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University of Alberta
1.
Martinez, Roberto Carlos.
Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.
Degree: MS, Department of Mechanical Engineering, 2012, University of Alberta
URL: https://era.library.ualberta.ca/files/vx021g61s 
► A recent in vitro study demonstrated a non invasive method to enhance local deposition in a small airway by controlling the angular position of magnetic…
(more)
▼ A recent in vitro study demonstrated a non invasive
method to enhance local deposition in a small airway by controlling
the angular position of magnetic high aspect ratio particles. This
technique could mitigate the challenge of providing sufficient
therapeutic effects when using aerosolized chemotherapy techniques.
To highlight the potential of this new magnetic field alignment
approach the effect of increasing particle aspect ratio on the
deposition efficiency was studied using direct numerical
simulations. Simulations were done using an in house finite element
algorithm. A steady air flow, typical of tidal breathing, was
simulated through a three dimensional physiologically realistic
bifurcation representing a single symmetrical bifurcation between
generations 14 and 15 in the lung. For two different aspect ratios
the deposition efficiency was found for the case of an
unconstrained particle and magnetically aligned particle. Results
indicate that forcing local alignment of high aspect ratio
particles can increase local deposition considerably.
Subjects/Keywords: Aerosols; Numerical Method; Deposition; Targeting
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APA (6th Edition):
Martinez, R. C. (2012). Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. (Masters Thesis). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/vx021g61s
Chicago Manual of Style (16th Edition):
Martinez, Roberto Carlos. “Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.” 2012. Masters Thesis, University of Alberta. Accessed September 23, 2019.
https://era.library.ualberta.ca/files/vx021g61s.
MLA Handbook (7th Edition):
Martinez, Roberto Carlos. “Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations.” 2012. Web. 23 Sep 2019.
Vancouver:
Martinez RC. Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. [Internet] [Masters thesis]. University of Alberta; 2012. [cited 2019 Sep 23].
Available from: https://era.library.ualberta.ca/files/vx021g61s.
Council of Science Editors:
Martinez RC. Study of Enhanced Deposition due to Magnetic Field Alignment
of Ellipsoid Particles Using Direct Numerical Simulations. [Masters Thesis]. University of Alberta; 2012. Available from: https://era.library.ualberta.ca/files/vx021g61s
Texas A&M University
2.
Leung, Wing Tat.
Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.
Degree: PhD, Mathematics, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/165860
► Many problems in application involve media with multiple scale, for example, in composite materials, porous media. These problems are usually computationally challenging since fine grid…
(more)
▼ Many problems in application involve media with multiple scale, for example, in composite materials, porous media. These problems are usually computationally challenging since fine grid computation is extremely expensive. Therefore, one may need to develop a coarse grid model reduction for this type of problems. In this dissertation, we will consider a multiscale
method called generalized multiscale finite element
method (GMsFEM).
GMsFEM follows the framework of multiscale finite element
method. Instead of using one basis function per coarse grid node, GMsFEM uses several basis functions for one coarse grid node. Since the media is highly heterogeneous and may involves high contrast, having more than one basis function per node is important to reduce the error significantly. Due to the varying heterogeneity in the domain, we may require different numbers of basis functions in different regions. Then the question is how to determine the number of basis functions in each region. In this dissertation, we will discuss an adaptive enrichment algorithm for enriching basis functions for the regions with large error. We will consider two different types of basis function for enrichment. One is using the pre-computed offline basis functions. We call this
method offline adaptive enrichment. The other
method uses online constructed basis functions called online adaptive enrichment.
In applications, non-conforming basis functions can give us more flexibility on gridding. The discontinuous Galerkin
method also makes the mass matrix block diagonal, which enhances the computation speed in solving time-dependent problem with an explicit scheme. In this dissertation, we will discuss offline and online adaptive methods for the generalized multiscale discontinuous Galerkin
method (GMsDGM). We will also discuss using GMsDGM for simulating wave propagation in heterogeneous media.
Advisors/Committee Members: Efendeiv, Yalchin (advisor), Chung, Eric (advisor), Gildin, Eduardo (committee member), Howard, Peter (committee member), Lazarov, Raytcho (committee member).
Subjects/Keywords: Multiscale Method; Numerical Analysis
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APA (6th Edition):
Leung, W. T. (2017). Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/165860
Chicago Manual of Style (16th Edition):
Leung, Wing Tat. “Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.” 2017. Doctoral Dissertation, Texas A&M University. Accessed September 23, 2019.
http://hdl.handle.net/1969.1/165860.
MLA Handbook (7th Edition):
Leung, Wing Tat. “Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods.” 2017. Web. 23 Sep 2019.
Vancouver:
Leung WT. Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/1969.1/165860.
Council of Science Editors:
Leung WT. Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/165860
Texas A&M University
3.
Jiang, Han.
Experimental and Numerical Study of Polymer Scratch Behavior.
Degree: 2010, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-844
► As part of a larger effort to understand the fundamental knowledge of polymer scratch behavior, this dissertation is focused on both experimental study and numerical…
(more)
▼ As part of a larger effort to understand the fundamental knowledge of polymer scratch behavior, this dissertation is focused on both experimental study and
numerical analysis of scratch deformation of a broad range of polymers, with an emphasis on the mechanical understanding of how the scratch-induced damage is formed. An instrumented progressive load scratch
method recommended by ASTM/ISO standards was adopted for the experimental work. The commercial finite element (FE)
method package ABAQUS was employed as a
numerical simulation tool to describe the stress-strain fields, and it analyzes the deformation mechanisms during the scratch process. A thorough parametric study has been performed to assess the influence of material parameters and surface properties, such as Young's modulus, yield strength, and friction coefficient, on the polymer scratch behavior.
Upon investigation of the scratch behaviors of a broad range of polymer materials, various kinds of scratch damage features are identified and correlated with the mechanical characteristics of the polymers. A generalized scratch damage mechanism map for polymers is presented. Correlation between different material types and scratch damage mechanisms is made. It is found that both the material characteristics and the stress state exerted on the scratched surface are responsible for the observed scratch damage mechanisms. The phenomenological deduction of the scratch damage process based on the stick-slip mechanism is established. A more realistic material law for the scratch analysis is also provided.
To evaluate the polymer resistance against scratch visibility quantitatively, an entirely new automated on-set scratch visibility determination methodology is developed based on typical visual characteristics of human eyes. Its application on the evaluation of mar and abrasion of polymer is also explored. This new methodology can quantify polymer scratch resistance consistently and reliably regardless of the sample surface characteristics and color.
Advisors/Committee Members: Sue, Hung-Jue (advisor), Whitcomb, John D. (committee member), Schwartz, Cris (committee member), Suh, Steve (committee member).
Subjects/Keywords: Polymer; Scratch; Numerical Simulation; Finite Element Method
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APA (6th Edition):
Jiang, H. (2010). Experimental and Numerical Study of Polymer Scratch Behavior. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-844
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):
Jiang, Han. “Experimental and Numerical Study of Polymer Scratch Behavior.” 2010. Thesis, Texas A&M University. Accessed September 23, 2019.
http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-844.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Jiang, Han. “Experimental and Numerical Study of Polymer Scratch Behavior.” 2010. Web. 23 Sep 2019.
Vancouver:
Jiang H. Experimental and Numerical Study of Polymer Scratch Behavior. [Internet] [Thesis]. Texas A&M University; 2010. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-844.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Jiang H. Experimental and Numerical Study of Polymer Scratch Behavior. [Thesis]. Texas A&M University; 2010. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-844
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Iowa State University
4.
Tong, Lin.
Pricing mortgages with default and prepayment.
Degree: 2009, Iowa State University
URL: https://lib.dr.iastate.edu/etd/10320
► This thesis develops a model to price the fixed-rate mortgage with default and prepayment as derivative assets, generally termed the option-pricing approach to mortgage valuation.…
(more)
▼ This thesis develops a model to price the fixed-rate mortgage with
default and prepayment as derivative assets, generally termed the
option-pricing approach to mortgage valuation. The problem is
considered in a stochastic environment when the house price follows
a log-normal diffusion process. A highly accurate numerical scheme
is presented to solve the partial differential equation of the value
of the mortgage. In order to simplify the method, the interest rate
is considered to be a constant within each month. Further, a
discount factor is graded to make the model more suitable to current
economic situation.
Subjects/Keywords: Default; Mortgages; Numerical Method; Option; Prepayment; Mathematics
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APA (6th Edition):
Tong, L. (2009). Pricing mortgages with default and prepayment. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/10320
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):
Tong, Lin. “Pricing mortgages with default and prepayment.” 2009. Thesis, Iowa State University. Accessed September 23, 2019.
https://lib.dr.iastate.edu/etd/10320.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Tong, Lin. “Pricing mortgages with default and prepayment.” 2009. Web. 23 Sep 2019.
Vancouver:
Tong L. Pricing mortgages with default and prepayment. [Internet] [Thesis]. Iowa State University; 2009. [cited 2019 Sep 23].
Available from: https://lib.dr.iastate.edu/etd/10320.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Tong L. Pricing mortgages with default and prepayment. [Thesis]. Iowa State University; 2009. Available from: https://lib.dr.iastate.edu/etd/10320
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Rice University
5.
Ye, Ruichao.
Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth.
Degree: PhD, Natural Sciences, 2018, Rice University
URL: http://hdl.handle.net/1911/105670
► We present a novel method to simulate the propagation of seismic waves in realistic fluid-solid materials, coupled with dynamically evolving faults, in the self-gravitating prestressed…
(more)
▼ We present a novel
method to simulate the propagation of seismic waves in realistic fluid-solid materials, coupled with dynamically evolving faults, in the self-gravitating prestressed Earth. A discontinuous Galerkin
method is introduced, with a modified penalty
numerical flux dealing with various boundary conditions, in particular with discontinuities. This
numerical scheme allows general heterogeneity and anisotropy in the materials, by avoiding the diagonalization into polarized wave constituents such as in the approach based on solving elementwise Riemann problems, while maintains the
numerical accuracy with mesh and polynomial refinements. We also include the interior slip boundary conditions for dynamic ruptures coupling with nonlinear friction laws, as an approach to simulate spontaneously cracking faults. We show the well-posedness for the system of particle motion coupled with gravitation field and its perturbation, by proving the coercivity of the bilinear operator, both in the continuous and discretized polynomial space, and therefore the convergence results. A multi-rate iterative scheme is proposed to address the challenging of solving the large implicit nonlinear system, and to allow different time steps for distinct physical processes in the overall coupling problem. We give rigorous proof for the well-posedness of mathematical model and moreover the stability of the
numerical methods.
Numerical experiments show the convergence as well as robustness in both well-established benchmark examples and realistic simulations.
Advisors/Committee Members: de Hoop, Maarten V (advisor).
