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Oregon State University
1.
Costa, Timothy B.
Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science.
Degree: PhD, Mathematics, 2016, Oregon State University
URL: http://hdl.handle.net/1957/59138 
► In this work we consider two multiscale applications with tremendous computational complexity at the lower scale. First, we examine a model for charge transport in…
(more)
▼ In this work we consider two
multiscale applications with tremendous computational
complexity at the lower scale. First, we examine a model for charge transport in semicon-
ductor structures with heterojunction interfaces. Due to the complex physical phenomena
at the interface, the model at the design scale is unable to adequately capture the behavior
of the structure in the interface region. Simultaneously it is computationally intractable to
simulate the full heterostructure on the scale required near the interface. Second, we con-
sider the problem of the simulation of fluid flow in a dynamically evolving porous medium.
The evolution of the medium strongly couples the porescale flow solutions and the macro
scale model, requiring a novel approach to communicate the porescale evolution to the
macroscale without resorting to the intractable simulation of the fluid flow problem di-
rectly on the porescale geometry. We formulate novel methods for these two applications
in the
multiscale framework. For the semiconductor problem we present iterative sub-
structuring domain decomposition methods that decouple the interface computation from
the macroscale model. For the fluid flow problem we develop a reduced order three-scale
fluid flow model based on a spatial decomposition of the porescale geometry and the offline
approximation of a stochastic process describing macroscale permeability paramaterized
by the volume fraction of the evolved geometry.
Advisors/Committee Members: Peszynska, Malgorzata (advisor), Showalter, Ralph (committee member).
Subjects/Keywords: Multiscale modeling
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APA (6th Edition):
Costa, T. B. (2016). Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/59138
Chicago Manual of Style (16th Edition):
Costa, Timothy B. “Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science.” 2016. Doctoral Dissertation, Oregon State University. Accessed March 01, 2021.
http://hdl.handle.net/1957/59138.
MLA Handbook (7th Edition):
Costa, Timothy B. “Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science.” 2016. Web. 01 Mar 2021.
Vancouver:
Costa TB. Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science. [Internet] [Doctoral dissertation]. Oregon State University; 2016. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1957/59138.
Council of Science Editors:
Costa TB. Hybrid Multiscale Methods with Applications to Semiconductors, Porous Media, and Materials Science. [Doctoral Dissertation]. Oregon State University; 2016. Available from: http://hdl.handle.net/1957/59138
2.
Wang, Wei.
Multiscale discontinuous Galerkin methods and
applications.
Degree: PhD, Applied Mathematics, 2008, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:259/
► This thesis contains three related topics on the multiscale discontinuous Galerkin (DG) methods and applications. In the first part, we present a multiscale model for…
(more)
▼ This thesis contains three related topics on the
multiscale discontinuous Galerkin (DG) methods and applications. In
the first part, we present a
multiscale model for numerical
simulation of dynamics of crystalline solids. The method couples
nonlinear elastodynamics as the continuum description and molecular
dynamics as another component at the atomic scale. The governing
equations on the macroscale are solved by the DG method, which is
built up with an appropriate local curl-free space to produce a
coherent displacement field. In the second part, we develop a
multiscale local discontinuous Galerkin (LDG) method to simulate
the 1-D stationary Schrödinger-Poisson problem. The WKB-LDG
method is proposed for solving the Schrödinger equation and
provides a significant reduction of both the computational cost and
memory. It has the advantages of the DG methods including their
flexibility in h-p adaptivity and the allowance of complete
discontinuity at element interfaces compared with a traditional
continuous finite element Galerkin methodology. In the third part,
we develop a
multiscale DG method for solving a class of second
order elliptic problems with rough coefficients based on the
previous work of Yuan and Shu . The main ingredient of
this method is to use a non-polynomial
multiscale approximation
space in the DG method to capture the solutions without resolving
the fine-scale structure of the solution. We generalize the
analysis of the
multiscale Babu\v{s}ka-Zl\'amal DG method to the
case of u∈ H
1([0,1]). We also propose a
multiscale local
discontinuous Petrov-Galerkin method and a
multiscale interior
penalty DG method in the numerical tests.
Advisors/Committee Members: Shu, Chi-Wang (director), Gottlieb, David (reader), Hesthaven, Jan (reader).
Subjects/Keywords: multiscale
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APA (6th Edition):
Wang, W. (2008). Multiscale discontinuous Galerkin methods and
applications. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:259/
Chicago Manual of Style (16th Edition):
Wang, Wei. “Multiscale discontinuous Galerkin methods and
applications.” 2008. Doctoral Dissertation, Brown University. Accessed March 01, 2021.
https://repository.library.brown.edu/studio/item/bdr:259/.
MLA Handbook (7th Edition):
Wang, Wei. “Multiscale discontinuous Galerkin methods and
applications.” 2008. Web. 01 Mar 2021.
Vancouver:
Wang W. Multiscale discontinuous Galerkin methods and
applications. [Internet] [Doctoral dissertation]. Brown University; 2008. [cited 2021 Mar 01].
Available from: https://repository.library.brown.edu/studio/item/bdr:259/.
Council of Science Editors:
Wang W. Multiscale discontinuous Galerkin methods and
applications. [Doctoral Dissertation]. Brown University; 2008. Available from: https://repository.library.brown.edu/studio/item/bdr:259/
3.
Raghunathan, Smitha.
Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression.
Degree: 2010, Wake Forest University
URL: http://hdl.handle.net/10339/14888
► Crash injury prevention research has yielded many preventative measures that work in conjunction to protect vital areas of the human body. However, some of these…
(more)
▼ Crash injury prevention research has yielded many preventative measures that work in conjunction to protect vital areas of the human body. However, some of these methods of fatality prevention have been shown to increase injury frequency in other areas of the body, including the abdomen. Within the abdomen, the liver is particularly prone to injury due to its size and relatively fixed position. One known mode of injury to this organ is burst injury, caused by rapidly increasing fluid pressure within this highly vascular organ. Exploration of this type of injury has shown fluid pressure to correlate well to liver injury severity in perfused whole-organ rapid compression testing. This study aimed to address one level of liver multi-scale testing by conducting unconfined compression tests on unperfused and perfused tissue blocks. This data was then used in model development, leading to finite element models capable of predicting mechanical and fluid response in tissue specimens. This strategy serves as the foundation to future testing and model development, working towards higher compression rates, larger deformation and increased geometric complexity. The eventual goal is the integration of a liver model into a whole body model, allowing the advancement of high-fidelity virtual crash test dummies and improved vehicle safety.
Subjects/Keywords: Multiscale
…equipment for sports, military and motor
vehicles applications.
Key Words
Multiscale, mechanical… …wealth of multiscale
information will be expanded and synthesized in new ways to create… …their inherent multiscale nature. Next-generation dummies will be
responsible for simulating… …cellular level.
2.2 Methods for Multiscale Characterization of Liver
The sampling of methods… …outlined below was selected to illustrate the multiscale
biomechanical characterization of liver…
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APA (6th Edition):
Raghunathan, S. (2010). Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression. (Thesis). Wake Forest University. Retrieved from http://hdl.handle.net/10339/14888
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):
Raghunathan, Smitha. “Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression.” 2010. Thesis, Wake Forest University. Accessed March 01, 2021.
http://hdl.handle.net/10339/14888.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Raghunathan, Smitha. “Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression.” 2010. Web. 01 Mar 2021.
Vancouver:
Raghunathan S. Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression. [Internet] [Thesis]. Wake Forest University; 2010. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/10339/14888.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Raghunathan S. Poroviscoelastic Modeling of the Mechanical and Fluid Response of Liver Tissue in Unconfined Compression. [Thesis]. Wake Forest University; 2010. Available from: http://hdl.handle.net/10339/14888
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Manchester
4.
Gowers, Richard.
Developing dual-scale models for structured liquids and
polymeric materials.
Degree: 2016, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:301532
► Computer simulation techniques for exploring the microscopic world are quickly gaining popularity as a tool to complement theoretical and experimental approaches. Molecular dynamics (MD) simulations…
(more)
▼ Computer simulation techniques for exploring the
microscopic world are quickly gaining popularity as a tool to
complement theoretical and experimental approaches. Molecular
dynamics (MD) simulations allow the motion of an N–body soft matter
system to be solved using a classical mechanics description. The
scope of these simulations are however limited by the available
computational power, requiring the development of
multiscale
methods to make better use of available resources.Dual scale models
are a novel form of molecular model which simultaneously feature
particles at two levels of resolution. This allows a combination of
atomistic and coarse-grained (CG) force fields to be used to
describe the interactions between particles. By using this
approach, targeted details in a molecule can be described at high
resolution while other areas are treated with fewer degrees of
freedom. This approach aims to allow for simulating the key
features of a system at a reduced computational cost. In this
thesis, two generations of a methodology for constructing dual
scale models are presented and applied to various materials
including polyamide, polyethene, polystyrene and octanol. Alongside
a variety of well known atomistic force fields, these models all
use iterative Boltzmann inversion (IBI) force fields to describe
the CG interactions. In addition the algorithms and data structures
for implementing dual scale MD are detailed, and expanded to
include a multiple time step (MTS) scheme for optimising its
peformance.Overall the IBI and atomistic force fields were
compatible with each other and able to correctly reproduce the
expected structural results. The first generation methodology
featured bonds directly between atoms and beads, however these did
not produce the correct structures. The second generation used only
atomistic resolution bonds and this improved the intramolecular
structures greatly for a relatively minor cost. In both the
polyamide and octanol systems studied, the models were also able to
properly describe the hydrogen bonding. For the CG half of the
force field, it was possible to either use preexisting force field
parameters or develop new parameters in situ. The resulting
dynamical behaviour of the models was unpredictable and remains an
open question both for CG and dual scale models.The theoretical
performance of these models is faster than the atomistic
counterpart because of the reduced number of pairwise interactions
that must be calculated and this scaling was seen with the proposed
reference implementation. The MTS scheme was successful in
improving the performance with no effects on the quality of
results. In summary this work has shown that dual scale models are
able to correctly reproduce the structural behaviour of atomistic
models at a reduced computational cost. With further steps towards
making these models more accessible, they will become an exciting
new option for many types of simulation.
Advisors/Committee Members: SIPERSTEIN, FLOR F, Siperstein, Flor, Carbone, Paola.
Subjects/Keywords: molecular dynamics; multiscale
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APA (6th Edition):
Gowers, R. (2016). Developing dual-scale models for structured liquids and
polymeric materials. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:301532
Chicago Manual of Style (16th Edition):
Gowers, Richard. “Developing dual-scale models for structured liquids and
polymeric materials.” 2016. Doctoral Dissertation, University of Manchester. Accessed March 01, 2021.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:301532.
MLA Handbook (7th Edition):
Gowers, Richard. “Developing dual-scale models for structured liquids and
polymeric materials.” 2016. Web. 01 Mar 2021.
Vancouver:
Gowers R. Developing dual-scale models for structured liquids and
polymeric materials. [Internet] [Doctoral dissertation]. University of Manchester; 2016. [cited 2021 Mar 01].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:301532.
Council of Science Editors:
Gowers R. Developing dual-scale models for structured liquids and
polymeric materials. [Doctoral Dissertation]. University of Manchester; 2016. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:301532
University of Guelph
5.
