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1.
Martel, Laura.
Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy.
Degree: Docteur es, Physique et chimie des matériaux, 2011, Université d'Orléans
URL: http://www.theses.fr/2011ORLE2034 
► La compréhension de la structure des verres est actuellement à l’origine de nombreuses recherches scientifiques. L’une des preuves expérimentale d’un certain ordre dans ceux-ci est…
(more)
▼ La compréhension de la structure des verres est actuellement à l’origine de nombreuses recherches scientifiques. L’une des preuves expérimentale d’un certain ordre dans ceux-ci est la séparation de phase. En effet, ce phénomène est lié à la présence dans ces matériaux amorphes d’au moins deux phases de composition chimique différentes. Ainsi, une étude des prémices de la séparation de phase de type nucléation-croissance dans des verres de silicate de sodium a été menée. La RMN c’est révélée la plus efficace pour cette étude. L’utilisation des expériences de corrélation 29Si-29Si a permis de sonder le réseau silicaté à des échelles plus grandes que celles communément considérées. Nous avons donc pu identifier ce phénomène, caractériser la composition des phases qui apparaissaient et enfin établi un lien avec la cristallisation observée pour de long temps de recuits. A l’inverse, la séparation de phase dans les aluminosilicates de calcium étant visible à l’échelle macroscopique, nous voulions donc suivre la diminution de la séparation de phase avec l’ajout d’alumine. Ainsi, en élaborant un protocole de synthèse spécifique, nous avons pu synthétiser ces verres à hautes températures. Ils ont été étudiés par le biais de la microscopie électronique et de la RMN. Comme ces verres sont composés de nano-domaines vitreux intégrés dans une matrice de composition différente, nous avons pu obtenir des matériaux nano-structurés de taille contrôlée. L’utilisation de la RMN nous a permis de montrer que l’aluminium s’insérait sous forme de « clusters » dans le réseau silicaté.
The understanding of the vitreous state is actually a center of great interest in inorganic chemistry. In fact, even if a glass is often described as a totally disordered material, presence of structures at the atomic scale has to be considered. One of the first experimental proof against the random network theory is the observation of phase separation. In fact, in these systems, at least two glasses with different compositions are observed. In this way, the first steps of phase separation in sodium silicate glasses have been studied. This was afforded with the NMR technique using 29Si-29Si correlations experiments. Thus, the silicon network was probed at higher distances compared with which was commonly observed in these glasses. Therefore, we have been able to identify this phenomenon at the atomic scale, to define the composition of each glassy phase and to do a link with crystallization which happened after long heat treatment of the glass. At the contrary phase separation in calcium aluminosilicate glasses can be observed at the macroscopic scale, observation of its decrease with increasing amount of alumina has been under the scope of this study. The main challenge of this study was to synthesized high temperature glasses. Since an efficient protocol has been implemented, we have been able to obtained nano-structured materials with a controlled size of nano-domains. This caracterisation of the material has been possible using electron microscopy.…
Advisors/Committee Members: Massiot, Dominique (thesis director).
Subjects/Keywords: Séparation de phase; Phase separation
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APA (6th Edition):
Martel, L. (2011). Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy. (Doctoral Dissertation). Université d'Orléans. Retrieved from http://www.theses.fr/2011ORLE2034
Chicago Manual of Style (16th Edition):
Martel, Laura. “Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy.” 2011. Doctoral Dissertation, Université d'Orléans. Accessed December 13, 2019.
http://www.theses.fr/2011ORLE2034.
MLA Handbook (7th Edition):
Martel, Laura. “Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy.” 2011. Web. 13 Dec 2019.
Vancouver:
Martel L. Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy. [Internet] [Doctoral dissertation]. Université d'Orléans; 2011. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2011ORLE2034.
Council of Science Editors:
Martel L. Etude de la séparation de phase dans des verres silicatés par résonance magnétique nucléaire haute résolution solide et microscopie electronique : Study of phase separation in silicate glasses using high resolution solid state nuclear magnetic resonance and electron microscopy. [Doctoral Dissertation]. Université d'Orléans; 2011. Available from: http://www.theses.fr/2011ORLE2034
University of Georgia
2.
Velasquez, Jose.
Infrared photodissociation investigations of metal carbonyl systems in the gas phase.
Degree: PhD, Chemistry, 2008, University of Georgia
URL: http://purl.galileo.usg.edu/uga_etd/velasquez_jose_200805_phd
► A brief survey of the history of metal carbonyls and their study is provided, and the methods for generating and studying metal containing species in…
(more)
▼ A brief survey of the history of metal carbonyls and their study is provided, and the methods for generating and studying metal containing species in the gas
phase are discussed. In the work presented, gas
phase metal ion-ligand complexes are generated with a laser vaporization/supersonic expansion source and studied with infrared photodissociation spectroscopy. Specifically, the atomic metal ion-carbonyl interactions of Au+ and Pt+ with CO and Mg+, Al+ and Ca+ with the organic carbonyl acetone are studied. These complexes' mass spectra and IR photodissociation breakdown patterns give clues about their gas
phase coordination number. Metal carbonyl interactions are usually interpreted with the famous Dewar-Chatt-Duncanson (DCD) model. In conjunction with calculations, when available, the IR spectra of these complexes are used to understand the binding interaction and structure. Complexes of Au+(CO)n, n = 3-6 fall under the heading of "nonclassical" metal carbonyls, as evidenced by their vibrational spectra which show shifts of 60-70 cm-1. These complexes have highly symmetric structures as suggested by the single peaks in their IR spectra. Complexes of Pt+(CO)n, n = 4-6, demonstrate only slightly blue shifted spectra of ~ 10 cm-1, and the interaction is suggested to be more of an offsetting synergy in the bonding motifs of the DCD model. In agreement with the previous work of Armentrout and coworkers, our findings indicate that gas
phase platinum cation has a preferred coordination number of four that is near square planar. Complexes of M+(acetone), M = Mg, Al and Ca, demonstrate classical red-shifted behavior due to their binding to the carbonyl oxygen. The shift each complex displays relative to free acetone can be interpreted in light of the metal's ionic radius Both the Mg+ and Ca+ complexes have unanticipated doublets in their spectra. These doublets are interpreted as being Fermi resonances with the help of density functional theory. The three studies reported here were aimed at understanding the fundamental interactions of organometallic systems with relevance to inorganic and biochemistry.
Advisors/Committee Members: Michael A. Duncan.
Subjects/Keywords: Gas Phase
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APA (6th Edition):
Velasquez, J. (2008). Infrared photodissociation investigations of metal carbonyl systems in the gas phase. (Doctoral Dissertation). University of Georgia. Retrieved from http://purl.galileo.usg.edu/uga_etd/velasquez_jose_200805_phd
Chicago Manual of Style (16th Edition):
Velasquez, Jose. “Infrared photodissociation investigations of metal carbonyl systems in the gas phase.” 2008. Doctoral Dissertation, University of Georgia. Accessed December 13, 2019.
http://purl.galileo.usg.edu/uga_etd/velasquez_jose_200805_phd.
MLA Handbook (7th Edition):
Velasquez, Jose. “Infrared photodissociation investigations of metal carbonyl systems in the gas phase.” 2008. Web. 13 Dec 2019.
Vancouver:
Velasquez J. Infrared photodissociation investigations of metal carbonyl systems in the gas phase. [Internet] [Doctoral dissertation]. University of Georgia; 2008. [cited 2019 Dec 13].
Available from: http://purl.galileo.usg.edu/uga_etd/velasquez_jose_200805_phd.
Council of Science Editors:
Velasquez J. Infrared photodissociation investigations of metal carbonyl systems in the gas phase. [Doctoral Dissertation]. University of Georgia; 2008. Available from: http://purl.galileo.usg.edu/uga_etd/velasquez_jose_200805_phd
University of Georgia
3.
Reed, Zachary David.
Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems.
Degree: PhD, Chemistry, 2009, University of Georgia
URL: http://purl.galileo.usg.edu/uga_etd/reed_zachary_d_200912_phd
► Metal oxide clusters of the form MnOm + (M=Y,La,In), transition metal carbonyl complexes of the form TM-(CO)n + (TM=Mn,Cu,Au), and mixed vanadium benzene carbonyl complexes…
(more)
▼ Metal oxide clusters of the form MnOm + (M=Y,La,In), transition metal carbonyl complexes of the form TM-(CO)n + (TM=Mn,Cu,Au), and mixed vanadium benzene carbonyl complexes of the form V-bz-(CO)n
+ are produced in the gas
phase by laser vaporization in a pulsed nozzle and detected with time-of-flight mass spectrometry. The metal oxide clusters are studied using fixed frequency photodissociation. A limited number of stoichiometries are found for each value of n. Clusters are mass selected and photodissociated using the third harmonic (355 nm) of an Nd:YAG laser. Larger clusters undergo fission to produce certain stable cation clusters. Yttrium and lanthanum oxides clusters of the form MO(M2O3)n
+ are found to be particularly stable, along with Y6O8+.
Density functional theory (DFT) calculations were performed to investigate the structures and bonding of these clusters. The stability of some indium oxide clusters, including In5O4+, In5O4+, and In3O2+ can be understood in terms of Wade’s Rules of electron counting. Other indium oxide clusters with enhanced stability do not follow Wade’s Rules, including In3O1+, and In2O+.
The carbonyl and mixed benzene-carbonyl complexes are studied using infrared photodissociation spectroscopy and density functional theory. Mn(CO)6+ has a completed coordination sphere, consistent with its expected 18 electron stability. All manganese carbonyl complexes feature red-shifted υCO. The argon tagged analogues of the small (n=1-6) complexes are studied by IRPD. The spin state of small clusters is observed to gradually decrease as additional ligands are added, from a quintet MnCO+ to
a singlet Mn(CO)5+. Copper carbonyl cations are observed to have blue-shifted υCO, demonstrating that they are non-classical carbonyls. Cu(CO)4+ has a completed coordination sphere, in line with the 18 electron rule. All small complexes are observed exclusively as singlets, but some triplet population is observed for n=7,8. This is explained in terms of the increased oscillator strengths of the triplets. Au(CO)n+ is demonstrated to have a completed coordination sphere at n=4, despite having significant
reduced binding energy for n=3,4. It is also a non-classical carbonyl. V-bz-(CO)n+ is demonstrated to have two different coordination numbers, with n=3 and n=4. Both feature redshifted υCO. The symmetric CO stretch is strongly activated in these complexes.
Advisors/Committee Members: Michael Duncan.
Subjects/Keywords: Gas phase
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APA (6th Edition):
Reed, Z. D. (2009). Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems. (Doctoral Dissertation). University of Georgia. Retrieved from http://purl.galileo.usg.edu/uga_etd/reed_zachary_d_200912_phd
Chicago Manual of Style (16th Edition):
Reed, Zachary David. “Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems.” 2009. Doctoral Dissertation, University of Georgia. Accessed December 13, 2019.
http://purl.galileo.usg.edu/uga_etd/reed_zachary_d_200912_phd.
MLA Handbook (7th Edition):
Reed, Zachary David. “Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems.” 2009. Web. 13 Dec 2019.
Vancouver:
Reed ZD. Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems. [Internet] [Doctoral dissertation]. University of Georgia; 2009. [cited 2019 Dec 13].
Available from: http://purl.galileo.usg.edu/uga_etd/reed_zachary_d_200912_phd.
Council of Science Editors:
Reed ZD. Fixed frequency dissociation of metal oxide cations and infrared photodissociation studies of metal carbonyl cation systems. [Doctoral Dissertation]. University of Georgia; 2009. Available from: http://purl.galileo.usg.edu/uga_etd/reed_zachary_d_200912_phd
University of Manchester
4.
Ward, Joseph.
MAX phase ceramics for nuclear applications.
