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Sample records for off-vertical axis rotation

  1. 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

  2. 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.

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

    PubMed

    Merfeld, D M

    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. PMID:8749160

  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. Translational otolith-ocular reflex during off-vertical axis rotation in humans.

    PubMed

    Clément, Gilles; Wood, Scott J

    2016-03-11

    Two characteristics of otolith-ocular responses - linear vestibulo-ocular reflex and vergence - were examined during constant velocity off-vertical axis rotation (OVAR) in the dark. Sixteen subjects were rotated about their longitudinal axis when tilted 30° relative to the direction of gravity. Rotational velocities were 36 and 288/s corresponding to frequencies of 0.1 and 0.8Hz, respectively. Subjects were asked to imagine stationary targets located at 0.5m, 1m, and 2m in the straight-ahead direction. Binocular eye movements were recorded in the dark using infrared videography. The modulation of horizontal slow phase velocity during OVAR was larger at 0.8Hz than at 0.1Hz, and the modulation at the high frequency was larger for the near target than for the mid and far targets. These characteristics confirm that the horizontal slow phase velocity during yaw OVAR represents a translational otolith-ocular reflex in response to acceleration along the inter-aural axis that is dependent on imagined fixation distance.

  7. Parabrachial nucleus neuronal responses to off-vertical axis rotation in macaques

    PubMed Central

    McCandless, Cyrus H.; Balaban, Carey D.

    2010-01-01

    The caudal aspect of the parabrachial nucleus (PBN) contains neurons responsive to whole body, periodic rotational stimulation in alert monkeys. This study characterizes the angular and linear motion-sensitive response properties of PBN unit responses during off-vertical axis rotation (OVAR) and position trapezoid stimulation. The OVAR responses displayed a constant firing component which varied from the firing rate at rest. Nearly two-thirds of the units also modulated their discharges with respect to head orientation (re: gravity) during constant velocity OVAR stimulation. The modulated response magnitudes were equal during ipsilateral and contralateral OVARs, indicative of a one-dimensional accelerometer. These response orientations during OVAR divided the units into three spatially tuned populations, with peak modulation responses centered in the ipsilateral ear down, contralateral anterior semicircular canal down, and occiput down orientations. Because the orientation of the OVAR modulation response was opposite in polarity to the orientation of the static tilt component of responses to position trapezoids for the majority of units, the linear acceleration responses were divided into colinear dynamic linear and static tilt components. The orientations of these unit responses formed two distinct population response axes: (1) units with an interaural linear response axis and (2) units with an ipsilateral anterior semicircular canal-contralateral posterior semicircular canal plane linear response axis. The angular rotation sensitivity of these units is in a head-vertical plane that either contains the linear acceleration response axis or is perpendicular to the linear acceleration axis. Hence, these units behave like head-based (‘strap-down’) inertial guidance sensors. Because the PBN contributes to sensory and interoceptive processing, it is suggested that vestibulo-recipient caudal PBN units may detect potentially dangerous anomalies in control of postural

  8. 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

  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. 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.

  11. 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.

  12. Evaluation of the otolith function using sinusoidal off-vertical axis rotation in patients with benign paroxysmal positional vertigo.

    PubMed

    Sugita-Kitajima, Akemi; Azuma, Miki; Hattori, Kosuke; Koizuka, Izumi

    2007-07-01

    The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate the otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60 degrees s(-1) in earth-vertical axis rotation (EVAR) and OVAR. Twenty-three controls and 24 BPPV patients were investigated. Results showed that VOR gain during OVAR at 0.8 Hz in a 30 degrees nose-up position in BPPV patients was significantly less than the gain during EVAR, whereas the gain was not significantly different between EVAR and OVAR in the controls in each condition. In addition, to examine each type of BPPV, we also investigated whether there were any differences between the patients who suffered from dizziness and those who did not. VOR gain in OVAR of BPPV patients who were suffering from dizziness was significantly less than that of BPPV patients without dizziness. Not only cupulolithiasis or canalolithiasis, but also otolith dysfunction was considered to be the possible origin of BPPV. Because sinusoidal OVAR produced minimal nausea compared to constant velocity OVAR, the stimulation of 0.8 Hz nose-up in sinusoidal OVAR may be used to evaluate otolith function without discomfort for patients. PMID:17597299

  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 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Interplay between tilted and principal axis rotation

    SciTech Connect

    Datta, Pradip

    2014-08-14

    At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely {sup 109,110}Ag and {sup 108,110}Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay.

  2. 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.

  3. An off-axis rotating atom trap.

    PubMed

    Wu, J; Moscatelli, F; Oh, E

    2006-06-12

    We present a novel configuration of a magneto-optical trap for cold atoms. The trap is very simple in design, employing only a small permanent magnet and an external Helmholtz bias coil. The trap's principal advantage is that the entire volume of the overlapping laser beams can be used for atom guiding and manipulation. An especially interesting effect is the rotation of the trapped atoms in circular motion as the permanent magnet is rotated. Clouds containing on the order of 2*10(6) atoms are rotated up to 60Hz forming a 5 mm diameter ring. This rotation can potentially be used in studying the behavior of cold atoms in 2-dimensional potential as well as applications for rotational sensors. We also present a classical theoretical model to simulate the experiment.

  4. Fixed Exit Monochromator with fixed Rotation Axis

    SciTech Connect

    Caliebe, W.A.; Cheung, S.; Lenhard, A.; Siddons, D.P.

    2004-05-12

    A new simple design for a fixed-exit monochromator has been developed. The set-up uses a linear slide to couple the rotation of the crystals to a translation of the second one to compensate for the 2hcos{theta} dependence of the beam-offset in a double crystal monochromator. This set-up requires just one motor for the rotation of the monochromator, and three piezo-actuators to tune the second crystal.The monochromator has been tested for Bragg-angles between 7 deg. and 70 deg.

  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. Manipulating cold atoms with off-axis rotating traps

    NASA Astrophysics Data System (ADS)

    Oh, Eun; Du, Shengwang

    2013-08-01

    We investigate classical motions of cold atoms in three types (harmonic, linear, and Gaussian) of off-axis rotating traps in the presence of damping forces. When the radius of rotation of the trap is within the trap volume, the atoms are always attracted towards the rotation's origin if the damping rate Γ is larger than the trap frequency ω ( i.e., Γ > ω). This is opposed to being repelled by the centrifugal force in a rotating reference frame. Contrarily, when the trap's rotation radius is larger than the trap size, the atoms experience a time-averaged ring-shape trap at a high rotational frequency. These anomalous properties can be used to realize high-speed rotation sensors and effective static ring-trap potentials for manipulating cold atoms.

  8. Abrupt change of rotation axis in {sup 109}Ag

    SciTech Connect

    Datta, P.; Pal, S.; Chattopadhyay, S.; Bhattacharya, S.; Goswami, A.; Sarkar, M. Saha; Sun, Y.; Rao, P. V. Madhusudhana; Bhowmik, R. K.; Kumar, R.; Madhavan, N.; Muralithar, S.; Singh, R. P.; Jain, H. C.; Joshi, P. K.; Amita

    2008-08-15

    The electromagnetic transition rates for all the high spin levels of the yrast sequence of {sup 109}Ag have been measured. The observed behavior of the magnetic dipole transition rates as a function of angular momentum establishes that there is a sudden change in rotation axis associated with rotational alignment of two neutrons. The projected shell model calculations give a consistent picture of the observed phenomena in {sup 109}Ag.

  9. The anatomical tibial axis: reliable rotational orientation in knee replacement.

    PubMed

    Cobb, J P; Dixon, H; Dandachli, W; Iranpour, F

    2008-08-01

    The rotational alignment of the tibia is an unresolved issue in knee replacement. A poor functional outcome may be due to malrotation of the tibial component. Our aim was to find a reliable method for positioning the tibial component in knee replacement. CT scans of 19 knees were reconstructed in three dimensions and orientated vertically. An axial plane was identified 20 mm below the tibial spines. The centre of each tibial condyle was calculated from ten points taken round the condylar cortex. The tibial tubercle centre was also generated as the centre of the circle which best fitted eight points on the outside of the tubercle in an axial plane at the level of its most prominent point. The derived points were identified by three observers with errors of 0.6 mm to 1 mm. The medial and lateral tibial centres were constant features (radius 24 mm (SD 3), and 22 mm (SD 3), respectively). An anatomical axis was created perpendicular to the line joining these two points. The tubercle centre was found to be 20 mm (SD 7) lateral to the centre of the medial tibial condyle. Compared with this axis, an axis perpendicular to the posterior condylar axis was internally rotated by 6 degrees (SD 3). An axis based on the tibial tubercle and the tibial spines was also internally rotated by 5 degrees (sd 10). Alignment of the knee when based on this anatomical axis was more reliable than either the posterior surfaces or any axis involving the tubercle which was the least reliable landmark in the region.

