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INFLUENCE OF FILM THICKNESS ON OXYGEN DETERMINATION IN HIGH-TC MATERIALS BY RBS

NUCLEAR INSTRUMENTS & METHODS IN physics RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 1991年第PART 2期56-7卷 776-779页

作者： TIDROW, SC FISCHBECK, HJ Engineering Physics Program University of Oklahoma Norman OK 73019 USA

RBS determination of oxygen content in high T(c) materials deposited on substrates for oriented film growth, such as SiO2, MgO, Al2O3 and SrTiO3, can be difficult due to substrate interference. This is especially the case if the relatively small oxygen signal from the film appears on a large substrate signal and is overlapping the oxygen signal from the substrate. We will show oxygen determination in films can be significantly improved by properly choosing film thickness and incident beam energy such that the front edge of the oxygen signal from the film is separated from the substrate signal. RBS analysis of varying thickness La1.8Sr(x)Cu(y)O(z) films, deposited on SiO2 and MgO substrates by a rf planar magnetron, is shown. RBS simulation is used to demonstrate the importance of film thickness and beam energy for the determination of oxygen in high T(c) material films deposited on other substrates.

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Plasma startup of the ARIES-III second stability advanced fuel tokamak 14

Plasma startup of the ARIES-III second stability advanced fu...

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14th IEEE/NPSS Symposium Fusion engineering, FUSION 1991

作者： Emmert, G.A. Mogahed, E.A. Kessell, C. Mandrekas, J. Mau, T.-K. Fusion Technology Institute University of Wisconsin-Madison Madison WI53706-1687 United States Princeton Plasma Physics Laboratory Princeton University PrincetonNJ08544 United States Fusion Research Center Georgia Institute of Technology AtlantaGA30332 United States Fusion Engineering and Physics Program University of California Los AngelesCA90024 United States

ISBN: (纸本)0780301323

The ARIES-III conceptual reactor design utilizes D-3He fuel in a second stability tokamak configuration. The process of starting up the plasma and bringing it to the desired operating point was analyzed using a time-dependent particle and power balance code in conjunction with MHD (magnetohydrodynamic) equilibrium and stability, and neutral beam current drive calculations. Two different startup scenarios, one using D-T to assist reaching the D-3He operating point and one using only pure D-3He, were analyzed. In order to minimize the amount of ICRF (ion cyclotron range of frequencies) auxiliary heating required, one must program the plasma current so that the plasma enters second stability as soon as practical;it was assumed that confinement improves greatly when the plasma is in second stability. Seeding the plasma with tritium during startup reduces the amount of ICRF power required, but leads to a 14-MeV neutron pulse. The blanket and magnet heating due to this neutron pulse are within acceptable limits. The DT assisted startup was chosen as the reference procedure. © 1991 IEEE.

关键词： Magnetoplasma

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A ventricular model with a 3-D fractal conduction network

A ventricular model with a 3-D fractal conduction network

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Computers in Cardiology (CinC)

作者： D. Eylon A. Beker S. Abboud D. Sadeh Medical Physics Group Tel-Aviv University Tel-Aviv Israel Biomedical Engineering Program Tel-Aviv University Tel-Aviv Israel

A 3-D electrical model of the heart's ventricles is introduced. The model consists of 75*75*75 (or 421875) cubical finite elements arranged inside a cube. Each of these elements can be defined as one of several types of cells, characterized by various electrophysiological attributes, such as conduction velocity and action potential shape. Inside this structure, a general geometrical form similar to the general shape of the heart's ventricles is defined. A specialized group of elements simulates the heart's conduction system. This group has the 3-D structure of a bifurcating, self-similar tree, which is connected to bundle branches and a bundle of His. Preliminary traces of the electrical activity of the model show similarity to physiological QRST complexes.< >

关键词： Fractals Myocardium Bifurcation Solid modeling Finite element methods Shape physics Biomedical engineering Contracts Surface morphology

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The circular nature of discrete-time frequency estimates

