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1999

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Articles 151 - 180 of 2348

Full-Text Articles in Physical Sciences and Mathematics

Study On Electrochemical Reduction Properties Of Nitrobenzene, Chu-Na Ma, Wen-Kui Zhang, Hui Huang, Yong-Ping Gan Nov 1999

Study On Electrochemical Reduction Properties Of Nitrobenzene, Chu-Na Ma, Wen-Kui Zhang, Hui Huang, Yong-Ping Gan

Journal of Electrochemistry

The electrochemical reduction characteristics of nitrobenzene was extensively investigated by using the techniques such as quasi-steady-state polarization, cyclic voltammetry, fast linear potential sweep method and chronoamperometry in this paper. The electroanalytic properties of Cu, Cu-Hg and Cu-Ni electrodes were evaluated. Based on the study of the transient steping behaviour of nitrobenzene to PAP, the reduction mechanism was discussed. The results showed that the transition steps existed on the electrochemical reduction of nitrobenzene in acidic solution, the reactant is also absorbed on electrodes surface. The control step in the reduction of nitrobenzene was ascribed to the diffusion of nitrobenzene and its …

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A Gas Analysis Method For Determining The Perchlorate Current Efficiency And Other Applications, Zhi-Gang Shao, Bao-Lian Yi Nov 1999

A Gas Analysis Method For Determining The Perchlorate Current Efficiency And Other Applications, Zhi-Gang Shao, Bao-Lian Yi

Journal of Electrochemistry

A method for determining the current efficiency by means of measuring the flow capacity of the cell gas in a perchlorate cell has been proposed. The perchlorate cell system was equipped with an oxygen cathode or a Na+ ion exchange membrane. This method is simple and convenient as well as accurate in the evaluation of the perchlorate current efficiency in the perchlorate cell as compared with the traditional methods of analysis. It is useful in the investigation of electrochemical problems with high perchlorate concentration, as well as for the assessment of electrocatalytic performance of anode materials.With an oxygen cathode …

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High Performance Proton Exchange Membrane Fuel Cells, Jing-Rong Yu, Bao-Lian Yi, Ming Han, Xiao-Liang Cheng, Zhi-Gang Shao, Jing-Xin Zhang Nov 1999

High Performance Proton Exchange Membrane Fuel Cells, Jing-Rong Yu, Bao-Lian Yi, Ming Han, Xiao-Liang Cheng, Zhi-Gang Shao, Jing-Xin Zhang

Journal of Electrochemistry

Proton-exchange membrane fuel cells(PEMFC) using a perfluorosulfonic acid proton exchange membrane as an electrolyte can simplify water and electrolyte management. In this paper, the effects of thickness of PEM on the performance of PEMFC were studied. The Nafion-112 PEM and low platinum loading E-TEK electrode yielded very high power density, of the order of 0.95 W/cm2. The energy-conversion efficiency, the degree of platinum utilization and stability for PEMFC using Nafion 112 and E-TEK electrode were also investigated.

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Electrochemical Studies Of Metal Complexes In Solution, Ye-Xiang Tong, Bei-Sheng Kang, Qi-Qin Yang Nov 1999

Electrochemical Studies Of Metal Complexes In Solution, Ye-Xiang Tong, Bei-Sheng Kang, Qi-Qin Yang

Journal of Electrochemistry

The prospectus of electrochemical studies of metal complexes in solution have been introduced as a background of our research work. The electrochemical behaviors of the metal complexes and clusters have been investigated by many kinds of electrochemical methods. The content includes the standard electrode potential and the related equilibrium constant, electrochemical kinetics and the related behavior of structure, electrocatalysis and electrosynthesis of metal complexes. The electrode reaction mechanisms of the complexes have been approached. The methods for measuring some thermodynamic and kinetic parameters of the complexes are also given. Electrochemical studies would provid many kinds of important information for studying …

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Photoelectrochemical Studies On The Tio2 Nanostructured Porous Film Sensitized By Cyanine Dye, Li Zhang, Mai-Zhi Yang, Xue-Bin Qiao, Yan-Zhong Hao, En-Qing Gao, Sheng-Min Cai Nov 1999