Subjects/Keywords: seismic wave; numerical method; discontinuous galerkin
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ye, R. (2018). Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth. (Doctoral Dissertation). Rice University. Retrieved from http://hdl.handle.net/1911/105670
Chicago Manual of Style (16th Edition):
Ye, Ruichao. “Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth.” 2018. Doctoral Dissertation, Rice University. Accessed September 23, 2019.
http://hdl.handle.net/1911/105670.
MLA Handbook (7th Edition):
Ye, Ruichao. “Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth.” 2018. Web. 23 Sep 2019.
Vancouver:
Ye R. Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth. [Internet] [Doctoral dissertation]. Rice University; 2018. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/1911/105670.
Council of Science Editors:
Ye R. Discontinuous Galerkin method with a modified penalty flux for the modeling of acousto-elastic waves, coupled to rupture dynamics, in a self gravitating Earth. [Doctoral Dissertation]. Rice University; 2018. Available from: http://hdl.handle.net/1911/105670
Queens University
6.
Bespalko, Dustin John.
Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.
Degree: Mechanical and Materials Engineering, 2011, Queens University
URL: http://hdl.handle.net/1974/6729
► In this work, the lattice Boltzmann method (LBM) was validated for direct numerical simulation (DNS) of wall-bounded turbulent flows. The LBM is a discrete-particle-based method…
(more)
▼ In this work, the lattice Boltzmann method (LBM) was validated for direct numerical simulation (DNS) of wall-bounded turbulent flows. The LBM is a discrete-particle-based method that numerically solves the Boltzmann equation as opposed to conventional DNS methods that are based on the Navier-Stokes (NS) equations. The advantages of the LBM are its simple implementation, its ability to handle complex geometries, and its scalability on modern high-performance computers.
An LBM code was developed and used to simulate fully-developed turbulent channel flow. In order to validate the results, the turbulence statistics were compared to those calculated from a conventional NS-based finite difference (FD) simulation. In the present study, special care was taken to make sure the computational domains for LBM and FD simulations were the same. Similar validation studies in the literature have used LBM simulations with smaller computational domains in order to reduce the computational cost. However, reducing the size of the computational domain affects the turbulence statistics and confounds the results of the validation.
The turbulence statistics calculated from the LBM and FD simulations were found to agree qualitatively; however, there were several significant deviations, particularly in the variance profiles. The largest discrepancy was in the variance of the pressure fluctuations, which differed by approximately 7%. Given that both the LBM and FD simulations resolved the full range of turbulent scales and no models were used, this error was deemed to be significant.
The cause of the discrepancy in the pressure variance was found to be the compressibility of the LBM. The LBM allows the density to vary, while the FD method does not since it solves the incompressible form of the NS equations. The effect of the compressibility could be reduced by lowering the Mach number, but this would come at the cost of significantly increasing the computational cost. Therefore, the conclusion of this work is that, while the LBM is capable of producing accurate solutions for incompressible turbulent flows, it is significantly more expensive than conventional methods for simple wall-bounded turbulent flows.
Subjects/Keywords: Lattice Boltzmann Method;
Direct Numerical Simulation;
Turbulence
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APA (6th Edition):
Bespalko, D. J. (2011). Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/6729
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):
Bespalko, Dustin John. “Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.” 2011. Thesis, Queens University. Accessed September 23, 2019.
http://hdl.handle.net/1974/6729.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bespalko, Dustin John. “Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
.” 2011. Web. 23 Sep 2019.
Vancouver:
Bespalko DJ. Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. [Internet] [Thesis]. Queens University; 2011. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/1974/6729.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bespalko DJ. Validation of the Lattice Boltzmann Method for Direct Numerical Simulation of Wall-Bounded Turbulent Flows
. [Thesis]. Queens University; 2011. Available from: http://hdl.handle.net/1974/6729
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Western Australia
7.
Qu, Xiaolei.
Development of an explicit numerical manifold method for dynamic stability analysis of rock slope.
Degree: PhD, 2013, University of Western Australia
URL: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=40207&local_base=GEN01-INS01
► In this thesis, an explicit version of the numerical manifold method (NMM) has been developed for dynamic stability analysis of rock slope. Firstly, Newmark integration…
(more)
▼ In this thesis, an explicit version of the numerical manifold method (NMM) has been developed for dynamic stability analysis of rock slope. Firstly, Newmark integration scheme used in the NMM is brief introduced and derived in detail to further deepen understanding of the NMM and its implementations. The numerical results present the explicit scheme is more efficient in solving the nonlinear dynamic systems and such problems compared to implicit scheme. Then, an explicit time integration scheme for the NMM is proposed to improve the computational efficiency. The developed explicit NMM (ENMM) is validated by several examples. The calibration study of the ENMM on P-wave propagation across a rock bar has been conducted. Various considerations in the numerical simulations are discussed and parametric studies have been carried out to obtain an insight into the influencing factors in wave propagation simulation. The numerical results from the ENMM and NMM modelling are accordant well with the theoretical solutions, but the ENMM is more efficient than the original NMM. The temporal and spatial coupled explicit-implicit (E-I) algorithms for the numerical manifold method (NMM) are proposed. The time integration schemes, transfer algorithm, contact algorithm and damping algorithm are studied in the temporal coupled E-I algorithm to merge both merits of the explicit and implicit algorithms in terms of efficiency and accuracy. In particular, onefold cover system is drawn into the coupled spatial E-I algorithm, in which the contact algorithm based on the onefold cover system is discussed and derived in detail. The simulated results are well agreement with the implicit and explicit algorithms simulations, but the efficiency is improved evidently. The dynamic stability analysis of rock slope failure using the NMM is studied. Conservational pseudo-static methods (PSMs), Newmark method and numerical methods applying into the seismic stability analyses are investigated, the advantages and limitations of which are studied by contrast of the NMM. An alternative ENMM and coupled E-I algorithms are applied to study the seismic stability of rock slope. Furthermore, parallel computing with OpenMP is evaluated to improve efficiency of the NMM. To reveal the validity and applicability of the developed ENMM, some numerical examples of rock slope stability analysis are investigated, in which one example of rock slope is taken into account to present the coupled ENMM with discontinuous deformation analysis (DDA) in terms of efficiency. Simulated results of the NMM will compare with the field measurements to illustrate the applicability of the NMM. The present study showed the developed ENMM is more efficient while without losing the accuracy, comparing to the original implicit version of the NMM. Therefore, it can be predicted that the proposed ENMM is promising and can be extend applied to larger scale project of rock slope with dynamic stability analysis.
In this thesis, an explicit version of the numerical manifold method (NMM) has…
Subjects/Keywords: Numerical manifold method; Explicit numerical manifold method; Dynamic stability; Rock slope; Computational efficiency; Computational accuracy
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APA ·
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MLA ·
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Manager
APA (6th Edition):
Qu, X. (2013). Development of an explicit numerical manifold method for dynamic stability analysis of rock slope. (Doctoral Dissertation). University of Western Australia. Retrieved from http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=40207&local_base=GEN01-INS01
Chicago Manual of Style (16th Edition):
Qu, Xiaolei. “Development of an explicit numerical manifold method for dynamic stability analysis of rock slope.” 2013. Doctoral Dissertation, University of Western Australia. Accessed September 23, 2019.
http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=40207&local_base=GEN01-INS01.
MLA Handbook (7th Edition):
Qu, Xiaolei. “Development of an explicit numerical manifold method for dynamic stability analysis of rock slope.” 2013. Web. 23 Sep 2019.
Vancouver:
Qu X. Development of an explicit numerical manifold method for dynamic stability analysis of rock slope. [Internet] [Doctoral dissertation]. University of Western Australia; 2013. [cited 2019 Sep 23].
Available from: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=40207&local_base=GEN01-INS01.
Council of Science Editors:
Qu X. Development of an explicit numerical manifold method for dynamic stability analysis of rock slope. [Doctoral Dissertation]. University of Western Australia; 2013. Available from: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=40207&local_base=GEN01-INS01
University of Hong Kong
8.
尤耀辉; You, Yaohui.
Automatic mesh generation of heterogeneous objects for
finite element analysis.
Degree: PhD, 2015, University of Hong Kong
URL: You,
Y.
[尤耀辉].
(2015).
Automatic
mesh
generation
of
heterogeneous
objects
for
finite
element
analysis.
(Thesis).
University
of
Hong
Kong,
Pokfulam,
Hong
Kong
SAR.
Retrieved
from
http://dx.doi.org/10.5353/th_b5689288
;
http://dx.doi.org/10.5353/th_b5689288
;
http://hdl.handle.net/10722/222398
► Adaptive meshing of 2D planar regions, curved surfaces as well as 3D volumes has been extensively studied in Finite Element Analysis (FEA) in the past…
(more)
▼ Adaptive meshing of 2D planar regions, curved
surfaces as well as 3D volumes has been extensively studied in
Finite Element Analysis (FEA) in the past few decades. Despite the
maturity of these adaptive meshing approaches, most of the existing
schemes assume the domain or sub-domain of interest is homogeneous.
In the context of FEA of heterogeneous objects, traditional
adaptive mesh generation strategies become inadequate as they fail
to take into account the material heterogeneities. This thesis is
motivated to tackle these problems and propose an adaptive mesh
generation scheme for FEA of versatile heterogeneous materials. In
order to tackle the material heterogeneities and the geometric
complexities, the proposed adaptive meshing strategy embraces three
steps: initial mesh generation, material-oriented refinement, and
geometry-oriented refinement. Specifically, in the
material-oriented refinement, a centroidal Voronoi tessellation
(CVT)-based method is designed to control the mesh adaptation in
terms of the material distribution. Based on a specific density
function of material variations, the CVT-based method distributes
the material composition variation over elements as equally as
possible and thus minimizes the number of elements regarding a
given material threshold. Experiments show that the proposed
approach guarantees desirable mesh adaptation as well as high mesh
quality.
By coupling the idea of adaptive meshing and a
heterogeneous solid modeler, we further propose an automatic mesh
generation strategy for heterogeneous objects. The automatic mesh
generation method consists of two stages: preprocessing and
adaptive mesh generation; the role of the former is to convert
heterogeneous CAD models into meshing-suitable models while the
latter aims to generate adaptive meshes with respect to the
material and geometric information. In the adaptive mesh algorithm,
we introduced a direct refinement algorithm rather than the
previous step-wise approach to refine the targeted mesh according
to the material threshold and the minimum angle simultaneously. In
addition, an optimal Delaunay triangulation (ODT)-based method was
utilized to improve the mesh quality and control the mesh density
instead of the previous CVT-based method. Experiments show that the
proposed automatic mesh generation method has the capacities to
generate efficient meshes on both 2D and 3D heterogeneous object
models with complex material distributions such as bidirectional
and tri-directional.
