Dissertations / Theses: 'PhaseI'

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Sang, Yan. "Phases and Phase Transitions in Quantum Ferromagnets." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/18716.

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In this dissertation we study the phases and phase transition properties of quantum ferromagnets and related magnetic materials. We first investigate the effects of an external magnetic field on the Goldstone mode of a helical magnet, such as MnSi. The field introduces a qualitatively new term into the dispersion relation of the Goldstone mode, which in turn changes the temperature dependences of the contributions of the Goldstone mode to thermodynamic and transport properties. We then study how the phase transition properties of quantum ferromagnets evolve with increasing quenched disorder. We find that there are three distinct regimes for different amounts of disorder. When the disorder is small enough, the quantum ferromagnetic phase transitions is generically of first order. If the disorder is in an intermediate region, the ferromagnetic phase transition is of second order and effectively characterized by mean-field critical exponents. If the disorder is strong enough the ferromagnetic phase transitions are continuous and are characterized by non-mean-field critical exponents.

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Ran, Ying. "Spin liquids, exotic phases and phase transitions." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45404.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.
Includes bibliographical references (p. 135-139).
Spin liquid, or featureless Mott-Insulator, is a theoretical state of matter firstly motivated from study on High-Tc superconductor. The most striking property of spin liquids is that they do not break any physical symmetry, yet there are many types of them, meaning a phase transition is necessary from one spin liquid to another. It was a long debate about whether these exotic states can serve as the ground states in real materials or even models. In this thesis I firstly discuss a large-N model, where we show the spin liquid states can be the ground states. Because the spin liquid phases cannot be characterized by symmetry breaking, the phase transitions associated with them are naturally beyond the traditional Laudau's paradigm. I discuss a few scenarios of these exotic phase transitions to show a general picture about what can happen for such exotic transitions. Those exotic phase transitions can actually serve as a way to detect these exotic phases. Then I move to a much more realistic model: spin-1/2 Kagome lattice, where we propose a U(1)-Dirac spin liquid as the ground state. The implications on the recent material ZnCu3(OH)6C12 are discussed. Finally, I come back to the high-Tc problem. A doped spin liquid can naturally be superconducting whose many properties have already been confirmed by experiments. Here I particularly study one experimental puzzle: the nodal-antinodal dichotomy in underdoped High-Tc material. This used to be one difficulty of the doped spin liquid theory. We show that a doped spin liquid can naturally has nodal-antinodal dichotomy due to further neighbor hoppings (t' and t").
by Ying Ran.
Ph.D.

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3

Xu, Jian. "X-Band Phase Shifters for Phased Array." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1196888776.

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4

Diat, Olivier. "Effet du cisaillement sur des phases lyotropes : phase lamellaire et phase éponge." Bordeaux 1, 1992. http://www.theses.fr/1992BOR10611.

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Les phases de membranes ont ete depuis longtemps l'objet de nombreuses etudes, quant a leurs proprietes statiques. Dans cette these, nous etudions leur dynamique et plus specifiquement, l'effet d'un cisaillement. Par differentes techniques de mesure (conoscopie, diffusion de lumiere, de neutrons ou de rayons x, microscopie, rheologie), nous presentons, et analysons les differents etats d'orientation d'une phase lamellaire lyotrope dans un systeme quaternaire eau-dodecane-sds-pentanol; un etat de vesicules multi-lamellaires de taille controlee par le cisaillement existe quel que soit le systeme lamellaire etudie. Une etude parallele concerne l'effet du cisaillement sur une phase eponge et semble indiquer une transition vers une phase lamellaire

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5

Zetterling, Fredrik. "Phase Transformations in Computer Simulated Icosahedrally Ordered Phases." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3570.

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Computer simulations play a profound and fundamental role inmodern theoretical physics, chemistry and materials science. Tounderstand the complex physics of metally liquids, metals,quasicrystals and metally glasses a working model imposing thelocal and global order is needed. Experiments and theory havepredicted the local order in liquid metals to beicosahedral.

The current work has been done using molecular dynamicscomputer simulations of a monatomic system using a simplepair-potential for the interactions. Two new pair-potentialshas been developed, the Zetterling-1(Z1) and Zetterling-2(Z2)potentials. They are specifically modeled to impose icosahedralorder. The basis for the development of the potentials was theold Dzugutov potential which is known to freeze into adodecagonal quasicrystal. The new Zetterling potentials have alonger interaction range and a narrower first minimum. The morenarrow first minimum will enhance the local icosahedralordering and the longer interaction range was introduced toincorporate a second maximum in the potential mimicing theFriedel oscillations found in metallic systems. These Friedeloscillations are due to the singularity which arises at theFermi surface due to the screening of the positive charge bythe electron gas.

Five papers are included in the study. The first two papersare studies of icosahedral clustering in the liquid andsupercooled liquid. The simulations in Paper I was done usingthe old Dzugutov potential while the new potentials were usedin Paper II using both molecular dynamics and the Basin Hoppingalgorithm presented in Chapter 5. Paper III considers theconcept of dynamical ergodicity in the context of thesuper-cooled liquid behaviour. The simulations were made usingthe old Dzugutov potential. Paper IVr eports a moleculardynamics simulation using the Dzugutov potential undersuper-cooling. A formation of icosahedrally structured domainswith distinctly slow diffusion which grows with cooling in alow-dimensional manner and percolate around Tc, the criticaltemperature of the mode-coupling theory. A sharp slowing downof the structural relaxation relative to diffusion is observed.It is concluded that this effect cannot be accounted for by thespatial variation in atomic mobility. The low-dimensionalclustering is discussed as a possible mechanism of fragility.Paper Vin vestigates the crystallization of a simple monatomicliquid model which utilizes the Zetterling-1 potential. Thesystem forms a thermodynamically stable solid phase exhibitingcubic symmetry. Its diffraction pattern is identified as thatof γ-brass, a tetrahedrally packed crystalline structurewith 52 atoms in the unit cell.

