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1998

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Full-Text Articles in Engineering

Bs News Mar 1998

Bs News

Building Services Engineering

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Studies Of Metallic Multilayer Structures, Optical Properties, And Oxidation Using In Situ Spectroscopic Ellipsometry, Xiang Gao, Jeff Hale, Scott Heckens, John A. Woollam Mar 1998

Studies Of Metallic Multilayer Structures, Optical Properties, And Oxidation Using In Situ Spectroscopic Ellipsometry, Xiang Gao, Jeff Hale, Scott Heckens, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

In situ spectroscopic ellipsometry (SE) has been successfully used to accurately measure sputter deposition rates and optical constants of un-oxidized metal layers and to control the growth of magnetic multilayers. The structures include [Co/Cu] n , [Co/Au] n , [Co/Ni] n , [Co/Pd] n and [Co/Pd/ Au] n . Layer thickness precision is better than ±0.05 nm for layer thicknesses in the range of 0.2 nm to 10 nm. Closed-loop feedback control of layer thickness is also demonstrated. Good consistency was obtained by comparing the in situ SE results to x-ray diffraction measurements. Dynamic oxidation studies of [Co/Au] n and …


Cryptococcus Neoformans Chemotyping By Quantitative Analysis Of H-1 Nuclear Magnetic Resonance Spectra Of Glucuronoxylomannans With A Computer-Simulated Artificial Neural Network, Robert Cherniak, Homayoun Valafar, Laura C. Morris, Faramarz Valafar Mar 1998

Cryptococcus Neoformans Chemotyping By Quantitative Analysis Of H-1 Nuclear Magnetic Resonance Spectra Of Glucuronoxylomannans With A Computer-Simulated Artificial Neural Network, Robert Cherniak, Homayoun Valafar, Laura C. Morris, Faramarz Valafar

Faculty Publications

The complete assignment of the proton chemical shifts obtained by nuclear magnetic resonance (NMR) spectroscopy of de-O-acetylated glucuronoxylomannans (GXMs) from Cryptococcus neoformanspermitted the high-resolution determination of the total structure of any GXM. Six structural motifs based on an α-(1→3)-mannotriose substituted with variable quantities of 2-O-β- and 4-O-β-xylopyranosyl and 2-O-β-glucopyranosyluronic acid were identified. The chemical shifts of only the anomeric protons of the mannosyl residues served as structure reporter groups (SRG) for the identification and quantitation of the six triads present in any GXM. The assigned protons for the mannosyl residues resonated at clearly …


Forecasting Market Index Performance Using Population Demographics, Bradley J. Alden Mar 1998

Forecasting Market Index Performance Using Population Demographics, Bradley J. Alden

Theses and Dissertations

This study attempted to verify claims made by forecaster Harry S. Dent, Jr. It utilized regression analysis in order to determine the correlation between the number of births and the closings on a market index with a specified lag between the input and output variables. While the research was able to develop a model with the factor Dent considers the most important, the predictions based on this model did not completely coincide with the forecasts Dent makes. Furthermore, the research could not confirm the accentuation Dent places on a 46-year lag between predictor and response variables. As an extension, scenarios …


Application Of Decision Analysis To Evaluate Alternative Research And Development Investments, Michael J. Artelli Mar 1998

Application Of Decision Analysis To Evaluate Alternative Research And Development Investments, Michael J. Artelli

Theses and Dissertations

This thesis is an application of decision analysis techniques to the problem of evaluating competing research and development investments and selecting the best portfolio from among the alternatives. In contrast to the current ad hoc approach, decision analysis provides an explicit and easily explained rationale for investment choices, complete and consistent incorporation of multiple objectives, and direct insight into the effects of uncertain investment returns. A hierarchical objective decomposition was used to capture the user's preference structure. The hierarchy was then used to develop a computer-based decision aid to allow the users to quickly and consistently evaluate technology investment options. …


Parameter Estimation Of The Mixed Generalized Gamma Distribution Using Maximum Likelihood Estimation And Minimum Distance Estimation, Dean G. Boerrigter Mar 1998

Parameter Estimation Of The Mixed Generalized Gamma Distribution Using Maximum Likelihood Estimation And Minimum Distance Estimation, Dean G. Boerrigter

