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Articles 31081 - 31110 of 40994

Full-Text Articles in Engineering

Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck Mar 2008

Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck

Physics Faculty Publications and Presentations

Two novel (and proprietary) strategies for the structural identification of a nanocrystal from either a single high-resolution (HR) transmission electron microscopy (TEM) image or a single precession electron diffraction pattern are proposed and their advantages discussed in comparison to structural fingerprinting from powder X-ray diffraction patterns. Simulations for cubic magnetite and maghemite nanocrystals are used as examples.

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Automatic Drift Compensation Using Phase Correlation Method For Nanomanipulation, Qinmin Yang, Jagannathan Sarangapani, Eric W. Bohannan Mar 2008

Automatic Drift Compensation Using Phase Correlation Method For Nanomanipulation, Qinmin Yang, Jagannathan Sarangapani, Eric W. Bohannan

Electrical and Computer Engineering Faculty Research & Creative Works

Nanomanipulation and nanofabrication with an atomic force microscope (AFM) or other scanning probe microscope (SPM) are a precursor for nanomanufacturing. It is still a challenging task to accomplish nanomanipulation automatically. In ambient conditions without stringent environmental controls, the task of nanomanipulation requires extensive human intervention to compensate for the spatial uncertainties of the SPM. Among these uncertainties, the thermal drift, which affects spatial resolution, is especially hard to solve because it tends to increase with time, and cannot be compensated simultaneously by feedback from the instrument. In this paper, a novel automatic compensation scheme is introduced to measure and estimate …

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Effects Of Ionic Strength, Temperature, And Ph On Degradation Of Selected Antibiotics, Keith A. Loftin, Craig D. Adams, Michael T. Meyer, Rao Surampalli Mar 2008

Effects Of Ionic Strength, Temperature, And Ph On Degradation Of Selected Antibiotics, Keith A. Loftin, Craig D. Adams, Michael T. Meyer, Rao Surampalli

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Aqueous degradation rates, which include hydrolysis and epimerization, for chlorretracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin a (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na2HPO4), temperature (7, 22, and 35°C), and pH (2, 5, 7, 9, and 11). Multiple linear regression revealed that ionic strength did not significantly affect (α = 0.05) degradation rates for all compounds, but temperature and pH affected rates for CTC, OTC, and TET significand (α = 0.05). Degradation also was observed for TYL at pH 2 …

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Output Feedback Controller For Operation Of Spark Ignition Engines At Lean Conditions Using Neural Networks, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier Mar 2008

Output Feedback Controller For Operation Of Spark Ignition Engines At Lean Conditions Using Neural Networks, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

Spark ignition (SI) engines operating at very lean conditions demonstrate significant nonlinear behavior by exhibiting cycle-to-cycle bifurcation of heat release. Past literature suggests that operating an engine under such lean conditions can significantly reduce NO emissions by as much as 30% and improve fuel efficiency by as much as 5%-10%. At lean conditions, the heat release per engine cycle is not close to constant, as it is when these engines operate under stoichiometric conditions where the equivalence ratio is 1.0. A neural network controller employing output feedback has shown ability in simulation to reduce the nonlinear cyclic dispersion observed under …

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Digital Signal Processing Leveraged For Intrusion Detection, Theodore J. Erickson Mar 2008

Digital Signal Processing Leveraged For Intrusion Detection, Theodore J. Erickson

Theses and Dissertations

This thesis describes the development and evaluation of a novel system called the Network Attack Characterization Tool (NACT). The NACT employs digital signal processing to detect network intrusions, by exploiting the Lomb-Scargle periodogram method to obtain a spectrum for sampled network traffic. The Lomb-Scargle method for generating a periodogram allows for the processing of unevenly sampled network data. This method for determining a periodogram has not yet been used for intrusion detection. The spectrum is examined to determine if features exist above a significance level chosen by the user. These features are considered an attack, triggering an alarm. Two traffic …

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Hardware Algorithm Implementation For Mission Specific Processing, Jason W. Shirley Mar 2008

