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Articles 32491 - 32520 of 40977

Full-Text Articles in Engineering

Optimization Of A Multi-Echelon Repair System Via Generalized Pattern Search With Ranking And Selection: A Computational Study, Derek D. Tharaldson Mar 2006

Optimization Of A Multi-Echelon Repair System Via Generalized Pattern Search With Ranking And Selection: A Computational Study, Derek D. Tharaldson

Theses and Dissertations

With increasing developments in computer technology and available software, simulation is becoming a widely used tool to model, analyze, and improve a real world system or process. However, simulation in itself is not an optimization approach. Common optimization procedures require either an explicit mathematical formulation or numerous function evaluations at improving iterative points. Mathematical formulation is generally impossible for problems where simulation is relevant, which are characteristically the types of problems that arise in practical applications. Further complicating matters is the variability in the simulation response which can cause problems in iterative techniques using the simulation model as a function …

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An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz Mar 2006

An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz

Theses and Dissertations

Wireless networks have become ubiquitous recently and therefore their usefulness has also become more extensive. Wireless sensor networks (WSN) detect environmental information with sensors in remote settings. One problem facing WSNs is the inability to resupply power to these energy-constrained devices due to their remoteness. Therefore to extend a WSN's effectiveness, the lifetime of the network must be increased by making them as energy efficient as possible. An energy efficient medium access control (MAC) can boost a WSN's lifetime. This research creates a MAC protocol called Adaptive sensor Medium Access Control (AMAC) which is based on Sensor Medium Access Control …

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Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt Mar 2006

Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt

Theses and Dissertations

This research effort examines the theory, application and results of side-looking airborne radar operation in hot clutter. Hot clutter is an electronic counter-measure used to degrade the performance of airborne radar. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. When the received RCS scattered hot clutter waveform is perfectly coherent with the radar waveform, the radar believes the returns created by the hot clutter jammer resulted from the transmitting radar. Hot clutter degrades radar performance at locations in azimuth and Doppler. The effect of hot clutter …

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Active Optical Tracking With Spatial Light Modulators, Steven R. Mawhorter Mar 2006

Active Optical Tracking With Spatial Light Modulators, Steven R. Mawhorter

Theses and Dissertations

Two spatial light modulators are utilized for beam splitting, steering and tracking. Both linear and holographic phase screens are used in a demonstration of technology to allow real time tracking to communicate in a one-to-several type scenario. One SLM is used to apply a linear phase modulation to steer multiple beams onto a detector. The spots that are produced represent the targets as they move around the field of view of the central communication node. A Gerchberg-Saxton algorithm will subsequently use the detected spots as the desired pointing locations. Using this as input, the Gerchberg-Saxton algorithm yields a phase only …

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Multi-Dimensional Wave Front Sensing Algorithms For Embedded Tracking And Adaptive Optics Applications, Christopher C. Wood Mar 2006

Multi-Dimensional Wave Front Sensing Algorithms For Embedded Tracking And Adaptive Optics Applications, Christopher C. Wood

Theses and Dissertations

Current tracking and adaptive optics techniques cannot compensate for fast-moving extended objects, which is important for ground-based telescopes providing space situational awareness. To fill this need, a vector-projection maximum-likelihood wave-front sensing algorithm development and testing follows for this application. A derivation and simplification of the Cramer-Rao Lower Bound for wavefront sensing using a laser guide star bounds the performance of these systems and guides implementation of a vastly optimized maximum-likelihood search algorithm. A complete analysis of the bias, mean square error, and variance of the algorithm demonstrates exceptional performance of the new sensor. A proof of concept implementation shows feasibility …

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Lqg/Ltr Tilt And Tip Control For The Starfire Optical Range 3.5-Meter Telescope's Adaptive Optics System, Neil D. Paris Mar 2006

Lqg/Ltr Tilt And Tip Control For The Starfire Optical Range 3.5-Meter Telescope's Adaptive Optics System, Neil D. Paris

