Engineering Science and Materials Commons^™

Single Fiber Mechanical Properties Using Nano-Tensile Testing And Carbon Fiber Structure-Property Relationship, Matthew Erich Kant

Doctoral Dissertations

Single carbon fibers are studied using a nano-tensile testing system. This system has unprecedented load and displacement resolution, nN and nm respectively, and the ability to perform dynamic testing for storage and loss modulus during quasi-static tensile extension. Furthermore, improved fiber mounting and alignment procedures coupled with the precision of the nano-tensile testing system assist in unprecedented resolution in single fiber mechanical testing for axial modulus and strength. Hence, using these unique capabilities, the moduli and their statistical distribution of many high performance carbon fibers are reported here. From this, a simplified single parameter model describing the strain dependent modulus …

Spectroscopic Investigation Of The Chemical And Electronic Properties Of Chalcogenide Materials For Thin-Film Optoelectronic Devices, Kimberly Horsley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials.

For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These …

Effects Of Transportation Hazards On Package Performance And Food Product Shelf Life, Kyle Dunno

All Dissertations

This research studied the effect of transportation hazards on food product shelf life and package performance. Studies were conducted to determine the effect of package headspace volume, product viscosity and storage temperature on package integrity. Finally, accelerated shelf life testing (ASLT) was utilized to determine how simulated transportation hazards affected the shelf life of a specific food product. Institutional retort pouches containing either water or 5% starch solution were filled with varying amounts of headspace volume to determine if package headspace volume could aid in package performance during simulated engineering tests for packaged products. Fixed displacement vibration testing and compression …

The Effects Of Chlorine Dioxide Gas On The Sensory Properties Of Whole Tomatoes, Christopher Gottilla

All Theses

This experiment sought to measure the changes in sensory quality that occur in tomatoes as the result of chlorine dioxide gas treatment. Tasti-Lee tomatoes (VFFF Hybrid #5755) were treated with two different levels of chlorine dioxide gas (10mg and 50mg of ClO2-forming material per kg of tomato) utilizing sachets. Testing compared the treated tomatoes and an untreated control group. These tests included flat-plate compression for firmness, sensory evaluation using a difference from control test, color analysis of the skin and flesh using a colorimeter, and enumeration of aerobic microbes and yeasts and molds. Flat-plate compression of whole tomatoes revealed no …

Combining Modified Atmosphere Packaging And Nisin To Extend The Shelf Life Of Atlantic Salmon (Salmo Salar), Dong Han

All Theses

Atlantic salmon is often used in laboratory experiments to represent marine fishes. Many researchers try to optimize the levels and dosage of preservatives to maintain the freshness and extend the shelf-life of Atlantic salmon. Little information has been provided about the effectiveness of combined method between MAP and nisin, especially on the preservation of Atlantic salmon. Strong evidences suggest that MAP associated with nisin may have a potential to improve Atlantic salmon storage quality. Preservation effectiveness of combining modified atmosphere package (MAP) and nisin on fresh Atlantic salmon was determined using various methods. Six groups of farmed Atlantic salmon were …

Microanalysis Of Polymer Chain Diffusion In Heat Seals, Russell Cooper

All Theses

Heat sealing is an integral method for the closure and protection of packaging. Previous work has shown that seal strength is developed by the interdiffusion of polymer chains within heat seals. Heat seals were made between two dissimilar materials. Poly(ethylene-co-acrylic acid) (EAA) was heat sealed to ionomer. Diffusion within the EAA-ionomer heat seals was estimated. The diffusion estimates were then related to resulting seal strength in the EAA-ionomer sealant system. Heated tooling sealing was utilized to make heat seals at 40 psi (275.79 kPa), 0.5 seconds, and a range of temperatures between 180˚F (82.22˚C) and 300˚F (148.89˚C). Scanning electron microscopy …