Photoelectrochemical Studies On The Tio2 Nanostructured Porous Film Sensitized By Cyanine Dye, Li Zhang, Mai-Zhi Yang, Xue-Bin Qiao, Yan-Zhong Hao, En-Qing Gao, Sheng-Min Cai

Journal of Electrochemistry

The photoelectrochemical behaviors of the TiO2 nanostructured porous film sensitized by cyanine dye were investigated in this paper. The results showed that the excitaed state level matched the conduction band edge of TiO2 nanoparticle. Therefore the sensitization of the dye can increase the photocurrent intensity of the TiO2 nanostructured electrode obviously and results in a red-shift of optical absorption from the ultra-violet region to the visible. As a result, the light-to-electricity conversion efficiency was improved evidently, the maximum value of IPCE has reached 12.1%.

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Electro-Oxidation Of Phenol On Sno2/Ti Electrodes Prepared By Thermal Oxidation, Qing-Song Zhang, Hui-Huang Wu Nov 1999

Electro-Oxidation Of Phenol On Sno2/Ti Electrodes Prepared By Thermal Oxidation, Qing-Song Zhang, Hui-Huang Wu

Journal of Electrochemistry

A SnO2/Ti electrode prepared by thermal oxidation was used as the anode for galvanostatic electrolysis in acidic solution containing phenol, the time-dependances of phenol concentration, chemical oxygen demand in solution(COD) and instantaneous current efficiency were determined during electrolysis. The results show that with the SnO2/Ti anode instead of Pt, the COD significantly decreases at the same charge passage, and average current efficiency of oxidation increases by three times. The mechanism for phenol oxidation at two electrodes was discussed.

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Investigation Of Sodium Hypophosphite Anodic Oxidizing Behavior In The Process Of Acid Electroless Nickel Deposition, Mei-Yuan Wang, Ya-Fei Kuang, Yan Xu Nov 1999

Investigation Of Sodium Hypophosphite Anodic Oxidizing Behavior In The Process Of Acid Electroless Nickel Deposition, Mei-Yuan Wang, Ya-Fei Kuang, Yan Xu

Journal of Electrochemistry

The anodic oxidizing behavior of sodium hypophosphite in the process of electroless nickle deposition (pH=5.5) was investigated with the linear potential sweep method and alternating current impedance. The results indicated that, the oxidation of NaH2PO2 was a complicated electrochemical process and affected by the concentration of NaH2PO2, the temperature of the bath, the sweep rate and the existence of nickel ion. The NaH2PO2 electrooxidation reaction was very likely preceded by heterogeneous interface transformation process, which might be the control step of the whole anodic process.

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The Preparation Of Flexible Polymeric Anode And The Measurement Of Its Protective Ability For Cathodic Protection, Ai-Ling Du, He-Ming Zhang, Ming-Zong Zhang, Shi-De Ma Nov 1999

The Preparation Of Flexible Polymeric Anode And The Measurement Of Its Protective Ability For Cathodic Protection, Ai-Ling Du, He-Ming Zhang, Ming-Zong Zhang, Shi-De Ma

Journal of Electrochemistry

The flexible electrode, whose shape can be changed freely, was made of ethenyl copolymer and conductive component and proper amount of additive for cathodic protection. The resistance of electrode was measured.In low concentration of H2SO4, the flexible electrode can be used as auxiliary anode to protect the carbon steel. The protection ability of the flexible auxiliary anode was measured too.

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Studies Of The Electrode Preparation Of Electrode From Lead Carbonate For Lead Acid Batteryⅰ. The Activation Of The Pme, Zhong-Xu Dai, Di-Hua Wang, Jun-Wei Jiang, Yun-Hong Zhou, Jin-Yun Zou Nov 1999

Studies Of The Electrode Preparation Of Electrode From Lead Carbonate For Lead Acid Batteryⅰ. The Activation Of The Pme, Zhong-Xu Dai, Di-Hua Wang, Jun-Wei Jiang, Yun-Hong Zhou, Jin-Yun Zou