Hardware Algorithm Implementation For Mission Specific Processing, Jason W. Shirley

Theses and Dissertations

There is a need to expedite the process of designing military hardware to stay ahead of the adversary. The core of this project was to build reusable, synthesizeable libraries to make this a possibility. In order to build these libraries, Matlab® commands and functions, such as Conv2, Round, Floor, Pinv, etc., had to be converted into reusable VHDL modules. These modules make up reusable libraries for the Mission Specific Process (MSP) which will support AFRL/RY. The MSP allows the VLSI design process to be completed in a mere matter of days or months using an FPGA or ASIC design, as …

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Signal Processing Design Of Low Probability Of Intercept Waveforms, Nathaniel C. Liefer Mar 2008

Signal Processing Design Of Low Probability Of Intercept Waveforms, Nathaniel C. Liefer

Theses and Dissertations

This thesis investigates a modification to Differential Phase Shift Keyed (DPSK) modulation to create a Low Probability of Interception/Exploitation (LPI/LPE) communications signal. A pseudorandom timing offset is applied to each symbol in the communications stream to intentionally create intersymbol interference (ISI) that hinders accurate symbol estimation and bit sequence recovery by a non-cooperative receiver. Two cooperative receiver strategies are proposed to mitigate the ISI due to symbol timing offset: a modified minimum Mean Square Error (MMSE) equalization algorithm and a multiplexed bank of equalizer filters determined by an adaptive Least Mean Square (LMS) algorithm. Both cooperative receivers require some knowledge …

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Semantic Components: A Model For Enhancing Retrieval Of Domain- Specific Information, Susan Loucette Price Mar 2008

Semantic Components: A Model For Enhancing Retrieval Of Domain- Specific Information, Susan Loucette Price

Dissertations and Theses

Despite the success of general Internet search engines, information retrieval remains an incompletely solved problem. Our research focuses on supporting domain experts when they search domain-specific libraries to satisfy targeted information needs. The semantic components model introduces a schema specific to a particular document collection. A semantic component schema consists of a two-level hierarchy, document classes and semantic components. A document class represents a document grouping, such as topic type or document purpose. A semantic component is a characteristic type of information that occurs in a particular document class and represents an important aspect of the document’s main topic. …

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Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican Mar 2008

Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican

Theses and Dissertations

The current research is focused on the design and fabrication of an electrically programmable diffraction grating using standard micro electro mechanical systems (MEMS) technology. The goal is to design a beam steering element required to build very small hyperspectral imaging (HSI) sensors. The diffraction grating will be used to perform beam-dispersion - a critical step in the imaging process. The proposed transmissive diffraction grating based approach will minimize the overall size and the number of components in the physical design of the hyperspectral imagers, thereby enabling us to exploit the traditional advantages of MEMS such as increased reliability, smaller size, …

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Multi-Class Classification Fusion Using Boosting For Identifying Steganography Methods, Benjamin M. Rodriguez, Gilbert L. Peterson Mar 2008

Multi-Class Classification Fusion Using Boosting For Identifying Steganography Methods, Benjamin M. Rodriguez, Gilbert L. Peterson

Faculty Publications

No abstract provided.

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Cu Doping Lifepo4 And Its Electrochemical Performance, Ming-Sen Zheng, Shan-Ke Liu, Shi-Gang Sun, Quan-Feng Dong Feb 2008

Cu Doping Lifepo4 And Its Electrochemical Performance, Ming-Sen Zheng, Shan-Ke Liu, Shi-Gang Sun, Quan-Feng Dong

Journal of Electrochemistry

LiFePO4 and LiFePO4 doped with Cu2+ ions were synthesized by solid-state reactions.The structure of LiFePO4 and the Fe valence were analyzed by the XRD(X-ray diffraction) and XPS(X-ray photoelectron spectroscopy) respectively.The Cu doping position in LiFePO4 is discussed.It has found that the volume of LiFePO4 by doping Cu2+ ions is reduced.The minim Cu2+ ions doping does not almost change the binding energy of Fe2p1/2 in LiFePO4.According to the experiment results,we conclude that most of the Cu2+ ions substitute the Fe2+ ions in LiFePO4 when a …

