Engineering Commons^™

Technical Research Needs For Sustainable Buildings: Results From A Multidisciplinary Nsf Workshop, Leidy Klotz, Vivien Loftness, Gregor Henze, David J. Sailor, David Riley

Mechanical and Materials Engineering Faculty Publications and Presentations

This article describes research needs for sustainable buildings as defined in a July 2009 National Science Foundation-sponsored workshop. This workshop brought together building researchers with researchers in the areas of distributed renewable energy and multifunctional materials to engage their expertise and identify overlapping research needs and opportunities. An overview of sustainable building design provided the broad context for discussion. This overview was followed by focused presentations in building control systems, advanced building envelopes, and systems and process integration. In addition, presentations on distributed renewable energy and multi-functional materials supported the participants in outlining and generating research needs that connect the …

Focusing Electromagnetic Radiation In Dielectric Media, Mark A. Migliaccio Jr.

Electrical & Computer Engineering Theses & Dissertations

Bioelectrics and microwave imaging requires an ultra-wideband (UWB) antenna to deliver intense, short electromagnetic pulses into biological targets for the purpose of therapy and imaging. Two antennas with different focal distances, predicted by a two­ dimensional model, have been designed for focusing electromagnetic radiation in the near field.

Focusing is achieved through the use of prolate spheroidal reflector antennas with a conical wave launcher submerged in water. For an ultra-wideband feed signal, with a rise time of 200 picoseconds, the maximum electric field was found to be close to the edge of the reflector, a result that differs from the …

A Systematic Study Of Atomic Layer Deposition Of Platinum Nano-Scale Metallization Films And Their Application To Electrical Contacts In Porous Alumina Templates, Ngoc H. Tran

Electrical & Computer Engineering Theses & Dissertations

ln this thesis a comprehensive analysis is presented on nano-scale thin films of platinum deposited with Angstrom resolution by Atomic Layer Deposition (ALD) technology utilizing the Cambridge Nanotech Savannah 100 ALD system. Physical characterizations of film thickness, film morphology, and surface roughness of the deposited platinum were all performed before and after rapid thermal annealing (RTA) and as a function of forming gas annealing (FGA). Noble metal thin films of platinum were deposited on four inch wafers of p-type boron doped &100& oriented silicon (Si) substrates. The ALD film thickness was measured with a novel method utilizing the linear dependence …

Nanoscale Domain Patterns In Ultrathin Polymer Ferroelectric Films, Pankaj Sharma, Timothy J. Reece, Daniel W. Wu, Vladimir M. Fridkin, Stephen Ducharme, Alexei Gruverman

Stephen Ducharme Publications

High-resolution studies of domain configurations in Langmuir–Blodgett films of ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), have been carried out by means of piezoresponse force microscopy (PFM). Changes in film thickness and morphology cause significant variations in polarization patterns. In continuous films and nanomesas with relatively low thickness/grain aspect ratio (<1/10), the relationship between the average domain size and thickness follows the Kittel law. Nanomesas with high aspect ratio (>1/5) exhibit significant deviations from this law, suggesting additional surface-energy-related mechanisms affecting the domain patterns. Polarization reversal within a single crystallite has been demonstrated and local switching parameters (coercive voltage and remnant piezoresponse) have been measured by monitoring the local hysteresis loops. Reliable control of polarization at the sub-grain level demonstrates …

Methods For Cancer Detection, Kimberly W. Anderson, Kimberly M.L. May, Leonidas G. Bachas

Chemical and Materials Engineering Faculty Patents

A method is provided for detecting an analyte indicative of a cancer or a metastatic disease condition, which utilizes the ability of the analyte to induce permeability in a barrier. The method includes providing a biosensor having a barrier which is substantially impermeable to an ion, a permeable membrane which is selective for the ion, and a detector capable of detecting the ion. The biosensor is contacted with a sample including at least one of the ion and the analyte, wherein the analyte causes at least a portion of the ion to pass through the barrier and the membrane. Passage …

Shear Rate Threshold For The Boundary Slip In Dense Polymer Films, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible chains. We found that at low shear rates the velocity profiles acquire a pronounced curvature near the wall and the absolute value of the negative slip length is approximately equal to thickness of the viscous interfacial layer. At higher shear rates, the velocity profiles become linear and the slip length increases rapidly as a function of shear rate. The gradual transition from no-slip to steady-state …

Work In Progress - A Mixed-Methods Approach To Developing An Instrument Measuring Engineering Students' Positive Ethical Behavior, Mathew A. Holsapple, Cynthia J. Finelli, Donald D. Carpenter, Trevor S. Harding, Janel A. Sutkus