  10. 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.

  11. 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

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

    NASA Astrophysics Data System (ADS)

    Fanelli, Francesco

    2016-04-01

    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.

  13. About the Reference Axis Of The Rotation Of The Earth

    NASA Astrophysics Data System (ADS)

    Vicente, R. O.

    2006-08-01

    The dynamical theory of the motion of the Earth is developed in such a way that considers the centre of mass of the Earth as a fixed point and it shows the existence of 3 axes(rotation, figure and angular momentum) that can be adopted for any system of celestial or terrestrial coordinates. Some of the theories developed do not clearly specify which of these axes is adopted as a reference axis. This is nowadays very important because of the modern observational techniques, for instance, VLBI, SLR and GPS, leading to precisions, at least, of milli-arc-seconds. Another approach is to try to define a reference axis from the astronomical observations. It has the advantage that we are dealing with observed values and not theoretical models. We have nowadays a better knowledge about the Chandler and annual components of polar motion than when this approach was employed in the definition of the Conventional International Origin (CIO) in 1967, which was adopted by the IAU and IUGG as a standard of any reference system. The reduction of about 20 years of modern observations permits us to define a better reference axis and, therefore, another conventional origin called Conventional International Reference Origin (CIRO). It should be emphasized the need for such an improved reference axis and it is proposed its adoption as a new international standard.

  14. Lightcurves and the axis of rotation of 433 Eros

    NASA Technical Reports Server (NTRS)

    Dunlap, J. L.

    1976-01-01

    Ten lightcurves and UBV photometry of 433 Eros were obtained between August 1972 and May 1975. The absolute magnitude of the lightcurve maximum is 10.75 and the phase coefficient is 0.025 mag/deg. There may be a small difference in B-V color between the northern and southern hemispheres. The pole of the axis of rotation is directed toward 16 deg, ecliptic longitude and 12 deg ecliptic latitude, respectively, and the rotation is direct with a sidereal period of 5 hr 16 min 13.4 sec. The dimensions derived from the polarimetric albedo and the lightcurve amplitudes are 12 km by 12 km by 31 km for a smooth cylinder with hemispherical ends.

  15. Surgical epicondylar axis vs anatomical epicondylar axis for rotational alignment of the femoral component in total knee arthroplasty.

    PubMed

    Tanavalee, A; Yuktanandana, P; Ngarmukos, C

    2001-06-01

    The anatomical epicondylar (AEpi) axis and the surgical epicondylar (SEpi) axis have been widely used as the epicondylar axis, one of the most commonly used axes for rotational alignment of the femoral component in total knee arthroplasty. The purpose of this study was to evaluate the differences and reliability between these two axes. Computerized tomography scan of the distal femur was done in 55 osteoarthritic knees. Thirty-two knees were varus and 23 knees were neutral in alignment. Axes for rotational alignment of the femoral component were lined including posterior condylar (PC), anteroposterior (AP), AEpi, and SEpi axes. Angles between each pair of axes were measured including PC-AEpi, PC-SEpi, AP-AEpi, AP-SEpi and AP-PC. The average PC-AEpi angle was 5.7 degrees +/- 1.7 degrees. The average PC-SEpi angle was 1.5 degrees +/- 2.1 degrees. The average AP-AEpi angle was 90.2 degrees +/- 1.0 degrees. The average AP-SEpi angle was 94.5 degrees +/- 1.3 degrees and the average AP-PC angle was 95.9 degrees +/- 2.0 degrees. Twenty-nine per cent of knees had prominent medial epicondyle (a landmark for AEpi axis) and 5 per cent had prominent medial sulcus (a landmark for SEpi axis). The lateral epicondyle was prominent in all knees. There were no significant differences of all angles of referencing axes between men and women (p>0.05). There were no significant differences between varus and neutral knees in terms of PC-AEpi angle and PC-SEpi angle (p>0.05). The AEpi axis was more perpendicular to the AP axis and more external rotated to the PC axis than the SEpi axis. Because the perpendicular line to the AEpi axis was closer to the AP axis than that of the SEpi axis and the AEpi axis provided appropriate external rotated to the PC axis, the AEpi axis was more reliable for rotational alignment of the femoral component than the SEpi axis. On the other hand, SEpi axis, providing less external rotated to the PC axis, may be difficult to define and could cause

  16. Characteristics of Friedel pairs and diffraction contrast tomography with non-perpendicular rotation axis.

    PubMed

    Yi, Qiru; Li, Gang; Zhang, Jie; Luo, Sheng Nian; Fan, Duan; Gao, Zhenhua; Wang, Yanping; Gao, Guanfeng; Jiang, Shiping; Jiang, Xiaoming

    2015-07-01

    The characteristics of Friedel pairs in diffraction contrast tomography (DCT) are studied in the condition that the rotation axis of the sample is not exactly perpendicular to the incident X-ray direction. For the rotation axis approximately aligned along the vertical direction, the Friedel pairs close to the horizontal plane are insensitive to the non-perpendicularity of the rotation axis, and can be used to refine the sample-to-detector distance and X-ray energy, while the Friedel pairs close to the vertical direction are sensitive to the non-perpendicularity of the rotation axis, and can be used to determine the rotation axis orientation. The correct matching proportion of Friedel pairs decreases with increasing non-perpendicularity of the rotation axis. A method of data processing considering rotation axis misalignment is proposed, which significantly increases the correct matching and indexing proportions of the diffraction spots. A pure aluminium polycrystalline sample is investigated using DCT at beamline 4W1A of Beijing Synchrotron Radiation Facility. Based on the analysis of Friedel pairs, the sample-to-detector distance and X-ray energy are refined to be 8.67 mm and 20.04 keV, respectively. The non-perpendicular angle of the rotation axis is calculated to be 0.10°. With these refined geometric parameters, the matching proportion of the spatial position of diffraction spots is 90.62%. Three-dimensional reconstruction of the sample with 13 grains is realised using the algebraic reconstruction technique. It is demonstrated that the precise correction of the orientation of the sample rotation axis is effective in DCT suffering from rotation axis misalignment, and the higher accuracy in determining the rotation axis is expected to improve the reconstruction precision of grains. PMID:26134812

  17. Radiographic determinants of the elbow rotation axis: experimental identification and quantitative validation.

    PubMed

    Bottlang, M; O'Rourke, M R; Madey, S M; Steyers, C M; Marsh, J L; Brown, T D

    2000-09-01

    This study identifies new radiographic indices to approximate the location of the elbow rotational axis. With use of electromagnetic motion tracking source data, the average rotational axis of the ulnohumeral articulation was calculated in seven cadaveric specimens. Quasi-lateral radiographs of the elbow specimens were then analyzed to identify radiographic landmarks of the elbow axis in the lateral view. The spatial relationships of these landmarks with the elbow aligned on-axis were contrasted with their relationships in eight distinct off-axis alignments. Elbow axis orientation in the transverse plane (internal/external rotation) was identified by the location of a dense intramedullary cortical line, appearing in the projection of the distal humerus in relation to the periosteal surface of the posterior cortex of the humerus. This intramedullary line corresponds to the posteromedial cortex of the distal humerus. Correct alignment occurred when this line laid 27.1+/-3.7% of the anteroposterior humeral diameter anterior from the periosteal surface of the posterior cortex. Axis orientation in the coronal plane (abduction/adduction) was identified by the concentric appearance of radiographic arcs formed by the capitellum, trochlear sulcus, and medial trochlear flange. Using these radiographic indices, three orthopaedic surgeons were able to fluoroscopically align the elbow along the axis of rotation with an accuracy of 3.7+/-1.8 degrees. These results are immediately applicable to fluoroscopic identification of the elbow axis. This technique can be used to increase the accuracy of hinge placement during application of hinged external fixation or distraction arthroplasty.

  18. 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.

