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You searched for +publisher:"University of Oklahoma" +contributor:("Ruyle, Jessica"). Showing records 1 – 3 of 3 total matches.

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University of Oklahoma

1. Bhowmik, Lal Mohan. Applications of Floquet Analysis to Modern Phased Array Antennas.

Degree: PhD, 2019, University of Oklahoma

Next generation radar technology is based on phased array technology and provides remarkable scanning flexibility and spatial search capability for the multifunction weather and air surveillance radar systems. The future weather radar is comprised of thousands of antenna elements and requires strict polarization purity, grating lobe free system, low sidelobe levels, suppressed surface waves, low cross-polarization, with beam shape requirements. To address these demands is a serious challenge. Over the past few decades, phased array radar technology has been a tremendous advancement in search for future radar technology. With the blessing of modern computational electromagnetic tools, the theory behind the electromagnetic and circuit-level behavior of large-scale phased array system opened the door to analyze the wide variety of multi-layered, complex system of large arrays. However, numerous challenges still remained unsolved for large scale development. One such challenge in integrating a large phased array is the threat of grating lobes that are introduced by unavoidable disturbances to the periodic structure at the seams between mechanical sub-array modules. In particular, gaps in the ground plane may interrupt the natural currents between elements, leading to radiation from periodic sources that are spaced at regular distances that are typically many wavelengths apart. In order to quantify these grating lobe effects, an appropriate analysis framework and accurate model are of utmost importance. The model must capture all surface wave and mutual coupling between elements, and the analysis must have a clear formulation that allows for the calculation of worst-case grating lobe levels as well as differences in active reflection as a function of location within a sub-array. To accurately predict those effects, this dissertation work applied a modern method called Floquet framework, coupling with full wave solver to explore the grating lobe effects in infinite arrays of sub-arrays, with each physical sub-array potentially separated from the others by a gap or discontinuity in the ground plane. Calculations are then performed to extract active reflection coefficients and grating lobe levels from the resulting Floquet mode scattering parameters. Additionally, this Floquet framework is expanded from broadside to any scan angles in space. In the mathematical framework, the surface equivalence theorem based on Huygens’s equivalence principle is applied to authenticate its findings. From the simulation results, it is evident that the grating lobe amplitude level emerged to around 30 dB in the E-plane scan and E- plane grating lobes for a patch array. This is due to natural current disruption in between sub-arrays in the ground plane gap and it is very strong in the E-plane, leading to the potential for low-level grating lobe effects. The other planes and scan angles show less significant effects. It was found that the measurements qualitatively follow the simulated results. The Floquet-based method may therefore be used… Advisors/Committee Members: Fulton, Caleb (advisor), Remling, Christian (committee member), Bluestein, Howard (committee member), Goodman, Nathan (committee member), Sigmarsson, Hjalti (committee member), Ruyle, Jessica (committee member).

Subjects/Keywords: Scan blindness; Creeping waves; Cylindrical Electromagnetic Bandgap (EBG) structures; Floquet analysis; Grating lobe; MPAR; CPPAR; Phased array

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

APA (6th Edition):

Bhowmik, L. M. (2019). Applications of Floquet Analysis to Modern Phased Array Antennas. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/321405

Chicago Manual of Style (16th Edition):

Bhowmik, Lal Mohan. “Applications of Floquet Analysis to Modern Phased Array Antennas.” 2019. Doctoral Dissertation, University of Oklahoma. Accessed February 27, 2021. http://hdl.handle.net/11244/321405.

MLA Handbook (7th Edition):

Bhowmik, Lal Mohan. “Applications of Floquet Analysis to Modern Phased Array Antennas.” 2019. Web. 27 Feb 2021.

Vancouver:

Bhowmik LM. Applications of Floquet Analysis to Modern Phased Array Antennas. [Internet] [Doctoral dissertation]. University of Oklahoma; 2019. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/11244/321405.

Council of Science Editors:

Bhowmik LM. Applications of Floquet Analysis to Modern Phased Array Antennas. [Doctoral Dissertation]. University of Oklahoma; 2019. Available from: http://hdl.handle.net/11244/321405


University of Oklahoma

2. Winniford, Paul. Reconfigurable and multiband antennas with resonant and reactive loads.

Degree: PhD, 2020, University of Oklahoma

Reactive and resonant loads have been used from the very beginning of antenna design to improve impedance matching, bandwidth, and current distributions on antennas, and to create multiband and reconfigurable antennas.Trap loaded dipoles are one of the simplest resonator-loaded antennas and are traditionally loaded with either an inductor-capacitor pair or a quarter wavelength stub integrated into a dipole or monopole to create a second operating frequency at the trap resonant frequency. Adding resonant loads to antennas will only increase in popularity and practicality as filtennas are more often used for their SWaP improvements, better noise performance, and potential for additional degrees of reconfigurability. In this dissertation, I demonstrate that resonant loads can introduce lossy modes, and I significantly revise and expand the theory of the basic trap dipole antenna, which is a valuable aid in designing resonator loaded antennas with higher degrees of complexity. Based on the new analysis, I demonstrate novel series LC trap dipoles, dual-band inductor loaded trap dipoles, and parallel and series LC trap slots. The newly developed design process also allows for the integration of any kind of resonator or reactive load to be used to create trap style antennas. A reconfigurable load is also used to demonstrate novel tunable trap antennas. The design procedure is ultimately adaptable to any resonators that can be practically fabricated and physically incorporated into the antenna structure. Advisors/Committee Members: Ruyle, Jessica (advisor), Sigmarsson, Hjalti (committee member), Goodman, Nathan (committee member), Fulton, Caleb (committee member), Kornelson, Keri (committee member).

