Optical elements formed by compressed gases: Analysis and potential applications

Spherical, cylindrical, and conical shock waves are optically analogous to gas lenses. The geometrical optics of these shock configurations are analyzed as they pertain to flow visualization instruments, particularly the rainbow schlieren apparatus and single-pass interferometers. It is proposed that a lens or mirror formed by gas compressed between plastic sheets has potential as a fluid visualization test object; as the objective mirror in a very large space-based telescope, communication antenna, or energy collector; as the objective mirror in inexpensive commercial telescopes; and as a component in fluid visualization apparatuses

Large-aperture interferometer using local reference beam

A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed

Neural coding of high-frequency tones

Available evidence was presented indicating that neural discharges in the auditory nerve display characteristic periodicities in response to any tonal stimulus including high-frequency stimuli, and that this periodicity corresponds to the subjective pitch

Rainbow Schlieren

The rainbow schlieren is an apparatus in which the usual schlieren knife edge cutoff is replaced by a radial rainbow filter with a transparent center and an opaque surround. With this apparatus most refractive index nonuniformities in the test section appear varicolored whereas uniformities appear white. The rainbow schlieren is simple, easy to use, and relatively inexpensive and gives much greater detail regarding nonuniformities than does the ordinary schlieren. Moreover, the rainbow schlieren permits quantitative evaluation of certain refractive index distributions, including those involving turbulence, by simple calculations

On the use of electrical ion sources for ion tracer experiments in the magnetosphere

Electric ion source in orbit around earth to generate probes for magnetosphere studies of electric fields, ion diffusion, and distant magnetic field configuratio

Loudness (annoyance), prediction procedure for steady sounds

Method has been devised to predict loudness level of any steady sound solely from its measured power spectrum level. Method is based on assumption that, with respect to loudness sensation, the human auditory system acts as open-loop transmission system with transmittance function determined from measured tone curves

Polarized Neutron Matter: A Lowest Order Constrained Variational Approach

In this paper, we calculate some of the polarized neutron matter properties, using the lowest order constrained variational method with the $AV_{18}$ potential and employing a microscopic point of view. A comparison is also made between our results and those of other many-body techniques.Comment: 23 pages, 8 figure

Dynamic Project Control Utilising a New Approach to Project Control

A new system has been developed for dynamic project management and control known as Planning Orientation Evaluation Methods (POEM) which has been considered as a core project evaluation system incorporating cost and time analysis. The performance control gives the manager a direct influence on the project completion date and rate of spend