Engineering Commons^™

Fly Ash Based Geopolymer For High Temperature And High Compressive Strength Applications In Aggressive Environment, Aaryan Manoj Nair, Akm S. Rahman

Publications and Research

Geopolymers are the results of geosynthetic reactions between aluminosilicates and strong bases. This results in chemical bonds between aluminum (Al), Silicon (Si)and oxygen (O) composing polymer rings in tetrahedral coordination. These bonds give them widespread useful applications such as high heat bearing ceramics, and base construction material whilst being far more environmentally conscious. The purpose of the experiment is to examine the effect of Silicon Carbide whisker and inorganic glass particles on thermal and mechanical properties of Geopolymers. This study will help understand the effect of various compositions and concentrations of SiO₂ in mechanical strength. In this experiment, the …

Aps March Meeting 2020: Undergraduate-Friendly Research In Soft Matter And Beyond, Vianney Gimenez-Pinto

Title III Professional Development Reports

The in-person APS March Meeting 2020 taking place in Denver during March 02-06, 2020 was canceled in the last minute out of Covid-19 concerns for the well-being of the scientific community as well as the population of the city of Denver and the state of Colorado. Nevertheless, well-planned logistics by the physics community and the APS leadership, allowed attendants to share their findings, presenting their research works to their peers, and continuing the work towards the advancement of science. Given the historical and on-going under-representation of students of color in science and technology at all academic levels, there is a …

Tympanal Asymmetry In A Parasitoid Fly: Small Asymmetries Produce Big Gains, Max Mikel-Stites, Anne E. Staples

Biology and Medicine Through Mathematics Conference

No abstract provided.

Structure, Thermophysical Properties Of Liquids, And Their Connection With Glass Formability, Rongrong Dai

McKelvey School of Engineering Graduate Student Theses & Dissertations

Metallic glasses have drawn significant attention due to their unique properties, such as high strength, excellent elastic energy storage capacity, and versatile processability. However, why some liquids can easily form metallic glasses while others donմ is still unclear. Since metallic glasses are formed when liquids are cooled fast enough to bypass crystallization, we hope to better understand glass formation by investigating the structural evolution and thermophysical properties of the liquids as they are cooled toward the glass transition. Multiple molecular dynamics simulations suggest a crossover temperature for the dynamics near the liquidus temperature, which corresponds to the onset of cooperative …

First-Principles Studies Of Anion Engineering In Functional Ceramics, Steven Timothy Hartman

McKelvey School of Engineering Graduate Student Theses & Dissertations

Ceramic materials display a wide variety of valuable properties, such as ferroelectricity, superconductivity, and magnetic ordering, due to the partially covalent bonds which connect the cations and anions. While many breakthroughs have been made by mixing multiple cations on a sublattice, the equivalent mixed-anion ceramics have not received nearly as much attention, despite the key role the anion plays in the materials’ properties. There is great potential for functional ceramics design using anion engineering, which aims to tune the materials properties by adding and removing different types of anions in existing classes of ceramic materials. In this dissertation, I present …

Scalable Synthesis Of Nanostructured Metal Oxide Films Using Aerosol Chemical Vapor Deposition For Energy Storage Applications, Clayton Kacica

McKelvey School of Engineering Graduate Student Theses & Dissertations

As global energy consumption continues to rapidly increase, the need for new technologies to meet this demand in a sustainable way. Renewable sources such as solar and wind power are being increasingly utilized for electricity generation. However, the intermittent nature of these sources requires large-scale energy storage to reliably provide consistent power. Current grid-scale energy storage usually involves pumped hydroelectric systems, which are limited by location, or flywheel systems, which have limited use in high-power low-energy applications. Electrochemical storage solutions, such as lithium-ion batteries, provide robust energy storage that is not limited by location with a range of power and …

The Development Of All Solid-State Optical Cryo-Cooler, Junwei Meng

Optical Science and Engineering ETDs

This dissertation describes the development of an all solid-state optical cryo-cooler. Crystals of 10% wt. ytterbium-doped yttrium lithium fluoride (Yb³⁺:YLF) are used to cool an infrared HgCdTe sensor payload to an absolute temperature below 135 K, equivalent to delta T equal 138 K below ambient. This record level of cooling is accomplished with a single stage, in a completely vibration-free environment, with a corresponding cooling power of 190 mW. This milestone is made possible by the design and fabrication of an undoped YLF thermal link that efficiently shields the payload with a non-right angle kink from intense anti-Stokes …