Theses and Dissertations

The Air Force Research Laboratory has sponsored research on the tracking control loop portion of the adaptive optics system in the Starfire Optical Range 3.5-meter telescope at Kirtland Air Force Base. The control loop includes two steering mirrors (Coarse Steering Mirror and Fine Steering Mirror) used to remove wavefront tilt and tip phase distortion from light entering the telescope. The objective of this research is to design a single Linear Quadratic Gaussian controller to control both steering mirrors in order to eliminate wavefront tilt and tip distortions induced by the earth's atmosphere, and to evaluate the stability robustness and performance …

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Characteristics Of Two-Dimensional Triangular And Three-Dimensional Face-Centered-Cubic Photonic Crystals, Jeffery D. Clark Mar 2006

Characteristics Of Two-Dimensional Triangular And Three-Dimensional Face-Centered-Cubic Photonic Crystals, Jeffery D. Clark

Theses and Dissertations

The fabrication of photonic crystals (PhC) with photonic band gaps (PBG) in the visible range is a difficult task due to the small structural feature sizes of the PhC. The particular type of PhC examined is a two-dimensional (2-D) triangular structure with a PBG designed for visible wavelengths with applications in visible integrated photonic systems. This work examines the processes involved and viability of fabricating 2-D triangular PhC's by a variety of techniques: focused ion beam, electron lithography and holographic photo-polymerization/lithography. The design of the PhC was based on a program created to display gap maps for triangular structures. The …

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Analysis Of Bacterial Population And Distribution In The Developing Strata Of A Constructed Wetland Used For Chlorinated Ethene Bioremediation, Milton J. Clausen Jr. Mar 2006

Analysis Of Bacterial Population And Distribution In The Developing Strata Of A Constructed Wetland Used For Chlorinated Ethene Bioremediation, Milton J. Clausen Jr.

Theses and Dissertations

Chlorinated hydrocarbons and their degradation products are among of the most common organic groundwater contaminates in the United States. These compounds attack the central nervous system in animals and can affect the photosynthesis of plants. These compounds are also resistant to degradation in the environment and, because of this, pose a risk to any ecosystem in which they are present. This study identified the dominant microbial species in a constructed treatment wetland at Wright-Patterson AFB, Dayton, Ohio using 16S rRNA gene sequence analysis. Samples were taken from three different depths and during each of the four seasons. These samples were …

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Spatially-Resolved Temperature Diagnostic For Supersonic Flow Using Cross-Beam Doppler-Limited Laser Saturation Spectroscopy, Grady T. Phillips Mar 2006

Spatially-Resolved Temperature Diagnostic For Supersonic Flow Using Cross-Beam Doppler-Limited Laser Saturation Spectroscopy, Grady T. Phillips

Theses and Dissertations

Optical techniques for measuring the temperature in three-dimensional supersonic reactive flows have typically depended on lineshape measurements using single-beam laser absorption spectroscopy. However, absorption over extended path lengths in flows with symmetric, turbulent eddies can lead to systematically high extracted temperatures due to Doppler shifts resulting from flow along the absorption path. To eliminate these problems, Cross-Beam Saturation Absorption Spectroscopy (CBSAS) and Cross-Beam Inter-Modulated Fluorescence (CBIMF) have been developed which utilize two crossed and nearly copropogating laser beams.to record the spectral signal of an I2 ro-vibrational line in a small three-dimensional volume using a tunable CW dye laser. Temperature …

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Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks Mar 2006

Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks

Theses and Dissertations

The depth of absorption bands in observed spectra of distant, bright sources can be used to estimate range to the source. A novel approach is presented and demonstrated using observations of the oxygen absorption band near 762 nm. Range is estimated by comparing observed values of band-average absorption against curves derived from either historical data or model predictions. Curves are based on fitting a random band model to the data, which reduces average range error by 67% compared to the Beer's Law model used in previous work. A new modification to existing band models for long, inhomogeneous paths is presented …

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Doppler-Only Multistatic Radar, Dustin G. Mixon Mar 2006

