GPS telemetry, and compass data through its own WiFi access point. The smart boat also has the potential for autonomous navigation. My project captivated the interest of several members of California Polytechnic State University, San Luis Obispo’s (Cal Poly SLO) Marine Science Department faculty, who proposed a variety of fascinating and valuable smart boat applications.

Solid Thermal Storage As An Energy Storage Device In Insulated Solar Electric Cookers: Thermal Modeling And Experiment, Michael Antonio Fernandez

Physics

The use of solid thermal storage (STS) as an energy storage device in insulated solar electric cookers (ISEC) was explored using a thermal simulation before retrofitting an existing cooker without energy storage and testing it under several conditions. STS sizing, material selection, and geometry were examined from both theoretical and practical perspectives and re-examined following experimental results. Characterization of the system’s thermal interfaces and methods to improve their thermal conductivities were investigated resulting in several performance enhancements to the system.

Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander

Open Access Theses & Dissertations

The purpose of this dissertation is to study the feasibility of low-cost additive manufacturing to fabricate polymer electrolyte fuel cell bipolar plate materials. Traditional manufacturing techniques include molding, milling, hollow embossing, hydro-forming, rolling, and electromagnetic forming. These processes are employed when a design has been selected due to higher costs at low volumes. The combination of high initial costs and bipolar plates being the most expensive component of the polymer electrolyte fuel cell creates incentive to mitigate this obstacle. The feasibility of low-cost additive manufactured bipolar plates will be proven by fabrication, post-processing, and characterization of printed test specimen. The …

Investigation Of A Simultaneaous Direct And Indirect Contact Dehumidifier Using Parallel Strings For Hdh Desalination, Josue Perez Perez

Theses and Dissertations

Freshwater is a limited and precious resource. Currently, half a billion people in the world face sever water scarcity all year round. Humidification dehumidification (HDH) systems have received special attention among the variety of small-scale desalination technologies due to its potential to create affordable and sustainable seawater desalination, especially when combined with natural power sources such as waves, wind, and solar rays. Improvements in the development of HDH desalination systems have been achieved in recent years. Nonetheless, the improvements that have received most attention focus on solar heaters and humidifiers. Dehumidification systems have often been adapted from air conditioning condensation …

Analysis Of Bio-Alcohols With Mie-Scattering And Ltc For Lowered Emissions In Pcci, Cesar E. Carapia

Electronic Theses and Dissertations

An investigation was conducted on the optimal engine parameters for facilitating lower NOX and soot emissions of PCCI combustion with either ethanol or n-butanol. The PFI fuels selected were tested at loads of 3, 4, and 5 Bar IMEP for a total of 28 total combustion tests with variations made to the EGR% and boost pressure for each test in order to find the optimal emissions strategy. A Mie-scattering spray fuel analysis was also conducted on the three fuels to gain insight on their influence on combustion/emissions characteristics. It was found that ethanol had a greater average Sauter Mean Diameter …

Constraint-Aware And Efficiency-Aware Control Of Air-Path In Fuel Cell Vehicles, Eli Bacher-Chong

Graduate College Dissertations and Theses

Fuel cell technology offers the potential for clean, efficient, robust energy productionfor both stationary and mobile applications. But without fast and robust control systems, fuel cells cannot hope to maintain real-life efficiencies near enough to their theoretical potential. This work studies control and constraint management techniques to regulate a nonlinear multivariable air-path system for a proton exchange membrane fuel cell (PEMFC). The control objectives are to avoid oxygen starvation, run at the maximum net efficiency, achieve fast tracking of air flow and pressure set-points, and be easy to calibrate. To operate at maximum efficiency, a set-point map is generated for …

Supercritical Co2 Recompression Closed Brayton Cycle Analysis, Andres Eduardo Gutierrez Hernandez

Open Access Theses & Dissertations

On this research, the results of an analysis made of a Supercritical Carbon Dioxide (sCO2) Recuperated Closed Brayton Cycle (RCBC) done by performing theorical calculations and comparing it to the results obtained with the use of the software ASPEN Plus will be presented. To demonstrate and determine that this software is a useful tool for modeling the proposed type of cycle, a preliminary comparison was made to verify with previous studies found in literature. A comparison and analysis between the possible working fluids and thermal energy sources was also performed to emphasize the decision of using CO2 as the cycle …

Identification Of Phosphorous Loading Point Source Facilities To 303(D) Listed Nutrient Impaired Waters Through Watershed Delineation Using Arcgis For Life Cycle Assessment Applications, John Zimmerman

Chemical Engineering Undergraduate Honors Theses

The work done for this project is part of a larger “life cycle assessment (LCA) of novel electrochemical phosphorus recovery technology at the wastewater treatment plant and U.S. watershed scales” (Morrissey 2019). The goal of that LCA is to determine “environmental impacts of implementing electrochemical struvite recovery at the wastewater treatment plant, U.S watershed, and global scales” (Morrissey 2019). This project’s goal is to identify locations deemed more sensitive to eutrophication impacts. The results will be used as part of the life cycle inventory (LCI) accounting for geographically explicit phosphorus flows. The waters identified as impaired were sourced from the …

Modeling The Ambient Conditions Of A Manufacturing Environment Using Computational Fluid Dynamics (Cfd), Yang Liu