As a natural progression of the preceding
automatic mesh generation method, we develop an integrated CAD-FEA
system for heterogeneous object design and analysis with the
automatic mesh generator being an integral part. The integrated
system includes three parts: heterogeneous solid modeler, automatic
mesh generator, and FEA module. The main role of the automatic mesh
generator here is to convert heterogeneous solid models into finite
element models automatically so that FEA can be conducted.
Experiments demonstrate that this integrated system releases…
Subjects/Keywords: Finite element method; Numerical grid generation (Numerical
analysis)
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APA ·
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Manager
APA (6th Edition):
尤耀辉; You, Y. (2015). Automatic mesh generation of heterogeneous objects for
finite element analysis. (Doctoral Dissertation). University of Hong Kong. Retrieved from You, Y. [尤耀辉]. (2015). Automatic mesh generation of heterogeneous objects for finite element analysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5689288 ; http://dx.doi.org/10.5353/th_b5689288 ; http://hdl.handle.net/10722/222398
Chicago Manual of Style (16th Edition):
尤耀辉; You, Yaohui. “Automatic mesh generation of heterogeneous objects for
finite element analysis.” 2015. Doctoral Dissertation, University of Hong Kong. Accessed September 23, 2019.
You, Y. [尤耀辉]. (2015). Automatic mesh generation of heterogeneous objects for finite element analysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5689288 ; http://dx.doi.org/10.5353/th_b5689288 ; http://hdl.handle.net/10722/222398.
MLA Handbook (7th Edition):
尤耀辉; You, Yaohui. “Automatic mesh generation of heterogeneous objects for
finite element analysis.” 2015. Web. 23 Sep 2019.
Vancouver:
尤耀辉; You Y. Automatic mesh generation of heterogeneous objects for
finite element analysis. [Internet] [Doctoral dissertation]. University of Hong Kong; 2015. [cited 2019 Sep 23].
Available from: You, Y. [尤耀辉]. (2015). Automatic mesh generation of heterogeneous objects for finite element analysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5689288 ; http://dx.doi.org/10.5353/th_b5689288 ; http://hdl.handle.net/10722/222398.
Council of Science Editors:
尤耀辉; You Y. Automatic mesh generation of heterogeneous objects for
finite element analysis. [Doctoral Dissertation]. University of Hong Kong; 2015. Available from: You, Y. [尤耀辉]. (2015). Automatic mesh generation of heterogeneous objects for finite element analysis. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5689288 ; http://dx.doi.org/10.5353/th_b5689288 ; http://hdl.handle.net/10722/222398
9.
Liu, Tuo.
Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/532
► In this research, an automatic, complex geometry applicable, unstructured curved 2D mesh generation method is developed. Based on this 2D method, an extension to 3D…
(more)
▼ In this research, an automatic, complex geometry applicable, unstructured curved 2D mesh generation
method is developed. Based on this 2D
method, an extension to 3D geometries is developed. The methodology of this mesh generation is to provide near-body and off-body meshes by an advancing-layer
method to avoid mesh quality problems in transition areas, while using spring models to complement the advancing-layers by smoothing the mesh, especially in medial axis regions. After generating the linear mesh, a higher-order finite-element ready, curved mesh is obtained by deforming the linear mesh through “pipes” using a simple Vector-Adding approach. Different from most curved viscous mesh generation approaches, this
method eschews a linear or nonlinear elasticity analogy while still providing positive-Jacobian mesh elements. In addition, the transformation from linear to curved meshes can be achieved by only deforming the necessary edges of the elements near domain boundaries while retaining the remaining non-curved edges to the benefit of
numerical solvers. The CFD results of 30P30N airfoil on the curved mesh are given and are in good agreement with the experimental data.
Further, a new
method for moving boundary problems with viscous mesh layers is also presented. This
method is an extension of the mesh generation approach above. It can be used not only for high-order mesh moving but also for high-order mesh generation. Also, based on the curved mesh deformation strategy, the
method can handle high-order mesh movement or regeneration with minimal extra computational time compared with linear mesh movement. Several 2D boundary motion cases are tested including boundary translations, boundary rotations, and boundary morphing. The CFD results on the curved mesh after rotation are given and are in good agreement with the experimental data. This technique is also tested through the optimization of an airfoil to achieve a maximized lift and drag ratio. The results demonstrate that this approach can handle large boundary movements while preserving a good mesh quality.
Advisors/Committee Members: Hilbert, C. Bruce, Newman, James C., III, Sreenivas, Kidambi, Karman, Steve L., Jr., College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method – Data processing
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Chicago ·
MLA ·
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to Zotero / EndNote / Reference
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APA (6th Edition):
Liu, T. (2017). Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/532
Chicago Manual of Style (16th Edition):
Liu, Tuo. “Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed September 23, 2019.
https://scholar.utc.edu/theses/532.
MLA Handbook (7th Edition):
Liu, Tuo. “Automatic higher order mesh generation and movement utilizing spring-field and vector-adding.” 2017. Web. 23 Sep 2019.
Vancouver:
Liu T. Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2019 Sep 23].
Available from: https://scholar.utc.edu/theses/532.
Council of Science Editors:
Liu T. Automatic higher order mesh generation and movement utilizing spring-field and vector-adding. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/532
10.
Karman, Kristen.
Higher order mesh curving using geometry curvature extrapolation.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/533
► A higher order mesh curving method is developed which uses information from the geometry to determine the appropriate curvature of edges in the interior of…
(more)
▼ A higher order mesh curving
method is developed which uses information from the geometry to determine the appropriate curvature of edges in the interior of the mesh. Edges are represented using four point Bézier curves to determine the positions of higher order edge points. Higher order face and volume points are positioned using the basis functions for serendipity face and volume
elements. Parameters are defined which allow user specified control over element quality and the propagation of curvature in the mesh. Curved higher order meshes are shown for test cases in both two and three dimensions.
Advisors/Committee Members: Hilbert, C. Bruce, Newman, James C., III, Sreenivas, Kidambi, Matthews, Matt, College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method
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Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Karman, K. (2017). Higher order mesh curving using geometry curvature extrapolation. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/533
Chicago Manual of Style (16th Edition):
Karman, Kristen. “Higher order mesh curving using geometry curvature extrapolation.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed September 23, 2019.
https://scholar.utc.edu/theses/533.
MLA Handbook (7th Edition):
Karman, Kristen. “Higher order mesh curving using geometry curvature extrapolation.” 2017. Web. 23 Sep 2019.
Vancouver:
Karman K. Higher order mesh curving using geometry curvature extrapolation. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2019 Sep 23].
Available from: https://scholar.utc.edu/theses/533.
Council of Science Editors:
Karman K. Higher order mesh curving using geometry curvature extrapolation. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/533
11.
Shoemake, William L.
Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.
Degree: 2017, University of Tennessee – Chattanooga
URL: https://scholar.utc.edu/theses/534
► The finite element method has been shown to be a powerful tool in computational engineering with recent application to electromagnetics and fluid dynamics. However, achieving…
(more)
▼ The finite element
method has been shown to be a powerful tool in computational engineering
with recent application to electromagnetics and fluid dynamics. However, achieving the
high orders of accuracy easily available to the finite element
method has proven difficult due to
conforming higher-order meshes to curved geometries. If higher-order nodes are not placed on the
surface of the geometry error is introduced into the simulated solution. This barrier is largely a
non-issue for inviscid meshes where a mid-edge node can be projected onto the nearest geometry
surface with minimal detrimental side effects. Viscous meshes however have to deform most of
the boundary layers in order to avoid inverting the surface elements and to maintain an acceptable
mesh quality. This research focuses on extending the application of the linear elastic analogy to
this mesh movement problem by attributing orthotropic material properties individually to each
node or element. This technique allows each node or element to behave differently under the
stress of conforming to the boundary. These localized material properties are determined using the
adjoint optimization
method. To better determine mesh quality, a new mesh metric called Metric3
is introduced. This new metric resembles the included angle metric and is based on an element’s
isoparametric transformation matrix.
Advisors/Committee Members: Hilbert, C. Bruce, Sreenivas, Kidambi, Matthews, Matt, Newman, James C., III, College of Engineering and Computer Science.
Subjects/Keywords: Numerical grid generation (Numerical analysis); Finite element method
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Shoemake, W. L. (2017). Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. (Doctoral Dissertation). University of Tennessee – Chattanooga. Retrieved from https://scholar.utc.edu/theses/534
Chicago Manual of Style (16th Edition):
Shoemake, William L. “Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.” 2017. Doctoral Dissertation, University of Tennessee – Chattanooga. Accessed September 23, 2019.
https://scholar.utc.edu/theses/534.
MLA Handbook (7th Edition):
Shoemake, William L. “Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method.” 2017. Web. 23 Sep 2019.
Vancouver:
Shoemake WL. Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. [Internet] [Doctoral dissertation]. University of Tennessee – Chattanooga; 2017. [cited 2019 Sep 23].
Available from: https://scholar.utc.edu/theses/534.
Council of Science Editors:
Shoemake WL. Linear elastic mesh deformation via localized orthotropic material properties optimized by the adjoint method. [Doctoral Dissertation]. University of Tennessee – Chattanooga; 2017. Available from: https://scholar.utc.edu/theses/534
University of Colorado
12.
Ashby, Ava.
The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.
Degree: MS, Physics, 2016, University of Colorado
URL: http://scholar.colorado.edu/phys_gradetds/165
► The general impedance method developed by Khondker et.al [1] is applied to multiple barrier potentials to study the transmission behaviors of a single Gaussian…
(more)
▼ The general impedance
method developed by Khondker et.al [1] is applied to multiple barrier potentials to study the transmission behaviors of a single Gaussian barrier potential, double rectangular barrier potential, and a double Gaussian barrier potential. Using the impedance
method we will find quantum mechanical transmission behaviors like resonant tunneling for the quasi bound-states of the double barrier potentials. The single Gaussian barrier potential is an approximation for the atomtronic battery and the double Gaussian barrier potential is an approximation for the atomtronic transistor. Thus far, the atomtronic work presented in reference [2] was done in the classical regime where thermal currents dominate. The work presented in this thesis analyzes the quantum mechanical characteristics, such as tunneling, to be incorporated and perhaps used to explore coherent transistor action.
Advisors/Committee Members: Dana Anderson, Heather Lewandowski, Charles Rogers.
Subjects/Keywords: atomtronics; impedance method; numerical method; quantum mechanical transmission probablity; Physics
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ashby, A. (2016). The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. (Masters Thesis). University of Colorado. Retrieved from http://scholar.colorado.edu/phys_gradetds/165
Chicago Manual of Style (16th Edition):
Ashby, Ava. “The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.” 2016. Masters Thesis, University of Colorado. Accessed September 23, 2019.
http://scholar.colorado.edu/phys_gradetds/165.
MLA Handbook (7th Edition):
Ashby, Ava. “The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method.” 2016. Web. 23 Sep 2019.
