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Sample records for off-vertical axis rotation

  1. Verticality perception during off-vertical axis rotation.

    PubMed

    Vingerhoets, R A A; Van Gisbergen, J A M; Medendorp, W P

    2007-05-01

    During prolonged rotation about a tilted yaw axis, often referred to as off-vertical axis rotation (OVAR), a percept of being translated along a conical path slowly emerges as the sense of rotation subsides. Recently, we found that these perceptual changes are consistent with a canal-otolith interaction model that attributes the illusory translation percept to improper interpretation of the ambiguous otolith signals. The model further predicts that the illusory translation percept must be accompanied by slowly worsening tilt underestimates. Here, we tested this prediction in six subjects by measuring the time course of the subjective visual vertical (SVV) during OVAR stimulation at three different tilt-rotation speed combinations, in complete darkness. Throughout the 2-min run, at each left-ear-down and right-ear-down position, the subject indicated whether a briefly flashed line deviated clockwise or counterclockwise from vertical to determine the SVV with an adaptive staircase procedure. Typically, SVV errors indicating tilt underestimation were already present at rotation onset and then increased exponentially to an asymptotic value, reached at about 60 s after rotation onset. The initial error in the SVV was highly correlated to the response error in a static tilt control experiment. The subsequent increase in error depended on both rotation speed and OVAR tilt angle, in a manner predicted by the canal-otolith interaction model. We conclude that verticality misjudgments during OVAR reflect a dynamic component linked to canal-otolith interaction, superimposed on a tilt-related component that is also expressed under stationary conditions.

  2. Tilt and Translation Motion Perception during Off Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Reschke, Millard F.; Clement, Gilles

    2006-01-01

    The effect of stimulus frequency on tilt and translation motion perception was studied during constant velocity off-vertical axis rotation (OVAR), and compared to the effect of stimulus frequency on eye movements. Fourteen healthy subjects were rotated in darkness about their longitudinal axis 10deg and 20deg off-vertical at 0.125 Hz, and 20deg offvertical at 0.5 Hz. Oculomotor responses were recorded using videography, and perceived motion was evaluated using verbal reports and a joystick with four degrees of freedom (pitch and roll tilt, mediallateral and anteriorposterior translation). During the lower frequency OVAR, subjects reported the perception of progressing along the edge of a cone. During higher frequency OVAR, subjects reported the perception of progressing along the edge of an upright cylinder. The modulation of both tilt recorded from the joystick and ocular torsion significantly increased as the tilt angle increased from 10deg to 20deg at 0.125 Hz, and then decreased at 0.5 Hz. Both tilt perception and torsion slightly lagged head orientation at 0.125 Hz. The phase lag of torsion increased at 0.5 Hz, while the phase of tilt perception did not change as a function of frequency. The amplitude of both translation perception recorded from the joystick and horizontal eye movements was negligible at 0.125 Hz and increased as a function of stimulus frequency. While the phase lead of horizontal eye movements decreased at 0.5 Hz, the phase of translation perception did not vary with stimulus frequency and was similar to the phase of tilt perception during all conditions. During dynamic linear acceleration in the absence of other sensory input (canal, vision) a change in stimulus frequency alone elicits similar changes in the amplitude of both self motion perception and eye movements. However, in contrast to the eye movements, the phase of both perceived tilt and translation motion is not altered by stimulus frequency. We conclude that the neural processing

  3. Modeling human vestibular responses during eccentric rotation and off vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    A mathematical model has been developed to help explain human multi-sensory interactions. The most important constituent of the model is the hypothesis that the nervous system incorporates knowledge of sensory dynamics into an "internal model" of these dynamics. This internal model allows the nervous system to integrate the sensory information from many different sensors into a coherent estimate of self-motion. The essence of the model is unchanged from a previously published model of monkey eye movement responses; only a few variables have been adjusted to yield the prediction of human responses. During eccentric rotation, the model predicts that the axis of eye rotation shifts slightly toward alignment with gravito-inertial force. The model also predicts that the time course of the perception of tilt following the acceleration phase of eccentric rotation is much slower than that during deceleration. During off vertical axis rotation (OVAR) the model predicts a small horizontal bias along with small horizontal, vertical, and torsional oscillations. Following OVAR stimulation, when stopped right- or left-side down, a small vertical component is predicted that decays with the horizontal post-rotatory response. All of the predictions are consistent with measurements of human responses.

  4. Off-vertical axis rotation: a test of the otolith-ocular reflex

    NASA Technical Reports Server (NTRS)

    Furman, J. M.; Schor, R. H.; Schumann, T. L.

    1992-01-01

    The vestibulo-ocular reflex was studied via off-vertical axis rotation (OVAR) in the dark. The axis of the turntable could be tilted from vertical by up to 30 degrees. Eye movements were measured with electro-oculography. Results from healthy asymptomatic subjects indicated that 1) a reliable otolith-induced response could be obtained during constant velocity OVAR using a velocity of 60 degrees/s with a tilt of 30 degrees; 2) constant velocity OVAR rotation was nausea-producing and, especially if subjects were rotated in the dark about an earth-vertical axis prior to being tilted, disorienting; and 3) sinusoidal OVAR produced minimal nausea; the eye movement response appeared to be the result of a combination of semicircular canal and otolith components. We conclude that OVAR has the potential of becoming a useful method for clinically assessing both the otolith-ocular reflex and semicircular canal-otolith interaction.

  5. Translational Vestibulo-Ocular Reflexes During Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Clement, Gilles

    2009-01-01

    The translational vestibulo-ocular reflex (tVOR) is an otolith-mediated response that stabilizes near vision during linear acceleration at higher frequencies where visually mediated reflexes are not adequate. The modulation of horizontal and vergence eye movements during Off-Vertical Axis Rotation (OVAR) are presumed to reflect the tVOR in response to the continuously varying linear acceleration in the interaural and nasooccipital axes, respectively. The purpose of this study was to examine the effect of frequency and fixation distance on the modulation of slow phase eye velocity (SPV) as further evidence that the tVOR is elicited during OVAR. Eighteen subjects were rotated about their longitudinal axis tilted by 30 deg off-vertical. Rotational velocities varied between 18 and 288 deg/sec corresponding to a frequency range of 0.05 to 0.8 Hz. Fixation distance was altered by asking subjects to imagine stationary targets that were briefly presented at 0.5, 1 and 2 m during some rotation cycles. The target flash was 40 msec in the nose-up position at eye level. Oculomotor responses were recorded in the dark using infrared binocular videography. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple rotation cycles. Consistent with previous studies, the modulation of both horizontal and vergence SPV increased with stimulus frequency. The effect of fixation distance was negligible at lower frequencies. The modulation of horizontal and vergence SPV was; however, proportional to fixation distance during OVAR at 0.8 Hz. This increasing sensitivity and dependence on fixation distance of horizontal and vergence SPV during OVAR is consistent with tVOR characteristics measured during other types of linear motion. We conclude that the modulation of horizontal and vergence SPV will be diagnostically more useful at higher stimulus frequencies where the tVOR is more robust.

  6. Time course and magnitude of illusory translation perception during off-vertical axis rotation.

    PubMed

    Vingerhoets, R A A; Medendorp, W P; Van Gisbergen, J A M

    2006-03-01

    Human spatial orientation relies on vision, somatosensory cues, and signals from the semicircular canals and the otoliths. The canals measure rotation, whereas the otoliths are linear accelerometers, sensitive to tilt and translation. To disambiguate the otolith signal, two main hypotheses have been proposed: frequency segregation and canal-otolith interaction. So far these models were based mainly on oculomotor behavior. In this study we investigated their applicability to human self-motion perception. Six subjects were rotated in yaw about an off-vertical axis (OVAR) at various speeds and tilt angles, in darkness. During the rotation, subjects indicated at regular intervals whether a briefly presented dot moved faster or slower than their perceived self-motion. Based on such responses, we determined the time course of the self-motion percept and characterized its steady state by a psychometric function. The psychophysical results were consistent with anecdotal reports. All subjects initially sensed rotation, but then gradually developed a percept of being translated along a cone. The rotation percept could be described by a decaying exponential with a time constant of about 20 s. Translation percept magnitude typically followed a delayed increasing exponential with delays up to 50 s and a time constant of about 15 s. The asymptotic magnitude of perceived translation increased with rotation speed and tilt angle, but never exceeded 14 cm/s. These results were most consistent with predictions of the canal-otolith-interaction model, but required parameter values that differed from the original proposal. We conclude that canal-otolith interaction is an important governing principle for self-motion perception that can be deployed flexibly, dependent on stimulus conditions.

  7. Modification of Eye Movements and Motion Perception during Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.; Denise, P.; CLement, G.

    2006-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity. The ensuing ocular reflexes include modulation of both torsional and horizontal eye movements as a function of the varying linear acceleration along the lateral plane, and modulation of vertical and vergence eye movements as a function of the varying linear acceleration along the sagittal plane. Previous studies have demonstrated that tilt and translation otolith-ocular responses, as well as motion perception, vary as a function of stimulus frequency during OVAR. The purpose of this study is to examine normative OVAR responses in healthy human subjects, and examine adaptive changes in astronauts following short duration space flight at low (0.125 Hz) and high (0.5 Hz) frequencies. Data was obtained on 24 normative subjects (14 M, 10 F) and 14 (13 M, 1F) astronaut subjects. To date, astronauts have participated in 3 preflight sessions (n=14) and on R+0/1 (n=7), R+2 (n= 13) and R+4 (n= 13) days after landing. Subjects were rotated in darkness about their longitudinal axis 20 deg off-vertical at constant rates of 45 and 180 deg/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with video-oculography. Perceived motion was evaluated using verbal reports and a two-axis joystick (pitch and roll tilt) mounted on top of a two-axis linear stage (anterior-posterior and medial-lateral translation). Eye responses were obtained in ten of the normative subjects with the head and trunk aligned, and then with the head turned relative to the trunk 40 deg to the right or left of center. Sinusoidal curve fits were used to derive amplitude, phase and bias of the responses over several cycles at each stimulus frequency. Eye responses during 0.125 Hz OVAR were dominated by modulation of torsional and vertical eye position, compensatory for tilt relative to gravity. While there is a bias horizontal slow phase velocity (SPV), the

  8. Compensatory and orienting eye movements induced by off-vertical axis rotation (OVAR) in monkeys.

    PubMed

    Kushiro, Keisuke; Dai, Mingjia; Kunin, Mikhail; Yakushin, Sergei B; Cohen, Bernard; Raphan, Theodore

    2002-11-01

    Nystagmus induced by off-vertical axis rotation (OVAR) about a head yaw axis is composed of a yaw bias velocity and modulations in eye position and velocity as the head changes orientation relative to gravity. The bias velocity is dependent on the tilt of the rotational axis relative to gravity and angular head velocity. For axis tilts <15 degrees, bias velocities increased monotonically with increases in the magnitude of the projected gravity vector onto the horizontal plane of the head. For tilts of 15-90 degrees, bias velocity was independent of tilt angle, increasing linearly as a function of head velocity with gains of 0.7-0.8, up to the saturation level of velocity storage. Asymmetries in OVAR bias velocity and asymmetries in the dominant time constant of the angular vestibuloocular reflex (aVOR) covaried and both were reduced by administration of baclofen, a GABA(B) agonist. Modulations in pitch and roll eye positions were in phase with nose-down and side-down head positions, respectively. Changes in roll eye position were produced mainly by slow movements, whereas vertical eye position changes were characterized by slow eye movements and saccades. Oscillations in vertical and roll eye velocities led their respective position changes by approximately 90 degrees, close to an ideal differentiation, suggesting that these modulations were due to activation of the orienting component of the linear vestibuloocular reflex (lVOR). The beating field of the horizontal nystagmus shifted the eyes 6.3 degrees /g toward gravity in side down position, similar to the deviations observed during static roll tilt (7.0 degrees /g). This demonstrates that the eyes also orient to gravity in yaw. Phases of horizontal eye velocity clustered ~180 degrees relative to the modulation in beating field and were not simply differentiations of changes in eye position. Contributions of orientating and compensatory components of the lVOR to the modulation of eye position and velocity were

  9. Phase-linking and the perceived motion during off-vertical axis rotation

    PubMed Central

    Wood, Scott J.; McCollum, Gin

    2010-01-01

    Human off-vertical axis rotation (OVAR) in the dark typically produces perceived motion about a cone, the amplitude of which changes as a function of frequency. This perception is commonly attributed to the fact that both the OVAR and the conical motion have a gravity vector that rotates about the subject. Little-known, however, is that this rotating-gravity explanation for perceived conical motion is inconsistent with basic observations about self-motion perception: (a) that the perceived vertical moves toward alignment with the gravito-inertial acceleration (GIA) and (b) that perceived translation arises from perceived linear acceleration, as derived from the portion of the GIA not associated with gravity. Mathematically proved in this article is the fact that during OVAR these properties imply mismatched phase of perceived tilt and translation, in contrast to the common perception of matched phases which correspond to conical motion with pivot at the bottom. This result demonstrates that an additional perceptual rule is required to explain perception in OVAR. This study investigates, both analytically and computationally, the phase relationship between tilt and translation at different stimulus rates—slow (45°/s) and fast (180°/s), and the three-dimensional shape of predicted perceived motion, under different sets of hypotheses about self-motion perception. We propose that for human motion perception, there is a phase-linking of tilt and translation movements to construct a perception of one’s overall motion path. Alternative hypotheses to achieve the phase match were tested with three-dimensional computational models, comparing the output with published experimental reports. The best fit with experimental data was the hypothesis that the phase of perceived translation was linked to perceived tilt, while the perceived tilt was determined by the GIA. This hypothesis successfully predicted the bottom-pivot cone commonly reported and a reduced sense of tilt

  10. Ocular Reflex Phase during Off-Vertical Axis Rotation in Humans is Modified by Head-Turn-On-Trunk Position

    PubMed Central

    Douglas, Samantha B.; Clément, Gilles; Denise, Pierre; Wood, Scott J.

    2017-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity, which generates a modulation of horizontal (conjugate and vergence), vertical, and torsional eye movements. We introduced the head-turn-on-trunk paradigm during OVAR to examine the extent to whether the modulation of these ocular reflexes is mediated by graviceptors in the head, i.e., otoliths, versus other body graviceptors. Ten human subjects were rotated in darkness about their longitudinal axis 20° off-vertical at a constant velocity of 45 and 180°/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with the head and trunk aligned, and then with the head turned relative to the trunk 40° to the right or left of center. The modulation of vertical and torsional eye position was greater at 0.125 Hz while the modulation of horizontal and vergence slow phase velocity was greater at 0.5 Hz. The amplitude modulation was not significantly altered by head-on-trunk position, but the phases shifted towards alignment with the head. These results are consistent with the modulation of ocular reflexes during OVAR being primarily mediated by the otoliths in response to the sinusoidally varying linear acceleration along the interaural and naso-occipital head axis. PMID:28176802

  11. Eye movements and motion perception induced by off-vertical axis rotation (OVAR) at small angles of tilt after spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, G.; Darlot, C.; Petropoulos, A.; Berthoz, A.

    1995-01-01

    The nystagmus and motion perception of two astronauts were recorded during Earth-vertical axis rotation and during off-vertical axis rotation (OVAR) before and after 7 days of spaceflight. Postflight, the peak velocity and duration of per- and postrotatory nystagmus during velocity steps about the Earth-vertical axis were the same as preflight values. During OVAR at constant velocity (45/s, tilt angles successively 5, 10, and 15 degrees), the mean horizontal slow-phase eye velocity (bias), produced by the 'velocity storage mechanism' in the vestibular system, and the peak-to-peak amplitude (modulation) in horizontal eye velocity and position, generated from the output of otolith afferents, were also the same before as after flight. There were, however, changes in the vertical eve position and in the perceived body motion during OVAR. The angle of the perceived body path described as a cone was larger in both astronauts postflight. One astronaut experienced either a large cone angle with its axis upright, or a smaller cone angle with its axis tilted backwards, accompanied by an upward vertical eye drift. These results suggest an increase in the sensitivity of the otolithic system after spaceflight and a longer period of readaptation to Earth's gravity for otolith-induced responses than for canal-induced responses. Our data support the hypothesis that just after spaceflight the CNS generally interprets changes in the otolith signals to be due to translation rather than to tilt.

  12. Ocular Reflex Phase During Off-Vertical Axis Rotation In Humans Is Modified By Head-On-Trunk Position

    NASA Technical Reports Server (NTRS)

    Wood, Scott; Clement, Gilles; Denise, Pierre; Reschke, Millard

    2005-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity. The ensuing ocular reflexes include modulation of both horizontal and torsional eye velocity as a function of the varying linear acceleration along the lateral plane. The purpose of this study was to examine whether the modulation of these ocular reflexes would be modified by different head-on-trunk positions. Ten human subjects were rotated in darkness about their longitudinal axis 20 deg off-vertical at constant rates of 45 and 180 deg/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with video-oculography with the head and trunk aligned, and then with the head turned relative to the trunk 40 deg to the right or left of center. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple cycles for each head-on-trunk position. Consistent with previous studies, the modulation of torsional eye movements was greater at 0.125 Hz while the modulation of horizontal eye movements was greater at 0.5 Hz. Neither amplitude nor bias velocities were significantly altered by head-on-trunk position. The phases of both torsional and horizontal ocular reflexes, on the other hand, shifted towards alignment with the head. These results are consistent with the modulation of torsional and horizontal ocular reflexes during OVAR being primarily mediated by the otoliths in response to the sinusoidally varying linear acceleration along the interaural head axis.

  13. Modulation of vergence by off-vertical yaw axis rotation in the monkey: normal characteristics and effects of space flight

    NASA Technical Reports Server (NTRS)

    Dai, M.; Raphan, T.; Kozlovskaya, I.; Cohen, B.

    1996-01-01

    Horizontal movements of both eyes were recorded simultaneously using scleral search coils in 2 rhesus monkeys before and after the COSMOS 2229 space-flight of 1992-1993. Another 9 monkeys were tested at comparable time intervals and served as controls. Ocular vergence, defined as the difference in horizontal position between the left and right eyes, was measured during off-vertical yaw axis rotation (OVAR) in darkness. Vergence was modulated sinusoidally as a function of head position with regard to gravity during OVAR. The amplitude of peak-to-peak modulation increased with increments in tilt of the angle of the rotational axis (OVAR tilt angle) that ranged from 15 degrees to 90 degrees. Of the 11 monkeys tested, 1 had no measurable modulation in vergence. In the other 10, the mean amplitude of the peak to peak modulation was 5.5 degrees +/- 1.3 degrees at 90 degrees tilt. Each of these monkeys had maximal vergence when its nose was pointed close to upward (gravity back; mean phase: -0.9 degree +/- 26 degrees). After space flight, the modulation in vergence was reduced by over 50% for the two flight monkeys, but the phase of vergence modulation was not altered. The reduction in vergence modulation was sustained for the 11-day postflight testing period. We conclude that changes in vergence are induced in monkeys by the sinusoidal component of gravity acting along the naso-occipital axis during yaw axis OVAR, and that the modulation of the vergence reflex is significantly less sensitive to linear acceleration after space flight.

  14. Human Ocular Counter-Rolling and Roll Tilt Perception during Off-Vertical Axis Rotation after Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Denise, Pierre; Reschke, Millard; Wood, Scott J.

    2007-01-01

    Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45 /s in darkness at two angles of tilt (10 and 20 ). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weigthing of the internal representation of gravitational vertical as a result of adaptation to microgravity.

  15. Neural basis for eye velocity generation in the vestibular nuclei of alert monkeys during off-vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Reisine, H.; Raphan, T.; Cohen, B. (Principal Investigator)

    1992-01-01

    Activity of "vestibular only" (VO) and "vestibular plus saccade" (VPS) units was recorded in the rostral part of the medial vestibular nucleus and caudal part of the superior vestibular nucleus of alert rhesus monkeys. By estimating the "null axes" of recorded units (n = 79), the optimal plane of activation was approximately the mean plane of reciprocal semicircular canals, i.e., lateral canals, left anterior-right posterior (LARP) canals or right anterior-left posterior (RALP) canals. All units were excited by rotation in a direction that excited a corresponding ipsilateral semicircular canal. Thus, they all displayed a "type I" response. With the animal upright, there were rapid changes in firing rates of both VO and VPS units in response to steps of angular velocity about a vertical axis. The units were bidirectionally activated during vestibular nystagmus (VN), horizontal optokinetic nystagmus (OKN), optokinetic after-nystagmus (OKAN) and off-vertical axis rotation (OVAR). The rising and falling time constants of the responses to rotation indicated that they were closely linked to velocity storage. There were differences between VPS and VO neurons in that activity of VO units followed the expected time course in response to a stimulus even during periods of drowsiness, when eye velocity was reduced. Firing rates of VPS units, on the other hand, were significantly reduced in the drowsy state. Lateral canal-related units had average firing rates that were linearly related to the bias or steady state level of horizontal eye velocity during OVAR over a range of +/- 60 deg/s. These units could be further divided into two classes according to whether they were modulated during OVAR. Non-modulated units (n = 5) were VO types and all modulated units (n = 5) were VPS types. There was no significant difference between the bias level sensitivities relative to eye velocity of the units with and without modulation (P > 0.05). The modulated units had no sustained change in

  16. Human ocular counter-rolling and roll tilt perception during off-vertical axis rotation after spaceflight.

    PubMed

    Clément, Gilles; Denise, Pierre; Reschke, Millard F; Wood, Scott J

    2007-01-01

    Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45 degrees/s in darkness at two angles of tilt (10 degrees and 20 degrees). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weighting of the internal representation of gravitational vertical as a result of adaptation to microgravity.

  17. Human otolith-ocular reflexes during off-vertical axis rotation: effect of frequency on tilt-translation ambiguity and motion sickness

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Paloski, W. H. (Principal Investigator)

    2002-01-01

    The purpose of this study was to examine how the modulation of tilt and translation otolith-ocular responses during constant velocity off-vertical axis rotation varies as a function of stimulus frequency. Eighteen human subjects were rotated in darkness about their longitudinal axis 30 degrees off-vertical at stimulus frequencies between 0.05 and 0.8 Hz. The modulation of torsion decreased while the modulation of horizontal slow phase velocity (SPV) increased with increasing frequency. It is inferred that the ambiguity of otolith afferent information is greatest in the frequency region where tilt (torsion) and translational (horizontal SPV) otolith-ocular responses crossover. It is postulated that the previously demonstrated peak in motion sickness susceptibility during linear accelerations around 0.3 Hz is the result of frequency segregation of ambiguous otolith information being inadequate to distinguish between tilt and translation.

  18. Three-dimensional organization of vestibular-related eye movements to off-vertical axis rotation and linear translation in pigeons

    NASA Technical Reports Server (NTRS)

    Dickman, J. D.; Angelaki, D. E.

    1999-01-01

    During linear accelerations, compensatory reflexes should 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 during linear accelerations produced by constant velocity off-vertical axis yaw rotations and translational motion in darkness. With off-vertical axis rotations, sinusoidally modulated eye-position and velocity responses were observed in all three components, with the vertical and torsional eye movements predominating the response. Peak torsional and vertical eye positions occurred when the head was oriented with the lateral visual axis of the right eye directed orthogonal to or aligned with the gravity vector, respectively. No steady-state horizontal nystagmus was obtained with any of the rotational velocities (8-58 degrees /s) tested. During translational motion, delivered along or perpendicular to the lateral visual axis, vertical and torsional eye movements were elicited. No significant horizontal eye movements were observed during lateral translation at frequencies up to 3 Hz. These responses suggest that, in pigeons, all linear accelerations generate eye movements that are compensatory to the direction of actual or perceived tilt of the head relative to gravity. In contrast, no translational horizontal eye movements, which are known to be compensatory to lateral translational motion in primates, were observed under the present experimental conditions.

  19. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. I. Linear acceleration responses during off-vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties

  20. Off-vertical rotation produces conditioned taste aversion and suppressed drinking in mice

    NASA Technical Reports Server (NTRS)

    Fox, R. A.; Lauber, A. H.; Daunton, N. G.; Phillips, M.; Diaz, L.

    1984-01-01

    The effects of off-vertical rotation upon the intake of tap water immediately after rotation and upon conditioned taste aversion were assessed in mice with the tilt of the rotation axis varying from 5 to 20 deg from the earth-vertical. Conditioned taste aversion occurred in all mice that were rotated, but the intake of tap water was suppressed only in mice that were rotated at 15 or 20 deg of tilt. The greater suppression of tap-water intake and the stronger conditioned aversion in the mouse as the angle of tilt was increased in this experiment are consistent with predictions from similar experiments with human subjects, where motion sickness develops more rapidly as the angle of tilt is increased. It was suggested that off-vertical rotation may be a useful procedure for insuring experimental control over vestibular stimulation in animal studies of motion sickness.

  1. Perception of the upright and susceptibility to motion sickness as functions of angle of tilt and angular velocity in off-vertical rotation. [human tolerance to angular accelerations

    NASA Technical Reports Server (NTRS)

    Miller, E. F., II; Graybiel, A.

    1973-01-01

    Motion sickness susceptibility of four normal subjects was measured in terms of duration of exposure necessary to evoke moderate malaise (MIIA) as a function of velocity in a chair rotated about a central axis tilted 10 deg with respect to gravitational upright. The subjects had little or no susceptibility to this type of rotation at 2.5 and 5.0 rpm, but with further increases in rate, the MIIA endpoint was always reached and with ever shorter test durations. Minimal provocative periods for all subjects were found at 15 or 20 rpm. Higher rotational rates dramatically reversed the vestibular stressor effect, and the subjects as a group tended to reach a plateau of relatively low susceptibility at 40 and 45 rpm. At these higher velocities, furthermore, the subjects essentially lost their sensation of being tilted off vertical. In the second half of the study, the effect of tilt angle was varied while the rotation rate was maintained at a constant 17.5 rpm. Two subjects were completely resistant to symptoms of motion sickness when rotated at 2.5 deg off vertical; with greater off-vertical angles, the susceptibility of all subjects increased sharply at first, then tapered off in a manner reflecting a Fechnerian function.

  2. Solar rotating magnetic dipole?. [around axis perpendicular to rotation axis of the sun

    NASA Technical Reports Server (NTRS)

    Antonucci, E.

    1974-01-01

    A magnetic dipole rotating around an axis perpendicular to the rotation axis of the sun can account for the characteristics of the surface large-scale solar magnetic fields through the solar cycle. The polarity patterns of the interplanetary magnetic field, predictable from this model, agree with the observed interplanetary magnetic sector structure.

  3. Actuator assembly including a single axis of rotation locking member

    DOEpatents

    Quitmeyer, James N.; Benson, Dwayne M.; Geck, Kellan P.

    2009-12-08

    An actuator assembly including an actuator housing assembly and a single axis of rotation locking member fixedly attached to a portion of the actuator housing assembly and an external mounting structure. The single axis of rotation locking member restricting rotational movement of the actuator housing assembly about at least one axis. The single axis of rotation locking member is coupled at a first end to the actuator housing assembly about a Y axis and at a 90.degree. angle to an X and Z axis providing rotation of the actuator housing assembly about the Y axis. The single axis of rotation locking member is coupled at a second end to a mounting structure, and more particularly a mounting pin, about an X axis and at a 90.degree. angle to a Y and Z axis providing rotation of the actuator housing assembly about the X axis. The actuator assembly is thereby restricted from rotation about the Z axis.

  4. Spin-stabilized magnetic levitation without vertical axis of rotation

    DOEpatents

    Romero, Louis; Christenson, Todd; Aaronson, Gene

    2009-06-09

    The symmetry properties of a magnetic levitation arrangement are exploited to produce spin-stabilized magnetic levitation without aligning the rotational axis of the rotor with the direction of the force of gravity. The rotation of the rotor stabilizes perturbations directed parallel to the rotational axis.

  5. Aircraft body-axis rotation measurement system

    NASA Technical Reports Server (NTRS)

    Cowdin, K. T. (Inventor)

    1983-01-01

    A two gyro four gimbal attitude sensing system having gimbal lock avoidance is provided with continuous azimuth information, rather than roll information, relative to the magnetic cardinal headings while in near vertical attitudes to allow recovery from vertical on a desired heading. The system is comprised of a means for stabilizing an outer roll gimbal that is common to a vertical gyro and a directional gyro with respect to the aircraft platform which is being angularly displaced about an axis substantially parallel to the outer roll gyro axis. A means is also provided for producing a signal indicative of the magnitude of such displacement as an indication of aircraft heading. Additional means are provided to cause stabilization of the outer roll gimbal whenever the pitch angle of the aircraft passes through a threshold prior to entering vertical flight and destabilization of the outer roll gimbal upon passing through the threshold when departing vertical flight.

  6. Registration of the rotation axis in X-ray tomography

    SciTech Connect

    Yang, Yimeng; Yang, Feifei; Hingerl, Ferdinand F.; Xiao, Xianghui; Liu, Yijin; Wu, Ziyu; Benson, Sally M.; Toney, Michael F.; Andrews, Joy C.; Pianetta, Piero A.

    2015-01-01

    There is high demand for efficient, robust and automated routines for tomographic data reduction, particularly for synchrotron data. Registration of the rotation axis in data processing is a critical step affecting the quality of the reconstruction and is not easily implemented with automation. Existing methods for calculating the center of rotation have been reviewed and an improved algorithm to register the rotation axis in tomographic data is presented. The performance of the proposed method is evaluated using synchrotron-based microtomography data on geological samples with and without artificial reduction of the signal-to-noise ratio. The proposed method improves the reconstruction quality by correcting both the tilting error and the translational offset of the rotation axis. The limitation of this promising method is also discussed.

  7. The axis of rotation of the ankle joint.

    PubMed

    Lundberg, A; Svensson, O K; Németh, G; Selvik, G

    1989-01-01

    The axis of the talo-crural joint was analysed by roentgen stereophotogrammetry in eight healthy volunteers. Examinations were performed at 10 degrees increments of flexion and pronation/supination of the foot as well as medial and lateral rotation of the leg. Results indicate that the talo-crural joint axis changes continuously throughout the range of movement. In dorsiflexion it tended to be oblique downward and laterally. In rotation of the leg, the axis took varying inclinations between horizontal and vertical. All axes in each subject lay close to the midpoint of a line between the tips of the malleoli. Our study indicates that the talo-crural joint axis may alter considerably during the arc of motion and differ significantly between individuals. This prompts caution in the use of hinge axes in orthoses and prostheses for the ankle.

  8. Surface acoustic wave micromotor with arbitrary axis rotational capability

    NASA Astrophysics Data System (ADS)

    Tjeung, Ricky T.; Hughes, Mark S.; Yeo, Leslie Y.; Friend, James R.

    2011-11-01

    A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

  9. X- And y-axis driver for rotating microspheres

    DOEpatents

    Weinstein, Berthold W.

    1979-01-01

    Apparatus for precise control of the motion and position of microspheres for examination of their interior and/or exterior. The apparatus includes an x- and y-axis driver mechanism controlled, for example, by a minicomputer for selectively rotating microspheres retained between a pair of manipulator arms having flat, smooth end surfaces. The driver mechanism includes an apertured plate and ball arrangement which provided for coupled equal and opposite movement of the manipulator arms in two perpendicular directions.

  10. 24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR SHEAVE, MOTOR, BRAKE, PINION SHAFT, DRIVE WHEEL. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

  11. A Singular Limit Problem for Rotating Capillary Fluids with Variable Rotation Axis

    NASA Astrophysics Data System (ADS)

    Fanelli, Francesco

    2016-12-01

    In the present paper we study a singular perturbation problem for a Navier-Stokes-Korteweg model with Coriolis force. Namely, we perform the incompressible and fast rotation asymptotics simultaneously, while we keep the capillarity coefficient constant in order to capture surface tension effects in the limit. We consider here the case of variable rotation axis: we prove the convergence to a linear parabolic-type equation with variable coefficients. The proof of the result relies on compensated compactness arguments. Besides, we look for minimal regularity assumptions on the variations of the axis.

  12. Implementation of Unsteady Double-Axis of Rotation Motion to Predict Pitch-Damping Moment

    DTIC Science & Technology

    2016-10-18

    10 Fig. 9 File -based body spinning rotation motion ...........................................11 Fig. 10 The 6...The rotation about the body axis (spinning motion) is setup using the “ File -Based Single-Axis Rotational motion” option, and the rotation about the...After clicking on “Details” for “ File -Based Single-Axis Rotational motion (body frame)”, the user is prompted for the number of sets of grid velocity

  13. Excitation of the earth's rotational axis by recent glacial discharges

    NASA Technical Reports Server (NTRS)

    Gasperini, P.; Sabadini, R.; Yuen, D. A.

    1986-01-01

    The effects of present-day glacial discharges and the growth of the Antarctic ice sheet on exciting the earth's rotational axis are studied. Glacial forcing could cause a maximum change in J2 of about one-third of the observed amount, for the Maxwell rheology and for Burgers' body models with a long-term, lower-mantle viscosity greater than about 10 to the 23rd P. For transient rheologies the amount of excitation due to glacial melting decreases. Polar wander is not much excited by recent glacial melting for the various types of rheologies examined.

  14. Tilt of the radius from forearm rotational axis reliably predicts rotational improvement after corrective osteotomy for malunited forearm fractures.

    PubMed

    Tatebe, Masahiro; Shinohara, Takaaki; Okui, Nobuyuki; Yamamoto, Michiro; Kurimoto, Shigeru; Hirata, Hitoshi

    2012-02-01

    Forearm rotation occurs around an axis connecting the center of the radial head and the fovea of the distal ulna. The purpose of the present study was to demonstrate the usefulness of the difference between forearm and proximal radial axis in the treatment of malunited forearm fractures. We reviewed the results of eight corrective osteotomies for malunited fractures of the forearm without dislocations of the wrist or elbow. Subjects were 6 men and 2 women (mean age, 15 years; range, 10-21 years). Corrective osteotomy was performed at the fracture site. Preoperatively and at final follow-up, the are of forearm rotation was recorded and anteroposterior and lateral X-rays were taken. Proximal radius tilt was defined as the angle between the rotational axis of the forearm and the axis of the proximal radius. Corrective osteotomy improved proximal radius tilt in all cases. Three patients were considered to have malrotation. Postoperative rotational are correlated with proximal radial tilt (r = -0.83). No significant difference in rotational arc was evident between malunited cases and the remaining cases. To improve forearm rotation, corrective osteotomy should be planned to minimize proximal radius tilt.

  15. Polynomial shape of an inclined ellipsoid with rotational symmetry about its major axis.

    PubMed

    Castañeda-Escobar, Lizbeth A; Malacara-Hernández, Daniel

    2006-08-01

    We present the approximate polynomial expression for an ellipsoid with rotational symmetry about its major axis, which is on the y-z plane and at angle theta with respect to the z axis. These expressions have many possible useful applications in optics as shown. The main optical properties of these types of inclined ellipsoidal surface will be reviewed.

  16. Effect of Rotational Axis Position of Wheelchair Back Support on Shear Force when Reclining

    PubMed Central

    Kobara, Kenichi; Osaka, Hiroshi; Takahashi, Hisashi; Ito, Tomotaka; Fujita, Daisuke; Watanabe, Susumu

    2014-01-01

    [Purpose] The purpose of this study was to investigate the influence of the rotational axis position of a reclining wheelchair’s back support on fluctuations in the shear force applied to the buttocks while the back support is reclined. [Subjects] The subjects were 12 healthy adult men. [Methods] The shear force applied to the buttocks was measured using a force plate. This study used two different experimental conditions. The rotational axis of the back support was positioned at the joint between the seat and the back support for the rear-axis condition, and was moved 13 cm forward for the front-axis condition. [Results] With the back support fully reclined, the shear forces were 11.2 ± 0.8%BW and 14.1 ± 2.5%BW under the rear-axis and front-axis conditions, respectively. When returned to an upright position, the shear forces were 17.1 ± 3.1%BW and 13.8 ± 1.7%BW under the rear-axis and front-axis conditions, respectively. Significant differences appeared between the two experimental conditions (p < 0.01). [Conclusion] These results suggest that the shear force value could be changed by altering the position of the back support’s rotational axis during reclining. PMID:24926135

  17. Tilted axis rotation in odd-odd {sup 164}Tm

    SciTech Connect

    Reviol, W.; Riedinger, L.L.; Wang, X.Z.; Zhang, J.Y.

    1996-12-31

    Ten band structures are observed in {sup 164}Tm, among them sets of parallel and anti-parallel couplings of the proton and neutron spins. The Tilted Axis Cranking scheme is applied for the first time to an odd-odd nucleus in a prominent region of nuclear deformation.

  18. Rotation Angle for the Optimum Tracking of One-Axis Trackers

    SciTech Connect

    Marion, W. F.; Dobos, A. P.

    2013-07-01

    An equation for the rotation angle for optimum tracking of one-axis trackers is derived along with equations giving the relationships between the rotation angle and the surface tilt and azimuth angles. These equations are useful for improved modeling of the solar radiation available to a collector with tracking constraints and for determining the appropriate motor revolutions for optimum tracking.

  19. Displacements and rotations of a body moving about an arbitrary axis in a global reference frame

    SciTech Connect

    Hollerbach, K.; Hollister, A.

    1995-11-01

    Measurement of human joint motion frequently involves the use of markers to describe joint motion in a global reference frame. Results may be quite arbitrary if the reference frame is not properly chosen with respect to the joint`s rotational axis(es). In nature joint axes can exist at any orientation and location relative to an arbitrarily chosen global reference frame. An arbitrary axis is any axis that is not coincident with a reference coordinate. Calculations are made of the errors that result when joint motion occurs about an arbitrary axis in a global reference frame.

  20. Binocular Coordination of the Human Vestibulo-Ocular Reflex during Off-axis Pitch Rotation

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.; Kaufman, G. D.; Black, F. O.; Paloski, W. H.

    2006-01-01

    Head movements in the sagittal pitch plane typically involve off-axis rotation requiring both vertical and horizontal vergence ocular reflexes to compensate for angular and translational motion relative to visual targets of interest. The purpose of this study was to compare passive pitch VOR responses during rotation about an Earth-vertical axis (canal only cues) with off-axis rotation (canal and otolith cues). Methods. Eleven human subjects were oscillated sinusoidally at 0.13, 0.3 and 0.56 Hz while lying left-side down with the interaural axis either aligned with the axis of rotation or offset by 50 cm. In a second set of measurements, twelve subjects were also tested during sinusoidally varying centrifugation over the same frequency range. The modulation of vertical and horizontal vergence ocular responses was measured with a binocular videography system. Results. Off-axis pitch rotation enhanced the vertical VOR at lower frequencies and enhanced the vergence VOR at higher frequencies. During sinusoidally varying centrifugation, the opposite trend was observed for vergence, with both vertical and vergence vestibulo-ocular reflexes being suppressed at the highest frequency. Discussion. These differential effects of off-axis rotation over the 0.13 to 0.56 Hz range are consistent with the hypothesis that otolith-ocular reflexes are segregated in part on the basis of stimulus frequency. At the lower frequencies, tilt otolith-ocular responses compensate for declining canal input. At higher frequencies, translational otolith-ocular reflexes compensate for declining visual contributions to the kinematic demands required for fixating near targets.

  1. Tidal friction and generalized Cassini's laws in the solar system. [for planetary spin axis rotation

    NASA Technical Reports Server (NTRS)

    Ward, W. R.

    1975-01-01

    The tidal drift toward a generalized Cassini state of rotation of the spin axis of a planet or satellite in a precessing orbit is described. Generalized Cassini's laws are applied to several solar system objects and the location of their spin axes estimated. Of those considered only the moon definitely occupies state 2 with the spin axis near to the normal of the invariable plane. Most objects appear to occupy state 1 with the spin axis near to the orbit normal. Iapetus could occupy either state depending on its oblateness. In addition, the resonant rotation of Mercury is found to have little effect on the tidal drift of its spin axis toward state 1.

  2. Large Vertical Axis Rotations along Neotethyan Sutures in TURKEY

    NASA Astrophysics Data System (ADS)

    Ozkaptan, M.; Gulyuz, E.; Kaymakci, N.; Langereis, C. G.; Ozacar, A. A.; Lefebvre, C.

    2014-12-01

    Two Neotethyan Sutures,Izmir-Ankara and Intra-Tauride suture zones meet around Ankara region appx. at right angles.The northerly located Izmir-Ankara Suture zone follows approximately E-W trend and it makes a sharp approximately 90° bend at the east along the western margin of the Çankiri Basin.The Intra-Tauride suture follows approximately the Tuzgölü Fault Zone and trends NW-SE and seems to be overprinted by the structures related to the Izmir-Ankara suture zone. These two sutures meet southeastern corner of the Haymana Basin where the basin makes major eastwards counterclockwise bend.From west to East, the Haymana, Tuzgölü and Çankiri Basins straddle these suture zones and are developed in relation to the subduction and collision processes in the region, making them the perfect sites to unravel deformation history and paleogeography of the Neotethyan suture zones in the region. In order to accomplish this, the tectono-stratigraphic evolution of the basin and its paleogeographical positions, in different time slices, constructed by conducting a very detailed study on the Late Cretaceous to Recent infill of the Haymana, Tuzgölü, and Çankiri Basins. We collected more than 4500 sedimentary paleomagnetic samples for paleomagnetic purposes from 112 different locations within 250 km diameter area.Before the demagnetization process, nearly 3000 core specimens were measured for anisotropy of magnetic susceptibility (AMS) in order to understand deformation amounts and kinematics.The paleomagnetic results show that the region underwent strong clockwise and counterclockwise rotations more than 90° in places, resulting in the present geometry of the suture zones. The central part of the Haymana basin rotated as high as 90° counterclockwise while its northern part together with the southwestern part of the Çankiri basin and northern part of the Tuzgölü basin rotated approximately 30° clockwise contrary to almost all published paleomagnetic data from the region

  3. Earth horizontal axis rotational responses in patients with unilateral peripheral vestibular deficits

    NASA Technical Reports Server (NTRS)

    Furman, Joseph M. R.; Kamerer, Donald B.; Wall, Conrad, III

    1989-01-01

    The vestibulo-ocular reflex (VOR) of five patients with surgically confirmed unilateral peripheral vestibular lesions is evaluated. Testing used both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotation. Results indicated that the patients had short VOR time constants, asymmetric responses to both EVA and EHA rotation, and normal EHA modulation components. These findings suggest that unilateral peripheral vestibular loss causes a shortened VOR time constant even with the addition of dynamic otolithic stimulation and causes an asymmetry in semicircular canal-ocular reflexes and one aspect of otolith-ocular reflexes.

  4. Nystagmus responses in a group of normal humans during earth-horizontal axis rotation

    NASA Technical Reports Server (NTRS)

    Wall, Conrad, III; Furman, Joseph M. R.

    1989-01-01

    Horizontal eye movement responses to earth-horizontal yaw axis rotation were evaluated in 50 normal human subjects who were uniformly distributed in age (20-69 years) and each age group was then divided by gender. Subjects were rotated with eyes open in the dark, using clockwise and counter-clockwise 60 deg velocity trapezoids. The nystagmus slow component velocity is analyzed. It is shown that, despite large intersubject variability, parameters which describe earth-horizontal yaw axis responses are loosely interrelated, and some of them vary significantly with gender and age.

  5. Dual-axis 360° rotation specimen holder for analysis of three-dimensional magnetic structures.

    PubMed

    Tsuneta, Ruriko; Kashima, Hideo; Iwane, Tomohiro; Harada, Ken; Koguchi, Masanari

    2014-12-01

    A dual-axis 360° rotation specimen holder was developed for use in reconstructing the three-dimensional (3D) distribution of a magnetic field using a combination of electron holography and tomography. Pillar-shaped specimens are used to obtain accurate reconstruction without a missing angle. The holder's rotation rod can be turned >360°; the pillar is set ±45° to the azimuth for both x- and y-axis rotation. Two rotation series of holograms in individual axes are recorded for vector field tomography. The two vector components of the magnetic field are reconstructed directly from the two series of holograms, and the remaining component is calculated using Maxwell's equation, div B = 0. As a result, all 3D magnetic fields are reconstructed.

  6. Accurate Compensation of Attitude Angle Error in a Dual-Axis Rotation Inertial Navigation System

    PubMed Central

    Jiang, Rui; Yang, Gongliu; Zou, Rui; Wang, Jing; Li, Jing

    2017-01-01

    In the dual-axis rotation inertial navigation system (INS), besides the gyro error, accelerometer error, rolling misalignment angle error, and the gimbal angle error, the shaft swing angle and the axis non-orthogonal angle also affect the attitude accuracy. Through the analysis of the structure, we can see that the shaft swing angle and axis non-orthogonal angle will produce coning errors which cause the fluctuation of the attitude. According to the analysis of the rotation vector, it can be seen that the coning error will generate additional drift velocity along the rotating shaft, which can reduce the navigation precision of the system. In this paper, based on the establishment of the modulation average frame, the vector projection is carried out, and then the attitude conversion matrix and the attitude error matrix mainly including the shaft swing angle and axis non-orthogonal are obtained. Because the attitude angles are given under the static condition, the shaft swing angle and the axis non-orthogonal angle are estimated by the static Kalman filter (KF). This kind of KF method has been widely recognized as the standard optimal estimation tool for estimating the parameters such as coning angles (α1 , α2), initial phase angles (ϕ1,ϕ2), and the non-perpendicular angle (η). In order to carry out the system level verification, a dual axis rotation INS is designed. Through simulation and experiments, the results show that the amplitudes of the attitude angles’ variation are reduced by about 20%–30% when the shaft rotates. The attitude error equation is reasonably simplified and the calibration method is accurate enough. The attitude accuracy is further improved. PMID:28304354

  7. Accurate Compensation of Attitude Angle Error in a Dual-Axis Rotation Inertial Navigation System.

    PubMed

    Jiang, Rui; Yang, Gongliu; Zou, Rui; Wang, Jing; Li, Jing

    2017-03-17

    In the dual-axis rotation inertial navigation system (INS), besides the gyro error, accelerometer error, rolling misalignment angle error, and the gimbal angle error, the shaft swing angle and the axis non-orthogonal angle also affect the attitude accuracy. Through the analysis of the structure, we can see that the shaft swing angle and axis non-orthogonal angle will produce coning errors which cause the fluctuation of the attitude. According to the analysis of the rotation vector, it can be seen that the coning error will generate additional drift velocity along the rotating shaft, which can reduce the navigation precision of the system. In this paper, based on the establishment of the modulation average frame, the vector projection is carried out, and then the attitude conversion matrix and the attitude error matrix mainly including the shaft swing angle and axis non-orthogonal are obtained. Because the attitude angles are given under the static condition, the shaft swing angle and the axis non-orthogonal angle are estimated by the static Kalman filter (KF). This kind of KF method has been widely recognized as the standard optimal estimation tool for estimating the parameters such as coning angles (α₁ , α₂), initial phase angles (ϕ₁,ϕ₂), and the non-perpendicular angle (η). In order to carry out the system level verification, a dual axis rotation INS is designed. Through simulation and experiments, the results show that the amplitudes of the attitude angles' variation are reduced by about 20%-30% when the shaft rotates. The attitude error equation is reasonably simplified and the calibration method is accurate enough. The attitude accuracy is further improved.

  8. Visual-vestibular interaction in humans during earth-horizontal axis rotation

    NASA Technical Reports Server (NTRS)

    Wall, Conrad, III; Furman, Joseph M. R.

    1990-01-01

    Visual-vestibular interaction using 60 percent constant velocity earth horizontal axis yaw rotation, simulating both the horizontal semicircular canals and the otolith organs, was measured in seven human subjects. Subjects were tested with their eyes open in the dark (EOD) while fixating upon a target rotating with them (FIX), and while observing stationary optokinetic stripes (VVR). Resulting nystagmus slow component velocity (SCV) was analyzed for EOD, FIX, and VVR conditions. It is concluded that the visual-vestibular interactions during EHA differ significantly from those during rotation about the vertical; specifically, there is a nonlinear interaction between linear acceleration and optokinetic nystagmus.

  9. Measurement of angle and axis of rotation in a carousel interferometer: a detailed analysis

    SciTech Connect

    Hussain, Ghazanfar; Ikram, Masroor

    2010-02-20

    A detailed analysis of a carousel interferometer is presented for the measurement of an unknown angle and axis of rotation. The technique exploits a set of compensator glass plates and a right-angle prism that is placed in each of the two arms of the interferometer. The two sets are placed at the same rotational stage, while the end mirrors of the interferometer are static. When rotation takes place, individual and relative optical path differences are generated in the two beams of the interferometer. The generated phase differences contribute toward finding the angle and axis of rotation. The analysis is presented for any initial position of the interferometer, i.e., the radial vector from the axis of rotation to the apex of one of the prisms used. The results show the slight variations in the error and nonlinearity when different parameters are manipulated. Moreover, the trade-off between the maximum size of the prisms and the radial distances are also presented.

  10. Attitude heading reference system using MEMS inertial sensors with dual-axis rotation.

    PubMed

    Kang, Li; Ye, Lingyun; Song, Kaichen; Zhou, Yang

    2014-09-29

    This paper proposes a low cost and small size attitude and heading reference system based on MEMS inertial sensors. A dual-axis rotation structure with a proper rotary scheme according to the design principles is applied in the system to compensate for the attitude and heading drift caused by the large gyroscope biases. An optimization algorithm is applied to compensate for the installation angle error between the body frame and the rotation table's frame. Simulations and experiments are carried out to evaluate the performance of the AHRS. The results show that the proper rotation could significantly reduce the attitude and heading drifts. Moreover, the new AHRS is not affected by magnetic interference. After the rotation, the attitude and heading are almost just oscillating in a range. The attitude error is about 3° and the heading error is less than 3° which are at least 5 times better than the non-rotation condition.

  11. Attitude Heading Reference System Using MEMS Inertial Sensors with Dual-Axis Rotation

    PubMed Central

    Kang, Li; Ye, Lingyun; Song, Kaichen; Zhou, Yang

    2014-01-01

    This paper proposes a low cost and small size attitude and heading reference system based on MEMS inertial sensors. A dual-axis rotation structure with a proper rotary scheme according to the design principles is applied in the system to compensate for the attitude and heading drift caused by the large gyroscope biases. An optimization algorithm is applied to compensate for the installation angle error between the body frame and the rotation table's frame. Simulations and experiments are carried out to evaluate the performance of the AHRS. The results show that the proper rotation could significantly reduce the attitude and heading drifts. Moreover, the new AHRS is not affected by magnetic interference. After the rotation, the attitude and heading are almost just oscillating in a range. The attitude error is about 3° and the heading error is less than 3° which are at least 5 times better than the non-rotation condition. PMID:25268911

  12. A self-calibration method for tri-axis rotational inertial navigation system

    NASA Astrophysics Data System (ADS)

    Gao, Pengyu; Li, Kui; Wang, Lei; Liu, Zengjun

    2016-11-01

    The navigation accuracy of the rotational inertial navigation system (RINS) could be greatly improved by periodically rotating the inertial measurement unit (IMU) with gimbals. However, error parameters in RINS should be effectively calibrated and compensated. In this paper, a self-calibration method is proposed for tri-axis RINS using attitude errors and velocity errors as measurements. The proposed calibration scheme is designed as three separate steps, and a certain gimbal rotates continuously in each step. All the error parameters in the RINS are calibrated when the whole scheme finishes. The separate calibration steps reduce the correlations between error parameters, and the observability of errors in this method is clear to demonstrate according to the relations between navigation errors and error parameters when gimbals rotate. Each calibration step only lasts 12 min, thus gyro drifts and accelerometers biases could be regarded as constant. The proposed calibration scheme is tested in both simulation and actual tri-axis RINS, and simulation and experimental results show that all 23 error parameters could be well estimated in tri-axis RINS. A long-term vehicle navigation experiment results show that after calibration and compensation, the navigation performance has doubled approximately, and the velocity accuracy is less than 2 m s-1 while the position accuracy is less than 1500 m, fully illustrating the significance of the proposed self-calibration method in improving the navigation performance of RINS.

  13. Is the earth's dipole actually inclined with respect to the rotation axis?

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.; Saito, T.

    1990-01-01

    Planetary exploration by deep space probes in recent years has shown that the dipole moment of some magnetized planets has a surprisingly large inclination angle with respect to the rotation axis. Applying the method developed for the source surface magnetic field of the sun (a spherical surface of 2.5 solar radii), it is suggested that the main dipole of the earth and the magnetized planets may actually be axial (the magnetic moment being parallel or antiparallel to the rotation axis), and that two or three smaller dipoles near the core surface could be responsible for the apparent inclination of the main dipole. In formulating a dynamo theory of the planetary magnetic field, such a possibility should be considered, as well as the inclined dipole case.

  14. Magnetic and antimagnetic rotation in 110Cd within tilted axis cranking relativistic mean-field theory

    NASA Astrophysics Data System (ADS)

    Peng, J.; Zhao, P. W.

    2015-04-01

    The self-consistent tilted axis cranking relativistic mean-field (TAC-RMF) theory based on a point-coupling interaction is applied to investigate the observed magnetic and antimagnetic rotations in the nucleus 110Cd . The energy spectra, the relation between the spin and the rotational frequency, the deformation parameters, and the reduced M 1 and E 2 transition probabilities are studied with the various configurations. It is found that the configuration has to be changed to reproduce the energy spectra and the relations between the spin and the rotational frequency for both the magnetic and antimagnetic rotational bands. The shears mechanism for the magnetic rotation and the two-shears-like mechanism for the antimagnetic rotation are examined by investigating the orientation of the neutron and proton angular momenta. The calculated electromagnetic transitions B (M 1 ) and B (E 2 ) are in reasonable agreement with the data, and their tendencies are coincident with the typical characteristics of the magnetic and antimagnetic rotations.

  15. Posterior Cortical Axis: A New Landmark to Control Femoral Component Rotation in Total Knee Arthroplasty.

    PubMed

    Matziolis, Doerte; Meiser, Marius; Sieber, Norbert; Teichgräber, Ulf; Matziolis, Georg

    2017-01-20

    Rotation errors of the femoral component are held responsible for occurrences such as instability in flexion and midflexion, patellar maltracking, and arthrofibrosis following total knee arthroplasty. However, in many cases, the epicondylar axis cannot be reliably identified due to bone defects or metal artifacts on computed tomography, so alternative landmarks are necessary to evaluate the femoral component rotation. The current study sought to determine the relationship of the posterior cortical bone and the anterior cortical bone in relation to the epicondylar axis. In this retrospective study, 398 consecutive patients who had undergone magnetic resonance imaging of the knee joint were included. The average angle between the posterior cortical bone and the epicondylar axis was 7.3°±3.3°. When the posterior cortical bone was used as the reference, the average absolute error was 2.6°±2.1°. In comparison, the average angle between the anterior cortical bone and epicondylar axis was 10.4°±4.5°. When this reference was used, the average absolute error was 3.6°±2.8°. The posterior cortical bone is a more consistent landmark than the anterior cortical bone is for intra- or postoperative approximation of the epicondylar axis. This appears to be due to the flat geometry of the posterior cortical bone compared with the elliptical form of the anterior cortical bone of the distal femur. In practice, an external rotation of the femoral component of 7° in relation to the posterior cortical bone is to be recommended. [Orthopedics. 201x; xx(x):xx-xx.].

  16. Automatic Mass Balancing of Air-Bearing-Based Three-Axis Rotational Spacecraft Simulator

    DTIC Science & Technology

    2009-06-01

    are capable of providing 1 rotational and 2 translational degrees of freedom and they are often used for simulations of formation flying, rendezvous ...requires approximately 70 psi to float the approximately 800 kg of the simulator. The z axis of the spacecraft body is aligned with the direction of...the four different attitude values of jhj=t in Fig. 8. As shown in [24] with an approximately 200-kg spacecraft simulator, a good manual balancing

  17. Measurements of isocenter path characteristics of the gantry rotation axis with a smartphone application

    SciTech Connect

    Schiefer, H. Peters, S.; Plasswilm, L.; Ingulfsen, N.; Kluckert, J.

    2015-03-15

    Purpose: For stereotactic radiosurgery, the AAPM Report No. 54 [AAPM Task Group 42 (AAPM, 1995)] requires the overall stability of the isocenter (couch, gantry, and collimator) to be within a 1 mm radius. In reality, a rotating system has no rigid axis and thus no isocenter point which is fixed in space. As a consequence, the isocenter concept is reviewed here. It is the aim to develop a measurement method following the revised definitions. Methods: The mechanical isocenter is defined here by the point which rotates on the shortest path in the room coordinate system. The path is labeled as “isocenter path.” Its center of gravity is assumed to be the mechanical isocenter. Following this definition, an image-based and radiation-free measurement method was developed. Multiple marker pairs in a plane perpendicular to the assumed gantry rotation axis of a linear accelerator are imaged with a smartphone application from several rotation angles. Each marker pair represents an independent measuring system. The room coordinates of the isocenter path and the mechanical isocenter are calculated based on the marker coordinates. The presented measurement method is by this means strictly focused on the mechanical isocenter. Results: The measurement result is available virtually immediately following completion of measurement. When 12 independent measurement systems are evaluated, the standard deviations of the isocenter path points and mechanical isocenter coordinates are 0.02 and 0.002 mm, respectively. Conclusions: The measurement is highly accurate, time efficient, and simple to adapt. It is therefore suitable for regular checks of the mechanical isocenter characteristics of the gantry and collimator rotation axis. When the isocenter path is reproducible and its extent is in the range of the needed geometrical accuracy, it should be taken into account in the planning process. This is especially true for stereotactic treatments and radiosurgery.

  18. Simulation of winds as seen by a rotating vertical axis wind turbine blade

    SciTech Connect

    George, R.L.

    1984-02-01

    The objective of this report is to provide turbulent wind analyses relevant to the design and testing of Vertical Axis Wind Turbines (VAWT). A technique was developed for utilizing high-speed turbulence wind data from a line of seven anemometers at a single level to simulate the wind seen by a rotating VAWT blade. Twelve data cases, representing a range of wind speeds and stability classes, were selected from the large volume of data available from the Clayton, New Mexico, Vertical Plane Array (VPA) project. Simulations were run of the rotationally sampled wind speed relative to the earth, as well as the tangential and radial wind speeds, which are relative to the rotating wind turbine blade. Spectral analysis is used to compare and assess wind simulations from the different wind regimes, as well as from alternate wind measurement techniques. The variance in the wind speed at frequencies at or above the blade rotation rate is computed for all cases, and is used to quantitatively compare the VAWT simulations with Horizontal Axis Wind Turbine (HAWT) simulations. Qualitative comparisons are also made with direct wind measurements from a VAWT blade.

  19. Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1996-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force.

  20. Wall transpiration on mixed convection heat transfer in a square duct rotating about a parallel axis

    SciTech Connect

    Yan, W.M.; Lee, K.T.

    1997-07-01

    A detailed numerical study, using the vorticity-velocity method, has been carried out to examine the wall transpiration on mixed convection flow and heat transfer in a square duct rotating about a parallel axis. The prediction was presented for various parameters, wall Reynolds number Re{sub w}, rotational Reynolds number J, and rotational Grashof number Gr{sub {Omega}}. Typical developments of axial velocity, secondary flow, and temperature at various axial locations in the entrance region are presented. Both local circumferentially averaged friction factors f Re and Nusselt number N u in the developing region are examined. The predicted results disclosed that the wall transpiration effect has considerable impact on the flow and heat transfer characteristics. Results also showed that both circumferentially averaged friction factor and Nusselt number are enhanced with an increase in J or Gr{sub {Omega}}, except for the range of J < 400 or Gr{sub {Omega}} < 1,000.

  1. Periodicity Signatures of Lightcurves of Active Comets in Non-Principal-Axis Rotational States

    NASA Astrophysics Data System (ADS)

    Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Barrera, Jose G.