  19. Effects of the axis of rotation and primordially solicited limb of high level athletes in a mental rotation task.

    PubMed

    Habacha, Hamdi; Lejeune-Poutrain, Laure; Margas, Nicolas; Molinaro, Corinne

    2014-10-01

    A recent set of studies has investigated the selective effects of particular physical activities that require full-body rotations, such as gymnastics and wrestling (Moreau, Clerc, Mansy-Dannay, & Guerrien, 2012; Steggemann, Engbert, & Weigelt, 2011), and demonstrated that practicing these activities imparts a clear advantage in in-plane body rotation performance. Other athletes, such as handball and soccer players, whose activities do require body rotations may have more experience with in-depth rotations. The present study examined the effect of two components that are differently solicited in sport practices on the mental rotation ability: the rotation axis (in-plane, in-depth) and the predominantly used limb (arms, legs). Handball players, soccer players, and gymnasts were asked to rotate handball and soccer strike images mentally, which were presented in different in-plane and in-depth orientations. The results revealed that handball and soccer players performed the in-depth rotations faster than in-plane rotations; however, the two rotation axes did not differ in gymnasts. In addition, soccer players performed the mental rotations of handball strike images slower. Our findings suggest that the development of mental rotation tasks that involve the major components of a physical activity allows and is necessary for specifying the links between this activity and the mental rotation performance.

  20. Effects of the axis of rotation and primordially solicited limb of high level athletes in a mental rotation task.

    PubMed

    Habacha, Hamdi; Lejeune-Poutrain, Laure; Margas, Nicolas; Molinaro, Corinne

    2014-10-01

    A recent set of studies has investigated the selective effects of particular physical activities that require full-body rotations, such as gymnastics and wrestling (Moreau, Clerc, Mansy-Dannay, & Guerrien, 2012; Steggemann, Engbert, & Weigelt, 2011), and demonstrated that practicing these activities imparts a clear advantage in in-plane body rotation performance. Other athletes, such as handball and soccer players, whose activities do require body rotations may have more experience with in-depth rotations. The present study examined the effect of two components that are differently solicited in sport practices on the mental rotation ability: the rotation axis (in-plane, in-depth) and the predominantly used limb (arms, legs). Handball players, soccer players, and gymnasts were asked to rotate handball and soccer strike images mentally, which were presented in different in-plane and in-depth orientations. The results revealed that handball and soccer players performed the in-depth rotations faster than in-plane rotations; however, the two rotation axes did not differ in gymnasts. In addition, soccer players performed the mental rotations of handball strike images slower. Our findings suggest that the development of mental rotation tasks that involve the major components of a physical activity allows and is necessary for specifying the links between this activity and the mental rotation performance. PMID:25064695

  1. 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.

  2. 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.

  3. An additional reference axis for determining rotational alignment of the femoral component in total knee arthroplasty.

    PubMed

    Won, Ye-Yeon; Cui, Wen-Quan; Baek, Myong-Hyun; Yun, Tae-Bong; Han, Seung-Ho

    2007-10-01

    No studies have examined the trochlear line connecting the most anterior projections of the lateral and medial femoral condyles in relation to the surgical epicondylar axis. To determine if the trochlear line is more consistent relative to the transepicondylar axis than the posterior condylar axis and the Whiteside's line, the angles between the surgical epicondylar axis and each of the 3 axes in 50 knees of cadavers were measured using computed tomography scans. The results showed that the variability in the trochlear line for referencing the transepicondylar axis was comparable to those of the Whiteside line and the posterior condylar axis. The trochlear line may be considered as an additional reference axis for determining the rotational alignment of the femoral component in total knee arthroplasty.

  4. Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis.

    PubMed

    Berger, R A; Rubash, H E; Seel, M J; Thompson, W H; Crossett, L S

    1993-01-01

    The posterior condylar surfaces of the femur are routinely used as the reference for the rotational orientation of the femoral component during most primary total knee arthroplasties. The purpose of this investigation was to identify a clearly discernible, reproducible secondary anatomic axis useful for determining the rotational orientation of the femoral component when the posterior condylar surfaces cannot be used. Seventy-five embalmed anatomic specimen femurs were studied. A surgical epicondylar axis was defined as the line connecting the lateral epicondylar prominence and the medial sulcus of the medial epicondyle. The posterior condylar angle was measured as the angle between the posterior condylar surfaces and the surgical epicondylar axis. Measurement of the posterior condylar angle referenced from the surgical epicondylar axis yielded a mean posterior condylar angle of 3.5 degrees (+/- 1.2 degrees) of internal rotation for males and a mean posterior condylar angle of 0.3 degree (+/- 1.2 degrees) of internal rotation for females. Thus, rotational alignment of the femoral component can be accurately estimated using the posterior condylar angle. The posterior condylar angle, referenced from the surgical epicondylar axis, provides a visual rotational alignment check during primary arthroplasty and may improve alignment of the femoral component at revision.

  5. 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.

  6. Reliability of the anteroposterior axis and the posterior condylar axis for determining rotational alignment of the femoral component in total knee arthroplasty.

    PubMed

    Nagamine, R; Miura, H; Inoue, Y; Urabe, K; Matsuda, S; Okamoto, Y; Nishizawa, M; Iwamoto, Y

    1998-01-01

    We examined the reliability of the anteroposterior and posterior condylar axes for determining rotational alignment of the femoral component in total knee arthroplasty (TKA). A computed tomography scan was taken at the level of the femoral epicondyle in 84 knees (27 varus knees with medial femorotibial arthritis (FT-OA) in 26 patients, 17 knees with patellofemoral arthritis in 14 patients, and 40 normal knees in 40 volunteers). On the image, an anteroposterior axis, a line perpendicular to the anteroposterior axis, an epicondylar axis and a posterior condylar axis were drawn, and the relationship between the three axes was assessed. The mean values for the 84 knees were evaluated, and the posterior condylar axis was 6.0 degrees +/- 2.4 degrees internally rotated relative to the epicondylar axis, while the line perpendicular to the anteroposterior axis was 1.4 degrees +/- 3.3 degrees internally rotated relative to the epicondylar axis. The internal rotation angle of the posterior condylar axis relative to the epicondylar axis was 6.2 degrees +/- 1.9 degrees in the knees with medial femorotibial arthritis, 6.4 degrees +/- 2.4 degrees in the knees with patellofemoral arthritis, and 5.8 degrees +/- 2.7 degrees in the normal knees, showing consistent values in normal and osteoarthritic knees. The internal rotation angle of the line perpendicular to the anteroposterior axis relative to the epicondylar axis was 0.1 degrees +/- 3.3 degrees, 1.3 degrees +/- 3. 3 degrees, and 2.3 degrees +/- 3.1 degrees in the three groups, respectively (i.e., there were significant differences between the medial FT-OA knees and the normal knees). The results demonstrated that the anteroposterior axis was rotated externally to a significant degree in medial FT-OA knees and was less reliable than the posterior condylar axis for use in alignment for TKA on medial FT-OA knees.

  7. 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.

  8. Effects of surface reflectance and 3D shape on perceived rotation axis.

    PubMed

    Doerschner, Katja; Yilmaz, Ozgur; Kucukoglu, Gizem; Fleming, Roland W

    2013-09-10

    Surface specularity distorts the optic flow generated by a moving object in a way that provides important cues for identifying surface material properties (Doerschner, Fleming et al., 2011). Here we show that specular flow can also affect the perceived rotation axis of objects. In three experiments, we investigate how three-dimensional shape and surface material interact to affect the perceived rotation axis of unfamiliar irregularly shaped and isotropic objects. We analyze observers' patterns of errors in a rotation axis estimation task under four surface material conditions: shiny, matte textured, matte untextured, and silhouette. In addition to the expected large perceptual errors in the silhouette condition, we find that the patterns of errors for the other three material conditions differ from each other and across shape category, yielding the largest differences in error magnitude between shiny and matte, textured isotropic objects. Rotation axis estimation is a crucial implicit computational step to perceive structure from motion; therefore, we test whether a structure from a motion-based model can predict the perceived rotation axis for shiny and matte, textured objects. Our model's predictions closely follow observers' data, even yielding the same reflectance-specific perceptual errors. Unlike previous work (Caudek & Domini, 1998), our model does not rely on the assumption of affine image transformations; however, a limitation of our approach is its reliance on projected correspondence, thus having difficulty in accounting for the perceived rotation axis of smooth shaded objects and silhouettes. In general, our findings are in line with earlier research that demonstrated that shape from motion can be extracted based on several different types of optical deformation (Koenderink & Van Doorn, 1976; Norman & Todd, 1994; Norman, Todd, & Orban, 2004; Pollick, Nishida, Koike, & Kawato, 1994; Todd, 1985).

