Tunable Double-Band Perfect Absorbers via Acoustic Metasurfaces with Nesting Helical Tracks

We propose a design of tunable double-band perfect absorbers based on the resonance absorption in acoustic metasurfaces with nesting helical tracks and deep-subwavelength thicknesses(<λ/30 withλbeing the operation wavelength).By rotating the cover cap with an open aperture on the nesting helical tracks,we can tailor the effective lengths of resonant tubular cavities in the absorber at will,while the absorption peak frequency is flexibly shifted in spectrum and the acoustic impedance is roughly matched with air.The simulated particle velocity fields at different configurations reveal that sound absorption mainly occurs at the open aperture.Our experiment measurements agree well with the theoretical analysis and simulation,demonstrating the wide-spectrum and tunable absorption performance of the designed flat acoustic device.

我的文化小学

文化小学已经陪伴我走过了四年的学习生活，时间如流水般逝去，我得赶紧记录下校园的点点滴滴。我们的学校好似世外桃源，学生与老师们在这里怡然自乐。鲜艳的塑胶跑道上，从不缺乏矫健的身影和欢呼雀跃的“拉拉队”，因为我们总会参与其中。