Дисертації з теми "Topological waves"
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Krishna, Aditya. "Topological Imaging of Tubular Structures using Ultrasonic guided waves." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0111.
Повний текст джерелаTubular structures are widely used in a variety of industries such as Aerospace, Oil and Gas, Nuclear, etc. Non Destructive Evaluation (NDE) of these structures plays a crucial role during it’s life cycle. In order to test large structures with limited accessibility, guided wave testing was developed as a viable solution. Due to the nature of these waves, they are able to propagate over large distances without losing much of their energy. However, they are also complex in that their velocity is frequency dependent i.e. they are dispersive. Conventionally, guided wave testing require costly finite element simulations. This thesis offers an alternative to such simulations with a quick and robust method to simulate guided wave propagation in tubular structures.Based on these calculations, the aim of this work is to obtain the 3d topological image of multilayered isotropic tubular structures using ultrasonic guided waves to locate defects. A mathematical model has been proposed where the wave equation is converted to an ordinary differential equation with respect to radius 'r' using the Fourier and Laplace transforms for the spatial and temporal variables respectively. The partial wave solution, expressed as a combination of Bessel’s functions, allows for the creation of a fast robust semi-analytical algorithm to compute the Green function in tubular structures. A model to approximate numerical defects is then developed. The defect response is considered as the cumulative response of secondary sources, aiming to negate the incident and diffracted stress field present within it. Next, the numerical model is validated with experimental measurements.Finally, the technique of Topological Imaging is introduced. This method of imaging is based on the idea of performing a correlation between two wave fields for defect localization. The versatility and flexibility of the numerical tool in conjunction with the method of imaging is then successfully demonstrated by localising and imaging a multitude of numerical and experimental defects with dimensions as low as 1=40th of the wavelength
Zheng, Li-Yang. "Granular monolayers : wave dynamics and topological properties." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1035/document.
Повний текст джерелаGranular crystals are spatially periodic structures of elastic particles arranged in crystal lattices. The interactions between particles take place via their elastic interconnections, which are of much smaller dimensions and weights than the beads. This induces propagation of elastic waves in granular structures at significantly slower velocities than in the individual grains. In addition, due to the existence of non-central shear forces, rotations of particles can be initiated, leading to extra phononic modes in the crystals. In the manuscript, wave dynamics in two-dimensional monolayer granular crystals with either out-of-plane or in-plane particle motion is studied. The phononic properties are investigated, including Dirac points, zero-frequency modes, zero-group-velocity modes and their transformation into slow propagating phononic modes. Furthermore, in the presence of edges/boundaries, zero-frequency and extremely slow elastic edge waves can be also predicted in mechanical granular honeycomb crystals (granular graphene). In addition, topological properties of rotational edge waves in a granular graphene are theoretically demonstrated. By inducing topological transition, which turns the topological order of granular graphene from trivial to nontrivial, topological edge transport in the granular graphene can be observed. The developed theories could promote the potential applications of designed granular structures with novel elastic wave propagation properties
Deymier, Pierre, and Keith Runge. "One-Dimensional Mass-Spring Chains Supporting Elastic Waves with Non-Conventional Topology." MDPI AG, 2016. http://hdl.handle.net/10150/615109.
Повний текст джерелаWang, Wei. "Manipulation of Lamb waves with elastic metamaterials." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS414.
Повний текст джерелаWe develop elastic pillared metamaterials to manipulate Lamb waves. Firstly, the negative properties associated with bending, compression and torsion resonances in two structures consisting of pillars on one side of a thin plate are examined. We describe in details two different mechanisms at the origin of doubly negative property. The potential of these structures for negative refraction of Lamb waves and acoustic cloaking is demonstrated numerically. Secondly, we present the topologically protected transport of Lamb waves by analogy with quantum spin and valley quantum Hall effects. By rearranging the previous structures into a honeycomb network, a single Dirac cone and a double Dirac cone are introduced. We discuss the appearance of topologically valley-protected edge states in an asymmetrical double-sided pillar structure. The unidirectional propagation of edge states on different domain walls is studied. In addition, we consider a symmetrical double-sided system allowing the separation of the symmetric and antisymmetric modes. Combined edge states protected topologically by pseudospin and pseudospin-valley degree of freedom are demonstrated. Third, we propose an approach to actively control the transmission of the antisymmetric Lamb wave propagating through an infinite line of pillars. Two different situations with bending and compression resonances respectively separated or superimposed are studied. External tensile force and pressure are applied to the pillars, which allows them to couple with the bending and compressive vibrations. The transmission is studied as a function of the amplitude and the relative phase of the external sources
Dennis, Mark Richard. "Topological singularities in wave fields." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391183.
