Engineering Commons^™

Lead Modified Nanoporous Platinum Electro-Catalysts For Formic Acid Oxidation, Yuan-Yuan Zhang, Qing-Feng Yi, Ge-Kun-Kun Zuo, Tao Zou, Xiao-Ping Liu, Xiu-Lin Zhou

Journal of Electrochemistry

Platinum (Pt) catalysts modified by other suitable metals significantly enhance their electrochemical activities for formic acid oxidation. In this work, a titanium-supported nanoporous network platinum (nanoPt/Ti) electrode was prepared using a hydrothermal method. The as-prepared nanoPt/Ti electrode was modified with a certain amount of lead by using cyclic voltammetry for different scan cycle numbers (n), namely, n = 10, 15, 20 and 30, to synthesize the novel lead-modified nanoporous Pt (nanoPb_(n)-Pt/Ti) electrodes. Electro-oxidation of formic acid on these electrodes was studied with cyclic voltammetry (CV), chronoamperometry and chronopotentiometry in sulfuric acid solution. CV curves showed that both nanoPt/Ti …

Co3(Hcoo)6@Rgo As A Promising Anode For Lithium Ion Batteries, Heng Jiang, Jing-Min Fan, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Metal–organic framework(MOF) is a kind of novel electrode materials for lithium ion batteries. Here, a composite material Co₃(HCOO)₆@rGO was synthesized for the first time by in situ loading of Co₃(HCOO)₆ on rGO (reduced oxide graphene) through a solution chemistry method. As an anode material for lithium ion batteries, it exhibited an excellent cycle stability as well as a large reversible capacity of 926 mAh·g^-1 at a current density of 500 mA·g^-1 after 100 cycles within the voltage range of 0.02 ~ 3.0 V vs. Li/Li⁺ with a good rate capability. …

Preparations And Electrochemical Performances Of Carbon Coated Silicon/Graphite Composites, Tian-Yi Gao, Zheng-Liang Gong

Journal of Electrochemistry

In this work, the carbon coated silicon (Si@C) composite materials were synthesized based on the industrial silicon powder (600 meshes) via a high energy ball milling combing with in-situ carbon coating (carbonization) method. The Si@C/graphite (Si/C) composite anode materials were prepared by a simple mechanical ball-milling approach. The effects of carbon coating and the ratio of Si to graphite on electrochemical performances of Si/graphite composite materials were investigated systematically. Compared with the nano-Si/graphite composites, the Si/C composites showed higher reversible capacity, better rate capability and cycle performance. The Si@C materials composited of amorphous carbon and crystal silicon with the primary …

Preparation And Electrochemical Performance Of Ag-Tio2-Mno2 Composites, Ling-Xiao Zhang, Hui-Hui Zhao, Li-Juan Zhang, Yu Fu

Journal of Electrochemistry

The silver-titanium dioxide  co-modified manganese dioxide (Ag-TiO₂-MnO₂) cathode material was prepared through high temperature solid state reaction. The microstructure, phase composition and electrochemical performance of the prepared samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), Cyclic voltammetry (CV), galvanostatic discharge and electrochemical impedance spectroscopy (EIS). Results showed that the unmodified and Ag-TiO₂ modified MnO₂ samples both exhibited β-MnO₂ structurebut with different morphologies. The EDS mapping results revealed that Ag was uniformly dispersed on the surface of …

Migration Resistance Of Esophageal Stents: The Role Of Stent Design, Hozhabr Mozafari, Pengfei Dong, Shijia Zhao, Yonghua Bi, Xinwei Han, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Objective: Stenting is one of the major treatments for malignant esophageal cancer. However, stent migration compromises clinical outcomes. A flared end design of the stent diminishes its migration. The goal of this work is to quantitatively characterize stent migration to develop new strategies for better clinical outcomes.

Methods: An esophageal stent with flared ends and a straight counterpart were virtually deployed in an esophagus with asymmetric stricture using the finite element method. The resulted esophagus shape, wall stress, and migration resistance force of the stent were quantified and compared.