  9. 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.

  10. 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.

  11. The anteroposterior axis for femoral rotational alignment in valgus total knee arthroplasty.

    PubMed

    Whiteside, L A; Arima, J

    1995-12-01

    This study evaluated a technique using the anteroposterior axis of the distal femur, rather than the transepicondylar or posterior femoral condylar axis, to establish rotational alignment of the femoral component in valgus knees. The anteroposterior axis of the distal femur was defined by a line through the deepest part of the patellar groove anteriorly and the center of the intercondylar notch posteriorly. Total knee arthroplasty was done in 46 valgus knees between 1980 and 1986 using the posterior femoral condyles as landmarks for rotational alignment. From January 1986 through January 1992 total knee arthroplasty was done in 107 valgus knees using the anteroposterior axis for rotational alignment of the femoral component. In the group of knees using the posterior condylar axis, medial tibial tubercle transfer was needed intra-operatively in 8 knees to prevent lateral dislocation of the patella. In the first 2 postoperative years, 4 knees had recurrent patellar dislocation or subluxation that required surgical correction. In the group of knees using the anteroposterior axis, patellar tracking problems that required realignment were significantly reduced. One knee required medial tibial tubercle transfer to correct a Q angle > 20 degrees. In the remaining knees, the Q angle was < 10 degrees, and patellar tracking was acceptable. Two years after surgery, no knees had patellar instability.

  12. Paleomagnetic investigation of late Neogene vertical axis rotation and remagnetization in central coastal California

    NASA Astrophysics Data System (ADS)

    Horns, Daniel M.; Verosub, Kenneth L.

    1995-03-01

    Outcrops of shallow marine sedimentary rocks of the Neogene Purisima Formation and Santa Cruz Mudstone occur throughout the Santa Cruz Mountains and along the coast of Santa Cruz and San Mateo counties in California. Within the Santa Cruz Mountains, the Purisima Formation has been extensively folded and offset by reverse faults. Along the coast, the Purisima Formation and Santa Cruz Mudstone are only gently folded although the Purisima Formation is cut by the San Gregorio Fault Zone. Previous paleomagnetic studies have shown that vertical axis rotation has occurred within some parts of the San Gregorio Fault Zone. As part of a kinematic study of the San Gregorio Fault Zone, this paleomagnetic investigation of the Purisima Formation and Santa Cruz Mudstone was conducted to determine the extent of the vertical axis rotation. The characteristic paleomagnetic directions of the Purisima Formation and Santa Cruz Mudstone, which we interpret as the primary directions, indicate that a clockwise vertical axis rotation of 35 deg to 60 deg has occurred throughout the San Gregorio Zone, whereas no rotation has occurred away from the fault zone. This result suggests that vertical axis rotation is fundamentally related to shear across the San Gregorio Fault Zone. Our work also indicates that while the Purisima Formation and Santa Cruz Mudstone along the coast have retained their primary magnetizations, the Purisima Formation within the Santa Cruz Mountains has been remagnetized after folding.

  13. Long-axis rotation: the missing link in proximal-to-distal segmental sequencing.

    PubMed

    Marshall, R N; Elliott, B C

    2000-04-01

    Most assessments of segmental sequencing in throwing, striking or kicking have indicated a proximal-to-distal sequencing of end-point linear speeds, joint angular velocities, segment angular velocities and resultant joint moments. However, the role of long-axis rotations has not been adequately quantified and located in the proximal-to-distal sequence. The timing and importance of upper arm internal-external rotation and pronation-supination in the development of racquet head speed have been examined in the tennis serve and squash forehand drive and considered in relation to conventional concepts of proximal-to-distal sequencing. Both long-axis rotations reached their peak angular speeds late in both strokes, typically after shoulder flexion-extension, shoulder abduction-adduction and elbow extension. These results clarify and confirm the importance of upper limb long-axis rotations in the production of racquet head speed. It appears that traditional proximal-to-distal sequencing concepts are inadequate to describe accurately the complexity of the tennis serve or squash forehand drive. It is essential to consider upper arm and forearm longitudinal axis rotations in explaining the mechanics of these movements and in developing coaching emphases, strength training schedules and injury prevention programmes. PMID:10824641

  14. Triaxial shape with rotation around the longest principal axis in Gd142

    NASA Astrophysics Data System (ADS)

    Carlsson, B. G.; Ragnarsson, I.; Bengtsson, R.; Lieder, E. O.; Lieder, R. M.; Pasternak, A. A.

    2008-09-01

    The cranking model is used to describe rotational bands. We investigate the approach of using diabatic configurations and minimizing the particle-number projected energy in a mesh of both λ,Δ and deformation parameters. We use the method to interpret recent experimental data in Gd142 and conclude that for the highest spin states observed (I≈30), the nucleus is triaxial and builds spin by rotating around the classically unfavored longest axis.

  15. 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.

  16. Manifestation of the rotational Doppler effect by use of an off-axis optical vortex beam.

    PubMed

    Basistiy, I V; Slyusar, V V; Soskin, M S; Vasnetsov, M V; Bekshaev, A Ya

    2003-07-15

    We report what is to our knowledge the first all-optical detection of the frequency beats between Gaussian and Laguerre-Gaussian LG0(1) modes in their axial superposition, caused by the rotational Doppler effect. The relation between the observable off-axis optical vortex rotation and the rotational frequency shift of the Laguerre-Gaussian component is ascertained. The results can be used as a physical basis for recognition of Laguerre-Gaussian mode spectra along their orbital angular momenta.

  17. Forced vibration analysis of rotating structures with application to vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Lobitz, D. W.

    Predictive methods for the dynamic analysis of wind turbine systems are important for assessing overall structural integrity and fatigue life. For the former, the identification of resonance points (spectral analysis) is of primary concern. For the latter forced vibration analysis is necessary. These analyses are complicated by the fact that, for a spinning turbine, the stress-producing deformations take place in both fixed and rotating reference systems simultaneously. As an example, the tower of a horizontal axis wind turbine (HAWT) must be analyzed in a fixed frame, and the rotor in a rotating one. Forced vibration analysis is further complicated in that accurate models need to be developed for aeroload prediction. Methods which are available for forced vibration analysis of both horizontal and vertical axis machines are identified and the method which was developed for vertical axis wind turbines is emphasized, with some comparisons of the predictions to experimental data.

  18. 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.

  19. 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

  20. Antimagnetic rotation in 108,110In with tilted axis cranking relativistic mean-field approach

    NASA Astrophysics Data System (ADS)

    Sun, Wu-Ji; Xu, Hai-Dan; Li, Jian; Liu, Yong-Hao; Ma, Ke-Yan; Yang, Dong; Lu, Jing-Bing; Ma, Ying-Jun

    2016-08-01

    Based on tilted axis cranking relativistic mean-field theory within point-coupling interaction PC-PK1, the rotational structure and the characteristic features of antimagnetic rotation for ΔI = 2 bands in 108,110In are studied. Tilted axis cranking relativistic mean-field calculations reproduce the experimental energy spectrum well and are in agreement with the experimental I ∼ ω plot, although the calculated spin overestimates the experimental values. In addition, the two-shears-like mechanism in candidate antimagnetic rotation bands is clearly illustrated and the contributions from two-shears-like orbits, neutron (gd) orbits above Z = 50 shell and Z = 50, N = 50 core are investigated microscopically. The predicted B(E2), dynamic moment of inertia ℑ(2), deformation parameters β and γ, and ℑ(2)/B(E2) ratios in tilted axis cranking relativistic mean-field calculations are discussed and the characteristic features of antimagnetic rotation for the bands before and after alignment are shown. Supported by National Natural Science Foundation of China (11205068, 11205069, 11405072, 11475072, 11547308) and China Postdoctoral Science Foundation (2012M520667)

  1. Stationary observers on the symmetry axis of rotating supermassive black holes

    NASA Astrophysics Data System (ADS)

    Petrásek, Martin; Hledík, Stanislav

    2007-12-01

    Generalizing the results obtained by Semerák, O. (1993) [Semerák, O. (1993), Stationary Frames in the Kerr Field, Gen. Relativity Gravitation, 10 (1045)], an interesting difference between the Kerr and Kerr-de Sitter geometries has been found. In the case of freely falling stationary observers located on the axis of symmetry, rotating supermassive black holes (not necessarily fast rotating) behave differently from the same bodies for which the present value of cosmological constant is not included. An interesting family of "freely falling stationary observers" is described.