Vancouver:
Ashby A. The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. [Internet] [Masters thesis]. University of Colorado; 2016. [cited 2019 Sep 23].
Available from: http://scholar.colorado.edu/phys_gradetds/165.
Council of Science Editors:
Ashby A. The Study of Modeled Atomtronic Barrier Potentials Through the Impedance Method. [Masters Thesis]. University of Colorado; 2016. Available from: http://scholar.colorado.edu/phys_gradetds/165
NSYSU
13.
Lin, Bing-han.
Method of fundamental solutions on simulating sloshing liquids in 2D tanks.
Degree: Master, Marine Environment and Engineering, 2018, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
► A two dimension numerical model for sloshing response of the partially filled con- tainer is developed by a meshless method in this study. Laplace equation…
(more)
▼ A two dimension
numerical model for sloshing response of the partially filled con-
tainer is developed by a meshless
method in this study. Laplace equation is considered
as the governing equation for potential flow, and fully non-linear free surface boundary
conditions are implemented on the free surface. The
numerical model is established in
the moving coordinate system attached to the container. The present meshless
method,
method of fundamental solutions, only need to distribute nodes on the physical bound-
aries and the virtual boundaries outside the computational domain. Comparing with the
traditional mesh-based
numerical method, this
method has the advantage of being easy
to construct and flexible in dealing with the moving boundary problem. A preliminary
numerical validation was carried out by the case of a free oscillating standing wave. The
parameters such as the position of the virtual boundary, the number of nodes, and the time
step size are also determined.
The program is written in Python. A simple
method for tracking fully non-linear free
surface is implemented, and the physical boundaries are updated with time. The
numerical
results under horizontal motions were compared with the solutions of Chen and Chiang
(1999) and Frandsen (2004), respectively. The comparison shows that the presented re-
sults coincide with their solutions very well in both resonance and off-resonance cases.
The present
numerical model is further applied to the sloshing response under coupled
motions (horizontal and vertical). Based on the study of Benjamin and Ursell (1954) who
discussed the stability of sloshing response under vertical motion, 25 cases are conducted
in various sloshing parameters under coupled motions. The present
numerical model has
been successfully applied to investigating sloshing response under coupled motions.
Advisors/Committee Members: Shih-Meng Hsu (chair), Liang-hsiung Huang (chair), Bang-Fuh Chen (committee member), Chia-Cheng Tsai (chair).
Subjects/Keywords: Numerical tank; Nonlinear free surface; Method of fundamental solution; Meshless method
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lin, B. (2018). Method of fundamental solutions on simulating sloshing liquids in 2D tanks. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
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):
Lin, Bing-han. “Method of fundamental solutions on simulating sloshing liquids in 2D tanks.” 2018. Thesis, NSYSU. Accessed September 23, 2019.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lin, Bing-han. “Method of fundamental solutions on simulating sloshing liquids in 2D tanks.” 2018. Web. 23 Sep 2019.
Vancouver:
Lin B. Method of fundamental solutions on simulating sloshing liquids in 2D tanks. [Internet] [Thesis]. NSYSU; 2018. [cited 2019 Sep 23].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lin B. Method of fundamental solutions on simulating sloshing liquids in 2D tanks. [Thesis]. NSYSU; 2018. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0413118-191748
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Guelph
14.
Althubyani, Mohammed.
Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
.
Degree: 2013, University of Guelph
URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
► Traditionally, the numerical analysis of di erential equations focusses on stability, convergence and accuracy of the numerical methods employed. However in practice, there are other…
(more)
▼ Traditionally, the
numerical analysis of di erential equations focusses
on stability, convergence and accuracy of the
numerical methods employed.
However in practice, there are other features of the
numerical methods that
we are interested in. Generally, when we discretize a di erential equation,
we would like to preserve certain intrinsic characteristics of the model, for
example, positivity and boundedness of the quantities of interest. Consider-
able progress has been made in this area for the Finite Di erence
Method
(FDM), for example, the Non Standard Finite Di erence
Method (NSFDM).
However, little work has been done on preserving positivity and bounded-
ness for the
numerical solutions of the Finite Element
Method (FEM). In this
work we develop a general framework for achieving this aim, which is based
on the careful application of the Standard Galerkin FEM with 'Mass Lump-
ing'. For concreteness, we present results for the Heat Equation, The Fisher
reaction-di usion equation, and a coupled predator-prey reaction-di usion of
Rosenzweig-MacArthur form.
Advisors/Committee Members: Garvie, Marcus (advisor).
Subjects/Keywords: Numerical Analysis;
Finite Difference Method;
Finite Element Method
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Export
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Manager
APA (6th Edition):
Althubyani, M. (2013). Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
. (Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
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):
Althubyani, Mohammed. “Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
.” 2013. Thesis, University of Guelph. Accessed September 23, 2019.
https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Althubyani, Mohammed. “Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
.” 2013. Web. 23 Sep 2019.
Vancouver:
Althubyani M. Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
. [Internet] [Thesis]. University of Guelph; 2013. [cited 2019 Sep 23].
Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Althubyani M. Bounded and Positive Finite Element Approximations of Reaction-Diffusion Equations
. [Thesis]. University of Guelph; 2013. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/7513
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Cambridge
15.
Rockstroh, Parousia.
Boundary value problems for the Laplace equation on convex domains with analytic boundary.
Degree: PhD, 2018, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/273939
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744615
► In this thesis we study boundary value problems for the Laplace equation on do mains with smooth boundary. Central to our analysis is a relation,…
(more)
▼ In this thesis we study boundary value problems for the Laplace equation on do mains with smooth boundary. Central to our analysis is a relation, known as the global relation, that couples the boundary data for a given BVP. Previously, the global re lation has primarily been applied to elliptic PDEs defined on polygonal domains. In this thesis we extend the use of the global relation to domains with smooth boundary. This is done by introducing a new transform, denoted by F_p, that is an analogue of the Fourier transform on smooth convex curves. We show that the F_p-transform is a bounded and invertible integral operator. Following this, we show that the F_p-transform naturally arises in the global relation for the Laplace equation on domains with smooth boundary. Using properties of the F_p-transform, we show that the global relation defines a continuously invertible map between the Dirichlet and Neumann data for a given BVP for the Laplace equation. Following this, we construct a numerical method that uses the global relation to find the Neumann data, given the Dirichlet data, for a given BVP for the Laplace equation on a domain with smooth boundary.
Subjects/Keywords: Partial Differential Equations; Laplace Equation; Fokas Method; Unified Transform Method; Elliptic PDEs; Numerical Method
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Rockstroh, P. (2018). Boundary value problems for the Laplace equation on convex domains with analytic boundary. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/273939 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744615
Chicago Manual of Style (16th Edition):
Rockstroh, Parousia. “Boundary value problems for the Laplace equation on convex domains with analytic boundary.” 2018. Doctoral Dissertation, University of Cambridge. Accessed September 23, 2019.
https://www.repository.cam.ac.uk/handle/1810/273939 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744615.
MLA Handbook (7th Edition):
Rockstroh, Parousia. “Boundary value problems for the Laplace equation on convex domains with analytic boundary.” 2018. Web. 23 Sep 2019.
Vancouver:
Rockstroh P. Boundary value problems for the Laplace equation on convex domains with analytic boundary. [Internet] [Doctoral dissertation]. University of Cambridge; 2018. [cited 2019 Sep 23].
Available from: https://www.repository.cam.ac.uk/handle/1810/273939 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744615.
Council of Science Editors:
Rockstroh P. Boundary value problems for the Laplace equation on convex domains with analytic boundary. [Doctoral Dissertation]. University of Cambridge; 2018. Available from: https://www.repository.cam.ac.uk/handle/1810/273939 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744615
University of Cambridge
16.
Rockstroh , Parousia.
Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
.
Degree: 2018, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/273939
► In this thesis we study boundary value problems for the Laplace equation on do mains with smooth boundary. Central to our analysis is a relation,…
(more)
▼ In this thesis we study boundary value problems for the Laplace equation on do
mains with smooth boundary. Central to our analysis is a relation, known as the global
relation, that couples the boundary data for a given BVP. Previously, the global re
lation has primarily been applied to elliptic PDEs defined on polygonal domains. In
this thesis we extend the use of the global relation to domains with smooth boundary. This is done by introducing a new transform, denoted by F_p, that is an analogue of the Fourier transform on smooth convex curves. We show that the F_p-transform is a bounded and invertible integral operator. Following this, we show that the F_p-transform naturally arises in the global relation for the Laplace equation on domains with smooth boundary. Using properties of the F_p-transform, we show that the global relation defines a continuously invertible map between the Dirichlet and Neumann data
for a given BVP for the Laplace equation. Following this, we construct a numerical
method that uses the global relation to find the Neumann data, given the Dirichlet
data, for a given BVP for the Laplace equation on a domain with smooth boundary.
Subjects/Keywords: Partial Differential Equations;
Laplace Equation;
Fokas Method;
Unified Transform Method;
Elliptic PDEs;
Numerical Method
Record Details
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Rockstroh , P. (2018). Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
. (Thesis). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/273939
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):
Rockstroh , Parousia. “Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
.” 2018. Thesis, University of Cambridge. Accessed September 23, 2019.
https://www.repository.cam.ac.uk/handle/1810/273939.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Rockstroh , Parousia. “Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
.” 2018. Web. 23 Sep 2019.
Vancouver:
Rockstroh P. Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
. [Internet] [Thesis]. University of Cambridge; 2018. [cited 2019 Sep 23].
Available from: https://www.repository.cam.ac.uk/handle/1810/273939.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Rockstroh P. Boundary Value Problems for the Laplace Equation on Convex Domains with Analytic Boundary
. [Thesis]. University of Cambridge; 2018. Available from: https://www.repository.cam.ac.uk/handle/1810/273939
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Washington State University
17.
[No author].
APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.
