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Articles 4441 - 4470 of 16704

Full-Text Articles in Engineering

Uio-Type Metal-Organic Framework Derivatives As Sorbents For The Detection Of Gas-Phase Explosives, Matthew Ryan Sherrill Jan 2022

Uio-Type Metal-Organic Framework Derivatives As Sorbents For The Detection Of Gas-Phase Explosives, Matthew Ryan Sherrill

Legacy Theses & Dissertations (2009 - 2024)

The detection of energetic compounds – better known to the public as explosives – has is an important cornerstone of counterterrorism and homeland security . While significant advances have been achieved for the detection of trace explosives in various matrices such as soil, wastewater, and clothing, the detection of explosives in the gas phase remains challenging due to their infamously low vapor pressures. In this thesis, we leverage the high sensitivity of direct analysis in real-time mass spectrometry (DART-MS) and the microporosity of metal-organic frameworks (MOFs) to adsorb and therefore concentrate explosives from the vapor phase and subsequently detect them …

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Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian Jan 2022

Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian

Dissertations, Master's Theses and Master's Reports

Composite materials require a multi-scale approach to fully understand its behavior. At the micro level, material behavior analysis is conducted most often using numerical or analytical approaches. These models, however, require validation from experimental data to ensure material predictions are accurate. This study compares a semi-analytical micromechanical analysis tool, MAC/GMC, to experimental results of in-situ microscale transverse compression testing conducted at AFRL facilities. Effective properties, stress-strain curves, stress and strain fields, and damage predictions are compared with experimental outputs. Both generalized method of cells (GMC) and high-fidelity generalized method of cells (HFGMC) theories implemented within MAC/GMC show results that agree …

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Cold-Formed Steel Strength Predictions For Torsion, Yu Xia, Robert S. Glauz, Benjamin W. Schafer, Michael Seek, Hannah B. Blum Jan 2022

Cold-Formed Steel Strength Predictions For Torsion, Yu Xia, Robert S. Glauz, Benjamin W. Schafer, Michael Seek, Hannah B. Blum

Engineering Technology Faculty Publications

Locally slender open cross-section members are susceptible to significant twisting and high warping torsion stresses. Torsion considerations are complicated by whether it is derived as a first-order effect from loading or a second-order effect from instability. Previous direct torsion experiments on lipped channels have shown significant inelastic reserve in limited cases. The current design for combined bending and torsion interaction has some limitations, including only considering the first yield in torsion and ignoring the cross-section slenderness in torsion. A parametric study is conducted to predict the torsion capacity in locally slender cross-sections. Shell finite element models of lipped Cee and …

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Exploring The Effects Of Chip Flexibility On The Behavior Of Standing Seam Diaphragms To Brace Cold Formed Steel Purlins, Michael W. Seek Jan 2022

Exploring The Effects Of Chip Flexibility On The Behavior Of Standing Seam Diaphragms To Brace Cold Formed Steel Purlins, Michael W. Seek

Engineering Technology Faculty Publications

Cold-formed steel C- and Z-shaped purlins in standing seam roof systems rely on the diaphragm action provided by the panels to restrain lateral movements and thus increase the load carrying capacity the purlins. The clip connection between the purlin and the panel has inherent and sometimes intentional flexibility designed to accommodate thermal deformations. The lateral deformation behavior of standing seam systems supported by Zees is highly nonlinear and this behavior is not well understood. The flexibility has major implications on the transfer of diaphragm forces throughout these systems and simplified models often grossly overpredict the demands on the diaphragm and …

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A Study Of Reduced Activation Ferritic Martensitic Metal Core Wire For Wire Arc Additive Manufacturing, Alexander L. Reichenbach Jan 2022

A Study Of Reduced Activation Ferritic Martensitic Metal Core Wire For Wire Arc Additive Manufacturing, Alexander L. Reichenbach

