Electroacoustic absorbers consist of loudspeakers, shunted with an electrical circuit designed to obtain a given acoustic impedance. Their design and principles are now well understood. Unidimensional experiments, using plane waves under normal incidence in ducts, agree perfectly with simulations and confirm the validity of the model: the low-frequency absorption is maximal (and total) when the...

All vehicles use suspension system. The suspension system mainly consists of a mechanical spring and a damper. The damper dissipates the mechanical energy into heat and thus damps down the vehicle oscillations. In a bid to reduce the vehicle emissions, many technologies are being thought to reduce energy losses and also recover energy from the energy losses if any. One such technology is regene...

This paper reports on a numerical study of the six-band metamaterial absorber composed of two alternating stack of metallic-dielectric layers on top of a continuous metallic plane. Six obvious resonance peaks with high absorption performance (average larger than 99.37%) are realized. The first, third, fifth, and the second, fourth, sixth resonance absorption bands are attributed to the multiple...

A high performance solar absorber using a 2D tantalum superlattice photonic crystal (PhC) is proposed and its design is optimized for high-temperature energy conversion. In contrast to the simple lattice PhC, which is limited by diffraction in the short wavelength range, the superlattice PhC achieves solar absorption over broadband spectral range due to the contribution from two superposed latt...

Headspace oxygen in sample vial for the purge-and-trap dynamic headspace/gas chromatography method oxidizes meat if held hours before purging, influences volatile profiles, and misrepresents the true composition of volatiles. Helium flush and helium flush plus oxygen absorber were used to eliminate residual oxygen and minimize oxidative changes in meat during sample holding time. Both helium fl...

Solar collector (Air heater) has low thermal efficiency due to the low thermal conductivity between Air and absorber plate. So there is a need to enhance the thermal conductivity between air and absorber plate. This leads higher temperature to absorber plate and hence maximum thermal losses occurs to environment .It can be made possible by creating artificial roughness on absorber plate .There ...

This paper presents the characterization of integrated micromachined waveguide absorbers in the frequency band of 220 to 325 GHz. Tapered absorber wedges were cut out of four different commercially available semi-rigid absorber materials and inserted in a backshorted micromachined waveguide cavity for characterization. The absorption properties of these materials are only specified at 10 GHz, a...

An epoxy-modified urethane rubber mixed with carbon particles is now chosen as the millimeter-wave absorber material in our study. The absorption characteristics of the absorber is measured under temperature changes. The weatherability of our absorber is also clarified based on absorption characteristics, thickness and hardness of the sample. As a result of the temperature characteristics of th...

We investigate the average time for the earliest particle to hit a spherical absorber when a homogeneous gas of freely diffusing particles with density ρ and diffusivity D is prepared in a deterministic state and is initially separated by a minimum distance l from this absorber. In the high-density limit, this first absorption time scales as l D 1 ln ρl in one dimension; we also obtain the firs...

Detection peculiarities of an un-cooled (room temperature) 8×8 pixel array designed to image broadband THz radiation were investigated. Each pixel consists of a thin conductive film absorber on a dielectric membrane with thermopile temperature readout. It was designed and tested for four combinations of two different types of absorber and thermopile materials. The photo-response profile, determ...