1,112 research outputs found
Networked Assembly of Affine Physical System Models
Engineering design is evolving into a global strategy that distributes engineering effort to team members around the world. Because modern engineering design uses analytical models, model information mus
Pacemaker-induced cardiomyopathy in the sheep: RVA but not RVOT pacing results in a heart failure cellular phenotype
Method of Collective Degrees of Freedom in Spin Coherent State Path Integral
We present a detailed field theoretic description of those collective degrees
of freedom (CDF) which are relevant to study macroscopic quantum dynamics of a
quasi-one-dimensional ferromagnetic domain wall. We apply spin coherent state
path integral (SCSPI) in the proper discrete time formalism (a) to extract the
relevant CDF's, namely, the center position and the chirality of the domain
wall, which originate from the translation and the rotation invariances of the
system in question, and (b) to derive effective action for the CDF's by
elimination of environmental zero-modes with the help of the {\it Faddeev-Popov
technique}. The resulting effective action turns out to be such that both the
center position and the chirality can be formally described by boson coherent
state path integral. However, this is only formal; there is a subtle departure
from the latter.Comment: 10 pages, 1 figur
Memetic Multilevel Hypergraph Partitioning
Hypergraph partitioning has a wide range of important applications such as
VLSI design or scientific computing. With focus on solution quality, we develop
the first multilevel memetic algorithm to tackle the problem. Key components of
our contribution are new effective multilevel recombination and mutation
operations that provide a large amount of diversity. We perform a wide range of
experiments on a benchmark set containing instances from application areas such
VLSI, SAT solving, social networks, and scientific computing. Compared to the
state-of-the-art hypergraph partitioning tools hMetis, PaToH, and KaHyPar, our
new algorithm computes the best result on almost all instances
Extended coherent states and modified perturbation theory
An extended coherent state for describing a system of two interacting quanum
objects is considered. A modified perturbation theory based on using the
extended coherent states is formulated.Comment: LaTex, 7 pages, no figures, minor correction
f-Oscillators and Nonlinear Coherent States
The notion of f-oscillators generalizing q-oscillators is introduced. For
classical and quantum cases, an interpretation of the f-oscillator is provided
as corresponding to a special nonlinearity of vibration for which the frequency
of oscillation depends on the energy. The f-coherent states (nonlinear coherent
states) generalizing q-coherent states are constructed. Applied to quantum
optics, photon distribution function, photon number means, and dispersions are
calculated for the f-coherent states as well as the Wigner function and
Q-function. As an example, it is shown how this nonlinearity may affect the
Planck distribution formula.Comment: Latex, 32 pages, accepted by Physica Script
Macroscopic Quantum Dynamics of a Free Domain Wall in a Ferromagnet
We study macroscopic quantum dynamics of a free domain wall in a
quasi-one-dimensional ferromagnet by use of the spin-coherent-state path
integral in {\it discrete-time} formalism. Transition amplitudes between
typical states are quantitatively discussed by use of {\it stationary-action
approximation} with respect to collective degrees of freedom representing the
center position and the chirality of the domain wall. It is shown that the
chirality may be loosely said to be canonically conjugate to the center
position; the latter moves with a speed depending on the former. It is
clarified under what condition the center position can be regarded as an
effective free-particle position, which exhibits the phenomenon of wave-packet
spreading. We demonstrate, however, that in some case the non-linear character
of the spin leads to such a dramatic phenomenon of a non-spreading wave packet
as to completely invalidate the free-particle analogy. In the course of the
discussion, we also point out various difficulties associated with the
continuous-time formalism.Comment: 23 pages, REVTEX, 4 figures, submitted to Phys. Rev.
Coherent pairing states for the Hubbard model
We consider the Hubbard model and its extensions on bipartite lattices. We
define a dynamical group based on the -pairing operators introduced by
C.N.Yang, and define coherent pairing states, which are combinations of
eigenfunctions of -operators. These states permit exact calculations of
numerous physical properties of the system, including energy, various
fluctuations and correlation functions, including pairing ODLRO to all orders.
This approach is complementary to BCS, in that these are superconducting
coherent states associated with the exact model, although they are not
eigenstates of the Hamiltonian.Comment: 5 pages, RevTe
Streamwater Dissolved Organic Carbon and Total Dissolved Nitrogen: Effects of Timber Harvest in the Georgia Piedmont
Proceedings of the 2011 Georgia Water Resources Conference, April 11, 12, and 13, 2011, Athens, Georgia.A paired watershed experiment of silvicultural best management practices first initiated in 1973 and harvested in 1974/75 was harvested for a second time in 2004. During the current harvest, BMPs were updated to reflect current guidelines. Stream water yield and physical and chemical attributes were monitored for one year pre-harvest and one year post-harvest. Here we report results for dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations and fluxes. In the treatment watershed, no response to harvest in the discharge-concentration relationship was observed. Based on double mass curves, however, the yield of DOC and TDN increased in the treatment watershed as a result of increased stream water fluxes, although the increased mass of DOC or TDN loss was relatively small.Sponsored by:
Georgia Environmental Protection Division
U.S. Geological Survey, Georgia Water Science Center
U.S. Department of Agriculture, Natural Resources Conservation Service
Georgia Institute of Technology, Georgia Water Resources Institute
The University of Georgia, Water Resources FacultyThis book was published by Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, Georgia 30602-2152. The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia, the U.S. Geological Survey, the Georgia Water Research Institute as authorized by the Water Research Institutes Authorization Act of 1990 (P.L. 101-307) or the other conference sponsors
Semiclassical description of Heisenberg models via spin-coherent states
We use spin-coherent states as a time-dependent variational ansatz for a
semiclassical description of a large family of Heisenberg models. In addition
to common approaches we also evaluate the square variance of the Hamiltonian in
terms of coherent states. This quantity turns out to have a natural
interpretation with respect to time-dependent solutions of the equations of
motion and allows for an estimate of quantum fluctuations in a semiclassical
regime. The general results are applied to solitons, instantons and vortices in
several one- and two-dimensional models.Comment: 14 page
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