Theses and Dissertations

The Generalized Gamma is an extremely flexible distribution that is useful for reliability modeling. Among its many special cases are the Weibull and Exponential distributions. A mixture of Generalized Gamma Distributions is even more useful because multiple causes of failure can he simultaneously modeled. This research studied parameter estimation of the special cases of the Mixed Generalized Gamma Distribution and built upon them until the full nine-parameter distribution was being estimated. First, special cases of a single Generalized Gamma Distribution were estimated. Next, mixtures of Exponential distributions with both known and unknown location parameters were estimated. Next, mixtures of Weibull …


Performance Of Imaging Laser Radar In Rain And Fog, Kathleen M. Campbell Mar 1998

Performance Of Imaging Laser Radar In Rain And Fog, Kathleen M. Campbell

Theses and Dissertations

The Air Force is currently developing imaging laser radar systems (ladar) for use on precision guided munitions and other imaging systems. Scientists at Eglin Air Force Base, in conjunction with Wright Laboratories, are testing a 1.06-um wavelength ladar system and need to understand the weather effects on the ladar images. As the laser beam propagates through the atmosphere, fog droplets and raindrops can cause image degradation, and these image degradations are manifested as either dropouts or false returns. An analysis of the dropouts and false returns helped to quantify the performance of the system in adverse weather conditions. Statistical analysis …


Channel-Mismatch Compensation In Speaker Identification Feature Selection And Adaptation With Artificial Neural Networks, Edmund A. Fitzgerald Mar 1998

Channel-Mismatch Compensation In Speaker Identification Feature Selection And Adaptation With Artificial Neural Networks, Edmund A. Fitzgerald

Theses and Dissertations

We develop and present results of an artificial neural network (ANN) based compensation technique for mismatched classifier training and testing conditions in speaker identification (SID). One ANN per feature per speaker is trained to perform a mapping of that feature from a corrupted condition to an undistorted condition. Therefore, a classifier trained under one condition may be used to classify data collected under a different condition. Speech utterances from 168 speakers, collected in a studio, and also re-recorded after transmission over telephone networks, are used for developing and testing the method. Peak formant resonant frequencies, their bandwidths, and pitch are …


Embedding A Reactive Tabu Search Heuristic In Unmanned Aerial Vehicle Simulations, Joel L. Ryan Mar 1998

Embedding A Reactive Tabu Search Heuristic In Unmanned Aerial Vehicle Simulations, Joel L. Ryan

Theses and Dissertations

We apply a Reactive Tabu Search (RTS) heuristic within a discrete event simulation to solve routing problems for Unmanned Aerial Vehicles (UAVs). Our formulation represents this problem as a multiple Traveling Salesman Problem with time windows (mTSPTW), with the objective of attaining a specified level of target coverage using a minimum number of vehicles. Incorporating weather and probability of UAV survival at each target as random inputs, the RTS heuristic in the simulation searches for the best solution in each realization of the problem scenario in order to identify those routes that are robust to variations in weather, threat, or …


The Measurement Of Human Intellectual Capital In The United States Air Force, Thomas J. Wagner Mar 1998

The Measurement Of Human Intellectual Capital In The United States Air Force, Thomas J. Wagner

Theses and Dissertations

For centuries, companies used basically the same accounting system developed in the fifteenth century to measure economic performance. Through much of this period the tangible value of a firm, its plants, property and equipment, was closely related to the market value of the firm. With the dawning of the information age, America has evolved from a manufacturing based economy to a service oriented economy. Closely related to this change from a blue collar to white collar workplace has been the widening gap between the market value of a company and its tangible assets. Roughly equal before, now the tangible assets …


Effect Of High Free Stream Turbulence On Film Cooling Using Double Row Of 30° Slant-Hole Injectors, Lilith I. Sorensen Mar 1998

Effect Of High Free Stream Turbulence On Film Cooling Using Double Row Of 30° Slant-Hole Injectors, Lilith I. Sorensen

Theses and Dissertations

In this study free stream turbulence levels from 7.3% to 17.8% are applied to film cooling over a flat plate with two rows of 30° slant holes using a wall jet as the main stream air supply and source of turbulence. Blowing ratios are varied from 0.25 to 2.0 and free stream velocities at injection range from 10 m/s to 85 m/s. A constant density ratio of 1.07 is kept throughout the experiment. Results show that for different magnitudes of blowing ratio free stream turbulence has a different influence on effectiveness. At the forward stations, where blow off was present …


