Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(Wave Triads). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


University of Oxford

1. Marshall, Samuel David. Sloping convection : an experimental investigation in a baroclinic annulus with topography.

Degree: PhD, 2014, University of Oxford

This thesis documents a collection of experimental investigations in which a differentially-heated annulus was used to investigate the effects of topography on the atmospheric and oceanic circulation. To this end a number of experiments were devised, each using a different topographic base to study a different aspect of the impact of topography, motivated by the most notable outstanding questions found in a review of the literature, namely exploring the effects of topographic resonance, blocking via partial barriers, and azimuthally differential-heating via thermal topography. First of all, whilst employing sinusoidal wavenumber-3 topography to extend the experimental parameter space of a similar study, namely Read and Risch (2011), a new regime within a region of structural vacillation was encountered. Denoted as the ‘stationary-transition’ regime, it featured periodic oscillations between a dominant stationary wavenumber-3 flow and axisymmetric or chaotic flow. An investigation into topographic resonance followed, keeping the wavenumber-3 base, but with a sloped lid to add a beta effect to the annulus. This acted to increase the occurrence of stationary waves, along with the ‘stationary-transition’ regime, which was discovered to be a near-resonant region where nonlinear topographic resonant instability led to a 23 to 42 ‘day’ oscillatory structure. The base was then replaced with an isolated ridge, forming a partial barrier to study the difference between blocked and unblocked flow. The topography was found to impact the circulation at a level much higher than its own peak, causing a unique flow structure when the drifting flow and the topography interacted in the form of an ‘interference’ regime at low Taylor Numbers, as well as forming an erratic ‘irregular’ regime at higher Taylor Numbers. Lastly, this isolated ridge was replaced by flat heating elements covering the same azimuthal extent, in order to observe whether thermal topography could be comparable to mechanical topography. These azimuthally-varying heating experiments produced much the same results as the partial barriers study, despite the lack of a physical peak or bottom-trapped waves, suggesting that blocking is independent of these activities. Evidence of resonant wave-triads was noted in all experiments, though the component wavenumbers of the wave-triads and their impact on the flow was found to depend on the topography in question.

Subjects/Keywords: 551.46; Atmospheric,Oceanic,and Planetary physics; Topography; Baroclinic; Annulus; Atmospheric Circulation; Oceanic Circulation; Resonance; Blocking; Thermal; Walker Circulation; Low Frequency Variability; Wave-Triads; Intraseasonal Oscillations.

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Marshall, S. D. (2014). Sloping convection : an experimental investigation in a baroclinic annulus with topography. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:ca9cfaf5-49e8-4e30-b93a-65c27d1c8a15 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629565

Chicago Manual of Style (16th Edition):

Marshall, Samuel David. “Sloping convection : an experimental investigation in a baroclinic annulus with topography.” 2014. Doctoral Dissertation, University of Oxford. Accessed May 26, 2019. http://ora.ox.ac.uk/objects/uuid:ca9cfaf5-49e8-4e30-b93a-65c27d1c8a15 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629565.

MLA Handbook (7th Edition):

Marshall, Samuel David. “Sloping convection : an experimental investigation in a baroclinic annulus with topography.” 2014. Web. 26 May 2019.

Vancouver:

Marshall SD. Sloping convection : an experimental investigation in a baroclinic annulus with topography. [Internet] [Doctoral dissertation]. University of Oxford; 2014. [cited 2019 May 26]. Available from: http://ora.ox.ac.uk/objects/uuid:ca9cfaf5-49e8-4e30-b93a-65c27d1c8a15 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629565.

Council of Science Editors:

Marshall SD. Sloping convection : an experimental investigation in a baroclinic annulus with topography. [Doctoral Dissertation]. University of Oxford; 2014. Available from: http://ora.ox.ac.uk/objects/uuid:ca9cfaf5-49e8-4e30-b93a-65c27d1c8a15 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629565


University of Waterloo

2. Hu, Youna. The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models.

Degree: 2007, University of Waterloo

This thesis investigates the effects of the earth's rotation on internal waves from two perspectives of nonlinear internal wave theory: near-resonant triads and weakly nonlinear models. We apply perturbation theory (multiple scale analysis) to the governing equations of internal waves and develop a near-resonant internal wave triad theory. This theory explains a resonant-like phenomenon in the numerical results obtained from simulating internal waves generated by tide topography interaction. Furthermore, we find that the inclusion of the earth's rotation (nonzero f) in the numerical runs leads to a very special type of resonance: parametric subharmonic instability. Through using perturbation expansion to solve separable solutions to the governing equations of internal waves, we derive a new rotation modified KdV equation (RMKdV). Of particular interest, the dispersion relation of the new equation obeys the exact dispersion relation for internal waves for both small and moderate wavenumbers (k). Thus this new RMKdV is able to model wea kly nonlinear internal waves with various wavenumbers (k), better than the Ostrovsky equation which fails at describing waves of small k.

