Engineering Commons^™

Prediction Of Effective Permittivity Of Diphasic Dielectrics Using An Equivalent Capacitance Model, Sandeep K. Patil, Marina Koledintseva, Robert W. Schwartz, Wayne Huebner

Electrical and Computer Engineering Faculty Research & Creative Works

An analytical model based on an equivalent capacitance circuit for expressing a static effective permittivity of a composite dielectric with complex-shaped inclusions is presented. The dielectric constant of 0-3 composites is investigated using this model. The geometry of the capacitor containing a composite dielectric is discretized into partial parallel-plate capacitor elements, and the effective permittivity of the composite is obtained from the equivalent capacitance of the structure. First, an individual cell diphasic dielectric (a high-permittivity spherical inclusion enclosed in a lower permittivity parallelepiped) is considered. The capacitance of this cell is modeled as a function of an inclusion radius/volume fraction. …

A Systematic Study On Structural And Optical Properties In Conjugated Polymer Photovoltaic Devices, Sri Sabarinadh Sunkavalli

Electrical & Computer Engineering Theses & Dissertations

Conjugated polymer/fullerene based solar cells represent an exciting alternative to inorganic ones because of their low production costs, flexibility and low weight. At present, commercialization of organic photovoltaic (OPV) cells is limited due to their relatively low efficiency in comparison to silicon ones. In order to understand the operation of OPV cells and to increase their efficiency, more information about the structure of the absorber layer is needed. In particular, the connection between structure and properties of the absorber layer is of great importance. Performance of bulk heterojunction organic solar cells based on poly (3-hexylthiophene) as donor and a soluble …

Surface Pre-Treatments And Fabrication Of Highly Ordered Anodic Aluminum Oxide Nanopores At Room Temperature, Sampath Chennuri

Electrical & Computer Engineering Theses & Dissertations

The object of this work is to develop a novel approach to fabricate model membranes of well-defined and well aligned nanostructured materials in a robust environment. The main focus is on electrochemical synthesis, involving anodic oxidation of high purity aluminum sheets to form porous oxide films. Alumina films were prepared by anodizing highly pure aluminum (99.999%) in acidic electrolytes. Anodization parameters (current density, temperature, applied voltage, anodization time and electrolyte concentration) were selected with respect to the electrolyte used.

The primary challenge in nanotechnology is the creation of nanometer-scaled objects with as narrow a size distribution as possible for a …

High Temperature Heat Exchanger Annual Report, Anthony Hechanova

Publications (NSTD)

Objectives

• Identify candidate materials for heat exchanger components.

• Test candidate materials for heat exchanger components.

• Design critical components in the interface between the reactor and hydrogen production plant and within the sulfur iodine thermochemical process.

• Fabricate prototypical components.

• Test prototypical components.

Equi-Biaxial Fatigue Of Elastomers: The Effect Of Oil Swelling On Fatigue Life, Stephen Jerrams, John Hanley, Niall Murphy, Ali Hassan

Articles

The effect of oil swelling on the fatigue life of ethylene propylene diene monomer rubber (EPDM) has been studied under conditions of equi-biaxial cycling using dynamic bubble inflation. Specimens were subjected to varying degrees of swelling in reference mineral oils and fatigued at constant engineering stress amplitudes. The reference oils used for swelling the EPDM had known aniline points, allowing the rubber-oil compatibility to be determined. The inflation fluid for fatigue testing was selected with a solubility parameter that would produce a desired level of incompatibility with the test specimens, thereby limiting the amount of additional swelling during cycling. Wöhler …

Environmental Effects On Corrosion Properties Of Alloy 22, Mano Misra

Publications (YM)

This document presents detailed technical report for four Subtasks that were conducted independently. All four Subtasks investigated environmental effects on corrosion properties of Alloy 22. The four Subtasks that were investigated are as follows: Subtask 1: Experimental Determination of Parameters for the General Corrosion Model. Subtask 2: Corrosion under Dust Deposits Containing Hygroscopic Salts. Subtask 3: Heated Electrode Approach for the Study of Corrosion Under Aggressive Conditions. Subtask 4: Effect of Hydrogen Permeation on the Stability of the Passive Film of Alloy 22.