Newman, Daniel.
Investigating hyperscale terrain analysis metrics and methods.
Degree: MS, Department of Geography, 2018, University of Guelph
URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/13045
► New elevation sampling technology provides digital elevation data at unprecedented resolution. Multiscale analytical methods are becoming increasingly important for meaningful analysis as a result of…
(more)
▼ New elevation sampling technology provides digital elevation data at unprecedented resolution.
Multiscale analytical methods are becoming increasingly important for meaningful analysis as a result of increasingly fine-resolution datasets. However, high computational complexity often limits the feasibility and quality of the analysis. This research sought to investigate and develop metrics and methods for geomorphometric analyses that provide the computational efficiency required of hypercscaled analyses on fine-resolution data. Local topographic position (LTP) metrics are a class of elevation indices that benefit greatly from hyperscale analytical techniques, yet there is little guidance for metric selection in the literature. Four efficiency-optimized algorithms LTP metrics were benchmarked to document their performance. Having established DEV as the optimal metric for hyperscale analysis, it was modified to measure landscape topographic anisotropy using oriented windows. The novel terrain attribute had the sensitivity to detect even complex nested anisotropic features and the efficiency to feasibly sample in hyperscale.
Advisors/Committee Members: Lindsay, John (advisor).
Subjects/Keywords: multiscale; terrain; analysis
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APA (6th Edition):
Newman, D. (2018). Investigating hyperscale terrain analysis metrics and methods. (Masters Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/13045
Chicago Manual of Style (16th Edition):
Newman, Daniel. “Investigating hyperscale terrain analysis metrics and methods.” 2018. Masters Thesis, University of Guelph. Accessed March 01, 2021.
https://atrium.lib.uoguelph.ca/xmlui/handle/10214/13045.
MLA Handbook (7th Edition):
Newman, Daniel. “Investigating hyperscale terrain analysis metrics and methods.” 2018. Web. 01 Mar 2021.
Vancouver:
Newman D. Investigating hyperscale terrain analysis metrics and methods. [Internet] [Masters thesis]. University of Guelph; 2018. [cited 2021 Mar 01].
Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/13045.
Council of Science Editors:
Newman D. Investigating hyperscale terrain analysis metrics and methods. [Masters Thesis]. University of Guelph; 2018. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/13045
University of Utah
6.
Reese, Shawn Peter.
Multiscale structure-function relationships in the mechanical behavior of tendon and ligament.
Degree: PhD, Bioengineering, 2012, University of Utah
URL: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/661/rec/1657
► Ligaments and tendons are dense, fibrous connective tissue that transmit and bear loads within the musculoskeletal system. They are elastic and viscous, and thus are…
(more)
▼ Ligaments and tendons are dense, fibrous connective tissue that transmit and bear loads within the musculoskeletal system. They are elastic and viscous, and thus are capable of storing and dissipating energy. Although soft and flexible, they can interface with materials that are orders of magnitude stiffer (e.g., bone) and orders of magnitude more compliant (e.g., muscle). These functions are mediated by a complex network of hierarchically organized fibrillar collagen and accessory proteins and molecules. Tissue constituents form unique structural motifs that span the nanoscale, microscale, mesoscale and macroscale. This multiscale organization enables both a robust mechanical responseat the macroscopic joint level and simultaneously provides a microscale environment conducive to cellular proliferation and nutrient transport.The aim of this dissertation was to gain a deeper understanding of how the organization of tissue constituents contribute to mechanical function of tendon and ligament across scale levels. At the nanoscale, the question regarding the role of the proteoglycan decorin was addressed. A novel combination of an in vitro assay, imaging techniques and mechanical testing was used to explore how decorin acts to modify thestrength of collagen fibril networks. At the microscale, computational modeling was used to examine how different fibril organizations contribute to the macroscopic volumetric response of tendon and ligament during tensile loading. The volumetric response is believed to drive fluid flux within the tissue, which may play a role in nutrient transport and the apparent viscoelastic response. This flow dependent mechanism was addressed in a study that experimentally measured the volumetric changes in mesocale fascicles during viscoelastic testing. One of the challenges in discerning structure-function relationships in tendon and ligament is the large number of uncontrolled variables, which can be difficult to account for in an experimental setting. To address this challenge, a collagen based tendon surrogate was developed for use as a physical model. The physical model was coupled to a validated micromechanical computational model. This facilitated the testing of hypotheses that would have been difficult to address experimentally. The four studies contained within this dissertation, along with a number of preliminary studies, represent a novel contribution to the field of tendon and ligament mechanics.
Subjects/Keywords: Biomechanics; Ligament; Micromechanical; Multiscale; Tendon
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APA (6th Edition):
Reese, S. P. (2012). Multiscale structure-function relationships in the mechanical behavior of tendon and ligament. (Doctoral Dissertation). University of Utah. Retrieved from http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/661/rec/1657
Chicago Manual of Style (16th Edition):
Reese, Shawn Peter. “Multiscale structure-function relationships in the mechanical behavior of tendon and ligament.” 2012. Doctoral Dissertation, University of Utah. Accessed March 01, 2021.
http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/661/rec/1657.
MLA Handbook (7th Edition):
Reese, Shawn Peter. “Multiscale structure-function relationships in the mechanical behavior of tendon and ligament.” 2012. Web. 01 Mar 2021.
Vancouver:
Reese SP. Multiscale structure-function relationships in the mechanical behavior of tendon and ligament. [Internet] [Doctoral dissertation]. University of Utah; 2012. [cited 2021 Mar 01].
Available from: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/661/rec/1657.
Council of Science Editors:
Reese SP. Multiscale structure-function relationships in the mechanical behavior of tendon and ligament. [Doctoral Dissertation]. University of Utah; 2012. Available from: http://content.lib.utah.edu/cdm/singleitem/collection/etd3/id/661/rec/1657
Mississippi State University
7.
Yu, Jaesang.
MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES.
Degree: PhD, Aerospace Engineering, 2011, Mississippi State University
URL: http://sun.library.msstate.edu/ETD-db/theses/available/etd-04012011-131653/
;
► The Effective Continuum Micromechanics Analysis Code (EC-MAC) was developed for predicting effective properties of composites containing multiple distinct nanoheterogeneities (fibers, spheres, platelets, voids, etc.)…
(more)
▼ The Effective Continuum Micromechanics Analysis Code (EC-MAC) was developed for predicting effective properties of composites containing multiple distinct nanoheterogeneities (fibers, spheres, platelets, voids, etc.) each with an arbitrary number of coating layers based upon either the modified Mori-Tanaka method (MTM) and self consistent method (SCM). This code was used to investigate the effect of carbon nanofiber morphology (i.e., hollow versus solid cross-section), nanofiber waviness, and both nanofiber-resin interphase properties and dimensions on bulk nanocomposite elastic moduli. For a given nanofiber axial force-displacement relationship, the elastic modulus for hollow nanofibers can significantly exceed that for solid nanofibers resulting in notable differences in bulk nanocomposite properties. The development of a nanofiber-resin interphase had a notable effect on the bulk elastic moduli. Consistent with results from the literature, small degrees of nanofiber waviness resulted in a significant decrease in effective composite properties.
Key aspects of nanofiber morphology were characterized using transmission electron microscopy (TEM) images for VGCNF/vinyl ester (VE) nanocomposites. Three-parameter Weibull probability density functions were generated to describe the statistical variation in nanofiber outer diameters, wall thicknesses, relative wall thicknesses, visible aspect ratios, and visible waviness ratios. Such information could be used to establish more realistic nanofiber moduli and strengths obtained from nanofiber tensile tests, as well as to develop physically motivated computational models for predicting nanocomposite behavior. This study represents one of the first attempts to characterize the distribution of VGCNF features in real thermoset nanocomposites.
In addition, the influence of realistic nanoreinforcement geometries, distinct elastic properties, and orientations on the effective elastic moduli was addressed. The effect of multiple distinct heterogeneities, including voids, on the effective elastic moduli was investigated. For the composites containing randomly oriented wavy vapor grown carbon nanofibers (VGCNFs) and voids, the predicted moduli captured the essential character of the experimental data, where the volume fraction of voids was approximated as a nonlinear function of the volume fraction of reinforcements. This study should facilitate the development of
multiscale materials design by providing insight into the relationships between nanomaterial morphology and properties across multiple spatial scales that lead to improved macroscale performance.
Advisors/Committee Members: Thomas E. Lacy (chair), Charles U. Pittman (committee member), Hossein Toghiani (committee member), Judith A. Schneider (committee member), Rani W. Sullivan (committee member).
Subjects/Keywords: polymer nanocomposites; multiscale modeling; micromechanics
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APA (6th Edition):
Yu, J. (2011). MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES. (Doctoral Dissertation). Mississippi State University. Retrieved from http://sun.library.msstate.edu/ETD-db/theses/available/etd-04012011-131653/ ;
Chicago Manual of Style (16th Edition):
Yu, Jaesang. “MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES.” 2011. Doctoral Dissertation, Mississippi State University. Accessed March 01, 2021.
http://sun.library.msstate.edu/ETD-db/theses/available/etd-04012011-131653/ ;.
MLA Handbook (7th Edition):
Yu, Jaesang. “MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES.” 2011. Web. 01 Mar 2021.
Vancouver:
Yu J. MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES. [Internet] [Doctoral dissertation]. Mississippi State University; 2011. [cited 2021 Mar 01].
Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-04012011-131653/ ;.
Council of Science Editors:
Yu J. MICROMECHANICALLY BASED MULTISCALE MATERIAL MODELING OF POLYMER NANOCOMPOSITES. [Doctoral Dissertation]. Mississippi State University; 2011. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-04012011-131653/ ;
Oregon State University
8.
Truszkowska, Agnieszka.
Multiscale modeling of two-phase flows in microarchitectures with microfeatures.
Degree: PhD, Chemical Engineering, 2014, Oregon State University
URL: http://hdl.handle.net/1957/54887
► Two-phase flows in microtechnology based devices are purposefully present in multiphase reactors, phase separators, analytical devices and others. Two-phase flows can also be an undesirable…
(more)
▼ Two-phase flows in microtechnology based devices are purposefully present in multiphase reactors, phase separators, analytical devices and others. Two-phase flows can also be an undesirable side effect occurring during operation due to phase transitions or, more commonly, introduction of surrounding air through equipment gaps and with process feed. In both cases, the two phases require control to achieve desired system performance.
Devices with microfeatures such as posts and pillars represent relatively unexplored design direction with the potential for successful fulfillment of various multi-phase flows objectives. Efficient design of microfeatured devices requires computational tools. However, the importance of two-phase interface physics imposes high resolution computing, which when combined with usual microtechnology high-aspect ratios results in large computational efforts.
Multiscale modeling provides a means for preserving accuracy while lowering computational costs. This thesis proposes a novel
multiscale modeling approach for modeling microarchitectures with microfeatures. The main idea of the approach is to enable numerical simulations of two-phase flows in microfeatured architectures without resolving the actual microfeatures. Effect of microfeatures presence
is incorporated through a coupling operator, vector, or scalar field. Removal of microfeatures allows for modeling with significantly coarser computational grids with grid size being limited by the smallest droplet sizes.