Degree: 2018, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:314189
► The PhD research presented here is part of the new nuclear manufacturing (NNUMAN) research group, looking into novel materials and manufacturing processes. NNUMAN is an…
(more)
▼ The PhD research presented here is part of the new
nuclear manufacturing (NNUMAN) research group, looking into novel
materials and manufacturing processes. NNUMAN is an EPSRC funded
(EP/J021172/1) program with direct support from Rolls Royce plc.
The fabrication of MAX
phase coatings by different means and
assessing their tribological properties was the original theme of
this thesis. However, due to issues with fabrication processes the
overriding direction was moved towards assessing the response of
bulk MAX phases to irradiating and corrosive environments. It is
believed that this research will contribute to the understanding of
suitable compositions and applications within nuclear. The MAX
phases comprise an early transition metal (M), an A-group element
(A) and either carbon or nitrogen (X). They have an inherently
nano-layered structure with alternating ceramic (MX) and metallic
(A) layers. The unique mix of both ceramic and metallic properties
have made MAX phases a proposed material for nuclear applications.
Proton irradiation is performed on Ti3SiC2, Ti3AlC2, Ti2AlC and
Cr2AlC bulk MAX phases to 0.1 dpa at 350 °C. Crystallographic
instabilities are observed through x-ray diffraction (XRD) analysis
after irradiation. A mechanism for irradiation induced point defect
swelling is proposed, by matching XRD and modelling data. Anti-site
point defects are proposed to be a major contributor to anisotropic
lattice parameter changes in Ti3SiC2. Additional carbon
interstitial defects are also proposed in Ti3AlC2, as well as
anti-site defects, making them less radiation tolerant. Further
proton irradiations on Ti3SiC2 and Ti3AlC2 were performed at
elevated temperatures to propose a temperature at which lattice
changes are not observed. It is concluded that high proton fluences
require temperatures in excess of ~700 °C and ~1,000 °C for Ti3SiC2
and Ti3AlC2, respectively. Corrosion of bulk MAX phases in
simulated primary water also suggests a deleterious response to
normal light water reactor (LWR) operations. Advanced scanning
transmission electron microscopy (STEM) techniques, such as energy
dispersive x-ray spectroscopy (EDS) and electron energy loss
spectroscopy (EELS), is employed to understand corrosion
mechanisms. Selective oxidation of A-layers is observed, with no
evidence of passivation for Ti3SiC2, Ti3AlC2 and Ti2AlC. The
response of Cr2AlC was most promising as little oxidation occurred,
which is confirmed also with XRD analysis. A comprehensive
corrosion mechanism is proposed, whereby compositions of MAX
phase
in LWR coolants is limited.
Advisors/Committee Members: FRANKEL, PHILIPP PG, WITHERS, PHILIP PJ, Preuss, Michael, Frankel, Philipp, Withers, Philip.
Subjects/Keywords: MAX phase
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APA (6th Edition):
Ward, J. (2018). MAX phase ceramics for nuclear applications. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:314189
Chicago Manual of Style (16th Edition):
Ward, Joseph. “MAX phase ceramics for nuclear applications.” 2018. Doctoral Dissertation, University of Manchester. Accessed December 13, 2019.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:314189.
MLA Handbook (7th Edition):
Ward, Joseph. “MAX phase ceramics for nuclear applications.” 2018. Web. 13 Dec 2019.
Vancouver:
Ward J. MAX phase ceramics for nuclear applications. [Internet] [Doctoral dissertation]. University of Manchester; 2018. [cited 2019 Dec 13].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:314189.
Council of Science Editors:
Ward J. MAX phase ceramics for nuclear applications. [Doctoral Dissertation]. University of Manchester; 2018. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:314189
5.
Rice, James W.
Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures.
Degree: PhD, Fluids, Thermal, and Chemical Processing, 2011, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:11275/
► Polycyclic aromatic hydrocarbons (PAHs) are normally found in mixtures of many similarly structured compounds. The goal of the research presented in this thesis is to…
(more)
▼ Polycyclic aromatic hydrocarbons (PAHs) are normally
found in mixtures of many similarly structured compounds. The goal
of the research presented in this thesis is to better understand
PAH mixture thermodynamics by studying the
phase behavior of PAH
systems. The compounds examined are common PAHs and are also common
components of PAH mixtures, which have considerable environmental
and industrial significance.PAH mixtures have been studied using
differential scanning calorimetry, melting temperature analysis,
X-ray diffraction, and Knudsen effusion (for vapor pressure).
Furthermore, experiments were conducted to better characterize the
aqueous solubility of PAH mixtures and sorption behavior of pure
PAHs to soils.Thermochemical and vapor pressure experiments were
used to examine the
phase behavior of the anthracene + pyrene and
anthracene + benzo[a]pyrene systems. Solid-liquid
phase diagrams
were mapped for the mixtures. Eutectic points occur for both
mixture systems. Models based on eutectic
phase formation can be
used to predict the enthalpies of fusion associated with the
mixtures. Solid-vapor equilibrium, i.e., vapor pressure, studies
show that mixtures of anthracene and pyrene form solid azeotropes
and also suggest that the solid-vapor equilibrium of benzo[a]pyrene
is not significantly influenced by moderate levels of anthracene in
the crystal structure. A transition occurs from the non-ideal solid
mixtures (above) to a relatively ideal liquid behavior
characteristic of "tars". Ternary mixtures of anthracene, pyrene
and fluoranthene show behavior that is consistent with the binary
PAH mixtures; that is, the initially solid mixture exhibits a
significant melting point depression, relative to the pure
components, and in a certain range of composition, solid azeotrope
behavior on vaporization. As the number of distinct PAH species is
increased (by adding in benzo[a]pyrene, phenanthrene, fluorene and
chrysene) this behavior gradually leads to liquid
phase character
even at room temperature, and the vaporization behavior approaches
that crudely predictable from ideal mixture theory.
Advisors/Committee Members: Suuberg, Eric (Director), Calo, Joseph (Reader), Diebold, Gerald (Reader).
Subjects/Keywords: Phase equilibria
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APA (6th Edition):
Rice, J. W. (2011). Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:11275/
Chicago Manual of Style (16th Edition):
Rice, James W. “Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures.” 2011. Doctoral Dissertation, Brown University. Accessed December 13, 2019.
https://repository.library.brown.edu/studio/item/bdr:11275/.
MLA Handbook (7th Edition):
Rice, James W. “Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures.” 2011. Web. 13 Dec 2019.
Vancouver:
Rice JW. Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures. [Internet] [Doctoral dissertation]. Brown University; 2011. [cited 2019 Dec 13].
Available from: https://repository.library.brown.edu/studio/item/bdr:11275/.
Council of Science Editors:
Rice JW. Thermodynamics and Phase Behavior of Polycyclic Aromatic
Hydrocarbon Mixtures. [Doctoral Dissertation]. Brown University; 2011. Available from: https://repository.library.brown.edu/studio/item/bdr:11275/
University of North Texas
6.
Soni, Vishal.
Phase Transformations in Refractory High Entropy Alloys.
Degree: 2019, University of North Texas
URL: https://digital.library.unt.edu/ark:/67531/metadc1538735/
► High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits…
(more)
▼ High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits a microstructure similar to the γ-γ' in Ni-based superalloys. While these alloys exhibit impressive strengths at room temperature (RT) and at elevated temperatures, the continuous B2 matrix in these alloys is likely to be responsible for their brittle behavior at RT.
Phase stability of five such alloys are studied by thermo-mechanical treatments and characterization techniques using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two of these alloys showed an inverted microstructure, where the disordered BCC
phase becomes continuous, and therefore, they were characterized in detail using SEM, TEM, atom probe tomography (APT) and synchrotron x-ray diffraction experiments. The phenomenon of
phase inversion lead to a better combination of strength and ductility as compared to the non-inverted microstructure.To enhance the stability of B2 intermetallic
phase which provides the strength when present in a BCC matrix, multicomponent B2
phase compositions stable at 1000°C in some of the above studied alloys, were melted separately. The aim was to establish a single
phase B2 at 1000°C and understand the mechanical behavior of these single-
phase multicomponent B2 intermetallic alloys. These alloys exhibited a ductile behavior under compression and retained ~1 GPa yield strength at temperature up to 600°C. The ductile nature of these alloys is attributed to the change in bonding nature form directional to metallic bonding, possibly resulting from a significantly high configurational entropy compared to binary or ternary stoichiometric B2 compounds.
Advisors/Committee Members: Banerjee, Rajarshi, Srivilliputhur, Srinivasan G, Mishra, Rajiv S, Mukherjee, Sundeep, Scharf, Thomas, Fraser, Hamish.
Subjects/Keywords: phase; microscopy
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NSYSU
7.
Lin, Yi-Ting.
Studies of polymer stabilized blue phase liquid crystals phase grating.
Degree: PhD, Electro-Optical Engineering, 2013, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-161901
► ããThe advantages of liquid crystal (LC) diffraction gratings include their low cost and low-power electrical switchability. Liquid crystal is easily controlled by exploiting common electro-optical…
(more)
▼ ããThe advantages of liquid crystal (LC) diffraction gratings include their low cost and low-power electrical switchability. Liquid crystal is easily controlled by exploiting common electro-optical behaviors. To form a
phase grating profile, the LC must have a periodically varying refractive index. Previous works by the authors showed that, because of the intrinsic optical anisotropy of LCs, the optical properties of
these gratings are highly dependent on the polarization state of incident light. Some polarization-independent gratings use conventional orthogonally aligned nematic LC in one cell. However, even though the diffraction intensity is independent of light polarization, the diffraction beam polarization still depends on the angle between the polarization of the incident beam and the LC alignment.
ããBlue phases (BPs) have been in chiral liquid crystals between the cholesteric and isotropic phases The BP of a self-assembled three-dimensional cubic structure with lattice periods of several hundred nanometers exhibits not only selective Bragg reflections of light in the visible wavelength, but also optical isotropy owing to its highly symmetric molecular structure. A BPLC is optically isotropic when no voltage is
applied, and
phase-only modulation occurs when an electric field is applied parallel to the direction of propagated light. However, the use of in-plane switching (IPS) electrodes makes the grating polarization-dependent and retains background diffraction from the patterned electrode.
ããThis dissertation discusses the control of a polarization-independent and rapidly responding polymer-stabilized blue
phase liquid crystal (PSBP)
phase grating by exploiting the variation in the voltage-induced birefringence of the LC under a varying
phase. The electro-optical properties, including the voltage-dependent diffraction intensity, polarization-independence and response time, are also discussed.
ããFirstly, the hybrid PSBP liquid crystal
phase grating was studied. This grating consists of hybrid PSBPs with different Kerr constants that are determined by varied
phase separation conditions. When cured at a high temperature, a loose PSBP network is formed and a large Kerr effect is obtained. Accordingly, the electric-field-induced birefringence of PSBPI is lower than that of PSBPII at a given driving voltage. The
non-patterned electrode and optical isotropy of both PSBPI and PSBPII enable elimination of the diffraction effect when the voltage is off. The diffraction intensity increases with the applied voltage up to a maximum at 150V.
ããSecondly, a polarization-independent and rapidly responding dye-doped (DD) PSBP liquid crystal
phase grating was realized with two different
phase states. The non-patterned electrode and the optical isotropy of the PSBP completely eliminate the diffraction effect when the voltage is off. The diffraction intensity can be increased by applying a uniform electrical field, which induces a
phase difference in the DDPSBP. The diffraction efficiency exceeds 6%, which is 7-fold higher than…
Advisors/Committee Members: Chin-Ping Yu (chair), Wei Lee (chair), Kuang-Yao Lo (chair), Chi-Yen Huang (chair), Tsung-Hsien Lin (committee member), Andy Fuh (chair).
Subjects/Keywords: azobenzene; phase grating; blue phase; Liquid crystal
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APA ·
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MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lin, Y. (2013). Studies of polymer stabilized blue phase liquid crystals phase grating. (Doctoral Dissertation). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-161901
Chicago Manual of Style (16th Edition):
Lin, Yi-Ting. “Studies of polymer stabilized blue phase liquid crystals phase grating.” 2013. Doctoral Dissertation, NSYSU. Accessed December 13, 2019.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-161901.
