SummaryVision-based monitoring receives increased attention for measuring displacements of civil infrastructure such as towers and bridges. Currently, most field applications rely on artificial targets for video processing convenience, leading to high installation effort and focus on only single-point displacement measurement, for example, at mid-span of a bridge. This study proposes a low-cost and non-contact vision-based system for multipoint displacement measurement based on a consumer-grade camera for video acquisition and a custom-developed package for video processing. The system has been validated on a cablestayed footbridge for deck deformation and cable vibration measurement under pedestrian loading. The analysis results indicate that the system provides valuable information about bridge deformation of the order of a few centimetres induced, in this application, by pedestrian passing. The measured data enable accurate estimation of modal frequencies of either the bridge deck or the bridge cables and could be used to investigate variations of modal frequencies under varying pedestrian loads. KEYWORDSbridge displacement, cable vibration, cable-stayed bridge, pedestrian loads, vision-based system | INTRODUCTIONStructural health monitoring is aimed at providing valuable information about structural performance and characterisation of structural defects to the asset owners, especially for those civil infrastructures beyond the design life. Vibrationbased modal tests are a common way for structural condition and serviceability assessment, providing a direct view about the structural stiffness, mass properties, and their distributions. [1] As well as for validating designs of civil structures, modal parameters extracted from vibration data obtained in short-term or long-term measurements are widely believed to have potential for identifying changes in structural condition or "damage." [2] The sensitivity of these parameters to damage depends on the nature of the damage, for example, local deterioration of material, for example, due to corrosion, may not be detectable against background effects of environmental variability, whereas boundary conditions are known to have a relatively strong effect, for example, fixity of bridge supports.[3]This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

How far Jupiter's cloud-level zonal winds penetrate into its interior, a question related to the origin of the winds, has long been a major puzzle about Jupiter. There exist two different views: the shallow scenario in which the cloud-level winds are confined within the thin weather layer at cloud top and the deep scenario in which the cloud-level winds manifest thermal convection in the deep interior. We interpret, using two different models corresponding to the two scenarios, the high-precision measurements of Jupiter's equatorially antisymmetric gravitational field by the Juno spacecraft. We demonstrate, based on the thermal-gravitational wind equation, that both the shallow and deep cloud-level winds models are capable of explaining the measured odd gravitational coefficients within the measured uncertainties, reflecting the nonunique nature of the gravity inverse problem. We conclude that the high-precision Juno gravity measurements cannot provide an answer to the long-standing question about the origin of Jupiter's cloud-level zonal winds.

TITLEThermal-gravitational wind equation for the wind-induced gravitational signature of giant gaseous planets: mathematical derivation, numerical method, and illustrative solutions AUTHORS Schubert, G; Zhang, Keke; Kong, Dali; et al. ABSTRACTThe standard thermal wind equation (TWE) relating the vertical shear of a flow to the horizontal density gradient in an atmosphere has been used to calculate the external gravitational signature produced by zonal winds in the interiors of giant gaseous planets. We show, however, that in this application the TWE needs to be generalized to account for an associated gravitational perturbation. We refer to the generalized equation as the thermalgravitational wind equation (TGWE). The generalized equation represents a two-dimensional kernel integral equation with the Green's function in its integrand and is hence much more difficult to solve than the standard TWE. We develop an extended spectral method for solving the TGWE in spherical geometry. We then apply the method to a generic gaseous Jupiter-like object with idealized zonal winds. We demonstrate that solutions of the TGWE are substantially different from those of the standard TWE. We conclude that the TGWE must be used to estimate the gravitational signature of zonal winds in giant gaseous planets. Key words: planetary systemsplanets and satellites: gaseous planetsplanets and satellites: interiors q without accounting for the associated gravitational perturbation. The observed zonal gravitational coefficients J n in Equation (1) would compri-sethe two parts J J J , n n n static dyn = +Dwhere J n static is caused by the effect of rotational distortion while J n dyn

