Thermophysical and transport properties of humid air at temperature range between 0 and 100 °C

Three-dimensional (3-D) ultrasound (US) is an emerging new technology with numerous clinical applications. Ultrasound probe calibration is an obligatory step to build 3-D volumes from 2-D images acquired in a freehand US system. The role of calibration is to find the mathematical transformation that converts the 2-D coordinates of pixels in the US image into 3-D coordinates in the frame of reference of a position sensor attached to the US probe. This article is a comprehensive review of what has been published in the field of US probe calibration for 3-D US. The article covers the topics of tracking technologies, US image acquisition, phantom design, speed of sound issues, feature extraction, least-squares minimization, temporal calibration, calibration evaluation techniques and phantom comparisons. The calibration phantoms and methods have also been classified in tables to give a better overview of the existing methods.

A review of calibration techniques for freehand 3-D ultrasound systems.

Mechanical aspects of membrane thermodynamics. Estimation of the mechanical properties of lipid membranes close to the chain melting transition from calorimetry

The speeds of sound in water measured by Del Grosso and Mader [J. Acoust. Soc. Am. 52, 1442–1446 (1972)], Kroebel and Mahrt [Acustica 35, 154–164 (1976)], and Fujii and Masui [J. Acoust. Soc. Am. 93, 276–282 (1993)] were compared. A fairly good agreement was found. A new fifth-order polynomial describing the dependence of the speed of sound in water on temperature (ITS-90) within the limits 0–95 °C was proposed. The importance of the effect of impurities of water on the systematic errors of the measurement results was pointed out. The accuracy of the relative measurements of speed of sound in liquids was discussed in the context of the proper choice of a standard (“true”) value of the speed in water.

Water as a standard in the measurements of speed of sound in liquids

This paper describes new algorithms, not previously available, for predicting atmospheric absorption of sound at high altitudes. A basis for estimating atmospheric absorption up to 160 km is described. The estimated values at altitudes above 90 km must be considered as only approximate due to uncertainties about the composition of the atmosphere above 90 km and simplifying assumptions. At high altitudes, classical and rotational relaxation absorption are dominant, as opposed to absorption by molecular vibrational relaxation that is the principle atmospheric absorption loss mechanism for primary sonic booms propagating downward from a cruising supersonic aircraft. Classical and rotational relaxation absorption varies inversely with atmospheric pressure, thus increasing in magnitude at high altitudes as atmospheric pressure falls. However, classical and rotational losses also relax at the high values of frequency/pressure reached at high altitudes and thus, for audio and infrasonic frequencies, begin to dec...

Atmospheric absorption in the atmosphere up to 160 km

In view of the adoption of the International Temperature Scale of 1990 (ITS‐90), which defines the International Celsius Temperatures, t90, the dependence on temperature of the speed of sound in pure water is examined. Drawing on the experimental data published previously [V. A. Del Grosso and C. W. Mader, ‘‘Speed of Sound in Pure Water,’’ J. Acoust. Soc. Am. 52, 1442–1446 (1972)], it is found that the change from the previous t68 scale is significant. At 100 °C, the difference between the two scales (t68−t90) is 0.026 °C, resulting in a difference of 0.022 m/s for the speed of sound. The speed of sound is fitted to a new fifth‐order polynomial applicable over the t90 range 0–100 °C.

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Speed of sound in pure water as a function of temperature

In view of the adoption of the International Temperature Scale of 1990 (ITS‐90) which defines the International Celsius Temperatures t90, the dependence on temperature of the speed of sound in seawater is reexamined. The coefficients for two seawater sound‐speed equations published previously, one by UNESCO (1983) which is also known as the Chen and Millero equation of 1977, and one by DelGrosso (1974) are revised for application with the new temperature scale ITS‐90. It is found that the resulting change in seawater sound speed is within 0.024 and 0.017 m/s for the UNESCO and the DelGrosso equations, respectively. These changes are comparable to the numerical correction values suggested by Dushaw et al. (1993).

Speed of sound in seawater as a function of salinity, temperature, and pressure

This paper describes the calculation of a new value for sound speed (c0=331.29 m s−1) in standard dry air at 0 °C and at a barometric pressure of 101.325 kPa. The maximum uncertainty is estimated to be approximately 200 ppm. The theory of the calculation is based on the equation of state, and includes the knowledge of γ/M which is derived from published theoretical and experimental thermodynamic data on the constituents of the standard atmosphere. Investigations which led to the general acceptance of the previous sound speed are examined, and there is good evidence to conclude that, in previous sound speed assessments, the maximum possible uncertainties were sufficient to encompass the above new sound speed. The variation of sound speed with carbon dioxide concentration and temperature is also discussed.

Speed of sound in standard air

Erratum: Speed of sound in pure water as a function of temperature [J. Acoust. Soc. Am. 93, 1609–1612 (1993)]

This paper describes the influence of humidity on the speed of sound in standard atmospheric air at various temperatures. The prediction is based on theoretical and experimental data obtained for the variation of the ratio of specific heats, γ, in humid air. Over a temperature range from 0°–30° Celsius, the maximum uncertainty in the sound speed ratio ch/c0, is estimated to be about 400 ppm. Comparison is made with known experimental measurements and theoretical data.

George S. K. Wong

Papers

Speed of sound in pure water as a function of temperature

Speed of sound in seawater as a function of salinity, temperature, and pressure

Speed of sound in standard air

Erratum: Speed of sound in pure water as a function of temperature [J. Acoust. Soc. Am. 93, 1609–1612 (1993)]

Variation of the speed of sound in air with humidity and temperature