Tech Briefs

Separation and Sealing of a Sample Container Using Brazing

This process is an alternative to a prior explosive welding process.

A special double-wall container and a process for utilizing the container are being developed to enable (1) acquisition of a sample of material in a “dirty” environment that may include a biological and/or chemical hazard; (2) sealing a lid onto the inner part of the container to hermetically enclose the sample; (3) separating the resulting hermetic container from the dirty environment; and (4) bringing that hermetic container, without any biological or chemical contamination of its outer surface, into a clean environment. The process is denoted “S3B” (separation, seaming, and sealing using brazing) because sealing of the sample into the hermetic container, separating the container from the dirty environment, and bringing the container with a clean outer surface into the clean environment are all accomplished simultaneously with a brazing operation. This container and process were conceived as a superior alternative to the double-wall container and process described in “Explosion Welding for Hermetic Containerization” (NPO-20868), NASA Tech Briefs, Vol. 27, No. 8 (August 2003), page 46. As in the previously reported case, the present container and process were originally intended to be used to return samples from Mars to Earth, but could also be used on Earth to store and transport material samples acquired in environments that contain biological and/or chemical hazards.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Containers, Joining, Adhesives and sealants, Hazardous materials

High-Speed Noninvasive Eye-Tracking System

This system operates at a frame rate of several kilohertz.

The figure schematically depicts a system of electronic hardware and software that noninvasively tracks the direction of a person’s gaze in real time. Like prior commercial noninvasive eye-tracking systems, this system is based on (1) illumination of an eye by a low-power infrared light-emitting diode (LED); (2) acquisition of video images of the pupil, iris, and cornea in the reflected infrared light; (3) digitization of the images; and (4) processing the digital image data to determine the direction of gaze from the centroids of the pupil and cornea in the images. Relative to the prior commercial systems, the present system operates at much higher speed and thereby offers enhanced capability for applications that involve human-computer interactions, including typing and computer command and control by handicapped individuals, and eye-based diagnosis of physiological disorders that affect gaze responses.

Posted in: Briefs, Bio-Medical, Medical, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Computer software / hardware, Computer software and hardware, Imaging, Imaging and visualization, Body regions, Diagnosis, Human machine interface (HMI)

Detergent-Specific Membrane Protein Crystallization Screens

A suite of reagents has been developed for three-dimensional crystallization of integral membranes present in solution as protein-detergent complexes (PDCs). The compositions of these reagents have been determined in part by proximity to the phase boundaries (lower consolute boundaries) of the detergents present in the PDCs. The acquisition of some of the requisite phase-boundary data and the preliminary design of several of the detergent- specific screens was supported by a NASA contract. At the time of expiration of the contract, a partial set of preliminary screens had been developed. This work has since been extended under non-NASA sponsorship, leading to near completion of a set of 20 to 30 different and unique detergent-specific 96-condition screens.

Posted in: Briefs, Bio-Medical, Medical, Research and development, Materials properties

A New Approach to Railgun Operation Requires Analysis of Electromagnetic Fields

To find the best materials and design for effective railguns, analysis must be performed to determine how electromagnetic fields are generated and distributed.

Railguns, which propel a projectile using electromagnetic forces instead of chemical explosions, promise to revolutionize projectile launchers. Such guns have been built and operated successfully on a test basis, but several problems are holding them back from usage in the field. To solve these problems, researchers must understand the inner workings of these weapons. Several groups are conducting research taking different approaches to how the electromagnetic fields within these guns operate. One group, whose proposals differ from traditional thought, is using COMSOL Multiphysics software to illustrate the validity of their views.

Posted in: Briefs, Mechanical Components, Mechanics, Simulation and modeling, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Defense industry, Research and development

Plasmonic Antenna Coupling for QWIPs

Plasmonic antennas would be potentially superior alternatives to surface corrugations.

In a proposed scheme for coupling light into a quantum-well infrared photodetector (QWIP), an antenna or an array of antennas made of a suitable metal would be fabricated on the face of what would otherwise be a standard QWIP (see figure). This or any such coupling scheme is required to effect polarization conversion: Light incident perpendicularly to the face is necessarily polarized in the plane of the face, whereas, as a matter of fundamental electrodynamics and related quantum selection rules, light must have a non-zero component of perpendicular polarization in order to be absorbed in the photodetection process. In a prior coupling scheme, gratings in the form of surface corrugations diffract normally incident light to oblique angles, thereby imparting some perpendicular polarization. Unfortunately, the corrugation- fabrication process increases the overall nonuniformity of a large QWIP array. The proposed scheme is an alternative to the use of surface corrugations.

