27,922 research outputs found
Effects of dilute substitutional solutes on carbon in -Fe: interactions and associated carbon diffusion from first-principles calculations
By means of first-principles calculations coupled with the kinetic Monte
Carlo simulations, we have systematically investigated the effects of dilute
substitutional solutes on the behaviors of carbon in -Fe. Our results
uncover that: () Without the Fe vacancy the interactions between most
solutes and carbon are repulsive due to the strain relief, whereas Mn has a
weak attractive interaction with its nearest-neighbor carbon due to the local
ferromagnetic coupling effect. () The presence of the Fe vacancy results in
attractive interactions of all the solutes with carbon. In particular, the
Mn-vacancy pair shows an exceptionally large binding energy of -0.81 eV with
carbon. () The alloying addition significantly impacts the atomic-scale
concentration distributions and chemical potential of carbon in the Fe matrix.
Among them, Mn and Cr increase the carbon chemical potential whereas Al and Si
reduce it. () Within the dilute scale of the alloying solution, the solute
concentration and temperature dependent carbon diffusivities demonstrate that
Mn has a little impact on the carbon diffusion whereas Cr (Al or Si) remarkably
retards the carbon diffusion. Our results provide certain implication for
better understanding the experimental observations related with the carbon
solubility limit, carbon micro-segregation and carbide precipitations in the
ferritic steels.Comment: 13 pages, 14 figure, Phys. Rev. B, accepte
Signless Laplacian spectral radius and Hamiltonicity of graphs with large minimum degree
In this paper, we establish a tight sufficient condition for the
Hamiltonicity of graphs with large minimum degree in terms of the signless
Laplacian spectral radius and characterize all extremal graphs. Moreover, we
prove a similar result for balanced bipartite graphs. Additionally, we
construct infinitely many graphs to show that results proved in this paper give
new strength for one to determine the Hamiltonicity of graphs.Comment: 12 pages, 1 figur
C++ Codes of Implicit Lu Algorithms for Absdll01
This report is devoted to some C++ codes implementing the implicit LU class
algorithms for solving linear determined, and undetermined systems with
variables and equations. A main program used in part of the numerical test
is given in the last section.Comment: 23 pages; report for the III international conference on ABS methods;
CAS (Chinese Accademy of Sciences), Beijing, 13-14/05/200
Dual Link Algorithm for the Weighted Sum Rate Maximization in MIMO Interference Channels
MIMO interference network optimization is important for increasingly crowded
wireless communication networks. We provide a new algorithm, named Dual Link
algorithm, for the classic problem of weighted sum-rate maximization for MIMO
multiaccess channels (MAC), broadcast channels (BC), and general MIMO
interference channels with Gaussian input and a total power constraint. For
MIMO MAC/BC, the algorithm finds optimal signals to achieve the capacity region
boundary. For interference channels with Gaussian input assumption, two of the
previous state-of-the-art algorithms are the WMMSE algorithm and the polite
water-filling (PWF) algorithm. The WMMSE algorithm is provably convergent,
while the PWF algorithm takes the advantage of the optimal transmit signal
structure and converges the fastest in most situations but is not guaranteed to
converge in all situations. It is highly desirable to design an algorithm that
has the advantages of both algorithms. The dual link algorithm is such an
algorithm. Its fast and guaranteed convergence is important to distributed
implementation and time varying channels. In addition, the technique and a
scaling invariance property used in the convergence proof may find applications
in other non-convex problems in communication networks
Hybrid Fault diagnosis capability analysis of Hypercubes under the PMC model and MM* model
System level diagnosis is an important approach for the fault diagnosis of
multiprocessor systems. In system level diagnosis, diagnosability is an
important measure of the diagnosis capability of interconnection networks. But
as a measure, diagnosability can not reflect the diagnosis capability of
multiprocessor systems to link faults which may occur in real circumstances. In
this paper, we propose the definition of -edge tolerable diagnosability to
better measure the diagnosis capability of interconnection networks under
hybrid fault circumstances. The -edge tolerable diagnosability of a
multiprocessor system is the maximum number of faulty nodes that the system
can guarantee to locate when the number of faulty edges does not exceed
,denoted by . The PMC model and MM model are the two most widely
studied diagnosis models for the system level diagnosis of multiprocessor
systems. The hypercubes are the most well-known interconnection networks. In
this paper, the -edge tolerable diagnosability of -dimensional hypercube
under the PMC model and MM is determined as follows: ,
where , .Comment: 5 pages, 1 figur
Control of the stability and soliton formation of dipole moments in a nonlinear plasmonic finite nanoparticle array
We perform numerical analysis of a finite nanoparticle array, in which the
transversal dipolar polarizations are excited by a homogenous optical field.