Повний текст джерелаHafidi, Alaoui Hamza. "Imagerie topologique ultrasonore des milieux périodiques." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0388/document.
Повний текст джерелаThe detection, localization and monitoring of the evolution of defects in periodic media and waveguides is a major issue in the field of Non-Destructive Testing (NDT). Wave propagation in such media is complex, for example when the velocity depends on the frequency (dispersion) or direction of propagation (anisotropy). The signature of the defect can also be "embedded" in the acoustic field reflected by the structure (reverberation or multiple diffusion). It is to answer these stakes of the size that the Topological Optimization (TO) has been adapted to the problems of diffraction of the acoustic waves by infinitesimal defects in order to obtain reflectivity images of the inspected media. The method can be applied to all kinds of media, regardless of their complexity, provided an exact simulation of the wave propagation in a reference medium (without defects) is performed. Inspired by the TO, the work of this thesis proposes to implement qualitative imaging methods adapted to the specificities of Phononic Crystals (PC) and waveguides. First, we focus on the description of the mathematical formalism of Topological Optimization and Full-Waveform Inversion (FWI). Although these methods do not try to solve the same inverse problems, we highlight their similarities. In a second step, we apply Topological Imaging (TI) to the inspection in pulse-echo configuration of weakly heterogeneous media. Thirdly, we draw inspiration from TI to define a new variant of this method called Hybrid Topological Imaging (HTI).We apply these methods for the pulse-echo configuration inspection of PCs created by steel rods immersed in water.We compare the performance of these methods according to the kind of defects in the PC. Numerical simulations for some case studies are supported by conclusive experimental trials. In a fourth step, we adapt the TI to a pitch-catch configuration in order to implement a new method of Structural Health Monitoring (SHM) of waveguides. In this regard, we have developed a new imaging method that is better suited than TI to pitch-catch configurations
Larocque, Hugo. "Generation and Characterization of Topologically Structured Waves." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37857.
Повний текст джерелаBungey, Timothy N. "Topological configurations of coronal magnetic fields and current sheets." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/14021.
Повний текст джерелаRieder, Maria-Theresa [Verfasser]. "On Topological Phases in Disordered P-wave Superconducting Wires / Maria-Theresa Rieder." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1076038816/34.
Повний текст джерелаSaputo, Roberto. "Two dimensional P-wave superconductors with long range interactions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16315/.
Повний текст джерелаChen, Mengsu. "Exact diagonalization study of strongly correlated topological quantum states." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/87436.
Повний текст джерелаPHD
Topological quantum states are a new type of quantum state that have properties that cannot be described by local order parameters. These types of states were first discovered in the 1980s with the integer quantum Hall effect and the fractional quantum Hall effect. In the 2000s, the predicted and experimentally discovered topological insulators triggered studies of new topological quantum states. Studies of strongly correlated systems have been a parallel research topic in condensed matter physics. When combining topological systems with strong correlation, the resulting systems can have novel properties that emerge, such as fractional charge. This thesis summarizes our work that uses the exact diagonalization method to study topological states with strong interaction.