Keywords:simple liquids, molecular dynamics, pairpotential, icosahedral cluster.

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Knott, Michael. "Phases and phase transitions in charged colloidal suspensions." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270941.

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7

Auguste, Frédéric. "Flexibilité et structure de deux phases lyotropes : phase lamellaire et phase de vésicules." Bordeaux 1, 1993. http://www.theses.fr/1993BOR10587.

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8

Ghaemi, Mohammadi Pouyan. "Phases and phase transitions of strongly correlated electron systems." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45456.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.
Includes bibliographical references (leaves 169-174).
Different experiments on strongly correlated materials have shown phenomena which are not consistent with our conventional understandings. We still do not have a general framework to explain these properties. Developing such a general framework is much beyond the scope of this thesis, but here we try to address some of challenges in simpler models that are more tractable. In correlated metals it appears as strong correlations have different effect on different parts of fermi surface. Perhaps most striking example of this is normal state of optimally doped cuprates; the quasiparticle peaks on the nominal fermi surface do not appear uniformly. We try to track such phenomena in heavy fermion systems, which are correlated fermi liquids. In these systems, a lattice of localized electrons in f or d orbitals is coupled to the conduction electrons through an antiferromagnetic coupling. Singlets are formed between localized and conduction electrons. This singlet naturally have non-zero internal angular momentum. This nontrivial structure leads to anisotropic effect of strong correlations. Internal structure of Kondo singlet can also lead to quantum Hall effect in Kondo insulator, and formation of isolated points on the fermi surface with fractionalized quasiparticles. In the second part we study a phase transition in Heisenberg model between two insulating phases, Neel ordered and certain spin liquid state, popular in theories of the cuprates. The existence of such a transition has a number of interesting implications for spin liquid based approaches to the underdoped cuprates and clarifies existing ideas for incorporating antiferromagnetic long range order into such a spin liquid based approach. This transition might also be enlightening, despite fundamental differences, for the heavy fermion critical points where a second order transition between the heavy fermion phase and a metallic phase with magnetic antiferromagnetic order is observed.
by Pouyan Ghaemi Mohammadi.
Ph.D.

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Sanyal, Alarka. "CMOS Phase Shifter for Conformal Phased Array Beamformer Applications." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27697.

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A vector modulator based phase shifter is developed using 0.18um CMOS process at S-band frequency to be integrated into a conformal phased array antenna to recover the desired radiation pattern in the entire 360? range. The phase shifter has a variable gain amplifier integrated into the circuit in order to vary gain along with phase for precise control to correct the degraded radiation pattern due to the conformal shaping. The results show state-of-the-art performances including more than 7dB conversion gain with variable feature, a continuous phase rotation of 360? with steps as low as 11.25? and very low power consumption of 17mW, for the first time to the best of the authors? knowledge. The chip size including all pads is 1.5mm X 0.75mm.
ND NASA EPSCoR (Agreement FAR0020852)

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Ye, Bing. "Unconventional Quantum Phases in Strongly Correlated Systems." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:106990.

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Thesis advisor: Ying Ran
In this thesis, I investigated and implemented various numerical and simulation methods, including mean field theory, functional renormalization group method (fRG), density matrix renormalization group (DMRG) method etc., to find different quantum phases and quantum phase diagrams on models of correlated electronic systems. I found different phase diagrams with phases such as magnetism, superconductivity. By summarizing the strength and limitations of these methods, I investigated the projected entangled paired states (PEPS) with symmetry quantum number to sharply distinguish phases into crude classes and applied a variation of fast full update (FFU) prototype[58] to simulate different phases numerically. This method provides a promising, powerful and efficient way to simulate unconventional quantum phases and quantum phase diagrams in correlated electronic systems
Thesis (PhD) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics

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11

Kim, Sunghwan. "Phase shifter approaches for compact low-power phased array transmitters." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3398530.

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Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed May 5, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 103-109).

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Tweedlie-Yuill, Tracey. "Characterisation of cyanopropyl stationary phases for reserved phase liquid chromatography." Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488857.

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The current study has demonstrated that CN phases have poor stability and should not be operated above pH 5.7. Nonetheless, a number of protocols have been developed for the characterization of CN phases that include a measurement of silanophilic interaction determined in mobile phases with pH > 5.7. The aim of this study was to perform the chromatographic characterization of commercially available CN phases using two distinct approaches.

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Waichigo, Martin M. "Alkylammonium Carboxylates as Mobile Phases for Reversed-Phase Liquid Chromatography." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1134142423.

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14

Heinisch, Sabine. "Optimisation des phases mobiles binaires et ternaires en chromatographie en phase liquide à polarité de phases inversée." Lyon 1, 1993. http://www.theses.fr/1993LYO10116.

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Le but de ce travail est de developper une methode d'optimisation rapide et fiable pour etablir les conditions d'elution optimales en chromatographie en phase liquide a polarite de phases inversee. Nous avons tente, par cette methode, de resoudre un grand nombre des problemes auxquels le chromatographiste peut se trouver confronte: optimisation en gradient d'elution, prise en compte des hauteurs relatives et asymetries des pics, selection de modificateurs organiques. Les performances de cette methode ainsi que ces limites sont discutees dans ce travail et illustrees par differentes applications

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15

Apte, Pankaj A. "Phase equilibria and nucleation in condensed phases a statistical mechanical study /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1135876018.