Field Solutions For Bidirectional High-Gain Laser Amplifiers And Oscillators, Lee W. Casperson, Mohammad Azadeh Mar 1998

Field Solutions For Bidirectional High-Gain Laser Amplifiers And Oscillators, Lee W. Casperson, Mohammad Azadeh

Electrical and Computer Engineering Faculty Publications and Presentations

General analytical solutions are obtained for the amplitude, phase, and intensity of the electromagnetic waves in bidirectional homogeneously broadened high-gain laser amplifiers and oscillators. These solutions are important as increasingly high-gain lasers are being employed in practical systems. Expressions are derived relating the output power to the input, including the effects of arbitrary mirror reflectivities and frequency detunings from the line center. For negligible reflectivities, these regenerative amplifier results reduce to earlier expressions for single-pass high-gain amplifiers. Multivalued outputs also occur, and in the limit of low gain per pass the results are consistent with earlier studies of single-frequency laser …


Spatial Resolution Enhancement Of Ssm/I Data, David G. Long, Douglas L. Daum Mar 1998

Spatial Resolution Enhancement Of Ssm/I Data, David G. Long, Douglas L. Daum

Faculty Publications

One of the limitations in using Special Sensor Microwave/Imager (SSM/I) data for land and vegetation studies is the relatively low-spatial resolution. To ameliorate this limitation, resolution-enhancement algorithms can be applied to the data. In this paper, the Backus-Gilbert inversion (BGI) technique and the scatterometer image-reconstruction (SIR) algorithm are investigated as possible methods for creating enhanced resolution images from SSM/I data. The two algorithms are compared via both the simulation and the actual SSM/I data. The algorithms offer similar resolution enhancement, though SIR requires significantly less computation. Sample results over two land regions of South America are presented.


Determination Of The Asymmetry Parameter And Scattering Coefficient Of Turbid Media From Spatially Resolved Reflectance Measurments, Matthew R. Jones, Yukio Yamada Mar 1998

Determination Of The Asymmetry Parameter And Scattering Coefficient Of Turbid Media From Spatially Resolved Reflectance Measurments, Matthew R. Jones, Yukio Yamada

Faculty Publications

We present a technique for determining the asymmetry parameter and scattering coefficient of turbid media from spatially resolved reflectance measurements. This technique will contribute to the development of medical applications in which it is necessary to predict the distribution and propagation of light in tissue. Based on Monte Carlo simulations, we derived correlations which relate the reduced scattering coefficient and the asymmetry parameter to the relative reflectance curve. Initial estimates of the optical properties are obtained from these correlations. Final values are obtained by adjusting the optical parameters and repeating the Monte Carlo simulations until the simulated reflectance pattern matches …


Understanding Comics: The Invisible Art, Alan D. Manning Mar 1998

Understanding Comics: The Invisible Art, Alan D. Manning

Faculty Publications

INSIGHTS about professional communication may come from odd and unexpected places. McCloud's Understanding Comics (hereafter UC) is a case in point. Despite the juvenile connotations evoked by any discussion of comic books, the theory of visual communication presented in UC arguably rivals the best of contemporary semiotics (that is, the study of how we make meaning out of gestures, words, paragraphs, pictures, and so on).


Studies Of Surface Electrochemistry And Electrocatalysis At Atomic And Molecule Level, Shigang Sun Feb 1998

Studies Of Surface Electrochemistry And Electrocatalysis At Atomic And Molecule Level, Shigang Sun

Journal of Electrochemistry

The main progresses achieved during last few years in our research group concerning studies of surface electrochemistry and electrocatalysis were reviewed in this present paper. Four topics were described: 1) the surface electrochemistry and model electrocatalysis of metal single crystal planes, 2) the electrocatalytic reaction mechanism and the control of reaction pathways at molecule level, 3) the reaction kinetics of electrooxidation of small organic molecules, and 4) the relationship between the properties and the surface chemical states of electrocatalyst. This review lays in emphasis on the demonstration of the results as well as the research direction of surface electrochemistry and …