Pereira, Erms Rodrigues. "Física dos cristais líquidos e gravitação : pontos de encontro." Universidade Federal da Paraíba, 2011. http://tede.biblioteca.ufpb.br:8080/handle/tede/9546.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Aspects of the physics of nematic liquid crystals are studied in this thesis from the viewpoint of riemannian geometry through analogue models of gravitation. The topics chosen for study were: geometric and wave optics, elastic waves, hydrodynamics and heat conduction. The main analogue model used is based on the interpretation of Fermat’s principle as a process to obtain null geodesics, where the liquid crystalline material is seen as a riemannian manifold. This approach predicts that the metric effectively felt by the light ray depends on the configuration of molecules in the liquid crystal and on the parallel and perpendicular refractive indexes to the axis of symmetry of the liquid-cristal molecule. It is known that, for the particular case of the existence of topological defects within the material, effective metric similar to cosmological defects (like global monopoles and cosmic strings) are obtained. This thesis develops itself on the situation where there are topological defects of hedgehog type and (k = 1, c = 0) disclination type in the nematic phase of the liquid crystalline material. The first problem studied, as a review, deals with the wave optics, with respect to the light diffracted by the cited defects. Since plane waves of small wavelength have identical trajectories to light rays, the use of analog model is therefore justified. Thus, we show that light scattered by these defects generates a characteristic diffraction pattern, being the location given by an algebraic expression dependent on the parallel and perpendicular refractive indexes to the axis of symmetry of the molecule. We also show how theses patterns depend on the temperature of the material. The second studied problem deals with the geometrical optics and hydrodynamics of the nematic liquid crystals. From a molecular configuration similar to a (k = 1, c = 0) disclination, we let the material flow radially towards the axis of the defect. Then, using the hydrodynamic fact that velocity gradients in the material locally change the refractive index of the molecule, we find the velocity profile that must exist around the defect so that the metric actually experienced by light traveling in the plane perpendicular to the axis the defect is the Schwarzschild one in the equatorial plane, with the Schwarzschild radius interior to the object. We found that the absolute values of the velocity of liquid crystalline fluid can be order of a few meters per second, differing greatly from the values obtained by Gordon metric for an isotropic fluid under identical conditions. The third studied problem deals with the elastic oscillations in the presence of topological defects. Similarly to the first problem, the trajectory of the sound is obtained by an elastic version of Fermat’s principle and, then, compared with a null geodesic. We show how topological defects influence the sound trajectories and the sound diffracted by them. The fourth problem deals with the heat conduction in the vicinity of defects. Considering that the defects come from an addition or removal of portion of the material, letting the medium relaxes elastically, effective metric of the space disturbed by the defect are found, with expressions similar to those obtained by the analogous model based on Fermat’s principle. These metrics generate a modified thermal conductivity tensor, allowing the study of the temperature field in this situation. We show that, depending on the values of parallel and perpendicular thermal conductivity to the axis of symmetry of the molecule and on the defect in question, the temperature gradient can be accentuated or attenuated on the defect, allowing control of the response thermal temperature of the material, according to the presence of defects. Encouraging a greater understanding of the physics of liquid crystals and its use as a background in analogue models of gravity is the main theme of each analyzed problem.
Aspectos da física dos cristais líquidos nemáticos são estudados nesta tese do ponto de vista da geometria riemannina, por meio de modelos análogos de gravitação. Os tópicos escolhidos para estudo foram: óptica geométrica e ondulatória, ondas elásticas, hidrodinâmica e condução de calor. O principal modelo análogo empregado baseia-se na interpretação do princípio de Fermat como um processo de obtenção de geodésicas nulas, onde o material líquido-cristalino é visto como sendo uma variedade riemanniana. Esta abordagem prevê que a métrica efetivamente sentida pelo raio luminoso dependa da configuração das moléculas dentro do cristal líquido e dos índices de refração paralelo e perpendicular ao eixo de simetria da molécula líquido-cristalina. É sabido que, para o caso especial da existência de defeitos topológicos dentro do material, métricas efetivas semelhantes às de defeitos cosmológicos (como monopolos globais e cordas cósmicas) são obtidas. Esta tese desenrola-se sobre a situação onde existem defeitos topológicos do tipo ouriço e do tipo desclinação (k = 1, c = 0) na fase nemática do material líquido-cristalino. O primeiro problema estudado, em caráter de revisão, trata da óptica ondulatória, no que concerne a difração de luz pelos defeitos citados. Uma vez que ondas planas de comprimento de onda pequeno possuem trajetórias idênticas aos raios luminosos, o emprego do modelo análogo é justificado. Assim, mostramos que a luz espalhada por esses defeitos