Physical Sciences and Mathematics Commons^™

Using Transects To Understand Cyanobacterial Blooms, John Rueter

Environmental Science and Management Faculty Publications and Presentations

Presentation focuses on Toxic algae (and cyanobacteria) and on short-term mitigation:

• Monitoring
• Possible approaches

The Geometry And Density Of B-Emission Star Disks From Statistical Analysis And Numerical Simulations, Isabelle H. Cyr

Electronic Thesis and Dissertation Repository

This thesis is divided into 3 investigations. First we present a novel method to estimate the opening angles of Be star disks from interferometric axis ratio measurements, using Bayesian statistics and Monte Carlo techniques. A large set of theoretical axis ratios generated from disk models were compared to observational samples to determine which distribution best reproduces the observations. We find that the observed axis ratio distributions in the K-, H-, and N-band can best be explained by the presence of thin disks while measurements over the H$\alpha$ line point toward slightly thicker disks. Second, using a smoothed particle hydrodynamics (SPH) …

Understanding The Links Between Cyanobacteria Physiology And Hydrodynamics May Help Find Adaption Strategies For Toxic Blooms, John Rueter

Environmental Science and Management Faculty Publications and Presentations

Even though we are managing lakes to decrease algal blooms overall, harmful algal blooms seem to be showing up more and more frequently. Although the word “blooms” connotes dominance and rapid growth, dangerous accumulations of cyanobacteria can occur because of combinations of physiological advantages and particular weather and hydrodynamic conditions. I am particularly interested in specific conditions that might favor Aphanizomenon versus those that might favor Microcystis in Upper Klamath and Agency Lakes. Aphanizomenon is a nuisance and large blooms can lead to oxygen depletion and fish deaths. Microcystis can both be a nuisance and is toxic. The comparison of …

Hydrodynamic Theories For Flows Of Active Liquid Crystals And The Generalized Onsager Principle, Xiaogang Yang, Jun Li, M. Gregory Forest, Qi Wang

Faculty Publications

We articulate and apply the generalized Onsager principle to derive transport equations for active liquid crystals in a fixed domain as well as in a free surface domain adjacent to a passive fluid matrix. The Onsager principle ensures fundamental variational structure of the models as well as dissipative properties of the passive component in the models, irrespective of the choice of scale (kinetic to continuum) and of the physical potentials. Many popular models for passive and active liquid crystals in a fixed domain subject to consistent boundary conditions at solid walls, as well as active liquid crystals in a free …

Dynamics Of Discs In A Nematic Liquid Crystal, Alena Antipova

Electronic Thesis and Dissertation Repository

In this thesis, a new way of simulating a two-way coupling between a liquid crystal and an immersed object is proposed. It can be used for objects of various geometries and can be expanded to be used for an object of any geometry. Additionally, a simple yet effective model was suggested for calculations of transmitted light through a nematic liquid crystal sample. This model allowed us to clarify the behavior of a ferromagnetic disc in a nematic liquid crystal observed in experiments and incorrectly interpreted at that time.

Our simulations have demonstrated the following: in the absence of external forces …

Generalized Scaling And The Master Variable For Brownian Magnetic Nanoparticle Dynamics, Daniel B. Reeves, Yipeng Shi, John B. Weaver

Dartmouth Scholarship

Understanding the dynamics of magnetic particles can help to advance several biomedical nanotechnologies. Previously, scaling relationships have been used in magnetic spectroscopy of nanoparticle Brownian motion (MSB) to measure biologically relevant properties (e.g., temperature, viscosity, bound state) surrounding nanoparticles in vivo. Those scaling relationships can be generalized with the introduction of a master variable found from non-dimensionalizing the dynamical Langevin equation. The variable encapsulates the dynamical variables of the surroundings and additionally includes the particles’ size distribution and moment and the applied field’s amplitude and frequency. From an applied perspective, the master variable allows tuning to an optimal MSB …

Complex Capillary Fluidic Phenomena For Passive Control Of Liquids In Low-Gravity Environments, Logan Torres

Undergraduate Research & Mentoring Program

In an effort to further apply the recent results of puddle jumping research, we seek to expand the oblique droplet impact studies of others by exploiting large liquid droplets in the near weightless environment of a drop tower. By using the spontaneous puddle jump mechanism, droplets of volumes 1 mL ≤ V ≤ 3 mL with corresponding Weber numbers of We ≈ 1 are impinged on surfaces inclined in the range 40° ≤ α ≤ 80° (measured from the horizontal plane). Impact surface wetting characteristics exhibit static contact angles θstatic = 165 ± 5°. All impacts result in complete rebound. …

Simulating The Dispersal Of Invasive Clams In A Freshwater Lake Using A Three-Dimensional Hydrodynamic Model; A Prototype For Simulating Invasions In Marine Ecosystems, Elizabeth Kilanowski, Lambert Rubash

Salish Sea Ecosystem Conference

The discovery of several populations of an invasive Asian clam (corbicula fluminea) in Lake Whatcom, the drinking water source for approximately 100,000 people in Northern Washington State, created a need among elected officials, local government staff, and the public for a better understanding of lake hydrodynamics during the reproductive season for the Asian clam, and for times when Quagga and Zebra mussel invasions are likely. Seasonal vertical thermal stratification of the lake and a desire to predict likely locations of additional clam populations or of new populations of mussels led to the choice of a model that could be configured …

A Coin Vibrational Motor Swimming At Low Reynolds Number, Alice C. Quillen, Hesam Askari, Douglas H. Kelley, Tamar Friedmann, Patrick W. Oakes

Mathematics Sciences: Faculty Publications

Low-cost coin vibrational motors, used in haptic feedback, exhibit rotational internal motion inside a rigid case. Because the motor case motion exhibits rotational symmetry, when placed into a fluid such as glycerin, the motor does not swim even though its oscillatory motions induce steady streaming in the fluid. However, a piece of rubber foam stuck to the curved case and giving the motor neutral buoyancy also breaks the rotational symmetry allowing it to swim. We measured a 1 cm diameter coin vibrational motor swimming in glycerin at a speed of a body length in 3 seconds or at 3 mm/s. …

The Conflict Resolution Case Study In Urban Life: Bull Run Watershed Case, Chang-Yu Hong

Geography Faculty Publications and Presentations

The City of Portland and the United States Department of Agriculture (USDA) Forest Service are working together, along with citizens, to formulate a comprehensive new policy to guide joint management of the Bull Run watershed at Mt. Hood National Forest. This process has brought about four decades of conflict, resulting from differences between the federal view of multiple use and the local view of exclusive use for producing high quality water. The new policy is being formulated by the City of Portland and the Forest Service through negotiation of a comprehensive Memorandum of Understanding that structures the parties’ roles, responsibilities, …