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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

The effect of attention loading on the inhibition of choice reaction time to visual motion by concurrent rotary motion

This study investigates the influence of attention loading on the established intersensory effects of passive bodily rotation on choice reaction time (RT) to visual motion. Subjects sat at the center of rotation in an enclosed rotating chamber and observed an oscilloscope on which were, in the center, a tracking display and, 10 deg left of center, a RT line. Three tracking tasks and a no-tracking control condition were presented to all subjects in combination with the RT task, which occurred with and without concurrent cab rotations. Choice RT to line motions was inhibited (probability less than .001) both when there was simultaneous vestibular stimulation and when there was a tracking task; response latencies lengthened progressively with increased similarity between the RT and tracking tasks. However, the attention conditions did not affect the intersensory effect; the significance of this for the nature of the sensory interaction is discussed.

Looper, M.↗
NASA NTRS1975

A study of moving base simulation motion cues utilizing washout technique

The present study was conducted to derive data on non-visual motion thresholds utilizing washout technique, and to develop specific threshold values for use as washout parameters. It describes the results of acceleration detection studies carried out using the NASA MSFC General Purpose Simulator which provides six degree-of-freedom cab motion. A series of experiments was performed to test the hypothesis that constant velocity visual cues might suppress non-visual deceleration sensitivity. The psychophysical method employed was the forced-choice procedure which theoretically yields a pure sensitivity measure. The MSFC General Purpose Simulator was programmed to provide velocity ramps in three axes - pitch, fore-aft translation, and vertical translation. Data were collected with and without a constant velocity visual input. Comparison of the current results with classical data suggested significantly greater sensitivity of the human observer to fore-aft accelerations than has generally been reported, sensitivity tending to depend on motion direction and sign of velocity change.

Kirkpatrick, M., III↗
NASA NTRS1995

A case study of transient event motion in the magnetosphere and in the ionosphere

We present a case study of the magnetospheric and ionospheric response to a series of repetitive (7-8 min) solar wind dynamic pressure and interplanetary magnetic field (IMF) strength variations generated at the bow shock. During a period of duskward and antisunward IMF orientation, the magnetospheric and ionospheric observations indicate transient events moving dawnward and duskward away from a point of origin at or after local noon. In contrast, during a subsequent period of dawnward and antisunward IMF orientation, the observations indicate events moving duskward away from a point of origin at or prior to 0900 LT. We consider explanations in terms of pressure pulse driven riplets on the magnetopause or directly driven bursts of antiparallel merging.

Korotova, G. I.↗
NASA NTRS1938

Theoretical Study of Various Airplane Motions After Initial Disturbance

The present investigation may be considered as preliminary to the study of automatic stabilizers. We have sought to determine first how an airplane of average characteristics reacts against the principal disturbances it may encounter. Without entering into the general study of automatic stabilizers, the present work suggests the idea of a stabilizer whose sensitive member would be a wind vane or pressure plate. The elements considered as variable were the coefficients of static stability - that is, the derivatives of the coefficients of the moments with respect to the angles of attack and of yaw; these angles may be determined by the vanes.

Haus, FR↗
NASA NTRS1988

Probing Polymer-Segment Motions By ESR

Molecular origins of mechanical properties and aging processes studied. Rotational motions of segments of poly(methyl methacrylate) molecules studied theoretically and experimentally. Activation energies of these motions as determined from temperature dependencies of ESR spectra agree closely with predictions of theory.

Tsay, Fun-Dow↗
NASA NTRS1959

Study of the Oscillatory Motion of Manned Vehicles Entering the Earth's Atmosphere

An analysis is made of the oscillatory motion of vehicles which traverse arbitrarily prescribed trajectories through the atmosphere. Expressions for the oscillatory motion are derived as continuous functions of the properties of the trajectory. Results are applied to a study of the oscillatory behavior of re-entry vehicles which have decelerations that remain within limits of human tolerance. It is found that a deficiency of aerodynamic damping for such vehicles may have more serious consequences than it does for comparable ballistic missiles.

Sommer, Simon C.↗
NASA NTRS1983

Meteorological and dynamical requirements for MST radar networks: Waves

Studies of wave motions using the MST radar have concentrated on single station time series analyses of gravity waves and tides. Since these radars collect high time resolution data they have the potential to become a significant tool for mesoscale research. In addition, radars are operated almost continuously unattended and, consequently, data sets are available for analyzing longer period wave motions such as tides and planetary scale waves. Although there is much to learn from single station data, the possibilities of new knowledge from a network of radars is exciting. The scales of wave motions in the atmosphere cover a broad range. Consequently the choice of a radar network depends to a large extent on the types of wave motions that are studied. There are many outstanding research problems that would benefit from observations from a MST radar network. In particular, there is a strong need for measurements of gravity wave parameters and equatorial wave motions. Some of the current problems in wave dynamics are discussed.

