Current Search: Lu, Huizong (x)
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Title
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Experimental studies of yttrium barium(2)(copper(1-x)iron(x))(3)oxygen(7+delta) and bismuth(2)strontium(2)calcium(n-1)copper(n)oxygen(2n+4) high T(c) superconductors.
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Creator
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Lu, Huizong, Florida Atlantic University, Medina, Fernando D.
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Abstract/Description
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Fe-substituted Y123 and Bi-based high Tc superconducting samples were prepared and studied. Magnetic susceptibility measurements, x-ray diffraction and Scanning Electron Microscopy were used to study the transition temperature Tc, preferential grain orientation and phase formation of the compounds. Tc was found to decrease more rapidly with Fe concentrations above 2.5%. Thermally reducing the oxygen content shows that Fe clusters form at high Fe concentrations. Magnetic susceptibility and x...
Show moreFe-substituted Y123 and Bi-based high Tc superconducting samples were prepared and studied. Magnetic susceptibility measurements, x-ray diffraction and Scanning Electron Microscopy were used to study the transition temperature Tc, preferential grain orientation and phase formation of the compounds. Tc was found to decrease more rapidly with Fe concentrations above 2.5%. Thermally reducing the oxygen content shows that Fe clusters form at high Fe concentrations. Magnetic susceptibility and x-ray diffraction measurements show that only the 80 K phase is present in Bi4Sr3Ca3Cu6Ox samples. For Bi0.7Pb0.3SrCaCu1.8Ox and Bi1.8Pb0.2Sr2Ca2Cu3Ox samples, the 110 K phase becomes dominant after sintering for 126 hours and 48 hours respectively. Preferential grain orientation was also observed in these materials.
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Date Issued
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1990
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PURL
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http://purl.flvc.org/fcla/dt/14643
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Subject Headings
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High temperature superconductivity, High temperature superconductors
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Format
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Document (PDF)
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Title
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Critical behavior of forest fires: Theory and numerical simulations.
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Creator
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Lu, Huizong, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
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Abstract/Description
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Forest fire is an integral part of natural ecosystems. Understanding the mechanisms governing the formation and propagation of forest fire is imperative for effectively managing the natural resources of a forest and minimizing or eliminating damages caused by uncontrolled forest fire. Numerical simulation of two-dimensional forest fires indicates that there is a critical state at which the fire is likely to spread to the entire forest. The effects of wind conditions and multiple tree species...
Show moreForest fire is an integral part of natural ecosystems. Understanding the mechanisms governing the formation and propagation of forest fire is imperative for effectively managing the natural resources of a forest and minimizing or eliminating damages caused by uncontrolled forest fire. Numerical simulation of two-dimensional forest fires indicates that there is a critical state at which the fire is likely to spread to the entire forest. The effects of wind conditions and multiple tree species are studied using numerical simulations and various Mean Field Approximations. Results from the analytical calculations agree well with numerical simulations for square lattice forest fire. Other lattice structures are also investigated. Mathematical models with non-linearly coupled equations are derived to study finite, layered, pseudo-two-dimensional forest fires. Critical states can be predicted by evaluating these non-lineady coupled equations.
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Date Issued
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2000
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PURL
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http://purl.flvc.org/fcla/dt/12645
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Subject Headings
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Agriculture, Forestry and Wildlife
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Format
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Document (PDF)