A Better Nondimensionalization Scheme For Slender Laminar Flows: The Laplacian Operator Scaling Method, Mark M. Weislogel, Yongkang Chen, D. Bolleddula

Mechanical and Materials Engineering Faculty Publications and Presentations

A scaling of the two-dimensional Laplacian operator is demonstrated for certain solutions (at least) to Poisson’s equation. It succeeds by treating the operator as a single geometric scale entity. The belated and rather subtle method provides an efficient assessment of the geometrical dependence of the problem and is preferred when practicable to the hydraulic diameter or term-by-term scaling for slender fully developed laminar flows. The improved accuracy further reduces the reliance of problems on widely varying numerical data or cumbersome theoretical forms and improves the prospects of exact or approximate theoretical analysis. Simple example problems are briefly described that demonstrate …

Big Challenges In Designing Small Parts For Mass Production, Kevin Delaney, David Kennedy

Conference Papers

Micro manufacturing involves the production of parts or products with features on a micro scale. The technology is used to produce parts for several business sectors which have experienced dramatic growth in recent years and forecasts are that this growth will continue in the years ahead. With the loss of traditional manufacturing jobs to lower-cost locations many companies in Ireland see micro manufacturing as having significant potential to preserve and increase revenue. A move into micro manufacturing will present significant opportunities for those companies willing to take the risk of producing parts with micro dimensions. Such a transition is a …

Modeling Edge Effects Of Mesa Diodes For Silicon Photovoltaics, Jesse S. Appel

Dissertations

A mesa diode has been modeled and its performance under dark and illuminated conditions has been simulated using a commercial finite element software package. These simulations have led to a determination of the self-consistent solution to the continuity equations for electrons and holes using the steady-state drift-diffusion model for carrier dynamics coupled with electric potential determined from Poisson's equation. The purpose of these simulations has been to determine the influence of edge conditions on the overall performance of mesa diodes under dark and illuminated conditions.

Mesa diode arrays are fabricated on crystalline silicon solar cells. They are an array of …

Probing Spin, Charge And Lattice Coupling In Manganites, Zhiqiang Chen

Dissertations

Complex oxides such as the manganites exhibit an intimate coupling of the electron spin, charge and lattice degrees of freedom. The characteristic feature of these materials is the existence of a ground state topology with many closely lying minima. The system can be switched from one minimum to another by the application of external parameters such as strain, temperature, magnetic fields, or electrical fields. These materials thus exhibit large responses to these external parameters and can be used as novel sensors in data storage and other applications. Understanding the couplings will have an impact on the fundamental science of highly …

Ionic Liquids As Additives For Biodegradable Polyactic Acid, Ku-Il Park

Dissertations

In this study, two ionic liquids (IL) with different anions (decanoate, tetrafluoroborate) but with the same phosphonium based cation were evaluated as potential plasticizers and lubricants for polylactic acid (PLA) and also for their effects on its hydrolytic and thermal degradation. Both ILs at 5wt% were well dispersible and partly miscible with PLA as evidenced by scanning electron microscopy/energy dispersive x-ray scattering, SEMIEDX, and glass transition temperature, T_g, characterization, as well as from solubility parameters calculations.