USF Tampa Graduate Theses and Dissertations

As manufacturing equipment evolve to higher speed and require high precision operations, the impact of environmental changes on machine accuracy becomes critical. Due to thermal expansion, the structure of the machine can change when ambient temperature varies. When the airflow in the laboratory changes, this also alters the operator's thermal comfort. Either the change in machine structure or operator comfort can ultimately affect machine accuracy. The manufacturing industry is currently using heating, ventilation, and air-conditioning (HVAC) systems to regulate the temperature of the working environment. However, since conventional HVAC systems determine whether to activate the HVAC system by collecting the …

Economic Feasibility Of Mixed Plastic Waste Pyrolysis Using Twin Reactor System In Northwest Arkansas, Carol Rogers, Patricia Means, Renato Gonzalez, Kaida Sheets, Hayden Townsend

Chemical Engineering Undergraduate Honors Theses

Plastic waste generation is increasing at an unsustainable rate while recycling solutions remain stagnant. As a chemical means of recycling, mixed plastic waste pyrolysis can generate synthetic oil appropriate for use as fuel in power generation from plastic waste that otherwise accumulates in landfills. With the scaling of a commercial plastic pyrolysis process in Northwest Arkansas (NWA) modeled after an operational sawdust pyrolysis unit in Huntsville, Arkansas, economic analysis resulted in 26.3% internal rate of return. Therefore, construction of a commercial mixed plastic-to-fuel pyrolysis plant is economically justified and should be pursued. To effectively implement the proposed design, NWA must …

Sensible/Latent Hybrid Thermal Energy Storage For The Supercritical Carbon Dioxide Brayton Cycle, Kelly Osterman

USF Tampa Graduate Theses and Dissertations

Mitigating the effects of climate change will require rapid deployment of a carbon-free electricity system that includes all available forms of zero-carbon energy. Both renewables and nuclear show great promise, but both come with drawbacks. Power production from wind and solar is limited to times when their respective resources are available, while nuclear is limited in its ability to adjust its output according to the ever-varying demand for electricity. Additionally, the systems must be affordable. One way to reduce the cost of thermal power plants (concentrated solar power and nuclear) is to use new power cycles, such as the supercritical …

On The Improvements Of Boundary-Layer Representation For High Resolution Weather Forecasting In Costal-Urban Environments, David Melecio-Vazquez

Dissertations and Theses

As large urban centers around the world become more densely populated, the global conversion from natural to man-made land surfaces will only increase. These land-use changes affect the urban surface energy budget which in turn changes the structure of the planetary boundary layer (PBL) above. With current high-performance computing systems, meteorological and built environment information can be better utilized to quantify the anthropogenic effects of these modifications. Although these systems have improved forecasting near-surface weather conditions, a comprehensive approach to represent urban impacts on the PBL is still limited. Improved PBL representation can lead to better weather and climate forecasts, …

Investigation Of A Machine-Plant Interface For Extracting Rooted Invasive Aquatic Plants, Brad Baas

Dissertations, Master's Theses and Master's Reports

The current solutions for managing rooted aquatic invasive plants are time consuming, have negative environmental impacts, or are cost-limiting for management organizations. The most effective treatment method is hand pulling, but hand pulling is not a feasible solution for a whole lake. A new device, the invasive aquatic plant extractor, aims to replace human divers who hand pull plants with a mechanical system. The device implements a machine-plant interface that resembles the tines of a fork. These tines will be pushed linearly through the substrate, and then raised from the substrate with the plant caught in the tines. The primary …

Sustainability Assessment Of Direct Energy Deposition (Ded) Based Hybrid Manufacturing Using Life Cycle Assessment (Lca) Method, Faujia Islam

Graduate Theses, Dissertations, and Problem Reports

As sustainability has emerged as a highlight for almost every field over the last few decades, the manufacturing field is no exception. Generally, additive manufacturing performs better than traditional manufacturing in terms of sustainability because of its lean energy- and material usage. Previous studies have compared the sustainability performance between traditional and additive manufacturing, but hybrid manufacturing was not focused upon much. In this paper, the life cycle assessment method is used to analyze and compare the energy consumption and environmental impact of direct energy deposition (DED) based hybrid manufacturing and traditional manufacturing “CNC milling” process for a turbine blade. …

Numerical And Experimental Investigation Of Aeration Self Mixing By Using Pulsating And Continuous Air Flow, Ahmed Ali Alkhafaji

Theses and Dissertations

Wastewater treatment is considered one of the most common forms of pollution control in the united states. Considered as an integral part of the wastewater treatment, the aeration process is the most energy-consuming process among all the processes that take place in any wastewater treatment plant. According to the United States Environmental Protection Agency (EPA), a wastewater treatment plant is expected to remove at least 85% of the suspended solids and dissolved organic compounds from the wastewater before discharging it to a river or a lake. The normal operation of the aeration process is by compressing air continuously to basin …

Indoor Air Quality Impacts Of A Woodstove Exchange Program In Washington County, Oregon, Matthew Forrest Survilo

Dissertations and Theses

More than six million people in the United States use wood stoves as their primary heat source. Wood stoves emit air pollutants that may impact health, e.g., wood combustion products are associated with premature death and aggravation of pulmonary and cardiovascular conditions. There are few studies investigating the efficacy of wood stove exchange programs (WSEPs) as a method to improve indoor air quality (IAQ). In partnership with Washington County Department of Health and Human Services we conducted an air quality study to measure the impact of a WSEP on indoor and neighborhood levels of wood combustion products. Twenty households engaged …

Feasibility Study On Environmental Protection Reform Of Ship Stern Tube System Based On Water Lubrication, Yang Cui

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.