Multiscale modeling approach is accompanied by a piecewise modeling concept in which characterization of the entire microarchitecture is performed with smaller, and hence computationally less intensive, representative domains. Piecewise modeling can be used as a replacement for full-size architecture simulations in
multiscale modeling but can also serve as an independent modeling tool.
The basic framework of the proposed approach is developed based on the example of droplet retention times in microfeatured architectures. This approach is successfully incorporated into Shan and Chen Lattice Boltzmann method, validated and applied to three different architectures. Demonstrated are the capabilities and challenges of the proposed
multiscale modeling approach. Viability and potential improvements of piecewise modeling are also confirmed.
Advisors/Committee Members: Jovanovic, Goran N. (advisor), Apte, Sourabh (committee member).
Subjects/Keywords: multiscale modeling; Two-phase flow
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APA ·
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APA (6th Edition):
Truszkowska, A. (2014). Multiscale modeling of two-phase flows in microarchitectures with microfeatures. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/54887
Chicago Manual of Style (16th Edition):
Truszkowska, Agnieszka. “Multiscale modeling of two-phase flows in microarchitectures with microfeatures.” 2014. Doctoral Dissertation, Oregon State University. Accessed March 01, 2021.
http://hdl.handle.net/1957/54887.
MLA Handbook (7th Edition):
Truszkowska, Agnieszka. “Multiscale modeling of two-phase flows in microarchitectures with microfeatures.” 2014. Web. 01 Mar 2021.
Vancouver:
Truszkowska A. Multiscale modeling of two-phase flows in microarchitectures with microfeatures. [Internet] [Doctoral dissertation]. Oregon State University; 2014. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1957/54887.
Council of Science Editors:
Truszkowska A. Multiscale modeling of two-phase flows in microarchitectures with microfeatures. [Doctoral Dissertation]. Oregon State University; 2014. Available from: http://hdl.handle.net/1957/54887
Cornell University
9.
Baker, Kristopher.
Improving Atomistic Simulations To Predict Deformation And Fracture.
Degree: PhD, Civil and Environmental Engineering, 2012, Cornell University
URL: http://hdl.handle.net/1813/31080
► Atomistic simulations can illuminate detailed mechanisms of brittle and ductile fracture and plasticity. However, there are many limitations to these simulations like short timescales, small…
(more)
▼ Atomistic simulations can illuminate detailed mechanisms of brittle and ductile fracture and plasticity. However, there are many limitations to these simulations like short timescales, small spatial scales, and limitations of the discretization. Using molecular dynamics (MD) and
multiscale methods, adaptations can be made to allow MD to answer problems relevant to engineers. In the first of three examples, MD is adapted to simulate brittle fracture by changing the discretization and allowing permanent damage between particles. By changing the discretization, specific mechanisms inherent to MD can be suppressed to allow accurate, macroscopic simulations of dynamic fragmentation of brittle materials. Second, the timescale available to MD is extended in a concurrent
multiscale method (CADD) combined with accelerated MD. This combined approach allows for microseconds of simulation time at experimentally achievable loading rates. The method is applied to crack opening in aluminum alloys, and the effect of the loading rate on crack growth mechanisms is observed. From the results, it is clear that crack growth mechanisms depend greatly on the rate of the far-field loading. Third, the effect of aging on fatigue crack growth is studied by varying the resistance to dislocation motion in the dislocation dynamics region of CADD. Only in a
multiscale simulation like CADD, can dislocation pileups reaching microns into the material interact with the atomic-scale mechanisms at a crack tip. The results of the simulations indicated that increasing the friction force raises the fatigue crack threshold. Also, a transition from stage I fatigue crack growth to stage II fatigue crack growth occurs by dislocations shielding dislocation nucleation on the primary slip plane. These observations support the conclusion that the fatigue crack growth threshold is controlled by the spacing between obstacles to dislocation glide, which is consistent with experimental observations.
Advisors/Committee Members: Warner, Derek H. (chair), Ingraffea, Anthony R (committee member), Hennig, Richard G. (committee member).
Subjects/Keywords: Multiscale; Fatigue; Molecular Dynamics
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APA (6th Edition):
Baker, K. (2012). Improving Atomistic Simulations To Predict Deformation And Fracture. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/31080
Chicago Manual of Style (16th Edition):
Baker, Kristopher. “Improving Atomistic Simulations To Predict Deformation And Fracture.” 2012. Doctoral Dissertation, Cornell University. Accessed March 01, 2021.
http://hdl.handle.net/1813/31080.
MLA Handbook (7th Edition):
Baker, Kristopher. “Improving Atomistic Simulations To Predict Deformation And Fracture.” 2012. Web. 01 Mar 2021.
Vancouver:
Baker K. Improving Atomistic Simulations To Predict Deformation And Fracture. [Internet] [Doctoral dissertation]. Cornell University; 2012. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1813/31080.
Council of Science Editors:
Baker K. Improving Atomistic Simulations To Predict Deformation And Fracture. [Doctoral Dissertation]. Cornell University; 2012. Available from: http://hdl.handle.net/1813/31080
University of Manchester
10.
Naji, Haneen.
Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs).
Degree: 2019, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:322469
► This project focuses on manufacturing novel carbon fibre (CF) multiscale composites (MSCs) based on nanocomposite matrices of thermoplastic polyurethane (TPU) and graphene nanoplatelets (GNPs). The…
(more)
▼ This project focuses on manufacturing novel carbon
fibre (CF)
multiscale composites (MSCs) based on nanocomposite
matrices of thermoplastic polyurethane (TPU) and graphene
nanoplatelets (GNPs). The main aim of this study is to obtain
innovative MSCs with optimised electrical, thermal and mechanical
properties that make them applicable to aerospace, transportation
and electrical devices. The TPU with 70 wt. % hard segments (HS)
was filled with three different sizes of GNPs, with average
particle diameters of 5 microns (GNPM5), 15 microns (GNPM15) and 25
Âmicrons (GNPM25), and reinforced with CF fabric to produce MSCs.
The effect of GNP size and annealing treatment on the thermal
dynamic, mechanical and electrical properties of TPU-70 HS and
TPU70/CF laminate were investigated. Following these tests, the
best MSCs that could be obtained were used to study the effect of
GNP content on the Mode-I interlaminar fracture toughness (ILFT),
impact-damage resistance and damage tolerance of TPU70/CF
laminates. It was found that the tensile modulus (E) and flexural
modulus (FM) of polymers-NCs matrices were affected by both the
size of GNPs and annealing treatments. While the addition of GNPM25
yielded an impressive improvement in the E and FM of TPU-70 HS, the
annealing treatment caused a slight reduction owing to the
disruption of phase separation and restacking of the GNP flakes.
However, the neat TPU-70 HS exhibited significant improvements in
the E and FM after annealing due to the formation of
microcrystalline hard domain (HD) phase separation, which caused an
increase in stiffness. The in-plane and out-of-plane electrical
conductivity and the thermal conductivity of NCs combined with
GNPM15 and GNPM25 showed a significant improvement compared to that
of neat TPU-70 HS. The same results of E and FM were reported for
MSCs based on GNPM25, where the E and FM enhanced by 19% and 105%
compared with that of TPU70/CF laminates and reduced by 11% and 4%
respectively after annealing. The out-of-plane electrical
conductivity of TPU70/CF composites showed a noticeable improvement
upon incorporating GNPM15 and GNPM25. Conversely, the thermal
conductivity of the TPU70/CF laminate exhibited a significant
improvement upon the addition of GNPM5 compared to that of GNPM15
and GNPM25. This result might be attributed to the non-uniform
dispersion of GNPM5 due to its small size, leading to an increase
in local thermal diffusivity. Since the best tensile, flexural and
electrical properties were ascribed to the NCs and MSCs combined
with GNPM25, these materials were selected and different weight
percentages of GNPs (0.5, 2.5 and 5) were used. The MSCs combined
with 0.5 wt.% GNPs showed a slight improvement in the GIC-Max and
GIC-Prop compared with that of the TPU-70 CF, while a high loading
caused a significant reduction in both GIC initiation and
propagation. In addition, both the impact-damage resistance and
residual compressive strength of MSCs at high GNP loading and
impact energy levels experienced a significant reduction compared
to…
Advisors/Committee Members: GRESIL, MATTHIEU M, Saiani, Alberto, Gresil, Matthieu.
Subjects/Keywords: graphene nanoplatelets nanocomposites; Multiscale composites
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MLA ·
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Export
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Manager
APA (6th Edition):
Naji, H. (2019). Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs). (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:322469
Chicago Manual of Style (16th Edition):
Naji, Haneen. “Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs).” 2019. Doctoral Dissertation, University of Manchester. Accessed March 01, 2021.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:322469.
MLA Handbook (7th Edition):
Naji, Haneen. “Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs).” 2019. Web. 01 Mar 2021.
Vancouver:
Naji H. Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs). [Internet] [Doctoral dissertation]. University of Manchester; 2019. [cited 2021 Mar 01].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:322469.
Council of Science Editors:
Naji H. Fabricating of Multiscale Composite Materials Based on
TPU reinforced by carbon fibre and Graphene Nanoplatelets
(GNPs). [Doctoral Dissertation]. University of Manchester; 2019. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:322469
Vanderbilt University
11.
Paulson, Wendy Jean.
Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions.
Degree: MS, Civil Engineering, 2017, Vanderbilt University
URL: http://hdl.handle.net/1803/11455
► Composite materials are attractive for aerospace vehicles due to their low weight and high performance; however, predictive computational models are needed to lower the costs…
(more)
▼ Composite materials are attractive for aerospace vehicles due to their low weight and high performance; however, predictive computational models are needed to lower the costs associated with their design and certification process. Furthermore, because aircraft structures are built up from many components fastened together, it is critical to understand and predict the mechanical behavior bolted joints introduce. The goal of this thesis is to advance the state of the art in fiber reinforced polymer composite bolted joint computational modeling and prediction using the
multiscale reduced order computational model known as the Eigendeformation-based Homogenization Method (EHM). Preliminary blind predictions were performed for laminated [44/44/11] IM7/977-3 composite specimens in single-lap straight hole and countersunk bolt joints under static tension tests. To address stiffness and post-peak behavioral issues, an in-depth blind prediction study was conducted for open hole, filled hole, and single shear bearing configurations of countersunk laminated [44/44/11] IM7/977-3 specimens under static tension and compression tests. EHM performed very well in the open and filled hole cases, and the single shear bearing results show promise of EHM as a reliable choice for composite bolted joint damage analysis.
Advisors/Committee Members: Ravindra Duddu (committee member), Caglar Oskay (Committee Chair).
Subjects/Keywords: multiscale modeling; composite bolted joints
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Paulson, W. J. (2017). Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/11455
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):
Paulson, Wendy Jean. “Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions.” 2017. Thesis, Vanderbilt University. Accessed March 01, 2021.
http://hdl.handle.net/1803/11455.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Paulson, Wendy Jean. “Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions.” 2017. Web. 01 Mar 2021.
Vancouver:
Paulson WJ. Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions. [Internet] [Thesis]. Vanderbilt University; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1803/11455.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Paulson WJ. Modeling the Failure Behavior of Composite Bolted Joints Subjected to Monotonic Loading Conditions. [Thesis]. Vanderbilt University; 2017. Available from: http://hdl.handle.net/1803/11455
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Texas A&M University
12.
