Engineering Commons^™

Nitrogen Doped Carbon Nanofibers Derived From Water-Soluble Precursors, Lee Cremar, Ben Jones, Nicole Martinez, Gustavo Mejia, Hilario Cortez, Edgar Muñoz, Rocío Nava, Karen Lozano

Mechanical Engineering Faculty Publications

Nitrogen doped carbon fibers were synthesized from polyvinyl alcohol (PVA), a water soluble precursor. The PVA fine fibers were first developed by centrifugally spinning an aqueous based solution using Forcespinning® technology. The precursor fibers were then exposed to sulfuric acid vapors to partially carbonize and stabilize the fibers for further heat treatment. For nitrogen doping, the fibers were exposed to two different heat treatment routes. One was under a nitrogen atmosphere at 850°C followed by exposure to ammonia gas at 500°C. The second route consisted of heating the treated fibers in pure ammonia gas only, up to 850°C. Both heating …

Micro-Cantilever Based Fiber Optic Hydrophone, Jie Liu

All Dissertations

Endoscopic photoacoustic imaging probe is becoming increasingly important for many clinical photoacoustic imaging applications in which the target tissue can only be accessed by introducing an endoscopic probe percutaneously or through a natural orifice. Miniature fiber optic hydrophone (FOH) has become an attractive choice for endoscopic photoacoustic imaging application. Fiber optic hydrophone has many proven advantages, including small size, light weight, immunity to electromagnetic interference, low cost for single-use application and capability of integration of excitation light source and acoustic wave receiver.

This dissertation demonstrates an open cavity, micro-cantilever based fiber optic Fabry-Perot interferometer (FPI) hydrophone. A fused silica micro-cantilever …

Synthesis And Characterization Of Glycidyl Methacrylate-Based Graft Copolymer Functional Interfaces, Nikolay Brordinov

All Dissertations

Modification of materials properties such as surface energy, wettability, ability to absorb, contain or release specific type of chemicals enables practical application of these materials in various scientific and engineering set-ups. However, designing protocol that could be easily adapted for different situations and simultaneously unlock multiple variations of the resulting properties is a non-trivial task. This dissertation is devoted to application of glycidyl methacrylate-based graft copolymers for the purposes of surface modification, establishing fundamental trends and dependencies of this process and exploring the possible range of applications. These materials have extremely valuable property to undergo controllable post-synthetic modifications including surface …

Green Chemistry Oxidative Modification Of Peptoids Utilizing Bleach And Tempo, Jesse Leland Roberts

Graduate Theses and Dissertations

Biotherapeutic drugs, derived from biological molecules such as proteins and DNA, are becoming an integral and exceptionally critical aspect of modern medicine. Compared to common pharmaceutical drugs, biotherapeutics are much larger in size and have greater target specificity, allowing them to treat many chronic diseases ranging from cancer to rheumatoid arthritis. The major issue with protein based therapeutics is that they readily undergo proteolysis, or enzymatic degradation, when administered through subcutaneous injections. Traditionally, biotherapeutic modification procedures have centered on the use of PEG derivatives. This process, called PEGylation, is unfavorable due to the increases in molecular weights of the proteins …

Synthesis Of Magnetic Carbon Supported Manganese Catalysts For Phenol Oxidation By Activation Of Peroxymonosulfate, Yuxian Wang, Yongbing Xie, Chunmao Chen, Xiaoguang Duan, Hongqi Sun, Shaobin Wang

Research outputs 2014 to 2021

Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe₃O₄/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as the precursor of manganese oxide. The Mn/MCS catalysts were characterized by a variety of characterization techniques and the catalytic performances of Fe₃O₄/C/Mn nanoparticles were tested in activation of peroxymonosulfate to produce reactive radicals for phenol degradation in aqueous solutions. It was found that Fe₃O₄/C/Mn catalysts can be well dispersed …

Additive Manufacturing Techniques And Their Biomedical Applications, Yujing Liu, Wei Wang, Laichang Zhang

