Combustor liner film cooling in the presence of high free-stream turbulence
Gas turbine combustor liner film cooling for slot geometries in presence of high free stream turbulence
Juhasz, A. J.↗
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Detection of several non-protein amino acids in the presence of protein amino acids
Nonproteins detection in presence of protein amino acids with Beckman analyzer chromatograms
Shapshak, P.↗
Shock tube investigation of bromine dissociation rates in the presence of helium, neon, argon, krypton, and xenon
Bromine dissociation rates in presence of He, Ne, Ar, Kr and Xe, determining rate constant expressions from light absorption measurements behind incident shock waves
Warshay, W.↗
Lorentz transformations in the presence of a uniform gravitational field.
This article describes a Lorentz-like transformation between a fixed frame and an inertial frame that is free falling due to the presence of a uniform gravitation field. The application to the clock paradox problem and some connections with similar works are also discussed.
Broucke, R.↗
Detection of non-protein amino acids in the presence of protein amino acids. II.
Studies conducted with the JEOL 5AH amino acid analyzer are described. This instrument makes possible the programming of the chromatographic process. Data are presented showing the separations of seventeen non-protein amino acids in the presence of eighteen protein amino acids. It is pointed out that distinct separations could be obtained in the case of a number of chemically similar compounds, such as ornithine and lysine, N-amidino alanine and arginine, and iminodiacetic acid and S-carboxymethyl cysteine and aspartic acid.
Shapshak, P.↗
Space shuttle: Preliminary pressure distributions on the 049 orbiter, orbiter in presence of H/O tank and orbiter in launch configuration
The 049 orbiter and launch configurations were tested in a trisonic wind tunnel to obtain preliminary loads information on the orbiter alone, orbiter in presence of the H/O tank and orbiter in the full launch configuration. The orbiter consisted of the baseline 049 double-delta wing, twin vertical stabilizers, seven degrees of dihedral and included abort rockets. The orbiter was mounted at minus 1.50 degree of incidence (fuselage centerline relative to H/O tank centerline) in the launch configuration. The solid rocket motors were mounted at a radial location of 21 degrees from the horizontal centerline of the H/O tank. The test was conducted over a Mach number range of 0.6 to 4.96. Nominal angle of attack and angle of sideslip ranges of minus 6 to plus 6 degrees were tested. In addition, the orbiter alone was tested over an angle of attack range of minus 6 to plus 26 degrees.
Hamilton, J. T.↗
Effects of certain control-system nonlinearities on stability and pointing of an attached double-gimbal experiment package in presence of random crew-motion disturbances
The effects of two types of control-system nonlinearities, sensor deadband and actuator breakout torque, on the pointing capability of a Apollo Telescope Mount (ATM) double-gimbal experiment isolation and control system are investigated. A composite structural model of a flexible experiment package connected through frictionless double gimbals to a flexible carrier vehicle is used for this investigation. Contributions of the primary carrier control system to experiment pointing are neglected. Pointing errors onboard the experiment package due to random crew-motion input into the carrier vehicle are computed. A stability investigation is performed to verify control-system stability with nominal nonlinearities and gains. Indications are that there is no stability problem due to the nonlinearities. A nonlinearity sensitivity study is carried out to determine the effects on pointing accuracy. Its results indicate that nominal ATM control system nonlinearities limit the pointing accuracy to approximately 0.4 arc second in the presence of crew motion. Methods of reducing the error to less than 0.1 arc second are discussed.
Shaughnessy, J. D.↗
A model for the pressure excitation spectrum and acoustic impedance of sound absorbers in the presence of grazing flow
The acoustic impedance of sound absorbers in the presence of grazing flow is essential information when analyzing sound propagation within ducts. A unification of the theory of the nonlinear acoustic resistance of Helmholtz resonators including grazing flow is presented. The nonlinear resistance due to grazing flow is considered to be caused by an exciting pressure spectrum produced by the interaction of the grazing flow and the jets flowing from the resonator orifices. With this exciting pressure spectrum the resonator can be treated in the same manner as a resonator without grazing flow but with an exciting acoustic spectrum.
Rice, E. J.↗
Dipole receiver characteristics in the presence of sea water
The receive properties for a dipole in the presence of sea water were obtained by solving integral equations for currents along the unloaded dipole and its image. For dipoles of 0.1 wavelength or higher above the sea surface, the performance resembled that of a dipole over a perfectly conducting plane; for dipoles within 0.1 wavelength above the sea surface, the relative gain dropped in about the same proportion as the relative reduction in the strength of the resultant electric field. An insulated wavelength/2 dipole with a conjugate load matched in free space had a relative power gain of 17 db below isotropic at the sea surface.
Kao, P. S.↗
Thoria stability in TD-NiCr at high temperatures in the presence of chromium in solution.