    2016-10-01

    There are two comets (1P/Halley, 103P/Hartley 2) that are unambiguously in non-principal-axis (NPA) rotational states in addition to a few more comets that are candidates for NPA rotation. Considering this fact, and the ambiguities associated with how to accurately interpret the periodicity signatures seen in lightcurves of active comets, we have started an investigation to identify and characterize the periodicity signatures present in simulated lightcurves of active comets. We carried out aperture photometry of simulated cometary comae to generate model lightcurves and analyzed them with Fourier techniques to identify their periodicity signatures. These signatures were then compared with the input component periods of the respective NPA rotational states facilitating the identification of how these periodicity signatures are related to different component periods of the NPA rotation. Ultimately, we also expect this study to shed light on why only a small fraction of periodic comets is in NPA rotational states, whereas theory indicates a large fraction of them should be in NPA states (e.g., Jewitt 1999, EMP, 79, 35). We explore the parameter space with respect to different rotational states, different orientations for the total rotational angular momentum vector, and different locations on the nucleus for the source region(s). As for special cases, we also investigate potential NPA rotational states representative of comet 103P/Hartley2, the cometary target of the EPOXI mission. The initial results from our investigation will be presented at the meeting. The NASA DDAP Program supports this work through grant NNX15AL66G.

  2. Physiological mechanisms of the nystagmus produced by rotations about an earth-horizontal axis

    NASA Technical Reports Server (NTRS)

    Goldberg, J. M.; Fernandez, C.

    1981-01-01

    The physiological basis of the nystagmus produced by rotation about an earth-horizontal axis is investigated with particular emphasis on the unidirectional nystagmus attributed to a bias component. Eye movement recordings were made with dc electro-oculography in alert squirrel monkeys and afferent responses were recorded from semicircular canals and otolith receptors of anesthetized animals upon rotations in the pitch and yaw planes. The eye-movement recordings show the rotation responses in the squirrel monkey to resemble those of other species, including persistent horizontal and vertical nystagmuses during yaw and pitch rotations, respectively, a unidirectional nystagmus at low rotation speeds, and postrotatory responses of relatively small amplitude and duration. The vestibular nerve recordings do not show a directionally specific dc response that can account for the bias component, but instead exhibit sinusoidal responses of peak amplitudes 0-15 and 25-75 spikes/sec for the canals and otolith, respectively. Results thus indicate that the dc signal to the oculomotor centers responsible for the nystagmus is of central origin, most likely based on some transformation of the otolith signals.

  3. Single-cell diffraction tomography with optofluidic rotation about a tilted axis

    NASA Astrophysics Data System (ADS)

    Müller, Paul; Schürmann, Mirjam; Chan, Chii J.; Guck, Jochen

    2015-08-01

    Optical diffraction tomography (ODT) is a tomographic technique that can be used to measure the three-dimensional (3D) refractive index distribution within living cells without the requirement of any marker. In principle, ODT can be regarded as a generalization of optical projection tomography which is equivalent to computerized tomography (CT). Both optical tomographic techniques require projection-phase images of cells measured at multiple angles. However, the reconstruction of the 3D refractive index distribution post-measurement differs for the two techniques. It is known that ODT yields better results than projection tomography, because it takes into account diffraction of the imaging light due to the refractive index structure of the sample. Here, we apply ODT to biological cells in a microfluidic chip which combines optical trapping and microfluidic flow to achieve an optofluidic single-cell rotation. In particular, we address the problem that arises when the trapped cell is not rotating about an axis perpendicular to the imaging plane, but is instead arbitrarily tilted. In this paper we show that the 3D reconstruction can be improved by taking into account such a tilted rotational axis in the reconstruction process.

  4. Effects of body orientation and rotation axis on pitch visual-vestibular interaction.

    PubMed

    Clément, G; Wood, S J; Lathan, C E; Peterka, R J; Reschke, M F

    1999-01-01

    Spatial transformations of the vestibular-optokinetic system must account for changes in head position with respect to gravity in order to produce compensatory oculomotor responses. The purpose of this experiment was to study the influence of gravity on the vestibulo-ocular reflex (VOR) in darkness and on visual-vestibular interaction in the pitch plane in human subjects using two different comparisons: (1) Earth-horizontal axis (EHA) rotation about an upright versus a supine body orientation, and (2) Earth-horizontal versus Earth-vertical (EVA) rotation axes. Visual-vestibular responses (VVR) were evaluated by measuring the slow phase velocity of nystagmus induced during sinusoidal motion of the body in the pitch plane (at 0.2 Hz and 0.8 Hz) combined with a constant-velocity vertical optokinetic stimulation (at +/- 36 degrees/s). The results showed no significant effect on the gain or phase of the VOR in darkness or on the VVR responses at 0.8 Hz between EHA upright and EHA supine body orientations. However, there was a downward shift in the VOR bias in darkness in the supine orientation. There were systematic changes in VOR and VVR between EHA and EVA for 0.2 Hz, including a reduced modulation gain, increased phase lead, and decreased bias during EVA rotation. The same trend was also observed at 0.8 Hz, but at a lesser extent, presumably due to the effects of eccentric rotation in our EVA condition and/or to the different canal input across frequencies. The change in the bias at 0.2 Hz between rotation in darkness and rotation with an optokinetic stimulus was greater than the optokinetic responses without rotation. During EHA, changes in head position relative to gravity preserve graviceptor input to the VVR regardless of body orientation. However, the modifications in VVR gain and phase when the rotation axis is aligned with gravity indicate that this graviceptive information is important for providing compensatory eye movements during visual

  5. Effects of body orientation and rotation axis on pitch visual-vestibular interaction

    NASA Technical Reports Server (NTRS)

    Clement, G.; Wood, S. J.; Lathan, C. E.; Peterka, R. J.; Reschke, M. F.

    1999-01-01

    Spatial transformations of the vestibular-optokinetic system must account for changes in head position with respect to gravity in order to produce compensatory oculomotor responses. The purpose of this experiment was to study the influence of gravity on the vestibulo-ocular reflex (VOR) in darkness and on visual-vestibular interaction in the pitch plane in human subjects using two different comparisons: (1) Earth-horizontal axis (EHA) rotation about an upright versus a supine body orientation, and (2) Earth-horizontal versus Earth-vertical (EVA) rotation axes. Visual-vestibular responses (VVR) were evaluated by measuring the slow phase velocity of nystagmus induced during sinusoidal motion of the body in the pitch plane (at 0.2 Hz and 0.8 Hz) combined with a constant-velocity vertical optokinetic stimulation (at +/- 36 degrees/s). The results showed no significant effect on the gain or phase of the VOR in darkness or on the VVR responses at 0.8 Hz between EHA upright and EHA supine body orientations. However, there was a downward shift in the VOR bias in darkness in the supine orientation. There were systematic changes in VOR and VVR between EHA and EVA for 0.2 Hz, including a reduced modulation gain, increased phase lead, and decreased bias during EVA rotation. The same trend was also observed at 0.8 Hz, but at a lesser extent, presumably due to the effects of eccentric rotation in our EVA condition and/or to the different canal input across frequencies. The change in the bias at 0.2 Hz between rotation in darkness and rotation with an optokinetic stimulus was greater than the optokinetic responses without rotation. During EHA, changes in head position relative to gravity preserve graviceptor input to the VVR regardless of body orientation. However, the modifications in VVR gain and phase when the rotation axis is aligned with gravity indicate that this graviceptive information is important for providing compensatory eye movements during visual

  6. Sun-Relative Pointing for Dual-Axis Solar Trackers Employing Azimuth and Elevation Rotations

    SciTech Connect

    Riley, Daniel; Hansen, Clifford W.

    2014-12-30

    Dual axis trackers employing azimuth and elevation rotations are common in the field of photovoltaic (PV) energy generation. Accurate sun-tracking algorithms are widely available. However, a steering algorithm has not been available to accurately point the tracker away from the sun such that a vector projection of the sun beam onto the tracker face falls along a desired path relative to the tracker face. We have developed an algorithm which produces the appropriate azimuth and elevation angles for a dual axis tracker when given the sun position, desired angle of incidence, and the desired projection of the sun beam onto the tracker face. Development of this algorithm was inspired by the need to accurately steer a tracker to desired sun-relative positions in order to better characterize the electro-optical properties of PV and CPV modules.

  7. Postural illusions experienced during Z-axis recumbent rotation and their dependence upon somatosensory stimulation of the body surface

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; Graybiel, A.

    1978-01-01

    A blindfolded recumbent subject experiences a variety of postural illusions when rotated about his Z axis. Initially, during the acceleratory phase of rotation, turning about his Z axis is experienced; but, as rotary velocity increases, a spiraling of the body outward in the direction opposite to true rotation is experienced as well. Above 15-20 rpm, only orbital motion of the body is experienced, with the subject feeling that he is always facing in the same direction. One cycle of the apparent orbit is completed each time the subject actually rotates 360 deg. The reverse sequence of illusory motion is experienced during deceleration. The illusory motion all subjects experience during Z-axis recumbent rotation is shown to depend upon the touch and pressure stimulation of the body surface generated by contact forces of support.

  8. Evidence for a 20° tilting of the Earth's rotation axis 110 million years ago

    NASA Astrophysics Data System (ADS)

    Prévot, Michel; Mattern, Estelle; Camps, Pierre; Daignières, Marc

    2000-07-01

    True polar wander (TPW), the shift of the Earth's rotation axis with respect to the entire globe, is most probably due to mass redistribution in the Earth's mantle as a result of convection. Using a new rigorously selected paleomagnetic database gathering only directions obtained from magmatic rocks, we find that TPW has been clearly intermittent over the last 200 Myr with two long periods of strict standstill from the present to 80 Ma and from approximately 150 to 200 Ma. A single period of shifting is observed, between 80 and about 150 Ma. This period culminates around 110 Ma in an 20° abrupt tilting during which an angular speed exceeding 5°/Myr (0.5 m/yr) may have been reached. Assuming that the time-averaged geomagnetic field is axial, our results indicate that the changes in the position of the rotation axis, and therefore in the inertia tensor of the Earth, are intermittent. We suggest that a major reorganization of the mass distribution in the Earth's mantle occurred in the Lower Cretaceous. This event, concomitant with plume hyperactivity at the Earth's surface and probable drastic changes at the core-mantle boundary attested by the inhibition of geomagnetic reversals, suggests unmixing of upper and lower mantle by avalanching of upper mantle material down to the core-mantle boundary. The astonishingly strict stability of the time-averaged position of the rotation axis before and after this episode of shifting implies the existence of some steady convection which does not modify the large-scale distribution of mass within the mantle. Given the intermittence of mantle avalanching, we suggest that these long periods of stability correspond to the temporary reestablishment of a basically two-layered convection system within the mantle.

  9. Development of a model counter-rotating type horizontal-axis tidal turbine

    NASA Astrophysics Data System (ADS)

    Huang, B.; Yoshida, K.; Kanemoto, T.

    2016-05-01

    In the past decade, the tidal energies have caused worldwide concern as it can provide regular and predictable renewable energy resource for power generation. The majority of technologies for exploiting the tidal stream energy are based on the concept of the horizontal axis tidal turbine (HATT). A unique counter-rotating type HATT was proposed in the present work. The original blade profiles were designed according to the developed blade element momentum theory (BEMT). CFD simulations and experimental tests were adopted to the performance of the model counter-rotating type HATT. The experimental data provides an evidence of validation of the CFD model. Further optimization of the blade profiles was also carried out based on the CFD results.

  10. Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.; Benolken, Martha S.

    1992-01-01

    Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulo-ocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

  11. Real-time iris detection on faces with coronal and transversal axis rotation

    NASA Astrophysics Data System (ADS)

    Perez, Claudio A.; Lazcano, Vanel A.

    2005-12-01

    Real-time face and iris detection on video sequences is important in diverse applications such as, study of the eye function, drowsiness detection, man-machine interfaces, face recognition, security and multimedia retrieval. In this work we present and extension to our previous method to incorporate face and iris detection in faces with coronal and transversal axis rotations in real time. The method is based on anthropometric templates and consists of three stages: coarse face detection, fine face detection and iris detection. In the coarse face detection, a directional image is computed and the contribution of each directional vector is weighted into an accumulator. The highest score in the accumulator is taken as the coarse face position. Then, a high-resolution directional image is computed. Face templates were constructed off-line for face coronal and transversal rotation, using face features such as elliptical shape, location of the eyebrows, nose and lips. A line integral is computed using these templates over the fine directional image to find the actual face location, size and rotation angle. This information provides a region to search for the eyes and the iris boundary is detected within this region by a ratio among to line integrals using a semicircular template. Results computed on five video sequences which include coronal and transversal rotations with over 1900 frames show correct face detection rate above 92% and iris detection rate above 86%.

  12. Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.; Benolken, Martha S.

    1991-01-01

    Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

  13. How does lever length and the position of its axis of rotation influence human performance during lever wheelchair propulsion?

    PubMed

    Fiok, Krzysztof; Mróz, Anna

    2015-10-01

    The purpose of this study was to investigate empirically how lever length and its axis of rotation position influences human performance during lever wheelchair propulsion. In order to fulfill this goal, a dedicated test stand allowing easy implementation of various lever positions was created. In the experiment, 10 young, healthy, male subjects performed 8 tests consisting of propulsion work with levers of different lengths and lever axis of rotation positions. During tests heart rate, oxygen consumption and EMG assessment of 6 muscles was carried out. Measurements of power output on the test stand were done as well. Together with oxygen consumption analysis, this allowed calculation of human work efficiency. The results show significant (p<0.05 and p<0.001) differences between lever configurations when comparing various parameters values. From the carried out experiments, the authors conclude that levers' length and their axis of rotation position significantly influence human performance during lever wheelchair propulsion. For the examined subjects, placing the levers' axis of rotation close behind the back wheels axis of rotation offered advantageous work conditions.

  14. Goldstone radar evidence for short-axis mode non-principal axis rotation of near-Earth asteroid (214869) 2007 PA8

    NASA Astrophysics Data System (ADS)

    Brozovic, M.; Benner, L.; Magri, C.; Busch, M.; Scheeres, D. J.; Giorgini, J. D.; Reddy, V.; Hicks, M. D.; Jao, J. S.; Lee, C. G.; Snedeker, L. G.; Silva, M. A.; Slade, M. A.; Lawrence, K. J.

    2014-12-01

    We report Goldstone radar (8560 MHz, 3.5 cm) observations and shape and spin state modeling of near-Earth asteroid (214869) 2007 PA8. We observed 2007 PA8 on 16 days between Oct 16-Nov 13, 2012 when the asteroid was within 0.14 AU of Earth. Closest approach was on Nov 5 at a distance of 0.043 AU (17 lunar distances). Images obtained with Goldstone's new chirp system achieved range resolution as fine as 3.75 m, placing thousands of pixels on the asteroid's surface and revealing that 2007 PA8 is an elongated, asymmetric object. Surface features include angularities, multiple facets, and a concavity approximately several hundred meters in diameter. We used the Shape software [1, 2] to estimate the asteroid's 3D shape and spin state. The initial shape of the asteroid was parameterized as an ovoid with dimensions of 1.85 kmx1.25 kmx1.20 km in principal axis (PA) rotation with rotational rates of 80-100 deg/day to match the progression of features visible in the images. This yielded two candidate spin states: one near the south ecliptic pole and another near ecliptic longitude and latitude of (270, +17) deg. However, PA spin state models predict that images from Oct 31 and Nov 11 should be very similar, but the images on those two days appear dramatically different. As a result, we expanded the spin state search to include non-principal axis (NPA) rotation. The best fit was obtained with NPA rotation in short-axis mode with an average period of precession by the long axis around the angular momentum vector of 4.25 days and an oscillatory period around the long axis of 20.16 days. The amplitude of rolling around the long axis is 42 deg. The angular momentum vector points within 10 deg of ecliptic longitude and latitude of (273, +16) deg. 2007 PA8 is only the second confirmed short-axis mode NPA rotator found in the near-Earth asteroid population, after (99942) Apophis [3]. References: [1] Hudson, S., 1993. Remote Sens. Rev. 8, 195-203. [2] Magri, C. et al., 2007. Icarus

  15. Fragmentation of elongated cylindrical clouds. IV - Clouds with solid-body rotation about an arbitrary axis

    NASA Technical Reports Server (NTRS)

    Bonnell, Ian; Arcoragi, Jean-Pierre; Martel, Hugo; Bastien, Pierre

    1992-01-01

    Results of 3D hydrodynamic collapse calculations of elongated isothermal clouds with solid-body rotation about an arbitrary axis are presented. Four different modes of fragmentation are identified. In all evolutions that formed more than one fragment, a structural fragmentation mode occurred first, forming condensations on each side of the cylinder. It is shown that gravitational torques and tidal effects control most of the fragmentation and coalescence which occur. The fragmentation processes and gravitational torques can also reduce the fragment's specific angular momentum by up to two orders of magnitude compared to that of the parent cloud. This is consistent with the inferred value of the specific angular momentum of the initial protosolar nebula.

  16. Open-close movements in the human temporomandibular joint: does a pure rotation around the intercondylar hinge axis exist?

    PubMed

    Ferrario, V F; Sforza, C; Miani, A; Serrao, G; Tartaglia, G

    1996-06-01

    Mandibular movements near the maximum intercuspal position were analysed for the location of the mean instantaneous centre of curvature of the interincisal point path. Measurements were performed using a kinesiograph in 28 healthy young adults with sound dentitions and free from temporomandibular joint disorders. The subjects performed habitual open-close cycles at different speeds; opening movements starting from the centric relation occlusion were also analysed. In none of the 28 subjects was the interincisal point path derived from pure rotation movements performed around the intercondylar axis, not even in the first millimetres of motion. Translation and rotation were always combined, and the position of the centre of curvature changed during the motion, showing different characteristics in the open and close movements; these patterns were also dependent upon motion speed. The results show that the hinge axis theory cannot explain the mandibular movements because a pure rotation did not occur around the intercondylar axis.

  17. Alignment of fiducial marks in a tomographic tilt series with an unknown rotation axis

    NASA Astrophysics Data System (ADS)

    Levine, Zachary H.; Volkovitsky, Alex; Hung, Howard K.

    2007-06-01

    Alignment for tomography using a transmission electron microscopy frequently uses colloidal gold particles as fiducial reference marks. Typically, there is an implicit assumption that the tilt axis of the tomographic series is orthogonal to the beam direction. However, this may not be true, either intentionally, if a tilt-rotate stage is used, or unintentionally, because of mechanical errors in the rotation stage or the sample fixture. Here, we provide a computer code which takes as input a set of two-dimensional (2D) observations of fiducial reference marks at various tilt angles and the values of those tilt angles. It produces as output a three-dimensional model of the observations, 2D shifts for each view, and the tilt axis direction. Program summaryTitle of program: particleTilt Catalogue identifier: ADYW_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYW_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computers: IBM compatible desktop PC; SGI Octane Operating system: Red Hat WS 3 Linux (with 2.4.21-40.EL kernel); IRIX 6.5 IP30 Program language used: Fortran 90 No. of bits in a word: 32 No. of processors used: one Has the code been vectorized: no No. of lines in distributed program, including test data, etc.: 2397 No. of bytes in distributed program, including test data, etc.: 47 017 Distribution format: tar.gz Peripherals used: one Typical running time: 350 ms (larger included example, on 2.8 GHz 32-bit PC) Nature of problem: The program is used to assist the alignment step in tomography. The samples should be prepared with spherical particles (typically gold beads) which are observed in several views. (Not every particle need be observed in every view.) The program reports coordinates of a 3D model of the particles as well as the direction of the tilt axis as a point on the unit sphere. Method of solution: Our package minimizes an objective function whose free variables are a set of 3D model points and

  18. Identifying Z-axis gyro drift and scale factor error using azimuth measurement in fiber optic gyroscope single-axis rotation inertial navigation system

    NASA Astrophysics Data System (ADS)

    Wang, Lingcao; Li, Kui; Wang, Lei; Gao, Jiaxin

    2017-02-01

    In the fiber optic gyroscope (FOG) single-axis rotation inertial navigation system (SRINS), the Z-axis gyro drift (ɛz) dramatically limits its navigation precision and the Z-axis gyro scale factor error (δK) can cause greater navigation error because of the rotation process compared with the strap-down inertial navigation system. Hence, identification and compensation for the ɛz and δK are important in SRINS. An approach based on the azimuth error model of open-loop algorithm is proposed. This approach considers azimuth angle as a measurement and uses a least recursive square algorithm for identifying the ɛz and δK. Compared with the traditional method, which takes velocity and position errors as measurements, the time required for identifying ɛz with the proposed method is only approximately 10 min, while the traditional method requires 6 h to 12 h. Experimental results from an SRINS with FOGs demonstrate that the accuracy of identifying the ɛz reaches 0.002°/h and that of the δK reaches 8 ppm in 10 min. The positioning accuracy of the SRINS improves greatly after the identification and compensation.

  19. On the Measurement and Analysis of Rotation and Spin Axis of LAGEOS and LAGEOS II

    NASA Astrophysics Data System (ADS)

    Currie, D.; Andres, N.; Noomen, R.

    2003-04-01

    The University of Maryland has, for the past 15 years, been monitoring the rotation of LAGEOS, LAGEOS II and other satellites by the sun-glint method. This has resulted in the first determination of the orientation of the spin axis, and has provide a history of the motion of the spin. The accuracy ellipse is typically better than 1 degree by 10 degrees, and when two passes are available for the same night, the error ellipse improves to 1 degree by 1 degree. This accuracy has been verified by internal consistency and by the agreement with the model of Andres. The current status of the observations and the method will be presented. The role of the thermal thrust will be addressed on the orbit will be addressed, as well as the effect of the satellite orientation. The relation of these measurement and the thermal thrust to the joint Italian/University of Maryland program for the measurement of the Lense-Thirring will be also discussed.

  20. Rotational kinematics of a rigid body about a fixed axis: development and analysis of an inventory

    NASA Astrophysics Data System (ADS)

    Mashood, K. K.; Singh, Vijay A.

    2015-07-01

    We present the development, administration, and analysis of a focused inventory on the rotational kinematics of a rigid body around a fixed axis. The inventory, which is made up of 13 multiple-choice questions, was developed on the basis of interactions with students and teachers. The systematic and iterative aspects of the construction of the inventory are illustrated. The questions, which were validated, were administered to a set of teachers (N = 25) and two groups of preuniversity students (N = 74 and 905) in India. Students, as well as teachers, exhibited difficulties in applying the operational definition of angular velocity to a rigid body. Many erroneously assumed that an angular acceleration cannot exist without a net torque. Patterns of reasoning resulting in errors were identified and categorized under four broad themes. These include inappropriate extensions of familiar procedural practices, reasoning cued by primitive elements in thought, lack of differentiation between related but distinct concepts, and indiscriminate use of equations. The inventory was also administered to introductory-level students (N = 384) at the University of Washington. Popular distractors to most items were similar to the Indian students.

  1. Goldstone radar evidence for short-axis mode non-principal-axis rotation of near-Earth asteroid (214869) 2007 PA8

    NASA Astrophysics Data System (ADS)

    Brozović, Marina; Benner, Lance A. M.; Magri, Christopher; Scheeres, Daniel J.; Busch, Michael W.; Giorgini, Jon D.; Nolan, Michael C.; Jao, Joseph S.; Lee, Clement G.; Snedeker, Lawrence G.; Silva, Marc A.; Lawrence, Kenneth J.; Slade, Martin A.; Hicks, Michael D.; Howell, Ellen S.; Taylor, Patrick A.; Sanchez, Juan A.; Reddy, Vishnu; Dykhuis, Melissa; Corre, Lucille Le

    2017-04-01

    We report radar and optical photometric observations of near-Earth asteroid (214869) 2007 PA8 obtained during October 2-November 13, 2012. We observed 2007 PA8 on sixteen days with Goldstone (8560 MHz, 3.5 cm) and on five days with the 0.6 m telescope at Table Mountain Observatory. Closest approach was on November 5 at a distance of 0.043 au. Images obtained with Goldstone's new chirp system achieved range resolutions as fine as 3.75 m, placing thousands of pixels on the asteroid's surface, and revealing that 2007 PA8 is an elongated, asymmetric object. Surface features include angularities, facets, and a concavity approximately 400 m in diameter. We used the Shape software to estimate the asteroid's 3D shape and spin state. 2007 PA8 has a broad, rounded end and a tapered, angular end with sharp-crested ridges. The asteroid's effective diameter is 1.35 ± 0.07 km, which in combination with the absolute magnitude of 16.30 ± 0.52 gives an optical albedo of pV = 0.29 ± 0.14. The shape modeling of the radar data revealed that 2007 PA8 is a non-principal axis (NPA) rotator in the short-axis mode with an average period of precession by the long axis around the angular momentum vector of 4.26 ± 0.02 days and an oscillatory period around the long axis of 20.55 ± 3.75 days. The amplitude of rolling around the long axis is 42 ± 7° . The angular momentum vector points toward ecliptic longitude and latitude of 273.6 ± 10°, +16.9 ± 5°. 2007 PA8 is only the second confirmed short-axis mode NPA rotator known in the near-Earth asteroid population after (99942) Apophis (Pravec et al., 2014). 2007 PA8 has a geopotential high at the equator, where the equator is defined as the plane that contains the long and intermediate axis. This geopotential extreme could be interpreted as a large, hidden surface depression, or as evidence that 2007 PA8 is a multi-component body.

  2. Transverse axis fluid turbine

    SciTech Connect

    Brenneman, B.

    1983-11-15

    A fluid turbine, the rotation axis of which is transverse to the direction of fluid flow, has at least two blade assemblies mounted for rotation about the rotation axis. Each blade assembly includes a streamlined elongated blade having a span parallel to the rotation axis. Each blade is pivotable about a pivot axis parallel to and spaced from the rotation axis. The pivot axis is located circumferentially ahead of the blade center of pressure with respect to the direction of turbine rotation. Each blade assembly is so constructed that its center of mass is located either at its pivot axis or circumferentially at its pivot axis and radially outboard of its pivot axis.

  3. Frequency analysis of the non-principal-axis rotation of uniaxial space debris in circular orbit subjected to gravity-gradient torque

    NASA Astrophysics Data System (ADS)

    Lin, Hou-Yuan; Zhao, Chang-Yin; Zhang, Ming-Jiang

    2016-03-01

    The non-principal-axis rotational motion of uniaxial space debris can be decomposed into periodic motions associated with two frequencies: the polhode frequency of the space debris rotating around the symmetry axis, and the tumbling frequency of the symmetry axis rotating around the angular momentum. To determine from optical measurements the rotational motion of upper rocket stages in circular orbits subjected to gravity-gradient torque, the evolutions of these two frequencies need to be analyzed. Taking into account only the long-term changes in the long-period variables, the differential equations of the non-principal axis rotational motion of the uniaxial space debris are averaged and reduced, from which the evolutions of the polhode and tumbling frequencies are then obtained analytically. The theoretical results are verified by numerical simulations of the diffuse reflection model. The frequencies in the variation of the reflected light intensity in the simulation are analyzed using the frequency map analysis (FMA) method. Errors of these results are found to be less than 1%. Based on the theoretical expressions, the rotational state of the uniaxial space debris can be estimated in the simulation without any prior information except the orbital parameters. A series of state variables are estimated, including the ratio of the moments of inertia about the transverse axis and the symmetry axis, the instantaneous rotation velocity, the orientation of the angular momentum, and the precession cone of the symmetry axis.

  4. Method and device for determining the position of a cutting tool relative to the rotational axis of a spindle-mounted workpiece

    DOEpatents

    Williams, R.R.

    1980-09-03

    The present invention is directed to a method and device for determining the location of a cutting tool with respect to the rotational axis of a spindle-mounted workpiece. A vacuum cup supporting a machinable sacrificial pin is secured to the workpiece at a location where the pin will project along and encompass the rotational axis of the workpiece. The pin is then machined into a cylinder. The position of the surface of the cutting tool contacting the machine cylinder is spaced from the rotational axis of the workpiece a distance equal to the radius of the cylinder.

  5. Dike orientations in the late jurassic independence dike swarm and implications for vertical-axis tectonic rotations in eastern California

    USGS Publications Warehouse

    Hopson, R.F.; Hillhouse, J.W.; Howard, K.A.

    2008-01-01

    Analysis of the strikes of 3841 dikes in 47 domains in the 500-km-long Late Jurassic Independence dike swarm indicates a distribution that is skewed clockwise from the dominant northwest strike. Independence dike swarm azimuths tend to cluster near 325?? ?? 30??, consistent with initial subparallel intrusion along much of the swarm. Dike azimuths in a quarter of the domains vary widely from the dominant trend. In domains in the essentially unrotated Sierra Nevada block, mean dike azimuths range mostly between 300?? and 320??, with the exception of Mount Goddard (247??). Mean dike azimuths in domains in the Basin and Range Province in the Argus, Inyo, and White Mountains areas range from 291?? to 354?? the mean is 004?? in the El Paso Mountains. In the Mojave Desert, mean dike azimuths range from 318?? to 023??, and in the eastern Transverse Ranges, they range from 316?? to 051??. Restoration for late Cenozoic vertical-axis rotations, suggested by paleodeclinations determined from published studies from nearby Miocene and younger rocks, shifts dike azimuths into better agreement with azimuths measured in the tectonically stable Sierra Nevada. This confirms that vertical-axis tectonic rotations explain some of the dispersion in orientation, especially in the Mojave Desert and eastern Transverse Ranges, and that the dike orientations can be a useful if imperfect guide to tectonic rotations where paleomagnetic data do not exist. Large deviations from the main trend of the swarm may reflect (1) clockwise rotations for which there is no paleomagnetic evidence available, (2) dike intrusions of other ages, (3) crack filling at angles oblique or perpendicular to the main swarm, (4) pre-Miocene rotations, or (5) unrecognized domain boundaries between dike localities and sites with paleomagnetic determinations. ?? 2008 The Geological Society of America.

  6. Development of a Low-Cost Attitude and Heading Reference System Using a Three-Axis Rotating Platform

    PubMed Central

    Lai, Ying-Chih; Jan, Shau-Shiun; Hsiao, Fei-Bin

    2010-01-01

    A development procedure for a low-cost attitude and heading reference system (AHRS) with a self-developed three-axis rotating platform has been proposed. The AHRS consists of one 3-axis accelerometer, three single-axis gyroscopes, and one 3-axis digital compass. Both the accelerometer and gyroscope triads are based on micro electro-mechanical system (MEMS) technology, and the digital compass is based on anisotropic-magnetoresistive (AMR) technology. The calibrations for each sensor triad are readily accomplished by using the scalar calibration and the least squares methods. The platform is suitable for the calibration and validation of the low-cost AHRS and it is affordable for most laboratories. With the calibrated parameters and data fusion algorithm for the orientation estimation, the self-developed AHRS demonstrates the capabilities of compensating for the sensor errors and outputting the estimated orientation in real-time. The validation results show that the estimated orientations of the developed AHRS are within the acceptable region. This verifies the practicability of the proposed development procedure. PMID:22319258

  7. Development of a low-cost attitude and heading reference system using a three-axis rotating platform.

    PubMed

    Lai, Ying-Chih; Jan, Shau-Shiun; Hsiao, Fei-Bin

    2010-01-01

    A development procedure for a low-cost attitude and heading reference system (AHRS) with a self-developed three-axis rotating platform has been proposed. The AHRS consists of one 3-axis accelerometer, three single-axis gyroscopes, and one 3-axis digital compass. Both the accelerometer and gyroscope triads are based on micro electro-mechanical system (MEMS) technology, and the digital compass is based on anisotropic-magnetoresistive (AMR) technology. The calibrations for each sensor triad are readily accomplished by using the scalar calibration and the least squares methods. The platform is suitable for the calibration and validation of the low-cost AHRS and it is affordable for most laboratories. With the calibrated parameters and data fusion algorithm for the orientation estimation, the self-developed AHRS demonstrates the capabilities of compensating for the sensor errors and outputting the estimated orientation in real-time. The validation results show that the estimated orientations of the developed AHRS are within the acceptable region. This verifies the practicability of the proposed development procedure.

  8. Spinning dust emission: the effect of rotation around a non-principal axis

    NASA Astrophysics Data System (ADS)

    Silsbee, Kedron; Ali-Haïmoud, Yacine; Hirata, Christopher M.

    2011-03-01

    We investigate the rotational emission from dust grains that rotate around non-principal axes. We argue that in many phases of the interstellar medium, the smallest grains, which dominate spinning dust emission, are likely to have their nutation state (orientation of principal axes relative to the angular momentum vector) randomized during each thermal spike. We recompute the excitation and damping rates associated with rotational emission from the grain permanent dipole, grain-plasma interactions, infrared photon emission and collisions. The resulting spinning dust spectra generally show a shift towards higher emissivities and peak frequencies relative to previous calculations.

  9. Reorientation of the rotation axis of triaxial viscoelastic icy moons: Europa and Titan

    NASA Astrophysics Data System (ADS)

    Jara Orue, H. M.; Vermeersen, L. L. A.

    2011-10-01

    We provide an analysis of the rotational response of triaxial viscoelastic icy moons, focusing on the free rotational behavior of Europa and Titan. In a similar way as for terrestrial planets, the rotational behavior of icy moons is dominated by a secular shift of the pole and the periodic Chandler wobble. However, unlike terrestrial planets, the Chandler wobble of icy moons is associated with the viscoelastic response of the layers located below the ocean. The fast relaxation of low-viscous ice layers induces additional wobble frequencies. However, these wobbles are generally weak compared to the strength of the main Chandler wobble.

  10. Estimating the Error of an Asymptotic Solution Describing the Angular Oscillations of the Axis of Symmetry of a Rotating Rigid Body

    NASA Astrophysics Data System (ADS)

    Konosevich, B. I.

    2014-07-01

    The error of the Wentzel-Kramers-Brillouin solution of the equations describing the angular motion of the axis of symmetry of rotation of a rigid body (projectile) is estimated. It is established that order of this estimate does not depend on whether the low-frequency oscillations of the axis of symmetry are damped or not

  11. The influence of correlation between initial axis curvature and cross-section rotation on the beam static resistance

    SciTech Connect

    Valeš, Jan

    2015-03-10

    The paper deals with statistical analysis of the resistance of simply supported I-beams subjected to bending. The resistance was solved by applying the geometrically nonlinear solution. The influence of lateral-beam buckling on resistance is studied. Initial geometrical imperfections originating from the first eigenmode of lateral-beam buckling and from the cross section rotation at the stability lost were ascribed to the beams. These imperfections consist of initial axial lateral buckling and rotation of cross sections along the beam axis length. The correlation between the amplitudes of these imperfections is considered to be the parameter of solutions within the interval from -1 to 1. The influence of this correlation on the change of mean values and standard deviations of random resistance of beams with nondimensional slenderness close to 1 is studied. The imperfections mentioned were considered, together with geometrical and material characteristics of cross section and material characteristics of steel, to be random quantities.

  12. Asymmetric basin subsidence and horizontal-axis block rotations in the Miocene North Whipple Basin, SE California and W Arizona

    SciTech Connect

    Dorsey, R.J.; Roberts, P. . Dept. of Geology)

    1992-01-01

    A thick, faulted sequence of post-18.5-Ma Miocene sedimentary and volcanic rocks is well exposed in the Aubrey Hills, W Arizona, and the northeastern Whipple Mountains, SE California. These strata were deposited in alluvial fans and playa lakes of a syntectonic sedimentary basin (North Whipple Basin), which evolved in the upper plate of the Whipple detachment fault on the north flank of the growing proto-Whipple Mountains. Sedimentary deposits reveal substantial lateral changes in thickness and depositional facies (lacustrine to proximal-fan) that provide a record of asymmetric basin subsidence and upper-plate block rotations during strong regional extension. Final uplift, exhumation and unroofing of lower-plate rocks occurred during this time, as evidenced by sandstone-petrographic and conglomerate clast-count studies. Two horizontal orthogonally oriented axes of synbasinal crustal rotation are recognized: extension-perpendicular (NW-SE), and extension-parallel (NE-SW). Rotation about extension-perpendicular axes occurred by displacements on NW-striking normal faults that formed classic half-graben basins in the extending upper plate. Evidence for rotation about an extension-parallel axis is seen in pronounced lateral thickening and coarsening of sedimentary lithofacies toward the SE in the Aubrey Hills. This was likely controlled by synbasinal growth of an extension-parallel syncline, which formed on the NW flank of the Whipple Mountain extension-parallel antiform.

  13. Method and device for determining the position of a cutting tool relative to the rotational axis of a spindle-mounted workpiece

    DOEpatents

    Williams, Richard R.

    1982-01-01

    The present invention is directed to a method and device for determining the location of a cutting tool with respect to the rotational axis of a spindle-mounted workpiece. A vacuum cup supporting a machinable sacrifical pin is secured to the workpiece at a location where the pin will project along and encompass the rotational axis of the workpiece. The pin is then machined into a cylinder. The position of the surface of the cutting tool contacting the machine cylinder is spaced from the rotational aixs of the workpiece a distance equal to the radius of the cylinder.

  14. Analysis and calibration of the gyro bias caused by geomagnetic field in a dual-axis rotational inertial navigation system

    NASA Astrophysics Data System (ADS)

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Yin, Hongliang; Liu, Yiliang

    2016-10-01

    A rotational inertial navigation system (RINS) has been wildly used in long term marine navigation. In a dual-axis RINS, with all constant biases averaged out, the errors which can not be averaged out become the main error source. In this paper, the gyro geomagnetic biases of a dual-axis RINS are modelled, analysed and calibrated. The gyro geomagnetic biases are proved unable to be averaged out, but can be modulated to be a constant value in the navigation frame. A slope error term of longitude error is found to be caused by gyro geomagnetic biases in north and upward directions, which increases linearly with time and is remarkable in long term navigation. Thus, a calibration method based on least square regression is proposed to compensate the slope error term. Laboratory and sailing experimental results show that the divergence speed of longitude error can be effectively slowed down by the compensation of gyro geomagnetic biases. In long term independent navigation, the position accuracy of dual-axis RINS is improved about 50% by the calibration method proposed in this paper.

  15. Mixed convection flow and heat transfer in entrance region of rectangular ducts rotating about a parallel axis

    SciTech Connect

    Soong, C.Y.; Yan, W.M.

    1995-12-31

    The objective of the present work is to investigate the laminar mixed convection flow and heat transfer in the entrance region of heated rectangular ducts rotating about a parallel axis. Heating conditions of isothermal and iso-flux are both considered. Boussinesq approximation is invoked to take into account buoyancy effect induced by centrifugal force. Navier-Stokes/Boussinesq system can be cast into a dimensionless form, in which five governing parameters, the Prandtl number Pr, rotational Reynolds number J, rotational Grashof number Gr{sub {Omega}}, aspect ratio {gamma} and the eccentricity E, are involved. Mechanisms of secondary vortex development in the ducts are explored by a theoretical analysis on vorticity transport equation. The values of Pr and E are fixed as 0.7 and 10, respectively. For various combinations of the other thee parameters, a vorticity-velocity method implemented with a marching technique is employed to solve the resultant three-dimensional system for simultaneously developing flow and temperature fields. The emphasis is placed on the rotational effects, including both coriolis force and centrifugal buoyancy; on the non-isothermal flow and the related heat transfer. The results reveal that the friction factors and heat transfer rates can be enhanced by Coriolis and rotation-induced buoyancy effects; and the variations of the local values are closely related to the evolution of the secondary vortices in ducts. The differences in flow behaviors and thermal characteristics for UWT and UHF are also investigated by the present theoretical analysis on secondary flow mechanism as well as the computational results.

  16. Design, Analysis, Hybrid Testing and Orientation Control of a Floating Platform with Counter-Rotating Vertical-Axis Wind Turbines

    NASA Astrophysics Data System (ADS)

    Kanner, Samuel Adam Chinman

    The design and operation of two counter-rotating vertical-axis wind turbines on a floating, semi-submersible platform is studied. The technology, called the Multiple Integrated and Synchronized Turbines (MIST) platform has the potential to reduce the cost of offshore wind energy per unit of installed capacity. Attached to the platform are closely-spaced, counter-rotating turbines, which can achieve a higher power density per planform area because of synergistic interaction effects. The purpose of the research is to control the orientation of the platform and rotational speeds of the turbines by modifying the energy absorbed by each of the generators of the turbines. To analyze the various aspects of the platform and wind turbines, the analysis is drawn from the fields of hydrodynamics, electromagnetics, aerodynamics and control theory. To study the hydrodynamics of the floating platform in incident monochromatic waves, potential theory is utilized, taking into account the slow-drift yaw motion of the platform. Steady, second-order moments that are spatially dependent (i.e., dependent on the platform's yaw orientation relative to the incident waves) are given special attention since there are no natural restoring yaw moment. The aerodynamics of the counter-rotating turbines are studied in collaboration with researchers at the UC Berkeley Mathematics Department using a high-order, implicit, large-eddy simulation. An element flipping technique is utilized to extend the method to a domain with counter-rotating turbines and the effects from the closely-spaced turbines is compared with existing experimental data. Hybrid testing techniques on a model platform are utilized to prove the controllability of the platform in lieu of a wind-wave tank. A 1:82 model-scale floating platform is fabricated and tested at the UC Berkeley Physical-Model Testing Facility. The vertical-axis wind turbines are simulated by spinning, controllable actuators that can be updated in real-time of

  17. Paleomagnetic Determination of Vertical-Axis Block Rotation and Magnetostratigraphy in the Coachella Valley, California

    NASA Astrophysics Data System (ADS)

    Dimitroff, C.; Housen, B. A.; McNabb, J. C.; Dorsey, R. J.; Burmester, R. F.; Messe, G. T.

    2015-12-01

    Here, we report new paleomagnetism and magnetostratigraphy data from the Palm Spring Fm of the Mecca Hills, the Pleistocene conglomeratic sandstone in Desert Hot Springs and the Plio-Pleistocene San Timoteo beds from Live Oak Canyon. From the Mecca Hills, new data are from 29 sites and 112 samples. The paleomagnetic results yielded well-defined components of magnetization- defining seven polarity zones within the Ocotillo and upper Palm Spring Fm. Correlation to the geomagnetic polarity timescale, using the Bishop Ash near the top of the section as a tie point, places the Brunhes-Matuyama boundary near the base of the Ocotillo Fm, and the Jaramillo, Olduvai, and Reunion normal polarity sub-chrons in the upper Palm Spring Fm. This indicates the upper Palm Spring Fm in the Mecca Hills was deposited between 2.3 and 0.9 Ma. Sites from the Mecca Hills section have mean directions of D = 343, I = 53, α95 =11.3 N = 5 for normal sites, D = 175, I = -50, α95 = 4.9 N = 24 for reverse sites, and normal and reverse sites combined have a mean direction of D = 353, I = 51 α95 = 4.4. This indicates modest (7 degrees) CCW rotation of the section. Results from 19 sites (53 samples) of the Pleistocene conglomeritic sandstone from Desert Hot Springs have very well-defined paleomagnetic components. Six of the sites have normal polarity- 13 sites have reverse polarity. Sites with normal polarity have a mean direction of D = 358, I = 45, α95 = 13 and reverse sites have a mean of D = 182, I = -50, α95 = 6.6.The combined mean direction (in tilt-corrected coordinates) is D = 0.7, I = 49, α95 = 5.6 and indicates that 3.1° ± 2.3° of CW rotation has occurred at this location since ~1 to 1.5 Ma. Results from 8 sites (35 samples) of the upper-most San Timoteo beds from Live Oak Canyon also have well-defined paleomagnetic components for 6 sites. All of the results have normal polarity, and one site has a direction that is >40 degree from the other sites- the mean of the remaining 5

  18. Off-axis cooling of rotating devices using a crank-shaped heat pipe

    DOEpatents

    Jankowski, Todd A.; Prenger, F. Coyne; Waynert, Joseph A.

    2007-01-30

    The present invention is a crank-shaped heat pipe for cooling rotating machinery and a corresponding method of manufacture. The crank-shaped heat pipe comprises a sealed cylindrical tube with an enclosed inner wick structure. The crank-shaped heat pipe includes a condenser section, an adiabatic section, and an evaporator section. The crank-shape is defined by a first curve and a second curve existing in the evaporator section or the adiabatic section of the heat pipe. A working fluid within the heat pipe provides the heat transfer mechanism.

  19. Post-middle Miocene Tuffs of Bodie Hills and Mono Basin, California: Paleomagnetic Reference Directions and Vertical Axis Rotation

    NASA Astrophysics Data System (ADS)

    Lindeman, J. R.; Pluhar, C. J.; Farner, M. J.

    2013-12-01

    The relative motions of the Pacific and North American plates about the Sierra Nevada-North American Euler pole is accommodated by dextral slip along the San Andreas Fault System (~75%) and the Walker Lane-Eastern California Shear Zone system of faults, east of the Sierra Nevada microplate (~25%). The Bodie Hills and Mono Basin regions lie within the Walker Lane and partially accommodate deformation by vertical axis rotation of up to 60o rotation since ~9.4 Ma. This region experienced recurrent eruptive events from mid to late Miocene, including John et al.'s (2012) ~12.05 Ma Tuff of Jack Springs (TJS) and Gilbert's (1968) 11.1 - 11.9 Ma 'latite ignimbrite' east of Mono Lake. Both tuffs can be identified by phenocrysts of sanidine and biotite in hand specimens, with TJS composed of a light-grey matrix and the latite ignimbrite composed of a grey-black matrix. Our paleomagnetic results show these units to both be normal polarity, with the latite ignimbrite exhibiting a shallow inclination. TJS's normal polarity is consistent with emplacement during subchron C5 An. 1n (12.014 - 12.116 Ma). The X-ray fluorescence analyses of fiamme from TJS in Bodie Hills and the latite ignimbrite located east of Mono Lake reveal them both to be rhyolites with the latite ignimbrite sharing elevated K composition seen in the slightly younger Stanislaus Group (9.0 - 10.2 Ma). We establish a paleomagnetic reference direction of D = 352.8o I = 42.7o α95 = 7.7o n = 5 sites (42 samples) for TJS in the Bodie Hills in a region hypothesized by Carlson (2012) to have experienced low rotation. Our reference for Gilbert's latite ignimbrite (at Cowtrack Mountain) is D = 352.9o I = 32.1o α95 = 4.7o. This reference locality is found on basement highland likely to have experienced less deformation then the nearby Mono Basin since ignimbrite emplacement. Paleomagnetic results from this latite ignimbrite suggests ~98.2o × 5.5o of clockwise vertical axis rotation of parts of eastern Mono Basin since

  20. Intersegmental dynamics of 3D upper arm and forearm longitudinal axis rotations during baseball pitching.

    PubMed

    Naito, Kozo; Takagi, Hiroyasu; Yamada, Norimasa; Hashimoto, Shinichi; Maruyama, Takeo

    2014-12-01

    The shoulder internal rotation (IR) and forearm pronation (PR) are important elements for baseball pitching, however, how rapid rotations of IR and PR are produced by muscular torques and inter-segmental forces is not clear. The aim of this study is to clarify how IR and PR angular velocities are maximized, depending on muscular torque and interactive torque effects, and gain a detailed knowledge about inter-segmental interaction within a multi-joint linked chain. The throwing movements of eight collegiate baseball pitchers were recorded by a motion capture system, and induced-acceleration analysis was used to assess the respective contributions of the muscular (MUS) and interactive torques associated with gyroscopic moment (GYR), and Coriolis (COR) and centrifugal forces (CEN) to maximum angular velocities of IR (MIRV) and PR (MPRV). The results showed that the contribution of MUS account for 98.0% of MIRV, while that contribution to MPRV was indicated as negative (-48.1%). It was shown that MPRV depends primarily on the interactive torques associated with GYR and CEN, but the effects of GYR, COR and CEN on MIRV are negligible. In conclusion, rapid PR motion during pitching is created by passive-effect, and is likely a natural movement which arises from 3D throwing movement. Applying the current analysis to IR and PR motions is helpful in providing the implications for improving performance and considering conditioning methods for pitchers.

  1. Dynamic motion analysis of dart throwers motion visualized through computerized tomography and calculation of the axis of rotation.

    PubMed

    Edirisinghe, Y; Troupis, J M; Patel, M; Smith, J; Crossett, M

    2014-05-01

    We used a dynamic three-dimensional (3D) mapping method to model the wrist in dynamic unrestricted dart throwers motion in three men and four women. With the aid of precision landmark identification, a 3D coordinate system was applied to the distal radius and the movement of the carpus was described. Subsequently, with dynamic 3D reconstructions and freedom to position the camera viewpoint anywhere in space, we observed the motion pathways of all carpal bones in dart throwers motion and calculated its axis of rotation. This was calculated to lie in 27° of anteversion from the coronal plane and 44° of varus angulation relative to the transverse plane. This technique is a safe and a feasible carpal imaging method to gain key information for decision making in future hand surgical and rehabilitative practices.

  2. Retrograde diurnal motion of the instantaneous rotation axis observed by a large ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Tian, W.

    2017-01-01

    Ring laser gyroscope technique directly senses the Earth's instantaneous rotation pole (IRP), whose polar motion contains strong retrograde diurnal components induced by external torques due to the gravitational attraction of the Moon and Sun. The first direct measurement of this retrograde diurnal motion with three large ring lasers was reported by Schreiber et al. (J Geophys Res 109(B18):B06405, significant increase in precision and stability of ring laser gyroscopes; however, precise determination of amplitude and phase at main partial waves has not been given in the literature. In this paper, I will report on determination of the retrograde diurnal motion of the IRP at main partial waves (Oo_1, J_1, K_1, M_1, O_1, Q_1) by the ring laser "G", located in Wettzell, Germany, which is the most stable one amongst the currently running large ring laser gyroscopes.

  3. Developing a 6-DOF robot to investigate multi-axis ACL injuries under valgus loading coupled with tibia internal rotation.

    PubMed

    Ren, Yupeng; Jacobs, Benjamin J; Nuber, Gordon W; Koh, Jason L; Zhang, Li-Qun

    2010-01-01

    Anterior cruciate ligament (ACL) injuries have become more common in recent years as more young people participate in risky sporting activities [1]. Most ACL injuries occur as a result of noncontact mechanisms. Previous in vitro studies of ACL strain have found significant increases in ACL strain primarily with anterior directed force on the tibia relative to the femur and with internal rotation and often with valgus torque [2,3]. However, there remains significant controversy over the mechanisms of ACL failure and the forces on the knee that lead to injury. Some studies have also shown that isolated valgus loading may not load the ACL strongly. The goal of this study was to investigate the mechanism underlying valgus-related ACL injuries. An improved understanding of ACL failure may lead to improved ACL injury prevention programs. A novel 6 degrees of freedom (DOF) knee driving robot was developed in this study with a unique multi-axis simultaneous torque/position control. It was found that pure valgus torque caused a torque that internally rotated the tibia and thus increased ACL strain markedly, which may be an important mechanism underlying the rather common seemingly valgus-related ACL injuries.

  4. Three-dimensional flow field around and downstream of a subscale model rotating vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Ryan, Kevin J.; Coletti, Filippo; Elkins, Christopher J.; Dabiri, John O.; Eaton, John K.

    2016-03-01

    Three-dimensional, three-component mean velocity fields have been measured around and downstream of a scale model vertical axis wind turbine (VAWT) operated at tip speed ratios (TSRs) of 1.25 and 2.5, in addition to a non-rotating case. The five-bladed turbine model has an aspect ratio (height/diameter) of 1 and is operated in a water tunnel at a Reynolds number based on turbine diameter of 11,600. Velocity fields are acquired using magnetic resonance velocimetry (MRV) at an isotropic resolution of 1/50 of the turbine diameter. Mean flow reversal is observed immediately behind the turbine for cases with rotation. The turbine wake is highly three-dimensional and asymmetric throughout the investigated region, which extends up to 7 diameters downstream. A vortex pair, generated at the upwind-turning side of the turbine, plays a dominant role in wake dynamics by entraining faster fluid from the freestream and aiding in wake recovery. The higher TSR case shows a larger region of reverse flow and greater asymmetry in the near wake of the turbine, but faster wake recovery due to the increase in vortex pair strength with increasing TSR. The present measurement technique also provides detailed information about flow in the vicinity of the turbine blades and within the turbine rotor. The details of the flow field around VAWTs and in their wakes can inform the design of high-density VAWT wind farms, where wake interaction between turbines is a principal consideration.

  5. Distribution and mechanism of Neogene to present-day vertical axis rotations, Pacific-Australian Plate Boundary Zone, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Little, Timothy A.; Roberts, Andrew P.

    1997-01-01

    Remarkably little knowledge exists about mechanisms of vertical axis rotation in continental crust. Steeply dipping basement rocks in South Island, New Zealand, provide an opportunity to map the distribution of rotations across the Pacific-Australian plate boundary zone, and to delineate boundaries of rotated blocks in unusual detail. We synthesize new structural data with new and existing paleomagnetic data, with geodetic data, and with patterns of Neogene-Quaternary faulting in the strike-slip Marlborough fault system. For the past 20 m.y., vertical axis rotations have been hinged about two crustal-scale boundaries near the east coast. The NE hinge accommodated ˜50° of early-middle Miocene clockwise rotation, which caused deformation of the eastern ends of the Alpine-Wairau and Clarence strike-slip faults. The SW hinge has accommodated a further 30°-50° of finite clockwise rotation since ˜4 Ma and deflects active fault traces. The locus of rotation has shifted southwestward astride a subduction margin that is lengthening in that direction. Rotating rocks are pinned to the south against a locked collision zone where the continental Chatham Rise impinges against the margin. Slip on inland strike-slip faults is transformed seaward across a zone of fault termination into rigid body rotation of a large continental block that has been thrust eastward over the downgoing subducted slab of the Pacific plate. The rotation mechanism is a "migrating hinge," which resembles a flexed telephone book. Strike-slip faults are translated through a brecciated hinge region that does not coincide with a fixed material line in the rock.

  6. Q-adjusting technique applied to vertical deflections estimation in a single-axis rotation INS/GPS integrated system

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Wang, Xingshu; Wang, Jun; Dai, Dongkai; Xiong, Hao

    2016-10-01

    Former studies have proved that the attitude error in a single-axis rotation INS/GPS integrated system tracks the high frequency component of the deflections of the vertical (DOV) with a fixed delay and tracking error. This paper analyses the influence of the nominal process noise covariance matrix Q on the tracking error as well as the response delay, and proposed a Q-adjusting technique to obtain the attitude error which can track the DOV better. Simulation results show that different settings of Q lead to different response delay and tracking error; there exists optimal Q which leads to a minimum tracking error and a comparatively short response delay; for systems with different accuracy, different Q-adjusting strategy should be adopted. In this way, the DOV estimation accuracy of using the attitude error as the observation can be improved. According to the simulation results, the DOV estimation accuracy after using the Q-adjusting technique is improved by approximate 23% and 33% respectively compared to that of the Earth Model EGM2008 and the direct attitude difference method.

  7. Development of a Robotic Assembly for Analyzing the Instantaneous Axis of Rotation of the Foot Ankle Complex

    PubMed Central

    Salb, Kelly N.; Wido, Daniel M.; Stewart, Thomas E.; DiAngelo, Denis J.

    2016-01-01

    Ankle instantaneous axis of rotation (IAR) measurements represent a more complete parameter for characterizing joint motion. However, few studies have implemented this measurement to study normal, injured, or pathological foot ankle biomechanics. A novel testing protocol was developed to simulate aspects of in vivo foot ankle mechanics during mid-stance gait in a human cadaveric specimen. A lower leg was mounted in a robotic testing platform with the tibia upright and foot flat on the baseplate. Axial tibia loads (ATLs) were controlled as a function of a vertical ground reaction force (vGRF) set at half body weight (356 N) and a 50% vGRF (178 N) Achilles tendon load. Two specimens were repetitively loaded over 10 degrees of dorsiflexion and 20 degrees of plantar flexion. Platform axes were controlled within 2 microns and 0.008 degrees resulting in ATL measurements within ±2 N of target conditions. Mean ATLs and IAR values were not significantly different between cycles of motion, but IAR values were significantly different between dorsiflexion and plantar flexion. A linear regression analysis showed no significant differences between slopes of plantar flexion paths. The customized robotic platform and advanced testing protocol produced repeatable and accurate measurements of the IAR, useful for assessing foot ankle biomechanics under different loading scenarios and foot conditions. PMID:27099456

  8. Numerical study of mixed convection around a sphere rotating about its vertical axis in a Newtonian fluid at rest and subject to a heat flux

    SciTech Connect

    Hatem, N.; Philippe, C.; Mbow, C.; Kabdi, Z.; Najoua, S.; Daguenet, M.

    1996-03-01

    The authors study numerically the steady state laminar mixed convection around a sphere heated by a nonuniform flux in a Newtonian fluid. The sphere rotates around its vertical axis. The governing transfer equations in this three-dimensional problem are solved by using the method of Cebeci-Keller. Three types of convection are considered: pure rotation, pure natural convection, and mixed convection. The profiles of the coefficients of heat transfer and local friction, as well as the profiles of temperature, will be determined for various distributions of a heat flux. In the case of a two-dimensional problem, the results agree with those in the literature.

  9. Three-axis attitude control by two-step rotations using only magnetic torquers in a low Earth orbit near the magnetic equator

    NASA Astrophysics Data System (ADS)

    Inamori, Takaya; Otsuki, Kensuke; Sugawara, Yoshiki; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

    2016-11-01

    This study proposes a novel method for three-axis attitude control using only magnetic torquers (MTQs). Previously, MTQs have been utilized for attitude control in many low Earth orbit satellites. Although MTQs are useful for achieving attitude control at low cost and high reliability without the need for propellant, these electromagnetic coils cannot be used to generate an attitude control torque about the geomagnetic field vector. Thus, conventional attitude control methods using MTQs assume the magnetic field changes in an orbital period so that the satellite can generate a required attitude control torque after waiting for a change in the magnetic field direction. However, in a near magnetic equatorial orbit, the magnetic field does not change in an inertial reference frame. Thus, satellites cannot generate a required attitude control torque in a single orbital period with only MTQs. This study proposes a method for achieving a rotation about the geomagnetic field vector by generating a torque that is perpendicular to it. First, this study shows that the three-axis attitude control using only MTQs is feasible with a two-step rotation. Then, the study proposes a method for controlling the attitude with the two-step rotation using a PD controller. Finally, the proposed method is assessed by examining the results of numerical simulations.

  10. Perception of self motion during and after passive rotation of the body around an earth-vertical axis.

    PubMed

    Sinha, N; Zaher, N; Shaikh, A G; Lasker, A G; Zee, D S; Tarnutzer, A A

    2008-01-01

    We investigated the perception of self-rotation using constant-velocity chair rotations. Subjects signalled self motion during three independent tasks (1) by pushing a button when rotation was first sensed, when velocity reached a peak, when velocity began to decrease, and when velocity reached zero, (2) by rotating a disc to match the perceived motion of the body, or (3) by changing the static position of the dial such that a bigger change in its position correlated with a larger perceived velocity. All three tasks gave a consistent quantitative measure of perceived angular velocity. We found a delay in the time at which peak velocity of self-rotation was perceived (2-5 s) relative to the beginning or to the end of chair rotation. In addition the decay of the perception of self-rotation was preceded by a sensed constant-velocity interval or plateau (9-14 s). This delay in the rise of self-motion perception, and the plateau for the maximum perceived velocity, contrasts with the rapid rise and the immediate decay of the angular vestibuloocular reflex (aVOR). This difference suggests that the sensory signal from the semicircular canals undergoes additional neural processing, beyond the contribution of the velocity-storage mechanism of the aVOR, to compute the percept of self-motion.

  11. Magnetic rotation (MR) band crossing in N=78 odd-Z nuclei: Tilted axis cranking (TAC) calculations to explore the role of nucleons

    SciTech Connect

    Kumar, Suresh

    2014-08-14

    Magnetic Rotation (MR) band crossing is studied systematically in N=78 isotones (La, Pr, Pm and Eu) using Tilted Axis Cranking (TAC) model. The observables such as I(¯h) vs ¯hω, excitation energy E(MeV) vs spin I(¯h), and the B(M1)/B(E2) vs I(¯h) were considered to pinpoint MR crossing in these nuclei. The results of tilted axis cranking were compared with these experimental observables. The B(M1) and B(E2) values were also reported and used to understand the crossing behaviour of these MR bands. The systematic evolution of this phenomenon in N=78 odd-Z istotones leads to understand the role of nucleons in MR band crossing.

