Engineering Commons^™

Flexural Behavior Of Thermoplastic Beams With And Without Frp Reinforcement, Hilmi Coskun

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the results of an experimental and theoretical study of the flexural behavior of thermoplastic beams with and without fiber-reinforced plastic (FRP) rebars. Tests are conducted on commercially available thermoplastic beams known as Seatimber. The normal stress-strain relations of both the thermoplastic material and FRP rebars are obtained in tension and compression experimentally. These mechanical property curves are then used as part of the input for developing the theoretical moment-curvature relations using an iterative equilibrium procedure. The moment-curvature relations are in turn used for predicting the beam load-deflection curves via the central finite-difference procedure. Behavior predictions are made …

Selective Cvd Growth Of Diamond Crystals On Tungsten, Charles Randal Cole

Electrical & Computer Engineering Theses & Dissertations

Typical field emitters consist of sharp metal tips which usually have a short life due to erosion and contamination. To improve the performance of regular field emitters, diamond can be placed on the emitter tip. This is done by selectively growing diamond on tungsten tips using chemical vapor deposition (CVD) processing. Diamond exhibits negative electron affinity, so that electrons will be emitted by properly biasing the tip.

To obtain single crystal growth right at the tip, a cantilever controlled nucleation method was developed which worked better than other methods. Surface preparation was also important to the growth process. An oxide …

Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr

Materials Science and Engineering Faculty Research & Creative Works

Glass ribbon-reinforced transparent polymer composites which provide excellent optical transparency and a low distortion level over a wide temperature range while exhibiting superior mechanical properties as compared to non- reinforced polymer counterparts, and equivalent properties as compared to glass fiber-reinforced counterparts.

Optimization Of Microstructure Development During Hot Working Using Control Theory, James C. Malas Iii, W. Garth Frazier, S. Venugopal, Enrique A. Medina, Steven Madeiros, Raghavan Srinivasan, R. Dennis Irwin, W. M. Mullins, Anil Chaudhary

Mechanical and Materials Engineering Faculty Publications

A new approach for controlling microstructure development during hot working processes is proposed. This approach is based on optimal control theory and involves state-space type models for describing the material behavior and the mechanics of the process. The effect of process control parameters such as strain, strain rate, and temperature on important microstructural features can be systematically formulated and then solved as an optimal control problem. This method has been applied to the optimization of grain size and process parameters such as die geometry and ram velocity during the extrusion of plain carbon steel. Experimental results of this investigation show …

Corrosion Behaviour Of Copper Covered With Ion Selective Phenolic Coatings By Eis, Zhoucheng Wang, Yingzhou Zhang, Shaomin Zhou

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS) technique was employed to study the corrosion behaviour of copper painted with the anion selective, cation selective and bipolar phenolic coatings in 3% NaCl solution. From the impedance spectrum characteristics, the models of equivalent circuit for these different coating systems were established, and the methods for the analysis of experimental impedance diagrams in terms of coating and interface properties were discussed. The research results show that the composition and structure of ion selective coatings have significant influence on corrosion behaviour of copper. The bipolar coating consisting of an anion selective inner layer and a cation selective outer …

Preparation Of Pbo2/Ti Plate Electrode, Zhigang Shao, Baolian Yi, Xinge Zhang, Enjun Zhang

Journal of Electrochemistry

The perchlorate was made up of a lead dioxide plate elcetrode and an oxygen cathode. By measuring the flow capacity of cell gas in the cell, and by means of CV, SEM, XRD, the performances of the lead dioxide plate electrodes are evaluated. The influence of changes in the concentrations of electroplating solutions (F, HNO₃, Bi³⁺, Ni²⁺, Fe³⁺ and surface active agent) is investigated. The results show that the concentrations of Fe³⁺ in the solutions must be lower 0.01 g/L, and the concentrations of HNO₃ in the solutions are about 20 …

Study On The Diffusion Of Electroactive Molecules In Polymer Electrolyte By Microelectrode Voltammetry, Liming Ding, Shaojun Dong, Erkang Wang

Journal of Electrochemistry

The ten years study on the diffusion of electroactive molecules in polymer electrolyte by microelectrode voltammetry was reviewed by considering the development background of polymer electrolyte materials. The classification, fabrication, applications and electrochemical measurements of microelectrode were introduced concisely. The several important factors influencing the diffusion of electroactive molecules were stressed. In the final part of this paper, some new reports on the diffusion of labeled molecules were introduced.