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A Study On Supercapacitor Based On Aligned Carbon Nanotubes, Xiao-Yan Ye, Yan-Zhi Wang, Hai-Yan Song, Zhuo Sun, Pin-Gang He, Yu-Zhi Fang Feb 2008

A Study On Supercapacitor Based On Aligned Carbon Nanotubes, Xiao-Yan Ye, Yan-Zhi Wang, Hai-Yan Song, Zhuo Sun, Pin-Gang He, Yu-Zhi Fang

Journal of Electrochemistry

Large scale vertically aligned carbon nanotubes(ACNTs) with uniform length and diameter were prepared by the pyrolysis of iron(Ⅱ) phthalocyanine at low pressure.The ACNTs were activated by electrolyte-activation,acid-activation or electrochemical activation.The performance of the capacitor based on activated ACNTs was characterized by cyclic voltammograms which was of rectangular shape,impedence spectroscopy in which the phase is above 80° and the result specific capacitance was 16～32 F/g,which suggest that the ACNTs are the promising material for the supercapacitor.

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Preparation And Electrochemical Performance Of Ordered Mesoporous Titanium Phosphate As Cathode Material For Li-Ion Battery, Qiong Wang, Attia Adel, Zhi-Cong Shi, Yong Yang Feb 2008

Preparation And Electrochemical Performance Of Ordered Mesoporous Titanium Phosphate As Cathode Material For Li-Ion Battery, Qiong Wang, Attia Adel, Zhi-Cong Shi, Yong Yang

Journal of Electrochemistry

Ordered porous titanium phosphate materials were prepared by using the surfactant template combined with the sol-gel method. The samples were characterized by small angle X-ray diffraction(SA-XRD) method, N2 adsorption/desorption techniques,high resolution transmission electron microscopy(HRTEM) and element analysis. It is found that the calcination temperature is a big influence on the porous structure, and electrochemical performance of the titanium phosphate materials, and the mesoporous titanium phosphate showed good performance in the electrochemical test, the first discharge capacity is 94 mAh/g at the current density of 150 mA/g. On the other hand, the no porous material with a low capacity of …

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Synthesis Of Adipic Acid From Cyclohexanol By Electrochemical Oxidation Using Cr2O72-/Cr3+ As Indirect Oxidant, Zhen-Hai Liang, Yu-Qing Cui, Hong-Yan Sun Feb 2008

Synthesis Of Adipic Acid From Cyclohexanol By Electrochemical Oxidation Using Cr2O72-/Cr3+ As Indirect Oxidant, Zhen-Hai Liang, Yu-Qing Cui, Hong-Yan Sun

Journal of Electrochemistry

Adipic acid was synthesized by electro-oxidation of cyclohexanol taking Cr2O72-/Cr3+ as indirect oxidant.The best technological conditions were optimized by orthogonal experiment.The optimum condition are as follows: the temperature is 35 ℃,ratio of crude material is n(cyclohexanol)∶n(Cr2O72-)=0.4∶1 and concentration of H2SO4 is 4 mol·L-1.Under these conditions,the yield of adipic acid can reach 70.29%.Moreover,The effects of concentration of Ag2SO4,(NH4)2SO4,H2SO4and current density on the formation of Cr2O72-were also …

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Mechanism Of The Cathode Reduction Of Ti(Ⅳ) In Molten Na3Alf6-Alf3, Hai-Bin Sun, Xiu-Rong Zuo, Zhi-Guo Zhong, Xue-Hui Hu Feb 2008

Mechanism Of The Cathode Reduction Of Ti(Ⅳ) In Molten Na3Alf6-Alf3, Hai-Bin Sun, Xiu-Rong Zuo, Zhi-Guo Zhong, Xue-Hui Hu

Journal of Electrochemistry

The mechanism of TiO2 electrode process has been investigated by cyclic voltammetry and chronopotentiometry on the tungsten filament in molten Na3AlF6-AlF3 salts at 990 ℃.The experimental results showed that electrochemical reduction of Ti(Ⅳ) precede were two steps,firstly Ti(Ⅳ) was reduced to Ti(Ⅱ),then Ti(Ⅱ) was reduced to Ti,namely: Ti(Ⅳ)→Ti(Ⅱ)→Ti.