College of Graduate Studies: Theses & Dissertations

This study seeks to determine the technical feasibility of fabricating reduced activation ferritic martensitic (RAFM) steel parts, using a wire arc additive manufacturing (WAAM) process. The WAAM process, manufactures a part by depositing layers of metal onto a substrate to build a large scale near net shape part. RAFM alloy steels are next generation steels designed to resist radiation effects in the radiation intense working environments, such as nuclear reactors. To achieve this, process development and testing to design the WAAM production process with the custom RAFM filler wire was carried out. Several welding waveform modes were tested, and it …

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Scale Formation, Properties And De-Scaling In Steelmaking, Richard Osei Jan 2022

Scale Formation, Properties And De-Scaling In Steelmaking, Richard Osei

Doctoral Dissertations

During continuous castings, reheating, and hot rolling, slab surfaces are exposed to atmospheres containing oxidizing gases which results in scale formation. Inefficient removal of the formed scale during reheating affects product surface quality. The effect of steel composition and operating parameters on scale formation and scale removal efficiencies were investigated. Experimental investigations were carried out using a thermogravimetric (TGA) apparatus designed to replicate the combustion gas atmosphere and temperature in actual industrial slab reheat furnaces. Report on oxidation kinetics, scale structure and properties, and descaling were conducted on laboratory cast and industrial samples. Different characterization techniques were used to analyze …

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Zinc Plating From Alkaline Non-Cyanide Bath, Abdul J. Mohammed Jan 2022

Zinc Plating From Alkaline Non-Cyanide Bath, Abdul J. Mohammed

Masters Theses

“Alkaline non-cyanide zinc plating baths are preferred when trying to avoid the toxicity of cyanide baths or corrosivity of acid baths. Without additives, alkaline zincate baths produce powdery non-adherent deposits which have no use in commercial plating. Additives must be added at optimum concentrations to produce adherent, bright and uniform zinc deposits. In this study electrochemical tests were used to determine effects of additives on cathodic polarization, throwing power and morphology of deposits. Current density distribution in a unique bath of 37.5 g L-1 Zn and 210 g L-1 NaOH was modelled using COMSOL and validated two plating …

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Controlling Microalloy Interactions On Precipitation, Hot Ductility, And Microstructure -- Mechanical Property Relationships, Madhuri Varadarajan Jan 2022

Controlling Microalloy Interactions On Precipitation, Hot Ductility, And Microstructure -- Mechanical Property Relationships, Madhuri Varadarajan

Masters Theses

“One of the main problems faced in the continuous casting of micro-alloy steels is the formation of transverse cracks. Transverse cracks are surface, or near-surface cracks formed perpendicular to the casting direction. The research focuses on using laboratory hot tensile tests methods to determine the low ductility ranges in high strength steel grades with different micro-alloy additions of titanium, niobium, and vanadium. The hot ductility of commercially produced as-cast slab and beam blank samples was evaluated using two experimental methods: tensile testing utilizing a servo-hydraulic load frame with a resistance furnace and thermomechanical testing using rapid Joule heating. The tests …

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Controlling The Thermal And Electrical Properties Of Camno3-Δ Based Perovskite Ceramics, Sergio Andres Paredes Navia Jan 2022

Controlling The Thermal And Electrical Properties Of Camno3-Δ Based Perovskite Ceramics, Sergio Andres Paredes Navia

Graduate Theses, Dissertations, and Problem Reports (ETD)

Most of the energy lost during the conversion process comes in the form of waste heat. The world's energy consumption loses over 60% of its energy after conversion. In order to increase the efficiency of the conversion process, it is essential to harness waste heat and reutilize this energy resource. Heat recovery technology as thermoelectric (TE) technology is one of the growing alternatives to harvest excessive amounts of energy lost as waste heat for a more efficient, safe, and sustainable future. Due to the Seebeck effect, TE materials have the potential to convert waste heat directly into electricity, improving efficiency …

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Combinatorial Approaches For Effective Design, Synthesis, And Optimization Of Enzyme-Based Conjugates, Jordan Scott Chapman Jan 2022