Results: The lumen gain for both the flared stent and the …

Chemical Stability Investigations Of Catalyst Layer In Pemfc, Yan-Yan Gao, Ming Hou, Yong-Yi Jiang, Dong Liang, Jun Ai, Li-Min Zheng

Journal of Electrochemistry

This work was intended to study the effect of free radicals on the chemical stability of catalyst layer via ex situ accelerated stress test (AST). Fenton reagent was used as the free radical provider in this research. Apart from the decomposition of Nafion in catalyst layer, the agglomerated Pt nanoparticles and the corroded carbon support were also observed after being treated in Fenton reagent for 100 h. Firstly, the existence of fluoride (F) ions evidenced the chemical decomposation of Nafion after being attacked by trace radical species, which was supported by the intensity decrease in the C-F stretching and vibration …

A Study Of Pulse Electrodeposition On Suppressing The Formation Of Lithium Dendrite, Wen-Jun Guo, Zi-Qiong Li, Ruo-Hao Ke, Dong-Fang Niu, Heng Xu, Xin-Sheng Zhang

Journal of Electrochemistry

A pulse charge method was used to suppress the formation of lithium dendrite on the copper electrode in 0.5 mol·L^-1 LiBr/propylene carbonate (PC) electrolyte. The surface variation of lithium deposition was investigated by scanning electron microscope and impedance measurement. The SEM test showed that the lithium dendrites were formed on the copper electrode during the traditional process of electrodeposition. However, the formed dendrite was suppressed by pulse charge method. The results of the impedance measurement confirmed that the pulse electrodeposition could suppress the dendrite under the optimized duty ratio (0.5). The long single pulse deposition time decreased the resistance …

Energy Conversion System For Travelers (Ecost), Thipok Bovornratanaraks

The International Student Science Fair 2018

We have innovated “The Energy Conversion System for Travelers” or the ECoST. With the fact that most travelers have wheeled cabin-bags, whilst walking, the wheels will rotate so why don’t we harvest electricity from this kinetic energy? We thus install our innovation, the ECoST, to the bag to generate electricity from the spinning wheels. The electricity is then kept in the storage unit and ready to charge your empty battery devices in an emergency case via a USB port. To make life easy, our ECoST was designed to replicate the power bank charging method; therefore, we can charge …

A Coupled Thermo-Mechanical Theory Of Strain Gradient Plasticity For Small And Finite Deformations, Yooseob Song

LSU Doctoral Dissertations

In this work, a thermodynamically consistent coupled thermo-mechanical gradient enhanced continuum plasticity theory is developed for small and finite deformations. The proposed model is conceptually based on the dislocations interaction mechanisms and thermal activation energy. The thermodynamic conjugate microstresses are decomposed into energetic and dissipative components. This work incorporates the thermal and mechanical responses of microsystems. It addresses phenomena such as size and boundary effects and in particular microscale heat transfer in fast-transient processes. Not only the partial heat dissipation caused by the fast transient time, but also the distribution of temperature caused by the transition from the plastic work …

Me-Em Enewsbrief, June 2018, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Analysis Of The Low-Cycle Fatigue Behavior Of Silicone Rubber For Biomedical Balloons, Chase Cooper

Materials Engineering

The development of a medical drug delivery device that allows for the deployment drugs into the adventitial tissue of blood vessels requires the inflation of a silicone elastomer. The inflated silicone must be able to consistently endure multiple loading cycles without failing so that the device can operate reliably. There are multiple methods of processing the silicone for the device and the goal of this study is to examine the effect of the various processing methods on the characteristics of the silicone. The Dynamic Mechanical Analysis Machine (DMA) is used to model the conditions of the device’s application by performing …

Direct Synthesis Of Graphene On Niobium And Niobium Nitride, Robin Ekeya, Otto Zietz

Maseeh Summer Undergraduate Research Experience

Since its isolation by mechanical exfoliation in 2004, graphene has attracted enormous interest from the scientific community not the least because of its unique physical and electronic properties. Among these, graphene’s ballistic electron transport and proximity induced superconductivity make graphene-superconductor (GS) hybrid structures a scientifically promising area.