Subjects/Keywords: Antennas; Reconfigurable Antennas; Multifrequency Antennas; Loaded Antennas

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

APA (6th Edition):

Winniford, P. (2020). Reconfigurable and multiband antennas with resonant and reactive loads. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/326683

Chicago Manual of Style (16th Edition):

Winniford, Paul. “Reconfigurable and multiband antennas with resonant and reactive loads.” 2020. Doctoral Dissertation, University of Oklahoma. Accessed February 27, 2021. http://hdl.handle.net/11244/326683.

MLA Handbook (7th Edition):

Winniford, Paul. “Reconfigurable and multiband antennas with resonant and reactive loads.” 2020. Web. 27 Feb 2021.

Vancouver:

Winniford P. Reconfigurable and multiband antennas with resonant and reactive loads. [Internet] [Doctoral dissertation]. University of Oklahoma; 2020. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/11244/326683.

Council of Science Editors:

Winniford P. Reconfigurable and multiband antennas with resonant and reactive loads. [Doctoral Dissertation]. University of Oklahoma; 2020. Available from: http://hdl.handle.net/11244/326683


University of Oklahoma

3. Wang, Huiyu. Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes.

Degree: PhD, 2020, University of Oklahoma

Electromagnetic-based energy harvesting materials and devices have emerged as a prominent research area in the last ten years, especially systems using ferrofluidic induction—a process that generates voltage via the pulsation of a ferrofluid (iron-based nanofluid) through a solenoid. This work includes the development of an analytical model and computational modeling methods to investigate ferrofluid pulsating flow within an energy harvesting device and the mass and heat transfer performance of a two-phase closed thermosyphon (TPCT) and oscillating heat pipe (OHP). First, an analytical model is proposed to predict the induced electromotive force (EMF) based on the flow behavior and magnetic properties of a pulsating ferrofluid energy harvesting device. The model identifies key parameters for describing and optimizing induction for ferrofluid pulsing through a solenoid. Data from a previously documented experimental study was used to validate the analytical model, and both the experimental data and analytical model show the same trends with the induced EMF increasing as a function of pulsating frequency and magnetic field strength as a higher percentage of the ferrofluid nanoparticle moments are aligned. Second, computational fluid dynamics (CFD) simulations were performed to predict the heat transfer performance of a TPCT. Simulations were performed using a three-dimensional finite-volume flow solver (ANSYS Fluent) with a pressure-based scheme for the solution of the continuity and momentum equations, volume-of-fluid method for resolution of the liquid-vapor phase interface, and a temperature-dependent model for interphase mass transfer by evaporation and condensation. Different model and numerical scheme combinations were investigated to identify an efficient and consistently accurate method using currently available software tools. To address issues with previously published simulation methods violating the conservation of mass, a new variable saturation temperature model was tested along with mass transfer coefficients based on the vapor-liquid density ratio and more physically realistic boundary conditions. The variable saturation temperature model significantly mitigated mass and energy imbalance in the simulations, for both constant heat flux and convection condenser boundary conditions. In addition, for the VOF discretization the Geo-Reconstruct scheme was found to be more accurate than the Compressive scheme available in Fluent without additional computational cost. Third, simulations of a vertical OHP were performed using the CFD methodology developed for the TPCT system. Results show simulations using appropriate values for the evaporation and condensation mass transfer time relaxation parameters and the new variable saturation temperature model are in good agreement with the available experimental data. For the OHP system, using the Compressive discretization scheme for the VOF model allowed for computationally efficient simulation. It is believed that the advances in analytical and computational modeling… Advisors/Committee Members: Walters, D. Keith (advisor), Walters, Keisha B. (advisor), Ruyle, Jessica E. (committee member), Shabgard, Hamidreza (committee member), Vedula, Prakash (committee member), Garg, Jivtesh (committee member).

Subjects/Keywords: Heat Transfer; Computational fluid dynamics (CFD); Electrodynamic energy harvesting

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

APA (6th Edition):

Wang, H. (2020). Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/324967

Chicago Manual of Style (16th Edition):

Wang, Huiyu. “Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes.” 2020. Doctoral Dissertation, University of Oklahoma. Accessed February 27, 2021. http://hdl.handle.net/11244/324967.

MLA Handbook (7th Edition):

Wang, Huiyu. “Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes.” 2020. Web. 27 Feb 2021.

Vancouver:

Wang H. Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes. [Internet] [Doctoral dissertation]. University of Oklahoma; 2020. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/11244/324967.

Council of Science Editors:

Wang H. Analytical and computational modeling of multiphase flow in ferrofluid charged oscillating heat pipes. [Doctoral Dissertation]. University of Oklahoma; 2020. Available from: http://hdl.handle.net/11244/324967

.