Global ETD Search

1	Theoretical Investigation on Propagation and Coupling of Nonreciprocal Electromagnetic Surface Waves Liu, Kexin January 2016 (has links) This thesis aims at revealing the fundamental guiding and coupling properties of nonreciprocal electromagnetic surface waves on magneto-optical or gyromagnetic media and designing novel applications based on the properties. We introduce the background in the first chapter. We then describe the concept of nonreciprocity and the main calculation method in the second chapter. In the third chapter, we show that one-way waves can be sustained at the edge of a gyromagnetic photonic crystal slab under an external magnetic field. We also investigate the coupling between two parallel one-way waveguides. We reveal the condition for effective co-directional and contra-directional coupling. We also notice that the contra-directional coupling is related to the concept of a “trapped rainbow”. In the fourth chapter, we address the concept of a “trapped rainbow”. It aims at trapping different frequency components of the electromagnetic wave packet at different positions in space permanently. In previous structures, the entire incident wave is reflected due to the strong contra-directional coupling between forward and backward modes. To overcome this difficulty, we show that utilizing nonreciprocal waveguides under a tapered external magnetic field can achieve a truly “trapped rainbow” effect at microwave frequencies. We observe hot spots and relatively long duration times around critical positions through simulations and find that such a trapping effect is robust against disorders. Lastly, in the fifth chapter, we study the one-way waves in a surface magnetoplasmon cavity. We find that the external magnetic field can separate the clockwise and anti-clockwise cavity modes into two totally different frequency ranges. This offers us more choices, both in the frequency ranges and in the one-way directions, for realizing one-way components. We also show the waveguide-cavity coupling by designing a circulator, which establishes the foundation for potential applications. / <p>QC 20160816</p><p></p> wave propagation coupling magneto-optical gyromagnetic photonic crystal nonreciprocity one-way trapped rainbow
2	Nuclear orientation of odd-A nuclei near to '1'3'2SN White, Gareth Nicholas January 1999 (has links) No description available. 539.7
3	A measurement of trilinear gauge couplings using the DELPHI detector Parzefall, Ulrich January 1999 (has links) No description available. 539.72
4	Out-of-plane Ferromagnetic Resonance (FMR) measurements on magnetic nanoparticle dispersions for biomedical sensor applications Back, Markus January 2020 (has links) In this master work, we investigated the feasibility of a magnetic resonance measurement technique using magnetic nanoparticle dispersions in both liquid and solid form. The implementation is realised as a coplanar waveguide operating in the frequency range of 0.5 - 20 GHz and an electromagnet producing a static magnetic field of strength up to 1.2 T. The Gilbert magnetic damping factor is determined for polymer composites of magnetic nanoparticles and the gyromagnetic ratio is determined for both nanoparticle dispersions in liquid form and polymer composites. Ferromagnetic magnetic resonance FMR EPR nanoparticle microwave coplanar waveguide cavity s-parameter gilbert damping gyromagnetic liquid biosensor landau lifshits spin polymer composites engineering physics teknisk fysik magnetism ferromagnetisk vågledare resonans mikrovågsteknik nanopartiklar Condensed Matter Physics Den kondenserade materiens fysik
5	The Ratio of Reality : A study of the gyromagnetic ratio in theories ranging from classical mechanics to string theory Nilsson, Daniel January 2021 (has links) In this project a theoretical study of the so called gyromagnetic ratio was done by investigating classical mechanics, Dirac theory and string theory. The gyromagnetic ratio is a constant term appearing in the coupling between angular momentum and magnetic moment for a particle. A universality in quantum field theory claiming g = 2 regardless of spin is known to exist which also agrees with the found values (g = 2) of the Dirac and string theory. The proof of the aforementioned universality in quantum field theory was sketched in the project by showing that the W-boson Lagrangian is well behaved in the massless limit. Furthermore it is shown that the spin equations of motion for a particle is greatly reduced if g = 2 regardless of spin. / I det här projektet utfördes en teoretisk studie av den så kallade gyromagnetsika kvoten genom att undersöka klassisk mekanik, Dirac-teori och strängteori. Den gyromagnetiska kvoten är en konstant term som visar sig i kopplingen mellan rörelsemängsmoment och magnetiskt moment för en partikel. I kvantfältsteori existerar en universalitet som hävdar att g = 2 oberoende av spin. Denna universalitet stämmer överens med de funna värden på g från Dirac-teori och strängtoeri. Beviset för denna universalitet testades genom ett exempel där Lagrangianen för W-bosonen i kvantfältsteori visades bete sig som förväntat när massan för partikeln tilläts gå mot noll. Vidare undersöktes rörelseekvationerna för ett system helt bestämt av dess spin. I dessa kan det visas att ett universellt värde på g oavsett spin reducerar dessa ekvationer avsevärt. "Quantum field theory" "String theory" "Dirac equation" "Dirac theory" Dirac gyromagnetic ratio g-factor Kvantfältsteori strängteori Dirac g-factor "gyrmagnetisk kvot" Other Physics Topics Annan fysik

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