Special Coverage

Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
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
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines

Predicting Stresses in Thermal-Barrier Coatings

Creep, oxidation, differential thermal expansion, and interface roughness are taken into account.

A methodology for predicting stresses and the resultant cracking in plasma-sprayed thermal-barrier coatings (TBCs) has been developed. The methodology is built around a computer code that implements a finite-element model that simulates the evolution of stresses, strains, and related phenomena in a TBC. The economic and technological value of the methodology lies in its potential to provide a more systematic basis for designing reliable and durable TBCs for advanced gas turbine engines by reducing the amount of time-consuming empirical testing needed to assess alternative TBC designs.

Posted in: Briefs, TSP, Materials, Finite element analysis, Coatings Colorants and Finishes, Coatings, colorants, and finishes

Enhancing the Removal of Chlorocarbons From Groundwater

Sonication apparently removes corrosion products that inhibit dechlorination.

Experiments have shown that ultrasound could be an effective means of enhancing the removal of chlorinated hydrocarbon contaminants from groundwater by the zero-valent-metal treatment process. This process, which has been a subject of research in recent years, is attractive because it does not involve above-ground treatment or the use of pumps, and because the materials needed to effect treatment are safe and relatively inexpensive.

Posted in: Briefs, TSP, Materials, Hydrocarbons, Water reclamation

Magnetic/Extendible Boom Mechanism for Docking of Spacecraft

Docking loads can be smaller than those of prior mechanisms.

The magnetic/extendible boom docking aid is an improved mechanism that enables two spacecraft to capture and structurally mate with each other without inducing the large (and frequently excessive) loads encountered in docking by use of prior docking mechanisms. The capability afforded by this mechanism should prove invaluable when applied to the International Space Station. This mechanism is relatively simple to construct, easily integrable into pre-existing docking hardware, and highly reliable.

Posted in: Briefs, Mechanical Components, Mechanics, Spacecraft

Vapor-Compression Solar Refrigerator Without Batteries

Practical refrigeration is powered by an environmentally benign source.

A solar-powered vapor-compression refrigeration system developed for Johnson Space Center operates without batteries. The design of this system will make the cost of solar-powered refrigeration systems competitive and enable the use of such systems in long-distance spaceflights, military field operations, and other situations in which electric power for conventional refrigerators and freezers is unavailable.

Posted in: Briefs, Mechanical Components, Mechanics, Electric power, Solar energy

Thermal-Stress Technique for Cutting Thin Glass Sheets

Highly localized heating generates highly localized stresses.

A technique based on the generation of highly localized thermal stresses has been devised as a means of cutting both flat and curved glass sheets of thicknesses between 30 and 600 µm. The technique is reliable, accurate, and economical. The technique can be used, for example, to cut thin glass sheets for microscope slides and for covers on laptop-computer displays and other flat-panel displays.

Posted in: Briefs, Manufacturing & Prototyping, Thermodynamics, Thermodynamics, Cutting, Glass

Microwave-Sterilizable Access Port

Materials can be transferred into and out of closed bioreactors without contamination.

The microwave-sterilizable access port is an apparatus that functions in a simple, quick, and reliable manner to reduce significantly the risk of contamination during transfer of materials into or out of bioreactors or other microbially vulnerable closed systems. A major improvement over equipment developed previously for the same purpose, this apparatus can be expected to increase confidence in the microbial integrity of samples taken from closed systems. In tests, the original model of this apparatus exceeded expectations: Although it was rigorously challenged by a variety of microorganisms (e.g., C. albicans, A. niger, S. faecalis, E. coli, K. terrigena, Ps. cepacia, B. pumilus, B. stearothermophilus), it performed very well. The apparatus is easily adaptable to applications in cell culture and tissue engineering, and to applications in the production of diverse products that could include foods, drugs, bottled water, soft drinks, and fruit juices. By ensuring that sterilization can be achieved simply, reliably, and quickly, the microwave-sterilizable access port will facilitate collection of samples, delivery of nutrients, and harvesting of products, all without the potential for contamination of the experimental or production systems, samples, or the environment.

Posted in: Briefs, Bio-Medical, Medical, Test equipment and instrumentation

Treatment With Ferrates Eliminates DNA and Proteins

Water and perhaps air can be cleansed of microbiological (probably including viral) contamination.

Ferrate (VI) salts have been proposed for use in sterilizing water (perhaps also in sterilizing air). The iron in ferrate (VI) salts is in its highest oxidation state (VI), and these salts are extremely strong oxidants. In laboratory experiments, it was shown that treatment of DNA solutions with micromolar concentrations of potassium ferrate (VI) irreversibly inhibits further DNA polymerization and polymerase-chain-reaction (PCR) synthesis. Such treatment does not produce any toxic wastes; instead, what remains after treatment are iron ions, which can be recycled and which, in some applications, are useful as nutrients.

Posted in: Briefs, TSP, Bio-Medical, Medical, Research and development, Iron

All-Pressure Fluid-Drop Model Applied to a Binary Mixture

A report presents a computational study of the subcritical and supercritical behaviors of a drop of heptane surrounded by nitrogen, using the fluid-drop model described in "Model of a Drop of O2 Surrounded by H2 at High Pressure" (NPO-20220) and "The Lewis Number Under Supercritical Conditions" (NPO-20256), NASA Tech Briefs, Vol. 23, No. 3 (March 1999), pages 66-70. In this model, the differences between subcritical and supercritical behaviors are identified with length scales. The report compares results of the computations with data from microgravity experiments on large drops at temperatures and pressures in the sub- and supercritical regimes.

Posted in: Briefs, TSP, Physical Sciences, Computational fluid dynamics, Measurements, Test procedures

Validation of All-Pressure Fluid-Drop Model

A report presents a computational study of the subcritical and supercritical behaviors of a drop of heptane surrounded by nitrogen. The subject matter is basically same as that of the report described in the preceding article, except that the Lewis-number issue is not addressed in detail; however, this article presents the full set of equations which lack in the former. As in the preceding case, the results of the computations are compared with data from microgravity experiments on drops of heptane evaporating in nitrogen at temperatures and pressures in the sub- and supercritical regimes, and conclusions are drawn regarding the accuracy of (1) the mathematical model used in the present study and (2) the limitation on accuracy of a traditional model (known as the d2 law) at supercritical pressures. The conclusions stated in the report are essentially a subset of the conclusions stated in the report described in the preceding article.

Posted in: Briefs, TSP, Physical Sciences, Mathematical models

Generating Commands for the Mars Polar Lander Robotic Arm

A report discusses the use of the Web Interface for Telescience (WITS) for visualization and command sequence generation in the Mars Polar Lander (MPL) mission. WITS, which has been described in prior articles in NASA Tech Briefs, is an Internet-based software system that enables geographically dispersed scientists and engineers to participate in sequence generation for planetary lander and rover missions. Public outreach versions of WITS enable the general public to use WITS to view mission images and plan and simulate their own missions. WITS enables scientists to view mission data and generate command sequences from their home institutions, making it unnecessary for them to travel to a mission control center to participate in the mission. The present report describes how WITS fits in the MPL mission operations architecture and how it was used for Robotic Arm and Robotic Arm Camera sequence generation.

Posted in: Briefs, TSP, Information Sciences, Architecture, Communication protocols, Electronic control systems, Architecture, Communication protocols, Electronic control systems, Robotics, Spacecraft

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