MLA Handbook (7th Edition):
Lin, Yi-Ting. “Studies of polymer stabilized blue phase liquid crystals phase grating.” 2013. Web. 13 Dec 2019.
Vancouver:
Lin Y. Studies of polymer stabilized blue phase liquid crystals phase grating. [Internet] [Doctoral dissertation]. NSYSU; 2013. [cited 2019 Dec 13].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-161901.
Council of Science Editors:
Lin Y. Studies of polymer stabilized blue phase liquid crystals phase grating. [Doctoral Dissertation]. NSYSU; 2013. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-161901
University of Louisville
8.
Ray, Herman E.
Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints.
Degree: PhD, 2011, University of Louisville
URL: 10.18297/etd/1189
;
https://ir.library.louisville.edu/etd/1189
► The phase II clinical trial is a critical step in the drug development process. In the oncology setting, phase II studies typically evaluate one primary…
(more)
▼ The
phase II clinical trial is a critical step in the drug development process. In the oncology setting,
phase II studies typically evaluate one primary endpoint, which is efficacy. In practice, a binary measurement representing the response to the new treatment defines the efficacy. The single-arm, multiple-stage designs are popular and the Simon 2-Stage design is preferred. Although the study designs evaluate the efficacy, the
subject's safety is an important concern. Safety is monitored through the number of grade 3 or grade 4 toxic events. The
phase II clinical trial design based on the primary endpoint is typically augmented with an ad hoc monitoring rule. The studies are designed in two steps. First, the sample size and critical values are determined based on the primary endpoint. Then an ad hoc toxicity monitoring rule is applied to the study. Previous authors recommended a method to monitor toxic events after each patient is enrolled which is also known as continuous toxicity monitoring. A trial designed at the JG Brown Cancer Center combined the Simon 2-Stage design with continuous toxicity monitoring. We describe how to integrate the continuous toxicity monitoring methodology with the Simon 2-Stage design for response. Theoretical justification is given for the nominal size, power, probability of early termination (PET), and average sample size (ASN) of the combined testing procedure. A series of simulations were conducted to investigate the performance of the combined procedure. We discover that the type I error rate, type II error rate, PET, and ASN are
subject to the correlation between toxicity and response. In fact, the study may have a smaller type I error rate than expected. The theoretical expressions derived to describe the operating characteristics of the combined procedure were utilized to create a new flexible, bivariate, multistage clinical trial. The design is considered flexible because it can monitor toxicity on a different schedule than response. An example is considered in which toxicity is measured after four equally spaced intervals and the response is evaluated only at the second and fourth toxicity examinations. This example corresponds to a data monitoring committee's meeting schedule that may happen every 6 months over a two year span. The effect of the correlation on the type I and type II error rates is examined through simulation. The simulations also examine the power over the range of response rates with a fixed toxicity rate in the alternative region and vice-versa. There are several single-arm, multiple-stage clinical trial designs that consider multiple endpoints at the same time. A subset of the designs includes those that consider both efficacy and toxicity as binary endpoints. A common problem, considered after the conduct of the trial, is appropriate inference given the repeated examinations of the multiple endpoints. We propose a uniformly minimum variance unbiased estimator (UMVUE) for the response in a multistage clinical trial design incorporating toxicity effects.…
Advisors/Committee Members: Rai, Shesh Nath.
Subjects/Keywords: Clinical trial; Bivariate; Phase II; Phase III
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APA (6th Edition):
Ray, H. E. (2011). Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints. (Doctoral Dissertation). University of Louisville. Retrieved from 10.18297/etd/1189 ; https://ir.library.louisville.edu/etd/1189
Chicago Manual of Style (16th Edition):
Ray, Herman E. “Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints.” 2011. Doctoral Dissertation, University of Louisville. Accessed December 13, 2019.
10.18297/etd/1189 ; https://ir.library.louisville.edu/etd/1189.
MLA Handbook (7th Edition):
Ray, Herman E. “Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints.” 2011. Web. 13 Dec 2019.
Vancouver:
Ray HE. Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints. [Internet] [Doctoral dissertation]. University of Louisville; 2011. [cited 2019 Dec 13].
Available from: 10.18297/etd/1189 ; https://ir.library.louisville.edu/etd/1189.
Council of Science Editors:
Ray HE. Design and inference in phase II/III clinical trials incorporating monitoring of multiple endpoints. [Doctoral Dissertation]. University of Louisville; 2011. Available from: 10.18297/etd/1189 ; https://ir.library.louisville.edu/etd/1189
Oregon State University
9.
Elshazly, Amr.
Performance enhancement techniques for low power digital phase locked loops.
Degree: PhD, Electrical and Computer Engineering, 2012, Oregon State University
URL: http://hdl.handle.net/1957/31116
► Desire for low-power, high performance computing has been at core of the symbiotic union between digital circuits and CMOS scaling. While digital circuit performance improves…
(more)
▼ Desire for low-power, high performance computing has been at core of the symbiotic union between digital circuits and CMOS scaling. While digital circuit performance improves with device scaling, analog circuits have not gained these benefits. As a result, it has become necessary to leverage increased digital circuit performance to mitigate analog circuit deficiencies in nanometer scale CMOS in order to realize world class analog solutions.
In this thesis, both circuit and system enhancement techniques to improve performance of clock generators are discussed. The following techniques were developed: (1) A digital PLL that employs an adaptive and highly efficient way to cancel the effect of supply noise, (2) a supply regulated DPLL that uses low power regulator and improves supply noise rejection, (3) a digital multiplying DLL that obviates the need for high-resolution TDC while achieving sub-picosecond jitter and excellent supply noise immunity, and (4) a high resolution TDC based on a switched ring oscillator, are presented. Measured results obtained from the prototype chips are presented to illustrate the proposed design techniques.
Advisors/Committee Members: Hanumolu, Pavan Kumar (advisor), Temes, Gabor (committee member).
Subjects/Keywords: Phase locked loops; Phase-locked loops
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APA (6th Edition):
Elshazly, A. (2012). Performance enhancement techniques for low power digital phase locked loops. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/31116
Chicago Manual of Style (16th Edition):
Elshazly, Amr. “Performance enhancement techniques for low power digital phase locked loops.” 2012. Doctoral Dissertation, Oregon State University. Accessed December 13, 2019.
http://hdl.handle.net/1957/31116.
MLA Handbook (7th Edition):
Elshazly, Amr. “Performance enhancement techniques for low power digital phase locked loops.” 2012. Web. 13 Dec 2019.
Vancouver:
Elshazly A. Performance enhancement techniques for low power digital phase locked loops. [Internet] [Doctoral dissertation]. Oregon State University; 2012. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/1957/31116.
Council of Science Editors:
Elshazly A. Performance enhancement techniques for low power digital phase locked loops. [Doctoral Dissertation]. Oregon State University; 2012. Available from: http://hdl.handle.net/1957/31116
KTH
10.
Bhogireddy, Venkata Sai Pavan Kumar.
Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver.
Degree: Materials Science and Engineering, 2013, KTH
URL: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161712
► Duplex Stainless Steels (DSS) are used extensively in various industrial applications where the properties of both austenite and ferrite steels are required. Higher mechanical…
(more)
▼ Duplex Stainless Steels (DSS) are used extensively in various industrial applications where the properties of both austenite and ferrite steels are required. Higher mechanical strength and superior corrosion resistance are the advantages of DSS. One of the main drawbacks for Duplex steels is precipitation of sigma phase and other intermetallic phases adversely affecting the mechanical strength and the corrosion behavior of the steels. The precipitation of these secondary phases and the associated brittleness can be due to improper heat treatment. The instability in the microstructure of Duplex stainless steels can be studied by understanding the phase transformations especially the ones involving sigma phase. To reduce the time and effort to be put in for experimental work, computational simulations are used to get an initial understanding on the phase transformations. The present thesis work is on the phase transformations involving sigma phase for Fe-Cr system and Fe-Cr-Ni system using theoretical approach in 1D and 2D geometries. A phase field model is implemented for the microstructural evolution in DSS in combination with thermodynamic data collected from the Thermo-Calc software. The Wheeler Boettinger McFadden (WBM) model is used for Gibbs energy interpolation of the system. FiPy- Finite volume PDE solver written in python is used to simulate the phase transformation conditions first in Fe-Cr system for ferrite-austenite and ferrite-sigma phase transformations. It is then repeated for Fe-Cr-Ni ternary system. In the present study a model was developed for deriving Gibbs energy expression for sigma phase based on the common tangent condition. This model can be used to describe composition constrained phases and stoichiometric phases using the WBM model in phase field modeling. Cogswell’s theory of using phase order variable instead of an interpolating polynomial in the expression for Gibbs energy of whole system is also tried.
Subjects/Keywords: Phase field; Duplex Stainless steels; Sigma phase
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APA (6th Edition):
Bhogireddy, V. S. P. K. (2013). Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver. (Thesis). KTH. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161712
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Bhogireddy, Venkata Sai Pavan Kumar. “Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver.” 2013. Thesis, KTH. Accessed December 13, 2019.
http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161712.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bhogireddy, Venkata Sai Pavan Kumar. “Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver.” 2013. Web. 13 Dec 2019.
Vancouver:
Bhogireddy VSPK. Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver. [Internet] [Thesis]. KTH; 2013. [cited 2019 Dec 13].
Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161712.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bhogireddy VSPK. Phase Field modeling of sigma phase transformation in duplex stainless steels : Using FiPy-Finite Volume PDE solver. [Thesis]. KTH; 2013. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161712
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
11.
Gouraud, Fanny.
Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories.
Degree: Docteur es, Matériaux Céramiques et Traitement de Surface, 2016, Limoges
URL: http://www.theses.fr/2016LIMO0110
► Ces travaux de thèse, réalisés dans le cadre du programme de recherche ASZTech, portent sur l’étude de deux réfractaires électrofondus : un matériau Alumine-Zircone-Silice (AZS)…
(more)
▼ Ces travaux de thèse, réalisés dans le cadre du programme de recherche ASZTech, portent sur l’étude de deux réfractaires électrofondus : un matériau Alumine-Zircone-Silice (AZS) et un produit à Très Haute Teneur en Zircone (THTZ), destinés à l’industrie verrière. La zircone étant non stabilisée, ces réfractaires subissent donc, lors de l’étape de recuisson (refroidissement), la transformation quadratique (Q) à monoclinique (M) de la zircone qui, de par sa forte expansion volumique, est une source d’endommagement. L’objectif de cette étude a consisté à caractériser, au cours de traitements thermiques représentatifs, le comportement thermomécanique de ces matériaux et à établir des corrélations avec les évolutions microstructurales rencontrées. En étudiant leurs comportements sous sollicitations thermiques par des techniques acoustiques, l’impact de la transformation Q-M de la zircone sur le développement de l’endommagement a été mis en évidence. En s’intéressant particulièrement au comportement mécanique au passage de cette transformation, la présence d’un phénomène de plasticité de transformation (TRIP) a été confirmée. Outre le phénomène de TRIP qui participe à la relaxation des contraintes au passage de la transformation de phase, un phénomène d’endommagement diffus, offrant également une capacité d’accommodation, a été identifié pour le matériau THTZ. Au final, ces données ont permis d’améliorer le modèle de simulation numérique décrivant l’étape de recuisson de blocs industriels. En outre, la robustesse de ce modèle pourra maintenant être validée par confrontation à des mesures expérimentales de contraintes résiduelles réalisées au cours de cette étude.
