Real-time acoustic energy harvesting in tunable frequencies via metasurface fabricated by additive manufacturing

This paper demonstrates an acoustic metasurface for energy harvesting at tunable frequencies. The support structure of the metasurface was fabricated by additive manufacturing. The acoustic absorption coefficient and sound transmission loss of the metasurface can be tuned by optimization of various structural parameters, such as mass, mass size, prestress, membrane thickness, and array arrangement. The impedance tube was used to test the sound absorption ability of the fabricated metasurface, and the numerical simulation agreed well with the experiment, with a minimum acoustic absorption coefficient at ∼400 Hz. A PZT structure was designed and integrated into the acoustic metasurface, transforming the absorbed acoustic energy into electrical energy. Real-time acoustic energy harvesting was realized, and the peak voltage of 1.469 V was successfully monitored under the excitation of 410 Hz. For future applications, the energy harvesting efficiency can be further increased by improving the isolation components of the whole system.Published versionThis work was supported by the National Natural Science Foundation of China (NNSFC) (No. 51508031) and the Natural Science Foundation of Shaanxi Province (No. 2020JM-253)

Influence of plastic aggregate geometry on strength properties of cement-stabilized macadam

Abstract In order to improve the toughness and flexibility of cement-stabilized macadam and inhibit crack formation and propagation, the influence of plastic aggregate geometry on the strength properties of cement-stabilized macadam is studied. The surface roughness of plastic aggregate was designed into Ra 12.5 and Ra 25. When the content of plastic coarse aggregate was gradually increased from 4 to 8%, 12%, 16%, 20%, and 24%, the compressive strength, splitting strength, and the tensile-compression ratio of the cement-stabilized macadam made of aggregate with rough surface texture were found higher than those of aggregate with smooth surface texture. The rough cylindrical, spherical, spindle, and dumbbell-shaped plastic coarse aggregates were designed and prepared for testing. The test results showed the maximum compressive strength, splitting strength, and tensile-compression ratio of cement-stabilized macadam with the dumbbell-shaped plastic coarse aggregate. The tensile-compression ratio increased by 15.2% compared to natural aggregate cement-stabilized macadam. The results show that under the same conditions, the plastic aggregate with different geometry can improve the compressive and splitting strengths of cement-stabilized macadam and significantly improve the toughness and flexibility, with dumbbell-shaped plastic coarse aggregate having the greatest improvement, especially compared with natural aggregate cement-stabilized crushed stone. This research provides insights for improving pavement engineering quality and new ideas for utilizing waste plastics

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

non present