May 1999

Briefs : Materials
Ceramic Composites of ZrB₂, HfB₂, ZrC, HfC, and SiC

Improved zirconium- and hafnium-based ceramic composites have been invented in an effort to obtain better resistance to ablation at high temperature. These ceramics are suitable for use as thermal-protection materials on the exterior surfaces of spacecraft reentering the terrestrial...

Briefs : Electronics & Computers
Biotelemetry Using Implanted Unit To Monitor Preterm Labor

A biotelemetric system for monitoring key physiological parameters of a fetus and its uterine environment is undergoing development. The main purpose of the monitoring is to detect preterm labor in order to enable timely treatment. At the present stage of development, the system monitors...

Briefs : Materials
Hybrid Composite Overwraps for Low-Pressure Tanks

Hybrid versions of the high-performance overwraps used on some low-pressure tanks have been proposed. The hybrid overwraps would weigh less than do the corresponding nonhybrid overwraps, as explained below.

Briefs : Physical Sciences
Single-Crystal YAG Reinforcement Preforms for Refractory Composites

Preforms (essentially, shaped mats) of single-crystal yttrium aluminum garnet (YAG) fibers can now be readily fabricated in net size and shape, with tailored orientation of the fibers. These preforms can be used as fiber reinforcements in ceramic- and metal-matrix composite...

Briefs : Electronics & Computers
Resonant Microstrip Patch Antenna as Ice-Thickness Gauge

Researchers at Johnson Space Center (JSC) recently demonstrated that the resonant microstrip patch antenna (RMPA), which has been proven in commercial applications, can be applied with equal success to measuring prelaunch ice buildup on the insulated low-temperature external tanks of the...

Briefs : Electronics & Computers
GPS "Compound Eye" Attitude Sensor

A proposed Global Positioning System (GPS) sensor would give information on approximate attitude as well as on position. Unlike other GPS-based attitude sensors, this attitude sensor would not depend on carrier-phase measurements and thus would not be subject to the difficulties and limitations involved in...

Briefs : Mechanical & Fluid Systems
Eclipse Aerotow Dynamics Experiment

NASA Dryden Flight Research Center is supporting a Phase II Small Business Innovation Research (SBIR) contract between the U.S. Air Force Research Labs and Kelly Space & Technology (KST). KST's innovation is to use an aerotowed reusable launch vehicle to put small satellites into low orbits around the...

Briefs : Software
Updated Software for Predicting Noise From Aircraft

The FOOTPR and RADIUS computer programs implement state-of-the-art mathematical models for predicting levels of noise generated by existing or proposed aircraft. These programs can be used to calculate Federal Aviation Administration (FAA) noise-certification levels, airport-vicinity noise...

Briefs : Materials
Repair of Composite-Overwrapped Pressure Vessels

Pressure vessels overwrapped with graphite-fiber-based composite materials that become damaged would be salvaged by a proposed repair technique. The need for the technique arises as follows: High-performance graphite-fiber-based composites are very susceptible to damage from impact or cutting....

Briefs : Mechanical & Fluid Systems
Direct Thrust-Measurement Technique Applied to an F-15 Airplane

Direct measurement of aircraft-engine thrust by use of strain gauges offers several advantages over traditional model-based methods of calculating thrust, provided that care is taken during the installation and calibration of strain gauges, and provided further that secondary load...

Briefs : Physical Sciences
Quadrupole Mass Analyzer Based on Linear Ion Trap

An improved quadrupole mass analyzer (QMA) has been proposed for use in determining the compositions of gas mixtures. The proposed QMA would incorporate two major innovations over traditional QMAs: (1) It would feature a simplified radio-frequency-excited quadrupole electrode structure that would...

Briefs : Materials
Properties of Cubic Boron Nitride Films

A report describes an experimental study of the surface-chemical, microstructural, and tribological properties of cubic boron nitride (c-BN) films, which are potentially useful as hard, wear-resistant coatings on bearings and on steel-cutting tools. For the experiments, BN films about 500 nm thick were...

Briefs : Physical Sciences
Acoustical-Sensor Assemblies for Use in Flows

Improved sensor assemblies have been invented for measuring acoustic signals in gases or liquids flowing in or around any of a variety of moving or stationary objects. Examples of such objects include land vehicles, aircraft, submarines, structures exposed to winds or natural water streams, and...

Briefs : Physical Sciences
Computing Chemical Kinetics With Low-Dimensional Manifolds

A method of computing the concentrations of chemical species in chemically reacting flows includes, among other things, utilization of a prior chemical-kinetic method based on a concept of intrinsic low-dimensional manifolds (ILDM) in composition space. The present method is particularly...

Briefs : Robotics, Automation & Control
Active Homopolar Magnetic Bearing

A report presents information on an earlier work on active magnetic bearings with high-critical-temperature superconducting coils. To recapitulate, the device is a homopolar radial-type active magnetic bearing with a bias coil and control coils made of a high-critical-temperature superconductor. The report...