The effects of the IL containing a decanoate anion were more pronounced on lubrication and degradation as evidenced by reduced melt viscosities …

Synthesis And Characterization Of Atmospheric Pressure Chemically Vapor Deposited Aluminum, Sipeng Gu

Dissertations

This study investigates the use of atmospheric pressure chemical vapor deposition (APCVD) to produce high quality aluminum coatings for corrosion protection of steel. The coatings were produced through thermal decomposition of tri-isobutyl-aluminum (TIBAL) over the 275 to 300°C temperature range. Under optimal deposition conditions, growth rates as high as 1.2 um/min were achieved. X-ray photoelectron spectroscopy, auger electron spectroscopy, glow discharge optical emission spectroscopy and nuclear reaction analysis revealed that the coatings consisted essentially of pure aluminum (~99 at.%) with oxygen and carbon present as minor constituents. The coatings were characterized in terms of their morphological, structural, electrical, and mechanical …

Electrocatalytic Performance Of Carbon Supported Au-Ir Catalyst As Cathodic Catalyst In Direct Formic Acid Fuel Cell, Wei Chen, Ya-Wen Tang, Tain-Hong Lu

Journal of Electrochemistry

In this paper,it is reported for the first time that the electrocatalytic activities of the carbon supported Au(Au/C),carbon supported Ir(Ir/C) and the carbon supported Au-Ir(Au-Ir/C) catalysts prepared in the aqueous solution with tetrahydrofuran(THF) for the oxidation of formic acid and for the oxygen reduction were compared.It was found that all three catalysts showed no electrocatalytic activity for the oxidation of formic acid,but the electrocatalytic activity of the Au-Ir/C catalyst for oxygen reduction was much better than those of Au/C and Ir/C.Thus,the Au-Ir/C catalyst is suitable to be used as the cathodic catalyst in Direct formic acid fuel cell(DFAFC).

Hydrolysis Of Sodium Borohydride By Ru-Ni Foam Catalyst, Jie Cheng, Feng Ye, Tong-Tao Wang, Jing-Jing Li, Yong-Liang Wang, Xin-Dong Wang

Journal of Electrochemistry

This paper presented a method of hydrogen generation from sodium borohydride solution for fuel cells.The Ru-Ni foam catalyst which was prepared by chemical plating showed strong activity and stability.The pretreatment of Ni foam before chemical plating was very important for the catalyst's strong activity and stability.This easy-to-prepared catalyst exhibited a good activity after being used several times.The effects of NaBH₄ concentration,temperature and used times on the hydrogen generation rate were investigated.The results showed that the rate was remarkablely increased with the temperature rising and the rate increased more than ten times when the temperature of reaction rised from 15 …

Preparation And Supercapacitive Properties Of Co(Oh)2/Nay Composite, Chi Ma, Ling-Bin Kong, Yong-Chun Luo, Long Kang

Journal of Electrochemistry

The Co(OH)₂/NaY composite was prepared by chemical precipitation method and then tested as an active electrode material for an electrochemical supercapacitor.The results indicated that the composite displayed superior capacitive performance.The maximum specific capacitance of Co(OH)₂ was 632.5 F/g.The structure and electrochemical properties of the composite were also discussed.

Corrosion Inhibition Of Self-Assembled Films On Iron By Electrochemical Impedance Spectroscopy, Yuan-Yuan Feng, Shen-Hao Chen, Juan-Juan Zhou, Wen-Juan Guo

Journal of Electrochemistry

The self-assembled films of tetradecylamine were formed on iron surface, and the inhibition ability of which for iron corrosion in 0.5 mol/L H₂SO₄ solutions was studied by electrochemical impedance spectroscopy technique. Results indicated that longer immersion time would result in stronger inhibition ability of the films. The maximal inhibition efficiency(IE) of the tetradecylamine films was 68.7%. When the tetradecylamine films were modified by dodecylthiol, the mixed films became denser and more stable, thus the inhibition ability increased remarkably. The η of the mixed films increased to 78.2%.