Gao, Kai.
Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media.
Degree: PhD, Geophysics, 2014, Texas A&M University
URL: http://hdl.handle.net/1969.1/153630
► Seismic wave simulation in realistic Earth media with full wavefield methods is a fundamental task in geophysical studies. Conventional approaches such as the finite-difference method…
(more)
▼ Seismic wave simulation in realistic Earth media with full wavefield methods is a fundamental task in geophysical studies. Conventional approaches such as the finite-difference method and the finite-element method solve the wave equation in geological models represented with discrete grids and elements. When the Earth model includes complex heterogeneities at multiple spatial scales, the simulation requires fine discretization and therefore a system with many degrees of freedom, which often exceeds current computational abilities. In this dissertation, I address this problem by proposing new
multiscale methods for simulating elastic wave propagation based on previously developed algorithms for solving the elliptic partial differential equations and the acoustic wave equation. The fundamental motivation for developing the
multiscale method is that it can solve the wave equation on a coarsely discretized mesh by incorporating the effects of fine-scale medium properties using so-called
multiscale basis functions. This can greatly reduce computation time and degrees of freedom compared with conventional methods. I first derive a numerical homogenization method for arbitrarily heterogeneous, anisotropic media that utilizes the
multiscale basis functions determined from a local linear elasticity equation to compute effective, anisotropic properties, and these equivalent elastic medium parameters can be used directly in existing elastic modeling algorithms. Then I extend the approach by constructing multiple basis functions using two types of appropriately defined local spectral linear elasticity problems. Given the eigenfunctions determined from local spectral problems, I develop a generalized
multiscale finite-element method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media in both continuous Galerkin (CG) and discontinuous Galerkin (DG) formulations. The advantage of the
multiscale basis functions is they are model-dependent, unlike the predefined polynomial basis functions applied in conventional finite-element methods. For this reason, the GMsFEM can effectively capture the influence of fine-scale variation of the media. I present results for several numerical experiments to verify the effectiveness of both the numerical homogenization method and GMsFEM. These tests show that the effectiveness of the
multiscale method relies on the appropriate choice of boundary conditions that are applied for the local problem in numerical homogenization method and on the selection of basis functions from a large set of eigenfunctions contained in local spectral problems in GMsFEM. I develop methods for solving both these problems, and the results confirm that the
multiscale method can be powerful tool for providing accurate full wavefield solutions in heterogeneous, anisotropic media, yet with reduced computation time and degrees of freedom compared with conventional full wavefield modeling methods. Specially, I applied the DG-GMsFEM to the Marmousi-2 elastic model, and find that DG-GMsFEM can greatly reduce…
Advisors/Committee Members: Gibson Jr., Richard L (advisor), Efendiev, Yalchin (advisor), Chester, Frederick M (committee member), Everett, Mark E (committee member), Duan, Benchun (committee member).
Subjects/Keywords: elastic wave; anisotropy; multiscale
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Gao, K. (2014). Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153630
Chicago Manual of Style (16th Edition):
Gao, Kai. “Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media.” 2014. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/153630.
MLA Handbook (7th Edition):
Gao, Kai. “Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media.” 2014. Web. 01 Mar 2021.
Vancouver:
Gao K. Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/153630.
Council of Science Editors:
Gao K. Multiscale Method for Elastic Wave Propagation in the Heterogeneous, Anisotropic Media. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153630
Texas A&M University
13.
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 ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
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 March 01, 2021.
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. 01 Mar 2021.
Vancouver:
Leung WT. Adaptivity and Online Basis Construction for Generalized Multiscale Finite Element Methods. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Mar 01].
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
14.
Moon, Minam.
Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media.
Degree: PhD, Mathematics, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155430
► This dissertation is devoted to the development, study and testing of numerical methods for elliptic and parabolic equations with heterogeneous coefficients. The motivation for this…
(more)
▼ This dissertation is devoted to the development, study and testing of numerical methods for elliptic and parabolic equations with heterogeneous coefficients. The motivation for this study is to meet the need for fast and robust methods for numerical upscaling and simulation of single and multi-phase fluid flow in highly heterogeneous porous media. We consider the
multiscale model reduction technique in the framework of the discontinuous Galerkin (DG) and the hybridizable discontinuous Galerkin (HDG) finite element methods.
First, we design
multiscale finite element methods for second order elliptic equations by applying the symmetric interior penalty discontinuous Galekin finite element method. We propose two different types of finite element spaces on the coarse mesh within DG framework. The first type of spaces is based on a local spectral problem that uses an interior weighted L²-norm and a boundary weighted L²-norm for computing the mass matrix. The second choice is based on generation of a snapshot space and subsequent selection of a subspace of a reduced dimension.
Second, we develop
multiscale model reduction methods within the HDG framework. We provide construction of several
multiscale finite element spaces (related to the coarse-mesh edges) that guarantee a reasonable approximation on a reduced dimensional space of the numerical traces. In these approaches, we use local snapshot spaces and local spectral decomposition following the concept of Generalized
Multiscale Finite Element Methods. We also provide a general framework for systematic construction of
multiscale spaces. By using local snapshots we were able to add local features to the solution space and to avoid high dimensional representation of trace spaces. Further, we extend
multiscale finite element methods within HDG method to nonlinear and/or time-dependent problems. These extensions demonstrate the potential of the proposed constructions for some advanced and more practical applications.
For most of the proposed methods, we investigate their stability and derive error estimates for the approximate solutions. Furthermore we study the performance of all proposed methods on a representative number of numerical examples. In the numerical tests, we use various permeability data of highly heterogeneous porous media and contrasts ranging from 10³ to 10
6. Since the exact solution is in general unknown, we first generate solutions on a very fine mesh and use them as reference solutions in our tests. The numerical results confirm the theoretical study of the accuracy of the proposed methods and their robustness with respect to the media contrast. Our numerical experiments also show that the proposed methods could be implemented in a practical and efficient way.
Advisors/Committee Members: Lazarov, Raytcho (advisor), Efendiev, Yalchin (advisor), Popov, Bojan (committee member), Ragusa, Jean (committee member).
Subjects/Keywords: Porous media; multiscale method
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APA ·
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MLA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Moon, M. (2015). Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155430
Chicago Manual of Style (16th Edition):
Moon, Minam. “Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media.” 2015. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/155430.
MLA Handbook (7th Edition):
Moon, Minam. “Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media.” 2015. Web. 01 Mar 2021.
Vancouver:
Moon M. Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/155430.
Council of Science Editors:
Moon M. Generalized Discontinuous Multiscale Methods for Flows in Highly Heterogeneous Porous Media. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155430
Queens University
15.
Tanhatan Naseri, Seyed Alireza.
Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
.
Degree: Chemical Engineering, 2015, Queens University
URL: http://hdl.handle.net/1974/13483
► This research presents a multi-scale analysis of the transport and reaction processes in the catalyst coating of a reformer to optimize the catalyst coating microstructure…
(more)
▼ This research presents a multi-scale analysis of the transport and reaction processes in the catalyst coating of a reformer to optimize the catalyst coating microstructure for methane steam reforming. A multi-scale methodology is developed to incorporate and analyze the effect of the catalyst coating morphology on the performance of a wall-coated reformer, based on hypothetical catalyst structures generated using an in-house particle packing code. The results show the significant effect of intra-particle and inter-particle porosity as well as particle size on the rate of hydrogen production in the coating. This study also shows that an optimal catalyst coating has decreasing porosity along the reformer length based on the difference in the degree of diffusion limitation. The results of the multi-scale analysis based on random particle packing are compared with the analysis based on the real catalyst coating pore structure obtained from nano- and micro-computed tomography. The comparison shows that despite similar morphological characteristics and transport properties, the rate of hydrogen production in the packing of overlapping spheres is higher than the rate in the real catalyst structure. This result also shows that by making a structured catalyst coating with a tailored pore network, the performance of the coating improves significantly. Based on the assumption that a structured catalyst coating can be represented by a random packing of spheres, a systematic parametric study is done using response surface methodology and Latin hypercube design of experiment to optimize the catalyst coating microstructure.
Subjects/Keywords: Multiscale Analysis
;
Catalyst
;
Hydrogen
;
Reactor
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APA ·
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APA (6th Edition):
Tanhatan Naseri, S. A. (2015). Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
. (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/13483
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):
Tanhatan Naseri, Seyed Alireza. “Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
.” 2015. Thesis, Queens University. Accessed March 01, 2021.
http://hdl.handle.net/1974/13483.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Tanhatan Naseri, Seyed Alireza. “Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
.” 2015. Web. 01 Mar 2021.
Vancouver:
Tanhatan Naseri SA. Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
. [Internet] [Thesis]. Queens University; 2015. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1974/13483.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Tanhatan Naseri SA. Computational Analysis of the Reacting Flow in the Catalyst Coating of a Reformer Using a Multiscale Approach
. [Thesis]. Queens University; 2015. Available from: http://hdl.handle.net/1974/13483
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Manchester
16.
Gowers, Richard.
Developing dual-scale models for structured liquids and polymeric materials.
Degree: PhD, 2016, University of Manchester
URL: https://www.research.manchester.ac.uk/portal/en/theses/developing-dualscale-models-for-structured-liquids-and-polymeric-materials(edfe6991-79de-45a9-84e4-9e9dfb68faa4).html
;
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694299
► Computer simulation techniques for exploring the microscopic world are quickly gaining popularity as a tool to complement theoretical and experimental approaches. Molecular dynamics (MD) simulations…
(more)
▼ Computer simulation techniques for exploring the microscopic world are quickly gaining popularity as a tool to complement theoretical and experimental approaches. Molecular dynamics (MD) simulations allow the motion of an N–body soft matter system to be solved using a classical mechanics description. The scope of these simulations are however limited by the available computational power, requiring the development of multiscale methods to make better use of available resources. Dual scale models are a novel form of molecular model which simultaneously feature particles at two levels of resolution. This allows a combination of atomistic and coarse-grained (CG) force fields to be used to describe the interactions between particles. By using this approach, targeted details in a molecule can be described at high resolution while other areas are treated with fewer degrees of freedom. This approach aims to allow for simulating the key features of a system at a reduced computational cost. In this thesis, two generations of a methodology for constructing dual scale models are presented and applied to various materials including polyamide, polyethene, polystyrene and octanol. Alongside a variety of well known atomistic force fields, these models all use iterative Boltzmann inversion (IBI) force fields to describe the CG interactions. In addition the algorithms and data structures for implementing dual scale MD are detailed, and expanded to include a multiple time step (MTS) scheme for optimising its peformance. Overall the IBI and atomistic force fields were compatible with each other and able to correctly reproduce the expected structural results. The first generation methodology featured bonds directly between atoms and beads, however these did not produce the correct structures. The second generation used only atomistic resolution bonds and this improved the intramolecular structures greatly for a relatively minor cost. In both the polyamide and octanol systems studied, the models were also able to properly describe the hydrogen bonding. For the CG half of the force field, it was possible to either use preexisting force field parameters or develop new parameters in situ. The resulting dynamical behaviour of the models was unpredictable and remains an open question both for CG and dual scale models. The theoretical performance of these models is faster than the atomistic counterpart because of the reduced number of pairwise interactions that must be calculated and this scaling was seen with the proposed reference implementation. The MTS scheme was successful in improving the performance with no effects on the quality of results. In summary this work has shown that dual scale models are able to correctly reproduce the structural behaviour of atomistic models at a reduced computational cost. With further steps towards making these models more accessible, they will become an exciting new option for many types of simulation.
