Modelling of elastic metamaterials with negative mass and modulus based on translational resonance

A numerical simulation study on elastic wave propagation of a phononic composite structure consisting of epoxy and tungsten carbide is presented for low-frequency elastic wave attenuation applications. The calculated dispersion curves of the epoxy/tungsten carbide composite show that the propagation of elastic waves is prohibited inside the periodic structure over a frequency range. To achieve a wide bandgap, the elastic composite structure can be optimized by changing its dimensions and arrangement, including size, number, and rotation angle of square inclusions. The simulation results show that increasing the number of inclusions and the filling fraction of the unit cell significantly broaden the phononic bandgap compared to other geometric tunings. Additionally, a nonmonotonic relationship between the bandwidth and filling fraction of the composite was found, and this relationship results from spacing among inclusions and inclusion sizes causing different effects on Bragg scatterings and localized resonances of elastic waves. Moreover, the calculated transmission spectra of the epoxy/tungsten carbide composite structure verify its low-frequency bandgap behavior.

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Compression of a photoinjector electron bunch in the negative-mass undulator

Physical Review Accelerators and Beams ◽

10.1103/physrevaccelbeams.20.020704 ◽

2017 ◽

Vol 20 (2) ◽

Cited By ~ 9

Author(s):

Ilya V. Bandurkin ◽

Ilya S. Kurakin ◽

Andrey V. Savilov

Keyword(s):

Electron Bunch ◽

Negative Mass

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Graded Elastic Metamaterials for Energy Harvesting

10.1007/978-3-030-69060-1 ◽

2021 ◽

Author(s):

Jacopo Maria De Ponti

Keyword(s):

Energy Harvesting ◽

Elastic Metamaterials

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Glacier Surface Mass Balance in the Suntar-Khayata Mountains, Northeastern Siberia

Water ◽

10.3390/w11091949 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1949 ◽

Cited By ~ 1

Author(s):

Yong Zhang ◽

Xin Wang ◽

Zongli Jiang ◽

Junfeng Wei ◽

Hiroyuki Enomoto ◽

...

Keyword(s):

Mass Loss ◽

Mass Balance ◽

Surface Mass Balance ◽

Negative Mass ◽

Glacier Surface ◽

Surface Mass ◽

Northeastern Siberia ◽

Response To Temperature ◽

Rapid Mass

Arctic glaciers comprise a small fraction of the world’s land ice area, but their ongoing mass loss currently represents a large cryospheric contribution to the sea level rise. In the Suntar-Khayata Mountains (SKMs) of northeastern Siberia, in situ measurements of glacier surface mass balance (SMB) are relatively sparse, limiting our understanding of the spatiotemporal patterns of regional mass loss. Here, we present SMB time series for all glaciers in the SKMs, estimated through a glacier SMB model. Our results yielded an average SMB of −0.22 m water equivalents (w.e.) year−1 for the whole region during 1951–2011. We found that 77.4% of these glaciers had a negative mass balance and detected slightly negative mass balance prior to 1991 and significantly rapid mass loss since 1991. The analysis suggests that the rapidly accelerating mass loss was dominated by increased surface melting, while the importance of refreezing in the SMB progressively decreased over time. Projections under two future climate scenarios confirmed the sustained rapid shrinkage of these glaciers. In response to temperature rise, the total present glacier area is likely to decrease by around 50% during the period 2071–2100 under representative concentration pathway 8.5 (RCP8.5).

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