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A Study on the Correlation between Wood Moisture and the Damping Behaviour of the Tonewood Spruce

100%

Göken J., Fayed S., Schäfer H., Enzenauer J.

Acta Physica Polonica A

2018

vol. 133

issue 5

1241-1260

In acoustic musical instruments special attention needs to be paid to those particularly sensitive parts made of tonewood whose function is to respond to vibrations. One of the most important tonewoods is spruce because of its good resonance properties. Spruce is especially used for soundboards, these being the primary source of sound. Piano manufacturers dry their soundboards to approximately 6% wood moisture, at which drying stage they are glued into the instrument. Fluctuations of the moisture content in the wood affect the tone. With changing moisture content, the instrument can go out of tune, even cracks can appear at very low moisture content in the wood. In addition, the tone colour will change. This may result from changes in the hammer felt or from changes in the vibration properties of the soundboard. Strain- and frequency-dependent damping measurements were carried out on spruce wood at different wood moisture contents in order to investigate the effect of the moisture content on the vibration behaviour. Wood which is slowly dried in air for several years is preferably used for high-class pianos. Therefore, damping measurements on new and on more than 130-year old spruce wood samples were performed.

Investigations on ZnSe/GaAs Interface by Treatment of GaAs (2×4) Surface with Te and Mg

64%

Ebel R., Spahn W., Ress H., Albert D., Schäfer H., Ehinger M., Faschinger W., Landwehr G.

Acta Physica Polonica A

1996

vol. 90

issue 4

767-772

The heterovalent interface ZnSe/GaAs, despite the small lattice misfit, still poses certain problems. The condition of the substrate surface prior to growth start determines the initial growth conditions, which on the other hand are assumed to be responsible for defect densities. Since Zn, in contrast to Se, hardly binds to GaAs the initial surface during growth start is essentially Se terminated. Therefore the binding of Mg to Se terminated GaAs was investigated. The structural quality of 140 nm thick ZnSe layers on different MgSe coverages were compared to conventionally grown and Te initiated ZnSe epilayers of the same thickness.

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2 Acta Physica Polonica A

1 2018

1 1996

2 Schäfer H.

1 Albert D.

1 Ebel R.

1 Ehinger M.

1 Enzenauer J.

1 Faschinger W.

1 Fayed S.

1 Göken J.

1 Landwehr G.

1 Ress H.

1 Spahn W.

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A Study on the Correlation between Wood Moisture and the Damping Behaviour of the Tonewood Spruce

Investigations on ZnSe/GaAs Interface by Treatment of GaAs (2×4) Surface with Te and Mg