Physical Sciences

This report presents a study of numerical simulations of mixing layers developing between opposing flows of paired fluids under supercritical conditions, the purpose of the study being to elucidate chemical-species- specific aspects of turbulence. The simulations were...

This report presents a study of dissipation (irreversible production of entropy) in three-dimensional, temporal mixing layers laden with evaporating liquid drops. The purpose of the study is to examine the effects of evaporating drops on the development of turbulent features in flows....

The Mars Cost Tracking Model is a computer program that administers a system set up for tracking the costs of future NASA projects that pertain to Mars. Previously, no such tracking system existed, and documentation was written in a variety of formats and scattered in various places. It was difficult to...

A paper presents a theoretical investigation of subsonic and supersonic effects in a Bose-Einstein condensate (BEC). The BEC is represented by a time-dependent, nonlinear Schroedinger equation that includes terms for an external confining potential term and a weak interatomic repulsive...

Compact, lightweight instruments have been developed for measuring small flows of helium and/or detecting helium leaks in solenoid valves when the valves are nominally closed. These instruments do not impede the flows when the valves are nominally open. They can be integrated into newly fabricated...

A method for correcting measured coherence spectra for the effect of incoherent instrument noise has been developed and demonstrated. Coherence measurements are widely used in engineering and science to determine the extent to which two signals are alike. The signals may come from...

Two reports discuss methods for evaluating the magnitude of electrostatic charging that occurs in spacecraft dielectric materials (in particular, polyimides) during prolonged exposure to radiation in outer space. The reports describe experiments on the electrical resistivities and...

Reversible, colorimetric fiber-optic sensors are undergoing development for use in measuring concentrations of ammonia in air at levels relevant to human health [0 to 50 parts per million (ppm)]. A sensor of this type includes an optical fiber that has been modified by replacing a portion of its cladding with a polymer...

A report discusses selected aspects of a continuing program to develop thermally stable, lightweight mirrors for planned Earth-observing spaceborne instruments. These mirrors are required to retain precise concave or convex surface figures required for diffraction-limited optical...

An airborne submillimeter-wavelength radiometer, expected to be built and tested in the near future, is designed primarily to yield measurement data that can be processed to quantify the ice contents and mean sizes (and, to some extent, the shapes) of ice crystals in cirrus clouds that range...

A technique for detecting a small leak of gas into a vacuum involves the use of a diaphragm made of a thin film of poly (vinylidene fluoride) [PVDF]. To exploit the piezoelectricity of PVDF for this purpose, both sides of the film are coated with thin, electrically conductive layers that serve as...

A paper presents some novel conclusions concerning the Shvab-Zel’dovich (SZ) vari- ables, which are linear combinations of dep- endent variables in mathematical models of multicomponent, chemically reacting flows. The SZ variables represent scalar quantities that are conserved, that is, are not...

Two reports describe a method of assessing the susceptibility of digital electronic equipment to upsets (bit errors) caused by impingement of energetic ions (both protons and heavier ions) in outer space. The method, which is applicable at the single-component, circuit-board, box, and...

The membrane test cell (MTC) is an automated laboratory apparatus that applies a known osmotic potential across a membrane and measures the kinetics of the resulting transport of solvents across the membrane as a function of time. Data acquired by use of the MTC should prove especially...