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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Data user's notes of the radio astronomy experiment aboard the OGO-V spacecraft

General information concerning the low-frequency radiometer, instrument package launching and operation, and scientific objectives of the flight are provided. Calibration curves and correction factors, with general and detailed information on the preflight calibration procedure are included. The data acquisition methods and the format of the data reduction, both on 35 mm film and on incremental computer plots, are described.

Haddock, F. T.↗
NASA NTRS1974

A note on a broken layer in an orthotropic laminate composite

An orthotropic laminate composite containing a completely broken layer is considered. The problem is formulated in terms of integral transforms and then reduced to a singular integral equation which is solved numerically. The strength of stress singularity at the crack tip is determined from a characteristic equation which is obtained by studying the dominant part of the singular integral equation near the end points. The stress intensity factors are given for various material properties.

Arin, K.↗
NASA NTRS1975

The fluorescence of chlorophyll and yellow substances in natural waters: A note on the problems of measurement and the importance of their remote sensing

There are two chromophylls which, if sensed remotely from high altitude, would revolutionize the ability to survey large areas of the world's oceans. The chromophylls of importance are: the photosynthetic pigments of plankton algae and a group of organic materials frequently termed dissolved yellow substances. These are derived from plants and carried into the ocean by fresh water inflow. The attenuation of light by phytoplankton is characterized by two distinctive bands (450, 675 nm) which represent absorption by chloroplastic pigments. Yellow substances are characterized by a strong ultraviolet absorption which tails over into the visible region. It is emphasized that chlorophyll determination could be a unique technique for estimating the extent of eutrophication in coastal waters, and that a high altitude observer equipped with temperature, chlorophyll and yellow substance sensors has the possibility of detecting the magnitude of eutrophication and its sources by using laser induced fluorescent devices.

Yentsch, C. S.↗
NASA NTRS1974

Note on the symmetry of perturbed Hartree-Fock and X-alpha wavefunctions

An objection to the effect that the first-order orbitals describing the perturbation of Hartree-Fock or X-alpha closed shell atoms by a multipole electric field may not have the required symmetry properties is acknowledged and answered. It is shown that the assumption of the expected symmetry is a self-consistent one.

Eaves, J. O.↗
NASA NTRS1974

A note on the interference of two collinear cracks in a cylindrical shell

A simple interference problem in shells is evaluated and the results are compared with the obtained data for flat plates. A pressurized shallow cylindrical shell containing two collinear axial through cracks of equal lengths is investigated. It is found that as the size of the net ligament between the two cracks approaches zero, the stress intensity factors at the inner crack tips go to infinity, and the factors at the outer tips approach values that correspond to a single crack except that they are twice as long.

Erdogan, F.↗
NASA NTRS1975

Notes on the acoustic field of rigid bodies

The present paper extends a previous analysis, in Farassat (1974), of the acoustic field of rigid bodies. A restriction on that analysis can be removed by replacing the moving body by a stationary, virtual radiating body whose shape depends on the observer time and location and on the shape and motion of the rigid body. The possible singularity of the solution is considered.

Farassat, F.↗
NASA NTRS1975

A note on an attempt at more efficient Poisson series evaluation

A substantial reduction has been achieved in the time necessary to compute lunar libration series. The method involves eliminating many of the trigonometric function calls by a suitable transformation and applying a short SNOBOL processor to the FORTRAN coding of the transformed series, which obviates many of the multiplication operations during the course of series evaluation. It is possible to accomplish similar results quite easily with other Poisson series.

Shelus, P. J.↗
NASA NTRS1975

A note on the effect of lateral bending stiffness of stringers attached to a plate with a crack

An infinite stringer which is assumed to be partially bonded to a plate through a layer of adhesive is considered. The stringer is assumed to have bending as well as longitudinal stiffness. The effect of the stringer's bending rigidity on the stress intensity factor at the tip of the crack is illustrated. Shear stress distribution between the plate and the stringer and the stress intensity factors will be obtained from the solution of a system of Fredholm integral equations which represent the continuity of displacements along the line of bond.

