Statistical, Nonlinear, and Soft Matter Physics Commons^™

Discrete Space-Time Model For Heat Conduction: Application To Sizedependent Thermal Conductivity In Nano-Films, Sergey Sobolev

Sergey Sobolev

No abstract provided.

Interface Propagation And Nucleation Phenomena For Discontinuous Poisoning Transitions In Surface-Reaction Models, James W. Evans, T. R. Ray

James W. Evans

Here, we consider discontinuous nonequilibrium phase transitions to poisoned or ‘‘adsorbing’’ states in lattice-gas models of surface reactions. Specifically, we examine the monomer or CO-poisoning transition in the Ziff-Gulari-Barshad monomer-dimer reaction model for CO oxidation, modified to include adspecies diffusion. For CO pressures below the poisoning transition, we first characterize the propagation of and fluctuations at an interface between reactive and CO-poisoned states. Here, we utilize ideas from spatial contact models, reaction-diffusion theory, and kinetic roughening theory. Evolution is described by the Kardar-Parisi-Zhang equation, but with the nonlinearity and kinetic surface tension vanishing on approaching the transition. Next, again for ...

Kinetics Of The Monomer-Monomer Surface Reaction Model, James W. Evans, T. R. Ray

James W. Evans

The two-dimensional monomer-monomer (AB) surface reaction model without diffusion is considered for infinitesimal, finite, and infinite reaction rates k. For equal reactant adsorption rates, in all cases, simulations reveal the same form of slow poisoning, associated with clustering of reactants. This behavior is also the same as that found in simulations of the two-dimensional voter model studied in interacting-particle systems theory. The voter model can also be obtained from the dimer-dimer or monomer-dimer surface reaction models with infinitesimal reaction rate. We provide a detailed elucidation of the slow poisoning kinetics via an analytic treatment for the k=0+ AB reaction ...

Theory Of Helicoids And Skyrmions In Confined Cholesteric Liquid Crystals, Sajedeh Afghah, Jonathan Selinger

Jonathan Selinger

Determining The Grain Size Of Polycrystalline Diamond For High Energy Density Experiments, Lauren Barmore

Undergraduate Research and Arts Exposition

The High Energy Density Sciences group at SLAC National Accelerator Laboratory uses shock waves produced by the Linac Coherent Light Source to dynamically compress polycrystalline diamond samples. Compressing these polycrystalline samples allows us to use x-ray diffraction to study the changes to the structure as it experiences high pressure conditions. Polycrystalline diamond is valuable to study because it can be formed into ablator capsules for use in inertial confinement fusion reactions. As a result of the shock compression, the polycrystalline diamond samples undergo dynamic compression, a combination of stress and strain. To understand how dynamic compression takes place in a ...

Effective Temperature In Nonequilibrium State With Heat Flux Using Discrete Variable Model, Sergey Sobolev

Sergey Sobolev

Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory

University of Tennessee Honors Thesis Projects

No abstract provided.

Modeling Out-Of-Plane Actuation In Thin-Film Nematic Polymer Networks: From Chiral Ribbons To Auto-Origami Boxes Via Twist And Topology, Vianney Gimenez-Pinto, Fangfu Ye, Badel Mbanga, Jonathan Selinger, Robin Selinger

Jonathan Selinger

Code For "Noise-Enhanced Coding In Phasic Neuron Spike Trains", Cheng Ly, Brent D. Doiron

Statistical Sciences and Operations Research Data

This zip file contains Matlab scripts and ode (XPP) files to calculate the statistics of the models in "Noise-Enhanced Coding in Phasic Neuron Spike Trains". This article is published in PLoS ONE.

Morphology Of Thin Sheets In The Lame Setup And Beyond, Zhanlong Qiu

Doctoral Dissertations

We present a general analytical approach to study the wrinkling phenomena in the Lame, sheet on drop, drop on sheet, and twisted ribbon setups. In the partially single-mode wrinkle pattern, we employ the boundary layer analysis to regularize the divergence in the energy and obtain the optimal wavenumber. In the multi-mode wrinkle pattern scenario, we consider the effects of the boundary condition, meniscus, and the geometry of the setup separately on the energies and obtain scaling results for the wavenumber of the multi-mode pattern due to each effect. Lastly, a wrinkle-to-fold transition is discussed in the Lame setup, with our ...

Enzymatically Active Microspheres For Self-Propelled Colloidal Engines, Jungeun Park

Master's Theses

Micro- and nano-motors have attracted numerous attentions from various scientific areas due to their potential applications. Most studies on self-propelled colloidal engines have exploited catalytic decomposition of hydrogen peroxide to drive the motor. Since the hydrogen peroxide is caustic, it is not suitable to use in biological applications, encouraging people to develop “greener” fuels. The aim of this research is to study a new transduction mechanism for self-propulsion not tied to hydrogen peroxide, and which can in particular be used with biological molecules as fuels. In this study, we focus on making particles with enzymatic activity which can effectively decompose ...

