Alfred G. Emslie

Flow of a Viscous Liquid on a Rotating Disk

Equations describing the flow of a Newtonian liquid on a rotating disk have been solved so that characteristic curves and surface contours at successive times for any assumed initial fluid distribution may be constructed. It is shown that centrifugation of a fluid layer that is initially uniform does not disturb the uniformity as the height of the layer is reduced. It is also shown that initially irregular fluid distributions tend toward uniformity under centrifugation, and means of computing times required to produce uniform layers of given thickness at given angular velocity and fluid viscosity are demonstrated. Contour surfaces for a number of exemplary initial distributions (Gaussian, slowly falling, Gaussian plus uniform, sinusoidal) have been constructed. Edge effects on rotating planes with rising rims, and fluid flow on rotating nonplanar surfaces, are considered.

Theory of the propagation of UHF radio waves in coal mine tunnels

The theoretical study of UHF radio communication in coal mines, with particular reference to the rate of loss of signal strength along a tunnel, and from one tunnel to another around a corner is the concern of this paper. Of prime interest are the nature of the propagation mechanism and the prediction of the radio frequency that propagates with the smallest loss. The theoretical results are compared with published measurements. This work was part of an investigation of new ways to reach and extend two-way communications to the key individuals who are highly mobile within the sections and haulageways of coal mines.

Spectral Reflectance and Emittance of Particulate Materials. 2: Application and Results

Experimental data on the spectral emittance of particulate minerals, obtained using a Michelson interferometer operating between 300 cm(-1) and 1400 cm(-1) are compared with the results of a new theory of the spectral reflectance (emittance) of such materials. The comparisons show that the theory predicts the infrared spectra of minerals quite well both for single substances and mixtures, over the wide particle size range between 0.3 micro and 330 micro. The good agreement suggests that the theory can be used in the application of remote infrared spectroscopy to such problems as the compositional analysis of the surface of a planet.

Infrared Spectra of Lithium Halide Monomers

The infrared spectra of the lithium halides have been re‐examined. The vibrational constants of the diatomic molecules are LiClωe=641±3ωexe=4.2±0.3LiBrωe=563.2±0.2ωexe=3.53±0.15ωeye=0.02±0.03LiIωe=498.2±0.2ωexe=3.39±0.15ωeye=0.08±0.03. The first five coefficients of the Dunham expansion of the potential energy have been obtained for lithium bromide and iodide. Rittners ionic model has been found to give a good representation of the potential energy. The ionic‐model treatment of the lithium halides has been extended to take account of the higher multipole polarizabilities of the halide ions. The introduction of quadrupole and higher polarizabilities destroys the agreement between observed and calculated spectroscopic constants which is found when only dipole polarizabilities are used.

Infrared spectra from fine particulate surfaces.

Characteristic spectral information can be obtained from a surface composed of fine particles either if the spectrum is observed at sufficiently high signal-to-noise ratio or if the particles are well compacted.

Infrared Spectra of the Group II Halides: Zinc Halides and the Ionic Model

The bending vibrations of gaseous ZnCl2 and ZnBr2 have been observed in the cesium iodide region at 295 and 225 cm—1, respectively. It is shown that a molecular model based on polarizable ions cannot account for the observed bending frequencies of the Group II dihalides.

Optical constants of monoclinic anisotropic crystals: gypsum

The principal complex refractive indices for gypsum have been derived in the infrared region of the spectrum. These values were obtained by dispersion analysis of the reflection spectra for E ‖ b and the a-c (monoclinic) plane. Two sets of complex indices are obtained for the latter plane, taking account of axis wander. The oscillator parameters are presented here, together with formulas for calculating the optical constants at any desired infrared frequency. In addition the usefulness of such optical constants for modeling the infrared properties of powders is demonstrated for gypsum and spodumene.

Sensitive Tiltmeter Utilizing a Diamagnetic Suspension

A tiltmeter of the horizontal pendulum type is described whose mass consists of a diamagnetic material suspended in a potential well of a suitably shaped magnetic field. The depth of the potential minimum determines the restoring force acting upon the mass and consequently the pendulous frequency and sensitivity of the instrument. In this manner the elastic forces usually supplied by fine springs or fibers are replaced by field forces and the mass is free to respond to tilts or accelerations without any trace of friction of external (Coulomb) or internal (anelastic) origin. The required amount of damping is obtained from eddy currents induced in the seismic mass by its motion in the field. The instrument requires no power to operate the suspension and it can be used over a wide range of temperatures. Under usual environmental conditions, it requires no temperature control. Some of the preliminary results obtained with the tiltmeter in measurement of earth tides are discussed.

Infrared emittance of fibrous materials

A theory of the IR emittance of fibrous materials has been developed. The theory predicts the IR spectral emittance of a matte of randomly arrayed cylindrical fibers as a function of the optical constants of the fiber material, the fiber diameter, the packing density of the fibers, the packing of the fibers within fiber bundles, the reflectance of the substrate, and the thickness of the fabric layer. Theoretical simulations were made and compared with experimental measurements of the IR emittance of polypropylene samples. Both the theory and the experimental data confirm the validity of the concept that fabrics can be tailored by a proper choice of the above parameters so as to obtain an emittance distinctly different from unity.

Effective optical constants of anisotropic materials

The applicability of a technique for determining the optical constants of soil or aerosol components on the basis of measurements of the reflectance or transmittance of inhomogeneous samples of component material is investigated. Optical constants for a sample of very pure quartzite were obtained by a specular reflection technique and line parameters were calculated by classical dispersion theory. Predictions of the reflectance of powdered quartz were then derived from optical constants measured for the anisotropic quartz and for pure quartz crystals, and compared with experimental measurements. The calculated spectra are found to resemble each other moderately well in shape, however the reflectance level calculated from the psuedo-optical constants (quartzite) is consistently below that calculated from quartz values. The spectrum calculated from the quartz optical constants is also shown to represent the experimental nonrestrahlen features more accurately. It is thus concluded that although optical constants derived from inhomogeneous materials may represent the spectral features of a powdered sample qualitatively a quantitative fit to observed data is not likely.