System And Method For Controlling Operations Of Air - Conditioning System, Mouhacine Benosman, Petros Boufounos, Boris Kramer, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

A method controls an operation of an air - conditioning system generating airflow in a conditioned environment . The method updates a model of airflow dynamics connecting values of flow and temperature of air conditioned during the operation of the air - conditioning system . The model is updated interactively iteratively to reduce an error between values of the airflow determined according to the model and values of the airflow measured during the operation . Next , the method models the airflow using the updated model and controls the operation of the air - conditioning system using the model .

Modeling Kidney Transplantation Decisions: Regulatory Oversight, Information Sharing, And Post-Transplant Drug Choice, Zahra Gharibi

Operations Research and Engineering Management Theses and Dissertations

The United States and many other nations are encountering a disturbing obstacle: A shortage of available organs for patients who are in need of kidney transplantation. This dissertation strives to analyze this trend and present potential solution by focusing on three different aspects, namely regulatory oversight, information sharing, and post-transplant immunosuppressant drug choice. In my first essay, I propose a stochastic model that identifies a socially-optimal kidney transplant choice given the inherent trade-off between the expected wait time (driven by supply and demand) and the quality of received donor kidney.

I modify the model to account for changes made by …

Preliminary Investigation Of Tensile Strength And Impact Characterization Of Cementitious Composite Incorporating Carbon Nanotubes, Robabeh Jazaei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cement has been largely used in the construction industry, specifically as a matrix for concrete. Recently, a new generation of cement-based composite that greatly increases mechanical properties is replacing conventional concrete. With periodic advances in the field, researchers considered particles with high-aspect ratios such as Carbon Nanotubes (CNTs) to reinforce cement matrices. Although there is not much literature to draw upon in research, some research on improving the tensile strength of cementitious composite incorporating with CNTs does exist. However, there had been no evidence of investigation into impact strength until this study.

Most papers presented examined the effect of multi-walled …

Morphological And Energy Transport Optimization Of Spectrally-Selective Solar Absorber Coatings At Mesoscale, Dale Karas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A special class of cuprous-based inorganic oxide materials, synthesized as nanoparticles via hydrothermal and co-precipitation methods, are portable to spectrally-selective absorber coatings with high solar-thermal energy conversion efficiency. Operating reliably at elevated temperatures when used in tandem with solar concentrators, these materials enable cost-competitive solar energy conversion technology that can be incorporated with thermal energy storage systems, supporting the viability of novel renewable power generation; notably, optimizing absorptive performance while mitigating thermal losses through re-radiated waste heat motivates sustainable energy production particular to desert climates, where water conservation and ecological sensitivity needs are paramount.

This work targets the chemical synthesis …

A Novel Approach To Analyzing Strain Heterogeneity In Polycrystalline Quartz Specimens Deformed At High Pressure And Temperature, Nolan Ambrose Regis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rheological studies of rocks and minerals allow researchers to study the grain-scale deformation mechanisms that govern large-scale geologic processes from mountain building to mantle mixing. Deforming rock samples with high pressure and temperature apparatuses similar to the Griggs piston cylinder apparatus allows us to simulate deformation at depth. However, many apparatuses are limited to “cook-and-look” analysis and require modeling techniques to determine the evolution of deformation patterns found in experimental samples. A previous study used two-dimensional finite element models to analyze the development of stress and strain patterns in polycrystalline rocks. The study suggested rhythmic patterns in deformed rocks develop …

Numerical Study Of Oxidation In Stainless Steel Alloy Ep-823 By Liquid Lead-Bismuth Eutectic, Rajyalakshmi Palaparty

UNLV Theses, Dissertations, Professional Papers, and Capstones

The oxidation of stainless steel is influenced by the presence of oxygen in the surrounding medium; the oxygen reacts with the alloy to form an oxide. In certain environments, such as nuclear reactor coolant systems, minimal oxidation of the stainless steel containment functions as a protective shield from corrosive coolants such as liquid lead-bismuth eutectic.

