The thesis is dedicated to the understanding and characterization of brittle compressive fracture of columnar S2 ice. The work quantifies the strength of fresh-water S2 ice and investigates its characteristic brittle failure modes under biaxial...
Proper chromosome alignment and segregation depends on the formation and maintenance of a bipolar mitotic spindle with focused poles. It has been shown that microtubules are focused at spindle poles through the combined actions of centrosomes and a...
Electric fields in the high-latitude regions of Earth's ionosphere are an important component of the coupled magnetosphere-ionosphere-thermosphere system. Characterizing the average behavior of these fields (or the corresponding drifts) is useful...
Experimental and theoretical aspects of macroscopic and mesoscopic elastic instability are investigated in this thesis. For the theoretical investigations we utilize a Lagrangian formulation of nonlinear continuum elasticity theory, the novel...
Ice mechanics. Compressibility. Fracture mechanics. Strains and stresses. Brittleness.
This work describes the effect of triaxial compressive confinement on the strength of columnar S2 ice loaded under conditions leading to brittle failure. Cubes of columnar S2 ice were tested at -10 °C under triaxial (proportional) loading where...
Van Allen radiation belts -- Mathematical models. Electrons -- Diffusion -- Mathematical models. Magnetohydrodynamic waves -- Mathematical models.
It is becoming increasingly important to understand the dynamics of radiation belt energetic particles given their potentially hazardous effects on satellites and our ever-increasing dependence on those satellites. There is a need to determine...
Robots -- Control systems. ; Robots -- Motion. ; Computer algorithms. ; Electronic data processing -- Distributed processing.
Self-reconfiguring robots are robots composed of many physically connected modules which can change their structural configuration to support multiple functionalities. We claim that self-reconfiguring robots are more versatile, extensible, and...
Two-phase flow -- Mathematical models. ; Gas dynamics -- Mathematical models. ; Kinetic theory of gases.
The kinetic theory based gas-dynamical computational method, due to (Prendergast and Xu, 1993: Xu and Prendergast, 1994) is generalized to two-phase flow computations. The Bhatnagar-Gross-Krook kinetic model is generalized to the case of two...
1981 Dartmouth Women's Gymnastics team- Front row, from left: Coach Michael Rizzuto, Denise Cloutier, Stephanie Lifton, Captain Paula Shear, Debbie McCoy and manager Jenny Merchant. Back row, from left: Beth Cohen, Deenya Rabius, Mary Haney, Kathy...
The purpose of this thesis is to describe methods for detecting hidden crevasses on glaciers in Polar regions. Crevasses form in ice sheets as a result of forces imposed upon the brittle ice. The crevasses are hidden from view by bridges of soft...
Cataclysmic variable stars (CVs) are close, interacting binary systems comprised of a white dwarf and a companion star, which is typically a late-type dwarf star. Their progenitor systems are post common envelope binaries (PCEBs) with a white dwarf...
Through a series of case studies, signal processing and statistical tools, analyses of dynamic sea ice processes of drift, deformation, and ice pack expansion and decay are investigated for the Weddell Sea region during 1992. Cavitating fluid (CAV)...
Coherent states. Quantum field theory. Nonlinear theories.
In this thesis we study the properties of time-dependent, nontopological configurations and their effect on the macroscopic properties of a system described by a nonlinear field theory. These structures seem to be ubiquitous in relativistic field...
Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD...
This dissertation explores the spatial and temporal distributions of impurities in natural ice. Using polarized light, ion chromatography (IC), synchrotron x-ray topography (SXT), scanning electron microscopy (SEM), and energy-dispersive...
Plasma instabilities. ; Ionospheric electron density. ; Ionosphere.
As a result of an unstable plasma stratification the nighttime equatorial ionosphere is subject to a variety of plasma instabilities known commonly as equatorial spread-F. In its fully developed form spread-F consists of large wedges of depleted...
Geomagnetic micropulsations. ; Magnetosphere. ; Cosmic magnetic fields -- Measurement.
A study of magnetospheric pulsations is presented in three parts. The first consists of a statistical survey using data from the AMPTE/IRM satellite. A number of conclusions are drawn from the study. Evidence is provided that supports the theory...
The effects of vacancies on the mechanical properties of FeAl single crystals and polycrystals have been investigated. Scanning calorimetric results indicate that vacancies in quenched Fe-40Al undergo rearrangement at ~550K, and then annihilate at...
Cellulase -- Biotechnology. ; Hydrolysis. ; Paper industry -- Technological innovations. ; Biomass energy -- Economic aspects. ; Saccharomyces cerevisiae -- Genetics. ; Enzymes -- Industrial applications.
Paper sludge is the largest solid waste stream produced by pulp and paper industry, and is also an attractive feedstock for emergent technologies based on processing of cellulosic biomass featuring enzymatic hydrolysis. This study focuses on...
Ocean circulation -- Georges Bank -- Mathematical models. ; Submarine topography -- Georges Bank.
A two-dimensional continuously-stratified model is derived for the study of instability properties of oceanic density fronts in the presence of sloping bottom topography. While the model retains several traditional assumptions, such as uniformity...
A method for the reconstruction of a spectrum of mechanical properties from phase-contrast, MR displacement data is developed and implemented via the finite element method. To overcome the significant computational load associated with...
Three-dimensional imaging in medicine -- Mathematical models. Diagnostic imaging -- Digital techniques. Brain -- Magnetic resonance imaging. Inverse problems (Differential equations).
An accurate registration between the preoperative images and the current surgical scene is critical to image-guided neurosurgery. However, during a neuro-surgical intervention, brain tissues shift and degrade the accuracy of the registration....
Laser speckle monitoring is a way to measure the motion of an optically rough surface without making physical contact to that surface. Laser speckle is inherently sensitive to motion in the plane of the reflecting surface, which gives speckle...