Development Of Multi-Axial Fatigue Retrofits For Lock Gate Components, Logan Verkamp

Graduate Theses and Dissertations

Lock gates are essential infrastructure components to the United State (US) supply chain. They create large cost savings and environmental benefits when compared with traditional methods of transport (freight and rail). Because of the large quantity of goods and dependence on these shipping chains, the US economy can be drastically affected by an unexpected gate closure. Unfortunately, many lock gates within the US have reached or exceeded their designed life. Due to the intensity of cyclic loads and the environment, fatigue cracks have become a prominent issue. Developed cracks near the pintle region (a joint which the gate rotates and …

Chemical And Electronic Surface Structure Of Chalcopyrite-Based Thin Films For Solar Water Splitting, James C. Carter

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, various thin film solar devices have reached markedly high efficiencies on both the laboratory and large area scale. To further evaluate their potential, and help drive device optimization of efficient solar devices, a detailed understanding of the chemical and electronic structure of the surfaces and interfaces is required. It is these interfaces that play a pivotal role in dictating aspects of device performance. Chalcopyrite-based materials, such as Cu(In,Ga)S2 (CIGS) are regarded as one of the most promising absorber materials for use in highly efficient solar devices. In the context of photoelectrochemical (PEC) hydrogen generation, the tunability of …

Spherical Cavity Expansion Approach For The Study Of Rigid-Penetrator’S Impact Problems, Mario Buchely, Alejandro Marañon

Materials Science and Engineering Faculty Research & Creative Works

In recent years, Spherical Cavity Expansion (SCE) theory has been extensively utilized to model dynamic deformation processes related to indentation and penetration problems in many fields. In this review, the SCE theory is introduced by explaining the different mathematical features of this theory, its solution, and a potential application to model the penetration of a rigid penetrator into a deformable target. First, a chronologically literature review of the most common models used to study this kind of penetration problems is introduced, focusing on the SCE theory. Then, the engineering model of penetration is presented using the SCE approach. The model …

Effects Of Polytetrafluoroethylenemicro–Particles On Mechanical Andtribological Properties Of Glass Fiberreinforced Polyoxymethylene, Kunnan Singh Jasbir Singh

Student Works (2020-2029)

Reinforcing polyoxymethylene (POM) with glass fibers (GF) enhances its mechanical properties, but at the expense of tribological performance. Formation of a transfer film to facilitate tribo–contact is compromised due to the abrasiveness of GF. As a solid lubricant, for example, polytetrafluoroethylene (PTFE) significantly improves friction and wear resistance. The effects of chemically etched PTFE micro–particles on the fiber– matrix interface of POM/GF/PTFE composites have not been systematically characterized. This research investigated the effects of PTFE micro–particles on mechanical and tribological properties of POM/GF/PTFE composites. Since PTFE is immiscible with most polymers, the surface was etched using sodium naphthalene salt dissolved …

Materials, Micro-Stacks And Related Applications Of Single-Chamber Solid Oxide Fuel Cells, Zhe Lv, Bo Wei, Zhi-Hong Wang, Yan-Ting Tian

Journal of Electrochemistry

Single-chamber solid oxide fuel cell (SC-SOFC) is a special type of fuel cells, in which both an anode and a cathode are placed in one chamber. Its working principle relies on the selective catalytic activity of the electrodes towards fuel and oxidant in a gas mixture, leading to the generation of an electromotive force. Because of its unique principle and structure, SC-SOFC has many advantages such as sealing-free, easy stacking, quick start-up and no carbon deposition, thus, it possesses large potential in application. Herein, the principles and characteristics of SC-SOFC are introduced. Furthermore, the SC-SOFC materials, micro-stack design, degeneration mechanisms …

Syntheses And Properties Of Ta5+ Doped Li7La3Zr2O12, Feng-Feng Peng, Shi-You Li, Tong-Tong Geng, Chun-Lei Li, Shuang-Wei Zeng

