A constant pressure gas flowmeter using a directly driven diaphragm bellows as a volume displacer was studied. This flowmeter is perfectly vacuum-sealed, does not contain elastomers and liquids that would prevent outgassing at elevated temperatures and can achieve a smaller ratio of the final volume to the displaced volume than when bellows are used, so that the uncertainty in generating small flow rates can be small. As, when a bellows is used in the volume displacer, the displaced volume cannot be calculated from the geometric dimensions and its dependence on the displacement is non-linear, a sensitive method had to be developed for measuring this dependence. The uncertainty in measuring the displaced volume by this method and the achieved uncertainty of the flowmeter were determined.

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This work is concerned primarily with the acoustic structure and propagation of sound in highly porous, layered, fine fiber materials. Of particular interest is the utilization of the Kozeny number for determining the static flow resistance and the static structure factor based on flow permeability measurements. In this formulation the Kozeny number is a numerical constant independent of volume porosity at high porosities. The other essential parameters are then evaluated employing techniques developed earlier for open-cell foams. [J. Acoust. Soc. Am. 72, 879–887 (1982)]. The attenuation and progressive phase characteristics in bulk samples were measured and compared with predicted values. The agreements on the whole were very satisfactory.

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The pressure differences between the positions for gauge connection in a chamber for gauge comparison were measured and evaluated in two ways: (a) by the mutual interchange of two ionization gauges at the positions; and (b) by readings of one ionization gauge at various positions and of a spinning rotor gauge at a fixed position. The pressure in the chamber was set up by simultaneous admission and pumping of the gas. Differences of the order of a few percent were observed, probably caused by imperfect adjustment of the gas-introducing jet. Those differences are specific to the given apparatus, they depend on its adjustment, the geometry and some other parameters. The two methods are suitable for checking and adjusting the apparatus.

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In this paper, a new measurement system and a new approach in calculation for infrared (IR) radiation investigation in quasi-simultaneous transmission laser welding of plastics are presented. The measurement system is based on a MW/SWIR (medium-wave/short-wave IR) camera and optical filters narrowing the spectral region to SWIR. The measured signals contain radiation from the melted zone in between the semitransparent and absorbing polymers, as well as radiation from the surface and interior of the semitransparent polymer. The new calculation approach was developed to distinguish between these signals. It is based on simplification of the process to two places with two temperatures (surface and molten interface) and knowledge of the spectral optical properties of the material, filters, and camera response. The results of measurement and calculation for three different optical filters and polyoxymethylene samples with two thicknesses are shown and discussed. Good agreement is obtained for the calculation variant using normal transmissivity of the semitransparent polymer.