Subjects/Keywords: 541; molecular dynamics; multiscale
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APA (6th Edition):
Gowers, R. (2016). Developing dual-scale models for structured liquids and polymeric materials. (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/developing-dualscale-models-for-structured-liquids-and-polymeric-materials(edfe6991-79de-45a9-84e4-9e9dfb68faa4).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694299
Chicago Manual of Style (16th Edition):
Gowers, Richard. “Developing dual-scale models for structured liquids and polymeric materials.” 2016. Doctoral Dissertation, University of Manchester. Accessed March 01, 2021.
https://www.research.manchester.ac.uk/portal/en/theses/developing-dualscale-models-for-structured-liquids-and-polymeric-materials(edfe6991-79de-45a9-84e4-9e9dfb68faa4).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694299.
MLA Handbook (7th Edition):
Gowers, Richard. “Developing dual-scale models for structured liquids and polymeric materials.” 2016. Web. 01 Mar 2021.
Vancouver:
Gowers R. Developing dual-scale models for structured liquids and polymeric materials. [Internet] [Doctoral dissertation]. University of Manchester; 2016. [cited 2021 Mar 01].
Available from: https://www.research.manchester.ac.uk/portal/en/theses/developing-dualscale-models-for-structured-liquids-and-polymeric-materials(edfe6991-79de-45a9-84e4-9e9dfb68faa4).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694299.
Council of Science Editors:
Gowers R. Developing dual-scale models for structured liquids and polymeric materials. [Doctoral Dissertation]. University of Manchester; 2016. Available from: https://www.research.manchester.ac.uk/portal/en/theses/developing-dualscale-models-for-structured-liquids-and-polymeric-materials(edfe6991-79de-45a9-84e4-9e9dfb68faa4).html ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694299
Delft University of Technology
17.
Navarro Hernandez, L.C. (author).
Design of residual-based unresolved-scale models using time-averaged data.
Degree: 2015, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558
► The Large Eddy Simulation of high Reynolds number wall-bounded flows, has grid refinement requirements in near-wall regions similar to those of DNS. The feasibility of…
(more)
▼ The Large Eddy Simulation of high Reynolds number wall-bounded flows, has grid refinement requirements in near-wall regions similar to those of DNS. The feasibility of such computations is restricted by their elevated costs and therefore alternate solutions must be employed. While several methods to couple LES and RANS have been proposed, most of them employ complicated techniques to combat issues that stem from the inconsistencies introduced by the arbitrary nature of the coupling methods. The aim of this research is to propose a consistent hybrid framework based on a Variational Multiscale Method (VMM) formulation of the Navier-Stokes equations for turbulence computation; where a residual-based algebraic expression for an SGS model will be employed as a coupling term. While, the final solution will be obtained under an LES scheme, the SGS model will contain information drawn from reference data in an overlapping domain. Since the VMM results in an SGS model which depends on the large-scale residual, the coupling will effectively vanish within sufficiently resolved regions without the need of additional controlling terms. The expected result is therefore to demonstrate that reference-data-enriched LES is possible with a solid understanding of the behavior of the proposed SGS models as a basis for future work.
Aerodynamics
Aerospace Engineering
Advisors/Committee Members: Hulshoff, S.J. (mentor).
Subjects/Keywords: Variational Multiscale Method; Turbulence; LES
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APA (6th Edition):
Navarro Hernandez, L. C. (. (2015). Design of residual-based unresolved-scale models using time-averaged data. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558
Chicago Manual of Style (16th Edition):
Navarro Hernandez, L C (author). “Design of residual-based unresolved-scale models using time-averaged data.” 2015. Masters Thesis, Delft University of Technology. Accessed March 01, 2021.
http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558.
MLA Handbook (7th Edition):
Navarro Hernandez, L C (author). “Design of residual-based unresolved-scale models using time-averaged data.” 2015. Web. 01 Mar 2021.
Vancouver:
Navarro Hernandez LC(. Design of residual-based unresolved-scale models using time-averaged data. [Internet] [Masters thesis]. Delft University of Technology; 2015. [cited 2021 Mar 01].
Available from: http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558.
Council of Science Editors:
Navarro Hernandez LC(. Design of residual-based unresolved-scale models using time-averaged data. [Masters Thesis]. Delft University of Technology; 2015. Available from: http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558
Georgia Tech
18.
Li, Yan.
Prediction of material fracture toughness as function of microstructure.
Degree: PhD, Mechanical Engineering, 2014, Georgia Tech
URL: http://hdl.handle.net/1853/52999
► Microstructure determines fracture toughness of materials through the activation of different fracture mechanisms. To tailor the fracture toughness through microstructure design, it is important to…
(more)
▼ Microstructure determines fracture toughness of materials through the activation of different fracture mechanisms. To tailor the fracture toughness through microstructure design, it is important to establish relations between microstructure and fracture toughness. To this end, systematic characterization of microstructures, explicit tracking of crack propagation process and realistic representation of deformation and fracture at different length scales are required. A cohesive finite element method (CFEM) based
multiscale framework is proposed for analyzing the effect of microstructural heterogeneity, phase morphology, texture, constituent behavior and interfacial bonding strength on fracture toughness. The approach uses the J-integral to calculate the initiation/propagation fracture toughness, allowing explicit representation of realistic microstructures and fundamental fracture mechanisms.
Both brittle and ductile materials can be analyzed using this framework. For two-phase Al₂O₃/TiB₂ ceramics, the propagation fracture toughness is improved through fine microstructure size scale, rounded reinforcement morphology and appropriately balanced interphase bonding strength and compliance. These microstructure characteristics can promote interface debonding and discourage particle cracking induced catastrophic failure. Based on the CFEM results, a semi-empirical model is developed to establish a quantitative relation between the propagation toughness and statistical measures of microstructure, fracture mechanisms, constituent and interfacial properties. The analytical model provides deeper insights into the fracture process as it quantitatively predicts the proportion of each fracture mechanism in the heterogeneous microstructure. Based on the study on brittle materials, the semi-analytical model is extended to ductile materials such as AZ31 Mg alloy and Ti-6Al-4V alloy. The fracture resistance in these materials not only depends on the crack surfaces formed during the failure process, but also largely determined by the bulk plastic energy dissipation. The CFEM simulation permits surface energy release rate to be quantified through explicit tracking of crack propagation in the microstructure. The plastic energy dissipation rate is evaluated as the difference between the predicted J value and the surface energy release rate. This method allows competition between material deformation and fracture as well as competition between transgranular and intergranular fracture to be quantified. The methodology developed in this thesis is potentially useful for both the selection of materials and tailoring of microstructure to improve fracture resistance.
Advisors/Committee Members: Zhou, Min (advisor), McDowell, David L. (committee member), Neu, Richard (committee member), Zhu, Ting (committee member), Xia, Shuman (committee member), Shih, Donald (committee member).
Subjects/Keywords: Fracture toughness; Microstructure; Multiscale modeling
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APA (6th Edition):
Li, Y. (2014). Prediction of material fracture toughness as function of microstructure. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/52999
Chicago Manual of Style (16th Edition):
Li, Yan. “Prediction of material fracture toughness as function of microstructure.” 2014. Doctoral Dissertation, Georgia Tech. Accessed March 01, 2021.
http://hdl.handle.net/1853/52999.
MLA Handbook (7th Edition):
Li, Yan. “Prediction of material fracture toughness as function of microstructure.” 2014. Web. 01 Mar 2021.
Vancouver:
Li Y. Prediction of material fracture toughness as function of microstructure. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1853/52999.
Council of Science Editors:
Li Y. Prediction of material fracture toughness as function of microstructure. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/52999
University of Waterloo
19.
Jain, Aanchal.
Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding.
Degree: 2012, University of Waterloo
URL: http://hdl.handle.net/10012/6887
► Image processing applications such as image denoising, image segmentation, object detection, object recognition and texture synthesis often require a multi-scale analysis of images. This is…
(more)
▼ Image processing applications such as image denoising, image segmentation, object detection, object recognition and texture synthesis often require a multi-scale analysis of images. This is useful because different features in the image become prominent at different scales. Traditional imaging models, which have been used for multi-scale analysis of images, have several limitations such as high sensitivity to noise and structural degradation observed at higher scales. Parametric models make certain assumptions about the image structure which may or may not be valid in several situations. Non-parametric methods,
on the other hand, are very flexible and adapt to the underlying image structure more easily. It is highly desirable to have effi cient non-parametric models for image analysis, which can be used to build robust image processing algorithms with little or no prior knowledge of the underlying image content. In this thesis, we propose a non-parametric pixel neighbourhood based framework for multi-scale image analysis and apply the model to build image denoising and saliency detection algorithms for the purpose of illustration. It has
been shown that the algorithms based on this framework give competitive results without
using any prior information about the image statistics.
Subjects/Keywords: Nonparametric; Wavelet; Multiscale; Saliency
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APA (6th Edition):
Jain, A. (2012). Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6887
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):
Jain, Aanchal. “Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding.” 2012. Thesis, University of Waterloo. Accessed March 01, 2021.
http://hdl.handle.net/10012/6887.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Jain, Aanchal. “Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding.” 2012. Web. 01 Mar 2021.
Vancouver:
Jain A. Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/10012/6887.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Jain A. Nonparametric Neighbourhood Based Multiscale Model for Image Analysis and Understanding. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/6887
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Manchester
20.
Naji, Haneen.
Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs).
