4,704 research outputs found
Some inequalities and limit theorems under sublinear expectations
In this note, we study inequality and limit theory under sublinear
expectations. We mainly prove Doob's inequality for submartingale and
Kolmogrov's inequality. By Kolmogrov's inequality, we obtain a special version
of Kolmogrov's law of large numbers. Finally, we present a strong law of large
numbers for independent and identically distributed random variables under
one-order type moment condition.Comment: 15 page
Shape and flow fluctuations in ultra-central Pb+Pb collisions at the LHC
In ultra-central heavy-ion collisions, anisotropic hydrodynamic flow is
generated by density fluctuations in the initial state rather than by geometric
overlap effects. For a given centrality class, the initial fluctuation spectrum
is sensitive to the method chosen for binning the events into centrality
classes. We show that sorting events by total initial entropy or by total final
multiplicity yields event classes with equivalent statistical fluctuation
properties, in spite of viscous entropy production during the fireball
evolution. With this initial entropy-based centrality definition we generate
several classes of ultra-central Pb+Pb collisions at LHC energies and evolve
the events using viscous hydrodynamics with non-zero shear but vanishing bulk
viscosity. Comparing the predicted anisotropic flow coefficients for charged
hadrons with CMS data we find that both the Monte Carlo Glauber (MC-Glb) and
Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) models produce initial fluctuation
spectra that are incompatible with the measured final anisotropic flow power
spectrum, for any choice of the specific shear viscosity. In spite of this
failure, we show that the hydrodynamic model can qualitatively explain, in
terms of event-by-event fluctuations of the anisotropic flow coefficients and
flow angles, the breaking of flow factorization for elliptic, triangular and
quadrangular flow measured by the CMS experiment. For elliptic flow, this
factorization breaking is large in ultra-central collisions. We conclude that
the bulk of the experimentally observed flow factorization breaking effects are
qualitatively explained by hydrodynamic evolution of initial-state
fluctuations, but that their quantitative description requires a better
understanding of the initial fluctuation spectrum.Comment: 11 pages, 11 figures; In v2 and the current version, we updated all
the calculations (except for Fig. 2) that do not include microscopic
NN-correlations with a hard core radius of 0.9 fm. In v1, some of the results
are done with a smaller hard core radius of 0.4 fm. We also reduced the
statistical errors in Figs. 5-8 by increasing the simulated events to 1000
for every set of the ru
New bounds and efficient algorithm for sparse difference resultant
Let be a
generic Laurent transformally essential system and
be its super essential system. We show that the sparse difference
resultant of a simplified system of by setting the
selected variables to one is the same to the one of .
Moreover, new order bounds of sparse difference resultant are obtained. Then we
propose an efficient algorithm to compute sparse difference resultant which is
the quotient of two determinants whose elements are the coefficients of the
polynomials in the strong essential system. We analyze complexity of the
algorithm. Experimental results show the efficiency of the algorithm
An experiential formula for the energy eigenvalues of a particle in a one-dimension finite-deep square well potential
We propose an experiential formula for the calculation of the energy
eigenvalues of a particle moving in a one-dimension finite-deep square well
potential after some physical considerations. This formula shows a simple
relation between the energy eigenvalues and the potential papameters, and can
be used to estimate the energy eigenvalues in a very simple way
Resonance Decay Contributions to Higher-Order Anisotropic Flow Coefficients
We show that in hydrodynamic simulations for relativistic heavy-ion
collisions, strong resonance decay calculations can be performed with fewer
species of particle resonances while preserving good accuracy in single
particle spectra and flow anisotropies. Such partial resonance calculations
boost computation efficiency by a factor of 10 which is essential for large
scale event-by-event simulations.Comment: 20 pages, 4 figures, 14 table
Controlled remote state preparation via partially entangled quantum channel
We propose two controlled remote state preparation protocols via partially
entangled channels. One prepares a single-qubit state and the other prepares a
two-qubit state. Different from other controlled remote state preparation
schemes which also utilize partially entangled channels, neither auxiliary
qubits nor two-qubit unitary transformations are required in our schemes and
the success probabilities are independent of the coefficients of the quantum
channel. The success probabilities are 50% and 25% for arbitrary single-qubit
states and two-qubit states, respectively. We also show that the success
probabilities can reach 100% for restricted classes of states
Video Primal Sketch: A Unified Middle-Level Representation for Video
