May 1998

Briefs : Mechanical & Fluid Systems
Deflection of Circular Membrane Under Differential Pressure

Equations have been derived to fill a gap in previously published standard collections of stress-and-strain formulas: These are equations for deflection of a thin circular membrane that is clamped rigidly around its periphery and subjected to differential pressure. Related equations...

Briefs : Electronics & Computers
Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere

Plasma windows can separate vacuum and atmosphere, or regions of high and low vacuums, in a way which facilitates transmission of various particle beams and/or radiation from low- to high-pressure regions. In a prototype device, a stabilized plasma...

Briefs : Electronics & Computers
Bounceless Switch/Monostable Multivibrator

A circuit has been designed to debounce a mechanical switch, which is used to activate a digital circuit. Contacts tend to make and break connections several times until the switch contacts settle out. The repetitive activity plays havoc with digital circuits because more than one state condition could...

Briefs : Materials
Advanced Cryogenic Insulation System for Graphite/Organic Resin Composite Cryogenic-Tank Structures

Engineers at Rockwell International Corporation's Space System Division have developed a new method of insulating composite structural material that will stand up to the harsh environment of space. The new liquid-hydrogen cryogenic tankage...

Briefs : Mechanical & Fluid Systems
Deployable and Restowable Protective Dome
Briefs : Materials
High-Tg Thermosetting Polyimide

A thermosetting polyimide called "DMBZ-15" has been developed for use as a matrix material in relatively inexpensive matrix/fiber composite materials. The glass-transition temperature (Tg) of DMBZ-15 is 414°C. In contrast, the industry standard polyimide for such composites (developed in 1971 at Lewis...

Briefs : Physical Sciences
Source of Fast Oxygen Atoms for Testing Satellite Materials

We have developed an apparatus that generates a pulsed beam of fast oxygen atoms, under Small Business Innovation Research (SBIR) funding by NASA's Jet Propulsion Laboratory, to provide a ground test facility to qualify materials to be used in low Earth orbit (LEO). This development...

Briefs : Materials
Joining of SiC-Based Ceramic and Fiber-Reinforced Composite Parts

A process that involves reaction forming has been devised to enable the joining of high-temperature-resistant structural parts made of SiC-based materials. These materials include SiC-based ceramics and composites reinforced by fibers that are made of various component materials...

Briefs : Software
Program Counts Lines of Source Code

The Source Lines of Code Count (SLOCC) computer program counts the number of source lines of a computer code, as an aid in the management of software, documentation of code, estimation of cost, and satisfying miscellaneous code-metric needs. SLOCC accommodates the following programming languages: Ada, Pascal,...

Briefs : Mechanical & Fluid Systems
Probes for Measuring Pressures in Flowing Gases

Improved pressure probes have been designed to give nearly instantaneous readings of the time-varying local static pressure in flowing gases. The probes have been installed in a wind tunnel (see figure). Probes of this type could also be particularly useful as pressure-sensing instruments to help...

Briefs : Physical Sciences
Aircraft-Skin-Rivet Thermocouple

The aircraft-skin-rivet thermocouple is designed for measuring the temperature on the outer surface of an airplane wing under icing conditions. More specifically, its design was motivated by the need to measure the temperature near 32 °F (0 °C) on an aluminum wing skin, with an error of no more than 1 °F (0.6...

Briefs : Electronics & Computers
Better Electrochemical Profiling of III -V Semiconductors

An etching and electrolyte solution called "UNIEL" has been found to be useful for electrochemical characterization as a function of depth ("electrochemical profiling" for short) of semiconductor compounds of elements from periods III and V of the periodic table; that is, InP- and...

Briefs : Manufacturing & Prototyping
Magnetron Plasma Etching of SiC for Microfabrication

Magnetron plasma etching has been found to be a promising technique for micromachining of single-crystal silicon carbide to fabricate microscopic structures comprising integrated mechanical, electronic, and/or optical devices. Silicon carbide offers several advantages over silicon for the...

Briefs : Robotics, Automation & Control
Electromagnetic Shaker for Flight Flutter Testing

An electromagnetic shaker based on a linear induction motor has been developed for use in flight flutter testing of aircraft. The shaker is a wing-tip-mounted unit capable of delivering root-mean-square forces as large as 140 lb (623 N) at frequencies from 10 to 60 Hz.

Briefs : Electronics & Computers
More Uses for Brillouin Amplification

Some additional applications have been proposed to exploit amplification by stimulated Brillouin scattering ("Brillouin Amplification" for short), building on the concepts introduced in the preceding article. Chief among the proposed applications is conversion of a phase-modulated optical signal to an...

Briefs : Physical Sciences
Chimera/Unstructured Hybrid Grids for Flow and Heat Transfer

A hybrid-grid scheme has been developed to afford a computationally efficient means for numerically solving equations of both (1) coupled flows of heat and mass in a fluid and (2) conduction of heat in a body or bodies that bound the fluid. The scheme should prove especially beneficial...

Briefs : Electronics & Computers
Computer System for Collection of Quality-Assurance Data

The Paperless Procedure System (PPS) is a computer-based, semiautomated electronic system for collection and management of quality-assurance data in a large organization. The original version of PPS was designed for use by Kennedy Space Center personnel engaged in inspection tasks during...

