40,197 research outputs found
Tuning thermal transport in nanotubes with topological defects
Using the atomistic nonequilibrium Green's function, we find that thermal
conductance of carbon nanotubes with presence of topological lattice imperfects
is remarkably reduced, due to the strong Rayleigh scattering of high-frequency
phonons. Phonon transmission across multiple defects behaves as a cascade
scattering based with the random phase approximation. We elucidate that phonon
scattering by structural defects is related to the spatial fluctuations of
local vibrational density of states (LVDOS). An effective method of tuning
thermal transport in low-dimensional systems through the modulation of LVDOS
has been proposed. Our findings provide insights into experimentally
controlling thermal transport in nanoscale devicesComment: 10 pages, 3 figure
Recovery of Sparse Signals Using Multiple Orthogonal Least Squares
We study the problem of recovering sparse signals from compressed linear
measurements. This problem, often referred to as sparse recovery or sparse
reconstruction, has generated a great deal of interest in recent years. To
recover the sparse signals, we propose a new method called multiple orthogonal
least squares (MOLS), which extends the well-known orthogonal least squares
(OLS) algorithm by allowing multiple indices to be chosen per iteration.
Owing to inclusion of multiple support indices in each selection, the MOLS
algorithm converges in much fewer iterations and improves the computational
efficiency over the conventional OLS algorithm. Theoretical analysis shows that
MOLS () performs exact recovery of all -sparse signals within
iterations if the measurement matrix satisfies the restricted isometry property
(RIP) with isometry constant The recovery performance of MOLS in the noisy scenario is also
studied. It is shown that stable recovery of sparse signals can be achieved
with the MOLS algorithm when the signal-to-noise ratio (SNR) scales linearly
with the sparsity level of input signals
Next-to-next-to-leading order -jettiness soft function for production
We calculate the -jettiness soft function for production up to
next-to-next-to-leading order in QCD, which is an important ingredient of the
-jettiness subtraction method for predicting the differential cross sections
of massive coloured particle productions. The divergent parts of the results
have been checked using the renormalization group equations controlled by the
soft anomalous dimension.Comment: 14 pages, 3 figures, published version in PL
Fully Differential Higgs Pair Production in Association With a Boson at Next-to-Next-to-Leading Order in QCD
To clarify the electroweak symmetry breaking mechanism, we need to probe the
Higgs self-couplings, which can be measured in Higgs pair productions. The
associated production with a vector boson is special due to a clear tag in the
final state. We perform a fully differential next-to-next-to-leading-order
calculation of the Higgs pair production in association with a boson at
hadron colliders, and present numerical results at the 14 TeV LHC and a future
100 TeV hadron collider.Comment: 7 pages, 7 figures, matched to the published version in PL
Mode-coupling theory and molecular dynamics simulation for heat conduction in a chain with transverse motions
We study heat conduction in a one-dimensional chain of particles with
longitudinal as well as transverse motions. The particles are connected by
two-dimensional harmonic springs together with bending angle interactions. The
problem is analyzed by mode-coupling theory and compared with molecular
dynamics. We find very good, quantitative agreement for the damping of modes
between a full mode-coupling theory and molecular dynamics result, and a
simplified mode-coupling theory gives qualitative description of the damping.
The theories predict generically that thermal conductance diverges as N^{1/3}
as the size N increases for systems terminated with heat baths at the ends. The
N^{2/5} dependence is also observed in molecular dynamics which we attribute to
crossover effect.Comment: 17 pages, 13 figure
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