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Evaluation of zirconium-iron-rhenium alloys as surrogates for a technetium alloy waste formMews, Paul Aaron 10 October 2008 (has links)
Stainless steel - zirconium alloys were developed by the US Department of
Energy Laboratories as metallic waste forms for noble metal fission products. This
thesis evaluates iron-zirconium-rhenium alloys to establish a technical basis for using
metal waste form alloys for technetium-99 immobilization. Rhenium is used as a
surrogate for Tc-99 since Tc is not naturally available and Re is metallurgically similar
to Tc.
The iron-zirconium system has two eutectic compositions, Fe-15 wt % Zr and Zr-
16 wt% Fe. Ten test samples were successfully cast in yttrium oxide crucibles at
1600°C, half near each eutectic composition, with Re amounts varying from 2.5 to 12.5
weight percent.
A scanning electron microscope (SEM) with energy dispersive X-ray
spectroscopy (EDS) capability was employed to determine the phase structure and phase
composition of each sample. Iron rich samples were found to form up to three phases,
with the rhenium content favoring the intermetallic phases: 1) an Fe solid solution phase,
2) an FeZr2-type intermetallic with 11 wt % or less Re, and 3) a second intermetallic with about 18 wt % Re. Zirconium rich samples formed as many as five distinct phases:
1) a Zr solid solution phase, 2) a Zr3Fe-type intermetallic with as much as 13 wt% Re, 3)
a rhenium-zirconium intermetallic, 4) another Fe-Zr intermetallic with very little Re, and
5) a Fe-Re intermetallic.
Potentiostatic and potentiodynamic electrochemical tests were performed using
sulfuric acid to evaluate the corrosion resistance of each sample. These tests found that
the zirconium rich samples were very corrosion resistant but became increasingly
susceptible at higher rhenium concentrations. The iron rich samples were not very
resistant to corrosion under the test conditions; there was no notable trend in corrosion
behavior related to the introduction of rhenium.
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3D-visualisering av molekylmodellerHaraldsson, Elin January 2007 (has links)
<p>Naturvetenskapen är abstrakt, speciellt inom kemin. Atomer och molekyler är osynliga och måste åskådliggöras med strukturer och modeller. Modeller kan man bygga för hand med hjälp av kulor och pinnar eller så kan man visualisera modeller på datorn. För det första är det intressant att veta hur modeller visualiseras i läroböcker. För det andra hur eleverna tolkar visualiseringarna. För det tredje vilken attityd eleverna har till 3D-visualisering. En förstudie för identifikation av innehållsligt fokus utfördes. Vidare analyserade jag läroböcker genom att till att börja med identifiera de bilder som används i respektive bok i de avsnitt där dipol och geometrisk form behandlas och därefter följer en analys av de utvalda bilderna. Mot bakgrund av ovanstående resonemang har jag undersökt hur elever tolkar dipol och geometrisk form genom bildanalys av läroboksbilder och interaktiva 3D-modeller. Elever fick svara på enkäter med öppna frågor som sedan bearbetades för att se skillnader och likheter vad eleverna visualiserat. Vidare utformades en enkät utefter likertsystemet för att undersökta elevernas attityd till 3D-visualisering. Undersökningen visar dessutom hur eleverna läser en lärobok eftersom en fråga var utformad för att ge svar på det. Resultatet av min undersökning blir alltså att förstudien visar att elever anser dipol abstrakt. Läroböcker visar relativt många modeller och olika varianter av modeller. Vidare använder man sig av de konventionella symbolerna δ- och δ+. De flesta visar en bild från vardagen. Enligt min undersökning finns det vissa skillnader och likheter på hur eleverna tolkar läroboksbilder och 3D-visualisering. Eleverna är positiva till 3D-visualisering och de anser att det abstrakta blivit mer konkret med 3D-visualisering.</p>
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The history & sources of Percy's Memoir of GoldsmithBalderston, Katharine Canby, January 1926 (has links)
Thesis (Ph. D.)--Yale University, 1925.
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Characteristics and strategies of Bible college fund-raising lettersFincher, David B., January 2003 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 246-265). Also available on the Internet.
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Cadence and form in Hindemith's "Lilacs" requiem /Turner, Jonathan J. Whitman, Walt, January 1996 (has links)
Thesis (Ph. D.)--University of Rochester, Eastman School of Music, 1996. / Includes vita and abstract. Accompanies: First symphony / by Jonathan J. Turner (1 score (107 p.) ; 28 cm.). Includes bibliographical references. Digitized version available online via the Sibley Music Library, Eastman School of Music http://hdl.handle.net/1802/5752
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Billing below title the contested autobiographies of Frances Farmer and Louise Brooks /Anderson, Karen M. January 2003 (has links)
Thesis (M.A.)--Marshall University, 2003. / Title from document title page. Document formatted into pages; contains v, 85 p. Includes bibliographical references (p. 78-85).
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Coherence and historical understanding in children's biography and historical nonfiction literature : a content analysis of selected Orbis Pictus books /Wilson, Sandip LeeAnne, January 2001 (has links)
Thesis (Ed. D.) in Literacy Education--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 304-318).
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Characteristics and strategies of Bible college fund-raising letters /Fincher, David B., January 2003 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 246-265). Also available on the Internet.
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Der kindliche Ich-Erzähler in der modernen Kinderliteratur eine erzähltheoretische Analyse mit Blick auf aktuelle KinderromaneHofmann, Regina January 2009 (has links)
Zugl.: Giessen, Univ., Diss., 2009
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Inexact ProgrammingMahmood, Muhammad Yasir January 2012 (has links)
Two types of fuzzy linear programming i.e. fuzzy number linear programming and interval number linear programming are used for optimization problems. In interval form of linear programming we convert the inequalities from the feasible region, containing intervals as coefficients, to two groups of inequalities characterized by real, exact coefficients values. Then classical programming has been used to achieve an optimal solution in the feasible region. In fuzzy number linear programming, α‐cuts and LR forms of fuzzy numbers as coefficients have been used to find optimal solution in the feasible region. Finally the numerical examples and their solutions are attached to provide explanations of procedures.
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