Subjects/Keywords: Near-resonant Internal Wave Triads; Weakly Nonlinear Models of Internal Waves

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hu, Y. (2007). The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/3180

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hu, Youna. “The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models.” 2007. Thesis, University of Waterloo. Accessed May 26, 2019. http://hdl.handle.net/10012/3180.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hu, Youna. “The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models.” 2007. Web. 26 May 2019.

Vancouver:

Hu Y. The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models. [Internet] [Thesis]. University of Waterloo; 2007. [cited 2019 May 26]. Available from: http://hdl.handle.net/10012/3180.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hu Y. The Effects of the Earth's Rotation on Internal Wave Near-resonant Triads and Weakly Nonlinear Models. [Thesis]. University of Waterloo; 2007. Available from: http://hdl.handle.net/10012/3180

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Waterloo

3. Mohebbi, Hamid Reza. Parametric Interaction in Josephson Junction Circuits and Transmission Lines.

Degree: 2011, University of Waterloo

This research investigates the realization of parametric amplification in superconducting circuits and structures where nonlinearity is provided by Josephson junction (JJ) elements. We aim to develop a systematic analysis over JJ-based devices toward design of novel traveling-wave Josephson parametric amplifiers (TW-JPA). Chapters of this thesis fall into three categories: lumped JPA, superconducting periodic structures and discrete Josephson transmission lines (DJTL). The unbiased Josephson junction (JJ) is a nonlinear element suitable for parametric amplification through a four-photon process. Two circuit topologies are introduced to capture the unique property of the JJ in order to efficiently mix signal, pump and idler signals for the purpose of signal amplification. Closed-form expressions are derived for gain characteristics, bandwidth determination, noise properties and impedance for this kind of parametric power amplifier. The concept of negative resistance in the gain formulation is observed. A design process is also introduced to find the regimes of operation for gain achievement. Two regimes of operation, oscillation and amplification, are highlighted and distinguished in the result section. Optimization of the circuits to enhance the bandwidth is also carried out. Moving toward TW-JPA, the second part is devoted to modelling the linear wave propagation in a periodic superconducting structure. We derive closed-form equations for dispersion and s-parameters of infinite and finite periodic structures, respectively. Band gap formation is highlighted and its potential applications in the design of passive filters and resonators are discussed. The superconducting structures are fabricated using YBCO and measured, illustrating a good correlation with the numerical results. A novel superconducting Transmission Line (TL), which is periodically loaded by Josephson junctions (JJ) and assisted by open stubs, is proposed as a platform to realize a traveling-wave parametric device. Using the TL model, this structure is modeled by a system of nonlinear partial differential equations (PDE) with a driving source and mixed-boundary conditions at the input and output terminals, respectively. This model successfully emulates parametric and nonlinear microwave propagation when long-wave approximation is applicable. The influence of dispersion to sustain three non-degenerate phased-locked waves through the TL is highlighted. A rigorous and robust Finite Difference Time Domain (FDTD) solver based on the explicit Lax-Wendroff and implicit Crank-Nicolson schemes has been developed to investigate the device responses under various excitations. Linearization of the wave equation, under small-amplitude assumption, dispersion and impedance analysis is performed to explore more aspects of the device for the purpose of efficient design of a traveling-wave parametric amplifier. Knowing all microwave characteristics and identifying different regimes of operation, which include impedance properties, cut-off propagation, dispersive…

Subjects/Keywords: Parametric Amplifier; Josephson Junction; Superconducting Device; Traveling-wave Josephson Parametric Amplifier; Discrete Josephson Transmission Line; Finite Difference Time Domain; Spectral Methods; Coupled Wave Equations; Periodic Transmission Line; Superconducting Transmission Line; Dispersion Engineering; Shock Wave; Up/Down Conversion; Three-wave Mixing; Resonant Triads; Phase Matching Condition; Ultra-low Noise Amplifier; Floquet Theorem; Perturbation Thechnique; Multiple Scale Method

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Mohebbi, H. R. (2011). Parametric Interaction in Josephson Junction Circuits and Transmission Lines. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/5973

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Mohebbi, Hamid Reza. “Parametric Interaction in Josephson Junction Circuits and Transmission Lines.” 2011. Thesis, University of Waterloo. Accessed May 26, 2019. http://hdl.handle.net/10012/5973.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Mohebbi, Hamid Reza. “Parametric Interaction in Josephson Junction Circuits and Transmission Lines.” 2011. Web. 26 May 2019.

Vancouver:

Mohebbi HR. Parametric Interaction in Josephson Junction Circuits and Transmission Lines. [Internet] [Thesis]. University of Waterloo; 2011. [cited 2019 May 26]. Available from: http://hdl.handle.net/10012/5973.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mohebbi HR. Parametric Interaction in Josephson Junction Circuits and Transmission Lines. [Thesis]. University of Waterloo; 2011. Available from: http://hdl.handle.net/10012/5973

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.