Electrocatalytic Oxidation Of Methanol On The Stearate Nickel L-B Film, Benzeng Hua, Wenyan Hu, Yanzhen Chen, Yanhong Zhang

Journal of Electrochemistry

The stearate nickel L-B films is good electroacatlyst for the oxidation of methanol MeOH in alkaline. The electrochemical behaviors of stearate nickel L-B films is affected by the concentration of KOH. The rate of quantity of mickel ion and stearic acid in L-B films is 1∶1, which means that the nickel ion may exist in -COONi(OH) form. The electrocatalytic process is influenced by the concentration of OH^-, it involves the penetration of MeOH into the films. The oxidative currents of MeOH are linearly dependent on the bulk concentration.

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅲ. Improvement Of Artificially Imposed Solid Electrolyte Film On Cell Performance, Shuhua Ma, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The improving effect of solid electrolyte film artificially imposed on carbon electrode was investigated. The result showed that both the charge/discharge capacity and first charge/discharge efficiency, to a certain extent, were enhanced, and the result also suggested the effectiveness of the substitution of the artificially imposed solid electrolyte film for the inherent passivating film which was formed on the surface of the carbon electrode while inserted in the electrolyte during charging or discharging. The Scanning Electron Microscope result displayed the compact and well-defined morphology of the artificially imposed crystalline film.

Investigation On Electro Reduction Behaviour Of Copper Anodic Products In Concentrated Naoh Solutions Ⅱ. Electro Reduction Of Cu(Ⅱ) Products, Jianbo He, Hanhe Chen, Jianxin Lin

Journal of Electrochemistry

Potentiostatic oxidation potentiodynamic or galvanostatic reduction methods have been used to study the cathodic reduction behaviour of various products anodically formed on the second stage of copper oxidation in concentrated NaOH solutions. Seven cathodic current peaks and the corresponding cathodic potential plateaus are observed on the potentiodynamic E/i curves and the galvanostatic E/t curves, respectively. In the negative potential scan, there are three couples of voltammetric peaks which have been attributed to the formation and reduction of CuO, Cu(OH)₂ and Cu(Ⅱ) ion, respectively. The complicated mechanism for the electro formation of the three Cu(Ⅱ) species are discussed.

Studies On The Failure Modes Of Stationary Vrla Batteries, Yibo Tong, Xiangming Qiu

Journal of Electrochemistry

In order to improve the reliability and the quality of stationary valve-regulated lead-acid (VRLA) batteries, the failure modes of the stationary VRLA batteries which caused by the water loss and the thermal runaway are studied. The water loss may be solved by increasing the Oxygen-recombination efficiency, choosing the suitable grid material and the additives of megative paste, decreasing the corrosion of the positive plates. The thermal runaway may be solved by decreasing the inner ohmic resistance of VRLA batteries, improving the outside condition of batteries such as putting into the absorbing-heat material between the abtteries etc..

Preparation And Examination Of Planar Type Solid Oxide Fuel Cells, Yi Jiang, Jingwang Yan, Shizhong Wang, Chunying Yu, Wenzhao Li

Journal of Electrochemistry

The solid oxide fuel cells of planar type (SOFC) have been developed after successfully preparing La_0.8Sr_0.2MnO₃ cathodes and Ni-YSZ ceramic anodes on YSZ plates and solving the high temperature sealing technical problem. Examination of the single cells fabricated showed that the maximum power output at 950 ℃ for H₂ as fuel and air as oxidant reached 0.12 W/cm². It was found that the large polarization overpotential of the Ni-YSZ anode and the Ohmic losses of the cells were two main factors responsible for the relative low output power density.