This paper presents a middle-level video representation named Video Primal
Sketch (VPS), which integrates two regimes of models: i) sparse coding model
using static or moving primitives to explicitly represent moving corners,
lines, feature points, etc., ii) FRAME /MRF model reproducing feature
statistics extracted from input video to implicitly represent textured motion,
such as water and fire. The feature statistics include histograms of
spatio-temporal filters and velocity distributions. This paper makes three
contributions to the literature: i) Learning a dictionary of video primitives
using parametric generative models; ii) Proposing the Spatio-Temporal FRAME
(ST-FRAME) and Motion-Appearance FRAME (MA-FRAME) models for modeling and
synthesizing textured motion; and iii) Developing a parsimonious hybrid model
for generic video representation. Given an input video, VPS selects the proper
models automatically for different motion patterns and is compatible with
high-level action representations. In the experiments, we synthesize a number
of textured motion; reconstruct real videos using the VPS; report a series of
human perception experiments to verify the quality of reconstructed videos;
demonstrate how the VPS changes over the scale transition in videos; and
present the close connection between VPS and high-level action models
Fluctuating flow angles and anisotropic flow measurements
Event-by-event fluctuations in the initial density distributions of the
fireballs created in relativistic heavy-ion collisions lead to event-by-event
fluctuations of the final anisotropic flow angles, and density inhomogeneities
in the initial state cause these flow angles to vary with the transverse
momentum of the emitted particles. It is shown that these effects lead to
characteristically different transverse momentum dependencies for anisotropic
flow coefficients extracted from different experimental methods. These
differences can be used to experimentally constrain flow angle fluctuations in
the final state of heavy-ion collisions which, in turn, are sensitive to the
initial state density fluctuations and the shear viscosity of the expanding
fireball medium.Comment: 11 pages, incl. 8 figures. v2: several figures and corresponding
discussions added, Sec. III significantly rewritten. No qualitative change in
conclusions but more precise and detailed discussion of the results. To
appear in Physical Review
Realization of high-capacity hydrogen storage using carbon atomic chains: the role of terminations
The capacity of carbon atomic chains with different terminations for hydrogen
storage is studied using first-principles density functional theory
calculations. Unlike the physisorption of H2 on the H-terminated chain, we show
that two Li (Na) atoms each capping one end of the carbon chain can hold ten H2
molecules with optimal binding energies for room temperature storage. The
hybridization of the Li 2p states with the H2 sigma orbitals contributes to the
H2 adsorption. However, the binding mechanism of the H2 molecules on Na arises
only from the polarization interaction between the charged Na atom and the H2.
Moreover, additional H2 molecules can be bound to the carbon atoms at the chain
ends due to the charge transfer between Li 2s2p (Na 3s) and C 2p states.
Importantly, dimerization of these isolated metal-capped chains does not affect
the hydrogen binding energy significantly. In addition, a single chain can be
stabilized effectively by termination on the C60 clusters. With a hydrogen
uptake of > 10 wt % on Li-coated C60-Cn-C60 (n = 5, 8), the Li12C60-Cn-Li12C60
complex, without reducing the number of adsorbed H2 molecules per Li, can serve
as better building blocks of polymers than the (Li12C60)2 dimer. These findings
suggest a new route to design cluster-assembled storage materials based on
terminated sp carbon chains.Comment: 19 pages, 8 figure
Synchrotron X-ray tomography investigation of 3D morphology of intermetallic phases and pores and their effect on the mechanical properties of cast Al-Cu alloys
The influence of Fe content on the three-dimensional (3D) morphology of
Fe-rich intermetallic phases (Fe phases), Al2Cu, and pores and mechanical
properties of cast Al-5.0Cu-0.6Mn alloys with 0.5 and 1.0 wt. % Fe are
characterized using synchrotron X-ray tomography and a tensile test. The
results show that both Fe phases and Al2Cu exhibit a complex 3D network
structure, and the pores are irregular with complex interconnected and
near-globular shape. As the Fe content increases from 0.5 % to 1.0 %, the
volume fraction and equivalent diameter of Fe phases decrease, whereas both
their interconnectivities decrease. Skeletonization analysis shows that the
Chinese-script-shaped Fe phase is compacted than the plate-like Fe phases. The
equivalent diameter and sphericity of pores vary with Fe content, and their
relationships follow exponential functions, Y = 7.14*X-1.29 and Y =
7.06*X-1.20, respectively. The addition of Fe results in a decrease in the
ultimate tensile strength and elongation from 223.7 MPa to 199.8 MPa and from
5.51 % to 3.64 %, respectively, owing to increasing volume fraction of
sharp-edged Fe phases and pores, resulting in stress concentration during
tensile test.Comment: 27 pages, 13 figure
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