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NASA NTRS1981

Laboratory tank studies of a single species of phytoplankton using a remote sensing fluorosensor

Phytoplankton were grown in the laboratory for the purpose of testing a remote fluorosensor. The fluorosensor uses a unique four-wavelength dye laser system to excite phytoplankton bearing chlorophyll and to measure the chlorophyll fluorescence generated by this excitation. Six different species were tested, one at a time, and each was grown two to four times. Fluorescence measured by the fluorosensor provides good quantitative measurement of chlorophyll concentrations for all species tested while the cultures were in log phase growth. Fluorescene cross section ratios obtained in the single species tank tests support the hypothesis that the shape of the fluorescence cross section curve remains constant with the species (differences in fluorescence cross section ratios are a basis for determining composition of phytoplankton according to color group when a multiwavelength source of excitation is used. Linear relationships exist between extracted chlorophyll concentration and fluorescence measured by the remote fluorosensor during the log phase growth of phytoplankton cultures tested.

Brown, C. A., Jr.↗

NASA NTRS1980

X-ray properties of quasars

The X-ray properties of 111 catalogued quasars have been examined with the imaging proportional counter on board the Einstein Observatory. Thirty-five of the objects, of redshift between 0.064 and 3.53, were detected as X-ray sources. The 0.5-4.5-keV X-ray properties of these quasars are correlated with their optical and radio continuum properties and with their redshifts and variability characteristics. The X-ray luminosity of quasars tends to be highest for those objects which are bright in the optical and radio regimes and which exhibit optically violent variability. These observations suggest that quasars should be divided into two classes on the basis of radio luminosities, spectra, evolution and underlying morphology and that quasars can make up a significant portion of the diffuse soft X-ray background only if the slope of the optical quasar log N-log S relation is steeper than 2 to m sub b of about 21.5.

Ku, W. H.-M.↗

NASA NTRS1981

Antimony in iron meteorites

Sb concentrations determined by radiochemical neutron activation analysis in 60 iron meteorites range from 0.2 ng/g to 36 microg/g. The meteorites with the highest Sb concentrations are those of the nonmagmatic groups IAB and IIICD, while meteorites with the lowest Sb concentrations are found in groups IVA and IVB. In all groups Sb is positively correlated with Ni; slopes on log Sb vs log Ni plots decrease with increasing Ni. This decrease may reflect an increasing tendency to avoid schreibersite during the analysis of high-Ni meteorites because Sb partitions strongly into schreibersite. It is found that schreibersite from New Westville is enriched in Cr, Ni, Ge, As, Sb, and Au and depleted in Fe, Co, Ir; the Sb content in schreibersite is 540 times higher than the bulk metal value.

Willis, J.↗

NASA NTRS1980

Theory and application of the polarization-albedo rules

The paper reports results of a computer calculation of the scattering of light from porous particulate surfaces such as those of the moon, asteroids, and airless planets. The scattered-light intensity and polarization are computed as a function of phase angle, and plots are constructed corresponding to the observed empirical rules for deducing albedo from the slope, maximum, and minimum of polarization curves. The approximate linearity of these rules on a log-log plot is confirmed for most solar system objects. The theory shows that the albedo vs. polarization plots correspond directly to a plot in two dimensions of the real vs. imaginary index of refraction of these soils, using curved axes.

Wolff, M.↗

NASA NTRS1982

Influence of the number of vehicles in the emergence of sound events on the annoyance expressed - experimental study

The acoustical index leg was studied to determine its accuracy in predicting annoyance from traffic noise. Annoyance was tested in experimental situations where the frequency of the number of heavy vehicles varied from 3 to 30 HV/30 min for different classes of the Leg level at 50, 55, 60 dB(A) of traffic noise. The results showed that: (1) for a constant Leg level the annoyance increases as a function of the number of HV up to a certain threshold at which the annoyance is stabilized; (2) for a constant frequency of passage of HV, the annoyance increases with the Leg level; (3) composite indexes of the type Leg + Log NHV, L1 + EMER or L1 + L10 give a predictive value greater than that of the Leg pr Log nHV taken alone.

Vallet, M.↗

NASA NTRS1981

Balloon material characterization

Experimental data are reviewed to study the state of stress and strain in a typical balloon fabricated from thin polyethylene film. Relaxation tests are conducted over a temperature range of -60 C to 140 C for a constant strain of 1%, and loads measured with the load cell are converted to values of the relaxation modulus. A log-log plot is made of the modulus as a function of time, and the maximum stress is found to occur at times of the order of one-half second. The film behaves as a nonlinear viscoelastic material, and by examining various theoretical relationships of stress and strain with temperature and time histories, a material testing program is developed which yields the necessary data to characterize the film.