Arin, K.↗
NASA NTRS1975

Note on performance of tapered grip tensile loading devices

Alignment results are presented in terms of percent bending for a quick release, tapered grip, tensile loading device that has been proposed for testing sharply notched specimens of aluminum and magnesium alloys by a Task Group of the ASTM Committee E-24 on Fracture Testing of Metals. The results show that the bending introduced by the fixtures is strongly dependent on their relative rotational positions in respect to the loading rods which adapt them, to the tensile machine. For one set of tapered grips the highest bending was about 15%. Recommendations are made for improvement in the design of the tapered grips which should reduce the bending stresses substantially.

Jones, M. H.↗
NASA NTRS1974

Note on the transfer wave matrix

A relationship exists between the elements of the transfer wave matrix and the ABCD matrix elements which allows a considerable reduction of effort required to find the matrix for cascaded two-port network sections. This relationship and the simplified expressions for obtaining the matrix elements are presented here.

Chang, F.-C.↗
NASA NTRS1975

Note on the electric splitting of drift shells

A nonrelativistic analysis is presented for the deviation of a particle from its dipole magnetic drift shell in the presence of an electric field. An alternative definition of weak shell splitting is introduced in which the corotation drift velocity need not be small with respect to the azimuthal magnetic drift velocity. Approximate explicit solutions are obtained for the asymmetry of drift shells in the strong shell splitting case, i.e., for the case where the cross-magnetosphere potential drop is not small compared to particle kinetic energy. Upper limits to drift shell asymmetry are obtained from considerations of the Alfven layer.

Kivelson, M. G.↗
NASA NTRS1974

The LARSYS educational package: Instructor's notes

Materials are presented for assisting instructors in teaching the LARSYS Educational Package, which is a set of instructional materials to train people to analyze remotely sensed multispectral data. The seven units of the package are described. These units are: quantitative remote sensing, overview of the LARSYS software system, the 2780 remote terminal, demonstration of LARSYS on the 2780 remote terminal, exercises, guide to multispectral data analysis, and a case study using LARSYS for analysis of LANDSAT data.

Lindenlaub, J. C.↗
NASA NTRS1976

Notes on the stability and control of tailless airplanes

Problems involved in the stability and control of tailless airplanes are discussed. Such factors as the location of the aerodynamic center and its effect on the longitudinal stability, longitudinal trim with high lift devices, the effects of various changes in the shape of the wing on lateral stability, and the effects of nacelles are covered. It appears that sufficient stability and controllability can be secured without sweepback. With sweepback, a flap over the center section of the wing may be used to serve the dual purpose of elevator control and high lift device. Sweepback introduces undesirable stalling characteristics, however, and may require auxiliary devices to prevent stalling of the tips.

Jones, R. T.↗
NASA NTRS1976

A note on correlation description

The paper suggests some modifications to definitions of correlation functions made by Freeman and Bennett (1974) specifically for comparing measured quantities with those predicted by rotor theories, with reference to rotorcraft flight simulation. Special attention is paid to the quality of correlation, determined by a quality factor relating the measured and computed entities. Correlation criteria (mean load and rotor performance, overall amplitude and phase, harmonic altitude and harmonic phase) are examined, along with phase angle correlation criteria (harmonic phase defined by sine-cosine relation and harmonic phase defined by a first positive peak rotor azimuth position)

Mccloud, J. L., III↗
NASA NTRS1976

A note on the leap-frog scheme in two and three dimensions

The paper considers the leap-frog finite-difference method (Kreiss and Oliger, 1973) for systems of partial differential equations of the form du/dt = dF/dx + dG/dy + dH/dz, where d denotes partial derivative, u is a q-component vector and a function of x, y, z, and t, and the vectors F, G, and H are functions of u only. The original leap-frog algorithm is shown to admit a modification that improves on the stability conditions for two and three dimensions by factors of 2 and 2.8, respectively, thereby permitting larger time steps. The scheme for three dimensions is considered optimal in the sense that it combines simple averaging and large time steps.

Abarbanel, S.↗