Degree: 2013, Washington State University
URL: http://hdl.handle.net/2376/5057
► We describe how the analytic field propagation (AFP) technique can be coupled with a total-field/scattered-field (TFSF) boundary to obtain a novel implementation of a "gen-eralized"…
(more)
▼ We describe how the analytic field propagation (AFP) technique can be coupled with a total-field/scattered-field (TFSF) boundary to obtain a novel implementation of a "gen-eralized" total-field/scattered-field (G-TFSF) boundary. Using a G-TFSF boundary,one can directly model "infinite" objects, such as wedges, corners, and edges. Exampleapplications of the AFP-based G-TFSF technique are shown that model not just scatter-ing from wedges, but also scattering from 3D "defects" in wedges or edges. As describedin the thesis, the AFP-based G-TFSF
method described in this thesis possesses variousadvantages over the original G-TFSF
method presented by Anantha and Taflove [IEEETrans. Antennas and Propagat., 50(10):1337-1349, 2002].We revisit the long-standing debate surrounding whether or not "enhanced totalinternal reflection" (ETIR) is possible. ETIR implies that the magnitude of the reflectioncoefficient is greater than unity and is conjectured to be possible when a field is incidentfrom a lossless material to a gainy material beyond the critical angle. We examine thisproblem using FDTD modeling where the Poynting vector is used to examine the flowof energy. The two-dimensional simulations employ a Gaussian incident beam and makeno a priori assumptions about the reflection coefficient. We consider illumination ofgainy, lossless, and lossy materials. For gainy material, the magnitude of the reflectioncoefficient is found to be greater than unity, but there is a delay between when energyenters the gainy material and when the "excess" energy is reflected from the interface.Corona onset conditions in periodic micro- and nano-materials are analyzed via a dis-cretization of Gauss's Law. A
numerical model is developed to examine the mechanismby which nano-materials may provide superior performance relative to micro-materials.Starting from a single-cell layered structure, the electrical field distribution is computedusing the finite difference
method (FDM) and a sparse matrix solver. From these results,a general model is inferred by comparing results from the multi-cell layered structures tothe single-cell layered ones. Next, the corona onset condition is calculated for materialwith any particle size. Finally, the relationship between the breakdown voltage and theparticle size is derived based on the
numerical findings.
Advisors/Committee Members: Schneider, John B (advisor).
Subjects/Keywords: Electromagnetics;
Electrical engineering;
Computer science;
Electromagnetics;
FDTD method;
finite-difference method;
numerical method
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APA (6th Edition):
author], [. (2013). APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. (Thesis). Washington State University. Retrieved from http://hdl.handle.net/2376/5057
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):
author], [No. “APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.” 2013. Thesis, Washington State University. Accessed September 23, 2019.
http://hdl.handle.net/2376/5057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
author], [No. “APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
.” 2013. Web. 23 Sep 2019.
Vancouver:
author] [. APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. [Internet] [Thesis]. Washington State University; 2013. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/2376/5057.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
author] [. APPLICATIONS OF, AND ENHANCEMENTS TO, FINITE-DIFFERENCE-BASED SOLUTIONS TO PROBLEMS IN ELECTROMAGNETICS
. [Thesis]. Washington State University; 2013. Available from: http://hdl.handle.net/2376/5057
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Manchester
18.
Owen, Benjamin Joseph.
Development of a discrete fluid-structure interaction
method for cardiovascular applications.
Degree: 2019, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
► The interaction between blood and cardiovascular tissue is known to play a significant role in the development cardiovascular diseases and associated conditions. With the ever…
(more)
▼ The interaction between blood and cardiovascular
tissue is known to play a significant role in the development
cardiovascular diseases and associated conditions. With the ever
increasing availability and performance of computational resources,
in conjunction with improved understanding of the disease
mechanisms, the integration of
numerical analysis into in silico
tools has become more prevalent. Once viewed as emerging
technology, these tools are now being routinely utilised in
clinical practice. However, the majority of these tools consider
the fluid or structure in isolation. This is due to the added
complexity of coupling the methods and the computational cost
incurred through modelling fluid-structure interaction using
traditional continuum methods. As a result, discretisations of the
structure used in fluid-structure interaction (FSI) methods tend to
be simpler representations and offer limited potential to model
complex non-linear material properties and discrete effects such as
rupture. The purpose of this work is to develop an efficient
fluid-structure interaction
method capable of modelling complex
phenomena. The inherent parallel performance of discrete
numerical
methods is explored, with a long-term view to developing the
method
for use in clinical tools; where speed, robustness and adaptability
are paramount. In the present work, the fluid is represented via
the lattice Boltzmann
method and the structure via the vector-based
discrete element
method, known as the V-model. These solvers are
strongly coupled using a version of the immersed boundary
method
based on direct forcing in a block Gauss-Seidel scheme, where the
time step size of the fluid and structure are to be kept
independent. Validation results for the V-model show good agreement
with analytical and
numerical solutions for static and dynamic
cantilever beam cases with constant and time-varying external
loads. This demonstrates the V-model's ability to accurately
capture the mechanical response of a material before extending the
method to model more complex physics. GPU implementation of the
V-model demonstrated speed-ups of x50 relative to an optimised
serial CPU implementation. The FSI
method demonstrated good
agreement with
numerical benchmark data while stochastic modelling
of the structure material properties demonstrated the V-model's
potential to model variation in cardiovascular tissue that occurs
naturally and due to disease. The major original contributions of
this work include the implementation and elucidation of a recently
developed structure model; which is used here for the first time
with a lattice Boltzmann scheme. The work also provides first steps
towards the use of stochastic modelling using the V-model, the
first GPU implementation of the V-model, and development of the
first strongly coupled fluid-structure interaction
method to
include the V-model.
Advisors/Committee Members: BOJDO, NICHOLAS NM, KEAVNEY, BERNARD B, HARWOOD, ADRIAN ARG, Revell, Alistair, Bojdo, Nicholas, Keavney, Bernard, Harwood, Adrian.
Subjects/Keywords: fluid-structure interaction; numerical modelling; GPU; discrete element method; lattice Boltzmann method; immersed boundary method
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Owen, B. J. (2019). Development of a discrete fluid-structure interaction
method for cardiovascular applications. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
Chicago Manual of Style (16th Edition):
Owen, Benjamin Joseph. “Development of a discrete fluid-structure interaction
method for cardiovascular applications.” 2019. Doctoral Dissertation, University of Manchester. Accessed September 23, 2019.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620.
MLA Handbook (7th Edition):
Owen, Benjamin Joseph. “Development of a discrete fluid-structure interaction
method for cardiovascular applications.” 2019. Web. 23 Sep 2019.
Vancouver:
Owen BJ. Development of a discrete fluid-structure interaction
method for cardiovascular applications. [Internet] [Doctoral dissertation]. University of Manchester; 2019. [cited 2019 Sep 23].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620.
Council of Science Editors:
Owen BJ. Development of a discrete fluid-structure interaction
method for cardiovascular applications. [Doctoral Dissertation]. University of Manchester; 2019. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:320620
The Ohio State University
19.
Zhao, Kezhong.
A domain decomposition method for solving electrically large
electromagnetic problems.
Degree: PhD, Electrical Engineering, 2007, The Ohio State University
URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1189694496
► This dissertation presents a domain decomposition method as an effective and efficient preconditioner for frequency domain FEM solution of geometrically complex and electrically large electromagnetic…
(more)
▼ This dissertation presents a domain decomposition
method as an effective and efficient preconditioner for frequency
domain FEM solution of geometrically complex and electrically large
electromagnetic problems. The
method reduces memory requirements by
decomposing the original problem domain into several
non-overlapping and possibly repeatable sub-domains. At the heart
of this research are the Robin-to-Robin map, the “cement” finite
element coupling of non-conforming grids and the concept of duality
paring. The Robin’s transmission condition is employed on
interfaces between adjacent sub-domains to enforce continuity of
electromagnetic fields and to ensure the sub-domain problems are
well-posed. Through the introduction of cement variables, the
meshes at the interface could be non-conformal which significantly
relaxes the meshing procedures. By following the spirit of duality
paring a symmetric system is obtained to better reflect physical
nature of the problem. These concepts in conjunction with the
so-called finite element tearing and interconnecting algorithm form
the basic modules of the present domain decomposition
method. To
enhance the convergence of DDM solver, the Krylov solvers instead
of classical stationary solvers are employed and studied. In order
to account the radiation condition exactly thus eliminating
spurious reflection, a boundary element formulation is hybridized
with the present DD
method, also through the aforementioned novel
concepts. One of the special cases of present hybridization is the
well known hybrid finite element and boundary element
method. It
will be shown that the proposed hybrid offers simultaneously: (1)
symmetry, (2) modularity, (3) non-conformity between FEM and BEM
domains, (4) free of internal resonance, and (5) natural and
effective preconditioning scheme that guarantees spectral radius
less or equal to one. Lastly this dissertation presents a DDM
solution scheme for analyzing electromagnetic problems involving
multiple separable scatterers. The
method first decomposes the
original problem into several disjoint sub-regions. In each
sub-region, the domain decomposition
method is further applied
rendering geometrically complicated and electrically large
sub-region problems tractable. The sub-regions communicate through
the near-field Green’s function. To overcome the vast computational
costs required in exchanging information between electrically large
sub-regions, the adaptive cross approximation algorithm is adopted
to expedite the process.
Advisors/Committee Members: Lee, Jin-Fa (Advisor).
Subjects/Keywords: numerical methods; computational electromagnetics; domain decomposition method; finite element method; hybrid finite element and boundary element
method; multi-region method
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APA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Zhao, K. (2007). A domain decomposition method for solving electrically large
electromagnetic problems. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1189694496
Chicago Manual of Style (16th Edition):
Zhao, Kezhong. “A domain decomposition method for solving electrically large
electromagnetic problems.” 2007. Doctoral Dissertation, The Ohio State University. Accessed September 23, 2019.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1189694496.
MLA Handbook (7th Edition):
Zhao, Kezhong. “A domain decomposition method for solving electrically large
electromagnetic problems.” 2007. Web. 23 Sep 2019.
Vancouver:
Zhao K. A domain decomposition method for solving electrically large
electromagnetic problems. [Internet] [Doctoral dissertation]. The Ohio State University; 2007. [cited 2019 Sep 23].
Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1189694496.
Council of Science Editors:
Zhao K. A domain decomposition method for solving electrically large
electromagnetic problems. [Doctoral Dissertation]. The Ohio State University; 2007. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1189694496
Université Catholique de Louvain
20.
Hubert, Simon.
Numerical analysis of strongly coupled antenna arrays and metasurfaces.
Degree: 2018, Université Catholique de Louvain
URL: http://hdl.handle.net/2078.1/198381
► Nowadays, communication technologies form an essential part of our everyday lives. Antenna systems receive thus more and more attention from both industrial and academic actors.…
(more)
▼ Nowadays, communication technologies form an essential part of our everyday lives. Antenna systems receive thus more and more attention from both industrial and academic actors. These modern technologies are increasingly complex, and require fast prototyping and benchmarking in their design process. Numerical methods play a key role in that perspective, by providing an accurate estimation of the performance at low cost. However, the computation time and memory required by these electromagnetic simulators remain prohibitively high for certain classes of problems. This thesis focuses on the development of specialized numerical methods, with the goal of mitigating their computational cost. The proposed methods are physics-based optimizations of the Method of Moments, which has been ubiquitous in the analysis of planar and metallic antenna structures. Motivated by the recent and exciting advances in the field of metasurface antennas, the main part of the dissertation is dedicated to planar structures. The contributions range from essentially theoretical results, such as mathematical links between well-established antenna theory results; to efficient solvers exploiting the Contour-FFT for the analysis of large planar arbitrary arrays; to the development of miniaturized shielded arrays for localization applications.