  12. On the rotation rates and axis ratios of the smallest known near-Earth asteroids-The archetypes of the Asteroid Redirect Mission targets

    NASA Astrophysics Data System (ADS)

    Hatch, Patrick; Wiegert, Paul A.

    2015-06-01

    NASA's Asteroid Redirect Mission (ARM) has been proposed with the aim to capture a small asteroid a few meters in size and redirect it into an orbit around the Moon. There it can be investigated at leisure by astronauts aboard an Orion or other spacecraft. The target for the mission has not yet been selected, and there are very few potential targets currently known. Though sufficiently small near-Earth asteroids (NEAs) are thought to be numerous, they are also difficult to detect and characterize with current observational facilities. Here we collect the most up-to-date information on near-Earth asteroids in this size range to outline the state of understanding of the properties of these small NEAs. Observational biases certainly mean that our sample is not an ideal representation of the true population of small NEAs. However our sample is representative of the eventual target list for the ARM mission, which will be compiled under very similar observational constraints unless dramatic changes are made to the way near-Earth asteroids are searched for and studied. We collect here information on 88 near-Earth asteroids with diameters less than 60 m and with high quality light curves. We find that the typical rotation period is 40 min. Relatively few axis ratios are available for such small asteroids, so we also considered the 92 smallest NEAs with known axis ratios. This sample includes asteroids with diameters up to 300 m. The mean and median axis ratios were 1.43 and 1.29, respectively. Rotation rates much faster than the spin barrier are seen, reaching below 30 s, and implying that most of these bodies are monoliths. Non-principal axis rotation is uncommon. Axial ratios often reach values as high as two, though no undisputed results reach above three. We find little correlation of axis ratio with size. The most common spectral type in the sample of small NEAs is S-type (> 90 %), with only a handful of C and X types known.

  13. The ultimate arc: Differential displacement, oroclinal bending, and vertical axis rotation in the External Betic-Rif arc

    NASA Astrophysics Data System (ADS)

    Platt, J. P.; Allerton, S.; Kirker, A.; Mandeville, C.; Mayfield, A.; Platzman, E. S.; Rimi, A.

    2003-06-01

    The External Betic-Rif arc, which lies between the converging African and Iberian plates, is one of the tightest orogenic arcs on Earth. It is a thin-skinned fold and thrust belt formed in Miocene time around the periphery of the Alborán Domain, an older contractional orogen that underwent extensional collapse coevally with the formation of the thrust belt. Restoration of four sections across the thrust belt, together with kinematic and paleomagnetic analysis, allows a reconstruction of the prethrusting geometry of the Alborán Domain, and the identification of the following processes that contributed to the formation of the arc: (1) The Alborán Domain moved some 250 km westward relative to Iberia and Africa during the Miocene. This initiated the two limbs of the arc on its NW and SW margins, closing to the WSW in the region of Cherafat in northern Morocco. The overall convergence direction on the Iberian side of the arc was between 310° and 295°, and on the African side it was between 235° and 215°. The difference in convergence direction between the two sectors was primarily a result of the relative motion between Africa and Iberia. (2) Extensional collapse of the Alborán Domain during the Miocene modified the geometry of the western end of the arc: the Internal Rif rotated anticlockwise to form the present north trending sector of the arc, and additional components of displacement produced by extension were transferred into the external thrust belt along a series of strike-slip faults and shear zones. These allowed the limbs of the arc to rotate and extend, tightening the arc, and creating variations in the amounts and directions of shortening around the arc. The Betic sector of the arc rotated clockwise by 25° during this process, and the southern Rif rotated anticlockwise by ˜55°. (3) Oblique convergence on the two limbs of the arc, dextral in the Betics and sinistral in the southern Rif, resulted in strongly noncoaxial deformation. This had three

  14. Measuring the off-axis angle and the rotational movements of phonating sperm whales using a single hydrophone.

    PubMed

    Laplanche, Christophe; Adam, Olivier; Lopatka, Maciej; Motsch, Jean-François

    2006-06-01

    The common use of the bent-horn model of the sperm whale sound generator describes sperm whale clicks as the pulse series {p0, p1, p2, p3,...}. Clicks, however, deviate from this standard when recorded using off-axis hydrophones. The existence of additional pulses within the {p0, p1, p2, p3, ...} series can be explained still using the bent-horn model. Multiple reflections on the whale's frontal and distal sacs of the p0 pulse lead to additional sets of pulses detectable using a farfield, off-axis hydrophone. The travel times of some of these additional pulses depend on the whale's orientation. The authors propose a method to estimate the off-axis angle of sperm whale clicks. They also propose a method to determine the nature of the movement (if it is pitch, yaw, or roll) of phonating sperm whales. The application of both methods requires the measurement of the travel time differences between pulses composing a sperm whale click. They lead, using a simple apparatus consisting of a single hydrophone at an unknown depth, to new measurements of the underwater movements of sperm whales. Using these methods shows that sperm whales would methodically scan seawater while searching for prey, by making periodic pitch and yaw movements in sync with their acoustic activity.

  15. Rapid rotations about a vertical axis in a collisional setting revealed by the Palu Fault, Sulawesi, Indonesia

    NASA Astrophysics Data System (ADS)

    Stevens, C.; McCaffrey, R.; Bock, Y.; Genrich, J.; Endang, null; Subarya, C.; Puntodewo, S. S. O.; Fauzi, null; Vigny, C.

    Global Positioning System (GPS) measurements from 1992 to 1995 indicate that the left-lateral Palu fault in central Sulawesi slips at a rate of 38±8 mm/a with a locking depth between 2 and 8 km. From the measured slip rate and the historic seismicity of the fault, we estimate that the Palu fault currently has stored enough strain to produce a Mw>7 earthquake. The Palu and other nearby faults accommodate rapid clockwise rotation of nearly 4°/Ma of E Sulawesi relative to eastern Sunda. The rotation of east Sulawesi transfers E-W shortening between the Pacific and Eurasian plates to N-S subduction of the Celebes Basin beneath Sulawesi.

  16. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Cortés, José M.; Terrizzano, Carla M.

    2017-03-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to 450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  17. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Cortés, José M.; Terrizzano, Carla M.

    2016-05-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to ~450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  18. Kinematic Implications of New Paleomagnetic Data From the Northern Walker Lane, Western Nevada: Counterintuitive Anticlockwise Vertical-Axis Rotation in an Incipient Dextral Shear Zone

    NASA Astrophysics Data System (ADS)

    Faulds, J. E.; Henry, C. D.; Hinz, N. H.; Delwiche, B.; Cashman, P. H.

    2004-12-01

    ). Slight anticlockwise rotation is also supported by paleomagnetic data from the 28.6 Ma tuff of Campbell Creek (D=191, I= -40 [2 sites] compared to reference direction of D=205, I= -43, a95=3 [10 sites in Sierra Nevada]) and the predominance of WNW-striking strata in these fault blocks, which contrasts with a more northerly striking regional norm. However, data from the Nine Hill Tuff do indicate 30-60 deg of clockwise rotation (D=16, I=47, a95=10, 6 sites) in narrow 2 km wide bands along major dextral faults in the NWL. In the transtensional setting of the NWL, the slight anticlockwise rotation may reflect coeval E-W to WNW regional extension and NW-directed dextral shear. In this model, extension induces a domino-like, map-view collapse and slight anticlockwise rotation of fault blocks between the left-stepping dextral faults. The anticlockwise rotation is opposite to the clockwise rotation typically found in dextral shear zones. Anticlockwise rotation may ultimately rotate Riedel shears toward the main shear zone at depth, thus facilitating eventual development of a through-going, upper-crustal strike-slip fault. Ironically, as the system matures and a through-going fault develops, the predominant sense of vertical-axis rotation may reverse and become compatible with the dextral sense of shear. Such complex kinematics may characterize incipient strike-slip fault systems in both transtensional and transpressional settings.

  19. Vertical-Axis Rotations Within Columbia River Basalt Flows Define a Sharp Eastern Boundary of the Coast Range Block with Potentially Increased Seismic Risk for Portland, Oregon

    NASA Astrophysics Data System (ADS)

    Hagstrum, J. T.; Wells, R. E.; Evarts, R. C.; Blakely, R. J.; Beeson, M. H.

    2006-12-01

    Paleomagnetic analysis of the Miocene Columbia River Basalt Group (CRBG) in the northern Willamette Valley of Oregon was undertaken as part of a larger mapping and hydrogeologic investigation of the CRBG's internal stratigraphy and structure. Differences in paleomagnetic directions between flows due to geomagnetic reversals and paleosecular variation, in combination with geochemical data, provide the most reliable means of flow identification. In addition, vertical-axis rotations between CRBG sites in the Portland area and sampling localities within the same flow units on the relatively stable Columbia Plateau were calculated. Clockwise rotations for sites within the northern Willamette Valley are remarkably consistent and have a weighted mean of 29°±3° (N=94). Available paleomagnetic data from CRBG sites along the Oregon coast at Cape Lookout (19°±22°, N=4) and Cape Foulweather (29°±18°, N=4) show similar results. East of the Portland Hills fault zone along the Columbia River Gorge, however, clockwise rotations are much less averaging 12°±3° (N=15). North of Portland, the CRBG rotational values drop abruptly from ~29° to 6°±17° (N=3) across an unnamed fault near Woodland, WA, identified using aeromagnetic data; to the south, the values drop from ~29° to 18°±3° (N=6) across the Mt. Angel-Gales Creek fault zone east of Salem, OR. The eastern boundary of the Oregon Coast Range block is thus defined by three offset NW-trending fault segments, with the offsets corresponding to the Portland and Willamette pull-apart basins. North of the Coast Range block's northern boundary, which is roughly coincident with the Columbia River, CRBG rotations also are about half that (15°±3°, N=15) found within the block. Northward movement and clockwise rotation of the Oregon Coast Range block have previously been modeled as decreasing continuously eastward to the Columbia Plateau. Our new paleomagnetic data indicate an abrupt step down of rotational values by

  20. The influence of an inner core, tides, and precession of the pericenter on the orientation of the rotation axis of Mercury

    NASA Astrophysics Data System (ADS)

    Baland, Rose-Marie; Yseboodt, Marie; Van Hoolst, Tim; Rivoldini, Attilio

    2016-10-01

    Mercury's spin axis occupies the Cassini state 1, in which the orbit normal and spin axis precess together with a long period of about 300 000 years. An accurate model of the Cassini state is needed to get a reliable estimate of its polar moment of inertia from the measured orientation of its spin axis. The polar moment of inertia provides a strong constraint on the interior structure. For long, it has been assumed that Mercury precesses as a solid body, meaning that the estimate of the polar moment of inertia may be inaccurate. Recently, there has been renewed interest for the topic, because of the recent determination of Mercury's rotation state (Earth-based radar observations, MESSENGER data), as well as the possibility of future more accurate measurements with the BepiColombo mission.Here, we revisit the influence of the liquid outer core, solid inner core, and precession of the pericenter (period of about 127 000 years). Previous studies have concluded that those effects may have an influence above or up to about an order of magnitude below the present uncertainty on the obliquity. We consider three-layer interior models with a mantle (including the crust), a liquid outer core and a solid inner core. Those models are constrained by the mass, radius, second-degree gravity field coefficients and libration amplitude. We adapt to Mercury a Cassini state model previously developed for synchronous satellites, in which we express the spin axis motion in a frame based on the Laplace plane. We take into account the solar gravitational torque exerted on each layer, the internal gravitational torques between the internal layers and the pressure torques as well as the dissipative viscous torques exerted at the interfaces. We reassess the effect of tidal periodic deformations on the torques, currently thought to be two orders of magnitude below the present uncertainty on the spin orientation determination. Finally, we use the current rotation data to constrain Mercury

  1. Magnetostratigraphy and Paleomagnetism of the Palm Spring and Mecca Formations, Mecca Hills, CA: spatial variation of vertical axis rotation in the Coachella Valley

    NASA Astrophysics Data System (ADS)

    Housen, B. A.; Fattaruso, L.; McNabb, J. C.; Dorsey, R. J.; Messe, G. T.; Cooke, M. L.

    2013-12-01

    to the NW of the Mecca Hills, which are bound by the San Jacinto and San Andreas faults, (Hehn et al, 1996) indicated consistent 10 to 20° CCW rotations. Overall, these results highlight significant variations in the amount and sense of block rotations in the Coachella Valley. Patterns and magnitudes of CW and CCW rotations derived from 3-D boundary element models (see also Fattaruso et al, this session) of the Coachalla Valley can be compared with these independent paleomagnetic data. Initial comparison indicates that the zones of CW and CCW rotation observed in the paleomagnetic results from the San Timoteo and Borrego Badlands, and the Mecca Hills agree well with model results. Additionally, smaller faults- such as the Painted Canyon and Inspiration Point faults- often demarcate areas with differing amounts, and sense, of vertical axis rotation, and thus these structures play an important role in the structural development of these fault zones.

  2. Bending and shear stresses developed by the instantaneous arrest of the root of a cantilever beam rotating with constant angular velocity about a transverse axis through the root

    NASA Technical Reports Server (NTRS)

    Stowell, Elbridge Z; Schwartz, Edward B; Houbolt, John C

    1945-01-01

    A theoretical investigation was made of the behavior of a cantilever beam in rotational motion about a transverse axis through the root determining the stresses, the deflections, and the accelerations that occur in the beam as a result of the arrest of motion. The equations for bending and shear stress reveal that, at a given percentage of the distance from root to tip and at a given trip velocity, the bending stresses for a particular mode are independent of the length of the beam and the shear stresses vary inversely with the length. When examined with respect to a given angular velocity instead of a given tip velocity, the equations reveal that the bending stress is proportional to the length of the beam whereas the shear stress is independent of the length. Sufficient experimental verification of the theory has previously been given in connection with another problem of the same type.

  3. Discordant paleomagnetic data for middle-Cretaceous intrusive rocks from northern Baja California: Latitude displacement, tilt, or vertical axis rotation?

    NASA Astrophysics Data System (ADS)

    BöHnel, Harald; Delgado-Argote, Luis A.; Kimbrough, David L.

    2002-10-01

    Paleomagnetic results and U/Pb zircon dating from the San Marcos dike swarm and the El Testerazo pluton in the Cretaceous Peninsular Ranges batholith of northern Baja California are used to evaluate alternative pre-Neogene paleogeographic reconstructions of the Baja California peninsula. The San Marcos dike swarm is a dense, northwest striking, regional dike swarm that is exposed over an ˜100 km long segment of the batholith and has yielded a U/Pb zircon crystallization age of 120 ± 1 Ma. Dike attitudes from the swarm suggest a regionally consistent average ˜320°E strike and ˜79°NE dip. The El Testerazo pluton is a younger tonalite intrusion that truncates the northern end of the dike swarm. All but one of 36 sites sampled in this study show remanence of normal polarity. Paleopoles for the San Marcos dike swarm and El Testerazo pluton are indistinguishable and were combined into a paleopole at 248.1°E, 86.6°N, A95 = 4.8°, which is displaced with respect to the 122 Ma reference pole for stable North America at 198.2°E, 72.3°N, A95 = 3.3°. The displacement may be described by an apparent clockwise rotation of 18° ± 6° and an apparent northward shift of 8° ± 5°. Restoring a northward shift of about 3°, related to the separation of Baja California from North America since 10 Ma, only a marginal northward displacement of 5° ± 5° is left. The clockwise rotation may be the result of crustal block rotations within the right-lateral shear systems in northern Baja California, although there is no geological evidence that supports this possibility. Alternatively, the difference between paleopole and reference pole may be due to tilting of the study area. Restoring a northeastward tilt of 11°, based on the mean dip measured for the San Marcos dike swarm in the study area, yields a paleopole at 187.6°E, 70.8°N, A95 = 5.6°, which is indistinguishable from the 122 Ma North American reference pole. The tilting hypothesis suggested previously as a

  4. The Research of Variation of the Period and Precession of the Rotation Axis of EGS (AJISAI) Satellite by Using Photometric Measurement

    NASA Astrophysics Data System (ADS)

    Burlak, N.; Koshkin, N.; Korobeynikova, E.; Melikyants, S.; Shakun, L.; Strakhova, S.

    The light curves of EGS Ajisai with temporal resolution of 20 ms referred to the time scale UTC (GPS) with an error of at most 0.1 ms were obtained. The observed flashes are produced when the mirrors which cover the spinning satellite's surface reflect off the sunlight. In previous paper the analysis of sequence of flashes allowed of reconstructing the arrangement and orientation of the mirrors, i.e. developing an optogeometric model of the satellite (Korobeynikova et al., 2012), and to apply that model along with new photometric observations to determine the satellite's sidereal rotational period with an accuracy that was previously unachievable. A new technique for determination of the spin-axis orientation during each passage of the satellite over an observation site was developed. The secular slowdown of the satellite's spin rate (Psid = 1.4858*EXP(0.000041099*T), where T is measured in days counted from the date of the satellite launch) and its variations correlating with the average duration of the satellite orbit out of the Earth's shadow were refined. New parameters of the spin-axis precession were estimated: the period Pprec = 116.44 days, αprec = 18.0h, δprec = 87.66°, the nutation angle θ = 1.78°.

  5. No vertical axis rotations during Neogene transpressional orogeny in the NE Gobi Altai: coinciding Mongolian and Eurasian early Cretaceous apparent polar wander paths

    NASA Astrophysics Data System (ADS)

    Straathof, G. B.; Hinsbergen, D. V.; Kuiper, K. F.; Cunningham, W.; Wijbrans, J.

    2007-12-01

    Here we test the role of vertical axis rotations during transpressional mountain building. To this end, we carried out a paleomagnetic study in the NE Gobi Altai of southern Mongolia, sampling widely exposed lower Cretaceous lavas allowing comparison of rotation histories of the Ih Bogd, Baga Bogd and Artz Bogd restraining bends at the eastern termination of the Bogd strike-slip zone. We provide new 40Ar/39Ar ages to show that the stratigraphy of mafic lavas and fluvio-lacustrine sediments on the southern flanks of Mt Ih Bogd and Mt Baga Bogd have ages between ~125 and ~122 Ma, and a mafic sill that intrudes the sequence has an age of 118.2 ± 0.8 Ma. The lavas are older than previously dated lavas south of Artz Bogd, with ages of 119-115 Ma. Paleomagnetic results from the 119-115 Ma lavas south of Artz Bogd show a significant steeper inclination than both results from 125-122 Ma lavas of Baga Bogd and Ih Bogd, as well as from newly sampled and previously published younger lavas and necks of the 107-92 Ma Tsost Magmatic Field and Shovon and Khurmen Uul basalts. We explain this result by insufficient averaging of secular variation and small errors induced by overcorrection of bedding tilt. We show that individual lavas in the SE Artz Bogd locality represent individual spot readings of the Earth's magnetic field and integrate all results obtained from lower Cretaceous lavas in the Gobi Altai. We present a pole, or rather, an apparent polar wander path without significant plate motion from ~125-95 Ma, with n=126, ë=80.8, ö=158.4, ê=25.3, A95=2.5, paleo-latitude = 48.2 with a scatter Së=16.7 (Sl=15.3, Su=17.8) and a regionally consistent direction for the Gobi Altai of D/I = 11.1/65.9, ÄD/ÄI = 3.8/1.9. This is one of the best-determined paleopoles/APWP's for Asia. There is no significant deviation of the 125-95 Ma pole position of the Gobi Altai from the reference positions of Eurasia. Formation of the Ih Bogd, Baga Bogd and Artz Bogd restraining bends was thus

  6. Design of non-selective refocusing pulses with phase-free rotation axis by gradient ascent pulse engineering algorithm in parallel transmission at 7T.

    PubMed

    Massire, Aurélien; Cloos, Martijn A; Vignaud, Alexandre; Le Bihan, Denis; Amadon, Alexis; Boulant, Nicolas

    2013-05-01

    At ultra-high magnetic field (≥ 7T), B1 and ΔB0 non-uniformities cause undesired inhomogeneities in image signal and contrast. Tailored radiofrequency pulses exploiting parallel transmission have been shown to mitigate these phenomena. However, the design of large flip angle excitations, a prerequisite for many clinical applications, remains challenging due the non-linearity of the Bloch equation. In this work, we explore the potential of gradient ascent pulse engineering to design non-selective spin-echo refocusing pulses that simultaneously mitigate severe B1 and ΔB0 non-uniformities. The originality of the method lays in the optimization of the rotation matrices themselves as opposed to magnetization states. Consequently, the commonly used linear class of large tip angle approximation can be eliminated from the optimization procedure. This approach, combined with optimal control, provides additional degrees of freedom by relaxing the phase constraint on the rotation axis, and allows the derivative of the performance criterion to be found analytically. The method was experimentally validated on an 8-channel transmit array at 7T, using a water phantom with B1 and ΔB0 inhomogeneities similar to those encountered in the human brain. For the first time in MRI, the rotation matrix itself on every voxel was measured by using Quantum Process Tomography. The results are complemented with a series of spin-echo measurements comparing the proposed method against commonly used alternatives. Both experiments confirm very good performance, while simultaneously maintaining a low energy deposition and pulse duration compared to well-known adiabatic solutions.

  7. Rotational testing.

    PubMed

    Furman, J M

    2016-01-01

    The natural stimulus for the semicircular canals is rotation of the head, which also might stimulate the otolith organs. Vestibular stimulation usually induces eye movements via the vestibulo-ocular reflex (VOR). The orientation of the subject with respect to the axis of rotation and the orientation of the axis of rotation with respect to gravity together determine which labyrinthine receptors are stimulated for particular motion trajectories. Rotational testing usually includes the measurement of eye movements via a video system but might use a subject's perception of motion. The most common types of rotational testing are whole-body computer-controlled sinusoidal or trapezoidal stimuli during earth-vertical axis rotation (EVAR), which stimulates primarily the horizontal semicircular canals bilaterally. Recently, manual impulsive rotations, known as head impulse testing (HIT), have been developed to assess individual horizontal semicircular canals. Most types of rotational stimuli are not used routinely in the clinical setting but may be used in selected research environments. This chapter will discuss clinically relevant rotational stimuli and several types of rotational testing that are used primarily in research settings.

  8. Rotatable shear plate interferometer

    DOEpatents

    Duffus, Richard C.

    1988-01-01

    A rotatable shear plate interferometer comprises a transparent shear plate mounted obliquely in a tubular supporting member at 45.degree. with respect to its horizontal center axis. This tubular supporting member is supported rotatably around its center axis and a collimated laser beam is made incident on the shear plate along this center axis such that defocus in different directions can be easily measured.

  9. Mars: destruction of the tropical belt and building up extra tropics is a physical requirement of angular momentum equilibration between zones with different distances to the rotation axis

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2012-09-01

    Often observed a sensible difference in appearance and structure between tropical and extra-t ropical zones of various heavenly bodies including rocky and gas planets, satellites and Sun (Fig. 6) compels to look for a common reason of such phenomenon [1-3]. All bodies rotate and their spherical shape makes zones at different lat itudes to have differing angular momenta as a distance to the rotation axis diminishes gradually from the equator to the poles (Fig. 1) (this is felt particularly when one launches rockets into space -preferable cheaper launches are from the equatorial regions - Kourou in the French Guyana is better than Baikonur in Kazakhstan). One of remarkable changes occurs at tropics. As a total rotating planetary body tends to have angular momenta of its tectonic blocks equilibrated it starts mechanisms leveling this basic physical property. At tropical zones (bulged also due to the rotation ellipsoid) the outer shell - crust as a consequence tends to be destroyed, sunk, subsided and shrunk; a density of crust material changes; the atmosphere reacts changing chemistry and structure; in terrestrial anthroposphere man looses its mass and stature (well known pygmioidness process). Ext ratropical belts, on the contrary, tend to add material and increase radius. Thus, a body tends to be like a cucumber but mighty gravity always makes it globular. According to the Le Chatelier rule mechanisms with opposing tendencies also begin to act. However, traces of this cosmic "struggle" very often are seen on surfaces of heavenly bodies as structurally distinguished tropical and extra-t ropical zones (Fig. 1, 6) [1-3]. At Mars the widespread "enigmatic" chaotic and fretted terrains at the highland-lowland boundary could be considered as traces of the crust destruction along the wide tropical belt (Fig. 2-4). A system of hillocks and their relics, mesas, ridges, cliffs and separating them depressions or plains (deep up to 1-2 km) is controlled by a crosscutting

  10. Io's Volcanoes: Possible Influence on Spin Axis

    NASA Astrophysics Data System (ADS)

    Stoddard, P. R.; Jurdy, D. M.

    2002-03-01

    Massive outpourings of lava in short intervals could cause an instability in Io's rotation and a reorientation of its spin axis. The volcanos and mountains exhibit a complementary distribution, with the maximum principal inertia axis for volcanos close to the position of the rotation axis.

  11. Piezostrain tuning non-volatile 90° magnetic easy axis rotation in Co2FeAl Heusler alloy film grown on Pb(Mg1/3Nb2/3)O3-PbTiO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Zhou, Cai; Wang, Fenglong; Dunzhu, Gesang; Yao, Jinli; Jiang, Changjun

    2016-11-01

    Non-volatile electric field-based control of magnetic anisotropy in Co2FeAl/ Pb(Mg1/3Nb2/3)O3-PbTiO3 (CFA/PMN-PT) heterostructures is investigated at room temperature. The remnant magnetization response under different electric fields shows a asymmetric butterfly-like behavior; specifically, this behavior is consistent with the asymmetric butterfly-like piezostrain versus applied electric field curve. Thus electric field-induced non-volatile 90° magnetic easy axis rotation can be attributed to the piezostrain effect. Further, the result measured by rotating-angle ferromagnetic resonance demonstrates piezostrain-mediated non-volatile 90° magnetic easy axis rotation at the initial state and the two remnant polarization states after application of the poling fields of 10 and  -10 kV cm-1 turned off. The angular dependence of magnetic damping also indicates a 90° phase shift at the above mentioned three different states. Additionally, the piezostrain-mediated non-volatile stable magnetization reversal in the two directions of easy and hard magnetization axes are observed under positive and negative pulsed electric fields, which can be used to improve the performance of low-loss multiple-state memory devices.

  12. Paleomagnetic evidence for vertical-axis rotations of crustal blocks in the Woodlark Rift, SE Papua New Guinea: Miocene to present-day kinematics in one of the world's most rapidly extending plate boundary zones

    NASA Astrophysics Data System (ADS)

    Cairns, Elizabeth A.; Little, Timothy A.; Turner, Gillian M.; Wallace, Laura M.; Ellis, Susan

    2015-07-01

    The continental Woodlark Rift, in SE Papua New Guinea lies west of a propagating oceanic spreading center in the Woodlark Basin and is currently one of few places on Earth where active continental breakup is thought to be occurring. Here north-south extension is localized on a few major normal faults. We determined characteristic remanent magnetization (ChRM) components from demagnetization profiles of >300 individual specimens. From these, 157 components contribute to paleomagnetic directions for six formations. We compare Early Miocene (˜20 Ma) to Late Pliocene (3.0 ± 0.5) ChRM mean directions, at four localities, with contemporaneous expected field directions corresponding to the Australian Plate. Time-varying finite rotations from Cape Vogel Peninsula (28-12°) suggest anticlockwise rotation had begun by ˜15 Ma. This rotation may have been accompanied by rifting, ˜7 Ma earlier than previously inferred. Furthermore, that early extension may have occurred south of the present rift, and that deformation later migrated north of the Peninsula. Pliocene vertical-axis rotations are consistent with GPS-determined plate motions, suggesting that contemporary rift kinematics were established by ˜3 Ma. Finite anticlockwise rotation (10.1 ± 7.6°) in the Amphlett Islands is accordant with seafloor spreading in the Woodlark Basin, suggesting this locality has seen the full Woodlark plate motion since 3 Ma. Clockwise rotation of the Goodenough Bay Block (-6.5 ± 11.2°) since the Late Miocene has accomplished transfer of deformation between major extensional corridors, and an especially rapid local rotation (-16.3 ± 9.5°) in NW Normanby Island may suggest an incipient dextral transfer fault.

  13. Vertical axis windmill

    SciTech Connect

    Campbell, J.S.

    1980-04-08

    A vertical axis windmill is described which involves a rotatable central vertical shaft having horizontal arms pivotally supporting three sails that are free to function in the wind like the main sail on a sail boat, and means for disabling the sails to allow the windmill to be stopped in a blowing wind.

  14. Helical axis stellarator with noninterlocking planar coils

    DOEpatents

    Reiman, Allan; Boozer, Allen H.

    1987-01-01

    A helical axis stellarator using only noninterlocking planar, non-circular coils, generates magnetic fields having a magnetic well and large rotational transform with resultant large equilibrium beta.

  15. Design and analysis of horizontal axis rotor with increased power output due to an array of rotating tip-devices and their mirror images within an axi-symmetric ground-effect generator

    SciTech Connect

    Basic, S.L.

    1996-10-01

    This paper extends applicability of the ground effect theory to the refinement of the rotor-rotating shroud concept. In light of Prandtl`s conformal transformation, the main aerodynamic performances of a wing flying in proximity of the ground and at heights that are less than its single semi-span, will be changed. For example, the lift of a real wing will be equal to the lift of /its ground-generated mirror image wing, whose lift acts in opposite direction, i.e., in direction of the real wing`s lift. According to test substantiation of the theory, a real wing flying in respect to its mirror image generator at the height amounting to 0.21% of its span, has its drag reduced by 20% its lift increased by 20% and its lift to drag ratio increased by 50%. This substantial improvement in performances of the real wing was the main reason for creation of an axisymmetric ground-effect generator of the mirror images of the tip-devices in form of a simple narrow stationary conical surface in space surrounding the rotating shroud.

  16. Aeroelastically coupled blades for vertical axis wind turbines

    DOEpatents

    Paquette, Joshua; Barone, Matthew F.

    2016-02-23

    Various technologies described herein pertain to a vertical axis wind turbine blade configured to rotate about a rotation axis. The vertical axis wind turbine blade includes at least an attachment segment, a rear swept segment, and optionally, a forward swept segment. The attachment segment is contiguous with the forward swept segment, and the forward swept segment is contiguous with the rear swept segment. The attachment segment includes a first portion of a centroid axis, the forward swept segment includes a second portion of the centroid axis, and the rear swept segment includes a third portion of the centroid axis. The second portion of the centroid axis is angularly displaced ahead of the first portion of the centroid axis and the third portion of the centroid axis is angularly displaced behind the first portion of the centroid axis in the direction of rotation about the rotation axis.

  17. A paleomagnetic investigation of vertical-axis rotations in coastal Sonora, Mexico: Evidence for distributed transtensional deformation during the Proto-Gulf shift from a subduction-dominated to transform-dominated plate boundary in the Gulf of California

    NASA Astrophysics Data System (ADS)

    Herman, Scott William

    The history of late Miocene (Proto-Gulf) deformation on the Sonoran margin of the Gulf of California is key to understanding how Baja California was captured by the Pacific plate and how strain was partitioned during the Proto-Gulf period (12.5-6 Ma). The Sierra el Aguaje and Sierra Tinajas del Carmen are located in southwestern coastal Sonora, Mexico, and represent the eastern rifted margin of the central Gulf of California. The ranges are composed of volcanic units and their corresponding volcaniclastic units which are the result of persistent magmatic activity between 20 and 8.8 Ma, including three packages of basalt and andesite that make excellent paleomagnetic recorders. Based on cross cutting relations and geochronologic data for pre-, syn-, and post-tectonic volcanic units, most of the faulting and tilting in the Sierra El Aguaje is bracketed between 11.9 and 9.0 Ma, thus falling entirely within Proto-Gulf time. A paleomagnetic investigation into possible vertical axis rotations in the Sierra el Aguaje has uncovered evidence of clockwise rotations between ~13º and ~105º with possible translations. These results are consistent with existing field relations, which suggest the presence of large (>45°) vertical axis rotations in this region. This evidence includes: a) abrupt changes in the strike of tilted strata in different parts of the range, including large domains characterized by E-W strikes b) ubiquitous NE-SW striking faults with left lateral-normal oblique slip, that terminate against major NW-trending right lateral faults, and c) obliquity between the general strike of tilted strata and the strike of faults. These rotations occurred after 12 Ma and largely prior to 9 Ma, thus falling into the Proto-Gulf period. Such large-scale rotations lend credence to the theory that the area inboard of Baja California was experiencing transtension during the Proto-Gulf period, rather than the pure extension that would be the result of strain partitioning

  18. Paleomagnetism of the Miocene Columbia River Basalt Group in Oregon and Washington from the Pacific Coast to the Columbia Plateau: Magnetostratigraphy, Vertical-Axis Rotations, Paleosecular Variation, and Remagnetization

    NASA Astrophysics Data System (ADS)

    Hagstrum, J. T.; Wells, R. E.; Evarts, R. C.; Niem, A. R.; Sawlan, M. G.; Blakely, R. J.

    2008-12-01

    Identification of individual flows within the Columbia River Basalt Group (CRBG) has mostly relied on minor differences in geochemistry, but magnetic polarity has also proved useful in differentiating flows and establishing a temporal framework. Within the thick, rapidly erupted Grande Ronde Basalt four major polarity chrons (R1 to N2) have been identified. Because cooling times of CRBG flows are brief compared to rates of paleosecular variation (PSV), within-flow paleomagnetic directions are expected to be constant across the extensive east-west reaches of these flows. Vertical-axis rotations in OR and WA, driven by northward-oblique subduction of the Juan de Fuca plate, thus can be measured by comparing directions for western sampling localities to directions for the same flow units on the relatively stable Columbia Plateau. Clockwise rotations calculated for outcrop locations within the Coast Range (CR) block are uniformly about 30° (N=102 sites). East of the northwest-trending en échelon Mt. Angel-Gales Creek, Portland Hills, and northern unnamed fault zones, as well as north of the CR block's northern boundary (~Columbia River), clockwise rotations abruptly drop to about 15° (N=39 sites), with offsets in these bounding fault zones corresponding to the Portland and Willamette pull-apart basins. The general agreement of vertical- axis rotation rates estimated from CRBG magnetizations with those determined from modern GPS velocities indicates a relatively steady rate over the last 10 to 15 Myr. Unusual directions due to PSV, field excursions, or polarity transitions could provide useful stratigraphic markers. Individual flow directions, however, have not been routinely used to identify flows. One reason this has been difficult is that remagnetization is prevalent, particularly in the Coast Ranges, coupled with earlier demagnetization techniques that did not completely remove overprint components. Except for the Ginkgo and Pomona flows of the Wanapum and Saddle

  19. Evidence of Vibrational-Induced Rotational Axis Switching for HD 12C 16O: New High-Resolution Analysis of the ν 5 and ν 6 Bands and First Analysis of the ν 4 Band (10-μm Region)

    NASA Astrophysics Data System (ADS)

    Perrin, A.; Flaud, J.-M.; Smirnov, M.; Lock, M.

    2000-09-01

    Using new high-resolution Fourier transform spectra recorded in Giessen in the 8-12 μm region, a more extended analysis of the ν5 and ν6 bands and the first high-resolution study of the ν4 band of HDCO were performed. As pointed out previously [M. Allegrini, J. W. C. Johns, and A. R. W. McKellar, Can. J. Phys. 56, 859-864 (1978)], the energy levels of the 51 and 61 states are strongly coupled by A- and B-type Coriolis interactions. On the other hand, it appeared that weaker resonances involving the energy levels of the 41 state with those of the 51 and 61 states also had to be accounted for. Consequently, the calculation of the energy levels was performed taking into account the Coriolis-type resonances linking the energy levels of the {61, 51, 41} resonating states. Because of the unusually strong Coriolis interaction between ν5 and ν6, a nonclassical behavior of the rotational levels of the 51 and 61 states was observed and it was necessary to use a new Hamiltonian matrix which possesses, as usual, both A- and B-type Coriolis operators in the 51 ⇔ 61 and 61 ⇔ 41 off diagonal blocks but differs from the classical reduced Hamiltonian which is used commonly for planar Cs-type molecules. More precisely, it proved necessary to include non-orthorhombic terms in the expansion of the rotational Hamiltonian of the 51 and 61 states. According to the considerations developed by Watson [J. K. G. Watson, in 'Vibrational Spectra and Structure,' (J. Durig, Ed.), Chap. 1, Elsevier, Amsterdam, 1977], these non-orthorhombic operators which are not symmetry forbidden are usually removed for semirigid Cs-type molecules by rotational contact transformations. In the present study, the occurrence of terms in {Jx, Jz} in the expansions of the rotational Hamiltonians for the 51 and 61 states indicates that the inertial system of HDCO differs for each of the three {61, 51, 41} resonating states. Therefore, HDCO becomes a good example of vibrational-induced rotational axis

  20. Shaft-Rotation Detector

    NASA Technical Reports Server (NTRS)

    Randall, Richard L.

    1990-01-01

    Signal-processing subsystem generates signal indicative of rotation of shaft from output of accelerometer mounted on housing of bearing supporting shaft. Output of subsystem binary signal at frequency of rotation of shaft. Part of assembly of electronic equipment measuring vibrations in rotating machinery. Accelerometer mounted in such way sensitive to vibrations of shaft perpendicular to axis. Output of accelerometer includes noise and components of vibration at frequencies higher than rotational frequency of shaft.

  1. Two-axis angular effector

    DOEpatents

    Vaughn, Mark R.; Robinett, III, Rush D.; Phelan, John R.; Van Zuiden, Don M.

    1997-01-21

    A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.

  2. Earth Rotation

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.

    1995-01-01

    The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.

  3. Omni-directional and holonomic rolling platform with decoupled rotational and translational degrees of freedom

    DOEpatents

    Pin, F.G.; Killough, S.M.

    1994-12-20

    A wheel assembly includes a support, a cage rotatably mounted on the support and having a longitudinal rotation axis, a first ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis of the cage, and a second ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis or the cage and to the rotation axis of the first ball wheel. A control circuit includes a photodetector signal which indicates ground contact for each ball wheel, and a tachometer which indicates actual drive shaft velocity. 6 figures.

  4. Omni-directional and holonomic rolling platform with decoupled rotational and translational degrees of freedom

    DOEpatents

    Pin, Francois G.; Killough, Stephen M.

    1994-01-01

    A wheel assembly includes a support, a cage rotatably mounted on the support and having a longitudinal rotation axis, a first ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis of the cage, and a second ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis or the cage and to the rotation axis of the first ball wheel. A control circuit includes a photodetector signal which indicates ground contact for each ball wheel, and a tachometer which indicates actual drive shaft velocity.

  5. Vertical axis wind turbine airfoil

    DOEpatents

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  6. Rotational joint assembly and method for constructing the same

    NASA Technical Reports Server (NTRS)

    Bandera, Pablo (Inventor); Buchele, Paul (Inventor)

    2012-01-01

    A rotational joint assembly and a method for constructing a rotational joint assembly are provided. The rotational joint assembly includes a first rotational component, a second rotational component coupled to the first rotational component such that the second rotational component is rotatable relative to the first rotational component in first and second rotational directions about an axis, and a flexure member, being deflectable in first and second deflection directions, coupled to at least one of the first and second rotational components such that when the second rotational component is rotated relative to the first rotational component in each of the first and second rotational directions about the axis, the flexure member is deflected in the first deflection direction and exerts a force on the second rotational component opposing the rotation.

  7. Rotating cooloing flows

    NASA Technical Reports Server (NTRS)

    Kley, Wilhelm; Mathews, William G.

    1995-01-01

    We describe the evolution of the hot interstellar medium in a large, slowly rotating elliptical galaxy. Although the rotation assumed is a small fraction of the circular velocity, in accordance with recent observations, it is sufficient to have a profound influence on the X-ray emission and cooling geometry of the interstellar gas. The hot gas cools into a disk that extends out to approximately 10 kpc. The cool, dusty disks observed in the majority of elliptical galaxies may arise naturally from internal cooling rather than from mergers with gas-rich companions. As a result of angular momentum conservation in the cooling flow, the soft X-ray isophotes are quite noticeably flatter than those of the stellar image. The gas temperature is higer along the rotation axis. The rotational velocity of the gas several kiloparcsecs above the central disk far exceeds the local stellar rotation and approaches the local circular velocity as it flows toward the galactic core. The detailed appearance of the X-ray image and velocity field of the X-ray gas provide information about the global rotational properties of giant ellipticals at radii too distant for optical observations. The overall pattern of rotation in these galaxies retains information about the origin of ellipticals, particularly of their merging history. In ellipticals having radio jets, if the jets are aligned with the rotation axis of the inner cooling flow, rotation within the jet could be sustained by the rotating environment. Since most large ellipticals have modest rotation, the X-ray observations at low spatial resolution, when interpreted with spherical theoretical models, give the impression that hot gas undergoes localized cooling to very low temperatures many kiloparcsecs from the galactic core. We suggest that such apparent cooling can result in a natural way as gas cools onto a rotating disk.

  8. Three axis attitude control system

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1988-01-01

    A three-axis attitude control system for an orbiting body comprised of a motor driven flywheel supported by a torque producing active magnetic bearing is described. Free rotation of the flywheel is provided about its central axis and together with limited angular torsional deflections of the flywheel about two orthogonal axes which are perpendicular to the central axis. The motor comprises an electronically commutated DC motor, while the magnetic bearing comprises a radially servoed permanent magnet biased magnetic bearing capable of producing cross-axis torques on the flywheel. Three body attitude sensors for pitch, yaw and roll generate respective command signals along three mutually orthogonal axes (x, y, z) which are coupled to circuit means for energizing a set of control coils for producing torques about two of the axes (x and y) and speed control of the flywheel about the third (z) axis. An energy recovery system, which is operative during motor deceleration, is also included which permits the use of a high-speed motor to perform effectively as a reactive wheel suspended in the magnetic bearing.

  9. Centrifugally activated bearing for high-speed rotating machinery

    DOEpatents

    Post, R.F.

    1994-02-15

    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation. 4 figures.

  10. Centrifugally activated bearing for high-speed rotating machinery

    DOEpatents

    Post, Richard F.

    1994-01-01

    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

  11. Galaxy cluster's rotation

    NASA Astrophysics Data System (ADS)

    Manolopoulou, M.; Plionis, M.

    2017-03-01

    We study the possible rotation of cluster galaxies, developing, testing, and applying a novel algorithm which identifies rotation, if such does exist, as well as its rotational centre, its axis orientation, rotational velocity amplitude, and, finally, the clockwise or counterclockwise direction of rotation on the plane of the sky. To validate our algorithms we construct realistic Monte Carlo mock rotating clusters and confirm that our method provides robust indications of rotation. We then apply our methodology on a sample of Abell clusters with z ≲ 0.1 with member galaxies selected from the Sloan Digital Sky Survey DR10 spectroscopic data base. After excluding a number of substructured clusters, which could provide erroneous indications of rotation, and taking into account the expected fraction of misidentified coherent substructure velocities for rotation, provided by our Monte Carlo simulation analysis, we find that ∼23 per cent of our clusters are rotating under a set of strict criteria. Loosening the strictness of the criteria, on the expense of introducing spurious rotation indications, we find this fraction increasing to ∼28 per cent. We correlate our rotation indicators with the cluster dynamical state, provided either by their Bautz-Morgan type or by their X-ray isophotal shape and find for those clusters showing rotation within 1.5 h^{-1}_{70} Mpc that the significance of their rotation is related to the dynamically younger phases of cluster formation but after the initial anisotropic accretion and merging has been completed. Finally, finding rotational modes in galaxy clusters could lead to the necessity of correcting the dynamical cluster mass calculations.

  12. Rotating reactor studies

    NASA Technical Reports Server (NTRS)

    Roberts, Glyn O.

    1991-01-01

    Undesired gravitational effects such as convection or sedimentation in a fluid can sometimes be avoided or decreased by the use of a closed chamber uniformly rotated about a horizontal axis. In a previous study, the spiral orbits of a heavy or buoyant particle in a uniformly rotating fluid were determined. The particles move in circles, and spiral in or out under the combined effects of the centrifugal force and centrifugal buoyancy. A optimization problem for the rotation rate of a cylindrical reactor rotated about its axis and containing distributed particles was formulated and solved. Related studies in several areas are addressed. A computer program based on the analysis was upgraded by correcting some minor errors, adding a sophisticated screen-and-printer graphics capability and other output options, and by improving the automation. The design, performance, and analysis of a series of experiments with monodisperse polystyrene latex microspheres in water were supported to test the theory and its limitations. The theory was amply confirmed at high rotation rates. However, at low rotation rates (1 rpm or less) the assumption of uniform solid-body rotation of the fluid became invalid, and there were increasingly strong secondary motions driven by variations in the mean fluid density due to variations in the particle concentration. In these tests the increase in the mean fluid density due to the particles was of order 0.015 percent. To a first approximation, these flows are driven by the buoyancy in a thin crescent-shaped depleted layer on the descending side of the rotating reactor. This buoyancy distribution is balanced by viscosity near the walls, and by the Coriolis force in the interior. A full analysis is beyond the scope of this study. Secondary flows are likely to be stronger for buoyant particles, which spiral in towards the neutral point near the rotation axis under the influence of their centrifugal buoyancy. This is because the depleted layer is

  13. Progress in geophysical aspects of the rotation of the earth

    NASA Technical Reports Server (NTRS)

    Lambeck, K.

    1978-01-01

    The geophysical causes and consequences of the Earth's rotation are reviewed. Specific topics covered include: (1) the motion of the rotation axis in space, precession and nutation; (2) the motion of the rotation axis relative to the Earth, polar motion; and (3) the rate of rotation about this axis, or changes in the length of day. Secular decrease in obliquity and evolution of the Earth-Moon system are also discussed.

  14. Electrical-Discharge Machining With Additional Axis

    NASA Technical Reports Server (NTRS)

    Malinzak, Roger M.; Booth, Gary N.

    1991-01-01

    Proposed electrical-discharge-machining (EDM) apparatus uses moveable vertical wire as electrode. Wire positionable horizontally along one axis as it slides vertically past workpiece. Workpiece indexed in rotation about horizontal axis. Because of symmetry of parts, process used to make two such parts at a time by defining boundary between them. Advantages: cost of material reduced, imparts less residual stress to workpiece, and less time spent machining each part when parts produced in such symmetrical pairs.

  15. Rotatable prism for pan and tilt

    NASA Technical Reports Server (NTRS)

    Ball, W. B.

    1980-01-01

    Compact, inexpensive, motor-driven prisms change field of view of TV camera. Camera and prism rotate about lens axis to produce pan effect. Rotating prism around axis parallel to lens produces tilt. Size of drive unit and required clearance are little more than size of camera.

  16. Flexible helical-axis stellarator

    DOEpatents

    Harris, Jeffrey H.; Hender, Timothy C.; Carreras, Benjamin A.; Cantrell, Jack L.; Morris, Robert N.

    1988-01-01

    An 1=1 helical winding which spirals about a conventional planar, circular central conductor of a helical-axis stellarator adds a significant degree of flexibility by making it possible to control the rotational transform profile and shear of the magnetic fields confining the plasma in a helical-axis stellarator. The toroidal central conductor links a plurality of toroidal field coils which are separately disposed to follow a helical path around the central conductor in phase with the helical path of the 1=1 winding. This coil configuration produces bean-shaped magnetic flux surfaces which rotate around the central circular conductor in the same manner as the toroidal field generating coils. The additional 1=1 winding provides flexible control of the magnetic field generated by the central conductor to prevent the formation of low-order resonances in the rotational transform profile which can produce break-up of the equilibrium magnetic surfaces. Further, this additional winding can deepen the magnetic well which together with the flexible control provides increased stability.

  17. Distribution of Io's volcanoes: Possible influence on spin axis

    NASA Astrophysics Data System (ADS)

    Stoddard, Paul R.; Jurdy, Donna M.

    2002-05-01

    We examine the potential effect of volcano distribution on the orientation of Io's spin axis. Volcanoes dominate Io's surface and the massive outpourings documented in short intervals could cause instability in Io's rotation and a corresponding reorientation of its spin axis. Currently, the volcanoes and mountains exhibit a complementary distribution, with the maximum principal axis for the set of 351 volcanoes close to the position of the rotation axis. In addition, a delicate balance results from the near equivalence of the magnitudes of the maximum and intermediate eigenvalues. Assuming an otherwise homogeneous body, a changing mass distribution on its surface could control the location of the spin axis. In our models, changing the location of as few as three volcanoes is sufficient to cause dramatic shifts of the principal axis positions, and hence the spin axis orientation. This result, although somewhat diminished, still prevails even when a strong influence of Io's tidal bulge is included in the model.

  18. Rotating Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Scase, M. M.; Baldwin, K. A.; Hill, R. J. A.

    2017-02-01

    The effect of rotation upon the classical Rayleigh-Taylor instability is investigated. We consider a two-layer system with an axis of rotation that is perpendicular to the interface between the layers. In general, we find that a wave mode's growth rate may be reduced by rotation. We further show that in some cases, unstable axisymmetric wave modes may be stabilized by rotating the system above a critical rotation rate associated with the mode's wavelength, the Atwood number, and the flow's aspect ratio.

  19. Rotational scanning atomic force microscopy.

    PubMed

    Ulčinas, A; Vaitekonis, Š

    2017-03-10

    A non-raster scanning technique for atomic force microscopy (AFM) imaging which combines rotational and translational motion is presented. The use of rotational motion for the fast scan axis allows us to significantly increase the scanning speed while imaging a large area (diameter > 30 μm). An image reconstruction algorithm and the factors influencing the resolution of the technique are discussed. The experimental results show the potential of the rotational scanning technique for high-throughput large area AFM investigation.

  20. Rotational scanning atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ulčinas, A.; Vaitekonis, Š.

    2017-03-01

    A non-raster scanning technique for atomic force microscopy (AFM) imaging which combines rotational and translational motion is presented. The use of rotational motion for the fast scan axis allows us to significantly increase the scanning speed while imaging a large area (diameter > 30 μm). An image reconstruction algorithm and the factors influencing the resolution of the technique are discussed. The experimental results show the potential of the rotational scanning technique for high-throughput large area AFM investigation.

  1. Angle interferometer cross axis errors

    SciTech Connect

    Bryan, J.B.; Carter, D.L.; Thompson, S.L.

    1994-01-01

    Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them by remachining the reference surfaces.

  2. Angle interferometer cross axis errors

    NASA Astrophysics Data System (ADS)

    Bryan, J. B.; Carter, D. L.; Thompson, S. L.

    1994-01-01

    Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them.

  3. Modeling rigid magnetically rotated microswimmers: Rotation axes, bistability, and controllability

    NASA Astrophysics Data System (ADS)

    Meshkati, Farshad; Fu, Henry Chien

    2014-12-01

    Magnetically actuated microswimmers have recently attracted attention due to many possible biomedical applications. In this study we investigate the dynamics of rigid magnetically rotated microswimmers with permanent magnetic dipoles. Our approach uses a boundary element method to calculate a mobility matrix, accurate for arbitrary geometries, which is then used to identify the steady periodically rotating orbits in a co-rotating body-fixed frame. We evaluate the stability of each of these orbits. We map the magnetoviscous behavior as a function of dimensionless Mason number and as a function of the angle that the magnetic field makes with its rotation axis. We describe the wobbling motion of these swimmers by investigating how the rotation axis changes as a function of experimental parameters. We show that for a given magnetic field strength and rotation frequency, swimmers can have more than one stable periodic orbit with different rotation axes. Finally, we demonstrate that one can improve the controllability of these types of microswimmers by adjusting the relative angle between the magnetic field and its axis of rotation.

  4. Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

    2003-01-01

    The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head

  5. Research of misalignment between dithered ring laser gyro angle rate input axis and dither axis

    NASA Astrophysics Data System (ADS)

    Li, Geng; Wu, Wenqi; FAN, Zhenfang; LU, Guangfeng; Hu, Shaomin; Luo, Hui; Long, Xingwu

    2014-12-01

    The strap-down inertial navigation system (SINS), especially the SINS composed by dithered ring laser gyroscope (DRLG) is a kind of equipment, which providing high reliability and performance for moving vehicles. However, the mechanical dither which is used to eliminate the "Lock-In" effect can cause vibration disturbance to the INS and lead to dithering coupling problem in the inertial measurement unit (IMU) gyroscope triad, so its further application is limited. Among DRLG errors between the true gyro rotation rate and the measured rotation rate, the frequently considered one is the input axis misalignment between input reference axis which is perpendicular to the mounting surface and gyro angular rate input axis. But the misalignment angle between DRLG dither axis and gyro angular rate input axis is often ignored by researchers, which is amplified by dither coupling problem and that would lead to negative effects especially in high accuracy SINS. In order to study the problem more clearly, the concept of misalignment between DRLG dither axis and gyro angle rate input axis is researched. Considering the error of misalignment is of the order of 10-3 rad. or even smaller, the best way to measure it is using DRLG itself by means of an angle exciter as an auxiliary. In this paper, the concept of dither axis misalignment is explained explicitly firstly, based on this, the frequency of angle exciter is induced as reference parameter, when DRLG is mounted on the angle exciter in a certain angle, the projections of angle exciter rotation rate and mechanical oscillation rate on the gyro input axis are both sensed by DRLG. If the dither axis has misalignment error with the gyro input axis, there will be four major frequencies detected: the frequency of angle exciter, the dither mechanical frequency, sum and difference frequencies of the former two frequencies. Then the amplitude spectrum of DRLG output signal obtained by the using LabVIEW program. if there are only angle

  6. Systematic Disturbance Of Optimal Rotational Trajectory

    NASA Technical Reports Server (NTRS)

    Grunwald, Arthur J.; Kaiser, Mary K.

    1992-01-01

    Algorithm introduces systematic disturbance into otherwise optimal rotation of body from prescribed initial to prescribed final orientation. Disturbance introduced as deviation of actual axis of rotation from optimal one, like wobble of top. Algorithm effects rotational transformations and solves differential equations necessary to compute disturbed trajectory. Devised for use with motion-control program and three-dimensional computer-graphical display to study ability of observers to distinguish between optimal and suboptimal rotational trajectories.

  7. Vertical Axis Wind Turbine

    SciTech Connect

    Homicz, Greg

    2002-04-01

    Blade fatigue life is an important element in determining the economic viability of the Vertical-Axis Wind Turbine (VAWT). VAWT-SAL Vertical Axis Wind Turbine- Stochastic Aerodynamic Loads Ver 3.2 numerically simulates the stochastic (random0 aerodynamic loads of the Vertical-Axis Wind Turbine (VAWT) created by the atomspheric turbulence. The program takes into account the rotor geometry, operating conditions, and assumed turbulence properties.

  8. DEVICE FOR CONVEYING AND ROTATING OBJECTS

    DOEpatents

    Frantz, C.E.; Roslund, J.

    1958-01-21

    A device is described for conveying cylindrical material with a combined rotary and axial motion. The material rides on a series of balls which are retained in a guide plate and rotated by bearing against a rotating drum. The drum has a series of conical sections or grooves cut in its outer surface on which the balls ride. The grooves and balls match in such a way that all the balls are caused to rotate about an axis at an angle to the drum axis. This skewed rotation of the ball imparts a longitudinal as well as a rotary motion to the cylinders being conveyed.

  9. Rotating Apparatus for Isoelectric Focusing

    NASA Technical Reports Server (NTRS)

    Bier, M.

    1986-01-01

    Remixing of separated fractions prevented. Improved isoelectric focusing apparatus helps to prevent electro-osmosis and convection, both of which cause remixing of separated fractions. Fractionating column segmented and rotated about horizontal axis: Only combined effects of both features fully effective in making good separations. Improved apparatus slowly rotated continuously or rocked (at rotational amplitude of at least 180 degrees) about its horizontal axis so average gravitational vector experienced by fluid is zero and convection is therefore suppressed. Electro-osmosis suppressed and convection further suppressed by separating column into disklike compartments along its length with filters. Experiments have shown dimensions of apparatus not critical. Typical compartment and column volumes are 2 and 40 ml, respectively. Rotation speeds lie between 3 and 30 rpm.

  10. Rotatable non-circular forebody flow controller

    NASA Technical Reports Server (NTRS)

    Moskovitz, Cary A. (Inventor)

    1991-01-01

    The invention is a rotatable, non-circular forebody flow controller. The apparatus comprises a small geometric device located at a nose of a forebody of an aircraft and a non-circular cross-sectional area that extends toward the apex of the aircraft. The device is symmetrical about a reference plane and preferably attaches to an axle which in turn attaches to a rotating motor. The motor rotates the device about an axis of rotation. Preferably, a control unit connected to an aircraft flight control computer signals to the rotating motor the proper rotational positioning of the geometric device.

  11. Method for spinning up a three-axis controlled spacecraft

    NASA Technical Reports Server (NTRS)

    Vorlicek, Preston L. (Inventor)

    1988-01-01

    A three-axis controlled spacecraft (1), typically a satellite, is spun up about its roll axis (20) prior to firing a motor (2), i.e., a perigee kick motor, to achieve the requisite degree of angular momentum stiffness. Thrusters (21) for imparting rotation about the roll axis (20) are activated in open-loop fashion, typically at less than full duty cycle. Cross-axis torques induced by this rotational motion are compensated for by means of closed control loops for each of the pitch and yaw axes (30, 40, respectively). Each closed control loop combines a prebias torque (72) with torques (75, 74) representative of position and rate feedback information, respectively. A deadband (52) within each closed control loop can be widened during the spinup, to conserve fuel. Position feedback information (75) in each of the control loops is disabled upon saturation of the gyroscope associated with the roll axis (20).

  12. Rotating Vesta

    NASA Video Gallery

    Astronomers combined 146 exposures taken by NASA's Hubble SpaceTelescope to make this 73-frame movie of the asteroid Vesta's rotation.Vesta completes a rotation every 5.34 hours.› Asteroid and...

  13. Deferred action battery activated by rotation

    SciTech Connect

    Hruden, W.R.

    1988-02-16

    A deferred action battery is described comprising: a rotor having a longitudinal axis therethrough and having an outer circumference that is capable of being gripped by hand, and a stator adjacent the rotor and being rotatably mounted with respect to the rotor about the longitudinal axis.

  14. Stability of vertical and horizontal axis Levitrons

    NASA Astrophysics Data System (ADS)

    Michaelis, M. M.; Taylor, D. B.

    2015-11-01

    The stability of the new horizontal axis Levitron3 is compared with that of the vertical axis device. The rotation frequency ranges are similar because they are determined by the same precessional micro-trap, for which some theory is given. But the macro-trap of the horizontal axis system gives it far greater mechanical stability. Field-line studies allow this to be more easily visualized. The greater stability allows for educational experiments which could only be contemplated with the old Levitron: driven precession and nutation and motion along the field lines. These experiments illustrate some very fundamental space dynamics and several other topics. The enhanced stability may also lead to electro-mechanical applications.

  15. Determining the Stellar Spin Axis Orientation

    NASA Astrophysics Data System (ADS)

    Lesage, Anna-Lea; Wiedemann, Gunter

    2015-01-01

    We present an observing method that permits the determination of the absolute stellar spin axis position angle based on spectro-astrometric observations for slowly-rotating late-type stars. This method is complementary to current interferometric observations that determine the orientation of stellar spin axis for early-type fast-rotating stars. Spectro-astrometry enables us to study phenomena below the diffraction limit, at the milli-arcsecond scale. It relies on the wavelength dependent variations of the centroid position of a structured source in a long-slit spectrum. A rotating star has a slight tilt in its spectral lines, which induces a displacement of the photocentre's position. By monitoring the amplitude of the displacement for varying slit orientations, we can infer the absolute position angle of the stellar spin axis. Finally, we present first observational results on Aldebaran obtained with the Thüringer Landesternwarte high resolution spectrograph. We were able to retrieve Aldebaran's position angle with less than 10° errors.

  16. Single-Axis Accelerometer

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis Stephen (Inventor); Capo-Lugo, Pedro A. (Inventor)

    2016-01-01

    A single-axis accelerometer includes a housing defining a sleeve. An object/mass is disposed in the sleeve for sliding movement therein in a direction aligned with the sleeve's longitudinal axis. A first piezoelectric strip, attached to a first side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The first piezoelectric strip includes a first strip of a piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A second piezoelectric strip, attached to a second side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The second piezoelectric strip includes a second strip of the piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A voltage sensor is electrically coupled to at least one of the first and second piezoelectric strips.

