112,333 research outputs found
Toroidal modeling of penetration of the resonant magnetic perturbation field
A toroidal, quasi-linear model is proposed to study the penetration dynamics
of the resonant magnetic perturbation (RMP) field into the plasma. The model
couples the linear, fluid plasma response to a toroidal momentum balance
equation, which includes torques induced by both fluid electromagnetic force
and by (kinetic) neoclassical toroidal viscous force. The numerical results for
a test toroidal equilibrium quantify the effects of various physical parameters
on the field penetration and on the plasma rotation braking. The neoclassical
toroidal viscous torque plays a dominant role in certain region of the plasma,
for the RMP penetration problem considered in this work.Comment: 20 pages, 14 figures. Copyright 2013 United Kingdom Atomic Energy
Authority. This article may be downloaded for personal use only. Any other
use requires prior permission of the author and the American Institute of
Physic
Tunable subpicosecond electron bunch train generation using a transverse-to-longitudinal phase space exchange technique
We report on the experimental generation of a train of subpicosecond electron
bunches. The bunch train generation is accomplished using a beamline capable of
exchanging the coordinates between the horizontal and longitudinal degrees of
freedom. An initial beam consisting of a set of horizontally-separated beamlets
is converted into a train of bunches temporally separated with tunable bunch
duration and separation. The experiment reported in this Letter unambiguously
demonstrates the conversion process and its versatility.Comment: 4 pages, 5 figures, 1 table; accepted for publication in PR
Tidal Waves -- a non-adiabatic microscopic description of the yrast states in near-spherical nuclei
The yrast states of nuclei that are spherical or weakly deformed in their
ground states are described as quadrupole waves running over the nuclear
surface, which we call "tidal waves". The energies and E2 transition
probabilities of the yrast states in nuclides with = 44, 46, 48 and are calculated by means of the cranking model in a microscopic
way. The nonlinear response of the nucleonic orbitals results in a strong
coupling between shape and single particle degrees of freedom
Probing and modelling the localized self-mixing in a GaN/AlGaN field-effect terahertz detector
In a GaN/AlGaN field-effect terahertz detector, the directional photocurrent
is mapped in the two-dimensional space of the gate voltage and the drain/source
bias. It is found that not only the magnitude, but also the polarity, of the
photocurrent can be tuned. A quasistatic self-mixing model taking into account
the localized terahertz field provides a quantitative description of the
detector characteristics. Strongly localized self-mixing is confirmed. It is
therefore important to engineer the spatial distribution of the terahertz field
and its coupling to the field-effect channel on the sub-micron scale.Comment: 12 pages, 4 figures, submitted to AP
The Child is Father of the Man: Foresee the Success at the Early Stage
Understanding the dynamic mechanisms that drive the high-impact scientific
work (e.g., research papers, patents) is a long-debated research topic and has
many important implications, ranging from personal career development and
recruitment search, to the jurisdiction of research resources. Recent advances
in characterizing and modeling scientific success have made it possible to
forecast the long-term impact of scientific work, where data mining techniques,
supervised learning in particular, play an essential role. Despite much
progress, several key algorithmic challenges in relation to predicting
long-term scientific impact have largely remained open. In this paper, we
propose a joint predictive model to forecast the long-term scientific impact at
the early stage, which simultaneously addresses a number of these open
challenges, including the scholarly feature design, the non-linearity, the
domain-heterogeneity and dynamics. In particular, we formulate it as a
regularized optimization problem and propose effective and scalable algorithms
to solve it. We perform extensive empirical evaluations on large, real
scholarly data sets to validate the effectiveness and the efficiency of our
method.Comment: Correct some typos in our KDD pape
Low-Temperature Thermal Conductivity of Superconductors With Gap Nodes
We report a detailed analytic and numerical study of electronic thermal
conductivity in d-wave superconductors. We compare theory of the cross over at
low temperatures from T-dependence to T^3-dependence for increasing temperature
with recent experiments on YBCO in zero magnetic field for temperatures from
0.04K to 0.4K by Hill et al., Phys. Rev. Lett. 92, 027001 (2004). Transport
theory, including impurity scattering and inelastic scattering within strong
coupling superconductivity, can consistently fit the temperature dependence of
the data in the lower half of the temperature regime. We discuss the conditions
under which we expect power-law dependences over wide temperature intervals.Comment: 4 pages, 3 figure
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