(FSA - Sciences de l'ingénieur) – UCL, 2018
Advisors/Committee Members: UCL - SST/ICTM/ELEN - Pôle en ingénierie électrique, UCL - Ecole Polytechnique de Louvain, Craeye, Christophe, Oestges, Claude, Bol, David, Gilles, Thierry, Hum, Sean, Mesa, Francisco.
Subjects/Keywords: Antenna; Metasurface; Electromagnetics; Computational electromagnetics; Antenna array; Numerical method; Algorithm; Simulation; Mutual coupling; Numerical analysis
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Hubert, S. (2018). Numerical analysis of strongly coupled antenna arrays and metasurfaces. (Thesis). Université Catholique de Louvain. Retrieved from http://hdl.handle.net/2078.1/198381
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):
Hubert, Simon. “Numerical analysis of strongly coupled antenna arrays and metasurfaces.” 2018. Thesis, Université Catholique de Louvain. Accessed September 23, 2019.
http://hdl.handle.net/2078.1/198381.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hubert, Simon. “Numerical analysis of strongly coupled antenna arrays and metasurfaces.” 2018. Web. 23 Sep 2019.
Vancouver:
Hubert S. Numerical analysis of strongly coupled antenna arrays and metasurfaces. [Internet] [Thesis]. Université Catholique de Louvain; 2018. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/2078.1/198381.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hubert S. Numerical analysis of strongly coupled antenna arrays and metasurfaces. [Thesis]. Université Catholique de Louvain; 2018. Available from: http://hdl.handle.net/2078.1/198381
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of California – Berkeley
21.
Hermes, Daniel Jerome.
High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.
Degree: Applied Mathematics, 2018, University of California – Berkeley
URL: http://www.escholarship.org/uc/item/2p38w1w6
► The problem of solution transfer between meshes arises frequently in computational physics, e.g. in Lagrangian methods where remeshing occurs. The interpolation process must be conservative,…
(more)
▼ The problem of solution transfer between meshes arises frequently in computational physics, e.g. in Lagrangian methods where remeshing occurs. The interpolation process must be conservative, i.e. it must conserve physical properties, such as mass. We extend previous works – which described the solution transfer process for straight sided unstructured meshes – by considering high-order isoparametric meshes with curved elements. The implementation is highly reliant on accurate computational geometry routines for evaluating points on and intersecting Bézier curves and triangles.Two ill-conditioned problems that occur evaluating points on and intersecting Bézier curves are then explored. This work presents a family of compensated algorithms to accurately evaluate a polynomial in Bernstein form with floating point coefficients. The principle is to apply error-free transformations to improve the traditional de Casteljau algorithm. The resulting output is as accurate as the de Casteljau algorithm performed in K times the working precision. After compensated evaluation is considered, a compensated Newton's method is described, both for root-finding for polynomials in the Bernstein basis and for Bézier curve intersection.
Subjects/Keywords: Applied mathematics; Bezier Curve Intersection; Compensated Algorithm; Lagrangian Method; Numerical Analysis; Numerical Quadrature; Solution Transfer
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APA (6th Edition):
Hermes, D. J. (2018). High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/2p38w1w6
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):
Hermes, Daniel Jerome. “High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.” 2018. Thesis, University of California – Berkeley. Accessed September 23, 2019.
http://www.escholarship.org/uc/item/2p38w1w6.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Hermes, Daniel Jerome. “High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection.” 2018. Web. 23 Sep 2019.
Vancouver:
Hermes DJ. High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. [Internet] [Thesis]. University of California – Berkeley; 2018. [cited 2019 Sep 23].
Available from: http://www.escholarship.org/uc/item/2p38w1w6.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Hermes DJ. High-order Solution Transfer between Curved Meshes and Ill-conditioned Bézier Curve Intersection. [Thesis]. University of California – Berkeley; 2018. Available from: http://www.escholarship.org/uc/item/2p38w1w6
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Johannes Gutenberg Universität Mainz
22.
Götz, Daniel.
Helicity methods in LO and NLO QCD calculations.
Degree: 2014, Johannes Gutenberg Universität Mainz
URL: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
► The goal of this thesis is the acceleration of numerical calculations of QCD observables, both at leading order and next–to–leading order in the coupling constant.…
(more)
▼ The goal of this thesis is the acceleration of numerical calculations of QCD observables, both at leading order and next–to–leading order in the coupling constant. In particular, the optimization of helicity and spin summation in the context of VEGAS Monte Carlo algorithms is investigated. In the literature, two such methods are mentioned but without detailed analyses. Only one of these methods can be used at next–to–leading order. This work presents a total of five different methods that replace the helicity sums with a Monte Carlo integration. This integration can be combined with the existing phase space integral, in the hope that this causes less overhead than the complete summation. For three of these methods, an extension to existing subtraction terms is developed which is required to enable next–to–leading order calculations. All methods are analyzed with respect to efficiency, accuracy, and ease of implementation before they are compared with each other. In this process, one method shows clear advantages in relation to all others.
Ziel dieser Arbeit ist es, die numerische Berechnung von QCD Observablen sowohl auf führender Ordnung als auch auf nächst-führender Ordnung in der Kopplungskonstante zu beschleunigen. Konkret wird eine solche Optimierung im Gebiet der Helizitäts- und Spinsummen im Zusammenhang mit dem VEGAS-Monte-Carlo-Algorithmus untersucht. In der Literatur werden zwei solcher Methoden erwähnt, jedoch ohne detaillierte Analysen. Nur eine dieser Methoden ist auf die nächst-führende Ordnung anwendbar. Diese Arbeit stellt insgesamt fünf verschiedene Methoden vor, welche die Helizitätssummen durch eine Monte-Carlo-Integration ersetzen. Diese kann mit dem existierenden Phasenraumintegral kombiniert werden, in der Hoffnung dass dies einen geringeren Mehraufwand als die vollständige Summation bietet. Für drei der Methoden wird eine Erweiterung von existierenden Subtraktionstermen entwickelt, die auf nächst-führender Ordnung benötigt wird. Alle Methoden werden analysiert im Bezug auf Effizienz, Genauigkeit und Implementierbarkeit, und anschließend verglichen. Dabei zeigt eine Methode klare Vorteile vor allen anderen.
Subjects/Keywords: Helizitätsmethode, Subtraktionsmethode, Numerische Methoden; Helicity method, subtraction method, numerical methods, random polarizations; Physics
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APA ·
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APA (6th Edition):
Götz, D. (2014). Helicity methods in LO and NLO QCD calculations. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
Chicago Manual of Style (16th Edition):
Götz, Daniel. “Helicity methods in LO and NLO QCD calculations.” 2014. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed September 23, 2019.
http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/.
MLA Handbook (7th Edition):
Götz, Daniel. “Helicity methods in LO and NLO QCD calculations.” 2014. Web. 23 Sep 2019.
Vancouver:
Götz D. Helicity methods in LO and NLO QCD calculations. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2014. [cited 2019 Sep 23].
Available from: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/.
Council of Science Editors:
Götz D. Helicity methods in LO and NLO QCD calculations. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2014. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2014/3856/
Michigan Technological University
23.
Schaefer, Lauren N.
Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala.
Degree: MS, Department of Geological and Mining Engineering and Sciences, 2012, Michigan Technological University
URL: http://digitalcommons.mtu.edu/etds/470
► The continual eruptive activity, occurrence of an ancestral catastrophic collapse, and inherent geologic features of Pacaya volcano (Guatemala) demands an evaluation of potential collapse…
(more)
▼
The continual eruptive activity, occurrence of an ancestral catastrophic collapse, and inherent geologic features of Pacaya volcano (Guatemala) demands an evaluation of potential collapse hazards. This thesis merges techniques in the field and laboratory for a better rock mass characterization of volcanic slopes and slope stability evaluation. New field geological, structural, rock mechanical and geotechnical data on Pacaya is reported and is integrated with laboratory tests to better define the physical-mechanical rock mass properties. Additionally, this data is used in
numerical models for the quantitative evaluation of lateral instability of large sector collapses and shallow landslides. Regional tectonics and local structures indicate that the local stress regime is transtensional, with an ENE-WSW sigma 3 stress component. Aligned features trending NNW-SSE can be considered as an expression of this weakness zone that favors magma upwelling to the surface.
Numerical modeling suggests that a large-scale collapse could be triggered by reasonable ranges of magma pressure (greater than or equal to 7.7 MPa if constant along a central dyke) and seismic acceleration (greater than or equal to 460 cm/s2), and that a layer of pyroclastic deposits beneath the edifice could have been a factor which controlled the ancestral collapse. Finally, the formation of shear cracks within zones of maximum shear strain could provide conduits for lateral flow, which would account for long lava flows erupted at lower elevations.
Advisors/Committee Members: Thomas Oommen.
Subjects/Keywords: Finite Element Method; Limit Equilibrium Method; Numerical Modeling; Pacaya Volcano; Volcanic slope stability; Geology
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Schaefer, L. N. (2012). Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala. (Masters Thesis). Michigan Technological University. Retrieved from http://digitalcommons.mtu.edu/etds/470
Chicago Manual of Style (16th Edition):
Schaefer, Lauren N. “Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala.” 2012. Masters Thesis, Michigan Technological University. Accessed September 23, 2019.
http://digitalcommons.mtu.edu/etds/470.
MLA Handbook (7th Edition):
Schaefer, Lauren N. “Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala.” 2012. Web. 23 Sep 2019.
Vancouver:
Schaefer LN. Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala. [Internet] [Masters thesis]. Michigan Technological University; 2012. [cited 2019 Sep 23].
Available from: http://digitalcommons.mtu.edu/etds/470.
Council of Science Editors:
Schaefer LN. Geotechnical Data and Numerical Analysis of Edifice Collapse and Related Hazards at Pacaya Volcano, Guatemala. [Masters Thesis]. Michigan Technological University; 2012. Available from: http://digitalcommons.mtu.edu/etds/470
Univerzitet u Beogradu
24.
Džindo, Emina, 1973-.
Развој прслине заварених хетерогених спојева.
