856,130 research outputs found
A macro-element based practical model for seismic analysis of steel-concrete composite high-rise buildings
This is the post-print version of the final paper published in Engineering Structures. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.Seismic behaviour of steel–concrete composite high-rise buildings, composed of external steel frames (SFs) and internal concrete tube (CT), with rectangular plan is investigated in this paper. A macro-element based model is established for seismic analysis of composite high-rise buildings aiming at predicting their global responses under earthquakes. By employing this macro-element based model, natural frequencies and vibration modes, storey and inter-storey drifts, overturning moments and storey shear forces of composite structures, induced by earthquakes, are able to be obtained with much less computation time and cost compared with using micro-element based analytical models. To validate its efficiency and reliability, the macro-element based model is employed to analyse a 1/20 scaled-down model of a 25-storey steel–concrete composite high-rise building subjected to simulated earthquakes with various intensities through a shaking table. Natural frequencies and storey drifts of the model structure are obtained from numerical analyses and compared with those from shaking table test results. It has been found that the calculated dynamic responses of the composite model structure subjected to minor, basic, major and super strong earthquakes agree reasonably well with those obtained from experiments, suggesting that the proposed macro-element based model is appropriate for inelastic time-history analyse for global responses of steel–concrete composite high-rise structures subjected to earthquakes with satisfactory precision and reliability. This research thus provides a practical model for elastic and inelastic deformation check of high-rise composite buildings under earthquakes.Ministry of Science and Technology of Chin
Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes
In [arXiv:0803.3259] the equations describing the parallel transport of
orthonormal frames along timelike (spacelike) geodesics in a spacetime
admitting a non-degenerate principal conformal Killing-Yano 2-form h were
solved. The construction employed is based on studying the Darboux subspaces of
the 2-form F obtained as a projection of h along the geodesic trajectory. In
this paper we demonstrate that, although slightly modified, a similar
construction is possible also in the case of null geodesics. In particular, we
explicitly construct the parallel-transported frames along null geodesics in
D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport
along principal null directions in these spacetimes. Such directions coincide
with the eigenvectors of the principal conformal Killing-Yano tensor. Finally,
we show how to obtain a parallel-transported frame along null geodesics in the
background of the 4D Plebanski-Demianski metric which admits only a conformal
generalization of the Killing-Yano tensor.Comment: 17 pages, no figure
Multicanonical Parallel Tempering
We present a novel implementation of the parallel tempering Monte Carlo
method in a multicanonical ensemble. Multicanonical weights are derived by a
self-consistent iterative process using a Boltzmann inversion of global energy
histograms. This procedure gives rise to a much broader overlap of
thermodynamic-property histograms; fewer replicas are necessary in parallel
tempering simulations, and the acceptance of trial swap moves can be made
arbitrarily high. We demonstrate the usefulness of the method in the context of
a grand-multicanonical ensemble, where we use multicanonical simulations in
energy space with the addition of an unmodified chemical potential term in
particle-number space. Several possible implementations are discussed, and the
best choice is presented in the context of the liquid-gas phase transition of
the Lennard-Jones fluid. A substantial decrease in the necessary number of
replicas can be achieved through the proposed method, thereby providing a
higher efficiency and the possibility of parallelization.Comment: 8 pages, 3 figure, accepted by J Chem Phy
Construction of scaling partitions of unity
Partitions of unity in formed by (matrix) scales of a fixed
function appear in many parts of harmonic analysis, e.g., wavelet analysis and
the analysis of Triebel-Lizorkin spaces. We give a simple characterization of
the functions and matrices yielding such a partition of unity. For invertible
expanding matrices, the characterization leads to easy ways of constructing
appropriate functions with attractive properties like high regularity and small
support. We also discuss a class of integral transforms that map functions
having the partition of unity property to functions with the same property. The
one-dimensional version of the transform allows a direct definition of a class
of nonuniform splines with properties that are parallel to those of the
classical B-splines. The results are illustrated with the construction of dual
pairs of wavelet frames
The molecular ion in a magnetic field
A detailed study of the low-lying electronic states
{}^1\Si,{}^3\Si,{}^3\Pi,{}^3\De of the molecular ion in parallel
to a magnetic field configuration (when \al-particle and proton are situated
on the same magnetic line) is carried out for G in
the Born-Oppenheimer approximation. The variational method is employed using a
physically adequate trial function. It is shown that the parallel configuration
is stable with respect to small deviations for \Si-states. The quantum
numbers of the ground state depend on the magnetic field strength. The ground
state evolves from the spin-singlet {}^1\Si state for small magnetic fields
a.u. to the spin-triplet {}^3\Si unbound state for
intermediate fields and to the spin-triplet strongly bound state for a.u. When the molecular ion exists, it is stable with
respect to a dissociation.Comment: 13 pages, 5 figures, 4 table
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