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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Fault tolerance using self-checking building-block computers

The paper attempts to define and characterize a set of VLSI (very large scale integration) building-block circuits which can be used to combine existing microprocessors and memories into a wide variety of fault-tolerant computing systems. Such VLSI circuits would transform fault-tolerant computing into an off-the-shelf technology and enable its routine use for new applications. The self-checking computer module (SCCM) is the basic component out of which fault-tolerant computer systems are constructed. Several fault-tolerant configurations of SCCM are discussed, including the standby redundant uniprocessor, the voted/hybrid uniprocessor, and the distributed computer network.

Rennels, D. A.↗
NASA NTRS1980

Flight manager and check-airman training

An analysis of industry incidents, accidents, and related human factors research is given. The need to develop more effective resource management training for the flight deck crewmembers is discussed with specific emphasis on flight manager and check-airman training.

Carroll, J. E.↗
NASA NTRS1980

Advanced microbial check valve development

A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through the device. The device is equally effective for fluid flow in either direction and its primary method of organism removal is killing rather than filtering. The MCV was successfully developed for the space shuttle to: disinfect fuel cell water; and prevent back contamination of the stored potable water supply. One version of the device consists of a high residual iodinated resin bed that imparts approximately 2 ppm of iodine to the fuel cell water as it flows to the potable water tanks. A second version of the device consists of a low residual iodinated resin bed. One of these low residual beds is located at each use port in the potable water system for the dual purpose of removing some iodine from the potable water as it is dispensed and also to prevent back contamination of the potable supply.

Colombo, G. V.↗
NASA NTRS1980

Improved orthogonality check for measured modes

A method is proposed for performing an orthogonality check for normal modes derived from ground vibration testing. The method utilizes partitioned mass and stiffness matrices for a linear undamped representation of a structure. The normalization of the modes by the proposed method inherently includes the effects of significant displacements which were not measured; and the method may allow the use of fewer measurement points than would be necessary with the conventional method.

Berman, A.↗
NASA NTRS1978

User's manual for large-scale integrated circuit layout check program

A computer program is described that checks for the correctness of chip design layout generated by the Banning Placement Routing Folding program (PRF) by verifying agreement between a specified circuit design and a corresponding computer generated circuit layout as stored on the Artwork (PRF output) tape. An example computer run is included.

Source record↗
NASA NTRS1983

Jig Quickly Checks Connector Pin Alinement

Test jig checks whether pins of connector are within location tolerance. Jig greatly reduces test time. Machined slots on opposite faces of plate form matrix of rectangular windows at intersections. If connector pin is out of alinement, it makes electrical contact with side of window, triggering indicator.

Hall, W. M.↗
NASA NTRS1981

Advanced Microbial Check Valve development

The Microbial Check Valve (MCV) is a flight qualified assembly that provides bacteriologically safe drinking water for the Space Shuttle. The 1-lb unit is basically a canister packed with an iodinated ion-exchange resin. The device is used to destroy organisms in a water stream as the water passes through it. It is equally effective for fluid flow in either direction and its primary method of disinfection is killing rather than filtering. The MCV was developed to disinfect the fuel cell water and to prevent back contamination of stored potable water on the Space Shuttle. This paper reports its potential for space applications beyond the basic Shuttle mission. Data are presented that indicate the MCV is suitable for use in advanced systems that NASA has under development for the reclamation of humidity condensate, wash water and human urine.

Colombo, G. V.↗
NASA NTRS1986

Wind-Tunnel-Model Leak-Checking System

Voice-actuated system allows one operator to do work of three. System uses voice-recognition-and-response unit and graphics terminal to interact with technician and to provide technician visual feedback. Computer-based Leakcheck system allows computer to do more of total work in checking model for leaks to reduce time and manpower required to perform task.

Larson, W. E.↗
NASA NTRS1985

Seismic analysis of the large 70-meter antenna. Part 2: General dynamic response and a seismic safety check

An extensive dynamic analysis for the new JPL 70-meter antenna structure is presented. Analytical procedures are based on the normal mode decomposition which include dumping and special forcing functions. The dynamic response can be obtained for any arbitrarily selected point on the structure. A new computer program for computing the time-dependent, resultant structural displacement, summing the effects of all participating modes, was developed also. Program compatibility with natural frequency analysis output was verified. The program was applied to the JPL 70-meter antenna structure and the dynamic response for several specially selected points was computed. Seismic analysis of structures, a special application of the general dynamic analysis, is based also on the normal modal decomposition. Strength specification of the antenna, with respect to the earthquake excitation, is done by using the common response spectra. The results indicated basically a safe design under an assumed 5% or more damping coefficient. However, for the antenna located at Goldstone, with more active seismic environment, this study strongly recommends and experimental program that determines the true damping coefficient for a more reliable safety check.

