Tech Briefs

A comprehensive library of technical briefs from engineering experts at NASA and major government, university, and commercial laboratories covering all aspects of innovations in electronics, software, photonics, imaging, motion control, automation, sensors, test, materials, manufacturing, mechanical, and mechatronics.

 Briefs : Materials
Experiments on Residual-Stress Bondline Failures in an RSRM

A report describes an experimental study undertaken to verify a finite-element mathematical model used to predict residual stresses and stress-induced failures in the adhesive interfacial layers (bondlines) that join phenolic liners to interior surfaces of metal housings of...

 Briefs : Mechanical & Fluid Systems
Improved Micromachined Vaporizing-Liquid Microthruster

A report describes an improved micromachined vaporizing-liquid microthruster (VLM), now under development as a prototype of thrusters for microspacecraft. This thruster is of the resistojet type: the energy for vaporization and expansion of a propellant liquid is provided through...

 Briefs : Physical Sciences
Sizes of Surface and Capped InxGa1-xAs/GaAs Quantum Dots

A report describes an experimental study of the sizes and concentrations of capped (buried) and surface In0.6Ga0.4As/GaAs quantum dots that were grown by metal-organic vapor deposition under the same conditions except for the inclusion or exclusion of capping....

 Briefs : Physical Sciences
Fuel Cell Would Generate Power From Martian Atmosphere

A report proposes the development of a thin-film fuel cell that would generate electric power from two minor constituents of the Martian atmosphere — O2 and CO. These compounds are generated continuously by photolysis of CO2, the major constituent. The fuel cell...

 Briefs : Photonics/Optics
System for Measuring Three Tilts and Distance of an Object

An optoelectronic system discussed herein measures the state of alignment (SOA) of an object under test in four of its six degrees of freedom (DOFs). This system was originally intended for use in determining the SOA of an optical bench in a vacuum chamber. The basic design and mode of...

 Briefs : Photonics/Optics
Thermal Imaging for Diagnosing Fuel Cells

Thermal (that is, infrared) imaging has been demonstrated to be an effective technique for the diagnosis of operating fuel cells and fuel-cell stacks. Thermal imaging can be used to identify a variety of phenomena, described below, that are associated with nonuniform generation of heat. Hence, thermal...

 Briefs : Photonics/Optics
Tunable Ultraviolet Light Source for Combustion Experiments

An ultraviolet light source that comprises a tunable diode laser and associated optics provides the optical excitation needed for simultaneous wavelength-modulation-absorption spectroscopy (WMS) and laser-induced-fluorescence (LIF) measurements in experiments on combustion. These...

 Briefs : Physical Sciences
Fourier-Transform X-Ray Microscope

A proposed x-ray instrument - a Fourier-transform x-ray microscope - would enable high-resolution imaging of objects with sizes of the order of 20 nm. (This size range is typical of cell organelles.) The instrument would also offer a spectroscopic capability for the sensitive detection and identification of...

 Briefs : Photonics/Optics
Ring-Resonator/Bragg-Grating Laser-Feedback Elements

Integrated optical structures that contain ring resonators and Bragg gratings have been proposed as external feedback elements for semiconductor lasers. These feedback elements would constrain the laser spectra to narrow lines (more precisely, narrow spectral bands) centered at desired...

 Briefs : Photonics/Optics
Computer Program for Designing Diffractive Optics

AMPERES is a prototype computer program that implements the algorithm, described in the preceding article, for optimizing designs of diffractive optics. Several other programs for designing refractive optics are commercially available, but they offer very limited capabilities with respect to...

 Briefs : Photonics/Optics
Fiber-Optic Illumination for Microscope

In a simple but very effective method for providing intense illumination of an opaque specimen under a microscope, light is supplied via an optical fiber. This system eliminates the need for traditional Köhler-type vertical illumination system components, such as beam splitters and lenses, and is easily...

 Briefs : Photonics/Optics
Algorithm for Optimizing Designs of Diffractive Optics

An algorithm for optimizing the designs of diffractive optics is based on constrained dynamics and the reciprocity of electromagnetic propagation. This algorithm can contribute to realization of the potential of diffractive optics, which offer capabilities greater than those of refractive...

 Briefs : Photonics/Optics
Improved Etalon-Type Fiber-Optic Hydrogen Sensors

Three modifications have been proposed for hydrogen sensors in which hydrogen in the air causes changes in the reflection spectra of interferometric film stacks that are interrogated via optical fibers. One of the films in the stack in each such sensor contains palladium, which reacts with...

 Briefs : Photonics/Optics
Wavelength-Agile External-Cavity Diode Laser

A prototype wavelength-agile external-cavity diode laser (ECDL) was demonstrated in the first phase of a continuing effort to develop noninvasive laser-based instruments that would measure absolute concentrations of trace gases. As envisioned, these instruments would offer a combination of high...