Printing Functional Electronic Circuits And Components, Ahmed Tausif Aijazi

Dissertations

The purpose of this study was to investigate the challenges in printing reliable multilayer flexible circuits, devices and components. Gravure was used as the primary printing process for this work, but due to some limitations of gravure, other printing methods were also investigated. At first a systematic study was done to determine the optimum parameters for the gravure printing of sub 50 micron lines. Commercially available silver nanoparticle inks were printed on a lab scale gravure printer, Accupress®. The highest resolution line that was electrically conductive was 36μm wide. The 9μm, 18μm and 27μm lines were printed but were not …

Relationship Between Peel Force, Opening Force, And Burst Force For A Semi-Rigid Cup And Lid, Pre- And Post-Retort, Raj Navalakha

All Theses

This research determines if there is any relationship between the peel force, the opening force and the burst force for a semi-rigid cup and lid system, for pre- and post-retort conditions. It also compares the relationship (regression lines) between these forces pre- and post-retort. These seal results were studied by varying the sealing parameters of dwell time and temperature while keeping the pressure constant. Polypropylene cups and a peelable barrier retort lidding were used in this study. As compared to past research, a different peel testing technique was used to measure the peel and the opening force. The entire lid …

High Strength Steel Fiber Reinforced Flow-Able Or Scc Concrete With Variable Fiber By Volume Fractions For Thin Plate And Shell Structures, Abebe Berhe

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to incorporate discrete, short, mechanically deformed, small diameter steel fibers into high strength concrete with f'c > 70 MPa (10 ksi) in an attempt to reduce and partially eliminate the need for steel rebar in concrete construction. By introducing steel fibers to high strength concrete mixture, the overall tensile, compressive and shear strength of the mixture can be improved immensely thus, replacing portions or major parts of the longitudinal, temperature and shrinkage reinforcements. The reduction or elimination of longitudinal and transverse reinforcements in the construction of structural or non-structural members can result in savings in …

Primary Creep In Astm A325 Bolts Under Simulated Fire Loading, Mohammad Matar

Theses and Dissertations

At room temperature, small creep effects are present on steel structures. This is not the case at fire condition where the temperature is much higher than room temperature; in this case creep can be significant, and should be taken into consideration. Since fire hazard can happen in any building, creep effect must be taken into consideration when designing a building. Creep strain behaves as a function of time, temperature and stress. As the temperature increases, the creep strain increases. Similarly, the longer the temperature at a given stress on the structure, the more the creep strain present.

The smallest component …

Studies On The Wrinkling Of Thin Polymer Films Floating On Liquid, Kamil B. Toga

Doctoral Dissertations

This dissertation aims to broaden our understanding on wrinkling instabilities occurring on floating polymeric sheets, and tries to establish innovative methods that exploit these patterns in studies on material behavior and interfacial phenomena. We will address three major topics in this thesis including, i) characterization of the conditions required to buckle an annular disc, ii) characterization of wrinkles occurring around a droplet/bubble placed on a membrane that is kept taut at the liquid-air interface, and iii) using wrinkling patterns as a probe to understand the interfacial behavior and dynamics of ultrathin films. The first project in this thesis is about …

Design Of Well-Defined Mesoporous Silicas Via Surfactant Templating Method Enhanced By The Use Of Swelling Agents, Tiffany Man

Dissertations, Theses, and Capstone Projects

Surfactant-templated ordered mesoporous materials continue to attract tremendous attention as these materials are characterized by reproducibility and predictability of their synthesis as well as their wide range of potential applications, which serve as future opportunities for additional advancement. The main purpose of this dissertation is to advance the understanding how to control the structural features and properties in the synthesis of well-defined porous materials via surfactant templating method, while keeping in mind that the uniformity of pore size and structural ordering are essential characteristics for these well-defined materials. The work was primarily focused on the issue of the unit-cell size …

Synthesis And Evaluation Of Sensitizer Drug Photorelease Chemistry: Micro-Optic Method Applied To Singlet Oxygen Generation And Drug Delivery, Goutam Ghosh