Degree: PhD, 2019, University of Manchester
URL: https://www.research.manchester.ac.uk/portal/en/theses/fabricating-of-multiscale-composite-materials-based-on-tpu-reinforced-by-carbon-fibre-and-graphene-nanoplatelets-gnps(cdcf1b8b-5dfe-4ed2-8cb8-f37627d4a3fb).html
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799326
► This project focuses on manufacturing novel carbon fibre (CF) multiscale composites (MSCs) based on nanocomposite matrices of thermoplastic polyurethane (TPU) and graphene nanoplatelets (GNPs). The…
(more)
▼ This project focuses on manufacturing novel carbon fibre (CF) multiscale composites (MSCs) based on nanocomposite matrices of thermoplastic polyurethane (TPU) and graphene nanoplatelets (GNPs). The main aim of this study is to obtain innovative MSCs with optimised electrical, thermal and mechanical properties that make them applicable to aerospace, transportation and electrical devices. The TPU with 70 wt. % hard segments (HS) was filled with three different sizes of GNPs, with average particle diameters of 5 μm (GNPM5), 15 μm (GNPM15) and 25 μm (GNPM25), and reinforced with CF fabric to produce MSCs. The effect of GNP size and annealing treatment on the thermal dynamic, mechanical and electrical properties of TPU-70 HS and TPU70/CF laminate were investigated. Following these tests, the best MSCs that could be obtained were used to study the effect of GNP content on the Mode-I interlaminar fracture toughness (ILFT), impact-damage resistance and damage tolerance of TPU70/CF laminates. It was found that the tensile modulus (E) and flexural modulus (FM) of polymers-NCs matrices were affected by both the size of GNPs and annealing treatments. While the addition of GNPM25 yielded an impressive improvement in the E and FM of TPU-70 HS, the annealing treatment caused a slight reduction owing to the disruption of phase separation and restacking of the GNP flakes. However, the neat TPU-70 HS exhibited significant improvements in the E and FM after annealing due to the formation of microcrystalline hard domain (HD) phase separation, which caused an increase in stiffness. The in-plane and out-of-plane electrical conductivity and the thermal conductivity of NCs combined with GNPM15 and GNPM25 showed a significant improvement compared to that of neat TPU-70 HS. The same results of E and FM were reported for MSCs based on GNPM25, where the E and FM enhanced by 19% and 105% compared with that of TPU70/CF laminates and reduced by 11% and 4% respectively after annealing. The out-of-plane electrical conductivity of TPU70/CF composites showed a noticeable improvement upon incorporating GNPM15 and GNPM25. Conversely, the thermal conductivity of the TPU70/CF laminate exhibited a significant improvement upon the addition of GNPM5 compared to that of GNPM15 and GNPM25. This result might be attributed to the non-uniform dispersion of GNPM5 due to its small size, leading to an increase in local thermal diffusivity. Since the best tensile, flexural and electrical properties were ascribed to the NCs and MSCs combined with GNPM25, these materials were selected and different weight percentages of GNPs (0.5, 2.5 and 5) were used. The MSCs combined with 0.5 wt.% GNPs showed a slight improvement in the GIC-Max and GIC-Prop compared with that of the TPU-70 CF, while a high loading caused a significant reduction in both GIC initiation and propagation. In addition, both the impact-damage resistance and residual compressive strength of MSCs at high GNP loading and impact energy levels experienced a significant reduction compared to TPU70/CF laminate.…
Subjects/Keywords: graphene nanoplatelets nanocomposites; Multiscale composites
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APA (6th Edition):
Naji, H. (2019). Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs). (Doctoral Dissertation). University of Manchester. Retrieved from https://www.research.manchester.ac.uk/portal/en/theses/fabricating-of-multiscale-composite-materials-based-on-tpu-reinforced-by-carbon-fibre-and-graphene-nanoplatelets-gnps(cdcf1b8b-5dfe-4ed2-8cb8-f37627d4a3fb).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799326
Chicago Manual of Style (16th Edition):
Naji, Haneen. “Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs).” 2019. Doctoral Dissertation, University of Manchester. Accessed March 01, 2021.
https://www.research.manchester.ac.uk/portal/en/theses/fabricating-of-multiscale-composite-materials-based-on-tpu-reinforced-by-carbon-fibre-and-graphene-nanoplatelets-gnps(cdcf1b8b-5dfe-4ed2-8cb8-f37627d4a3fb).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799326.
MLA Handbook (7th Edition):
Naji, Haneen. “Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs).” 2019. Web. 01 Mar 2021.
Vancouver:
Naji H. Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs). [Internet] [Doctoral dissertation]. University of Manchester; 2019. [cited 2021 Mar 01].
Available from: https://www.research.manchester.ac.uk/portal/en/theses/fabricating-of-multiscale-composite-materials-based-on-tpu-reinforced-by-carbon-fibre-and-graphene-nanoplatelets-gnps(cdcf1b8b-5dfe-4ed2-8cb8-f37627d4a3fb).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799326.
Council of Science Editors:
Naji H. Fabricating of multiscale composite materials based on TPU reinforced by carbon fibre and graphene nanoplatelets (GNPs). [Doctoral Dissertation]. University of Manchester; 2019. Available from: https://www.research.manchester.ac.uk/portal/en/theses/fabricating-of-multiscale-composite-materials-based-on-tpu-reinforced-by-carbon-fibre-and-graphene-nanoplatelets-gnps(cdcf1b8b-5dfe-4ed2-8cb8-f37627d4a3fb).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.799326
Virginia Tech
21.
Sabin, Robert Paul Travers.
Multiscale and Dirichlet Methods for Supply Chain Order Simulation.
Degree: PhD, Statistics, 2019, Virginia Tech
URL: http://hdl.handle.net/10919/89099
► Supply chains are complex systems. Researchers in the Social and Decision Analytics Laboratory (SDAL) at Virginia Tech worked with a major global supply chain company…
(more)
▼ Supply chains are complex systems. Researchers in the Social and Decision Analytics Laboratory (SDAL) at Virginia Tech worked with a major global supply chain company to simulate an end-to-end supply chain. The supply chain data includes raw materials, production lines, inventory, customer orders, and shipments. Including contributions of this author, Pires, Sabin, Higdon et al. (2017) developed simulations for the production, customer orders, and shipments. Customer orders are at the center of understanding behavior in a supply chain. This dissertation continues the supply chain simulation work by improving the order simulation. Orders come from a diverse set of customers with different habits. These habits can differ when it comes to which products they order, how often they order, how spaced out those orders times are, and how much of each of those products are ordered. This dissertation is unique in that it relies extensively on Dirichlet and
multiscale methods to tackle supply-chain order simulation.
Multiscale model methodology is furthered to include Dirichlet models which are used to simulate order times for each customer and the collective system on different scales.
Advisors/Committee Members: Higdon, David (committeechair), Ellis, Kimberly P. (committee member), House, Leanna L. (committee member), Deng, Xinwei (committee member).
Subjects/Keywords: Multiscale; Dirichlet; Bayesian; Supply Chain
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APA (6th Edition):
Sabin, R. P. T. (2019). Multiscale and Dirichlet Methods for Supply Chain Order Simulation. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/89099
Chicago Manual of Style (16th Edition):
Sabin, Robert Paul Travers. “Multiscale and Dirichlet Methods for Supply Chain Order Simulation.” 2019. Doctoral Dissertation, Virginia Tech. Accessed March 01, 2021.
http://hdl.handle.net/10919/89099.
MLA Handbook (7th Edition):
Sabin, Robert Paul Travers. “Multiscale and Dirichlet Methods for Supply Chain Order Simulation.” 2019. Web. 01 Mar 2021.
Vancouver:
Sabin RPT. Multiscale and Dirichlet Methods for Supply Chain Order Simulation. [Internet] [Doctoral dissertation]. Virginia Tech; 2019. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/10919/89099.
Council of Science Editors:
Sabin RPT. Multiscale and Dirichlet Methods for Supply Chain Order Simulation. [Doctoral Dissertation]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/89099
Rutgers University
22.
Hu, Wangsu, 1989-.
Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor.
Degree: PhD, Civil and Environmental Engineering, 2019, Rutgers University
URL: https://rucore.libraries.rutgers.edu/rutgers-lib/60167/
► The emergence of Transportation Big Data provides rich information for estimating and predicting urban travel demand patterns. The traditional travel demand sensors involve labor-intensive survey…
(more)
▼ The emergence of Transportation Big Data provides rich information for estimating and predicting urban travel demand patterns. The traditional travel demand sensors involve labor-intensive survey data, traffic detector data for assignment model calibration, vehicle re-identification data from scattered Bluetooth, Wifi, or License plate readers, or aggregated cellphone activity data used in existing dynamic Origin-Destination estimation models or applications. With the growing number of mobile devices with GPS units and improvement in WLT technologies, the Location-Based Social Network (LBSN) data is an emerging travel demand data source. LBSN data recorded check-in or tweeting activities of massive users at different points of interests (POIs). The wide-range of POIs ensure the dense coverage of the main urban areas and the user-confirmed POI information provides the much-needed trip purpose information not available in other data sources. Meanwhile, the LBSN data has the advantages of passive secondary data collection usually not for the purpose of travel surveys, and anonymization. Despite the above advantages, LBSN data is not without its limitations for estimating urban travel demand, as well as dynamic OD estimation for proactive urban congestion mitigation and operations. First, LBSN can have a systematic temporal error for estimating travel demand. The LBSN activities do not always mimic travel activities throughout the day. Second, LBSN data includes a sampling bias for different population groups and venue types. Third, the stochastic nature of human activities, especially the POI arriving patterns are critical for travel demand estimation. The existing approaches to the LBSN-based travel demand analysis have suffered from those limitations on deriving the dynamic travel demand patterns.
Recent development in spatial-temporal characteristics provides the opportunities to identify and quantify the correlation between LSBN-based travel activity and urban travel demand pattern. In this dissertation, a novel set of travel demand models based on the LBSN data is proposed and tested. The research starts with a comprehensive review of the existing travel demand data collection methods and the travel demand modeling. Then we introduce a profiling method to infer the functionality of city zones based on the POI categorical distribution and local mobility patterns. By classifying zones by these zone topics, we can now analyze interactions between zones of different functionality. Thirdly, by conducting zonal time-of-day variation modeling on the LBSN check-in arrivals, a new stochastic point process based trip arrivals estimation is developed. The output is applied to the input of a temporal delay based trip distribution model for deriving dynamic OD patterns. And the model calibration and applications are also provided and discussed. The evaluation results illustrate the promising benefits of applying LBSN Data in urban travel demand modeling.
Advisors/Committee Members: Jin, Jing (chair), Liu, Xiang (internal member), Gong, Jie (internal member), Di, Xuan (outside member), Xiong, Hui (outside member), School of Graduate Studies.
Subjects/Keywords: Location-based services; Multiscale modeling
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APA (6th Edition):
Hu, Wangsu, 1. (2019). Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor. (Doctoral Dissertation). Rutgers University. Retrieved from https://rucore.libraries.rutgers.edu/rutgers-lib/60167/
Chicago Manual of Style (16th Edition):
Hu, Wangsu, 1989-. “Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor.” 2019. Doctoral Dissertation, Rutgers University. Accessed March 01, 2021.
https://rucore.libraries.rutgers.edu/rutgers-lib/60167/.
MLA Handbook (7th Edition):
Hu, Wangsu, 1989-. “Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor.” 2019. Web. 01 Mar 2021.
Vancouver:
Hu, Wangsu 1. Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor. [Internet] [Doctoral dissertation]. Rutgers University; 2019. [cited 2021 Mar 01].
Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/60167/.
Council of Science Editors:
Hu, Wangsu 1. Dynamic origin-destination estimation with location-based social networking data: exploring urban travel demand sensor. [Doctoral Dissertation]. Rutgers University; 2019. Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/60167/
University of Minnesota
23.
Poigai Arunachalam, Shivaram.
Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation.
