Circular piston

The body, in the form of a cylindrical chamber, is fitted with a radial partition and a central hub. The circular piston has a slot gap in the circumference to fit over the partition... 

The specimen s compaction is carried out using the proctor method in accordance with CEN EN 13286-2 (2012) (normal or modified compaction, whichever is chosen), whereas the diameter of circular piston (50 5 mm), the piston s penetration velocity (1.27 mm/min) and the rest of the procedure are similar to the American standard. 

By means of the inverse piezoeleetric effect, the ferroelectret samples can also be used as sound sourees. Measurement of the sound pressure on axis in the far field yields the inverse 33 eoeffieient. In this method, the ferroelectret sample, driven sinusoidally with an AC voltage, is used as sound sources and can be modeled as a circular piston mounted in an infinite baffle (Kressmann 2001b Sessler and Hillenbrand 2013). The on-axis sound pressure p(r) generated by a circular piston with radius R and area TtR, mounted in an infinite baffle, at a distance r is given by... 

Here in Chapter 1 we make the additional assumptions that the fluid has constant density, that the cross-sectional area of the tube is constant, and that the walls of the tube are impenetrable (i.e., no transpiration through the walls), but these assumptions are not required in the general definition of piston flow. In the general case, it is possible for u, temperature, and pressure to vary as a function of z. The axis of the tube need not be straight. Helically coiled tubes sometimes approximate piston flow more closely than straight tubes. Reactors with square or triangular cross sections are occasionally used. However, in most of this book, we will assume that PFRs are circular tubes of length L and constant radius R. 

With a constant, circular cross section, A = 2jiR (although the concept of piston flow is not restricted to circular tubes). If Cp is constant,... 

Fig. 13.41 The Keuerleber and Pahl (1970) mixhead. In the closed or recirculation position, reactants recirculate through grooves (c) along the cylindrical cleanout piston (b). In the open position, reactants flow at high velocity through circular orifices (a), impinge in the chamber (d), and flow out to the mold cavity (diagram from G. Oertel, 1985 (80)). [Reprinted by permission from C. W. Macosko, RIM Fundamentals of Reaction Injection Molding, Hanser, Munich, 1989.]...

In axial-flow viscometers, the sample is made to flow through a duct of regular cross-section. Capillary (circular cross-section) and slit (rectangular cross-section) viscometers are controlled stress instruments a known pressure difference (which causes shear stress in the sample) is applied over the duct length, and the resulting volumetric flow rate measured. In the extrusion viscometer, a controlled shear rate instrument, the sample is extruded through a capillary tube by the action of a constant speed piston, acting on the sample in a cylindrical reservoir to which the capillary is attached. The pressure difference between the ends of the capillary is measured. 

The above statements of the nature of the photoacoustic effect are drawn primarily from the conclusions of the theory developed by Rosencwaig and Gersho (R-G) (9), based on a onedimensional thermal piston model. Since this is the starting point for extending the theory of photoacoustic spectroscopy (PAS) to include photoacoustic circular dichroism (PACD), a brief survey of the salient factors and important parameters of that treatment follows. 

A piston slides freely in a circular cylinder (diameter 6 in.). At what... 

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