Study of the influence of chromium in solid solution on the coarsening of ThO2 in TD-NiCr. Comparisons were made of ThO2 coarsening in chromium-free TD-Ni and in TD-NiCr, which is known to be low in Cr2O3 as a contaminant. The results of these comparisons indicate that the presence of 20% Cr in solid solution in a nickel-base alloy does not lead to a more rapid coarsening of ThO2 at temperatures of at least 2462 deg F (1350 deg C).
Dalal, H.↗
Cracking and reformation of saturated hydrocarbons by ultrasound in the presence of water
The exposure of saturated hydrocarbons to ultrasound (800 kHz, 6 W/sq cm) in the presence of water results in: (1) cleavage of the carbon chain, producing saturated and unsaturated hydrocarbons with a lower number of carbons than the initial hydrocarbon (cracking); and (2) recombination after cleavage, producing saturated and unsaturated hydrocarbons with a higher number of carbons than the initial hydrocarbon (reformation). The addition of argon facilitates these phenomena. The effects are attributed to a homolytic (radical) mechanism occurring within the cavitation bubbles under the effects of microsparks.
Prudhomme, M. R. O.↗
Identification of aircraft stability and control derivatives in the presence of turbulence
A maximum likelihood estimator for a linear system with state and observation noise is developed to determine stability and control derivatives from flight data obtained in the presence of turbulence. The formulation for the longitudinal short-period mode is presented briefly, including a special case that greatly simplifies the problem if the measurement noise on one signal is negligible. The effectiveness and accuracy of the technique are assessed by applying it first to simulated flight data, in which the true parameter values and state noise are known, then to actual flight data obtained in turbulence. The results are compared with data obtained in smooth air and with wind-tunnel data. The complete maximum likelihood estimator, which accounts for both state and observation noise, is shown to give the most accurate estimate of the stability and control derivatives from flight data obtained in turbulence. It is superior to the techniques that ignores state noise and to the simplified method that neglects the measurement noise on the angle-of-attack signal.
Iliff, K. W.↗
Monitoring the presence of foreign bodies in the equipment
The methods for monitoring the presence of foreign bodies in radio electronic equipment are discussed. Descriptions of the structural design under the operating principle of the device for detecting foreign bodies weighing to 0.0026 grams are given.
Breslavets, A. V.↗
The possible presence of C2 lines in sunspot spectra
Indirect evidence against the presence of C2 lines in umbral spectra is discussed. The dominant role of CO in the molecular equilibrium of C at umbral temperatures ensures that CN, CH and C2 lines are formed in the same atmospheric regions. Observations of CN and CH umbral lines are in good accord with predictions based on accepted umbral model atmospheres. This implies that C2 must follow the predictions and that it is too weak to contribute to the umbral spectrum. C2 lines in the photosphere and penumbrae are in excellent quantitative agreement with predictions. Additional tests are proposed.
Lambert, D. L.↗
Lunar orbit determination in the presence of unmodeled accelerations
A technique for estimating the state of an artificial satellite in the presence of unmodeled accelerations is presented. The unmodeled acceleration is approximated by a first-order Gauss-Markov sequence which can be separated into a timewise-correlated component and a purely random component. Using this approximation, a sequential procedure for estimating the position, velocity, and the unmodeled acceleration is developed. The method is evaluated by reducing range-rate observations obtained by tracking the Apollo 10 and 11 spacecraft during the lunar-orbit phase of the mission. Numerical results are presented which show that the observation residual pattern lies within the observation noise standard deviation. The values of the estimated components of the unmodeled acceleration are repeatable from orbit to orbit within a given mission and from mission to mission when the same ground track is covered. Finally, the variation in the radial component of the unmodeled acceleration shows a high correlation with the reported location of the lunar surface mascons.
Ingram, D. S.↗
Numerical evaluation of electromagnetic fields due to dipole antennas in the presence of stratified media
Two numerical methods are used to evaluate the integrals that express the em fields due to dipole antennas radiating in the presence of a stratified medium. The first method is a direct integration by means of Simpson's rule. The second method is indirect and approximates the kernel of the integral by means of the fast Fourier transform. In contrast to previous analytical methods that applied only to two-layer cases the numerical methods can be used for any arbitrary number of layers with general properties.
Tsang, L.↗
Unified approach to aerodynamic sound generation in the presence of solid boundaries
A general equation governing aerodynamic sound generation in the presence of solid boundaries is derived. It is shown that all the theories in the literature appear as special cases of this general equation. Derived special equations for propeller and fan noise are likewise shown to be more general than the conventional equations in that they make allowance for variation in retarded time over the blade surfaces.
Goldstein, M.↗
Analysis of strip antennas in the presence of a dielectric inhomogeneity
Moment method solutions are considered for treating the problem of wire antennas in the presence of an arbitrary dielectric inhomogeneity. In the first method, the current on the wire and the electric field intensity in the inhomogeneity are treated as independent unknowns, while in the second and third methods they are treated as dependent unknowns. The third method is applied to the problem of strip antennas in an electrically thin dielectric slab. Numerical results are presented, and are in good agreement with measurements and previous calculations.
Newman, E. H.↗