The circular nature of discrete-time frequency estimates

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： B.C. Lovell P.J. Kootsookos R.C. Williamson Department of Electrical Engineering University of Queensland Brisbane Australia Department of Systems Engineering R.S. Physics Science and Engineering Australian National University Canberra Australia Department of Systems Engineering and Interdisciplinary Program in Engineering Australian National University Canberra Australia

It is shown that the conventional (linear) definitions of mean and variance can yield absurd results when applied to data defined on a circular domain. Appropriate definitions for the mean, variance, and moments of circular data are given, and these concepts are applied to reformulate a recently proposed frequency estimator to avoid bias and elevated threshold effects. The maximum likelihood frequency estimator is shown to be equivalent to least-squares regression on phase estimates. These results demonstrate the importance of appreciating the true circular nature of many quantities commonly encountered in digital signal processing.< >

关键词： Frequency estimation Discrete Fourier transforms Australia Data visualization Convolution Systems engineering and theory Sampling methods Data analysis Signal processing Arithmetic

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Application of the monolithic solid oxide fuel cell to space power systems

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AIP Conference Proceedings 1991年第1期217卷 61-66页

作者： Kevin M. Myles Samit K. Bhattacharyya Electrochemical Technology Program Chemical Technology Division Argonne National Laboratory 9700 South Cass Avenue Argonne Illinois 60439 Engineering Physics Division Argonne National Laboratory 9700 South Cass Avenue Argonne Illinois 60439

The monolithic solid‐oxide fuel cell (MSOFC) is a promising electrochemical power generation device that is currently under development at Argonne National Laboratory. The extremely high power density of the MSOFC leads to MSOFC systems that have sufficiently high energy densities that they are excellent candidates for a number of space missions. The fuel cell can also be operated in reverse, if it can be coupled to an external power source, to regenerate the fuel and oxidant from the water product. This feature further enhances the potential mission applications of the MSOFC. In this paper, the current status of the fuel cell development is presented—the focus being on fabrication and currently achievable performance. In addition, a specific example of a space power system, featuring a liquid metal cooled fast spectrum nuclear reactor and a monolithic solid oxide fuel cell, is presented to demonstrate the features of an integrated system.

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NEW TECHNIQUES IN WEAPON FIRING CUTOUT ZONE DESIGN

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NAVAL ENGINEERS JOURNAL 1991年第3期103卷 278-290页

作者： GEORGE, E The Author received his B.S. degree in mechanical engineering from the Georgia Institute of Technology in 1982 and a M.S. degree in physics from the Virginia Polytechnic Institute and State University in 1988. Since 1984 he has worked in the Pointing and Firing Cutout Zone Program at the Naval Surface Warfare Center concentrating on computer applications in weapon safety analyses.

Weapon pointing and firing zones are critical operational parameters which directly affect the safety and capability of weapon performance and ship mission. These zones are normally implemented in the weapon system and restrict areas of weapon movement and function allowing clearance for ship structure during weapon performance. The primary purpose of the zones is to ensure topside safety by preventing the weapon from firing into surrounding ship structure. Weapon pointing and firing zones are also used to integrate weapon and other shipboard equipment functions to avoid interference conflicts. The Naval Surface Warfare Center (NAVSWC) is the technical direction agent which designs weapon pointing and firing zones for every large caliber gun mount and rotating missile launcher on U.S. Navy ships. Because of the increasing complexity of topside operations and applications in computer technology, new methods are being developed to support NAVSWC weapon zone design efforts. This paper first summarizes present techniques in NAVSWC weapon zone analysis and design. The second part of the paper describes methods under development using graphic computer systems to conduct safety analyses for weapon zone design. The paper concludes with a review of future weapon cutout system improvements.

