Recent results concerning a graphical test for checking the stability of a linear time-invariant system.
Explore the source record for details and available documents.
Callier, F. M.↗
SEARCH · Search NASA
Results for “Checking”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Dual stage check valve
A dual stage seat valve head arrangement is described which consists of a primary sealing point located between a fixed orifice seat and a valve poppet, and a secondary sealing point between an orifice poppet and a valve poppet. Upstream of the valve orifice is a flexible, convoluted metal diaphragm attached to the orifice poppet. Downstream of the valve orifice, a finger spring exerts a force against the valve poppet, tending to keep the valve in a closed position. The series arrangement of a double seat and poppet is able to tolerate small particle contamination while minimizing chatter by controlling throttling or metering across the secondary seat, thus preserving the primary sealing surface.
Whitten, D. E.↗
Modeling of a bubble-memory organization with self-checking translators to achieve high reliability.
Study of the design and modeling of a highly reliable bubble-memory system that has the capabilities of: (1) correcting a single 16-adjacent bit-group error resulting from failures in a single basic storage module (BSM), and (2) detecting with a probability greater than 0.99 any double errors resulting from failures in BSM's. The results of the study justify the design philosophy adopted of employing memory data encoding and a translator to correct single group errors and detect double group errors to enhance the overall system reliability.
Bouricius, W. G.↗
Computer checking of rotational line intensity factors for diatomic transitions.
Previously published analytical formulae for the rotational line intensity factors of diatomic molecules have been compared with results from a comprehensive computer program, which determines numerical intensity factors for both spin-allowed and spin-forbidden electric and magnetic dipole transitions in diatomic molecules. The comparison uncovered several typographical errors and a few algebraic errors in the published formulae. The changes required in the formulae to give agreement with the results from the computer program are tabulated.
Whiting, E. E.↗
Design criteria monograph for pressure regulators, relief valves, check valves, burst disks, and explosive valves
Monograph reviews and assesses current design practices, and from them establishes firm guidance for achieving greater consistency in design, increased reliability in end product, and greater efficiency in design effort. Five devices are treated separately. Guides to aid in configuration selection are outlined.
Source record↗
Pocket gauge for checking insert clocking of multipin circular connectors
Prototype gauge has been constructed of heavy clear plastic with engraved degree lines, numerals, and alignment lines. With suitable modification, gauge can be mass produced. It could be marketed directly to users or to manufacturers of circular multipin connectors.
Billmeyer, E.↗
Checking the statistical theory of liquids by ultraacoustic measurements
The manner of theoretically obtaining radial distribution functions 9(r) for n-hexane as a function of temperature is described. With the aid of function g(r) the coefficient of dynamic viscosity and the coefficient of volumetric viscosity for temperatures ranging from 213 K to 273 K were calculated. With the aid of the two coefficients of viscosity the coefficient of absorption of ultrasounds in n-hexane referred to the square of the frequency was determined. The same values were measured experimentally. Comparison of theory with experiments resulted in satisfactory agreement.
Dima, V. N.↗
A dynamic pressure generator for checking complete pressure sensing systems installed on an airplane
A portable dynamic pressure generator, how it operates, and a test setup on an airplane are described. The generator is capable of providing a sinusoidal pressure having a peak-to-peak amplitude of 3.5 N/sq cm (5 psi) at frequencies ranging from 100 hertz to 200 hertz. A typical power spectral density plot of data from actual dynamic pressure fluctuation tests within the air inlet of the YF-12 airplane is presented.
Demarco, D. M.↗
Check out of rebuilt optical cross-beam units
Preliminary evaluations of limited cross beam data taken with the rebuilt optical cross beam units at the Gun Barrel Hill Test Site of ESSA are presented. The evaluations were made using the analogue Princeton Time Correlator. A study of these evaluations indicates that the rebuilt units are performing satisfactorily. However, there are indications that, in order to obtain useful information from the cross-correlations, it is essential to make judicious choices of computation time and frequency band pass filtering for the analysis of the data.
Huff, L. L.↗
Checking the parameters of AFS in spacecraft in flight
The use of elements for remote testing of matching of on-board spacecraft antennas, required by the need to receive timely telemetry information on the quality of operation of antenna-feeder systems (AFS) during long flights, is discussed. Information on the traveling wave ratio deficiency to the AFS allowed improvement of quality and reliability of communications with spacecraft and developed telemetric information on the matching of on-board antennas, the efficiency of the feeder system and power of transmitters during long flights.
Vlasov, Y. A.↗
Compatibility check of measured aircraft responses using kinematic equations and extended Kalman filter
An extended Kalman filter smoother and a fixed point smoother were used for estimation of the state variables in the six degree of freedom kinematic equations relating measured aircraft responses and for estimation of unknown constant bias and scale factor errors in measured data. The computing algorithm includes an analysis of residuals which can improve the filter performance and provide estimates of measurement noise characteristics for some aircraft output variables. The technique developed was demonstrated using simulated and real flight test data. Improved accuracy of measured data was obtained when the data were corrected for estimated bias errors.
Klein, V.↗
Curve tracer checks CMOS IC's
Conventional transistor curve tracer can speed up failure analysis of CMOS integrated circuits by displaying transfer characteristics while device is subjected to vibration or environmental testing. Failures that show up as change in threshold voltage or transfer characteristics are quickly detected.
Kizer, F.↗
NORCK: A NASTRAN module to check input data and element geometry
NORCK, a direct matrix abstraction module, was written which allows the user the ability to define error limits for finite element geometry and properties within the solution flow, and to find these errors before the more expensive parts of the analysis are run.
Zemer, D. T.↗
Computing with impure numbers - Automatic consistency checking and units conversion using computer algebra
The computer algebra language MACSYMA enables the programmer to include symbolic physical units in computer calculations, and features automatic detection of dimensionally-inhomogeneous formulas and conversion of inconsistent units in a dimensionally homogeneous formula. Some examples illustrate these features.
Stoutemyer, D. R.↗
Checking weld penetration
Fused wire in weld root area verifies weld penetration in electron-beam-welded joints. Method could be used in automotive, aircraft, and machinery manufacturing when electron-beam-welds cannot be inspected ultrasonically.
Macfarlane, D. I.↗
Ultrasonic grating checks electron-beam welds
Remote inspection technique uses reflectance of ultrasonic waves from machined steps in root area of electron beam welds to indicate sound or faulty welds.
Mitchell, H. A.↗
Microcomputer Checks Butt-Weld Accuracy
Electrical gage and microcomputer eliminate time-consuming manual measurements. Alinement and angle of plates on either side of butt weld are measured and recorded automatically by hand-held gage and desk-top microcomputer. Gage/micro-computer quickly determine whether weld is within dimensional tolerances or whether reworking is needed. Microcomputer prints out measurements while operator moves gage from point to point along weld. Out-of-tolerance measurements are marked by an asterisk on printout.
Clisham, W.↗
Eddy-Current Meter Would Check Weld Wire Online
Simple Technique samples an entire spool of welding wire to test for contamination or unauthorized filler wire. Since unit monitors entire length of wire used in welding, completed welds need not be inspected individually. Technique would save time, avoiding human interface and production delays.
Bailey, G. R.↗