Briefs : Electronics & Computers
Overview of Tapered-Slot Antennas

A document presents a comprehensive overview of the technology of tapered-slot antennas and arrays of such antennas. The fundamental operation of tapered-slot antennas is not yet fully understood, and, for lack of established design rules, the designs of these antennas have been based primarily on empirical...

Briefs : Materials
Fiber-Reinforced-Plastic/Concrete Structural Members

Improved concrete structural members such as columns, piers, and piles can be manufactured by incorporating fiber-reinforced-plastic (FRP) exterior shells and FRP interior submembers. The FRP components impart greater compressive, flexural and shear strengths and ductility to a concrete...

Briefs : Materials
Creep-Resistant Ceramic Composite for High-Temperature Use

A low-density, creep-resistant ceramic composite material has been developed as a prototype of such materials for use at high temperatures in the next generation of aircraft engines. The material consists of Nextel (or equivalent) ceramic fibers in a matrix that is, itself, a composite...

Briefs : Materials
Nearly Isotropic Resin-Transfer-Molded Composites

Nearly isotropic matrix/fiber composite materials can be made quickly and at relatively low cost by resin-transfer molding. The fiber components of these materials are fine, loosely woven, three-dimensional preforms; the matrix components are epoxy or polycyanate resins. With proper tooling,...

Briefs : Mechanical & Fluid Systems
Bidirectional Operating Actuator (BOA)

A generic actuator has been designed to amplify the piezoelectric effect. The Bidirectional Operating Actuator (BOA) amplifies the stroke of a piezoelectric element and reorients it through a kinematic linkage.

Briefs : Electronics & Computers
Automated Vision System Inspects a Large Surface

The figure schematically illustrates an automated electronic vision system that operates in conjunction with a scanning robot to inspect a large surface for damage. In the original application for which the system was developed, the surface comprises the panels of the space shuttle thermal...

Briefs : Robotics, Automation & Control
Micromachined Monopropellant Thrusters

A report proposes monopropellant microthrusters for a new generation of miniature spacecraft with mission lifetimes stretching into years. These thrusters would include micromachined nozzle/chamber assemblies containing microvalves, designed according to emerging concepts of microelectromechanical systems...

Briefs : Electronics & Computers
Control System for Steerable, Rooftop-Mounted Antenna

An excerpt from JPL Document D-12104 presents additional information on the control system of a steerable microwave antenna that is mounted on the roof of a land vehicle and used to communicate with a geostationary satellite. The antenna and control system were described previously in...

Briefs : Electronics & Computers
Fabrication of Arrays of Large Step-Free Regions on Si(100)

When a silicon wafer is cut from an ingot, it is essentially impossible to align the cut perfectly with the crystal structure. Therefore the surface contour of the wafer will be a flat plane on which terraces consisting of additional atomic layers will be scattered. An atomic step will...

Briefs : Materials
Iron-Containing Carbon Materials Made From Graphite Fluoride

Experiments have shown that carbon-based materials containing pure metallic iron, alloys of iron, halides of iron, and/or oxides of iron can be synthesized from precursors of general composition CFx, denoted loosely as graphite fluoride. Typical samples of the product...

Briefs : Electronics & Computers
Reflective Coating System for High-Temperature Vacuum Use

A substrate of nickel coated with a thin layer of silver and further coated with a thin protective layer of silicon dioxide has been found to constitute an optically reflective substrate/coating system that is suitable for use at high temperature in vacuum. This system was developed...

Briefs : Electronics & Computers
Extracting Misalignments of Layers in Microfabricated Devices

Two closely related methods of optical inspection and computation yield data on misalignments between critical features in different layers of microfabricated devices. Examples of such devices containing features in different layers that are required to be aligned with each other...

Briefs : Electronics & Computers
Optoelectronic Oscillators Based on Brillouin Scattering

An improved type of optoelectronic oscillator is based on Brillouin amplification. An oscillator of this type converts light energy into an electro-optical oscillation, typically at a frequency of several gigahertz. It offers several advantages over other electro-optical and over...

Briefs : Materials
Evaluation of Additives to PFPEs in Boundary Lubrication

A report describes experiments on the wear-reducing performances of six additives to perfluoropolyether (PFPE)-based fluids in the boundary-lubrication regime. The additives were a phosphate, a thiophosphate, a β-diketone, a benzothiazole, an amide/thiol, and a sulfite. Each additive was...

Briefs : Mechanical & Fluid Systems
Electromagnetic Smart Washer for Detecting Bolthole Cracking

Engineers have designed a new device, called the Smart Washer, that can electromagnetically detect bolthole cracks in metal structures. The device is a metal washer that contains a wire coil embedded onto the bottom surface of the washer. An alternating current drives this coil and...

Briefs : Electronics & Computers
Exploiting Brillouin Scattering in Analog Signal Processing

Stimulated Brillouin Scattering (SBS) in optical fibers can be exploited to obtain frequency conversion with amplification and frequency-selective amplification in photonic signal-transmission and signal-processing systems. SBS has been found to be particularly useful in photonic...


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