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16

Baumann, Wolfgang [Verfasser]. "Phase-transformation kinetics of TiCr2 laves phases / vorgelegt von Wolfgang Baumann." Stuttgart : Max-Planck-Inst. für Metallforschung, 2010. http://d-nb.info/1007316489/34.

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Charles, Cameron T. "A calibrated phase and amplitude control system for phased-array transmitters /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5911.

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Khong, Teck Meng. "Heterogeneous gas phase reactions for the production of chemically bonded phases." Thesis, Birkbeck (University of London), 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246077.

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Grover, Tarun Ph D. Massachusetts Institute of Technology. "Applied fractionalization : quantum phases and phase transitions of strongly interacting systems." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/68973.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 131-136).
Strongly correlated systems present interesting challenges in condensed matter physics. On the one hand, the theoretical work in the last two decades suggests that strong interactions may lead to new phases and phase transitions of matter that don't fit paradigms such as Fermi liquid theory or Landau's theory of phase transitions. On the other hand, there are actual materials which are undoubtedly governed by strong interactions and indeed do not fit the conventional paradigms but whose behavior often doesn't quite match our theoretical expectations. This gap between theory and experiments is slowly narrowing owing to the discovery of new materials and recent advances in numerical simulations. As an example, the material K - (ET)2Cu 2(CN) 3 exhibits metallic specific heat in its insulating phase. This is indicative of the theoretically proposed phenomena of 'fractionalization' where elementary excitations in a phase carry quantum numbers that are fractions of that corresponding to an electron. Similarly, there is growing numerical evidence of the theoretical phenomena of 'deconfined quantum criticality', where quantum Berry phases lead to emergence of fractionalized particles right at the phase transition. In this thesis we study phenomena where the concept of fractionalization is a useful tool to explore new phases and phase transitions. Most of our examples are in the context of frustrated quantum magnets. Along the way, we also explore topics such as quantum numbers of topological defects and non-abelian phases of matter. Whenever possible, we compare theoretical predictions with experimental and numerical data. We also discuss deconfined quantum criticality in the context of metallic systems where it opens the route to phase transitions very different from the conventional spin-density wave instability of Fermi surface.
by Tarun Grover.
Ph.D.

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20

Debray, Jean-Christophe. "Elaboration de phases stationnaires originales pour la chromatographie en phase gazeuse." Rouen, 2014. http://www.theses.fr/2014ROUES048.

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Lienne, Michelle. "Separation d'enantiomeres par chromatographie en phase liquide sur phases stationnaires chirales." Paris 6, 1989. http://www.theses.fr/1989PA066318.

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La separation directe d'enantiomeres par chromatographie en phase liquide sur phases stationnaires chirales (psc) repose sur la difference de stabilite des complexes diastereoisomeres formes transitoirement entre les enantiomeres du solute et les entites chirales de la psc. La premiere partie de ce memoire est consacree a l'etude de psc de type pirkle synthetisees a partir d'oxydes de phosphines chiraux ou de derives n-dinitro-3,5-benzoyle (dnb) d'acides amines. Des mecanismes bimoleculaires de reconnaissance chirale sont discutes et les parametres qui les affectent sont evalues. La seconde partie rassemble trois exemples de strategies de separations enantiomeriques concernant des composes appartenant a des familles therapeutiques variees: butyrolactones et butyrolactames (cytotoxiques), sulfoxides derives du benzimidazole (anthelminthiques) et esters de l'acide (thienyl-3)-2-cyclohexyl-2-glycolique (anticholinergiques)

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Huang, Tsang-Min. "Phase Equilibria of Binary Liquid Crystal Mixtures Involving Induced Ordered Phases." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1284381816.

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Apte, Pankaj A. "Phase equilibria and nucleation in condensed phases: a statistical mechanical study." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1135876018.

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Torrellas-Hidalgo, Luzmila. "EFFECTS OF ETHANOL/WATER MOBILE PHASES ON REVERSED-PHASE LIQUID CHROMATOGRAPHY." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275466.

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Jones, Kevin David. "Three-Phase Linear State Estimation with Phasor Measurements." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32119.

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Given the ability of the Phasor Measurement Unit (PMU) to directly measure the system state and the increasing implementation of PMUs across the electric power industry, a natural expansion of state estimation techniques would be one that employed the exclusive use of PMU data. Dominion Virginia Power and the Department of Energy (DOE) are sponsoring a research project which aims to implement a three phase linear tracking state estimator on Dominionâ s 500kV network that would use only PMU measurements to compute the system state. This thesis represents a portion of the work completed during the initial phase of the research project. This includes the initial development and testing of two applications: the three phase linear state estimator and the topology processor. Also presented is a brief history of state estimation and PMUs, traditional state estimation techniques and techniques with mixed phasor data, a development of the linear state estimation algorithms and a discussion of the future work associate with this research project.
Master of Science

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Gendron, François-Xavier. "Contribution à la discrimination chirale à l'état solide et accès aux énantiomères pures par cristallisation." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR032/document.