This thesis, carried out under the research program ASZTech, focuses on the study of two fused cast refractories: an Alumina-Zirconia-Silica (AZS) product and a product with very High content of Zirconia (HZ), used in glass industry. These refractories containing non-stabilized zirconia are therefore subjected, during the annealing step (cooling), to the tetragonal (T) to the monoclinic (M) phase transition of zirconia associated with a very high volumetric expansion which is a source of stresses. This study aims at characterizing, during representative thermal treatments, the thermo-mechanical behavior of these materials, in correlation with the detected microstructural evolutions. Thanks to the analysis of their behavior under thermal stresses by acoustic techniques, the effect of the T-M transition of zirconia on the development of damage has been highlighted. In particular, the occurrence of a TRansformation Induced Plasticity (TRIP) phenomenon during the zirconia phase transition has been identified and characterized thanks to cooling tests under mechanical stress. In addition to this TRIP phenomenon which allows to relax the mechanical stresses induced during the phase transition, a diffuse damage phenomenon has been also identified for HZ product. Eventually, these data have led to an improvement of the numerical model which simulates the annealing step…
Advisors/Committee Members: Chotard, Thierry (thesis director), Huger, Marc (thesis director), Antou, Guy (thesis director).
Subjects/Keywords: Transformations de phase; Phase transitions; 620.189 35
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Manager
APA (6th Edition):
Gouraud, F. (2016). Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories. (Doctoral Dissertation). Limoges. Retrieved from http://www.theses.fr/2016LIMO0110
Chicago Manual of Style (16th Edition):
Gouraud, Fanny. “Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories.” 2016. Doctoral Dissertation, Limoges. Accessed December 13, 2019.
http://www.theses.fr/2016LIMO0110.
MLA Handbook (7th Edition):
Gouraud, Fanny. “Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories.” 2016. Web. 13 Dec 2019.
Vancouver:
Gouraud F. Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories. [Internet] [Doctoral dissertation]. Limoges; 2016. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2016LIMO0110.
Council of Science Editors:
Gouraud F. Influence des transformations de phase de la zircone sur le comportement thermomécanique de réfractaires à très haute teneur en zircone : Influence of zirconia phase transitions on the thermo-mechanical behavior of high zirconia refractories. [Doctoral Dissertation]. Limoges; 2016. Available from: http://www.theses.fr/2016LIMO0110
North Carolina State University
12.
Cassidy, Daniel Anthony.
Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications.
Degree: PhD, Mechanical Engineering, 2009, North Carolina State University
URL: http://www.lib.ncsu.edu/resolver/1840.16/5199
► The present study is both a numerical and experimental investigation into the two phase flow of a microPCM fluid in a circular tube with mixed…
(more)
▼ The present study is both a numerical and experimental investigation into the two
phase flow of a microPCM fluid in a circular tube with mixed convection. The PCM was octacosane encapsulated by a polyethylene shell to form a spherical particle with an average diameter of 20 microns. The microPCM particles were suspended in a 50 / 50 ethylene glycol water mixture. The flow was through a 0.00775 m diameter copper tube with a length of approximately 0.75m. A constant wall heat flux was supplied by an electric resistance wire. The flow was gravity fed with a pumped circulation to maintain a constant pressure head. Experimental measurements were made of the tube outer wall at the top and bottom of the copper tube. Numerically an incompressible flow model was used with an Eulerian - Eulerian method to solve the two
phase momentum and energy equations. The numerical model was verified using experimental data of single
phase flow with mixed convection available in literature and was also verified by thermal results of both single
phase and two
phase flow from the experimental work in the current investigation.
Through the numerical investigation of the experimental conditions it was found that when the slurry was not cooled to a temperature far enough below the inlet temperature a supercooling effect did not allow a full use of the latent heat available in the octacosane microPCM, only about 50% of the total latent heat was used in one case. Further numerical investigations included tube wall material in which stainless steel was compared to the copper tubing used in the experiment. The inclusion of the solid
phase buoyancy term was found to affect the thermal solution. A comparison was also made of microPCM flow rates in which the Reynolds number, the mass flow rate, and the pump power were each held constant and the solutions compared. It was then recommended that a constant pump power be used as a basis for comparison. A parametric study was also completed in which the Rayleigh number and the Stefan number were both varied to find the effects on the thermal and hydrodynamic solution.
Advisors/Committee Members: Dr. Richard D. Gould, Committee Chair (advisor), Dr. Kevin M. Lyons, Committee Member (advisor), Dr. Andrey V. Kuznetsov, Committee Member (advisor), Dr. James W. Leach, Committee Member (advisor).
Subjects/Keywords: phase change material; two phase flow; octacosane
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Export
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Manager
APA (6th Edition):
Cassidy, D. A. (2009). Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications. (Doctoral Dissertation). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/5199
Chicago Manual of Style (16th Edition):
Cassidy, Daniel Anthony. “Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications.” 2009. Doctoral Dissertation, North Carolina State University. Accessed December 13, 2019.
http://www.lib.ncsu.edu/resolver/1840.16/5199.
MLA Handbook (7th Edition):
Cassidy, Daniel Anthony. “Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications.” 2009. Web. 13 Dec 2019.
Vancouver:
Cassidy DA. Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications. [Internet] [Doctoral dissertation]. North Carolina State University; 2009. [cited 2019 Dec 13].
Available from: http://www.lib.ncsu.edu/resolver/1840.16/5199.
Council of Science Editors:
Cassidy DA. Numerical and Experimental Investigations of Mixed Convection in Solid-Liquid Flow for MicroPCM Applications. [Doctoral Dissertation]. North Carolina State University; 2009. Available from: http://www.lib.ncsu.edu/resolver/1840.16/5199
University of North Texas
13.
Devaraj, Arun.
Phase Separation and Second Phase Precipitation in Beta Titanium Alloys.
Degree: 2011, University of North Texas
URL: https://digital.library.unt.edu/ark:/67531/metadc67975/
► The current understanding of the atomic scale phenomenon associated with the influence of beta phase instabilities on the evolution of microstructure in titanium alloys is…
(more)
▼ The current understanding of the atomic scale phenomenon associated with the influence of beta
phase instabilities on the evolution of microstructure in titanium alloys is limited due to their complex nature. Such beta
phase instabilities include
phase separation and precipitation of nano-scale omega and alpha phases in the beta matrix. The initial part of the present study focuses on omega precipitation within the beta matrix of model binary titanium molybdenum (Ti-Mo) alloys. Direct atomic scale observation of pre-transition omega-like embryos in quenched alloys, using aberration-corrected high resolution scanning transmission electron microscopy and atom probe tomography (APT) was compared and contrasted with the results of first principles computations performed using the Vienna ab initio simulation package (VASP) to present a novel mechanism of these special class of
phase transformation. Thereafter the beta
phase separation and subsequent alpha
phase nucleation in a Ti-Mo-Al ternary alloy was investigated by coupling in-situ high energy synchrotron x-ray diffraction with ex-situ characterization studies performed using aberration corrected transmission electron microscopy and APT to develop a deeper understanding of the mechanism of transformation. Subsequently the formation of the omega
phase in the presence of simultaneous development of compositional
phase separation within the beta matrix
phase of a Ti-10V-6Cu (wt%) alloy during continuous cooling has been investigated using a combination of transmission electron microscopy and atom probe tomography. The results of these investigations provided novel insights into the mechanisms of solid-state transformations in metallic systems by capturing the earliest stages of nucleation at atomic to near atomic spatial and compositional resolution.
Advisors/Committee Members: Banerjee, Rajarshi, Srivilliputhur, Srinivasan, Needleman, Alan, Nag, SoumyA, Fraser, Hamish.
Subjects/Keywords: Titanium alloys; phase transformation; phase separation
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Texas A&M University
14.
Firat, Volkan H.
Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals.
Degree: 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155521
► Clouds are still one of the largest uncertainties of the current climate models. While satellites provide suitable global datasets for comparing with cloud properties derived…
(more)
▼ Clouds are still one of the largest uncertainties of the current climate models. While satellites provide suitable global datasets for comparing with cloud properties derived from models, satellite retrievals are inferences of cloud properties, rather than direct measurements, and therefore have errors. Therefore, it is important to evaluate satellite cloud products and gain advanced understanding of the products to accurately interpret the observations.
This study investigates Aqua AIRS version 6 Level 2 cloud thermodynamic
phase, ice cloud optical thickness, and ice cloud effective diameter, which released in April, 2013 and are available for all 13 years of the AIRS record. A filtering and gridding algorithm is used to create customized globally gridded datasets to evaluate the effects of satellite's viewing zenith angle, effective cloud fraction, cloud layers, cloud top temperature, time of the year, and geographic region.
Viewing zenith angle does not strongly affect AIRS ice-
phase, but higher viewing zenith angles lead to more water and fewer unknown pixels; the viewing zenith angle dependence is not strongly affected by the time of the year. Higher effective cloud fraction yields more ice- and water-
phase, and less unknown-
phase retrievals. Also, higher effective cloud fractions lead to greater values of ice cloud optical thickness. In addition, especially in high latitudes, ice-
phase frequency is greater for two-layer clouds than single-layer clouds. On the other hand, water- and unknown-
phase frequencies are greater for single layer clouds. Also, higher viewing zenith angles slightly decrease upper cloud top temperature. Approximately 90% of ice-
phase cases have upper cloud top temperature values between 210 K and 235 K, ~80% of water-
phase cases are found at 243-273 K upper cloud top temperature interval, and ~80% of the unknown cases have upper cloud top temperature values between 230 and 264 K. For ice cloud optical thickness and ice cloud effective diameter, no strong effects of satellite viewing zenith angle or cloud layering are observed.
Advisors/Committee Members: Nasiri, Shaima L (advisor), North, Gerald R (committee member), Filippi, Anthony M (committee member).
Subjects/Keywords: AIRS; clouds; phase
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Manager
APA (6th Edition):
Firat, V. H. (2015). Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155521
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Firat, Volkan H. “Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals.” 2015. Thesis, Texas A&M University. Accessed December 13, 2019.
http://hdl.handle.net/1969.1/155521.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Firat, Volkan H. “Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals.” 2015. Web. 13 Dec 2019.
Vancouver:
Firat VH. Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals. [Internet] [Thesis]. Texas A&M University; 2015. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/1969.1/155521.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Firat VH. Evaluation and Improvement of Atmospheric Infrared Sounder (AIRS) Ice Cloud Retrievals. [Thesis]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155521
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Oregon State University
15.
Arakali, Abhijith.
Low-power techniques for supply-noise mitigation in phase-locked
loops.
Degree: PhD, Electrical and Computer Engineering, 2010, Oregon State University
URL: http://hdl.handle.net/1957/14281
► Modern day digital systems employ frequency synthesizers to provide a common clock to the system. They are undergoing large scale integration due to which, mitigation…
(more)
▼ Modern day digital systems employ frequency
synthesizers to provide a common clock to the system.
They are undergoing large scale integration due to which, mitigation
of the effect of noise on power supply has become a major design consideration
in clocking circuits. Rapid scaling of CMOS technology mandates the
design of frequency synthesizers in a low supply voltage environment.
Maintaining the supply noise immunity of clocking circuits in low-voltage
processes is particularly challenging.
In this thesis, techniques to mitigate the effect of supply-noise
in frequency synthesizers are
explored. The ring-oscillator based frequency synthesizer
is an important part of many clocking circuits.
They are used in various digital communication systems and as a
building block in high speed signalling systems.
They suffer from high sensitivity to power supply noise thereby requiring
careful design considerations to improve its supply noise immunity.
In light of the above, an attempt has been made to
improve the immunity of the ring-oscillator based frequency synthesizer
to noise on the supply voltage. The effect of noise on
the supplies of other building blocks of a frequency synthesizer,
though not as pronounced as that of noise on the ring-oscillator supply,
is quite significant. Analysis of effect of power supply noise on
various building blocks of the frequency synthesizer are presented.
Also, techniques to effectively reduce the effect of power supply noise
on the performance of the frequency synthesizer are presented.
Measured results from proof-of-concept ICs are presented to illustrate the
effectiveness of the proposed techniques.
Clock and data recovery (CDR) circuits which utilize ring-oscillators are
also highly sensitive to power supply noise. Measurement of CDR jitter
tolerance without the use of expensive equipment is another challenge involved
in the design of CDRs. An on-chip jitter tolerance measurement technique is
presented wherein, a
phase averaging dual loop CDR architecture is used
which comprises of a
phase-locked loop (PLL) inside the CDR loop.