Wilbeck, J. S.↗

NASA NTRS1981

The stellar contribution to the galactic soft X-ray background

Log N-log S relations for stars are constructed based on median X-ray luminosities for dF, dG, and dK stars previously reported for the Einstein Observatory/Center for Astrophysics stellar survey and on a detailed X-ray luminosity function derived here for dM stars, and the stellar contribution to the diffuse soft X-ray background is investigated. The principal results are that stars provide approximately 20% of the soft X-ray background in the 0.28-1.0 keV passband and therefore contribute significantly to the soft X-ray background in this energy range (with dM stars constituting the dominant contributing class), and that the stellar contribution to the diffuse X-ray background in the 0.15-0.28 keV passband is less than approximately 3%.

Rosner, R.↗

NASA NTRS1980

Improving the performance of soft decision Viterbi decoding in a non-Gaussian environment through non-linear quantization

The performance of Viterbi decoding in a non-Gaussian environment is investigated using a nonlinear quantization strategy. The channel model consists of a convolutionally encoded BPSK signal transmitted to a satellite where it is corrupted with additive white Gaussian noise and pulsed radio frequency interference (RFI). The resultant signal is then passed through a satellite nonlinearity and transmitted to a ground station where it is coherently detected. Interleaving is assumed in order to make the channel memoryless. The presence of RFI makes the channel statistics non-Gaussian, leading to a nonlinear log-likelihood function. A near optimum quantization scheme is found by maximizing a channel parameter, or by matching the quantizer to the log-likelihood function in a mean square error sense. Bit error rate performance improvement is achieved by using such nonlinear quantization.

Mcgregor, D. N.↗

NASA NTRS1983

The LSS 4300: A hot counterpart of Upsilon Sgr and KS Per?

A number of observations indicate that the star LSS 4300 is a high temperature analog of the hydrogen-deficient binaries upsilon Sgr and KS Per. A preliminary model-atmosphere analysis based on high-dispersion spectra obtained at Kitt Peak and Cerro Tololo yields T(eff) = 14,400 K, log(g) = 1.4, n(H)/n(He) = 0.003, and n(N)/n(C) = 20 (the corresponding values for upsilon Sgr are T(eff) = 10,000 K, log(g) = 1, n(H)/n(He) = 0.0005, and n(N)/n(C) = 20). The optical emission-line spectrum of LSS 4300 is nearly identical to that of upsilon Sgr, including strong, broad H alpha, FeII and Ca II emission. The ultraviolet spectrum of LSS 4300 was observed with IUE, and can be attributed almost entirely to the visible star. The JHKL photometry of LSS 4300 obtained at Cerro Tololo reveals an infrared excess nearly identical to that of upsilon Sgr. It is suggested that LSS 4300, like upsilon Sgr and KS Per, is a close binary system consisting of a helium supergiant of about one solar mass, and a secondary which is overluminous for its mass due to the accretion of matter from the primary, which is undergoing its second mass exchange.

Drilling, J. S.↗

NASA NTRS1983

Film thickness for different regimes of fluid-film lubrication

Mathematical formulas are presented which express the dimensionless minimum film thickness for the four lubrication regimes found in elliptical contacts: isoviscous-rigid regime; piezoviscous-rigid regime; isoviscous-elastic regime; and piezoviscous-elastic regime. The relative importance of pressure on elastic distortion and lubricant viscosity is the factor that distinguishes these regimes for a given conjunction geometry. In addition, these equations were used to develop maps of the lubrication regimes by plotting film thickness contours on a log-log grid of the dimensionless viscosity and elasticity parameters for three values of the ellipticity parameter. These results present a complete theoretical film thickness parameter solution for elliptical constants in the four lubrication regimes. The results are particularly useful in initial investigations of many practical lubrication problems involving elliptical conjunctions.

Hamrock, B. J.↗

NASA NTRS1983

Satellite freeze forecast system. Operating/troubleshooting manual

Examples of operational procedures are given to assist users of the satellites freeze forecasting system (SFFS) in logging in on to the computer, executing the programs in the menu, logging off the computer, and setting up the automatic system. Directions are also given for displaying, acquiring, and listing satellite maps; for communicating via terminal and monitor displays; and for what to do when the SFFS doesn't work. Administrative procedures are included.

Martsolf, J. D.↗

NASA NTRS1982

The IUE spectrum of BD + 39 deg 4926

IUE spectra of the A- or F-type supergiant BD + 39 deg 4926 have been combined with existing optical data. Comparison with model atmospheres yields an effective temperature of 7750 K, gravity log g of 0.5, and a reddening corresponding to E(B-V) of 0.15. The Mg II wavelength 2800 feature was used to estimate the abundance of Mg(+), and the value of log (epsilon (Mg(+)/epsilon (Ca(+)) was found to be about 2.7.

