This Site umd.edu

2015 Applied Dynamics Seminar Archives

September 10, 2015

When the Moon stays where it belongs: An introduction to quasiperiodicity

Prof. James Yorke

University of Maryland Distinguished Research Professor of Mathematics and Physics

 

September 17, 2015

What’s in a label? Language matrices and their dynamical interactions

Prof. Juan Uriagereka

University of Maryland, Dept of Linguistics

Abstract: Formal and generative linguistics has always assumed the manipulation of feature matrices in its operations. However, relatively little thought had been given, until the last decade or so, to how these putative matrices operate, beyond the assumption that they somehow do. This talk explicitly argues that matrix multiplication (Hadamard and Kronecker products) is a useful way to operate with linguistic matrices. Under standard linguistic assumptions (in particular "projection", the idea that a linguistic phrase of type X must immediately dominate another syntactic object of type X – e.g. a verb phrase contains a verb, a noun phrase contains a noun, etc.), this view of things predicts a number of distributional facts among phrasal dependents, which currently is not predicted in any other way. The formalism also has significant consequences for long-distance relations among phrases in syntax (e.g. conditions on question formation, ellipsis, etc.) and the study of grounding natural language on the mind/brain of speakers.

 

September 24, 2015

Optical and optomechanical response of visible frequency plasmonic metamaterials

Dr. Amit Agrawal

UMD, NIST-Nanocenter

 

October 1, 2015

A Low Paradigm for High Dimensional Chaos

S. Das

University of Maryland, Dept of Mathematics

 

October 8, 2015

The evolution and complexity of self-assembling structures in biology

Dr. Sebastian Ahnert

Cambridge University, Cavendish Lab

 

October 15, 2015

From oscillating candles to complex spatiotemporal arrhythmias in the heart

Prof. Flavio Fenton

Georgia Tech, School of Physics

 

October, 22, 2015

Electrostatic levitation of dust grains near the moon and asteroids

Prof. Christine Hartzell

University of Maryland, Department of Aerospace Engineering

 

October 29, 2015

Pressure driven flow of normal and super fluids through single nanopipes

Prof. Peter Taborek

University of California - Irvine, Department of Physics and Astronomy

Abstract: No slip boundary conditions successfully describe macroscopic flows near solids, but this boundary condition is not a law of physics, and several recent experiments have invoked large slip lengths to explain surprising results on flow through carbon nanotubes and other nanoscale flows. We will describe measurements of the mass flow rate as a function of pressure for flow through nanopipes made from single ion etch tracks 20 nm in diameter and glass tubes 200 nm in diameter. The extremely small flows involved are detected with a mass spectrometer. For classical fluids, our measurements always yield slip lengths less than 2 nm. For superfluid 4He , the flow rate has a complicated dependence on temperature and pressure which reflects the kinetics of vortex nucleation and vortex motion in the nanopipe.

 

November 5, 2015

Core-shell microgels: smart materials with tunable properties

Dr. Manis Chaudhuri

Harvard University

 

November 12, 2015

Quantifying stability in networks: From linear to basin stability

Juergen Kurths

Potsdam Inst. for Climate Impact and Humboldt University

 

November 19, 2015

Insects in a Changing World: Modeling Insect Populations In the Context of Climate and Land-Use Change

Dr. Sharon Bewick

University of Maryland, Department of Biology

 

November 26, 2015

THANKSGIVING BREAK

 

December 3, 2015

Wave chaos and enhancement of coherence with rippled waveguides

Dr. Dong Ho Wu

Naval Research Laboratory

 

December 10, 2015

The Spectrum of Wind Power Fluctuations

Mahesh Bandi

Okinawa Institute of Science and Technology

Abstract: Conventional energy sources such as nuclear or coal generate energy at a constant rate. Renewables on the other hand fluctuate with the variability in the natural sources from which they derive energy. Such fluctuations are particularly acute for wind and solar photovoltaics. On one hand, such fluctuations threaten the stability of the grid, whereas on the other, matching the fluctuating power production with a variable consumer demand presents scheduling difficulties for grid operators. Understanding fluctuations in renewables is also important for the design of robust smart grid technologies for the future. 

In this talk, I will chart out the non-equilibrium character of wind power fluctuations which depend upon the turbulent wind blowing past the wind turbines. Indeed, the spectrum of wind power fluctuations is widely known to reflect the Kolmogorov spectrum of turbulence; both vary with frequency $f$ as $f^{-5/3}$. Yet it has not been possible to derive this spectrum from the turbine power equation which relates the generated power $P$ to the wind speed $v$. I will explain the wind power fluctuation spectrum and show it arises from the violation of an underlying assumption in Kolmgorov theory of 1941 with crucial implications for wind power. In particular, every individual turbine feels the influence of the largest length scales of atmospheric turbulence. As a result, turbines within and between wind farms become coupled with each other at low turbulent frequencies over large distances. Consequently, when geographically distributed wind farms feed their power to the electrical grid, the fluctuations remain correlated and smooth out until they reach a theoretical bound that can be deduced from Kolmogorov theory. I will close my talk with a summary of engineering and policy implications of these results.