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University of Arkansas, Fayetteville

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Articles 601 - 615 of 615

Full-Text Articles in Electrical and Computer Engineering

Comparison Of High-Temperature Superconductors In Multi-Chip Module Applications, D. E. Ford, S. S. Scott, S. S. Ang, W. D. Brown Jan 1994

Comparison Of High-Temperature Superconductors In Multi-Chip Module Applications, D. E. Ford, S. S. Scott, S. S. Ang, W. D. Brown

Journal of the Arkansas Academy of Science

In the application of high-temperature superconductors (HTSCs) in multi-chip module (MCM) technology, it is first necessary to investigate the advantages and disadvantages of the various HTSC compounds. The standard criteria for comparing the suitability of HTSCs in electronics applications has been critical temperature (Tc )and critical current density (Jc ). It is also necessary to consider the physical properties of HTSCs in relation to the various processing techniques required in fabrication of MCMs. These techniques can be grouped into four main areas: deposition, patterning, packaging, and characterization. The four main HTSC materials, Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Tl,Ba-Ca-Cu-O and Hg-Ba-Ca-Cu-O, will be compared …

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Using The Cern Program-Library Graphics And Interactive Data Display, Morgan T. Burks, Wilson H. Howe, Christine A. Byrd, Wilfred J. Braithwaite Jan 1994

Using The Cern Program-Library Graphics And Interactive Data Display, Morgan T. Burks, Wilson H. Howe, Christine A. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

Small scale Monte Carlo programming is growing rapidly due to the ease with which complex problems may be formulated by any programmer. These programmers may choose to exploit graphics and interactive displays available in the program library developed and maintained by CERN (the Center for European Nuclear Research). This paper outlines the use of graphics and interactive data display features of the CERN program library, developed for visualizing simulated data events in particle detectors. One example uses GEANT, CERN's Monte Carlo modeling program, to simulate 300 MeV/c protons incident on a silicon slab. Display packages for GEANT are available both …

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Gamma Ray Emissions From Binary Pulsar Systems, Tony A. Hall, Andrew T. Sustich Jan 1994

Gamma Ray Emissions From Binary Pulsar Systems, Tony A. Hall, Andrew T. Sustich

Journal of the Arkansas Academy of Science

A method is developed for estimating the gamma ray flux impinging upon the earth from production in binary pulsar systems. We calculate production of the 6.13 MeV gamma ray line characteristic of 16O. These are produced by protons emitted by the pulsar interacting with 16O atoms at the surface of the companion. We examine different types of companion stars and estimate the gamma ray flux at the earth as a function of proton emission from the pulsar and distance from the earth. Prospects for detection from earth are discussed.

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Multiple Sample Cryostat For The Determination Of Superconductor Properties, G. Burnside, Roger M. Hawk, Paul C. Mcleod Jan 1993

Multiple Sample Cryostat For The Determination Of Superconductor Properties, G. Burnside, Roger M. Hawk, Paul C. Mcleod

Journal of the Arkansas Academy of Science

Cryostats which are currently used to characterize the properties of superconductors between 4 K and 100 K are primarily single sample devices. The purpose of this paper is to present an instrument design which can hold up to five (5) one cm. diameter samples at a stable temperature (+ /-0.1K) within the above range specified while measurements of the sample properties are made.

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Sputter Deposition And Thallination Of Ti-Ba-Ca-Cu-O Superconducting Thin Films, T. H. Dhayagude, S. S. Ang, W. D. Brown Jan 1993

Sputter Deposition And Thallination Of Ti-Ba-Ca-Cu-O Superconducting Thin Films, T. H. Dhayagude, S. S. Ang, W. D. Brown

Journal of the Arkansas Academy of Science

Thallination techniques used for the fabrication of sputter-deposited TI2Ba2CaCu 2Ox and TI2Ba2Ca2Cu3Ox superconducting thin films were investigated. Differences in elemental composition of precursor Ba-Ca-Cu-O sputtering targets were found to yield different superconducting phases. Thallination conditions which yielded transition temperatures as high as 122 K for samples annealed in air are described. Finally, reactive ion etching of films using a mixture of chlorine and argon gases is discussed.

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Semi-Insulating Polysilicon Hetero- And Isotype Junctions On Silicon, R. M. Ranade, S. S. Ang, W. D. Brown Jan 1993

Semi-Insulating Polysilicon Hetero- And Isotype Junctions On Silicon, R. M. Ranade, S. S. Ang, W. D. Brown

Journal of the Arkansas Academy of Science

The effects of nitrogen trifluorideinthe gas stream during deposition of semi-insulating polysilicon (SIPOS) on the electrical characteristics of undoped (SIPSO)/p-Si, and n+-SIPOS/n-Si isotype junctions were investigated. The current-voltage characteristics of undoped SIPOS/p-Si heterojunctions exhibit a strong dependence on the oxygen content of the SIPOS film and depart from a hyperbolic sine behavior as the refractive index of the SIPOS increases.. The addition of nitrogen trifluoride decreases the current density of these undoped SIPOS/p-Si heterojunctions due presumably to the oxidation/hydrolysis of SiF species intoSiO2. The n+-SIPOS formed a rectifying isotype junction o n-Si. The forward current voltage characteristics exhibit two distinct …

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Properties Of Ruthenium Oxide Coatings, Roger M. Hawk, Kamesh V. Gadepally, David N. Patangia Jan 1991

Properties Of Ruthenium Oxide Coatings, Roger M. Hawk, Kamesh V. Gadepally, David N. Patangia