Briefs : Physical Sciences
Inflatable Membrane Reflectors for Multiple-Purpose Applications

Experiments have demonstrated the feasibility of inflatable reflectors with very low system aerial densities of the order of 1 kg/m². Diverse applications include radio and optical communications, telescopes, and the concentration of sunlight for power generation. The same...

Briefs : Materials
Polymeric Composite Damage Protective Overwraps for Composite Pressure Vessels

Damage-tolerant polymeric composite overwraps have been proposed for lightweight pressure vessels that are made of composites of graphite fibers in polymeric matrices. Graphite-fiber/polymer composites are vulnerable to impact damage; overwraps on the pressure...

Briefs : Materials
Durable Advanced Flexible Reusable Surface Insulation

Continuing efforts to develop lightweight, flexible thermal-insulation blankets that withstand high temperatures have led to design and fabrication concepts that effect the following improvements:

Briefs : Robotics, Automation & Control
Experiment on Quasi-Tailless Flight of an X-31A Airplane

An experiment consisting of flight tests on the X-31A airplane (see figure) has demonstrated the ability to use thrust vectoring to replace the functions of stabilization and turn coordination usually required of a rudder and vertical tail. Comments by the pilot indicated no difference in...

Briefs : Manufacturing & Prototyping
Making Curved Diffractive Optics by E-Beam Lithography

Electron-beam (e-beam) lithography has shown promise as a technique for fabricating diffractive optical elements on nonflat substrates. Such optical elements could include convex or concave diffraction gratings with curved grating lines, for use in imaging spectrometers or other scientific...

Briefs : Medical
Improved Suit for Protection During Abrasive Blasting

An improved suit to be worn by a worker during abrasive blasting has been developed. Denoted an environmentally controlled abrasive-blasting suit (ECAB), it provides comprehensive protection that, heretofore, has been afforded by a set of special under- and over-garments (including a helmet)...

Briefs : Medical
Exoskeletal System for Neuromuscular Rehabilitation

A system of sensors and actuators designed to fit on the lower extremities of human patients and astronauts like an exoskeleton is under development to serve diverse purposes in neuromuscular research and rehabilitation. This system will be operated under both Earth and microgravity conditions....

Briefs : Electronics & Computers
LaNi₅₋ₓMₓ Alloys for Ni/Metal Hydride Electrochemical Cells

Studies of physical and chemical effects in the hydride-forming electrodes of rechargeable nickel/metal hydride electrochemical cells have yielded results that now guide efforts to formulate improved electrode alloys to extend the cycle lives of the cells. These efforts involve...

Briefs : Photonics/Optics
Novel Coating Technology Improves Ball Lenses for Fiber Coupling

Small ball (full sphere) lenses in the 0.5-mm to 3.0-mm diameter range offer a number of practical advantages for fiber-to-fiber coupling and fiber collimation. Ball lenses are more physically compact and less expensive than commonly used gradient index (GRIN) lenses. Furthermore,...

Briefs : Photonics/Optics
Two-Axis Reflective Device for Image Stabilization and Beamsteering

Scientists, astronomers, optical re-searchers, and manufacturers frequently require two-axis reflective optical mechanisms to meet the requirements of robust beamsteering systems. Image tracking, scene scanning, line-of-sight pointing and/or beam stabilization designs often...

Briefs : Electronics & Computers
Compact Magnetic-Sensor Units for Detecting Mines

Compact, low-power-consumption magnetic-sensor units called "integrated sensor system" (ISS) units are being developed for detecting buried mines and arsenals without exposing human searchers to unnecessary danger. The fully developed ISS units would be mass produced at relatively low cost, so...

Briefs : Electronics & Computers
Finite-Width Coplanar-Waveguide Patch Antenna

The upper part of Figure 1 illustrates an antenna derived by widening the middle strip conductor of a finite-width coplanar waveguide (FCPW) to form a rectangular patch. An FCPW offers all the advantages of a conventional coplanar waveguide, along with the additional advantage that its finite-width...

Briefs : Manufacturing & Prototyping
Integrally Wound Skirt for Composite-Overwrapped Tank

The skirt that supports a composite-overwrapped tank would be made an integral part of the composite overwrap, according to a proposal. In current practice, the structure that supports a composite-overwrap tank usually includes a layer of rubber between the tank and its skirt. The rubber...

Briefs : Manufacturing & Prototyping
Crimping Thin PTFE Tubes Onto Thin Stainless-Steel Tubes

A crimping technique has been developed for fastening polytetrafluoroethylene (PTFE) tubes of 0.032-in. (0.81-mm) outside diameter and 0.0105-in. (0.267-mm) inside diameter onto stainless-steel hypodermic tubes of 0.0105-in. (0.267-mm) outside diameter. The technique was developed to...