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Le besoin d’accès aux énantiomères purs a largement augmenté depuis les années 90. Les procédés ayant recours à la cristallisation sont souvent moins cher mais tout aussi efficace que les autres procédés. Deux études ont été réalisées dans cette thèse : -La première concerne l’amélioration d’un procédé déjà établi. En effet, l’efficacité de la Cristallisation Préférentielle (PC) de conglomérat est connue. Néanmoins, son application à des solutions solides images l’une de l’autre dans un miroir est plus complexe. Est présenté le premier exemple de PC réalisée sur un système à solution solide complète démixant à basse température : le sel d’hydrogénomaléate de baclofène (un API). De plus, il s’agit de la première preuve expérimentale d’un tel équilibre de phases et de PC de solutions solides dont les résultats sont comparables à la cristallisation préférentielle traditionnelle. -Le second sujet ne traite pas directement de la séparation d’énantiomère mais de prometteuses discriminations chirales ont été obtenues. Le diagramme d’équilibre de phases entre les compositions racémiques de deux couples d’atropoisomères a été étudié. Deux résultats en lien avec la discrimination chirale ont été établis : le premier est la possibilité de déracémiser un composé A initialement non-discriminé (composé racémique) à l’intérieur de la matrice d’un composé B discriminé (conglomérat). Le second est l’observation d’un nouveau type de chiralité : Chiralité Induite par Dissymmétrie de Distribution (CIDD)
The need for access to pure enantiomers has largely increased since the nineties. Processes using crystallization are often cheaper and as efficient as other processes. Thus, the improvement of existing techniques and the need for new processes are attractive for scientist and industry. Two studies have been performed in this thesis:The first one concerns the improvement of an existing technique. Indeed, conglomerate Preferential Crystallization efficiency is well known. Nonetheless, its application to mirror image partial solid solutions is more difficult. Here is presented the first example of PC performed on a complete solid solution at high temperature which shows a solid solutions demixion at low temperature: the baclofen hydrogenomaleate salt (an API). Moreover, it is the first experimental observation of such phase equilibria and PC of mirror image solid solutions whose results are comparable to classical PC. -The second topic did not involve directly enantiomer separation but promising chiral discriminations have been obtained. The phase diagram between the racemic composition of two couples of atropisomers has been defined. Beside multiples equilibria observed, two results concerning the chiral discrimination can be highlighted: the first one is the possibility to deracemize a compound A initially not discriminated (racemic compound) inside the matrix of a compound B (which forms a stable conglomerate). The second is the observation of a new kind of chirality: Chirality Induced by Dissymmetric Distribution (CIDD)

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Aufrecht, Jochen Marc [Verfasser]. "Phase transformations of the NbCr2 and HfCr2 Laves phases / Jochen Marc Aufrecht." Stuttgart : Max-Planck-Inst. für Metallforschung, 2010. http://d-nb.info/1010529943/34.

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Watson, Richard Charles. "Studies of reversed phase high performance liquid chromatography (RP-HPLC) stationary phases." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338492.

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Li, Hongxing. "Mechanical Properties of Dual Phase Alloys Composed of Soft and Hard Phases." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215959.

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Tsai, Yen-Chang. "Development of the phase synchronization circuit for wirelessly distributed digital phased array." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FTsai.pdf.

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Thesis (M.S. in Electronic Warfare Systems Engineering)--Naval Postgraduate School, September 2009.
Thesis Advisor(s): Jenn, David C. "September 2009." Description based on title screen as viewed on Novermber 5, 2009. Author(s) subject terms: Radar, Distributed array, Phased Array, Phase Synchronization, Digital Radar, Digital Beamforming (DBF), Wireless Beamforming, Wireless Network Sensor, Aperstructure, Opportunistic Array, LabVIEW, Ballistic Missile Defense (BMD), CG(X), DDG-1000, Network-Centric Warfare (NCW), UAV, Modulator, Demodulator, Filter, Transmit/ Receive (T/R) Module, Leakage Cancellation. Includes bibliographical references (p. 105-108). Also available in print.

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Speybrouck, David. "Impact de l'additif en chromatographie en phase supercritique sur phases stationnaires énantiosélectives." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR052/document.

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Le développement de molécules chirales est devenu un enjeu majeur pour l’industrie pharmaceutique. Lors de la mise au point d’un nouveau principe actif, la chromatographie en phase supercritique (CPS) sur phases stationnaires énantiosélectives, est devenue une méthode incontournable pour l’analyse ou la purification d’énantiomères. Il n’en demeure pas moins que certains composés tels que les composés basiques restent délicats à analyser par cette technique et que l’ajout d’un additif basique dans la phase mobile est très souvent nécessaire. La quantité d’additif ajoutée dans la phase mobile est souvent choisie de manière arbitraire en se basant sur les spécifications des fournisseurs de phases stationnaires et sur les travaux publiés dans le domaine, sans se soucier de l’effet potentiel sur la résolution d’une modification de sa concentration. Ce travail de thèse a démontré l’importance de la concentration en additif dans la phase mobile lors de l’analyse de mélanges d’énantiomères par CPS, avec notamment des effets significatifs sur l’énantiosélectivité allant jusqu’à une inversion de leur ordre d’élution selon la concentration en additif. Dans un deuxième temps cette étude a consisté en une amélioration de notre compréhension des modes d’actions de l’additif, sur la phase stationnaire et sur la phase mobile permettant de poser des hypothèses sur les effets observés lors de la séparation d’énantiomères. La dernière partie est consacrée à la présentation de différents exemples, justifiant l’intérêt de moduler la concentration en additif lors de séparations d’énantiomères
Nowadays, the development of chiral molecule is a strategic issue for the pharmaceutical industry. During the development of a new molecular entity, supercritical fluid chromatography using enantioselective stationary phases is essential for the analysis or the purification of racemates. Despite the advantages of SFC, the analysis of some compounds like basic compounds may still be a challenge. Their analysis most of the time, requires an additive in the mobile phase. In many cases additives concentration is chosen arbitrarily, based on the columns supplier guidelines and work already published, regardless of the impact of the additive concentration on the resolution. This work has shown the impact of the additives concentration for the analysis of enantiomers by SFC, in particular a significative impact on the enantioselectivity of chiral stationary phases, with for some of them a reversal elution order depending on the additive concentration. The second objective is to improve our knowledge on the mechanism of action of the additive both on the stationary phase and the mobile phase. The last part is dedicated to the presentation of a few examples highlighting the positive impact of the variation of the additives concentration for enantiomer separation

