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You searched for +publisher:"University of North Carolina" +contributor:("Klotsa, Daphne"). Showing records 1 – 2 of 2 total matches.

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University of North Carolina

1. Battista, Nicholas. The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages.

Degree: Mathematics, 2017, University of North Carolina

Proper cardiogenesis requires a delicate balance between genetic and environmental (epigenetic) signals, and mechanical forces. While many cellular biologists and geneticists have extensively studied heart morphogenesis using various experimental techniques, only a few scientists have begun using mathematical modeling as a tool for studying cardiogenic events. Hemodynamic processes, such as vortex formation, are important in the generation of shear at the endothelial surface layer and strains at the epithelial layer, which aid in proper morphology and functionality. The purpose of this thesis is to study the underlying fluid dynamics in various stages on heart development, in particular, the morphogenic stages when the heart is a linear heart tube as well as during the onset of ventricular trabeculation. Previous mathematical models of the linear heart tube stage have focused on mechanisms of valveless pumping, whether dynamic suction pumping (impedance pumping) or peristalsis; however, they all have neglected hematocrit. The impact of blood cells was examined by fluid-structure interaction simulations, via the immersed boundary method. Moreover, electrophysiology models were incorporated into an immersed boundary framework, and bifurcations within the morphospace were studied that give rise to a spectrum of pumping regimes, with peristaltic-like waves of contraction and impedance pumping at the extremes. Lastly, effects of resonant pumping, damping, and boundary inertial effects (added mass) were studied for dynamic suction pumping. The other stage of heart development considered here is during the onset of ventricular trabeculation. This occurs after the heart has undergone the cardiac looping stage and now is a multi-chambered pumping system with primitive endocardial cushions, which act as precursors to valve leaflets. Trabeculation introduces complex morphology onto the inner lining of the endocardium in the ventricle. This transition of a smooth endocardium to one with complex geometry, may have significant effect on the intracardial fluid dynamics and stress distribution within emrbyonic hearts. Previous studies have not included these geometric perturbations along the ventricular endocardium. The role of trabeculae on intracardial (and intertrabecular) flows was studied using two different mathematical models implemented within an immersed boundary framework. It is shown that the trabecular geometry and number density have a significant effect on such flows. Furthermore this thesis also focused attention to the creation of software for scientists and engineers to perform fluid-structure interaction simulations at an accelerated rate, in user-friendly environments for beginner programmers, e.g., MATLAB or Python 3.5. The software, IB2d, performs fully coupled fluid-structure interaction problems using Charles Peskin's immersed boundary method. IB2d is capable of running a vast range of biomechanics models and contains multiple options for constructing material properties of the fiber structure,… Advisors/Committee Members: Battista, Nicholas, Miller, Laura, Forest, M. Gregory, Griffith, Boyce, Klotsa, Daphne, Liu, Jiandong.

Subjects/Keywords: College of Arts and Sciences; Department of Mathematics

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

APA (6th Edition):

Battista, N. (2017). The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages. (Thesis). University of North Carolina. Retrieved from https://cdr.lib.unc.edu/record/uuid:10c652c0-5884-47f8-95b6-ce38502bcc66

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):

Battista, Nicholas. “The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages.” 2017. Thesis, University of North Carolina. Accessed November 23, 2020. https://cdr.lib.unc.edu/record/uuid:10c652c0-5884-47f8-95b6-ce38502bcc66.

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

MLA Handbook (7th Edition):

Battista, Nicholas. “The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages.” 2017. Web. 23 Nov 2020.

Vancouver:

Battista N. The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages. [Internet] [Thesis]. University of North Carolina; 2017. [cited 2020 Nov 23]. Available from: https://cdr.lib.unc.edu/record/uuid:10c652c0-5884-47f8-95b6-ce38502bcc66.