Considering the linearly long-range dipole-dipole interaction and the cubic
dipole nonlinearity of particle, the characteristics of stability of a finite
number nanoparticle array should be revised, compared with that of an infinite
number nanoparticle array. A critical point in the low branch of the bistable
curve is found, beyond which the low branch becomes unstable for a finite
number of nanoparticles. The influence of the external field intensities and
detuning frequencies on this critical point are investigated in detail. When
the total number of particles approaches infinity, our results become similar
to that of an infinity number particle system [cf. Ref.32]. Notably, with
appropriate external optical field, a dark dipole soliton is formed. Moreover,
when the scaled detuning is set to an appropriate value, a double monopole dark
soliton (DMDS) consisting of two particles is formed. The DMDS may have
potential applications in the subwavelength highly precise detection because of
its very small width.Comment: 9 pages, 8 figures, Photonics and Nanostructures - Fundamentals and
Applications (Elsevier), in pres
Graph Convolutional Label Noise Cleaner: Train a Plug-and-play Action Classifier for Anomaly Detection
Video anomaly detection under weak labels is formulated as a typical
multiple-instance learning problem in previous works. In this paper, we provide
a new perspective, i.e., a supervised learning task under noisy labels. In such
a viewpoint, as long as cleaning away label noise, we can directly apply fully
supervised action classifiers to weakly supervised anomaly detection, and take
maximum advantage of these well-developed classifiers. For this purpose, we
devise a graph convolutional network to correct noisy labels. Based upon
feature similarity and temporal consistency, our network propagates supervisory
signals from high-confidence snippets to low-confidence ones. In this manner,
the network is capable of providing cleaned supervision for action classifiers.
During the test phase, we only need to obtain snippet-wise predictions from the
action classifier without any extra post-processing. Extensive experiments on 3
datasets at different scales with 2 types of action classifiers demonstrate the
efficacy of our method. Remarkably, we obtain the frame-level AUC score of
82.12% on UCF-Crime.Comment: To appear in CVPR 201
Classification of entanglement and quantum phase transition in XX model
We study the relation between entanglement and quantum phase transition (QPT)
from a new perspective. Motivated by one's intuition: QPT is characterized by
the change of the ground-state structure, while entangled states belong to
different classes have different structures, we conjecture that QPT occurs as
the class of ground-state entanglement changes and prove it in XX model.
Despite the classification of multipartite entanglement is yet unresolved, we
proposed a new method to judge whether two many-body states belong to the same
entanglement class.Comment: 9 page
Dynamic Sparse Graph for Efficient Deep Learning
We propose to execute deep neural networks (DNNs) with dynamic and sparse
graph (DSG) structure for compressive memory and accelerative execution during
both training and inference. The great success of DNNs motivates the pursuing
of lightweight models for the deployment onto embedded devices. However, most
of the previous studies optimize for inference while neglect training or even
complicate it. Training is far more intractable, since (i) the neurons dominate
the memory cost rather than the weights in inference; (ii) the dynamic
activation makes previous sparse acceleration via one-off optimization on fixed
weight invalid; (iii) batch normalization (BN) is critical for maintaining
accuracy while its activation reorganization damages the sparsity. To address
these issues, DSG activates only a small amount of neurons with high
selectivity at each iteration via a dimension-reduction search (DRS) and
obtains the BN compatibility via a double-mask selection (DMS). Experiments
show significant memory saving (1.7-4.5x) and operation reduction (2.3-4.4x)
with little accuracy loss on various benchmarks.Comment: ICLR 201
Study on direct pion emission in decay
The QCD multipole expansion (QCDME) is based on the quantum field theory, so
should be more reliable. However, on another aspect, it refers to the
non-perturbative QCD , so that has a certain application range. Even though it
successfully explains the data of transition among members of the
() family, as Eichten indicates, beyond the production threshold of
mediate states it fails to meet data by several orders. In this work, by
studying a simple decay mode , where a pion may be emitted
before transiting into , we analyze the contribution of QCD multipole
expansion. Whereas as the portal is open, the dominant contribution is
an OZI allowed process where a light quark-pair is excited out from vacuum and
its contribution can be evaluated by the model. Since the direct pion
emission is a process which is OZI suppressed and violates the isospin
conservation, its contribution must be much smaller than the dominant one. By a
careful calculation, we may quantitatively estimate how small the QCDME
contribution should be and offer a quantitative interpretation for Eichten's
statement.Comment: 12 pages, 3 figure
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