Two-Photon Polymerization Of Soft Matter Composites, Yasser Albarakat

Undergraduate Honors Theses

With two-photon photopolymerization (2PP), it is possible to design and produce composite materials with three dimensional control and sub-micron precision, thanks to highly localized nonlinear process of polymerization. In this work, the feasibility of fabricating mesostructured composite particles with pre-defined shape and topology is examined. We explored polymerizable materials from both commercial sources and laboratory products as well as variable laser parameters, including pulse width and intensity along with dwell time, to find optimum conditions for 2PP. Later 2PP was performed on polymerizable materials containing quantum dots dispersion and the optical response of the resultant composite was characterized with spectroscopy ...

Memory Effects In Brownian Motion, Random Walks Under Confining Potentials, And Relaxation Of Quantum Systems, Matthew Chase

Physics & Astronomy ETDs

This dissertation is a report on a number of distinct topics in the field of non-equilibrium statistical mechanics including the evolution of classical as well as quantum systems.

The evolution of an object that is described by the Ornstein-Uhlenbeck process generalized through a time-nonlocal attraction is considered. The time-nonlocality is taken to be represented in the Langevin description through the presence of memory. Analysis of the Langevin equation is performed for algebraic and delay-type memories. An equivalent \emph{bona-fide} Fokker-Planck equation is constructed.

A random walker subjected to a non-standard confining potential, taken to be a piece-wise linear function, is ...

Elasticity Of Cylindrical Black Holes, Conrad Pearson

Physics

Black holes are regions of strong gravity, and are often regarded as behaving like drops of fluid. When this line of thought is applied to cylindrical black holes (black cylinders), a mapping can be made between known instabilities for black cylinders and ordinary fluid cylinders. However, this known correlation is increasingly less accurate for lower spatial dimensions, and I seek to correct this discrepancy in this thesis. By considering soft solids instead of pure fluids, elastic energy can be included, which brings us closer to a direct comparison. In improving this mapping, it becomes possible to better understand the behavior ...

Large Scale Brownian Dynamics Simulation Of Dilute And Semidilute Polymeric Solutions, Amir Saadat

Doctoral Dissertations

Excluded Volume (EV) and Hydrodynamic Interactions (HI) play a central role in static and dynamic properties of macromolecules in solution under equilibrium and nonequilibrium settings. The computational cost of incorporating HI in mesoscale Brownian dynamics (BD) simulations, particularly in the semidilute regime has motivated significant research aimed at development of high-fidelity and efficient techniques.

In this study, I have developed several algorithms for the mesoscale bead-spring representation of a macromolecular solution in dilute and semidilute regimes. The Krylov subspace method enables fast calculation of single chain dynamics with simulation time scaling of O(N_b²) [order N subscript b ...

Why Does The Liquid Crystal Rotate?, Jonathan Selinger

Jonathan Selinger

No abstract provided.

Interplay Of Quantum Size Effect, Anisotropy And Surface Stress Shapes The Instability Of Thin Metal Films, Mikhail Khenner

Mikhail Khenner

The Effect Of Attractive Polymer-Nanoparticle Interactions On The Local Segmental Dynamics Of Polymer Nanocomposites, Adam Prillaman Holt

Doctoral Dissertations

Considerable progress has been made in understanding the miscibility and morphology of polymer nanocomposites (PNCs). However, to date, there is little understood concerning the modification of segmental mobility at the polymer-nanoparticle interface, which due to prevalence of interfaces in PNCs, will predominately control the viscoelastic and mechanical properties of these materials.

In this dissertation, static and dynamic experimental techniques are combined to identify the specific parameters controlling the modification of segmental dynamics at the polymer-nanoparticle interface in the model system of poly(2-vinyl pyridine)/silica nanocomposites. In general, the experimental results clearly demonstrate that the segmental dynamics at the polymer-nanoparticle ...

Fluctuation Modes Of A Twist-Bend Nematic Liquid Crystal, Z. Parsouzi, Shaikh Shamid, Volodymyr Borshch, P. K. Challa, A. R. Baldwin, M. G. Tamba, C. Welch, G. H. Mehl, J. T. Gleeson, Antal Jakli, Oleg Lavrentovich, David W. Allender, Jonathan Selinger, Samuel Sprunt

Jonathan Selinger

Classical Transport In Disordered Systems, Antonios Papaioannou

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non-Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase ϕ to the ...