Substructuring Method in Structural Health Monitoring

In sensitivity-based finite element model updating, the eigensolutions and eigensensitivities are calculated repeatedly, which is a time-consuming process for large-scale structures. In this chapter, a forward substructuring method and an inverse substructuring method are proposed to fulfill the model updating of large-scale structures. In the forward substructuring method, the analytical FE model of the global structure is divided into several independent substructures. The eigensolutions of each independent substructure are used to recover the eigensolutions and eigensensitivities of the global structure. Consequently, only some specific substructures are reanalyzed in model updating and assembled with other untouched substructures to recover the eigensolutions and eigensensitivities of the global structure. In the inverse substructuring method, the experimental modal data of the global structure are disassembled into substructural flexibility. Afterwards, each substructure is treated as an independent structure to reproduce its flexibility through a model-updating process. Employing the substructuring method, the model updating of a substructure can be conducted by measuring the local area of the concerned substructure solely. Finally, application of the proposed methods to a laboratory tested frame structure reveals that the forward and inverse substructuring methods are effective in model updating and damage identification

Quantum transport through a double Aharonov-Bohm-interferometer in the presence of Andreev reflection

Quantum transport through a double Aharonov-Bohm-interferometer in the presence of Andreev reflection is investigated in terms of the nonequilibrium Green function method with which the reflection current is obtained. Tunable Andreev reflection probabilities depending on the interdot coupling strength and magnetic flux as well are analysised in detail. It is found that the oscillation period of the reflection probability with respect to the magnetic flux for the double interferometer depends linearly on the ratio of two parts magnetic fluxes n, i.e. 2(n+1)pi, while that of a single interferometer is 2pi. The coupling strength not only affects the height and the linewidth of Andreev reflection current peaks vs gate votage but also shifts the peak positions. It is furthermore demonstrated that the Andreev reflection current peaks can be tuned by the magnetic fluxes.Comment: 13 pages, 12 figur

Topological triply-degenerate point with double Fermi arcs

Unconventional chiral particles have recently been predicted to appear in certain three dimensional (3D) crystal structures containing three- or more-fold linear band degeneracy points (BDPs). These BDPs carry topological charges, but are distinct from the standard twofold Weyl points or fourfold Dirac points, and cannot be described in terms of an emergent relativistic field theory. Here, we report on the experimental observation of a topological threefold BDP in a 3D phononic crystal. Using direct acoustic field mapping, we demonstrate the existence of the threefold BDP in the bulk bandstructure, as well as doubled Fermi arcs of surface states consistent with a topological charge of 2. Another novel BDP, similar to a Dirac point but carrying nonzero topological charge, is connected to the threefold BDP via the doubled Fermi arcs. These findings pave the way to using these unconventional particles for exploring new emergent physical phenomena

Effects of guar gum supplementation in high-fat diets on fish growth, gut histology, intestinal oxidative stress, inflammation, and apoptosis in juvenile largemouth bass (<em>Micropterus salmoides</em>)

The present study aimed to investigate the influence of guar gum supplementation in high-fat diets on the growth performance and intestinal oxidative stress, inflammation, and apoptosis of juvenile largemouth bass. Five isonitrogenous diets were prepared: a control diet (10% crude lipid, C), a high-fat diet (17% crude lipid, HF), and three high-fat diets supplemented with 0.3% guar gum (GG0.3), 1% guar gum (GG1), and 3% guar gum (GG3). Largemouth bass (3.1±0.2 g) were randomly assigned to fifteen tanks (30 fish/tank) and fed for 8 weeks. The results demonstrated that GG0.3 significantly increased specific growth rate (SGR) and increased feed conversion ratio (FCR) compared to HF (P < 0.05). For histology, high-fat diets containing guar gum significantly increased intestinal villus length, villus width, and perimeter ratio, compared with HF (P < 0.05). Compared with Control, HF significantly decreased reduced glutathione (GSH) contents and increased malondialdehyde (MDA) contents in the intestine (P < 0.05). Additionally, HF significantly increased the expression of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and cysteine-aspartic proteases 9 (Caspase 9) in the intestine (P < 0.05). Compared to HF, GG0.3 significantly decreased MDA contents, increased GSH contents, and downregulated the expression of IL-1β, TNF-α, and Caspase 3 than diet HF in the intestine (P < 0.05). These results suggest that guar gum can alleviate the adverse effects of high-fat diets on growth and gut health in fish

A second ortho­rhom­bic polymorph of 2-(pyridin-4-ylmeth­oxy)phenol

The crystal structure of the title compound, C12H11NO2, represents a new ortho­rhom­bic polymorph II of the previously reported ortho­rhom­bic form I [Zhang et al. (2009 ▶) Acta Cryst. E65, o3160]. In polymorph II, the six-membered rings form a dihedral angle of 13.8 (1)° [71.6 (1)° in I], and O—H⋯N hydrogen bonds link mol­ecules into chains along [100], whereas the crystal structure of I features hydrogen-bonded centrosymmetric dimers

Potential Nighttime Contamination of CERES Clear-sky Field of View by Optically Thin Cirrus during the CRYSTAL-FACE Campaign

We investigate the outgoing broadband longwave (LW, 5 to approx. 200 microns) and window (WIN, 8 to approx. 12 microns) channel radiances at the top of atmosphere (TOA) under clear-sky conditions, using data acquired by the Cloud and the Earth s Radiant Energy System (CERES) and Moderate-Resolution Imaging Spectroradiometer (MODIS) instruments onboard the NASA Terra satellite platform. In this study, detailed analyses are performed on the CERES Single Scanner Footprint TOA/Surface Fluxes and Clouds product to understand the radiative effect of thin cirrus. The data are acquired over the Florida area during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) field program. Of particular interest is the anisotropy associated with the radiation field. Measured CERES broadband radiances are compared to those obtained from rigorous radiative transfer simulations. Analysis of results from this comparison indicates that the simulated radiances tend to be larger than their measured counterparts, with differences ranging from 2.1% to 8.3% for the LW band and from 1.7% to 10.6% for the WIN band. The averaged difference in radiance is approximately 4% for both the LW and WIN channels. A potential cause for the differences could be the presence of thin cirrus (i.e., optically thin ice clouds with visible optical thicknesses smaller than approximately 0.3). The detection and quantitative analysis of these thin cirrus clouds are challenging even with sophisticated multispectral instruments. While large differences in radiance between the CERES observations and the theoretical calculations are found, the corresponding difference in the anisotropic factors is very small (0.2%). Furthermore, sensitivity studies show that the influence due to a 1 K bias of the surface temperature on the errors of the LW and WIN channel radiances is of the same order as that associated with a 2% bias of the surface emissivity. The LW and WIN errors associated with a 5% bias of water vapor amount in the lower atmosphere in conjunction with a 50% bias of water vapor amount in the upper atmosphere is similar to that of a 1 K bias of the vertical temperature profile. Even with the uncertainties considered for these various factors, the simulated LW and WIN radiances are still larger than the observed radiances if thin cirrus clouds are excluded