gera padrões de difração bem característicos, sendo a localização dada por expressão algébrica dependente dos índices de refração paralelo e perpendicular ao eixo de simetria da molécula líquido-cristalina. Também mostramos de que forma esses padrões dependem da temperatura do material. O segundo problema estudado trata da óptica geométrica e da hidrodinâmica dos cristais líquidos nemáticos. A partir de uma configuração de moléculas semelhantes à de uma desclinação (k = 1, c = 0), permitimos que o material flua radialmente na direção do eixo do defeito. Em seguida, fazendo uso do fato hidrodinâmico de que gradientes de velocidade no material modificam localmente os índices de refração da molécula, encontramos o perfil de velocidade que deve existir em torno do defeito para que a métrica efetivamente sentida pela luz, que viaja no plano perpendicular ao eixo do defeito, seja a de Schwarzschild no plano equatorial, com raio de Schwarzschild interior ao objeto. Encontramos que os valores absolutos da velocidade de fluido líquido-cristalino podem ser da ordem de alguns metros por segundo, diferindo enormemente dos valores obtidos pela métrica de Gordon para um fluido isotrópico em condições idênticas. O terceiro problema estudado aborda as oscilações elásticas na presença de defeitos. Semelhantemente ao primeiro problema, a trajetória do som é obtida por uma versão elástica do princípio de Fermat e, então, comparada com uma geodésica nula. Mostramos como defeitos topológicos influenciam nas trajetórias sonoras, assim como no som difratado por eles. O quarto problema trata da condução de calor na vizinhança de defeitos. Considerando que os defeitos são resultantes de uma adição ou remoção de porção de material, dando-se seguimento a uma relaxação elástica do meio, métricas efetivas do espaço perturbado pelo defeito são encontradas, com expressões semelhantes às obtidas pelo modelo análogo baseado no princípio de Fermat. Essas métricas geram um tensor condutividade térmica modificado, dando cabo ao estudo do campo de temperatura nessa situação. Mostramos que, dependendo dos valores da condutividade térmica perpendicular e paralela ao eixo de simetria da molécula líquido-cristalina e do defeito em questão, o gradiente de temperatura pode ser acentuado ou atenuado sobre o defeito, permitindo o controle da resposta térmica do material à temperatura, de acordo com a presença de defeitos. Suscitar um entendimento maior da física dos cristais líquidos e de seu emprego como background em modelos análogos de gravitação é o tema principal de cada um dos problemas analisados.
Cruz, Francisco Marks da. "Simulador didático de ondas viajantes para diferentes topologias de sistemas de potência." Programa de Pós-graduação em Sistemas de Comunicação e Automação, 2017. http://bdtd.ufersa.edu.br:80/tede/handle/tede/741.
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The model of education in the last decades has undergone considerable changes from a didactic point of view. With the advancement of technology, the speed of obtaining information increases and the use of tools that allow the dynamic visualization of content becomes a strong ally to the teaching-learning process. This work deals with the creation of an interactive tool to visualize the propagation of traveling waves in an electric power system, with the possibility of insertion of data by the user, in order to facilitate the consolidation of knowledge. The model was created from the GUIDE of Matlab R, which has a graphical interface with the possibility of inserting data into a single screen with action buttons, which when clicked performs actions like calculate and display the animated graphic. It is important to highlight that the creation of the program, besides facilitating the student's understanding, due to the animation, also allow a better familiarization with computer simulation software, and with the parameters used in the transient analysis in transmission lines
O modelo de educação nas últimas décadas vem sofrendo alterações consideráveis do ponto de vista didático. Com o avanço da tecnologia, a velocidade da obtenção de informações aumenta e a utilização de ferramentas que possibilitem a visualização dinâmica do conteúdo se faz um forte aliado ao processo ensino-aprendizado. Esse trabalho aborda a criação de uma ferramenta interativa para a visualização da propagação de ondas viajantes em um sistema elétrico de potência, com a possibilidade de inserção de dados por parte do usuário, afi m de facilitar a consolidação do conhecimento. O modelo foi criado a partir do GUIDE do Matlab R, que possui uma interface gráfica com a possibilidade de inserção de dados em uma única tela com botões de ação, que ao serem clicados realizam ações como calcular e mostrar o gráfi co animado. É importante destacar que a criação do programa além de facilitar a compreensão por parte do aluno, devido à animação, também possibilita uma maior familiarização com softwares de simulação computacional, e com os parâmetros utilizados na análise do transitório em linhas de transmissão
2017-06-28
Krückl, Viktor [Verfasser], and Klaus [Akademischer Betreuer] Richter. "Wave packets in mesoscopic systems: From time-dependent dynamics to transport phenomena in graphene and topological insulators / Viktor Krückl. Betreuer: Klaus Richter." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1034198378/34.
Повний текст джерелаSouza, Adelcio Marques de. "Topologias WDM-PON utilizando auto-alimentação com dupla cavidade óptica para Fronthaul analógico de redes 5G." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-04122018-111631/.