Avery, S. K.↗
NASA NTRS1974

Some suggested approaches to solving the Hamilton-Jacobi equation associated with constrained rigid body motion

Some methods of approaching a solution to the Hamilton-Jacobi equation are outlined and examples are given to illustrate particular methods. These methods may be used for cases where the Hamilton-Jacobi equation is not separable and have been particularly useful in solving the rigid body motion of an earth satellite subjected to gravity torques. These general applications may also have usefulness in studying the motion of satellites with aerodynamic torque and in studying space vehicle motion where thrusting is involved.

Fitzpatrick, P. M.↗
NASA NTRS1975

Perception of linear horizontal self-motion induced by peripheral vision /linearvection/ - Basic characteristics and visual-vestibular interactions

The basic characteristics of the sensation of linear horizontal motion have been studied. Objective linear motion was induced by means of a moving cart. Visually induced linear motion perception (linearvection) was obtained by projection of moving images at the periphery of the visual field. Image velocity and luminance thresholds for the appearance of linearvection have been measured and are in the range of those for image motion detection (without sensation of self motion) by the visual system. Latencies of onset are around 1 sec and short term adaptation has been shown. The dynamic range of the visual analyzer as judged by frequency analysis is lower than the vestibular analyzer. Conflicting situations in which visual cues contradict vestibular and other proprioceptive cues show, in the case of linearvection a dominance of vision which supports the idea of an essential although not independent role of vision in self motion perception.

Berthoz, A.↗
NASA NTRS1982

A harmonic analysis method for unsteady transonic flow and its application to the flutter of airfoils

A finite difference method for solving the unsteady transonic flow about harmonically oscillating wings is investigated. The procedure is based on separating the velocity potential into steady and unsteady parts and linearizing the resulting unsteady differential equation for small disturbances. The differential equation for the unsteady velocity potential is linear with spatially varying coefficients and with the time variable eliminated by assuming harmonic motion. A study is presented of the shock motion associated with an oscillating airfoil and its representation by the harmonic procedure. The effects of the shock motion and the resulting pressure pulse are shown to be included in the harmonic pressure distributions and the corresponding generalized forces. Analytical and experimental pressure distributions for the NACA 64A010 airfoil are compared for Mach numbers of 0.75, 0.80 and 0.842. A typical section, two-degree-of-freedom flutter analysis of a NACA 64A010 airfoil is performed. The results show a sharp transonic bucket in one case and abrupt changes in instability modes.

Ehlers, F. E.↗
NASA NTRS1982

Susceptibility of the squirrel monkey to different motion conditions

The exact stimulus eliciting vomiting in animal studies of motion sickness is difficult to specify because the vestibular stimulation produced by many motion conditions is confounded by voluntary movements with animals. This is an important problem because experiments with animal models of motion sickness can provide useful information about antimotion sickness drugs or the role of neural mechanisms, only when animals are exposed to the same motion stimuli in each experimental session. A series of tests were conducted to determine the susceptibility of 15 adult squirrel monkeys to motion sickness in freely moving and restrained test conditions. Canal stimulation was varied by exposing the monkey in freely moving conditions to varying degrees of angular velocity (60, 90, 120, 150 deg/sec), and in restrained conditions to one angular velocity (150 deg/sec) and to cross-coupling effects of whole-body roll movements during rotation. Otolith stimulation was investigated by using sinusoidal vertical linear acceleration during free movement conditions, and off-vertical rotation and earth-horizontal (BBQ) rotation while restrained. The percentage of freely moving animal vomiting during vertical axis rotation was 27, 93, 86, and 92 for the angular velocities of 60, 90, 120, and 150 deg/sec respectively. None of the monkeys vomited during vertical axis rotation or cross-coupled rotation when restrained. Otolith stimulation appears to be a less provocative stimulus for the squirrel monkey as the percentage of animals vomiting were 13, 0, and 7 for the conditions of free movement during oscillation, restraint during off-vertical, and BBQ rotation respectively. Motion sickness to the point of vomiting occurred regularly only in conditions where self-motion was possible. Such effects could occur because voluntary movement during motion augments vestibular effects by producing self-inflicted cross-coupling, but the failure to elicit vomiting with experimenter-coupling cross-coupling argues against this interpretation. Alternatively, these results might imply that feedback from movement control mechanisms may play an important role in sensory conflict as suggested by Oman's sensory-motor conflict theory.