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

Council of Science Editors:

Battista N. The Fluid Dynamics of Heart Development: The effect of morphology on flow at several stages. [Thesis]. University of North Carolina; 2017. Available from: https://cdr.lib.unc.edu/record/uuid:10c652c0-5884-47f8-95b6-ce38502bcc66

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


University of North Carolina

2. HEROY, SAMUEL. Rigidity Percolation in Disordered Fiber Systems: Theory and Applications.

Degree: Mathematics, 2018, University of North Carolina

Nanocomposites, particularly carbon nanocomposites, find many applications spanning an impressive variety of industries on account of their impressive properties and versatility. However, the discrepancy between the performance of individual nanoparticles and that of nanocomposites suggests continued technological development and better theoretical understanding will provide much opportunity for further property enhancement. Study of computational renderings of disordered fiber systems has been successful in various nanocomposite modeling applications, particularly toward the characterization of electrical properties. Motivated by these successes, I develop an explanatory model for `mechanical' or `rheological percolation,' terms used by experimentalists to describe a nonlinear increase in elastic modulus/strength that occurs at particle inclusion volume fractions well above the electrical percolation threshold. Specifically, I formalize a hypothesis given by \citet*{penu}, which states that these dramatic gains result from the formation of a `rigid CNT network.' Idealizing particle interactions as hinges, this amounts to the network property of \emph{rigidity percolation} – the emergence of a giant component (within the inclusion contact network) that is not only connected, but furthermore the inherent contacts are patterned to constrain all internal degrees of freedom in the component. Rigidity percolation has been studied in various systems (particularly the characterization of glasses and proteins) but has never been applied to disordered systems of three-dimensional rod-like particles. With mathematically principled arguments from \emph{rigidity matroid theory}, I develop a scalable algorithm (\emph{Rigid Graph Compression}, or \emph{RGC}), which can be used to detect rigidity percolation in such systems by iteratively compressing provably rigid subgraphs within the rod contact networks. Prior to approaching the 3D system, I confirm the usefulness of \emph{RGC} by using it to accurately approximate the rigidity percolation threshold in disordered systems of 2D fibers – achieving <1% error relative to a previous exact method. Then, I develop an implementation of \emph{RGC} in three dimensions and determine an upper bound for the rigidity percolation threshold in disordered 3D fiber systems. More work is required to show that this approximation is sufficiently accurate – however, this work confirms that rigidity in the inclusion network is a viable explanation for the industrially useful mechanical percolation. Furthermore, I use \emph{RGC} to quantitatively characterize the effects of interphase growth and spatial CNT clustering in a real polymer nanocomposite system of experimental interest. Advisors/Committee Members: HEROY, SAMUEL, MUCHA, PETER, MUCHA, PETER, FOREST, GREGORY, KLOTSA, DAPHNE, DINGEMANS, THEO, Adalsteinsson, David.

Subjects/Keywords: College of Arts and Sciences; Department of Mathematics

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

HEROY, S. (2018). Rigidity Percolation in Disordered Fiber Systems: Theory and Applications. (Thesis). University of North Carolina. Retrieved from https://cdr.lib.unc.edu/record/uuid:456c1173-d48e-4b39-a6d5-a64b92248b17

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):

HEROY, SAMUEL. “Rigidity Percolation in Disordered Fiber Systems: Theory and Applications.” 2018. Thesis, University of North Carolina. Accessed November 23, 2020. https://cdr.lib.unc.edu/record/uuid:456c1173-d48e-4b39-a6d5-a64b92248b17.

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

MLA Handbook (7th Edition):

HEROY, SAMUEL. “Rigidity Percolation in Disordered Fiber Systems: Theory and Applications.” 2018. Web. 23 Nov 2020.

Vancouver:

HEROY S. Rigidity Percolation in Disordered Fiber Systems: Theory and Applications. [Internet] [Thesis]. University of North Carolina; 2018. [cited 2020 Nov 23]. Available from: https://cdr.lib.unc.edu/record/uuid:456c1173-d48e-4b39-a6d5-a64b92248b17.

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

Council of Science Editors:

HEROY S. Rigidity Percolation in Disordered Fiber Systems: Theory and Applications. [Thesis]. University of North Carolina; 2018. Available from: https://cdr.lib.unc.edu/record/uuid:456c1173-d48e-4b39-a6d5-a64b92248b17

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

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