4,819 research outputs found
Algorithms For Extracting Timeliness Graphs
We consider asynchronous message-passing systems in which some links are
timely and processes may crash. Each run defines a timeliness graph among
correct processes: (p; q) is an edge of the timeliness graph if the link from p
to q is timely (that is, there is bound on communication delays from p to q).
The main goal of this paper is to approximate this timeliness graph by graphs
having some properties (such as being trees, rings, ...). Given a family S of
graphs, for runs such that the timeliness graph contains at least one graph in
S then using an extraction algorithm, each correct process has to converge to
the same graph in S that is, in a precise sense, an approximation of the
timeliness graph of the run. For example, if the timeliness graph contains a
ring, then using an extraction algorithm, all correct processes eventually
converge to the same ring and in this ring all nodes will be correct processes
and all links will be timely. We first present a general extraction algorithm
and then a more specific extraction algorithm that is communication efficient
(i.e., eventually all the messages of the extraction algorithm use only links
of the extracted graph)
Asymptotic iteration method for eigenvalue problems
An asymptotic interation method for solving second-order homogeneous linear
differential equations of the form y'' = lambda(x) y' + s(x) y is introduced,
where lambda(x) \neq 0 and s(x) are C-infinity functions. Applications to
Schroedinger type problems, including some with highly singular potentials, are
presented.Comment: 14 page
Simultaneous Optical Model Analyses of Elastic Scattering, Breakup, and Fusion Cross Section Data for the He + Bi System at Near-Coulomb-Barrier Energies
Based on an approach recently proposed by us, simultaneous
-analyses are performed for elastic scattering, direct reaction (DR)
and fusion cross sections data for the He+Bi system at
near-Coulomb-barrier energies to determine the parameters of the polarization
potential consisting of DR and fusion parts. We show that the data are well
reproduced by the resultant potential, which also satisfies the proper
dispersion relation. A discussion is given of the nature of the threshold
anomaly seen in the potential
The REVERE project:Experiments with the application of probabilistic NLP to systems engineering
Despite natural language’s well-documented shortcomings as a medium for precise technical description, its use in software-intensive systems engineering remains inescapable. This poses many problems for engineers who must derive problem understanding and synthesise precise solution descriptions from free text. This is true both for the largely unstructured textual descriptions from which system requirements are derived, and for more formal documents, such as standards, which impose requirements on system development processes. This paper describes experiments that we have carried out in the REVERE1 project to investigate the use of probabilistic natural language processing techniques to provide systems engineering support
A basis for variational calculations in d dimensions
In this paper we derive expressions for matrix elements (\phi_i,H\phi_j) for
the Hamiltonian H=-\Delta+\sum_q a(q)r^q in d > 1 dimensions.
The basis functions in each angular momentum subspace are of the form
phi_i(r)=r^{i+1+(t-d)/2}e^{-r^p/2}, i >= 0, p > 0, t > 0. The matrix elements
are given in terms of the Gamma function for all d. The significance of the
parameters t and p and scale s are discussed. Applications to a variety of
potentials are presented, including potentials with singular repulsive terms of
the form b/r^a, a,b > 0, perturbed Coulomb potentials -D/r + B r + Ar^2, and
potentials with weak repulsive terms, such as -g r^2 + r^4, g > 0.Comment: 22 page
Kink far below the Fermi level reveals new electron-magnon scattering channel in Fe
Many properties of real materials can be modeled using ab initio methods
within a single-particle picture. However, for an accurate theoretical
treatment of excited states, it is necessary to describe electron-electron
correlations including interactions with bosons: phonons, plasmons, or magnons.
In this work, by comparing spin- and momentum-resolved photoemission
spectroscopy measurements to many-body calculations carried out with a newly
developed first-principles method, we show that a kink in the electronic band
dispersion of a ferromagnetic material can occur at much deeper binding
energies than expected (E_b=1.5 eV). We demonstrate that the observed spectral
signature reflects the formation of a many-body state that includes a photohole
bound to a coherent superposition of renormalized spin-flip excitations. The
existence of such a many-body state sheds new light on the physics of the
electron-magnon interaction which is essential in fields such as spintronics
and Fe-based superconductivity.Comment: 6 pages, 2 figure
On a theorem of Kang and Liu on factorised groups
[EN] Kang and Liu ['On supersolvability of factorized finite groups', Bull. Math. Sci. 3 (2013), 205-210] investigate the structure of finite groups that are products of two supersoluble groups. The goal of this note is to give a correct proof of their main theorem.The first author was supported by the grant MTM2014-54707-C3-1-P from the Ministerio de Economia y Competitividad, Spain, and FEDER, European Union, and a project of Natural Science Foundation of Guangdong Province (No. 2015A030313791).Ballester-Bolinches, A.; Pedraza Aguilera, MC. (2018). On a theorem of Kang and Liu on factorised groups. Bulletin of the Australian Mathematical Society. 97(1):54-56. https://doi.org/10.1017/S0004972717000363S5456971Ezquerro, L. M., & Soler-EscrivĂ , X. (2003). On MutuallyM-Permutable Products of Finite Groups. Communications in Algebra, 31(4), 1949-1960. doi:10.1081/agb-120018515Kang, P., & Liu, Q. (2013). On supersolvability of fatorized finite groups. Bulletin of Mathematical Sciences, 3(2), 205-210. doi:10.1007/s13373-013-0032-4Ballester-Bolinches, A., Esteban-Romero, R., & Asaad, M. (2010). Products of Finite Groups. de Gruyter Expositions in Mathematics. doi:10.1515/9783110220612Ballester-Bolinches, A., Cossey, J., & Pedraza-Aguilera, M. C. (2001). ON PRODUCTS OF FINITE SUPERSOLUBLE GROUPS. Communications in Algebra, 29(7), 3145-3152. doi:10.1081/agb-501
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