Kiedron, K.↗
NASA NTRS1987

In-situ technique for checking the calibration of platinum resistance thermometers

The applicability of the self-heating technique for checking the calibration of platinum resistance thermometers located inside wind tunnels was investigated. This technique is based on a steady state measurement of resistance increase versus joule heating. This method was found to be undesirable, mainly because of the fluctuations of flow variables during any wind tunnel testing.

Daryabeigi, Kamran↗
NASA NTRS1990

Quick Check Of Butt-Weld Alignment

Proposed tool measures alignments of plates before butt-welded. Provides nearly instantaneous check on alignment, thereby facilitating repetitive measurements along length of weld joint. Reduces risk of contamination of weld from dirty measuring tools. Middle photodetector indicates acceptable alignment when position of transmitter fiber preciously matches that of center receiver fiber. If plates offset, other photodetectors signal misalignment.

Smith, Matthew A.↗
NASA NTRS1990

Checking Automated-Welder Programs By Computer

Computer system detects and displays actual and potential errors in programs for computer-controlled electron-beam welder. Uses personal computer, separate from welding computer. Programmed specifically to highlight errors in welding program. Eliminates need for preweld full-power test run reducing checkout time to about half hour. Assures much higher quality, damage-free welding. Used to create and edit new programs for welder. Control computer thereby free for production. Useful for checking programs for such other computer-controlled equipment as inertia welders, robots, machine tools, and heat treaters.

Damicone, L. O.↗
NASA NTRS1989

Solar sensor subsystems alignment check using solar scans for the Halogen Occultation Experiment

The alignment of a dual-axes sun sensor subsystem to a telescope having a multiple sensor subsystem is described. The sun sensor consists of two analog and one digital silicon detectors. The analog detectors are shadow mask type operating in the visible spectrum. The detectors are mounted for azimuth and elevation positioning of biaxial gimbals. The digital detector is a linear diode array that operates at a spectral position of 0.7 micron and is used for elevation positioning. The position signals correspond to relative angles between the sun sensor and the solar disk. These three detectors are aligned on an Invar structure which is mounted to a Cassegrain telescope. This telescope relays solar radiance to an eight channel detector subsystem operating in the infrared range from 2 to 10 microns. The test technique and results to check the boresight alignment of these two subsystems by scanning the solar disk will be reported. The boresight alignment for both the azimuth and elevation axes of the two detector subsystems is verified using this technique.

Jurczyk, S. G.↗
NASA NTRS1992

Calibration Check For Programmed Welding Robot

Preweld calibration check helps to ensure welding torch on computer-controlled welding robot mounted properly, right gas cup selected, and length of extension of electrode adjusted correctly. Performed by operator just before dry run for each set of parts welded. Procedure takes 2 to 3 minutes and enables correction of errors before parts or equipment damaged.

Sliwinski, Karen E.↗
NASA NTRS1993

Self-checking sequential circuit design using m-out-of-n codes

A technique for designing sequential circuits which are totally self-checking for single stuck at faults is presented. This technique uses m-out-of-n codes for state assignments and for output encoding. The next stage logic and the output logic are implemented such that any stuck-at-fault will either create a single bit error or unidirectional multibit error at the output. The technique has been applied to MCNC benchmark circuits and the overhead is estimated.

Busaba, F. Y.↗
NASA NTRS1993

Nonlinear smoothing identification algorithm with application to data consistency checks

A parameter identification algorithm for nonlinear systems is presented. It is based on smoothing test data with successively improved sets of model parameters. The smoothing, which is iterative, provides all of the information needed to compute the gradients of the smoothing performance measure with respect to the parameters. The parameters are updated using a quasi-Newton procedure, until convergence is achieved. The advantage of this algorithm over standard maximum likelihood identification algorithms is the computational savings in calculating the gradient. This algorithm was used for flight-test data consistency checks based on a nonlinear model of aircraft kinematics. Measurement biases and scale factors were identified. The advantages of the presented algorithm and model are discussed.

Idan, M.↗
NASA NTRS1992

Regenerable Microbial Check Valve - Life cycle tests results

Life cycle regeneration testing of the Microbial Check Valve (MCV) that is used on the Shuttle Orbiter to provide microbial control of potable water is currently in progress. Four beds are being challenged with simulated reclaimed waters and repeatedly regenerated. Preliminary results indicate that contaminant systems exhibit unique regeneration periodicities. Cyclic throughput diminishes with increasing cumulative flow. It is considered to be feasible to design a regenerable MCV system which will function without human intervention and with minimal resupply penalty for the 30 year life of the Space Station.

Atwater, James E.↗