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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Quantitative models of magnetic and electric fields in the magnetosphere

In order to represent the magnetic field B in the magnetosphere various auxiliary functions can be used: the current density, the scalar potential, toroidal and poloidal potentials, and Euler potentials -- or else, the components of B may be expanded directly. The most versatile among the linear representations is the one based on toroidal and poloidal potentials; it has seen relatively little use in the past but appears to be the most promising one for future work. Other classifications of models include simple testbed models vs. comprehensive ones and analytical vs. numerical representations. The electric field E in the magnetosphere is generally assumed to vary only slowly and to be orthogonal to B, allowing the use of a scalar potential which may be deduced from observations in the ionosphere, from the shape of the plasmapause, or from particle observations in synchronous orbits.

Stern, D. P.↗
NASA NTRS1975

A satellite technique for quantitatively mapping rainfall rates over the oceans

A theoretical model for calculating microwave radiative transfer in raining atmospheres is developed. These calculations are compared with microwave brightness temperatures at a wavelength of 1.55 cm measured on the Nimbus-5 satellite and rain rates derived from WSR-57 meteorological radar measurements. A specially designed ground based verification experiment was also performed wherein upward viewing microwave brightness temperature measurements at wavelengths of 1.55 cm and 0.81 cm were compared with directly measured rain rates.

Wilheit, T. T.↗
NASA NTRS1975

Quantitative determination of stratospheric aerosol characteristics

The author has identified the following significant results. The multiplicative scale factor needed to calibrate the recorded intensity is obtained by fitting the measured curve against a brightness model. The model was converted to the multispectral band scanner signal. Inversion of this measured signature is shown as the profile of attenuation coefficients versus altitude. Because of Gaussian noise, data were not measured directly. Data were fit with two exponential curves, one covering the lower altitude and the other covering the higher altitude. A twenty point curve was derived by selecting a data point and plotting its value from each of twenty adjacent scans. Noise from the lower altitudes was found to be erratic.

Tingey, D. L.↗
NASA NTRS1975

A quantitative magnetospheric model derived from spacecraft magnetometer data

The model is derived by making least squares fits to magnetic field measurements from four Imp satellites. It includes four sets of coefficients, representing different degrees of magnetic disturbance as determined by the range of Kp values. The data are fit to a power series expansion in the solar magnetic coordinates and the solar wind-dipole tilt angle, and thus the effects of seasonal north-south asymmetries are contained. The expansion is divergence-free, but unlike the usual scalar potential expansion, the model contains a nonzero curl representing currents distributed within the magnetosphere. The latitude at the earth separating open polar cap field lines from field lines closing on the day side is about 5 deg lower than that determined by previous theoretically derived models. At times of high Kp, additional high-latitude field lines extend back into the tail. Near solstice, the separation latitude can be as low as 75 deg in the winter hemisphere. The average northward component of the external field is much smaller than that predicted by theoretical models; this finding indicates the important effects of distributed currents in the magnetosphere.

Mead, G. D.↗
NASA NTRS1975

Magnetospheric mapping with a quantitative geomagnetic field model

Mapping the magnetosphere on a dipole geomagnetic field model by projecting field and particle observations onto the model is described. High-latitude field lines are traced between the earth's surface and their intersection with either the equatorial plane or a cross section of the geomagnetic tail, and data from low-altitude orbiting satellites are projected along field lines to the outer magnetosphere. This procedure is analyzed, and the resultant mappings are illustrated. Extension of field lines into the geomagnetic tail and low-altitude determination of the polar cap and cusp are presented. It is noted that while there is good agreement among the various data, more particle measurements are necessary to clear up statistical uncertainties and to facilitate comparison of statistical models.

Fairfield, D. H.↗
NASA NTRS1975

Use of dew-point detection for quantitative measurement of sweating rate

A method of measuring sweat rate (SR) based on detection of dew point (DP) is proposed which has advantages that may be attractive to other laboratories concerned with recording SR from selected areas of skin. It is similar to other methods in that dry gas is passed through a capsule which isolates several square centimeters of skin surface. The difference is in the means of determining how much gaseous water is carried off in the effluent moist gas. The DP detector used is free of the drawbacks of previous devices. DP is obtained through the fundamental technique of determining the temperature at which condensate forms on a mirror. Variations in DP are tracked rapidly, and accurately (+ or - 0.8 C nominal, sensitivity + or - 0.05 C) over a wide range ( -40 C to +50 C) without measurable hysteresis. The detector asembly is rugged and readily opened for cleaning and inspection.

