β Scribed by S. Moss; K. Attenborough
No coin nor oath required. For personal study only.
A suspension of alumina particles in air has been created inside a cylindrical tube. The attenuation and dispersion characteristics of the mixture have been calculated from the impulse response of the tube, with and without the dust suspension. Results are presented for three dust sizes with mean radius 2.0, 3.1 and 6.7 txm, over the frequency range 200 Hz to 2 kHz. Dust concentrations varied between 6 and 18 ppm by volume. Results are compared with predictions of a multiple scattering model. Agreement is reasonable for larger particle sizes, while the smallest particle distribution showed higher than predicted dispersion. The measurements show larger discrimination in acoustical effects between different mean particle sizes than predicted.
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Field surveys of dust concentrations within and dust emissions from cattle, pig and poultry buildings were conducted in England, the Netherlands, Denmark and Germany. Measurements of inhalable and respirable dust concentrations were made in 329 buildings. Concentrations of CO within and outside the
## Abstract An account is given or a new laboratory method of determining the least proportion of incombustible dust which must be added to a combustible dust in order that the mixture, when dispersed in any volume of air will not propagate flame. In common with other smallβscale methods depending
would need to be trapped in order to bring the viscosity results back to the correct value. A clue to this can be found from observations of the specific heat 4 and adsorption characteristics 5 of He 3-tte 4 mixture films, from which it was inferred that the He 3 component of such films resides main