scholarly journals Pulse height analyser

2020 ◽  
Author(s):  
Daniel Bell ◽  
Zemar Vajuhudeen
Keyword(s):  
Pulse Height ◽  
Pulse Height Analyser

The Damage Capacity of Cavitating Flow From Pulse Height Analysis

1989 ◽  
Vol 111 (4) ◽  
pp. 502-509 ◽  
Author(s):  
S. A. Fry
Keyword(s):  
Circular Cylinder ◽  
Pulse Height ◽  
Pulse Amplitude ◽  
Flow Conditions ◽  
Noise Levels ◽  
Linear Calibration ◽  
Cavitation Noise ◽  
Pulse Height Analyser ◽  
Pulse Height Analysis ◽  
Digital Pulse

Digital pulse amplitude acquisition systems are reviewed and an analogue pulse height analyser (PHA) is described. Cavitation experiments are reported in which pressure pulses in the liquid (water) are picked up by a flush mounted pressure transducer and measured using the PHA. Tests were carried out on two cavitation sources: a 60 deg symmetric wedge and a circular cylinder. Despite generating similar r.m.s. noise levels the wedge is 21 times as damaging as the circular cylinder at peak noise flow conditions (at V = 16 m/s). By imposing thresholds on the spectra parameters it had been possible to find a linear calibration beween noise and erosion applicable to both cavitation sources over a range of flow velocities. A good correlation between cavitation noise and erosion was found by simply measuring the number of pulses above a suitable threshold.

Heterogeneity of Platelets: Origin of Light Platelet Fraction from 32N Megakaryocytes

1975 ◽  
Author(s):  
D. G. Penington ◽  
N. Y. T. Lee ◽  
A. Moore ◽  
K. Streatfield
Keyword(s):  
Pulse Height ◽  
Size Variation ◽  
Mixed Population ◽  
Density Fractions ◽  
Continuous Density ◽  
Pulse Height Analyser ◽  
Tubular System ◽  
Rat Platelets

Heterogeneity of circulating platelets has been ascribed to ageing but demonstration of differing cytoplasmic features in 8N, 16N and 32N megakaryocytes (Ser. Haemat. 8, 21, 1975) suggests that heterogeneity arises during platelet production.Rat platelets have been separated on continuous density gradients (whole blood on Ludox: PVP) and platelets sized using a Coulter Counter with 24 channel pulse: height analyser. Approx. 80% of rat platelets settle between S. G. 1,058 and 1.067 with marked, consistent size variation (modal channel, 6). Approx. 12% settle between 1,042 and 1,058 and are small in size (modal channel, 3) with few large platelets. Platelets between 1,007 and 1,074 are a mixed population, both large and small. In vivo 75Se selenomethionine injection gives synchronous labelling of the three density fractions. IN vitro incubation of platelets with colloidal gold 188Au (200–400 Å) gives more avid labelling of light than of median and heavy platelets. Mature megakaryocytes in vitro also take up colloid and 32N cells, with abundant demarcation tubular system, are particularly heavily labelled. Origin of small light platelets from 32N megakaryocytes is suggested.

A dual source gamma ray traversing mechanism suitable for the non-destructive simultaneous measurement of bulk density and water content in columns of swelling soil

Soil Research ◽  
1973 ◽  
Vol 11 (1) ◽  
pp. 83 ◽  
Author(s):  
BJ Bridge ◽  
N Collis-George
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Gamma Ray ◽  
Single Channel ◽  
Soil Column ◽  
Pulse Height ◽  
Silica Sand ◽  
Absorption Coefficients ◽  
Mass Absorption ◽  
Pulse Height Analyser

A traversing mechanism is described in which 100 mCi sources of americum-241 and caesium-137 are alternately brought into line with a sodium iodide (thallium) scintillation counter connected to a single-channel pulse height analyser equipped with two preset base lines. The equipment is capable of scanning a 10 cm diameter soil column equipped with sensors to a height of 200 cm, and facilities are provided for automatic indexing at preset intervals to an accuracy of 0.01 cm. Non-linear counting losses in the spectrometer system are described, and were found to be dependent on the window setting of the pulse height analyser. With the window setting adjusted to cover the apparent spread of the gamma peak, counting losses were negligible. Mass absorption coefficients of various materials were obtained using a compartmented box. Measured mass absorption coefficients of water, silica sand, and a chernozemic soil were 0.201, 0.247, and 0.303 cm2 g-1 respectively for americum-241, and 0.0826, 0.0746, and 0.0728 respectively for caesium-137. The precision of the apparatus was demonstrated by determining the moisture characteristic and bulk density characteristic of 0.5-1.0 mm aggregates of Narrabri soil during absorption and desorption. Gamma ray attenuation measurements and direct volumetric measurements were comparable. The standard deviations in the gamma ray measurements were found to be 0.03 g cm-3 for bulk density and 0.04 cm3 cm-3 for water content. Most of this inaccuracy arose from lack of precision in the americum-241 mass attenuation coefficient for the soil. By contrast, changes in moisture content and bulk density, at any level, of 0.004 cm3 cm-3 and 0.004 g cm-3 respectively, were statistically very significant.

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