Brengelmann, G. L.↗
NASA NTRS1976

Quantitative bioluminescent detection of bacteria

Phosphoflavins in sample are measured using photobacterial luciferase assay technique for flavin mononucleotide (FMN). Boiling perchloric acid is used to rupture cells to free bound flavin and to hydrolyze flavin adenine dinucleotide to FMN. Base-stabilized water solution of sodium borohydride is used as reactant.

Chappelle, E. W.↗
NASA NTRS1975

Quantitative comparisons of type 3 radio burst intensity and fast electron flux at 1 AU

The flux of fast solar electrons and the intensity of the type 111 radio emission generated by these particles were compared at one AU. Two regimes were found in the generation of type 111 radiation: one where the radio intensity is linearly proportional to the electron flux, and another, which occurs above a threshold electron flux, where the radio intensity is approximately proportional to the 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.

Fitzenreiter, R. J.↗
NASA NTRS1975

The effect of growth phase and medium on the use of the firefly adenosine triphosphate (ATP) assay for the quantitation of bacteria

Luciferase assay for adenosine triphosphate (ATP) was used as a rapid method to determine the number of bacteria in a urine sample after nonbacterial components were removed. Accurate cellular ATP values, determined when bacteria were grown in an environment similar to that in which they were found, were necessary for the calculation of bacterial titer in urine. Cellular ATP values vary depending on the extraction method, the cell growth phase, and cell growth conditions. ATP per cell values of stationary E. coli grown in urine were two times greater than ATP per cell values of cells grown in trypticase soy broth. Glucose and urea were examined as possible components responsible for the cellular ATP variation.

Bush, V. N.↗
NASA NTRS1975

Quantitative determination of stratospheric aerosol characteristics

The author has identified the following significant results. In the S192 data, a peak was apparent in the lower altitudes that was not present in the shorter wavelengths and grew with increasing wavelength beginning with band 7. For ten S192 wavelengths, the relative altitude increment was determined by knowledge of the relative position of the highest point in the scan arc. Using this scheme, results of scaling and inverting data for passes 47 and 61 were put into two models. Each result had three chart representations: (1) limb brightness measurement, (2) attenuation coefficients, and (3) ratio of the aerosol and Rayleigh coefficients to accentuate layers.

Tingey, D. L.↗
NASA NTRS1976

Quantitative observation of light flash sensations experiment MA-106

Light flashes caused by the interaction of cosmic particles with the visual apparatus have been observed by astronauts on all space missions since Apollo 11. This Apollo Soyuz Test Project experiment compared measurements of the observer's visual sensitivity with measurements of the ambient radiation environment and with the frequency and character of the flashes observed. The data obtained reveal a latitude dependence of the frequency of observed flashes. This distribution of flashes is correlated with the distribution of cosmic particles with stopping power greater than 15 keV/ micrometers in the eye. The interaction of dark adaptation, specific ionization, and range of particles in the retina as factors in the visualization of particle passage is discussed.

Budinger, T. F.↗
NASA NTRS1975

Use of LARS system for the quantitative determination of smoke plume lateral diffusion coefficients from ERTS images of Virginia

A technique for measuring smoke plume of large industrial sources observed by satellite using LARSYS is proposed. A Gaussian plume model is described, integrated in the vertical, and inverted to yield a form for the lateral diffusion coefficient, Ky. Given u, wind speed; y sub l, the horizontal distance of a line of constant brightness from the plume symmetry axis a distance x sub l, downstream from reference point at x=x sub 2, y=0, then K sub y = u ((y sub 1) to the 2nd power)/2 x sub 1 1n (x sub 2/x sub 1). The technique is applied to a plume from a power plant at Chester, Virginia, imaged August 31, 1973 by LANDSAT I. The plume bends slightly to the left 4.3 km from the source and estimates yield Ky of 28 sq m/sec near the source, and 19 sq m/sec beyond the bend. Maximum ground concentrations are estimated between 32 and 64 ug/cu m. Existing meteorological data would not explain such concentrations.

Blais, R. N.↗