  17. Finding the Orientation of the Stellar Spin Axis

    NASA Astrophysics Data System (ADS)

    Wilkinson, Tessa D.; Lesage, Anna-Lea

    2016-01-01

    The stellar position angle is defined as the projection of the stellar spin axis on the night sky, as measured from North to East. Measuring the stellar position angle gives information that can be used for stellar spin axis evolution and binary formation theories. Current methods to find this angle use imaging with long baseline interferometry for fast rotating stars. There is a lack of observational techniques to find the orientation of the stellar rotation axis for slow rotating stars, which make up the vast majority of stellar population. We developed a new method for determining the absolute stellar position angle for slow rotating stars using a spectro-astrometric analysis of high resolution long-slit spectra. We used the 2m Thueringer Landessternwarte (TLS) telescope to obtain high resolution spectra (R=60,000) with multiple slit orientations to test this method. The stellar rotation causes a tilt in the stellar lines, and the angle of this tilt depends on the stellar position angle and the orientation of the slit. We used a cross-correlation method to compare the subpixel displacements of the position of the photocenter at each slit orientation with telluric lines to obtain the tilt amplitude. We report the results of finding the position angle of the slow rotating K giant Aldebaran and fast rotating reference stars like Vega.

  18. ROTATING PLASMA DEVICE

    DOEpatents

    Boyer, K.; Hammel, J.E.; Longmire, C.L.; Nagle, D.E.; Ribe, F.L.; Tuck, J.L.

    1961-10-24

    ABS>A method and device are described for obtaining fusion reactions. The basic concept is that of using crossed electric and magnetic fields to induce a plasma rotation in which the ionized particles follow a circumferential drift orbit on wldch a cyclotron mode of motion is superimposed, the net result being a cycloidal motion about the axis of symmetry. The discharge tube has a radial electric field and a longitudinal magnetic field. Mirror machine geometry is utilized. The device avoids reliance on the pinch effect and its associated instability problems. (AEC)

  19. Three-axis force actuator for a magnetic bearing

    NASA Technical Reports Server (NTRS)

    Gondhalekar, Vijay (Inventor)

    1998-01-01

    This invention features a three-axis force actuator that axially, radially and rotatably supports a bearing member for frictionless rotation about an axis of rotation generally coincident with a Z-axis. Also featured is a magnetic bearing having such an actuator. The actuator includes an inner member, a magnetic member and a pole assembly having a ring member and four pole extending therefrom. The poles are equi-angular spaced from each other and radially spaced about the Z-axis. The inner member extends along the Z-axis and is a highly magnetic permeable material. The magnetic member is formed about the inner member outer surface, extends along the Z-axis and is configured so one magnetic pole polarity is located at its outer surface and the other polarity pole is located at its inner surface. Preferably, the magnetic member is a radially magnetized permanent magnet. The inner surface of the ring member is magnetically coupled to the magnetic member and a face of each pole is coupled to the bearing member. The magnetic member, the pole assembly, the inner member and the bearing member cooperate to generate a magnetic field that radially and rotatably supports a rotating member secured to the bearing member. The actuator further includes a plurality of electromagnetic coils. Preferably, a coil is formed about each pole and at least 2 coils are formed about the inner member. When energized, the electromagnetic coils generate a modulated magnetic field that stabilizes the rotating member in the desired operational position.

  20. Development of methodology for horizontal axis wind turbine dynamic analysis

    NASA Technical Reports Server (NTRS)

    Dugundji, J.

    1982-01-01

    Horizontal axis wind turbine dynamics were studied. The following findings are summarized: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotor; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastics; and (7) development of simple models for stability and response of wind turbines on flexible towers.

  1. Rotating Wavepackets

    ERIC Educational Resources Information Center

    Lekner, John

    2008-01-01

    Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

  2. Decrease of the Atmospheric Co-Rotation with Height

    ERIC Educational Resources Information Center

    Membrado, M.; Pacheco, A. F.

    2010-01-01

    Considering our atmosphere as a steady viscous gaseous envelope that co-rotates with the Earth, we obtain a solution for the form in which this induced rotational effect decreases as a function of the distances to the centre of the Earth and to the rotation axis. (Contains 1 figure.)

  3. A slowly rotating impeller in a rapidly rotating fluid

    NASA Astrophysics Data System (ADS)

    Machicoane, Nathanael; Moisy, Frederic; Cortet, Pierre-Philippe; Instability, waves; turbulence Team

    2016-11-01

    We characterize the two-dimensionalization process in the turbulent flow produced by an impeller rotating at a rate ω in a fluid rotating at a rate Ω around the same axis for Rossby number Ro = ω / Ω down to 0.01. The flow can be described as the superposition of a large-scale vertically invariant global rotation and small-scale shear layers detached from the impeller blades. As Ro decreases, the large-scale flow is subjected to azimuthal modulations. In this regime, the shear layers can be described in terms of wakes of inertial waves traveling with the blades, originating from the velocity difference between the non-axisymmetric large-scale flow and the blade rotation. The wakes are well defined and stable at low Rossby number, but they become disordered and interact nonlinearly at Ro of order of 1.

  4. On LAM's and SAM's for Halley's rotation

    NASA Technical Reports Server (NTRS)

    Peale, Stanton J.

    1992-01-01

    Non principal axis rotation for comet Halley is inferred from dual periodicities evident in the observations. The modes where the spin axis precesses around the axis of minimum moment of inertia (long axis mode or LAM) and where it precesses around the axis of maximum moment of inertia (short axis mode or SAM) are described from an inertial point of view. The currently favored LAM model for Halley's rotation state satisfies observational and dynamical constraints that apparently no SAM can satisfy. But it cannot reproduce the observed post perihelion brightening through seasonal illumination of localized sources on the nucleus, whereas a SAM can easily produce post or pre perihelion brightening by this mechanism. However, the likelihood of a LAM rotation for elongated nuclei of periodic comets such as Halley together with Halley's extreme post perihelion behavior far from the Sun suggest that Halley's post perihelion brightening may be due to effects other than seasonal illumination of localized sources, and therefore such brightening may not constrain its rotation state.

  5. Supergranulation rotation

    NASA Astrophysics Data System (ADS)

    Schou, Jesper; Beck, John G.

    2001-01-01

    Simple convection models estimate the depth of supergranulation at approximately 15,000 km which suggests that supergranules should rotate at the rate of the plasma in the outer 2% of the Sun by radius. Previous measurements (Snodgrass & Ulrich, 1990; Beck & Schou, 2000) found that supergranules rotate significantly faster than this, with a size-dependent rotation rate. We expand on previous work and show that the torsional oscillation signal seen in the supergranules tracks that obtained for normal modes. We also find that the amplitudes and lifetimes of the supergranulation are size dependent.

  6. Diamond Machining of an Off-Axis Biconic Aspherical Mirror

    NASA Technical Reports Server (NTRS)

    Ohl, Raymond G.; Preuss, Werner; Sohn, Alex; MacKenty, John

    2009-01-01

    Two diamond-machining methods have been developed as part of an effort to design and fabricate an off-axis, biconic ellipsoidal, concave aluminum mirror for an infrared spectrometer at the Kitt Peak National Observatory. Beyond this initial application, the methods can be expected to enable satisfaction of requirements for future instrument mirrors having increasingly complex (including asymmetrical), precise shapes that, heretofore, could not readily be fabricated by diamond machining or, in some cases, could not be fabricated at all. In the initial application, the mirror is prescribed, in terms of Cartesian coordinates x and y, by aperture dimensions of 94 by 76 mm, placements of -2 mm off axis in x and 227 mm off axis in y, an x radius of curvature of 377 mm, a y radius of curvature of 407 mm, an x conic constant of 0.078, and a y conic constant of 0.127. The aspect ratio of the mirror blank is about 6. One common, "diamond machining" process uses single-point diamond turning (SPDT). However, it is impossible to generate the required off-axis, biconic ellipsoidal shape by conventional SPDT because (1) rotational symmetry is an essential element of conventional SPDT and (2) the present off-axis biconic mirror shape lacks rotational symmetry. Following conventional practice, it would be necessary to make this mirror from a glass blank by computer-controlled polishing, which costs more than diamond machining and yields a mirror that is more difficult to mount to a metal bench. One of the two present diamond machining methods involves the use of an SPDT machine equipped with a fast tool servo (FTS). The SPDT machine is programmed to follow the rotationally symmetric asphere that best fits the desired off-axis, biconic ellipsoidal surface. The FTS is actuated in synchronism with the rotation of the SPDT machine to generate the difference between the desired surface and the best-fit rotationally symmetric asphere. In order to minimize the required stroke of the FTS

  7. Two-axis joint assembly and method

    NASA Technical Reports Server (NTRS)

    Le, Thang D. (Inventor); Lewis, James L. (Inventor); Carroll, Monty B. (Inventor)

    2010-01-01

    In an embodiment, a two-axis joint that utilizes planar reactions to handle moments applied to the side of the joint thereby allowing the device to remain low profile and compact with minimal intrusion to the mounting surface of the two-axis joint. To handle larger moments, the diameter of the planar member can be increased without increasing the overall height of the joint assembly thereby retaining the low profile thereof. Upper and lower antifriction bearings may be positioned within a housing engage the planar member to reduce rotational friction. The upper and lower bearings and a hub which supports the planar member transfer forces produced by moments applied to the side of the joint so as to spread the forces over the area of the housing.

  8. Multiple axis reticle

    NASA Technical Reports Server (NTRS)

    Barns, Chris E. (Inventor); Gunter, William D. (Inventor)

    1990-01-01

    A reticle permits the alignment of three orthogonal axes (X, Y and Z) that intersect at a common target point. Thin, straight filaments are supported on a frame. The filaments are each contained in a different orthogonal plane (S sub xy, S sub xz, and S sub yz) and each filament intersects two of the three orthogonal axes. The filaments, as viewed along the frame axis, give the appearance of a triangle with a V extending from each triangle vertex. When axial alignment is achieved, the filament portions adjacent to a triangle vertex are seen (along the axis of interest) as a right-angle cross, whereas these filament portions are seen to intersect at an oblique angle when axial misalignment occurs. The reticle is open in the region near the target point leaving ample space for alignment aids such as a pentaprism or a cube mirror.

  9. Rotational Energy.

    ERIC Educational Resources Information Center

    Lockett, Keith

    1988-01-01

    Demonstrates several objects rolling down a slope to explain the energy transition among potential energy, translational kinetic energy, and rotational kinetic energy. Contains a problem from Galileo's rolling ball experiment. (YP)

  10. Solar rotation.

    NASA Astrophysics Data System (ADS)

    Dziembowski, W.

    Sunspot observations made by Johannes Hevelius in 1642 - 1644 are the first ones providing significant information about the solar differential rotation. In modern astronomy the determination of the rotation rate is done in a routine way by measuring positions of various structures on the solar surface as well as by studying the Doppler shifts of spectral lines. In recent years a progress in helioseismology enabled determination of the rotation rate in the layers inaccessible for direct observations. There are still uncertainties concerning, especially, the temporal variations of the rotation rate and its behaviour in the radiative interior. We are far from understanding the observations. Theoretical works have not yet resulted in a satisfactory model for the angular momentum transport in the convective zone.

  11. Rotational Spectrum of 1,1-Difluoroethane: Internal Rotation Analysis and Structure

    NASA Astrophysics Data System (ADS)

    Villamanan, R. M.; Chen, W. D.; Wlodarczak, G.; Demaison, J.; Lesarri, A. G.; Lopez, J. C.; Alonso, J. L.

    1995-05-01

    The rotational spectrum of CH3CHF2 in its ground state was measured up to 653 GHz. Accurate rotational and centrifugal distortion constants were determined. The internal rotation splittings were analyzed using the internal axis method. An ab initio structure has been calculated and a near-equilibrium structure has been estimated using offsets derived empirically. This structure was compared to an experimental r0 structure. The four lowest excited states (including the methyl torsion) have also been assigned.

  12. Deep cytoplasmic rearrangements in axis-respecified Xenopus embryos

    NASA Technical Reports Server (NTRS)

    Denegre, J. M.; Danilchik, M. V.

    1993-01-01

    In fertilized eggs of the frog Xenopus, the vegetal yolk mass rotates away from the future dorsal side (J. P. Vincent and J. Gerhart, 1987, Dev. Biol. 123, 526-539), and a major rearrangement of the deep animal hemisphere cytoplasm produces a characteristic swirl in the prospective dorsal side (M. V. Danilchik and J. M. Denegre, 1991, Development 111, 845-856). The relationship between this swirl and determination of the dorsal-ventral axis was further investigated by attempting to experimentally separate the positions of the swirl and the dorsal-ventral axis. Eggs were obliquely oriented in the gravity field to respecify the direction of yolk mass rotation and the position of the dorsal-ventral axis. When yolk mass rotation occurred in the absence of a sperm, as in activated eggs, a swirl pattern formed on the side away from which the yolk mass had rotated. In fertilized eggs tipped with the sperm entry point (SEP) down or to the side, swirl patterns were always found to form on the side away from which the yolk mass was displaced. However, in eggs tipped SEP up, in which the yolk mass was forced to rotate away from the SEP, more complicated rearrangements were observed in addition to the rotation-oriented swirl. Because the direction of yolk mass rotation was found to be influenced by both gravity and the actual position of the SEP in obliquely oriented eggs (SEP to the side), such complicated rearrangement patterns may result from opposing forces generated by both yolk mass rotation and the expanding sperm aster. Thus, except in cases in which the influences of SEP position and unit gravity opposed each other, it was not possible to experimentally separate the position of the deep cytoplasmic swirl from the direction of yolk mass rotation, and therefore the position of the prospective dorsal side.

  13. Control system for a vertical axis windmill

    DOEpatents

    Brulle, Robert V.

    1983-10-18

    A vertical axis windmill having a rotating structure is provided with a series of articulated vertical blades whose positions are controlled to maintain a constant RPM for the rotating structure, when wind speed is sufficient. A microprocessor controller is used to process information on wind speed, wind direction and RPM of the rotating structure to develop an electrical signal for establishing blade position. The preferred embodiment of the invention, when connected to a utility grid, is designed to generate 40 kilowatts of power when exposed to a 20 mile per hour wind. The control system for the windmill includes electrical blade actuators that modulate the blades of the rotating structure. Blade modulation controls the blade angle of attack, which in turn controls the RPM of the rotor. In the preferred embodiment, the microprocessor controller provides the operation logic and control functions. A wind speed sensor provides inputs to start or stop the windmill, and a wind direction sensor is used to keep the blade flip region at 90.degree. and 270.degree. to the wind. The control system is designed to maintain constant rotor RPM when wind speed is between 10 and 40 miles per hour.

  14. Vertical axis wind turbines

    DOEpatents

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  15. Single Axis Piezoceramic Gimbal

    NASA Technical Reports Server (NTRS)

    Horner, Garnett C.; Taleghani, Barmac K.

    1999-01-01

    This paper describes the fabrication, testing, and analysis of a single axis piezoceramic gimbal. The fabrication process consist of pre-stressing a piezoceramic wafer using a high-temperature thermoplastic polyimide and a metal foil. The differential thermal expansion between the ceramic and metal induces a curvature. The pre-stressed, curved piezoceramic is mounted on a support mechanism and a mirror is attached to the piezoceramic. A plot of gimbal angle versus applied voltage to the piezoceramic is presented. A finite element analysis of the piezoceramic gimbal is described. The predicted gimbal angle versus applied voltage is compared to experimental results.

  16. NEA rotations and binaries

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Harris, A. W.; Warner, B. D.

    2007-05-01

    Of nearly 3900 near-Earth asteroids known in June 2006, 325 have got estimated rotation periods. NEAs with sizes down to 10 meters have been sampled. Observed spin distribution shows a major changing point around D=200 m. Larger NEAs show a barrier against spin rates >11 d-1 (period P~2.2 h) that shifts to slower rates with increasing equatorial elongation. The spin barrier is interpreted as a critical spin rate for bodies held together by self-gravitation only, suggesting that NEAs larger than 200 m are mostly strenghtless bodies (i.e., with zero tensile strength), so called `rubble piles'. The barrier disappears at D<200 m where most objects rotate too fast to be held together by self-gravitation only, so a non-zero cohesion is implied in the smaller NEAs. The distribution of NEA spin rates in the `rubble pile' range (D>0.2 km) is non-Maxwellian, suggesting that other mechanisms than just collisions worked there. There is a pile up in front of the barrier (P of 2-3 h). It may be related to a spin up mechanism crowding asteroids to the barrier. An excess of slow rotators is seen at P>30 h. The spin-down mechanism has no clear lower limit on spin rate; periods as long as tens of days occur. Most NEAs appear to be in basic spin states with rotation around the principal axis. Excited rotations are present among and actually dominate in slow rotators with damping timescales >4.5 byr. A few tumblers observed among fast rotating coherent objects consistently appear to be more rigid or younger than the larger, rubble-pile tumblers. An abundant population of binary systems among NEAs has been found. The fraction of binaries among NEAs larger than 0.3 km has been estimated to be 15 +/-4%. Primaries of the binary systems concentrate at fast spin rates (periods 2-3 h) and low amplitudes, i.e., they lie just below the spin barrier. The total angular momentum content in the binary systems suggests that they formed at the critical spin rate, and that little or no angular

  17. An algorithm for the systematic disturbance of optimal rotational solutions

    NASA Technical Reports Server (NTRS)

    Grunwald, Arthur J.; Kaiser, Mary K.

    1989-01-01

    An algorithm for introducing a systematic rotational disturbance into an optimal (i.e., single axis) rotational trajectory is described. This disturbance introduces a motion vector orthogonal to the quaternion-defined optimal rotation axis. By altering the magnitude of this vector, the degree of non-optimality can be controlled. The metric properties of the distortion parameter are described, with analogies to two-dimensional translational motion. This algorithm was implemented in a motion-control program on a three-dimensional graphic workstation. It supports a series of human performance studies on the detectability of rotational trajectory optimality by naive observers.

  18. Fibromyxoma of the axis.

    PubMed

    Mavrogenis, Andreas F; Casadei, Roberto; Gambarotti, Marco; Ruggieri, Pietro

    2012-07-01

    Fibromyxoma of bone is a rare benign tumor of fibrous tissue origin. The typical location is the jaws. Sporadic extragnathic cases have been reported, but fibromyxoma of the spine has not been reported. The histological appearance of fibromyxoma is benign and includes abundant extracellular fibrous and myxoid stroma with varying amounts of calcification and ossification. Myxoid changes are usually extensive. Extragnathic fibromyxoma of bone should be distinguished from benign cartilage-forming bone tumors, such as chondromyxoid and myxoid chondrosarcoma and myxoma of bone. It has also been suggested that fibromyxoma is a variant of myxoid fibrous dysplasia, whereas other authors reported extragnathic fibromyxoma resulting from myxoid degeneration of bone tumors, such as chondrosarcoma or fibrosarcoma. The overtreatment of patients with fibromyxoma of bone due to an aggressive imaging appearance should be avoided; the prognosis is excellent compared with the jaw variant and depends on the location and extent of the tumor. This article describes a case of a 21-year-old woman with fibromyxoma of bone originating from the spinous process of the axis. Clinical examination showed a tender mass in the midline of the posterior aspect the neck and slight limitation of neck range of motion; neurologic examination was normal. Diagnosis was obtained with a preoperative biopsy. Marginal excision of the lesion with posterior laminectomy of the axis was performed. The facets were preserved, and no fusion was performed. At last follow-up 2 years after diagnosis and treatment, the patient was asymptomatic with no evidence of local recurrence.

  19. Laser interferometric system for six-axis motion measurement

    SciTech Connect

    Zhang Zhipeng; Menq, C.-H.

    2007-08-15

    This article presents the development of a precision laser interferometric system, which is designed to achieve six-axis motion measurement for real-time applications. By combining the advantage of the interferometer with a retroreflector and that of the interferometer with a plane mirror reflector, the system is capable of simultaneously measuring large transverse motions along and large rotational motions about three orthogonal axes. Based on optical path analysis along with the designed kinematics of the system, a closed form relationship between the six-axis motion parameters of the object being measured and the readings of the six laser interferometers is established. It can be employed as a real-time motion sensor for various six-axis motion control stages. A prototype is implemented and integrated with a six-axis magnetic levitation stage to illustrate its resolution and measurement range.

  20. Forced vibration analysis of rotating cyclic structures in NASTRAN

    NASA Technical Reports Server (NTRS)

    Elchuri, V.; Gallo, A. M.; Skalski, S. C.

    1981-01-01

    A new capability was added to the general purpose finite element program NASTRAN Level 17.7 to conduct forced vibration analysis of tuned cyclic structures rotating about their axis of symmetry. The effects of Coriolis and centripetal accelerations together with those due to linear acceleration of the axis of rotation were included. The theoretical, user's, programmer's and demonstration manuals for this new capability are presented.

  1. Rotating Gravity Gradiometer Study

    NASA Technical Reports Server (NTRS)

    Forward, R. L.

    1976-01-01

    The application of a Rotating Gravity Gradiometer (RGG) system on board a Lunar Polar Orbiter (LPO) for the measurement of the Lunar gravity field was investigated. A data collection simulation study shows that a gradiometer will give significantly better gravity data than a doppler tracking system for the altitudes under consideration for the LOP, that the present demonstrated sensitivity of the RGG is adequate for measurement of the Lunar gravity gradient field, and that a single RGG instrument will provide almost as much data for geophysical interpretation as an orthogonal three axis RGG system. An engineering study of the RGG sensor/LPO spacecraft interface characteristics shows that the RGG systems under consideration are compatible with the present models of the LPO spacecraft.

  2. Rotatable crucible for rapid solidification process

    NASA Technical Reports Server (NTRS)

    Gaspar, Thomas (Inventor)

    1990-01-01

    This invention relates to an apparatus for producing filament, fiber, ribbon or film from a molten material, comprising a preferably heat extracting crucible which contains a pool of molten material at a selected horizontal level in the pool. The crucible has an opening extending from above the free surface level to a bottom edge of the opening, the bottom edge being sufficiently below the free surface level so that the molten material cannot form and hold a meniscus by surface tension between the edge and the level of the free surface and further comprises a heat extracting substrate laterally disposed with respect to the crucible and which rotates about an axis of rotation. The substrate is positioned adjacent the edge of the opening which confines the molten material and prevents it from overflowing downwardly out of the crucible. The invention features rotating means which includes a first drive means for tiltably rotating the crucible about an axis of rotation which is coaxial with the axis of rotation of the substrate, so the crucible edge can be maintained a predetermined constant distance from the substrate. The distance chosen is suitable for depositing molten material on the substrate and the apparatus also has a second drive means which is drivingly connected to the substrate for continuously moving the surface of the substrate upwardly past the edge and a melt front formed at the interface of the molten material and the substrate surface.

  3. Dynamic modulation of ocular orientation during visually guided saccades and smooth-pursuit eye movements

    NASA Technical Reports Server (NTRS)

    Hess, Bernhard J M.; Angelaki, Dora E.

    2003-01-01

    Rotational disturbances of the head about an off-vertical yaw axis induce a complex vestibuloocular reflex pattern that reflects the brain's estimate of head angular velocity as well as its estimate of instantaneous head orientation (at a reduced scale) in space coordinates. We show that semicircular canal and otolith inputs modulate torsional and, to a certain extent, also vertical ocular orientation of visually guided saccades and smooth-pursuit eye movements in a similar manner as during off-vertical axis rotations in complete darkness. It is suggested that this graviceptive control of eye orientation facilitates rapid visual spatial orientation during motion.

  4. Rotating drum filter

    DOEpatents

    Anson, Donald

    1990-01-01

    A perforated drum (10) rotates in a coaxial cylindrical housing (18) having three circumferential ports (19,22,23), and an axial outlet (24) at one end. The axis (11) is horizontal. A fibrous filter medium (20) is fed through a port (19) on or near the top of the housing (81) by a distributing mechanism (36) which lays a uniform mat (26) of the desired thickness onto the rotating drum (10). This mat (26) is carried by the drum (10) to a second port (23) through which dirty fluid (13) enters. The fluid (13) passes through the filter (26) and the cleaned stream (16) exits through the open end (15) of the drum (10) and the axial port (24) in the housing (18). The dirty filter material (20) is carried on to a third port (22) near the bottom of the housing (18) and drops into a receiver (31) from which it is continuously removed, cleaned (30), and returned (32) to the charging port (36) at the top. To support the filter mat, the perforated cylinder may carry a series of tines (40), shaped blades (41), or pockets, so that the mat (26) will not fall from the drum (10) prematurely. To minimize risk of mat failure, the fluid inlet port (23) may be located above the horizontal centerline (11).

  5. Rotation and particle loss in Tore Supra

    SciTech Connect

    R. B. White; F. W. Perkins; X. Garbet; C. Bourdelle; V. Basiuk; L. G. Eriksson

    2000-06-13

    Although plasma heating with ICRF imparts negligible angular momentum to a tokamak plasma, the high energy particles give significant torque to the plasma through diamagnetic effects. This effect has been directly modeled through guiding center simulations. It is found that heating in Tore Supra, with the location of the resonance surface on the high field side of the magnetic axis, can produce negative central rotation of up to 40 km/sec. Particle loss also contributes to negative rotation, but this is not the dominant effect in most discharges. In this work the authors examine the effect of collisions and strong plasma rotation on the loss of high energy particles.

  6. Unusual rotation modes of minor planetary satellites

    NASA Astrophysics Data System (ADS)

    Mel'Nikov, A. V.; Shevchenko, I. I.

    2007-12-01

    An analysis of the character of the possible dynamics of all hitherto known planetary satellites shows two satellites—Amalthea (J5) and Prometheus (S16)—to have the most unusual structure of the phase space of possible rotational motion. These are the only satellites whose phase space of planar rotation may host synchronous resonances of three different kinds: the α resonance, the β resonance, and a mode corresponding to the period doubling bifurcation of the α resonance. We analyze the stability of these states against the tilt of the rotational axis.

  7. Miniature rotating transmissive optical drum scanner

    NASA Technical Reports Server (NTRS)

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  8. Automated shell theory for rotating structures (ASTROS)

    NASA Technical Reports Server (NTRS)

    Foster, B. J.; Thomas, J. M.

    1971-01-01

    A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.

  9. Static Atmospheres in a Rotating Space Habitat.

    ERIC Educational Resources Information Center

    McKinley, John M.

    1980-01-01

    Discusses O'Neill's proposal for the colonization of space as it offers new problems in pure physics. Addresses specifically the distribution of the atmosphere in O'Neill's habitat and whether there will be enough air at the axis of rotation to allow human-powered flight, with particular reference to the habitat's "artificial gravity."…

  10. Brake for counter rotating bladed members

    SciTech Connect

    Cedoz, R.W.

    1987-02-10

    This patent describes a propulsion system including a gas turbine engine having an output shaft and a gear drive having a planetary gear set with a first element connected to the engine output shaft and a second element connected to a first bladed member and a third element connected to a second bladed member whereby the first and second bladed members are rotated in opposite directions by the output shaft. A brake is described comprising, a first transfer shaft supported on a stationary housing for rotation about an axis of the latter, a second transfer shaft supported on the stationary housing for rotation about the axis, gear means between one of the counter rotating bladed members and the first transfer shaft and gear means between the other of the counter rotating bladed members and the second transfer shaft. The brake also includes a selectively operable brake actuator on the housing movable between an extended position and a retracted position, and friction means between the brake actuator and each of first and second transfer shafts operative in the extended position of the brake actuator to simultaneously frictionally retard rotation of each of the first and the second transfer shafts whereby each of the counter rotating bladed members is simultaneously braked.

  11. Error motion compensating tracking interferometer for the position measurement of objects with rotational degree of freedom

    NASA Astrophysics Data System (ADS)

    Holler, Mirko; Raabe, Jörg

    2015-05-01

    The nonaxial interferometric position measurement of rotating objects can be performed by imaging the laser beam of the interferometer to a rotating mirror which can be a sphere or a cylinder. This, however, requires such rotating mirrors to be centered on the axis of rotation as a wobble would result in loss of the interference signal. We present a tracking-type interferometer that performs such measurement in a general case where the rotating mirror may wobble on the axis of rotation, or even where the axis of rotation may be translating in space. Aside from tracking, meaning to measure and follow the position of the rotating mirror, the interferometric measurement errors induced by the tracking motion of the interferometer itself are optically compensated, preserving nanometric measurement accuracy. As an example, we show the application of this interferometer in a scanning x-ray tomography instrument.

  12. Rotational study of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Lhotka, C.; Reimond, S.; Souchay, J.; Baur, O.

    2015-10-01

    The aim of the study is to determine the gravity field and moments of inertia along the principal axes of the comet, the obliquity of the axis of rotation with respect to the mean orbital plane, the precession rate, and the nutation coefficients. We also investigate the role of relevant parameters on the rotation.

  13. Rotation of solid bodies in the solar system

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    1973-01-01

    The effects of elastic distortion, nonprincipal axis rotation, precessing orbits, and internal dissipation on the rotation of a solid solar system body, which is in the gravitational field of an exterior body, are relatively easily analyzed by a Hamiltonian theory developed here. Examples of applications include the Chandler wobble, wobble of the moon, spin-orbit coupling, generalized Cassini laws, and tidal evolution.

  14. Magnetic and antimagnetic rotation in covariant density functional theory

    SciTech Connect

    Zhao, P. W.; Liang, H. Z.; Peng, J.; Ring, P.; Zhang, S. Q.; Meng, J.

    2012-10-20

    Progress on microscopic and self-consistent description of the magnetic rotation and antimagnetic rotation phenomena in tilted axis cranking relativistic mean-field theory based on a point-coupling interaction are briefly reviewed. In particular, the microscopic pictures of the shears mechanism in {sup 60}Ni and the two shears-like mechanism in {sup 105}Cd are discussed.

  15. Microgyroscope with Vibrating Post as Rotation Transducer

    NASA Technical Reports Server (NTRS)

    Tang, Tony K.; Gutierrez, Roman

    2003-01-01

    The figure depicts a micromachined silicon vibratory gyroscope that senses rotation about its z axis. The rotation-sensitive vibratory element is a post oriented (when at equilibrium) along the z axis and suspended at its base by thin, flexible silicon bands oriented along the x and y axes, respectively. Unlike in the vibratory microgyroscopes described in the immediately preceding article ["Cloverleaf Vibratory Microgyroscope With Integrated Post" (NPO-20688)] and other previous articles in NASA Tech Briefs, the rotation-sensitive vibratory element does not include a cloverleaf-shaped structure that lies (when at equilibrium) in the x-y plane. As in the cases of the previously reported vibratory microgyroscopes, vibrations of the rotation-sensitive vibratory element are excited electrostatically, the vibrations are measured by use of capacitive proximity sensors, and the rate of rotation along the axis of sensitivity is deduced from the effect of the Coriolis force upon the vibrations. To create electrodes for electrostatic excitation and capacitive sensing of vibrations, portions of the facing surfaces of the post and of the four stationary members that surround the post are rendered electrically conductive; this can be accomplished by either depositing metal films or else doping the silicon in the affected areas.

  16. Shadow of rotating wormhole in plasma environment

    NASA Astrophysics Data System (ADS)

    Abdujabbarov, Ahmadjon; Juraev, Bakhtinur; Ahmedov, Bobomurat; Stuchlík, Zdeněk

    2016-07-01

    The massless particle motion around rotating wormhole in the presence of plasma environment has been studied. It has been shown that the presence of the plasma decreases the inner radius of the circular orbits of photons around rotating wormhole. The shadow cast by rotating wormhole surrounded by inhomogeneous plasma with the radial power-law density has been explored. It has been shown that the shape and size of the wormhole shadow is distorted and changed depending on i) plasma parameters, ii) wormhole rotation and iii) inclination angle between observer plane and axis of rotation of wormhole. As an example we have considered an inverse radial distribution of the plasma density and different types of the wormhole solution.

  17. System for controlled acoustic rotation of objects

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B. (Inventor)

    1983-01-01

    A system is described for use with acoustically levitated objects, which enables close control of rotation of the object. One system includes transducers that propagate acoustic waves along the three dimensions (X, Y, Z) of a chamber of rectangular cross section. Each transducers generates one wave which is resonant to a corresponding chamber dimension to acoustically levitate an object, and additional higher frequency resonant wavelengths for controlling rotation of the object. The three chamber dimensions and the corresponding three levitation modes (resonant wavelengths) are all different, to avoid degeneracy, or interference, of waves with one another, that could have an effect on object rotation. Only the higher frequencies, with pairs of them having the same wavelength, are utilized to control rotation, so that rotation is controlled independently of levitation and about any arbitrarily chosen axis.

  18. Energy Transfer in Rotating Turbulence

    NASA Technical Reports Server (NTRS)

    Cambon, Claude; Mansour, Nagi N.; Godeferd, Fabien S.; Rai, Man Mohan (Technical Monitor)

    1995-01-01

    The influence or rotation on the spectral energy transfer of homogeneous turbulence is investigated in this paper. Given the fact that linear dynamics, e.g. the inertial waves regime tackled in an RDT (Rapid Distortion Theory) fashion, cannot Affect st homogeneous isotropic turbulent flow, the study of nonlinear dynamics is of prime importance in the case of rotating flows. Previous theoretical (including both weakly nonlinear and EDQNM theories), experimental and DNS (Direct Numerical Simulation) results are gathered here and compared in order to give a self-consistent picture of the nonlinear effects of rotation on tile turbulence. The inhibition of the energy cascade, which is linked to a reduction of the dissipation rate, is shown to be related to a damping due to rotation of the energy transfer. A model for this effect is quantified by a model equation for the derivative-skewness factor, which only involves a micro-Rossby number Ro(sup omega) = omega'/(2(OMEGA))-ratio of rms vorticity and background vorticity as the relevant rotation parameter, in accordance with DNS and EDQNM results fit addition, anisotropy is shown also to develop through nonlinear interactions modified by rotation, in an intermediate range of Rossby numbers (Ro(omega) = (omega)' and Ro(omega)w greater than 1), which is characterized by a marco-Rossby number Ro(sup L) less than 1 and Ro(omega) greater than 1 which is characterized by a macro-Rossby number based on an integral lengthscale L and the micro-Rossby number previously defined. This anisotropy is mainly an angular drain of spectral energy which tends to concentrate energy in tile wave-plane normal to the rotation axis, which is exactly both the slow and the two-dimensional manifold. In Addition, a polarization of the energy distribution in this slow 2D manifold enhances horizontal (normal to the rotation axis) velocity components, and underlies the anisotropic structure of the integral lengthscales. Finally is demonstrated the

  19. Properties of a strongly focused Gaussian beam with an off-axis vortex

    NASA Astrophysics Data System (ADS)

    Zhao, Xinying; Zhang, Jingcheng; Pang, Xiaoyan; Wan, Guobin

    2017-04-01

    The intensity distribution and the phase properties, especially the Gouy phase and the phase singularities are studied in a strongly focused Gaussian beam with an off-axis vortex. The symmetry relation of the focused field is also derived. It is found that the off-axis vortex induces a rotation of the field pattern, the transverse focal shift, and the asymmetric distribution of the phase singularities. Our results also show that the initial position of the off-axis vortex in the incident beam strongly influences the distance of the transverse focal shift, but does not have an effect on the Gouy phase along the central axis.

  20. Rotation-independent representations for haptic movements.

    PubMed

    Shioiri, Satoshi; Yamazaki, Takanori; Matsumiya, Kazumichi; Kuriki, Ichiro

    2013-01-01

    The existence of a common mechanism for visual and haptic representations has been reported in object perception. In contrast, representations of movements might be more specific to modalities. Referring to the vertical axis is natural for visual representations whereas a fixed reference axis might be inappropriate for haptic movements and thus also inappropriate for its representations in the brain. The present study found that visual and haptic movement representations are processed independently. A psychophysical experiment examining mental rotation revealed the well-known effect of rotation angle for visual representations whereas no such effect was found for haptic representations. We also found no interference between processes for visual and haptic movements in an experiment where different stimuli were presented simultaneously through visual and haptic modalities. These results strongly suggest that (1) there are separate representations of visual and haptic movements, and (2) the haptic process has a rotation-independent representation.

  1. Method for culturing mammalian cells in a horizontally rotated bioreactor

    NASA Technical Reports Server (NTRS)

    Schwarz, Ray P. (Inventor); Wolf, David A. (Inventor); Trinh, Tinh T. (Inventor)

    1992-01-01

    A bio-reactor system where cell growth microcarrier beads are suspended in a zero head space fluid medium by rotation about a horizontal axis and where the fluid is continuously oxygenated from a tubular membrane which rotates on a shaft together with rotation of the culture vessel. The oxygen is continuously throughput through the membrane and disbursed into the fluid medium along the length of the membrane.

  2. Rotating Bioreactor

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues currently being cultured in rotating bioreactors by investigators.

  3. Six-Axis Inertial Sensor Using Cold-Atom Interferometry

    SciTech Connect

    Canuel, B.; Leduc, F.; Holleville, D.; Gauguet, A.; Fils, J.; Virdis, A.; Clairon, A.; Dimarcq, N.; Borde, Ch.J.; Landragin, A.; Bouyer, P.

    2006-07-07

    We have developed an atom interferometer providing a full inertial base. This device uses two counterpropagating cold-atom clouds that are launched in strongly curved parabolic trajectories. Three single Raman beam pairs, pulsed in time, are successively applied in three orthogonal directions leading to the measurement of the three axis of rotation and acceleration. In this purpose, we introduce a new atom gyroscope using a butterfly geometry. We discuss the present sensitivity and the possible improvements.

  4. Wind tunnel investigation of a 14 foot vertical axis windmill

    NASA Technical Reports Server (NTRS)

    Muraca, R. J.; Guillotte, R. J.

    1976-01-01

    A full scale wind tunnel investigation was made to determine the performance characteristics of a 14 ft diameter vertical axis windmill. The parameters measured were wind velocity, shaft torque, shaft rotation rate, along with the drag and yawing moment. A velocity survey of the flow field downstream of the windmill was also made. The results of these tests along with some analytically predicted data are presented in the form of generalized data as a function of tip speed ratio.

  5. Estimation of power in low velocity vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Sampath, S. S.; Shetty, Sawan; Chithirai Pon Selvan, M.

    2015-06-01

    The present work involves in the construction of a vertical axis wind turbine and the determination of power. Various different types of turbine blades are considered and the optimum blade is selected. Mechanical components of the entire setup are built to obtain maximum rotation per minute. The mechanical energy is converted into the electrical energy by coupling coaxially between the shaft and the generator. This setup produces sufficient power for consumption of household purposes which is economic and easily available.

  6. Celestial rotation: its importance in the development of migratory orientation.

    PubMed

    Emlen, S T

    1970-12-11

    Three groups of indigo buntings were hand-raised in various conditions of visual isolation from celestial cues. When they had been prevented from viewing the night sky prior to the autumn migration season, birds tested under planetarium skies were unable to select the normal migration direction. By contrast, when they had been exposed as juveniles to a normal, rotating, planetarium sky, individuals displayed typical southerly directional preferences. The third group was exposed to an incorrect planetarium sky in which the stars rotated about a fictitious axis. When tested during the autumn, these birds took up the "correct" migration direction relative to the new axis of rotation. These results fail to support the hypothesis of a "genetic star map." They suggest, instead, a maturation process in which stellar cues come to be associated with a directional reference system provided by the axis of celestial rotation.

  7. Nuclear chiral and magnetic rotation in covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Zhao, Pengwei

    2016-05-01

    Excitations of chiral rotation observed in triaxial nuclei and magnetic and/or antimagnetic rotations (AMR) seen in near-spherical nuclei have attracted a lot of attention. Unlike conventional rotation in well-deformed or superdeformed nuclei, here the rotational axis is not necessary coinciding with any principal axis of the nuclear density distribution. Thus, tilted axis cranking (TAC) is mandatory to describe these excitations self-consistently in the framework of covariant density functional theory (CDFT). We will briefly introduce the formalism of TAC-CDFT and its application for magnetic and AMR phenomena. Configuration-fixed CDFT and its predictions for nuclear chiral configurations and for favorable triaxial deformation parameters are also presented, and the discoveries of the multiple chiral doublets in 133Ce and 103Rh are discussed.

  8. Numerical and Experimental Investigations of a Rotating Heat Pipe

    SciTech Connect

    Jankowski, Todd A.

    2007-05-01

    Rotating and revolving heat pipes have been used in a variety of applications including heat pipe heat exchangers, cooling of rotating electrical machines, and heat removal in high speed cutting operations. The use of heat pipes in rotating environments has prompted many analytical, numerical, and experimental investigations of the heat transfer characteristics of these devices. Past investigations, however, have been restricted to the study of straight heat pipes. In this work, a curved rotating heat pipe is studied numerically and experimentally. In certain types of rotating machines, heat generating components, which must be cooled during normal operation, are located at some radial distance from the axis of rotation. The bent heat pipe studied here is shown to have advantages when compared to the conventional straight heat pipes in these off-axis cooling scenarios. The heat pipe studied here is built so that both the condenser and evaporator sections are parallel to the axis of rotation. The condenser section is concentric with the axis of rotation while the evaporator section can be placed in contact with off-axis heat sources in the rotating machine. The geometry is achieved by incorporating an S-shaped curve between the on-axis rotating condenser section and the off-axis revolving evaporator section. Furthermore, the heat pipe uses an annular gap wick structure. Incorporating an annular gap wick structure into the heat pipe allows for operation in a non-rotating environment. A numerical model of this rotating heat pipe is developed. The analysis is based on a two-dimensional finite-difference model of the liquid flow coupled to a one-dimensional model of the vapor flow. Although the numerical model incorporates many significant aspects of the fluid flow, the flow in the actual heat pipe is expected to be threedimensional. The rotating heat pipe with the S-shaped curve is also studied experimentally to determine how well the numerical model captures the key

  9. The chaotic rotation of Hyperion

    NASA Technical Reports Server (NTRS)

    Wisdom, J.; Peale, S. J.; Mignard, F.

    1984-01-01

    Under the assumption that the satellite is rotating about a principal axis that is normal to its orbit plane, a plot of spin rate-versus-orientation for Hyperion at the pericenter of its orbit has revealed a large, chaotic zone surrounding Hyperion's synchronous spin-orbit state. The chaotic zone is so large that it surrounds the 1/2 and 2 states, and libration in the 3/2 state is not possible. Rotation in the chaotic zone is also attitude-unstable. As tidal dissipation drives Hyperion's spin toward a nearly synchronous value, Hyperion necessarily enters the large chaotic zone, becoming attitude-unstable and tumbling. It is therefore predicted that Hyperion will be found to be tumbling chaotically.

  10. Rotation periods of exoplanet host stars

    NASA Astrophysics Data System (ADS)

    Simpson, E. K.; Baliunas, S. L.; Henry, G. W.; Watson, C. A.

    2010-11-01

    The stellar rotation periods of 10 exoplanet host stars have been determined using newly analysed CaII H&K flux records from the Mount Wilson Observatory and Strömgren b, y photometric measurements from Tennessee State University's automatic photometric telescopes at the Fairborn Observatory. Five of the rotation periods have not previously been reported, with that of HD 130322 very strongly detected at Prot = 26.1 +/- 3.5 d. The rotation periods of five other stars have been updated using new data. We use the rotation periods to derive the line-of-sight inclinations of the stellar rotation axes, which may be used to probe theories of planet formation and evolution when combined with the planetary orbital inclination found from other methods. Finally, we estimate the masses of 14 exoplanets under the assumption that the stellar rotation axis is aligned with the orbital axis. We calculate the mass of HD 92788 b (28 MJ) to be within the low-mass brown dwarf regime and suggest that this object warrants further investigation to confirm its true nature.

  11. Psoas major and its controversial rotational action.

    PubMed

    Skyrme, A D; Cahill, D J; Marsh, H P; Ellis, H

    1999-01-01

    The action of psoas major muscle as a primary flexor of the hip joint is undisputed. However it is also variably reported as being a medial and a lateral rotator of the femur at the hip joint. The psoas and iliacus muscles, along with their common insertion, were isolated by dissection in six adult cadaveric specimens. The action of psoas muscle was assessed by pulling the muscle along its long axis and then observing the effects on rotation of the femur, with a visual estimation of the rotation in degrees. The experiment was repeated with the hip joint capsule removed. In the anatomical position, applied traction along the long axis of the muscle produced hip flexion with no rotational component. With the hip in the abducted position, traction produced flexion, adduction, and lateral rotation of the femur at the hip joint. In adduction of the hip, traction on psoas produced only flexion at the hip joint, with no rotation. In maximal flexion, traction also produced adduction. The results were unaffected by the removal of the joint capsule.

  12. Rotational motion of Vesta

    NASA Astrophysics Data System (ADS)

    Rambaux, N.; Asmar, S. W.; Konopliv, A. S.

    2012-09-01

    Vesta is the second most massive body of the asteroid belt and contains a giant impact and a differentiated interior. Constraints on internal structure can be inferred from various observations such as gravity field measurements [1]. Especially, detailed knowledge of the rotational motion can help constrain the mass distribution inside the body, which in turn can lead to information on its history. Here, we compute the polar motion, precession-nutation, and length-of-day variations of Vesta. The Vesta's Pole position in space has been obtained by Dawn mission [1] and the orbital pole of Vesta at J2000 can be obtained from the Horizons ephemerides [2]. The obliquity, defined as the angle between the normal to the orbital plane and the figure axis, brings information on the moment of inertia if it has reached its equilibrium position [3], the present value from observations is around 27 degrees. That is far from the ˜ 0.03 deg expected for the equilibrium position. In addition, the required timescale to fully damped the obliquity appears to be very long following the same approach developed in [4]. Thus, it appears that the obliquity of Vesta has not yet relaxed in its Cassini state. The figure of Vesta appears to be triaxial and the Sun exerts a non-zero torque. By following the approach developed for the Earth [e.g. 5] and Ceres [4], we compute the nutation of Vesta. The nutational motion of Vesta is dominated by the semi-annual nutation (996 milli-arcseconds or 1.26 m surface displacement) related to the large obliquity of Vesta, and then terms related to harmonics and also to the planet's mean longitude. The detection of such small displacement requires tracking of Vesta's surface with high precision. The precession time of the axis of Vesta is very long, about 179,000 years.

  13. Myocardial Rotation and Torsion in Child Growth

    PubMed Central

    Kim, Chang Sin; Park, Sora

    2016-01-01

    Background The speckle tracking echocardiography can benefit to assess the regional myocardial deformations. Although, previous reports suggested no significant change in left ventricular (LV) torsion with aging, there are certain differences in LV rotation at the base and apex. The purpose of this study was to evaluate the change and relationship of LV rotation for torsion with aging in children. Methods Forty healthy children were recruited and divided into two groups of twenty based on whether the children were preschool-age (2–6 years of age) or school-age (7–12 years of age). After obtaining conventional echocardiographic data, apical and basal short axis rotation were assessed with speckle tracking echocardiography. LV rotation in the basal and apical short axis planes was determined using six myocardial segments along the central axis. Results Apical and basal LV rotation did not show the statistical difference with increased age between preschool- and school-age children. Apical radial strain showed significant higher values in preschool-age children, especially at the anterior (52.8 ± 17.4% vs. 34.7 ± 23.2%, p < 0.02), lateral (55.8 ± 20.4% vs. 36.1 ± 22.7%, p < 0.02), and posterior segments (57.1 ± 17.6% vs. 38.5 ± 21.7%, p < 0.01). The torsion values did not demonstrate the statistical difference between two groups. Conclusion This study revealed the tendency of higher rotation values in preschool-age children than in school-age children. The lesser values of rotation and torsion with increased age during childhood warrant further investigation. PMID:27721953

  14. Effect of gravity level fluctuations for rotating fluids in high and low rotating speeds

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Hong, B. B.; Leslie, F. W.

    1989-01-01

    Time-dependent evolutions of the profile of the free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with sinusoidal-function vibration of the gravity environment at high and low cylinder speeds.

  15. System for automatically aligning a support roller system under a rotating body

    DOEpatents

    Singletary, B.H.

    1982-07-21

    Two support rings on a rotatable drum respectively engage conically tapered end surfaces of support rollers mounted on pivot universally relative to its axis of rotation and translate therealong. Rotation of the drum on differential conical support roller diameters causes pivotal steering and axial translation of support roller until roller is centered on support rings.

  16. System for automatically aligning a support roller system under a rotating body

    DOEpatents

    Singletary, B. Huston

    1983-01-01

    Two support rings on a rotatable drum respectively engage conically tapered nd surfaces of support rollers mounted on pivot universally relative to its axis of rotation and translate therealong. Rotation of the drum on differential conical support roller diameters causes pivotal steering and axial translation of support roller until roller is centered on support rings.

  17. Dynamical evolution of comet nucleus rotation

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Sidorenko, V. V.; Neishtadt, A. I.; Vasiliev, A. A.

    2002-09-01

    The rotational dynamics of outgassing cometary nuclei are investigated analytically. We develop a general theory for the evolution of a comet nucleus' rotation state using averaging theory and assuming that the outgassing torques are a function of solar insolation and heliocentric distance. The resulting solutions are a function of the nucleus inertia ellipsoid, its outgassing properties, its heliocentric orbit, and the assumed distribution of active regions on its surface. We find that the long-term evolution of the comet nucleus rotation is a strong function of the distribution of active regions over its surface. In particular, we find that nuclei with nearly axisymmetric inertia ellipsoids and a uniformly active surface will tend towards a rotation state that has a nutation angle of ~ 55 degrees and its angular momentum perpendicular to the sun-perihelion direction. If such a comet nucleus has only one isolated active region, it will tend towards a zero nutation angle with its approximate symmetry axis and rotational angular momentum aligned parallel to the sun-perihelion direction. In the general case for an inertia ellipsoid that is not close to being axisymmetric we find a much richer set of possible steady-state solutions that are stable, ranging from rotation about the maximum moment of the inertia axis, to SAM and LAM non-principal axis rotation states. The resulting stable rotation states are a strong function of outgassing activity distribution, which we show using a simplified model of the comet Halley nucleus. Also, we demonstrate that comet Borrely observations are consistent with a stable rotation state. Our results can be used to discriminate between competing theories of comet outgassing based on a nucelus' rotation state. They also allow for a range of plausible a priori constraints to be placed on a comet's rotation state to aid in the interpretation of its outgassing structure. This work was supported by the NASA JURRISS program under Grant NAG5

  18. A mechanical rotator for neutron scattering measurements

    NASA Astrophysics Data System (ADS)

    Thaler, A.; Northen, E.; Aczel, A. A.; MacDougall, G. J.

    2016-12-01

    We have designed and built a mechanical rotation system for use in single crystal neutron scattering experiments at low temperatures. The main motivation for this device is to facilitate the application of magnetic fields transverse to a primary training axis, using only a vertical cryomagnet. Development was done in the context of a triple-axis neutron spectrometer, but the design is such that it can be generalized to a number of different instruments or measurement techniques. Here, we discuss some of the experimental constraints motivating the design, followed by design specifics, preliminary experimental results, and a discussion of potential uses and future extension possibilities.

  19. Eyes open versus eyes closed - Effect on human rotational responses

    NASA Technical Reports Server (NTRS)

    Wall, Conrad, III; Furman, Joseph M. R.

    1989-01-01

    The effect of eyelid closure on the response to rotational vestibular stimulation was assessed by evaluating 16 normal human subjects with both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotations with either eyes closed (EC) or eyes open in the dark (EOD). Results indicated that for EVA rotation, the subjects' responses were of larger magnitude and less variable with EOD than with EC. However, for EHA rotation, responses were of larger magnitude and equally variable with EC as compared to EOD. Data also indicated that the quality of the EHA response with EC was altered because eyelid closure influenced the amount of periodic gaze. It is concluded that eyelid closure has an effect upon both canalocular and otolithocular reflexes and it is suggested that both EVA and EHA rotational testing be performed with EOD rather than with EC.

  20. Measurement of a part having a known axis misalignment

    SciTech Connect

    Castleton, R.

    1993-05-01

    It has been shown that undetected misalignment of the axis of a part can lead to unacceptable measurement errors. For this technical note, it is assumed that the axis misalignment has been determined, and that polar sweeps are used to measure the part. The proposed polar sweeps run vertically (ignoring the axis misalignment) between a plane that is parallel to the bottom datum surface of the part and a second such plane that is close to the pole of the part. No attempt is made to correct for axis misalignment by rotation of the part during the measurement sweeps. It is apparent that the distance traveled along the measurement sweep is more than the arc length representing the actual change in elevation in the part coordinate system. It is proposed that the measurement of the part on the vertical path be used as the measurement of the part on the base longitude line. This introduces an error, {delta}{theta}, in the sensitive direction that corresponds to the arc length B-S. It is shown that this error is not significant when the axis misalignment is small.

  1. Optical angular momentum in a rotating frame.

    PubMed

    Speirits, Fiona C; Lavery, Martin P J; Padgett, Miles J; Barnett, Stephen M

    2014-05-15

    It is well established that light carrying orbital angular momentum (OAM) can be used to induce a mechanical torque causing an object to spin. We consider the complementary scenario: will an observer spinning relative to the beam axis measure a change in OAM as a result of their rotational velocity? Remarkably, although a linear Doppler shift changes the linear momentum of a photon, the angular Doppler shift induces no change in the angular momentum. Further, we examine the rotational Doppler shift in frequency imparted to the incident light due to the relative motion of the beam with respect to the observer and consider what must happen to the measured wavelength if the speed of light c is to remain constant. We show specifically that the OAM of the incident beam is not affected by the rotating observer and that the measured wavelength is shifted by a factor equal and opposite to that of the frequency shift induced by the rotational Doppler effect.

  2. The horizontal computerized rotational impulse test.

    PubMed

    Furman, Joseph M; Shirey, Ian; Roxberg, Jillyn; Kiderman, Alexander

    2016-01-01

    Whole-body impulsive rotations were used to overcome several limitations associated with manual head impulse testing. A computer-controlled rotational chair delivered brief, whole-body, earth-vertical axis yaw impulsive rotations while eye movements were measured using video-oculography. Results from an unselected group of 20 patients with dizziness and a group of 22 control subjects indicated that the horizontal computerized rotational head impulse test (crHIT) is well-tolerated and provides an estimate of unidirectional vestibulo-ocular reflex gain comparable to results from caloric testing. This study demonstrates that the horizontal crHIT is a new assessment tool that overcomes many of the limitations of manual head impulse testing and provides a reliable laboratory-based measure of unilateral horizontal semicircular canal function.

  3. Revisit of rotational dynamics of Asteroid 4179 Toutatis from Chang'e-2's flyby

    NASA Astrophysics Data System (ADS)

    Zhao, Yuhui; Hu, Shoucun; Ji, Jianghui

    2016-01-01

    This paper presents analysis of the rotational parameters of Toutatis based on the observational results from Chang'e-2's close flyby. The 3-D shape model derived from ground-based radar observation is used to calculate the 3-1-3 Euler angles at the flyby epoch, which are evaluated to be -20.1° +/- 1°, 27.6° +/- 1° and 42.2° +/- 1°. The large amplitude of Toutatis' tumbling attitude is demonstrated to be the result of the large deviation of the angular momentum axis and the rotational axis. Two rotational periods are evaluated to be 5.38+/-0.03 days for rotation about the long axis and 7.40+/-0.03 days for precession of the long axis about the angular momentum vector based on Fourier analysis. These results provide a further understanding of rotational state of Toutatis.

  4. Dipole Alignment in Rotating MHD Turbulence

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.; Fu, Terry; Morin, Lee

    2012-01-01

    We present numerical results from long-term CPU and GPU simulations of rotating, homogeneous, magnetohydrodynamic (MHD) turbulence, and discuss their connection to the spherically bounded case. We compare our numerical results with a statistical theory of geodynamo action that has evolved from the absolute equilibrium ensemble theory of ideal MHD turbulence, which is based on the ideal MHD invariants are energy, cross helicity and magnetic helicity. However, for rotating MHD turbulence, the cross helicity is no longer an exact invariant, although rms cross helicity becomes quasistationary during an ideal MHD simulation. This and the anisotropy imposed by rotation suggests an ansatz in which an effective, nonzero value of cross helicity is assigned to axisymmetric modes and zero cross helicity to non-axisymmetric modes. This hybrid statistics predicts a large-scale quasistationary magnetic field due to broken ergodicity , as well as dipole vector alignment with the rotation axis, both of which are observed numerically. We find that only a relatively small value of effective cross helicity leads to the prediction of a dipole moment vector that is closely aligned (less than 10 degrees) with the rotation axis. We also discuss the effect of initial conditions, dissipation and grid size on the numerical simulations and statistical theory.

  5. Axis-switching transitions and the stimulated emission pumping spectrum of HCN

    NASA Astrophysics Data System (ADS)

    Jonas, David M.; Yang, Xueming; Wodtke, Alec M.

    1992-08-01

    Six of the 14 unidentified bands in the stimulated emission pumping (SEP) spectrum of HCN are shown to be forbidden transitions to l`=1 e parity levels of the ground state. The band origins agree with predictions within the error of the anharmonic expansion; the rotational constants, when corrected for rotational-l doubling, agree within experimental error. Rotational-l resonance between l`=0 and l`=2 is found in highly excited bending levels, confirming the extrapolation of the rotational-l resonance and doubling constant q2 from microwave and infrared measurements to 17 000 cm-1. The rotational intensity of the l`=1 bands due to the axis-switching mechanism of Hougen and Watson [Can. J. Phys. 43, 298 (1965)] is shown to be greater than some of the observed allowed rotational transitions to l`=2 when laser polarization effects are taken into account. A qualitative Franck-Condon analysis of the SEP spectrum provides unusually strong evidence for the axis-switching mechanism. The eight remaining unassigned bands are evidently perturbed and are assigned based on agreement between sums of observed rotational constants and sums of zero-order (unperturbed) rotational constants predicted by the anharmonic expansion, the magnitude of the rotational-l resonance, and the expected Franck-Condon factors.

  6. Gut Microbiota-brain Axis

    PubMed Central

    Wang, Hong-Xing; Wang, Yu-Ping

    2016-01-01

    Objective: To systematically review the updated information about the gut microbiota-brain axis. Data Sources: All articles about gut microbiota-brain axis published up to July 18, 2016, were identified through a literature search on PubMed, ScienceDirect, and Web of Science, with the keywords of “gut microbiota”, “gut-brain axis”, and “neuroscience”. Study Selection: All relevant articles on gut microbiota and gut-brain axis were included and carefully reviewed, with no limitation of study design. Results: It is well-recognized that gut microbiota affects the brain's physiological, behavioral, and cognitive functions although its precise mechanism has not yet been fully understood. Gut microbiota-brain axis may include gut microbiota and their metabolic products, enteric nervous system, sympathetic and parasympathetic branches within the autonomic nervous system, neural-immune system, neuroendocrine system, and central nervous system. Moreover, there may be five communication routes between gut microbiota and brain, including the gut-brain's neural network, neuroendocrine-hypothalamic-pituitary-adrenal axis, gut immune system, some neurotransmitters and neural regulators synthesized by gut bacteria, and barrier paths including intestinal mucosal barrier and blood-brain barrier. The microbiome is used to define the composition and functional characteristics of gut microbiota, and metagenomics is an appropriate technique to characterize gut microbiota. Conclusions: Gut microbiota-brain axis refers to a bidirectional information network between the gut microbiota and the brain, which may provide a new way to protect the brain in the near future. PMID:27647198

  7. Unidirectional Heat Transport Driven by Rotating Cholesteric Droplets

    NASA Astrophysics Data System (ADS)

    Sato, Sayumi; Bono, Shinji; Tabe, Yuka

    2017-02-01

    When a cholesteric liquid crystal (LC) is submitted to a thermal gradient, it exhibits continuous director rotation. The phenomenon is called the Lehmann effect and is understood as a thermomechanical coupling in chiral LCs without mirror symmetry. Since the Lehmann effect is considered to possess time-reversal symmetry, one can expect the inverse process, i.e., rotating chiral LCs to pump heat along the rotational axis. We report the first observation of heat transport driven by rotating cholesteric droplets. This result suggests a new function of the cholesterics as a micro heat pump.