Dissertations, Theses, and Capstone Projects

This thesis summarizes a new micro-optic method for singlet oxygen generation and sensitizer drug delivery, which include i) synthesis and evaluation of a first generation device for drug delivery from native and fluorinated silica probe tips, ii) synthesis of PEG conjugated sensitizers to study phototoxicity in ovarian cancer cells, and iii) synthesis and evaluation of tris-PEGylated chlorin conjugated fluorinated silica for its future integration into the device to use as a 2nd generation device. A first generation micro-optic device was developed that works by sparging O2 gas and light generating cytotoxic singlet oxygen that cleaves the covalently attached drug (sensitizer) …

Characterization Of Wide Band Gap Semiconductors And Multiferroic Materials, Bo Cai

Dissertations, Theses, and Capstone Projects

Structural, optical and electrical properties of zinc oxide (ZnO), aluminum nitride (AlN), and lutetium ferrite (LuFe₂O4) have been investigated. Temperature dependent Hall Effect measurements were performed between 80 and 800 K for phosphorus (P) and arsenic (As) doped ZnO thin films grown on c-plane sapphire substrate by RF magnetron sputtering. These samples exhibited n-type conductivity throughout the temperature range with carrier concentration of 3.85 × 10 ¹⁶ cm^-3 and 3.65 × 10 ¹⁷ cm^-3 at room temperature for P-doped and As-doped ZnO films, respectively. The Arrhenius plots of free electron concentration of those doped samples showed …

Synthesis, Fabrication And Characterization Of Magnetic And Dielectric Nanoparticles And Nanocomposite Films, Xiaohua Liu

Dissertations, Theses, and Capstone Projects

Materials science is an interdisciplinary field investigating the structure-property relationship in solid-state materials scientifically and technologically. Nanoscience is concerned with the distinctive properties that matter exhibits when confined to physical dimensions on the order of 10^-9 meters. At these length scales, behaviors of particles or elaborate structures are often governed by the rules of quantum mechanics in addition to the physical properties associated with the bulk material.

The work reported here seeks to employ nanocystals, binary nanocomposites and thin films of materials, to build versatile, functional systems and devices. With a focus on dielectric, ferroelectric, and magnetoelectric performance, a …

The Effect Of Fixation Plate Length On Spinal Instability Following Anterior Cervical Plate Fixation For The Repair Of In Vitro Flexion-Distraction Injuries, Abdulaziz J. Al-Kuwari

Electronic Thesis and Dissertation Repository

Abstract:

The Effect of Fixation Plate Length on Spinal Instability Following Anterior Cervical Plate Fixation for the Repair of in Vitro Flexion-Distraction Injuries

Introduction: Anterior cervical decompression and fusion with a plate (ACDFP) is a commonly performed treatment following a traumatic injury to the subaxial cervical spine. The purpose of the presented work was to determine the biomechanical effect of plate length on cervical spine kinematic stability following ACDFP stabilization for a simulated traumatic injury.

Methods: Eleven fresh-frozen cadaveric C5-C6 and C6-C7 motion segments were examined in this study. To assess kinematics, flexibility testing was performed on each specimen …

Size-Dependent Electroelastic Properties Of Piezoelectric Nanoplates, Zhengrong Zhang

Electronic Thesis and Dissertation Repository

With the development of nanotechnology, piezoelectric nanostructures have attracted a surge of interests in research communities for the potential applications as transistors, sensors, actuators, resonators and energy harvesters in nanoelectromechanical systems (NEMS) due to their high electromechanical coupling and unique features at the nano-scale. Piezoelectric nanomaterials have been characterized to possess size-dependent electromechanical coupling properties from both experimental and theoretical perspectives. Therefore it is of great importance to investigate the physical mechanisms of these distinct nano-scale structure features in order to fulfill the design and application of those piezoelectricity-based nanodevices.