Doppler-Only Multistatic Radar, Dustin G. Mixon

Theses and Dissertations

In order to estimate the position and velocity of a target, most multistatic radar systems require multiple independent target measurements, such as angle-of-arrival, time-of-arrival, and Doppler information. Though inexpensive and reliable, Doppler-only systems have not been widely implemented due to the inherent nonlinear problem of determining a target’s position and velocity from their measurements. We solve this problem. In particular, we first establish the lack of observability in the Doppler-only bistatic system, thereby demonstrating the need for multiple transmitters and/or receivers. Next, for a multistatic system with a sufficient number of transmitter-receiver pairs, we invoke classical optimization techniques, such as …

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A Climatological Study Of Equatorial Gps Data And The Effects On Ionospheric Scintillation, Katharine A. Wicker Mar 2006

A Climatological Study Of Equatorial Gps Data And The Effects On Ionospheric Scintillation, Katharine A. Wicker

Theses and Dissertations

Ionospheric scintillation is detrimental to radio signals, especially those from the global positioning system. Such scintillation is caused when a signal permeates the ionosphere through plasma bubbles. The signal’s phase and amplitude can be altered, and a receiver on the ground can lose lock on the GPS signal. Measured using a zero to one index known as S4, scintillation severity is based upon season, solar cycle, time of day, location and frequency. The most severe scintillation occurs at the equatorial anomaly, or fifteen degrees north and south of the equator. Seven years of data from fifteen different locations around the …

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Quantitative Object Reconstruction Using Abel Transform Tomography And Mixed Variable Optimization, Kevin R. O'Reilly Mar 2006

Quantitative Object Reconstruction Using Abel Transform Tomography And Mixed Variable Optimization, Kevin R. O'Reilly

Theses and Dissertations

Researchers at the Los Alamos National Laboratory (LANL) are interested in quantitatively reconstructing an object using Abel transform x-ray tomography. Specifically, they obtain a radiograph by x-raying an object and attempt to quantitatively determine the number and types of materials and the thicknesses of each material layer. Their current methodologies either fail to provide a quantitative description of the object or are generally too slow to be useful in practice. As an alternative, the problem is modeled here as a mixed variable programming (MVP) problem, in which some variables are nonnumeric and for which no derivative information is available. The …

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Control Demonstration Of A Thin Deformable In-Plane Actuated Mirror, Gina A. Peterson Mar 2006

Control Demonstration Of A Thin Deformable In-Plane Actuated Mirror, Gina A. Peterson

Theses and Dissertations

Current imaging satellites are limited in resolution and coverage area by the aperture size of their primary optical mirror. To get a large optical mirror into space, current launch weight and size restrictions must be overcome. Membrane-like optical mirrors can overcome these restrictions with their very lightweight and flexible properties. However, thin, deformable membrane mirrors are very susceptible to the space environment and require active control for surface stabilization and shaping. The primary goal of this research is to demonstrate that an in-plane actuated membrane-like deformable optical mirror can be controlled to optical wavelength tolerances in a closed-loop system. Fabrication …

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A Comparison Of Main Rotor Smoothing Adjustments Using Linear And Neural Network Algorithms, Nathan A. Miller Mar 2006

A Comparison Of Main Rotor Smoothing Adjustments Using Linear And Neural Network Algorithms, Nathan A. Miller

Theses and Dissertations

Helicopter main rotor smoothing is a maintenance procedure that is routinely performed to minimize airframe vibrations induced by non-uniform mass and/or aerodynamic distributions in the main rotor system. This important task is both time consuming and expensive, so improvements to the process have long been sought. Traditionally, vibrations have been minimized by calculating adjustments based on an assumed linear relationship between adjustments and vibration response. In recent years, artificial neural networks have been trained to recognize non-linear mappings between adjustments and vibration response. This research was conducted in order observe the character of the adjustment mapping of the Vibration Management …

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Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang Feb 2006

Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang

Journal of Electrochemistry

A new procedure of surface activation without using palladium salt was proposed for electroless nickel plating on carbon nanotubes.In the procedure,carbon nanotubes were oxidized by nitric acid and then neutralized with NaOH to create carboxyl surface groups which were used to adsorb Ni2+ ions,thereafter the adsorbed Ni2+ ions were chemically reduced into Ni nano-particles as a catalytic center for electroless nickel deposition,all these were further confirmed by infrared absorption spectra and electron microscopic observations.The results indicate that the procedure is feasible to electroless nickel plating on carbon nanotubes.The different morphology of deposits obtained from electroless plating was also …