  8. Note: Design of a novel rotating magnetic field device

    NASA Astrophysics Data System (ADS)

    Godínez, F. A.; Chávez, O.; Zenit, R.

    2012-06-01

    A novel device to produce a rotating magnetic field was designed, constructed, and tested. The system consists of a Helmholtz coil pair which is mechanically coupled to a dc electric motor whose angular velocity is controlled. The coil pair generates a uniform magnetic field; the whole system is rotated maintaining the coils energized using brushes. The magnetic field strength is uniform (≈5.8 mT) for a workspace of about 100 mm along the rotation axis. The system remains free of undesirable high amplitude mechanical vibrations for rotation frequencies below 10 Hz. We verified the performance of the apparatus by conducting experiments with magnetic swimmers.

  9. Helical axis stellarator equilibrium model

    SciTech Connect

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift.

  10. Development of a scanning touch probe with 5-axis measuring functions

    NASA Astrophysics Data System (ADS)

    Chu, Chih-Liang; Lai, Kuan-Wen; Chen, Hung-Chi

    2015-02-01

    The purpose of this study is to develop a five-axis scanning touch probe with high precision and low contact force. The development of scanning touch probe is consisted of three parts: mechanism design, optical path design, and rotation structure design. The mechanism design contains three parts, Z-axis system, XY-axis system, and probe mechanism. The Z-axis system applies the characteristic of the thin sheet spring to move vertically. In the design of XY-axis system, a micro-beam is employed, through which length, width, and thickness of the micro-beam and corresponding dimensions of the leaf spring are designed according to the selected contact force. The freedom degree is limited to three. And the center of the mechanism is equipped with a stylus to inhibit displacement of the Z-axis. The contact between the probe and the work piece only leads to change in the angles of X- and Y-axes, achieving the feature of 2-degree freedom. To enable rapid change for the probes, this study designs a probe mechanism, reliability of which is analyzed and validated with ANSYS software, so that the design of 3-degree freedom mechanism is completed. The sensor has a laser diode to coordinate with Position Sensor Detector (PSD) which works with the optical path designed to measure placement of Z-axis and angle placement of XY-axis. The rotation structure refers to the principle of 5-axis machining design, and the two rotary axes (A- and C-axis) to join the self-developed scanning probe. This design can achieve independent measurements and eliminate the dynamic measurement error that three-axis scanning systems typically have. By validation through an experiment, the three-dimensional scanning touch probe developed by this study has a measuring range of +/-1mm×+/-1mm×1mm, and unidirectional repeatability of 0.6μm.

  11. Instabilities of a rotating helical rod

    NASA Astrophysics Data System (ADS)

    Park, Yunyoung; Ko, William; Kim, Yongsam; Lim, Sookkyung

    2016-11-01

    Bacteria such as Escherichia coli and Vibrio alginolyticus have helical flagellar filament. By rotating a motor, which is located at the bottom end of the flagellar filament embedded in the cell body, CCW or CW, they swim forward or backward. We model a left-handed helix by the Kirchhoff rod theory and use regularized Stokes formulation to study an interaction between the surrounding fluid and the flagellar filament. We perform numerical studies focusing on relations between physical parameters and critical angular frequency of the motor, which separates overwhiring from twirling. We are also interested in the buckling instability of the hook, which is very flexible elastic rod. By measuring buckling angle, which is an angle between rotational axis and helical axis, we observe the effects of physical parameters on buckling of the hook.

  12. Single Axis Attitude Control and DC Bus Regulation with Two Flywheels

    NASA Technical Reports Server (NTRS)

    Kascak, Peter E.; Jansen, Ralph H.; Kenny, Barbara; Dever, Timothy P.

    2002-01-01

    A computer simulation of a flywheel energy storage single axis attitude control system is described. The simulation models hardware which will be experimentally tested in the future. This hardware consists of two counter rotating flywheels mounted to an air table. The air table allows one axis of rotational motion. An inertia DC bus coordinator is set forth that allows the two control problems, bus regulation and attitude control, to be separated. Simulation results are presented with a previously derived flywheel bus regulator and a simple PID attitude controller.

  13. Using the axis of elongation to align shapes: Developmental changes between 18 and 24 months

    PubMed Central

    Smith, Linda B.; Street, Sandra; Jones, Susan S.; James, Karin H.

    2014-01-01

    An object’s axis of elongation serves as an important frame of reference for forming 3-dimensional representations of object shape. By several recent accounts, the formation of these representations is also related to experiences of acting on objects. Four experiments examined 18- to 24-month-old (N = 103) infants’ sensitivity to the elongated axis in action tasks that required extracting, comparing and physically rotating an object so that its major axis was aligned with that of a visual standard. In Experiments 1 and 2, the older infants precisely rotated both simple and complexly shaped 3-dimensional objects in insertion tasks in which the visual standard was the rectangular contour defining the opening in a box. The younger infants performed poorly. Experiments 3 and 4 provide evidence on emerging abilities in extracting and using the most extended axis as a frame of reference for shape comparison. Experiment 3 showed that 18 month olds could rotate an object to align its major axis to the direction of their own hand motion and Experiment 4 showed that they could align the major axis of one object to that of another object of the exact same 3-dimensional shape. The results are discussed in terms of theories of the development of 3-dimensional shape representations, visual object recognition, and the role of action in these developments. PMID:24650776

  14. Compensation to whole body active rotation perturbation.

    PubMed

    Rossi, S; Gazzellini, S; Petrarca, M; Patanè, F; Salfa, I; Castelli, E; Cappa, P

    2014-01-01

    The aim of the present study is the exploration of the compensation mechanisms in healthy adults elicited by superimposing a horizontal perturbation, through a rotation of the support base, during a whole body active rotation around the participant's own vertical body axis. Eight healthy participants stood on a rotating platform while executing 90° whole body rotations under three conditions: no concurrent platform rotation (NP), support surface rotation of ± 45° in the same (45-S) and opposite (45-O) directions. Participants' kinematics and CoP displacements were analyzed with an optoelectronic system and a force platform. In both 45-S and 45-O conditions, there was a tendency for the head to be affected by the external perturbation and to be the last and least perturbed segment while the pelvis was the most perturbed. The observed reduced head perturbation in 45-S and 45-O trials is consistent with a goal-oriented strategy mediated by vision and vestibular information, whereas the tuning of lumbar rotation is consistent with control mechanisms mediated by somato-sensory information.

  15. Anatomical study of the gastrointestinal tract in free-living axis deer (Axis axis).

    PubMed

    Pérez, W; Erdogan, S; Ungerfeld, R

    2015-02-01

    The macroscopic anatomy of the stomach and intestines of adult axis deer (Axis axis), a cervid species considered intermediate/mixed feeder, was observed and recorded. Nine adult wild axis deers of both sexes were used and studied by simple dissection. The ruminal papillae were distributed unevenly in the overall area of the inner surface of rumen and primarily were more large and abundant within the atrium. The ruminal pillars had no papillae. There was an additional ruminal pillar located between the right longitudinal and right coronary ventral pillars connected to the caudal pillar. No dorsal coronary pillars were found, and the ventral coronary pillars are connected. The reticulum was the third compartment in size, and the maximum height of the reticular crests was 1.0 mm. The Cellulae reticuli were not divided and rarely contained secondary crests. There were no Papillae unguiculiformes. The omasum was the smallest gastric compartment. The abomasum had about twelve spiral plicae, and a small pyloric torus was present. The intraruminal papillation was similar to those species that are characterized by a higher proportion of grass in their natural diet. The finding of the small reticular crests is typical for browser ruminants and was coincident with data reported for other deer. The comparative ratio of the small intestine to the large intestine was 1.69, in terms of length measurements in axis deer and appears below of the 'browser range'. We concluded that the gastrointestinal system of axis deer reflected similar morphological characteristics of the both types of ruminants: browser and grazer, and we consider it as an intermediate feeder.

  16. Three axis velocity probe system

    DOEpatents

    Fasching, George E.; Smith, Jr., Nelson S.; Utt, Carroll E.

    1992-01-01

    A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head. Any changes in these currents due to the particle are amplified and synchronously detected to produce positional signal values that are converted to digital form. Using these digital forms and two values of time permit generation of values of the three components of the particle vector and thus the total velocity vector.

  17. Face seal assembly for rotating drum

    DOEpatents

    Morgan, J. Giles; Rennich, Mark J.; Whatley, Marvin E.

    1982-01-01

    A seal assembly comprises a tube rotatable about its longitudinal axis and having two longitudinally spaced flanges projecting radially outwardly from the outer surface thereof. Slidably positioned against one of the flanges is a seal ring, and disposed between this seal ring and the other flange are two rings that are forced apart by springs, one of the latter rings being attached to a flexible wall.

  18. Fetal and Neonatal HPA Axis.

    PubMed

    Wood, Charles E; Walker, Claire-Dominique

    2015-12-15

    Stress is an integral part of life. Activation of the hypothalamus-pituitary-adrenal (HPA) axis in the adult can be viewed as mostly adaptive to restore homeostasis in the short term. When stress occurs during development, and specifically during periods of vulnerability in maturing systems, it can significantly reprogram function, leading to pathologies in the adult. Thus, it is critical to understand how the HPA axis is regulated during developmental periods and what are the factors contributing to shape its activity and reactivity to environmental stressors. The HPA axis is not a passive system. It can actively participate in critical physiological regulation, inducing parturition in the sheep for instance or being a center stage actor in the preparation of the fetus to aerobic life (lung maturation). It is also a major player in orchestrating mental function, metabolic, and cardiovascular function often reprogrammed by stressors even prior to conception through epigenetic modifications of gametes. In this review, we review the ontogeny of the HPA axis with an emphasis on two species that have been widely studied-sheep and rodents-because they each share many similar regulatory mechanism applicable to our understanding of the human HPA axis. The studies discussed in this review should ultimately inform us about windows of susceptibility in the developing brain and the crucial importance of early preconception, prenatal, and postnatal interventions designed to improve parental competence and offspring outcome. Only through informed studies will our public health system be able to curb the expansion of many stress-related or stress-induced pathologies and forge a better future for upcoming generations.

  19. Low order physical models of vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Craig, Anna; Dabiri, John; Koseff, Jeffrey

    2016-11-01

    In order to examine the ability of low-order physical models of vertical axis wind turbines to accurately reproduce key flow characteristics, experiments were conducted on rotating turbine models, rotating solid cylinders, and stationary porous flat plates (of both uniform and non-uniform porosities). From examination of the patterns of mean flow, the wake turbulence spectra, and several quantitative metrics, it was concluded that the rotating cylinders represent a reasonably accurate analog for the rotating turbines. In contrast, from examination of the patterns of mean flow, it was found that the porous flat plates represent only a limited analog for rotating turbines (for the parameters examined). These findings have implications for both laboratory experiments and numerical simulations, which have previously used analogous low order models in order to reduce experimental/computational costs. NSF GRF and SGF to A.C; ONR N000141211047 and the Gordon and Betty Moore Foundation Grant GBMF2645 to J.D.; and the Bob and Norma Street Environmental Fluid Mechanics Laboratory at Stanford University.

  20. Survival analysis of deep-water floating offshore platforms: Critical axis

    SciTech Connect

    Falzarano, J.M.; Kota, R.S.

    1996-12-31

    This paper describes the global dynamics of a typical Column Stabilized Mobile Offshore Drilling Unit (CS-MODU) about its critical, approximately quartering axis. It is well known that short and wide (i.e., small L/B ratio) twin hull vessels such as CS-MODU`s have minimum righting moment about an approximately quartering axis. This paper attempts to answer the question of whether this is also a critical rotational motion axis. In order to answer this question, a comparative global transient dynamical systems analysis is undertaken which compares the vessels response at all heading angles.

  1. On the Stability of Rotating Drops

    PubMed Central

    Nurse, A. K.; Coriell, S. R.; McFadden, G. B.

    2015-01-01

    We consider the equilibrium and stability of rotating axisymmetric fluid drops by appealing to a variational principle that characterizes the equilibria as stationary states of a functional containing surface energy and rotational energy contributions, augmented by a volume constraint. The linear stability of a drop is determined by solving the eigenvalue problem associated with the second variation of the energy functional. We compute equilibria corresponding to both oblate and prolate shapes, as well as toroidal shapes, and track their evolution with rotation rate. The stability results are obtained for two cases: (i) a prescribed rotational rate of the system (“driven drops”), or (ii) a prescribed angular momentum (“isolated drops”). For families of axisymmetric drops instabilities may occur for either axisymmetric or non-axisymmetric perturbations; the latter correspond to bifurcation points where non-axisymmetric shapes are possible. We employ an angle-arc length formulation of the problem which allows the computation of equilibrium shapes that are not single-valued in spherical coordinates. We are able to illustrate the transition from spheroidal drops with a strong indentation on the rotation axis to toroidal drops that do not extend to the rotation axis. Toroidal drops with a large aspect ratio (major radius to minor radius) are subject to azimuthal instabilities with higher mode numbers that are analogous to the Rayleigh instability of a cylindrical interface. Prolate spheroidal shapes occur if a drop of lower density rotates within a denser medium; these drops appear to be linearly stable. This work is motivated by recent investigations of toroidal tissue clusters that are observed to climb conical obstacles after self-assembly [Nurse et al., Journal of Applied Mechanics 79 (2012) 051013]. PMID:26958440

  2. Process and apparatus for measuring degree of polarization and angle of major axis of polarized beam of light

    DOEpatents

    Decker, Derek E.; Toeppen, John S.

    1994-01-01

    Apparatus and process are disclosed for calibrating measurements of the phase of the polarization of a polarized beam and the angle of the polarized optical beam's major axis of polarization at a diagnostic point with measurements of the same parameters at a point of interest along the polarized beam path prior to the diagnostic point. The process is carried out by measuring the phase angle of the polarization of the beam and angle of the major axis at the point of interest, using a rotatable polarizer and a detector, and then measuring these parameters again at a diagnostic point where a compensation apparatus, including a partial polarizer, which may comprise a stack of glass plates, is disposed normal to the beam path between a rotatable polarizer and a detector. The partial polarizer is then rotated both normal to the beam path and around the axis of the beam path until the detected phase of the beam polarization equals the phase measured at the point of interest. The rotatable polarizer at the diagnostic point may then be rotated manually to determine the angle of the major axis of the beam and this is compared with the measured angle of the major axis of the beam at the point of interest during calibration. Thereafter, changes in the polarization phase, and in the angle of the major axis, at the point of interest can be monitored by measuring the changes in these same parameters at the diagnostic point.

  3. Measurement of turbulent wind velocities using a rotating boom apparatus

    SciTech Connect

    Sandborn, V.A.; Connell, J.R.

    1984-04-01

    The present report covers both the development of a rotating-boom facility and the evaluation of the spectral energy of the turbulence measured relative to the rotating boom. The rotating boom is composed of a helicopter blade driven through a pulley speed reducer by a variable speed motor. The boom is mounted on a semiportable tower that can be raised to provide various ratios of hub height to rotor diameter. The boom can be mounted to rotate in either the vertical or horizontal plane. Probes that measure the three components of turbulence can be mounted at any location along the radius of the boom. Special hot-film sensors measured two components of the turbulence at a point directly in front of the rotating blade. By using the probe rotated 90/sup 0/ about its axis, the third turbulent velocity component was measured. Evaluation of the spectral energy distributions for the three components of velocity indicates a large concentration of energy at the rotational frequency. At frequencies slightly below the rotational frequency, the spectral energy is greatly reduced over that measured for the nonrotating case measurements. Peaks in the energy at frequencies that are multiples of the rotation frequency were also observed. We conclude that the rotating boom apparatus is suitable and ready to be used in experiments for developing and testing sensors for rotational measurement of wind velocity from wind turbine rotors. It also can be used to accurately measure turbulent wind for testing theories of rotationally sampled wind velocity.

  4. Optical slip ring for off-axis high-bit-rate data transmission.

    PubMed

    Helzel, T; Martens, G

    1986-03-01

    A 0.9-m diam off-axis optical slip ring for a 140-Mbit/s data transmission between the fixed and rotating parts of a continuously rotating device has been made. A grazing incidence multiple reflection technique has been used in this data link for guiding the light around the circumference of the slip ring. The optical properties are discussed as well as a special arrangement for the compensation of pulse delay time effects.

  5. Two-axis MEMS scanner with transfer-printed high-reflectivity, broadband monolithic silicon photonic crystal mirrors.

    PubMed

    Jeong, Jae-Woong; Park, Bryan; Keum, Hohyun; Kim, Seok; Rogers, John A; Solgaard, Olav

    2013-06-03

    We present a two-axis electrostatic MEMS scanner with high-reflectivity monolithic single-crystal-silicon photonic crystal (PC) mirrors suitable for applications in harsh environments. The reflective surfaces of the MEMS scanner are transfer-printed PC mirrors with low polarization dependence, low angular dependence, and reflectivity over 85% in the wavelength range of 1490nm~1505nm and above 90% over the wavelength band of 1550~1570nm. In static mode, the scanner has total scan range of 10.2° on one rotation axis and 7.8° on the other. Dynamic operation on resonance increase the scan range to 21° at 608Hz around the outer rotation axis and 9.5° at 1.73kHz about the inner rotation axis.

  6. Computational analysis of vertical axis wind turbine arrays

    NASA Astrophysics Data System (ADS)

    Bremseth, J.; Duraisamy, K.

    2016-10-01

    Canonical problems involving single, pairs, and arrays of vertical axis wind turbines (VAWTs) are investigated numerically with the objective of understanding the underlying flow structures and their implications on energy production. Experimental studies by Dabiri (J Renew Sustain Energy 3, 2011) suggest that VAWTs demand less stringent spacing requirements than their horizontal axis counterparts and additional benefits may be obtained by optimizing the placement and rotational direction of VAWTs. The flowfield of pairs of co-/counter-rotating VAWTs shows some similarities with pairs of cylinders in terms of wake structure and vortex shedding. When multiple VAWTs are placed in a column, the extent of the wake is seen to spread further downstream, irrespective of the direction of rotation of individual turbines. However, the aerodynamic interference between turbines gives rise to regions of excess momentum between the turbines which lead to significant power augmentations. Studies of VAWTs arranged in multiple columns show that the downstream columns can actually be more efficient than the leading column, a proposition that could lead to radical improvements in wind farm productivity.

  7. Spin-Axis Alignment of Koronis Family Asteroids

    NASA Astrophysics Data System (ADS)

    Slivan, Stephen Michael

    1995-01-01

    The Koronis asteroid family is believed to have formed through the catastrophic collisional disruption of a large parent body. Collisional evolution studies have thus far not well constrained its age, although it appears to be younger than the Eos family (Binzel, (7)). It has been hypothesized that the relatively large mean amplitudes of rotational brightness variations observed from its members are due to spin axes of member asteroids being preferentially aligned at low obliquities. Such spin axis alignment could only occur for a young family, since as family members undergo collisional evolution subsequent to their formation, it's expected each object's spin axis would be reoriented away from that of the parent body on a relatively short time scale. The present work was undertaken to test whether family members have retained a preferential orientation. A long-term survey of lightcurves for members of the Koronis family, and subsequent analysis of their distributions of spin axes, have been completed. The observational database includes published and unpublished rotational lightcurves obtained through 1994. The most recent data (1992-1994) were obtained using CCD imaging systems during 111 nights at the MIT Wallace Astrophysical Observatory (Westford, MA), 5 nights at the University of Texas McDonald Observatory, and 3 nights at the Michigan-Dartmouth-MIT Observatory. Spin axis solutions of nine Koronis family asteroids are now available, including 243 Ida whose pole and shape were determined prior to the Galileo flyby by Binzel et al. (11). The results support the hypothesis that the spin vectors are preferentially clustered, to within the axis ambiguities inherent in the axis-determination method used, and the obliquities of the sample objects appear to be partitioned into two relatively narrow groupings near 25^circ and 55 ^circ. A very crude minimum family age of about 50 million years is estimated based on the limited dispersion of the axis latitudes. The

  8. Angle estimation of simultaneous orthogonal rotations from 3D gyroscope measurements.

    PubMed

    Stančin, Sara; Tomažič, Sašo

    2011-01-01

    A 3D gyroscope provides measurements of angular velocities around its three intrinsic orthogonal axes, enabling angular orientation estimation. Because the measured angular velocities represent simultaneous rotations, it is not appropriate to consider them sequentially. Rotations in general are not commutative, and each possible rotation sequence has a different resulting angular orientation. None of these angular orientations is the correct simultaneous rotation result. However, every angular orientation can be represented by a single rotation. This paper presents an analytic derivation of the axis and angle of the single rotation equivalent to three simultaneous rotations around orthogonal axes when the measured angular velocities or their proportions are approximately constant. Based on the resulting expressions, a vector called the simultaneous orthogonal rotations angle (SORA) is defined, with components equal to the angles of three simultaneous rotations around coordinate system axes. The orientation and magnitude of this vector are equal to the equivalent single rotation axis and angle, respectively. As long as the orientation of the actual rotation axis is constant, given the SORA, the angular orientation of a rigid body can be calculated in a single step, thus making it possible to avoid computing the iterative infinitesimal rotation approximation. The performed test measurements confirm the validity of the SORA concept. SORA is simple and well-suited for use in the real-time calculation of angular orientation based on angular velocity measurements derived using a gyroscope. Moreover, because of its demonstrated simplicity, SORA can also be used in general angular orientation notation.

  9. Boundary Layer Transition Detection on a Rotor Blade Using Rotating Mirror Thermography

    NASA Technical Reports Server (NTRS)

    Heineck, James T.; Schuelein, Erich; Raffel, Markus

    2014-01-01

    Laminar-to-turbulent transition on a rotor blade in hover has been imaged using an area-scan infrared camera. A new method for tracking a blade using a rotating mirror was employed. The mirror axis of rotation roughly corresponded to the rotor axis of rotation and the mirror rotational frequency is 1/2 that of the rotor. This permitted the use of cameras whose integration time was too long to prevent image blur due to the motion of the blade. This article will show the use of this method for a rotor blade at different collective pitch angles.

  10. Stress and the Reproductive Axis

    PubMed Central

    Toufexis, Donna; Rivarola, Maria Angelica; Lara, Hernan; Viau, Victor

    2014-01-01

    There exists a reciprocal relationship between the hypothalamic-pituitary-adrenal (HPA) and the hypothalamic-pituitary-gonadal (HPG) axes wherein the activation of one affects the function of the other and vice versa. For instance, both testosterone and oestrogen modulate the response of the HPA axis, while activation of the stress axis, especially activation that is repeating or chronic, has an inhibitory effect upon oestrogen and testosterone secretion. Alterations in maternal care can produce significant effects on both HPG and HPA physiology and behaviour in the offspring at adulthood. For example, changes in reproductive behaviour induced by altered maternal care may alter the expression of sex hormone receptors like ERα that govern sexual behaviour, and may be particularly important in determining the sexual strategies utilized by females. Stress in adulthood continues to mediate HPG activity in females through activation of a sympathetic neural pathway originating in the hypothalamus and releasing norepinephrine (NE) into the ovary, which produces a non-cyclic anovulatory ovary that develops cysts. In the opposite direction, sex differences and sex steroid hormones regulate the HPA axis. For example, although serotonin (5-HT) has a stimulatory effect on the HPA axis in humans and rodents that is mediated by the 5-HT1A receptor, only male rodents respond to 5-HT1A antagonism to show increased corticosterone responses to stress. Furthermore, oestrogen appears to decrease 5-HT1A receptor function at presynaptic sites, yet increase 5-HT1A receptor expression at postsynaptic sites. These mechanisms could explain heightened stress HPA axis responses in females compared to males. Studies on female rhesus macaques show that chronic stress in socially subordinate female monkeys produces a distinct behavioral phenotype that is largely unaffected by oestrogen, a hypo-responsive HPA axis that is hypersensitive to the modulating effects of oestrogen, and changes in 5-HT

  11. Perception of longitudinal body axis in microgravity during parabolic flight.

    PubMed

    Clément, Gilles; Arnesen, Tonje N; Olsen, Morten H; Sylvestre, Bruno

    2007-02-14

    It has been proposed that an internal representation of body vertical has a prominent role in spatial orientation. This investigation investigated the ability of human subjects to accurately locate their longitudinal body axis (an imaginary straight body midline running from head to toes) while free-floating in microgravity. Subjects were tested in-flight, as well as on ground in normal gravity in both the upright and supine orientations to provide baseline measurements. The subjects wore a goggle device and were in total darkness. They used knobs to rotate two luminous lines until they were parallel to the subjective direction of their longitudinal body axis, in the roll (right/left) and the pitch (forward/backward) planes. Results showed that the error between the perceived and the objective direction of the longitudinal body axis was significantly larger in microgravity than in normal gravity. This error in this egocentric frame of reference is presumably due to the absence of somatosensory cues when free-floating. Mechanical pressure on the chest using an airbag reduced the error in perception of the longitudinal body axis in microgravity, thus improving spatial orientation.

  12. A four-axis hand controller for helicopter flight control

    NASA Technical Reports Server (NTRS)

    Demaio, Joe

    1993-01-01

    A proof-of-concept hand controller for controlling lateral and longitudinal cyclic pitch, collective pitch and tail rotor thrust was developed. The purpose of the work was to address problems of operator fatigue, poor proprioceptive feedback and cross-coupling of axes associated with many four-axis controller designs. The present design is an attempt to reduce cross-coupling to a level that can be controlled with breakout force, rather than to eliminate it entirely. The cascaded design placed lateral and longitudinal cyclic in their normal configuration. Tail rotor thrust was placed atop the cyclic controller. A left/right twisting motion with the wrist made the control input. The axis of rotation was canted outboard (clockwise) to minimize cross-coupling with the cyclic pitch axis. The collective control was a twist grip, like a motorcycle throttle. Measurement of the amount of cross-coupling involved in pure, single-axis inputs showed cross coupling under 10 percent of full deflection for all axes. This small amount of cross-coupling could be further reduced with better damping and force gradient control. Fatigue was not found to be a problem, and proprioceptive feedback was adequate for all flight tasks executed.

  13. Novel system for optical axis on-line calibration

    NASA Astrophysics Data System (ADS)

    Qiao, Wen; Yan, Huimin; Lu, Wei

    2007-12-01

    Calibration of optical axis is an essential process to ensure the quality of optical systems. Only when the light path center, CCD (Charge Coupled Device) center and rotary center of motor fit each other well, can the system run properly to fulfill the proposed function. However, in most cases, the process is conducted by experienced workers and it is hard to precisely evaluate the coherence of optical axis. So the development of an optical calibrator that can detect the optical axis and calibrate the center automatically is of high priority for precise optical instruments. In this research project, we aim to develop a novel system for optical axis online calibration. The system is based on photoelectric encoder for rotary signal sampling of motor. MCU (Micro Controlling Unit) is used as the main control module instead of PC to miniaturize and simplify the system. CPLD (Complex Programmable Logic Device) is employed to realize high speed data storage and processing. A motor driving circuit and a voltage interval location method are designed to control the motor to rotate precisely. The novel optical calibrator has already been taken into practical application in factories, and proved to be of high stability and resolution.

  14. Modeling of prosthetic limb rotation control by sensing rotation of residual arm bone.

    PubMed

    Li, Guanglin; Kuiken, Todd A

    2008-09-01

    We proposed a new approach to improve the control of prosthetic arm rotation in amputees. Arm rotation is sensed by implanting a small permanent magnet into the distal end of the residual bone, which produces a magnetic field. The position of the bone rotation can be derived from magnetic field distribution detected with magnetic sensors on the arm surface, and then conveyed to the prosthesis controller to manipulate the rotation of the prosthesis. Proprioception remains intact for residual limb skeletal structures; thus, this control system should be natural and easy-to-use. In this study, simulations have been conducted in an upper arm model to assess the feasibility and performance of sensing the voluntary rotation of residual humerus with an implanted magnet. A sensitivity analysis of the magnet size and arm size was presented. The influence of relative position of the magnet to the magnetic sensors, orientation of the magnet relative to the limb axis, and displacement of the magnetic sensors on the magnetic field was evaluated. The performance of shielding external magnetostatic interference was also investigated. The simulation results suggest that the direction and angle of rotation of residual humerus could be obtained by decoding the magnetic field signals with magnetic sensors built into a prosthetic socket. This pilot study provides important guidelines for developing a practical interface between the residual bone rotation and the prosthesis for control of prosthetic rotation.

  15. Modeling of Prosthetic Limb Rotation Control by Sensing Rotation of Residual Arm Bone

    PubMed Central

    Kuiken, Todd A.

    2011-01-01

    We proposed a new approach to improve the control of prosthetic arm rotation in amputees. Arm rotation is sensed by implanting a small permanent magnet into the distal end of the residual bone, which produces a magnetic field. The position of the bone rotation can be derived from magnetic field distribution detected with magnetic sensors on the arm surface, and then conveyed to the prosthesis controller to manipulate the rotation of the prosthesis. Proprioception remains intact for residual limb skeletal structures; thus, this control system should be natural and easy-to-use. In this study, simulations have been conducted in an upper arm model to assess the feasibility and performance of sensing the voluntary rotation of residual humerus with an implanted magnet. A sensitivity analysis of the magnet size and arm size was presented. The influence of relative position of the magnet to the magnetic sensors, orientation of the magnet relative to the limb axis, and displacement of the magnetic sensors on the magnetic field was evaluated. The performance of shielding external magnetostatic interference was also investigated. The simulation results suggest that the direction and angle of rotation of residual humerus could be obtained by decoding the magnetic field signals with magnetic sensors built into a prosthetic socket. This pilot study provides important guidelines for developing a practical interface between the residual bone rotation and the prosthesis for control of prosthetic rotation. PMID:18713682

  16. An overview of craniospinal axis fields and field matching

    SciTech Connect

    Scott, Robin L.

    2013-01-01

    Many methods are implemented for craniospinal axis (CSA) radiation treatment (RT). This paper’s goal is to define correctly matched CSA RT fields. Overlap or a space between matched RT fields can create variances of dose and the possibility of negative side effects or disease recurrence, respectively. An accurate CSA RT match procedure is created with localization markers, immobilization devices, equations, feathered matches, safety gap, and portal imaging. A CS match angle is predetermined to optimize patient position before immobilization device fabrication. Various central axis (CA) placements within the brain and spine fields that effect gantry, table, and collimator rotation are described. An overview of the methods used to create CSA RT fields and matches is presented for optimal CSA RT implementation. In addition, to the author’s knowledge, this is the first time that a prone CSA RT with anesthesia has been described.

  17. Effective solidity in vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Parker, Colin M.; Leftwich, Megan C.

    2016-11-01

    The flow surrounding vertical axis wind turbines (VAWTs) is investigated using particle imaging velocimetry (PIV). This is done in a low-speed wind tunnel with a scale model that closely matches geometric and dynamic properties tip-speed ratio and Reynolds number of a full size turbine. Previous results have shown a strong dependance on the tip-speed ratio on the wake structure of the spinning turbine. However, it is not clear whether this is a speed or solidity effect. To determine this, we have measured the wakes of three turbines with different chord-to-diameter ratios, and a solid cylinder. The flow is visualized at the horizontal mid-plane as well as the vertical mid-plane behind the turbine. The results are both ensemble averaged and phase averaged by syncing the PIV system with the rotation of the turbine. By keeping the Reynolds number constant with both chord and diameter, we can determine how each effects the wake structure. As these parameters are varied there are distinct changes in the mean flow of the wake. Additionally, by looking at the vorticity in the phase averaged profiles we can see structural changes to the overall wake pattern.

  18. Analysis of buoyancy effect on fully developed laminar heat transfer in a rotating tube

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1985-01-01

    Laminar heat transfer is analyzed in a tube rotating about an axis perpendicular to the tube axis. The solution applies for flow that is either radially outward from the axis of rotation, or radially inward toward the axis of rotation. The conditions are fully developed, and there is uniform heat addition at the tube wall. The analysis is performed by expanding velocities and temperature in power series using the Taylor number as a perturbation parameter. Coriolis and buoyancy forces caused by tube rotation are included, and the solution is calculated through second-order terms. The secondary flow induced by the Coriolis terms always tends to increase the heat transfer coefficient; this effect can dominate for small wall heating. For radial inflow, buoyancy also tends to improve heat transfer. For radial outflow, however, buoyancy tends to reduce heat transfer; for large wall heating this effect can dominate, and there is a net reduction in heat transfer coefficient.

  19. The aging reproductive neuroendocrine axis.

    PubMed

    Brann, Darrell W; Mahesh, Virendra B

    2005-04-01

    It is well known that the reproductive system is one of the first biological systems to show age-related decline. While depletion of ovarian follicles clearly relates to the end of reproductive function in females, evidence is accumulating that a hypothalamic defect is critical in the transition from cyclicity to acyclicity. This minireview attempts to present a concise review on aging of the female reproductive neuroendocrine axis and provide thought-provoking analysis and insights into potential future directions for this field. Evidence will be reviewed, which shows that a defect in pulsatile and surge gonadotropin hormone-releasing hormone (GnRH) secretion exists in normal cycling middle-aged female rats, which is thought to explain the significantly attenuated pulsatile and surge luteinizing hormone (LH) secretion at middle-age. Evidence is also presented, which supports the age-related defect in GnRH secretion as being due to a reduced activation of GnRH neurons. Along these lines, stimulation of GnRH secretion by the major excitatory transmitter glutamate is shown to be significantly attenuated in middle-aged proestrous rats. Corresponding age-related defects in other major excitatory regulatory factors, such as catecholamines, neuropeptide Y, and astrocytes, have also been demonstrated. Age-related changes in hypothalamic concentrations of neurotransmitter receptors, steroid receptors, and circulating steroid hormone levels are also reviewed, and discussion is presented on the complex interrelationships of the hypothalamus-pituitary-ovarian (HPO) axis during aging, with attention to how a defect in one level of the axis can induce defects in other levels, and thereby potentiate the dysfunction of the entire HPO axis.

  20. Linking mantle convection with rotational dynamics on Earth

    NASA Astrophysics Data System (ADS)

    Rose, I.; Buffett, B. A.

    2012-12-01

    Ian Rose and Bruce Buffett University of California, Berkeley A surprising number of features of the solid Earth are aligned with its rotation axis: plate velocities are faster near the equator and may have a net westward drift, the seismically-observed LLSVPs are located equatorially and may have been stable over hundred million year time scales, and large-scale geoid highs reside on the equator. All of these observations suggest that convection and rotation of Earth's mantle are linked, despite the small relative sizes of the rotational forces in Earth's mantle. Coupling of solid-Earth convection and its rotation may be through centrifugal forces on density anomalies in the mantle, gravitational perturbations due to the hydrostatic bulge, changes in the rotation axis due to changes in Earth's moment of inertia, or some combination of the three. We investigate the interplay between convection and rotation using models that fully couple the processes. We accomplish this in the following ways: 1) Earth will tend to rotate about the axis of its maximum moment of inertia. At every time step we solve for this axis and compute the rotational forces accordingly. 2) We implement a true free surface boundary condition with a remeshing algorithm that allows the hydrostatic bulge to adjust dynamically (critical to getting the correct rates of true polar wander). 3) We use Lagrangian tracer particles to represent compositional heterogeneity, as they reduce numerical diffusion and allow for history dependent materials. With these we may represent potentially large contributors to the moment of inertia such as continents and LLSVPs. Here we discuss details of implementation of the model and preliminary results constraining the rate and magnitude of true polar wander on Earth.

  1. Rotating bio-reactor cell culture apparatus

    NASA Technical Reports Server (NTRS)

    Schwarz, Ray P. (Inventor); Wolf, David A. (Inventor)

    1991-01-01

    A bioreactor system is described in which a tubular housing contains an internal circularly disposed set of blade members and a central tubular filter all mounted for rotation about a common horizontal axis and each having independent rotational support and rotational drive mechanisms. The housing, blade members and filter preferably are driven at a constant slow speed for placing a fluid culture medium with discrete microbeads and cell cultures in a discrete spatial suspension in the housing. Replacement fluid medium is symmetrically input and fluid medium is symmetrically output from the housing where the input and the output are part of a loop providing a constant or intermittent flow of fluid medium in a closed loop.

  2. Flow in a partially filled rotating cylinder

    NASA Astrophysics Data System (ADS)

    Shadday, M. A., Jr.

    Axial flow in a rapidly rotating cylinder, partially filled with a viscous, incompressible fluid is measured with a laser-Doppler velocimeter. The cylinder has a vertical axis of rotation, and the axial circulation is induced by rotating a coaxially mounted disk at the top endcap slightly faster than the cylinder. The experimental results are compared with the predictions of a finite-difference model of the flow, and the correlation is qualitatively good. The axial circulation in the fluid layer is confined primarily to E(1/3) shear layers along the lateral boundaries, where E is the Ekman number. The radial transport in the Ekman layers is essentially unaffected by the presence of the free surface. It will be shown that this leads to axial transport in an E(1/3) boundary layer along the free surface.

  3. Flow in a partially filled rotating cylinder

    NASA Astrophysics Data System (ADS)

    Shadday, M. A., Jr.

    1982-05-01

    Axial flow in a rapidly rotating cylinder, partially filled with a viscous, incompressible fluid is measured with a laser Doppler velocimeter. The cylinder has a vertical axis of rotation, and the axial circulation is induced by rotating a coaxially mounted disk at the top endcap slightly faster than the cylinder. The experimental results are compared with the prediction of a finite difference model of the flow, and the correlation is qualitatively good. The axial circulation in the fluid layer is confined primarily to E/sup 1/3/ shear layers along the lateral boundaries, where E is the Ekman number. The radial transport in the Ekman layers is essentially unaffected by the presence of the free surface. It will be shown that this leads to axial transport in an E/sup 1/3/ boundary layer along the free surface.

  4. Mental rotation task of hands: differential influence number of rotational axes

    PubMed Central

    van Lier, Rob; Steenbergen, Bert

    2010-01-01

    Various studies on the hand laterality judgment task, using complex sets of stimuli, have shown that the judgments during this task are dependent on bodily constraints. More specific, these studies showed that reaction times are dependent on the participant’s posture or differ for hand pictures rotated away or toward the mid-sagittal plane (i.e., lateral or medial rotation, respectively). These findings point to the use of a cognitive embodied process referred to as motor imagery. We hypothesize that the number of axes of rotation of the displayed stimuli during the task is a critical factor for showing engagement in a mental rotation task, with an increased number of rotational axes leading to a facilitation of motor imagery. To test this hypothesis, we used a hand laterality judgment paradigm in which we manipulated the difficulty of the task via the manipulation of the number of rotational axes of the shown stimuli. Our results showed increased influence of bodily constraints for increasing number of axes of rotation. More specifically, for the stimulus set containing stimuli rotated over a single axis, no influence of biomechanical constraints was present. The stimulus sets containing stimuli rotated over more than one axes of rotation did induce the use of motor imagery, as a clear influence of bodily constraints on the reaction times was found. These findings extend and refine previous findings on motor imagery as our results show that engagement in motor imagery critically depends on the used number of axes of rotation of the stimulus set. PMID:20376435

  5. Kinematical modeling of the Earth rotation, focusing on the Oppolzer terms in a rigid Earth and the Oppolzer-like terms in an elastic Earth

    NASA Astrophysics Data System (ADS)

    Kubo, Yoshio

    2011-06-01

    Under perturbations from outer bodies, the Earth experiences changes of its angular momentum axis, figure axis and rotational axis. In the theory of the rigid Earth, in addition to the precession and nutation of the angular momentum axis given by the Poisson terms, both the figure axis and the rotational axis suffer forced deviation from the angular momentum axis. This deviation is expressed by the so-called Oppolzer terms describing separation of the averaged figure axis, called CIP (Celestial Intermediate Pole) or CEP (Celestial Ephemeris Pole), and the mathematically defined rotational axis, from the angular momentum axis. The CIP is the rotational axis in a frame subject to both precession and nutation, while the mathematical rotational axis is that in the inertial (non-rotating) frame. We investigate, kinematically, the origin of the separation between these two axes - both for the rigid Earth and an elastic Earth. In the case of an elastic Earth perturbed by the same outer bodies, there appear further deviations of the figure and rotational axes from the angular momentum axis. These deviations, though similar to the Oppolzer terms in the rigid Earth, are produced by quite a different physical mechanism. Analysing this mechanism, we derive an expression for the Oppolzer-like terms in an elastic Earth. From this expression we demonstrate that, under a certain approximation (in neglect of the motion of the perturbing outer bodies), the sum of the direct and convective perturbations of the spin axis coincides with the direct perturbation of the figure axis. This equality, which is approximate, gets violated when the motion of the outer bodies is taken into account.

  6. Rotational Doppler effect in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

  7. Three-axis atomic magnetometer based on spin precession modulation

    SciTech Connect

    Huang, H. C.; Dong, H. F. Hu, X. Y.; Chen, L.; Gao, Y.

    2015-11-02

    We demonstrate a three-axis atomic magnetometer with one intensity-modulated pump beam and one orthogonal probe beam. The main field component is measured using the resonance of the pumping light, while the transverse field components are measured simultaneously using the optical rotation of the probe beam modulated by the spin precession. It is an all-optical magnetometer without using any modulation field or radio frequency field. Magnetic field sensitivity of 0.8 pT/Hz{sup 1∕2} is achieved under a bias field of 2 μT.

  8. Stability Analysis for Constrained Principal Axis Slew Maneuvers

    NASA Technical Reports Server (NTRS)

    Seywald, Hans; Lim, Kyong B.; Anthony, Tobin C.

    1996-01-01

    This paper addresses the problem of reorienting a rigid spacecraft from arbitrary initial conditions to prescribed final conditions with zero angular velocity. The control law analyzed is based on quaternion feedback and leaves the user to choose two gains as functions of position, angular rate, and time. For arbitrary initial states, conditions on the controller gains are identified that guarantee global asymptotic stability. For the special case of rest-to-rest reorientations, the control law reduces to earlier results involving a principal axis rotation. The paper also addresses slew rate constraints, both, in terms of the two and infinity norms.

  9. On the Structure Orientation in Rotating and Sheared Homogeneous Turbulence

    NASA Astrophysics Data System (ADS)

    Aguirre, Joylene C.; Moreau, Adam F.; Jacobitz, Frank G.

    2016-11-01

    The results of direct numerical simulations are used to study the effect of rotation on the orientation of structures and the evolution of the turbulent kinetic energy in homogeneous sheared turbulence. Shear flows without rotation, with moderate rotation, and with strong rotation are considered and the rotation axis is either parallel or anti-parallel to the mean flow vorticity. In the case of moderate rotation, an anti-parallel configuration increases the growth rate of the turbulent kinetic energy, while a parallel configuration decreases the growth rate as compared to the flow without rotation. The orientation of turbulent structures present in the flows are characterized using the three-dimensional, two-point autocorrelation coefficient of velocity magnitude and vorticity magnitude. An ellipsoid is fitted to the surface defined by a constant autocorrelation coefficient value and the major and minor axes are used to determine the inclination angle of flow structures in the plane of shear. It was found that the inclination angle assumes a maximum value for the anti-parallel configuration with moderate rotation. Again, the inclination angle for the parallel configuration with moderate rotation is reduced as compared to the case without rotation. The smallest inclination angles are found for the strongly rotating cases. Hence, the inclination angle is directly related to the growth rate of the turbulent kinetic energy. University of San Diego Shiley-Marcos School of Engineering and McNair Scholars.

  10. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    NASA Astrophysics Data System (ADS)

    Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Wen, Zhuoman; Liu, Shaojin; Cai, Sheng; Li, Jianrong

    2015-10-01

    This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendicular to the rotating shaft. The reversal measurement method is applied to decrease the effect of inclinometer drifts caused by temperature, to eliminate inclinometer and rotating shaft mechanical error and inclinometer systematic error to attain high measurement accuracy. The uncertainty estimation shows that the accuracy of rotating shaft tilt angle measurement depends mainly on the inclinometer uncertainty and its uncertainty is almost the same as the inclinometer uncertainty in the simulation. The experimental results indicate that measurement time is 4 seconds; the range of rotating shaft tilt angle is 0.002° and its standard deviation is 0.0006° using NS-5/P2 inclinometer, whose precision and resolution are ±0.01° and 0.0005°, respectively.

  11. Galvano-rotational effect induced by electroweak interactions in pulsars

    SciTech Connect

    Dvornikov, Maxim

    2015-05-21

    We study electroweakly interacting particles in rotating matter. The existence of the electric current along the axis of the matter rotation is predicted in this system. This new galvano-rotational effect is caused by the parity violating interaction between massless charged particles in the rotating matter. We start with the exact solution of the Dirac equation for a fermion involved in the electroweak interaction in the rotating frame. This equation includes the noninertial effects. Then, using the obtained solution, we derive the induced electric current which turns out to flow along the rotation axis. We study the possibility of the appearance of the galvano-rotational effect in dense matter of compact astrophysical objects. The particular example of neutron and hypothetical quark stars is discussed. It is shown that, using this effect, one can expect the generation of toroidal magnetic fields comparable with poloidal ones in old millisecond pulsars. We also briefly discuss the generation of the magnetic helicity in these stars. Finally we analyze the possibility to apply the galvano-rotational effect for the description of the asymmetric neutrino emission from a neutron star to explain pulsars kicks.

  12. Galvano-rotational effect induced by electroweak interactions in pulsars

    SciTech Connect

    Dvornikov, Maxim

    2015-05-01

    We study electroweakly interacting particles in rotating matter. The existence of the electric current along the axis of the matter rotation is predicted in this system. This new galvano-rotational effect is caused by the parity violating interaction between massless charged particles in the rotating matter. We start with the exact solution of the Dirac equation for a fermion involved in the electroweak interaction in the rotating frame. This equation includes the noninertial effects. Then, using the obtained solution, we derive the induced electric current which turns out to flow along the rotation axis. We study the possibility of the appearance of the galvano-rotational effect in dense matter of compact astrophysical objects. The particular example of neutron and hypothetical quark stars is discussed. It is shown that, using this effect, one can expect the generation of toroidal magnetic fields comparable with poloidal ones in old millisecond pulsars. We also briefly discuss the generation of the magnetic helicity in these stars. Finally we analyze the possibility to apply the galvano-rotational effect for the description of the asymmetric neutrino emission from a neutron star to explain pulsars kicks.

  13. Two-dimensional discrete solitons in rotating lattices.

    PubMed

    Cuevas, Jesús; Malomed, Boris A; Kevrekidis, P G

    2007-10-01

    We introduce a two-dimensional discrete nonlinear Schrödinger (DNLS) equation with self-attractive cubic nonlinearity in a rotating reference frame. The model applies to a Bose-Einstein condensate stirred by a rotating strong optical lattice, or light propagation in a twisted bundle of nonlinear fibers. Two types of localized states are constructed: off-axis fundamental solitons (FSs), placed at distance R from the rotation pivot, and on-axis (R=0) vortex solitons (VSs), with vorticities S=1 and 2 . At a fixed value of rotation frequency Omega , a stability interval for the FSs is found in terms of the lattice coupling constant C , 0rotation. On the contrary, VSs with S=2 , that are known to be unstable in the standard DNLS equation, with Omega=0 , are stabilized by the rotation in region 0axis solitons are considered too, their stability regions being weakly affected by Omega not equal 0 .

  14. A clinical study of the rotational alignment of the femoral component in total knee arthroplasty

    PubMed Central

    Ding, Liangjia; Liu, Xiaomin; Liu, Changlu; Liu, Yingli

    2015-01-01

    [Purpose] The reasons for femorotibial rotational malalignment after total knee arthroplasty (TKA) were analyzed to provide evidence for clinical knee joint surgery and to reduce complications. [Subjects and Methods] Ninety knees of 60 patients were selected and randomly divided into two groups (n=30). For one group, rotational alignment of the femoral component was determined by the transepicondylar axis and TKA was performed. For the other group, rotational alignment of the femoral component was conducted through 3° external rotation of the posterior femoral condyles. Knee joint specimens were operated with TKA and various biomechanical indices were measured. [Results] The femoral epicondylar axis was a constant, reliable reference for femoral component rotational alignment. When the femoral component was rotated by 0° versus the epicondylar axis, the peak contact pressure on the patellofemoral joint was optimal. When the femoral component was arranged in parallel with Whiteside’s line, the peak contact pressure on the patellofemoral joint varied largely. The patellofemoral contact areas of the two groups were similar. [Conclusion] Axial rotational alignment of the femoral component influenced the contact pressure of patellofemoral joints in TKA more significantly than external rotation of the femoral condyles. It is more reliable to use the femoral epicondylar axis as the reference for the rotational alignment of the femoral component. PMID:26311929

  15. Shear rotation numbers

    NASA Astrophysics Data System (ADS)

    Doeff, E.; Misiurewicz, M.

    1997-11-01

    This paper presents results on rotation numbers for orientation-preserving torus homeomorphisms homotopic to a Dehn twist. Rotation numbers and the rotation set for such homeomorphisms have been defined and initially investigated by the first author in a previous paper. Here we prove that each rotation number 0951-7715/10/6/017/img5 in the interior of the rotation set is realized by some compact invariant set, and that there is an ergodic measure on that set with mean rotation number 0951-7715/10/6/017/img5. It is also proved that the function which assigns its rotation set to such a homeomorphism is continuous. Finally, a counterexample is presented that shows that rational extremal points of the shear rotation set do not necessarily correspond to any periodic orbits.

  16. Power Harvesting from Rotation?

    ERIC Educational Resources Information Center

    Chicone, Carmen; Feng, Z. C.

    2008-01-01

    We show the impossibility of harvesting power from rotational motions by devices attached to the rotating object. The presentation is suitable for students who have studied Lagrangian mechanics. (Contains 2 figures.)

  17. Rotator cuff exercises

    MedlinePlus

    ... to these tendons may result in: Rotator cuff tendinitis, which is irritation and swelling of these tendons ... Brien MJ, Leggin BG, Williams GR. Rotator cuff tendinopathies and tears: surgery and therapy. In: Skirven TM, ...

  18. Eye formation in rotating convection

    NASA Astrophysics Data System (ADS)

    Oruba, L.; Davidson, P. A.; Dormy, E.

    2017-02-01

    We consider rotating convection in a shallow, cylindrical domain. We examine the conditions under which the resulting vortex develops an eye at its core; that is, a region where the poloidal flow reverses and the angular momentum is low. For simplicity, we restrict ourselves to steady, axisymmetric flows in a Boussinesq fluid. Our numerical experiments show that, in such systems, an eye forms as a passive response to the development of a so-called eyewall, a conical annulus of intense, negative azimuthal vorticity that can form near the axis and separates the eye from the primary vortex. We also observe that the vorticity in the eyewall comes from the lower boundary layer, and relies on the fact the poloidal flow strips negative vorticity out of the boundary layer and carries it up into the fluid above as it turns upward near the axis. This process is effective only if the Reynolds number is sufficiently high for the advection of vorticity to dominate over diffusion. Finally we observe that, in the vicinity of the eye and the eyewall, the buoyancy and Coriolis forces are negligible, and so although these forces are crucial to driving and shaping the primary vortex, they play no direct role in eye formation in a Boussinesq fluid.

  19. Control system for a vertical-axis windmill

    DOEpatents

    Brulle, R.V.

    1981-09-03

    A vertical-axis windmill having a rotating structure is provided with a series of articulated vertical blades whose positions are controlled to maintain a constant RPM for the rotating structure, when wind speed is sufficient. A microprocessor controller is used to process information on wind speed, wind direction and RPM of the rotating structure to develop an electrical signal for establishing blade position. The preferred embodiment of the invention, when connected to a utility grid, is designed to generate 40 kilowatts of power when exposed to a 20 mile per hour wind. The control system for the windmill includes electrical blade actuators that modulate the blades of the rotating structure. Blade modulation controls the blade angle of attack, which in turn controls the RPM of the rotor. In the preferred embodiment, the microprocessor controller provides the operation logic and control functions. A wind speed sensor provides inputs to start or stop the windmill, and a wind direction sensor is used to keep the blade flip region at 90 and 270/sup 0/ to the wind. The control system is designed to maintain constant rotor RPM when wind speed is between 10 and 40 miles per hour.

  20. The Radical Axis: A Motion Study

    ERIC Educational Resources Information Center

    McGivney, Ray; McKim, Jim

    2006-01-01

    Interesting problems sometimes have surprising sources. In this paper we take an innocent looking problem from a calculus book and rediscover the radical axis of classical geometry. For intersecting circles the radical axis is the line through the two points of intersection. For nonintersecting, nonconcentric circles, the radical axis still…

  1. Numerical studies of Siberian snakes and spin rotators for RHIC

    SciTech Connect

    Luccio, A.

    1995-04-17

    For the program of polarized protons in RHIC, two Siberian snakes and four spin rotators per ring will be used. The Snakes will produce a complete spin flip. Spin Rotators, in pairs, will rotate the spin from the vertical direction to the horizontal plane at a given insertion, and back to the vertical after the insertion. Snakes, 180{degrees} apart and with their axis of spin precession at 90{degrees} to each other, are an effective means to avoid depolarization of the proton beam in traversing resonances. Classical snakes and rotators are made with magnetic solenoids or with a sequence of magnetic dipoles with fields alternately directed in the radial and vertical direction. Another possibility is to use helical magnets, essentially twisted dipoles, in which the field, transverse the axis of the magnet, continuously rotates as the particles proceed along it. After some comparative studies, the authors decided to adopt for RHIC an elegant solution with four helical magnets both for the snakes and the rotators proposed by Shatunov and Ptitsin. In order to simplify the construction of the magnets and to minimize cost, four identical super conducting helical modules will be used for each device. Snakes will be built with four right-handed helices. Spin rotators with two right-handed and two left-handed helices. The maximum field will be limited to 4 Tesla. While small bore helical undulators have been built for free electron lasers, large super conducting helical magnets have not been built yet. In spite of this difficulty, this choice is dictated by some distinctive advantages of helical over more conventional transverse snakes/rotators: (i) the devices are modular, they can be built with arrangements of identical modules, (ii) the maximum orbit excursion in the magnet is smaller, (iii) orbit excursion is independent from the separation between adjacent magnets, (iv) they allow an easier control of the spin rotation and the orientation of the spin precession axis.

  2. Triple axis and spins spectrometers

    SciTech Connect

    Trevino, S.F.

    1993-01-01

    In the paper are described the triple axis and spin polarized inelastic neutron scattering (SPINS) spectrometers which are installed at the NIST Cold Neutron Research Facility (CNRF). The general principle of operation of these two instruments is described in sufficient detail to allow the reader to make an informed decision as to their usefulness for his needs. However, it is the intention of the staff at the CNRF to provide the expert resources for their efficient use in any given situation. Thus, the work is not intended as a user manual but rather as a guide into the range of applicability of the two instruments.

  3. Rotations with Rodrigues' Vector

    ERIC Educational Resources Information Center

    Pina, E.

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

  4. Model of a rotating magnetic cloud

    NASA Technical Reports Server (NTRS)

    Farrugia, C. J.; Osherovich, V. A.; Burlaga, L. F.

    1992-01-01

    The possibility that magnetic clouds rotate while they propagate antisunward was investigated. Magnetic clouds are modeled as magnetic flux ropes which rotate rigidly about the axis of symmetry. An ideal magnetohydrodynamic model, in which the evolution of the magnetic structure is related to the time evolution of the angular frequency, is developed. A class of 'separable' magnetic fields is employed to reduce the problem to a nonlinear ordinary differential equation for the evolution function, and it is solved numerically. The corresponding effective potential gives rise to two modes of evolution--expansion and oscillation--depending on the energy and on the value of a dimensionless parameter, k. Parameter k depends on the gas pressure, the ratio of the magnetic field components, and the frequency of rotation. There is a critical value of k, k(sub c), above which the oscillatory regime disappears and the flux rope invariably expands, regardless of the energy. Below k(sub c) the energy determines whether the configuration is confined or unbounded. Rotation always helps expansion by lowering the potential barrier. A data example was studied and features which are interpreted as signatures of rotation are presented. The angular speed is comparable to the Alfven speed, and the core of the rotating cloud completes on average one full revolution every three days at 1 AU. The parameter k is calculated from observations, and it is found to be close to, but below, critical. Only three out of the nine clouds examined showed signatures of rotation. Theoretical analysis suggests that close to the Sun rotation effects may play a more important role in the evolution of magnetic clouds than 1 AU.

  5. Rotating Rayleigh-Benard convection: The Kueppers-Lortz transition

    SciTech Connect

    Zhong, F.; Ecke, R.; Steinberg, V.

    1990-01-01

    Rayleigh-Benard convection with rotation about a vertical axis is investigated for small dimensionless rotation rates 0 < {Omega} < 50. The convection cell is cylindrical with aspect ratio {Gamma} = 10 and the convecting fluid is water with a Prandtl number of 6.8 at T = 23.8C. Comparisons are made between experimental data and linear stability theory for the onset Rayleigh number and for the wave number dependence of the convective pattern. The nonlinear Kueppers-Lortz transition is found to occur significantly below the theoretically expected rotation rate {Omega}{sub c} and to be nucleated by defects created at the lateral cell walls. 20 refs., 10 figs.

  6. Probe-rotating atomic force microscopy for determining material properties

    SciTech Connect

    Lee, Sang Heon

    2014-03-15

    In this paper, we propose a probe-rotating atomic force microscope that enables scan in an arbitrary direction in the contact imaging mode, which is difficult to achieve using a conventional atomic force microscope owing to the orientation-dependent probe and the inability to rotate the probe head. To enable rotation of the probe about its vertical axis, we employed a compact and light probe head, the sensor of which is made of an optical disk drive pickup unit. Our proposed mechanical configuration, operating principle, and control system enables axial and lateral scan in various directions.

  7. Stress and the HPA Axis

    PubMed Central

    Stephens, Mary Ann C.; Wand, Gary

    2012-01-01

    Stress has long been suggested to be an important correlate of uncontrolled drinking and relapse. An important hormonal response system to stress—the hypothalamic–pituitary–adrenal (HPA) axis—may be involved in this process, particularly stress hormones known as glucocorticoids and primarily cortisol. The actions of this hormone system normally are tightly regulated to ensure that the body can respond quickly to stressful events and return to a normal state just as rapidly. The main determinants of HPA axis activity are genetic background, early-life environment, and current life stress. Alterations in HPA axis regulation are associated with problematic alcohol use and dependence; however, the nature of this dysregulation appears to vary with respect to stage of alcohol dependence. Much of this research has focused specifically on the role of cortisol in the risk for, development of, and relapse to chronic alcohol use. These studies found that cortisol can interact with the brain’s reward system, which may contribute to alcohol’s reinforcing effects. Cortisol also can influence a person’s cognitive processes, promoting habit-based learning, which may contribute to habit formation and risk of relapse. Finally, cortisol levels during abstinence may be useful clinical indicators of relapse vulnerability in alcohol-dependent people. PMID:23584113

  8. Gut microbiota-bone axis.

    PubMed

    Villa, Christopher R; Ward, Wendy E; Comelli, Elena M

    2017-05-24

    The gut microbiota (GM) is an important regulator of body homeostasis, including intestinal and extra-intestinal effects. This review focuses on the GM-bone axis, which we define as the effect of the gut-associated microbial community or the molecules they synthesize, on bone health. While research in this field is limited, findings from preclinical studies support that gut microbes positively impact bone mineral density and strength parameters. Moreover, administration of beneficial bacteria (probiotics) in preclinical models has demonstrated higher bone mineralization and greater bone strength. The preferential bacterial genus that has shown these beneficial effects in bone is Lactobacillus and thus lactobacilli are among the best candidates for future clinical intervention trials. However, their effectiveness is dependent on stage of development, as early life constitutes an important time for impacting bone health, perhaps via modulation of the GM. In addition, sex-specific difference also impacts the efficacy of the probiotics. Although auspicious, many questions regarding the GM-bone axis require consideration of potential mechanisms; sex-specific efficacy; effective dose of probiotics; and timing and duration of treatment.

  9. Fluid forces on rotating centrifugal impeller with whirling motion

    NASA Technical Reports Server (NTRS)

    Shoji, H.; Ohashi, H.

    1980-01-01

    Fluid forces on a centrifugal impeller, whose rotating axis whirls with a constant speed, were calculated by using unsteady potential theory. Calculations were performed for various values of whirl speed, number of impeller blades and angle of blades. Specific examples as well as significant results are given.