A Preliminary Study On Thin Film Plasticizing Lithium Ion Battery, Quanfeng Dong, Hanxi Yang, Xinping Ai, Xiaohong Hu, Shengxian Li Feb 1998

A Preliminary Study On Thin Film Plasticizing Lithium Ion Battery, Quanfeng Dong, Hanxi Yang, Xinping Ai, Xiaohong Hu, Shengxian Li

Journal of Electrochemistry

A dry polymer electrolyte was made by plasticizing a copolymer matrix and further filling with liquid electrolyte. A thin-film lithium ion battery based on the dry polymer electrolyte was manufactured and its electrochemical properties were measured. It is found that the thin film lithium ion battery exhibits similar discharge properties to liquid electrolyte battery, and shows strong high rate capability.


Microelectrode Studies On The Pitting Corrosion Process Of Stainless Steel, Changjian Lin, Lijian Chen, Ronggui Du, Zude Feng, Jianguang Tang, Hongping Dai Feb 1998

Microelectrode Studies On The Pitting Corrosion Process Of Stainless Steel, Changjian Lin, Lijian Chen, Ronggui Du, Zude Feng, Jianguang Tang, Hongping Dai

Journal of Electrochemistry

Differing with the scanning microelectrode techniques, which scan microelctrode closely to the interface of electrode/electrolyte and make electrochemical imaging in a lateral spatial resolution, the technique of microelectrode with a micron diameter is of very high time-resolution and ratio of signal/noise in electrochemical measurements. The microelectrode technique allows double-layer capacitance and background current for a microelectrode to be drastically reduced due to the exposed area of a microelectrode is usually 6~8 orders of magnetite lower than that of a conventional electrode with large-scale exposed area. Microelectrode was recently developed as a new powerful electrochemical technique and widely used in the …


Gold Electrodeposition On Microelectrodes, Lihua Xiong, Caihui Shi, Xiaoqin Li, Bingwei Mao Feb 1998

Gold Electrodeposition On Microelectrodes, Lihua Xiong, Caihui Shi, Xiaoqin Li, Bingwei Mao

Journal of Electrochemistry

The initial stage electrodeposition behaviors of gold onto glassy carbon and platinum microelectrodes are studied in an acid solution containing AuCl3 using cyclic voltammetry and potential step techniques. The results suggest that gold nucleation on microelectrodes requires a higher driving force with high probability. Within the range of the microelectrode dimension that have been used in the present work, large amount of gold nucleus could be formed at short time scale at overpotentials higher than a threshole value. The It curves from the platinum microelectrode are in consistence with the continuous nucleation model. It has been found that …


Study On The Synthesis And Electrochemical Behavior Of Poly (Quinonoid-Disulfide), Xiaohui Tang, Xiuwu Sun, Yongfang Li, Shibi Fang Feb 1998

Study On The Synthesis And Electrochemical Behavior Of Poly (Quinonoid-Disulfide), Xiaohui Tang, Xiuwu Sun, Yongfang Li, Shibi Fang

Journal of Electrochemistry

Organic polydisulfide containing quinonoid structure was synthesized by chloromethylation, oxidation by nitric acid, and condensation polymerization with sodium disulfide. The effect of quinonoid structure on the electrochemical behavior of organic polydisulfide was investigated with cyclic voltammetry and chargedischarge measurement. The result shows that quinonoid struture mainly affects the positions of redox peaks of organic polydisulfide, open circuit voltage and discharge platform voltage of cell with the organic polydisulfide as cathode.


The Investigations Of Surface Treatment Methods And Characterization Of Oxide Films On Ab5 Based Metal Hydride Electrodes Ⅰ. New NiRich Treatment Methods And Photoelectrochemical Characterization Of Oxide Films, Junmin Nan, Yong Yang, Jun Li, Zugeng Lin Feb 1998

The Investigations Of Surface Treatment Methods And Characterization Of Oxide Films On Ab5 Based Metal Hydride Electrodes Ⅰ. New NiRich Treatment Methods And Photoelectrochemical Characterization Of Oxide Films, Junmin Nan, Yong Yang, Jun Li, Zugeng Lin