Electrochemical Synthesis, Characterization And Fluorescence Property Of Nano Na2Sif6, Guo-Xu Qin, Xin-Jun Wan, Xi-Mei Yuan, Dao-Bao Chu

Journal of Electrochemistry

The nano TiO₂ film was prepared by sol-gel process and characterized with X-ray diffraction(XRD) and scanning electron microscope(SEM).It was found that the average size of pore diameter was about 80 nm for the nano TiO₂ film.The Nano Na₂SiF₆ was synthesized by electrochemical deposition on the nanoporous film electrode and characterized with XRD and transmission electron microscope(TEM).The result showed that the average size of nanoparticle was 20 nm for the nano Na₂SiF₆.The fluorescence property of nano Na₂SiF₆ was also studied briefly.The result indicated that the nano Na₂SiF …

Electricity Generation In Microbial Fuel Cells Catalyzed By Mixed Culture And Pure Culture, Chen-Dong Shuang, En-Ren Zhang, Guo-Wang Diao, Fang-Fang Fan, Jie Yuan

Journal of Electrochemistry

Microbial fuel cells(MFCs) were constructed by inoculating fresh sedimentary microorganisms.Effect of phenol on performance of MFCs was investigated.The results showed that the generation of electrical current was induced by bacteria attached on the surface of the anode.Presence of phenol reduced the rate of glucose consumption and extended the duration of electricity generation with the same addition of glucose.In addition,the electricity generation by a single strain(belonging to pseudomonas species) separated from the sedimentary MFC was also investigated.The experimental results indicated that the presence of metabolic intermediates which exhibited electrochemical activity was necessary for the electricity production.Analysis of GC-MS showed that the …

Preliminary Study Of Single Flow Zinc-Nickel Battery, Li Zhang, Jie Cheng, Yu-Sheng Yang, Yue-Hua Wen, Xin-Dong Wang, Zi-Li Xie

Journal of Electrochemistry

The micromorphology of zinc electrodeposited at different currents in the flowing electrolyte was studied.It has been shown that the structure of the zinc became compacted with the increase of the charge current density and no zinc dendrite was presenct.A cell with 2Ah capacity was assembled and the charge-discharge test was performed.The results showed that the average charge voltage was 1.84V and the average discharge voltage was 1.65V.The high efficiencies can be achieved with an average coulombic efficiency of 97% and energy efficiency of 86% over 1000 cycles.

Electrochemical Reductive Behaviors Of 3,4,5,6-Tetrachloro-2-Trichloromethylpyridine At Ag Electrode, Chun-An Ma, Yi-Jiao Hu, Ying-Hua Xu

Journal of Electrochemistry

The electrochemical reductive behavior of 3,4,5,6-tetrachloro-2-trichloropyridine(heptachloropyridine) on silver electrode in the mixture of acetonitrile and water solutions containing TBAP was investigated by cyclic voltammetry.The influences of scan rate,concentration and temperature on the electrochemical behavior were discussed.It was shown that the reduction of heptachloropyridine on the silver electrode was a diffusion-controlled irreversible process.The diffusion coefficient of heptachloropyridine in the acetonitrile solution was 3.0×10^-5 cm²/s.The mechanism of the dechloration of 3,4,5,6-tetrachloro-2-trichloropyridine was also discussed.

Direct Electrochemistry Of Hemoglobin On The Electrode Modified With Ddab And Swcnt, Wen-Jing Hou, Lin Zhou, Xia-Qin Wu, Hong-Xia Zhang, Wen Xie, Liu Yang, Zhong-Qing Lu

Journal of Electrochemistry

Hemoglobin(Hb) was immobilized onto the surface of glassy carbon electrode with the single-wall carbon nanotubes and surfactant didodecyldimethylamonium bromide(DDAB) modified previously and its electrochemical behaviors have been investigated by cyclic voltammetry.A pair of well-defined redox peaks has been obtained.Cyclic voltammetry and electrochemical impedance spectroscopy(EIS) were also used to study on the effect of different concentration of SWCNT in DDAB.The result shows that the 1 mg/mL is the best choice.The dependence of E₀' on solution pH with the slope of 39 mV/pH,indicated that redox of the Hb is a one electron reaction with two protons transfer.The results also showed …

The Effect Of Ru: Sn On Properties Of Ru-Ir-Sn Oxide Anode Coatings, Lei Ji, Jun-Tao Wang, Wen-Bin Liu, Li-Kun Xu, Gui-Lin Xue