Previously proposed idea of using oversampling in this architecture has proven
to considerably
reduce power consumption in this CDR architecture. In this thesis, an
attempt has been made to further reduce the power consumption.
The PLL in this CDR architecture utilizes the proposed supply regulated PLL
architecture in order to minimize the bit-error rate (BER) of the CDR due to
power supply noise.
Advisors/Committee Members: Hanumolu, Pavan Kumar (advisor), Mayaram, Kartikeya (committee member).
Subjects/Keywords: Phase-locked loops
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APA (6th Edition):
Arakali, A. (2010). Low-power techniques for supply-noise mitigation in phase-locked
loops. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/14281
Chicago Manual of Style (16th Edition):
Arakali, Abhijith. “Low-power techniques for supply-noise mitigation in phase-locked
loops.” 2010. Doctoral Dissertation, Oregon State University. Accessed December 13, 2019.
http://hdl.handle.net/1957/14281.
MLA Handbook (7th Edition):
Arakali, Abhijith. “Low-power techniques for supply-noise mitigation in phase-locked
loops.” 2010. Web. 13 Dec 2019.
Vancouver:
Arakali A. Low-power techniques for supply-noise mitigation in phase-locked
loops. [Internet] [Doctoral dissertation]. Oregon State University; 2010. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/1957/14281.
Council of Science Editors:
Arakali A. Low-power techniques for supply-noise mitigation in phase-locked
loops. [Doctoral Dissertation]. Oregon State University; 2010. Available from: http://hdl.handle.net/1957/14281
Oregon State University
16.
Black, Corrie D.
The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography.
Degree: MS, Radiation Health Physics, 2011, Oregon State University
URL: http://hdl.handle.net/1957/21872
► An alternative extractant for the TRUEX/UNEX process was investigated in solid phase extraction chromatography. The para and ortho isomers of diamides derivatives of dipicolinic acid…
(more)
▼ An alternative extractant for the TRUEX/UNEX process was investigated in solid
phase extraction chromatography. The para and ortho isomers of diamides derivatives of dipicolinic acid (N,N'-diethyl-N,N'-ditolyl-dipicolinamide, EtTDPA) have been found in the past to effectively separate actinides from lanthanides in solvent extraction and were successfully impregnated on two uncoated, inert macroporous polymeric support resin types. The ortho resins consistently yielded higher extractions while the para resin consistently yielded higher Am/Eu separations. These findings were consistent with past solvent extraction experiments and suggest the versatility of these extractants in a variety of applications. The use of complexing agents were also considered both in the eluent and on the resin and found to change the extraction properties of the resin enough to warrant further investigation.
Advisors/Committee Members: Paulenova, Alena (advisor), Mincher, Bruce (committee member).
Subjects/Keywords: Solid Phase Extraction
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APA (6th Edition):
Black, C. D. (2011). The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/21872
Chicago Manual of Style (16th Edition):
Black, Corrie D. “The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography.” 2011. Masters Thesis, Oregon State University. Accessed December 13, 2019.
http://hdl.handle.net/1957/21872.
MLA Handbook (7th Edition):
Black, Corrie D. “The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography.” 2011. Web. 13 Dec 2019.
Vancouver:
Black CD. The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography. [Internet] [Masters thesis]. Oregon State University; 2011. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/1957/21872.
Council of Science Editors:
Black CD. The investigation of dipicolinic acid diamide derivatives for the separation of actinides and lanthanides using solid phase extraction chromatography. [Masters Thesis]. Oregon State University; 2011. Available from: http://hdl.handle.net/1957/21872
Baylor University
17.
[No author].
The observation of phase state and temperature using noninvasive ultrasonic waves.
Degree: 2017, Baylor University
URL: http://hdl.handle.net/2104/10042
► There are many ways to obtain temperature measurements and observe phase changes, but most rely on physical contact or a line-of-sight path with the material.…
(more)
▼ There are many ways to obtain temperature measurements and observe
phase changes, but most rely on physical contact or a line-of-sight path with the material. Many industries ranging from oil and gas to food and beverage could expand their application space in select scenarios if a noninvasive means were available to identify the internal temperature state of a material within a confined vessel. This thesis investigates the hypothesis that the use of ultrasonic signals and the resulting time of flight and intensity of the high-frequency sound wave may be used to identify a material undergoing a
phase change within a confined vessel. A wax melting experiment within a confined chamber has been designed to test this hypothesis. The results presented within this work demonstrate the viability of the method and the results for the speed of sound of a material as a function of temperature are highly repeatable and indicate a clear one-to-one ratio between the speed of sound and the temperature state.
Advisors/Committee Members: Jack, David Abram, 1977- (advisor).
Subjects/Keywords: Ultrasound. Phase change.
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APA (6th Edition):
author], [. (2017). The observation of phase state and temperature using noninvasive ultrasonic waves.
(Thesis). Baylor University. Retrieved from http://hdl.handle.net/2104/10042
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
author], [No. “The observation of phase state and temperature using noninvasive ultrasonic waves.
” 2017. Thesis, Baylor University. Accessed December 13, 2019.
http://hdl.handle.net/2104/10042.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
author], [No. “The observation of phase state and temperature using noninvasive ultrasonic waves.
” 2017. Web. 13 Dec 2019.
Vancouver:
author] [. The observation of phase state and temperature using noninvasive ultrasonic waves.
[Internet] [Thesis]. Baylor University; 2017. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/2104/10042.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
author] [. The observation of phase state and temperature using noninvasive ultrasonic waves.
[Thesis]. Baylor University; 2017. Available from: http://hdl.handle.net/2104/10042
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
18.
Peters, Phillip.
Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains.
Degree: Docteur es, Optique et Lasers, Physico-chimie, Atmosphère, 2012, Université Lille I – Sciences et Technologies
URL: http://www.theses.fr/2012LIL10125
► L'objectif de ce travail est de caractériser par des méthodes de chimie quantique de haute qualité les processus réactionnels impliquant H, CO, H2CO, H3COH et…
(more)
▼ L'objectif de ce travail est de caractériser par des méthodes de chimie quantique de haute qualité les processus réactionnels impliquant H, CO, H2CO, H3COH et H2O à la surface des grains interstellaires. En effet, H2CO et H3COH sont parmi les molécules organiques les plus abondantes dans les nuages moléculaires interstellaires. Il s’agit de la première étude décrivant les étapes conduisant au méthanol par hydrogénations successives de CO. En phase gazeuse, les méthodes multi-références ont été employées. Les calculs montrent que certaines étapes cruciales de la synthèse (formation de HCO) mettent en jeu des barrières d'activation significatives dans les conditions interstellaires. L’effet tunnel a aussi été pris en compte. Les mêmes réactions ont ensuite été étudiées sur des agrégats d'eau ou de CO. Ceux-ci ont été choisis comme surfaces modèles pour les grains interstellaires. Compte-tenu de la taille du système, les calculs ont été menés en utilisant la théorie DFT et la méthode MP2. Pour la formation de HCO, la présence d'un agrégat ne modifie pas l'énergie d'activation. En revanche, pour la formation de COH et H3CO, l'énergie d'activation est réduite et l'endo/exothermicité change. L'isomérisation HCOH-H2CO devient possible dans des agrégats d'eau. Ces résultats indiquent que l'état de surface et le flux d'atomes H peuvent avoir une influence notable, ouvrant d'autres voies non envisageables en phase gazeuse. Enfin, ces résultats seront intégrés dans le modèle astrophysique GRAINOBLE, ce qui permettra de tenir compte des différents intermédiaires qui pourraient potentiellement participer à la synthèse de ces deux molécules ainsi que d’autres plus complexes.
Throughout this work high level quantum chemistry methods have been used to investigate reactive processes involving: H, D, CO, H2CO, H3COH and H2O at model interstellar grains surfaces. This study has mainly focused upon the formation of the two most abundant Complex Organic Molecules (COMS), H2CO and H3COH. For the first time, all of the hydrogenation steps have been considered and treated with reliable methods in the gas phase, and in particular making use of multi-reference approaches such as MRCI+Q and MRMP2. Following the characterization of all the reactions in the gas phase, the same processes have been investigated within small molecular clusters using various density functionals and MP2. This was done as a preliminary attempt to model the icy grain mantles of interstellar dust grains. For some of the steps, such as the formation of HCO, the activation energy does not vary significantly between the gas phase and the clusters. In contrast, for other processes, such as the formation of COH, and H3CO, the activation energy is lowered and the exothermicity/endothermicity of the reaction changes. In addition, the isomerizations of some species, as for instance HCOH to H2CO, are also strongly affected by the presence of water. From the cluster calculations, we conclude that the arrangement of the surface molecules and the H flux may have a significant…
Advisors/Committee Members: Duflot, Denis (thesis director), Wiesenfeld, Laurent (thesis director), Toubin, Céline (thesis director).
Subjects/Keywords: Phase gazeuse; 523.02
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APA (6th Edition):
Peters, P. (2012). Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains. (Doctoral Dissertation). Université Lille I – Sciences et Technologies. Retrieved from http://www.theses.fr/2012LIL10125
Chicago Manual of Style (16th Edition):
Peters, Phillip. “Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains.” 2012. Doctoral Dissertation, Université Lille I – Sciences et Technologies. Accessed December 13, 2019.
http://www.theses.fr/2012LIL10125.
MLA Handbook (7th Edition):
Peters, Phillip. “Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains.” 2012. Web. 13 Dec 2019.
Vancouver:
Peters P. Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains. [Internet] [Doctoral dissertation]. Université Lille I – Sciences et Technologies; 2012. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2012LIL10125.
Council of Science Editors:
Peters P. Etude théorique de la réactivité de l’hydrogène avec CO, H2CO, H3COH à la surface des grains interstellaires : A Theoretical study of the reaction of hydrogen with CO, H2CO, CH3OH on the surfaces of interstellar dust grains. [Doctoral Dissertation]. Université Lille I – Sciences et Technologies; 2012. Available from: http://www.theses.fr/2012LIL10125
19.
Stephan, Baptiste.
Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content.
Degree: Docteur es, Physique et Science des Matériaux, 2018, Université Lille I – Sciences et Technologies
URL: http://www.theses.fr/2018LIL1R004
► La mise en ordre (MEO) chimique des alliages Ni-Cr modifie leurs propriétés mécaniques et est une préoccupation potentielle pour leur utilisation dans les réacteurs à…
(more)
▼ La mise en ordre (MEO) chimique des alliages Ni-Cr modifie leurs propriétés mécaniques et est une préoccupation potentielle pour leur utilisation dans les réacteurs à eau sous pression. Dans ces travaux, la caractérisation de la cinétique de MEO par des vieillissements accélérés a été effectuée sur des alliages modèles à faible teneur en fer. L’apparition de la phase ordonnée Ni2Cr se traduit par une augmentation de la dureté. De plus, la mesure du pouvoir thermoélectrique s’est révélée très sensible à l’apparition de la MEO. Le rôle de la teneur en fer dans la cinétique du phénomène est négligeable à basse température (<450 °C), contrairement aux traitements thermiques pratiqués sur les alliages. Nous avons extrapolé nos résultats au cas des alliages industriels où la teneur en fer est plus élevée : le temps d’incubation de la MEO est estimé à 140 ans à 325 °C. La taille nanométrique des domaines ordonnés et leur faible différence de composition avec la matrice désordonnée rendent leur étude délicate. Nous avons utilisé des méthodes avancées de microscopie électronique en transmission pour progresser dans leur description. Grâce au couplage de l’analyse d’images et de cartographies d’orientation, la proportion surfacique des domaines ordonnés a pu être estimée sur un échantillon témoin. Des cartographies chimiques en perte d’énergie révèlent que le fer est en partie ségrégé autour des domaines ordonnés. Ceci remet en cause l’état d’ordre de la phase Ni2Cr, ce qui a été corroboré par des études quantitatives en microdiffraction sur des domaines ordonnés. A l’échelle atomique, les analyses montrent que le fer se substitue de préférence au chrome dans la maille ordonnée.
