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At least 235 records · Page 13

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NASA NTRS1976

Dynamics of the Jovian magnetosphere and energetic particle radiation

Inferences are drawn from Jovian magnetosphere data acquired in the flybys of Pioneer 10 and Pioneer 11. Data on the outer magnetosphere and the inner core, and on observed 10-hr variations in particle intensity, are summarized, with attention given to the immense size and complexity of the magnetosphere and the behavior of trapped charged particles. The data support the maintenance and acceleration of charged particles trapped in Jupiter's magnetic field by inward diffusion in violation of the third adiabatic invariant. Prodigious quantities of high-energy particles are found to escape from Jupiter into interplanetary space, and MHD waves in the circumjovian plasma are considered. Whether the 10-hr variations are spatial or temporal in origin is weighed in favor of the latter. Production and loss mechanisms for the particles, and the nature of the Jovian magnetosphere itself, are noted among questions remaining obscure.

Simpson, J. A.↗

NASA NTRS1976

Remote sensing, land use, and demography - A look at people through their effects on the land

Relevant causes of failure by the remote sensing community in the urban scene are analyzed. The reasons for the insignificant role of remote sensing in urban land use data collection are called the law of realism, the incompatibility of remote sensing and urban management system data formats is termed the law of nominal/ordinal systems compatibility, and the land use/population correlation dilemma is referred to as the law of missing persons. The study summarizes the three laws of urban land use information for which violations, avoidance, or ignorance have caused the decline of present remote sensing research. Particular attention is given to the rationale for urban land use information and for remote sensing. It is shown that remote sensing of urban land uses compatible with the three laws can be effectively developed by realizing the 10 percent contribution of remote sensing to urban land use planning data collection.

Paul, C. K.↗

NASA NTRS1976

Interchange stability of a rapidly rotating magnetosphere

A rotation-dominated magnetosphere is unstable to magnetic flux-tube interchange motions if and only if the plasma content of a unit magnetic flux tube is a decreasing function of distance from the spin axis. For a spin-aligned dipole field, an approximate expression is obtained for the marginally stable distribution. Plasma filling the Jovian magnetosphere from internal sources would initially violate this stability criterion so that interchange motions would act to establish the marginally stable distribution.

Hill, T. W.↗

NASA NTRS1976

Aeroelastic characteristics of composite bearingless rotor blades

Owing to the inherent unique structural features of composite bearingless rotors, various assumptions upon which conventional rotor aeroelastic analyses are formulated, are violated. Three such features identified are highly nonlinear and time-varying structural twist, structural redundancy in bending and torsion, and for certain configurations a strongly coupled low frequency bending-torsion mode. An examination of these aeroelastic considerations and appropriate formulations required for accurate analyses of such rotor systems is presented. Also presented are test results from a dynamically scaled model rotor and complementary analytic results obtained with the appropriately reformulated aeroelastic analysis.

Bielawa, R. L.↗

NASA NTRS1977

Some further information on the rapid burster MXB 1730-335

Further analysis of SAS-3 data on the rapid burster MXB 1730-335 show the existence of anomalous bursts. They have approximately 3-s rise times and low peak intensities; they also violate the energy vs. interburst-interval relationship for normal bursts. The short normal bursts of about 4-s duration do not show a long tail such as observed in the long normal bursts. Evidence for time structure in normal bursts down to a time scale of 50 ms is presented. No periodic variations in the total X-ray flux were found in the 1-500-Hz range.

Ulmer, M. P.↗

NASA NTRS1977

Principles of equivalence, Eotvos experiments, and gravitational red-shift experiments - The free fall of electromagnetic systems to post-post-Coulombian order

Free fall in an external static gravitational field of a composite test body consisting of electromagnetically interacting charged particles is analyzed using the TH-epsilon-mu formalism developed by Lightman and Lee (1973). The Lightman and Lee calculation that was carried out to 'post-Coulombian' order is extended to 'post-post-Coulombian' order, and violations of the weak equivalence principle are found which result from the magnetostatic self-energy of the test body. The current generation of Eotvos experiments is shown to test the cited formalism at first order in the external gravitational potential to an accuracy of 4 by 10 to the -10th power for electrostatic energies and 6 by 10 to the -6th power for magnetostatic energies. It is concluded that although the formalism can be tested to an accuracy of 0.04 for electrostatic energies at second order in the gravitational potential, a significant second-order test for magnetostatic energies would require Eotvos experiments accurate to better than one part in 10 to the 15th power.