Many gaseous planets and stars are rapidly rotating and can be approximately described by a polytropic equation of state with index unity. We present the first exact analytic solution, under the assumption of the oblate spheroidal shape, for an arbitrarily rotating gaseous polytrope with index unity in hydrostatic equilibrium, giving rise to its internal structure and gravitational field. The new exact solution is derived by constructing the non-spherical Green's function in terms of the oblate spheroidal wavefunction. We then apply the exact solution to a generic object whose parameter values are guided by the observations of the rapidly rotating star α Eridani with its eccentricity E α = 0.7454, the most oblate star known. The internal structure and gravitational field of the object are computed from its assumed rotation rate and size. We also compare the exact solution to the three-dimensional numerical solution based on a finite-element method taking full account of rotation-induced shape change and find excellent agreement between the exact solution and the finite-element solution with about 0.001 per cent discrepancy.Key words: planets and satellites: gaseous planets -planets and satellites: interiors -stars: interiors. I N T RO D U C T I O NA fully compressible polytropic gas with index unity obeying the polytropic equation of state (EOS)where p * is the pressure, K is a constant and ρ * is the density, has been widely employed to study the physical properties of gaseous planets, exoplanets and stars (see for example, Chandrasekhar 1933; Roberts 1962;Hubbard 1973;Stevenson 1982;Dintrans & Ouyed 2001;Horedt 2004;Kong et al. 2014). In this paper, the superscript * is adopted to represent a dimensional variable and its corresponding dimensionless variable is denoted without the superscript. Many astrophysical gaseous bodies are rapidly rotating, causing significant departure from sphericity: the eccentricity at the one-bar surface is E S = 0.4316 for Saturn (Seidelmann et al. 2007) while the star α Eridani is marked by a much larger departure from sphericity with the approximate eccentricity E α = 0.7454 (Carciofi et al. 2008). The rotational effect on the shape and physical structure of a slowly rotating polytrope was first studied by Chandrasekhar (1933) using a perturbation analysis. For an isolated, non-rotating and selfgravitating body, the density distribution ρ * within the interior of E-mail: kzhang@ex.ac.uk the polytrope is spherically symmetric and described by the LaneEmden equation, a second-order ordinary differential equation that can be readily solved to determine the one-dimensional density distribution. For a polytropic body that is slowly rotating with small angular velocity such that its departure from sphericity is slight, Chandrasekhar (1933) introduced a small parameter ∼ 2 and was able to solve for the density distribution ρ * of the slowly rotating polytrope via a perturbation method in terms of the small expansion parameter . Without developing a small parameter expansion, R...

Advanced functional composite of ZnO nanoparticles embedded in N-doped nanoporous carbons has been synthesized by a simple one-step carbonization of zeolitic imidazolate framework-8 under a water stream atmosphere. A variety of characterization techniques show that the introduction of water steam during the carbonization process holds the key to obtain the fine and homogeneously dispersed ZnO nanoparticles within the functionalised nanoporous carbon matrix. Possessing a higher specific surface area, a larger pore volume and abundant oxygen-containing hydrophilic functional groups, the resulting composite exhibits a stronger interaction with CO 2 and is more efficient to promote the photocatalytic degradation-adsorption of methylene blue under visible light than the composite obtained without steam treatment. As a result, the steam derived composite exhibits increased CO 2 uptake capacity and excellent methylene blue molecules removal from water. Using different metal-organic frameworks as precursors, this new, simple and green method can be further expanded to generate various new homogeneous dispersed functional metal oxide/porous carbon composites with high efficient in relevant applications.

[1] To first approximation the interiors of many planetary bodies consist of a core and mantle with significantly different densities. The shapes of the surface and interface between the core and the mantle are basic properties reflecting planetary structure and rotation. In addition, interface shape is an important parameter controlling the dynamics of a fluid core. We present a theory for the rotational distortion of a two-layer model of a planet (two-layer Maclaurin spheroid) that determines the shapes of both the interface and the outer free surface without treating departure from sphericity as a small perturbation. Since the interface and the outer free surface, in general, have different shapes, two different spheroidal coordinates are required in the mathematical analysis, and the transformation between them is at the heart of the complexity of the theory. Furthermore, two different cases have to be considered. In the first case, the core is sufficiently large, or the rate of rotation is sufficiently small, that the foci of the outer free surface are located within the core. In the second case, the core is sufficiently small, or the rate of rotation is sufficiently fast, that the foci of the free surface are located within the outer layer. In comparison to the classical Maclaurin solution which is explicitly analytical, the relevant multiple integrals for the equilibrium solution of a two-layer Maclaurin spheroid have to be evaluated numerically. The shape of a two-layer rotating planet is characterized by three dimensionless parameters that are explored systematically in the present study.

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