Investigation of acoustic performance of compressed wool carpets

Sound absorbers including porous materials are used widely for noise control. The most widely exploited and acknowledged absorption mechanism in porous materials is viscous friction due to relative motion between solid and fluid. Acoustical performance of carpet made of wool by using a traditional compression technique has been investigated. The results are very interesting

Laser spectroscopy of gas confined in nanoporous materials

We show that high-resolution laser spectroscopy can probe surface interactions of gas confined in nano-cavities of porous materials. We report on strong line broadening and unfamiliar lineshapes due to tight confinement, as well as signal enhancement due to multiple photon scattering. This new domain of laser spectroscopy constitute a challenge for the theory of collisions and spectroscopic lineshapes, and open for new ways of analyzing porous materials and processes taking place therein.Comment: 4 pages, 3 figures, partly presented orally at 7th International Conference on Tunable Diode Laser Spectroscopy (TDLS), July 2009 in Zermatt, Switzerland; Accepted for Applied Physics Letters (December 2009

Porous materials show superhydrophobic to superhydrophilic switching

Switching between superhydrophobicity and superhydrophilicity in porous materials was predicted theoretically and demonstrated experimentally with the example of thermally induced contact angle change; tunability of this system was also demonstrated

Sound propagation through bone tissue

Effect of perforation on structure borne sound propagation through rigid porous materials has been investigated. Experimental works has been carried out on rigid porous materials with and without perforations. A low frequency vibration has been applied to excite the material structure by using a force transducer connected a shaker to detect the changes in resulting response. Applied vibration on sample surface causes structure borne sound wave to propagate through the material. The resulting response of this structural borne vibration is detected by using an accelerometer. The results with and without perforation of the sample have been compared. The results show that changing the structure of the material has an effect on the amplitude, shape and arrival time of the transmitted acoustic wave

Thermal conductivity and electrical resistivity of porous materials

Process for determining thermal conductivity and electrical resistivity of porous materials is described. Characteristics of materials are identified and used in development of mathematical models. Limitations of method are examined

Optical coherence tomography for vulnerability assessment of sandstone

Sandstone is an important cultural heritage material, in both architectural and natural settings, such as neolithic rock art panels. The majority of deterioration effects in porous materials such as sandstone are influenced by the presence and movement of water through the material. The presence of water within the porous network of a material results in changes in the optical coherence tomography signal intensity that can be used to monitor the wetting front of water penetration of dry porous materials at various depths. The technique is able to detect wetting front velocities from 1 cm s_1 to 10~6 cms-1, covering the full range of hydraulic conductivities likely to occur in natural sandstones from pervious to impervious. © 2013 Optical Society of America