Due to large surface to volume ratio and manifest strain …

Micromechanics Modeling Of The Electrical Conductivity Of Carbon Nanotude (Cnt)- Polymer Nanocomposites, Chuang Feng

Electronic Thesis and Dissertation Repository

The addition of carbon nanotubes (CNTs) in polymers to form conductive composites has been attracting great interest from research and industry communities due to their potential applications. Experiments and simulations have demonstrated that the addition of a very small amount of CNTs into polymers can significantly improve the electrical conductivity of the composites. Such significant improvement in the electrical conductivity is attributed to two conductivity mechanisms: nanoscale electron hopping and microscale conductive networks. Understanding and prediction of the overall electrical conductivity of the composites with the incorporation of the conductivity mechanisms that underpin the macroscopic electrical properties are essential for …

Integrating 3d Layered Manufacturing With Photonic Sintering, Precision Machining And Smart Coating Techniques For Rapid Casting Applications, Hemant Bohra

Dissertations

Developments in rapid casting technologies have led to a new era of inclusion of 3D printing. Three-Dimensional (3D) printing provides the flexibility and ease of reproducing a sand mold directly from CAD models, eliminating patterning steps, thus reducing the process time for creating prototypes. In addition to minimizing processing steps, 3D printing provides the advantages of higher precision and the ability to produce complex shaped sand molds, but it simultaneously possesses some limitations and concerns related to throughput, safety and logistics.

This study proposes an alternative method for creating sand molds by introducing a hybrid rapid prototyping approach to overcome …

Self-Supported Printed Multi-Layer Capacitors, Michael James Joyce

Masters Theses

The increasing demand for miniaturized electronic devices has increased the need for rechargeable micro-power sources. Although lithium and lithium ion batteries have been utilized in these applications since the late 1990s, other energy harvesting technologies, such as thermal, mechanical, and solar, are now being used to augment batteries to enable systems to be self-powered. However, the lifetime of any battery is finite, which may be a major problem when the application is in a permanent structure or medical implant device. For power or significant energy storage applications, printed multilayer capacitors or supercapacitors are being explored as an enhancement, or replacement …

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …

Analytical And Experimental Analysis Of Magnetorheological Elastomers, Sarah Trabia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many engineering applications ranging from robotic joints to shock and vibration mitigation can benefit by incorporating components with variable stiffness. In addition, variable stiffness structures can provide haptic feedback (the sense of touch) to the user. In this work, it is proposed to study Magnetorheological Elastomers (MRE), where iron particles within the elastomer compound develop a dipole interaction energy, to be used in a device for haptic feedback. A novel feature of this MRE device is to introduce a field-induced variable shear modulus bias via a permanent magnet and using a current input to the electromagnetic control coil to change …

Characterization Of Carbon-Fiber Reinforced Polyetherimide Thermoplastic Composites Using Mechanical And Ultrasonic Methods, Mohannad A. Alhaidri

Theses and Dissertations

Continuous fiber-reinforced thermoplastics (CFRT) have the potential for being a mass-produced material for high-performance applications. The primary challenge of using CFRT is achieving fiber wet-out due to the high viscosity of thermoplastics. This results in higher temperatures and pressures required for processing the composites. Co-mingling thermoplastic fibers with a reinforcing fiber, potentially, can enable better wetting by reducing the distance the matrix needs to flow. This could result in shorter cycle times and better consolidation at lower temperatures and pressures. In this study, a polyetherimide (PEI) fiber was comingled with carbon fibers (CF). The resultant fibers were woven into fabrics …

Mechanistic Failure Criterion For Unidirectional And Random Fibre Polymer Composites, Jamaloddin Jamali

Electronic Thesis and Dissertation Repository

Polymer composite design in energy absorbing components requires a failure criterion that can predict the energy involved in its fracture under different modes of loading. Present mixed mode criteria are mainly empirical or semi-empirical, and are only suitable for a small range of composite types.

The purpose of this study was to develop a mechanistic failure criterion that is applicable to a wide range of polymer composites. An energy based mechanistic failure criterion is proposed to characterize the toughness of unidirectional (UD) and randomly oriented short fibre composites (random fibre composites).