Journal of Electrochemistry

The anode coatings of Ru-Ir-Sn oxide with different Ru/Sn ratios were prepared by sol-gel method.The influences of Ru/Sn ratio on properties of anode coatings were studied by scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD).The potential of chlorine evolution,current efficiency,accelerated life,cyclic vohammetry and electrochemical impedance spectroscopy(EIS) tests were carried out.The results showed that there was an obvious effect of Ru/Sn ratio on the morphology of the coatings.The cyclic voltammogram,double layer capacitances and accelerated life of anode coatings had a tendency to fall down firstly then increased as the Ru% increased,the current effency and potential of chlorine evolution had a tendency to …

Design And Fabrication Of The High Efficient Platinum-Nanoporous Gold Catalysts, Zhao-Na Liu, Jin-Tao Zhang, Fang Tian, Peng-Peng Liu, Hou-Yi Ma, Yi Ding

Journal of Electrochemistry

The nanoporous gold(NPG) electrodes with uniform pore sizes and ligaments were prepared by using a simple dealloying method.The as-prepared NPG showed high catalytic activity towards the oxidation of formic acid and formaldehyde.After tiny amount of platinum was deposited onto the NPG substrate,not only the structure stability of NPG was greatly improved,but also the Pt-Au bimetallic catalysts displayed the better catalytic activity and the stronger poison resistance towards the electrooxidation of small organic molecules than the bulk platinum due to synergistic effect between Au and Pt compositions.

Study On Electrocatalytic Oxidation Of Salbutamol At Carbon Nanotubes Modified Electrode, Ying-Liang Wei, Lu-Ping Zhang, Chen Shao, Hui Feng, Xian-Li Li

Journal of Electrochemistry

The multi-wall carbon nanotubes(MWNT) were dispersed successfully into water in the presence of dihexadecyl hydrogen phosphate(DHP) and a stable well-distributed suspension.A was formed sensor based on the multi-carbon nanotubes film coated glassy carbon electrode was developed.The electrochemical response of salbutamol was studied by square wave voltammetry.The oxidation peak potential of salbutamol at the modified electrode was observed at 0.604 V,which shifted about 40 mV negatively.The peak current increased 4.5 folds,in contrast to that at a bare electrode.Under optimal measurement conditions,there was a good linear relationship between the peak current(Ipa) and salbutamol concentration(C) in the range from 8.3 × 1 0 …

Formation Of Copper Microcrystals On Porous Silicon Films, Lan-Li Chen, Fu-Fang Zhou, Bao-Gai Zhai, Yuan-Ming Huang

Journal of Electrochemistry

Microcrystals of metallic copper were electrochemically deposited onto the surface of porous silicon films in the aqueous electrolyte of copper(II) chloride.The microstructures of electrochemically deposited copper microcrystals on the porous silicon films were characterized by using scanning electron microscopy.The results have demonstrated that both center-hollowed and center-solid equilateral triangles in the sizes of several micrometers can be formed on the smooth bed of copper microcrystals.As the deposition duration increased from 0 to 28 hours,the fractal dimensions of the porous silicon was decreased from 2.608 to 2.252,suggesting that the electrochemical deposition can smooth the rough surface of porous silicon films.Compared to …

A Study Of Pd-Ir On Nickel Foam Cathode For Aluminum-Hydrogen Peroxide Semi-Fuel Cells, Ding-Wang Zhu, Dan-Dan Chen, Bi-Jin Li, Gui-Ling Wang, Dian-Xue Cao

Journal of Electrochemistry

The Pd-Ir/Ni electrodes were prepared by electrodeposition of Pd and Ir on the porous nickel foam surface.The structure,composition and state of the Pd-Ir catalyst were analyzed using SEM and XPS.The catalytic performance of Pd-Ir/Ni for H₂O₂ electroveduction at different concentrations of H₂O₂ were investigated.A limiting current density of 318 mA/cm² was obtained with 0.4 mol/L H₂O₂.The aluminum-hydrogen peroxide semi-fuel cells using different aluminum alloys as anode and Pd-Ir/Ni as cathode were assembled and tested.It was found that the fuel cell with aluminum-manganese alloy anode demonstrated a maximum power density …