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Conductivity Of Comb Polyether Pure Solid Polymer Electrolyte, Lin Ye, Peng Gao, Zeng-Guo Feng, Feng Wu, Shi Chen, Guo-Qing Wang Feb 2006

Conductivity Of Comb Polyether Pure Solid Polymer Electrolyte, Lin Ye, Peng Gao, Zeng-Guo Feng, Feng Wu, Shi Chen, Guo-Qing Wang

Journal of Electrochemistry

A comb polymer was synthesized through cationic ring-opening polymerization starting from a monomer 3-hydroxymethyl-3-methyl-oxetane.The ion conductivity was measured by CHI660A electrochemical station under various lithium salt concentrations and various temperatures.The highest ion conductivity was recorded to be 10-4.43 S/cm at room temperature and 10-3.44 S/cm at 80 ℃.DSC results showed that the segment moves more difficultly with the increasing of lithium salts concentration.XPS found the existence of aggregating lithium ions in POE5 and POE10,and it suggested that POE20 had a suitable lithium concentration for polymer electrolyte.

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Studies On Pva-Cmc-Koh-H2O Alkaline Polymer Electrolytes, An-Bao Yuan, Jun Zhao Feb 2006

Studies On Pva-Cmc-Koh-H2O Alkaline Polymer Electrolytes, An-Bao Yuan, Jun Zhao

Journal of Electrochemistry

A given amount of sodium carboxymethyl cellulose(CMC)was added to PVA complex and thus the PVA-CMC-KOH-H2O alkaline polymer electrolyte with this modification was prepared.The properties of the polymer electrolyte films were characterized by AC impedance,cyclic voltammetry,differential thermal analysis and infrared spectroscopic analysis methods.The polymer electrolyte exhibited a high ionic conductivity,typically 10-2S·cm-1 with an electrochemical stability window of about 1.6 V on stainless steel blocking electrodes.The influence of the film composition such as KOH,H2O and CMC on ion conductivity was investigated.In addition,a preliminary study was carried out on the polymer electrolyte for Ni/MH battery.It was …

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Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng Feb 2006

Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng

Journal of Electrochemistry

The anodic behaviors of Pb-Ca-Sn-Re and Pb-Ca-Sn alloys were investigated at 1.28 V(vsHg/(H2SO4)) in 4.5 mol/L sulfuric acid solution by means of ac voltammetry,ac impedance and cyclic voltammetry.The results showed that the corrosion-resistance property of Pb-Ca-Sn-Re alloy is better than that of tradditional Pb-Ca-Sn alloy,the growth of Pb(Ⅱ) compounds was inhibited in the film of Pb-Ca-Sn-Re alloy,and the film impedance of Pb-Ca-Sn-Re alloy was decreased,indicating that the conductivity of the film was(increased),which is helpful to enhance the deep recycling property for lead acid battery.

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Mechanism Of Self Discharge Performance Improvement In The Ni-Mh Batteries With Naoh Electrolyte, Xiao-Feng Li, Tong-Chi Xia, Hui-Chao Dong, Yan-Wei Wei Feb 2006

Mechanism Of Self Discharge Performance Improvement In The Ni-Mh Batteries With Naoh Electrolyte, Xiao-Feng Li, Tong-Chi Xia, Hui-Chao Dong, Yan-Wei Wei

Journal of Electrochemistry

The self-discharge performance and charge efficiency at 60 ℃ for Ni-MH battery can be markedly enhanced by using NaOH electrolyte instead of KOH electrolyte.Both the results of electrochemical impedance spectroscopy and cyclic voltammetry tests indicate that the separation of H2 from the negative electrode may be partly blocked in the former because of the change of the adsorption/desorption behavior of H on the surface of the negative electrode,thus results in an improvement of self-discharge performance of the battery.