Journal of Electrochemistry

Two simple and efficient surface treatment methods for AB5 type hydrogen storage alloys were developed. The results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammetric (CV) experiments showed that the hydrogen storage alloys treated by two different methods had Ni rich surface layer so that the performances of the electrodes were improved after treatment. The characterization of the oxide films which formed on the surface of electrodes through potentiodynamic oxidation with the help of photoelectrochemical microscopy (PEM) were done. The anodic photocurrent and the cathodic photocurrent related to the oxidation of hydrogen and the reduction of oxygen on the …


Spectroscopic Investigation Of Ion Transport Mechanisms In Polyacrylonitrile Based Electrolytes, Zhaoxiang Wang, Biying Huang, Rongjian Xue, Xuejie Huang, Liquan Chen Feb 1998

Spectroscopic Investigation Of Ion Transport Mechanisms In Polyacrylonitrile Based Electrolytes, Zhaoxiang Wang, Biying Huang, Rongjian Xue, Xuejie Huang, Liquan Chen

Journal of Electrochemistry

Raman, IR, X-ray photoelectron (XPS), and NMR spectra of components in polyacrylonitrile based electrolytes have been studied. It is found that there are strong interactions among the components though different systems show different interaction characteristics. A concept of competition is proposed between the polymer matrix and the plasticizer on associating with the Li+ ions. By analyzing the important functions of the plasticizer, a possible mechanism of the ions transport in the polymer electrolyte is suggested.


Electrochemical Impedance Of Molten Salts Induced Hot Corrosion, Chaoliu Zeng, Weitao Wu, Jianqing Zhang Feb 1998

Electrochemical Impedance Of Molten Salts Induced Hot Corrosion, Chaoliu Zeng, Weitao Wu, Jianqing Zhang

Journal of Electrochemistry

Electrochemical impedance technique was employed to study corrosion behaviors of Ni-3Al, IN100 and IN738 alloys in molten (Na, K, Li)2SO4 at 700 ℃. The Nyquist plots for Ni-3Al and IN100 alloys have the characteristics of diffusion controlled reaction. But, the corrosion reaction for IN738 alloy is not controlled by the diffusion of oxidants. The equivalent circuits were proposed, and the parameters in circuits were also calculated. Ni-3Al and IN100 alloys suffer from catastrophic corrosion due to the formation of a porous corrosion layer. IN738 alloy has excellent corrosion resistance because of the formation of a protective oxide …


A Study Of Adsorption Kinetics Of Β-Phenylaminopropiophenone On Iron In Acid Solution, Dihua Wang, Xianzhang Bu, Jinyun Zou, Fuxing Gan Feb 1998

A Study Of Adsorption Kinetics Of Β-Phenylaminopropiophenone On Iron In Acid Solution, Dihua Wang, Xianzhang Bu, Jinyun Zou, Fuxing Gan

Journal of Electrochemistry

The adsorption kinetics of β-phenylaminopropiophenone (PAP) on iron electrode in 0.5 mol/L H2SO4 solution with or without Cl- were investigated by chronoamperometry.


A Study On Heterogeneous Indirect Electrosynthesis Of Benzaldehyde, Daobao Chu, Changjian Lin, Huashui Lin, Jianguang Tan Feb 1998

A Study On Heterogeneous Indirect Electrosynthesis Of Benzaldehyde, Daobao Chu, Changjian Lin, Huashui Lin, Jianguang Tan

Journal of Electrochemistry

Heterogeneous indirect electrosynthesis process of benzaldehyde has been investigated using cyclic voltammetry and polarization curves. An optimum condition for preparation of benzaldehyde by indirect electrooxidation of toluenc with redox Mn3+/Mn2+ is given in this paper. Electrolytic regeneration Mn3+ are made at Pt/Ti anode in “slurry” MnSO4/H2SO4 medium. Current efficiency for electrolytic regeneration Mn3+  was maintained over 88% by “double cyclic way”.