Research outputs 2014 to 2021

Additive manufacturing (AM), also known as three-dimensional (3D) printing, is gaining increasing attention in medical fields, especially in dental and implant areas. Because AM technologies have many advantages in comparison with traditional technologies, such as the ability to manufacture patient-specific complex components, high material utilization, support of tissue growth, and a unique customized service for individual patients, AM is considered to have a large potential market in medical fields. This brief review presents the recent progress of 3D-printed ­biomedical materials for bone applications, mainly for metallic materials, including multifunctional alloys with high strength and low Young’s modulus, shape memory alloys, …

Aliasing Of The Schumann Resonance Background Signal By Sprite-Associated Q-Bursts, Anirban Guha, Earle Williams, Robert Boldi, Gabriella Sátori, Tamás Nagy, József Bór, Joan Montanyà, Pascal Ortega

All Works

© 2017 The Authors The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called ‘Q-burst’ (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of ∼10–12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly …

Multiple Content Adaptive Intelligent Watermarking Schemes For The Protection Of Blocks Of A Document Image, Chetan Kr Mr., S Nirmala Dr.

Journal of Digital Forensics, Security and Law

Most of the documents contain different types of information such as white space, static information and dynamic information or mix of static and dynamic information. In this paper, multiple watermarking schemes are proposed for protection of the information content. The proposed approach comprises of three phases. In Phase-1, the edges of the source document image are extracted and the edge image is decomposed into blocks of uniform size. In Phase-2, GLCM features like energy, homogeneity, contrast and correlation are extracted from each block and the blocks are classified as no-information, static, dynamic and mix of static and dynamic information content …

Surface And Interface Characterization Of Solution-Processed Metal Oxides And Pedot:Pss Using Photoelectron Spectroscopy, Lynette M. Kogler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solution-processed materials are appealing for use in printable electronics as a means to lower production costs, but precise control of the process is crucial for achieving the desired properties in the final materials and their interfaces. Electronic interface properties depend on both the involved materials and their fabrication processes, impacting the development and commercialization of these materials. Analyzing the chemical and electronic structure of these materials, particularly at the surfaces and interfaces, is important not only for insuring that the materials have the desired properties, but also for understanding the effects of the fabrication process and how to modify properties …

Comparison Of Simulation Methods Of Single And Multi-Bit Continuous Time Sigma Delta Modulators, Benju Koirala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Continuous time Sigma Delta Modulators (CT ΣΔMs) are a type of analog to digital converter (ADC) that are used in mixed signal systems to convert analog signals into digital signals. ADCs typically require antialiasing filter; however antialiasing filters are inherent in CT ΣΔMs, and therefore they require less circuitry and less power than other ADC architectures that require separate antialiasing filters. As a result, CT ΣΔM ADC architectures are preferred in many mixed signal electronic applications.

Because of the mixed signal nature of CT ΣΔMs, they can be difficult to simulate. In this thesis, various methods for simulating single-bit and …

Reliability Underseepage Assessment Of Levees Incorporating Geomorphic Features And Length Effects, Lourdes Polanco Boulware

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

It has been estimated that approximately fifty percent of the United States’ population lives behind levees. Because these earth structures are typically long, subjected to seasonal changes and spatial variability, it is logical to analyze them in an uncertainty-based approach. This research is focused on assessing the potential of internal erosion related failure due to underseepage with the general objective of assessing the failure potential of individual geomorphic features while considering length effects. The project team was granted $204,000 from the National Science Foundation and $10,000 from the United States Society on Dams which resulted in research collaboration within graduate …

Experimental And Simplified Analytical Investigation Of Full Scale Sandwich Panel Walls, Salam Adil. Al-Rubaye

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Concrete sandwich wall panels have been used for decades in the precast concrete construction industry because of their thermal efficiency. To achieve full or partial-composite action in concrete sandwich panel walls, the engineer must obtain a percent composite action from a connector manufacturer, making some engineers uncomfortable. Engineers are dependent upon the recommendations given by the connector manufacturers to establish their designs. This project tested six full scale sandwich panel walls to evaluate the percent composite action of various connectors and compare the results to those provided by the composite connector manufacturers.