Journal of Electrochemistry

The tantalum ion (Ta ⁵⁺) doped garnet-type inorganic solid electrolyte Ta-LLZO was prepared by solid state reaction, and the effect of doping amount on the properties of the materials was investigated. The materials were characterized by X-ray diffraction (XRD), field emission electron scanning microscopy (FESEM) and electrochemical impedance spectroscopy (EIS). And the cycle stability was tested by assembly of LiFePO₄//LLZTO//Li all solid lithium battery. The results show that with the increase of Ta ⁵⁺ doping amount, the material appeared to form a single cubic phase structure. When the Ta ⁵⁺ doping content became 14.09wt.%, x=0.3, the …

Preparation And Characterization Of Cathode Supported Solid Oxide Fuel Cell, Xiao-Nan Bao, Guang-Jun Zhang, Shao-Rong Wang

Journal of Electrochemistry

A site deficient (La_0.8Sr_0.2)_0.95MnO₃ (LSM95) powder was synthesized by solid state reaction as a cathode material. The commercial Zr_0.9Sc_0.1SO_1.95 (SSZ) was selected as an electrolyte material and La_0.8Sr_0.2Cr_0.5Mn_0.5O₃- (LSCrM) was synthesized by sol-gel method as an anode material. Accordingly, single cells of LSCrM-CeO₂|SSZ|3YSZ-LSM95 were prepared by tape casting, sintering and impregnation. The single cell test results for LSCrM-CeO₂|SSZ|3YSZ-LSM95 with 0.11 g·cm ^-2 CeO₂ and using CH₄ as a fuel showed the power …

Direct Carbon Solid Oxide Fuel Cells, Jiang Liu, Xiao-Min Yan

Journal of Electrochemistry

Carbon is richly reserved in coal, biomasses, and many other nature resources. It is usually used as an energy source through oxygen oxidation reaction. The oxidation is generally realized through combustion which causes serious air pollution. Besides, the conversion efficiency of generating electricity through the combustion process is limited by Carnot efficiency. A direct carbon solid oxide fuel cell (DC-SOFC) is a solid oxide fuel cell (SOFC) directly operated with solid carbon as the fuel. It can convert the chemical energy of carbon into electricity with high efficiency. The concentration of produced CO₂ from a DC-SOFC is so high …

Research Progress Of Fuel Electrode In Oxide-Ion Conducting Solid Oxide Electrolysers, Ling-Ting Ye, Kui Xie

Journal of Electrochemistry

Solid oxide electrolysers are now attracting much more attentions because they can efficiently produce fuels by electrolyzing H₂O/CO₂. In this paper, a comprehensive introduction to the recent progress in the development of fuel electrode (cathode) materials is provided. The advantages, disadvantages and development trend towards various cathode materials are pointed out. The key scientific and technological problems in this field are emphasized.

Development Status And Prospects Of Hydrogen Production By High Temperature Solid Oxide Electrolysis, Wen-Qiang Zhang, Bo Yu

Journal of Electrochemistry

Solid oxide electrolysis cell is an advanced energy conversion device with high efficiency, simplicity, flexibility, and environmental friendliness. It is currently a research hotspot in the international energy field. This paper introduces and analyzes the basic principles, key materials, system components and developments of solid oxidation electrolysis cells. Furthermore, the recent research progresses, challenges and future development directions in solid oxidation electrolysis cells in the field of high-efficiency hydrogen production are summarized and outlined.

Nio@Rgo Supported Palladium And Silver Nanoparticles As Electrocatalysts For Oxygen Reduction Reaction, Shuo Yao, Tai-Zhong Huang, Rizwan Haider, Heng-Yi Fang, Jie-Mei Yu, Zhan-Kun Jiang, Dong Liang, Yue Sun, Xian-Xia Yuan

Journal of Electrochemistry

For pervasive applications of fuel cells, highly efficient and economical materials are required to replace Pt-based catalysts for oxygen reduction reaction (ORR). In this study, the NiO@rGO, Pd-NiO@rGO and Ag-NiO@rGO nanoparticles were synthesized, and their catalytic performances toward ORR were investigated. The results revealed that all the three materials were capable of catalyzing ORR, but both the Pd-NiO@rGO and Ag-NiO@rGO showed the better performances compared with the NiO@rGO in terms of the reaction pathway being 4-electron process, the increases of the onset potential and the intermediate yielding rate, as well as the extended stability. Moreover, the effect of Pd modification …

Recent Advances Of Co2 Electrochemical Reduction In Solid Oxide Electrolysis Cells, Yi-Hang Li, Chang-Rong Xia

Journal of Electrochemistry

Solid oxide electrolysis cells (SOECs) have stimulated wide interests for their promising application in the reduction of CO₂ emissions and the storage of renewable energy. Here, the advances made in the development of cathode materials including cermets and perovskite oxides in our research group, are summarized, along with the design of cell configurations. The electrochemical kinetics and performances of cathodes and cells are discussed and analyzed. It is expected that this brief review offers critical insights and useful guidelines for developing superior electrodes and SOECs in the future.