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Interfacial Electrochemical Behavior Of Fibrinogen On Pt Electrode, Song-Mei Chen, Jian-Zhang Zhou, Zhong-Hua Lin, Dong-Mei Zeng, Nan Huang, Guo-Jiang Wan Feb 2008

Interfacial Electrochemical Behavior Of Fibrinogen On Pt Electrode, Song-Mei Chen, Jian-Zhang Zhou, Zhong-Hua Lin, Dong-Mei Zeng, Nan Huang, Guo-Jiang Wan

Journal of Electrochemistry

The interfacial electrochemical behaviors of fibrinogen on Pt electrode in phosphate buffered solution(PBS) was investigated by using cyclic voltammetry and electrochemical in-situ FTIR spectroscopy.The cyclic voltammetry results demonstrated that the fibrinogen adsorb on Pt electrode and impede the interfacial charge transfer of hydrogen ion reaction process as well as of oxygen reduction process,which is increased with higher scan rate.The cyclic voltammetry spectra of platinum absorbed with fibrinogen in K3[Fe(CN)6] and K4[Fe(CN)6]·3H2O solutions shows that the fibrinogen can partly decrease the oxidation and reduction current peaks.There is no specific anodic and …

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Molten Salt Treatment Of Mno2 And Investigation On Supercapacitor Properties, Ye Chen, Zun-Bo Zhang, Wei Zhang, Liang Liu, Zhi-Min Liu Feb 2008

Molten Salt Treatment Of Mno2 And Investigation On Supercapacitor Properties, Ye Chen, Zun-Bo Zhang, Wei Zhang, Liang Liu, Zhi-Min Liu

Journal of Electrochemistry

The MnO2 prepared by solid phase method is treated by KCl-NaCl-LiCl molten salt system.The XRD patterns indicated that the crystal structures of MnO2 sample have had the α-MnO2 and γ-MnO2 phase,the crystallinity of sample is increased after treated by molten salt.The electrochemical properties were tested by cyclic voltammetry,constant current charge/discharge and AC impedance.The result shows that the supercapacitor performance of the treated material has improved.The specific discharge capacitance of the treated sample are 129.07 F·g-1,increased by 27.88% compared to 100.94 F·g-1 of untreated sample.Long cycle life and high coulombic efficiency were also demonstrated …

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Potentiometric Response Of Glucose On Mno2-GoX Carbon Paste Electrode, Cai-Juan Wang, Xiao-Ya Hu Feb 2008

Potentiometric Response Of Glucose On Mno2-GoX Carbon Paste Electrode, Cai-Juan Wang, Xiao-Ya Hu

Journal of Electrochemistry

A novel carbon paste electrode(CPE) modified with MnO2 and glucose oxidase(GOx), is reported. Different factors, such as the effect of supporting electrolyte, pH of solutions,various paste glues, the amount of MnO2 and temperature, which may influence the determination of H2O2 and glucose were tested to optimize. Based on above, potentiometric determination of glucose was achieved in neutral solution and at 35 ℃, the electrode gave a response of 36.12～34.62 mV/pG lucose between 2.0×10-5 mol·L-1 and 5.2×10-3 mol·L-1 with a detection limit of 3.3×10-6 mol·L-1. Moreover, this kind …

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Square Wave Stripping Voltammetric Behaviors Of Rutin On Glassy Carbon Electrode And Its Application, Jun Hua, Xiao-Ying He, Fang Liao, Qing-Tao Zhu Feb 2008