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da, Silva Neddef N. (Nedio). "Active phased array transceiver:an operational compensation for a multiple phase shifter system." Master's thesis, University of Oulu, 2018. http://jultika.oulu.fi/Record/nbnfioulu-201805151790.

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Abstract. The upcoming fifth-generation mobile technology relies on the implementation of beamforming techniques to fulfill the requirements proposed for the 2020 roll-out. One of the processes for stepping up this technique from the high-end applications to the telecommunication mass market is to be able to test, analyze and tune the product according to the specifications. After the manufacturing process, the phased antenna array, beamforming and beam-steering system must be tested against a prediction model, and corrected against deviations due to the uniqueness of the components, with the objective to conform the final product to be in accordance with specifications, while at low cost and time. The aim of this work is to propose and test different procedures for calibrating the phase component of an RF phased array transceiver with multiple phase-shifters. The different proposed procedures are compared in an over-the-air measurement through the performance when applying the beamforming and beam-steering techniques.

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33

Tönjes, Ralf. "Pattern formation through synchronization in systems of nonidentical autonomous oscillators." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1597/.

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This work is concerned with the spatio-temporal structures that emerge when non-identical, diffusively coupled oscillators synchronize. It contains analytical results and their confirmation through extensive computer simulations. We use the Kuramoto model which reduces general oscillatory systems to phase dynamics. The symmetry of the coupling plays an important role for the formation of patterns. We have studied the ordering influence of an asymmetry (non-isochronicity) in the phase coupling function on the phase profile in synchronization and the intricate interplay between this asymmetry and the frequency heterogeneity in the system. The thesis is divided into three main parts. Chapter 2 and 3 introduce the basic model of Kuramoto and conditions for stable synchronization. In Chapter 4 we characterize the phase profiles in synchronization for various special cases and in an exponential approximation of the phase coupling function, which allows for an analytical treatment. Finally, in the third part (Chapter 5) we study the influence of non-isochronicity on the synchronization frequency in continuous, reaction diffusion systems and discrete networks of oscillators.
Die vorliegende Arbeit beschäftigt sich in Theorie und Simulation mit den raum-zeitlichen Strukturen, die entstehen, wenn nicht-identische, diffusiv gekoppelte Oszillatoren synchronisieren. Wir greifen dabei auf die von Kuramoto hergeleiteten Phasengleichungen zurück. Eine entscheidene Rolle für die Musterbildung spielt die Symmetrie der Kopplung. Wir untersuchen den ordnenden Einfluss von Asymmetrie (Nichtisochronizität) in der Phasenkopplungsfunktion auf das Phasenprofil in Synchronisation und das Zusammenspiel zwischen dieser Asymmetrie und der Frequenzheterogenität im System. Die Arbeit gliedert sich in drei Hauptteile. Kapitel 2 und 3 beschäftigen sich mit den grundlegenden Gleichungen und den Bedingungen für stabile Synchronisation. Im Kapitel 4 charakterisieren wir die Phasenprofile in Synchronisation für verschiedene Spezialfälle sowie in der von uns eingeführten exponentiellen Approximation der Phasenkopplungsfunktion. Schliesslich untersuchen wir im dritten Teil (Kap.5) den Einfluss von Nichtisochronizität auf die Synchronisationsfrequenz in kontinuierlichen, oszillatorischen Reaktions-Diffusionssystemen und diskreten Netzwerken von Oszillatoren.

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34

Cha, Jun Ho. "A steerable array antenna using controllable microwave dielectric slab phase shifters on a coplanar waveguide /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5824.

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35

Chatchawalsaisin, Jittima, John Kendrick, S. C. Tuble, and Jamshed Anwar. "An optimized force field for crystalline phases of resorcinol." Royal Society of Chemistry, 2008. http://hdl.handle.net/10454/4733.

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no
The two known crystalline phases of resorcinol and their phase transitions are of considerable interest. The crystals exhibit pyro- and piezo-electricity and, remarkably, the higher temperature phase is the denser phase. Furthermore, crystals of the phase, by virtue of having a polar axis, have played a crucial role in investigating fundamental issues of crystal growth. We report an optimized force field for the molecular simulation of crystalline phases of resorcinol. The hydroxyl groups of the resorcinol molecule have a torsional degree of freedom and the molecule adopts a different conformation in each of the two phases of resorcinol. The torsional barrier, therefore, was considered to be critical and has been characterized using ab initio methods. Although the atomic partial charges showed some dependence on the molecular conformation, a single set of partial charges was found to be sufficient in describing the electrostatic potential for all conformations. The parameters for the van der Waals interactions were optimized using sensitivity analysis. The proposed force field reproduces not only the static structures but also the stability of the crystalline phases in extended molecular dynamics simulations.