Combinatorial Approaches For Effective Design, Synthesis, And Optimization Of Enzyme-Based Conjugates, Jordan Scott Chapman

Graduate Theses, Dissertations, and Problem Reports (ETD)

The specificity and efficiency with which enzymes catalyze selective chemical reactions far exceeds the performance of traditional heterogeneous catalysts that are predominant in industrial applications such as conversion of commodity chemicals to value-added products, fuel cells, and petroleum refinement. Moreover, biocatalysts exhibit exceptionally high product turnover at ambient conditions with little health and environmental burden. These advantageous qualities have led to the prolific use of enzyme catalysis in pharmaceutical, detergents, and food preservation industries wherein their use has greatly reduced waste generation, Unfortunately, the full slate of benefits that enzymes can impart to a broader range of chemical processes is …

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Reducing Print Time While Minimizing Loss In Mechanical Properties In Consumer Fdm Parts, Long Le, Mitchel A. Rabsatt, Hamid Eisazadeh, Mona Torabizadeh Jan 2022

Reducing Print Time While Minimizing Loss In Mechanical Properties In Consumer Fdm Parts, Long Le, Mitchel A. Rabsatt, Hamid Eisazadeh, Mona Torabizadeh

Mechanical & Aerospace Engineering Faculty Publications

Fused deposition modeling (FDM), one of various additive manufacturing (AM) technologies, offers a useful and accessible tool for prototyping and manufacturing small volume functional parts. Polylactic acid (PLA) is among the commonly used materials for this process. This study explores the mechanical properties and print time of additively manufactured PLA with consideration to various process parameters. The objective of this study is to optimize the process parameters for the fastest print time possible while minimizing the loss in ultimate strength. Design of experiments (DOE) was employed using a split-plot design with five factors. Analysis of variance (ANOVA) was employed to …

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Assembly Of Alumina Particles In Aqueous Suspensions Induced By High‐Frequency Ac Electric Field, James E. John, Shizhi Qian, Dipankar Ghosh Jan 2022

Assembly Of Alumina Particles In Aqueous Suspensions Induced By High‐Frequency Ac Electric Field, James E. John, Shizhi Qian, Dipankar Ghosh

Mechanical & Aerospace Engineering Faculty Publications

The role of high-frequency alternating current (AC) electric field in the assembly of alumina particles in aqueous media was investigated. Field–particle interactions were in situ investigated for coarse and fine powder particles in very dilute suspensions. For both coarse and fine particles, AC field-induced assembly led to the formation of chains of particles within a minute, which were aligned in the field direction. However, a much finer network of particle chains evolved in fine particle suspensions. Threshold field strength for chain formation was also lower for fine particles (28 V/mm) than for coarse particles (50 V/mm), suggesting stronger interactions for …

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Spray Deposition Of Sustainable Plant Based Graphene In Thermosetting Carbon Fiber Laminates For Mechanical, Thermal, And Electrical Properties, Daniel W. Mulqueen, Siavash Sattar, Thienan Le, Oleksandr G. Kravchenko Jan 2022

Spray Deposition Of Sustainable Plant Based Graphene In Thermosetting Carbon Fiber Laminates For Mechanical, Thermal, And Electrical Properties, Daniel W. Mulqueen, Siavash Sattar, Thienan Le, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

Graphene has generated substantial interest as a filler due to its exceptional strength, flexibility, and conductivity but faces obstacles in supply and implementation. A renewable, plant-based graphene nanoparticle (pGNP) presents a more accessible filler with the same properties as mineral graphenes. In this study, we examine the effects of pGNP, which was sprayed on a carbon fiber/epoxy prepreg at loadings from 1.1 to 4.2 g/m2. The study considered the mechanical, thermal, and electrical properties of pGNP-composite. An even particle dispersion was achieved using a spray application of pGNP in a water/alcohol suspension with the addition of surfactants and …

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3d Printing And Shape Memory Of Silicone Acrylate Polymers, Aphiwat Pongwisuthiruchte Jan 2022

