In trees, reaction wood, different from the main wood tissue, is formed in branches in order to carry high bending moments and actuate the branch towards upward growth. In conifer species, such as pine and spruce, com...
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Graphite is one of the most widely used negative electrode materials for lithium ion batteries (LIBs). However, because of the rapid growth of demands pursuing higher energy density and charging rates, comprehensive i...
This study aims to present simple conversion expressions of strains–stresses and the energy density for beams and plates subjected to high-frequency random forces using the radiative energy transfer method (RETM). Eu...
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This study aims to present simple conversion expressions of strains–stresses and the energy density for beams and plates subjected to high-frequency random forces using the radiative energy transfer method (RETM). Euler–Bernoulli beam theory and Kirchhoff plate theory are introduced to describe the deflections of beam and plate. The conversion expressions of strains–stresses and energy density for a single propagation wave are quickly established by dispersion relations. For multi-cylindrical wave fields, the strains–stresses are superimposed by the wave fields generated by the actual source in the domain and the wave fields reflected by the fictitious sources at boundaries according to Huygens’ superposition principle. The conversion expressions of strains–stresses and energy density in the energy finite element method (EFEM), which supposes that the superposition of plane waves forms the wave field, are also derived. Numerical examples indicate that in damping-frequency space, the conversion expressions obtained by RETM have a wider application region than those obtained by EFEM and can be applied to a low-frequency band than the corresponding energy algorithm itself.
Spectral-selectively solar harvest is achieved in designated frequency regions for photothermal energy generation. In this study, we have designed and synthesized porphyrin-based hybrids that typically exhibit two abs...
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We aimed to classify and quantify the abundance of litter in cities, which is a major source of marine plastic pollution, using citizen science combined with deep learning-based image processing. The project to collec...
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Equipping buildings with energy harvesting windows is a practical way to reduce greenhouse gas (GhG) emission. Utilizing semi-transparent organic photovoltaics (ST-OPVs) for this application requires the device to be ...
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Machine learning of microstructure–property relationships from data is an emerging approach in computational materialsscience. Most existing machine learning efforts focus on the development of task-specific models ...
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Many works in elasticity have exploited the concept of gradient-index (GRIN) lenses, borrowed from optics, for wave focusing and control. These effects are particularly attractive for cloaking, absorption, or energy-h...
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Many works in elasticity have exploited the concept of gradient-index (GRIN) lenses, borrowed from optics, for wave focusing and control. These effects are particularly attractive for cloaking, absorption, or energy-harvesting applications. Despite their potential, current lens designs suffer from limitations, mainly related to the difficulty of imaging pointlike sources. Here, we exploit an alternative GRIN lens design that enables a one-to-one correspondence between input and output phase and allows the focal length to be determined using the well-known thin-lens equation, effectively establishing an elastic equivalent of the convex lens in optics. This is demonstrated analytically, obtaining a bijective relation between the location of a pointlike source and its image. The results are also confirmed numerically and experimentally in an aluminum plate, in which the lens is realized by introducing rows of circular cavities of variable diameter. Moreover, a proof-of-concept experiment demonstrates the possibility of imaging sources of flexural waves at the centimeter scale with subwavelength resolution. This research can extend applications of elastic GRIN lenses to new fields such as imaging and nondestructive testing, in which the locations of defects can be identified by focusing the scattered field. Multiple sources can be imaged simultaneously, and the combined effects of multiple lenses can also be used to design more complex systems, opening new possibilities for the technological exploitation of elastic wave manipulation.
An atmospheric pressure plasma jet (APPJ) is used to process electrochemically deposited NiFe on carbon paper (NiFe/CP). The reactive oxygen and nitrogen species (RONs) of the APPJ modify the surface properties, chemi...
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