Electrorheological Characters Of Polyaniline Suspensions, Guangyao Su, Deshu Gao, Changqing Zhang

Journal of Electrochemistry

Polyaniline (PAn) as the dispersive particles and insulating oil as the dispersive medium, the electrorheological fluid (ERF) is constituted. Relations between the factors of electric field strength (E), temperature (T) and the static yield stress (τ_S), current density (i) of ERF are investigated. The results show that the changes of τ_S and i with electric field intensity have emerged in the exponential relation, i.e, τ_S∝E^0.7, i∝E^2.18. Otherwise, when exert a constant voltage on ERF, owing to the polarization, the absorption of medium of ERF have taken place. Therefore, the attenuation rate …

Behavior Of Copper In Hydrogen Storage Alloy Microencapsulated By Copper, Dawei Zhang, Huatang Yuan, Huabin Yang, Zuoxiang Zhou, Yunshi Zhang

Journal of Electrochemistry

Negative electrode made from Cu microencapsulated hydrogen storage alloy was studied by using cyclic voltammetry method. The results showed that copper as a coating material was of a certain stability in 5 mol/L KOH solution within the range of charge and discharge voltage. But when expanding the sweep voltage, the CV curve showed a pair of distinct oxidation reduction current peaks of Cu₂O formation at E = -0.3 V and Cu₂O reduction at E =-0.6 V. With charging discharging cycles, copper is liable to be oxidized to Cu₂O and further oxidized into CuO_{2 …}

The Electrochemical Behavior And Deposited Mechanism Of Zn-Ni Alloy Codeposition, Jixun Wu, Yongqin Liu, Huimin Meng

Journal of Electrochemistry

The electrochemical behavior of Zn-Ni alloy codeposition and concomitant hydrogen evolution have been studied in the chloride ammonia solution through the d-c electroplating method. Under the condition of the applied cathodic current density of 2A/dm² , the AC impedance spectra have been measured. An equivalent circuit has been presented for the impedance study on the alloy codeposition.

The Electrode Process Of Some Organic Dyes Studied By Spectroelectrochemical Technique In Situ, Yinxuan Tang, Hangsheng Yang, Baoen Shen

Journal of Electrochemistry

Spectroelectrochemistry especially with in situ measurement in a cell provides a very useful mthodology for measuring the parameters of electrode process. In this paper, we report the determination of formal potentials, the number of electron transfer, the diffusion coefficient, the heterogeneous electron transfer rate constant and the transfer coefficient of some organic dyes (Methyelene blue, Neutral red, Indigo carmine) using spectroelectro chemical technique in situ.

Orientation Relationships In The System Nb-Nbcr2, P. G. Kotula, Katherine C. Chen, Dan J. Thoma, F. Chu, T. E. Mitchell

Materials Engineering

No abstract provided.

39th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Preliminary program and registration information for the 39th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 3-7, 1997.

Fabrication, Structure, Properties And Workability Of Al 2024/Sic Particulate Composites, Renee Naim Aziz

Archived Theses and Dissertations

[abstract not provided]

Fabrication, Structure, Properties And Workability Of Al 2024/Sic Particulate Composites, Renee Naim Aziz

Archived Theses and Dissertations

No abstract provided.

Gallium Desorption Behavior At Algaas/Gaas Heterointerfaces During High-Temperature Molecular Beam Epitaxy, K. Mahalingam, D. L. Dorsey, K. R. Evans, Rama Venkat

Electrical & Computer Engineering Faculty Research

A Monte Carlo simulation study is performed to investigate the Ga desorption behavior during AlGaAs-on-GaAs heterointerface formation by molecular beam epitaxy. The transients in the Ga desorption rate upon opening the Al shutter are shown to be associated with the concurrent reduction in the V/III flux ratio. Monte Carlo simulations employing a constant V/III flux ratio yield a “steplike” variation in the Ga desorption rate with the resulting interfaces closer in abruptness to the ideal AlGaAs-on-GaAs interface. Further details on the stoichiometry of the interface and its relationship with predicted Ga desorption profiles is presented.

Experimental Investigation Of Nonlinear Dynamics In Single Mode Semiconductor Laser Diodes With Phase Conjugate Feedback, Gordon T. Hengst

Theses and Dissertations

The semiconductor laser diode offers a unique system to investigate nonlinear dynamics when optical feedback is applied. Although there is extensive research of laser diodes with optical feedback from normal dielectric mirrors, very little has been done experimentally to analyze the effects of degenerate phase conjugate feedback from a BaTiO₃ crystal. This research experimentally investigated the dynamics of a single-mode laser diode with weak phase conjugate feedback using both the self-pumped and double phase conjugate geometries. The experimental results validated a mathematical model which numerically evaluates the Lang-Kobayahsi coupled differential equations. The model simulated the nonlinear behavior of a …