关键词： Naval Warfare

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EVALUATING THE EFFECTIVENESS OF GROUND-WATER EXTRACTION SYSTEMS

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GROUND WATER MONITORING AND REMEDIATION 1991年第1期11卷 119-124页

作者： HALEY, JL HANSON, B ENFIELD, C GLASS, J Jennifer Haley is a chemical engineer working in the Remedial Operations and Guidance Branch of the Hazardous Site Control Division/Office of Emergency and Remedial Response (U.S. EPA OS-220 401 M St. SW Washington D.C. 20460). One of her responsibilities during her three years at EPA has been completion of the EPA Guidance on Remedial Actions for Contaminated Ground Water at Superfund Sites. Prior to taking her current position at the EPA in May 1987 she worked for two years for the California Regional Water Quality Control Board overseeing ground water contamination investigations and cleanups in the South San Francisco Bay. She received a B.S. in chemical engineering from the University of California in Berkeley and an M.S. in environmental management from the University of San Francisco. Bill Hanson is an engineer with the U.S. Environmental Protection Agency (OS-220 401 M St. SW Washington D.C. 20460). He received both his B.S. in engineering and M.A. in environmental engineering from Duke University. Before joining the Environmental Protection Agency Hanson worked for several consulting engineering firms including CH2M Hill in Res ton Virginia. At EPA he first worked in the Effluent Guidelines Program where he was responsible for developing pretreatment and direct discharge regulations for the electroplating industry. Hanson has been with the Superfund program since its start. He is currently chief of the Remedial Operations and Guidance Branch. His branch is responsible for developing guidance for consistency of approach with respect to selection of remedy land ban treatment requirements and treatability protocols. Carl G. Enfield is a soil scientist at the Robert S. Ken Environmental Research Laboratory (U.S. EPA Office of Research and Development P.O. Box 1198 Ada OK 74820). He earned his B.S.C.E. in civil engineering and M.S. in agronomy at Purdue University and his Ph.D. in agricultural chemistry and soils at the University of Arizona. He currently serves as research director at EP

The most common process for remediating contaminated ground water is extraction and treatment. Data from 19 on-going and completed ground water extraction systems were collected and analyzed (U.S. EPA 1989b) to evaluate the effectiveness of this process in achieving cleanup concentration goals for ground water. This analysis indicated several trends including (1) containment of ground water plumes was usually achieved;(2) contaminant concentrations dropped significantly initially followed by a leveling out;(3) after the period of initial rapid decline, the continued decreases in concentration were usually slower than anticipated;and (4) certain data important to optimizing system design and operation had often not been collected during the site characterization phase. Factors limiting the achievement of cleanup concentration goals fell into four basic categories: (1) hydrogeological factors, such as subsurface heterogeneity, low-permeability units, and presence of fractures;(2) contaminant-related factors, such as high sorption to soil and presence of non-aqueous phases (dissolution from a separate non-aqueous phases (dissolution from a separate non-aqueous phase or partitioning of contaminants from the residual non-aqueous phase);(3) continued migration from source areas and the size of the plume itself;and (4) system design factors, such as pumping rates, screened intervals, and extraction well locations. The findings of this study indicate that ground water extraction is an effective method for preventing additional migration of contaminant plumes and achieving risk reduction. However, the findings indicate that in many situations, it may not be practicable to rely solely on ground water extraction and treatment to achieve health-based cleanup concentrations throughout the contaminated zone and fulfill the primary goal of returning ground water to beneficial use. This study suggests several recommendations (U.S. EPA 1989a) for improving ground water response acti

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MAGNETOHYDRODYNAMIC SUBMARINE PROPULSION SYSTEMS

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NAVAL ENGINEERS JOURNAL 1991年第3期103卷 141-157页