Degree: Mašinski fakultet, 2018, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
► Област техничких наука, машинство - Технологија материјала, механика лома / technical science - materials and technology, fracture mechanics
Експериментално анализирање раста прслине у појединим конституентима…
(more)
▼ Област техничких наука, машинство - Технологија
материјала, механика лома / technical science - materials and
technology, fracture mechanics
Експериментално анализирање раста прслине у
појединим конституентима завареннх спојева комплексно легираннх
челика високе чврстоће на епруветама и у реалним конструкцијама,
као и утицај раста прслине на сигурност завареног споја управо је
циљ овог рада. Да би се омогуhило заваривање таквих конструкцијских
челика, додатни материјал за заваривање се пројектује тако да метал
шава након заваривања има нешто мању чврстоћу од основног метала
(андермечинг ефект). У тако завареном споју до пластичног течења ће
доћи прво у металу шава. Тек након ојачавања МШ до нивоа границе
течења ОМ долази до ппастичног деформисања ОМ. Циљ овог рада је да
се покажу нумерички модели, допринос анализи проблема из референтне
области који се састоји управо у могућности да се на брз и
релативно једноставан начин развоја модела који ће на меродаван
начин представити реално понашање епрувета,, у погледу
концентрације напона и поља деформацијатоком релевантних
оптерећења. Нумеричком анализом могуће је приказати и ширење
прслине, односно промена њене дужине у односу на иницијалну
вредност од 2.3 mm. Ови резултати се такође могу искористити и као
основа за будућа истраживања, која би могла да се баве испитивањем
понашања оваквих епрувета на заморно оптерећење, с обзиром да су
посуде под притиском (област примене оваквих материјала) управо
изложене оваквом оптерећењу и најчешће отказују услед истог. Дакле,
прво су примењене метода коначних елемената као нумеричка метода,
као и две експерименталне методе метода мерних трака и метода за
дигиталну корелацију слика. Детаљно је сакупљена, проучена и
систематизована научна литература из области везана за све аспекте
ове дисертације. Анализирана је разлика у понашању завареног споја
као целине и његових конституената и затезањем су испитане епрувете
са металом шава мање и веће чврстоће у односу на основни метал што
је важно и за оцену отпорности према ширењу прслине, даје основне
податке о понашању материјала при оптерећивању...
Advisors/Committee Members: Radaković, Zoran, 1961-.
Subjects/Keywords: heterogenous welded joint; undermatching; finite
element method; strength; numerical simulation; plastic
deformation; strain gauge method
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APA (6th Edition):
Džindo, Emina, 1. (2018). Развој прслине заварених хетерогених спојева. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
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):
Džindo, Emina, 1973-. “Развој прслине заварених хетерогених спојева.” 2018. Thesis, Univerzitet u Beogradu. Accessed September 23, 2019.
https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Džindo, Emina, 1973-. “Развој прслине заварених хетерогених спојева.” 2018. Web. 23 Sep 2019.
Vancouver:
Džindo, Emina 1. Развој прслине заварених хетерогених спојева. [Internet] [Thesis]. Univerzitet u Beogradu; 2018. [cited 2019 Sep 23].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Džindo, Emina 1. Развој прслине заварених хетерогених спојева. [Thesis]. Univerzitet u Beogradu; 2018. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:19042/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Université de Bordeaux I
25.
Trova, Audrey.
Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks.
Degree: Docteur es, Astrophysique, 2013, Université de Bordeaux I
URL: http://www.theses.fr/2013BOR14902
► La gravitation joue un rôle important dans de nombreux domaines de l'astrophysique : elle assure notamment la cohésion et la stabilité des planètes, des étoiles…
(more)
▼ La gravitation joue un rôle important dans de nombreux domaines de l'astrophysique : elle assure notamment la cohésion et la stabilité des planètes, des étoiles et des disques. Elle est aussi motrice dans le processus d'effondrement de structure et conduit, dès lors qu'un moment cinétique initial est significatif, à la formation d'un disque.Ma thèse est consacrée à l'étude des disques de gaz, et plus particulièrement à la description du potentiel et du champ de gravité qu'ils génèrent dans l'espace et sur eux-mêmes (l'auto-gravitation). Bien que la force de Newton soit connue depuis longtemps, la détermination des interactions auto-gravitantes reste difficile, en particulier lorsque l'on s'écarte significativement de la sphéricité. La principale difficulté tient dans la divergence hyperbolique du Noyau de Green 1/(r'-r) et nécessite un traitement propre. L'approche théorique est intéressante car elle fournit de nouveaux outils (techniques numériques, formules approchées, etc...) qui peuvent aider à produire des solutions de référence et à améliorer les simulations numériques.Dans une première partie, nous introduisons le sujet, les notions et les bases essentielles. Le chapitre 1 est consacré à une présentation succinte du contexte scientifique et aux motivations de notre travail. Dans le chapitre 2, nous reproduisons dans ces grandes lignes le cheminement conduisant au développement multipolaire, à partir de l'équation de Poisson et de la formule intégrale de Newton. Il s'agit de l'une des méthodes les plus classiques permettant d'obtenir le potentiel gravitationnel d'un corps. Les deux systèmes de coordonnées les plus utilisées sont mis en avant : sphériques et cylindriques. A travers quelques exemples, nous montrons les limites de cette approche, en particulier dans le cas de l'auto-gravité des disques.Dans une deuxième partie, nous abordons le vif du sujet. Le chapitre 3 présente l'approche basée sur les intégrales elliptiques que nous retrouverons dans l'ensemble du manuscrit (cas général d'abord, puis cas axi-symétrique). Dans le chapitre 4, nous établissons un premier résultat concernant le noyau de Green dans des systèmes axi-symétriques et verticalement homogènes : une forme alternative et régulière du noyau, quelque soit le point de l'espace. Nous avons exploité cette nouvelle formule pour déduire une bonne approximation du potentiel des disques géométriquement minces, des anneaux et des systèmes faiblement étendus en rayon. Ceci fait l'objet du chapitre 5.Dans une troisième partie, nous étudions les effets de bords sur la composante verticale du champ de gravité, g
z, causés par un disque mince axi-symétrique. Le chapitre 6 est dédié à l'approximation de Paczynski \citep{pacz78}, qui permet traditionnellement d'exprimer le champ comme une fonction linéaire de la densité de surface locale. Cette approximation n'est en fait strictement valide que dans le cas du modèle du "plan infini", loin d'un disque réaliste. Près du bord externe des disques où la gravité décroit, l'approximation de…
Advisors/Committee Members: Huré, Jean-Marc (thesis director), Hersant, Franck (thesis director).
Subjects/Keywords: Gravitation; Disque d'accretion; Methode analytique; Methode numérique; Gravitation; Accretion disk; Analytical method; Numerical method
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Trova, A. (2013). Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks. (Doctoral Dissertation). Université de Bordeaux I. Retrieved from http://www.theses.fr/2013BOR14902
Chicago Manual of Style (16th Edition):
Trova, Audrey. “Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks.” 2013. Doctoral Dissertation, Université de Bordeaux I. Accessed September 23, 2019.
http://www.theses.fr/2013BOR14902.
MLA Handbook (7th Edition):
Trova, Audrey. “Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks.” 2013. Web. 23 Sep 2019.
Vancouver:
Trova A. Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks. [Internet] [Doctoral dissertation]. Université de Bordeaux I; 2013. [cited 2019 Sep 23].
Available from: http://www.theses.fr/2013BOR14902.
Council of Science Editors:
Trova A. Gravité des systèmes verticalement homogènes : applications aux disques astrophysiques : Gravity of vertically homogeneous systems : application to astrophysical disks. [Doctoral Dissertation]. Université de Bordeaux I; 2013. Available from: http://www.theses.fr/2013BOR14902
Virginia Tech
26.
Pasareanu, Stephanie.
A numerical hybrid method for modeling outdoor sound propagation in complex urban environments.
Degree: MS, Mechanical Engineering, 2014, Virginia Tech
URL: http://hdl.handle.net/10919/47601
► Prediction of the sound field in large urban environments has been limited thus far by the heavy computational requirements of conventional numerical methods such as…
(more)
▼ Prediction of the sound field in large urban environments has been limited thus far by the heavy computational requirements of conventional
numerical methods such as boundary element (BE), finite-difference time-domain (FDTD), or ray-tracing methods. Recently, a considerable amount of work has been devoted to developing energy-based methods for this application, and results have shown the potential to compete with conventional methods. However, these developments have been limited to two-dimensional (2-D) studies (along street axes), and no real description of the phenomena at issue has been exposed (e.g., diffraction effects on the predictions).
The main objectives of the present work were (i) to evaluate the feasibility of an energy-based
method, the diffusion model (DM), for sound-field predictions in large, 3-D complex urban environments, (ii) to propose a
numerical hybrid
method that could improve the accuracy and computational time of these predictions, and (iii) to verify the proposed hybrid
method against conventional
numerical methods.
The proposed
numerical hybrid
method consists of a full-wave model coupled with an energy-based model. The full-wave model is used for predicting sound propagation (i) near the source, where constructive and destructive interactions between waves are substantial, and (ii) outside the cluttered environment, where free-field-like conditions apply. The energy-based model is used in regions where diffusion conditions are met. The hybrid approach, as implemented in this work, is a combination of FDTD and DM models.
Results from this work show the role played by diffraction near buildings edges close to the source and near the exterior boundaries of the computational domain, and its impact on the predictions. A wrong modeling of the diffraction effects in the environment leads to significant under or overpredictions of the sound levels in some regions, as compared to conventional
numerical methods (in these regions, some differences are as high as 10 dB). The implementation of the hybrid
method, verified against a full FDTD model, shows a significant improvement of the predictions. The mean error thus obtained inside the cluttered region of the environment is 1.5 dB.
Advisors/Committee Members: Inman, Daniel J. (committeechair), Burdisso, Ricardo A. (committeechair), Roan, Michael J. (committee member).
Subjects/Keywords: outdoor sound propagation; FDTD; energy-based method; energy density; geometrical acoustics; numerical hybrid method
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Pasareanu, S. (2014). A numerical hybrid method for modeling outdoor sound propagation in complex urban environments. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/47601
Chicago Manual of Style (16th Edition):
Pasareanu, Stephanie. “A numerical hybrid method for modeling outdoor sound propagation in complex urban environments.” 2014. Masters Thesis, Virginia Tech. Accessed September 23, 2019.
http://hdl.handle.net/10919/47601.
MLA Handbook (7th Edition):
Pasareanu, Stephanie. “A numerical hybrid method for modeling outdoor sound propagation in complex urban environments.” 2014. Web. 23 Sep 2019.
Vancouver:
Pasareanu S. A numerical hybrid method for modeling outdoor sound propagation in complex urban environments. [Internet] [Masters thesis]. Virginia Tech; 2014. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/10919/47601.
Council of Science Editors:
Pasareanu S. A numerical hybrid method for modeling outdoor sound propagation in complex urban environments. [Masters Thesis]. Virginia Tech; 2014. Available from: http://hdl.handle.net/10919/47601
University of Ottawa
27.
Fu, Jingyi J.Y.
Delay Analysis of Digital Circuits Using Prony's Method
.
Degree: 2011, University of Ottawa
URL: http://hdl.handle.net/10393/20125
► This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in…
(more)
▼ This thesis describes possible applications of Prony's method in timing analysis of digital circuits. Such applications include predicting the future shape of the waveform in DTA(Dynamic Timing Analysis) and delay look-up table in STA(Static Timing Analysis).