3d Printing And Shape Memory Of Silicone Acrylate Polymers, Aphiwat Pongwisuthiruchte

Chulalongkorn University Theses and Dissertations (Chula ETD)

The purpose of this research is to develop a novel UV curable resin as a 3D printing material which possesses shape memory properties. The first part of the study focuses on formulating acrylate-based resins by combining low-cost polypropylene glycol (PPG) with a commercial acrylate-based resin. The effects of PPG content on the printability, thermal, mechanical, and thermomechanical properties of the formulated resins were studied. The results show that the mechanical properties of the printed parts were successfully enhanced at a small loading of 5%vol. However, a higher PPG content leads to printing failure and reduced mechanical properties. The degree of …

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The Role Of Microstructure On High-Temperature Oxidation Behavior Of Hafnium Carbide, Jonathan A. Scott, Xiaoqing He, David W. Lipke Jan 2022

The Role Of Microstructure On High-Temperature Oxidation Behavior Of Hafnium Carbide, Jonathan A. Scott, Xiaoqing He, David W. Lipke

Materials Science and Engineering Faculty Research & Creative Works

Microstructure development of the products formed upon oxidation of hafnium carbide (HfCx, x = 0.65, 0.81, or 0.94) at 1300°C and 0.8 mbar oxygen pressure was investigated using Raman spectroscopy, X-ray diffraction, electron microscopy, and electron energy-loss spectroscopy. For all specimens a multilayered oxide scale was observed featuring an outermost porous hafnia layer and an interlayer adjacent to the parent carbide containing hafnia interspersed with carbon. The outermost hafnia features coarse pores presumably formed during initial stages of oxidation to allow rapidly evolving gaseous products to escape from the oxidation front. As the oxidation scale thickens, diffusional resistance results in …

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On The Effect Of Hot Rolling On Inclusion Size And Distribution In A Cast Aisi 1070 Steel Railroad Wheel, Jacob M. Summers, Soumava Chakraborty, Laura Bartlett, Ronald J. O'Malley, Mario F. Buchely, Richard Pilon Jan 2022

On The Effect Of Hot Rolling On Inclusion Size And Distribution In A Cast Aisi 1070 Steel Railroad Wheel, Jacob M. Summers, Soumava Chakraborty, Laura Bartlett, Ronald J. O'Malley, Mario F. Buchely, Richard Pilon

Materials Science and Engineering Faculty Research & Creative Works

The goal of this work is to examine the effect of hot deformation on shrinkage porosity and nonmetallic inclusions in an AISI 1070 grade steel industrially produced wheel casting. Steel cleanliness is an important consideration as it influences the mechanical properties of the final product. A high density of porosity and inclusions have been shown to be detrimental for mechanical properties, especially during hot rolling. Using a laboratory-scale rolling mill, cast preforms were subjected to a 66% cumulative reduction to determine the effect of thermomechanical processing on void closure and inclusions that may produce anisotropy in mechanical properties. Quantitative automated …

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Dielectric State Variables As Qualitative Indicators Of Moisture Absorption-Caused Mechanical Property Degradation In Gfrp Composite Structures, Partha Pratim Das, Vamsee Vadlamudi, Rassel Raihan Jan 2022

Dielectric State Variables As Qualitative Indicators Of Moisture Absorption-Caused Mechanical Property Degradation In Gfrp Composite Structures, Partha Pratim Das, Vamsee Vadlamudi, Rassel Raihan

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

Fiber reinforced polymer (FRP) composites are being used in numerous fields owing to their intrinsic strength to weight ratio and various design benefits. However, these materials are prone to environmental aging, particularly moisture absorption. In essence, absorbed moisture infiltrates the polymer matrix and induces changes in the polymer network through chain scission, plasticization, and other bonding interactions. This causes irreversible damages to the material and significantly decreases mechanical strength. In this study, Broadband Dielectric Spectroscopy (BbDS) has been used to identify the absorption mechanisms in glass fiber reinforced polymer (GFRP) composites by detecting the related polarization mechanisms. Here, results show …