This project aimed to validate current procedures using …

An Obstacle Avoidance System For The Visually Impaired Using 3-D Point Cloud Processing, Evan Justin Taylor

Theses and Dissertations

The long white cane offers many benefits for the blind and visually impaired. Still, many report being injured both indoors and outdoors while using the long white cane. One frequent cause of injury is due to the fact that the long white cane cannot detect obstacles above the waist of the user. This thesis presents a system that attempts to augment the capabilities of the long white cane by sensing the environment around the user, creating a map of obstacles within the environment, and providing simple haptic feedback to the user. The proposed augmented cane system uses the Asus Xtion …

Characterization Of Mechanical Properties Of Battery Electrode Films From Acoustic Resonance Measurements, Kathryn Lanae Dallon

Theses and Dissertations

Measurements of the mechanical properties of lithium-ion battery electrode films can be used to quantify and improve manufacturing processes and to predict the mechanical and electrochemical performance of the battery. This thesis demonstrates the use of acoustic resonances to distinguish among commercial-grade battery films with different active electrode materials, thicknesses, and densities. Resonances are excited in a clamped circular area of the film using a pulsed infrared laser or speaker and responses are measured using an electret condenser microphone. A numerical model is used to quantify the sensitivity of resonances to changes in mechanical properties. When the numerical model is …

Current State Of Practice Associated With The Use Of Building Information Modeling (Bim) In The Custom Home Building Industry, William Noble Smith

Theses and Dissertations

Building Information Modeling (BIM) has entered the construction industry and has permeated the commercial sector. Research is continually performed to expand the capabilities and applications within the industry. However, research has historically been mostly limited to the commercial sector and has seen little expansion to other sectors of the industry including the residential sector. The potential cause for this may be the limited number of industry professionals who utilize the software to the benefit of their companies. The focus of this study was specifically the custom home building sector of residential construction in the United States because of the unique …

Life Cycle Assessment In Foundry Sand Reclamation – Comparison Of Secondary Reclamation Processes, Samuel Keith Ghormley

Department of Environmental Engineering: Theses and Other Student Research

Foundries represent a significant part of the base of the world’s economy and as a sector are one of the largest consumers of energy and producers of solid waste in the United States. Sand casting foundries use approximately 5-10% of their total energy on sand handling processes. By adding a secondary sand reclamation process, foundries can expect to become more energy efficient as well as reducing solid waste from the foundry. To measure the broader environmental impacts, life cycle assessment (LCA) can be used. The goal of the current research was to examine a medium-sized foundry in the United States …

Design And Validation Of An Experimental Setup To Study Single Phase Heat Transfer Enhancement Of Femtosecond Laser Processed Metallic Surfaces, Sarah Jane Wallis

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

In the present work, a single phase flow heat transfer experimental loop was designed with the intention of studying the effects of femtosecond laser surface processing (FLSP) on metallic surfaces with the specific goal of enhancing heat transfer in compact heat exchangers currently in use by NASA. This experimental setup went through two major design iterations which are detailed in this thesis. The first iteration consisted of a counterflow fluid-to-fluid heat exchanger, which measured overall heat transfer coefficients and pressure drops, where the overall heat transfer coefficient is defined in terms of the total thermal resistance to heat transfer between …

The Development Of Novel Interconnection Technologies For 3d Packaging Of Wire Bondless Silicon Carbide Power Modules, Sayan Seal

Graduate Theses and Dissertations

This dissertation advances the cause for the 3D packaging and integration of silicon carbide power modules. 3D wire bondless approaches adopted for enhancing the performance of silicon power modules were surveyed, and their merits were assessed to serve as a vision for the future of SiC power packaging. Current efforts pursuing 3D wire bondless SiC power modules were investigated, and the concept for a novel SiC power module was discussed. This highly-integrated SiC power module was assessed for feasibility, with a focus on achieving ultralow parasitic inductances in the critical switching loops. This will enable higher switching frequencies, leading to …