  10. SEAL FOR ROTATING SHAFT

    DOEpatents

    Coffman, R.T.

    1957-12-10

    A seal is described for a rotatable shaft that must highly effective when the shaft is not rotating but may be less effective while the shaft is rotating. Weights distributed about a sealing disk secured to the shaft press the sealing disk against a tubular section into which the shiilt extends, and whem the shaft rotates, the centrifugal forces on the weights relieve the pressurc of the sealing disk against the tubular section. This action has the very desirible result of minimizing the wear of the rotating disk due to contact with the tubular section, while affording maximum sealing action when it is needed.

  11. Visualizing molecular unidirectional rotation

    NASA Astrophysics Data System (ADS)

    Lin, Kang; Song, Qiying; Gong, Xiaochun; Ji, Qinying; Pan, Haifeng; Ding, Jingxin; Zeng, Heping; Wu, Jian

    2015-07-01

    We directly visualize the spatiotemporal evolution of a unidirectional rotating molecular rotational wave packet. Excited by two time-delayed polarization-skewed ultrashort laser pulses, the cigar- or disk-shaped rotational wave packet is impulsively kicked to unidirectionally rotate as a quantum rotor which afterwards disperses and exhibits field-free revivals. The rich dynamics can be coherently controlled by varying the timing or polarization of the excitation laser pulses. The numerical simulations very well reproduce the experimental observations and intuitively revivify the thoroughgoing evolution of the molecular rotational wave packet of unidirectional spin.

  12. Optical rotation compensation for a holographic 3D display with a 360 degree horizontal viewing zone.

    PubMed

    Sando, Yusuke; Barada, Daisuke; Yatagai, Toyohiko

    2016-10-20

    A method for a continuous optical rotation compensation in a time-division-based holographic three-dimensional (3D) display with a rotating mirror is presented. Since the coordinate system of wavefronts after the mirror reflection rotates about the optical axis along with the rotation angle, compensation or cancellation is absolutely necessary to fix the reconstructed 3D object. In this study, we address this problem by introducing an optical image rotator based on a right-angle prism that rotates synchronously with the rotating mirror. The optical and continuous compensation reduces the occurrence of duplicate images, which leads to the improvement of the quality of reconstructed images. The effect of the optical rotation compensation is experimentally verified and a demonstration of holographic 3D display with the optical rotation compensation is presented.

  13. Predictors of human rotation.

    PubMed

    Stochl, Jan; Croudace, Tim

    2013-01-01

    Why some humans prefer to rotate clockwise rather than anticlockwise is not well understood. This study aims to identify the predictors of the preferred rotation direction in humans. The variables hypothesised to influence rotation preference include handedness, footedness, sex, brain hemisphere lateralisation, and the Coriolis effect (which results from geospatial location on the Earth). An online questionnaire allowed us to analyse data from 1526 respondents in 97 countries. Factor analysis showed that the direction of rotation should be studied separately for local and global movements. Handedness, footedness, and the item hypothesised to measure brain hemisphere lateralisation are predictors of rotation direction for both global and local movements. Sex is a predictor of the direction of global rotation movements but not local ones, and both sexes tend to rotate clockwise. Geospatial location does not predict the preferred direction of rotation. Our study confirms previous findings concerning the influence of handedness, footedness, and sex on human rotation; our study also provides new insight into the underlying structure of human rotation movements and excludes the Coriolis effect as a predictor of rotation.

  14. Stability of Steady-State Motion of an Isolated System Consisting of a Rotating Body and Two Pendulums

    NASA Astrophysics Data System (ADS)

    Filimonikhin, G. B.; Filimonikhina, I. I.; Pirogov, V. V.

    2014-07-01

    An isolated mechanical system consisting of a rotating body and two pendulums fit on its longitudinal axis is studied. This system models how pendulum, ball, or fluid (ring) dampers decrease or increase the nutation angle of a spin-stabilized artificial satellite. The conditions of origin, existence, and cessation of the steady-state motion of the system, depending on its parameters, and the stability conditions for the primary motion (the body rotates about the longitudinal axis and the pendulums lie on the same line) and secondary motions (the body does not rotate around the longitudinal axis) are established. The residual nutation angle is estimated

  15. Rotational polarities of sudden impulses in the magnetotail lobe

    NASA Technical Reports Server (NTRS)

    Kawano, H.; Yamamoto, T.; Kokubun, S.; Lepping, R. P.

    1992-01-01

    A sudden impulse (SI) is a sudden change in the magnetic field strength which is caused by a change in the solar wind pressure and is observed throughout the magnetosphere. In this report we have examined the rotations of the magnetic field vectors at times of SIs in the magnetotail lobe, by using IMP 6, 7, and 8 magnetometer data. The following properties have been found: (1) at the time of SI the arrowhead of the magnetic vector tends to rotate in one plane; (2) the plane of rotation tends to include the unperturbed magnetic field vector; (3) the plane of rotation tends to be aligned with the radial direction from the magnetotail axis; and (4) the magnetic vectors have a particular rotational polarity: when the plane of rotation is viewed so that the Sun is to the right of the viewed plane and the magnetotail axis is to the bottom, the arrowhead of the vector tends to rotate counterclockwise in this plane. These magnetic vector properties are consistent with those expected when part of an increase in solar wind lateral pressure squeezes the magnetotail axisymmetrically while moving tailward.

  16. COUNTER-ROTATION IN RELATIVISTIC MAGNETOHYDRODYNAMIC JETS

    SciTech Connect

    Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.; Matsakos, T.; Lima, J. J. G.

    2014-06-10

    Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. showed that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Motion signatures that are transverse to the jet axis, in two opposite directions, have recently been measured in M87. One possible interpretation of this motion is that of counter-rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases: if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of a relativistic magnetohydrodynamic jet simulation.

  17. Seasonal variations in the rotation of Mars

    NASA Astrophysics Data System (ADS)

    Le Maistre, Sebastien; Karatekin, Özgür; Rosenblatt, Pascal; Dehant, Veronique

    2010-05-01

    Seasonal variations in the rotation of Mars are primarily driven by its atmosphere and involve an exchange of mass and/or momentum between the atmosphere and the solid body. In this study, we investigate the determination of seasonal variations of the Length-of-Day (LOD) and of the polar motion (PM). PM corresponds to the motion of the rotation axis in a reference frame tied to the planet. Mars' polar motion contains seasonal effects of the atmosphere as well as a resonance with a rotational normal mode of the planet, the Chandler Wobble (CW), which is the natural wobbling of an oblate planet that does not rotate around its principal moment of inertia. The period and damping of this mode are very interesting since they are linked to the interior structure of the planet. LOD variations are deviations from the uniform rotation speed of the planet. They are mostly related to the dynamics of the geophysical fluids of the system such as the core and atmosphere of Mars. The amplitudes of the PM and LOD variations calculated from the outputs of the General Circulation Models will be compared with the observed amplitudes from the tracking of Martian landers and orbiters. The improvements with the future missions and their implications for the Martian atmospheric dynamics and interior structure will be discussed.

  18. The development and testing of a novel cross axis wind turbine

    NASA Astrophysics Data System (ADS)

    Chong, W. T.; Muzammil, W. K.; Gwani, M.; Wong, K. H.; Fazlizan, A.; Wang, C. T.; Poh, S. C.

    2016-06-01

    A novel cross axis wind turbine (CAWT) which comprises of a cross axis blades arrangement was presented and investigated experimentally. The CAWT is a new type of wind turbine that extracts wind energy from airflow coming from the horizontal and vertical directions. The wind turbine consists of three vertical blades and six horizontal blades arranged in a cross axis orientation. Hubs in the middle of the CAWT link the horizontal and vertical blades through connectors to form the CAWT. The study used a 45° deflector to guide the oncoming airflow upward (vertical wind direction). The results from the study showed that the CAWT produced significant improvements in power output and rotational speed performance compared to a conventional straight-bladed vertical axis wind turbine (VAWT).

  19. Rapid fabrication of miniature lens arrays by four-axis single point diamond machining

    PubMed Central

    McCall, Brian; Tkaczyk, Tomasz S.

    2013-01-01

    A novel method for fabricating lens arrays and other non-rotationally symmetric free-form optics is presented. This is a diamond machining technique using 4 controlled axes of motion – X, Y, Z, and C. As in 3-axis diamond micro-milling, a diamond ball endmill is mounted to the work spindle of a 4-axis ultra-precision computer numerical control (CNC) machine. Unlike 3-axis micro-milling, the C-axis is used to hold the cutting edge of the tool in contact with the lens surface for the entire cut. This allows the feed rates to be doubled compared to the current state of the art of micro-milling while producing an optically smooth surface with very low surface form error and exceptionally low radius error. PMID:23481813

  20. Blade pitch optimization methods for vertical-axis wind turbines

    NASA Astrophysics Data System (ADS)

    Kozak, Peter

    Vertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates safety and noise concerns, potentially allowing for installation closer to populated and ecologically sensitive areas. While VAWTs do offer significant operational advantages, development has been hampered by the difficulty of modeling the aerodynamics involved, further complicated by their rotating geometry. This thesis presents results from a simulation of a baseline VAWT computed using Star-CCM+, a commercial finite-volume (FVM) code. VAWT aerodynamics are shown to be dominated at low tip-speed ratios by dynamic stall phenomena and at high tip-speed ratios by wake-blade interactions. Several optimization techniques have been developed for the adjustment of blade pitch based on finite-volume simulations and streamtube models. The effectiveness of the optimization procedure is evaluated and the basic architecture for a feedback control system is proposed. Implementation of variable blade pitch is shown to increase a baseline turbine's power output between 40%-100%, depending on the optimization technique, improving the turbine's competitiveness when compared with a commercially-available horizontal-axis turbine.

  1. Millimetre Wave with Rotational Orbital Angular Momentum

    PubMed Central

    Zhang, Chao; Ma, Lu

    2016-01-01

    Orbital angular momentum (OAM) has been widely studied in fibre and short-range communications. The implementation of millimetre waves with OAM is expected to increase the communication capacity. Most experiments demonstrate the distinction of OAM modes by receiving all of the energy in the surface vertical to the radiation axis in space. However, the reception of OAM is difficult in free space due to the non-zero beam angle and divergence of energy. The reception of OAM in the space domain in a manner similar to that in optical fibres (i.e., receiving all of the energy rings vertical to the radiation axis) is impractical, especially for long-distance transmission. Here, we fabricate a prototype of the antenna and demonstrate that rather than in the space domain, the OAM can be well received in the time domain via a single antenna by rotating the OAM wave at the transmitter, i.e., the radio wave with rotational OAM. The phase and frequency measured in the experiment reveal that for different OAM modes, the received signals act as a commonly used orthogonal frequency division multiplexing (OFDM) signal in the time domain. This phase rotation has promising prospects for use in the practical reception of different OAMs of millimetre waves in long-distance transmission. PMID:27596746

  2. Millimetre Wave with Rotational Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Ma, Lu

    2016-09-01

    Orbital angular momentum (OAM) has been widely studied in fibre and short-range communications. The implementation of millimetre waves with OAM is expected to increase the communication capacity. Most experiments demonstrate the distinction of OAM modes by receiving all of the energy in the surface vertical to the radiation axis in space. However, the reception of OAM is difficult in free space due to the non-zero beam angle and divergence of energy. The reception of OAM in the space domain in a manner similar to that in optical fibres (i.e., receiving all of the energy rings vertical to the radiation axis) is impractical, especially for long-distance transmission. Here, we fabricate a prototype of the antenna and demonstrate that rather than in the space domain, the OAM can be well received in the time domain via a single antenna by rotating the OAM wave at the transmitter, i.e., the radio wave with rotational OAM. The phase and frequency measured in the experiment reveal that for different OAM modes, the received signals act as a commonly used orthogonal frequency division multiplexing (OFDM) signal in the time domain. This phase rotation has promising prospects for use in the practical reception of different OAMs of millimetre waves in long-distance transmission.

  3. Numerical simulation of negative Magnus force on a rotating sphere

    NASA Astrophysics Data System (ADS)

    Muto, Masaya; Tsubokura, Makoto; Oshima, Nobuyuki

    2010-11-01

    Flow characteristics and fluid force on a sphere rotating along with axis perpendicular to mean air flow were investigated using Large Eddy Simulation at two different Reynolds numbers of 10,000 and 200,000. As a result of simulation, opposite flow characteristics around the sphere and displacement of the separation point were visualized depending on the Reynolds number even though the sphere rotates at the same rotation speed according to the Reynolds number. When Reynolds number is 10,000, flow characteristics agree with the flow field explained in the Magnus effect. However sphere rotates at the same rotation speed while increasing Reynolds number to 200,000, separation point moves in opposite direction and wake appears in the different direction. The reason of the negative Magnus force was discussed in terms of the boundary layer transition on the surface.

  4. Studies of rotating liquid floating zones on Skylab IV

    NASA Technical Reports Server (NTRS)

    Carruthers, J. R.; Gibson, E. G.; Klett, M. G.; Facemire, B. R.

    1975-01-01

    Liquid zones of water, soap solution and soap foam were deployed between two aligned circular disks which were free to rotate about the zone axis in the microgravity environment of Skylab IV. Such a configuration is of interest in the containerless handling of melts for possible future space processing crystal growth experiments. Three basic types of zone surface deformation and instability were observed for these rotational conditions; axisymmetric shape changes under single disk rotation, nonaxisymmetric, whirling, C-modes for long zones with equal rotation of both disks, and capillary wave phenomena for short zones with equal rotation of both disks. The sources of these instabilities and the conditions promoting them are analyzed in detail from video tape recordings of the Skylab experiments.

  5. Rotating Vessels for Growing Protein Crystals

    NASA Technical Reports Server (NTRS)

    Cottingham, Paul

    2005-01-01

    Rotating vessels have been proposed as means of growing larger, more nearly uniform protein crystals than would otherwise be possible in the presence of normal Earth gravitation. Heretofore, nonrotating vessels have been used. It is difficult to grow high-quality protein crystals in the terrestrial gravitational field because of convection plumes created by the interaction between gravitation and density gradients in protein-solution depletion layers around growing crystals. The density gradients and the associated convection plumes cause the surfaces of growing crystals to be exposed to nonuniform solution densities, thereby causing the crystals to form in irregular shapes. The microgravitational environment of outer space has been utilized to eliminate gravitation-induced convection, but this approach is generally not favorable because of the high cost and limited availability of space flight. The use of a rotating vessel according to the proposal is intended to ameliorate the effects of gravitation and the resultant convection, relative to the corresponding effects in a non-rotating vessel. The rotation would exert an averaging effect over time, distributing the convective force on the depletion layer. Therefore, the depletion layer would be more nearly uniform and, as a result, the growing crystal would be more nearly perfect. The proposal admits of variations (see figure), including the following: The growing crystal could be rotated about its own central axis or an external axis. The crystal-growth vessel could be of any of various shapes, including cylindrical, hemispherical, conical, and combinations thereof. The crystal-growth vessel could be suspended in a viscous fluid in an outer vessel to isolate the growing crystal from both ambient vibrations and vibrations induced by a mechanism that drives the rotation. The rotation could be coupled to the crystal-growth vessel by viscous or magnetic means. The crystal-growth vessel could be supported within the

  6. Tumbling asteroid rotation with the YORP torque and inelastic energy dissipation

    NASA Astrophysics Data System (ADS)

    Breiter, S.; Murawiecka, M.

    2015-05-01

    The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect and rotational energy dissipation due to inelastic deformations are two key mechanisms affecting rotation of tumbling asteroids in long term. Each of the effects used to be discussed separately. We present the first results concerning a simulation of their joint action. Asteroids (3103) Eger and (99942) Apophis, as well as their scaled variants, are used as test bodies. Plugging in the dissipation destroys limit cycles of the pure YORP, but creates a new asymptotic state of stationary tumbling with a fixed rotation period. The present model does not contradict finding Eger in the principal axis rotation. For Apophis, the model suggests that its current rotation state should be relatively young. In general, the fraction of initial conditions leading to the principal axis rotation is too small, compared to the actual data. The model requires a stronger energy dissipation and weaker YORP components in the nutation angle and obliquity.

  7. Cylindrical rotating triboelectric nanogenerator.

    PubMed

    Bai, Peng; Zhu, Guang; Liu, Ying; Chen, Jun; Jing, Qingshen; Yang, Weiqing; Ma, Jusheng; Zhang, Gong; Wang, Zhong Lin

    2013-07-23

    We demonstrate a cylindrical rotating triboelectric nanogenerator (TENG) based on sliding electrification for harvesting mechanical energy from rotational motion. The rotating TENG is based on a core-shell structure that is made of distinctly different triboelectric materials with alternative strip structures on the surface. The charge transfer is strengthened with the formation of polymer nanoparticles on surfaces. During coaxial rotation, a contact-induced electrification and the relative sliding between the contact surfaces of the core and the shell result in an "in-plane" lateral polarization, which drives the flow of electrons in the external load. A power density of 36.9 W/m(2) (short-circuit current of 90 μA and open-circuit voltage of 410 V) has been achieved by a rotating TENG with 8 strip units at a linear rotational velocity of 1.33 m/s (a rotation rate of 1000 r/min). The output can be further enhanced by integrating more strip units and/or applying larger linear rotational velocity. This rotating TENG can be used as a direct power source to drive small electronics, such as LED bulbs. This study proves the possibility to harvest mechanical energy by TENGs from rotational motion, demonstrating its potential for harvesting the flow energy of air or water for applications such as self-powered environmental sensors and wildlife tracking devices.

  8. Coherent Structures and Extreme Events in Rotating Multiphase Turbulent Flows

    NASA Astrophysics Data System (ADS)

    Biferale, L.; Bonaccorso, F.; Mazzitelli, I. M.; van Hinsberg, M. A. T.; Lanotte, A. S.; Musacchio, S.; Perlekar, P.; Toschi, F.

    2016-10-01

    By using direct numerical simulations (DNS) at unprecedented resolution, we study turbulence under rotation in the presence of simultaneous direct and inverse cascades. The accumulation of energy at large scale leads to the formation of vertical coherent regions with high vorticity oriented along the rotation axis. By seeding the flow with millions of inertial particles, we quantify—for the first time—the effects of those coherent vertical structures on the preferential concentration of light and heavy particles. Furthermore, we quantitatively show that extreme fluctuations, leading to deviations from a normal-distributed statistics, result from the entangled interaction of the vertical structures with the turbulent background. Finally, we present the first-ever measurement of the relative importance between Stokes drag, Coriolis force, and centripetal force along the trajectories of inertial particles. We discover that vortical coherent structures lead to unexpected diffusion properties for heavy and light particles in the directions parallel and perpendicular to the rotation axis.

  9. Enhancement of rotatable anisotropy in ferrite doped FeNi thin film with oblique sputtering

    NASA Astrophysics Data System (ADS)

    Zhou, Cai; Jiang, Changjun; Zhao, Zhong

    2015-07-01

    Rotatable anisotropy of stripe domain (SD) was investigated in a ferrite doped FeNi thin film with different oblique angles. Rotation of SD under an in-plane magnetic field was observed by magnetic force microscopy, suggesting the existence of rotatable anisotropy. A rotatable anisotropy field Hrot was derived from the fitting curves of the in-plane resonance field versus the angle between the orientation of easy axis and applied field. As the oblique angle increases, an increase of Hrot from 305 Oe to 468 Oe was observed and the perpendicular anisotropy increased as well, indicating a correlation between rotatable anisotropy and perpendicular anisotropy.

  10. Thermocapillary bubble dynamics in a 2D axis swirl domain

    NASA Astrophysics Data System (ADS)

    Alhendal, Yousuf; Turan, Ali

    2014-09-01

    The lack of significant buoyancy effects in zero-gravity conditions poses an issue with fluid transfer in a stagnant liquid. In this paper, bubble movement in a stagnant liquid is analysed and presented numerically using a computational fluid dynamics approach. The governing continuum and conservation equations for two-phase flow are solved using the commercial software package Ansys-Fluent v.13. The volume of fluid method is used to track the liquid/gas interface in 2D and 3D domains, which has been found to be a valuable tool for studying the phenomenon of gas-liquid interaction, and the validation results are in reasonable agreement with earlier experimental observations. The flow is driven via Marangoni influence induced by the temperature difference, which in turn drives the bubble from the cold to the hot region. The results indicate that the inherent velocity of bubbles decreases with an increase in Marangoni number; this is in agreement with the results of previous experiments conducted in Kang et al. (Microgravity Sci Technol 20:67-71, 2008). Some three-dimensional simulations will also be performed to compare and examine the results with two-dimensional simulations. The thermocapillary bubble flow in a 2D swirl axisymmetry driven by the rotation of the walls was also carried out for different angular velocities in zero gravity. The bubble migration speed was found to decrease with increasing angular velocity. This occurrence is due to an increase in the pressure gradient between the cylinder's outer wall and the axis of rotation, which forces the lowest pressure region to shift from the sides of the bubble to the axis of rotation. A deformation of the bubble and the formation of the two vortices inside the bubble are also observed. These new and original findings aim to help support research into space applications.

  11. Thermocapillary bubble dynamics in a 2D axis swirl domain

    NASA Astrophysics Data System (ADS)

    Alhendal, Yousuf; Turan, Ali

    2015-04-01

    The lack of significant buoyancy effects in zero-gravity conditions poses an issue with fluid transfer in a stagnant liquid. In this paper, bubble movement in a stagnant liquid is analysed and presented numerically using a computational fluid dynamics approach. The governing continuum and conservation equations for two-phase flow are solved using the commercial software package Ansys-Fluent v.13. The volume of fluid method is used to track the liquid/gas interface in 2D and 3D domains, which has been found to be a valuable tool for studying the phenomenon of gas-liquid interaction, and the validation results are in reasonable agreement with earlier experimental observations. The flow is driven via Marangoni influence induced by the temperature difference, which in turn drives the bubble from the cold to the hot region. The results indicate that the inherent velocity of bubbles decreases with an increase in Marangoni number; this is in agreement with the results of previous experiments conducted in Kang et al. (Microgravity Sci Technol 20:67-71, 2008). Some three-dimensional simulations will also be performed to compare and examine the results with two-dimensional simulations. The thermocapillary bubble flow in a 2D swirl axisymmetry driven by the rotation of the walls was also carried out for different angular velocities in zero gravity. The bubble migration speed was found to decrease with increasing angular velocity. This occurrence is due to an increase in the pressure gradient between the cylinder's outer wall and the axis of rotation, which forces the lowest pressure region to shift from the sides of the bubble to the axis of rotation. A deformation of the bubble and the formation of the two vortices inside the bubble are also observed. These new and original findings aim to help support research into space applications.

  12. Methyl Group Internal Rotation in the Pure Rotational Spectrum of 1,1-DIFLUOROACETONE

    NASA Astrophysics Data System (ADS)

    Grubbs, G. S. Grubbs, II; Cooke, S. A.; Groner, P.

    2011-06-01

    We have used chirped pulse Fourier transform microwave spectroscopy to record the pure rotational spectrum of the title molecule. The spectrum was doubled owing to the internal rotation of the methyl group. The spectrum has been assigned and two approaches to the spectral analysis have been performed. In the first case, the A and E components were fit separately using a principal axis method with the SPFIT code of Pickett. In the second case, the A and E states were fit simultaneously using the ERHAM code. For a satisfactory analysis of the spectral data it has been found that the choice of Hamiltonian reduction, i.e. Watson A or S, is very important. The barrier to the internal rotation has been determined to be 261.1(8) Cm-1 and it will be compared to that of acetone and other halogenated acetone species recently studied in our laboratory.

  13. Electrohydrodynamic Quincke rotation of a prolate ellipsoid

    NASA Astrophysics Data System (ADS)

    Brosseau, Quentin; Hickey, Gregory; Vlahovska, Petia M.

    2017-01-01

    We study experimentally the occurrence of spontaneous spinning (Quincke rotation) of an ellipsoid in a uniform direct current (dc) electric field. For an ellipsoid suspended in an unbounded fluid, we find two stable states characterized by the orientation of the ellipsoid long axis relative to the applied electric field: spinless (parallel) and spinning (perpendicular). The phase diagram of ellipsoid behavior as a function of field strength and aspect ratio is in close agreement with the theory of Cēbers et al. [Phys. Rev. E 63, 016301 (2000)], 10.1103/PhysRevE.63.016301. We also investigate the dynamics of the ellipsoidal Quincke rotor resting on a planar surface with normal perpendicular to the field direction. We find behaviors, such as swinging (long axis oscillating around the applied field direction) and tumbling, due to the confinement.

  14. Differential rotation of the unstable nonlinear r -modes

    NASA Astrophysics Data System (ADS)

    Friedman, John L.; Lindblom, Lee; Lockitch, Keith H.

    2016-01-01

    At second order in perturbation theory, the r -modes of uniformly rotating stars include an axisymmetric part that can be identified with differential rotation of the background star. If one does not include radiation reaction, the differential rotation is constant in time and has been computed by Sá. It has a gauge dependence associated with the family of time-independent perturbations that add differential rotation to the unperturbed equilibrium star: For stars with a barotropic equation of state, one can add to the time-independent second-order solution arbitrary differential rotation that is stratified on cylinders (that is a function of distance ϖ to the axis of rotation). We show here that the gravitational radiation-reaction force that drives the r -mode instability removes this gauge freedom; the exponentially growing differential rotation of the unstable second-order r -mode is unique. We derive a general expression for this rotation law for Newtonian models and evaluate it explicitly for slowly rotating models with polytropic equations of state.

  15. Axis perpendicularity measuring method using vision

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Woo; Song, Jun-Yeob; Ha, Tae-Ho

    2008-11-01

    Perpendicularity measurement is very important in machine assembly and calibration. Axis perpendicularity error often contributes much more to the total error than the linear positioning and straightness errors. This paper presents two new non-contact methods for measuring axis perpendicularity using vision system. In general a perpendicular master and a dial gauge are used to measure the axis perpendicularity. We can obtain the axis perpendicularity by measuring differences from the master. Therefore, its accuracy depends on the accuracy of perpendicular master. The accuracy of the perpendicular master is therefore extremely important and it is impossible that the accuracy of a perpendicularity measurement is superior to the accuracy of the perpendicular master. This paper proposes two new methods that can measure axis perpendicularity without using a perpendicular master. Absolute axis perpendicularity measurement can be achieved by vision system. The feasibility of our developed measurement methods are confirmed by several experimental results.

  16. Antenna Axis Offset Estimation from VLBI

    NASA Technical Reports Server (NTRS)

    Kurdubov, Sergey; Skurikhina, Elena

    2010-01-01

    The antenna axis offsets were estimated from global solutions and single sessions. We have built a set of global solutions from R1 and R4 sessions and from the sets of sessions between SVETLOE repairs. We compared our estimates with local survey data for the stations of the QUASAR network. Svetloe station axis offset values have changed after repairs. For non-global networks, the axis offset value of a single station can significantly affect the EOP estimations.

  17. Vibrational analysis of vertical axis wind turbine blades

    NASA Astrophysics Data System (ADS)

    Kapucu, Onur

    The goal of this research is to derive a vibration model for a vertical axis wind turbine blade. This model accommodates the affects of varying relative flow angle caused by rotating the blade in the flow field, uses a simple aerodynamic model that assumes constant wind speed and constant rotation rate, and neglects the disturbance of wind due to upstream blade or post. The blade is modeled as elastic Euler-Bernoulli beam under transverse bending and twist deflections. Kinetic and potential energy equations for a rotating blade under deflections are obtained, expressed in terms of assumed modal coordinates and then plugged into Lagrangian equations where the non-conservative forces are the lift and drag forces and moments. An aeroelastic model for lift and drag forces, approximated with third degree polynomials, on the blade are obtained assuming an airfoil under variable angle of attack and airflow magnitudes. A simplified quasi-static airfoil theory is used, in which the lift and drag coefficients are not dependent on the history of the changing angle of attack. Linear terms on the resulting equations of motion will be used to conduct a numerical analysis and simulation, where numeric specifications are modified from the Sandia-17m Darrieus wind turbine by Sandia Laboratories.

  18. Perceptual Strategies of Pigeons to Detect a Rotational Centre—A Hint for Star Compass Learning?

    PubMed Central

    Helduser, Sascha; Mouritsen, Henrik; Güntürkün, Onur

    2015-01-01

    Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird orientation. Here, we use operant conditioning to demonstrate that homing pigeons can principally learn to detect a rotational centre in a rotating dot pattern and we examine their behavioural response strategies in a series of experiments. Initially, most pigeons applied a strategy based on local stimulus information such as movement characteristics of single dots. One pigeon seemed to immediately ignore eccentric stationary dots. After special training, all pigeons could shift their attention to more global cues, which implies that pigeons can learn the concept of a rotational axis. In our experiments, the ability to precisely locate the rotational centre was strongly dependent on the rotational velocity of the dot pattern and it crashed at velocities that were still much faster than natural celestial rotation. We therefore suggest that the axis of the very slow, natural, celestial rotation could be perceived by birds through the movement itself, but that a time-delayed pattern comparison should also be considered as a very likely alternative strategy. PMID:25807499

  19. Perceptual strategies of pigeons to detect a rotational centre--a hint for star compass learning?

    PubMed

    Alert, Bianca; Michalik, Andreas; Helduser, Sascha; Mouritsen, Henrik; Güntürkün, Onur

    2015-01-01

    Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird orientation. Here, we use operant conditioning to demonstrate that homing pigeons can principally learn to detect a rotational centre in a rotating dot pattern and we examine their behavioural response strategies in a series of experiments. Initially, most pigeons applied a strategy based on local stimulus information such as movement characteristics of single dots. One pigeon seemed to immediately ignore eccentric stationary dots. After special training, all pigeons could shift their attention to more global cues, which implies that pigeons can learn the concept of a rotational axis. In our experiments, the ability to precisely locate the rotational centre was strongly dependent on the rotational velocity of the dot pattern and it crashed at velocities that were still much faster than natural celestial rotation. We therefore suggest that the axis of the very slow, natural, celestial rotation could be perceived by birds through the movement itself, but that a time-delayed pattern comparison should also be considered as a very likely alternative strategy.

  20. Off-Axis Neutrino Scattering in Gamma-Ray Burst Central Engines

    NASA Astrophysics Data System (ADS)

    Miller, Warner A.; George, Nathan D.; Kheyfets, Arkady; McGhee, John M.

    2003-02-01

    The search for an understanding of an energy source great enough to explain the gamma-ray burst (GRB) phenomenon has attracted much attention from the astrophysical community since its discovery. In this paper we extend the work of Asano and Fukuyama, and Salmonson and Wilson and analyze the off-axis contributions to the energy-momentum deposition rate (MDR) from the ν-ν collisions above a rotating black hole/thin accretion disk system. Our calculations are performed by imaging the accretion disk at a specified observer using the full geodesic equations and calculating the cumulative MDR from the scattering of all pairs of neutrinos and antineutrinos arriving at the observer. Our results shed light on the beaming efficiency of GRB models of this kind. Although we confirm Asano and Fukuyama's conjecture as to the constancy of the beaming for small angles away from the axis, we find that the dominant contribution to the MDR comes from near the surface of the disk with a tilt of approximately π/4 in the direction of the disk's rotation. We find that the MDR at large radii is directed outward in a conic section centered around the symmetry axis and is larger by a factor of 10-20 than the on-axis values. By including this off-axis disk source, we find a linear dependence of the MDR on the black hole angular momentum.

  1. Spontaneous transfer of chirality in an atropisomerically enriched two-axis system.

    PubMed

    Barrett, Kimberly T; Metrano, Anthony J; Rablen, Paul R; Miller, Scott J

    2014-05-01

    One of the most well-recognized stereogenic elements in a chiral molecule is an sp(3)-hybridized carbon atom that is connected to four different substituents. Axes of chirality can also exist about bonds with hindered barriers of rotation; molecules containing such axes are known as atropisomers. Understanding the dynamics of these systems can be useful, for example, in the design of single-atropisomer drugs or molecular switches and motors. For molecules that exhibit a single axis of chirality, rotation about that axis leads to racemization as the system reaches equilibrium. Here we report a two-axis system for which an enantioselective reaction produces four stereoisomers (two enantiomeric pairs): following a catalytic asymmetric transformation, we observe a kinetically controlled product distribution that is perturbed from the system's equilibrium position. As the system undergoes isomerization, one of the diastereomeric pairs drifts spontaneously to a higher enantiomeric ratio. In a compensatory manner, the enantiomeric ratio of the other diastereomeric pair decreases. These observations are made for a class of unsymmetrical amides that exhibits two asymmetric axes--one axis is defined through a benzamide substructure, and the other axis is associated with differentially N,N-disubstituted amides. The stereodynamics of these substrates provides an opportunity to observe a curious interplay of kinetics and thermodynamics intrinsic to a system of stereoisomers that is constrained to a situation of partial equilibrium.

  2. Manipulator for rotating and examining small spheres

    DOEpatents

    Weinstein, B.W.; Willenborg, D.L.

    1980-02-12

    A manipulator is disclosed which provides fast, accurate rotational positioning of a small sphere, such as an inertial confinement fusion target, which allows inspecting of the entire surface of the sphere. The sphere is held between two flat, flexible tips which move equal amounts in opposite directions. This provides rolling of the ball about two orthogonal axes without any overall translation. The manipulator may be controlled, for example, by an x- and y-axis driven controlled by a mini-computer which can be programmed to generate any desired scan pattern. 8 figs.

  3. Manipulator for rotating and examining small spheres

    DOEpatents

    Weinstein, Berthold W. [Livermore, CA; Willenborg, David L. [Livermore, CA

    1980-02-12

    A manipulator which provides fast, accurate rotational positioning of a small sphere, such as an inertial confinement fusion target, which allows inspecting of the entire surface of the sphere. The sphere is held between two flat, flexible tips which move equal amounts in opposite directions. This provides rolling of the ball about two orthogonal axes without any overall translation. The manipulator may be controlled, for example, by an x- and y-axis driven controlled by a mini-computer which can be programmed to generate any desired scan pattern.

  4. Principles of the prolactin/vasoinhibin axis

    PubMed Central

    Bertsch, Thomas; Bollheimer, Cornelius; Rios-Barrera, Daniel; Pearce, Christy F.; Hüfner, Michael; Martínez de la Escalera, Gonzalo; Clapp, Carmen

    2015-01-01

    The hormonal family of vasoinhibins, which derive from the anterior pituitary hormone prolactin, are known for their inhibiting effects on blood vessel growth, vasopermeability, and vasodilation. As pleiotropic hormones, vasoinhibins act in multiple target organs and tissues. The generation, secretion, and regulation of vasoinhibins are embedded into the organizational principle of an axis, which integrates the hypothalamus, the pituitary, and the target tissue microenvironment. This axis is designated as the prolactin/vasoinhibin axis. Disturbances of the prolactin/vasoinhibin axis are associated with the pathogenesis of retinal and cardiac diseases and with diseases occurring during pregnancy. New phylogenetical, physiological, and clinical implications are discussed. PMID:26310939

  5. Discomfort criteria for single-axis vibrations

    NASA Technical Reports Server (NTRS)

    Dempsey, T. K.; Leatherwood, J. D.; Clevenson, S. A.

    1979-01-01

    Experimental investigations were conducted to determine the fundamental relationships governing human subjective discomfort response to single-axis vibrations. The axes investigated were vertical, lateral, longitudinal, roll, and pitch, and the vibrations used were both sinusoidal and random in nature. Results of these investigations provided the basis for: (1) development of a scale of passenger discomfort that is common to all axes of vibration; and (2) generation of discomfort criteria for each axis of each axis and for both types of vibration. Furthermore, empirical equations describing discomfort responses within each axis of vibration are included.

  6. MEMS inertial sensors with integral rotation means.

    SciTech Connect

    Kohler, Stewart M.

    2003-09-01

    The state-of-the-art of inertial micro-sensors (gyroscopes and accelerometers) has advanced to the point where they are displacing the more traditional sensors in many size, power, and/or cost-sensitive applications. A factor limiting the range of application of inertial micro-sensors has been their relatively poor bias stability. The incorporation of an integral sensitive axis rotation capability would enable bias mitigation through proven techniques such as indexing, and foster the use of inertial micro-sensors in more accuracy-sensitive applications. Fabricating the integral rotation mechanism in MEMS technology would minimize the penalties associated with incorporation of this capability, and preserve the inherent advantages of inertial micro-sensors.

  7. Spontaneous rotation in a driven mechanical system

    NASA Astrophysics Data System (ADS)

    Alexander, T. J.

    2016-06-01

    We show that a mass free to circulate around a shaken pivot point exhibits resonance-like effects and large amplitude dynamics even though there is no natural frequency in the system, simply through driving under geometrical constraint. We find that synchronization between force and mass occurs over a wide range of forcing amplitudes and frequencies, even when the forcing axis is dynamically, and randomly, changed. Above a critical driving amplitude the mass will spontaneously rotate, with a fractal boundary dividing clockwise and anti-clockwise rotations. We show that this has significant implications for energy harvesting, with large output power over a wide frequency range. We examine also the effect of driving symmetry on the resultant dynamics, and show that if the shaking is circular the motion becomes constrained, whereas for anharmonic rectilinear shaking the dynamics may become chaotic, with the system mimicking that of the kicked rotor.

  8. ON THE ROTATIONAL BEHAVIOR OF NEREID

    SciTech Connect

    Alexander, S. G.; Hesselbrock, Andrew J.; Wu Tiandan; Marshall, Megan D.; Abel, N. P.

    2011-07-15

    We have conducted a set of numerical simulations of the combined orbital and rotational motion of Neptune's moon Nereid to study its rotational behavior under the influence of gravitational torques from Neptune. Due to the high eccentricity of its orbit, and the fact that the gravitational torque from Neptune varies as r{sup -3}, Nereid experiences a large impulsive torque during each periapsis passage. If Nereid is a prolate body, then these kicks induce oscillations in the orientation of its spin axis that is seen to be a coning motion of modulating amplitude. We have proposed that these modulations may be responsible for the long-term photometric variability of Nereid as reported by Schaefer et al. and others.

  9. The flow past a freely rotating sphere

    NASA Astrophysics Data System (ADS)

    Fabre, David; Tchoufag, Joël; Citro, Vincenzo; Giannetti, Flavio; Luchini, Paolo

    2016-08-01

    We consider the flow past a sphere held at a fixed position in a uniform incoming flow but free to rotate around a transverse axis. A steady pitchfork bifurcation is reported to take place at a threshold Re^OS=206 leading to a state with zero torque but nonzero lift. Numerical simulations allow to characterize this state up to Re≈ 270 and confirm that it substantially differs from the steady-state solution which exists in the wake of a fixed, non-rotating sphere beyond the threshold Re^SS=212 . A weakly nonlinear analysis is carried out and is shown to successfully reproduce the results and to give substantial improvement over a previous analysis (Fabre et al. in J Fluid Mech 707:24-36, 2012). The connection between the present problem and that of a sphere in free fall following an oblique, steady (OS) path is also discussed.

  10. Helical axis stellarator with noninterlocking planar coils

    DOEpatents

    Reiman, A.; Boozer, A.H.

    1984-03-06

    The present invention generates stellarator fields having favorable properties (magnetic well and large rotational transform) by a simple coil system consisting only of unlinked planar non-circular coils. At large rotational transform toroidal effects on magnetic well and rotational transform are small and can be ignored. We do so herein, specializing in straight helical systems.

  11. An explicit reconstruction algorithm for the transverse ray transform of a second rank tensor field from three axis data

    NASA Astrophysics Data System (ADS)

    Desai, Naeem M.; Lionheart, William R. B.

    2016-11-01

    We give an explicit plane-by-plane filtered back-projection reconstruction algorithm for the transverse ray transform of symmetric second rank tensor fields on Euclidean three-space, using data from rotation about three orthogonal axes. We show that in the general case two-axis data is insufficient, but we give an explicit reconstruction procedure for the potential case with two-axis data. We describe a numerical implementation of the three-axis algorithm and give reconstruction results for simulated data.

  12. Combined Experiment Phase 1. [Horizontal axis wind turbines: wind tunnel testing versus field testing

    SciTech Connect

    Butterfield, C.P.; Musial, W.P.; Simms, D.A.

    1992-10-01

    How does wind tunnel airfoil data differ from the airfoil performance on an operating horizontal axis wind turbine (HAWT) The National Renewable Energy laboratory has been conducting a comprehensive test program focused on answering this question and understanding the basic fluid mechanics of rotating HAWT stall aerodynamics. The basic approach was to instrument a wind rotor, using an airfoil that was well documented by wind tunnel tests, and measure operating pressure distributions on the rotating blade. Based an the integrated values of the pressure data, airfoil performance coefficients were obtained, and comparisons were made between the rotating data and the wind tunnel data. Care was taken to the aerodynamic and geometric differences between the rotating and the wind tunnel models. This is the first of two reports describing the Combined Experiment Program and its results. This Phase I report covers background information such as test setup and instrumentation. It also includes wind tunnel test results and roughness testing.

  13. Differential rotation in solar-like stars from global simulations

    SciTech Connect

    Guerrero, G.; Kosovichev, A. G.; Smolarkiewicz, P. K.; Mansour, N. N. E-mail: sasha@sun.stanford.edu E-mail: nagi.n.mansour@nasa.gov

    2013-12-20

    To explore the physics of large-scale flows in solar-like stars, we perform three-dimensional anelastic simulations of rotating convection for global models with stratification resembling the solar interior. The numerical method is based on an implicit large-eddy simulation approach designed to capture effects from non-resolved small scales. We obtain two regimes of differential rotation, with equatorial zonal flows accelerated either in the direction of rotation (solar-like) or in the opposite direction (anti-solar). While the models with the solar-like differential rotation tend to produce multiple cells of meridional circulation, the models with anti-solar differential rotation result in only one or two meridional cells. Our simulations indicate that the rotation and large-scale flow patterns critically depend on the ratio between buoyancy and Coriolis forces. By including a sub-adiabatic layer at the bottom of the domain, corresponding to the stratification of a radiative zone, we reproduce a layer of strong radial shear similar to the solar tachocline. Similarly, enhanced super-adiabaticity at the top results in a near-surface shear layer located mainly at lower latitudes. The models reveal a latitudinal entropy gradient localized at the base of the convection zone and in the stable region, which, however, does not propagate across the convection zone. In consequence, baroclinicity effects remain small, and the rotation isocontours align in cylinders along the rotation axis. Our results confirm the alignment of large convective cells along the rotation axis in the deep convection zone and suggest that such 'banana-cell' pattern can be hidden beneath the supergranulation layer.

  14. Diamagnetism of rotating plasma

    SciTech Connect

    Young, W. C.; Hassam, A. B.; Romero-Talamas, C. A.; Ellis, R. F.; Teodorescu, C.

    2011-11-15

    Diamagnetism and magnetic measurements of a supersonically rotating plasma in a shaped magnetic field demonstrate confinement of plasma pressure along the magnetic field resulting from centrifugal force. The Grad-Shafranov equation of ideal magnetohydrodynamic force balance, including supersonic rotation, is solved to confirm that the predicted angular velocity is in agreement with spectroscopic measurements of the Doppler shifts.

  15. Wideband rotating junctions

    NASA Astrophysics Data System (ADS)

    Pochernyaev, V. N.

    1993-06-01

    Rotating junctions of coaxial-waveguide and waveguide type with a traveling wave coefficient exceeding 0.8 in a wide frequency range are considered. The design of these junctions is based on a method of the theory of electrodynamic circuits. Numerical results are obtained for rotating junctions of partially filled rectangular waveguide type and their particular cases.

  16. The Weighted Oblimin Rotation.

    ERIC Educational Resources Information Center

    Lorenzo-Seva, Urbano

    2000-01-01

    Demonstrates that the weighting procedure proposed by E. Cureton and S. Mulaik (1975) can be applied to the Direct Oblimin approach of D. Clarkson and R. Jennrich (1988) to provide good results. The rotation method obtained is called Weighted Oblimin. Compared this method to other rotation methods with favorable results. (SLD)

  17. SMAP Faraday Rotation

    NASA Technical Reports Server (NTRS)

    Le Vine, David

    2016-01-01

    Faraday rotation is a change in the polarization as signal propagates through the ionosphere. At L-band it is necessary to correct for this change and measurements are made on the spacecraft of the rotation angle. These figures show that there is good agreement between the SMAP measurements (blue) and predictions based on models (red).

  18. Design and analysis of a dual-axis resonator fiber-optic gyroscope employing a single source.

    PubMed

    Pinnoji, Prerana Dabral; Nayak, Jagannath

    2013-08-01

    In this paper, design of a resonator fiber-optic gyroscope comprised of a single laser source and two optical fiber resonator rings is presented. A typical gyroscope measures angular rotation around a fixed axis, whereas the proposed design can sense simultaneous rotation about two orthogonal axes. Two variants of the design are proposed and analyzed using a mathematical model based on Jones matrix methodology.

  19. Spin Axis Distribution of the Hungaria Asteroids via Lightcurve Inversion

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Stephens, Robert D.; Coley, Daniel

    2014-11-01

    Since 2005, we have conducted a dedicated campaign to obtain dense lightcurves of members of the Hungaria asteroid population. As a result, the number of Hungarias in the asteroid lightcurve database (LCDB; Warner et al., 2009; Icarus 202, 134-146) with a statistically valid rotation rate rose from less than 50 to almost 300. The particular value of the Hungarias is that they are smallest and closest-to-sun main belt objects that can be studied with modest-sized telescopes. As such, they are more likely subject to YORP-altered spin states. We have previously verified highly-evolved rotation rates (Warner et al., 2009; Icarus 204, 172-182). This study takes the next step of tracing the evolution of spin orientations. We combined the dense lightcurves from our campaign with so-called “sparse data” from the NEA surveys to model the spin axis orientation using lightcurve inversion methods (see works by Kaasalainen, Torppa, Durech, and Hanus). Because high-dispersion sparse data are of little use for low amplitude objects, we limited the Hungarias to be modeled to those with a maximum amplitude of A ≥ 0.15 mag, an LCDB reliability code of U ≥ 2, the period in the LCDB summary was unambiguous, and the asteroid did not show signs of tumbling (non-principal axis rotation). The result as of mid-August 2014 was a list of 231 Hungaria candidates for modeling. Using a bank of five independent desktop computers and customized software, we first determined the likely sidereal period of the asteroid. That period was then used for a spin axis (pole) search involving 315 discrete longitude-latitude pairs. We report on the results of our searches, including weighting solutions when a unique solution was not found (often the case in lightcurve inversion), and how the results compare to similar studies using a more general asteroid population. BDW and AWH acknowledge funding from NASA NNX13AP56G and NSF grant AST-1210099. RDS acknowledges NASA grant NNX13AP56G and the

  20. Rotational Spectroscopy of Methyl Vinyl Ketone

    NASA Astrophysics Data System (ADS)

    Zakharenko, Olena; Motiyenko, R. A.; Aviles Moreno, Juan-Ramon; Huet, T. R.

    2015-06-01

    Methyl vinyl ketone, MVK, along with previously studied by our team methacrolein, is a major oxidation product of isoprene, which is one of the primary contributors to annual global VOC emissions. In this talk we present the analysis of the rotational spectrum of MVK recorded at room temperature in the 50 -- 650 GHz region using the Lille spectrometer. The spectroscopic characterization of MVK ground state will be useful in the detailed analysis of high resolution infrared spectra. Our study is supported by high level quantum chemical calculations to model the structure of the two stable s-trans and s-cis conformers and to obtain the harmonic force field parameters, internal rotation barrier heights, and vibrational frequencies. In the Doppler-limited spectra the splittings due to the internal rotation of methyl group are resolved, therefore for analysis of this molecule we used the Rho-Axis-Method Hamiltonian and RAM36 code to fit the rotational transitions. At the present time the ground state of two conformers is analyzed. Also we intend to study some low lying excited states. The analysis is in progress and the latest results will be presented. Support from the French Laboratoire d'Excellence CaPPA (Chemical and Physical Properties of the Atmosphere) through contract ANR-10-LABX-0005 of the Programme d'Investissements d'Avenir is acknowledged.

  1. Streaming potential near a rotating porous disk.

    PubMed

    Prieve, Dennis C; Sides, Paul J

    2014-09-23

    Theory and experimental results for the streaming potential measured in the vicinity of a rotating porous disk-shaped sample are described. Rotation of the sample on its axis draws liquid into its face and casts it from the periphery. Advection within the sample engenders streaming current and streaming potential that are proportional to the zeta potential and the disk's major dimensions. When Darcy's law applies, the streaming potential is proportional to the square of the rotation at low rate but becomes invariant with rotation at high rate. The streaming potential is invariant with the sample's permeability at low rate and is proportional to the inverse square of the permeability at high rate. These predictions were tested by determining the zeta potential and permeability of the loop side of Velcro, a sample otherwise difficult to characterize; reasonable values of -56 mV for zeta and 8.7 × 10(-9) m(2) for the permeability were obtained. This approach offers the ability to determine both the zeta potential and the permeability of materials having open structures. Compressing them into a porous plug is unnecessary. As part of the development of the theory, a convenient formula for a flow-weighted volume-averaged space-charge density of the porous medium, -εζ/k, was obtained, where ε is the permittivity, ζ is the zeta potential, and k is the Darcy permeability. The formula is correct when Smoluchowski's equation and Darcy's law are both valid.

  2. Rotatable superconducting cyclotron adapted for medical use

    DOEpatents

    Blosser, Henry G.; Johnson, David A.; Riedel, Jack; Burleigh, Richard J.

    1985-01-01

    A superconducting cyclotron (10) rotatable on a support structure (11) in an arc of about 180.degree. around a pivot axis (A--A) and particularly adapted for medical use is described. The rotatable support structure (13, 15) is balanced by being counterweighted (14) so as to allow rotation of the cyclotron and a beam (12), such as a subparticle (neutron) or atomic particle beam, from the cyclotron in the arc around a patient. Flexible hose (25) is moveably attached to the support structure for providing a liquified gas which is supercooled to near 0.degree. K. to an inlet means (122) to a chamber (105) around superconducting coils (101, 102). The liquid (34) level in the cyclotron is maintained approximately half full so that rotation of the support structure and cyclotron through the 180.degree. can be accomplished without spilling the liquid from the cyclotron. With the coils vertically oriented, each turn of the winding is approximately half immersed in liquid (34) and half exposed to cold gas and adequate cooling to maintain superconducting temperatures in the section of coil above the liquid level is provided by the combination of cold gas/vapor and by the conductive flow of heat along each turn of the winding from the half above the liquid to the half below.

  3. Rotation sensor switch

    DOEpatents

    Sevec, John B.

    1978-01-01

    A protective device to provide a warning if a piece of rotating machinery slows or stops comprises a pair of hinged weights disposed to rotate on a rotating shaft of the equipment. When the equipment is rotating, the weights remain in a plane essentially perpendicular to the shaft and constitute part of an electrical circuit that is open. When the shaft slows or stops, the weights are attracted to a pair of concentric electrically conducting disks disposed in a plane perpendicular to the shaft and parallel to the plane of the weights when rotating. A disk magnet attracts the weights to the electrically conducting plates and maintains the electrical contact at the plates to complete an electrical circuit that can then provide an alarm signal.

  4. ROTATION OF CORONAL MASS EJECTIONS DURING ERUPTION

    SciTech Connect

    Lynch, B. J.; Li, Y.; Luhmann, J. G.; Antiochos, S. K.; DeVore, C. R. E-mail: yanli@ssl.berkeley.edu E-mail: spiro.k.antiochos@nasa.gov

    2009-06-01

    Understanding the connection between coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) is one of the most important problems in solar-terrestrial physics. We calculate the rotation of erupting field structures predicted by numerical simulations of CME initiation via the magnetic breakout model. In this model, the initial potential magnetic field has a multipolar topology and the system is driven by imposing a shear flow at the photospheric boundary. Our results yield insight on how to connect solar observations of the orientation of the filament or polarity inversion line (PIL) in the CME source region, the orientation of the CME axis as inferred from coronagraph images, and the ICME flux rope orientation obtained from in situ measurements. We present the results of two numerical simulations that differ only in the direction of the applied shearing motions (i.e., the handedness of the sheared-arcade systems and their resulting CME fields). In both simulations, eruptive flare reconnection occurs underneath the rapidly expanding sheared fields transforming the ejecta fields into three-dimensional flux rope structures. As the erupting flux ropes propagate through the low corona (from 2 to 4 R{sub sun}) the right-handed breakout flux rope rotates clockwise and the left-handed breakout flux rope rotates counterclockwise, in agreement with recent observations of the rotation of erupting filaments. We find that by 3.5 R {sub sun} the average rotation angle between the flux rope axes and the active region PIL is approximately 50 deg. We discuss the implications of these results for predicting, from the observed chirality of the pre-eruption filament and/or other properties of the CME source region, the direction and amount of rotation that magnetic flux rope structures will experience during eruption. We also discuss the implications of our results for CME initiation models.

  5. Dynamical evolution of comet nucleus rotation

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Sidorenko, V. V.; Neishtadt, A. I.; Vasiliev, A. A.

    2001-11-01

    The rotational dynamics of outgassing cometary nuclei are investigated analytically using dynamical systems theory. We develop a general theory for the averaged evolution of a comet nucleus rotation state assuming that the nucleus is a spheroid (either prolate or oblate) and that the outgassing torques are a function of solar insolation and heliocentric distance. The resulting solutions are a function of the comet outgassing properties, its heliocentric orbit, and the assumed distribution of active regions on its surface. We find that the long-term evolution of the comet nucleus rotation is a strong function of the distribution of active regions over its surface. Specifically, we find that a comet nucleus with a uniformly active surface will tend towards a rotation state with a nutation angle of ~ 55 degrees and an angular momentum perpendicular to the sun-perihelion direction. Conversely, a comet nucleus with an isolated active region will tend towards a zero nutation angle with its symmetry axis and angular momentum aligned parallel to the sun-perihelion direction. For active surface regions between these extremes we find 4 qualitatively different dynamical outcomes. In all cases, the theory predicts that the comet nucleus angular momentum will have a secular increase, a phenomenon that could contribute to nucleus splitting of active comets. These results can be used to discriminate between competing theories of comet outgassing based on a nucelus' rotation state. They also allow for a range of plausible a priori constraints to be placed on a comet's rotation state to aid in the interpretation of its outgassing structure. This work was supported by the NASA JURRISS program under Grant NAG5-8715. AIN, AAV and VVS acknowledge support from Russian Foundation for Basic research via Grants 00-01-00538 and 00-01-0174 respectively. DJS acknowledges support from the PG&G program via Grant NAG5-9017.

  6. Intrinsic rotation in DIII-D

    SciTech Connect

    DeGrassie, J. S.; Rice, J. E.; Burrell, K. H.; Groebner, R. J.; Solomon, W. M.

    2007-05-15

    In the absence of any auxiliary torque input, the DIII-D plasma consists of nonzero toroidal angular momentum, in other words, it rotates. This effect is commonly observed in tokamaks, being referred to as intrinsic rotation. Measurements of intrinsic rotation profiles have been made in DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] H-mode discharges, with both Ohmic heating (OH) and electron cyclotron heating (ECH) in which there is no auxiliary torque. Recently, the H-mode data set has been extended with the newly configured DIII-D simultaneous co- and counter-directed neutral beam injection (NBI) capability resulting in control of the local torque deposition, where co and counter refer to the direction relative to the toroidal plasma current. Understanding intrinsic rotation is important for projection toward burning plasma performance where any NBI torque will be relatively small. The toroidal velocity is recognizably important regarding issues of stability and confinement. In DIII-D ECH H-modes the rotation profile is hollow, co-directed at large minor radius and depressed, or actually counter-directed, nearer the magnetic axis. This profile varies with the ECH power deposition profile to some extent. In contrast, OH H-modes have a relatively flat co-directed rotation profile. There is a scaling of the DIII-D intrinsic toroidal velocity with W/I{sub p}, as seen in intrinsic rotation in Alcator C-Mod [J. Rice, Nucl. Fusion 39, 1175 (1999)], where W is the total plasma thermal energy and I{sub p} is the magnitude of the toroidal plasma current. This common scaling resulted in a dimensionless similarity experiment between DIII-D and Alcator C-Mod on intrinsic rotation, obtaining a single spatial point match in the toroidal velocity normalized to the ion thermal velocity. The balanced NBI capability in DIII-D is a useful tool to push scaling studies to higher values of the plasma normalized energy, notwithstanding the details of torque deposition for co-NBI versus

  7. Combined AC electroosmosis and dielectrophoresis for controlled rotation of microparticles

    PubMed Central

    Walid Rezanoor, Md.; Dutta, Prashanta

    2016-01-01

    Electrorotation is widely used for characterization of biological cells and materials using a rotating electric field. Generally, multiphase AC electric fields and quadrupolar electrode configuration are needed to create a rotating electric field for electrorotation. In this study, we demonstrate a simple method to rotate dielectrophoretically trapped microparticles using a stationary AC electric field. Coplanar interdigitated electrodes are used to create a linearly polarized nonuniform AC electric field. This nonuniform electric field is employed for dielectrophoretic trapping of microparticles as well as for generating electroosmotic flow in the vicinity of the electrodes resulting in rotation of microparticles in a microfluidic device. The rotation of barium titanate microparticles is observed in 2-propanol and methanol solvent at a frequency below 1 kHz. A particle rotation rate as high as 240 revolutions per minute is observed. It is demonstrated that precise manipulation (both rotation rate and equilibrium position) of the particles is possible by controlling the frequency of the applied electric field. At low frequency range, the equilibrium positions of the microparticles are observed between the electrode edge and electrode center. This method of particle manipulation is different from electrorotation as it uses induced AC electroosmosis instead of electric torque as in the case of electrorotation. Moreover, it has been shown that a microparticle can be rotated along its own axis without any translational motion. PMID:27014394

  8. Speed and Torque Control Strategies for Loss Reduction of Vertical Axis Wind Turbines

    NASA Astrophysics Data System (ADS)

    Argent, Michael; McDonald, Alasdair; Leithead, Bill; Giles, Alexander

    2016-09-01

    This paper builds on the work into modelling the generator losses for Vertical Axis Wind Turbines from their intrinsic torque cycling to investigate the effects of aerodynamic inefficiencies caused by the varying rotational speed resulting from different torque control strategies to the cyclic torque. This is achieved by modelling the wake that builds up from the rotation of the VAWT rotor to investigate how the wake responds to a changing rotor speed and how this in turn affects the torque produced by the blades as well as the corresponding change in generator losses and any changes to the energy extracted by the wind turbine rotor.

  9. Differential Rotation and Angular Momentum Transport Caused by Thermal Convection in a Rotating Spherical Shell

    NASA Astrophysics Data System (ADS)

    Takehiro, S.; Sasaki, Y.; Hayashi, Y.-Y.; Yamada, M.

    2013-12-01

    We investigate generation mechanisms of differential rotation and angular momentum transport caused by Boussinesq thermal convection in a rotating spherical shell based on weakly nonlinear numerical calculations for various values of the Prandtl and Ekman numbers under a setup similar to the solar convection layer. When the Prandtl number is of order unity or less and the rotation rate of the system is small (the Ekman number is larger than O(10-2)), the structure of thermal convection is not governed by the Taylor-Proudman theorem; banana-type convection cells emerge which follow the spherical shell boundaries rather than the rotation axis. Due to the Coriolis effect, the velocity field associated with those types of convection cells accompanies the Reynolds stress which transports angular momentum from high-latitudes to the equatorial region horizontally, and equatorial prograde flows are produced. The surface and internal distributions of differential rotation realized in this regime are quite similar to those observed in the Sun with helioseismology. These results may suggest that we should apply larger values of the eddy diffusivities than those believed so far when we use a low resolution numerical model for thermal convection in the solar interior.