Perovskite Catalysts For Fuel Reforming In Sofc:A Review And Perspective, Tong Wei, Jian Li, Li-Chao Jia, Bo Chi, Jian Pu

Journal of Electrochemistry

Solid oxide fuel cell (SOFC) is a generating device by electrochemical reaction to transfer the chemical energy of fossil fuels (coal, oil and gas, etc.), the biomass fuel or other hydrocarbon fuels directly into electricity with higher energy conversion efficiency and lower pollution, which is recognized to be efficient green energy technology in the 21st century. However, when hydrocarbons are directly used as fuel, carbon deposition is easy to occur in nickel-based anode, thus, losing electrochemical catalytic activity. Fuel pre-reforming on the outside of the anode is an effective solution, which strongly relies on highly efficient and stable reforming catalysts. …

Research Progress In Ethane Dehydrogenation To Cogenerate Power And Value-Added Chemicals In Solid Oxide Fuel Cells, Yun Fan, Qi Wang, Jun Li, Jing-Li Luo, Xian-Zhu Fu

Journal of Electrochemistry

Increasing supplies of methane/shale gas have promoted global development of higher value chemicals such as ethylene production by ethane, which dramatically changes the markets of petrochemical industry. Clean and efficient transformation of ethane into higher value chemicals has far-reaching significance. Ethylene production through ethane steam cracking is a relatively matured technology for industrial production. However, the process consumes large amounts of energy and the presence of carbon deposition becomes a serious problem which is difficult to be solved. The cogenerated energy-chemicals solid oxide fuel cells have been widely studied because fuel gas can be converted into high-value chemicals via spontaneous …

Construction And Electrochemical Performance Of Garnet-Type Solid Electrolyte/Al-Li Alloy Interface, Jia-Lin Ma, Hong-Chun Wang, Zheng-Liang Gong, Yong Yang

Journal of Electrochemistry

Garnet-type solid electrolyte is a newly developed Li ion conductor and promising in the application of all-solid-state batteries. However, Garnet is incompatible with Li anode, which restricts the application of Garnet-type solid batteries. In order to improve the contact between Garnet-type solid electrolyte and Li electrode, a composite anode which contains Al-Li alloy (Al₄Li₉) was prepared as an electrode. Al-Li alloy has many advantages such as easy preparation, low cost, simple post-treatment and high capacity. Garnet-type Li_6.5La₃Zr_1.75W_0.25O₁₂ (LLZWO) was synthesized via solid-state reaction. Garnet solid electrolyte has …

Designing An Adjustable And Transportable Staircase, Allison Currey

Undergraduate Honors Thesis Projects

People climb stairs every day, whether it is at work, a store, or at home; however, there are populations such as people who are elderly, with pathologies, with Parkinson’s disease, or have suffered from a stroke that see climbing the stairs as a challenging task and it decreases their mobility and quality of life. Factors such as muscle weakness, strategy, and balance have been previously investigated in these populations during stair climbing. However, few studies have researched how stair climb ability, balance, and perception of difficulty are influenced by step height. The objective of this thesis is to design a …

Stationary Exercise Classification Using Imus And Deep Learning, Andrew M. Heroy, Zackary Gill, Samantha Sprague, David Stroud, John Santerre

SMU Data Science Review

In the current market, successful fitness tracking devices utilize heart rate and GPS to determine performance. These devices are useful, but don't extensively classify stationary exercise. This paper proposes a modern approach for tuning and investigating optimal neural network types on stationary exercises using Inertial Measurement Units (IMUs). Using three IMUs located on the ankle, waist, and wrist, data is collected to map the body as it moves during the stationary physical activity. A novel five-stage deep learning tuning system was written and deployed to classify user movement as one of three classes: air squats, jumping jacks, and kettlebell swings. …

