466 research outputs found
Bulk Ultrafine-grained Magnesium Alloys by SPD Processing:Technique, Microstructures and Properties
Isotopic effects on the thermal conductivity of graphene nanoribbons: localization mechanism
Thermal conductivity of graphene nanoribbons (GNR) with length 106~{\AA} and
width 4.92~{\AA} after isotopic doping is investigated by molecular dynamics
with quantum correction. Two interesting phenomena are found: (1) isotopic
doping reduces thermal conductivity effectively in low doping region, and the
reduction slows down in high doping region; (2) thermal conductivity increases
with increasing temperature in both pure and doped GNR; but the increasing
behavior is much more slowly in the doped GNR than that in pure ones. Further
studies reveal that the physics of these two phenomena is related to the
localized phonon modes, whose number increases quickly (slowly) with increasing
isotopic doping in low (high) isotopic doping region.Comment: 6 fig
Spectral Analysis Network for Deep Representation Learning and Image Clustering
Deep representation learning is a crucial procedure in multimedia analysis
and attracts increasing attention. Most of the popular techniques rely on
convolutional neural network and require a large amount of labeled data in the
training procedure. However, it is time consuming or even impossible to obtain
the label information in some tasks due to cost limitation. Thus, it is
necessary to develop unsupervised deep representation learning techniques. This
paper proposes a new network structure for unsupervised deep representation
learning based on spectral analysis, which is a popular technique with solid
theory foundations. Compared with the existing spectral analysis methods, the
proposed network structure has at least three advantages. Firstly, it can
identify the local similarities among images in patch level and thus more
robust against occlusion. Secondly, through multiple consecutive spectral
analysis procedures, the proposed network can learn more clustering-friendly
representations and is capable to reveal the deep correlations among data
samples. Thirdly, it can elegantly integrate different spectral analysis
procedures, so that each spectral analysis procedure can have their individual
strengths in dealing with different data sample distributions. Extensive
experimental results show the effectiveness of the proposed methods on various
image clustering tasks
Nuclear transport models can reproduce charged-particle-inclusive measurements but are not strongly constrained by them
Nuclear transport models are important tools for interpretation of many heavy-ion experiments and are essential in efforts to probe the nuclear equation of state. In order to fulfill these roles, the model predictions should at least agree with observed single-particle-inclusive momentum spectra; however, this agreement has recently been questioned. The present work compares the Vlasov-Uehling-Uhlenbeck model to data for mass-symmetric systems ranging from 12C+12C to 139La+139La, and we find good agreement within experimental uncertainties at 0.4A and 0.8A GeV. For currently available data, these uncertainties are too large to permit effective nucleon-nucleon scattering cross sections in the nuclear medium to be extracted at a useful level of precision
Mpemba Effect in Crystallization of Polybutene-1
The Mpemba effect and its inverse can be understood as a result of
nonequilibrium thermodynamics. In polymers, changes of state are generally
non-equilibrium processes. However, the Mpemba effect has been rarely reported
in the crystallization of polymers. In the melt, polybutene-1 (PB-1) has the
lowest critical cooling rate in polyolefins and tends to maintain its original
structure and properties with thermal history. A nascent PB-1 sample was
prepared by using metallocene catalysis at low temperature, and the
crystallization behavior and crystalline structure of the PB-1 were
characterized by DSC and WAXS. Experimentally, a clear Mpemba effect is
observed not only in the crystallization of the nascent PB-1 melt in form II
but also in form I obtained from the nascent PB-1 at low melting temperature.
It is proposed that this is due to the differences in the chain conformational
entropy in the lattice which influence conformational relaxation times. The
entropy and the relaxation time can be predicted using the Adam-Gibbs
equations, whereas non-equilibrium thermodynamics is required to describe the
crystallization with the Mpemba effect
- …