  10. Giant Faraday Rotation of High-Order Plasmonic Modes in Graphene-Covered Nanowires.

    PubMed

    Kuzmin, Dmitry A; Bychkov, Igor V; Shavrov, Vladimir G; Temnov, Vasily V

    2016-07-13

    Plasmonic Faraday rotation in nanowires manifests itself in the rotation of the spatial intensity distribution of high-order surface plasmon polariton (SPP) modes around the nanowire axis. Here we predict theoretically the giant Faraday rotation for SPPs propagating on graphene-coated magneto-optically active nanowires. Upon the reversal of the external magnetic field pointing along the nanowire axis some high-order plasmonic modes may be rotated by up to ∼100° on the length scale of about 500 nm at mid-infrared frequencies. Tuning the carrier concentration in graphene by chemical doping or gate voltage allows for controlling SPP-properties and notably the rotation angle of high-order azimuthal modes. Our results open the door to novel plasmonic applications ranging from nanowire-based Faraday isolators to the magnetic control in quantum-optical applications.

  11. Identification of kinematic errors of five-axis machine tool trunnion axis from finished test piece

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Fu, Jianzhong; Chen, Zichen

    2014-09-01

    Compared with the traditional non-cutting measurement, machining tests can more accurately reflect the kinematic errors of five-axis machine tools in the actual machining process for the users. However, measurement and calculation of the machining tests in the literature are quite difficult and time-consuming. A new method of the machining tests for the trunnion axis of five-axis machine tool is proposed. Firstly, a simple mathematical model of the cradle-type five-axis machine tool was established by optimizing the coordinate system settings based on robot kinematics. Then, the machining tests based on error-sensitive directions were proposed to identify the kinematic errors of the trunnion axis of cradle-type five-axis machine tool. By adopting the error-sensitive vectors in the matrix calculation, the functional relationship equations between the machining errors of the test piece in the error-sensitive directions and the kinematic errors of C-axis and A-axis of five-axis machine tool rotary table was established based on the model of the kinematic errors. According to our previous work, the kinematic errors of C-axis can be treated as the known quantities, and the kinematic errors of A-axis can be obtained from the equations. This method was tested in Mikron UCP600 vertical machining center. The machining errors in the error-sensitive directions can be obtained by CMM inspection from the finished test piece to identify the kinematic errors of five-axis machine tool trunnion axis. Experimental results demonstrated that the proposed method can reduce the complexity, cost, and the time consumed substantially, and has a wider applicability. This paper proposes a new method of the machining tests for the trunnion axis of five-axis machine tool.

  12. Rotatable seal assembly. [Patent application; rotating targets

    DOEpatents

    Logan, C.M.; Garibaldi, J.L.

    1980-11-12

    An assembly is provided for rotatably supporting a rotor on a stator so that vacuum chambers in the rotor and stator remain in communication while the chambers are sealed from ambient air, which enables the use of a ball bearing or the like to support most of the weight of the rotor. The apparatus includes a seal device mounted on the rotor to rotate therewith, but shiftable in position on the rotor while being sealed to the rotor as by an O-ring. The seal device has a flat face that is biased towards a flat face on the stator, and pressurized air is pumped between the faces to prevent contact between them while spacing them a small distance apart to avoid the inflow of large amounts of air between the faces and into the vacuum chambers.

  13. Anisotropic turbulent thermal diffusion and thermal convection in a rapidly rotating fluid sphere

    NASA Astrophysics Data System (ADS)

    Ivers, D. J.; Phillips, C. G.

    2012-01-01

    Estimates of the molecular values of magnetic, viscous and thermal diffusion suggest that the state of the Earth's core is turbulent and that complete numerical simulation of the geodynamo is not realizable at present. Large eddy simulation of the geodynamo with modelling of the sub-grid scale turbulence must be used. Current geodynamo models effectively model the sub-grid scale turbulence with isotropic diffusivities larger than the molecular values appropriate for the core. In the Braginsky and Meytlis (1990) picture of core turbulence the thermal and viscous diffusivities are enhanced up to the molecular magnetic diffusivity in the directions of the rotation axis and mean magnetic field. We neglect the mean magnetic field herein to isolate the effects of anisotropic thermal diffusion, enhanced or diminished along the rotation axis, and explore the instability of a steady conductive basic state with zero mean flow in the Boussinesq approximation. This state is found to be more stable (less stable) as the thermal diffusion parallel to the rotation axis is increased (decreased), if the transverse thermal diffusion is fixed. To examine the effect of simultaneously varying the diffusion along and transverse to the rotation axis, the Frobenius norm is used to control for the total thermal diffusion. When the Frobenius norm of the thermal diffusion tensor is fixed, it is found that increasing the thermal diffusion parallel to the rotation axis is destabilising. This result suggests that, for a fixed total thermal diffusion, geodynamo codes with anisotropic thermal diffusion may operate at lower modified Rayleigh numbers.

  14. Rotating optical tubes for vertical transport of atoms

    NASA Astrophysics Data System (ADS)

    Al Rsheed, Anwar; Lyras, Andreas; Aldossary, Omar M.; Lembessis, Vassilis E.

    2016-12-01

    The classical dynamics of a cold atom trapped inside a vertical rotating helical optical tube (HOT) is investigated by taking also into account the gravitational field. The resulting equations of motion are solved numerically. The rotation of the HOT induces a vertical motion for an atom initially at rest. The motion is a result of the action of two inertial forces, namely, the centrifugal force and the Coriolis force. Both inertial forces force the atom to rotate in a direction opposite to that of the angular velocity of the HOT. The frequency and the turning points of the atom's global oscillation can be controlled by the value and the direction of the angular velocity of the HOT. However, at large values of the angular velocity of the HOT the atom can escape from the global oscillation and be transported along the axis of the HOT. In this case, the rotating HOT operates as an optical Archimedes' screw for atoms.

  15. Photoacoustic imaging with rotational compounding for improved signal detection

    NASA Astrophysics Data System (ADS)

    Forbrich, A.; Heinmiller, A.; Jose, J.; Needles, A.; Hirson, D.

    2015-03-01

    Photoacoustic microscopy with linear array transducers enables fast two-dimensional, cross-sectional photoacoustic imaging. Unfortunately, most ultrasound transducers are only sensitive to a very narrow angular acceptance range and preferentially detect signals along the main axis of the transducer. This often limits photoacoustic microscopy from detecting blood vessels which can extend in any direction. Rotational compounded photoacoustic imaging is introduced to overcome the angular-dependency of detecting acoustic signals with linear array transducers. An integrate system is designed to control the image acquisition using a linear array transducer, a motorized rotational stage, and a motorized lateral stage. Images acquired at multiple angular positions are combined to form a rotational compounded image. We found that the signal-to-noise ratio improved, while the sidelobe and reverberation artifacts were substantially reduced. Furthermore, the rotational compounded images of excised kidneys and hindlimb tumors of mice showed more structural information compared with any single image collected.

  16. Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Mehmed, Oral; Johnson, Dexter; Montague, Gerald; Duffy, Kirsten; Jansen, Ralph

    2005-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig is an apparatus for vibration testing of turbomachine blades in a vacuum at rotational speeds from 0 to 40,000 rpm. This rig includes (1) a vertically oriented shaft on which is mounted an assembly comprising a rotor holding the blades to be tested, (2) two actively controlled heteropolar radial magnetic bearings at opposite ends of the shaft, and (3) an actively controlled magnetic thrust bearing at the upper end of the shaft. This rig is a more capable successor to a prior apparatus, denoted the Dynamic Spin Rig (DSR), that included a vertically oriented shaft with a mechanical thrust bearing at the upper end and a single actively controlled heteropolar radial magnetic bearing at the lower end.

  17. Chaotic rotation of Hyperion?

    NASA Technical Reports Server (NTRS)

    Binzel, R. P.; Green, J. R.; Opal, C. B.

    1986-01-01

    Thomas et al. (1984) analyzed 14 Voyager 2 images of Saturn's satellite Hyperion and interpreted them to be consistent with a coherent (nonchaotic) rotation period of 13.1 days. This interpretation was criticized by Peale and Wisdom (1984), who argued that the low sampling frequency of Voyager data does not allow chaotic or nonchaotic rotation to be distinguished. New observations obtained with a higher sampling frequency are reported here which conclusively show that the 13.1 day period found by Thomas et al. was not due to coherent rotation.

  18. Method for Design Rotation

    DTIC Science & Technology

    1993-08-01

    desirability of a rotation as a function of the set of planar angles. Criteria for the symmetry of the design (such as the same set of factor levels for...P is -1. Hence there is no theoretical problem in obtaining rotations of a design; there are only the practical questions Why rotate a design? And...star points, which can be represented in a shorthand notation by the permutations of (±1,0, "’" , 0), and (c) factorial points, which are a two- level

  19. Hubble the Rotation of Uranus

    NASA Technical Reports Server (NTRS)

    1994-01-01

    These three NASA Hubble Space Telescope images of the planet Uranus reveal the motion of a pair of bright clouds in the planet's southern hemisphere, and a high altitude haze that forms a 'cap' above the planet's south pole.

    Hubble's new view was obtained on August 14, 1994, when Uranus was 1.7 billion miles (2.8 billion kilometers) from Earth. These atmospheric details were only previously seen by the Voyager 2 spacecraft, which flew by Uranus in 1986. Since then, detailed observations of Uranus's atmospheric features have not been possible because the planet is at the resolution limit of ground-based telescopes.

    Hubble's Wide Field Planetary Camera 2 observed Uranus through a filter that is sensitive to light reflected by a pair of high altitude clouds. This makes a high altitude haze over Uranus' south polar region clearly visible, along with a pair of high altitude clouds or plume-type features that are 2500 and 1800 miles (4300 and 3100 kilometers) across, respectively. This sequence of images shows how the clouds (labeled A and B) rotate with the planet during the three hours that elapsed between the first two observations (left and center picture) and the five hours that elapsed between the second pair of observations (center and right picture). Some cloud motion might be due to high altitude winds on the planet. (Observations are indicated in Universal Time.)

    By tracking the motion of high-altitude clouds, the new Hubble observations will allow astronomers to make new measurements of Uranus' rotation period. Based on the previous Voyager observations, Uranus spins on its axis at a faster rate than Earth does, completing one rotation every 7 hours, 14 minutes.

    One of the four gas giant planets of our solar system, Uranus is largely featureless. Unlike Earth, Uranus' south pole points toward the Sun during part of the planet's 84-year orbit. Thanks to its high resolution and ability to make observations over many years, Hubble can follow seasonal

  20. Precise Spatial Coding is Preserved Along the Longitudinal Hippocampal Axis

    PubMed Central

    Keinath, Alexander T.; Wang, Melissa E.; Wann, Ellen G.; Yuan, Robin K.; Dudman, Joshua T.; Muzzio, Isabel A.

    2015-01-01

    Compared with the dorsal hippocampus, relatively few studies have characterized neuronal responses in the ventral hippocampus. In particular, it is unclear whether and how cells in the ventral region represent space and/or respond to contextual changes. We recorded from dorsal and ventral CA1 neurons in freely moving mice exposed to manipulations of visuospatial and olfactory contexts. We found that ventral cells respond to alterations of the visuospatial environment such as exposure to novel local cues, cue rotations, and contextual expansion in similar ways to dorsal cells, with the exception of cue rotations. Furthermore, we found that ventral cells responded to odors much more strongly than dorsal cells, particularly to odors of high valence. Similar to earlier studies recording from the ventral hippocampus in CA3, we also found increased scaling of place cell field size along the longitudinal hippocampal axis. Although the increase in place field size observed toward the ventral pole has previously been taken to suggest a decrease in spatial information coded by ventral place cells, we hypothesized that a change in spatial scaling could instead signal a shift in representational coding that preserves the resolution of spatial information. To explore this possibility, we examined population activity using principal component analysis (PCA) and neural location reconstruction techniques. Our results suggest that ventral populations encode a distributed representation of space, and that the resolution of spatial information at the population level is comparable to that of dorsal populations of similar size. Finally, through the use of neural network modeling, we suggest that the redundancy in spatial representation along the longitudinal hippocampal axis may allow the hippocampus to overcome the conflict between memory interference and generalization inherent in neural network memory. Our results indicate that ventral population activity is well suited for

  1. Design of Off-Axis PIAACMC Mirrors

    NASA Technical Reports Server (NTRS)

    Pluzhnik, Eugene; Guyon, Olivier; Belikov, Ruslan; Kern, Brian; Bendek, Eduardo

    2015-01-01

    The Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) provides an efficient way to control diffraction propagation effects caused by the central obstruction/segmented mirrors of the telescope. PIAACMC can be optimized in a way that takes into account both chromatic diffraction effects caused by the telescope obstructed aperture and tip/tilt sensitivity of the coronagraph. As a result, unlike classic PIAA, the PIAACMC mirror shapes are often slightly asymmetric even for an on-axis configuration and require more care in calculating off-axis shapes when an off-axis configuration is preferred. A method to design off-axis PIAA mirror shapes given an on-axis mirror design is presented. The algorithm is based on geometrical ray tracing and is able to calculate off-axis PIAA mirror shapes for an arbitrary geometry of the input and output beams. The method is demonstrated using the third generation PIAACMC design for WFIRST-AFTA (Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets) telescope. Geometrical optics design issues related to the off-axis diffraction propagation effects are also discussed.

  2. Critical surface for explosions of rotational core-collapse supernovae

    SciTech Connect

    Iwakami, Wakana; Nagakura, Hiroki; Yamada, Shoichi

    2014-09-20

    The effect of rotation on the explosion of core-collapse supernovae is investigated systematically in three-dimensional simulations. In order to obtain the critical conditions for explosion as a function of mass accretion rate, neutrino luminosity, and specific angular momentum, rigidly rotating matter was injected from the outer boundary with an angular momentum, which is increased every 500 ms. It is found that there is a critical value of the specific angular momentum, above which the standing shock wave revives, for a given combination of mass accretion rate and neutrino luminosity, i.e., an explosion can occur by rotation even if the neutrino luminosity is lower than the critical value for a given mass accretion rate in non-rotational models. The coupling of rotation and hydrodynamical instabilities plays an important role in characterizing the dynamics of shock revival for the range of specific angular momentum that are supposed to be realistic. Contrary to expectations from past studies, the most rapidly expanding direction of the shock wave is not aligned with the rotation axis. Being perpendicular to the rotation axis on average, it can be oriented in various directions. Its dispersion is small when the spiral mode of the standing accretion shock instability (SASI) governs the dynamics, while it is large when neutrino-driven convection is dominant. As a result of the comparison between two-dimensional and three-dimensional rotational models, it is found that m ≠ 0 modes of neutrino-driven convection or SASI are important for shock revival around the critical surface.

  3. Method and apparatus for maintaining equilibrium in a helical axis stellarator

    DOEpatents

    Reiman, A.; Boozer, A.

    1984-10-31

    Apparatus for maintaining three-dimensional MHD equilibrium in a plasma contained in a helical axis stellarator includes a resonant coil system, having a configuration such that current therethrough generates a magnetic field cancelling the resonant magnetic field produced by currents driven by the plasma pressure on any given flux surface resonating with the rotational transform of another flux surface in the plasma. Current through the resonant coil system is adjusted as a function of plasma beta.

  4. Measured data for the Sandia 34-meter vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Ashwill, T. D.

    1992-07-01

    The 34-meter Test Bed is a research-oriented, variable-speed vertical-axis wind turbine located at the USDA Agricultural Research Station in Bushland, Texas. Sandia National Laboratories designed and built this machine to perform research in structural dynamics, aerodynamics, and fatigue. Testing to determine its performance in various wind conditions and rotation rates has been ongoing for over three years. This report documents a broad range of test data and includes comparisons to analytical results.

  5. Comparison of measured and calculated sound pressure levels around a large horizontal axis wind turbine generator

    NASA Technical Reports Server (NTRS)

    Shepherd, Kevin P.; Willshire, William L., Jr.; Hubbard, Harvey H.

    1989-01-01

    Results are reported from a large number of simultaneous acoustic measurements around a large horizontal axis downwind configuration wind turbine generator. In addition, comparisons are made between measurements and calculations of both the discrete frequency rotational harmonics and the broad band noise components. Sound pressure time histories and noise radiation patterns as well as narrow band and broadband noise spectra are presented for a range of operating conditions. The data are useful for purposes of environmental impact assessment.

  6. Method and apparatus for maintaining equilibrium in a helical axis stellarator

    DOEpatents

    Reiman, Allan; Boozer, Allen

    1987-01-01

    Apparatus for maintaining three-dimensional MHD equilibrium in a plasma contained in a helical axis stellerator includes a resonant coil system, having a configuration such that current therethrough generates a magnetic field cancelling the resonant magnetic field produced by currents driven by the plasma pressure on any given flux surface resonating with the rotational transform of another flux surface in the plasma. Current through the resonant coil system is adjusted as a function of plasma beta.

  7. Rotating mobile launcher

    NASA Technical Reports Server (NTRS)

    Gregory, T. J.

    1977-01-01

    Apparatus holds remotely piloted arm that accelerates until launching speed is reached. Then vehicle and counterweight at other end of arm are released simultaneously to avoid structural damage from unbalanced rotating forces.

  8. The Rotating Mirror.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1981-01-01

    Discusses theory of the rotating mirror, its use in measuring the velocity of the electrical signal in wires, and the velocity of light. Concludes with a description of the manometric flame apparatus developed for analyzing sound waves. (SK)

  9. Rotator Cuff Injuries

    MedlinePlus

    ... cuff are common. They include tendinitis, bursitis, and injuries such as tears. Rotator cuff tendons can become ... cuff depends on age, health, how severe the injury is, and how long you've had the ...

  10. Rotator cuff problems

    MedlinePlus

    Miller RH III, Azar FM, Throckmorton TW. Shoulder and elbow injuries. In: Canale ST, Beaty JH, eds. ... Krishnan SG. Rotator cuff and impingement lesions. In: Miller MD, Thompson SR, eds. DeLee and Drez's Orthopaedic ...

  11. Rotator cuff repair - slideshow

    MedlinePlus

    ... presentations/100229.htm Rotator cuff repair - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...

  12. The rotation of the halo of NGC 6822 from the radial velocities of carbon stars

    NASA Astrophysics Data System (ADS)

    Thompson, Graham P.; Ryan, Sean G.; Sibbons, Lisette F.

    2016-11-01

    Using spectra taken with the AAOmega spectrograph, we measure the radial velocities of over 100 stars, many of which are intermediate age carbon stars, in the direction of the dwarf irregular galaxy NGC 6822. Kinematic analysis suggests that the carbon stars in the sample are associated with NGC 6822, and estimates of its radial velocity and galactic rotation are made from a star-by-star analysis of its carbon star population. We calculate a heliocentric radial velocity for NGC 6822 of -51 ± 3 km s-1 and show that the population rotates with a mean rotation speed of 11.2 ± 2.1 km s-1 at a mean distance of 1.1 kpc from the galactic centre, about a rotation axis with a position angle of 26° ± 13°, as projected on the sky. This is close to the rotation axis of the H I gas disc and suggests that NGC 6822 is not a polar ring galaxy, but is dynamically closer to a late-type galaxy. However, the rotation axis is not aligned with the minor axis of the AGB isodensity profiles and this remains a mystery.

  13. Effect of Potato Orbits on Transport Properties Near the Axis in Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    Houlberg, W. A.; Shaing, K. C.

    1997-11-01

    Drift orbits near the magnetic axis are not concentric about the axis nor are their widths small compared to the local minor radius. The neoclassical viscosities in the NCLASS code (W.A. Houlberg, K.C. Shaing, S.P. Hirshman, M.C. Zarnstorff, to be published Phys. Plasmas.) have been modified to accomodate the effects of these `potato' orbits (K.C. Shaing, R.D. Hazeltine, M.C. Zarnstorff, Phys. Plasmas 4) (1997) 1371; 1375.. We show the effect of the potato modifications on the neoclassical electrical resistivity, bootstrap current, poloidal rotation and radial particle and heat fluxes near the magnetic axis in reversed shear plasmas. Electrical resistivity and radial transport are enhanced over their standard neoclassical values, but they are also more sensitive to orbit squeezing. The bootstrap current does not vanish, leading to the possibility that an axial seed current is not required for steady-state non-inductive operation.

  14. Rotator cuff injuries.

    PubMed

    Crusher, R H

    2000-07-01

    Different types of rotator cuff injuries frequently present to Accident and Emergency departments and minor injury units but can be difficult to differentiate clinically. This brief case study describes the examination and diagnosis of related shoulder injuries, specifically rotator cuff tears/disruption and calcifying supraspinatus tendinitis. The relevant anatomy and current therapies for these injuries is also discussed to enable the emergency nurse practitioner to have a greater understanding of the theory surrounding their diagnosis and treatments.

  15. Rotational rate sensor

    DOEpatents

    Hunter, Steven L.

    2002-01-01

    A rate sensor for angular/rotational acceleration includes a housing defining a fluid cavity essentially completely filled with an electrolyte fluid. Within the housing, such as a toroid, ions in the fluid are swept during movement from an excitation electrode toward one of two output electrodes to provide a signal for directional rotation. One or more ground electrodes within the housing serve to neutralize ions, thus preventing any effect at the other output electrode.

  16. Rotational spectrum of phenylglycinol

    NASA Astrophysics Data System (ADS)

    Simão, Alcides; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2014-11-01

    Solid samples of phenylglycinol were vaporized by laser ablation and investigated through rotational spectroscopy in a supersonic expansion using two different techniques: chirped pulse Fourier transform microwave spectroscopy and narrow band molecular beam Fourier transform microwave spectroscopy. One conformer, bearing an O-H···N and an N-H···π intramolecular hydrogen bonds, could be successfully identified by comparison of the experimental rotational and 14N nuclear quadruple coupling constants with those predicted theoretically.

  17. Rotating arc spark plug

    DOEpatents

    Whealton, John H.; Tsai, Chin-Chi

    2003-05-27

    A spark plug device includes a structure for modification of an arc, the modification including arc rotation. The spark plug can be used in a combustion engine to reduce emissions and/or improve fuel economy. A method for operating a spark plug and a combustion engine having the spark plug device includes the step of modifying an arc, the modifying including rotating the arc.

  18. Instability in Rotating Machinery

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The proceedings contain 45 papers on a wide range of subjects including flow generated instabilities in fluid flow machines, cracked shaft detection, case histories of instability phenomena in compressors, turbines, and pumps, vibration control in turbomachinery (including antiswirl techniques), and the simulation and estimation of destabilizing forces in rotating machines. The symposium was held to serve as an update on the understanding and control of rotating machinery instability problems.

  19. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  20. Joint representation of translational and rotational components of optic flow in parietal cortex

    PubMed Central

    Sunkara, Adhira; DeAngelis, Gregory C.; Angelaki, Dora E.

    2016-01-01

    Terrestrial navigation naturally involves translations within the horizontal plane and eye rotations about a vertical (yaw) axis to track and fixate targets of interest. Neurons in the macaque ventral intraparietal (VIP) area are known to represent heading (the direction of self-translation) from optic flow in a manner that is tolerant to rotational visual cues generated during pursuit eye movements. Previous studies have also reported that eye rotations modulate the response gain of heading tuning curves in VIP neurons. We tested the hypothesis that VIP neurons simultaneously represent both heading and horizontal (yaw) eye rotation velocity by measuring heading tuning curves for a range of rotational velocities of either real or simulated eye movements. Three findings support the hypothesis of a joint representation. First, we show that rotation velocity selectivity based on gain modulations of visual heading tuning is similar to that measured during pure rotations. Second, gain modulations of heading tuning are similar for self-generated eye rotations and visually simulated rotations, indicating that the representation of rotation velocity in VIP is multimodal, driven by both visual and extraretinal signals. Third, we show that roughly one-half of VIP neurons jointly represent heading and rotation velocity in a multiplicatively separable manner. These results provide the first evidence, to our knowledge, for a joint representation of translation direction and rotation velocity in parietal cortex and show that rotation velocity can be represented based on visual cues, even in the absence of efference copy signals. PMID:27095846

  1. Stellar structures and the enigma of pulsars rotation frequency decay

    NASA Astrophysics Data System (ADS)

    de Oliveira, H. O.; Marinho, R. M., Jr.; Maglhaes, N. S.

    2015-07-01

    Pulsars are astrophysical objects normally modelled as compact neutron stars that originated from the collapse of another star. This model, that we name canonical, assumes that pulsars are described by spherical magnetized dipoles that rotate, usually with the magnetic axis misaligned to the rotation axis. This misalignment would be responsible for the observation of radiation emitted in well-defined time intervals in a certain direction (lighthouse effect), the typical observational characteristic of this kind of star. It has been noticed that the rotation frequency of pulsars is slowly decaying with time (spin down), implying a gradual decrease of the rotational angular velocity (Ω). Such decay can be quantified by a dimensionless parameter called “braking index” (“n”), given by n = ΩΩ/(Ω)2, where a dot indicates a time derivative. The canonical model predicts that this index has one only value for all pulsars, equal to three. However, observational data indicate that actual braking indices are less than three, representing an enigma. The main goal of this research is the exploration of a more precise model for pulsars’ rotation frequency decay.

  2. Rimming flows and pattern formation inside rapidly rotating cylinder

    NASA Astrophysics Data System (ADS)

    Polezhaev, Denis; Dyakova, Veronika; Kozlov, Victor

    2014-11-01

    The dynamics of fluid and granular medium in a rotating horizontal cylinder is experimentally studied. In a rapidly rotating cylinder liquid and granular medium coat the cylindrical wall under centrifugal force. In the cavity frame gravity field performs rotation and produces oscillatory fluid flow which is responsible for the series of novel effects of pattern formation, namely, axial segregation of heavy particles and pattern formation in the form of sand regular hills extended along the axis of rotation. At least two types of axial segregation are found: a) patterns of spatial period of the same order of magnitude as fluid layer thickness which induced by steady flows generated by inertial waves; b) fine patterns which manifests Gortler - Taylor vortices developing as a consequence of centrifugal instability of viscous boundary layer near the cylindrical wall. Under gravity, intensive fluid shear flow induces partial fluidization of annular layer of granular medium. The oscillatory motion is followed by onset of regular ripples extended along the axis of rotation. The work is supported by Russian Scientific Foundation (project 14-11-00476).

  3. Conversion of rotational output to linear force-a transmission

    SciTech Connect

    Montalbano, P.J.

    1991-08-27

    This patent describes a transmission device for converting rotational torque into linear force. It comprises a combination large internally toothed annular gear and large flywheel rotatable within a housing by bearing means, in operative interconnection with a small externally toothed circular gear mounted within it annulus and provided with a source of variable rotary motion for driving the annular gear, a second large internally toothed annular gear, located above the first the annular gear, rotatable within a housing by bearing means and provided with a clutch connection to first annular gear, is in operative connection with three small externally toothed circular gears driven by the second annular gear, a member pivotably supported along the axis of the annular gear and rockable on the axis, the member having an upper and a lower arm, the upper arm in interconnection with two of the respective gears and the lower arm in interconnection with one of the respective gears, the gears driven by the second annular gear, in upper arm the gears causing the rocker element to move two off- centered weights, the first weight rotatable with one of the gears, the second weight rotatable in the opposite direction and mounted within the rocker element driven by an additional small externally toothed circular gear in mesh with one of the small gears, the weights generating centrifugal forces.

  4. Counter-Rotatable Fan Gas Turbine Engine with Axial Flow Positive Displacement Worm Gas Generator

    NASA Technical Reports Server (NTRS)

    Giffin, Rollin George (Inventor); Murrow, Kurt David (Inventor); Fakunle, Oladapo (Inventor)

    2014-01-01

    A counter-rotatable fan turbine engine includes a counter-rotatable fan section, a worm gas generator, and a low pressure turbine to power the counter-rotatable fan section. The low pressure turbine maybe counter-rotatable or have a single direction of rotation in which case it powers the counter-rotatable fan section through a gearbox. The gas generator has inner and outer bodies having offset inner and outer axes extending through first, second, and third sections of a core assembly. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes and extending radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. A combustor section extends through at least a portion of the second section.

  5. Rotational Spectrum of Sarin

    NASA Astrophysics Data System (ADS)

    Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel

    2001-05-01

    As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C4H10FO2P) was observed in the rotationally cold (Trot<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1σ), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm-1. Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G** level of theory is consistent with our experimental findings.

  6. Balanced-Rotating-Spray Tank-And-Pipe-Cleaning System

    NASA Technical Reports Server (NTRS)

    Thaxton, Eric A.; Caimi, Raoul E. B.

    1995-01-01

    Spray head translates and rotates to clean entire inner surface of tank or pipe. Cleansing effected by three laterally balanced gas/liquid jets from spray head that rotates about longitudinal axis. Uses much less liquid. Cleaning process in system relies on mechanical action of jets instead of contaminant dissolution. Eliminates very difficult machining needed to make multiple converging/diverging nozzles within one spray head. Makes nozzle much smaller. Basic two-phase-flow, supersonic-nozzle design applied to other spray systems for interior or exterior cleaning.

  7. Vibration Problems of Rotating Machinery due to Coupling Misalignments

    DTIC Science & Technology

    1988-05-01

    These configurations can be seen in figures 2-4a and 2-4b. A rotor can be bowed for a variety of reasons. In steam turbines Improper heating or cooling of... rotor outside its design orbit can cause collision of close tolerance components as in the vanes of steam and gas turbines leading to total destruction...shaft bent such that the centroid of mass of the rotor does not lie on the axis of rotation is analytically the same as an unbalanced rotating disk

  8. MHD Turbulence Sheared in Fixed and Rotating Frames

    NASA Technical Reports Server (NTRS)

    Kassinos, S. C.; Knaepen, B.; Wray, A.

    2004-01-01

    We consider homogeneous turbulence in a conducting fluid that is exposed to a uniform external magnetic field while being sheared in fixed and rotating frames. We take both the frame-rotation axis and the applied magnetic field to be aligned in the direction normal to the plane of the mean shear. Here a systematic parametric study is carried out in a series of Direct Numerical Simulations (DNS) in order to clarify the main effects determining the structural anisotropy and stability of the flow.

  9. Rotation-vibration states of H3+ at dissociation

    NASA Astrophysics Data System (ADS)

    Kostin, Maxim A.; Polyansky, Oleg L.; Tennyson, Jonathan; Mussa, Hamse Y.

    2003-02-01

    Calculations are presented which estimate energies for all the bound rotation-vibration energy levels of H3+ with rotation angular momentum J=0, 2 and 8. The calculations, which use Radau coordinates with z-axis of the molecule embedded perpendicular to the molecular plane, are performed on 128 nodes of a massively parallel computer. It is found that convergence with respect to basis set size of the higher J states is fairly slow and that further improvements are beyond the capabilities of the current computational set-up.

  10. The stability of differentially rotating self-gravitating gas clouds. II - Polytropic configurations

    NASA Astrophysics Data System (ADS)

    Schmitz, F.; Ebert, R.

    1987-07-01

    The stability of differentially rotating gas clouds with polytropic equations of state is investigated. The equilibrium states are self-consistent. The structure of the infinitely extended configurations is very simple. Perpendicular to the rotation axis, the density distribution and the differential rotational velocity are described by power laws. In the limit of vanishing rotation the authors obtain the familiar polytropic gas spheres. Only marginal axisymmetric perturbations are considered. The structure of the equilibrium states and the form of the perturbations are both calculated with the approximation method presented in paper I.

  11. Review of wind simulation methods for horizontal-axis wind turbine analysis

    NASA Astrophysics Data System (ADS)

    Powell, D. C.; Connell, J. R.

    1986-06-01

    This report reviews three reports on simulation of winds for use in wind turbine fatigue analysis. The three reports are presumed to represent the state of the art. The Purdue and Sandia methods simulate correlated wind data at two points rotating as on the rotor of a horizontal-axis wind turbine. The PNL method at present simulates only one point, which rotates either as on a horizontal-axis wind turbine blade or as on a vertical-axis wind turbine blade. The spectra of simulated data are presented from the Sandia and PNL models under comparable input conditions, and the energy calculated in the rotational spikes in the spectra by the two models is compared. Although agreement between the two methods is not impressive at this time, improvement of the Sandia and PNL methods is recommended as the best way to advance the state of the art. Physical deficiencies of the models are cited in the report and technical recommendations are made for improvement. The report also reviews two general methods for simulating single-point data, called the harmonic method and the white noise method. The harmonic method, which is the basis of all three specific methods reviewed, is recommended over the white noise method in simulating winds for wind turbine analysis.

  12. Rotation and particle loss in Tore Supra

    SciTech Connect

    R.B. White; F.W. Perkins; X. Garbet; C. Bourdelle; et al

    2000-06-13

    Although plasma heating with ICRF imparts negligible angular momentum to a tokamak plasma, the high energy particles give significant torque to the plasma through diamagnetic effects. This effect has been directly modeled through guiding center simulations. It is found that heating in Tore Supra, with the location of the resonance surface on the high field side of the magnetic axis, can produce negative central rotation of up to 40 km/sec. Particle loss also contributes to negative rotation, but this is not the dominant effect in most discharges. In this work the authors examine the effect of collisions and strong plasma rotation on the loss of high energy particles. Magnetic field strength variation due to discrete toroidal field coils, or ripple, produces two important loss channels in tokamaks. The trapping of particles in local ripple wells produces super banana orbits and, in the case of strong ripple, direct loss orbits leading to the plasma edge. These particles leave the device in the direction of vertical drift, and are characterized by small values of parallel velocity, or pitch. Ripple also causes high energy particles in banana orbits to diffuse stochastically, leading to banana orbits which impact the wall near the outer midplane. Both these loss processes are modified by the magnitude of the collision rate, and by plasma rotation. In Tore Supra the magnitude of the ripple makes ripple trapping a dominant loss mechanism for the background plasma as well as for ICRF produced non Maxwellian high energy tails. The authors have examined the loss as a function of collisionality and rotation using the Hamiltonian guiding center code ORBIT.

  13. Rotational Spectroscopy of 4-HYDROXY-2-BUTYNENITRILE

    NASA Astrophysics Data System (ADS)

    Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2015-06-01

    Recently we studied the rotational spectrum of hydroxyacetonitrile (HOCH_2CN, HAN) in order to provide a firm basis for its possible detection in the interstellar medium Different plausible pathways of the formation of HAN in the interstellar conditions were proposed; however, up to now, the searches for this molecule were unsuccessful. To continue the study of nitriles that represent an astrophysical interest we present in this talk the analysis of the rotational spectrum of 4-hydroxy-2-butynenitrile (HOCH_2CC-CN, HBN), the next molecule in the series of hydroxymethyl nitriles. Using the Lille spectrometer the spectrum of HBN was measured in the frequency range 50 -- 500 GHz. From the spectroscopic point of view HBN molecule is rather similar to HAN, because of -OH group tunnelling in gauche conformation. As it was previously observed for HAN, due to this large amplitude motion, the splittings in the rotational spectra of HBN are easily resolved making the spectral analysis more difficult. Additional difficulties arise from the near symmetric top character of HBN (κ = -0.996), and very dense spectrum because of relatively small values of rotational constants and a number of low-lying excited vibrational states. The analysis carried out in the frame of reduced axis system approach of Pickett allows to fit within experimental accuracy all the rotational transitions in the ground vibrational state. Thus, the results of the present study provide a reliable catalog of frequency predictions for HBN. The support of the Action sur Projets de l'INSU PCMI, and ANR-13-BS05-0008-02 IMOLABS is gratefully acknowledged Margulès L., Motiyenko R.A., Guillemin J.-C. 68th ISMS, 2013, TI12. Danger G. et al. Phys. Chem. Chem. Phys. 2014, 16, 3360. Pickett H.M. J. Chem. Phys. 1972, 56, 1715.

  14. Rotating Bullets from A Variable Protostar

    NASA Astrophysics Data System (ADS)

    Chen, Xuepeng; Arce, Héctor G.; Zhang, Qizhou; Launhardt, Ralf; Henning, Thomas

    2016-06-01

    We present Submillimeter Array (SMA) CO (2-1) observations toward the protostellar jet driven by SVS 13 A, a variable protostar in the NGC 1333 star-forming region. The SMA CO (2-1) images show an extremely high-velocity jet composed of a series of molecular “bullets.” Based on the SMA CO observations, we discover clear and large systematic velocity gradients, perpendicular to the jet axis, in the blueshifted and redshifted bullets. After discussing several alternative interpretations, such as twin-jets, jet precession, warped disk, and internal helical shock, we suggest that the systematic velocity gradients observed in the bullets result from the rotation of the SVS 13 A jet. From the SMA CO images, the measured rotation velocities are 11.7-13.7 km s-1 for the blueshifted bullet and 4.7 ± 0.5 km s-1 for the redshifted bullet. The estimated specific angular momenta of the two bullets are comparable to those of dense cores, about 10 times larger than those of protostellar envelopes, and about 20 times larger than those of circumstellar disks. If the velocity gradients are due to the rotation of the SVS 13 A jet, the significant amount of specific angular momenta of the bullets indicates that the rotation of jets/outflows is a key mechanism to resolve the so-called “angular momentum problem” in the field of star formation. The kinematics of the bullets suggests that the jet launching footprint on the disk has a radius of ˜7.2-7.7 au, which appears to support the extended disk-wind model. We note that further observations are needed to comprehensively understand the kinematics of the SVS 13 A jet, in order to confirm the rotation nature of the bullets.

  15. Factors determining the spin axis of a pitched fastball in baseball.

    PubMed

    Jinji, Tsutomu; Sakurai, Shinji; Hirano, Yuichi

    2011-04-01

    In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000 Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.

  16. Evaluation of Distal Femoral Rotational Alignment with Spiral CT Scan before Total Knee Arthroplasty (A Study in Iranian population)

    PubMed Central

    Jabalameli, Mahmoud; Moradi, Amin; Bagherifard, Abolfazl; Radi, Mehran; Mokhtari, Tahmineh

    2016-01-01

    Background: Evaluating the landmarks for rotation of the distal femur is a challenge for orthopedic surgeons. Although the posterior femoral condyle axis is a good landmark for surgeons, the surgical transepicondylar axis may be a better option with the help of preoperative CT scanning. The purpose of this study was to ascertain relationships among the axes’ guiding distal femur rotational alignment in preoperative CT scans of Iranian patients who were candidates for total knee arthroplasty and the effects of age, gender, and knee alignment on these relationships. Methods: One hundred and eight cases who were admitted to two university hospitals for total knee arthroplasty were included in this study. The rotation of the distal femur was evaluated using single axial CT images through the femoral epicondyle. Four lines were drawn digitally in this view: anatomical and surgical transepicondylar axes, posterior condylar axis and the Whiteside anteroposterior line. The alignment of the extremity was evaluated in the standing alignment view. Then the angles were measured along these lines and their relationship was evaluated. Results: The mean angle between the anatomical transepicondylar axis and posterior condylar axis and between the surgical transepicondylar axis and posterior condylar axis were 5.9 ± 1.6 degrees and 1.6±1.7 degrees respectively. The mean angle between the Whiteside’s anteroposterior line and the line perpendicular to the posterior condylar axis was 3.7±2.1 degrees. Significant differences existed between the two genders in these relationships. No significant correlation between the age of patients and angles of the distal femur was detected. The anatomical surgical transepicondylar axis was in 4.3 degrees external rotation in relation to the surgical transepicondylar axis. Conclusion: Preoperative CT scanning can help accurately determine rotational landmarks of the distal femur. If one of the reference axes cannot be determined, other

  17. Vertical axis wind turbine. Final report

    SciTech Connect

    Hollrock, R.H.

    1983-06-01

    The work reported consisted of the fabrication and whirl testing of a vertical axis wind turbine. Problems are reported in blade fabrication and balancing. It is planned to provide speed control with a water agitator. (LEW)

  18. Vertical Axis Wind Turbine Foundation parameter study

    SciTech Connect

    Lodde, P.F.

    1980-07-01

    The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

  19. On the flow between a rotating and a coaxial fixed disc - Numerical validation of the radial similarity hypothesis

    NASA Astrophysics Data System (ADS)

    Oliveira, L. A.; Pecheux, J.; Restivo, A. O.

    1991-06-01

    The rotating flow between coaxial disks in a radially confined geometry is studied by numerical integration of the full Navier-Stokes equations. The results indicate that both Batchelor's and Stewartson's flow structures can be observed near the axis of rotation, depending on what conditions are set at the peripheral boundary.

  20. Using the Anatomical Axis as an Alternative to the Mechanical Axis to Assess Knee Alignment.

    PubMed

    Tipton, Shane C; Sutherland, John; Schwarzkopf, Ran

    2015-12-01

    The treatment of knee osteoarthritis and the preparation for total knee arthroplasty require repetitive imaging to guide preoperative planning and operative technique. Full-length standing anteroposterior images are the gold standard in assessing the alignment of the limb via the measurement of the mechanical axis of the knee. The anatomical axis can be obtained from a more limited image of the knee, and as such is less expensive and exposes the patient to less ionizing radiation. The objective of this cross-sectional prospective study was to examine the extent to which the anatomical axis measured on a fixed-flexed posteroanterior (Rosenberg view) radiograph correlates with the mechanical axis. The data of 209 total knee arthroplasty radiographs were analyzed to compare the preoperative correlation between the mechanical and anatomical axis. The anatomical axis correlated with the mechanical axis when it was measured from both the standing full-length anteroposterior radiograph and from a fixed-flexed posteroanterior radiograph. Using an angle of offset found from linear regression, these correlations become closer. Body mass index and Kellgren-Lawrence grade were not found to have a significant effect. It is the conclusion of this study that the anatomical axis, as measured from a limited knee radiography, may serve as a plausible estimate of the mechanical axis when done with a neutral angle of offset, and that offset angle depends on gender and the imaging technique used to determine the anatomical axis.

  1. Rotating superconductor magnet for producing rotating lobed magnetic field lines

    DOEpatents

    Hilal, Sadek K.; Sampson, William B.; Leonard, Edward F.

    1978-01-01

    This invention provides a rotating superconductor magnet for producing a rotating lobed magnetic field, comprising a cryostat; a superconducting magnet in the cryostat having a collar for producing a lobed magnetic field having oppositely directed adjacent field lines; rotatable support means for selectively rotating the superconductor magnet; and means for energizing the superconductor magnet.

  2. Off-axis illumination of lithography tool

    NASA Astrophysics Data System (ADS)

    Xing, Han; Lin, Li; Bin, Ma

    2013-12-01

    Lithography tool is a necessary part for LSI and VLSI. The illumination system design is an important part in the lithography optical system design. Off-axis illumination technology is an effective way to reducing resolution of lithography. The paper introduction the basic components of lithography tool, the principle of off-axis illumination reducing the resolution of lithography and focus on the two implementations of OAI technology, finally point out advantages and disadvantage of the two implementations.

  3. Giant-cell granuloma of the axis.

    PubMed

    González-Martínez, Emilio; Santamarta, David; Lomas-García, Jesús; Ibáñez-Plágaro, F Javier; Fernández-Fernández, J Javier; Ariño, Teresa Ribas; García-Cosamalón, José

    2012-02-01

    Giant-cell granuloma is a benign and nonneoplastic lesion with an expansive and locally destructive behavior. It typically involves the mandible and the maxilla. Only 1 case arising from the odontoid process of the axis has been reported previously. The authors report on a 64-year-old man with a giant-cell granuloma of the axis. They review this uncommon entity, emphasizing the complexity of differentiating between this lesion and other giant-cell tumors.

  4. Responses of pigeon vestibulocerebellar neurons to optokinetic stimulation. II. The 3-dimensional reference frame of rotation neurons in the flocculus.

    PubMed

    Wylie, D R; Frost, B J

    1993-12-01

    1. The complex spike activity of Purkinje cells in the flocculus in response to rotational flowfields was recorded extracellularly in anesthetized pigeons. 2. The optokinetic stimulus was produced by a rotating "planetarium projector." A light source was placed in the center of a tin cylinder, which was pierced with numerous small holes. A pen motor oscillated the cylinder about its long axis. This apparatus was placed above the bird's head and the resultant rotational flow-field was projected onto screens that surrounded the bird on all four sides. The axis of rotation of the planetarium could be oriented to any position in three-dimensional space. 3. Two types of responses were found: vertical axis (VA; n = 43) neurons responded best to visual rotation about the vertical axis, and H-135i neurons (n = 34) responded best to rotation about a horizontal axis. The preferred orientation of the horizontal axis was at approximately 135 degrees ipsilateral azimuth. VA neurons were excited by rotation about the vertical axis producing forward (temporal to nasal) and backward motion in the ipsilateral and contralateral eyes, respectively, and were inhibited by rotation in the opposite direction. H-135i neurons in the left flocculus were excited by counterclockwise rotation about the 135 degrees ipsilateral horizontal axis and were inhibited by clockwise motion. Thus, the VA and H-135i neurons, respectively, encode visual flowfields resulting from head rotations stimulating the ipsilateral horizontal and ipsilateral anterior semicircular canals. 4. Sixty-seven percent of VA and 80% of H-135i neurons had binocular receptive fields, although for most binocular cells the ipsilateral eye was dominant. Binocular stimulation resulted in a greater depth of modulation than did monocular stimulation of the dominant eye for 69% of the cells. 5. Monocular stimulation of the VA neurons revealed that the best axis for the contralateral eye was tilted back 11 degrees, on average, to the

  5. The Inhibition of the Rayleigh-Taylor Instability by Rotation.

    PubMed

    Baldwin, Kyle A; Scase, Matthew M; Hill, Richard J A

    2015-07-01

    It is well-established that the Coriolis force that acts on fluid in a rotating system can act to stabilise otherwise unstable flows. Chandrasekhar considered theoretically the effect of the Coriolis force on the Rayleigh-Taylor instability, which occurs at the interface between a dense fluid lying on top of a lighter fluid under gravity, concluding that rotation alone could not stabilise this system indefinitely. Recent numerical work suggests that rotation may, nevertheless, slow the growth of the instability. Experimental verification of these results using standard techniques is problematic, owing to the practical difficulty in establishing the initial conditions. Here, we present a new experimental technique for studying the Rayleigh-Taylor instability under rotation that side-steps the problems encountered with standard techniques by using a strong magnetic field to destabilize an otherwise stable system. We find that rotation about an axis normal to the interface acts to retard the growth rate of the instability and stabilise long wavelength modes; the scale of the observed structures decreases with increasing rotation rate, asymptoting to a minimum wavelength controlled by viscosity. We present a critical rotation rate, dependent on Atwood number and the aspect ratio of the system, for stabilising the most unstable mode.

  6. Engineering Implications of Rotational Sensitivity of Translational Accelerometers

    NASA Astrophysics Data System (ADS)

    Boroschek, R. L.

    2006-12-01

    Several studies have indicated that nominal linear translational accelerometers are strongly sensitive to rotation motions, especially around their horizontal axis. It has been theoretically and experimentally demonstrated that this situation affects the acceleration record and severely limits appropriate velocity and displacement determination. More importantly the common believe that filtering long periods signals could "clean" the acceleration record from this unwanted effect has been shown inadequate by the author this abstract and collaborators using experimental testing. Rotational effects are still present on filtered records unless the complete frequency bandwidth that composes the rotation motion is filtered out. In civil engineering structures rotations are nearly always present. Typical examples are foundation rocking, beam bending, floor slab deformation and overall rotation of structures due to relative large loads or damage. Two real cases were rotation of a relative flexible structure strongly influence the linear accelerometer responses are presented and later experimentally reproduce in a shake table controlled situation. The first one corresponds to a bridge with a contiguous 383 meter simple supported beam rested on rubber bearing that suffered the rotational related distortions due to the passing of a heavy truck at the end of a seismic event. The second event corresponds to the vibration recording of vertical motions on an industrial bridge that is exposed to forced vibration of a large motor. Both examples indicate that in certain conditions motion records from structural instruments are subjected to distortions effects that could make acceleration, velocity and displacement (temporarily or permanent) measurements not reliable.

  7. The Inhibition of the Rayleigh-Taylor Instability by Rotation

    PubMed Central

    Baldwin, Kyle A.; Scase, Matthew M.; Hill, Richard J. A.

    2015-01-01

    It is well-established that the Coriolis force that acts on fluid in a rotating system can act to stabilise otherwise unstable flows. Chandrasekhar considered theoretically the effect of the Coriolis force on the Rayleigh-Taylor instability, which occurs at the interface between a dense fluid lying on top of a lighter fluid under gravity, concluding that rotation alone could not stabilise this system indefinitely. Recent numerical work suggests that rotation may, nevertheless, slow the growth of the instability. Experimental verification of these results using standard techniques is problematic, owing to the practical difficulty in establishing the initial conditions. Here, we present a new experimental technique for studying the Rayleigh-Taylor instability under rotation that side-steps the problems encountered with standard techniques by using a strong magnetic field to destabilize an otherwise stable system. We find that rotation about an axis normal to the interface acts to retard the growth rate of the instability and stabilise long wavelength modes; the scale of the observed structures decreases with increasing rotation rate, asymptoting to a minimum wavelength controlled by viscosity. We present a critical rotation rate, dependent on Atwood number and the aspect ratio of the system, for stabilising the most unstable mode. PMID:26130005

  8. Sex differences in the HPA axis.

    PubMed

    Goel, Nirupa; Workman, Joanna L; Lee, Tiffany T; Innala, Leyla; Viau, Victor

    2014-07-01

    The hypothalamic-pituitary-adrenal (HPA) axis is a major component of the systems that respond to stress, by coordinating the neuroendocrine and autonomic responses. Tightly controlled regulation of HPA responses is critical for maintaining mental and physical health, as hyper- and hypo-activity have been linked to disease states. A long history of research has revealed sex differences in numerous components of the HPA stress system and its responses, which may partially form the basis for sex disparities in disease development. Despite this, many studies use male subjects exclusively, while fewer reports involve females or provide direct sex comparisons. The purpose of this article is to present sex comparisons in the functional and molecular aspects of the HPA axis, through various phases of activity, including basal, acute stress, and chronic stress conditions. The HPA axis in females initiates more rapidly and produces a greater output of stress hormones. This review focuses on the interactions between the gonadal hormone system and the HPA axis as the key mediators of these sex differences, whereby androgens increase and estrogens decrease HPA activity in adulthood. In addition to the effects of gonadal hormones on the adult response, morphological impacts of hormone exposure during development are also involved in mediating sex differences. Additional systems impinging on the HPA axis that contribute to sex differences include the monoamine neurotransmitters norepinephrine and serotonin. Diverse signals originating from the brain and periphery are integrated to determine the level of HPA axis activity, and these signals are, in many cases, sex-specific.

  9. Diversity and Determinants of the Three-dimensional Anatomical Axis of the Heart as Revealed Using Multidetector-row Computed Tomography.

    PubMed

    Mori, Shumpei; Anderson, Robert H; Tahara, Natsuko; Izawa, Yu; Toba, Takayoshi; Fujiwara, Sei; Shimoyama, Shinsuke; Watanabe, Yoshiaki; Nishii, Tatsuya; Kono, Atsushi K; Hirata, Ken-Ichi

    2017-02-08

    The location of the heart within the thorax varies significantly between individuals. The resultant diversity of the anatomical cardiac long axis, however, and its determinants, have yet to be systematically investigated. We enrolled 100 consecutive patients undergoing coronary arterial computed tomographic angiography, decomposing the vector of the anatomical cardiac long axis by projecting it to horizontal, frontal, and sagittal planes. The projected vectors on each plane were then converted into three rotation angles using coordinate transformation. We then measured the extent of aortic wedging, using the vertical distance between the inferior margins of the non-adjacent aortic sinus and the epicardium. We took the aortic root rotation angle to be zero when an "en face" view of the right coronary aortic sinus was obtained in the frontal view, defining leftward rotation to be positive. The mean horizontal, frontal, and sagittal rotation angles were 48.7° ± 9.5°, 52.3° ± 12.0°, and 34.0° ± 11.2°, respectively. The mean extent of aortic wedging, and the aortic root rotation angle, were 42.7 ± 9.8 mm, and 5.3° ± 16.4°. Horizontal rotation of the anatomical axis was associated with leftward and ventral rotation, and vice versa. Multivariate analysis showed aortic root rotation to be associated with horizontal cardiac rotation, while aortic wedging is associated with frontal and sagittal cardiac rotation. We have quantified the marked individual variation observed in the anatomical axis of the living heart, identifying the different mechanisms involved in producing the marked three-dimensional diversity of the living heart. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc.

  10. An event database for rotational seismology

    NASA Astrophysics Data System (ADS)

    Salvermoser, Johannes; Hadziioannou, Celine; Hable, Sarah; Chow, Bryant; Krischer, Lion; Wassermann, Joachim; Igel, Heiner

    2016-04-01

    The ring laser sensor (G-ring) located at Wettzell, Germany, routinely observes earthquake-induced rotational ground motions around a vertical axis since its installation in 2003. Here we present results from a recently installed event database which is the first that will provide ring laser event data in an open access format. Based on the GCMT event catalogue and some search criteria, seismograms from the ring laser and the collocated broadband seismometer are extracted and processed. The ObsPy-based processing scheme generates plots showing waveform fits between rotation rate and transverse acceleration and extracts characteristic wavefield parameters such as peak ground motions, noise levels, Love wave phase velocities and waveform coherence. For each event, these parameters are stored in a text file (json dictionary) which is easily readable and accessible on the website. The database contains >10000 events starting in 2007 (Mw>4.5). It is updated daily and therefore provides recent events at a time lag of max. 24 hours. The user interface allows to filter events for epoch, magnitude, and source area, whereupon the events are displayed on a zoomable world map. We investigate how well the rotational motions are compatible with the expectations from the surface wave magnitude scale. In addition, the website offers some python source code examples for downloading and processing the openly accessible waveforms.

  11. Geometrical theory of aberrations near the axis in classical off-axis reflecting telescopes.

    PubMed

    Chang, Seunghyuk; Prata, Aluizio

    2005-11-01

    A geometrical theory of aberrations for the vicinity of the focus of arbitrary off-axis sections of conic mirrors is derived. It is shown that an off-axis conic mirror introduces linear astigmatism in the image. However, in classical two-mirror telescopes this aberration can be eliminated by tilting the secondary parent mirror axis. It is also shown that the practical geometrical-optics performance of a classical off-axis two-mirror telescope with no linear astigmatism is equivalent to the performance of an on-axis system, proving that both systems have identical third-order coma. To demonstrate the applicability of the theory developed in a practical system, a fast (i.e., f/2), compact, obstruction-free classical off-axis Cassegrain telescope is designed.

  12. The rotate-plus-shift C-arm trajectory: complete CT data with limited angular rotation

    NASA Astrophysics Data System (ADS)

    Ritschl, Ludwig; Kuntz, Jan; Kachelrieß, Marc

    2015-03-01

    In the last decade C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm scan is performed using a circle-like trajectory around a region of interest. Therefor an angular range of at least 180° plus fan-angle must be covered to ensure a completely sampled data set. This fact defines some constraints on the geometry and technical specifications of a C-arm system, for example a larger C radius or a smaller C opening respectively. These technical modifications are usually not beneficial in terms of handling and usability of the C-arm during classical 2D applications like fluoroscopy. The method proposed in this paper relaxes the constraint of 180° plus fan-angle rotation to acquire a complete data set. The proposed C-arm trajectory requires a motorization of the orbital axis of the C and of ideally two orthogonal axis in the C plane. The trajectory consists of three parts: A rotation of the C around a defined iso-center and two translational movements parallel to the detector plane at the begin and at the end of the rotation. Combining these three parts to one trajectory enables for the acquisition of a completely sampled dataset using only 180° minus fan-angle of rotation. To evaluate the method we show animal and cadaver scans acquired with a mobile C-arm prototype. We expect that the transition of this method into clinical routine will lead to a much broader use of intraoperative 3D imaging in a wide field of clinical applications.

  13. The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds’ Search Performance in Spatial Rotation Tasks

    PubMed Central

    Ebersbach, Mirjam; Nawroth, Christian

    2016-01-01

    Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children. PMID:27812346

  14. Algorithm for IAU north poles and rotation parameters

    NASA Technical Reports Server (NTRS)

    Lieske, J. H.

    1993-01-01

    In 1970 the International Astronomical Union (IAU) defined any object's north pole to be that axis of rotation which lies north of the solar system's invariable plane. A competing definition in widespread use at some institutions followed the 'right hand rule' whereby the 'north' axis of rotation was generally said to be that of the rotational angular momentum. In the case of the latter definition, the planet Neptune and its satellite Triton would have their 'north' poles in opposite hemispheres because Triton's angular momentum vector is in the hemisphere opposite from that of Neptune's rotation angular momentum. The IAU resolutions have been somewhat controversial in some quarters ever since their adoption. A Working Group has periodically updated the recommended values of planet and satellite poles and rotation rates in accordance with the IAU definition of north and the IAU definition of prime meridian. Neither system is completely satisfactory in the perception of all scientists, and some confusion has been generated by publishing data in the two different systems. In this paper we review the IAU definitions of north and of the location of prime meridian and we present the algorithm which has been employed in determining the rotational parameters of the natural satellites. The IAU definition of the prime meridian contains some ambiguities which in practice have been 'specified' by the numerical values published by the IAU working group but which have not yet been explicitly documented. The purpose of this paper is to explicitly document the algorithm employed by the IAU working group in specifying satellite poles and rotation rates.

  15. STRUCTURE OF UNIFORMLY ROTATING STARS

    SciTech Connect

    Deupree, Robert G.

    2011-07-10

    Zero-age main-sequence models of uniformly rotating stars have been computed for 10 masses between 1.625 and 8 M{sub sun} and for 21 rotation rates from zero to nearly critical rotation. The surface shape is used to distinguish rotation rather than the surface equatorial velocity or the rotation rate. Using the surface shape is close, but not quite equivalent, to using the ratio of the rotation rate to the critical rotation rate. Using constant shape as the rotation variable means that it and the mass are separable, something that is not true for either the rotation rate or surface equatorial velocity. Thus, a number of properties, including the ratio of the effective temperature anywhere on the surface to the equatorial temperature, are nearly independent of the mass of the model, as long as the rotation rate changes in such a way as to keep the surface shape constant.

  16. Enstrophy-based proper orthogonal decomposition of flow past rotating cylinder at super-critical rotating rate

    NASA Astrophysics Data System (ADS)

    Sengupta, Tapan K.; Gullapalli, Atchyut

    2016-11-01

    Spinning cylinder rotating about its axis experiences a transverse force/lift, an account of this basic aerodynamic phenomenon is known as the Robins-Magnus effect in text books. Prandtl studied this flow by an inviscid irrotational model and postulated an upper limit of the lift experienced by the cylinder for a critical rotation rate. This non-dimensional rate is the ratio of oncoming free stream speed and the surface speed due to rotation. Prandtl predicted a maximum lift coefficient as CLmax = 4π for the critical rotation rate of two. In recent times, evidences show the violation of this upper limit, as in the experiments of Tokumaru and Dimotakis ["The lift of a cylinder executing rotary motions in a uniform flow," J. Fluid Mech. 255, 1-10 (1993)] and in the computed solution in Sengupta et al. ["Temporal flow instability for Magnus-robins effect at high rotation rates," J. Fluids Struct. 17, 941-953 (2003)]. In the latter reference, this was explained as the temporal instability affecting the flow at higher Reynolds number and rotation rates (>2). Here, we analyze the flow past a rotating cylinder at a super-critical rotation rate (=2.5) by the enstrophy-based proper orthogonal decomposition (POD) of direct simulation results. POD identifies the most energetic modes and helps flow field reconstruction by reduced number of modes. One of the motivations for the present study is to explain the shedding of puffs of vortices at low Reynolds number (Re = 60), for the high rotation rate, due to an instability originating in the vicinity of the cylinder, using the computed Navier-Stokes equation (NSE) from t = 0 to t = 300 following an impulsive start. This instability is also explained through the disturbance mechanical energy equation, which has been established earlier in Sengupta et al. ["Temporal flow instability for Magnus-robins effect at high rotation rates," J. Fluids Struct. 17, 941-953 (2003)].

  17. IO Rotation Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    During its 1979 flyby, Voyager 2 observed Io only from a distance. However, the volcanic activity discovered by Voyager 1 months earlier was readily visible. This sequence of nine color images was collected using the Blue, Green and Orange filters from about 1.2 million kilometers. A 2.5 hour period is covered during which Io rotates 7 degrees.

    Rotating into view over the limb of Io are the plumes of the volcanoes Amirani (top) and Maui (lower). These plumes are very distinct against the black sky because they are being illuminated from behind. Notice that as Io rotates, the proportion of Io which is sunlit decreases greatly. This changing phase angle is because Io is moving between the spacecraft and the Sun.