Degree: PhD, Biomedical Engineering, 2017, University of Minnesota
URL: http://hdl.handle.net/11299/188910
► Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia that causes stroke affecting more than 2.3 million people in the US. Catheter ablation with…
(more)
▼ Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia that causes stroke affecting more than 2.3 million people in the US. Catheter ablation with pulmonary vein isolation (PVI) to terminate AF is successful for paroxysmal AF but suffers limitations with persistent AF patients as current mapping methods cannot identify AF active substrates outside of PVI region. Recent evidences in the mechanistic understating of AF pathophysiology suggest that ectopic activity, localized re-entrant circuit with fibrillatory propagation and multiple circuit re-entries may all be involved in human AF. Accordingly, the hypothesis that rotor is an underlying AF mechanism is compatible with both the presence of focal discharges and multiple wavelets. Rotors are stable electrical sources which have characteristic spiral waves like appearance with a pivot point surrounded by peripheral region. Targeted ablation at the rotor pivot points in several animal studies have demonstrated efficacy in terminating AF. The objective of this dissertation was to develop robust spatiotemporal mapping techniques that can fully capture the intrinsic dynamics of the non-stationary time series intracardiac electrogram signal to accurately identify the rotor pivot zones that may cause and maintain AF. In this thesis, four time domain approaches namely multiscale entropy (MSE) recurrence period density entropy (RPDE), kurtosis and intrinsic mode function (IMF) complexity index and one frequency domain approach namely multiscale frequency (MSF) was proposed and developed for accurate identification of rotor pivot points. The novel approaches were validated using optical mapping data with induced ventricular arrhythmia in ex-vivo isolated rabbit heart with single, double and meandering rotors (including numerically simulated data). The results demonstrated the efficacy of the novel approaches in accurate identification of rotor pivot point. The chaotic nature of rotor pivot point resulted in higher complexity measured by MSE, RPDE, kurtosis, IMF and MSF compared to the stable rotor periphery that enabled its accurate identification. Additionally, the feasibility of using conventional catheter mapping system to generate patient specific 3D maps for intraprocedural guidance for catheter ablation using these novel approaches was demonstrated with 1055 intracardiac electrograms obtained from both atria’s in a persistent AF patient. Notably, the 3D maps did not provide any clinically significant information on rotor pivot point identification or the presence of rotors themselves. Validation of these novel approaches is required in large datasets with paroxysmal and persistent AF patients to evaluate their clinical utility in rotor identification as potential targets for AF ablation.
Subjects/Keywords: Ablation; Atrial Fibrillation; Multiscale Entropy; Multiscale Frequency; Pivot Point; Rotors
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APA (6th Edition):
Poigai Arunachalam, S. (2017). Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/188910
Chicago Manual of Style (16th Edition):
Poigai Arunachalam, Shivaram. “Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation.” 2017. Doctoral Dissertation, University of Minnesota. Accessed March 01, 2021.
http://hdl.handle.net/11299/188910.
MLA Handbook (7th Edition):
Poigai Arunachalam, Shivaram. “Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation.” 2017. Web. 01 Mar 2021.
Vancouver:
Poigai Arunachalam S. Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation. [Internet] [Doctoral dissertation]. University of Minnesota; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/11299/188910.
Council of Science Editors:
Poigai Arunachalam S. Novel approaches for quantitative electrogram analysis for rotor identification: Implications for ablation in patients with atrial fibrillation. [Doctoral Dissertation]. University of Minnesota; 2017. Available from: http://hdl.handle.net/11299/188910
University of New South Wales
24.
Herasati, Saeed.
Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites.
Degree: Mechanical & Manufacturing Engineering, 2014, University of New South Wales
URL: http://handle.unsw.edu.au/1959.4/53641
;
https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12336/SOURCE02?view=true
► Single walled carbon nanotubes (SWCNTs) have attracted great attention for new generation of advanced polymer matrix composites (PMC). Nevertheless, diverse experimental reports on the elastic…
(more)
▼ Single walled carbon nanotubes (SWCNTs) have attracted great attention for new generation of advanced polymer matrix composites (PMC). Nevertheless, diverse experimental reports on the elastic properties of SWCNT-PMC, have also initiated extensive theoretical investigations aiming at revealing their reinforcement mechanisms and optimizing their mechanical properties. It has been reported that the overall stiffness of SWCNT-PMC is significantly affected by the interphase and waviness of SWCNTs. Although the impact of a pre-determined interphase on the stiffness of SWCNT-PMC has been studied thoroughly, little is known about the elastic properties of the interphase layer. Moreover, the waviness of SWCNTs has been unrealistically assumed to be regular wave-shaped fibres. To accurately predict the elastic properties of non-bonded SWCNT-PMC, this thesis has developed a comprehensive
multiscale numerical strategy to address both interphase and waviness with minimal simplifications. First, the stiffnesses of SWCNTs and polymer matrices are investigated through atomistic simulations. This leads to the conclusion that, except the transverse Young's modulus, all other elastic quantities of SWCNTs under the vdW forces increase with the pressure rise. The study also confirms that molecular mechanics (MM) can only provide acceptable results for polymers under specific conditions. The
multiscale investigations are then carried out in two stages. In Stage 1, a cubic nanoscale representative volume element (NRVE) of a polymer matrix with SWCNT is characterized through atomistic simulations. Using the results of individual constituents, a three-phase continuum finite element (FE) model, consisting of the bulk matrix, the dense interphase matrix and the SWCNT under van der walls (vdW) force, is developed successfully. The study shows that the average density of the interphase can be used as a parameter to determine the mechanical properties of the dense interphase matrix. In Stage 2, the NRVE model is used as a basic solid element for the wavy SWCNTs in a cubic micro-scale representative volume element (MRVE) composite. A new indicator for the waviness is defined and quantified from micrograph images. The study confirms that the models established produce results consistent with experiments, that aligned SWCNTs are remarkable stiffeners, and that the interphase region of non-bonded SWCNT-PMC can be ignored only if the SWCNT diameter is (10, 10) or smaller.
Advisors/Committee Members: Zhang, Liangchi, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.
Subjects/Keywords: Atomistic simulation; multiscale modelling; Waviness; CNT; Interphase; Multiscale modelling
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APA (6th Edition):
Herasati, S. (2014). Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53641 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12336/SOURCE02?view=true
Chicago Manual of Style (16th Edition):
Herasati, Saeed. “Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites.” 2014. Doctoral Dissertation, University of New South Wales. Accessed March 01, 2021.
http://handle.unsw.edu.au/1959.4/53641 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12336/SOURCE02?view=true.
MLA Handbook (7th Edition):
Herasati, Saeed. “Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites.” 2014. Web. 01 Mar 2021.
Vancouver:
Herasati S. Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Mar 01].
Available from: http://handle.unsw.edu.au/1959.4/53641 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12336/SOURCE02?view=true.
Council of Science Editors:
Herasati S. Multiscale modelling of elastic properties of non-bonded single-walled carbon nanotube polymer matrix composites. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/53641 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12336/SOURCE02?view=true
Mississippi State University
25.
McWilliams, James Keith.
Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties.
Degree: MS, Aerospace Engineering, 2014, Mississippi State University
URL: http://sun.library.msstate.edu/ETD-db/theses/available/etd-03202014-140806/
;
► Full-domain multiscale analyses of unidirectional AS4/H3502 open-hole composite tensile specimens were performed to assess the effect of microscale progressive fiber failures in regions with…
(more)
▼ Full-domain
multiscale analyses of unidirectional AS4/H3502 open-hole composite tensile specimens were performed to assess the effect of microscale progressive fiber failures in regions with large stress/strain gradients on macroscale composite strengths. The effect of model discretization at the microscale and macroscale on the calculated composite strengths and analysis times was investigated. Multiple sets of microscale analyses of repeating unit cells, each containing varying numbers of fibers with a distinct statistical distribution of fiber strengths and fiber volume fractions, were used to establish the microscale discretization for use in
multiscale calculations. In order to improve computational times,
multiscale analyses were performed over a reduced domain of the open-hole specimen. The calculated strengths obtained using reduced domain analyses were comparable to those for full-domain analyses, but at a fraction of the computational cost. Such reduced domain analyses likely are an integral part of efficient adaptive
multiscale analyses of large all-composite air vehicles.
Advisors/Committee Members: Thomas E. Lacy (chair), Samit Roy (committee member), Ratan Jha (committee member).
Subjects/Keywords: Multiscale modeling; PMC; composites; fiber strength stochastics
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APA (6th Edition):
McWilliams, J. K. (2014). Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties. (Masters Thesis). Mississippi State University. Retrieved from http://sun.library.msstate.edu/ETD-db/theses/available/etd-03202014-140806/ ;
Chicago Manual of Style (16th Edition):
McWilliams, James Keith. “Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties.” 2014. Masters Thesis, Mississippi State University. Accessed March 01, 2021.
http://sun.library.msstate.edu/ETD-db/theses/available/etd-03202014-140806/ ;.
MLA Handbook (7th Edition):
McWilliams, James Keith. “Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties.” 2014. Web. 01 Mar 2021.
Vancouver:
McWilliams JK. Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties. [Internet] [Masters thesis]. Mississippi State University; 2014. [cited 2021 Mar 01].
Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-03202014-140806/ ;.
Council of Science Editors:
McWilliams JK. Efficient coupling of micro/macroscale analyses with stochastic variations of constituent properties. [Masters Thesis]. Mississippi State University; 2014. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-03202014-140806/ ;
University of Alberta
26.
Xia, Weijie.
Three-scale modeling and numerical simulations of fabric
materials.
Degree: PhD, 2010, University of Alberta
URL: https://era.library.ualberta.ca/files/gf06g335b
► Based on the underlying structure of fabric materials, a three-scale model is constructed to describe the mechanical behavior of fabric materials. The current model assumes…
(more)
▼ Based on the underlying structure of fabric materials,
a three-scale model is constructed to describe the mechanical
behavior of fabric materials. The current model assumes that fabric
materials take on an overall behavior of anisotropic membranes, so
membrane scale is taken as the macroscopic or continuum scale of
the model. Following the membrane scale, yarn scale is introduced,
in which yarns and their weaving structure are accounted for
explicitly and the yarns are modeled as extensible elasticae. A
unit cell consisting of two overlapping yarns is used to formulate
the weaving patterns of yarns, which governs the constitutive
nonlinear behavior of fabric materials. The third scale, named
fibril scale, zooms to the fibrils inside a yarn and incorporates
its material properties. Via a coupling process between these three
scales, the overall behavior and performance of the complex fabric
products become predictable by knowing the material properties of a
single fibril and the weaving structure of the fabrics. In
addition, potential damage during deformation is also captured in
the current model through tracking the deformation of yarns in
fibril scale. Based on the multi-scale model, both static and
dynamic simulations were implemented. Comparison between the static
simulations and experiment demonstrates the model abilities as
desired. Through the dynamic simulations, parameter research was
conducted and indicates the ballistic performance and mechanical
behavior of the fabric materials are determined by a combination of
various factors and conditions rather than the material properties
alone. Factors such as boundary conditions, material orientation
and projectile shapes etc. affect the damage patterns and energy
absorption of the fabric.
Subjects/Keywords: fabric; impact; armor; modeling; multiscale; ballistic; damage
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APA (6th Edition):
Xia, W. (2010). Three-scale modeling and numerical simulations of fabric
materials. (Doctoral Dissertation). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/gf06g335b
Chicago Manual of Style (16th Edition):
Xia, Weijie. “Three-scale modeling and numerical simulations of fabric
materials.” 2010. Doctoral Dissertation, University of Alberta. Accessed March 01, 2021.
https://era.library.ualberta.ca/files/gf06g335b.
MLA Handbook (7th Edition):
Xia, Weijie. “Three-scale modeling and numerical simulations of fabric
materials.” 2010. Web. 01 Mar 2021.
Vancouver:
Xia W. Three-scale modeling and numerical simulations of fabric
materials. [Internet] [Doctoral dissertation]. University of Alberta; 2010. [cited 2021 Mar 01].