In the current study, this minimal oxidation is evaluated for a system in which corrosion-resistant stainless steel alloy EP-823 is subject to an environment of flowing oxygenated liquid lead-bismuth eutectic at a temperature of 743 K, whereby the thickness of the forming oxide layer is …

The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser

Senior Theses

There are many golf balls on the market today with varying dimple sizes, shapes, and distribution. These proprietary differences are all designed to reduce drag on the balls during flight, allowing golfers to hit the ball farther distances. There are limited published studies comparing how varying the dimples affects the reduction of drag. An experiment was developed in which golf balls were pulled through a water tank to measure the drag force acting on each ball. The water was chosen to allow for testing at slower velocities than the typical necessary speeds to cause turbulence for balls traveling in air. …

Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli

Electronic Theses and Dissertations

Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of process-structure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the …

Critical-Point Model Dielectric Function Analysis Of Wo3 Thin Films Deposited By Atomic Layer Deposition Techniques, Ufuk Kılıç, Derek Sekora, Alyssa Mock, Rafał Korlacki, Elena M. Echeverría, Natale J. Ianno, Eva Schubert, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

WO₃ thin films were grown by atomic layer deposition and spectroscopic ellipsometry data gathered in the photon energy range of 0.72-8.5 eV and from multiple samples was utilized to determine the frequency dependent complex-valued isotropic dielectric function for WO₃. We employ a critical-point model dielectric function analysis and determine a parameterized set of oscillators and compare the observed critical-point contributions with the vertical transition energy distribution found within the band structure of WO₃ calculated by density functional theory. We investigate surface roughness with atomic force microscopy and compare to ellipsometric determined effective roughness layer thickness.

Concomitant Crystallization In Propylene/Ethylene Random Copolymer With Strong Flow At Elevated Temperatures, Lirong Zheng, Lucia Fernandez-Ballester, Gerrit W. M. Peters, Zhe Ma

Department of Mechanical and Materials Engineering: Faculty Publications

Flow-induced crystallization of α- and γ-phases was studied for a propylene/ethylene random copolymer with 3.4 mol % ethylene at two high temperatures of 132 and 142 °C by combining a pressure-driven slit flow device with real-time synchrotron wide-angle X-ray diffraction. At 132 °C, it was found that both α- and γ-phases were generated at shear stresses ranging from 0.091 to 0.110 MPa and that the γ-phase always appeared later than the α-phase. However, for 142 °C and the same stresses, only the α-phase formed. Only upon cooling the partially crystallized copolymer did the γ-phase emerge. The lack of γ-crystals obtained …

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium, …

Synthesis And Electrochemical Properties Of Li3V2(Bo3)3/C Anode Materials For Lithium-Ion Batteries, You Wang, Yi-Wen Zeng, Xing Zhong, Xing Liu, Quan Tang

Journal of Electrochemistry

The Li₃V₂(BO₃)₃/C (LVB/C) composite materials were successfully synthesized in two steps:Firstly, a stoichiomertric mixture of Li₂C₂O₄, V₂O₅, H₃BO₃, H₂C₂O₄•H₂O and ethanol was thoroughly ball-milled to get the precursors. Secondly, the precursors were post-calcinated to get the ultimate products. The calcination temperatures of 750 ℃, 800 ℃ and 850 ℃ were selected based on TG-DTA analyses. The crystal structures, surface morphologies and carbon contents of the samples calcinated at five conditions, …

Electrochemical Performance Of Moo2-C Composite Coatings, Quan-Yi Li, Qi Yang, Yan-Hong Zhao

Journal of Electrochemistry

The molybdenum dioxide-carbon(MoO₂-C)composite coatings on the surface of Cu foils were prepared by simple knife coating route and followed by sintering in vacuum. The morphology, composition, structure and electrochemical performance of the MoO₂-C composite coatings were investigated. The results demonstrated that the MoO₂-C composite coatings consist of MoO₂ nano-particles with monoclinic crystal structure and amorphous carbon. Some MoO₂ nano-particles with a size range of 5-30nm were loaded on the surface of carbon matrices; while some MoO₂ nano-particles with a size of ~5nm were encapsulated inside. The composite coatings showed porous structure …

