Special Coverage

How Model Rockets Launch Tomorrow's Engineers
Lost in Space: Smart Spacesuits Feature 'Home' Button
With a Commercial Printer, Researchers Manufacture Motion Sensors in Bulk
NASA Supercomputer Simulations Reveal 'Noisy' Aerodynamics
Is It Hot in Here? New Double-Sided Fabric Will Find Your 'Comfortable' Temperature
Sound-Off: Thermoset Composites vs. Traditional Metals
Electric ‘Smart’ Paper Picks Up on Pipe Leaks
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat

Numerical Speed of Sound

The numerical speed of sound is a variable that is used in the numerical solution of flows from low to high speeds. The numerical speed of sound is an effective speed of sound associated with Mach numbers used in the numerical splitting of a flow into upwind and downwind mass-flux components that are defined on the faces of cells of a computational grid into which a flow volume is divided. Depending on the details of a given flow problem and the algorithm chosen to solve it, the numerical speed of sound may or may not equal the physical speed of sound.

Posted in: Briefs, TSP, Information Technology, Mathematical models, Noise, Noise

Locally Connected Neural Networks for Pattern Recognition

Neural networks of a proposed type would be formed with computational units called "neuromorphs" attached in a locally connected array. These neural networks would achieve pattern recognition invariant under rotation and translation by exploiting a combination of network symmetry and biologically inspired image-information-processing concepts. The architecture of these networks can be implemented in software; it is also suitable for implementation in hardware in the form of single-chip integrated circuits that would function in parallel-processing modes and thus be capable of fast recognition of patterns.

Posted in: Briefs, Electronics & Computers, Architecture, Computer software / hardware, Computer software and hardware, Neural networks, Architecture, Computer software / hardware, Computer software and hardware, Neural networks

Cross-Correlated Trellis-Coded Quadrature Modulation

Cross-correlated trellis-coded quadrature modulation (XTCQM) has been proposed as a generic scheme with specific embodiments that potentially offer superior alternatives to other highly power- and bandwidth-efficient phase-shift-keying (PSK) modulation schemes. Examples of such schemes include Gaussian minimum-shift keying (GMSK), staggered quadrature offset raised cosine (SQORC), Feher's patented quadrature PSK (FQPSK), and pulse-shaped offset quadrature PSK (OQPSK).

Posted in: Briefs, TSP, Electronics & Computers, Architecture, Architecture, Performance upgrades

Thrust Stand Measures Thrusts of

The development of miniature, cold- gas thrusters for on-orbit propulsion of such small devices as remotely piloted cameras and for inclusion in astronaut propulsion backpacks gave rise to a need to measure thrusts ranging from 0.04 to 0.8 lb (0.2 to 3.6 N). In addition, there was a need to measure thrust in a vacuum environment as well as in air at a pressure of 1 atmosphere (0.1 MPa), and over a wide range of propellant inlet pressures. The primary obstacle to be overcome for such measurements was to solve the problem of delivering the cold-gas propellant (compressed nitrogen gas) to the thruster without affecting thrust measurements, particularly those below 1/4 lb (1 N).

Posted in: Briefs, TSP, Test & Measurement, Attitude control, Attitude control, Propellants, Gases, Spacesuits, Spacecraft

Software for Designing Model Rockets for Base-Heating Tests

The Impulse Combustion Excel (ICE) computer program was developed to facilitate and accelerate the design and analysis of subscale rocket engines for use in base-heating tests. Such tests are performed on the ground to obtain data for estimating the heating effects of hot exhaust plumes on the aft regions of full-scale rockets during ascent. The computer program is so named because typically, a base-heating test involves impulse combustion — short-duration (of the order of 100 ms long) hot firing using flight propellants. Heretofore, the design of the subscale engines and base-heating tests has been a difficult, time-consuming, iterative process. ICE can be expected to reduce the testing times and costs and to yield improved designs. ICE can be used to design models to be tested in both wind tunnels and vacuum tanks.

Posted in: Briefs, Test & Measurement, CAD / CAM / CAE, CAD, CAM, and CAE, Scale models, Rocket engines, Thermal testing

Software for Analysis of Contamination of the ISS

The NASAN computer program can perform detailed analyses of molecular column density and molecular deposition on and around such complex space structures as the International Space Station (ISS). Contamination from both point sources (e.g., thrusters and vents) and diffuse sources (e.g., reflected plumes or outgassing of materials) can be analyzed. NASAN has been used to perform the assessments reported in the ISS incremental-design-review documents.

Posted in: Briefs, TSP, Software, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Hazardous materials, Spacecraft

CVD of Diamond Using Magnetoplasmadynamic Sources

A program of research and development is addressing the feasibility of using magnetoplasmadynamic (MPD) sources in the chemical vapor deposition (CVD) of synthetic diamond films. Because of its unique combination of thermal, electronic, mechanical, and chemical properties, diamond has potential for use as a coating material in numerous engineering and scientific applications.

Posted in: Briefs, TSP, Materials, Fabrication, Chemicals, Coatings Colorants and Finishes, Coatings, colorants, and finishes, Magnetic materials

Oxygen Batteries Based on a Solid Polymer Electrolyte

Scientists have developed a derivative of the lithium-ion cell that could prove useful in spaceflight and commercial applications in which it is planned to use oxygen batteries based on solid polymer electrolytes. This derivative cell, which contains a solid polymer electrolyte and an oxygen gas cathode, is designed for and operates best in an oxygen-rich atmosphere. (Inasmuch as the derivative cell as designed cannot store oxygen, the gas must be obtained from the environment.) Because the demand for portable electronic devices for scientific, educational, and even entertainment uses is constantly increasing, the need for rechargeable batteries as alternative means to power these devices is also increasing. Batteries based on the present derivative cell could be one such alternative means.

Posted in: Briefs, TSP, Materials, Battery cell chemistry, Battery cell chemistry, Product development, Electrolytes, Oxygen, Polymers

Microfabricated High-Q Optical Resonators for Microphotonics

Submillimeter-sized, transparent, solid, truncated spheres and ellipsoids for use as optical resonators in integrated microphotonic devices would be made by microfabrication techniques like those used in the electronic industry to make integrated circuits, according to a proposal. Such resonators, heretofore denoted generally as "microspheres," have been described in several recent articles in NASA Tech Briefs. In a microsphere, resonance is achieved through glancing-incidence total internal reflection in one or more "whispering-gallery" modes, in which the light propagates in equatorial planes near the surface, with an integer number of wavelengths along a nominal closed circumferential trajectory. If the surface of the resonator is sufficiently smooth and a sufficiently close approximation of a sphere or ellipsoid, then in principle, the resonance quality factor (Q) is limited only by attenuation in the resonator material; for a microsphere made of fused silica, this translates to a potential to obtain Q "e1010.

Posted in: Briefs, TSP, Physical Sciences, Downsizing, Architecture, Optics, Architecture, Optics, Fabrication

Knowledge-Based Software for Generating and Changing Plans

A methodology of computer-aided planning has been developed to (1) accelerate the generation of plans for activities within complex systems of personnel and equipment; (2) increase the quality of the plans thus generated; and (3) decrease the difficulty of predicting and responding to the effects of changes in plans, requirements, resources, and/or other constraints. Originally intended for application to planning of missions of the space shuttle and other spacecraft, the methodology could also be applied to strategic business planning, management of projects, general scheduling, and planning of manufacturing processes and systems.

Posted in: Briefs, Information Technology, Artificial intelligence, Computer software / hardware, Computer software and hardware, Artificial intelligence, Computer software / hardware, Computer software and hardware, Systems management, Spacecraft

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