Search NASA⌕ Search

SEARCH · Search NASA

Results for “intense”

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.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

The MIT/OSO 7 catalog of X-ray sources - Intensities, spectra, and long-term variability

This paper is a summary of the observations of the cosmic X-ray sky performed by the MIT 1-40-keV X-ray detectors on OSO 7 between October 1971 and May 1973. Specifically, mean intensities or upper limits of all third Uhuru or OSO 7 cataloged sources (185 sources) in the 3-10-keV range are computed. For those sources for which a statistically significant (greater than 20) intensity was found in the 3-10-keV band (138 sources), further intensity determinations were made in the 1-15-keV, 1-6-keV, and 15-40-keV energy bands. Graphs and other simple techniques are provided to aid the user in converting the observed counting rates to convenient units and in determining spectral parameters. Long-term light curves (counting rates in one or more energy bands as a function of time) are plotted for 86 of the brighter sources.

Markert, T. H.↗
NASA NTRS1979

Propagation of a Forbush decrease in cosmic ray intensity to 15.9 AU

By observation of the large Forbush decrease in cosmic-ray intensity of April-May 1978 at heliocentric radial distances of 1.01, 6.97, and 15.91 AU, it is found that the causative magnetized plasma cloud moved outward from the sun at an apparent radial speed of about 960 km/s, independent of radial distance over this range. Recovery from the impulsive decrease in intensity was markedly slower at the larger distances. On the basis of this fact and other considerations, several tentative suggestions are made as to the large-scale nature of Forbush decreases and their relationship to the 11-year solar modulation of galactic cosmic-ray intensity.

Van Allen, J. A.↗
NASA NTRS1979

On nuclear spin statistics in rotational transition intensities in tetrahedral AB4 molecules

A general expression is derived for the integrated intensity of rotational transitions in the vibronic ground state of tetrahedral molecules, taking into account the nuclear spin statistics. It is shown that the ratio of this expression to previously published spin-free integrated intensities depends only on the tensor character N of the operator driving the transition, the appropriate rotational quantum numbers J and J', and the nuclear spin of the identical nuclei. Tables are given for N = 3, 4 and J no more than 50, which enable the calculation of integrated intensities for octopole and hexadecapole collision-induced dipole-moment transitions, centrifugal-distortion-induced dipole-moment transitions, and centrifugal-distortion-induced anisotropic-polarizability-tensor Raman transitions.

Rosenberg, A.↗
NASA NTRS1979

Stress-intensity factors and crack-opening displacements for round compact specimens

A two dimensional, boundary collocation stress analysis was used to analyze various round compact specimens. The influence of the round external boundary and of pin-loaded holes on stress intensity factors and crack opening displacements was determined as a function of crack-length-to-specimen-width ratios. A wide-range equation for the stress intensity factors was developed. Equations for crack-surface displacements and load-point displacements were also developed. In addition, stress intensity factors were calculated from compliance methods to demonstrate that load-displacement records must be made at the loading points and not along the crack line for crack-length-to-specimen-width ratios less than about 0.4.

Newman, J. C., Jr.↗
NASA NTRS1979

Characterization of three types of silicon solar cells for SEPS deep space missions. Volume 1: Current-voltage characteristics of OCLI BSF/BSR 10 ohm-cm, and BSR 2 ohm-cm cells as a function of temperature and intensity

Three types of high performance silicon solar cells, BSF/BSR 10 ohm-cm, BSR 10 ohm-cm, and BSR 2 ohm-cm, were evaluated for their low temperature and low intensity performance. Sixteen cells of each type were subjected to ten temperatures and nine intensities. The BSF/BSR 10 ohm-cm cells provided the best performance at 1 solar constant and +25 C with an efficiency of 14.1% while the BSR 2 ohm-cm cells had the highest low temperature and low intensity performance with an efficiency of 22.2% at 0.04 solar constant and -170 C and the most consistent cell-to-cell characteristics.

Whitaker, A. F.↗
NASA NTRS1979

The mean intensity of radiation at 2 microns in the solar neighborhood

Consideration is given to the value of the mean intensity at 2 microns in the solar neighborhood, and it is found that it is likely to be a factor of four greater than previously estimated on theoretical grounds. It is noted however, that the estimate does agree with a reasonable extrapolation of the results of the survey of the Galactic plane by the Japanese group. It is concluded that the mean intensity in the solar neighborhood therefore probably peaks somewhat longward of 1 micron, and that this result is important for understanding the temperature of interstellar dust and the intensity of the far infrared background. This means specifically that dark clouds probably emit significantly more far infrared radiation than previously predicted.