Chemical ordering in Ni-Cr alloys modifies their mechanical properties and is a potential issue for their use in pressurized water reactors. In this work, ordering kinetics have been determined by accelerated ageing on model alloys with low iron content. The Ni2Cr ordered phase appearance induces a hardness increase. Furthermore, thermoelectric power measurements have been revealed very sensitive to ordering. The iron content does not affect ordering kinetics at low temperatures (<450 °C), contrary to thermal treatments practiced on the alloys. Our results have been extrapolated to the industrial case, where the iron content is higher: ordering incubation time is estimated at 140 years at 325 °C. The nanometric size of ordered domains together with their small difference in chemical composition with the disordered matrix make their study difficult. We used advance characterizations with transmission electron microscopy to progress in their description. Thanks to the coupling of image analysis with orientation mappings, the surface proportion of ordered domains has been estimated on a control sample. Energy loss chemical maps reveal that the iron is partly segregated around ordered domains. This questions the state of order of the Ni2Cr phase, which is corroborated by quantitative microdiffractions achieved on ordered domains. At the atomic scale,…
Advisors/Committee Members: Jacob, Damien (thesis director), Delabrouille, Frédéric (thesis director).
Subjects/Keywords: Phase Ni2Cr; 669.94
Record Details
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Stephan, B. (2018). Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content. (Doctoral Dissertation). Université Lille I – Sciences et Technologies. Retrieved from http://www.theses.fr/2018LIL1R004
Chicago Manual of Style (16th Edition):
Stephan, Baptiste. “Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content.” 2018. Doctoral Dissertation, Université Lille I – Sciences et Technologies. Accessed December 13, 2019.
http://www.theses.fr/2018LIL1R004.
MLA Handbook (7th Edition):
Stephan, Baptiste. “Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content.” 2018. Web. 13 Dec 2019.
Vancouver:
Stephan B. Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content. [Internet] [Doctoral dissertation]. Université Lille I – Sciences et Technologies; 2018. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2018LIL1R004.
Council of Science Editors:
Stephan B. Etude cinétique et microstructurale de la transformation ordre-désordre dans les alliages Ni2Cr à faible teneur en fer : A kinetic and microstructural study of order-disorder transformation in Ni2Cr alloys with low iron content. [Doctoral Dissertation]. Université Lille I – Sciences et Technologies; 2018. Available from: http://www.theses.fr/2018LIL1R004
University of Houston
20.
Li, Zhuoran.
Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates.
Degree: Petroleum Engineering, Department of, 2018, University of Houston
URL: http://hdl.handle.net/10657/3490
► As one of the most important ways to reduce the greenhouse gas emission, Carbon dioxide sequestration coupled with hydrocarbon resource recovery is often economically attractive.…
(more)
▼ As one of the most important ways to reduce the greenhouse gas emission, Carbon dioxide sequestration coupled with hydrocarbon resource recovery is often economically attractive. Applying CO2 to exchange CH4 in the hydrate
phase represents a growing concern in hydrate exploitation field. In order to characterize multiphase behavior in containing hydrate system, this paper constructed a multiphase flash model in presence of hydrates. The stability analysis and reformulated Richford-Rice equation solving algorithm are based on the minimization of the Gibbs free energy. The Soave–Redlich–Kwong (SRK) equation of state combined with Huron–Vidal mixing rules was applied in this model to give satisfactory prediction for polar systems. A good agreement between 61 experimental measurements and prediction values is observed, proving the reliability of this model.
Advisors/Committee Members: Qin, Guan (advisor), Lee, KyungJae (committee member), Soliman, Mohamed (committee member).
Subjects/Keywords: phase equilibrium; hydrates
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APA (6th Edition):
Li, Z. (2018). Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates. (Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/3490
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Li, Zhuoran. “Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates.” 2018. Thesis, University of Houston. Accessed December 13, 2019.
http://hdl.handle.net/10657/3490.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Li, Zhuoran. “Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates.” 2018. Web. 13 Dec 2019.
Vancouver:
Li Z. Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates. [Internet] [Thesis]. University of Houston; 2018. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/10657/3490.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Li Z. Multiphase Equilibrium Characterization and Compositional Analysis in Presence of Hydrates. [Thesis]. University of Houston; 2018. Available from: http://hdl.handle.net/10657/3490
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
21.
Meziane, Rachid.
Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system.
Degree: Docteur es, Instrumentation et analyses avancées, 2008, Université Lille I – Sciences et Technologies
URL: http://www.theses.fr/2008LIL10141
► Le discernement du comportement du cristal liquide au sein d'une matrice rigide est d'une grande importance afin de rendre plus performant les composites de ce…
(more)
▼ Le discernement du comportement du cristal liquide au sein d'une matrice rigide est d'une grande importance afin de rendre plus performant les composites de ce type qui peuvent être intéressant pour leurs nombreuses applications notamment dans les vitrages électroactifs et les dispositifs d'affichages. La compréhension de sa réponse à un signal électrique ou à un effet thermique est primordiale. Le volume, dans lequel le cristal liquide se situe, contribue fortement à la qualité de cette réaction. Ce travail est une étude portant sur l'évolution structural de l'ensemble 4-cyano-4'-n-octyl-biphényl (8CB)/polystyrène depuis la phase homogène jusqu'à la phase cristalline du 8CB. L'analyse morphologique établit qu'une formation des objets selon le modèle d'Ostwald-Ripening soit à l'origine de la morphologie, on note également une forte dépendance de la concentration en mésogènes sur la dimension des domaines ségrégués. Ainsi, l'étude menée par calorimétrie indique que les plus petits domaines observés ont une taille suffisante pour engendrer des phases métastables du 8CB. On montre par spectroscopie infrarouge que les molécules de mésogène ne forment pas de liaisons p aromatiques avec le groupement phényle du polystyrène, cependant différents groupements chimiques des deux constituants sont en interaction. L'ordre smectique du cristal liquide est étudié par diffusion de neutrons aux petits angles. La structure smectique subit des déformations élastiques différentes selon les dimensions de confinements. En dernier lieu, nous discutons de l'influence du cristal liquide dans la polymérisation radicalaire. La cinétique de polymérisation est fortement perturbée dans des conditions riches en mésogène soulignant le caractère important du comportement du radical sur la polydispersité finale du polymère.
The understanding of the behavior of a low molecular weight liquid crystal within a rigid matrix is of great importance in order to make powerful composite materials of this type which can be interesting for many applications in particular in the display devices. The understanding of their response to an electric signal or a heating effect is of primary importance. The volume, in which the liquid crystal is located, strongly contributes to these effects. This work is a study relating to the structural evolution of the 4-cyano-4'-n-octyl-biphenyl (8CB)/polystyrene system from the homogeneous phase to the crystal line phase of the 8CB. The morphological analysis reveals that a formation of the objects according to the model of Ostwald-Ripening is at the origin of morphology, one also notes a strong dependence of the mesogene concentration on the segregated size domains. Thus, the study undertaken by calorimetry indicates that the smallest domains observed have a sufficient size to generate metastable phases of the 8CB. One shows by infra-red spectroscopy that the molecules of mesogene do not form aromatic p connections with the phenyl group of polystyrene, however various chemical groups of the two components are in interaction.…
Advisors/Committee Members: Maschke, Ulrich (thesis director).
Subjects/Keywords: Phase smectique; Polydispersité
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APA ·
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to Zotero / EndNote / Reference
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APA (6th Edition):
Meziane, R. (2008). Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system. (Doctoral Dissertation). Université Lille I – Sciences et Technologies. Retrieved from http://www.theses.fr/2008LIL10141
Chicago Manual of Style (16th Edition):
Meziane, Rachid. “Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system.” 2008. Doctoral Dissertation, Université Lille I – Sciences et Technologies. Accessed December 13, 2019.
http://www.theses.fr/2008LIL10141.
MLA Handbook (7th Edition):
Meziane, Rachid. “Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system.” 2008. Web. 13 Dec 2019.
Vancouver:
Meziane R. Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system. [Internet] [Doctoral dissertation]. Université Lille I – Sciences et Technologies; 2008. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2008LIL10141.
Council of Science Editors:
Meziane R. Structure, dynamique et transition de phases d'un cristal liquide smectique en milieu polymère : Structure, dynamique and phases transition of a smectic liquid crystal in polymer system. [Doctoral Dissertation]. Université Lille I – Sciences et Technologies; 2008. Available from: http://www.theses.fr/2008LIL10141
University of Debrecen
22.
Lukács, Béla.
Evaluation of my Final Teaching
.
Degree: DE – TEK – Bölcsészettudományi Kar, 2014, University of Debrecen
URL: http://hdl.handle.net/2437/178026
My thesis is on a rather special subject: my final teaching. By nature, it is a very personal topic, and the thesis written on it shows my pedagogical headway as an English teacher trainee.
Advisors/Committee Members: Gulyás, Anita (advisor).Subjects/Keywords: lesson plan;
phase
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APA ·
Chicago ·
MLA ·
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APA (6th Edition):
Lukács, B. (2014). Evaluation of my Final Teaching
. (Thesis). University of Debrecen. Retrieved from http://hdl.handle.net/2437/178026
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lukács, Béla. “Evaluation of my Final Teaching
.” 2014. Thesis, University of Debrecen. Accessed December 13, 2019.
http://hdl.handle.net/2437/178026.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lukács, Béla. “Evaluation of my Final Teaching
.” 2014. Web. 13 Dec 2019.
Vancouver:
Lukács B. Evaluation of my Final Teaching
. [Internet] [Thesis]. University of Debrecen; 2014. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/2437/178026.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lukács B. Evaluation of my Final Teaching
. [Thesis]. University of Debrecen; 2014. Available from: http://hdl.handle.net/2437/178026
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
23.
Viardin, Alexandre.
Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels.
Degree: Docteur es, Science et ingénierie des matériaux et métallurgie, 2010, Lorraine INP
URL: http://www.theses.fr/2010INPL014N
► La ferrite allotriomorphe est une des morphologies de la ferrite dont la répartition spatiale influe fortement sur les propriétés mécaniques dans les aciers dual-phase. En…
(more)
▼ La ferrite allotriomorphe est une des morphologies de la ferrite dont la répartition spatiale influe fortement sur les propriétés mécaniques dans les aciers dual-phase. En fonction des traitements qu'ils subissent, la ferrite peut s'y répartir suivant les bandes de ségrégation en manganèse, issues de l'étape de solidification. Pour établir le rôle que joue le processus de croissance de la ferrite allotriomorphe sur la mise en place de la structure en bandes, nous avons développé un modèle de champ de phases possédant deux spécificités originales, imposées par le problème. D'une part, ce modèle est capable de reproduire les différents régimes cinétiques observés dans les alliages ternaires Fe-C-X, pilotés par la présence concomittante du carbone diffusant rapidement,et d'un élément substitutionnel X diffusant lentement. Nous avons ainsi mis en évidence la transition d'un régime initial rapide de paraéquilibre vers une croissance lente en orthoéquilibre, en bon accord avec des résultats expérimentaux de la littérature. D'autre part, notre modèle incorpore de manière économe la présence des joints de grains austénitiques, dont le rôle dans l'élimination des structures en bande est souligné par nos calculs. Nous observons ainsi qu'il existe un seuil d'intensité deségrégation en manganèse en dessous duquel le mouillage de la ferrite le long des joints de grain de plus grande énergie peut contrecarrer la croissance dans les bandes ségrégées négativement
The growth of allotriomorphic ferrite plays a major role in the formation of martensite bands in Dual-Phase steels. We have thus developed a phase field model to study the ferritic growth in different ternary Fe-C-X alloys, incorporating two necessary features. First, we have paid a particular attention to recover the different growth regimes due to the huge difference between the diffusion rates of Cand X substitutional species. Our calculations have exhibited a transition from fast paraequilibrium to slow orthoequilibrium in good agreement with experimental measurements in the literature. Second, austenite grain boundaries have been included in the model because they can conterbalance the manganese segregation bands, as shown in our calculations. Indeed, our results show that the bands can be broken bythe wetting of ferrite along the austenite grain boundaries, provided that the segregation is below a threshold value, and provided that the grain boundary energies are sufficiently high
Advisors/Committee Members: Gautier, Elisabeth (thesis director), Appolaire, Benoît (thesis director).