Given some equally spaced output values, the traditional Prony's method can be used to extract poles and residues of a linear system, i.e. to characterize a waveform using an exponential function. In this thesis, not only values but also equally spaced derivatives are tested. Still using same idea of the traditional Prony's method, poles and residues can also be extracted with those values and derivatives. The resultant poles and residues will be used to predict the output waveform in DTA analysis. The benefits brought by the using of derivatives include less simulation steps and less CPU time consuming than the regular constant step simulation.
As a matter of fact, the Prony's method can precisely approximate a complicated waveform. Such property can be applied for STA analysis. The Prony's approximation can be used to precisely record an output waveform, which is used as an entry of the look-up table of STA. Since the accuracy of STA analysis relies on the accuracy of the input and output waveform in the look-up table, the accuracy of the Prony's approach is promising.
Subjects/Keywords: Prony's method;
Timing Analysis;
Obreshokov;
numerical method;
Dynamic Timing Analysis (DTA);
Static Timing Analysis (STA)
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Manager
APA (6th Edition):
Fu, J. J. Y. (2011). Delay Analysis of Digital Circuits Using Prony's Method
. (Thesis). University of Ottawa. Retrieved from http://hdl.handle.net/10393/20125
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):
Fu, Jingyi J Y. “Delay Analysis of Digital Circuits Using Prony's Method
.” 2011. Thesis, University of Ottawa. Accessed September 23, 2019.
http://hdl.handle.net/10393/20125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Fu, Jingyi J Y. “Delay Analysis of Digital Circuits Using Prony's Method
.” 2011. Web. 23 Sep 2019.
Vancouver:
Fu JJY. Delay Analysis of Digital Circuits Using Prony's Method
. [Internet] [Thesis]. University of Ottawa; 2011. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/10393/20125.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Fu JJY. Delay Analysis of Digital Circuits Using Prony's Method
. [Thesis]. University of Ottawa; 2011. Available from: http://hdl.handle.net/10393/20125
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Urbana-Champaign
28.
Uddin, Hasib.
Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow.
Degree: PhD, 0242, 2014, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/50381
► The delivery of fusion material to the center of a laser inertial confinement engine happens by injecting a frozen hydrogen isotope mixture that resides inside…
(more)
▼ The delivery of fusion material to the center of a laser inertial confinement engine happens
by injecting a frozen hydrogen isotope mixture that resides inside a carefully crafted capsule
called hohlraum. Because of the injection mechanism, the capsule necessarily has the shape of a modified short cylinder traveling along its axis of symmetry. The flow details and stability of this geometry are of significant importance to the reliable operation of the device. The gas inside the fusion chamber is very hot and the viscosity is relatively high, which for the typical injection velocities of the capsule results in a low Reynolds number flow.
In this connection, a low Reynolds number compressible flow past a dynamically moving rigid short cylinder has been investigated using three-dimensional direct
numerical simulation (DNS) as a model of the real capsule. A Cartesian-based novel embedded geometry
method for compressible
fluid-structure interaction problems is developed and coupled with a low-
numerical-dissipation compressible flow solver to perform simulations in a parallel multiprocessor environment. In this
method, the surface of the cylinder is uniquely identified
by a zero level set separating the
fluid and solid region. A PDE-based global extension technique inspired by analytical continuation is used to smoothly propagate the surface boundary conditions inside the fictitious solid domain. This approach ensures smooth and noise-free reconstruction of pressure and viscous stresses on the surface of the solid body and utilization of a global high-order spatial discretization scheme due to the smooth nature of the flow quantities at each time step stage. The translational and rotational dynamics of the cylinder by modeling the 6-degree of freedom (DoF) motion employ a non-singular quaternion-based framework. The longitudinal stability of the cylinder is affected by the variation in angle of attack, aspect ratio and Reynolds number. The present work focuses on Reynolds number, Re = 60 and a Mach number, M = 0.25 to closely mimic the flow conditions
inside an inertial confinement fusion chamber. A critical angle of attack has been identified beyond which the short cylinder will start to tumble based on a set of stationary simulations. Additionally, the force coefficients and pitching moments from coupled moving boundary simulations are investigated.
Advisors/Committee Members: Pantano-Rubino, Carlos A. (advisor), Pantano-Rubino, Carlos A. (Committee Chair), Christensen, Kenneth T. (committee member), Vakakis, Alexander F. (committee member), Bodony, Daniel J. (committee member).
Subjects/Keywords: Embedded geometry method; immersed boundary method; fluid-structure interaction; direct numerical simulation; tumbling cylinder
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Uddin, H. (2014). Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/50381
Chicago Manual of Style (16th Edition):
Uddin, Hasib. “Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow.” 2014. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed September 23, 2019.
http://hdl.handle.net/2142/50381.
MLA Handbook (7th Edition):
Uddin, Hasib. “Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow.” 2014. Web. 23 Sep 2019.
Vancouver:
Uddin H. Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2014. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/2142/50381.
Council of Science Editors:
Uddin H. Direct numerical simulation of a tumbling short cylinder in low Reynolds number compressible flow. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2014. Available from: http://hdl.handle.net/2142/50381
New Jersey Institute of Technology
29.
Ma, Manman.
A numerical method for electro-kinetic flow with deformable interfaces.
Degree: PhD, Mathematical Sciences, 2013, New Jersey Institute of Technology
URL: https://digitalcommons.njit.edu/dissertations/372
► We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid-fluid interface, a screening cloud of…
(more)
▼ We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid-fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or ‘Debye layer’. The applied electric field acts on the ionic cloud it induces, resulting in a strong slip flow near the interface. This is known as ‘induced-charge electro-kinetic flow’, and is an important phenomenon in microfluidic applications and in the manipulation of biological cells. The models with two different cases including the fast or slow charging time scales are studied both analytically and numerically. We address a significant challenge in the
numerical computation of such flows in the thin-double-layer limit, by using the slenderness of the layer to develop a fast and accurate ‘hybrid’ or multiscale
numerical method. The
method incorporates an asymptotic analysis of the electric potential and fluid dynamics in the Debye layer into a boundary integral
numerical solution of the full moving boundary problem.
We present solutions for the quasi-steady state problem with ψ = O(1) and solutions for the time dependent problem with ψ « 1, where ψ is the dimensionless surface potential. Leading order problems for both electric fields and fluid fields are solved with boundary conditions and matching methods. The small deformation theories when Ca is small (Ca is the electric capillary number) for both quasi-steady state and time dependent problems are developed to check
numerical simulations.
Advisors/Committee Members: Michael Siegel, Michael R. Booty, Linda Jane Cummings.
Subjects/Keywords: Electro-kinetics; Hybrid numerical method; Moving boundary problem; Asymptotics; Small deformation; Boundary integral method; Mathematics
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APA ·
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Export
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Manager
APA (6th Edition):
Ma, M. (2013). A numerical method for electro-kinetic flow with deformable interfaces. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/372
Chicago Manual of Style (16th Edition):
Ma, Manman. “A numerical method for electro-kinetic flow with deformable interfaces.” 2013. Doctoral Dissertation, New Jersey Institute of Technology. Accessed September 23, 2019.
https://digitalcommons.njit.edu/dissertations/372.
MLA Handbook (7th Edition):
Ma, Manman. “A numerical method for electro-kinetic flow with deformable interfaces.” 2013. Web. 23 Sep 2019.
Vancouver:
Ma M. A numerical method for electro-kinetic flow with deformable interfaces. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2013. [cited 2019 Sep 23].
Available from: https://digitalcommons.njit.edu/dissertations/372.
Council of Science Editors:
Ma M. A numerical method for electro-kinetic flow with deformable interfaces. [Doctoral Dissertation]. New Jersey Institute of Technology; 2013. Available from: https://digitalcommons.njit.edu/dissertations/372
Queens University
30.
Jabbari Sahebari, Aidin.
ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
.
Degree: Civil Engineering, 2015, Queens University
URL: http://hdl.handle.net/1974/13568
► The accuracy of the inertial dissipation method (IDM), commonly applied to estimate the observed rate of turbulent dissipation in bottom boundary layers (BBL), is evaluated…
(more)
▼ The accuracy of the inertial dissipation method (IDM), commonly applied to estimate the observed rate of turbulent dissipation in bottom boundary layers (BBL), is evaluated by performing direct numerical simulations (DNS) and large eddy simulations (LES) of unidirectional turbulent channel flows. Errors in the IDM occur as the mean velocity is commonly used for the convection velocity and when the canonical Kolmogorov -5/3 constants, which assume isotropy and homogeneity of the flow, are applied. The optimal convection velocity, as previously shown by many researchers, is found to be 2 times greater than the local mean velocity near the bed and the Kolmogorov constants are significantly affected by anisotropy. Usage of the canonical Kolmogorov constants leads to significant errors (>50%) in computation of dissipation.
Using the same DNS and LES data, the accuracy of Kolmogorov 2/3 constants, used in the structure function method (SFM) to compute dissipation, is also investigated. As with the IDM, comparison of the dissipation, calculated directly from DNS/LES with that from the SFM, shows that usage of canonical constants results in considerable error (>50%) from the vertical or spanwise velocity components. Application of anisotropy-adjusted constants to data from the BBL of Lake Erie shows that these constants improve computed dissipation by a factor of two, with results within 20% of published dissipation obtained from the Batchelor fitting method.
DNS and LES of oscillating turbulent flows were also carried out to calibrate and evaluate common analytical models used in oscillatory BBLs in lakes and costal oceans. These include the log-law, Stokes second problem, the IDM, and a one-equation Spalart-Allmaras model. Velocity profile predictions from the Spalart-Allmaras model were found to be more accurate than those from the log-law and Stokes’ second problem. Comparison of the LES data and the turbulence models, with published field measurements, shows that the rate of dissipation from the IDM is more accurate than that obtained from the log-law, particularly when the flow reverses. The differences between the IDM and LES suggest that the errors in prediction of dissipation can be due to the anisotropy conditions in the BBL.
Subjects/Keywords: Structure function method;
Direct numerical simulations;
Inertial dissipation method;
Large eddy simulations;
Boundary layers
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APA (6th Edition):
Jabbari Sahebari, A. (2015). ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
. (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/13568
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):
Jabbari Sahebari, Aidin. “ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
.” 2015. Thesis, Queens University. Accessed September 23, 2019.
http://hdl.handle.net/1974/13568.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Jabbari Sahebari, Aidin. “ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
.” 2015. Web. 23 Sep 2019.
Vancouver:
Jabbari Sahebari A. ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
. [Internet] [Thesis]. Queens University; 2015. [cited 2019 Sep 23].
Available from: http://hdl.handle.net/1974/13568.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Jabbari Sahebari A. ANALYSIS OF IDEALIZED NUMERICAL SIMULATIONS TO CALIBRATE AND VALIDATE BOUNDARY LAYER MODELS
. [Thesis]. Queens University; 2015. Available from: http://hdl.handle.net/1974/13568
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
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