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36

Kokel, Samuel John. "Retrodirective phase-lock loop controlled phased array antenna for a solar power satellite system." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3047.

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This thesis proposes a novel technique using a phase-lock loop (PLL) style phase control loop to achieve retrodirective phased array antenna steering. This novel approach introduces the concept of phase scaling and frequency translation. It releases the retrodirective transmit-receive frequency ratio from integer constraints and avoids steering approximation errors. The concept was developed to achieve automatic and precise beam steering for the solar power satellite (SPS). The testing was performed using a transceiver converting a pair of received 2.9 GHz signals down to 10 MHz, and up converting two 10 MHz signals to 5.8 GHz. Phase scaling and conjugation was performed at the 10 MHz IF using linear XOR phase detectors and a PLL loop to synthesize a 10 MHz signal with conjugate phase. A phase control loop design is presented using PLL design theory achieving a full 2π steering range. The concept of retrodirective beam steering is also presented in detail. Operational theory and techniques of the proposed method are presented. The prototype circuit is built and the fabrication details are presented. Measured performance is presented along with measurement techniques. Pilot phase detectors and PCL achieve good linearity as required. The achieved performance is benchmarked with standards derived from likely performance requirements of the SPS and beam steering of small versus large arrays are considered.

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37

Bitteur, Sylvaine. "Etude, par chromatographie en phase liquide, du partage de composes d'arôme entre une phase aqueuse et des phases stationnaires hydrophobes." Paris 6, 1986. http://www.theses.fr/1986PA066449.

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Ce travail a consisté à étudier dans quelle mesure la chromatographie en phase liquide permet d'extraire les composes d'arôme présents en très faible concentration dans les effluents aqueux des industries agro-alimentaires. Les rendements d'extraction accessibles par enrichissement de traces étant directement lies aux facteurs de capacité des solutés d'intérêt, l'étude proposée se ramenait à celle du partage de composes d'arôme entre une phase aqueuse et des phases stationnaires hydrophobes. La première partie détaille les divers paramètres susceptibles de modifier les rendements d'extraction par les principaux types de supports apolaires de la chromatographie en phase liquide et met en évidence le caractère indispensable d'une étude systématique préalable. Une telle étude, menée à l'aide de composes modèles d'arôme et de supports chromatographiques choisis fait l'objet de la seconde partie. L'ensemble des résultats obtenus au terme de cette études systématique est finalement teste dans le cas concret d'un effluent aqueux industriel contenant des composes d'arôme de cassis à l'état de traces.

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38

Bitteur, Sylvaine. "Etude par chromatographie en phase liquide, du partage de composés d'arome entre une phase aqueuse et des phases stationnaires hydrophobes." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375960653.

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39

Grahn, Micael J. "Wirelessly networked digital phased array analysis and development of a phase synchronization concept." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5FGrahn.pdf.

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Thesis (M.S. in Electronic Warfare Systems Engineering)--Naval Postgraduate School, September 2007.
Thesis Advisor(s): Jenn, David. "September 2007." Description based on title screen as viewed on October 23, 2007. Includes bibliographical references (p.67-69). Also available in print.

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40

Gray, Sarah Jane. "Dissipative particle dynamics simulations of surfactant systems : phase diagrams, phases and self-assembly." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12641/.

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Surfactants, as lyotropic liquid crystals, exhibit a whole host of ordered liquid phases, as a function of surfactant concentration, solvent identity, and any additives present. These ordered phases confer properties to the solution on a macroscopic level, and so understanding ordered phase formation is critical in predicting the physical behaviours of surfactant--containing mixtures. Typically, household cleaning products contain sufficiently low surfactant concentrations that micellar solutions form, resulting in isotropic, low viscosity liquids. However, in recent years ``single unit dose'' (SUD) products have became increasing popular. The formulation of SUDs results in high concentrations of surfactant, which can result in undesirable properties such as excessively high viscosity, turbidity, and poor product dispersal. This work aims to elucidate the nature of the ordered structures that form in these products, and understand the molecular driving factors that result in their formation. To gain an understanding of the molecular--level interactions involved in these liquid mixtures, we applied the Dissipative Particle Dynamics (DPD) simulation method. DPD is the ideal technique to study mesophase formation of these mixtures as it is exceptionally fast, allowing one to simulate on the mesoscale (the pertinent length scale for mesophase studies) while retaining detail on the order of molecular fragments. The main body of this work has been dedicated to investigating the parameterisation of DPD models in a tractable manner. We have developed a highly transferable DPD model of the most common anionic surfactants: sodium dodecylsulphate, linear alkylbenzene sulphonate, and alkylether sulphate. Our model reproduces the phase behaviour of both individual isomers and isomeric mixtures, across entire phase diagrams (with respect to concentration). Although there are some difficulties in producing chemically tractable models with DPD, once developed these models are an incredibly powerful tool in studying phase behaviour from a molecular perspective.

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41

WANG, YU ALBERT. "RF MEMS SWITCHES AND PHASE SHIFTERS FOR 3D MMIC PHASED ARRAY ANTENNA SYSTEMS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022186207.

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42

Impéror-Clerc, Marianne. "Étude de transition de phase vers les phases cubiques des systèmes eau/surfactant." Paris 11, 1992. https://tel.archives-ouvertes.fr/tel-01989797.