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2006 National Conference On Corrosion Electrochemistry And Measuring Methods, Editorial Office Of J.Electrochem. Feb 2006

2006 National Conference On Corrosion Electrochemistry And Measuring Methods, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

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Electrochemistry And Structures Of Silicon Surface, Gregory X.Zhang Feb 2006

Electrochemistry And Structures Of Silicon Surface, Gregory X.Zhang

Journal of Electrochemistry

Accurate control and fabrication of silicon surface structures from atomic scale to micrometer scale,which may be randomly associated with surface roughness or have well defined patterns,is critical for the per-formance and reliability of electronic devices.Electrochemical reactions of silicon in solutions involved in wetcleaning and etching of silicon wafer play an importantrole in determining the structures of silicon surface.Atre-mendous amount of researches have been done in the last several decades to understand and control a range ofcomplex electrochemical reactions at silicon/solution interface and their relations to the resulted surface struc-tures.The findings generated from these research efforts have been compiled and integrated …

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Development On Hydriding/Dehydriding Kinetics Of Mg Nano-Materials For Hydrogen Storage, Wei Mo, Hong-Liang Sun, Hai-Chang Zhang, Hua-Bin Yang, Zuo-Xiang Zhou Feb 2006

Development On Hydriding/Dehydriding Kinetics Of Mg Nano-Materials For Hydrogen Storage, Wei Mo, Hong-Liang Sun, Hai-Chang Zhang, Hua-Bin Yang, Zuo-Xiang Zhou

Journal of Electrochemistry

The development of Mg nano-materials for hydrogen storage in the recent decade has been reviewed in this paper.It was shown the Mg nano-powders prepared by high-energy ball milling showed promising hydriding and dehydriding performance with the transition metal oxides and other types of hydrogen storage alloys(ABx)as the catalysts.

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Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen Feb 2006

Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen

Journal of Electrochemistry

Nano Pt/C electrocatalysts were prepared by intermittent microwave heating method.The electrooxidation of glucose on smooth Pt and～Pt/C electrodes has been studied and compared.The results showed that the electrochemical properties on nano Pt/C were improved due to the reduction of the overpotential and the increase in the kinetic rate.The surface area would be significantly increased when the particle size of the catalyst was reduced to nano-scale,resulting in the increase in the activity.The enhancement in the resistance to poisoning could be explained that the oxygen-containing species are easier to react with poisoning species on nano Pt/C and re-active the electrode.

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Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du, Chang-Jian Lin Feb 2006

Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The anticorrosion action of EDA on copper in dilute HCl solution and the effect of sulfide ions on the inhibiting efficiency were studied by the Tafel plot method.The corrosion potential of Cu shifted to more positive value and the corrosion current density decreased after the addition of Na2S to the solution.The results indicated that sulphide ions could increase the inhibiting efficiency of EDA because of the synergistic inhibition effect between EDA and Na2S,resulting from the adsorption of HS- on the surface of Cu,facilitated the adsorption of EDA to form a highly protective adsorbed layer which …

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The Complex Of Pasp And Tungstate As Inhibitors Of Cupronickel B10′S Corrosion In 3% Nacl Solution, Qun-Jie Xu, Guo-Ding Zhou, Hui-Feng Wang, Wen-Bin Cai Feb 2006

The Complex Of Pasp And Tungstate As Inhibitors Of Cupronickel B10′S Corrosion In 3% Nacl Solution, Qun-Jie Xu, Guo-Ding Zhou, Hui-Feng Wang, Wen-Bin Cai

Journal of Electrochemistry

AC impedance and polarization curve measurements were conducted to study the effects of environ-ment-friendly inhibitors PASP,Na2WO4 and their complexes on the corrosion of cupronickel B10 in 3%NaCl solution.The results indicate that PASP or Na2WO4 alone does inhibit the corrosion of B10,and most effectiveconcentrations are 40 mg/L and 60 mg/L for PASP and Na2WO4,respectively.With the total concentration of 40mg/L for the complex inhibitors,the optimum complex ratio of PASP to Na2WO4 was 3:1.The complex of such a combination showed a significantly synergetic inhibition effect on the corrosion of B10.

