4,866 research outputs found
BIM-based mixed-reality application for bridge inspection and maintenance
Purpose – The purpose of this study is to develop a BIM-based mixed reality (MR) application to enhance and facilitate the process of managing bridge inspection and maintenance works remotely from office. It aims to address the ineffective decision-making process on maintenance tasks from the conventional method which relies on documents and 2D drawings on visual inspection. This study targets two key issues: creating a BIM-based model for bridge inspection and maintenance; and developing this model in a MR platform based on Microsoft Hololens.
Design/methodology/approach – Literature review is conducted to determine the limitation of MR technology in the construction industry and identify the gaps of integration of BIM and MR for bridge inspection works. A new framework for a greater adoption of integrated BIM and Hololens is proposed. It consists of a bridge information model for inspection and a newly-developed Hololens application named “HoloBridge”. This application contains the functional modules that allow users to check and update the progress of inspection and maintenance. The application has been implemented for an existing bridge in South Korea as the case study.
Findings – The results from pilot implementation show that the inspection information management can be enhanced because the inspection database can be systematically captured, stored and managed through BIM-based models. The inspection information in MR environment has been improved in interpretation, visualization and visual interpretation of 3D models because of intuitively interactive in real-time simulation.
Originality/value – The proposed framework through “HoloBridge” application explores the potential of integrating BIM and MR technology by using Hololens. It provides new possibilities for remote inspection of bridge conditions
X-ray absorption branching ratio in actinides: LDA+DMFT approach
To investigate the x-ray absorption (XAS) branching ratio from the core 4d to
valence 5f states, we set up a theoretical framework by using a combination of
density functional theory in the local density approximation and Dynamical Mean
Field Theory (LDA+DMFT), and apply it to several actinides. The results of the
LDA+DMFT reduces to the band limit for itinerant systems and to the atomic
limit for localized f electrons, meaning a spectrum of 5f itinerancy can be
investigated. Our results provides a consistent and unified view of the XAS
branching ratio for all elemental actinides, and is in good overall agreement
with experiments.Comment: 6 pages, 4 figure
Polarimetric clutter modeling: Theory and application
The two-layer anisotropic random medium model is used to investigate fully polarimetric scattering properties of earth terrain media. The polarization covariance matrices for the untilted and tilted uniaxial random medium are evaluated using the strong fluctuation theory and distorted Born approximation. In order to account for the azimuthal randomness in the growth direction of leaves in tree and grass fields, an averaging scheme over the azimuthal direction is also applied. It is found that characteristics of terrain clutter can be identified through the analysis of each element of the covariance matrix. Theoretical results are illustrated by the comparison with experimental data provided by MIT Lincoln Laboratory for tree and grass fields
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AKARI observation of early-type galaxies in Abell 2218
We describe the AKARI InfraRed Camera (IRC) imaging observation of early-type galaxies (ETGs) in A2218 at z ≅ 0.175. With the imaging capability at 11 and 15 μm, we investigate mid-infrared (MIR) properties of ETGs in the cluster environment. Among our flux-limited sample of 22 optical red sequence ETGs, we find that more than 50% have MIR-excess emission, and the most likely cause of the MIR excess is the circumstellar dust emission from asymptotic giant branch (AGB) stars. The MIR-excess galaxies reveal a wide spread in N3-S11 (3 and 11 μm) colors, indicative of a significant spread (2–11 Gyr) in the mean ages of stellar populations. They are also preferentially located in the outer region, suggesting the environment dependence of MIR-excess ETGs over an area out to a half virial radius
Thermodynamic properties of extremely diluted symmetric Q-Ising neural networks
Using the replica-symmetric mean-field theory approach the thermodynamic and
retrieval properties of extremely diluted {\it symmetric} -Ising neural
networks are studied. In particular, capacity-gain parameter and
capacity-temperature phase diagrams are derived for and .