  2. A bead on a hoop rotating about a horizontal axis: A one-dimensional ponderomotive trap

    NASA Astrophysics Data System (ADS)

    Johnson, A. K.; Rabchuk, J. A.

    2009-11-01

    We describe a simple mechanical system that operates as a ponderomotive particle trap. The system consists of a circular hoop and a frictionless bead, with the hoop rotating about a horizontal axis lying in the plane of the hoop. The system is analyzed in the ideal case of small displacements from the minimum, and the motion of the particle is shown to satisfy the Mathieu equation. If the axis of rotation is tangential to the hoop, the system is an exact analog to the rf Paul ion trap. Various complicating factors such as anharmonic terms, friction, and noise are considered. A working model of the system was constructed using a ball-bearing rolling in a tube along the outside of a bicycle rim. The apparatus demonstrates the operation of an rf Paul trap by reproducing the dynamics of trapped atomic ions and illustrating the manner in which the electric potential varies with time.

  3. 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.

  4. The human torsional vestibulo-ocular reflex during rotation about an earth-vertical axis.

    PubMed

    Seidman, S H; Leigh, R J

    1989-12-18

    Using the magnetic search coil technique, we have measured the gain and time constant (Tvor) of the torsional vestibulo-ocular reflex (VOR) in 4 subjects who were rotated about an earth-vertical axis with their necks extended and faces supine. Following a 1-min period of rotation in darkness at 50 degrees/s, the post-rotational response to a velocity off-step had a group mean gain of 0.43 and Tvor of 3.7 s. Following a 1-min period of rotation in the light at 50 degrees/s, the post-rotational response in darkness had a group mean gain of 0.29 and Tvor of 4.1 s. Following rotation in darkness with the neck flexed and head prone, the post-rotational response, measured in two subjects, had a mean gain of 0.39 and Tvor of 5.7 s. Similar results were obtained with 100 degrees/s stimuli. In all subjects, the gain and Tvor of the torsional VOR were smaller than corresponding values for their horizontal VOR; these smaller values can be related to the different visual demands made of the torsional VOR.

  5. 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.

  6. 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.

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

    PubMed

    Merfeld, D M

    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

  8. 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.

  9. 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.

  10. 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.

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

    PubMed

    Wall, C; Furman, J M

    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 equally divided by gender for each decade. The subjects were rotated with eyes open in the dark, using clockwise and counterclockwise 60 degree/s velocity trapezoids. The nystagmus slow component velocity (SCV) was analysed using four parameters: Amp, Bias, Mod and Tau. Amp and Tau characterize the canal-ocular reflex to constant velocity steps, while Mod and Bias characterize the "AC" and "DC" components of the otolith-ocular reflex. Results indicated that intersubject variability was larger than that seen in earth-vertical axis data. Tau depended significantly (p less than 0.05) upon subject gender, while Mod increased monotonically with age decade. Linear regression showed a positive correlation between pairs of SCV magnitude parameters (Amp, Bias and Mod), suggesting a common scaling effect. In addition, there was a negative correlation between the value of the decay time constant Tau and each of the three magnitude parameters. Thus, despite large intersubject variability, parameters that describe earth-horizontal yaw axis responses are loosely interrelated and some of them vary significantly with gender and age.

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

    PubMed

    Wall, C; Furman, J M

    1990-01-01

    Visual-vestibular interaction (VVI) using 60 degrees/s constant velocity earth horizontal axis (EHA) yaw rotation was measured in 7 human subjects. This so-called 'barbecue spit' rotation stimulated both the horizontal semicircular canals and the otolith organs. 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). The resulting nystagmus slow component velocity (SCV) was analyzed. During EOD, subjects showed an exponentially decaying SCV response with a time constant of between 10 and 15 s that decayed to a non-zero baseline value (bias). Superimposed was a cyclic activity, modulation, whose period equalled the time for a complete revolution of the subject. During FIX, the average value of SCV was nearly zero indicating almost complete abolition of the exponential decay and bias components. The modulation component was reduced by half. During VVR, an exponential decay was observed in most subjects and the average value of the bias component nearly equalled that of the velocity of rotation. Modulation during VVR varied on a cycle-by-cycle basis. On average, the modulation component was nearly twice that for the EOD condition. We conclude that visual-vestibular interactions during EHA differ significantly from those during rotation about the vertical; specifically, there is a non-linear interaction between linear acceleration and optokinetic nystagmus.

  13. Vertical axis rotations in the Mojave: Evidence from the Independence dike swarm

    NASA Astrophysics Data System (ADS)

    Ron, Hagai; Nur, Amos

    1996-11-01

    The 500-km-long Late Jurassic Independence dike swarm in California extends from the central Sierra Nevada through the Mojave Desert to the Eastern Transverse Range. The dikes are mostly vertical, and their azimuth in the Sierra Nevada is ˜ 315°. However, in the Mojave region, their azimuth varies significantly: 300° 320° in the Argus Range, the Spangler Hills, and the Stoddard Well and Soda Mountain areas, and 340° 350° in the Granite Mountain, Alvord Mountain, and Eagle Mountain areas. Apparently the dikes in the Granite, Alvord, and Eagle mountains areas have rotated ˜ 50° clockwise about vertical axis relative to the Sierra Nevada and the Stoddard Well area. These rotations are remarkably consistent with known post early Miocene paleomagnetically derived rotations. The clockwise rotations are associated with the east-west trending left-lateral strike-slip faults in the northeastern Mojave and the Eastern Transverse range regions. In contrast, the data show that little or no rotation occurred in the central Mojave domain, which is characterized by northwest-trending faults.

  14. 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

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

    DOE PAGES

    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 ontomore » 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.« less

  16. 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.

  17. Late Cretaceous paleomagnetism of the Tucson Mountains: implications for vertical axis rotations in south central Arizona

    USGS Publications Warehouse

    Hagstrum, J.T.; Lipman, P.W.

    1991-01-01

    The Tucson Mountains of southern Arizona are the site of an Upper Cretaceous caldera from which the rhyolitic Cat Mountain Tuff was erupted at about 72 Ma. Two magnetic units within the Cat Mountain Tuff are distinguished by paleomagnetic data in both the northern and southern Tucson Mountains. The available paleomagnetic data indicate that rocks in southern Arizona have not remained unrotated with respect to North America since Late Cretaceous time and that vertical axis rotations may have played an important role in the region during Laramide deformation. -from Authors

  18. 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.

  19. 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.

  20. 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.

  1. 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%.

  2. Force field parameters for rotation around chi torsion axis in nucleic acids.

    PubMed

    Ode, Hirotaka; Matsuo, Yuri; Neya, Saburo; Hoshino, Tyuji

    2008-11-30

    To raise the accuracy of the force field for nucleic acids, several parameters were elaborated, focusing on the rotation around chi torsion axis. The reliability of molecular dynamics (MD) simulation was significantly increased by improving the torsion parameters at C8--N9--C1'--X (X = H1', C2', O4') in A, G and those at C6--N1--C1'--X in C, T, and U. In this work, we constructed small models representing the chemical structure of A, G, C, T, and U, and estimated energy profile for chi-axis rotation by executing numerous quantum mechanical (QM) calculations. The parameters were derived by discrete Fourier transformation of the calculated QM data. A comparison in energy profile between molecular mechanical (MM) calculation and QM one shows that our presently derived parameters well reproduce the energy surface of QM calculation for all the above torsion terms. Furthermore, our parameters show a good performance in MD simulations of some nucleic acids. Hence, the present refinement of parameters will enable us to perform more accurate simulations for various types of nucleic acids.

