Visual data captured at construction sites is a rich source of information for the day-to-day operation of construction projects. The development of deep-learning-based methods has demonstrated their ...capabilities in analyzing complex visual data and inferring valuable insights. Recent applications of these methods in construction have also shown promising performance in making the construction management process smarter. To understand the current research trends and to highlight future research directions, this study reviews state-of-the-art deep-learning applications on visual data analytics in the context of construction project management. This in-depth review identifies six major fields and fifty-two subfields of construction management where deep-learning-based visual data analytics have been applied. It also proposes a generalized workflow for applying deep-learning-based visual data analytics methods for solving construction management problems. In addition, the study highlights three future research directions where deep-learning-based visual data analytics can be applied on relatively less explored 3D visual data.
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•An in-depth review of 142 journal articles and conference papers related to deep learning-based visual data analytics in construction management applications.•Identification of 6 major fields and 52 subfields of construction management where deep learning-based visual data analytics were applied.•Analysis of the research field evolution since the inception of deep learning in 2012.•A generalized workflow for deploying deep learning-based visual data analytics for managing construction projects.•Knowledge gap and open challenges in each stage of the workflow.•Three future research directions where 3D visual data can be leveraged.
The electrochemical reduction of carbon monoxide is a promising approach for the renewable production of carbon-based fuels and chemicals. Copper shows activity toward multi-carbon products from CO ...reduction, with reaction selectivity favoring two-carbon products; however, efficient conversion of CO to higher carbon products such as n-propanol, a liquid fuel, has yet to be achieved. We hypothesize that copper adparticles, possessing a high density of under-coordinated atoms, could serve as preferential sites for n-propanol formation. Density functional theory calculations suggest that copper adparticles increase CO binding energy and stabilize two-carbon intermediates, facilitating coupling between adsorbed *CO and two-carbon intermediates to form three-carbon products. We form adparticle-covered catalysts in-situ by mediating catalyst growth with strong CO chemisorption. The new catalysts exhibit an n-propanol Faradaic efficiency of 23% from CO reduction at an n-propanol partial current density of 11 mA cm
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Abstract Using general relativistic magnetohydrodynamic simulations, it has been suggested that the rotational energy of a rapidly rotating black hole (BH) is preferentially extracted along the ...magnetic field lines threading the event horizon in the middle and lower latitudes. Applying this angle-dependent Poynting flux to the jet downstream, we demonstrate that the jets exhibit limb-brightened structures at various viewing angles, as observed from Mrk 501, M87, and Cyg A between 5° and 75°, and that the limb brightening is enhanced when the jet is collimated strongly. It is also found that the jet width perpendicular to the propagation direction shrinks at the projected distance of the altitude where the jet collimates from a conical shape (near the BH) to a parabolic one (in the jet). Comparing with Very Long Baseline Interferometry observations, we show that this collimation takes place within the deprojected altitude of 100 Schwarzschild radii from the BH in the case of the M87 jet.
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We examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (BHs), by applying our two-dimensional particle-in-cell simulation code. Assuming a ...stellar-mass BH, we find that the created pairs fail to screen the electric field along the magnetic field, provided that the mass accretion rate is much small compared to the Eddington limit. Magnetic islands are created by reconnection near the equator and migrate toward the event horizon, expelling magnetic flux tubes from the BH vicinity during a large fraction of time. When the magnetic islands stick to the horizon due to redshift and virtually vanish, a strong magnetic field penetrates the horizon, enabling efficient extraction of energy from the BH. During this flaring phase, a BH gap appears around the inner light surface with a strong meridional return current toward the equator within the ergosphere. If the mass accretion rate is 0.025% of the Eddington limit, the BH’s spin-down luminosity becomes 16–19 times greater than its analytical estimate during the flares, although its long-term average is only 6% of it. We demonstrate that the extracted energy flux concentrates along the magnetic field lines threading the horizon in the middle latitudes. It is implied that this meridional concentration of the Poynting flux may result in the formation of limb-brightened jets from low-accreting BH systems.
