Reliability in digital systems with asymmetrical failure modes
Digital network reliability with redundancy to mask logic modules failure for asymmetric failure modes
Meisel, W. S.↗
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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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On the structure of fault tolerant sequential machines
Permanent memory faults effects on sequential machines finite-state behavior, considering masking role in synthesis of fault-tolerant sequential networks
Meyer, J. F.↗
Diagnostic capability added to digital events evaluator
Digital events evaluator reviews events preceding system malfunction and automatically prints out most probable cause of problem. Analysis is performed by comparing input data with nominal values stored in tables. Each table has associated system mask to restrict comparison to preselected critical parameters within a given system.
Frasketi, A. S.↗
Computer-aided design of large-scale integrated circuits - A concept
Circuit design and mask development sequence are improved by using general purpose computer with interactive graphics capability establishing efficient two way communications link between design engineer and system. Interactive graphics capability places design engineer in direct control of circuit development.
Schansman, T. T.↗
High resolution developing of photosensitive resists Patent
Composition and process for improving definition of resin masks used in chemical etching
Taylor, C. J.↗
Coded scanning of optical images
Coded mask for improved signal to noise ratio in scanning optical systems
Helm, H. A.↗
Fault tolerant sequential machines
Memory cell fault tolerant sequential machine synthesis, considering masking feasibility and lower bounds on minimum redundancy
Meyer, J. F.↗
Piezoelectric transducer mosaic
Crystal substrate is used to form a transducer mosaic by employing single X-cut crystal and transferring desired pattern from stainless steel mask. Result is a less tedious and costly method of producing a mosaic of matched crystals having the same fundamental frequency.
Haborak, R. C.↗
Improved photoetching fabrication method
Photoetching method producing well-defined lines with minimum undercutting was developed for etching coolant passages in nickel sheet. Phosphate coating is applied over conventional silver plate maskant and phosphoric acid solution is used to remove silver maskant. Phosphoric acid prevents etching of silver edges and mask has sharply-defined lines.
Kistler, C. L.↗
Spaceborne computer executive routine functional design specification. Volume 1: Functional design of a flight computer executive program for the reusable shuttle
A flight computer functional executive design for the reusable shuttle is presented. The design is given in the form of functional flowcharts and prose description. Techniques utilized in the regulation of process flow to accomplish activation, resource allocation, suspension, termination, and error masking based on process primitives are considered. Preliminary estimates of main storage utilization by the Executive are furnished. Conclusions and recommendations for timely, effective software-hardware integration in the reusable shuttle avionics system are proposed.
Curran, R. T.↗
Determination of atmospheric structure function by using a single coherent detector
A technique is described and analyzed for using the single beam laser receiver to measure the wave structure function of atmospheric turbulence. The measurement procedure is as follows: first, the telescope aperture is masked with an opaque screen having two small holes; one hole is covered and the output of the laser receiver is measured; finally, the output of the laser receiver is measured with both holes uncovered. By repeating these measurements for different hole separations, the wave structure function can be derermined.
Lang, R. H.↗
Study of structural behavior of thin films
The work directed towards developing methods of increasing the strength of thin boron films is reported. The program was divided into two main parts. The first involved the improvement of methods for the measurement of the strength of thin films. The second was a study of the effect of condensation of deposition temperature on the strength of the films. Techniques were developed for depositing boron films onto both sides of thin titanium and tantalum foils. Small dogbone sections of boron were made by masking. Strain gauges were then mounted on these to measure failure strains when the films were loaded in tension. Test results were consistent with those obtained by flexure tests. The most important flaws in the boron films appeared to have been generated by either small globules of boron ejected from the melt or small particles (possibly boron dust) on the substrate prior to deposition.