Materials Engineering

Ethics education and the drive to produce ethical professional engineers is an important focus of one body of research on engineering education. This research often defines the positive outcome of ethics education as students and professional engineers choosing not to engage in unethical behavior. This paper discusses a portion of a larger research project and details efforts to identify and validate a definition of ethical behavior that includes the decision to engage in a positive behavior, defined as a service to a larger community. Through a series of interviews and focus groups with engineering administrators, faculty, and students, the authors …

Thermo-Mechanical Characterization Of Silicon Carbide-Silicon Carbide Composites At Elevated Temperatures Using A Unique Combustion Facility, Ted T. Kim

Theses and Dissertations

This research investigated four different types of CMCs in a simulated gas turbine engine hot section condition that involved the simultaneous application of a combustion environment and mechanical fatigue loading using a unique burner rig facility developed for this study at AFIT. Three of the materials were woven Melt-Infiltrated (MI) BN/SiC reinforced by Hi-Nicalon Type S (Hi-Nic-S), Sylramic (Syl) and Sylramic with insitu BN coating (Syl-iBN) fibers, respectively. They were made by the slurry cast method. The other CMC was MI Hi-Nic-S/BN/SiC made using the prepreg MI processing. Prepreg MI CMC and Sylramic-iBN fiber reinforced CMC showed better resistance to …

Feasibility Of Ellipsometric Sensor Development For Use During Pecvd Siox Coated Polymer Product Manufacturing, Daniel Lynn Helms

Master's Theses

Polymeric materials have provided pathways to products that could not be manufactured otherwise. A new technology which merges the benefits of ceramics into these polymer products has created materials ideally suited to many different industries, like food packaging. Nano Scale Surface Systems, Inc. (NS3), a company which coats polymers with ceramic oxides like SiO2 through a process known as plasma enhanced chemical vapor deposition (PECVD), was interested in the feasibility of an in line measurement system for monitoring the deposited films on various polymer products. This project examined two different coated polymer products, polyethylene terephthalate (PET) beverage containers and biaxially …

Dielectric Nanocomposites: An Inside-Out Approach To Storing Electrostatic Energy, Stephen Ducharme

Stephen Ducharme Publications

The ability to achieve high-energy densities is the central challenge in energy storage and recovery. A promising strategy for increasing energy storage is to use highperformance dielectric materials, such as highly polarizable nanoparticles or polymers, or nanocomposites of the two. In this issue, Kim et al. use a molecular coating and clever chemistry to combine oxide nanoparticles with a polymer matrix, thereby producing an improved nanocomposite dielectric. Some advantages and challenges of using nanocomposites as improved dielectric materials are presented in this Perspective.

Emerging Nonequilibrium Bound State In Spin-Current-Local-Spin Scattering, Fatih Dogan, Lucian Covaci, Wonkee Kim, Frank Marsiglio

Materials Science and Engineering Faculty Research & Creative Works

Magnetization reversal is a well-studied problem with obvious applicability in computer hard drives. One can accomplish a magnetization reversal in at least one of two ways: application of a magnetic field or through a spin current. The latter is more amenable to a fully quantum-mechanical analysis. We formulate and solve the problem whereby a spin current interacts with a ferromagnetic Heisenberg spin chain, to eventually reverse the magnetization of the chain. Spin flips are accomplished through both elastic and inelastic scattering. A consequence of the inelastic-scattering channel, when it is no longer energetically possible, is the occurrence of a nonequilibrium …

A Novel Approach To Predicting The Lifetime Of Elastomers Undergoing Stress Relaxation, Stephen Ronan

Doctoral

his work opens with a broad overview of several factors influencing the behaviour of elastomeric materials under constant deformation. Following this, an evaluation of the common difficulties surrounding industry-standard lifetime prediction methods is presented. Subsequently, a novel method for the lifetime prediction of stress relaxation in elastomeric materials under constant deformation is introduced. Experimental testing to determine the influence of filler type and content was conducted on several natural rubber materials. The effect of altering the vulcanising agent, crosslink density and mixing time was also examined. Chemiluminescence was used to determine the influence that oxidation has on the overall life …

Assessment Of Electrospinning As An In-House Fabrication Technique For Blood Vessel Mimic Cellular Scaffolding, Colby M. James

