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Articles 1 - 7 of 7
Full-Text Articles in Engineering
Development Of Pre-Magnetized Magnetorheological Elastomer For Bidirectionally Variable Stiffness Applications, Choonghan Lee
Development Of Pre-Magnetized Magnetorheological Elastomer For Bidirectionally Variable Stiffness Applications, Choonghan Lee
UNLV Theses, Dissertations, Professional Papers, and Capstones
Magnetorheological elastomers (MREs) utilize magnetic forces between ferromagnetic particles to cause variable stiffness properties and damping with external magnetic fields. In the MREs, the particles are embedded in a cured elastomer matrix, and an external magnetic field makes the stiffness change due to induced magnetic forces among particles. A disadvantage of the conventional MREs is that they cannot be softened (reduced stiffness) under an external magnetic field. Considering that there are many engineering applications where fast changes of stiffness in both directions (stiffening and softening) are required, embedding magnetically biased particles in the MRE can provide potential solutions. In this …
Towards Cfd Investigations Into Particulate Air Pollution Of A Desert Urban Environment, Prosun Roy
Towards Cfd Investigations Into Particulate Air Pollution Of A Desert Urban Environment, Prosun Roy
UNLV Theses, Dissertations, Professional Papers, and Capstones
This dissertation has explored computational fluid dynamics (CFD) techniques for studying particulate air quality in the Las Vegas urban area. The dissertation is based on three research tasks: • High time-resolution fenceline air quality sensing and dispersion modeling for environmental justice-centered source attribution. (Chapter 2) • Pollen dispersion and deposition in real-world urban settings: A computational fluid dynamic study. (Chapter 3) • Effects of urban canopy parameterizations on modeling pollen dispersion and exposure. (Chapter 4) In Chapter 2, we investigate the facilitation of low-cost air quality sensors (LCAQS) and CFD technique on exposure assessment of environmental justice (EJ) communities and …
High-Yield Bioinspired Atmospheric Water Capture Through Hydrogels, Yiwei Gao
High-Yield Bioinspired Atmospheric Water Capture Through Hydrogels, Yiwei Gao
UNLV Theses, Dissertations, Professional Papers, and Capstones
Water scarcity is a global issue affecting billions of people, and atmospheric water harvesting (AWH) technology has been identified as a potential solution. However, existing single-material AWH approaches have limited water harvesting yields due to alternated water capture, storage, and release stages, and only function within a high relative humidity range. In my doctoral research project, we developed a bio-inspired, hydrogel-based multi-layer AWH approach that allows for segregated capture, storage, and release stages, and is envisioned to have higher daily water harvesting efficiency even in low-humidity areas. My research began with understanding the relations between hydrogel mechanical stiffness, hydraulic permeability, …
Time-Dependent Wetting Behavior Of Hydrogels, Amir Kashani
Time-Dependent Wetting Behavior Of Hydrogels, Amir Kashani
UNLV Theses, Dissertations, Professional Papers, and Capstones
Hydrogels are 3-D polymers with hygroscopic properties that enable them to absorb and retain large amounts of water. In many applications such as biomedical applications, including drug delivery, wound healing, tissue engineering, biosensors, and contact lenses, agriculture, food and beverage, cosmetics, and environmental, hydrogels also need to maintain a high degree of wetting in order to ensure effective functionality and interaction with surrounding fluids or tissues in desired applications. The combination of wetting and absorptive behavior of hydrogels that are often encountered in biomedical, biological, industrial and the mentioned applications presents a challenging physical problem that is not completely understood. …
A One-Dimensional Analysis Of A Microbial Fuel Cell For Efficient Acetate Removal And Power Density Output, David Rouhani
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 …
An Investigation Of Soft Electrohydraulic Actuators: Theory, Characterization, And Conceptual Applications, Alexandrea Washington
An Investigation Of Soft Electrohydraulic Actuators: Theory, Characterization, And Conceptual Applications, Alexandrea Washington
UNLV Theses, Dissertations, Professional Papers, and Capstones
Electroactive polymer (EAP) materials are a novel soft electromechanical device that exploits the inherent electrical and mechanical advantages of flexible polymer materials. Within this groundbreaking field there are various actuator and sensor devices that have been developed for a variety of applications, from medical devices to artificial biological systems. This research focuses on electrohydraulic actuators, which are comprised of a flexible conductive medium, a dielectric fluid, and a compliant film material to encapsulate the dielectric fluid. This specific study centers around the electrohydraulic EAP actuator known as the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator, first introduced by the Keplinger group …
Metastability And Degradation In Cu(In,Ga)Se2 Thin-Film Solar Cells, Mohsen Jahandardoost
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 …