Journal of Electrochemistry

Lead carbonate which was an intermediate product in lead hydrometallurgy without pollution of lead vapor and sulfur dioxide was selected as electrode material of lead-acid batteries. In the present work, the performances of PbO2/PbSO4 or PbSO4/Pb electrode transformed from PbCO3 have been investigated by powder microelectrode technique combined with cyclic voltammetry. The results show that the CV characteristics of either negative or positive electrode prepared from PbCO3 is as good as that of both electrodes made from lead oxide produced by mill machine,when a powder microelectrode with PbCO3 transformed into PbSO 4 …

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Prparation Of Nanocrystaline Tio2(Anatase) With High Thermal And Textural Sability By Electrochemical Method, Dao-Bao Chu, Xing-Fu Zhou, Chang-Jian Lin, Jian-Guang Tang Nov 1999

Prparation Of Nanocrystaline Tio2(Anatase) With High Thermal And Textural Sability By Electrochemical Method, Dao-Bao Chu, Xing-Fu Zhou, Chang-Jian Lin, Jian-Guang Tang

Journal of Electrochemistry

Titanium alkoxides were prepared by anodic dissolution of metallic titanium in absolute ethanol in the presence of HN(C2H5)2·HCl (electro-conductive additives). The solution was directly hydrolyzed to prepare nanocrystalline of TiO2 (about 10nm)by a sol-gel process. The precursor gels was calcined at T =450 ℃ and 720 ℃ for 30 min, and nanocrystalline of TiO2 (anatase) with high textural and thermal stability was obtained. FTIR, XRD, TEM were used to characterize the structure of titanium alkoxides and nanocrystalline of TiO2. The characteristics of nanocrystalline of TiO2 was depended on the …

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The Studies Of The (Photo) Electrochemical Character On The Electrodeposited Silver Indium Selenium Thin Films, Shao-Ai Xie, Xun-Nan Deng, You-Jin Kua Nov 1999

The Studies Of The (Photo) Electrochemical Character On The Electrodeposited Silver Indium Selenium Thin Films, Shao-Ai Xie, Xun-Nan Deng, You-Jin Kua

Journal of Electrochemistry

A photoelectrochemical cell (PEC) is constructed, using an AgInSe2 film photoanode made from electrodeposition and a platinium electrode in aqueous polyiodide or polysufide electrolyte. The Voc and Isc of PEC have been tested and measured, and the effect of chemical decoration on the photoanodes also studied.

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Studies On Methods Of Fuel Cells Electrodes Preparation, Jun Gu, Sheng Sui, Guang-Qiang Li, Zhitong Sui Nov 1999

Studies On Methods Of Fuel Cells Electrodes Preparation, Jun Gu, Sheng Sui, Guang-Qiang Li, Zhitong Sui

Journal of Electrochemistry

In fuel cells, the structure of electrodes is an important factor which effect the cell performance. To improve the structure and the performance of electrodes, a new method of providing fuel cell electrodes is proposed in this paper. PTFE (polytetrafluoroethylene) and ethyne black was ground for about half an hour in a high-speed grinder, then the catalyst was added into the grinder and milled for an hour. This milled catalyst was transferred into a mixer followed by the addition of surface-active agent. After a suspension was formed, it was filtered under vacuum condition.Then a thin uniform filter-cake of the catalyst …

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Pushpush Is Np-Hard In 3d, Joseph O'Rourke, The Smith Problem Solving Group Nov 1999

Pushpush Is Np-Hard In 3d, Joseph O'Rourke, The Smith Problem Solving Group

Computer Science: Faculty Publications

We prove that a particular pushing-blocks puzzle is intractable in 3D. The puzzle, inspired by the game PushPush, consists of unit square blocks on an integer lattice. An agent may push blocks (but never pull them) in attempting to move between given start and goal positions. In the PushPush version, the agent can only push one block at a time, and moreover, each block, when pushed, slides the maximal extent of its free range. We prove this version is NP-hard in 3D by reduction from SAT. The corresponding problem in 2D remains open.