  3. Comet C/2013 X1 (PanSTARRS): Spin axis and rotation period

    NASA Astrophysics Data System (ADS)

    Manzini, Federico; Oldani, Virginio; Behrend, Raoul; Ochner, Paolo; Baransky, Alexandr; Starkey, Donn

    2016-09-01

    Applying image processing and enhancement techniques to our CCD images we could investigate the structures of the inner coma of comet C/2013 X1; the dust tail and a broad fan-shaped structure that originated from a different area of the nucleus than the tail were clearly detected. The triangular shape of the fan suggested that it was the result of a continuous outflow of dust from a single active source located at mid-high latitude (about 60° on a supposed spherical nucleus) on the surface of the comet's nucleus oriented in sunward direction, and that the comet's spin axis was placed near the sky plane. This allowed us to estimate its orientation at RA 240°±10° (=16h00 m) and declination +00°±10°. The fan structure remained quite stable in the 4-months observation period, indicating that the comet's spin axis remained steadily lying near the sky plane; a slow clockwise rotation of the fan in sunward direction appeared to be directly connected with the geometrical conditions of observation. Differential photometry applied to the inner coma, near the cometary nucleus, showed a light curve with an amplitude of 0.053 magnitudes, characterized by a highly repetitive periodicity throughout the entire observation period, and most likely related to the comet's rotation period, estimated at 0.498±0.015 days. Computer simulations of the coma features, as well as of the tail and spin axis positions, are fairly comparable with our observations, confirming the correctness of the findings.

  4. Axis of eye rotation changes with head-pitch orientation during head impulses about earth-vertical.

    PubMed

    Migliaccio, Americo A; Schubert, Michael C; Clendaniel, Richard A; Carey, John P; Della Santina, Charles C; Minor, Lloyd B; Zee, David S

    2006-06-01

    The goal of this study was to assess how the axis of head rotation, Listing's law, and eye position influence the axis of eye rotation during brief, rapid head rotations. We specifically asked how the axis of eye rotation during the initial angular vestibuloocular reflex (VOR) changed when the pitch orientation of the head relative to Earth-vertical was varied, but the initial position of the eye in the orbit and the orientation of Listing's plane with respect to the head were fixed. We measured three-dimensional eye and head rotation axes in eight normal humans using the search coil technique during head-and-trunk (whole-body) and head-on-trunk (head-only) "impulses" about an Earth-vertical axis. The head was initially oriented at one of five pitch angles (30 degrees nose down, 15 degrees nose down, 0 degrees, 15 degrees nose up, 30 degrees nose up). The fixation target was always aligned with the nasooccipital axis. Whole-body impulses were passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 80 degrees /s, and peak-acceleration of approximately 1000 degrees /s2. Head-only impulses were also passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 150 degrees /s, and peak-acceleration of approximately 3000 degrees /s2. During whole-body impulses, the axis of eye rotation tilted in the same direction, and by an amount proportional (0.51 +/- 0.09), to the starting pitch head orientation (P < 0.05). This proportionality constant decreased slightly to 0.39 +/- 0.08 (P < 0.05) during head-only impulses. Using the head-only impulse data, with the head pitched up, we showed that only 50% of the tilt in the axis of eye rotation could be predicted from vectorial summation of the gains (eye velocity/head velocity) obtained for rotations about the pure yaw and roll head axes. Thus, even when the orientation of Listing's plane and eye

  5. Accuracy assessment of novel two-axes rotating and single-axis translating calibration equipment

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Ye, Dong; Che, Rensheng

    2009-11-01

    There is a new method that the rocket nozzle 3D motion is measured by a motion tracking system based on the passive optical markers. However, an important issue is required to resolve-how to assess the accuracy of rocket nozzle motion test. Therefore, calibration equipment is designed and manufactured for generating the truth of nozzle model motion such as translation, angle, velocity, angular velocity, etc. It consists of a base, a lifting platform, a rotary table and a rocket nozzle model with precise geometry size. The nozzle model associated with the markers is installed on the rotary table, which can translate or rotate at the known velocity. The general accuracy of rocket nozzle motion test is evaluated by comparing the truth value with the static and dynamic test data. This paper puts emphasis on accuracy assessment of novel two-axes rotating and single-axis translating calibration equipment. By substituting measured value of the error source into error model, the pointing error reaches less than 0.005deg, rotation center position error reaches 0.08mm, and the rate stability is less than 10-3. The calibration equipment accuracy is much higher than the accuracy of nozzle motion test system, thus the former can be used to assess and calibrate the later.

  6. 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.

  7. 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

  8. Vestibular thresholds for yaw rotation about an earth-vertical axis as a function of frequency.

    PubMed

    Grabherr, Luzia; Nicoucar, Keyvan; Mast, Fred W; Merfeld, Daniel M

    2008-04-01

    Perceptual direction detection thresholds for yaw rotation about an earth-vertical axis were measured at seven frequencies (0.05, 0.1, 0.2, 0.5, 1, 2, and 5 Hz) in seven subjects in the dark. Motion stimuli consisted of single cycles of sinusoidal acceleration and were generated by a motion platform. An adaptive two-alternative categorical forced-choice procedure was used. The subjects had to indicate by button presses whether they perceived yaw rotation to the left or to the right. Thresholds were measured using a 3-down, 1-up staircase paradigm. Mean yaw rotation velocity thresholds were 2.8 deg s(-1) for 0.05 Hz, 2.5 deg s(-1) for 0.1 Hz, 1.7 deg s(-1) for 0.2 Hz, 0.7 deg s(-1) for 0.5 Hz, 0.6 deg s(-1) for 1 Hz, 0.4 deg s(-1) for 2 Hz, and 0.6 deg s(-1) for 5 Hz. The results show that motion thresholds increase at 0.2 Hz and below and plateau at 0.5 Hz and above. Increasing velocity thresholds at lower frequencies qualitatively mimic the high-pass characteristics of the semicircular canals, since the increase at 0.2 Hz and below would be consistent with decreased gain/sensitivity observed in the VOR at lower frequencies. In fact, the measured dynamics are consistent with a high pass filter having a threshold plateau of 0.71 deg s(-1) and a cut-off frequency of 0.23 Hz, which corresponds to a time constant of approximately 0.70 s. These findings provide no evidence for an influence of velocity storage on perceptual yaw rotation thresholds.

  9. 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.

  10. Three-dimensional velocity measurements around a rotating vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Coletti, Filippo; Ryan, Kevin; Dabiri, John; Eaton, John

    2013-11-01

    Vertical axis wind turbines (VAWT) can be more closely spaced than conventional horizontal axis wind turbines (HAWT), which points to a potentially greater power that can be extracted from a given wind farm footprint. In order to optimize the inter-turbine spacing and to investigate the potential for constructive aerodynamic interactions, the complex dynamics of VAWT wakes need to be analyzed. To date, only single-point or at best two-dimensional measurements of such wakes have been documented. We have measured the full three-component mean velocity field around and downstream the scaled-down model of a rotating VAWT by Magnetic Resonance Velocimetry (MRV). The high spatial resolution allows to quantitatively explore the structure of the wake, its interaction with the floor, and its development. The flow is shown to be highly three-dimensional and asymmetric for the whole investigated region (up to 7 diameters downstream of the turbine). These results can inform low-order models to predict the performance of turbine arrays.

  11. Transient recirculation in a slowly varying tube impulsively rotated about its axis with constant angular velocity

    NASA Astrophysics Data System (ADS)

    MacDonald, D. A.

    2000-12-01

    For time t¯<0, viscous fluid is in slow flow through a long straight axially symmetric tube whose radius, ā, varies slowly with axial distance, x¯. When t¯=0 the tube is impulsively rotated about its axis with angular velocity, Ω¯, at which angular speed it is thereafter maintained. During the transition from zero angular velocity, when t¯<0, to solid body rotation, when t¯→∞, the flow in the tube can briefly exhibit striking physical behavior, markedly different from the flow in the stationary tube. We present a linearization of the Navier-Stokes equations, valid when the Blasius parameter ɛ, which governs the magnitude of the inertial forces, tends to zero and the swirl parameter, λ, which is the ratio of a representative tube wall velocity, Ω¯ā0, to a representative axial velocity, tends to infinity, with the product ɛλ2≡Γ held fixed. An analytic solution suitable for computation and valid for suitably large t¯ is presented and streamlines are plotted for a typical diverging and a typical converging tube at time t¯=0.6ā02/ν when Γ=40. The relevance of the results to the phenomenon of vortex breakdown in tubes is discussed.