Electron Yield Measurements Of High-Yield, Low-Conductivity Dielectric Materials, Justin Christensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this …

A Parameterized Simulation Of Doppler Lidar, David B. Chester

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Upcoming missions to explore planetary bodies in the solar system will require accurate position and velocity data during descent in order to land safely at a predesignated site. A Doppler lidar instrument could provide measurements of the altitude, attitude, and velocity of the landing vehicle to supplement the data collected by other instruments. A flexible simulation tool would aid the tasks of designing and testing the functionality of such an instrument.

LadarSIM is a robust parameterized simulation tool developed for time of flight lidar at Utah State University's Center for Advanced Imaging Ladar. This thesis outlines how LadarSIM was modified …

Estimating Evapotranspiration Using The Complementary Relationship And The Budyko Framework, Homin Kim

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Land surface actual evapotranspiration (ET) is an important process in terrestrial water balance and reliable estimates of ET are necessary to improve water resources management. In this regard, there is a growing body of literature that recognizes the importance of an accurate ET model. Among them, the complementary relationship between ET and potential ET (ETP) has been the subject of many studies because it uses only meteorological data as inputs. However, there is an increasing concern that some complementary relationship models perform poorly under dry conditions. To overcome this limitation, this dissertation was designed to extend the latest complementary relationship …

Phased-Array Feed Instrumentation And Processing For Astronomical Detection, Interference Mitigation, And Transient Parameter Estimation, Richard Allen Black

Theses and Dissertations

Radio astronomy, the survey and study of naturally occurring astronomical radio signals, is a challenging field in terms of engineering requirements. The typical astronomical signal of interest is incredibly faint, resulting in very low signal-to-noise ratios (SNRs) on the order of -30 dB or lower. To detect such signals, one must have an uncommonly low and stable receiver noise temperature, high gain through large aperture reflectors, and state-of-the-art signal processing algorithms. One must also be able to mitigate the effects of interference, the presence of which, even if extremely weak, can completely mask the faint astronomical signals of interest. To …

A Molecular Simulation Study Of Antibody-Antigen Interactions On Surfaces For The Rational Design Of Next-Generation Antibody Microarrays, Derek B. Bush

Theses and Dissertations

Antibody microarrays constitute a next-generation sensing platform that has the potential to revolutionize the way that molecular detection is conducted in many scientific fields. Unfortunately, current technologies have not found mainstream use because of reliability problems that undermine trust in their results. Although several factors are involved, it is believed that undesirable protein interactions with the array surface are a fundamental source of problems where little detail about the molecular-level biophysics are known. A better understanding of antibody stability and antibody-antigen binding on the array surface is needed to improve microarray technology. Despite the availability of many laboratory methods for …

Multiple Target Tracking In Realistic Environments Using Recursive-Ransac In A Data Fusion Framework, Jeffrey Dyke Millard

Theses and Dissertations

Reliable track continuity is an important characteristic of multiple target tracking (MTT) algorithms. In the specific case of visually tracking multiple ground targets from an aerial platform, challenges arise due to realistic operating environments such as video compression artifacts, unmodeled camera vibration, and general imperfections in the target detection algorithm. Some popular visual detection techniques include Kanade-Lucas-Tomasi (KLT)-based motion detection, difference imaging, and object feature matching. Each of these algorithmic detectors has fundamental limitations in regard to providing consistent measurements. In this thesis we present a scalable detection framework that simultaneously leverages multiple measurement sources. We present the recursive random …