Jura, M.↗
NASA NTRS1980

Solar limb emission lines near Ca II H & K and their spatial intensity variations

The paper employs solar observations of high spatial and spectral resolution to identify emission lines seen in the extended wings of Ca II H & K near the solar limb. Emission lines in the wings of H & K represent valuable diagnostics of the atmospheres of cool stars, with a varying information content which depends on their particular formation mechanism. In solar spectrograms different emission line formation mechanisms can be distinguished by the character of the spatial intensity variation (SIV) apparent in the lines. Various classes of H & K emission features, their spatial intensity variations and their formation mechanisms (of which some pose further problems) are discussed. A new extended list of line identifications is compiled based on their formation class and compared with other line lists. Evidence is found that stellar luminosity-sensitive lines tend to show large spatial intensity variation on the sun.

Rutten, R. J.↗
NASA NTRS1980

A comparative study of cosmic ray intensity variations during 1972-1977 using spacecraft and ground-based observations

A study of cosmic ray intensity variations using data registered by Detector C on Pioneer 10 and the Sulphur Mountain neutron monitor is presented. The spacecraft data were corrected for temperature, Radioisotope Thermoelectric Generator background, and contamination by energetic solar particle events. A consistent long-term solar cycle variation intensity is observed, but additional contribution is observed in the neighborhood of 5.1 AU which is attributed to energetic electrons of Jovian origin. The spectral variation in long-term changes of the cosmic ray intensity is studied by comparing the low-energy and high-energy data, and an average value of their ratio during 1972-1977 was found to agree with the value for the 1965-1972 interval.

Venkatesan, D.↗
NASA NTRS1979

Reduction of intensity variations on a photovoltaic array with compound parabolic concentrators

The reduction of nonuniformities in the intensity distribution of light focused on a photovoltaic array by a compound parabolic concentrator is investigated. The introduction of small distortions into the surfaces of the reflector in order to diffuse the incident collimated light to fill the angular acceptance of the concentrator is calculated by means of ray tracing to decrease the irradiance nonuniformity at the cost of a lowered effective concentration of the concentrator. Measurements of the intensity distribution on a scale test model in terrestrial sunlight with corrugated aluminized mylar reflectors are shown to be in good agreement with the ray tracing results. A two-stage concentrator consisting of a focusing primary and a nonimaging secondary is also shown to result in a fairly uniform intensity distribution except in the case of a 4-deg incidence angle, which may be corrected by the introduction of distortions into one or both concentration stages.

Greenman, P.↗
NASA NTRS1980

Observations of a free-energy source for intense electrostatic waves

Significant progress has been made in understanding intense electrostatic waves near the upper hybrid resonance frequency in terms of the theory of multiharmonic cyclotron emission using a classical loss-cone distribution function as a model. Recent observations by Hawkeye 1 and GEOS 1 have verified the existence of loss-cone distributions in association with the intense electrostatic wave events, however, other observations by Hawkeye and ISEE have indicated that loss cones are not always observable during the wave events, and in fact other forms of free energy may also be responsible for the instability. Now, for the first time, a positively sloped feature in the perpendicular distribution function has been uniquely identified with intense electrostatic wave activity. Correspondingly, we suggest that the theory is flexible under substantial modifications of the model distribution function.

Kurth, W. S.↗
NASA NTRS1980

A multiphoton treatment of near resonant light scattering in intense fields

The scattering by a two-state atom of monochromatic light of arbitrary intensity and detuning, is treated by solving Schroedinger's equation directly for the state of the scattered field. The calculation is performed in a basis of dressed atom states, which include to all orders the coupling of the incident field to the atom. Amplitudes describing sequences of scattering events are found by a nonperturbative method. A scattered intensity spectrum, directly related to the rate of change of energy in any given scattered field mode, is constructed in terms of bilinear products of the amplitudes representing all possible sequences of photon emission, and in the steady state limit the spectrum is found to be identical to the widely quoted results of Mollow. A discussion is devoted to understanding in physical terms the various quantities appearing in the expression for the intensity spectrum.

Ballagh, R. J.↗
NASA NTRS1981

Stress-intensity factor equations for cracks in three-dimensional finite bodies

Empirical stress intensity factor equations are presented for embedded elliptical cracks, semi-elliptical surface cracks, quarter-elliptical corner cracks, semi-elliptical surface cracks at a hole, and quarter-elliptical corner cracks at a hole in finite plates. The plates were subjected to remote tensile loading. Equations give stress intensity factors as a function of parametric angle, crack depth, crack length, plate thickness, and where applicable, hole radius. The stress intensity factors used to develop the equations were obtained from three dimensional finite element analyses of these crack configurations.