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The Effect Of Solution Concentration On Properties Of Ru-Ti-Ir Oxide Anode Coatings, Ke Wang, Yan Han, Jun-Tao Wang, Xiao-Ling Zhang, Yu-Pu Sun Feb 2006

The Effect Of Solution Concentration On Properties Of Ru-Ti-Ir Oxide Anode Coatings, Ke Wang, Yan Han, Jun-Tao Wang, Xiao-Ling Zhang, Yu-Pu Sun

Journal of Electrochemistry

The anode coatings of Ru-Ti-Ir oxide with various solution concentrations were prepared by thermal decomposition.The scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD),accelerated life,polarization curve,cyclic voltammetry and electrochemical impedance.spectroscopy(EIS)tests were carried out.The results showed that there was an obvious effect of solution concentrations on the morphology of the coatings,but little effect on polarization of chlorine evolution.Voltammetric charges and double layer capacitances of anode coatings had a tendency to fall down firstly then increase afterwards as the solution concentration increased.

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Electrochemical Reduction Behavior Of Benzaldehyde In The Ionic Liquids, Ning Zhao, Wen-Ju Dong, Qi-Zeng Shi Feb 2006

Electrochemical Reduction Behavior Of Benzaldehyde In The Ionic Liquids, Ning Zhao, Wen-Ju Dong, Qi-Zeng Shi

Journal of Electrochemistry

In this paper, the electrochemical reduction of benzaldehyde was investigated in C4MIMBF4, C6MIMBF4  and C8MIMBF4 ionic liquids by cyclic linear sweep voltammetry,cyclic square-wave voltammetry and chronocoulometry.Benzaldehyde exhibits two successive one-electron irreversible reduction(EP1=-1.39 V, EP2=1.69 V) with GC electrode in C4MIMBF4, the voltammetric data for benzaldehyde give diffusion coefficients of 1.5*10-8cm2/s and 1.3*108cm2/s. There is one current peak in C6MIMBF4  and C8MIMBF4 ionic liquids due to their stronger alkalinity …

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Oxygen Enrichment Effect Of Ceo2 To The Cathode Performance Of Proton Exchange Membrane Fuel Cell, Xiang-Li Hou, Hong-Feng Xu, Jian-Hua Dong, Xin Sun Feb 2006

Oxygen Enrichment Effect Of Ceo2 To The Cathode Performance Of Proton Exchange Membrane Fuel Cell, Xiang-Li Hou, Hong-Feng Xu, Jian-Hua Dong, Xin Sun

Journal of Electrochemistry

CeO2 was added to Pt/C catalyst in the cathode of PEMFC by both sol and impregnation methods.The samples were evaluated by TEM,cyclic voltammogram techniques and proton exchange membrane fuel cell performance test.The addition of CeO2 obviously improved the performance of PEMFC and represented a notable function of oxygen enrichment in the cathode side.But with the addition of CeO2,part of the catalyst surface was covered and led to the performance drop of the PEMFC.The best content of CeO2 is 1% when it is added by impregnation method and 3% when it is added by sol method.

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Effects Of Srb Biofilm And Corrosion Product Films On Corrosion Behavior Of Carbon Steel, Jing Lin, Yong-Gui Yan, Guang-Zhang Chen, Guang-Zhou Liu, Qing-Fen Li Feb 2006

Effects Of Srb Biofilm And Corrosion Product Films On Corrosion Behavior Of Carbon Steel, Jing Lin, Yong-Gui Yan, Guang-Zhang Chen, Guang-Zhou Liu, Qing-Fen Li

Journal of Electrochemistry

Electrochemical techniques and surface analysis techniques were applied to study corrosion characteristic of A3 steel.The effects on corrosion behavior of A3 steel by sulfate-reducing bacteria(SRB)(biotic media)and corrosion product(abiotic media)were studied.The results showed that biofilms and corrosion product films play different role during different stages.Biofilms were easier flaky with increasing of its thickness.Non-uniform biofilms reduced pitting corrosion of the specimens.The corrosion product films formed under abiotic conditions were more adherently to the surface of the metal than those formed in biogenic media.

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