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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Synthesis and characterization of low-melting thermotropic liquid crystalline poly(ester-imide)s /

Jacob, Sunny. January 1994 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 1994. / Typescript. Includes bibliographical references (leaves 118-124).
72

Simulation of thermal stresses in vacuum arc remelting process

Wani, Nitin Yashwant. January 1995 (has links)
Thesis (M.S.)--Ohio University, November, 1995. / Title from PDF t.p.
73

Confinement effect on semiconductor nanowires properties

Nduwimana, Alexis. January 2007 (has links)
Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2008. / Committee Chair: Chou, Mei-Yin; Committee Member: First,Phillip; Committee Member: Gao, Jianping; Committee Member: Landman, Uzi; Committee Member: wang, Xiao-Qian.
74

Transfer function model for oxy-fuel fired batch tank

Rhodes, James Robert, January 2001 (has links)
Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 110 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 81-82).
75

Enhanced design for oxy-fuel fired batch tanks using CFD methods

Kang, Guosheng. January 2000 (has links)
Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains x, 153 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 150-153).
76

Monte Carlo simulations to study the effect of chain stiffness on static, dynamic, and equation-of-state properties of polymer melts

Khanal, Kiran. January 2009 (has links)
Thesis (M.S.)--University of Akron, Dept. of Physics, 2009. / "August, 2009." Title from electronic thesis title page (viewed 10/21/2009) Advisor, Jutta Luettmer-Strathmann; Committee members, Alper Buldum, Ben Yu-Kuang Hu; Department Chair, Robert R. Mallik; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
77

Elongational flow of polymer melts

Stevenson, James Francis, January 1970 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references.
78

Crossover from unentangled to entangled dynamics Monte Carlo simulation of polyethylene, supported by NMR experiments /

Lin, Heng. January 2006 (has links)
Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Science, 2006. / "May, 2006." Title from electronic dissertation title page (viewed 10/11/2006) Advisor, Wayne L. Mattice; Committee members, Ernst D. von Meerwall, Ali Dhinojwala, Gustavo A. Carri, Richard J. Elliott; Department Chair, Mark D. Foster; Dean of the College, Frank N. Kelley; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
79

Partial Melting Experiments on an Mg # 80 Martian Mantle and Their Implications for Basalt Genesis

Chartrand, Zachary Adam 01 August 2014 (has links)
Dreibus and Wänke (1985) calculated a bulk composition for the interior of Mars (DW model) based on eight Martian meteorites. Since then, experiments on the Martian interior have used this model, or similar models, to understand processes that may influence basalt genesis within the Martian mantle. Recent experiments have shown that the DW model does not fit with the current, now greater number of Martian meteorites (132 including paired stones as of April 2014) and surface basalt compositions. One of the parameters that does not match is the Mg # (atomic [Mg2+/(Mg2+ + Fe2+)]*100); the current data show that Mars is not as iron rich as once thought and needs a higher bulk Mg # for the mantle to produce Martian basaltic compositions. This project involves experiments using a new bulk composition with an Mg # of 80 to update the compositions of a partially melted Martian mantle. A melt produced by this new bulk composition consists of MgO and FeO levels that match well with the primitive Martian meteorite Yamato-980459. Additionally, this composition was produced with 37% melt. Melts produced with this bulk composition match poorly with Na2O composition of Martian meteorites and match better, but still not particularly well, with CaO and Al2O3 compositions. However, lower-temperature partial melts of the Mg # 80 mantle match well with CaO, Al2O3, FeO, and Na2O compositions of Martian surface basalts. This shows that the source of the surface basalts is represented well by the model in this study.
80

Estudo de sistemas coloidais fortemente correlacionados / Study of strongly correlated colloidal systems