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Les phases cubiques des systèmes binaires eau/surfactant sont un cas d'organisation liquide-cristalline de la matière très surprenant. Leur structure allie, a un ordre local liquide, une périodicité tridimensionnelle à l'échelle mésoscopique, qui en fait de véritables cristaux de films fluides. Elle se caractérise également par une topologie bicontinue tout à fait remarquable. Partant de l'observation de la croissance en épitaxie d'une phase cubique (de groupe d'espace Ia3d, le plus fréquent) à partir des mésophases lamellaire et hexagonale, nous nous sommes attaches à décrire comment, d'un point de vue purement structural, il est possible de déduire la structure cubique de celles, plus simples, de ces autres mésophases. Tout d'abord, la croissance en épitaxie de la phase cubique a été observée en diffusion des rayons X sur des échantillons monocristallins, ainsi qu'au microscope polarisant. Des désordres caractéristiques de chacune des mésophases, liés à leur nature liquide cristalline, ont également été mis en évidence grâce aux clichés de diffraction X et analyses. Nous avons ensuite utilisé des modèles géométriques récents, pour poser le problème du passage d'une phase à l'autre en termes purement topologiques de transformations de surfaces. Des intermédiaires possibles pour les deux transitions ont été conçus : les surfaces tours pour la transition hexagonale/cubique et les tunnels entre plans pour la transition lamellaire/cubique, expliquant notamment l'apparition de la topologie bicontinue de la phase cubique.

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43

Kern, Brian. "Optical pulse-phased observations of faint pulsars with a phase-binning CCD camera." Diss., Pasadena, Calif. : California Institute of Technology, 2002. http://resolver.caltech.edu/CaltechETD:etd-06042002-125011.

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44

Liu, Kun. "Polymeric Monolithic Stationary Phases for Capillary Reversed-phase Liquid Chromatography of Small Molecules." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3843.

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Highly cross-linked monoliths prepared from single cross-linking monomers were found to increase surface area and stability. Therefore, seven cross-linking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic columns in 75-µm i.d. capillaries by one-step UV-initiated polymerization using dodecanol and methanol as porogens for reversed-phase liquid chromatography (RPLC) of small molecules. Selection of porogen type and concentration was investigated in detail. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. In addition, highly cross-linked monolithic capillary columns poly(1,6-HDDMA), poly(cyclohexanediol dimethacrylate) [poly(CHDDMA)] and poly(1,4-phenylene diacrylate) [poly(PHDA)], were synthesized and compared for RPLC of small molecules. Isocratic elution of alkylbenzenes was performed using 1,6-HDDMA and CHDDMA monolithic columns. Gradient elution of alkylbenzenes using all three monolithic columns showed good separations. Monolithic columns formed from 1,6-HDDMA, which had a linear alkyl-bridging chain structure, exhibited the highest column efficiencies (86,000 plates/m). Optimized columns showed high permeability and high run-to-run and column-to-column reproducibilities. Monoliths prepared from controlled/living polymerization was demonstrated exhibiting narrower molecular weight distribution and more homogeneous cross-linked structures due to the reversible character of this polymerization method. Thus, monolithic columns were developed from three cross-linking monomers, i.e., 1, 12-DoDDMA, trimethylolpropane trimethacrylate (TMPTMA) and pentaerythritol tetraacrylate (PETA) using organotellurium-mediated living radical polymerization (TERP) in 150-Âµm i.d. capillaries for RPLC of small molecules. Selection of the polymerization conditions for the 1,12-DoDDMA monolirh was investigated in detail. Isocratic elution of alkylbenzenes was achieved with good efficiency (47,700 to 64,200 plates/m for uracil) using all monolithic columns prepared using TERP.

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45

Wu, Zhongyu. "Synchronized Phasor Measurement Units Applications in Three-phase Power System." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51660.

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Phasor Measurement Units (PMUs) are widely acknowledged as one of the most significant developments in the field of real-time monitoring of power system. By aligning time stamps of voltage and current phasor measurements, which are consistent with Coordinated Universal Time (UTC), a coherent picture of the power system state can be achieved through either direct measurements or simple linear calculations. With the growing number of PMUs installed or planned to be installed in the near future, both utilities and research institutions are looking for novel applications of synchrophasor measurements from these widely installed PMUs. In this dissertation, the author proposes two new PMUs measurements applications: three-phase instrument transformer calibration, and three-phase line parameter calculation with instrument transformers. First application is to calibrate instrument transformers. Instrument transformers are the main sensors used in power systems. They provide isolation between high voltage level of primary side and metering level of the secondary side. All the monitoring and measuring systems obtain input signals from the secondary side of instrument transformers. That means when instrument transformers are not accurate, all the measurements used in power system are inaccurate. The most important job of this dissertation is to explore a method to automatically calibrate all the instrument transformers in the power system based on real-time synchrophasor measurements. The regular instrument transformer calibration method requires the instrument transformer to be out of service (offline) and calibrated by technicians manually. However, the error of instrument transformer changes when environment changes, and connected burden. Therefore, utilities are supposed to periodically calibrate instrument transformers at least once a year. The high labor and economic costs make traditional instrument transformer calibration method become one of the urgent problems in power industry. In this dissertation we introduce a novel, low cost and easy method to calibrate three-phase instrument transformers. This method only requires one three-phase voltage transformer at one bus calibrated in advance. All other instrument transformers can be calibrated by this method as often as twice a day, based on the synchrophasor measurements under different load scenarios. Second application is to calculate line parameters during calibrating instrument transformers. The line parameters, line impedance and line shunt admittance, as needed by utilities are generated by the computer method. The computer method is based on parameters, such as the diameter, length, material characteristics, the distance among transmission line, the distance to ground and so on. The formulas to calculate line parameters have been improved and re-modeled from time to time in order to increase the accuracy. However, in this case, the line parameters are still inaccurate due to various reasons. The line parameters errors do affect the instrument transformers calibration results (with 5% to 10% error). To solve this problem, we present a new method to calculate line parameters and instrument transformers in the same processing step. This method to calibrate line parameter and instrument transformers at the same time only needs one pre-calibrated voltage transformer and one pre-calibrated current transformer in power system. With the pre-calibrated instrument transformers, the line parameter as well as the ratio correction factors of all the other instrument transformers can be solved automatically. Simulation results showed the errors between calculated line parameters and the real line parameter, the errors between calibrated ratio correction factors and the real ratio correction factors are of the order of 10e-10 per unit. Therefore, high accuracy line parameters as well as perfectly calibrated instrument transformers can be obtained by this new method. This method can run automatically every day. High accuracy and dynamic line parameters will significantly improve power system models. It will also increase the reliability and speed of the relay system, enhance the accuracy of power system analysis, and benefit all other researches using line parameters. New methods of calculating line parameter and the instrument transformer calibrations will influence the whole power industry significantly.
Ph. D.