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Dielectric Analysis To Predict Moisture Absorption In Structural Composites: A Data-Driven Approach, Partha Pratim Das, Monjur Morshed Rabby, Vamsee Vadlamudi, Rassel Raihan Jan 2022

Dielectric Analysis To Predict Moisture Absorption In Structural Composites: A Data-Driven Approach, Partha Pratim Das, Monjur Morshed Rabby, Vamsee Vadlamudi, Rassel Raihan

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

Due to continual exposure to moist environment, environmental degradation is a major threat to structural composites throughout their service life. Impedance Spectroscopy (IS)/Broadband Dielectric Spectroscopy (BbDS) is a reliable nondestructive method that has been used in polymer industries for dielectric characterization of material. While moisture absorption causes irreversible changes in the polymer matrix composites, it also alters the electrical properties of the system which is detectable using BbDS. Since the physics that drives the change in electrical characteristics is driven by the modifications imposed by water molecules (whether free or bound), both events can be linked. A dielectric spectrum over …

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Coupled Effects In Dielectric And Thermal Properties Of Polymer Matrix Composite Structures Due To Moisture Absorption, Partha Pratim Das, Monjur Morshed Rabby, Vamsee Vadlamudi, Kenneth Reifsnider, Rassel Raihan Jan 2022

Coupled Effects In Dielectric And Thermal Properties Of Polymer Matrix Composite Structures Due To Moisture Absorption, Partha Pratim Das, Monjur Morshed Rabby, Vamsee Vadlamudi, Kenneth Reifsnider, Rassel Raihan

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

Fiber reinforced polymer (FRP) composites are being used in number of fields including aerospace, marine, sports, medical, power sectors, etc. due to their lightweight nature while retaining high mechanical performance in terms of high specific strength, stiffness, and great fatigue properties. However, the applicability of these materials is restricted by their stability up to a certain temperature (i.e. glass transition temperature) and environmental degradation (i.e. moisture, UV light, etc.). Moisture ingression greatly reduces their mechanical properties altering material structure by causing polymer plasticization, chain scission and fiber-polymer interface deterioration. These changes instantaneously affect the thermal properties of the materials which …

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The Effect Of Plasma Treatment On The Cure Behavior Of Out-Of-Life Prepregs And An Investigation Of The Mechanical Properties Of Composite Parts Manufactured From Plasma-Treated Prepregs, Monjur Morshed Rabby, Partha Pratim Das, Minhazur Rahman, Vamsee Vadlamudi, Rassel Raihan Jan 2022

The Effect Of Plasma Treatment On The Cure Behavior Of Out-Of-Life Prepregs And An Investigation Of The Mechanical Properties Of Composite Parts Manufactured From Plasma-Treated Prepregs, Monjur Morshed Rabby, Partha Pratim Das, Minhazur Rahman, Vamsee Vadlamudi, Rassel Raihan

Institute of Predictive Performance Methodologies (IPPM-UTARI)-Archive

Many industries, including aircraft, automobiles, and marine, are using prepreg (pre-impregnated fibers and a partially cured polymer matrix) to manufacture composite parts to achieve optimum fiber and resin volume ratio and part repeatability. Since prepregs have a short out oflife (i.e., the maximum storing time allowed at room temperature), they must be stored in refrigerators at low temperatures, which, if not maintained, have an unfavorable influence on the intended quality of the final product. For the present study, glass/epoxy prepregs (expired out-life) were plasmatreated before being used to make the composite part to compensate for the room temperature aging effect. …

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Designing Physical And Chemical Confinement In Lithium Sulfur Battery Cathode For Suppression Of Shuttle Effect, Saisaban Fahad Jan 2022

Designing Physical And Chemical Confinement In Lithium Sulfur Battery Cathode For Suppression Of Shuttle Effect, Saisaban Fahad