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A Novel Reaction Region Moving Electrode System For Electrochemical Power Sources, Jin-Kua You, Que Tu, Zheng-Jian Wang, Jie Sun, Zu-Geng Lin Nov 1999

A Novel Reaction Region Moving Electrode System For Electrochemical Power Sources, Jin-Kua You, Que Tu, Zheng-Jian Wang, Jie Sun, Zu-Geng Lin

Journal of Electrochemistry

In most of practical rechargeable batteries, charging/discharging process is always concerned with phase-transformation in the solid state. Due to the irreversibility of the phase-transformation, the cyclic performance of the rechargeable batteries are limited. In this paper, a novel reaction-region moving counter electrode system is constructed in our laboratory. The electrode system is operated at room temperature and cycled in solid-liquid phase during charging/discharging processes. With this electrode, the metal-complexes are firstly deposited (i.e. charging process) on the nearest working electrode and gradually extended to those another working electrodes several centimeters away from the counter electrode. The deposite is dissolved again …

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Characterization And Electrochemical Behaviour Of Ce(Ⅲ) Amino Acid Imidazole Ternary Complexes, Hui-Xia Wu, Ze-Min Wang, Hai-Feng Yang, Zong-Rang Zhang Nov 1999

Characterization And Electrochemical Behaviour Of Ce(Ⅲ) Amino Acid Imidazole Ternary Complexes, Hui-Xia Wu, Ze-Min Wang, Hai-Feng Yang, Zong-Rang Zhang

Journal of Electrochemistry

Two Ce(Ⅲ)-amino acid-imidazole teranry complexe were synthesized,These complexes have the composition of Ce(Trp)3IM(NO3)3·3H2O and Ce(Phe)3IM(NO3)3 respectively. The IR spectra indicate that the carboxy group of amino-acid and the N atoms of imidazole are coordinated with Ce(Ⅲ) ion. Cyclic voltammetry was used to study the electrochemical behaviour of Ce(Ⅲ) ion, the mixture of Ce(Ⅲ) with ligands, and Ce(Ⅲ) binary or ternary complexes. Within the scan range of -0.1 to 1.10 V (vs.SCE), both of ternary complexes depicted completely irreversible electron transfer process.

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Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls Nov 1999

Recent Laboratory Tests Of A Hard X-Ray Solar Flare Polarimeter, Mark L. Mcconnell, John R. Macri, M Mcclish, Jack Ryalls

Space Science Center

We report on the development of a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (50 - 300 keV) from solar flares. Such measurements would be useful for studying the directivity (or beaming) of the electrons that are accelerated in solar flares. We initially used a simple prototype polarimeter to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. We have recently fabricated a science model based on a modular design concept that places a self-contained polarimeter module on the front-end of …

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A Construction Of Orthogonal Compactly-Supported Multiwavelets On $\R^{2}$, Bruce Kessler Nov 1999

A Construction Of Orthogonal Compactly-Supported Multiwavelets On $\R^{2}$, Bruce Kessler

Mathematics Faculty Publications

This paper will provide the general construction of the continuous, orthogonal, compactly-supported multiwavelets associated with a class of continuous, orthogonal, compactly-supported scaling functions that contain piecewise linears on a uniform triangulation of $\R^2$. This class of scaling functions is a generalization of a set of scaling functions first constructed by Donovan, Geronimo, and Hardin. A specific set of scaling functions and associated multiwavelets with symmetry properties will be constructed.

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Interacting Topological Defects On Frozen Topographies, Mark Bowick, David R. Nelson, Alex Travesset Nov 1999

Interacting Topological Defects On Frozen Topographies, Mark Bowick, David R. Nelson, Alex Travesset

Physics - All Scholarship

We propose and analyze an effective free energy describing the physics of disclination defects in particle arrays constrained to move on an arbitrary two-dimensional surface. At finite temperature the physics of interacting disclinations is mapped to a Laplacian Sine-Gordon Hamiltonian suitable for numerical simulations. We then specialize to the case of a spherical crystal at zero temperature. The ground state is analyzed as a function of the ratio of the defect core energy to the Young's modulus. We argue that the core energy contribution becomes less and less important in the limit R >> a, where R is the radius of …

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Remote Sensing Of Photosynthetic-Light-Use Efficiency Of Boreal Forest, Caroline J. Nichol, Karl F. Huemmrich, T. Andrew Black, Paul G. Jarvis, Charles L. Walthall, John Grace, Forrest G. Hall Nov 1999