  12. The variability in the external rotation axis of the distal femur: an MRI-based anatomical study.

    PubMed

    Jones, Carl; Nawaz, Zuhair; Hassan, Abdel; White, Simon; Khaleel, Arshad

    2016-02-01

    Commonly used total knee arthroplasty (TKA) systems utilising measured resection techniques default to 5°-7° valgus for the distal cut relative to the anatomical axis and 3° external rotation of the femoral component relative to posterior condylar axis (PCA). Rotational errors of the femoral component are associated with pain, patella maltracking and a poorer outcome. We analysed MRI scans from patients undergoing TKA using patient-specific instrumentation to assess coronal and rotational alignment from landmarks identified on the scans. One hundred and eight scans in 59 males and 49 females were studied with age range 35-93 years (mean 67.9 years). We found 91 % of patients had a femoral valgus angle between 5° and 7° (mean angles 5.9°), while only 24 % had an external rotation angle between 2.5° and 3.5° relative to PCA. There was no statistical significance in rotation between males and females although outliers tended to be female. Mean Whiteside's angle was 92.9° (87.8-98). This study highlights the variations in external rotation between patients undergoing TKA using the PCA as a reference for rotation. This may be a contributing factor in implant malalignment and patient dissatisfaction.

  13. Beyond Euler angles: exploiting the angle-axis parametrization in a multipole expansion of the rotation operator.

    PubMed

    Siemens, Mark; Hancock, Jason; Siminovitch, David

    2007-02-01

    Euler angles (alpha,beta,gamma) are cumbersome from a computational point of view, and their link to experimental parameters is oblique. The angle-axis {Phi, n} parametrization, especially in the form of quaternions (or Euler-Rodrigues parameters), has served as the most promising alternative, and they have enjoyed considerable success in rf pulse design and optimization. We focus on the benefits of angle-axis parameters by considering a multipole operator expansion of the rotation operator D(Phi, n), and a Clebsch-Gordan expansion of the rotation matrices D(MM')(J)(Phi, n). Each of the coefficients in the Clebsch-Gordan expansion is proportional to the product of a spherical harmonic of the vector n specifying the axis of rotation, Y(lambdamu)(n), with a fixed function of the rotation angle Phi, a Gegenbauer polynomial C(2J-lambda)(lambda+1)(cosPhi/2). Several application examples demonstrate that this Clebsch-Gordan expansion gives easy and direct access to many of the parameters of experimental interest, including coherence order changes (isolated in the Clebsch-Gordan coefficients), and rotation angle (isolated in the Gegenbauer polynomials). PMID:17267183

  14. A kinematically distinct core and minor-axis rotation: the MUSE perspective on M87

    NASA Astrophysics Data System (ADS)

    Emsellem, Eric; Krajnović, Davor; Sarzi, Marc

    2014-11-01

    We present evidence for the presence of a low-amplitude kinematically distinct component in the giant early-type galaxy M87, via data sets obtained with the SAURON and MUSE integral-field spectroscopic units. The MUSE velocity field reveals a strong twist of ˜140° within the central 30 arcsec connecting outwards such a kinematically distinct core to a prolate-like rotation around the large-scale photometric major axis of the galaxy. The existence of these kinematic features within the apparently round central regions of M87 implies a non-axisymmetric and complex shape for this galaxy, which could be further constrained using the presented kinematics. The associated orbital structure should be interpreted together with other tracers of the gravitational potential probed at larger scales (e.g. globular clusters, ultra-compact dwarfs, planetary nebulae): it would offer an insight in the assembly history of one of the brightest galaxies in the Virgo cluster. These data also demonstrate the potential of the MUSE spectrograph to uncover low-amplitude spectral signatures.

  15. Single leg jumping neuromuscular control is improved following whole body, long-axis rotational training.

    PubMed

    Nyland, John; Burden, Robert; Krupp, Ryan; Caborn, David N M

    2011-04-01

    Improved lower extremity neuromuscular control during sports may decrease injury risk. This prospective study evaluated progressive resistance, whole body, long-axis rotational training on the Ground Force 360 device. Our hypothesis was that device training would improve lower extremity neuromuscular control based on previous reports of kinematic, ground reaction force (GRF) or electromyographic (EMG) evidence of safer or more efficient dynamic knee stability during jumping. Thirty-six healthy subjects were randomly assigned to either training (Group 1) or control (Group 2) groups. Using a pre-test, post-test study design data were collected from three SLVJ trials. Unpaired t-tests with adjustments for multiple comparisons were used to evaluate group mean change differences (P≤0.05/25≤0.002). During propulsion Group 1 standardized EMG amplitude mean change differences for gluteus maximus (-21.8% vs. +17.4%), gluteus medius (-28.6% vs. +15.0%), rectus femoris (-27.1% vs. +11.2%), vastus medialis (-20.2% vs. +9.1%), and medial hamstrings (-38.3% vs. +30.3%) differed from Group 2. During landing Group 1 standardized EMG amplitude mean change differences for gluteus maximus (-32.9% vs. +11.1%) and rectus femoris (-33.3% vs. +29.0%) also differed from Group 2. Group 1 peak propulsion vertical GRF (+0.24N/kg vs. -0.46N/kg) and landing GRF stabilization timing (-0.68 vs. +0.05s) mean change differences differed from Group 2. Group 1 mean hip (-16.3 vs. +7.8°/s) and knee (-21.4 vs. +18.5°/s) flexion velocity mean change differences also differed from Group 2. Improved lower extremity neuromuscular efficiency, increased peak propulsive vertical GRF, decreased mean hip and knee flexion velocities during landing, and earlier landing stabilization timing in the training group suggests improved lower extremity neuromuscular control.

  16. Volatile and nonvolatile magnetic easy-axis rotation in epitaxial ferromagnetic thin films on ferroelectric single crystal substrates

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Wang, Y.; Ge, W.; Li, J.; Viehland, D.

    2013-09-01

    We explored the relationship between phase transformation and magnetoelectric effect by depositing epitaxial CoFe2O4 films on ⟨110⟩ oriented Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) with three different PbTiO3 contents (PMN-28PT, PMN-29.5PT, and PMN-30PT). Electric-field controlled rhombohedral to orthorhombic phase transformation was confirmed by both piezoelectric and dielectric constant measurements. A giant in-plane (IP) uniaxial strain in CoFe2O4 film was induced due to dramatic lattice parameter change trigged by phase transition. Magnetic easy axis can be rotated from IP⟨110⟩ to IP⟨001⟩. More importantly, the phase transformation could be either reversible or irreversible, resulting in either volatile or nonvolatile magnetic easy axis rotations.

  17. Active correction of the tilt angle of the surface plane with respect to the rotation axis during azimuthal scan

    NASA Astrophysics Data System (ADS)

    Sereno, M.; Lupone, S.; Debiossac, M.; Kalashnyk, N.; Roncin, P.

    2016-09-01

    A procedure to measure the residual tilt angle τ between a flat surface and the azimuthal rotation axis of the sample holder is described. When the incidence angle θ and readout of the azimuthal angle ϕ are controlled by motors, an active compensation mechanism can be implemented to reduce the effect of the tilt angle during azimuthal motion. After this correction, the effective angle of incidence is kept fixed, and only a small residual oscillation of the scattering plane remains.

  18. The flexion-extension axis of the knee and its relationship to the rotational orientation of the tibial plateau.

    PubMed

    Lawrie, Charles M; Noble, Philip C; Ismaily, Sabir K; Stal, Drew; Incavo, Steve J

    2011-09-01

    We measured the optimal rotational alignment of the tibial component with respect to anatomic landmarks. Kinematic data were collected from functional maneuvers simulated in 20 cadaveric knees mounted in a joint simulator. The axis of knee motion was calculated for squatting and lunging activities over the interval of 30° to 90° of knee flexion. We then examined the accuracy and variability of 5 different anatomic axes in predicting the direction of knee motion. No one landmark guaranteed correct alignment of the tibial component and most predictors were highly variable (range, 6°-21°). The most accurate indicators were the medial third of the tibial tubercle (average error: squatting: 3.5° external rotation; lunging: 9.5°), and the medial-lateral axis of the resected tibial surface (6.7° and 1.1° internal rotation). The correct alignment of the tibial component can be best achieved by splitting the difference between these landmarks to eliminate placement of the component in excessive external and excessive internal rotation.