Повний текст джерелаFuture radio access networks, such as the fifth generation mobile network (5G), are introducing and consolidating disruptive technologies, such as millimeter wave operation, dense picocell coverage and massive use of antennas for spatial and temporal diversity. These new technologies present a challenge for the capacity of the links that are present on these networks, including backhaul and fronthaul. In the latest cellular network generations, the fronthaul was typically implemented by Digital Radio-over-Fiber (D-RoF) technique. However, in this future context, the digitalization process would require a prohibitive bandwidth and the analog transmission of RF signals over the fiber can be a more attractive solution when compared to D-RoF. At the same time, Wavelength-Division-Multiplexing PON (WDM-PON) is prominent alternative for the future of PONs, especially considering its use as fronthaul. In order to avoid employing numerous distinct transmitters, several self-seeding techniques have been proposed to achieve colorless optical sources. This dissertation presents a numerical study of double-cavity self-seeding topologies to serve as analog fronthaul for future radio access networks. Numerical simulations using the software Optisystem demonstrate the feasibility of these topologies in various scenarios envisioned for these access networks, especially considering operation in millimeter waves. Successful transmission was achieved for ASK, M-PSK and M-QAM signals at microwave (1.25, 2.5 and 5 GHz) and millimeter wave (38 and 60 GHz) frequencies with throughput of 155 Mbps to 10 Gbps using direct and external modulation.
Batista, Edson Anibal de Macedo Reis. "Estudo da topologia de redes de conex?o funcional no c?rtex sensorial prim?rio e hipocampo durante o sono de ondas lentas." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15492.
Повний текст джерелаCoordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Complex network analysis is a powerful tool into research of complex systems like brain networks. This work aims to describe the topological changes in neural functional connectivity networks of neocortex and hippocampus during slow-wave sleep (SWS) in animals submited to a novel experience exposure. Slow-wave sleep is an important sleep stage where occurs reverberations of electrical activities patterns of wakeness, playing a fundamental role in memory consolidation. Although its importance there s a lack of studies that characterize the topological dynamical of functional connectivity networks during that sleep stage. There s no studies that describe the topological modifications that novel exposure leads to this networks. We have observed that several topological properties have been modified after novel exposure and this modification remains for a long time. Major part of this changes in topological properties by novel exposure are related to fault tolerance
A an?lise da topologia de redes ? uma poderosa ferramenta no estudo de sistemas complexos tal como as redes cerebrais. Este trabalho procura descrever as mudan?as na topologia de redes de conex?o funcional em neur?nios do c?rtex sensorial e do hipocampo durante o sono de ondas lentas (SWS) em animais expostos ? novidade. O sono de ondas lentas ? um importante estado do sono onde h? reverbera??o de padr?es de atividade el?trica ocorridos na vig?lia, tendo com isso papel fundamental na consolida??o de mem?ria. Apesar de sua import?ncia ainda n?o h? estudos que caracterizam a din?mica da topologia de redes de conex?o funcional durante este estado. Tampouco h? estudos que descrevem as modifica??es topol?gicas que a exposi??o ? novidade traz a essas redes. Observamos que v?rias propriedades topol?gicas s?o modificadas ap?s a exposi??o ? novidade e que tais modifica??es se mant?m por um longo per?odo de tempo. A maior parte das propriedades modificadas pela exposi??o ? novidade est? relacionada ? toler?ncia ? falha
Paula, Marcos Barros de. "Invariantes de frentes de ondas planas." Universidade Federal de Viçosa, 2010. http://locus.ufv.br/handle/123456789/4905.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
This dissertation is devoted to the study of wave planar fronts following the work developed by Aicardi in [Ai1]. She finds theses invariantsas a generalization of those introduced by Arnold for plane curves by using the Vassiliev Theory. In this work, we study and describe Aicardi's invariants as well as their properties. Moreover, by using the notions of bridges and chanel given in [MJ-RF] we obtain an alternative algorithm for the calculation os such invariants.
Esta dissertação é dedicada ao estudo dos invariantes de frentes de ondas planas seguindo o trabalho desenvolvido por F. Aicardi em [Ai1]. Ela encontra estes invariantes fazendo uma generalização dos invariantes de curvas planas introduzidos por Arnold utilizando a teoria de Vassiliev. Neste trabalho estudamos e descrevemos os invariantes de Aicardi, assim como suas propriedades. Além disso, utilizando as nações de pontes e canais de curvas dado em [MJ-RJ] apresentamos um algoritmo alternativo para o cálculo de tais invariantes.