In UD and random composites, the criterion predicts the …

Metal Nanoparticles Immobilized On Basic Supports As Catalysts For Hydrogenation And Dehydrogenation Reactions Of Relevance To Cleaner Fossil Fuels And Alternative Sources Of Energy, Reena Rahi

Dissertations, Theses, and Capstone Projects

We developed a series of catalysts, composed of metal nanoparticles immobilized on basic supports for the hydrogenation of heteroaromatics of relevance to cleaner fossil fuels and biodiesel, and for the dehydrogenation of heteroaromatics of relevance to hydrogen storage in organic liquids. Our catalyst design involves nanostructured catalysts composed of metal particles immobilized on basic supports capable of ionic mechanism that may avoid catalyst poisoning and enhance catalytic activity.

We prepared a new catalyst composed of Pd nanoparticles immobilized on MgO by NaBH4 reduction of Na2PdCl4 in methanol in the presence of the support. TEM measurements revealed well-dispersed 1.7 nm Pd …

Modification Of A Draw Bar Type Arena Harrow To Three Point Mounted Type Harrow, Clayton Alan Brown

BioResource and Agricultural Engineering

This senior project will be the design, and construction of a three point hitch to be attached to a draw bar type spike tooth harrow. Currently used by the Cal Poly Rodeo Team to cultivate their arena before performances, and practices.

The attachment will allow the harrow to be pulled in both directions to create different types of soil affects.

Also the fabrications has a minimal budget so the majority of the materials will be scrap material already in position of the rodeo team or donated to the project.

Lightweight Uav Launcher, Ben Miller, Christian Valoria, Corinne Warnock, Jake Coutlee

Mechanical Engineering

This report discusses the design, construction, and testing of a lightweight, portable UAV launcher. There is a current need for a small team of soldiers to launch a US Marine Tier II UAV in a remote location without transport. Research was conducted into existing UAV launcher designs and the pros and cons of each were recorded. This research served as a basis for concept generation during the initial design development stage. It was required that the design weigh less than 110 lbs, occupy a smaller volume than 48" x 24" 18" in its collapsed state, be portable by a single …

A Novel Silica-Based Nano Pigment As A Titanium Dioxide Replacement, Ryan Stoneburner

Masters Theses

This research focused on the evaluation of a new Silica-based pigment for the replacement of titanium dioxide (TiO₂) in paperboard coatings. The silica-based pigment has shown the ability to be a replacement in terms of functionality and runnability. TiO₂ is currently the highest opacifying pigment used in paper coatings, but it is also the most costly. Finding a less expensive pigment that doesn't reduce effectiveness is critical to reducing the cost of TiO₂ formulations. To evaluate the new pigment, coatings will be applied using a Cylindrical Laboratory Coater (CLC) with varying amounts of TiO₂ and …

Handloaded Rifle Ammunition: A Look Into The Assembly Process, Load Development Methods, And Its Comparison To Factory Ammunition, Jeffrey Dalton Snyder

Senior Theses

The purpose of this thesis is to educate the reader on the appeal of assembling firearm ammunition from its individual components, a process known as “handloading,” in comparison to factory assembled ammunition. This is accomplished by providing the reader with the benefits of handloading with an overview of the handloading process. Then, an example of a handload development method (Ladder Test) is discussed and performed. The results from the test are then analyzed and explained. Finally, the handloaded ammunition from the test is compared by function and price to factory ammunition from three different market segments.

The project portion of …

Nanolayer Polymeric Coatings To Enhance The Performance And Service Life Of Inorganic Membranes For High Temperature-High Pressure Biomass Pretreatment And Other Applications, Vincent C. Kandagor

Doctoral Dissertations

Membrane technology has become increasingly attractive in several applications including water filtration, food industry, oil and gas, and biomedical applications. Most recently the quest for renewable, bioenergy has called for use of membranes in biomass pretreatment and other stages of producing biofuel. The success and advancement of the membrane technology for these various applications has, however, been impeded by the fouling of membranes, which causes the pores in the microporous structure to block, resulting in reduced efficiency, and in some cases, total failure of the membranes system. This challenge leads to a tremendous increase in the cost of using membranes …