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Full-Text Articles in Physical Sciences and Mathematics

Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack Dec 2017

Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack

Theses and Dissertations

Using a finite element method, we numerically solve the time-dependent Ginzburg-Landau equations of superconductivity to explore vortex nucleation in type II superconductors. We consider a cylindrical geometry and simulate the transition from a superconducting state to a mixed state. Using saddle-node bifurcation theory we evaluate the superheating field for a cylinder. We explore how surface roughness and thermal fluctuations influence vortex nucleation. This allows us to simulate material inhomogeneities that may lead to instabilities in superconducting resonant frequency cavities used in particle accelerators.


Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack Dec 2017

Computational Exploration Of Vortex Nucleation In Type Ii Superconductors Using A Finite Element Method In Ginzburg-Landau Theory, Alden Roy Pack

Theses and Dissertations

Using a finite element method, we numerically solve the time-dependent Ginzburg-Landau equations of superconductivity to explore vortex nucleation in type II superconductors. We consider a cylindrical geometry and simulate the transition from a superconducting state to a mixed state. Using saddle-node bifurcation theory we evaluate the superheating field for a cylinder. We explore how surface roughness and thermal fluctuations influence vortex nucleation. This allows us to simulate material inhomogeneities that may lead to instabilities in superconducting resonant frequency cavities used in particle accelerators.


Finite Element Method Analysis Of Resonant Cavity For Whispering Gallery Acoustic Sensing Microscopy, Thanh N.D. Le, Ha Tran, Andres H. La Rosa May 2017

Finite Element Method Analysis Of Resonant Cavity For Whispering Gallery Acoustic Sensing Microscopy, Thanh N.D. Le, Ha Tran, Andres H. La Rosa

Student Research Symposium

Whispering Gallery Acoustic Sensing (WGAS) has been studied by Department of Physics at Portland State University as a mean of controlling sample to probe distance in tuning-folk-based scanning probe microscopy (TF-SPM). WGAS uses the microscope frame as a resonance acoustic cavity. The setup shows high potential because of high-quality factor nature of acoustic cavity as well as using mechanical motions of the TF itself instead of electrical signals. However, the analytic solution of the eigenfrequencies of the current microscope frame is very complex due to the asymmetric geometry. The purpose of this study is to use finite element method to …


Some Remarks On Interpolation And Best Approximation, Randolph E. Bank, Jeffrey S. Ovall Mar 2017

Some Remarks On Interpolation And Best Approximation, Randolph E. Bank, Jeffrey S. Ovall

Mathematics and Statistics Faculty Publications and Presentations

Sufficient conditions are provided for establishing equivalence between best approximation error and projection/interpolation error in finite-dimensional vector spaces for general (semi)norms. The results are applied to several standard finite element spaces, modes of interpolation and (semi)norms, and a numerical study of the dependence on polynomial degree of constants appearing in our estimates is provided.


A Spectral Element Method For The Solution Of Magnetostatic Fields, Ibrahim Mahariq, Atakan Erciyas Jan 2017

A Spectral Element Method For The Solution Of Magnetostatic Fields, Ibrahim Mahariq, Atakan Erciyas

Turkish Journal of Electrical Engineering and Computer Sciences

Recently, we have seen good progress in our capability to simulate complex electromagnetic systems. However, still there exist many challenges that have to be tackled in order to push limits restricting the field of computational electromagnetics upward. One of these challenges is the limitations in the available computational resources. Over several decades, the traditional computational methods, such as finite difference, finite element, and finite volume methods, have been extensively applied in the field of electromagnetics. On the other hand, the spectral element method (SEM) has been recently utilized in some branches of electromagnetics as waveguides and photonic structures for the …


Optimum Design And Operation Analysis Of Permanent Magnet-Assisted Synchronous Reluctance Motor, Jamal Dehghani Ashkezari, Hassan Khajeroshanaee, Mohsen Niasati, Mohammad Jafar Mojibian Jan 2017

Optimum Design And Operation Analysis Of Permanent Magnet-Assisted Synchronous Reluctance Motor, Jamal Dehghani Ashkezari, Hassan Khajeroshanaee, Mohsen Niasati, Mohammad Jafar Mojibian

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an optimum design process and operational analysis of a permanent magnet-assisted synchronous reluctance motor (PMASynRM) as a low-cost and highly efficient consumed magnet material machine. The motor's topology is based on inserting partial permanent magnetic materials into flux barriers of an original synchronous reluctance motor (SynRM) that implicitly increase the difference between the machine's inductances, thereby increasing output torque. The procedure of rotor design as the main contribution of this paper is carefully illustrated. The rectangular shape of the flux barriers was found to achieve cost reduction and improve productivity. The impact of the permanent magnet added …