Optokinetic motion sickness - Continuous head movements attenuate the visual induction of apparent self-rotation and symptoms of motion sickness
Explore the source record for details and available documents.
Lackner, J. R.↗
SEARCH · Search NASA
Results for “Continued Rotation”
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.
Active faulting and block rotations in the western Transverse Ranges, California
This paper uses the results of five years of VLBI measurements in conjunction with data on slip vectors of major earthquakes and the dominant westerly trend of faults and blocks to argue that these data are consistent with the concept that rotations about vertical axes in the western Transverse Ranges in California continue at rates of several degrees per million years. It is suggested that rotations about vertical axes may occur in the western Transverse Ranges without these rotations necessarily being manifestations of continuous deformation at depth and that attempts to account for the relative motion of the Pacific and the North America plates by adding rates of slip on major faults are likely to fail.
Jackson, James↗
Telescope dome control system automatically tracks sun
Automatic control system is designed to rotate a dome so that a telescope, or other instruments, within the dome will continuously view the sun as the earth rotates.
Cashion, K. D.↗
Dense cores in dark clouds. VIII - Velocity gradients
An analysis of motions consistent with uniform rotation in dense cores is presented. Twenty-nine of the 43 cores studied have a statistically significant gradient. Some gradients are spatially continuous and are consistent with uniform rotation, but other apparent gradients are caused by clump-clump motion, or sharp localized gradients, within a map. The motions in L1495, B217, L1251, L43, B361, and L1551 are discussed in detail. In L1551, the residuals of the fit to the NH3 velocity field indicate an outflow from IRS5 in the same direction as the CO outflow. Gradient orientation appears to be preserved over a range of density, as evidenced by comparing results of NH3 to fits of (C-18)O and CS maps. The specific angular momentum is found to scale roughly as F exp 3/2, where R represents the diameter of the FWHM intensity contour in a map.
Goodman, A. A.↗
Effects of Mass-Loading Variations and Applied Moments on Motion and Control of a Manned Rotating Space Vehicle
An analytical study has been made to determine the effects of mass-loading variations and onboard rotating machinery on a hypothetical earth-satellite space station, rotating to provide an artificial gravity equal to one-fourth of that at the earth's surface. Attempts were also made to damp out or minimize undesirable motions by using mass shifts, constant-rate inertia wheels, or jet-reaction moments. Results obtained indicate that the shifting of masses within the rotating space station could bring about large roll oscillations (plus or minus 100 degrees) or even continuous rolling motions if the craft is rotating about the axis of intermediate moment of inertia. The pitch angles obtained were generally small (less than plus or minus 1 degree). The amplitudes of the roll and pitch oscillations are dependent upon the angle of displacement of the greatest principal axis of inertia from the initial spin axis. In attempting to damp out or minimize undesirable motions, it was found that a constant-rate inertia wheel located on and rotating about the axis about which the craft is rotating (Z-axis) was beneficial in keeping the roll angles relatively small, provided it had a sufficient amount of angular momentum. It was also found that the use of jet-reaction moments was very satisfactory for damping undesirable motions in that the roll oscillations could be damped.
Grantham, William D.↗
Kinematic principles of primate rotational vestibulo-ocular reflex. I. Spatial organization of fast phase velocity axes
The spatial organization of fast phase velocity vectors of the vestibulo-ocular reflex (VOR) was studied in rhesus monkeys during yaw rotations about an earth-horizontal axis that changed continuously the orientation of the head relative to gravity ("barbecue spit" rotation). In addition to a velocity component parallel to the rotation axis, fast phases also exhibited a velocity component that invariably was oriented along the momentary direction of gravity. As the head rotated through supine and prone positions, torsional components of fast phase velocity axes became prominent. Similarly, as the head rotated through left and right ear-down positions, fast phase velocity axes exhibited prominent vertical components. The larger the speed of head rotation the greater the magnitude of this fast phase component, which was collinear with gravity. The main sequence properties of VOR fast phases were independent of head position. However, peak amplitude as well as peak velocity of fast phases were both modulated as a function of head orientation, exhibiting a minimum in prone position. The results suggest that the fast phases of vestibulo-ocular reflexes not only redirect gaze and reposition the eye in the direction of head motion but also reorient the eye with respect to earth-vertical when the head moves relative to gravity. As further elaborated in the companion paper, the underlying mechanism could be described as a dynamic, gravity-dependent modulation of the coordinates of ocular rotations relative to the head.
Non-NASA Center↗
A multiple-plate, multiple-pinhole camera for X-ray gamma-ray imaging
Plates with identical patterns of precisely aligned pinholes constitute lens system which, when rotated about optical axis, produces continuous high resolution image of small energy X-ray or gamma ray source. Camera has applications in radiation treatment and nuclear medicine.