Strip Casting With Fluxing Agent Applied To Casting Roll, Robert S. Williams, Ronald J. O'Malley, Richard C. Sussman

Materials Science and Engineering Faculty Research & Creative Works

A strip caster (10) for producing a continuous strip (24) includes a tundish (12) for containing a melt (14), a pair of horizontally disposed water cooled casting rolls (22) and devices (29) for electrostatically coating the outer peripheral chill surfaces (44) of the casting rolls with a powder flux material (56). The casting rolls are juxtaposed relative to one another for forming a pouting basin (18) for receiving the melt through a teeming tube (16) thereby establishing a meniscus (20) between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed …

Dyna3d Simulations Of Low-Speed Impact Response Of Laminated Composite Panels, Kenneth William Barlow

Mechanical & Aerospace Engineering Theses & Dissertations

Low-speed impact response of laminated composite panels is simulated without material damage using the DYNA3D finite element analysis code. The DYNA3D code is a nonlinear transient dynamics simulation tool with a contact algorithm for impact. By gaining a more comprehensive understanding of this dynamic impact event, this work is meant to contribute to improving designs for damage tolerance and residual strength by providing modeling and analysis guidelines for the analyst.

Structural modeling of the laminate and the impact event are found to be important factors for the analyst to consider. Since DYNA3D uses an explicit formulation, problem size is constrained …

A Piezoresistive Metal Thin Film Tilt Sensor, Todd Allan Lindley

Electrical & Computer Engineering Theses & Dissertations

Thin film strain gauges have many applications as transducers for monitoring pressure, vibration, and acceleration. In this thesis, a simple system, consisting of a Nichrome thin film strain gauge deposited on a glass substrate, is investigated in detail. Finite element analysis is used to model the expected sensor behavior. The substrate is shaped to exhibit a constant strain distribution, and is set up in a cantilever beam configuration. R. F. sputtering is used to deposit the Nichrome film, and the resistor pattern is transferred via photolithography. The gravitational force on a mass attached to the free end of the sensor …

Fabrication And Mechanical Properties Of Aluminium Composite Duplex Alloys By Semisolid Forming, Merhane Mohamed Kamel

Archived Theses and Dissertations

No abstract provided.

Gfrp External Strengthening Of Structural Concrete, Tarek Mohamed Nabil Fathy Rizk

Archived Theses and Dissertations

No abstract provided.

Chromatographic Separation Apparatus, Lynn S. Penn, Donna L. Scott, Howard H. Weetall, Anne L. Plant, Marion F. Mccurley, Scott A. Glazier

Chemical and Materials Engineering Faculty Patents

An apparatus for the monitoring of a column chromatography separation process includes a segmented column with a seal positioned at the joint defined by the segments of the column. A connector is provided for connecting the segments of the column together. The apparatus further includes a sensor for monitoring an analyte in an eluant within a separation zone of the column. The sensor includes a mesh grid made of optical fibers or metal wires which is placed so as to extend through the separation zone of the column. The metal wires or optical fibers extend through the seal of the …

Aluminum Nitride-Compatible Thick-Film Binder Glass And Thick-Film Paste Composition, Douglas M. Mattox

Materials Science and Engineering Faculty Research & Creative Works

Mixed alkaline earth boroaluminate glasses comprising BaO combined with at least one of CaO, SrO and MgO. The glasses are useful as frit binders in aluminum nitride- compatible, thick-film paste compositions used in thick-film printing of hybrid microelectronic circuits on aluminum nitride substrates.

Thickness Effects On A Cracked Aluminum Plate With Composite Patch Repair, Joel J. Schubbe

Theses and Dissertations

Post-repair fatigue crack growth was investigated in 3.175, 4.826, and 6.35 mm thick aluminum panels asymmetrically repaired with boron/epoxy composite patches bonded to the plates with FM73 sheet adhesive. Patches were uniaxial with patch to panel stiffness ratios ranging from 0.46 to 1.3. Experimental fatigue tests were carried out at 120 MPa, R=0.1, and 10 Hz (sinusoidal) to measure patched and unpatched face crack lengths, center crack opening displacements, and selected strains. Crack growth data was acquired using optical, eddy current, and post-test analysis methods. Crack growth rates were calculated using the incremental polynomial method. A three-layer Mindlin plate finite …