Temporal Transformation Of Barrier Islands A Round Nakdong Estuary, Sukzun Youn

Theses and Dissertations

The Nakdong Estuary system near Busan, South Korea consists of dynamic shorelines characterized by morphological transformations that result from both natural disasters (typhoons and flooding) and construction projects (Nakdong Estuary Dam, gates in the West Nakdong River and Busan New-ports). This study aims to synthesize existing data for tides, waves, bathymetry and meteorological data obtained from a variety of institutions with the objectives of (1) identifying and ranking major factors that influence morphological transformations and (2) determining how these factors influence morphological change over time. These objectives were met by analyzing patterns of flow and sediment transport using Center Point …

Reliability Of Feqdrain For Modeling Performance Of Sand Treated With Large-Diameter Prefabricated Drains For Liquefaction Mitigation, Travis Hatch Meservy

Theses and Dissertations

Finite element modeling of laminar shear box testing that consisted of loose sand treated with large diameter prefabricated vertical drains (PVDs), was performed. The objective of the modeling was to evaluate the reliability of the computer program FEQDrain for predicting excess pore pressure ratios (Ru) at sites treated with prefabricated drains. FEQDrain was found to be capable of successfully modeling measured excess pore pressure ratio time histories from the laminar shear box experiment, as long as an appropriate combination of €˜number of equivalent cycles and €˜shaking duration was chosen, and sensitive parameters were in the range of measured values. Hydraulic …

Managed Containers For Increased Cyber-Resilience, Xavier J. Merino Aguilera

Theses and Dissertations

Traditional defense mechanisms are no longer adequate in protecting critical infrastructure and mission critical systems. These systems require to be always-on-always-connected. High availability and data integrity become crucial to deliver their mission. Unable to guarantee uncompromisable security and given that systems will inevitably be attacked, we must change our goals to guarantee mission survivability, the ability of the system to fight through the attack. Previous work has been done to increase availability and integrity using virtual machines. We move away from virtual machines towards Linux containers and implement resiliency strategies to guarantee stateful system recovery after an attack. The goal …

A Heuristic Method For The Determination Of Assembly Network And Line Design For Discrete Manufacturing Processes, Ismael Hernan Naranjo Velez

Theses and Dissertations

This paper presents with a proposed alternative precedence algorithm which is determined by the Solid surfaces of the product design. The representation address in this paper address the manufacturing planning from all manufacturing levels of the product. Sequence is introduce to this paper in order to proof the propose precedence network alternatives. Both manufacturing level solutions are heuristic. This thesis explores the connection of the precedence and the sequence, as it introduces physical manufacturing constraints and its relationships to the station process planning. Precedence network are usually determine by the designer principal point and assembled connections. The proposed algorithm avoids …

Comparison Of Reference Signal Received Power Measurements Between Cell Phone And Scanning Receiver In Lte, Sahin Gullu

Theses and Dissertations

In cellular technology, before giving service to customers, coverage estimation, network optimization, and maintenance rely on RSRP (Received Signal Reference Power) measurements that are collected in a given area. This measurement collection is called “drive test or drive testing” that is very common practical experiment for RF engineers. These measurements are usually recorded by a professional receiver or a professional phone with appropriate software and license. A scanning receiver, PCTEL SeeGull EX scanning Receiver in this thesis, is a common professional tool for RF engineers to collect data. A cell phone, HTC One M7 for this experiment, has an appropriate …

The Influence Of Varying Fiber Stacking Sequence On The Tensile, Impact, And Water Absorption Properties Of Unidirectional Flax/E-Glass Fiber Reinforced Epoxy Composite, Mohammed F. Al-Edhari

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis includes the study of the mechanical performance of two different types of fibers reinforced hybrid composites. Two kinds of fibers, natural fiber (flax) and synthetic fiber (E-glass), are used to reinforce epoxy resin. To evaluate the effective properties of the hybrid composites, a micromechanical analysis of the structure genome (SG) of a unidirectional fiber hybrid composites is performed using nite element analysis (FEA). Both fibers are assumed to be circular and packed in a hexagonal pattern. The effects of varying volume fractions and fiber locations, of the two fibers, on the elastic properties of the hybrid composites are …