4,746 research outputs found

    Effective application of service core in a reinforced concrete tall building

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    This paper provides an outline of conducting the analysis and illustrates the behavior of high-rise structures including lateral stiffness, dynamic response (period, acceleration) and human comfort criteria, in the context of the British Standard and National Building Code of Canada

    Ferroelectricity of Ice Nanotubes inside Carbon Nanotubes

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    We report that ice nanotubes with odd number of side faces inside carbon nanotubes exhibit spontaneous electric polarization along its axes direction by using molecular dynamics simulations. The mechanism of this nanoscale quasi-one-dimensional ferroelectricity is due to low dimensional confinement and the orientational order of hydrogen bonds. These ferroelectric fiber structural materials are different from traditional perovskite structural bulk materials.Comment: 4 pages and 4 figure

    Bulk-fragment and tube-like structures of AuN (N=2-26)

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    Using the relativistic all-electron density-functional calculations on the AuN (N=2-26) in the generalized gradient approximation, combined with the guided simulated annealing, we have found that the two- to three-dimensional structural transition for AuN occurs between N=13 and 15, and the AuN (16<= N <=25) prefer also the pyramid-based bulk fragment structures in addition to the Au20. More importantly, the tubelike structures are found to be the most stable for Au24 and Au26, offering another powerful structure competitor with other isomers, e.g., amorphous, bulk fragment, and gold fullerene. The mechanism to cause these unusual AuN may be attributed to the stronger s-d hybridization and the d-d interaction enhanced by the relativistic effects.Comment: 12 pages and 3 figure

    Quantum interference in deformed carbon nanotube waveguides

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    Quantum interference (QI) in two types of deformed carbon nanotubes (CNTs), i.e., axially stretched and AFM tip-deformed CNTs, has been investigated by the pi-electron only and four-orbital tight-binding (TB) method. It is found that the rapid conductance oscillation (RCO) period is very sensitive to the applied strains, and decreases in an inverse proportion to the deformation degree, which could be used as a powerful experimental tool to detect precisely the deformation degree of the deformed CNTs. Also, the sigma-pi coupling effect is found to be negligible under axially stretched strain, while it works on the transport properties of the tip-deformed CNTs.Comment: 14 pages and 5 figure

    The Age-Redshift Relationship of Old Passive Galaxies

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    We use 32 age measurements of passively evolving galaxies as a function of redshift to test and compare the standard model (Λ\LambdaCDM) with the Rh=ctR_{\rm h}=ct Universe. We show that the latter fits the data with a reduced χdof2=0.435\chi^2_{\rm dof}=0.435 for a Hubble constant H0=67.2−4.0+4.5H_{0}= 67.2_{-4.0}^{+4.5} km s−1\rm s^{-1} Mpc−1\rm Mpc^{-1}. By comparison, the optimal flat Λ\LambdaCDM model, with two free parameters (including Ωm=0.12−0.11+0.54\Omega_{\rm m}=0.12_{-0.11}^{+0.54} and H0=94.3−35.8+32.7H_{0}=94.3_{-35.8}^{+32.7} km s−1\rm s^{-1} Mpc−1\rm Mpc^{-1}), fits the age-\emph{z} data with a reduced χdof2=0.428\chi^2_{\rm dof}=0.428. Based solely on their χdof2\chi^2_{\rm dof} values, both models appear to account for the data very well, though the optimized Λ\LambdaCDM parameters are only marginally consistent with those of the concordance model (Ωm=0.27\Omega_{\rm m}=0.27 and H0=70H_{0}= 70 km s−1\rm s^{-1} Mpc−1\rm Mpc^{-1}). Fitting the age-zz data with the latter results in a reduced χdof2=0.523\chi^2_{\rm dof}=0.523. However, because of the different number of free parameters in these models, selection tools, such as the Akaike, Kullback and Bayes Information Criteria, favour Rh=ctR_{\rm h}=ct over Λ\LambdaCDM with a likelihood of ∼66.5%−80.5%\sim 66.5\%-80.5\% versus ∼19.5%−33.5%\sim 19.5\%-33.5\%. These results are suggestive, though not yet compelling, given the current limited galaxy age-zz sample. We carry out Monte Carlo simulations based on these current age measurements to estimate how large the sample would have to be in order to rule out either model at a ∼99.7%\sim 99.7\% confidence level. We find that if the real cosmology is Λ\LambdaCDM, a sample of ∼45\sim 45 galaxy ages would be sufficient to rule out Rh=ctR_{\rm h}=ct at this level of accuracy, while ∼350\sim 350 galaxy ages would be required to rule out Λ\LambdaCDM if the real Universe were instead Rh=ctR_{\rm h}=ct.Comment: 36 pages, 13 figures, 1 table; accepted for publication in The Astronomical Journal. arXiv admin note: text overlap with arXiv:1405.238
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