17,060 research outputs found
Investigation of kilovolt ion sputtering second quarterly progress report
Kilovolt ion sputtering - electron beam focusing of cesium ion beam, radiation detection in copper atoms, ultrahigh vacuum system construction, and spectrometer pulse heigh
Modeling coronal magnetic field using spherical geometry: cases with several active regions
The magnetic fields in the solar atmosphere structure the plasma, store free
magnetic energy and produce a wide variety of active solar phenomena, like
flare and coronal mass ejections(CMEs). The distribution and strength of
magnetic fields are routinely measured in the solar surface(photosphere).
Therefore, there is considerable interest in accurately modeling the 3D
structure of the coronal magnetic field using photospheric vector magnetograms.
Knowledge of the 3D structure of magnetic field lines also help us to interpret
other coronal observations, e.g., EUV images of the radiating coronal plasma.
Nonlinear force-free field (NLFFF) models are thought to be viable tools for
those task. Usually those models use Cartesian geometry. However, the spherical
nature of the solar surface cannot be neglected when the field of view is
large. In this work, we model the coronal magnetic field above multiple active
regions using NLFFF extrapolation code using vector magnetograph data from the
Synoptic Optical Long-term Investigations of the Sun survey (SOLIS)/ Vector
Spectromagnetograph (VSM) as a boundary conditions. We compare projections of
the resulting magnetic field lines solutions with their respective coronal
EUV-images from the Atmospheric Imaging Assembly (SDO/AIA) observed on October
11, 2011 and November 13, 2012. This study has found that the NLFFF model in
spherical geometry reconstructs the magnetic configurations for several active
regions which agrees with observations. During October 11, 2011 observation,
there are substantial number of trans-equatorial loops carrying electric
current.Comment: 3 Figures, Submitted to Astrophysics and Space Science Journa
Simulation of How Jack Pine Budworm (Lepidoptera: Tortricidae) Affects Economic Returns From Jack Pine Timber Production in Michigan
The impact of jack pine budworm on economic returns from jack pine timber production in Lower Michigan and management actions that might be taken to reduce this impact were evaluated with a simulation model. Results indicate that current jack pine rotation ages arc excessive and should be reduced. Insecticide application is not a viable strategy for reducing jack pine budworm impact
Investigation of kilovolt ion sputtering Quarterly progress report, May - Jul. 1966
Aluminum sputtering, and neutron activation analysis after cesium ion bombardmen
Inefficiency of classically simulating linear optical quantum computing with Fock-state inputs
Aaronson and Arkhipov recently used computational complexity theory to argue
that classical computers very likely cannot efficiently simulate linear,
multimode, quantum-optical interferometers with arbitrary Fock-state inputs
[Aaronson and Arkhipov, Theory Comput. 9, 143 (2013)]. Here we present an
elementary argument that utilizes only techniques from quantum optics. We
explicitly construct the Hilbert space for such an interferometer and show that
its dimension scales exponentially with all the physical resources. We also
show in a simple example just how the Schr\"odinger and Heisenberg pictures of
quantum theory, while mathematically equivalent, are not in general
computationally equivalent. Finally, we conclude our argument by comparing the
symmetry requirements of multiparticle bosonic to fermionic interferometers
and, using simple physical reasoning, connect the nonsimulatability of the
bosonic device to the complexity of computing the permanent of a large matrix.Comment: 7 pages, 1 figure Published in PRA Phys. Rev. A 89, 022328 (2014
Imperfect identity
Questions of identity over time are often hard to answer. A long
tradition has it that such questions are somehow soft: they have no unique,
determinate answer, and disagreements about them are merely verbal. I
argue that this claim is not the truism it is taken to be. Depending on how
it is understood, it turns out either to be false or to presuppose a highly
contentious metaphysical claim
Simulations of Spinodal Nucleation in Systems with Elastic Interactions
Systems with long-range interactions quenched into a metastable state near
the pseudospinodal exhibit nucleation that is qualitatively different than the
classical nucleation observed near the coexistence curve. We have observed
nucleation droplets in our Langevin simulations of a two-dimensional model of
martensitic transformations and have determined that the structure of the
nucleating droplet differs from the stable martensite structure. Our results,
together with experimental measurements of the phonon dispersion curve, allow
us to predict the nature of the droplet. These results have implications for
nucleation in many solid-solid transitions and the structure of the final
state
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