Disk formation in magnetized cloud cores is hindered by magnetic braking. Previous work has shown that for realistic levels of core magnetization, the magnetic field suppresses the formation of ...rotationally supported disks during the protostellar mass accretion phase of low-mass star formation both in the ideal MHD limit and in the presence of ambipolar diffusion for typical rates of cosmic-ray ionization. Additional effects, such as ohmic dissipation, the Hall effect, and protostellar outflow, are needed to weaken the magnetic braking and enable the formation of persistent, rotationally supported, protostellar disks. In this paper, we first demonstrate that the classic microscopic resistivity is not large enough to enable disk formation by itself. We then experiment with a set of enhanced values for the resistivity in the range {eta} = 10{sup 17}-10{sup 22} cm{sup 2} s{sup -1}. We find that a value of order 10{sup 19} cm{sup 2} s{sup -1} is needed to enable the formation of a 10{sup 2} AU scale Keplerian disk; the value depends somewhat on the degree of core magnetization. The required resistivity is a few orders of magnitude larger than the classic microscopic values. Whether it can be achieved naturally during protostellar collapse remains to be determined.
Dense, star-forming cores of molecular clouds are observed to be significantly magnetized. A realistic magnetic field of moderate strength has been shown to suppress, through catastrophic magnetic ...braking, the formation of a rotationally supported disk (RSD) during the protostellar accretion phase of low-mass star formation in the ideal MHD limit. We address, through two-dimensional (axisymmetric) simulations, the question of whether realistic levels of non-ideal effects, computed with a simplified chemical network including dust grains, can weaken the magnetic braking enough to enable an RSD to form. We find that ambipolar diffusion (AD), the dominant non-ideal MHD effect over most of the density range relevant to disk formation, does not enable disk formation, at least in two dimensions. The reason is that AD allows the magnetic flux that would be dragged into the central stellar object in the ideal MHD limit to pile up instead in a small circumstellar region, where the magnetic field strength (and thus the braking efficiency) is greatly enhanced. We also find that, on the scale of tens of AU or more, a realistic level of Ohmic dissipation does not weaken the magnetic braking enough for an RSD to form, either by itself or in combination with AD. The Hall effect, the least explored of these three non-ideal MHD effects, can spin up the material close to the central object to a significant, supersonic rotation speed, even when the core is initially non-rotating, although the spun-up material remains too sub-Keplerian to form an RSD. The problem of catastrophic magnetic braking that prevents disk formation in dense cores magnetized to realistic levels remains unresolved. Possible resolutions of this problem are discussed.
The benefits of adopting Building Information Modeling (BIM) in a construction project have been well recognized. However, it involves additional labor costs and the timeliness of task completion ...should be considered because a BIM application may not be required (and paid for) by the owner in the current stage of BIM development. At present, a project manager often faces much risk in making decisions about the cost because the BIM labor cost is supposed to be proportional to the gross (or total) floor area in practice, and the project managers can only adopt simple linear regression to estimate it. Although this method is straightforward, it tends to have a high risk of estimation error. Therefore, this research tried to develop a new methodology based on Cross Industry Standard Process for Data Mining (CRISP-DM) and proposed a hybrid approach by combining Random Forest (RF) and Simple Linear Regression (SLR) for improving the accuracy of prediction on a project's BIM labor cost in construction phase. Case studies are conducted to demonstrate and validate the prediction results using nineteen completed BIM projects from a leading construction company in Taiwan. A cost breakdown structure (CBS) was proposed to establish the training data set for machine learning. Moreover, this study proposes the use of effective floor area, instead of gross floor area, to be one of the features for training RF and SLR models. Clustering analysis is also adopted and confirmed to improve model performance. Through comparative studies, the hybrid approach of prediction methodology proposed in this study has been proved to be effective in reducing the risk of BIM labor cost prediction.
•A hybrid approach is proposed for more accurately predicting the labor cost of a BIM project.•The case studies use 19 past BIM projects from a construction company in Taiwan to validate the proposed hybrid approach.•A cost breakdown structure is proposed for collecting the total man-hour of a BIM team.