Hoover, R. B.↗
Proposed system safety design and test requirements for the microlaser ordnance system
Safety for pyrotechnic ignition systems is becoming a major concern for the military. In the past twenty years, stray electromagnetic fields have steadily increased during peacetime training missions and have dramatically increased during battlefield missions. Almost all of the ordnance systems in use today depend on an electrical bridgewire for ignition. Unfortunately, the bridgewire is the cause of the majority of failure modes. The common failure modes include the following: broken bridgewires; transient RF power, which induces bridgewire heating; and cold temperatures, which contracts the explosive mix away from the bridgewire. Finding solutions for these failure modes is driving the costs of pyrotechnic systems up. For example, analyses are performed to verify that the system in the environment will not see more energy than 20 dB below the 'No-fire' level. Range surveys are performed to determine the operational, storage, and transportation RF environments. Cryogenic tests are performed to verify the bridgewire to mix interface. System requirements call for 'last minute installation,' 'continuity checks after installation,' and rotating safety devices to 'interrupt the explosive train.' As an alternative, MDESC has developed a new approach based upon our enabling laser diode technology. We believe that Microlaser initiated ordnance offers a unique solution to the bridgewire safety concerns. For this presentation, we will address, from a system safety viewpoint, the safety design and the test requirements for a Microlaser ordnance system. We will also review how this system could be compliant to MIL-STD-1576 and DOD-83578A and the additional necessary requirements.
Stoltz, Barb A.↗
Grinding Glass Disks On A Belt Sander
Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.
Lyons, James J., III↗
Discovery of Nine Gamma-Ray Pulsars in Fermi-Lat Data Using a New Blind Search Method
We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient, and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, and characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs Jl803-2149 and J2111+4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 x 10(exp 35) ergs per second and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J010622+3749, Jl620-4927, Jl746-3239, J2028+3332,J2030+4415, J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (|b| greater than 10 degrees). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2x 10(exp 11)G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 x l0(exp 33) erg per second) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR J0106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.
Celik-Tinmaz, Ozlem↗
Towers: Critical Initial Infrastructure for the Moon, Such as a Power Module Support
Towers are an efficient structure commonly used to elevate systems against a gravity field, such as above the surface of a planet or the Moon. Towers can be used to elevate antennas, transmitters and sensors for communication, navigation, and observation infrastructure in support of surface operations. Near the Lunar poles, elevation of rotating solar panels enables nearly continuous panel illumination for solar power production despite the Sun remaining near the horizon year-round. Further, once technology is developed for tower assembly, this same technology can be extended to the assembly of a variety of structures including rocket blast containment shields, bridges, shelters, and habitats from either Earth-sourced or Lunar-sourced structural members. Environmental factors on the Lunar surface are vastly different than those found on Earth and have significant impact on the design of towers. Towers designed for the Lunar surface have no heritage nor Earth analog. The designs discussed herein are therefore breaking new ground creating a fundamentally new class of structures outside of current experience and intuition. The purpose of this paper is to: a) describe the unique environmental factors affecting tower design on the Lunar surface compared to Earth-based systems, b) evaluate two structural forms for the tower; telescoping tubes and an assembled truss, as well as c)provide recommendations on when each structural form is most suitable. A major contribution presented in the current paper is to provide parametric plots and supporting equations of mass and volume versus module power level and blanket height above the Lunar surface for the solar array application, to enable system level studies of optimum power module distribution and size. A secondary contribution are plots of the mass and volume of aluminum or structural glass required for assembled truss towers formed from Lunar derived structural members. An objective of achieving 1 MW of total power has been used to enable comparison of structural forms, because the total mass of solar arrays is consistent. It will be shown that for moderate module sizes, up to ~50 kW power modules, based on a telescoping tube tower have advantages, but for power modules from 50 kW to 200 kW an assembled truss tower can be created with half to one third of the tube tower mass. More significantly, when shipped from Earth, an assembled truss tower can be packed into 1/14th to 1/25th of the tube tower volume. Truss designs in the 100 kW to 200 kW range will be shown to be a favorable when assembled from either graphite-epoxy angles shipped from Earth or aluminum angles fabricated from Lunar materials. 50 kW towers are an attractive choice for both a telescoping or assembled tower with the solar arrays elevated 10 m above the Lunar surface, while increased solar array elevation favors 100 kW to 200 kW power modules.
assembly↗
A sun gate for Galileo spacecraft attitude control
The combination of a sun sensor called a sun gate (SG) and a digital programmable signal processor on the Galileo spacecraft attitude and articulation control subsystem (AACS) will orient the rotation axis of the spacecraft toward the sun to satisfy a new requirement imposed by the new spacecraft trajectory. The combination will continuously monitor the pointing direction of the rotation axis, and any off-sun excursions of more than a preset threshold will be detected, triggering appropriate actions by the flight software to prevent off-sun cone angles of more than 14 deg. The design of the SG is described in detail, its principle of operation is given, and the flight software processing of the SG output is discussed.
