The line shape theory of Hess draws its attractiveness from the fact that it approaches the correct asymptotic theories at low and high pressures. In this paper, Hess's theory is generalized slightly to describe overlapping lines of diatomic molecules immersed in a bath of diatomic molecules. A "spherical" approximation is introduced in which the collision integrals are averaged over the propagation direction. In terms of a reduced S matrix evaluated in three commonly used coupling schemes, the pressure broadening cross sections agree with well-known results, and the isotropic Dicke line narrowing cross section is expressed in a form suitable for numerical computation. Both cross sections can be expressed as linear sums of generalized cross sections having the same formal structure.

The purpose of this paper is to demonstrate how an enthalpy method for heat conduction problems with moving boundaries associated with phase changes can be combined with Kirchhoff and coordinate transformations to put these problems in a particularly simple form. All nonlinearities in density, conductivity, and specific heat can be concentrated in the functional relation between enthalpy and the generalized temperature. Convection in the fluid is neglected. A simple numerical example is included.

We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- and long-range orders. General advantages of our technique are compact design, modest resolution requirements, insensitivity to slow surface microstructure changes (as seen with oxidation), and insensitivity to zero-mean-noise processes such as turbulence and vibration. Herein we detail the theory of our technique and the results of a number of experiments. Thesetests are intended to demonstrate the performance advantages and limitations of the transform method of processing speckle strain-rate data.

We have developed a highly sensitive method for measuring thermal expansion, mechanical strain and creep rates. We use the well-known technique of observing later speckle with a linear array detector, but employ a novel data processing approach based on a two-dimensional spectral transform of the speckle history as recorded by the detector. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Furthermore, although the measurement approach uses objective (non-imaged) speckle, the algorithm provides simultaneous global estimates of the strain rates at both small-and large-scale sizes. Such estimates may be of value in investigating materials with different shortand long-range orders. General advantages of our technique are compact design, modest resolution requirements, insensitivity to slow surface microstructure changes (as seen with oxidation) and insensitivity to zero-mean-noise processes such as turbulence and vibration. Herein we describe the theory of our processing algorithm, present results of measurements of strain in titanium wires and discuss the resolution limits of the measurement technique and subsequent data processing.

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