Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 414 for “"symmetries"”.
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Two-Component Link Symmetries
A mathematical knot is a closed curve in a three-dimensional space that does not intersect itself, while a link is two or more such curves that do not intersect each other. We consider the ``intrinsic'' symmetry group of a two-component link L which records directly whether L is isotopic to a link …
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Symmetries of trellis codes
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
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Symmetries in algebraic Property Testing
Modern computational tasks often involve large amounts of data, and efficiency is a very desirable feature of such algorithms. Local algorithms are especially attractive, since they can imply global properties by only inspecting a small window into the data. In Property Testing, a local algorithm …
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New symmetries from old: exploiting lie algebra structure to determine infinitesimal symmetries of differential equations
We give a method for using explicitly known Lie symmetries of a system of differential equations to help find more symmetries of the system. A Lie (or infinitesimal) symmetry of a system of differential equations is a transformation of its dependent and independent variables, depending on …
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Thresholds and Symmetries in Propositional Formulas
Two problems with application to the analysis and design of algorithms concerning the satisfiability of propositional formulas are investigated. With respect to the first problem, there is great experimental evidence for a phenomenon known as the 'phase transition' of satisfiability, that is there …
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Multipole Symmetries and Many Body Physics
This thesis studies the many body physics of systems with multipolar conservation laws --- systems which conserve both a total charge and various multipole moments thereof. These conservation laws place constraints on the way in which particles can move, and carry important ramifications for both …
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Conformal symmetries in special and general relativity.The derivation and interpretation of conformal symmetries and asymptotic conformal symmetries in Minkowski space-time and in some space-times of general relativity.
The central objective of this work is to present an analysis of the asymptotic conformal Killing vectors in asymptotically-flat space-times of general relativity. This problem has been examined by two different methods; in Chapter 5 the asymptotic expansion technique originated by Newman and Unti …
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Symmetries of Wave Equations of Statistical Optics
… to find conservation laws of the wave equations. Symmetries and conservation laws of the wave equations of scalar statistical optics and vector statistical optics are studied and compared to the symmetries and conservation laws of the wave equations of deterministic wave optics. Generalizations of …
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Higher-order topological phases with crystalline symmetries
… in HOTIs are usually protected by crystalline symmetries. In this dissertation, we systematically study the charge fractionalization in 2D HOTIs under rotation symmetries. We find that, under the Cn rotation symmetries, the electronic charge fractionalizes in units of 1/n at corners and bulk …
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Geometric aspects of gauge and spacetime symmetries
… in relativity and particle physics where symmetries play a central role; in all cases geometric properties of Lie groups and their quotients are related to physical effects. The first part is concerned with symmetries in gravity. We apply the theory of Lie group deformations to isometry …
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Aspects of higher degree forms with symmetries
In Chapter One we develop a basis for studying higher degree alternating forms. The concepts and results we present are mostly obvious analogues of Harrison's treatment of higher degree symmetric forms. We explain antisymmetrization; discuss the derivative of an alternating form and its …
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Combinatorial models for surface and free group symmetries
The curve complex of Harvey allows combinatorial representation of a surface mapping class group by describing its action on simple closed curves. Similar complexes of spheres, free factors, and free splittings allow combinatorial representation of the automorphisms of a free group. We consider a …
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Taming Biological Complexity Through the Use of Symmetries
… work is to present methods, through the use of symmetries, to address the complexity of these systems. In concrete, through the use of graph fibrations, which allow us to identify sets of nodes with isomorphic input history, called fibers, we develop tools that allow us to do a systematic and …
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Quantum Trajectories: Metastability, Gauge Freedom and Weak Symmetries
This thesis considers quantum systems which interact with their surrounding environment. Specifically we consider the underlying stochastic dynamics which arise from the back-action of measurements performed in the environment. These quantum trajectories can be tracked by continuously monitoring …
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Approach to equilibrium in systems with continuous symmetries
In this thesis, we consider the approach to equilibrium of quenched systems with continuous symmetry, whose relaxational dynamics is dominated by topological defects. The general aspects of the problem are discussed in chapter 1. In chapters 2 and 3, we report the results of two and three …
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Approach to equilibrium in systems with continuous symmetries
In this thesis, I consider the approach to equilibrium of quenched systems with continuous symmetry, whose relaxational dynamics is dominated by topological defects. The general aspects of the problem and relevant theoretical, numerical and experimental results from the literature are discussed in …
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Quantum Matter in the Era of Generalized Symmetries
The discovery of generalized symmetries has led to powerful new insights into quantum matter. They have been used to classify new families of quantum phases, place constraints on phases realizable in a given physical system, and conceptually unify seemingly disparate phenomena. In many ways, they …
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Gauge symmetries and charged matter in F-theory
F-theory has emerged as a powerful tool for string compactification, as it can realize a number of string vacua with varying gauge groups, charged matter, and other properties. However, some aspects of F-theory are still not completely understood, particularly those involving charged matter. There …
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Infinite Dimensional Symmetries of Self-Dual Yang-Mills Theories.
We construct infinite dimensional symmetries of the Chalmers-Siegel action describing the self-dual sector of non-supersymmetric Yang-Mills. The symmetries are derived by virtue of a canonical transformation between the Yang-Mills fields and new fields that map the Chalmers-Siegel action to a free …
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