Haugan, M. P.↗

NASA NTRS1977

Does electromagnetic radiation accelerate galactic cosmic rays

The 'reactor' theories of Tsytovich and collaborators (1973) of cosmic-ray acceleration by electromagnetic radiation are examined in the context of galactic cosmic rays. It is shown that any isotropic synchrotron or Compton reactors with reasonable astrophysical parameters can yield particles with a maximum relativistic factor of only about 10,000. If they are to produce particles with higher relativistic factors, the losses due to inverse Compton scattering of the electromagnetic radiation in them outweigh the acceleration, and this violates the assumptions of the theory. This is a critical restriction in the context of galactic cosmic rays, which have a power-law spectrum extending up to a relativistic factor of 1 million.

Eichler, D.↗

NASA NTRS1978

Curvilinear projection developments

Gradient projection is a powerful algorithm for minimization of a function subject to constraints. Constraint nonlinearities hamper projection computations. The constraints must then be restored before another projection cycle. The restoration steps taken in the process of following nonlinear constraint surfaces can be used as a guide to the construction of a curve which more nearly follows the constraints than does the straight line in the projected gradient direction. This scheme, termed 'curvilinear projection', was explored in earlier research. The study presently reported carries out some computational experiments using a related version of the technique. Some other details of projection computations which turn out to be practically important are taken up: rules for updating the variable metric in projection when early termination of the one-dimensional search on constraint violation occurs, and active-constraint logic for screening inequalities that makes use of the Kuhn-Tucker necessary conditions.

Kelley, H. J.↗

NASA NTRS1978

A mission profile life test facility

A test facility is being prepared for a 16,000 hour mission profile life test of multiple electric propulsion thrust subsystems. The facility will be capable of simultaneously operating three 2.7 kW, 30 cm mercury ion thrusters and their power processing. The facility will permit conduction of a program of long-term tests to document thruster characteristics as a function of time and operating point to allow prediction of thruster performance for any mission profile. The thruster will be tested in a 7m by 10m vacuum chamber. Each thruster will be installed in a separate lock chamber so that it can be extended into, or extracted from the main chamber without violating the vacuum integrity of the other thruster. The thrusters will exhaust into a 3m by 5m frozen mercury target. The target and an array of cryopanels to collect sputtered target material will be liquid nitrogen chilled. Power processor units will be tested in an adjacent 1.5m by 2m vacuum chamber and will be temperature controlled by simulated heat pipes.

James, E.↗

NASA NTRS1978

Analysis of weak interactions and Eotvos experiments

The intermediate-vector-boson model is preferred over the current-current model as a basis for calculating effects due to weak self-energy. Attention is given to a possible violation of the equivalence principle by weak-interaction effects, and it is noted that effects due to weak self-energy are at least an order of magnitude greater than those due to the weak binding energy for typical nuclei. It is assumed that the weak and electromagnetic energies are independent.

Hsu, J. P.↗

NASA NTRS1978

Radiolysis, racemization and the origin of molecular asymmetry in the biosphere

An investigation has been undertaken to determine whether ionizing radiation might engender racemization of optically active amino acids, along with their usual radiolysis. As prototypes, crystalline Dand L-leucine, as well as aqueous solutions of their sodium salts were exposed to the radiation from a 3000 Ci Co-60 gamma-ray source. Gamma-ray doses which caused about 68% radiolysis of solid leucine left a residue which was about 5% racemized, while racemization proved even greater at lower doses for the dissolved sodium salts. In aqueous solution both percent degradation and percent racemization of the sodium salts were proportional to gamma-ray dosage within the range employed (1,000,000-27,000,000 rads). Implications of these observations for the origin of molecular asymmetry by the beta-decay parity violation mechanism are discussed.