Mobasser, Sohrab↗
Generalization of Boundary-Layer Momentum-Integral Equations to Three-Dimensional Flows Including Those of Rotating System
The Navier-Stokes equations of motion and the equation of continuity are transformed so as to apply to an orthogonal curvilinear coordinate system rotating with a uniform angular velocity about an arbitrary axis in space. A usual simplification of these equations as consistent with the accepted boundary-layer theory and an integration of these equations through the boundary layer result in boundary-layer momentum-integral equations for three-dimensional flows that are applicable to either rotating or nonrotating fluid boundaries. These equations are simplified and an approximate solution in closed integral form is obtained for a generalized boundary-layer momentum-loss thickness and flow deflection at the wall in the turbulent case. A numerical evaluation of this solution carried out for data obtained in a curving nonrotating duct shows a fair quantitative agreement with the measures values. The form in which the equations are presented is readily adaptable to cases of steady, three-dimensional, incompressible boundary-layer flow like that over curved ducts or yawed wings; and it also may be used to describe the boundary-layer flow over various rotating surfaces, thus applying to turbomachinery, propellers, and helicopter blades.
Mager, Arthur↗
Investigation of Potential Thermal Processing Techniques for the Enhancement of PS300 High Temperature Solid Lubricant Coatings
Contemporary trends in rotating machinery development have produced a continuous evolution towards ever increasing speeds and higher operating temperatures. This process has been particularly evident in aerospace and automotive applications such as turbochargers. The combination of high temperature and high speed has exceeded the capacity of mainstream liquid lubrication technology. The NASA Glenn Research Center has been at the forefront in developing innovative solid lubricants for the oil free protection of rotating machinery under these extreme environmental conditions. The most recent of these is the PS 300 series of plasma sprayed solid lubricant coatings. St Louis University and NASA Glenn Research Center entered into this cooperative agreement to investigate potential thermal processing techniques for the enhancement of the PS 304 solid lubricant.
Benoy, Patricia A.↗
Summary of Jovian latitude and rotation period observations from 1898 to 1970.
A ten-year summary of recent measurements of the latitudes of Jupiter's belts and the rotation periods of the various atmospheric currents is presented. Comparison of these measured values with earlier visual observations indicates that the latter are sufficiently accurate to provide a reliable and continuous record of latitudes since 1908 and rotation periods since 1898. A summary of the earlier observations is also given.
Reese, E. J.↗
Rotational Raman Lidar for Lower Tropospheric Temperature Profiling
Accurate sensing of the tropospheric temperature profile is basically needed in meteorology and 3D mapping of the boundary layer atmospheric temperature over urban and industrial areas. Several temperature lidar techniques were investigated, including Differential Absorption Lidar (DIAL), rotational and vibrational Raman, Rayleigh and high resolution Rayleigh schemes. For the tropospheric applications, the rotational Raman scheme looks potentially advantageous, but several stringent technical problems still remain to be solved. Reported here are the continuing efforts of the system development of the rotational Raman lidar.
Kobayashi, Takao↗
Measurement of total electron content with a geostationary satellite during the solar eclipse of March 7, 1970.
This note deals with the measurement of the total electron content of the ionosphere at the Goddard Space Flight Center, looking towards the geostationary satellite ATS 3 during the solar eclipse of Mar. 7, 1970. Obscuration at this site was nearly total. Faraday rotation was measured with a stationary circularly polarized antenna and a dual-channel phase-lock receiver tuned to 137.350 MHz. By comparing the electrical phase of the two opposite circularly polarized components, a continuous chart recording was made of Faraday rotation vs local time. A depletion of about 25% in electron content was observed from first contact to the time of minimum electron content. The time variations of the electron content during the eclipse are briefly examined in the light of current theories of ionospheric processes.
Rangaswamy, S.↗
Three-dimensional organization of vestibular related eye movements to rotational motion in pigeons
During rotational motions, compensatory eye movement adjustments must continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined. Rotations about different head axes produced horizontal, vertical, and torsional eye movements, whose component magnitude was dependent upon the cosine of the stimulus axis relative to the animal's visual axis. Thus, the three-dimensional organization of the VOR in pigeons appears to be compensatory for any direction of head rotation. Frequency responses of the horizontal, vertical, and torsional slow phase components exhibited high pass filter properties with dominant time constants of approximately 3 s.
NASA Discipline Neuroscience↗