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46

Martin, Catherine. "Méthodes d'étude des microémulsions et étude de diagrammes pseudoternaires." Paris 5, 1992. http://www.theses.fr/1992PA05P247.

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47

Gloriant, Thierry. "Influence du titane sur les mécanismes de galvanisation d'aciers : les systèmes ternaire Fe-Zn-Ti et quaternaire Fe-Zn-Ti-Ni à 450°C." Lille 1, 1995. http://www.theses.fr/1995LIL10131.

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Le phénomène de Sandelin, se traduisant par une surépaisseur des revêtements lors de galvanisation d'aciers au silicium, s'explique par la réactivité du substrat avec le zinc liquide. Par des expériences de dépôt de zinc en phase vapeur, ce phénomène disparaît. En fait, lors de la réaction entre la vapeur de zinc et le substrat ferreux, le premier compose intermétallique qui se forme peut accepter une plus grande quantité de silicium que le composé qui précipite le premier lors du processus classique de galvanisation. Pour résoudre ces problèmes des surépaisseurs, une solution possible est l'ajout de titane dans le bain de zinc liquide. Pour comprendre les phénomènes liés à la présence du titane, le diagramme de phase ternaire Fe-Zn-Ti à 450°C a été établi par des expériences de diffusion réalisées sur des alliages Fe-Ti. Trois types de couple de diffusion ont été utilisés : solide/solide, solide/liquide et solide/vapeur à pression contrôlée. La réaction solide-liquide donne directement le coin riche en zinc du diagramme en relation avec le processus de galvanisation. Les analyses des différentes phases obtenues dans chaque revêtement conduisent à de nouveaux équilibres dans le système Fe-Zn-Ti à 450°C. Le nickel et le titane jouant un rôle similaire lors de la réaction acier-zinc liquide, une approche du système quaternaire expérimental Fe-Zn-Ti-Ni à 450°C est déterminée par galvanisation d'alliages Fe-Ti, Fe-Ni et Ti-Ni. Le but est d'étudier l'effet conjugué du titane et du nickel sur la formation des mattes en galvanisation.

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48

Ragaru, Christian. "Étude par microscopie électronique en transmission de la transformation de phase bêta-SiC, >alpha-SiC par maclage." Nantes, 1997. http://www.theses.fr/1997NANT2118.

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Le carbure de silicium est un covalent binaire qui possède une forte aptitude au polytypisme. Lors du frittage de nos échantillons, au dessus de 2000c, la transformation de phase beta (cubique-diamant) alpha-sic (polytypes hexagonaux et rhomboédriques), aboutit à la croissance massive de bicristaux de grandes dimensions en forme de fer-de-lance ou de plume. Ces plumes possèdent un axe commun 11-20, et un angle diedral atypique de 65,5, 64 ou 41,4 entre les plans denses (0001). Nous discutons la nucléation et la croissance de ces plumes en nous appuyant sur les caractéristiques microstructurales des phases alpha et beta. Nous avons donc caractérisé des joints de grains et des défauts par methr afin d'expliquer la formation d'un tel bicristal. L'analyse montre que les joints et défauts peuvent s'interpréter en terme d'unités structurales proches de celles des covalents simples (si, ge). Cependant, le caractère ionique et binaire de sic permet d'accommoder des déformations de manière plus variée que pour le silicium. L'étude des plumes montre que la régularité et l'originalité de leurs angles diedraux ne peut s'expliquer par une minimisation des distorsions du joint et donc de l'énergie du matériau. Nous nous sommes bases sur un modèle de transformation de phase par double-glissement dévié de dislocations propose par Pirouz. Ce mécanisme, initialement développé pour le silicium, permet de décrire la formation des plaquettes dans sic. En émettant des hypothèses basées sur la microstructure des phases alpha et beta, nous avons adapté ce modèle et montre qu'il peut rendre compte de la nucléation des plumes. Nous avons ensuite discuté le mécanisme de croissance des plumes.

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49

Barnes, Karen Wink. "The synthesis and characterization of reversed phase stationary phases for high performance liquid chromatography." Gainesville, FL, 1986. http://www.archive.org/details/synthesischaract00barn.

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50

Hermana, Joni. "Enhancing anaerobic digestion by manipulation of acidogenesis-methanogenesis phases during two-phase anaerobic system." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362518.

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Dissertations / Theses on the topic 'PhaseI'

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