Physics Commons^™

Application Of The Fokker-Planck Equation For Quantifying Initial Condition Uncertainty Of Reversible Dynamic Systems, Troy S. Newhart

Mechanical & Aerospace Engineering Theses & Dissertations

Characterizing the behavior of dynamic systems requires the inclusion of initial conditions to propagate behavior forward in time. More realistic representations of system behavior quantify uncertainty about the initial conditions to assess sensitivity, reliability, and other stochastic response parameters. In many engineering applications, the uncertain initial conditions may be unknown given a desired response. This research applies the Fokker-Planck equation to reversible dynamic systems of select multi-dimensional nonlinear differential equations as a means for predicting the uncertainty about initial conditions. An alternating directions implicit numerical scheme is used to numerically solve the Fokker-Planck equation for both forward and reversed equations …

Quantifying Confinement Of Chain Dynamics For Chains Tethered To Self-Assembling Crystalline Nanodomains Using Neutron Spin Echo Spectroscopy, Logan Benninghoff

Williams Honors College, Honors Research Projects

Polyisobutylene (PIB) rubbers can be reinforced with crystalline β-alanine nanodomains. Progress has been made in understanding the morphology of the nanodomains, but the dynamics of the PIB molecule chains attached to the surface of the nanodomains and in the matrix are not well understood. It is possible to observe the motion of these PIB chains using Neutron Spin Echo (NSE) experiments, since the experimental technique can give data for smaller timescales. Data collection for reinforced rubber samples has already been performed, but the data still need to be analyzed. For my honors project I will be comparing the data to …

Composite Network Of Actin And Microtubule Filaments, Self-Organization And Steady-State Dynamics, Leila Farhadi

Doctoral Dissertations

Actin and microtubule filaments, with their auxiliary proteins, enable the cytoskeleton to perform vital processes in the cell by tuning the organizational, mechanical properties and dynamics of the network. Despite their critical importance and interactions in cells, we are only beginning to uncover information about the composite network. Here, I use florescence microscopy to explore the role of filaments characteristics, interactions and activities in the self-organization and steady-state dynamics of the composite network of filaments. First, I discuss active self-organization of semiflexible actin and rigid microtubule filaments in the 2D composite network while myosin II and kinesin-1 motor proteins propel …

Emergent Phenomena In Quantum Critical Systems, Kun Chen

Doctoral Dissertations

A quantum critical point (QCP) is a point in the phase diagram of quantum matter where a continuous phase transition takes place at zero temperature. Low-dimensional quantum critical systems are strongly correlated, therefore hosting nontrivial emergent phenomena. In this thesis, we first address two decades-old problems on quantum critical dynamics. We then reveal two novel emergent phenomena of quantum critical impurity problems. In the first part of the thesis, we address the linear response dynamics of the $(2+1)$-dimensional $O(2)$ quantum critical universality class, which can be realized in the ultracold bosonic system near the superfluid (SF) to Mott insulator (MI) …

Structural Dynamics And Charge Transport In Room Temperature Ionic Liquids, Philip James Griffin

Doctoral Dissertations

Room temperature ionic liquids are an important class of materials due to their chemical tunability and numerous advantageous physicochemical properties. As a result, ionic liquids are currently being investigated for use in a wide array of chemical and electrochemical applications. Despite their great potential, however, the relationship between the chemical structure and physicochemical properties of ionic liquids is not well understood.

To this end, this dissertation presents experimental studies of the reorientational structural dynamics and charge transport properties of a variety of room temperature ionic liquids using quasielastic light scattering spectroscopy and broadband dielectric spectroscopy.

Studies of a series of …

High-Latitude Propagation Studies Using A Meridional Chain Of Lf/Mf/Hf Receivers, J Labelle

Dartmouth Scholarship

For over a decade, Dartmouth College has oper- ated programmable radio receivers at multiple high-latitude sites covering the frequency range 100–5000 kHz with about a 1-s resolution. Besides detecting radio emissions of auro- ral origin, these receivers record characteristics of the iono- spheric propagation of natural and man-made signals, docu- menting well-known effects, such as the diurnal variation in the propagation characteristics of short and long waves, and also revealing more subtle effects. For example, at auroral zone sites in equinoctial conditions, the amplitudes of dis- tant transmissions on MF/HF frequencies are often enhanced by a few dB just before …