Multi-functional programmable active acoustic meta-device: acoustic switch, lens, and barrier.

Active acoustic metamaterials (AAMM) have garnered special attention because of their potential as multi-function devices. In this direction, the present article demonstrates a novel AAMM that can be programmed as a multi-functional Active Acoustic Meta-device (AAMD) that can switch functionalities between Acoustic Switch (AS), Acoustic Lens (AL), and Acoustic Barrier (AB). Functionality: AL corresponds to the wave vector space, and AS and AB correspond to the frequency space of the proposed AAMM.

Estimation of dose contribution from 226Ra, 232Th and 40K radon exhalation rates in soil samples from Shivalik foot hills in India.

The concentration of radium, thorium and potassium and radon exhalation rates in soil samples collected from Shivalik foot hills in the states of Haryana and Himachal Pradesh (India) were experimentally measured. A high-resolution gamma-ray spectroscopic system was used for the measurement of natural radioactivity ((226)Ra, (232)Th and (40)K) at Inter-University Accelerator Center, New Delhi, using a coaxial n-type high-purity germanium detector (EG&G, ORTEC, Oak Ridge, USA). The mass exhalation rates (EM) of radon in soil samples from the study area measured by 'sealed canister technique' using LR-115 type II track detectors varied from 50±1 to 143±6 mBqkg(-1) h(-1).