Electronic Theses and Dissertations, 2020-2023

Lithium sulfur batteries (LSBs) are attracting attention as a next generation energy storage device because of their high energy density (2670WhKg-1), high specific capacity (1675 mAhg-1), low cost and environmental friendliness. However, there are several challenges that need to be overcome before LSBs can be implemented in general applications. This is due to the low electric conductivities of sulfur and lithium sulfide and large volume changes during charge/discharge cycling. Also, most importantly, the dissolution of lithium polysulfides into the electrolyte during cycling leads to capacity decay and low coulombic efficiency. Additionally, these lithium polysulfides can diffuse to the lithium anode …

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A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy Jan 2022

A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy

Theses and Dissertations--Chemical and Materials Engineering

The exact surface configuration of scandate cathodes has been a point of contention for the materials community for a long time. Without proper understanding of it and the related structures and emission mechanisms, scandate cathodes remain patchy and unreliable emitters. Thus, density functional theory techniques were applied to various potential surface arrangements and found that there are several low-energy surfaces with low work functions that incorporate a scandium interlayer between tungsten and oxygen or otherwise have a scandium-on-tungsten structure. Furthermore, it was discovered that adding a monolayer of scandium directly to a tungsten surface is surprisingly favorable, thermodynamically. While none …

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Pitch-Based Carbon Fiber Derived From Coal Extract Liquids, Cierra Danielle Crowe Jan 2022

Pitch-Based Carbon Fiber Derived From Coal Extract Liquids, Cierra Danielle Crowe

Theses and Dissertations--Chemical and Materials Engineering

Limited coal coking operations and the use of coal-tar pitch as a binding agent in the production of metallurgical anodes has led to a limited availability of coal tar pitch for carbon fiber products. This has sparked interest in utilizing non-metallurgical coal-based liquids as an alternative to traditional coal tar from metcoke operations. This can be achieved by low severity solvent extraction, with heavy aromatic solvents, to produce coal liquids that act as precursor to pitch-based carbon fiber. This thesis aims to establish the processing and determine the impact of utilizing coal liquids to produce carbon fiber. In this work …

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Green-Route Synthesis Of Halide Perovskite Materials And Their Optoelectronic Properties, Xiaobing Tang Jan 2022

Green-Route Synthesis Of Halide Perovskite Materials And Their Optoelectronic Properties, Xiaobing Tang

Theses and Dissertations--Chemical and Materials Engineering

Colloidal semiconductor quantum dots (QDs), also called as nanocrystals (NCs), are a class of functional materials with extraordinary properties, which are different from their bulk counterparts and benefit from their exclusive quantum confinement (size) effect. Semiconductor exhibits the quantum confinement effect when the characteristic size of the semiconductor is comparable to or smaller than the de Broglie wavelength of the electron wave function and/or the exciton Bohr diameter of the bulk semiconductor. In recent years, metal halide perovskite NCs, as next-generation semiconductor materials for lighting and display, have aroused a wide attention due to their excellent optoelectronic properties. However, traditional …

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Laptop Recycling Case Study: Estimating The Contained Value And Value Recovery Process Feasibility Of End-Of-Life Consumer Electronics, Zebulon Hart Jan 2022

Laptop Recycling Case Study: Estimating The Contained Value And Value Recovery Process Feasibility Of End-Of-Life Consumer Electronics, Zebulon Hart

Theses and Dissertations--Mining Engineering

Work has been done to establish, through the development and use of novel assay techniques and analysis metrics, the contained value of a sampling of laptop computers (as an analog for myriad e-waste sources). This work has conceptualized e-waste as an alternative to geologic-origin complex metallic ores and has likewise evaluated the feasibility of value recovery from e-waste sources in a similar manner to an ore. The application of conventional and novel mineral separation techniques to e-waste recycling processes has been evaluated and positive results are demonstrated. Further, this work has demonstrated the ability to identify the presence of base …

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Designing The Electrochemical Interface To Enable Lithium Metal Batteries, Supriya Koul Jan 2022

Designing The Electrochemical Interface To Enable Lithium Metal Batteries, Supriya Koul

