2,962 research outputs found
Off-critical lattice models and massive SLEs
We suggest how versions of Schramm’s SLE can be used to describe the scaling limit of
some off-critical 2D lattice models. Many open questions remain
On the optimal rank-1 approximation of matrices in the Chebyshev norm
The problem of low rank approximation is ubiquitous in science. Traditionally
this problem is solved in unitary invariant norms such as Frobenius or spectral
norm due to existence of efficient methods for building approximations.
However, recent results reveal the potential of low rank approximations in
Chebyshev norm, which naturally arises in many applications. In this paper we
tackle the problem of building optimal rank-1 approximations in the Chebyshev
norm. We investigate the properties of alternating minimization algorithm for
building the low rank approximations and demonstrate how to use it to construct
optimal rank-1 approximation. As a result we propose an algorithm that is
capable of building optimal rank-1 approximations in Chebyshev norm for small
matrices
KSNet-Approach to Knowledge Fusion from Distributed Sources
The rapidity of the decision making process is an important factor in different branches of the human life (business, healthcare, industry, military applications etc.). Since responsible persons make decisions using available knowledge, it is important for knowledge management systems to deliver necessary and timely information. Knowledge logistics is a new direction in the knowledge management addressing this. Technology of knowledge fusion, based on the synergistic use of knowledge from multiple distributed sources, is a basis for these activities. The paper presents an overview of a Knowledge Source Network configuration approach (KSNet-approach) to knowledge fusion, multi-agent architecture and research prototype of the KSNet knowledge fusion system based on this approach
Radiative corrections to hard spectator scattering in decays
We present the calculation of the next-to-leading corrections to the tree
amplitudes which appear in the description of non-leptonic B-decays in the
factorization approach. These corrections, together with radiative corrections
to the jet functions, represent the full next-to-leading contributions to the
dominant hard spectator scattering term generated by operators in the
decay amplitudes. Using obtained analytical results we estimate
branchings fractions in the physical (or BBNS) factorization scheme. We have
also found that the imaginary part generated in the hard spectator scattering
term is rather large compared to the imaginary part of the vertex contribution.Comment: text is improved and typos are corrected, accepted for publication in
JHE
Triple GEM Detectors for the Forward Tracker in STAR
Future measurements of the flavor-separated spin structure of the proton via
parity-violating W boson production at RHIC require an upgrade of the forward
tracking system of the STAR detector. This upgrade will allow the
reconstruction of the charge sign of electrons and positrons produced from
decaying W bosons. A design based on six large area triple GEM disks using GEM
foils produced by Tech-Etch Inc. has emerged as a cost-effective solution to
provide the necessary tracking precision. We report first results from a beam
test of three test detectors using Tech-Etch produced GEM foils and a laser
etched two dimensional strip readout. The detectors show good operational
stability, high efficiency and a spacial resolution of around 70 um or better,
exceeding the requirements for the forward tracking upgrade. The influence of
the angle of incidence of the particles on the spatial resolution of the
detectors has also been studied in detail.Comment: 5 pages, 8 figures, presented at the IEEE Nuclear Science Symposium
in Honolulu, HI, USA, October 27 - November 3, 200
Effect of substitutional doping and disorder on the phase stability, magnetism, and half-metallicity of Heusler alloys
Spintronics is the fast growing field that will play a key role in optimizing
power consumption, memory, and processing capabilities of nanoelectronic
devices. Heusler alloys are potential candidates for application in spintronics
due to their room temperature (RT) half-metallicity, high Curie temperature,
low lattice mismatch with most substrates, and strong control on electronic
density of states at Fermi level. In this work, we investigate the effect of
{substitutional doping and disorder} on the half-metallicity, phase stability,
and magnetism of Heusler alloys using density functional theory methods. Our
study shows that electronic and magnetic properties of half/full-Heusler alloys
can be tuned by changing electron-count through controlled variation of
chemical compositions of alloying elements. We provide a detailed discussion on
the effect of substitutional doping and disorder on the tunability of
half-metallic nature of CoMnX and NiMnX based Heusler alloys, where X
represents group 13\textendash 16 and period 3\textendash 6 elements of the
periodic table. {Based on the idea of electron count and disorder, we predicted
a possible existence of thermodynamically stable half-metallic multicomponent
bismuthides, for example, (CuNi)MnBi and
(ZnNi)MnBi, through substitution doping at Ni site by
specific Cu and Zn composition in half-Heusler NiMnBi.} We believe that the
design guide {based on electron-counts} presented for half-metals will play a
key role in electronic-structure engineering of novel Heusler alloys for
spintronic application, which will accelerate the development and synthesis of
novel materials.Comment: 19 pages (15 main text, 4 supplement) 9 Figures (6 main text, 3
supplement). arXiv admin note: substantial text overlap with arXiv:2004.0623
Aggregation kinetics at sedimentation: the impact of particles diffusion
We investigate the aggregation kinetics of sedimenting particles
theoretically and numerically, using the advection-diffusion equation.
Agglomeration, caused by both transport mechanisms (diffusion and advection),
is important for small particles, like primary ash or soot particles in
atmosphere, and large particles of equal or close size, where the advection
mechanism is weak. For small Peclet numbers, which quantify the relative
importance of diffusion and advection, we obtain the aggregation rates, as an
expansion in Peclet numbers. For large Peclet numbers we use purely ballistic
aggregation rates. Combining these results we obtain the rational approximant
for the whole range of Peclet numbers. We also compute the aggregation rates by
numerically solving the advection-diffusion equation. The results of the
numerical simulations are in excellent agreement with the analytical theory for
the studied Peclet numbers, varying by four orders of magnitude.Comment: 7 pages, 2 figures, 26 reference
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