Remote Sensing Of Photosynthetic-Light-Use Efficiency Of Boreal Forest, Caroline J. Nichol, Karl F. Huemmrich, T. Andrew Black, Paul G. Jarvis, Charles L. Walthall, John Grace, Forrest G. Hall

United States National Aeronautics and Space Administration: Publications

Using a helicopter-mounted portable spectroradiometer and continuous eddy covariance data we were able to evaluate the photochemical reflectance index (PRI) as an indicator of canopy photosynthetic light-use efficiency (LUE) in four boreal forest species during the Boreal Ecosystem Atmosphere experiment (BOREAS). PRI was calculated from narrow waveband reflectance data and correlated with LUE calculated from eddy covariance data. Significant linear correlations were found between PRI and LUE when the four species were grouped together and when divided into functional type: coniferous and deciduous. Data from the helicopter-mounted spectroradiometer were then averaged to represent data generated by the Airborne Visible Infrared …

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Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires Nov 1999

Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires

Faculty Publications

We have developed a new family of EUV multilayer mirror coatings using uranium. Using this approach we have coated a set of six mirrors for the EUV Imager, a component of the IMAGE mission. This mission is a Medium Explorer (MIDEX) program, which is scheduled for launch early in 2000. The EUV Imager will study the distribution of He+ in the Earth's plasmasphere by detecting its resonantly scattered emission at 30.4 nm (41 eV) and will produce images of the structure and dynamics of the cold plasma on a global scale. There is, however, a bright at 58.4 nm (21 …

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On Measuring The Cost Of Children:The Case Of Rural Maharashtra., Manisha Chakrabarty Dr. Nov 1999

On Measuring The Cost Of Children:The Case Of Rural Maharashtra., Manisha Chakrabarty Dr.

Doctoral Theses

In this dissertation we have attempted to measure the cost of children, which plays a crucial role in matters relating to welfare and public policy like child benefits and compensation policies of the government. The cost is measured based on the single equation as well as the systems approach using the 38th round National Sample Survey (NSS) data on household consumer expenditure for rural Maharashtra (relating to the period of January to December, 1983).The first chapter provides a brief account of the basic literature on empirical demand analysis which is relevant for welfare comparison between households. To be specific in …

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Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida Nov 1999

Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida

Faculty Publications

We report the observation of narrower structures in the yellow luminescence of bulk and thin-film n-type GaN, using the technique of selective excitation. These fine structures exhibit thermal quenching associated with an activated behavior. We attribute these fine structures to phonons and electronic excitations of a shallow donor-deep acceptor complex, and determine its activation energy for delocalization. Our results suggest that in addition to distant donor-acceptor pairs, the yellow luminescence can also involve emission complexes of shallow donors and deep acceptors.

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Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter Nov 1999

Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter

Donald Umstadter Publications

The authors seek to review injection concepts for plasma based acceleration. It is shown that regardless of injection mechanism, resultant beams will be similar due to wave structure. Also, most schemes employ the same basic processes, namely the dephasing of electrons by laser fields, and can thus be analyzed with similar approaches.

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Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter Nov 1999

Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter

Donald Umstadter Publications

Acceleration of electrons in a self-modulated laser-wakefield is investigated. The generated electron beam is oberved to have a multi-component beam profile and its energy distribution undergoes discrete transitions as the conditions are varied. These features can be explained by simple simulations of electron propagation in a 3-D plasma wave.

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Subsidence, Mixing, And Denitrification Of Arctic Polar Vortex Air Measured During Polaris, M. Rex, R. J. Salawitch, G. C. Toon, B. Sen, J. J. Margitan, G. B. Osterman, J. F. Blavier, R. S. Gao, Stephen G. Donnelly Ph.D., E. Keim, J. Neuman, D. W. Fahey, C. R. Webster, D. C. Scott, R. L. Herman, R. D. May, E. J. Moyer, M. R. Gunson, F. W. Irion, A. Y. Chang, C. P. Rinsland, T. P. Bui Nov 1999