Preparation Of Co3O4/Ti Electrocatalytic Membrane Electrode For Catalytic Oxidation Of Benzyl Alcohol, Yu-Mei Zheng, Zhen Yin, Hong Wang, Jian-Xin Li

Journal of Electrochemistry

The cobalt oxide(Co₃O₄) nanoparticles were loaded on microporous Ti membrane to prepare Co₃O₄/Ti electrocatalytic membrane electrode by dip-coating method. The microstructures and electrochemical properties of Co₃O₄/Ti electrocatalytic membrane were investigated. The Co₃O₄/Ti electrocatalytic membrane reactor (ECMR) assembled by using the Co₃O₄/Ti electrocatalytic membrane as an anode was adopted for catalytic oxidation of benzyl alcohol to produce benzaldehyde and benzoic acid.The effects of different operation parameters on benzyl alcohol conversion, and selectivity to benzaldehyde and benzoic acid of ECMR were studied. …

Electrochemical Oxidation Of P-Chlorophenol On Porous Ti/Bdd Electrode Cooperated With Cathode Dechlorination, Rong-Ling Chen, Wei-Min Huang, Ya-Peng He, Jun Shi, Hai-Bo Lin

Journal of Electrochemistry

The electrochemical oxidation of p-chlorophenol on porous Ti/BDD electrode cooperated with synergistic effect of cathode dechlorination was studied. Electrochemical degradation tests of p-chlorophenol were conducted in single and double compartment electrolytic cells separately, and the results showed that the mineralization happened mainly in the anode region. The product of chloride ions produced from the cathodic reduction of 4-chlorophenol in the single cell migrated to the anode region and further generated active chlorine toward electro-catalytic oxidation. At the same time, the chloride ion produced from the cathode of the double cell was difficult to be migrated to the anode region, which …

Preparations And Corrosion Protection Investigations Of Diethylene Triamine Penta(Methylene Phosphonic Acid)-Zn2+ Conversion Coatings On Cold Rolled Steel Substrates, Wei He, Ru Yan, Ying-Qi Wang, Xiang Gao, Hou-Yi Ma

Journal of Electrochemistry

Novel diethylene triamine penta(methylene phosphonic acid) (DTPMPA)-zinc ion (Zn²⁺) conversion coatings with uniform blue color and excellent corrosion protection were directly formed on the cold rolled steel (CRS) substrates by immersing a CRS plate into the film-forming solutions containing the appropriate concentrations of DTPMPA and Zn²⁺ ion at the proper pH. In this paper, surface morphologies and elemental compositions of DTPMPA-Zn²⁺ conversion coatings were characterized by SEM and EDS, respectivey. The surface functional groups, chemical constituents and binding modes to the substrates were investigated by means of FTIR and XPS methods. The influences of DTPMPA concentrations …

Simulation Analysis In Dynamic Performance Of Proton Exchange Membrane Fuel Cell Under Starting Condition, Yan Xiao, Ying-Jie Chang, Wei Zhang, Qiu-Hong Jia

Journal of Electrochemistry

Based on the equivalent circuit model, by considering both the dynamic gas pressure model and the dynamic heat transfer model, a lumped parameter model is developed. The start process of the fuel cell is simulated by using SIMULINK software. The undershoot of the voltage is observed from the simulation results, and the response time of the voltage is basically the same as that of the fuel cell temperature, which indicates that the temperature has great influence on the dynamic performance of the fuel cell. From the perspective of the temperature, the dynamic responses of the thermodynamic potential, the activation overvoltage, …

Interaction Between Energy And Electrocatalysis —— A Review On The 1st Young Scientist Forum On Energy Electrocatalysis, Hong Li, Wen-Bin Cai

Journal of Electrochemistry

No abstract provided.