作者： SWALLOM, DW SADOVNIK, I GIBBS, JS GUROL, H NGUYEN, LV VANDENBERGH, HH Daniel W. Swallomis the director of military power systems at Avco Research Laboratory Inc. a subsidiary of Textron Inc. in Everett Mass. Dr. Swallom received his B.S. M.S. and Ph.D. degrees in mechanical engineering from the University of Iowa Iowa City Iowa in 1969 1970 and 1972 respectively. He has authored numerous papers in the areas of power propulsion and plasma physics and currently is a member of the Aerospace Power Systems Technical Committee of the AIAA. Dr. Swallom has directed various programs for the development of advanced power generation systems lightweight power conditioning systems and advanced propulsion systems for marine applications. His previous experience includes work with Odin International Corporation Maxwell Laboratories Inc. Argonne National Laboratory and the Air Force Aero Propulsion Laboratory. Currently Dr. Swallom is directing the technical efforts to apply magnetohydrodynamic principles to a variety of propulsion and power applications for various marine vehicles and power system requirements respectively. Isaac Sadovnikis a principal research engineer in the Energy Technology Office at Avco Research Laboratory Inc. a subsidiary of Textron Inc. He received his B.S. in engineering (1974) B.S. in physics (1975) M.S. in aeronautics and astronautics (1976) and Ph.D. in physics of fluids (1981) at the Massachusetts Institute of Technology. Dr. Sadovnik has been involved in research work funded by DARPA concerning the use of magnetohydrodynamics for underwater propulsion. He has built theoretical models that predict the hydrodynamic behavior of seawater flow through magnetohydrodynamic ducts and their interaction with the rest of the vehicle (thrust and drag produced). In addition Dr. Sadovnik has been involved in research investigations geared toward the NASP program concerning the use of magnetohydrodynamic combustion-driven accelerator channels. Prior to joining Avco Dr. Sadovnik was a research assistant at MIT where he conducted experimental and

Magnetohydrodynamic propulsion systems for submarines offer several significant advantages over conventional propeller propulsion systems. These advantages include the potential for greater stealth characteristics, increased maneuverability, enhanced survivability, elimination of cavitation limits, greater payload capability, and the addition of a significant emergency propulsion system. These advantages can be obtained with a magnetohydrodynamic propulsion system that is neutrally bouyant and can operate with the existing submarine propulsion system power plant. A thorough investigation of magnetohydrodynamic propulsion systems for submarine applications has been completed. During the investigation, a number of geometric configurations were examined. Each of these configurations and mounting concepts was optimized for maximum performance for a generic attack class submarine. The optimization considered each thruster individually by determining the optimum operating characteristics for each one and accepting only those thrusters that result in a neutrally buoyant propulsion system. The results of this detailed optimization study show that the segmented, annular thruster is the concept with the highest performance levels and greatest efficiency and offers the greatest potential for a practical magnetohydrodynamic propulsion system for attack class submarines. The optimization study results were used to develop a specific point design for a segmented, annular magnetohydrodynamic thruster for an attack class submarine. The design point case has shown that this thruster may be able to provide the necessary thrust to propel an attack class submarine at the required velocity with the potential for a substantial acoustic signature reduction within the constraints of the existing submarine power plant and the maintenance of neutral buoyancy. This innovative magnetohydrodynamic propulsion system offers an approach for submarine propulsion that can be an important contributio

关键词： Ship Propulsion

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A VLSI neural network for color constancy 90

A VLSI neural network for color constancy

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Proceedings of the 4th International Conference on Neural Information Processing Systems

作者： Andrew Moore Geoffrey Fox John Allman Rodney Goodman Computation and Neural Systems Program California Institute of Technology Pasadena CA Dept. of Physics Syracuse University Syracuse NY and Dept. of Physics California Institute of Technology Pasadena CA Dept. of Biology California Institute of Technology Pasadena CA Dept. of Electrical Engineering California Institute of Technology Pasadena CA

ISBN: (纸本)9781558601840

A system for color correction has been designed, built, and tested successfully; the essential components are three custom chips built using subthreshold analog CMOS VLSI. The system, based on Land's Retinex theory of color constancy, produces colors similar in many respects to those produced by the visual system. Resistive grids implemented in analog VLSI perform the smoothing operation central to the algorithm at video rates. With the electronic system, the strengths and weaknesses of the algorithm are explored.

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Corrigendum:‘‘Reconnection of two vortex rings’’ [Phys. Fluids A 1, 630 (1989)]

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physics of Fluids A: Fluid Dynamics 1990年第4期2卷 638-638页

作者： S. Kida M. Takaoka F. Hussain Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 Department of Physics Faculty of Science Kyoto University Kyoto 606 Japan Department of Mechanical Engineering University of Houston Houston Texas 77004

S. Kida, M. Takaoka, F. Hussain; Corrigendum:‘‘Reconnection of two vortex rings’’ [Phys. Fluids A 1, 630 (1989)]Comments, physics of Fluids A: Fluid Dynamics, V

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