Square Wave Stripping Voltammetric Behaviors Of Rutin On Glassy Carbon Electrode And Its Application, Jun Hua, Xiao-Ying He, Fang Liao, Qing-Tao Zhu

Journal of Electrochemistry

The electrochemical behaviors of rutin(Rt) at glassy carbon electrode were studied by square wave stripping voltammeter in the presence of 0.1mol·L-1HAc-NaAc buffer solution(pH=3.0).The sensitive oxidation peak of rutin was observed and which potential peak is 0.46V(vs.SCE).The experimental parameters,such as pH value,deposition potential and deposition time were investigated and selected.The peak currents were proportional to the concentration of rutin in range of 5.0×10-8 mol·L-1~1.0×10-6mol·L-1,and the linear regression coefficient equaled 0.99799,the detection limit was 1.1×10-8 mol·L-1.This method was applied to the determination of rutin content in tablet with satisfactory results.

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Corrosion Electrochemical Behavior Of Az31 And Az61 Magnesium Alloys In Simulated Sea Water, Ling-Jie Li, Sheng-Hai Yu, Jing-Lei Lei, Chuan-Pu Liu, Sheng-Tao Zhang, Fu-Sheng Pan Feb 2008

Corrosion Electrochemical Behavior Of Az31 And Az61 Magnesium Alloys In Simulated Sea Water, Ling-Jie Li, Sheng-Hai Yu, Jing-Lei Lei, Chuan-Pu Liu, Sheng-Tao Zhang, Fu-Sheng Pan

Journal of Electrochemistry

Tafel polarization curves and electrochemical impedance spectroscopy(EIS) techniques were employed to investigate the corrosion electrochemical behavior of AZ31 and AZ61 magnesium alloys.Scanning electron microscopy(SEM) was used to observe the alloy microstructure and corrosion morphology.The variation of the bulk corrosive medium pH with immersion time was recorded during the exposure of the alloys to simulated sea water.Results show that AZ61 magnesium alloy exhibits much better anti-corrosion ability than AZ31 magnesium alloy.The different corrosion behavior between the two magnesium alloys is correlated with their different content of Al alloying element.The higher content of Al in AZ61 alloy leads to the homogenerous microstructure …

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The Determination Of Vitamin C By Bromophenol Blue Modified Glassy Carbon Electrode, Shu-Lin Zhang, Min-Jiao Li, Yi Luo, Xiao-Bo Wang Feb 2008

The Determination Of Vitamin C By Bromophenol Blue Modified Glassy Carbon Electrode, Shu-Lin Zhang, Min-Jiao Li, Yi Luo, Xiao-Bo Wang

Journal of Electrochemistry

The content of ascorbic acid of(vitamin C) was analyzed by using fast cyclic voltamment with bromophenol blue(BPB) modififed GC-electrode,and which experimental conditions were optimiged.The results showed that the BPB modified GC-electrode had the good stability and anti-jamming faculty for analysing the content of ascorbic acid.A linear relationship between the peak current and concentration of vitamin C in the range of 0.0050~0.1500 g·L-1 was obtained,which related coefficient and the detection limit are-0.9991 and 0.0010 g·L-1,respeclively.The method has satisfactory results.

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Effects Of Oxidation Methods On The Stability Of Coooh Conductive Network In Foam Nickel Electrodes, Xiao-Feng Li, Yan-Wei Wei, Hui-Chao Dong Feb 2008

Effects Of Oxidation Methods On The Stability Of Coooh Conductive Network In Foam Nickel Electrodes, Xiao-Feng Li, Yan-Wei Wei, Hui-Chao Dong

Journal of Electrochemistry

Two kinds of the cobalt oxyhydroxide conductive networks in foam nickel electrodes were prepared by different methods i.e.the electrochemical-oxidation(EO) and chemical-oxidation(CO) and which redox behaviors were studied by using cyclic voltammetry and X-ray diffraction measurements.The results show that the CoOOH(CO) has better redox reversibility than CoOOH(EO) and the structure of the former can be kept when nickel electrodes are subjected to a negative potential.Thus,98.7% capacity retention is demonstrated on nickel/metal-hydride batteries with CoOOH(CO) conductive network after being imposed over-discharge state storage;on the contrary,only 83.3% capacity retention is found on the batteries with CoOOH(EO) conductive network.