Available from: https://era.library.ualberta.ca/files/gf06g335b.
Council of Science Editors:
Xia W. Three-scale modeling and numerical simulations of fabric
materials. [Doctoral Dissertation]. University of Alberta; 2010. Available from: https://era.library.ualberta.ca/files/gf06g335b
University of Manchester
27.
Davison, Thomas James.
Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production.
Degree: 2014, University of Manchester
URL: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:220329
► AbstractUniversity: The University of ManchesterName: Thomas J. DavisonDegree: PhDThesis Title: Reaction and Diffusion Simulations for Heterogeneously Catalysed Biodiesel ProductionYear: 2013This thesis covers the simulation and…
(more)
▼ AbstractUniversity: The University of
ManchesterName: Thomas J. DavisonDegree: PhDThesis Title: Reaction
and Diffusion Simulations for Heterogeneously Catalysed Biodiesel
ProductionYear: 2013This thesis covers the simulation and modelling
of the transesterification of triglyceride oils to make biodiesel,
using heterogeneous catalysts. Initially, data fitting was
performed to fit overall kinetic rate equations to experimental
data, ignoring diffusional behaviour. Additionally, experiments
were undertaken to investigate the influence of feed ratio on the
reaction kinetics. A single site mechanism with surface reaction as
the rate limiting step was found to most closely match the
experimental conversion profiles for the operating conditions
studied. To incorporate diffusional behaviour into the modelling a
multicomponent diffusion methodology was adapted for use within
this system. To verify transport properties of the system and the
suitability of this theoretical diffusion calculation, measurement
of density and viscosity for a range of mixtures was undertaken,
along with molecular dynamics simulation to produce diffusion
coefficients. Finally, a novel algorithm was developed to simulate
coupled diffusion and reaction within the pores of the catalyst and
the subsequent bulk concentration changes this
produced.
Advisors/Committee Members: Masters, Andrew.
Subjects/Keywords: Biodiesel; Heterogeneous Catalysis; Diffusion; Reaction; Multiscale Simulation
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APA (6th Edition):
Davison, T. J. (2014). Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production. (Doctoral Dissertation). University of Manchester. Retrieved from http://www.manchester.ac.uk/escholar/uk-ac-man-scw:220329
Chicago Manual of Style (16th Edition):
Davison, Thomas James. “Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production.” 2014. Doctoral Dissertation, University of Manchester. Accessed March 01, 2021.
http://www.manchester.ac.uk/escholar/uk-ac-man-scw:220329.
MLA Handbook (7th Edition):
Davison, Thomas James. “Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production.” 2014. Web. 01 Mar 2021.
Vancouver:
Davison TJ. Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production. [Internet] [Doctoral dissertation]. University of Manchester; 2014. [cited 2021 Mar 01].
Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:220329.
Council of Science Editors:
Davison TJ. Reaction and Diffusion Simulations for Heterogeneously
Catalysed Biodiesel Production. [Doctoral Dissertation]. University of Manchester; 2014. Available from: http://www.manchester.ac.uk/escholar/uk-ac-man-scw:220329
Cornell University
28.
Wen, Bin.
Stochastic Multiscale Modeling Of Polycrystalline Materials.
Degree: PhD, Aerospace Engineering, 2013, Cornell University
URL: http://hdl.handle.net/1813/33822
► Mechanical properties of engineering materials are sensitive to the underlying random microstructure. Quantification of mechanical property variability induced by microstructure variation is essential for the…
(more)
▼ Mechanical properties of engineering materials are sensitive to the underlying random microstructure. Quantification of mechanical property variability induced by microstructure variation is essential for the prediction of extreme properties and microstructure-sensitive design of materials. Recent advances in high throughput characterization of polycrystalline microstructures have resulted in huge data sets of microstructural descriptors and image snapshots. To utilize these large scale experimental data for computing the resulting variability of macroscopic properties, appropriate mathematical representation of microstructures is needed. By exploring the space containing all admissible microstructures that are statistically similar to the available data, one can estimate the distribution/envelope of possible properties by employing efficient stochastic simulation methodologies along with robust physics-based deterministic simulators. The focus of this thesis is on the construction of lowdimensional representations of random microstructures and the development of efficient physics-based simulators for polycrystalline materials. By adopting appropriate stochastic methods, such as Monte Carlo and Adaptive Sparse Grid Collocation methods, the variability of microstructure-sensitive properties of polycrystalline materials is investigated. The primary outcomes of this thesis include: • Development of data-driven reduced-order representations of microstruc- ture variations to construct the admissible space of random polycrystalline microstructures. • Development of accurate and efficient physics-based simulators for the estimation of material properties based on mesoscale microstructures. • Investigating property variability of polycrystalline materials using efficient stochastic simulation methods in combination with the above two developments. The uncertainty quantification framework developed in this work integrates information science and materials science, and provides a new outlook to
multiscale materials modeling accounting for microstructure and process uncertainties. Predictive materials modeling will accelerate the development of new materials and processes for critical applications in industry.
Advisors/Committee Members: Zabaras, Nicholas John (chair), Earls, Christopher J (committee member), Warner, Derek H. (committee member).
Subjects/Keywords: Stochastic simulation; Multiscale modeling; Polycrystalline materials
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APA (6th Edition):
Wen, B. (2013). Stochastic Multiscale Modeling Of Polycrystalline Materials. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/33822
Chicago Manual of Style (16th Edition):
Wen, Bin. “Stochastic Multiscale Modeling Of Polycrystalline Materials.” 2013. Doctoral Dissertation, Cornell University. Accessed March 01, 2021.
http://hdl.handle.net/1813/33822.
MLA Handbook (7th Edition):
Wen, Bin. “Stochastic Multiscale Modeling Of Polycrystalline Materials.” 2013. Web. 01 Mar 2021.
Vancouver:
Wen B. Stochastic Multiscale Modeling Of Polycrystalline Materials. [Internet] [Doctoral dissertation]. Cornell University; 2013. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1813/33822.
Council of Science Editors:
Wen B. Stochastic Multiscale Modeling Of Polycrystalline Materials. [Doctoral Dissertation]. Cornell University; 2013. Available from: http://hdl.handle.net/1813/33822
Texas A&M University
29.
Fu, Shubin.
Some Applications of the Generalized Multiscale Finite Element Method.
Degree: PhD, Mathematics, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/165743
► Many materials in nature are highly heterogeneous and their properties can vary at different scales. Direct numerical simulations in such multiscale media are prohibitively expensive…
(more)
▼ Many materials in nature are highly heterogeneous and their properties can vary at different scales. Direct numerical simulations in such
multiscale media are prohibitively expensive and some types of model reduction are needed. Typical model reduction techniques include upscaling and
multiscale methods. In upscaling methods, one upscales the
multiscale media properties so that the problem can be solved on a coarse grid. In
multiscale method, one constructs
multiscale basis functions that capture media information and solves the problem on the coarse grid.
Generalized
Multiscale Finite Element Method (GMsFEM) is a recently proposed model reduction technique and has been used for various practical applications. This method has no assumption about the media properties, which can have any type of complicated structure. In GMsFEM, we first create a snapshot space, and then solve a carefully chosen eigenvalue problem to form the offline space. One can also construct online space for the parameter dependent problems. It is shown theoretically and numerically that the GMsFEM is very efficient for the heterogeneous problems involving high-contrast, no-scale separation.
In this dissertation, we apply the GMsFEM to perform model reduction for the steady state elasticity equations in highly heterogeneous media though some of our applications are motivated by elastic wave propagation in subsurface. We will consider three kinds of coupling mechanism for different situations. For more practical purposes, we will also study the applications of the GMsFEM for the frequency domain acoustic wave equation and the Reverse Time Migration (RTM) based on the time domain acoustic wave equation.
Advisors/Committee Members: Efendiev, Yalchin (advisor), Gibson, Richard (advisor), Lazarov, Raytcho (committee member), Zhou, Jianxin (committee member).
Subjects/Keywords: Multiscale method; linear elasticity; wave equation
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Export
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APA (6th Edition):
Fu, S. (2017). Some Applications of the Generalized Multiscale Finite Element Method. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/165743
Chicago Manual of Style (16th Edition):
Fu, Shubin. “Some Applications of the Generalized Multiscale Finite Element Method.” 2017. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/165743.
MLA Handbook (7th Edition):
Fu, Shubin. “Some Applications of the Generalized Multiscale Finite Element Method.” 2017. Web. 01 Mar 2021.
Vancouver:
Fu S. Some Applications of the Generalized Multiscale Finite Element Method. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/165743.
Council of Science Editors:
Fu S. Some Applications of the Generalized Multiscale Finite Element Method. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/165743
Texas A&M University
30.
Ren, Jun.
Multiscale Solution Techniques For High-Contrast Anisotropic Problems.
Degree: PhD, Mathematics, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/156423
► Anisotropy occurs in a wide range of applications. Examples include porous media, composite materials, heat transfer, and other fields in science and engineering. Due to…
(more)
▼ Anisotropy occurs in a wide range of applications. Examples include porous media, composite materials, heat transfer, and other fields in science and engineering. Due to the anisotropy, the physical property could vary significantly only in certain directions. As such, the discrete problem will have a very large condition number for traditional numerical methods. In addition, many anisotropic materials contain multiple scales and their physical properties could vary in orders of magnitude. These large variations bring an additional small-scale parameter into the problem. Thus, a proper treatment of the anisotropy not only helps to design robust iterative methods, but also provides accurate approximations of the problem.
Various well-developed techniques have been used to address anisotropic problems, such as multigrid methods, adaptive methods, and domain decomposition techniques. More recently, a large class of accurate reduced-order methods have been introduced and applied to many applications. These include
multiscale finite element,
multiscale finite volume, and mixed
multiscale finite element methods.
The primary focus of this dissertation is to study a
multiscale finite element method for the approximation of heterogeneous problems involving high-anisotropy, high-contrast, parameter dependency. First, we design robust two-level domain decomposition preconditioners using
multiscale coarse spaces. Next, a general formulation of heterogeneous problem is investigated using this
multiscale finite element method. Then, a multilevel
multiscale finite element method is proposed and analyzed to reduce the computational cost. Last, this
multiscale finite element method is extended to a convection-diffusion problem.
Advisors/Committee Members: Efendiev, Yalchin (advisor), King, Michael (committee member), Lazarov, Raytcho (committee member), Walton, Jay R (committee member).
Subjects/Keywords: Multiscale; High-contrast; Anisotropy; Finite element methods.
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to Zotero / EndNote / Reference
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APA (6th Edition):
Ren, J. (2015). Multiscale Solution Techniques For High-Contrast Anisotropic Problems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/156423
Chicago Manual of Style (16th Edition):
Ren, Jun. “Multiscale Solution Techniques For High-Contrast Anisotropic Problems.” 2015. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/156423.
MLA Handbook (7th Edition):
Ren, Jun. “Multiscale Solution Techniques For High-Contrast Anisotropic Problems.” 2015. Web. 01 Mar 2021.
Vancouver:
Ren J. Multiscale Solution Techniques For High-Contrast Anisotropic Problems. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/156423.
Council of Science Editors:
Ren J. Multiscale Solution Techniques For High-Contrast Anisotropic Problems. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/156423
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Open Access Theses and Dissertations