The zero-temperature results are compared with those obtained from a study of
the dynamics of the model. Furthermore, the de Almeida-Thouless line is
determined. Where appropriate, the difference with other -Ising
architectures is outlined.Comment: 16 pages Latex including 6 eps-figures. Corrections, also in most of
the figures have been mad
Superconductivity Near Ferromagnetism in MgCNi3
An unusual quasi-two-dimensional heavy band mass van Hove singularity (vHs)
lies very near the Fermi energy in MgCNi3, recently reported to superconduct at
8.5 K. This compound is strongly exchange enhanced and is unstable to
ferromagnetism upon hole doping with 12% Mg --> Na or Li. The 1/4-depleted fcc
(frustrated) Ni sublattice and lack of Fermi surface nesting argues against
competing antiferromagnetic and charge density wave instabilities. We identify
an essentially infinite mass along the M-Gamma line, leading to
quasi-two-dimensionality of this vHs may promote unconventional p-wave pairing
that could coexist with superconductivity.Comment: 4 two-column pages, 4 figure
Non-Drude Optical Conductivity of (III,Mn)V Ferromagnetic Semiconductors
We present a numerical model study of the zero-temperature infrared optical
properties of (III,Mn)V diluted magnetic semiconductors. Our calculations
demonstrate the importance of treating disorder and interaction effects
simultaneously in modelling these materials. We find that the conductivity has
no clear Drude peak, that it has a broadened inter-band peak near 220 meV, and
that oscillator weight is shifted to higher frequencies by stronger disorder.
These results are in good qualitative agreement with recent thin film
absorption measurements. We use our numerical findings to discuss the use of
f-sum rules evaluated by integrating optical absorption data for accurate
carrier-density estimates.Comment: 7 pages, 3 figure
Core pinning by intragranular nanoprecipitates in polycrystalline MgCNi_3
The nanostructure and magnetic properties of polycrystalline MgCNi_3 were
studied by x-ray diffraction, electron microscopy, and vibrating sample
magnetometry. While the bulk flux-pinning force curve F_p(H) indicates the
expected grain-boundary pinning mechanism just below T_c = 7.2 K, a systematic
change to pinning by a nanometer-scale distribution of core pinning sites is
indicated by a shift of F_p(H) with decreasing temperature. The lack of scaling
of F_p(H) suggests the presence of 10 to 20% of nonsuperconducting regions
inside the grains, which are smaller than the diameter of fluxon cores 2xi at
high temperature and become effective with decreasing temperature when xi(T)
approaches the nanostructural scale. Transmission electron microscopy revealed
cubic and graphite nanoprecipitates with 2 to 5 nm size, consistent with the
above hypothesis since xi(0) = 6 nm. High critical current densities, more than
10^6 A/cm^2 at 1 T and 4.2 K, were obtained for grain colonies separated by
carbon. Dirty-limit behavior seen in previous studies may be tied to electron
scattering by the precipitates, indicating the possibility that strong core
pinning might be combined with a technologically useful upper critical field if
versions of MgCNi_3 with higher T_c can be found.Comment: 5 pages, 6 figures, submitted to PR
A characteristic lengthscale causes anomalous size effects and boundary programmability in mechanical metamaterials
The architecture of mechanical metamaterialsis designed to harness geometry,
non-linearity and topology to obtain advanced functionalities such as shape
morphing, programmability and one-way propagation. While a purely geometric
framework successfully captures the physics of small systems under idealized
conditions, large systems or heterogeneous driving conditions remain
essentially unexplored. Here we uncover strong anomalies in the mechanics of a
broad class of metamaterials, such as auxetics, shape-changers or topological
insulators: a non-monotonic variation of their stiffness with system size, and
the ability of textured boundaries to completely alter their properties. These
striking features stem from the competition between rotation-based
deformations---relevant for small systems---and ordinary elasticity, and are
controlled by a characteristic length scale which is entirely tunable by the
architectural details. Our study provides new vistas for designing, controlling
and programming the mechanics of metamaterials in the thermodynamic limit.Comment: Main text has 4 pages, 4 figures + Methods and Supplementary
Informatio
Superconductivity near the vibrational mode instability in MgCNi3
To understand the role of electron-phonon interaction in superconducting
MgCNi we have performed density functional based linear response
calculations of its lattice dynamical properties. A large coupling constant = 1.51 is predicted and contributing phonons are identified as
displacements of Ni atoms towards octahedral interstitials of the perovskite
lattice. Instabilities found for some vibrational modes emphasize the role of
anharmonic effects in resolving experimental controversies.Comment: 4 pages, 4 eps figures, replaces the older versio
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