Subsurface Analytics: Contribution Of Artificial Intelligence And Machine Learning To Reservoir Engineering, Reservoir Modeling, And Reservoir Management, Shahab D. Mohaghegh

Faculty & Staff Scholarship

Subsurface Analytics is a new technology that changes the way reservoir simulation and modeling is performed. Instead of starting with the construction of mathematical equations to model the physics of the fluid flow through porous media and then modification of the geological models in order to achieve history match, Subsurface Analytics that is a completely AI-based reservoir simulation and modeling technology takes a completely different approach. In AI-based reservoir modeling, field measurements form the foundation of the reservoir model. Using data-driven, pattern recognition technologies; the physics of the fluid flow through porous media is modeled through discovering the best, most …

Morphology And Structure Of Pb Thin Films Grown On Si (111) By Pulsed Laser Deposition, Bektur Abdisatarov

Masters Theses & Specialist Projects

Pulsed laser deposition (PLD) is a versatile thin film deposition technique in which high powered laser beam interacts with a target material inside an ultrahigh vacuum chamber. Highly energetic particles such as electrons, atoms, protons, and ions generate a plasma plume that directed towards a substrate material where recondenses form a thin film. PLD is an effective and reliable method to create varieties of thin films such as metal, polymer, and ceramic for many technologically essential applications.

In this study, thin Pb films were grown by pulsed laser deposition on Si (111) at various laser fluences, pulse wavelengths, deposition times, …

Stability Analysis, Dynamic Modeling, And Kinematic Analysis Of Hydraulically Amplified Dielectric Elastomer Actuators And Robot Manipulators, Amir Hosein Zamanian

Mechanical Engineering Research Theses and Dissertations

In this dissertation, we have proposed a new dielectric elastomer actuator design and model that couples electrostatics, fluid mechanics, linear and nonlinear elastic deformations. The internal hydraulic pressure can amplify the structural deformation generated by induced electrostatic forces (Maxwell pressure), given the name of this class of actuators, hydraulically amplified dielectric elastomer actuators (HADEAs).

First, we developed novel lumped-parameter models (LPMs) using linear and hyper-elastic material models and second compared the LPM results with finite element analysis in quasi-static simulations. We analytically expressed the conditions for the snap-through instability in the HADEA, which appears after exceeding a certain voltage applied …

Dynamic And Control Of Air-Bearing Spacecraft Simulator, Jacob Joseph Korczyk

Doctoral Dissertations and Master's Theses

An air bearing is being designed as a spacecraft rotational motion simulator, featuring the Sawyer Robot and its control box. The objective is to maneuver the robot as desired, performing operations specific to on-orbit servicing operations while maintaining stability of the system. Before the control can be designed, the dynamics of the platform and the robot must be modeled. The dynamics of the robot can be derived utilizing a Newton-Euler recursive approach. By beginning with a simple pendulum, then adding links (degrees of freedom) to more closely resemble the Sawyer arm, the equations of motion for the robot can be …

Fatigue Damage Assessment Of Reinforced Concrete Slabs Using Integrated Dynamic Testing And Simulation, Jamadin Adiza

Student Works (2020-2029)

Assessment of existing fatigued structures is an important aspect of civil engineering infrastructure. This is critical in most loaded civil engineering structures such as bridges that are constantly subjected to dynamic loading, causing fatigue in the materials over time. Bridge deck slabs are one of the most structural elements susceptible to different cyclic loads, requiring regular checks for damage to fatigue. In order to understand the deterioration, fatigue carrying capacity and residual strength, the serviceability of the slab under the fatigue loads was not fully explored. Therefore, this research is designed to use vibration-based techniques to investigate the integrity of …

Hybrid Non-Destructive Assessment For Flow Induced Vibration Piping Systems Using Coupled Fluid-Structure Interaction, Keen Kuan Kong

Student Works (2020-2029)

Pipelines and piping systems are of great importance in many industries such as water supply, petroleum and petrochemicals and nuclear power generation. They provide transport for high-velocity pressurized fluids operating under time-varying conditions. They are required to operate non-stop for a schedule of 24 hours a day, 7 days a week. Piping vibration failures have been one of the major causes of downtime, fires and explosions in industrial plant over the past 30 years. Failure of piping systems can have disastrous effects, leading to injuries and fatalities as well as to substantial cost to industry and the environment. Flow-induced vibration …