 Briefs : Photonics/Optics
Enhanced Optical Microresonators for Detecting Molecules

Sensors based on microscopic optical resonators and arrays of such resonators have been proposed for detecting trace amounts of specific molecules in small gaseous, liquid, and solid samples. In addition to compactness, these sensors would offer ultrahigh sensitivity - in some cases,...

 Briefs : Software
Software for Automated Ortho-Rectification of SAR Images

The Automated SAR Ortho-rectification Software System enables users of synthetic-aperture-radar (SAR) data to form processed images that are free of the distortion caused by the SAR imaging geometry and topography. The software consists of four modules:

 Briefs : Mechanical & Fluid Systems
Actuated Ball-and-Socket Joints

The term "actuated ball-and-socket" (ABS) characterizes a proposed class of ball-and-socket joints that would incorporate ultrasonic motors and other piezoelectric actuators to generate multidimensional actuation. In some applications, ABS joints could supplant traditional joint-and-actuator assemblies that...

 Briefs : Materials
End Caps Increase Thermo-Oxidative Stability of Polyimides

Latently reactive end caps have been investigated as improved means to increase the thermo-oxidative stability of polyimides of the polymerization of monomeric reactants (PMR) type, which are often used as the matrix resins of high-temperature-resistant composite materials. The present...

 Briefs : Materials
End Caps for More Thermo-Oxidative Stability in Polyimides

An additional class of end-cap compounds that increase the thermo-oxidative stability of polyimides of the polymerization of monomeric reactants (PMR) type has been invented. The prior class of end-cap compounds in this line of development is described in the preceding article.

 Briefs : Materials
Low-Density, Ablative Resin-Impregnated Ceramic Insulation

Low-density, ablative thermal-protection panels can be made by impregnating fibrous ceramic substrates with organic polymers. With proper design and fabrication, these panels can protect temporarily against temperatures up to 3,500 °C or heat fluxes up to 16 MW/m2.

 Briefs : Materials
Solar Heating for Deployment of Foam Structures

Solar heating has been proposed as a means of deployment of structures of the type described in "Cold Hibernated Elastic Memory (CHEM) Expandable Structures," (NPO-20394), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 56. A few examples of structures that would be amenable to the CHEM...

 Briefs : Materials
Fluorinated Diamondlike Carbon Coatings

Some experiments directed toward the development of improved hard, lubricious coating materials have involved direct fluorination of proprietary diamondlike coats on various substrates. The idea is to retain the hardness of the diamondlike material while adding surface molecular structures that impart the...

 Briefs : Electronics & Computers
Ultra-Efficient Ka-Band MMIC Power Amplifier

A proposed monolithic microwave integrated circuit (MMIC) power amplifier has been designed to operate at frequencies around 28 GHz. According to a computer simulation of performance, this amplifier would operate at a power-added efficiency of more than 60 percent, which is more than 20 percent above...

 Briefs : Electronics & Computers
Implementing Permutation Matrices by Use of Quantum Dots

Integrated circuits of a proposed type based on quantum-dot cellular automata (QCA) would implement permutation matrices. These circuits would serve as prototype building blocks for demonstrating the feasibility of quantum-dot-based computing and for the further development of increasingly...

 Briefs : Software
Software for Concurrent Development of Reusable Software

The YaM computer program provides a conceptual framework (including configuration management) and a set of software tools that support the concurrent development of reusable software by members of a team. YaM favors development of software in modules that can be assembled into packages and...

 Briefs : Software
Adaptive Problem Solving for Refining Control Strategy

A computer program implements an adaptive problem-solving (APS) algorithm for real-time development, refinement, and maintenance of the control strategy of an autonomous system that must operate in an environment about which little or no detailed information is available in advance. In the...

 Briefs : Software
Advanced Software for Two-Phase Thermohydraulic Systems

Recent improvements in the SINDA/FLUINT computer program have made the program into a highly capable, commercially viable software product for general mathematical modeling of thermohydraulic systems. Versions of SINDA/FLUINT have been described in a number of previous NASA Tech Briefs...

 Briefs : Software
Test Automation Software for AI Planning Software

This test automation software reduces the burden of testing artificial-intelligence (AI) planning software written in the Heuristic Scheduling Testbed System (HSTS) [a software architecture for planning and scheduling]. It automates what would otherwise be the labor intensive and...

 Briefs : Software
Software for Simulation of 3D, Three-Phase Combusting Flow

A computational fluid dynamics (CFD) code has been developed to enable simulation of spray combustion near the fuel injectors in a liquid-fueled rocket engine. This code reflects the three-dimensional (3D), multiphase nature of the flow field in a rocket engine and is capable of modeling...

 Briefs : Mechanical & Fluid Systems
Flex Wedges

Flex wedges have been proposed for use in brakes and clutches like those in which, heretofore, basic wedges have been used. Flex wedges (see Figure 1) offer advantages of superior braking and clutching performance and less weight, relative to basic wedges.

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