Electronic Theses and Dissertations, 2020-2023

Although Li-ion battery is one of the most widely used energy storage devices, there have been extensive efforts to push its limit to meet the ever-increasing demands to improve its energy density for applications such as electric vehicles, portable electronics, and grid storages. Here, Li metal anode plays a key role in the next generation energy storage devices, ultimately enabling the anode-free configuration. However, there are major challenges that need to be overcome for a successful deployment of anode-free batteries. These include designing a competitive SEI, low Coulombic efficiency, and the formation of dendrites. To realize an effective anode-free configuration …

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Calcite Depression In Bastnaesite-Calcite Flotation System Using Organic Acids, Emmy Muhoza Jan 2022

Calcite Depression In Bastnaesite-Calcite Flotation System Using Organic Acids, Emmy Muhoza

Graduate Theses, Dissertations, and Problem Reports (ETD)

Bastnaesite is the primary source of light REEs, namely cerium (Ce), lanthanum (La), praseodymium (Pr), neodymium (Nd), to name a few. Bastnaesite is typically concentrated using the froth flotation beneficiation method. Flotation of bastnaesite suffers from high reagent consumption due to the similar surface characteristics of bastnaesite and associated gangue minerals, including calcite. Additionally, complex stages of high-temperature conditioning are often required to suppress the detrimental impact of dissolved calcium ions on the flotation of bastnaesite. This research seeks to investigate the capabilities of organic acids in the bastnaesite-calcite flotation systems to selectively depress calcite minerals and effectively chelate calcium …

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Molecular Modeling Of High-Performance Polymers, Sagar Umesh Patil Jan 2022

Molecular Modeling Of High-Performance Polymers, Sagar Umesh Patil

Dissertations, Master's Theses and Master's Reports

High-performance polymers are extensively used in the aerospace and aeronautics industries due to their low density, high specific strength, and high specific stiffness. These properties along with better infiltration with reinforcements [carbon nanotubes (CNTs), glass, etc.] capability make them an excellent candidate to fabricate Polymer Matrix Composites (PMCs) tailored for specific applications. The applications range from products used daily to deep space exploration. These materials are subjected to varying temperatures and pressures during fabrication and in service. Therefore, the evolution of their intrinsic properties needs to be studied and their ability to sustain extreme environmental conditions in outer space needs …

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Broadband Dielectric Spectroscopic Detection Of Ethanol: A Side-By-Side Comparison Of Zno And Hkust-1 Mofs As Sensing Media, Papa K. Amoah, Zeinab Mohammed Hassan, Pengtao Lin, Engelbert Redel, Helmut Baumgart, Yaw S. Obeng Jan 2022

Broadband Dielectric Spectroscopic Detection Of Ethanol: A Side-By-Side Comparison Of Zno And Hkust-1 Mofs As Sensing Media, Papa K. Amoah, Zeinab Mohammed Hassan, Pengtao Lin, Engelbert Redel, Helmut Baumgart, Yaw S. Obeng

Electrical & Computer Engineering Faculty Publications

The most common gas sensors are based on chemically induced changes in electrical resistivity and necessarily involve making imperfect electrical contacts to the sensing materials, which introduce errors into the measurements. We leverage thermal- and chemical-induced changes in microwave propagation characteristics (i.e., S-parameters) to compare ZnO and surface-anchored metal-organic-framework (HKUST-1 MOF) thin films as sensing materials for detecting ethanol vapor, a typical volatile organic compound (VOC), at low temperatures. We show that the microwave propagation technique can detect ethanol at relatively low temperatures (<100 >°C), and afford new mechanistic insights that are inaccessible with the traditional dc-resistance-based measurements. In addition, …

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Mechanical Behavior Of Plain Weave Nylon Reinforced Drop-Stitch Inflatable Panels, Anthony J. White Jan 2022

Mechanical Behavior Of Plain Weave Nylon Reinforced Drop-Stitch Inflatable Panels, Anthony J. White

Open Access Master's Theses

All CUI (Controlled Unclassified Information) is U.S. government property and has been removed from this thesis.

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