Journal of the Arkansas Academy of Science

Ruthenium oxide coatings have been deposited on titanium substrates using a flood coating process. These films were heat treated for varying times and temperatures. The resulting films subsequently were characterized by performing resistivity and SEM analyses. Resistivity of the ruthenium oxide coating was found to be extremely dependent upon the firing temperature. Effect of the process conditions and formulations of the coatings on the morphology with respect to their electrical characteristics is presented. Capacitors were fabricated using plates coated with ruthenium oxide coatings. Capacitance versus heat treatment temperatures are discussed and at one firing temperature (480'C), the capacitance was 50 …

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Data Acquisition And Control Program For Chromatography, M. Keith Hudson, William G. Hood Jan 1991

Data Acquisition And Control Program For Chromatography, M. Keith Hudson, William G. Hood

Journal of the Arkansas Academy of Science

No abstract provided.

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Principles And Clinical Applications Of Magnetic Resonance, Rao P. Gullapalli, Teresa T. Evans, Roger M. Hawk Jan 1990

Principles And Clinical Applications Of Magnetic Resonance, Rao P. Gullapalli, Teresa T. Evans, Roger M. Hawk

Journal of the Arkansas Academy of Science

A review is presented which covers the basic theory of nuclear magnetic resonance (NMR) with regard to angular momentum, magnetic moments, and the classical mechanical description of the NMR experiment. Longitudinal (T,) and Transverse (T2) relaxation times are defined as well as the basic pulse sequences used for their measurement. In particular, the 180°-t-90° and the Hahn Spin Echo pulse sequences are described in detail. Basic Magnetic Resonance Imaging (MRI) theory is discussed with regard to slice selection, frequency encoding, and phase encoding to define the imaged volume element. The equations defining the amount of Tt , T2 , and …

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Integrated Circuits Interconnect Metallization For The Submicron Age, Kamesh V. Gadepally, Roger M. Hawk Jan 1989

Integrated Circuits Interconnect Metallization For The Submicron Age, Kamesh V. Gadepally, Roger M. Hawk

Journal of the Arkansas Academy of Science

The interconnect metallization being used by the semiconductor industry has been aluminum or aluminum silicon. Aluminum silicon is being replaced by aluminum copper and aluminum copper silicon, due to its superior resistance to electromigration and hillock growth. This paper discusses the implementation of aluminum copper/silicon alloys in semiconductor processing, along with a review of the problems and advantages of the same.

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Versatile Potentiostat With Optional Computer Control, Gary L. Fuller, William A. Russell Jr., Roger M. Hawk, James D. Wilson, P. D. Bratton Jan 1989

Versatile Potentiostat With Optional Computer Control, Gary L. Fuller, William A. Russell Jr., Roger M. Hawk, James D. Wilson, P. D. Bratton

Journal of the Arkansas Academy of Science

A versatile potentiostat which can supply a maximum of 125 ma is described. The potentiostat uses readily available electronic components and an interface is detailed which allows the potentiostat optional computer control.

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Computer-Controlled Programmable Pulse Generator For A Jeol Jnm-Ft-1a Radio Frequency Amplifier Section Of A Nuclear Magnetic Resonance Spectrometer, William H. Russell, Roger M. Hawk Jan 1989

Computer-Controlled Programmable Pulse Generator For A Jeol Jnm-Ft-1a Radio Frequency Amplifier Section Of A Nuclear Magnetic Resonance Spectrometer, William H. Russell, Roger M. Hawk

Journal of the Arkansas Academy of Science

A microprocessor controlled programmable pulse generator was specifically designed to interface with the JEOL JNM-FT-1 A Radio Frequency (RF) section of a nuclear magnetic resonance (NMR) spectrometer. The programmable pulse generator was programmed and controlled by an IBM compatible computer. Statis rams were utilized as the programmable pulse generator's on board memory which were used to store the pulse sequences. Pulse widths can be programmed from 0.2 microseconds to 14.3 minutes. The JEOL RF section is unique in that it allows the pulse generator to control the phase of the RF transmitted to the NMR probe and whether the sample …

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Image Processing Instrumentation For Giardia Lamblia Detection, Cy R. Tamanaha, Mark A. Gross Jan 1989

Image Processing Instrumentation For Giardia Lamblia Detection, Cy R. Tamanaha, Mark A. Gross

Journal of the Arkansas Academy of Science

Currently, the identification and enumeration of Giardia Iamblia cysts are based upon microscopic methods requiring individuals proficient in this area. It is a tedious process which consumes time that could be constructively used elsewhere. This project attempts to alleviate that burden by employing a computer to automatically process Indirect Fluorescent Antibody (IFA) prepared slides using digital image processing techniques. A computer controlled frame grabber, in conjunction with a CCD TV camera mounted on the epi-fluorescence microscope phototube, captures the light intensities of the objects in view under the microscope objective. The captured image is stored as pixels, with each pixel …

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Application Of Geligam Software To The Analysis Of X-Ray Spectra, R. S. Saunders, Harold L. Pray, H. B. Eldridge Jan 1987

Application Of Geligam Software To The Analysis Of X-Ray Spectra, R. S. Saunders, Harold L. Pray, H. B. Eldridge

Journal of the Arkansas Academy of Science

No abstract provided.

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Random Wave Form Generator, Zaboj V. Harvalik Jan 1952

Random Wave Form Generator, Zaboj V. Harvalik

Journal of the Arkansas Academy of Science

No abstract provided.

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