Ramos, Igor Rochaid Oliveira January 2014 (has links)
RAMOS, Igor Rochaid Oliveira. Estudo de sistemas coloidais fortemente correlacionados. 2014. 113 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2014. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-10-31T20:49:57Z No. of bitstreams: 1 2014_tese_iroramos.pdf: 4160505 bytes, checksum: 1c5b95406b1be080fece98a7bc0bf05a (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2014-10-31T21:06:33Z (GMT) No. of bitstreams: 1 2014_tese_iroramos.pdf: 4160505 bytes, checksum: 1c5b95406b1be080fece98a7bc0bf05a (MD5) / Made available in DSpace on 2014-10-31T21:06:33Z (GMT). No. of bitstreams: 1 2014_tese_iroramos.pdf: 4160505 bytes, checksum: 1c5b95406b1be080fece98a7bc0bf05a (MD5) Previous issue date: 2014 / This thesis presents the study of the structural and dynamical properties, as well as, melting of colloidal systems. Initially, we study the structure and phonon spectrum of a system of charged magnetic dipoles, organized in a bilayer structure and oriented perpendicular to the plane of the layers. This system can be tuned through six different crystalline phases by changing parameters such as the interlayer separation and/or the charge and/or dipole moment of the particles. The presence of the electric charge on the dipole particles is responsible for the nucleation of five staggered phases and a disordered phase which are not found in the magnetic dipole bilayer system previously presented in the literature. These extra phases are a consequence of the competition between the repulsive Coulomb and the attractive dipole interlayer interaction. The minimum energy structures are summarized in a phase diagram associated to the separation between the layers and to the relative importance between the magnetic and electric interactions. We determine the order of the structural phase transitions. The phonon spectrum of the system was calculated within the harmonic approximation. A non-monotonic behavior of the phonon spectrum is found as a function of the effective strength of the inter-particle interaction. The thermodynamic stability of the different phases is determined. Then, we study the bilayer system of charged magnetic dipoles for nonzero temperatures, investigating the melting behavior of the system through the modified Lindemann criterion, as a function of the parameters: (i) the distance between the layers η and (ii) the relative intensity of the magnetic interaction with respect to the electric interaction λ. For large enough λ, one of the phases (the matching hexagonal phase) exhibits a re-entrant melting behavior as a function of η. Since the charges and the magnetic dipole moment of the colloidal particles can be altered, for example, by changing the pH of the solution in which they are immersed or an external magnetic field, respectively, this system can be in principle verified experimentally. Last, a two-dimensional (2D) binary colloidal system consisting of interacting dipoles is investigated. Within the harmonic approximation, we obtained the phonon spectrum of the system as a function of the composition, dipole moment ratio and mass ratio between the small and big particles. Through a systematic analysis of the phonon spectra, we are able to determine the stability region of the different lattice structures of colloidal alloys. The gaps in the phonon frequency spectrum, the optical frequencies in the long-wavelength limit and the sound velocity are discussed as well. Using the modified Lindemann criterion and within the harmonic approximation, we estimated the melting temperature of the sub-lattice generated by the big particles. / Nesta tese, estudamos as propriedades estruturais e dinâmicas, bem como, a fusão de sistemas coloidais. Inicialmente, abordamos o problema de determinar as estruturas de mínima energia e o espectro de fônons de um sistema de dipolos magnéticos carregados, organizados em uma estrutura de bicamadas e orientados perpendicularmente ao plano das camadas. Este sistema pode ser sintonizado através de seis diferentes fases cristalinas, através da variação de parâmetros tais como a separação entre as camadas e/ou a carga e/ou o momento de dipolo das partículas. A presença de carga elétrica nas partículas dipolares é responsável pela nucleação de cinco fases onde as camadas não estão alinhadas verticalmente e uma fase desordenada, que não são encontradas no sistema em bicamadas de dipolos magnéticos previamente apresentado na literatura. Estas fases extras são uma consequência da competição entre a repulsão coulombiana e a interação atrativa entre os dipolos em diferentes camadas. As estruturas de mínima energia são sumarizadas em um diagrama de fases associado à separação entre camadas e a importância relativa entre as interações elétrica e magnética. Determinamos, ainda, a ordem das transições estruturais entre as várias configurações de mínima energia. O espectro de fônons do sistema foi calculado usando a aproximação harmônica. Um comportamento não-monotônico do espectro de fônons é encontrado como função da interação efetiva entre as partículas. A estabilidade termodinâmica das diferentes fases é determinada. Em seguida, estudamos o sistema de bicamadas de dipolos magnéticos carregados para temperaturas diferentes de zero, investigando a fusão do sistema através do critério de Lindemann modificado, em função dos parâmetros: (i) a distância entre as camadas η e (ii) a intensidade relativa da interação magnética com respeito à interação elétrica λ. Para λ suficientemente grande, uma das fases (a fase hexagonal com alinhamento vertical) exibe um comportamento reentrante na temperatura de fusão em função de η. Uma vez que a carga e o momento de dipolo magnético das partículas coloidais pode ser alterado, por exemplo, pela variação do pH da solução na qual estão imersos e por um campo magnético externo, respectivamente, este sistema pode ser em princípio verificado experimentalmente. Por último, um sistema bidimensional (2D) coloidal binário consistindo de dipolos interagentes é investigado. Dentro da aproximação harmônica, calculamos o espectro de fônons do sistema em função da composição, da razão entre os momentos de dipolo e da razão entre as massas das partículas pequenas e grandes. Através de uma análise sistemática dos espectros de fônons, determinamos a região de estabilidade das diferentes estruturas das ligas coloidais. As lacunas no espectro de frequência dos fônons, as frequências óticas no limite de longos comprimentos de onda e a velocidade do som são também discutidos. Usando o critério de Lindemann modificado e dentro da aproximação harmônica, estimamos a temperatura de fusão da sub-rede gerada pelas partículas grandes.

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