Posted in: Briefs, Physical Sciences, Antennas, Antennas, Materials properties

Evaporation-Cooled Protective Suits for Firefighters

In comparison with suits now in use, these could protect for longer times.

Suits cooled by evaporation of water have been proposed as improved means of temporary protection against high temperatures near fires. When air temperature exceeds 600 °F (316 °C) or in the presence of radiative heating from nearby sources at temperatures of 1,200 °F (649 °C) or more, outer suits now used by firefighters afford protection for only a few seconds. The proposed suits would exploit the high latent heat of vaporization of water to satisfy a need to protect against higher air temperatures and against radiant heating for significantly longer times. These suits would be fabricated and operated in conjunction with breathing and cooling systems like those with which firefighting suits are now equipped.

Posted in: Briefs, Physical Sciences, Water, Fire fighting, Protective clothing

Electronic Tongue Containing Redox and Conductivity Sensors

Progress has been made toward long-lived sensors for monitoring water quality.

Electronic tongue 2 (E-tongue 2) represents the second generation of the apparatus described in “Electronic Tongue for Quantitation of Contaminants in Water” (NPO-30601), NASA Tech Briefs, Vol. 28, No. 2 (February 2004), page 31. To recapitulate: The previously reported apparatus, now retrospectively denoted E-tongue 1, is an assembly of sensors for measuring concentrations of metal ions and possibly other contaminants in water. Potential uses for electronic tongues include monitoring the chemical quality of water in a variety of natural, industrial, and laboratory settings, and detecting micro-organisms indirectly by measuring microbially influenced corrosion.

Posted in: Briefs, Physical Sciences, Sensors and actuators, Sensors and actuators, Water pollution, Materials identification, Metals

Improved Heat-Stress Algorithm

Corrections for solar radiation and wind increase the accuracy of determining dangerous outdoor work environments.

NASA Dryden presents an improved and automated site-specific algorithm for heat-stress approximation using standard atmospheric measurements routinely obtained from the Edwards Air Force Base weather detachment. Heat stress, which is the net heat load a worker may be exposed to, is officially measured using a thermal-environment monitoring system to calculate the wet-bulb globe temperature (WBGT). This instrument uses three independent thermometers to measure wet-bulb, dry-bulb, and the black-globe temperatures. Two reasons for this project were limited access to the Dryden monitoring system and delays of the required manual issuances for heat-stress warnings.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Humidity, Weather and climate, Human factors, Personnel, Thermal testing, Military vehicles and equipment

A Method of Partly Automated Testing of Software

Principles of symbolic execution and temporal monitoring are exploited.

A method of automated testing of software has been developed that provides an alternative to the conventional mostly manual approach for software testing. The method combines (1) automated generation of test cases on the basis of systematic exploration of the input domain of the software to be tested with (2) run-time analysis in which execution traces are monitored, verified against temporal-logic specifications, and analyzed by concurrency-error-detection algorithms. In this new method, the user only needs to provide the temporal logic specifications against which the software will be tested and the abstract description of the input domain.

Posted in: Briefs, Information Sciences, Failure analysis, Mathematical models, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Test procedures

Rover Wheel-Actuated Tool

A report describes an interface for utilizing some of the mobility features of a mobile robot for general-purpose manipulation of tools and other objects. The robot in question, now undergoing conceptual development for use on the Moon, is the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) rover, which is designed to roll over gentle terrain or walk over rough or steep terrain. Each leg of the robot is a six-degree-of-freedom generalpurpose manipulator tipped by a wheel with a motor drive. The tool interface includes a square cross-section peg, equivalent to a conventional socket-wrench drive, that rotates with the wheel. The tool interface also includes a clamp that holds a tool on the peg, and a pair of fold-out cameras that provides close-up stereoscopic images of the tool and its vicinity. The field of view of the imagers is actuated by the clamp mechanism and is specific to each tool. The motor drive can power any of a variety of tools, including rotating tools for helical fasteners, drills, and such clamping tools as pliers. With the addition of a flexible coupling, it could also power another tool or remote manipulator at a short distance. The socket drive can provide very high torque and power because it is driven by the wheel motor.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Wheels, Terrain, Tools and equipment, Robotics, Motor-in-wheel drives

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