Master's Theses

Intravascular devices, such as stents, must be rigorously tested before they can be approved by the FDA. This includes bench top in vitro testing to determine biocompatibility, and animal model testing to ensure safety and efficacy. As an intermediate step, a blood vessel mimic (BVM) testing method has been developed that mimics the three dimensional structure of blood vessels using a perfusion bioreactor system, human derived endothelial cells, and a biocompatible polymer scaffold used to support growth of the blood vessel cells. The focus of this thesis was to find an in-house fabrication method capable of making cellular scaffolding for …

Synthesis And Characterization For A New Organic Cathode Material Of Lithium-Ion Batteries——Poly Sulfurized Chloranilic Acid(Psca), Kai Liu, Jian-Ming Zheng, Gui-Ming Zhong, Yong Yang

Journal of Electrochemistry

A new organic cathode material,poly sulfurized chloranilic acid(PSCA),has been successfully synthesized for lithium-ion batteries. 13C solid state NMR and FTIR results indicated that the chorine in chronailic acid was substituted by sulfur after sulfurization. The electrochemical measurements showed that the initial discharge capacity of PSCA was up to 287.6 mAh/g,and 169.9 mAh/g still remained after 100 cycles when cycled between 1.5～3.6 V at the current density of 15 mA/g.

Silicon Silver Composite Materials For Li-Ion Batteries, Lian-Bang Wang, Xiao-Bo Dai, Xin-Yan Zhu, Xin-Biao Mao, Chun-An Ma

Journal of Electrochemistry

properties of the composites were determined by charge-discharge tests and cyclic voltammetry. The composite composed of Si∶Ag with an atomic ratio of 1∶1 (sample 1#) showed good cyclic stability and charge-discharge reversibility. The reversible capacity of the composite (sample 1#) was remained over 300 mAh·g^-1 after 50 cycles. Experimental results showed that controlling the potential range of charge-discharge processes could enhance the cyclic performance of alloy materials.

Synergism Of Complex Additives Of Dtab+Ktl For Zinc Corrosion Inhibition In Koh Solutions, Sheng-Zhou Lin, Zeng-Xin Cai, Gui-Sheng Wang, He-Bing Zhou, Wei-Shan Li

Journal of Electrochemistry

The electrochemical behaviors of Zn in 3mol/L KOH solution containing several kinds of inhibitors were investigated by weight-loss,electrochemical methods and SEM. The results showed that both the single ad-ditive and the mixed additives can suppress the corrosion of zinc in 3 mol/LKOH solution. And the inhibition ef-feciency of the mixed additives is higher than that of any single additive because of the synergistic effect between KTL and DTAB. The adsorption of DTAB on the surface of zinc has been enhanced in the presence of KTL.

A Study On The Lifepo4/Mwcnts Cathode Materials For Li-Ion Batteries, You-Yi Peng, Hai-Yan Zhang, Chun-Hua He, Wei Xie, Zhi-Feng Zeng

Journal of Electrochemistry

The LiFePO₄/MWCNTs composite was synthesized by ball milling,then the composite electrode was assembled into button lithium-ion batteries.The structure and morphology of the samples,the electrochemical performance of the electrodes were investigated by ways of X-ray diffraction,scanning electron microscopy,cyclic voltammetry and charge-discharge capacity tests. The electrochemical performance of the composite electrodes with different MWNTs contents were studied. The results indicated that the composite electrode containing 10% MWCNTs(by mass)exhibited the most excellent electrochemical performance with the initial charge-discharge capacities of 139 mAh·g^-1,128.5 mAh·g^-1,respectively,and a Kulun efficiency of 92.4% at 0.1C rate under room temperature.Compared to the electrodes …

A Direct Borohydride Fuel Cell With Fecopc2-Catalysed Cathode, Jin-Fu Ma, Yan Liu, Jun-Hua Lai, Yong-Ning Liu

Journal of Electrochemistry

In this paper,a membraneless direct borohydride fuel cell was investigated. Cyclic voltammograms of FeCoPc₂-modified glassy carbon electrode in the alkaline solution show that FeCoPc₂ was active for oxygen reduction reaction. In addition, the steady-state polarization curve tests indicate that FeCoPc₂ had better activity than FePc,CoPc or FePc+CoPc, which is due to its conjugated effect and synergistic effect of Fe and Co. Finally, a maximum power density of 110 mW/cm² was attained, and the 25-day life test shows that the direct borohydride fuel cell had a good stability.