Subjects/Keywords: Champ de phase; Acier; Dual-phase; Ferrite; Phase field; Steel; Dual-phase; Ferrite
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APA (6th Edition):
Viardin, A. (2010). Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels. (Doctoral Dissertation). Lorraine INP. Retrieved from http://www.theses.fr/2010INPL014N
Chicago Manual of Style (16th Edition):
Viardin, Alexandre. “Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels.” 2010. Doctoral Dissertation, Lorraine INP. Accessed December 13, 2019.
http://www.theses.fr/2010INPL014N.
MLA Handbook (7th Edition):
Viardin, Alexandre. “Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels.” 2010. Web. 13 Dec 2019.
Vancouver:
Viardin A. Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels. [Internet] [Doctoral dissertation]. Lorraine INP; 2010. [cited 2019 Dec 13].
Available from: http://www.theses.fr/2010INPL014N.
Council of Science Editors:
Viardin A. Modélisation par champ de phases de la croissance de la ferrite allotriomorphe dans les aciers Fe-C-Mn : Phase field modeling of allotriomorphic ferrite growth in Fe-C-Mn steels. [Doctoral Dissertation]. Lorraine INP; 2010. Available from: http://www.theses.fr/2010INPL014N
University of Manchester
24.
Ward, Joseph.
MAX phase ceramics for nuclear applications.
Degree: PhD, 2018, University of Manchester
URL: https://www.research.manchester.ac.uk/portal/en/theses/max-phase-ceramics-for-nuclear-applications(b6b22354-f430-4e78-824e-3e34afd83273).html
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.756886
► The PhD research presented here is part of the new nuclear manufacturing (NNUMAN) research group, looking into novel materials and manufacturing processes. NNUMAN is an…
(more)
▼ The PhD research presented here is part of the new nuclear manufacturing (NNUMAN) research group, looking into novel materials and manufacturing processes. NNUMAN is an EPSRC funded (EP/J021172/1) program with direct support from Rolls Royce plc. The fabrication of MAX phase coatings by different means and assessing their tribological properties was the original theme of this thesis. However, due to issues with fabrication processes the overriding direction was moved towards assessing the response of bulk MAX phases to irradiating and corrosive environments. It is believed that this research will contribute to the understanding of suitable compositions and applications within nuclear. The MAX phases comprise an early transition metal (M), an A-group element (A) and either carbon or nitrogen (X). They have an inherently nano-layered structure with alternating ceramic (MX) and metallic (A) layers. The unique mix of both ceramic and metallic properties have made MAX phases a proposed material for nuclear applications. Proton irradiation is performed on Ti3SiC2, Ti3AlC2, Ti2AlC and Cr2AlC bulk MAX phases to 0.1 dpa at 350 °C. Crystallographic instabilities are observed through x-ray diffraction (XRD) analysis after irradiation. A mechanism for irradiation induced point defect swelling is proposed, by matching XRD and modelling data. Anti-site point defects are proposed to be a major contributor to anisotropic lattice parameter changes in Ti3SiC2. Additional carbon interstitial defects are also proposed in Ti3AlC2, as well as anti-site defects, making them less radiation tolerant. Further proton irradiations on Ti3SiC2 and Ti3AlC2 were performed at elevated temperatures to propose a temperature at which lattice changes are not observed. It is concluded that high proton fluences require temperatures in excess of ~700 °C and ~1,000 °C for Ti3SiC2 and Ti3AlC2, respectively. Corrosion of bulk MAX phases in simulated primary water also suggests a deleterious response to normal light water reactor (LWR) operations. Advanced scanning transmission electron microscopy (STEM) techniques, such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), is employed to understand corrosion mechanisms. Selective oxidation of A-layers is observed, with no evidence of passivation for Ti3SiC2, Ti3AlC2 and Ti2AlC. The response of Cr2AlC was most promising as little oxidation occurred, which is confirmed also with XRD analysis. A comprehensive corrosion mechanism is proposed, whereby compositions of MAX phase in LWR coolants is limited.
Subjects/Keywords: 620; MAX phase
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MLA ·
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APA (6th Edition):
Ward, J. (2018). MAX phase ceramics for nuclear applications. (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/max-phase-ceramics-for-nuclear-applications(b6b22354-f430-4e78-824e-3e34afd83273).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.756886
Chicago Manual of Style (16th Edition):
Ward, Joseph. “MAX phase ceramics for nuclear applications.” 2018. Doctoral Dissertation, University of Manchester. Accessed December 13, 2019.
https://www.research.manchester.ac.uk/portal/en/theses/max-phase-ceramics-for-nuclear-applications(b6b22354-f430-4e78-824e-3e34afd83273).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.756886.
MLA Handbook (7th Edition):
Ward, Joseph. “MAX phase ceramics for nuclear applications.” 2018. Web. 13 Dec 2019.
Vancouver:
Ward J. MAX phase ceramics for nuclear applications. [Internet] [Doctoral dissertation]. University of Manchester; 2018. [cited 2019 Dec 13].
Available from: https://www.research.manchester.ac.uk/portal/en/theses/max-phase-ceramics-for-nuclear-applications(b6b22354-f430-4e78-824e-3e34afd83273).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.756886.
Council of Science Editors:
Ward J. MAX phase ceramics for nuclear applications. [Doctoral Dissertation]. University of Manchester; 2018. Available from: https://www.research.manchester.ac.uk/portal/en/theses/max-phase-ceramics-for-nuclear-applications(b6b22354-f430-4e78-824e-3e34afd83273).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.756886
Oklahoma State University
25.
Dange, Alok.
Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium.
Degree: Mechanical & Aerospace Engineering, 2010, Oklahoma State University
URL: http://hdl.handle.net/11244/9915
► The current study focuses on flow characteristics and particle motion in the recirculation zone downstream of a backward facing step preceding a porous medium. A…
(more)
▼ The current study focuses on flow characteristics and particle motion in the recirculation zone downstream of a backward facing step preceding a porous medium. A two dimensional backward facing step is created in ICEM CFD and the computations are performed in FLUENT. The numerical results for the velocity field are validated with the experimental results and with previous numerical results from the literature. A porous medium is placed at 4.25h and 6.75h from the step, where h is the step height, and its effect on the recirculation zone and the particle motion is analyzed. The Reynolds numbers used are 6550 and 10000. The k-epsilon RNG model with standard wall functions is used for modeling the continuous
phase and the discrete
phase is modeled using the discrete
phase model of FLUENT. For the discrete
phase, monodispersed particles of 10 microns and 40 microns diameter and polydispersed particles ranging from 1 micron to 50 microns, corresponding to the Stokes number ranging from 0.1 to 10 are used. The particle tracks are studied for the filter at 4.25h and 6.75h from the step. It is observed that the numerical results for velocity are in agreement with the experimental results and with previous numerical results from the literature, except for the velocity profiles at X = 3.75h when the filter is placed at 4.25h from the step. This may be due to the porous jump boundary condition used to model the filter. The recirculation zone is highly affected by the placement of the filter at 4.25h from the step. But when the filter is moved farther downstream at 6.75h, the effect on the recirculation zone is negligible. The discrete
phase model tracks injected particles inside the domain and provides results which are qualitatively similar to the literature. It is observed that the particles with lower Stokes number, and thus lower momentum, tend to follow the flow and enter the recirculation zone and the particles with higher Stokes number tend to reach the filter directly without entering the recirculation zone. The location of the filter also plays a significant role. When the filter is moved farther downstream at 6.75h, the recirculation zone is increased which results in more particles entering the recirculation zone. The results for the monodispersed and the polydispersed particles agree.
Advisors/Committee Members: Chambers, Frank W. (advisor), Lilley, David G. (committee member), Sallam, Khaled A. (committee member).
Subjects/Keywords: discrete phase modeling
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APA (6th Edition):
Dange, A. (2010). Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium. (Thesis). Oklahoma State University. Retrieved from http://hdl.handle.net/11244/9915
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Dange, Alok. “Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium.” 2010. Thesis, Oklahoma State University. Accessed December 13, 2019.
http://hdl.handle.net/11244/9915.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Dange, Alok. “Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium.” 2010. Web. 13 Dec 2019.
Vancouver:
Dange A. Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium. [Internet] [Thesis]. Oklahoma State University; 2010. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/11244/9915.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Dange A. Modeling of Turbulent Particulate Flow in the Recirculation Zone Downstream of a Backward Facing Step Preceding a Porous Medium. [Thesis]. Oklahoma State University; 2010. Available from: http://hdl.handle.net/11244/9915
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Urbana-Champaign
26.
Cullen, Lindsey R.
Development of novel methodologies utilizing quaternary ammonium salts as catalysts.
Degree: PhD, Chemistry, 2015, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/88216
► The first half of this thesis (Chapter 2) described the development of a fluoride-promoted conjugate addition of sulfur-stabilized carbanion nucleophiles to α,β-unsaturated ketones and esters.…
(more)
▼ The first half of this thesis (Chapter 2) described the development of a fluoride-promoted conjugate addition of sulfur-stabilized carbanion nucleophiles to α,β-unsaturated ketones and esters. This reaction was achieved using a substoichiometric amount of TBAF, resulting in high yields on the desired 1,4-addition product. The addition of 1,3-dithianes was given particular focus as a novel method for the preparation of differentially protect 1,4-dicarbonyl compounds. Observation by 13C NMR spectroscopy provided evidence that the reaction proceeds through an ion pair, and attempts to extend this reaction to asymmetric additions using a chiral counterion are presented in detail.
The second half of this thesis (Chapter 3) details development of a
phase transfer catalyzed [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds. Initial investigation focused on identifying viable substrate classes that would undergo selective [2,3]-rearrangement under
phase transfer conditions. Under certain conditions, the [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds takes place in the presence of a
phase transfer agent, providing a rare example of a
phase transfer catalyzed unimolecular reaction. In the course of this investigation it was found that catalysis is dependent on several variables including base concentration, catalyst structure, and substrate lipophilicity. Preliminary testing of chiral, non-racemic
phase transfer catalysts has shown promising levels of enantioselectivity for future development.
Advisors/Committee Members: Denmark, Scott E. (advisor), Denmark, Scott E. (Committee Chair), Burke, Martin D. (committee member), Zimmerman, Steven C. (committee member), Silverman, Scott K. (committee member).
Subjects/Keywords: Phase Transfer Catalysis
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APA (6th Edition):
Cullen, L. R. (2015). Development of novel methodologies utilizing quaternary ammonium salts as catalysts. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/88216
Chicago Manual of Style (16th Edition):
Cullen, Lindsey R. “Development of novel methodologies utilizing quaternary ammonium salts as catalysts.” 2015. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed December 13, 2019.
http://hdl.handle.net/2142/88216.
MLA Handbook (7th Edition):
Cullen, Lindsey R. “Development of novel methodologies utilizing quaternary ammonium salts as catalysts.” 2015. Web. 13 Dec 2019.
Vancouver:
Cullen LR. Development of novel methodologies utilizing quaternary ammonium salts as catalysts. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2015. [cited 2019 Dec 13].
Available from: http://hdl.handle.net/2142/88216.
Council of Science Editors:
Cullen LR. Development of novel methodologies utilizing quaternary ammonium salts as catalysts. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2015. Available from: http://hdl.handle.net/2142/88216
University of Connecticut
27.
Badran, Karim M.