    This time-lapse movie was produced at JPL by the Image Processing Laboratory in 1985.

  18. Rotating Aperture System

    DOEpatents

    Rusnak, Brian; Hall, James M.; Shen, Stewart; Wood, Richard L.

    2005-01-18

    A rotating aperture system includes a low-pressure vacuum pumping stage with apertures for passage of a deuterium beam. A stator assembly includes holes for passage of the beam. The rotor assembly includes a shaft connected to a deuterium gas cell or a crossflow venturi that has a single aperture on each side that together align with holes every rotation. The rotating apertures are synchronized with the firing of the deuterium beam such that the beam fires through a clear aperture and passes into the Xe gas beam stop. Portions of the rotor are lapped into the stator to improve the sealing surfaces, to prevent rapid escape of the deuterium gas from the gas cell.

  19. Chiral rotational spectroscopy

    NASA Astrophysics Data System (ADS)

    Cameron, Robert P.; Götte, Jörg B.; Barnett, Stephen M.

    2016-09-01

    We introduce chiral rotational spectroscopy, a technique that enables the determination of the orientated optical activity pseudotensor components BX X, BY Y, and BZ Z of chiral molecules, in a manner that reveals the enantiomeric constitution of a sample and provides an incisive signal even for a racemate. Chiral rotational spectroscopy could find particular use in the analysis of molecules that are chiral solely by virtue of their isotopic constitution and molecules with multiple chiral centers. A basic design for a chiral rotational spectrometer together with a model of its functionality is given. Our proposed technique offers the more familiar polarizability components αX X, αY Y, and αZ Z as by-products, which could see it find use even for achiral molecules.

  20. Lattice QCD in rotating frames.

    PubMed

    Yamamoto, Arata; Hirono, Yuji

    2013-08-23

    We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD.

  1. Conoscopic polarized interference applied in measuring uniaxial axis direction of electro-optic crystal

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Jiang, Hongzhen; Zhang, Lin; Li, Dong; Liu, Xu; Zheng, Fanglan

    2016-10-01

    The crystal can be used to be electro-optic switch because of its electro-optic modulation. Generally the uniaxial axis of electro-optic crystal is perpendicular to the light injection surface. Due to the manufacturing precision, the uniaxial axis direction has a little angle with the normal of the light injection surface, which affects the electro-optic modulation ability. In conoscopic polarized inference, due to birefraction the ordinary ray and extraordinary ray from crystal interferes after the polarizer. The interference pattern of crystal component is circle fringes with dark cross. The center of interference pattern has relation to the uniaxial axis direction. Using digital camera to capture the pattern and the center position of interferogram can be determinate by image processing program. In repeatability experiments the rms of center position is around 1 pixel. To measure the uniaxial axis direction, the normal direction of the crystal component should also be accurately determinate. Michelson interference method is introduced to determinate the normal direction. If rotate the crystal component around the normal direction in conoscopic polarized interference, the track of interferogram center is a circle theoretically. The circle center is related to the normal direction of crystal component, and the radii is related to the angle uniaxial axis, which can be determinate by least square fitting method. Experiment result shows that the measuring precision can achieves several tens of microradians.

  2. Rotating bubble membrane radiator

    DOEpatents

    Webb, Brent J.; Coomes, Edmund P.

    1988-12-06

    A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

  3. Rotating flexible drag mill

    DOEpatents

    Pepper, W.B.

    1984-05-09

    A rotating parachute for decelerating objects travelling through atmosphere at subsonic or supersonic deployment speeds includes a circular canopy having a plurality of circumferentially arranged flexible panels projecting radially from a solid central disk. A slot extends radially between adjacent panels to the outer periphery of the canopy. Upon deployment, the solid disk diverts air radially to rapidly inflate the panels into a position of maximum diameter. Air impinging on the panels adjacent the panel slots rotates the parachute during its descent. Centrifugal force flattens the canopy into a constant maximum diameter during terminal descent for maximum drag and deceleration.

  4. Minor-axis velocity gradients in spirals and the case of inner polar disks

    NASA Astrophysics Data System (ADS)

    Corsini, E. M.; Pizzella, A.; Coccato, L.; Bertola, F.

    2003-09-01

    We measured the ionized-gas and stellar kinematics along the major and minor axis of a sample of 10 early-type spirals. Much to our surprise we found a remarkable gas velocity gradient along the minor axis of 8 of them. According to the kinematic features observed in their ionized-gas velocity fields, we divide our sample galaxies in three classes of objects. (i) NGC 4984, NGC 7213, and NGC 7377 show an overall velocity curve along the minor axis without zero-velocity points, out to the last measured radius, which is interpreted as due to the warped structure of the gaseous disk. (ii) NGC 3885, NGC 4224, and NGC 4586 are characterized by a velocity gradient along both major and minor axis, although non-zero velocities along the minor axis are confined to the central regions. Such gas kinematics have been explained as being due to non-circular motions induced by a triaxial potential. (iii) NGC 2855 and NGC 7049 show a change of slope of the velocity gradient measured along the major axis (which is shallower in the center and steeper away from the nucleus), as well as non-zero gas velocities in the central regions of the minor axis. This has been attributed to the presence of a kinematically-decoupled gaseous component in orthogonal rotation with respect to the galaxy disk, namely an inner polar disk. The case and origin of inner polar disks are discussed and the list of their host galaxies is presented. Based on observations carried out at the European Southern Observatory (ESO 62.A-0463 and 63.N-0305). Tables 3 and 4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/408/873

  5. Feasibility and optical performance of one axis three positions sun-tracking polar-axis aligned CPCs for photovoltaic applications

    SciTech Connect

    Tang, Runsheng; Yu, Yamei

    2010-09-15

    A new design concept, called one axis three positions sun-tracking polar-axis aligned CPCs (3P-CPCs, in short), was proposed and theoretically studied in this work for photovoltaic applications. The proposed trough-like CPC is oriented in the polar-axis direction, and the aperture is daily adjusted eastward, southward, and westward in the morning, noon and afternoon, respectively, by rotating the CPC trough, to ensure efficient collection of beam radiation nearly all day. To investigate the optical performance of such CPCs, an analytical mathematical procedure is developed to estimate daily and annual solar gain captured by such CPCs based on extraterrestrial radiation and monthly horizontal radiation. Results show that the acceptance half-angle of 3P-CPCs is a unique parameter to determine their optical performance according to extraterrestrial radiation, and the annual solar gain stays constant if the acceptance half-angle, {theta}{sub a}, is less than one third of {omega}{sub 0,min}, the sunset hour angle in the winter solstice, otherwise decreases with the increase of {theta}{sub a}. For 3P-CPCs used in China, the annual solar gain, depending on the climatic conditions in site, decreased with the acceptance half-angle, but such decrease was slow for the case of {theta}{sub a}{<=}{omega}{sub 0,min}/3, indicating that the acceptance half-angle should be less than one third of {omega}{sub 0,min} for maximizing annual energy collection. Compared to fixed east-west aligned CPCs (EW-CPCs) with a yearly optimal acceptance half-angle, the fixed south-facing polar-axis aligned CPCs (1P-CPCs) with the same acceptance half-angle as the EW-CPCs annually collected about 65-74% of that EW-CPCs did, whereas 3P-CPCs annually collected 1.26-1.45 times of that EW-CPCs collected, indicating that 3P-CPCs were more efficient for concentrating solar radiation onto their coupling solar cells. (author)

  6. POGAL B-Axis Motor Test

    SciTech Connect

    Hale, L C; Wulff, T A

    2004-06-28

    The Aerotech model S-180-69-A, a brushless DC motor of slotless design, was selected as the B-axis drive for the Precision Optical Grinder and Lathe (POGAL). It is common knowledge that a slotless motor will have effectively no magnetic cogging and much less torque ripple than a traditional slot-type motor. It is logical to believe that the radial and axial forces generated between the rotor and stator would also be smaller for a slotless design. This is important when a frameless motor is directly coupled to the axis, as these forces directly influence the axis and affect its error motion. It is the purpose of this test to determine the radial and axial forces generated by the Aerotech motor and to estimate their effect on the error motion of the axis using a mathematical model of the hydrostatic bearing being designed for POGAL. The test results combined with a mathematical model of the POGAL B axis indicate that the directly coupled Aerotech motor will be quite acceptable. In the radial direction, the residual motor force, after subtracting out the one-cycle force, could cause sub nanometer level error motion at the tool point. The axial direction is not in a sensitive direction for turning.

  7. From lizard body form to serpentiform morphology: The atlas-axis complex in African cordyliformes and their relatives.

    PubMed

    Čerňanský, Andrej

    2016-04-01

    The comparative vertebral morphology of the atlas-axis complex in cordyliforms, xantusiid and several skinks is studied here. These lizards are particularly interesting because of their different ecological adaptations and anti-predation strategies, where conformation ranges from the lizard-like body to a snake-like body. This transition to serpentiform morphology shows several evolutionary patterns in the atlas-axis complex: 1) the zygapophyseal articulations are lost in the early stage of the transition. In contrast to mammals, the atlas is more or less locked to the axis in lepidosaurs, but the absence of zygapophyseal articulation releases this locking for rotation. However despite its serpentiform morphology, Chamaesaura is different, in possessing this articulation; 2) the first intercentrum of Chamaesaura and Tetradactylus africanus (serpentiform grass-swimmers) is fully curved anteriorly, underlying the occipital condyle. While this limits ventral skull rotation beyond a certain angle, it locks the skull, which is a crucial adaptation for a sit-and-wait position in grassland habitats that needs to keep the head stabilized; and 3) in Acontias, most of the atlas articular surface with the occipital condyle is formed by the lateral aspect of the articulation area relative to the area located in the dorsal region of the slightly reduced intercentrum. A similar state occurs in amphisbaenians, most likely reflecting a fossorial lifestyle of the limbless lizards. Although Chamaesaura and Tetradactylus live sympatrically in grasslands, Chamaesaura differs in several ways in atlas-axis complex: for example, aforementioned presence of the atlas-axis zygapophyseal articulation, and long posterodorsal processes. Its occipital condyle protrudes further posteriorly, placing the atlas-axis complex further from the endocranium than in Tetradactylus. Hence, adaptation in the same niche, even among sister clades, can lead to different atlas-axis morphology due to different

  8. Effect of rotation on a rotating hot-wire sensor

    NASA Technical Reports Server (NTRS)

    Hah, C.; Lakshminarayana, B.

    1978-01-01

    An investigation was conducted to discern the effects of centrifugal and Coriolis forces on a rotating hot-wire. The probe was calibrated in a wind tunnel as well as in a rotating mode. The effect of rotation was found to be negligibly small. A small change in cold resistance (1.5%) was observed in the rotating wire. The rotation seems to have a negligible effect on the fluid mechanics, heat transfer and material characteristics of the wire. This is a significant conclusion in view of the potential application of the hot-wire probe in a rotating passage (such as turbomachinery).

  9. Development of a Rotating Human Research Facility

    NASA Technical Reports Server (NTRS)

    Mulenburg, Gerald M.; Caldwell, William F.; Tucker, John; Wade, Charles E. (Technical Monitor)

    1994-01-01

    A unique facility has been developed at the NASA Ames Research Center to provide scientists with unusual research opportunities at greater than Earth's gravity. In addition to its use for basic research, this facility will help provide answers to many of the questions posed by proponents of rotating human space vehicles. This paper describes the design and planned use of this facility, the Spaceflight Environmental Simulator. Using an existing 52-foot diameter cylindrical rotating platform design centrifuge, the revised facility design includes the provision of two human habitats for long duration studies of the effects of hypergravity. Up to four humans (per habitat) will be able to live at up to 2 G for as long as one month without stopping the centrifuge. Each habitat, constructed of lightweight honeycomb sandwich panels, is nominally 9 ft high x 11 ft wide x 25 1/2 ft long. A radial positioning system provides for positioning each habitat at a distance of 15 to 21 feet from the centrifuge's axis of rotation to the midpoint of the habitat's interior floor. As centrifugal acceleration changes with rotation rate, a habitat floor-mounted accelerometer signal provides automatic servo controlled adjustment of each habitat's angle of inclination to provide an environment for the habitat's crew and cargo in which the resultant gravity vector is normal to the habitat floor at all times. Design of the habitats and modifications to the centrifuge are complete, and are currently under construction. Design philosophy and operational rationale are presented along with complete descriptions of the facility and its systems.

  10. Compact rotating cup anemometer

    NASA Technical Reports Server (NTRS)

    Wellman, J. B.

    1968-01-01

    Compact, collapsible rotating cup anemometer is used in remote locations where portability and durability are factors in the choice of equipment. This lightweight instrument has a low wind-velocity threshold, is capable of withstanding large mechanical shocks while in its stowed configuration, and has fast response to wind fluctuations.

  11. Rotationally Actuated Prosthetic Hand

    NASA Technical Reports Server (NTRS)

    Norton, William E.; Belcher, Jewell G., Jr.; Carden, James R.; Vest, Thomas W.

    1991-01-01

    Prosthetic hand attached to end of remaining part of forearm and to upper arm just above elbow. Pincerlike fingers pushed apart to degree depending on rotation of forearm. Simpler in design, simpler to operate, weighs less, and takes up less space.

  12. Rotating Science Classrooms.

    ERIC Educational Resources Information Center

    Hogg, Loretta A.

    1980-01-01

    Described is a science classroom program with centralized materials, and assistance and workshops for teachers. Classroom materials on one of five topics rotate every six weeks among five schools. Teachers plan specific units to match the arrival of the materials in their schools. (Author/DS)

  13. Rotational Dynamics with Tracker

    ERIC Educational Resources Information Center

    Eadkhong, T.; Rajsadorn, R.; Jannual, P.; Danworaphong, S.

    2012-01-01

    We propose the use of Tracker, freeware for video analysis, to analyse the moment of inertia ("I") of a cylindrical plate. Three experiments are performed to validate the proposed method. The first experiment is dedicated to find the linear coefficient of rotational friction ("b") for our system. By omitting the effect of such friction, we derive…

  14. Concepts in crop rotations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop rotations have been a part of civilization since the Middle Ages. With colonization of what would become the United States came new crops of tobacco, cotton, and corn, the first two of which would play significant roles in both the economic beginnings and social fabric of the new country, how ...

  15. Anisotropy in rotating drums

    NASA Astrophysics Data System (ADS)

    Povall, Timothy; McBride, Andrew; Govender, Indresan

    2015-11-01

    An anisotropic relationship between the stress and the strain rate has been observed in two-dimensional simulations of rotating drums. The objective of this work is to investigate the structure of the constitutive relation using three-dimensional discrete-element-method simulations of a rotating drum containing identical rigid spheres for a range of rotational speeds. Anisotropy is quantified from the alignment of the stress and strain rate tensors, with the strain rate computed using a least-squares fit. It is shown that in certain regions there is a strong anisotropic relationship, regardless of the speed of rotation. The effective friction coefficient is examined in order to determine the phase space in which the μ (I) rheology is valid. Lastly, a depth-averaged approach through the flowing layer is employed to determine the relationship between the velocity tangential to the equilibrium surface and the height of the flowing layer. A power-law relationship that approaches linear at high speeds is observed. Supported by NRF/DST Scarce Skills (South Africa).

  16. Rotating Saddle Paul Trap.

    ERIC Educational Resources Information Center

    Rueckner, Wolfgang; And Others

    1995-01-01

    Describes a demonstration in which a ball is placed in an unstable position on a saddle shape. The ball becomes stable when it is rotated above some threshold angular velocity. The demonstration is a mechanical analog of confining a particle in a "Paul Trap". (DDR)

  17. Rotatable stem and lock

    DOEpatents

    Deveney, Joseph E.; Sanderson, Stephen N.

    1984-01-01

    A valve stem and lock include a housing surrounding a valve stem, a solenoid affixed to an interior wall of the housing, an armature affixed to the valve stem and a locking device for coupling the armature to the housing body. When the solenoid is energized, the solenoid moves away from the housing body, permitting rotation of the valve stem.

  18. Rotatable stem and lock

    DOEpatents

    Deveney, J.E.; Sanderson, S.N.

    1981-10-27

    A valve stem and lock is disclosed which includes a housing surrounding a valve stem, a solenoid affixed to an interior wall of the housing, an armature affixed to the valve stem and a locking device for coupling the armature to the housing body. When the solenoid is energized, the solenoid moves away from the housing body, permitting rotation of the valve stem.

  19. Rotator Cuff Injuries.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Many baseball players suffer from shoulder injuries related to the rotator cuff muscles. These injuries may be classified as muscular strain, tendonitis or tenosynovitis, and impingement syndrome. Treatment varies from simple rest to surgery, so it is important to be seen by a physician as soon as possible. In order to prevent these injuries, the…

  20. The shape and rotation of asteroid 2008 TC3

    NASA Astrophysics Data System (ADS)

    Scheirich, Peter; Durech, Josef; Pravec, Petr; Kozubal, Marek; Dantowitz, Ron; Kaasalainen, Mikko; Betzler, Alberto Silva; Beltrame, Paolo; Muler, Gustavo; Birtwhistle, Peter; Kugel, Francois

    2010-10-01

    On October 6, 2008, a small F-class asteroid 2008 TC3 was discovered by Catalina Sky Survey telescope, and exploded 20 hr later in the Earth's atmosphere at 37 km altitude. We analyzed available photometric data taken from 6 October 21:10 to 7 October 01:46 UT, and created a numerical model of a shape and rotation state of the asteroid. The asteroid was in excited rotational state. We found two approximately mirror solutions of orientation of its angular momentum vector. Rotational and precession periods are 99.20 and 97.00 s (errors of the rotational period for the two solutions are 0.03 and 0.04 s; of the precession period are 0.05 s for both solutions). The volume of the convex model and the length of the longest axis of the dynamically equivalent, equal volume ellipsoid are ? and ?, where pV is surface geometric albedo. Assuming a mean albedo value for F taxonomic class, 0.049 ± 0.010, the volume is (25 ± 10) m3 and the longest axis is (6.7 ± 0.8) m. This volume of the convex model is an upper limit on a real volume of the asteroid, which may be less by up to 20% due to concavities.

  1. On the rotation and pitching of flat plates

    NASA Astrophysics Data System (ADS)

    Jin, Yaqing; Ji, Sheng; Chamorro, Leonardo P.

    2016-11-01

    Wind tunnel experiments were performed to characterize the flow-induced rotation and pitching of various flat plates as a function of the thickness ratio, the location of the axis of rotation and turbulence levels. High-resolution telemetry, laser tachometer, and hotwire were used to get time series of the plates motions and the signature of the wake flow at a specific location. Results show that a minor axis offset can induce high-order modes in the plate rotation under low turbulence due to torque unbalance. The spectral decomposition of the flow velocity in the plate wake reveals the existence of a dominating high-frequency mode that corresponds to a static-like vortex shedding occurring at the maximum plate pitch, where the characteristic length scale is the projected width at maximum pitch. The plate thickness ratio shows inverse relation with the angular velocity. A simple model is derived to explain the linear relation between pitching frequency and wind speed. The spectra of the plate rotation show nonlinear relation with the incoming turbulence, and the dominating role of the generated vortices in the plate motions.

  2. Lightcurve Analysis for Nine Main-belt Asteroids. Rotation Period and Physical Parameters from APT Observatory Group: 2016 October-December

    NASA Astrophysics Data System (ADS)

    Aznar Macias, Amadeo

    2017-04-01

    Lightcurves of nine main-belt asteroids (MBA) obtained at APT-Observatory Group from 2016 October- December were analyzed for rotation period, amplitude and physical parameters (axis size relationship).

  3. Quantum mechanical effects in tilted axis rotation in {sup 182}Os

    SciTech Connect

    Hashimoto, Yukio; Horibata, Takatoshi

    2010-05-12

    We performed the three-dimensional cranked Hartree-Fock-Bogoliubov calculation for {sup 182}Os. A family of states obtained by the calculation are expected to be the t-band with K = 8. We suggest a quantum mechanical mechanism which is responsible for the occurrence of a signature splitting in the t-band.

  4. Alignment Solution for CT Image Reconstruction using Fixed Point and Virtual Rotation Axis

    PubMed Central

    Jun, Kyungtaek; Yoon, Seokhwan

    2017-01-01

    Since X-ray tomography is now widely adopted in many different areas, it becomes more crucial to find a robust routine of handling tomographic data to get better quality of reconstructions. Though there are several existing techniques, it seems helpful to have a more automated method to remove the possible errors that hinder clearer image reconstruction. Here, we proposed an alternative method and new algorithm using the sinogram and the fixed point. An advanced physical concept of Center of Attenuation (CA) was also introduced to figure out how this fixed point is applied to the reconstruction of image having errors we categorized in this article. Our technique showed a promising performance in restoring images having translation and vertical tilt errors. PMID:28120881

  5. Review and Preliminary Evaluation of Lifting Horizontal-Axis Rotating-Wing Aeronautical Systems (HARWAS)

    DTIC Science & Technology

    ship propulsion and cycloidal ship propulsion . Approximately 1200 references are listed. A series of cross-index tables is also included to provide a quick means for the reader to determine the content and availability of the references. An analysis of the various lift systems pertinent to the HARWAS field is made with a view to potential air vehicle applications. Over 20 original aeronautical applications are identified and evaluated in the light of recent advances in power plants, transmissions and lightweight structural techniques. This analysis

  6. Axi-symmetric Gravitational MHD Equilibria in the Presence of Plasma Rotation

    SciTech Connect

    Cremaschini, C.; Beklemishev, A.; Miller, J.; Tessarotto, M.

    2008-12-31

    In this paper, extending the investigation developed in an earlier paper (Cremaschini et al., 2008), we pose the problem of the kinetic description of gravitational Hall-MHD equilibria which may arise in accretion disks (AD) plasmas close to compact objects. When intense EM and gravitational fields, generated by the central object, are present, a convenient approach can be achieved in the context of the Vlasov-Maxwell description. In this paper the investigation is focused primarily on the following two aspects:1) the formulation of the kinetic treatment of G-Hall-MHD equilibria. Based on the identification of the relevant first integrals of motion, we show that an explicit representation can be given for the equilibrium kinetic distribution function. For each species this is represented as a superposition of suitable generalized Maxwellian distributions;2) the determination of the constraints to be placed on the fluid fields for the existence of the kinetic equilibria. In particular, this permits a unique determination of the functional form of the species number densities and of the fluid partial pressures, in terms of suitably prescribed flux functions.

  7. Alignment Solution for CT Image Reconstruction using Fixed Point and Virtual Rotation Axis

    NASA Astrophysics Data System (ADS)

    Jun, Kyungtaek; Yoon, Seokhwan

    2017-01-01

    Since X-ray tomography is now widely adopted in many different areas, it becomes more crucial to find a robust routine of handling tomographic data to get better quality of reconstructions. Though there are several existing techniques, it seems helpful to have a more automated method to remove the possible errors that hinder clearer image reconstruction. Here, we proposed an alternative method and new algorithm using the sinogram and the fixed point. An advanced physical concept of Center of Attenuation (CA) was also introduced to figure out how this fixed point is applied to the reconstruction of image having errors we categorized in this article. Our technique showed a promising performance in restoring images having translation and vertical tilt errors.

  8. Thermal Emission Light-Curves of Rapidly Rotating Asteroids

    NASA Astrophysics Data System (ADS)

    Rozitis, Ben; Emery, Joshua; Lowry, Stephen; Rozek, Agata; Wolters, Stephen; Snodgrass, Colin; Green, Simon

    2014-12-01

    We propose to use Spitzer/IRAC to obtain simultaneous 3 and 4 um light-curves of 23 rapidly rotating asteroids (rotation periods of less than 3 hrs) to determine thermal inertia and surface roughness spatial variations. These observations will probe asteroid geophysics and constrain the origin of their rapid rotation. Rapidly rotating asteroids are unusual bodies where their own self-gravity is balanced or exceeded by rotational centrifugal forces, and are thought to have acquired their fast rotation rates through the YORP effect - a radiative torque induced by exposure to sunlight. For each target asteroid, we will measure thermal flux in both IRAC bands for a full rotation. When combined with shapes and spin axes derived from our ground-based programme, and a thermophysical model, we will be able to identify any temperature variations resulting from thermal inertia and/or surface roughness variation, and be able to constrain theoretical predictions of YORP rotational acceleration. The thermal property variations will be compared against models of surface gravity in order to provide insights into the physical processes by which asteroids retain and lose surface material. 16 of our target asteroids are being observed at optical wavelengths in a European Southern Observatory (ESO) Large Programme (LP) awarded 82 nights to constrain rotation period changes induced by the YORP effect (PI Stephen Lowry; Program IDs 185.C-1033, 185.C-1034). Approximately 80 additional nights on a range of other facilities has also been awarded for this programme. The ESO LP will support the Spitzer programme by providing shape and spin axis information necessary to search for surface property variations in the thermal emission light-curves of these asteroids. Likewise, the Spitzer/IRAC thermal emission light-curves will allow us to derive the physical properties that drive the YORP effect on the ESO LP asteroids.

  9. Modular off-axis solar concentrator

    DOEpatents

    Plesniak, Adam P; Hall, John C

    2015-01-27

    A solar concentrator including a housing defining a vertical axis and including a receiving wall connected to a reflecting wall to define an internal volume and an opening into the internal volume, wherein the reflecting wall defines at least one primary optical element, and wherein at least a portion of the reflecting wall includes a layer of reflective material, the housing further including a cover connected to the receiving wall and the reflecting wall to seal the opening, and at least one receiver mounted on the receiving wall such that a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, the receiver including at least one photovoltaic cell.

  10. Enclosed, off-axis solar concentrator

    SciTech Connect

    Benitez, Pablo; Grip, Robert E; Minano, Juan C; Narayanan, Authi A; Plesniak, Adam; Schwartz, Joel A

    2013-11-26

    A solar concentrator including a housing having receiving wall, a reflecting wall and at least two end walls, the receiving, reflecting and end walls defining a three-dimensional volume having an inlet, wherein a vertical axis of the housing is generally perpendicular to the inlet, a receiver mounted on the receiving wall of the housing, the receiver including at least one photovoltaic cell, wherein a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, at least one clip disposed on the reflecting wall an optical element received within the three-dimensional volume, the optical element including at least one tab, the tab being engaged by the clip to align the optical element with the receiver, and a window received over the inlet to enclose the housing.

  11. The holographic vibration analysis of rotating objects using a reflective image derotator

    NASA Astrophysics Data System (ADS)

    Fagan, W. F.; Beeck, M.-A.; Kreitlow, H.

    1981-03-01

    A reflective image derotator has been developed for the analysis of the vibrations of rotating components. The derotator is based on an encoder which relays electrical impulses to a control unit that drives a special servo-motor at exactly half the object's rotational speed. The servo-motor is connected to a prism mount and the unit is pointed along the object's rotational axis. The derotated image is observed via a beamsplitter in front of the rotating prism. It is concluded that image derotated holographic interferometry can be successfully applied to the study of rotating components and real engineering components operating under normal conditions. The technique is particularly applicable to the study of fatigue life, efficiency and the safety of rotating machinery.

  12. Heat-Driven Rotation in Cholesteric Droplets with a Double Twisted Structure

    NASA Astrophysics Data System (ADS)

    Ito, Fumiya; Yoshioka, Jun; Tabe, Yuka

    2016-11-01

    In an isotropic-cholesteric coexistence system, a single-helix structure is formed in the cholesteric droplets, and when a temperature gradient is applied, unidirectional rotations are induced in these droplets. However, in a previous work, we showed that a double twisted structure was also formed in the droplets by changing droplet size or chirality. In this paper, we find that unidirectional rotations are also induced by applying a temperature gradient to droplets with a double twisted structure. Here, however, the rotational behavior is strongly dependent on the relationship between the direction of the helical axis and the temperature gradient. Unidirectional rotation is induced when one of the helical axes is parallel to the gradient, whereas no rotation is found when all of the axes are perpendicular to the temperature gradient. These results suggest that the macroscopic helix plays a significant role in the heat-driven rotational dynamics of cholesteric droplets.

  13. Formation of huge in-plane anisotropy of intrinsic stress by off-axis growth of diamond

    NASA Astrophysics Data System (ADS)

    Gallheber, B.-C.; Fischer, M.; Klein, O.; Schreck, M.

    2016-10-01

    The present study shows that the heteroepitaxial growth of diamond by chemical vapour deposition (CVD) on Ir/YSZ/Si(111) substrates with off-axis angles of few degrees can generate intrinsic stress with huge anisotropy of several GPa in the diamond films. For all investigated off-axis directions and angles, a plane stress state with a perpendicular component σ33 ˜ 0 GPa is derived by X-ray diffraction. The size and direction of the associated in-plane stress tensor components exhibit a unique dependency on the off-axis tilt direction. They can combine the simultaneous presence of tensile and compressive stress within a layer. Stress anisotropy increases with the off-axis angle. For diamond with off-axis tilt towards [110] and [112], the principal axes of the tensor are parallel and perpendicular, respectively, to the projection of the off-axis direction into the film plane, whereas for [ 1 1 ¯ 0 ] they are rotated by an angle of ˜30°. For a consistent explanation of this complex behaviour, it is suggested that the measured stress is generated by the combined action of growth parameter controlled effective climb of dislocations and off-axis growth induced dislocation tilting. It is supposed that the described mechanism is not only valid for diamond CVD but also contributes to anisotropic stress formation in other semiconductor materials grown on vicinal surfaces.

  14. Direction of spin axis and spin rate of the pitched baseball.

    PubMed

    Jinji, Tsutomu; Sakurai, Shinji

    2006-07-01

    In this study, we aimed to determine the direction of the spin axis and the spin rate of pitched baseballs and to estimate the associated aerodynamic forces. In addition, the effects of the spin axis direction and spin rate on the trajectory of a pitched baseball were evaluated. The trajectories of baseballs pitched by both a pitcher and a pitching machine were recorded using four synchronized video cameras (60 Hz) and were analyzed using direct linear transform (DLT) procedures. A polynomial function using the least squares method was used to derive the time-displacement relationship of the ball coordinates during flight for each pitch. The baseball was filmed immediately after ball release using a high-speed video camera (250 Hz), and the direction of the spin axis and the spin rate (omega) were calculated based on the positional changes of the marks on the ball. The lift coefficient was correlated closely with omegasinalpha (r = 0.860), where alpha is the angle between the spin axis and the pitching direction. The term omegasinalpha represents the vertical component of the velocity vector. The lift force, which is a result of the Magnus effect occurring because of the rotation of the ball, acts perpendicularly to the axis of rotation. The Magnus effect was found to be greatest when the angular and translational velocity vectors were perpendicular to each other, and the break of the pitched baseball became smaller as the angle between these vectors approached 0 degrees. Balls delivered from a pitching machine broke more than actual pitcher's balls. It is necessary to consider the differences when we use pitching machines in batting practice.

  15. Variations of the Earth's figure axis from satellite laser ranging and GRACE

    NASA Astrophysics Data System (ADS)

    Cheng, Minkang; Ries, John C.; Tapley, Byron D.

    2011-01-01

    Satellite laser ranging (SLR) data were used to determine the variations in the Earth's principal figure axis represented by the degree 2 and order 1 geopotential coefficients: C21 and S21. Significant variations at the annual and Chandler wobble frequencies appear in the SLR time series when the rotational deformation or "pole tides" (i.e., the solid Earth and ocean pole tides) were not modeled. The contribution of the ocean pole tide is estimated to be only ˜8% of the total annual variations in the normalized coefficients: ?/? based on the analysis of SLR data. The amplitude of the nontidal annual variation of ? is only ˜ 30% of ? from the SLR time series. The estimates of the annual variation in ? from SLR, the Gravity Recovery and Climate Experiment (GRACE) and polar motion excitation function, are in a good agreement. The nature of the linear trend for the Earth's figure axis determined by these techniques during the last several years is in general agreement but does not agree as well with results predicted from current glacial isostatic adjustment (GIA) models. The "fluid Love number" for the Earth is estimated to be ˜0.9 based on the position of the mean figure axis from the GRACE gravity model GGM03S and the mean pole defined by the IERS 2003 conventions. The estimate of ?/? from GRACE and SLR provides an improved constraint on the relative rotation of the core. The results presented here indicate a possible tilt of the inner core figure axis of ˜2° and ˜3 arc sec displacement for the figure axis of the entire core.

  16. Three-dimensional control of the helical axis of a chiral nematic liquid crystal by light

    NASA Astrophysics Data System (ADS)

    Zheng, Zhi-Gang; Li, Yannian; Bisoyi, Hari Krishna; Wang, Ling; Bunning, Timothy J.; Li, Quan

    2016-03-01

    Chiral nematic liquid crystals—otherwise referred to as cholesteric liquid crystals (CLCs)—are self-organized helical superstructures that find practical application in, for example, thermography, reflective displays, tuneable colour filters and mirrorless lasing. Dynamic, remote and three-dimensional control over the helical axis of CLCs is desirable, but challenging. For example, the orientation of the helical axis relative to the substrate can be changed from perpendicular to parallel by applying an alternating-current electric field, by changing the anchoring conditions of the substrate, or by altering the topography of the substrate’s surface; separately, in-plane rotation of the helical axis parallel to the substrate can be driven by a direct-current field. Here we report three-dimensional manipulation of the helical axis of a CLC, together with inversion of its handedness, achieved solely with a light stimulus. We use this technique to carry out light-activated, wide-area, reversible two-dimensional beam steering—previously accomplished using complex integrated systems and optical phased arrays. During the three-dimensional manipulation by light, the helical axis undergoes, in sequence, a reversible transition from perpendicular to parallel, followed by in-plane rotation on the substrate surface. Such reversible manipulation depends on experimental parameters such as cell thickness, surface anchoring condition, and pitch length. Because there is no thermal relaxation, the system can be driven either forwards or backwards from any light-activated intermediate state. We also describe reversible photocontrol between a two-dimensional diffraction state, a one-dimensional diffraction state and a diffraction ‘off’ state in a bilayer cell.

  17. Molecular collisions. 11: Semiclassical approximation to atom-symmetric top rotational excitation

    NASA Technical Reports Server (NTRS)

    Russell, D.; Curtiss, C. F.

    1973-01-01

    In a paper of this series a distorted wave approximation to the T matrix for atom-symmetric top scattering was developed which is correct to first order in the part of the interaction potential responsible for transitions in the component of rotational angular momentum along the symmetry axis of the top. A semiclassical expression for this T matrix is derived by assuming large values of orbital and rotational angular momentum quantum numbers.

  18. A users guide to HPA axis research.

    PubMed

    Spencer, Robert L; Deak, Terrence

    2016-11-18

    Glucocorticoid hormones (cortisol and corticosterone - CORT) are the effector hormones of the hypothalamic-pituitary-adrenal (HPA) axis neuroendocrine system. CORT is a systemic intercellular signal whose level predictably varies with time of day and dynamically increases with environmental and psychological stressors. This hormonal signal is utilized by virtually every cell and physiological system of the body to optimize performance according to circadian, environmental and physiological demands. Disturbances in normal HPA axis activity profiles are associated with a wide variety of physiological and mental health disorders. Despite numerous studies to date that have identified molecular, cellular and systems-level glucocorticoid actions, new glucocorticoid actions and clinical status associations continue to be revealed at a brisk pace in the scientific literature. However, the breadth of investigators working in this area poses distinct challenges in ensuring common practices across investigators, and a full appreciation for the complexity of a system that is often reduced to a single dependent measure. This Users Guide is intended to provide a fundamental overview of conceptual, technical and practical knowledge that will assist individuals who engage in and evaluate HPA axis research. We begin with examination of the anatomical and hormonal components of the HPA axis and their physiological range of operation. We then examine strategies and best practices for systematic manipulation and accurate measurement of HPA axis activity. We feature use of experimental methods that will assist with better understanding of CORT's physiological actions, especially as those actions impact subsequent brain function. This research approach is instrumental for determining the mechanisms by which alterations of HPA axis function may contribute to pathophysiology.

  19. Invited review article: Large ring lasers for rotation sensing.

    PubMed

    Schreiber, Karl Ulrich; Wells, Jon-Paul R

    2013-04-01

    Over the last two decades a series of large ring laser gyroscopes have been built having an unparalleled scale factor. These upscaled devices have improved the sensitivity and stability for rotation rate measurements by six orders of magnitude when compared to previous commercial developments. This progress has made possible entirely new applications of ring laser gyroscopes in the fields of geophysics, geodesy, and seismology. Ring lasers are currently the only viable measurement technology, which is directly referenced to the instantaneous rotation axis of the Earth. The sensor technology is rapidly developing. This is evidenced by the first experimentally viable proposals to make terrestrial tests of general relativistic effects such as the frame dragging of the rotating Earth.

  20. The aerodynamic analysis of the gyroplane rotating-wing system

    NASA Technical Reports Server (NTRS)

    Wheatley, John B

    1934-01-01

    An aerodynamic analysis of the gyroplane rotating-wing system is presented herein. This system consists of a freely rotating rotor in which opposite blades are rigidly connected and allowed to rotate or feather freely about their span axis. Equations have been derived for the lift, the lift-drag ratio, the angle of attack, the feathering angles, and the rolling and pitching moments of a gyroplane rotor in terms of its basic parameters. Curves of lift-drag ratio against lift coefficient have been calculated for a typical case, showing the effect of varying the pitch angle, the solidarity, and the average blade-section drag coefficient. The analysis expresses satisfactorily the qualitative relations between the rotor characteristics and the rotor parameters. As disclosed by this investigation, the aerodynamic principles of the gyroplane are sound, and further research on this wing system is justified.

  1. Effects of clinostat rotation on mouse meiotic maturation in vitro

    NASA Technical Reports Server (NTRS)

    Wolgemuth, D. J.; Grills, G. S.

    1984-01-01

    The effects of microgravity on meiosis, fertilization, and early embryonic development in mammals are being examined by using a clinostat to reorient the cells with respect to the gravity vector. A clinostat capable of supporting mammalian cells in tissue culture has been developed. Initial studies have focused on examining the effects of clinostat rotation on meiotic maturation in mouse oocytes. Oocytes recovered from ovarian follicles were subjected to clinostat rotation on a horizontal or vertical axis or to static conditions for a 16 hr period. No gross morphological changes and no effects on germinal vesicle breakdown were observed under any rotation conditions (1/4, 1, 10, 30, 100 RPM). Success of meiotic progression to Metaphase II was comparable among experimental and control groups except at 100 RPM, where a slight inhibition was observed.

  2. Particle Movements in a Rotating Ultrasonic Waveguide.

    NASA Astrophysics Data System (ADS)

    Whitworth, Glenn

    An apparatus was designed to allow a suspension of biological cells to be subjected to a well-defined, 160 kHz standing ultrasonic field while being viewed through a stereo microscope. Cell positions were recorded either photographically or by means of a video camera. The chamber cavity, which has a square cross-section and pressure-release walls, acts as a single-mode acoustic waveguide. The well -defined, single-mode field is achieved through use of a special design involving air-filled chamber windows. Aqueous metrizamide solution is used to fill the ultrasonic chamber because it has a unique combination of properties including low viscosity, low osmolarity, and high density. The chamber rotates about its axis (whose inclination can be varied) producing the centripetal force necessary to contain the buoyant cells in the axial region. Observations were made on stroboscopically illuminated suspensions both of latex microspheres and of red blood cells (RBC's). Small (6-14 μm) latex microspheres or RBC's formed aggregates at half-wavelength intervals along the rotation axis near positions of acoustic pressure-amplitude (PA) minima. In addition, near the positions of PA maxima the particles would typically arrange themselves into axially symmetric distributions with evidence of flow. Larger (273 μm) latex microspheres also formed aggregates near the axial positions of PA minima. If these aggregates were sufficiently large, then much smaller aggregates would often form near positions of PA maxima. (This is in contrast with the flowing distributions seen near these positions when smaller particles were used.). The presence and shape of aggregates near positions of PA minima are explained by a scalar-potential theory for non-interacting particles that considers gravitational, rotational, and acoustic radiation forces on the particles. Theory was developed to describe acoustic streaming in a rotating fluid. This theory was then generalized to treat flow generated by a

  3. Natural convection in a horizontal cylinder with axial rotation

    NASA Astrophysics Data System (ADS)

    Sánchez, Odalys; Mercader, Isabel; Batiste, Oriol; Alonso, Arantxa

    2016-06-01

    We study the problem of thermal convection in a laterally heated horizontal cylinder rotating about its axis. A cylinder of aspect ratio Γ =H /2 R =2 containing a small Prandtl number fluid (σ =0.01 ) representative of molten metals and molten semiconductors at high temperature is considered. We focus on a slow rotation regime (Ω <8 ), where the effects of rotation and buoyancy forces are comparable. The Navier-Stokes and energy equations with the Boussinesq approximation are solved numerically to calculate the basic states, analyze their linear stability, and compute several secondary flows originated from the instabilities. Due to the confined cylindrical geometry—the presence of lateral walls and lids—all the flows are completely three dimensional, even the basic steady states. Results characterizing the basic states as the rotation rate increases are presented. As it occurred in the nonrotating case for higher values of the Prandtl number, two curves of steady states with the same symmetric character coexist for moderate values of the Rayleigh number. In the range of Ω considered, rotation has a stabilizing effect only for very small values. As the value of the rotation rate approaches Ω =3.5 and Ω =4.5 , the scenario of bifurcations becomes more complex due to the existence in both cases of very close bifurcations of codimension 2, which in the latter case involve both curves of symmetric solutions.

  4. Venus and Earth , false twins: really different rotational properties

    NASA Astrophysics Data System (ADS)

    Cottereau, L.

    2010-12-01

    Although Venus and the Earth are the most similar planets in the Solar system, the rotation of these two planets has quite different characteristics. Of the very slow retrograde rotation of Venus, due to a balance between atmospheric and solid body tidal torques, emerge many differences on the evolution of the rotational state of Venus with respect to the Earth one. A complete study of the rotation of Venus on short time scale is presented and compared to the results obtained for the Earth. Applying the theoretical models of Kinoshita (1972, 1977) already used for the Earth, the polhody and the nutation of the figure axis of a rigid Venus is determined. Then evaluating the deformations produced by the zonal part of the tidal potential on the principal moment of inertia, the periodic variations of the speed of rotation of Venus is presented. At last the differences between the results obtained for Venus and for the Earth are explained. Preliminary results on the effect of the atmosphere and the interior of the planet on its rotation state will also be discussed.

  5. Open dorsal vertebroplasty of the axis.

    PubMed

    Guerre, Pascal; Kröber, Markus

    2011-05-01

    Vertebroplasty of the axis is always a challenging procedure. We report the case of a young, HIV-positive patient suffering from an osteolytic metastasis of the axis. An open dorsal vertebroplasty was performed. A leakage of the cement formed a new cortical bone of the massa lateralis of C2, and stabilized the C1-C2 articulation by an arthrodesis-like effect. Durable pain relief and stabilization were obtained. The location of the cement, although atypical, had all desired effects of a conventional vertebroplasty. The intra-articular injection of cement into the facets for stabilization and pain relief could be considered in the future.

  6. Isodynamic axisymmetric equilibrium near the magnetic axis

    SciTech Connect

    Arsenin, V. V.

    2013-08-15

    Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo’s configuration)

  7. Isodynamic axisymmetric equilibrium near the magnetic axis

    NASA Astrophysics Data System (ADS)

    Arsenin, V. V.

    2013-08-01

    Plasma equilibrium near the magnetic axis of an axisymmetric toroidal magnetic confinement system is described in orthogonal flux coordinates. For the case of a constant current density in the vicinity of the axis and magnetic surfaces with nearly circular cross sections, expressions for the poloidal and toroidal magnetic field components are obtained in these coordinates by using expansion in the reciprocal of the aspect ratio. These expressions allow one to easily derive relationships between quantities in an isodynamic equilibrium, in which the absolute value of the magnetic field is constant along the magnetic surface (Palumbo's configuration).

  8. The Effect of Rotation on Oscillatory Double-diffusive Convection (Semiconvection)

    NASA Astrophysics Data System (ADS)

    Moll, Ryan; Garaud, Pascale

    2017-01-01

    Oscillatory double-diffusive convection (ODDC, more traditionally called semiconvection) is a form of linear double-diffusive instability that occurs in fluids that are unstably stratified in temperature (Schwarzschild unstable), but stably stratified in chemical composition (Ledoux stable). This scenario is thought to be quite common in the interiors of stars and giant planets, and understanding the transport of heat and chemical species by ODDC is of great importance to stellar and planetary evolution models. Fluids unstable to ODDC have a tendency to form convective thermocompositional layers that significantly enhance the fluxes of temperature and chemical composition compared with microscopic diffusion. Although a number of recent studies have focused on studying properties of both layered and nonlayered ODDC, few have addressed how additional physical processes such as global rotation affect its dynamics. In this work, we study first how rotation affects the linear stability properties of rotating ODDC. Using direct numerical simulations, we then analyze the effect of rotation on properties of layered and nonlayered ODDC, and we study how the angle of the rotation axis with respect to the direction of gravity affects layering. We find that rotating systems can be broadly grouped into two categories based on the strength of rotation. The qualitative behavior in the more weakly rotating group is similar to nonrotating ODDC, but strongly rotating systems become dominated by vortices that are invariant in the direction of the rotation vector and strongly influence transport. We find that whenever layers form, rotation always acts to reduce thermal and compositional transport.

  9. A new twist on gyroscopic sensing: body rotations lead to torsion in flapping, flexing insect wings

    PubMed Central

    Eberle, A. L.; Dickerson, B. H.; Reinhall, P. G.; Daniel, T. L.

    2015-01-01

    Insects perform fast rotational manoeuvres during flight. While two insect orders use flapping halteres (specialized organs evolved from wings) to detect body dynamics, it is unknown how other insects detect rotational motions. Like halteres, insect wings experience gyroscopic forces when they are flapped and rotated and recent evidence suggests that wings might indeed mediate reflexes to body rotations. But, can gyroscopic forces be detected using only changes in the structural dynamics of a flapping, flexing insect wing? We built computational and robotic models to rotate a flapping wing about an axis orthogonal to flapping. We recorded high-speed video of the model wing, which had a flexural stiffness similar to the wing of the Manduca sexta hawkmoth, while flapping it at the wingbeat frequency of Manduca (25 Hz). We compared the three-dimensional structural dynamics of the wing with and without a 3 Hz, 10° rotation about the yaw axis. Our computational model revealed that body rotation induces a new dynamic mode: torsion. We verified our result by measuring wing tip displacement, shear strain and normal strain of the robotic wing. The strains we observed could stimulate an insect's mechanoreceptors and trigger reflexive responses to body rotations. PMID:25631565

  10. A new twist on gyroscopic sensing: body rotations lead to torsion in flapping, flexing insect wings.

    PubMed

    Eberle, A L; Dickerson, B H; Reinhall, P G; Daniel, T L

    2015-03-06

    Insects perform fast rotational manoeuvres during flight. While two insect orders use flapping halteres (specialized organs evolved from wings) to detect body dynamics, it is unknown how other insects detect rotational motions. Like halteres, insect wings experience gyroscopic forces when they are flapped and rotated and recent evidence suggests that wings might indeed mediate reflexes to body rotations. But, can gyroscopic forces be detected using only changes in the structural dynamics of a flapping, flexing insect wing? We built computational and robotic models to rotate a flapping wing about an axis orthogonal to flapping. We recorded high-speed video of the model wing, which had a flexural stiffness similar to the wing of the Manduca sexta hawkmoth, while flapping it at the wingbeat frequency of Manduca (25 Hz). We compared the three-dimensional structural dynamics of the wing with and without a 3 Hz, 10° rotation about the yaw axis. Our computational model revealed that body rotation induces a new dynamic mode: torsion. We verified our result by measuring wing tip displacement, shear strain and normal strain of the robotic wing. The strains we observed could stimulate an insect's mechanoreceptors and trigger reflexive responses to body rotations.

  11. Electron cyclotron heating and core intrinsic rotation reversal in DIII-D

    SciTech Connect

    Grassie, J. S. de; Boedo, J. A.; Grierson, B. A.

    2015-12-10

    The effect of electron cyclotron heating (ECH) on the intrinsic rotation profile in DIII-D is shown experimentally. Former DIII-D experiments have shown that ECH tends to cause an interior reduction in the normally co-Ip directed intrinsic rotation profile, and this core rotation can be fully reversed to the opposite direction. This effect is due to a turbulent rearrangement of the interior rotation profile. Here, we show results that there is more than one mechanism causing this. We compare two low density L-mode discharges where the only operational difference is the location of the ECH deposition. At low ECH power, comparable to the Ohmic power, the primary change is in the q-profile accompanied by a reversal of the core intrinsic rotation direction for the more off-axis deposition. The change in the shear of the q-profile fits well with a recent theoretical prediction for this rotation reversal. At higher ECH power, the primary change is in the core electron temperature, Te, accompanied by a hollowing of the rotation profile near the magnetic axis. This effect appears to be due to the change in electron collisionality, consistent with another theoretical, gyrokinetic prediction. The variety of phenomena that could allow ECH to modify the intrinsic rotation profile give some expectation that regions of large velocity shear in the interior could be generated, with the possibility of triggering internal transport barriers.

  12. Rotated waveplates in integrated waveguide optics

    PubMed Central

    Corrielli, Giacomo; Crespi, Andrea; Geremia, Riccardo; Ramponi, Roberta; Sansoni, Linda; Santinelli, Andrea; Mataloni, Paolo; Sciarrino, Fabio; Osellame, Roberto

    2014-01-01

    Controlling and manipulating the polarization state of a light beam is crucial in applications ranging from optical sensing to optical communications, both in the classical and quantum regime, and ultimately whenever interference phenomena are to be exploited. In addition, many of these applications present severe requirements of phase stability and greatly benefit from a monolithic integrated-optics approach. However, integrated devices that allow arbitrary transformations of the polarization state are very difficult to produce with conventional lithographic technologies. Here we demonstrate waveguide-based optical waveplates, with arbitrarily rotated birefringence axis, fabricated by femtosecond laser pulses. To validate our approach, we exploit this component to realize a compact device for the quantum state tomography of two polarization-entangled photons. This work opens perspectives for integrated manipulation of polarization-encoded information with relevant applications ranging from integrated polarimetric sensing to quantum key distribution. PMID:24963757

  13. Stresses in rotating composite cylindrical shells

    NASA Astrophysics Data System (ADS)

    Wang, James T.-S.; Lin, Chien-Chang

    Stresses in composite cylindrical shells rotating with a constant speed about their longitudinal axis are analyzed. Each ply or ply group is treated as a separate thin layer of homogeneous and orthotropic material under the interfacial stresses as surface loading. There is no limitation on the total thickness of the shell. The circumferential stress, motivated by the conventional thin shell theory, is assumed to vary linearly through the thickness of the layer. The radial stress is determined in terms of the circumferential stress through the equilibrium condition, and an average compatibility condition through the thickness of the thin layer is used. Numerical results using the present analysis show nearly perfect agreement with the exact solution for homogeneous and isotropic cylinders. Some results for cylinders having orthotropic layers are presented for illustrative purposes.

  14. Scaling of rotational inertia in murine rodents and two species of lizard.

    PubMed

    Walter, Rebecca M; Carrier, David R

    2002-07-01

    Because the force required to rotate a body about an axis is directly proportional to its rotational inertia about the axis, it is likely that animals with high rotational inertia would be constrained in their turning abilities. Given that rotational inertia scales with mass(1.67) in geometrically similar animals, whereas the ability to apply torque scales with mass(1.00), larger animals would be expected to have more difficulty turning than smaller animals of similar shape. To determine how rotational inertia scales with body mass, we used the fact that the period of a physical pendulum is proportional to its rotational inertia(0.50), and measured rotational inertia in two groups of vertebrates with greatly different body shapes: murine rodents (Mus domesticus and Rattus norvegicus) and lizards (Iguana iguana and Varanus exanthematicus). Rotational inertia did not deviate significantly from isometric scaling in the murine rodents as a group or in the varanid lizards, scaling with mass(1.63) and mass(1.59), respectively. Although rotational inertia did scale with negative allometry in iguanas and rats alone, with mass(1.56) and mass(1.42), respectively, it still increased much more quickly with increasing mass than the predicted ability to apply torque. This suggests either that these animals are not constrained by rotational inertia because of their relatively small size or that larger rodents and lizards are poorer turners than smaller ones. The murine rodents had a 3.0- to 4.9-fold lower rotational inertia than similarly sized lizards of either species. Given that the basal synapsids had body proportions and limb configurations similar to those of modern lizards, we suggest that the loss of the large muscular tail and elongated body form during the evolution of cynodonts and mammals reduced rotational inertia and probably improved turning ability.

  15. Seismic constraints on rotation of Sun-like star and mass of exoplanet

    PubMed Central

    Gizon, Laurent; Ballot, Jérome; Michel, Eric; Stahn, Thorsten; Vauclair, Gérard; Bruntt, Hans; Quirion, Pierre-Olivier; Benomar, Othman; Vauclair, Sylvie; Appourchaux, Thierry; Auvergne, Michel; Baglin, Annie; Barban, Caroline; Baudin, Fréderic; Bazot, Michaël; Campante, Tiago; Catala, Claude; Chaplin, William; Creevey, Orlagh; Deheuvels, Sébastien; Dolez, Noël; Elsworth, Yvonne; García, Rafael; Gaulme, Patrick; Mathis, Stéphane; Mathur, Savita; Mosser, Benoît; Régulo, Clara; Roxburgh, Ian; Salabert, David; Samadi, Réza; Sato, Kumiko; Verner, Graham; Hanasoge, Shravan; Sreenivasan, Katepalli R.

    2013-01-01

    Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing to the scarcity of observations of rotation and magnetic fields in stars. Here, inferences are drawn on the internal rotation of a distant Sun-like star by studying its global modes of oscillation. We report asteroseismic constraints imposed on the rotation rate and the inclination of the spin axis of the Sun-like star HD 52265, a principal target observed by the CoRoT satellite that is known to host a planetary companion. These seismic inferences are remarkably consistent with an independent spectroscopic observation (rotational line broadening) and with the observed rotation period of star spots. Furthermore, asteroseismology constrains the mass of exoplanet HD 52265b. Under the standard assumption that the stellar spin axis and the axis of the planetary orbit coincide, the minimum spectroscopic mass of the planet can be converted into a true mass of , which implies that it is a planet, not a brown dwarf. PMID:23898183

  16. Seismic constraints on rotation of Sun-like star and mass of exoplanet.

    PubMed

    Gizon, Laurent; Ballot, Jérome; Michel, Eric; Stahn, Thorsten; Vauclair, Gérard; Bruntt, Hans; Quirion, Pierre-Olivier; Benomar, Othman; Vauclair, Sylvie; Appourchaux, Thierry; Auvergne, Michel; Baglin, Annie; Barban, Caroline; Baudin, Fréderic; Bazot, Michaël; Campante, Tiago; Catala, Claude; Chaplin, William; Creevey, Orlagh; Deheuvels, Sébastien; Dolez, Noël; Elsworth, Yvonne; García, Rafael; Gaulme, Patrick; Mathis, Stéphane; Mathur, Savita; Mosser, Benoît; Régulo, Clara; Roxburgh, Ian; Salabert, David; Samadi, Réza; Sato, Kumiko; Verner, Graham; Hanasoge, Shravan; Sreenivasan, Katepalli R

    2013-08-13

    Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing to the scarcity of observations of rotation and magnetic fields in stars. Here, inferences are drawn on the internal rotation of a distant Sun-like star by studying its global modes of oscillation. We report asteroseismic constraints imposed on the rotation rate and the inclination of the spin axis of the Sun-like star HD 52265, a principal target observed by the CoRoT satellite that is known to host a planetary companion. These seismic inferences are remarkably consistent with an independent spectroscopic observation (rotational line broadening) and with the observed rotation period of star spots. Furthermore, asteroseismology constrains the mass of exoplanet HD 52265b. Under the standard assumption that the stellar spin axis and the axis of the planetary orbit coincide, the minimum spectroscopic mass of the planet can be converted into a true mass of 1.85(-0.42)(+0.52)M(Jupiter), which implies that it is a planet, not a brown dwarf.

  17. Wave-driven Rotation in Supersonically Rotating Mirrors

    SciTech Connect

    A. Fetterman and N.J. Fisch

    2010-02-15

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  18. Accurate free and forced rotational motions of rigid Venus

    NASA Astrophysics Data System (ADS)

    Cottereau, L.; Souchay, J.; Aljbaae, S.

    2010-06-01

    Context. The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting because it can be compared with that of Earth for which such a modelling has already been achieved at the milli-arcsecond level. Aims: We aim to complete a previous study, by determining the polhody at the milli-arcsecond level, i.e. the torque-free motion of the angular momentum axis of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view. Methods: We use the same theoretical framework as Kinoshita (1977, Celest. Mech., 15, 277) did to determine the precession-nutation motion of a rigid Earth. It is based on a representation of the rotation of a rigid Venus, with the help of Andoyer variables and a set of canonical equations in Hamiltonian formalism. Results: In a first part we computed the polhody, we showed that this motion is highly elliptical, with a very long period of 525 cy compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we precisely computed the Oppolzer terms, which allow us to represent the motion in space of the third Venus figure axis with respect to the Venus angular momentum axis under the influence of the solar gravitational torque. We determined the corresponding tables of the nutation coefficients of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We showed that the nutation coefficients for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration, which revealed the indirect planetary effects.

  19. Turbulent Compressible Convection with Rotation. 2; Mean Flows and Differential Rotation

    NASA Technical Reports Server (NTRS)

    Brummell, Nicholas H.; Hurlburt, Neal E.; Toomre, Juri

    1998-01-01

    The effects of rotation on turbulent, compressible convection within stellar envelopes are studied through three-dimensional numerical simulations conducted within a local f-plane model. This work seeks to understand the types of differential rotation that can be established in convective envelopes of stars like the Sun, for which recent helioseismic observations suggest an angular velocity profile with depth and latitude at variance with many theoretical predictions. This paper analyzes the mechanisms that are responsible for the mean (horizontally averaged) zonal and meridional flows that are produced by convection influenced by Coriolis forces. The compressible convection is considered for a range of Rayleigh, Taylor, and Prandtl (and thus Rossby) numbers encompassing both laminar and turbulent flow conditions under weak and strong rotational constraints. When the nonlinearities are moderate, the effects of rotation on the resulting laminar cellular convection leads to distinctive tilts of the cell boundaries away from the vertical. These yield correlations between vertical and horizontal motions that generate Reynolds stresses that can drive mean flows, interpretable as differential rotation and meridional circulations. Under more vigorous forcing, the resulting turbulent convection involves complicated and contorted fluid particle trajectories, with few clear correlations between vertical and horizontal motions, punctuated by an evolving and intricate downflow network that can extend over much of the depth of the layer. Within such networks are some coherent structures of vortical downflow that tend to align with the rotation axis. These yield a novel turbulent alignment mechanism, distinct from the laminar tilting of cellular boundaries, that can provide the principal correlated motions and thus Reynolds stresses and subsequently mean flows. The emergence of such coherent structures that can persist amidst more random motions is a characteristic of turbulence

  20. Two-dimensionalization of the flow driven by a slowly rotating impeller in a rapidly rotating fluid

    NASA Astrophysics Data System (ADS)

    Machicoane, Nathanaël; Moisy, Frédéric; Cortet, Pierre-Philippe

    2016-11-01

    We characterize the two-dimensionalization process in the turbulent flow produced by an impeller rotating at a rate ω in a fluid rotating at a rate Ω around the same axis for Rossby number Ro=ω /Ω down to 10-2. The flow can be described as the superposition of a large-scale vertically invariant global rotation and small-scale shear layers detached from the impeller blades. As Ro decreases, the large-scale flow is subjected to azimuthal modulations. In this regime, the shear layers can be described in terms of wakes of inertial waves traveling with the blades, originating from the velocity difference between the nonaxisymmetric large-scale flow and the blade rotation. The wakes are well defined and stable at low Rossby number, but they become disordered at Ro of order of 1. This experiment provides insight into the route towards pure two-dimensionalization induced by a background rotation for flows driven by a nonaxisymmetric rotating forcing.