7,753 research outputs found
Pushing towards the Limit of Sampling Rate: Adaptive Chasing Sampling
Measurement samples are often taken in various monitoring applications. To
reduce the sensing cost, it is desirable to achieve better sensing quality
while using fewer samples. Compressive Sensing (CS) technique finds its role
when the signal to be sampled meets certain sparsity requirements. In this
paper we investigate the possibility and basic techniques that could further
reduce the number of samples involved in conventional CS theory by exploiting
learning-based non-uniform adaptive sampling.
Based on a typical signal sensing application, we illustrate and evaluate the
performance of two of our algorithms, Individual Chasing and Centroid Chasing,
for signals of different distribution features. Our proposed learning-based
adaptive sampling schemes complement existing efforts in CS fields and do not
depend on any specific signal reconstruction technique. Compared to
conventional sparse sampling methods, the simulation results demonstrate that
our algorithms allow less number of samples for accurate signal
reconstruction and achieve up to smaller signal reconstruction error
under the same noise condition.Comment: 9 pages, IEEE MASS 201
Kinetic Ballooning Mode Under Steep Gradient: High Order Eigenstates and Mode Structure Parity Transition
The existence of kinetic ballooning mode (KBM) high order (non-ground)
eigenstates for tokamak plasmas with steep gradient is demonstrated via
gyrokinetic electromagnetic eigenvalue solutions, which reveals that eigenmode
parity transition is an intrinsic property of electromagnetic plasmas. The
eigenstates with quantum number for ground state and for
non-ground states are found to coexist and the most unstable one can be the
high order states (). The conventional KBM is the state. It is
shown that the KBM has the same mode structure parity as the
micro-tearing mode (MTM). In contrast to the MTM, the KBM can be driven
by pressure gradient even without collisions and electron temperature gradient.
The relevance between various eigenstates of KBM under steep gradient and edge
plasma physics is discussed.Comment: 6 pages, 6 figure
Poly[bisÂ[μ2-2-(1H-1,2,4-triazol-1-yl)acetato]zinc(II)]
In the title compound, [Zn(C4H4N3O2)2]n, the ZnII atom is coordinated by two O atoms [Zn—O = 1.969 (2) and 1.997 (2) Å] and two N atoms [Zn—N = 2.046 (2) and 2.001 (2) Å] in a distorted tetraÂhedral geometry. Non-classical interÂmolecular C—H⋯O hydrogen bonds link the complex into a three-dimensional supraÂmolecular framework
BSG alignment of SDSS galaxy groups
We study the alignment signal between the distribution of brightest satellite
galaxies (BSGs) and the major axis of their host groups using SDSS group
catalog constructed by Yang et al. (2007). After correcting for the effect of
group ellipticity, a statistically significant (~ 5\sigma) major-axis alignment
is detected and the alignment angle is found to be 43.0 \pm 0.4 degrees. More
massive and richer groups show stronger BSG alignment. The BSG alignment around
blue BCGs is slightly stronger than that around red BCGs. And red BSGs have
much stronger major-axis alignment than blue BSGs. Unlike BSGs, other
satellites do not show very significant alignment with group major axis. We
further explore the BSG alignment in semi-analytic model (SAM) constructed by
Guo et al. (2011). We found general good agreement with observations: BSGs in
SAM show strong major-axis alignment which depends on group mass and richness
in the same way as observations; and none of other satellites exhibit prominent
alignment. However, discrepancy also exists in that the SAM shows opposite BSG
color dependence, which is most probably induced by the missing of large scale
environment ingredient in SAM. The combination of two popular scenarios can
explain the detected BSG alignment. The first one: satellites merged into the
group preferentially along the surrounding filaments, which is strongly aligned
with the major axis of the group. The second one: BSGs enter their host group
more recently than other satellites, then will preserve more information about
the assembling history and so the major-axis alignment. In SAM, we found
positive evidence for the second scenario by the fact that BSGs merged into
groups statistically more recently than other satellites. On the other hand,
although is opposite in SAM, the BSG color dependence in observation might
indicate the first scenario as well.Comment: 8 pages, 11 figures, ApJ accepte
Multifractal Modelling of Aircraft Echoes from Low-resolution Radars Based on Structural Functions
As a kind of complex targets, the nonrigid vibration and attitude change of an aircraft as well as the rotation of its rotating parts will induce complex nonlinear modulation on its echo from low-resolution radars. If one performs the multifractal analysis of measures on an aircraft echo, it may offer a fine description of the dynamic characteristics which induce the echo structure. On basis of introducing multifractal theory based on structural functions, the paper models real recorded aircraft echo data from a low-resolution radar by using the random walk process and the incremental process respectively, and investigates the application of echo multifractal characteristics in aircraft target classification with low-resolution radars. The analysis shows that aircraft echoes from low-resolution radars have clear multifractal characteristics, and one should take an aircraft echo series as a random walk process to perform the multifractal analysis. The experimental results validate the classification method based on multifractal signatures.Defence Science Journal, 2013, 63(5), pp.515-520, DOI:http://dx.doi.org/10.14429/dsj.63.377
Nonplanar On-shell Diagrams and Leading Singularities of Scattering Amplitudes
Bipartite on-shell diagrams are the latest tool in constructing scattering
amplitudes. In this paper we prove that a Britto-Cachazo-Feng-Witten
(BCFW)-decomposable on-shell diagram process a rational top-form if and only if
the algebraic ideal comprised of the geometrical constraints is shifted
linearly during successive BCFW integrations. With a proper geometric
interpretation of the constraints in the Grassmannian manifold, the rational
top-form integration contours can thus be obtained, and understood, in a
straightforward way. All rational top-form integrands of arbitrary higher loops
leading singularities can therefore be derived recursively, as long as the
corresponding on-shell diagram is BCFW-decomposable.Comment: 13 pages with 12 figures; final version appeared in Eur.Phys.J. C77
(2017) no.2, 8
Mott Physics and Topological Phase Transition in Correlated Dirac Fermions
We investigate the interplay between the strong correlation and the
spin-orbital coupling in the Kane-Mele-Hubbard model and obtain the qualitative
phase diagram via the variational cluster approach. We identify, through an
increase of the Hubbard , the transition from the topological band insulator
to either the spin liquid phase or the easy-plane antiferromagnetic insulating
phase, depending on the strength of the spin-orbit coupling. A nontrivial
evolution of the bulk bands in the topological quantum phase transition is also
demonstrated.Comment: 5 pages, 4 figures. Due to the limit of file size, a clear Fig.4 is
available on reques
Remote information concentration and multipartite entanglement in multilevel systems
Remote information concentration (RIC) in -level systems (qudits) is
studied. It is shown that the quantum information initially distributed in
three spatially separated qudits can be remotely and deterministically
concentrated to a single qudit via an entangled channel without performing any
global operations. The entangled channel can be different types of genuine
multipartite pure entangled states which are inequivalent under local
operations and classical communication. The entangled channel can also be a
mixed entangled state, even a bound entangled state which has a similar form to
the Smolin state, but has different features from the Smolin state. A common
feature of all these pure and mixed entangled states is found, i.e., they have
common commuting stabilizers. The differences of qudit-RIC and qubit-RIC
() are also analyzed.Comment: 10 pages, 3 figure
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