Electrocatalytic Oxidation Of Salicylic Acid At Novel Gold Nanoparticle-Modified Glassy Carbon Electrode, Yan-Ping Cui, Chang-Zhu Yang, Jian Huang, Wen-Hong Pu, Jing-Dong Zhang

Journal of Electrochemistry

A gold nano-particles modified glassy carbon electrode(GNP/GCE) was prepared by the"seed-mediated gold nano-particles growth method".Field emission scanning electron microscopy,ultraviolet-visible(UV-vis) spectroscopy analysis and electroalaylsis were employed to study the morphology and electrochemical performances.The resulting electrode showed excellent electro-catalytic activity toward the oxidation of salicylic acid and the response sensitivity was 1.8 fold than that obtained on GCE.Good linear relationship was obtained between response current and salicylic acid concentration in the range of 5.0 × 10^-7 ~8.0 × 10^-5 mol/L,which could be used in the detection of trace salicylic acid.

Direct Electrochemistry Of Hemoglobin Immobilized On The Electrode Modified With Ionic Liquid And Kgm, Liu Yang, Xia-Qin Wu, Wen-Jing Hou, Lin-Fei Gu, Rong Wang, Xiao-Ming Guo, Zong-Rang Zhang

Journal of Electrochemistry

Hemoglobin(Hb) has been immobilized on a glassy carbon electrode(GCE) surface with konjac glucomannan(KGM) and room temperature ionic liquid(RTIL).And which electrochemical behaviors have been investigated by cyclic voltammetry.The results shown that the entrapped Hemoglobin undergoes fast direct electron transfer reactions with formal potential of-0.38V(vs.SCE) and the E0' is linearly dependent on solution pH with a slope value of 51 mV/pH,due to the electron transfer of HbFe³⁺/HbFe²⁺ redox couple companied with a proton transfer.The electrocatalytic reduction of oxygen was also explored at the Hb-KGM/RTIL/Nafion/ GC electrode.

Performance Of Magnetic Field Coupled With Electrochemical Process For Preparing Polyaluminum Chloride, Ke-Wu Pi, Wen-Qi Gong, Zheng-Qing Huang

Journal of Electrochemistry

Polyaluminum chloride(PAC) was prepared by electrochemical process coupled with magnetic field paralleling to the gravitation direction.The electrolyte of 0.1 M AlCl3 solution was used,with the iron plates as cathode and aluminum sheets as anode.PAC of 0.6 M total aluminum(AlT),83.2% Alb to AlT and basicity(Ba)=2.4 was synthesized when magnetic flux density was 0.4T,the distance of electrodes was 15 mm,the voltage of electrolysis cell was 2.4 V and current density was 300 A/m2.Under above experimental conditions,the voltage efficiency,energy efficiency and electrodes surface area to reduction cells of electrochemical reactor were 85.2%,81.5% and 140.1m2/m3,respectively.The polarization curves determined by constant-current method showed that the …

Study Of Triethyl Phosphate Self-Assembled Films On Iron For Corrosion Inhibition, Wen-Juan Guo, Shen-Hao Chen, Wei He, Xue-Hui Pang, Yuan-Yuan Feng

Journal of Electrochemistry

The self-assembled film of triethyl phosphate(TEP) formed on the iron surface was found to protect iron from corrosion in 0.5 mol·L^-1 H₂SO₄ efficiently. The inhibition effects were investigated using the electrochemical impedance spectroscopy(EIS).EIS demonstrated that the charge-transfer resistance of the electrode covered with TEP film was greater than that of the naked iron electrodes and the inhibition efficiency of TEP film increased quickly in the initial period and then increased slowly. Quantum chemical calculations provide information about the process of adsorption of molecules on the metal surface at the molecular level.