Saha, A.↗

NASA NTRS1982

The effects of C, P, and S on trace element partitioning during solidification in Fe-Ni alloys

Trace and minor element distributions in the iron meteorites are generally ascribed to partitioning during solidification of the parent body core or to partial melting within the parent body. A model involving fractional crystallization is considered. The model cannot account for differences between the measured values for the slopes on the log Ir-log Ni plots and the slopes predicted using experimentally determined distribution coefficients obtained in an investigation conducted by Goldstein and Friel (1978). The model has also other weaknesses. Part of the answer concerning the existing problems was provided by Narayan and Goldstein (1981, 1982). The present investigation is concerned with a further clarification of the effect of the minor elements P, S, and C on the distribution behavior of trace elements. Attention is given to measurements of the distribution coefficients for various elements (Ir, Ge, Ga, Au, Cu, Cr) in the presence of these minor elements.

Willis, J.↗

NASA NTRS1982

Frequency of gamma-ray bursts greater than 3 x 10 to the -6th erg/sq cm

Results are presented for gamma-ray burst observations with the Large Area Sky Survey instrument on HEAO-1. It is noted that during the time HEAO-1 was operational, the instrument detected at least 12 confirmed gamma-ray bursts with intensities greater than 3 microerg/sq cm and identified six additional unconfirmed bursts. The rates of gamma-ray bursts are estimated to be about 125 per yr for intensities greater than 3 microerg/sq cm and approximately 50 per yr for intensities greater than 10 microerg/yr. The data are shown to yield a log N - log S relation for gamma-ray bursts that is consistent with a spherical distribution of sources within the Galaxy and having a broad range of intrinsic luminosities.

Share, G. H.↗

NASA NTRS1982

Derivation of the luminosity of a gamma ray burst

The intrinsic luminosity, erg/s, in a gamma ray burst is calculated using two assumptions: first, the power is independent of the burst duration, and, second, the spatial distribution of the bursters is similar to the spatial distribution of the pulsars. It is found that the experimentally determined distribution of burst durations is significantly biased by the observational selection effects. It is shown that a typical luminosity of 5 x 10 to the 35th erg/s can adequately reproduce the burst (log N, log S) curve, an isotropic latitude distribution, and the experimentally determined distribution of durations.

Higdon, J. C.↗

NASA NTRS1983

Possible evidence for the driving of the winds of hot stars by Alfven waves

Ultraviolet spectra of the supergiants Alpha Cam (09.5 Ia), HD 105056 (ON9.7 Iae), and 15 Sgr (O9.7 Iab) are compared, and it is shown that the terminal outflow velocity, TOV, of HD 105056 is one-half that of the other two stars even though HD 105056 has the highest effective temperature of the three stars. This anomaly, together with the fact that the observed TOV values for early-type stars scatter about an empirical correlation between TOV and log T(eff) by an amount which is larger than the amount expected according to the observational errors in determining TOV and log T(eff), leads to the conclusion that an agent in addition to radiation, Alfven waves, is driving the winds of early-type stars.

Underhill, A. B.↗

NASA NTRS1983

Constraints on gamma-ray bursters from soft X-ray transients

The Columbia Astrophysics Laboratory's Einstein imaging proportional counter database has been searched for possible X-ray counterparts to gamma ray bursts. The limiting sensitivity was about 10 to the 10th erg/sq cm with a total exposure of about 3 x 10 to the 6th s divided among about 1000 1 deg x 1 deg fields. Four events with a pointlike spatial distribution were detected but their extremely soft spectra makes them unlikely candidates for gamma ray burst counterparts. The results are used to place limits on the X-ray and gamma ray luminosity ratio and log(number)N-log(flux)S relation for gamma ray bursts. The constraints placed on models for their origin are commented on.

Helfand, D. J.↗

NASA NTRS1983

A multiwavelength study of the short-period cataclysmic variable V442 Ophiuchi

The results of a program of observations of the cataclysmic variable V442 Oph from UV to IR wavelengths are reported. The observations comprise IUE SWP and LWR-camera spectra from October, 1981; UBVr and R photometry at Manastash Ridge Observatory from August, 1980; UBV photometry and IR measurements at Kitt Peak from July, 1981; and Coudespectroscopy at Mt. Wilson from June, 1980, and at Mt Lemmon from July, 1982. Tables of data, plots of H-alpha and He-II radial velocity, sample spectra, light curves, and a log-log diagram of F(lambda) vs lambda are given. Flux-ratio analysis of the IR data indicates a disk with very little optically thin material anad an outer-edge temperature of about 7920 K. The calculated period (3.37 h) and mass-accretion rate (1 x 10 to the -8th solar mass/yr) are compared to those of similar objects, and V442 Oph is found to be similar in this respect to systems like H2252-035. Its lack of a rotational period and the weakness of the optical and UV line emissions, however, are more like the old nova V603 Aql.

Shafter, A. W.↗