R A Fox↗
NASA NTRS2022

A Numerical Study of the Liquid Motion in Titan’s Subsurface Ocean

An ocean filled with liquid water lies beneath the icy surface of several Jovian and Saturnian moons. In such an ocean, the currents are driven by various phenomena such as the tidal forcing, the deformation of the ice shell lying at its top, the temperature gradient resulting from the surface and bottom heat fluxes…The flow induced by the first two forcings can be modelled by means of a 2D depth-averaged model, while the third one generates horizontal and vertical density variations whose effects can only be captured by a 3D baroclinic model. We study the tides of Titan’s subsurface ocean and the impact of the ice shell on the liquid motion by means of the Second-generation Louvain-la-Neuve Ice–ocean Model, SLIM (https://www.climate.be/slim). The impact of the ice shell lying at the top of the ocean is modelled by a surface friction term and surface pressure terms. The latter are a function of the difference between the ocean elevation and the vertical displacement of the shell and the time derivative of this difference. Because of Titan’s appreciable obliquity (0.306°), the tidal motion expected (and found) is similar to the Europa tidal scenario described by Tyler (2008): the surface elevation consists of two bulges rotating around Titan and the associated depth-averaged velocity field consists of two gyres, separated by an area of high speed flow, whose centre follows a sinusoidal path centred on the equator. The ice shell damps the surface motion, thus slowing down the flow, without significantly modifying the spatial patterns of these fields. The depth of the ocean and the mechanical characteristics of the ice shell being poorly constrained, a sensitivity analysis is conducted. The depth-averaged flow slows down when the depth is increased and a lag appears in the tidal phase but the tidal range remains similar. The ice shell mechanical characteristics influences both the elevation and depth-averaged velocity fields in terms of magnitude but does not modify the spatial patterns of these fields. The influence of the surface heat flux is studied by means of the 3D baroclinic version of SLIM. The heat flux derived from Titan’s topography by Kvorka et al. (2018) is used as surface boundary condition for the temperature equation while a uniform bottom heat flux is implemented. Its value is computed assuming that the heat budget of the ocean is at equilibrium. These boundary conditions cause density variations, which impact the hydrodynamics of the ocean. While the flow velocity induced by these variations is two orders of magnitude smaller than the tidal flow, its orientation is time-independent, hence impacting the orientation of the velocity field. Although the variations of ocean surface elevation and speed with respect to the shell mechanical properties can be larger than those induced by the surface heat flux, taking into account the latter results in large variations of the velocity field global patterns, which was not observed when modifying the shell mechanical properties. Future studies should therefore focus on modelling the surface and bottom heat fluxes while uncertainties about the mechanical characteristics of the shell can be tolerated.

Titan↗
NASA NTRS1984

Tribology experiment in zero gravity

A tribology experiment in zero gravity was performed during the orbital flight of Spacelab 1 to study the motion of liquid lubricants over solid surfaces. The absence of a significant gravitational force facilitates studies of the motion of liquid lubricants over solid surfaces as controlled by interfacial and capillary forces. Observations were made of phenomena associated with the liquid on one solid surface and also with the liquid between a pair of closely spaced surfaces. Typical photographic records obtained on Spacelab 1 are described.

Pan, C. H. T.↗
NASA NTRS1994

Dynamics Of Ions In A Radio-Frequency Quadrupole Trap

Report describes computer-simulation study of motions of various numbers of ions in Paul trap. Study part of continuing effort to understand motions of trapped charged particles (atoms, ions, molecules, or dust particles). Motions characterized in terms of heating by radio-frequency fields, formation of crystallike structures in cold clouds of trapped particles, and other phenomena important in operation of radio-frequency traps in frequency standards.

Prestage, John D.↗
NASA NTRS1975

Study of cosmic ray motion in cosmic space near the earth

Data are presented on experimental installations developed in the cosmic ray variations laboratory in Kazgu (Alma-Ata). Various experiments on modelling the interaction of plasma with the geomagnetic field as well as the plasma distribution in quiet and disturbed fields are described. The characteristics of the meson supertelescope using scintillators (effective area, 10 sq m) for vertical alignments designed to study microvariations of the cosmic rays and their interrelation with magnetospheric fluctuations and the study of solar wind parameters are given.

Budilov, V. K.↗
NASA NTRS1991

Self Motion Perception and Motion Sickness

The studies conducted in this research project examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

Fox, Robert A.↗