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Effect Of Au At Different States On Electrocatalytic Performance Of Pd Catalyst For Oxidation Of Formic Acid, Xin Wang, Ya-Wen Tang, Tian-Hong Lu Feb 2008

Effect Of Au At Different States On Electrocatalytic Performance Of Pd Catalyst For Oxidation Of Formic Acid, Xin Wang, Ya-Wen Tang, Tian-Hong Lu

Journal of Electrochemistry

Using liquid-reduction or complex-redution method,four catalysts,i.e,the Au/C,Pd/C,Pd-Au/C-T and Pd-Au/C-H were preparated and which electroanalytic activities and stabilities for the oxidation of formic acid were compares.It was found that the Au/C catalyst has no electrocatalytic activity,and the Pd/C catalyst possesses the good electrocatalytic performance for the oxidation of formic acid.The addition of Au into the Pd/C catalyst can increase the electrocatalytic activity and stability.Especially,the electrocatalytic activity and stability of the Pd-Au/C-T catalyst with the alloy of Pd and Au are better than that of the of the Pd-Au/C-H catalyst,in which,Pd and Au do not form the alloy.The investigation of its reason …

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In Situ Measurement Of Chloride Concentration And Ph Distribution In The Crevice During The Crevice Corrosion Of Copper Electronic Board, Min Zhang, Xiang-Dong Zhuo, Chang-Jian Lin Feb 2008

In Situ Measurement Of Chloride Concentration And Ph Distribution In The Crevice During The Crevice Corrosion Of Copper Electronic Board, Min Zhang, Xiang-Dong Zhuo, Chang-Jian Lin

Journal of Electrochemistry

Although the crevice corrosion of metals had been extensively studied in the past years,it remained lack of direct experimental information of the micro chemical environments and electrochemical conditions inside the corroding crevice.The distribution of chloride concentration and local pH in the occluded area are the most crucial factors in development of crevice corrosion.The array probes in one dimension of Ag/AgCl and IrO2 array were developed in this work to in situ follow the distribution of chloride concentration and local pH in the occluded area during the crevice corrosion propagation.Based on a designed simulated crevice corrosion system in 0.5mol/L NaCl …

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Synthesis Of 2,2′-Dichlorohydrazobenzene Using An Ion Exchange Membrane, Chao Zhang, Pei-Jin Li Feb 2008

Synthesis Of 2,2′-Dichlorohydrazobenzene Using An Ion Exchange Membrane, Chao Zhang, Pei-Jin Li

Journal of Electrochemistry

Using an ion exchange membrane as a separator,the 2,2′-Dichlorohydrazobenzene is synthesized by the electrolytic reduction of o-chloronetrobenzene.The effects of electrode activation condition,current density,electrolyte temperature on electrolytic reduction are discussed.It was found that the optimum reaction temperature is 80 ℃.When the electrolyte concentration was 30% NaOH at the anode and 10% NaOH at the cathode,current density is 4.2A/dm2,the current efficiency reached 73% and yield is 83%.

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The Influence Of The Sputtering Power On The Structural And Electrochemical Properties Of Tin Oxide Films, Min-Zhen Cai, Jie Song, Ming-Sen Zheng, Qi-Hui Wu, Sun-Tao Wu, Quan-Feng Dong Feb 2008

The Influence Of The Sputtering Power On The Structural And Electrochemical Properties Of Tin Oxide Films, Min-Zhen Cai, Jie Song, Ming-Sen Zheng, Qi-Hui Wu, Sun-Tao Wu, Quan-Feng Dong