Subsidence, Mixing, And Denitrification Of Arctic Polar Vortex Air Measured During Polaris, M. Rex, R. J. Salawitch, G. C. Toon, B. Sen, J. J. Margitan, G. B. Osterman, J. F. Blavier, R. S. Gao, Stephen G. Donnelly Ph.D., E. Keim, J. Neuman, D. W. Fahey, C. R. Webster, D. C. Scott, R. L. Herman, R. D. May, E. J. Moyer, M. R. Gunson, F. W. Irion, A. Y. Chang, C. P. Rinsland, T. P. Bui

Chemistry Faculty Publications

We determine the degree of denitrification that occurred during the 1996-1997 Arctic winter using a technique that is based on balloon and aircraft borne measurements of NOy, N2O, and CH4. The NOy/N2O relation can undergo significant change due to isentropic mixing of subsided vortex air masses with extravortex air due to the high nonlinearity of the relation. These transport related reductions in NOy can be difficult to distinguish from the effects of denitrification caused by sedimentation of condensed HNO3. In this study, high-altitude balloon measurements are used to define the properties of air masses that later descend in the polar …

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Light Scalar Mesons, Joseph Schechter, Deirdre Black, Amir H. Fariborz Nov 1999

Light Scalar Mesons, Joseph Schechter, Deirdre Black, Amir H. Fariborz

Physics - All Scholarship

We review how a certain effective chiral Lagrangian approach to pi pi scattering, pi K scattering and eta-prime decay to eta pi pi provides evidence for the existence of light scalars sigma(550) and kappa(900) as well as describing the f0(980) and the a0(980). An attempt to fit these into a nonet suggests that their structure is closer to a dual quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain the next higher mass scalar nonet is also proposed.

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Immaccs: A Military Decision-Support System, Jens G. Pohl, Anthony A. Wood, Kym Jason Pohl, Arthur J. Chapman Nov 1999

Immaccs: A Military Decision-Support System, Jens G. Pohl, Anthony A. Wood, Kym Jason Pohl, Arthur J. Chapman

Collaborative Agent Design (CAD) Research Center

The Integrated Marine Multi-Agent Command and Control System (IMMACCS) is a multi-agent, distributed system, designed to provide a ‘common tactical picture’ with integrated and meaningful decision-support facilities to authorized operators at any access node. IMMACCS has been implemented as a three-tier architecture that distinguishes between information, logic and presentation. It utilizes an object-serving communication facility with subscription and multi-casting capabilities that is based on the Common Object Request Broker Architecture (CORBA). With an emphasis on application, IMMACCS was designed and implemented in concert with its military users as an integral component of experiments conceived by the Marine Corps Warfighting Laboratory …

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Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben Nov 1999

Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben

Peter Dowben Publications

Metallocene adsorption on clean Si(111) and CaF2/CaF1/Si(111) substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale. ©1999 American Institute of Physics.

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Evaluating Maximum Likelihood Estimation Methods To Determine The Hurst Coefficient, Christina Marie Kendziorski, J. B. Bassingthwaighte, Peter J. Tonellato Nov 1999

Evaluating Maximum Likelihood Estimation Methods To Determine The Hurst Coefficient, Christina Marie Kendziorski, J. B. Bassingthwaighte, Peter J. Tonellato

Mathematics, Statistics and Computer Science Faculty Research and Publications

A maximum likelihood estimation method implemented in S-PLUS (S-MLE) to estimate the Hurst coefficient (H) is evaluated. The Hurst coefficient, with 0.5<HS-MLE was developed to estimate H for fractionally differenced (fd) processes. However, in practice it is difficult to distinguish between fd processes and fractional Gaussian noise (fGn) processes. Thus, the method is evaluated for estimating H for both fd and fGn processes. S-MLE gave biased results of H for fGn processes of any length and for fd processes of lengths less than 210. A modified method is proposed to correct for …

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Generalized Averages For Solutions Of Two-Point Dirichlet Problems, Philip Korman, Yi Li Nov 1999

Generalized Averages For Solutions Of Two-Point Dirichlet Problems, Philip Korman, Yi Li

Mathematics and Statistics Faculty Publications

For very general two-point boundary value problems we show that any positive solution satisfies a certain integral relation. As a consequence we obtain some new uniqueness and multiplicity results.

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