A robust vibration absorber reduces vibrations of a system over a range of frequencies. Passive vibration absorption is achieved with a tuned mass and spring (known as a dynamic vibration absorber (DVA)). This is a simple, low cost method of reducing vibrations at a single frequency; however, in order to achieve robust absorption a heavy mass is required. Active vibration control is achieved wi...

The absorption performance of a locally-reacting acoustic metamaterial under oblique incidence is studied. The metamaterial is composed of a slotted panel, each slit being loaded by an array of Helmholtz resonators. The system is analytically studied using the transfer matrix method, accounting for the viscothermal losses both in the resonator elements and in the slits, allowing the representat...

Soft X-ray microscopy is a powerful tool for high-resolution mapping of light elements in thin specimens such as a biological cell with a few-micron thickness. We have explored the method to obtain intracellular distribution of light elements particularly of minor light elements such as Ca, P, and S. Since abundant major light elements, C, O and N are constituent elements of most biomolecules, ...

We demonstrate a duct muffler design that operates in the low-frequency range (<2000 Hz). The device contained pair of coupled annular Helmholtz resonators (HRs) and porous material stuffing. HRs were installed as side branches circular tube to avoid affecting ventilation. Porous materials employed form an asymmetric intrinsic loss HR enable achieve perfect sound absorption. An analytica...