Feakes, F.↗
Tolerance to external breathing resistance with particular reference to high inspiratory resistance
The ability of men to exercise while breathing through graded inspiratory resistances was studied in order to define acceptable respiratory mouthpiece assembly standards. Experimental results with subjects wearing breathing masks and walking for 30 min on treadmills were used to calculate expiratory work rates. It is concluded that the airflow must be appropriate to the upper limit of minute ventilation likely to be encountered in the men wearing the apparatus.
Bentley, R. A.↗
Twisted, multifilament Nb3Sn superconductive ribbon
An experimental study of superconductor stabilization has resulted in the successful application of the concepts of filamentary structure and conductor twist to Nb3Sn ribbon. The Nb3Sn is formed in parallel, helical paths, which are continuous around the ribbon. Short lengths (12-18cm) of 1.27 cm wide superconductive ribbon were produced. The filamentary and twist characteristics are incorporated in the ribbon by means of an inert mask formed on the ribbon surface early in the fabrication process. Diffusion reaction of the niobium and tin is prevented at the filament boundaries. Described are the conductor methods of fabrication, and test results obtained. The technology required to adapt the processes for the production of long lengths of ribbon is available.
Coles, W. D.↗
The nature of Becklin's star.
The IR point source in the Orion Nebula commonly known as Becklin's star appears to be exceptional because of its extreme colors and the lack of any associated optical object. Characteristics of the spectrum of Becklin's object are examined. It is found that the spectrum is consistent with that of a highly reddened early-type supergiant, in which weak absorption has been masked by low resolution.
Penston, M. V.↗
Doubly multiplexing dispersive spectrometer.
Description of a spectrometer that incorporates 19 entrances and 19 exit slots. The instrument's dual capability to perform either one-dimensional imaging or alternately to give a spectrum with a high SNR over the entire source is shown. The instrument operates in the Littrow mode at f/8. The slot width and length for each mask are 0.625 and 3.5 mm, respectively, giving a total aperture length of 12.1 mm. The corresponding resolving power at 1.7 microns is 230.
Phillips, P. G.↗
Rocket spectroscopy of zeta Orionis.
Analysis of a spectrum of zeta Ori extending from 922 to 1453 A with approximately 0.8 A resolution recorded at rocket altitudes. All lines used in existing models of stellar atmospheres appear in the recorded spectrum with the exception of those masked by telluric N2 or strong P Cygni-type profiles and by an O V line at 1371.29 A. Fifteen multiplets of subordinate lines have been reliably identified, indicating an approximate range of excitation from 0 to 50 eV. Transitions in C III (1176 A), N III (991 A), N V (1239, 1243 A), O VI (1032, 1038 A), Si IV (1394, 1403 A), S IV (1063, 1074 A), and S VI (933, 944 A) have been observed as P Cygni-type profiles presumably arising in a circumstellar envelope. The degree of ionization, transitions present, and mean radial velocities are all consistent with viewing the envelope as a hot (about 100,000 K), rarefied plasma in which collisional ionization is important. Interstellar lines in C I (1277, 1280 A), C II (1036, 1334 A), N I (1134-1135 A), N I (1200-1201 A), N II (1084-1086 A), O I (1302, 1305 A), Si II (1190, 1193 A), Si II (1260 A), and Si II (1304 A) have been definitely identified. Other transitions in Ar II, S I, C I, and Fe II are tentatively identified. The equivalent width of the L alpha line is found to be 10.4 plus or minus 1.6 A, corresponding to a columnar density of 2.0 plus or minus 0.7 x 10 to the 20th per cu cm.
Smith, A. M.↗
Hyperfine structure of excited states and quadrupole moment of Ne-21 using laser-induced line-narrowing techniques.
Observation results are presented on the optical hyperfine structure in Ne-21 obtained with the aid of laser-induced line-narrowing techniques. The output from a long stabilized single-mode 1.15-micron He-Ne laser focused into an external sample cell containing Ne-21 was used in implementing these techniques. Their applicability is demonstrated for optical hyperfine structure observation in systems whose features are ordinarily masked by Doppler broadening.
Ducas, T. W.↗