In a Helmholtz resonator, a volume of gas (usually air) in a confined space with a small opening (e.g. a neck or a hole) is set into motion by a driving force whereby the gas is either compressed or rarefied. This creates either a high or low pressure field, expelling or pulling...
Extrudates were compressed at a constant rate of 50 mm/min, and the maximum force (hardness) was recorded up to an assumed 50% strain. The compressive strain was estimated as the force divided by the cross-sectional area of the extrudates [51]. 2.9. Measurement of Colour Parameters The ...