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Nanocomposite Strain Gauges Having Small TCRs

Usefully large gauge factors and acceptably small drifts should also be attainable. Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500°F (about 816°C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate strain-gauge materials having TCRs as small as possible so as to minimize apparent strain.

Posted in: Briefs, TSP, Materials

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Quick-Connect Windowed Non-Stick Penetrator Tips for Rapid Sampling

Standard penetrator sampling systems were designed in order to allow for sampling via penetrators to produce a full set of sample acquisitions including volatile liquids, fine powders, and solid fragments. A gravity harpoon sampler has been designed with a removable tip and a quick coupling. The separation allows for sample handling and eliminates sample cross-contamination. Also, this design allows for multiple use of the penetrator body, which is the largest and heaviest part of the penetrator, while allowing for multiple changes of the light-mass, penetrator tip to avoid sample cross-contamination. The penetrator tip design has been improved by adding a spring trap to retain the sample, as well as a means for connecting to a quick coupling. Quick connect tips have been demonstrated in a sample handling carousel. The penetrator was released and rewound and the tips were released into a circular platter for rotation into instrument stations. The pyro-harpoon sampler was fabricated and tested with a NASA Standard Initiator (NSI) pyrotechnic charge. Initial tests collected cryogenic ice, but removal of the small pyro-harpoon from the ice was difficult. A brass metal sheath was then fitted over the harpoon tip, and removal from the ice was greatly alleviated by leaving the sheath in the ice. Quartz windows in the tips allow direct optical and spectral imaging and gas chromatographymass spectrometer (GCMS) pyrolysis, and were found to survive impact. All systems were successfully tested by dropping into sand and into cryogenic ice. This work was done by Stewart Sherrit, Jack A. Jones, and Mircea Badescu of Caltech for NASA’s Jet Propulsion Laboratory. NPO-45861

Posted in: Briefs, TSP, Mechanical Components

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Prediction of B-Pillar Failure in Automobile Bodies

Simulation of deformation, failure, and contact conditions help determine B-pillar quasi-static strength. The B-pillar is an important load-carrying component of any automobile body. It is a primary support structure for the roof, and is typically a thin-walled, spot-welded, closed-section structure made from high-strength steels. As part of the validation process, the B-pillar can be experimentally loaded at quasi-static rates until failure. The force and displacement of the impactor are measured to get valuable insight into the stiffness characteristics of the structure. During the past two decades, crashworthiness simulation of automotive structures has proven to be remarkably good, largely because the finite element codes being used can accurately predict the plastic bending and stretching deformation mechanisms that occur in stamped metal parts.

Posted in: Briefs, Mechanical Components

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Modeling Unsteady Cavitation and Dynamic Loads in Turbopumps

Magnitudes and frequencies of cavitation-instability-induced loads can be estimated. A computational fluid dynamics (CFD) model that includes representations of effects of unsteady cavitation and associated dynamic loads has been developed to increase the accuracy of simulations of the performances of turbopumps. Although the model was originally intended to serve as a means of analyzing preliminary designs of turbopumps that supply cryogenic propellant liquids to rocket engines, the model could also be applied to turbopumping of other liquids: this can be considered to have been already demonstrated, in that the validation of the model was performed by comparing results of simulations performed by use of the model with results of subscale experiments in water.

Posted in: Briefs, Mechanical Components

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Continuous-Flow System Produces Medical-Grade Water

Pressurized flowing water is heated by absorption of microwave power. A continuous-flow system utilizes microwave heating to sterilize water and to thermally inactivate endotoxins produced in the sterilization process. The system is designed for use in converting potable water to medical-grade water. Systems like this one could be used for efficient, small-scale production of medical-grade water in laboratories, clinics, and hospitals. This system could be adapted to use in selective sterilization of connections in ultra-pure-water-producing equipment and other equipment into which intrusion by microorganisms cannot be tolerated. Lightweight, portable systems based on the design of this system could be rapidly deployed to remote locations (e.g., military field hospitals) or in response to emergencies in which the normal infrastructure for providing medical-grade water is disrupted. Larger systems based on the design of this system could be useful for industrial production of medical-grade water.

Posted in: Briefs, TSP, Medical

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Discrimination of Spore-Forming Bacilli Using spoIVA

Sporulation-specific primers are mixed into a PCR cocktail. A method of discriminating between spore-forming and non-spore-forming bacteria is based on a combination of simultaneous sporulation-specific and non-sporulation-specific quantitative polymerase chain reactions (Q-PCRs). The method was invented partly in response to the observation that for the purposes of preventing or reducing biological contamination affecting many human endeavors, ultimately, only the spore-forming portions of bacterial populations are the ones that are problematic (or, at least, more problematic than are the non-spore-forming portions).

Posted in: Briefs, TSP, Medical

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nBn Infrared Detector Containing Graded Absorption Layer

Potential applications include environmental monitoring, firefighting, law enforcement, and medical diagnosis. It has been proposed to modify the basic structure of an nBn infrared photodetector so that a plain electron-donor-type (n-type) semiconductor contact layer would be replaced by a graded n-type III–V alloy semiconductor layer (i.e., ternary or quarternary) with appropriate doping gradient. The abbreviation “nBn” refers to one aspect of the unmodified basic device structure: There is an electron-barrier (“B”) layer between two n-type (“n”) layers, as shown in the upper part of the figure. One of the n-type layers is the aforementioned photon-absorption layer; the other n-type layer, denoted the contact layer, collects the photocurrent.

Posted in: Briefs, Physical Sciences

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