Simultaneous Determination Of Uric Acid(Ua) And Ascorbic Acid(Aa) At Pca/Gc Electrode, Ren Wang, Ying Zhang, Jie Ding

Journal of Electrochemistry

Poly(cinnamic acid)-modified electrode (PCA /GC) was prepared by potentiostatic technique and was used for determination of uric acid (UA),ascorbic acid (AA),and their mixture by cyclic voltammetry. This modified electrode exhibited a potent and persistent electron-mediating behavior followed by well-separated oxidation peaks toward UA and AA at a scan rate of 50 mV·s^-1 with a potential difference of 280 mV,which is large enough to determine UA and AA individually and simultaneously. The catalytic peak current obtained was linearly dependent on the UA and AA concentrations in the range of 2.0×10^-6~1.0×10^-4 mol·L^-1,2.0×10^-5~6.0×10^-4 mol·L …

The Electrochemical Behavior Of Daunorubicin Hydrochloride On Galactic Disk Electrode And Its Reaction With Bsa, Hong-Fen Cheng, Yong Zhang, Jie Liu, Yan-Mei Liu

Journal of Electrochemistry

This article used the linear sweep voltammetry and the circulation voltammetry to study the electrochemical behavior of daunorubicin hydrochloride on galactic disk electrode and its electrode reaction with BSA.Also it studied the interaction of daunorubicin hydrochloride with BSA.The results showed that daunorubicin hydrochloride has a sensitive reduction peak at -0.64 V(vs. SCE) in pH 6.50 Britton-Robinson buffer.The valus of reductions peak current reduced by the addition of BSA to the above mentioned solution.A new electrochemical determination method of bovine serum albumin was developed based on the interaction of daunorubicin hydrochloride with BSA.Furthermore,under the optimized condition,the decrease of the reduction peak …

Redox State Of Polyaniline Nanodot And Its Coulomb Staircase Effect, Jian-Zhang Zhou, Shao-Huang Weng, Zhong-Hua Lin

Journal of Electrochemistry

Polyaniline nanodot array had been fabricated in AAO template with potentiostatic method and the I~V characteristics of nanodots with different redox states were measured by conducting atomic force microscope (C-AFM) in atmosphere at room temperature. We found that only nanodots in partial oxidation state exhibit coulomb staircase in the I~V curves,while those in the full oxidation state and reduced state do not. The above phenomena were discussed preliminarily.

Electrochemical Reduction Of Nitrobenzene In Different Ionic Liquids, Jun-Li Fan, Wei-Lin Ye, Rong Wang, Li-Qun Xu, Xia-Qin Wu

Journal of Electrochemistry

Electrochemical reduction of nitrobenzene at glassy carbon electrode in different ionic liquids,such as N-methylimidazolium-p-toluene sulfonic acid ([Mim][PhSO₃]) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆]) have been investigated by cyclic voltammetry. Experimental results showed that only a cathodic current peak was observed in [Mim][PhSO₃],which is a diffusional controlled irreversible reaction. And two pairs of current peaks were obtained in [Bmim][PF₆] in the same potential range,indicating showed that the reduction products of nitrobenzene were different in different ionic liquids.

Electrochemical Studies On The Ionic Charge Transfer Properties Of The Oxygen Vacancy Defects In The Oxide Films Formed On Titanium, De-Sheng Kong, Hai-Yan Liu, Wen-Juan Fan, Wen-Hua Lv, Zhang-Yu Yu, Yuan-Yuan Feng

Journal of Electrochemistry

The ionic charge transfer properties of the oxygen vacancy point defects in TiO₂ films formed on titanium were studied in 1.0 mol·L^-1 HClO₄ solution with cyclic voltammetry,potentiostatic polarization,galvanostatic reduction and capacitance measurements. The measured capacitance data were analyzed based on the Mott-Schottky equation and Einstein equation. Based on the different response times to the changes of the applied electric field between the ionic and the electronic charge transfers,the diffusion coefficient of the point defects in the anodic oxide film on titanium was estimated. It was shown that the passive potential region for titanium in 1.0 mol·L^{-1 …}

Composite Micro-Porous Polymer Electrolyte Of Pvdf-Hfp Modified By Mcm-48, Wei-Feng Wu, Chang-Chun Yang, Su-Jiao He, Bing-Bing Zhang, Song Xu

Journal of Electrochemistry

The composite micro-porous polymer electrolyte (CMPE) of PVDF-HFP modified by meso-porous molecular sieves of MCM-48 was prepared by phase-inversion process. The ionic conductivity and Li⁺ transference number of the polymer electrolyte were raised,respectively,by 97%(from 0.89 mS/cm to 1.75 mS/cm) and 39%(from 0.57 to 0.79),when 4%(by mass) MCM-48 was added in. Meanwhile,the crystallinity and electrochemical stability of the polymer electrolyte had not been changed by the addition of MCM-48. The charge-discharge efficiency of the button cell assembled with the composite membrane (Li/4%MCM-48-CMPE/LiFePO₄) was 91% in the first cycle,and no loss of capacity was found even after 30 cycles. …

Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger

Other Nanotechnology Publications

The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes …

Crystallization And Electrochemical Corrosion Behaviors Of Amorphous And Nanocrystalline Fe-Based Alloys, Xiang Li, Biao Yan, Peng Dong

Journal of Electrochemistry

In this study,amorphous Fe₇₈Si₁₃B₉ and Fe_73.5Si_13.5B₉Nb₃Cu₁ ribbons were prepared by the chill block melt-spinning process and nanocrystalline Fe_73.5Si_13.5B₉Nb₃Cu₁ ribbons were obtained by annealing. The amorphous ribbons and their crystallization processes were identified by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). A comparative study of the electrochemical corrosion behaviors of  Fe₇₈Si₁₃B₉ and Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous and nanocrystallized alloys was performed by linear polarization method …

Synthesis And Characterization Of Sulfur-Carbonnanotubes As Cathode Of Lithium/Sulfur Rechargeable Battery, Rui Du, Zhong-Zhi Yuan

Journal of Electrochemistry

A carbon-containing composite was synthesized by heating element sulfur and carbon nanotubes. The sulfur-carbonnanotube composites were characterized by X-ray diffraction, SEM, Brunauer-Emmett-Teller. The electrochemical property was characterized by cyclic voltammetry,constant current charge and discharge. It was revealed that the sulfur-carbonnanotube cathode 2016-type coin cells exhibited a good electrochemical property with the initial dicharge specific capacity up to 680 mAh/g and a stable capacity approximately 500 mAh/g after 30 cycle numbers.

Capacitor Property Of Pani/Mwcnt Electrode In Li2So4 Solution, Wen-Bo Cong, Xiao-Shu He

Journal of Electrochemistry

Polyaniline/multi-walled carbon nanotubes (PANI/MWCNT) composites synthesized by chemical oxidation method were characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD) and IR techniques. In 1mol/L Li₂SO₄ neutral solution,the electrochemical performance of the composites electrode was investigated by cyclic voltammetry,galvanostatic charge-discharge tests and ac impedance spectroscopy. The results showed that the composites electrode performed well in 1mol/L Li₂SO₄ solution,the specific capacitance reached 412F/g at 5 mA/cm². The composites electrode possessed better capability of high current than that of PANI electrode,the specific capacitance kept at 318 F/g at 50mA/cm² and was 77.2% of that …

Tungstate/Pertungstate System Cathodic Indirect Oxidation To Synthesis Hydrophobic Monascus Yellow Colorant, Wen-Jian Chen, Xue-Hong Huang, Zhen Chen, Sheng-Bo Ke, You-Zhen Lin

Journal of Electrochemistry

Using SBS-g-(AA/StSO₃Na)/SBS-g-DMAEMA Bipolar Membrane as a separator between the cathode and anode chambers in the electrolysis cell,the optimum conditions of deoxidization of oxygen in cathode were obtained through orthogonal experiment. Then using tungstate/pertungstate as media to indirect electrooxidate hydrophobic monascus red colorant to prepare hydrophobic monascus yellow colorant in cathode. The experiment results show the average current efficiency of cathode was up to 72.39% under the following conditions:that graphite as electrode,10% sulfuric acid as anode electrolyte,0.5 g·L^-1 hydrophobic monascus red colorant solution as cathode electrolyte,tungstate concentration:15 mmol/L,pH=3,flow rate of oxygen:65 cm³/min,electrolyze 2 h under the …

Electrocatalytic Oxidation Of Glucose On Cnt/Nanocrystlline Tio2-Pt Complex Film Electrode In Ionic Liquids, Dao-Bao Chu, Long-Wu Zha, Shu-Xi Wang, Jian Wang, Ying Xiao, Yuan-Yuan Hou, Jian-Guo He, Xue-Jiao Zhang

Journal of Electrochemistry

Using ionic liquid [EMI]BF₄ as the electrolyte,the electrocatalytic oxidation of glucose on carbon nanotubes/nanocrystlline TiO₂ film loaded on Pt (CNT/nanoTiO₂-Pt) complex film electrode was investigated by cyclic voltammetry. The results found that the CNT/nanoTiO₂-Pt complex electrode had high catalytic activity to the electrochemical oxidation of glucose in ionic liquids and the oxidation potential was -0.46 V. The best effect of glucose oxidation was obtained with the volume ratio of ionic liquid to water being 3:1. The process of electrodic reaction process was concentration polarization controlled.