Journal of Electrochemistry

Tin oxide films were deposited on silicon substrates at room temperature using the radio frequency(RF) magnetron sputtering with different sputtering power.The influence of sputtering power upon the crystal structure,surface morphology and electrochemical properties of tin oxide films were then investigated.The XRD and SEM results illustrate that the phase of tin oxide thin films changed from amorphous to crystalline and the grain size augments with the increase of the sputtering power.The constant current charge and discharge cycle tests imply that the initial irreversible capacity loss of Li/tin oxide batteries increase and which capacity decrease as the sputtering power increases.The sputtering power …

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Computer Modeling And Analysis Of Thermal Link Performance For An Optical Refrigerator, Kevin Byram, David Mar, John Parker, Steven Von Der Porten, John Hankinson, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein Feb 2008

Computer Modeling And Analysis Of Thermal Link Performance For An Optical Refrigerator, Kevin Byram, David Mar, John Parker, Steven Von Der Porten, John Hankinson, Chris Lee, Kai Mayeda, Richard C. Haskell, Qimin Yang, Scott R. Greenfield, Richard I. Epstein

All HMC Faculty Publications and Research

We have used the thermal modeling tool in COMSOL Multiphysics to investigate factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a non-absorptive dielectric trapping mirror, the three dominant heating factors are blackbody radiation from the surrounding environment, conductive heat transfer through mechanical supports, and the absorption of fluorescent photons transmitted through the thermal link. Laboratory experimentation coupled with computer modeling using Code V optical software have resulted in link designs capable of reducing the transmission to 0.04% of the fluoresced photons emitted toward the thermal link. The ideal thermal link will have …

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The State Of The Art In Flow Visualization: Partition-Based Techniques, Tobias Salzbrunn, Heike Janicke, Thomas Wischgoll, Gerik Scheuermann Feb 2008

The State Of The Art In Flow Visualization: Partition-Based Techniques, Tobias Salzbrunn, Heike Janicke, Thomas Wischgoll, Gerik Scheuermann

Computer Science and Engineering Faculty Publications

Flow visualization has been a very active subfield of scientific visualization in recent years. From the resulting large variety of methods this paper discusses partition-based techniques. The aim of these approaches is to partition the flow in areas of common structure. Based on this partitioning, subsequent visualization techniques can be applied. A classification is suggested and advantages/disadvantages of the different techniques are discussed as well.

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Botsniffer: Detecting Botnet Command And Control Channels In Network Traffic, Guofei Gu, Junjie Zhang, Wenke Lee Feb 2008

Botsniffer: Detecting Botnet Command And Control Channels In Network Traffic, Guofei Gu, Junjie Zhang, Wenke Lee

Computer Science and Engineering Faculty Publications

Botnets are now recognized as one of the most serious security threats. In contrast to previous malware, botnets have the characteristic of a command and control (C&C) channel. Botnets also often use existing common protocols, e.g., IRC, HTTP, and in protocol-conforming manners. This makes the detection of botnet C&C a challenging problem. In this paper, we propose an approach that uses network-based anomaly detection to identify botnet C&C channels in a local area network without any prior knowledge of signatures or C&C server addresses. This detection approach can identify both the C&C servers and infected hosts in the network. Our …

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Multimodal News Story Clustering With Pairwise Visual Near-Duplicate Constraint, Xiao Wu, Chong-Wah Ngo, Alexander G. Hauptmann Feb 2008

Multimodal News Story Clustering With Pairwise Visual Near-Duplicate Constraint, Xiao Wu, Chong-Wah Ngo, Alexander G. Hauptmann

Research Collection School Of Computing and Information Systems

Story clustering is a critical step for news retrieval, topic mining, and summarization. Nonetheless, the task remains highly challenging owing to the fact that news topics exhibit clusters of varying densities, shapes, and sizes. Traditional algorithms are found to be ineffective in mining these types of clusters. This paper offers a new perspective by exploring the pairwise visual cues deriving from near-duplicate keyframes (NDK) for constraint-based clustering. We propose a constraint-driven co-clustering algorithm (CCC), which utilizes the near-duplicate constraints built on top of text, to mine topic-related stories and the outliers. With CCC, the duality between stories and their underlying …

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