Theoretical Formulation of Phase Field Fracture.
Degree: MS, Mechanical Engineering, 2014, University of Connecticut
URL: https://opencommons.uconn.edu/gs_theses/708
► Phase field theory provides a new and different method of modeling crack propagation. This method utilizes a mathematical model to deal with interfaces of…
(more)
▼ Phase field theory provides a new and different method of modeling crack propagation. This method utilizes a mathematical model to deal with interfaces of multiphase problems. Although it is often used for solidification, in this project it will be used to model fracture dynamics. Which is done by considering a crack and an undamaged material as two separate phases and the crack progress through diffusion. This approach offers a computationally effective approach to model crack propagation, and allows for smooth transition between interfaces. The objective of this project was to test a theoretical
phase diffusion model developed by B. N. Cassenti et al.[1] for crack propagation. This was done using a MATLAB code written by Nicholas W. Oren that utilizes finite difference method. A number of tests cases were done to examine the behavior of the governing equations. Test cases consisted of a crack on a plate undergoing tension or shear stress on the boundaries of the plate. Through the test cases the physical dependency of the
phase on the random local velocity was studied. In addition the effects of a double-well potential term and an elastic modulus factor on crack growth were also examined. A novel method of tracking the crack front and a test case for crack arrest were presented. The development of a physics based diffusion model will also be discussed.
Advisors/Committee Members: Dr. Eric Jordan, Dr. Alexander Staroselsky, Dr. Brice N. Cassenti.
Subjects/Keywords: Phase Field Fracture
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APA (6th Edition):
Badran, K. M. (2014). Theoretical Formulation of Phase Field Fracture. (Masters Thesis). University of Connecticut. Retrieved from https://opencommons.uconn.edu/gs_theses/708
Chicago Manual of Style (16th Edition):
Badran, Karim M. “Theoretical Formulation of Phase Field Fracture.” 2014. Masters Thesis, University of Connecticut. Accessed December 13, 2019.
https://opencommons.uconn.edu/gs_theses/708.
MLA Handbook (7th Edition):
Badran, Karim M. “Theoretical Formulation of Phase Field Fracture.” 2014. Web. 13 Dec 2019.
Vancouver:
Badran KM. Theoretical Formulation of Phase Field Fracture. [Internet] [Masters thesis]. University of Connecticut; 2014. [cited 2019 Dec 13].
Available from: https://opencommons.uconn.edu/gs_theses/708.
Council of Science Editors:
Badran KM. Theoretical Formulation of Phase Field Fracture. [Masters Thesis]. University of Connecticut; 2014. Available from: https://opencommons.uconn.edu/gs_theses/708
28.
Zhao, Ruike.
A Mechanics Study on Surface Ruga Morphologies of Soft
Materials.
Degree: PhD, Mechanics of Solids, 2016, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:674263/
► The surface morphologies of different soft material systems comprise various ruga phases (wrinkle, crease, fold or ridge). In the past a few decades, despite that…
(more)
▼ The surface morphologies of different soft material
systems comprise various ruga phases (wrinkle, crease, fold or
ridge). In the past a few decades, despite that one-
phase specific
studies have revealed certain intrinsic properties of some ruga
phases, their evolutions and transitions between each other are
still unclear. In this thesis, finite element analysis (FEA) is
used to study soft-material surface deformation of a homogeneous
half space, and one or multilayer thin film(s) on a substrate,
every component of which is represented by an incompressible
neo-Hookean solid. Furthermore, experiments are carried out by a
self-tightening loading device to verify the distinct morphologies.
Based on the simulation results, we construct the primary bilayer
(PB) ruga-
phase diagram which guides manipulation of various ruga
configurations in bilayer systems. On the PB ruga-
phase diagram,
various
phase boundaries represent bifurcation sites of ruga
structures caused by lateral compression of the bilayer. All the
ruga phases eventually evolve to a limit
phase of either global
crease or global fold localization, depending on the stiffness
ratio of the bilayer, when compressed up to the Biot critical
strain of 0.456. Moreover, the substrate pre-stretch promotes
ridging of bilayers and ruga mode-period multiplications during
loading. The ridging is intrinsically growth limited and highly
dependent on both substrate pre-stretch and modulus ratio of the PB
system. Configuration-mobility bifurcation of ridges, caused by
symmetry breaking of individual ridge configuration, leads to
order-disorder transition in the system. We pointed out two
irreversibility types for a bilayer system with a stiff film.
Irreversibility is typically exhibited through either mode locking
or primary period switching. The former leads to cyclic hysteresis
of ruga configurations during a loading/unloading cycle of the PB
system without strain mismatch. The latter exhibits snap jumps in
the PB ruga-
phase transitions, enhanced by substrate pre-stretch
and sufficient viscoelastic loss tangent. With multi-layered or
graded modulus structure, ridging can be suppressed, and hierarchal
wrinkle wavelengths can be observed during loading. Along this
line, we summarize the ruga morphology control aspects and
corresponding controlling factors.
Advisors/Committee Members: Kim, Kyung-suk (Director), Gao, Huajian (Reader), Franck, Christian (Reader).
Subjects/Keywords: ruga-phase diagram
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APA (6th Edition):
Zhao, R. (2016). A Mechanics Study on Surface Ruga Morphologies of Soft
Materials. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:674263/
Chicago Manual of Style (16th Edition):
Zhao, Ruike. “A Mechanics Study on Surface Ruga Morphologies of Soft
Materials.” 2016. Doctoral Dissertation, Brown University. Accessed December 13, 2019.
https://repository.library.brown.edu/studio/item/bdr:674263/.
MLA Handbook (7th Edition):
Zhao, Ruike. “A Mechanics Study on Surface Ruga Morphologies of Soft
Materials.” 2016. Web. 13 Dec 2019.
Vancouver:
Zhao R. A Mechanics Study on Surface Ruga Morphologies of Soft
Materials. [Internet] [Doctoral dissertation]. Brown University; 2016. [cited 2019 Dec 13].
Available from: https://repository.library.brown.edu/studio/item/bdr:674263/.
Council of Science Editors:
Zhao R. A Mechanics Study on Surface Ruga Morphologies of Soft
Materials. [Doctoral Dissertation]. Brown University; 2016. Available from: https://repository.library.brown.edu/studio/item/bdr:674263/
29.
Hollen, Shawna M.
Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.
Degree: PhD, Physics, 2013, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:320462/
► The superconductor-insulator transition (SIT) is a well-known phenomenon that is observed in many types of superconducting systems, including elemental films and high Tc superconductors. Ultrathin…
(more)
▼ The superconductor-insulator transition (SIT) is a
well-known phenomenon that is observed in many types of
superconducting systems, including elemental films and high Tc
superconductors. Ultrathin films provide a versatile platform from
which to study this ubiquitous, and possibly universal, transition.
Two different theoretical approaches have been made to describe the
SIT in thin films. The first predicts that Cooper pairs (CPs) exist
in the insulating
phase, and the second proposes that the
transition is driven by pair-breaking, yielding an insulator of
localized single electrons.
Recent experiments showing the existence of an insulating
phase of localized CPs have provided significant support for the
first mechanism. This CP insulating (CPI)
phase exhibits dramatic
transport features including a giant magnetoresistance (MR) peak.
Previous work in the Valles lab found such a
phase in ultrathin
amorphous Bi films quench-condensed onto a substrate with a
nanohoneycomb (NHC) hole array. The local Cooper pairing
correlations of the CPI
phase were evident from Little-Parks-like
MR oscillations due to the hole array.
This thesis describes investigations of the mechanism for CP
localization and the emergence of the CPI
phase in NHC films. There
are three main results. First, the CPI
phase appears to be induced
in NHC films by the undulating surface of the substrate, which
produces regular spatial variations in thickness that give rise to
nanoscale CP islands. Second, the giant positive MR characteristic
of the CPI
phase emerges with increasing film thickness
simultaneously with the MR oscillation signal, associated with
local CP
phase coherence. The insulating phases of the thinnest
films and films in magnetic fields just beyond the MR peak likely
consist of CPs totally localized to their islands. Third, amorphous
holey films of uniform thickness do not exhibit a CPI
phase. These
films go from superconductors directly to fermionic insulators with
decreasing thickness. These results lend further insight to the
nature of the CPI
phase and also require at least two classes of
SITs: one that can describe the presence of a CPI
phase and one
that can describe a transition from a superconductor to a fermionic
insulator.
Advisors/Committee Members: Valles, James, Jr. (Director), Mitrovic, Vesna (Reader), Feldman, Dmitri (Reader).
Subjects/Keywords: quantum phase transition
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APA ·
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MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Hollen, S. M. (2013). Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320462/
Chicago Manual of Style (16th Edition):
Hollen, Shawna M. “Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.” 2013. Doctoral Dissertation, Brown University. Accessed December 13, 2019.
https://repository.library.brown.edu/studio/item/bdr:320462/.
MLA Handbook (7th Edition):
Hollen, Shawna M. “Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.” 2013. Web. 13 Dec 2019.
Vancouver:
Hollen SM. Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2019 Dec 13].
Available from: https://repository.library.brown.edu/studio/item/bdr:320462/.
Council of Science Editors:
Hollen SM. Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320462/
30.
Liu, Yanan.
X-Ray Phase Contrast and Spatial Harmonic Imaging.
Degree: PhD, Chemistry, 2013, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:320524/
► The primary objective of research described in this dissertation was the development of an X-ray imaging technique to enhance normal X-ray phase contrast imaging. Phase…
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▼ The primary objective of research described in this
dissertation was the development of an X-ray imaging technique to
enhance normal X-ray
phase contrast imaging.
Phase contrast imaging
exploits differences in the index of refraction of different
materials to image structures. The index of refraction difference
between an object and its surroundings causes a
phase shift between
the X-ray wave that travels through and outside the object. An
interference pattern results marking out the object. Liquid filled
liver images showed that liquid filled liver vessels provide clear
visualization. Additionally, a software processing method for
vessel detection was used to enhance the visibility of the
phase
contrast images. In this approach, 2-d Gabor wavelet and supervised
classification were used to detect vessel segmentation and classify
the vessels into a vessel class or a non-vessel class.
Furthermore,
phase contrast imaging combined with a
scattering technique called Spatial Harmonic Imaging (SHI) is
reported. Three important properties of spatial harmonic imaging
are shown in this dissertation. First, for objects containing
oriented structures, the scattering signal depends on the object’s
orientation relative to that of the grid, and the choice of
specific Fourier component. This property helps distinguish
different orientations that appear the same in absorption image.
Second, the image sensitivity can be increased by orders of
magnitude relative to normal X-ray
phase contrast imaging
technique. Third, spatial harmonic imaging enhances contrast at the
edge of an object by several times that of conventional
phase
contrast imaging. These properties substantially broaden the
applicability of
phase contrast imaging technique to clinical,
biological and industrial fields.
Advisors/Committee Members: Diebold, Gerald (Director), Rose-Petruck, Christoph (Director), Weber, Peter (Reader), Doll, Jimmie (Reader).
Subjects/Keywords: Phase contrast imaging
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APA (6th Edition):
Liu, Y. (2013). X-Ray Phase Contrast and Spatial Harmonic Imaging. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320524/
Chicago Manual of Style (16th Edition):
Liu, Yanan. “X-Ray Phase Contrast and Spatial Harmonic Imaging.” 2013. Doctoral Dissertation, Brown University. Accessed December 13, 2019.
https://repository.library.brown.edu/studio/item/bdr:320524/.
MLA Handbook (7th Edition):
Liu, Yanan. “X-Ray Phase Contrast and Spatial Harmonic Imaging.” 2013. Web. 13 Dec 2019.
Vancouver:
Liu Y. X-Ray Phase Contrast and Spatial Harmonic Imaging. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2019 Dec 13].
Available from: https://repository.library.brown.edu/studio/item/bdr:320524/.
Council of Science Editors:
Liu Y. X-Ray Phase Contrast and Spatial Harmonic Imaging. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320524/
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