Magazine

A proposed technique would make it possible to maintain two reservoirs of superfluid helium at the same pressure but at different temperatures. Heretofore, a fountain effect (described below) has made this impossible. The proposed technique could be useful for low-temperature...

A method of in situ chemical analysis by use of small, simple, robust sensors has been proposed. The basis for the proposal is the discovery that chemical reactions emit acoustic waves, and that characteristic frequency spectra are associated with specific reactions. The acoustic frequencies...

Innovative designs of mufflers for engines of small airplanes have been investigated in an effort to satisfy conflicting demands to maximize the reduction of exhaust noise while minimizing back pressure, size, and weight. Automotive-type muffler designs are not suitable for this purpose because they entail...

An etching solution has been developed for use in removal of silver plating from polymer-based (including composite-material) structural components, the surfaces of which are intended to serve as mirrors and waveguide structures. Such structures are often plated with aluminum, copper, and...

A report discusses the design and testing of a laboratory-model arc-jet thruster designed to operate at a nominal power level of 300 W. This thruster is an intermediate product of continuing efforts to develop smaller, lower-power, higher-specific-impulse thrusters for use in a forthcoming generation of small...

An in vitro test that includes the use of two-color flow cytometry has been developed for use in screening of neutrophils for their ability to fight infections. Neutrophils constitute the first line of defense of the human body against infections. Neutrophils engulf invading bacteria in a...

The Synchronous Parallel Environment for Emulation and Discrete-Event Simulation (SPEEDES) is now using a new general-purpose priority queue data structure called the SPEEDES Qheap for managing its set of pending events in ascending time order. Empirical studies have shown this data structure to...

A proposed wavelength-division-multiplexing (WDM) optical communication system would feature a single optical fiber carrying eight channels of digital data signals. In the original application, the signal in each channel would be a serial digital video-camera output, but the system could just...

The NLEDIT computer program implements a generic graphical user interface for the preprocessing of FORTRAN namelist input files. The interface consists of a menu system, a message window, a help system, and data-entry forms. A form is generated for each namelist. The form includes an input...

Cross-talk in integrated-circuit focal-plane arrays of quantum-well photodetectors (QWIPs) equipped with microlenses would be reduced, according to a proposal, by etching deep trenches into the substrates of these devices. The proposal applies, more specifically, to GaAs-based,...

The MacWafer™ code computes gravitational and thermal stresses in silicon wafers and uses these results to determine the maximum allowable temperature variation across a wafer, maximum processing temperatures, and maximum allowable heating and cooling rates. This information is of particular...