Corrosion under insulation is one of the most important issues in the petroleum industry. Ordinarily, in order to check the corrosion, inspectors remove the insulation of pipelines to measure the ...level of corrosion on each section of pipelines. This procedure may take weeks for a site which distinctly affects the financial aspect of oil and gas companies due to the pause production of its high-value products; therefore, in most cases, inspectors spot-check pipeline corrosion based on their experience. However, because the environments on sites are various, experience-based inspection may not be suitable for every site. On the other hand, even though inspectors want to access more data for better understanding of the site before the site trip, historical data sometimes are lost or scattered which leads to a hard situation for preparation of corrosion inspection. This paper utilises passive RFID sensors, which are smart sensing technologies, to collect site data and then integrate them into a Building Information Modeling (BIM) system. A uniform corrosion model is also adapted from the theories of corrosion to leverage both sensor data and BIM elements' properties. They serve as inputs to calculate the corrosion rate which is the key value of corrosion prediction. Then, the corrosion prediction results are colour-coded on a BIM model which helps inspectors intuitively understand the prediction and prepare for the site inspection. In result, the proposed research could provide a novel approach for corrosion management under insulation.
•Integrate BIM and sensors for corrosion prediction and visualisation.•A mathematical model has been developed for corrosion prediction.•A prototype has been developed to validate the efficiency of the proposed approach.
Stars form in dense cores of molecular clouds that are observed to be significantly magnetized. In the simplest case of a laminar (non-turbulent) core with the magnetic field aligned with the ...rotation axis, both analytic considerations and numerical simulations have shown that the formation of a large, 10 super(2) AU scale, rotationally supported protostellar disk is suppressed by magnetic braking in the ideal MHD limit for a realistic level of core magnetization. This theoretical difficulty in forming protostellar disks is termed the "magnetic braking catastrophe." A possible resolution to this problem, proposed by Hennebelle & Ciardi and Joos et al., is that misalignment between the magnetic field and rotation axis may weaken the magnetic braking enough to enable disk formation. We evaluate this possibility quantitatively through numerical simulations. We confirm the basic result of Joos et al. that the misalignment is indeed conducive to disk formation. In relatively weakly magnetized cores with dimensionless mass-to-flux ratio > ~ 4, it enabled the formation of rotationally supported disks that would otherwise be suppressed if the magnetic field and rotation axis are aligned. For more strongly magnetized cores, disk formation remains suppressed, however, even for the maximum tilt angle of 90degrees. If dense cores are as strongly magnetized as indicated by OH Zeeman observations (with a mean dimensionless mass-to-flux ratio ~2), it would be difficult for the misalignment alone to enable disk formation in the majority of them. We conclude that, while beneficial to disk formation, especially for the relatively weak field case, misalignment does not completely solve the problem of catastrophic magnetic braking in general.
Effects of electronic and atomic structures of V‐doped 2D layered SnS2 are studied using X‐ray spectroscopy for the development of photocatalytic/photovoltaic applications. Extended X‐ray absorption ...fine structure measurements at V K‐edge reveal the presence of VO and VS bonds which form the intercalation of tetrahedral OVS sites in the van der Waals (vdW) gap of SnS2 layers. X‐ray absorption near‐edge structure (XANES) reveals not only valence state of V dopant in SnS2 is ≈4+ but also the charge transfer (CT) from V to ligands, supported by V Lα,β resonant inelastic X‐ray scattering. These results suggest V doping produces extra interlayer covalent interactions and additional conducting channels, which increase the electronic conductivity and CT. This gives rapid transport of photo‐excited electrons and effective carrier separation in layered SnS2. Additionally, valence‐band photoemission spectra and S K‐edge XANES indicate that the density of states near/at valence‐band maximum is shifted to lower binding energy in V‐doped SnS2 compare to pristine SnS2 and exhibits band gap shrinkage. These findings support first‐principles density functional theory calculations of the interstitially tetrahedral OVS site intercalated in the vdW gap, highlighting the CT from V to ligands in V‐doped SnS2.
The interstitially tetrahedral O–V–S site in the vdW gap of V‐doped 2D SnS2 establishes the origin of the charge transfer mechanism between metal ion V4+ 3d and ligand O2‐ 2p/S2‐ 3p states and the decrease in the band gap by studying synchrotron‐based techniques and first‐principles density functional theory.
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