Donald W. Baker

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The sample volume of continuous and pulsed ultrasonic Doppler velocity detectors can be examined using a small underwater jet. A test probe (line of velocity) is formed by the jet when it is seeded with silicone antifoam emulsion. A novel collection tube downstream from the nozzle prevents the spent scatters from contaminating the test tank. Studies are(More)
A pulsed ultrasonic Doppler flowmeter for detailed measurements of velocity profiles in man is described. The device projects a beam of ultrasound in bursts of 0·4 μs duration, at 5 MHz, into the flow; the back-scattered signals are processed to produce a signal corresponding to the mean velocity over a small region of the flowing stream. The size and shape(More)
Rietveld refinement using neutron powder diffraction data is reported for the potential lead-free piezoelectric material K(x)Na(1-x)NbO3 (x = 0.05, x = 0.3) at low temperatures. The structures were determined to be of rhombohedral symmetry, space group R3c, with the tilt system a(-)a(-)a(-) for both compositions. It was found that some of the structural(More)
The structure of the A-site substituted perovskite K(x)Na(1 - x)NbO(3), x = 0.24-0.36, where a phase boundary was previously reported, has been determined by high-resolution X-ray powder and neutron powder diffraction studies. The structure of the x = 0.3 compound was refined in the monoclinic space group Pm at 293 K and in P4mm at 523 K. The Glazer tilt(More)
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