Investigation Of Methanol Anode Electrooxidation Catalysts, Gangyao Wen, Ying Zhang, Zhenglong Yang, Changzhi Li Feb 1998

Investigation Of Methanol Anode Electrooxidation Catalysts, Gangyao Wen, Ying Zhang, Zhenglong Yang, Changzhi Li

Journal of Electrochemistry

A series of catalysts, Pt-WO3/C, Pt/Ru/C and Pt-Ru-WO3/C were prepared by chemical reduction deposition. Electrocatalytic oxidation of methanolon different catalyst/Nafion membrane electrodes was studies by voltammetry and current-potential polarization. The results indicated that the catalytic activity order of different catalysts is as follows: Pt-Ru-WO3/C > Pt-Ru/C > Pt-WO3/C. At the same time, influences of methanol concentrations and catalyst proportion on performances of anodes were also studies.


Progresses In Surface Electrochemistry And Electrocatalysis ——A Review On The 1997 Joint International Meeting Of Electrochemistry And 97' International Meeting Of Surface Electrochemistry, Shigang Sun Feb 1998

Progresses In Surface Electrochemistry And Electrocatalysis ——A Review On The 1997 Joint International Meeting Of Electrochemistry And 97' International Meeting Of Surface Electrochemistry, Shigang Sun

Journal of Electrochemistry

The progresses in surface electrochemistry and electrocatalsis reported in the 1997 joint international meeting of electrochemistry and in the 97′ international meeting of surface electrochemistry were reviewed. The main trends described in this paper consisted of 7 aspects: 1) the studies employing single crystal electrodes, 2) the development of in situ methods of diverse spectroscpoy, 3) the innovation of new research techniques, 4) the preparaton of electrocatalyst of high performances, 5) the quantitative studies on kinetics of electrocatalytic reactions, 6) the investigation on the dynamic processes of surface by timeresolved methods, and 7) the theoretical modeling and simulation of surface …


Anchor Effect Of Iron And Cobalt To Platinum On Carbon Substrates, Zidong Wei, Hetong Guo, Zhiyuan Tan Feb 1998

Anchor Effect Of Iron And Cobalt To Platinum On Carbon Substrates, Zidong Wei, Hetong Guo, Zhiyuan Tan

Journal of Electrochemistry

The cathodic reduction of oxygen is studied on porous carbonbased electrodes carrying platinumiron and/or cobalt alloy catalysts. Electrodes using such electrocatalysts, particularly when used as cathodes in acidic electrolytes, remain stable for longer periods. The cathodic polarization of oxygen reduction on such electrodes is 20 mV to 40 mV lower than that on the conventional electrode on which only platinum alone is used as an electrocatalysts. An accelerated aging test (AAT) is used to evaluate the corrosion resistance and sintering resistance of each catalyst. The dissolution of the catalyst in the AAT filtrate is analysed and provides a measure of …


Study On Nano Electrode Material Of Lithium Ion Batteries, Jinkua You, Yong Yang, Dong Shu, Shenghui Wu, Yingchun Zhang, Zugeng Lin Feb 1998

Study On Nano Electrode Material Of Lithium Ion Batteries, Jinkua You, Yong Yang, Dong Shu, Shenghui Wu, Yingchun Zhang, Zugeng Lin

Journal of Electrochemistry

In this paper, the structure and morphology of the nano phase electrode materials have been characterized with XRD and TEM. The performances of electrochemical intercalation and deintercalation of lithium ions have been studied by using cyclic voltammograms and galvanostatic charge discharge techniques. The results show that the nano materials posses advantage of micro structure and Li+ ions intercalation performances. The observed high capacity and large charge discharge current density of the nano phase materials seem to have resulted from three kinds of effects: 1) an increase in the space for Li+ ions intercalation; 2) a decrease in the …


The Migration Of Samarium(Ⅲ) Across Oil/Water Interface, Jun-Wei Di, Xiao-Xing Xu, Ying Wu, Rui-Xi Fan Feb 1998

The Migration Of Samarium(Ⅲ) Across Oil/Water Interface, Jun-Wei Di, Xiao-Xing Xu, Ying Wu, Rui-Xi Fan

Journal of Electrochemistry

The migration of Samarium(Ⅲ) across water/nitrobenzene (w/nb) interface facilitated by diantipyrylmethane (DAM) and the electrochemical behaviour affected by emulsifier OP in the nb phase have been studied by normal and convolute cyclic voltammetry. It is concluded that the formation of the complex occurs at w/nb interface and the mechanism of the samarium(Ⅲ)transfer across w/nb interface facilitated by DAM is E mechanism.