Bonner, W. A.↗

NASA NTRS1975

Lunar petrogenesis in a well-stirred magma ocean

The principal group of low-KREEP highlands rocks as indicated by quartz-olivine-anorthite pseudoternary phase diagrams shows chemical trends which violate the Bowen reaction principle, in that the greater the concentration of magnesian and mafic minerals, the more sodic the coexisting plagioclase tends to be. It is suggested that this trend was established during the primary differentiation of the lunar crust and is a result of crystallization in a vigorously convecting (well-stirred) system. Under these conditions all plagioclase crystals, all pyroxene crystals, and all of the residual liquid remain fairly uniform in composition until advanced crystallization immobilizes the system. The rock suite then established would vary continuously from anorthositic types at the top to ultramafic types at the bottom.

Wood, J. A.↗

NASA NTRS1978

On variations in the galactic interstellar extinction law

Ultraviolet data obtained by the TD1 satellite are rediscussed, and we conclude that they indicate that the interstellar extinction law is not constant throughout the galaxy. This result disagrees with the findings of Nandy et al. (1976) as based on the same observational material. Without violating the integrity of the data it is possible to explain all variations in terms of a varying 2200 A feature. It is stressed that this explanation is by no means unique.

Koornneef, J.↗

NASA NTRS1980

Extracting trace substances from biological fluids

Apparatus is used as aid in extraction of trace amounts of volatile organics from biological fluids. "Transervaporator" makes it possible to prepare violate fraction for analysis by high-resolution gas chromatography.

Zlatkis, A.↗

NASA NTRS1978

An experiment to verify that the weak interactions satisfy the strong equivalence principle

The construction of a clock based on the beta decay process is proposed to test for any violations by the weak interaction of the strong equivalence principle bu determining whether the weak interaction coupling constant beta is spatially constant or whether it is a function of gravitational potential (U). The clock can be constructed by simply counting the beta disintegrations of some suitable source. The total number of counts are to be taken a measure of elapsed time. The accuracy of the clock is limited by the statistical fluctuations in the number of counts, N, which is equal to the square root of N. Increasing N gives a corresponding increase in accuracy. A source based on the electron capture process can be used so as to avoid low energy electron discrimination problems. Solid state and gaseous detectors are being considered. While the accuracy of this type of beta decay clock is much less than clocks based on the electromagnetic interaction, there is a corresponding lack of knowledge of the behavior of beta as a function of gravitational potential. No predictions from nonmetric theories as to variations in beta are available as yet, but they may occur at the U/sg C level.

Eby, P. B.↗

NASA NTRS1978

Formulation of consumables management models, executive summary

Future manned space programs that have increased launch frequencies and reusable systems require an implementation of new consumables and systems management techniques that relieve both the operations support personnel and flight crew activities. Analytical models and techniques were developed which consist of a Mission Planning Processor (MPP) with appropriate consumables data base, methods of recognizing potential constraint violations in both the planning and flight operations functions, and flight data files for storage/retrieval of information over extended periods interfacing with flight operations processors for monitoring of the actual flights. Consumables subsystems considered in the MPP were electrical power, environmental control and life support, propulsion, hydraulics and auxiliary power.

Torian, J. G.↗

NASA NTRS1978

Radiative transfer in spherical shell atmospheres. II - Asymmetric phase functions

This paper investigates the effects of sphericity on the radiation reflected from a planet with a homogeneous conservative-scattering atmosphere of optical thicknesses of 0.25 and 1.0. A Henyey-Greenstein phase function with asymmetry factors of 0.5 and 0.7 was considered. Significant differences were found when these results were compared with the plane-parallel calculations. Also, large violations of the reciprocity theorem, which is only true for plane-parallel calculations, were noted. Results are presented for the radiance versus height distributions as a function of planetary phase angle. These results will be useful to researchers in the field of remote sensing and planetary spectroscopy.

Kattawar, G. W.↗

NASA NTRS1978

A dependency-based modelling mechanism for problem solving

The paper develops a technique of dependency net modeling which relies on an explicit representation of justifications for beliefs held by the problem solver. Using these justifications, the modeling mechanism is able to determine the relevant lines of inference to pursue during problem solving. Three particular problem-solving difficulties which may be handled by the dependency-based technique are discussed: (1) subgoal violation detection, (2) description binding, and (3) maintaining a consistent world model.

London, P.↗