Patier, Laurent. "Etude de techniques de calculs multi-domaines appliqués à la compatibilité électromagnétique." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00834164.
Повний текст джерелаLeriche, Raphaël. "Unconventional superconductivity in quasi-2D materials with strong spin-orbit coupling." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS577.
Повний текст джерелаThe realization of topological superconductors is one of the main current goals of condensed matter physics. It was indeed predicted that such systems should host Majorana fermions. These Majorana fermions possess both a non-Abelian statistics and, because of their topological origin, a certain robustness against local disorder, which makes them attractive for quantum computing applications. One approach likely to lead to topological superconductivity consists in considering superconducting systems with strong spin-orbit coupling and with broken inversion symmetry. It is in this framework that, during this thesis, I performed scanning tunneling microscopy and spectroscopy measurements on quasi-2D materials : (LaSe)1,14(NbSe2)2 and Sr2IrO4. I first studied the electronic properties of misfit compound LaNb2Se5, which is a parent of transition metal dichalcogenide 2H-NbSe2. (LaSe)1,14(NbSe2)2 is a heterostructure made out of alternations of NbSe2 bilayers with trigonal prismatic geometry and LaSe bilayers with rocksalt structure. (LaSe)1,14(NbSe2)2 is a potential candidate for topological superconductivity because of the presence of both a strong spin-orbit coupling and of broken inversion symmetry in NbSe2 planes. Here, I present spectroscopic results showing that the electronic structure of(LaSe)1,14(NbSe2)2 is very similar to the one of electron-doped monolayer NbSe2 with a shift of the chemical potential of 0,3 eV, priorly never reached. I could also demonstrate the quasi- 2D nature of (LaSe)1,14(NbSe2)2 and more particularly the presence of a strong Ising spinorbit coupling. Moreover, the observed weakness of superconductivity against non-magnetic disorder combined with quasiparticle interferences measurements allowed me to exhibit the unconventional nature of (LaSe)1,14(NbSe2)2 superconducting order parameter. This study opens the possibility to use misfit heterostructures such as (LaSe)1,14(NbSe2)2 to study thephysics of transition metal dichalcogenides in the 2D limit, for which many theoretical studies predict topological superconductivity. In this thesis, I also present a study on the effects of doping on the electronic properties of iridate compound Sr2IrO4. Sr2IrO4 is a spin-orbit induced Mott insulator. Because inversion symmetry is locally broken in Sr2IrO4, some theoretical predictions suggest that Sr2IrO4 should turn into a topological superconductor once doped. Here, I exhibit a nanometer-scaleinhomogeneous doping-driven Mott insulator to pseudo-metallic phase transition. This work further justifies the importance of using a local probe such as scanning tunnelling microscopy in order to complete results on Mott physics obtained by integrative methods like angle-resolved photoemission spectroscopy
Ting-YangLee and 李廷洋. "Topological Valley Edge States of Elastic Waves in Triangular Lattice Phononic Crystals." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e4w9mv.
Повний текст джерела國立成功大學
機械工程學系
107
In the present study, a two-dimensional phononic crystal with quantum valley Hall effect is proposed to exhibit the topologically protected edge mode in elastic wave, which only occurs at the interface between two topologically inequivalent phononic crystals. The unit cell of the topologically phononic crystal is composed of the scattering pillars embedded in the middle of the beam, and the Dirac point at the K-point in the irreducible Brillouin zone is investigated. Also, two topological inequivalent phononic crystals are obtained by breaking the spatial inversion symmetry of the primitive cell, and then study the edge mode at the interface by the supercell method and the full-wave simulation by the finite element analysis software COMSOL Multiphysics®. The robustness of edge mode for limiting the backscattering and defect immunity is perfectly verified. Our study may offer a brand new application in high-efficiency waveguide and energy harvesting devices.
Chun-TeChang and 張俊德. "Topological valley edge states of elastic waves in the plate with periodic stubs." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dzg7k4.
Повний текст джерела"Self-consistent study of Abelian and non-Abelian order in a two-dimensional topological superconductor." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-12-2398.
Повний текст джерелаDeb, Oindrila. "Studies of Topological Phases of Matter : Presence of Boundary Modes and their Role in Electrical Transport." Thesis, 2017. http://etd.iisc.ernet.in/2005/3571.
Повний текст джерелаVogelgesang, Simon. "Ultrafast low-energy electron diffraction at surfaces." Doctoral thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E5A1-F.
Повний текст джерела