Newman, J. C., Jr.↗
NASA NTRS1979

A review and assessment of the stress-intensity factors for surface cracks

The stress-intensity factor solutions proposed for a surface crack in a finite plate subjected to uniform tension are reviewed. Fourteen different solutions obtained over the past 16 years using approximate analytical methods, experimental methods, and engineering estimates are compared. The accuracy of the various solutions is assessed by correlating fracture data on surface-cracked tension specimens made of a brittle epoxy material. Fracture of the epoxy material was characterized by a constant value of stress-intensity factor as failure. Thus, the correctness of various solutions is judged by the variations in the stress-intensity factors at failure. The solutions were ranked in order of minimum standard deviation. The highest ranking solutions correlated 95% of data analyzed within + or - 10% whereas the lowest ranking solutions correlated 95% of data analyzed within + or - 20%. Some solutions could be applied to all data considered, whereas others were limited with respect to crack shapes and crack sizes that could be analyzed.

Newman, J. C., Jr.↗
NASA NTRS1980

Stress-intensity factors for internal surface cracks in cylindrical pressure vessels

The paper presents stress-intensity factors for a wide range of semi-elliptical surface cracks on the inside of pressurized cylinders. The ratio of crack depth to crack length ranged from 0.2 to 1; the ratio of crack depth to wall thickness ranged from 0.2 to 0.8; and the ratio of wall thickness to vessel radius was 0.1 to to 0.25. The stress-intensity factors were calculated by a three-dimensional finite-element method using singularity elements along the crack front and linear-strain elements elsewhere. An equation for the stress-intensity factors was obtained which applies over a wide range of configuration parameters and was within about 5 percent of the present results. A comparison was also made between the results and other analyses of internal surface cracks in cylinders. The results from a boundary-integral equation method were in agreement and those from another finite-element method were in fair agreement (+ or - 8 percent) with the results.

Newman, J. C., Jr.↗
NASA NTRS1981

Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images

Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.

Rodgers, E. B.↗
NASA NTRS1982

Intensity formulas for triplet bands

Previous work in this area is surveyed and the mathematics involved in determining the quantitative intensity measurements in triplet bands is presented. Explicit expressions for the intensity distribution in the branches of the 3 Sigma-3 Pi and 1 Sigma-3Pi bands valid for all values of the coupling constant Y of the 3 Pi terms are given. The intensity distribution calculated according to the formulas given is compared with measurements of PH, 3 Pi-3 Sigma. Good quantitative agreement is obtained.

Budo, A.↗
NASA NTRS1981

An empirical stress-intensity factor equation for the surface crack

This paper presents an empirical stress-intensity factor equation for a surface crack as a function of parametric angle, crack depth, crack length, plate thickness and plate width for tension and bending loads. The stress-intensity factors used to develop the equation were obtained from a previous three-dimensional, finite-element analysis of semielliptical surface cracks in finite elastic plates subjected to tension or bending loads. A wide range of configuration parameters was included in the equation. The ratios of crack length to plate thickness and the ratios of crack depth to crack length ranged from 0 to 1.0. The effects of plate width on stress-intensity variations along the crack front were also included. The equation was used to predict patterns of surface-crack growth under tension or bending fatigue loads. The equation was also used to correlate surface-crack fracture data for a brittle epoxy material within + or - 10 percent for a wide range of crack shapes and crack sizes.

Newman, J. C., Jr.↗
NASA NTRS1982

Quantum assignments and intensity measures for methane between 1100 and 1800 per cm - A comparison between theory and experiment

The paper analyzes line positions and absolute line strengths of Blatherwick et al. (1979), based on moderately high resolution spectra of methane between 1100 and 1800 per cm, obtained using the Fourier transform spectrometer and the multiple-pass cold cell at the NASA Ames Research Center. Hamiltonian models are used to calculate theoretical relative line strengths, which, in combination with measured line strengths, yield integrated band strengths for the fundamentals v2 and v4. Ratios of calculated intensities to experimental intensities are analyzed, and the systematic deviations in the P- and R-branches of the v2 band are found to be represented by a Herman-Wallis type factor for Coriolis interactions. An analysis of ratios of calculated to experimental intensities of the v4 band yields a small correction to the Herman-Wallis factor.

Lutz, B. L.↗