  19. Step-by-step rotation of a molecule-gear mounted on an atomic-scale axis

    NASA Astrophysics Data System (ADS)

    Manzano, C.; Soe, W.-H.; Wong, H. S.; Ample, F.; Gourdon, A.; Chandrasekhar, N.; Joachim, C.

    2009-07-01

    Gears are microfabricated down to diameters of a few micrometres. Natural macromolecular motors, of tens of nanometres in diameter, also show gear effects. At a smaller scale, the random rotation of a single-molecule rotor encaged in a molecular stator has been observed, demonstrating that a single molecule can be rotated with the tip of a scanning tunnelling microscope (STM). A self-assembled rack-and-pinion molecular machine where the STM tip apex is the rotation axis of the pinion was also tested. Here, we present the mechanics of an intentionally constructed molecule-gear on a Au(111) surface, mounting and centring one hexa-t-butyl-pyrimidopentaphenylbenzene molecule on one atom axis. The combination of molecular design, molecular manipulation and surface atomic structure selection leads to the construction of a fundamental component of a planar single-molecule mechanical machine. The rotation of our molecule-gear is step-by-step and totally under control, demonstrating nine stable stations in both directions.

  20. Dual-core photonic crystal fiber Doppler velocimeter for small horizontal axis wind turbine blade rotational speed measurement

    NASA Astrophysics Data System (ADS)

    Huang, Xue-Feng; Li, Sheng-Ji; Wang, Wei-Chih

    2014-03-01

    The blades are crucial components of a wind turbine, and its steady and reliable operation is directly related to the power output. Thus, condition monitoring and fault diagnosis of the wind turbine blades is highly beneficial to the operational cost. This paper presents a study of small horizontal axis wind turbine blade rotational speed measurement by laser Doppler velocimeter based on dual-core photonic crystal fiber (DC-PCF). The theory on the DC-PCF Doppler velocimeter is presented, and the measurement system is designed and tested. Experimental results show that the DC-PCF Doppler velocimeter has been proved to work successfully. The uncertainty of the rotational speed is about 0 ~ 4 rpm. The accuracy can meet the requirements for monitoring the rotational operation of the wind turbine.

  1. Method to rotate an endovascular device around the axis of a vessel using an external magnetic field.

    PubMed

    Florin, E; Rangwala, H S; Rudin, S

    2007-01-01

    A magnetic guidance methodology to rotate a device around the catheter axis is proposed. The specific medical application is to intracranial aneurysms. An endovascular device, the asymmetric stent, has a low porosity region that is rotated to cover the aneurysm neck so as to reduce the blood flow into and hence obliterate the aneurysm. The magnetic guidance system consists of a magnetic device attached to the asymmetric stent and an external homogeneous magnetic field of 0.1 T. This magnetic field puts a torque on the magnetic moment of the magnetic device, thereby rotating the stent for proper orientation. For the magnetic device with the required magnetic moment of 0.001 A m2, a cylindrical neodymium permanent magnet is proposed due to its favorable material characteristics while a coil electromagnet with iron core appears impractical due to demagnetizing effects.

  2. 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.

  3. Radial forces analysis and rotational speed test of radial permanent magnetic bearing for horizontal axis wind turbine applications

    NASA Astrophysics Data System (ADS)

    Kriswanto, Jamari

    2016-04-01

    Permanent magnet bearings (PMB) are contact free bearings which utilize the forces generated by the magnets. PMB in this work is a type of radial PMB, which functions as the radial bearings of the Horizontal Axis Wind Turbine (HAWT) rotor shaft. Radial PMB should have a greater radial force than the radial force HAWT rotor shaft (bearing load). This paper presents a modeling and experiments to calculate the radial force of the radial PMB. This paper also presents rotational speed test of the radial PMB compared to conventional bearings for HAWT applications. Modeling using COMSOL Multiphysics 4.3b with the magnetic fields physics models. Experiments were conducted by measuring the displacement of the rotor to the stator for a given load variation. Results of the two methods showed that the large displacement then the radial force would be greater. Radial forces of radial PMB is greater than radial forces of HAWT rotor shaft. The rotational speed test results of HAWT that used radial PMB produced higher rotary than conventional bearings with an average increase of 87.4%. Increasing rotational speed occured because radial PMB had no friction. HAWT that used radial PMB rotated at very low wind speeds are 1.4 m/s with a torque of 0.043 Nm, while the HAWT which uses conventional bearing started rotating at a wind speed of 4.4 m/s and required higher torque of 0.104 N.

  4. 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.

  5. 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

  6. 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.

  7. Antihysteresis of perceived longitudinal body axis during continuous quasi-static whole-body rotation in the earth-vertical roll plane.

    PubMed

    Tatalias, M; Bockisch, C J; Bertolini, G; Straumann, D; Palla, A

    2011-03-01

    Estimation of subjective whole-body tilt in stationary roll positions after rapid rotations shows hysteresis. We asked whether this phenomenon is also present during continuous quasi-static whole-body rotation and whether gravitational cues are a major contributing factor. Using a motorized turntable, 8 healthy subjects were rotated continuously about the earth-horizontal naso-occipital axis (earth-vertical roll plane) and the earth-vertical naso-occipital axis (earth-horizontal roll plane). In both planes, three full constant velocity rotations (2°/s) were completed in clockwise and counterclockwise directions (acceleration = 0.05°/s(2), velocity plateau reached after 40 s). Subjects adjusted a visual line along the perceived longitudinal body axis (pLBA) every 2 s. pLBA deviation from the longitudinal body axis was plotted as a function of whole-body roll position, and a sine function was fitted. At identical whole-body earth-vertical roll plane positions, pLBA differed depending on whether the position was reached by a rotation from upright or by passing through upside down. After the first 360° rotation, pLBA at upright whole-body position deviated significantly in the direction of rotation relative to pLBA prior to rotation initiation. This deviation remained unchanged after subsequent full rotations. In contrast, earth-horizontal roll plane rotations resulted in similar pLBA before and after each rotation cycle. We conclude that the deviation of pLBA in the direction of rotation during quasi-static earth-vertical roll plane rotations reflects static antihysteresis and might be a consequence of the known static hysteresis of ocular counterroll: a visual line that is perceived that earth-vertical is expected to be antihysteretic, if ocular torsion is hysteretic.

  8. 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.

  9. 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.

  10. Ball spin in the tennis serve: spin rate and axis of rotation.

    PubMed

    Sakurai, Shinji; Reid, Machar; Elliott, Bruce

    2013-03-01

    The purpose of this study was to describe three-dimensional ball kinematics including spin axis and spin rate for the flat, slice, and kick serves executed by elite male tennis players. Trajectories of three retro-reflective markers attached to the surface of the ball were measured using a Vicon MX motion analysis system. The local coordinate system of the ball enabled the ball's angular velocity vector to be determined. Mean (+/- SD) spin rates recorded were 127.4 (+/- 56.3), 232.1 (+/- 34.8), and 336.5 (+/- 51.5) rad/s for the flat, slice, and kick serves, respectively. The resultant horizontal velocities of the ball were 52.0 (+/- 2.9), 46.4 (+/- 3.4), and 40.8 (+/- 2.8) m/s, respectively, and a clear tradeoff existed between the development of ball spin rate and horizontal ball velocity. [corrected]. The spin axis and ball velocity vector were close to perpendicular regardless of serve type. Mean angles between the spin axis and the horizontal plane (elevation angles) were 65.68 (+/- 10.28), 68.48 (+/- 6.98), and 54.58 (+/- 8.48) for the flat, slice, and kick serves, respectively. [corrected].

  11. 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.

  12. Asymmetric rotational axis reconstruction of grating-based x-ray phase contrast tomography of the human cerebellum

    NASA Astrophysics Data System (ADS)

    Schulz, Georg; Weitkamp, Timm; Zanette, Irene; Pfeiffer, Franz; Müller-Gerbl, Magdalena; David, Christian; Müller, Bert

    2012-10-01

    The brain has an outstanding functional importance in the human organism. Therefore, there is a strong need for three-dimensional brain imaging modalities. Magnetic resonance imaging provides deep insights but its spatial resolution is insufficient to study the structure on the cellular level. X-ray absorption microtomography yields the necessary spatial resolution, but shows only marginal contrast between the different types of brain tissue. Alternatively, differential X-ray phase contrast obtained with grating interferometry, which is known for much better differentiations between soft tissues can be used for the visualization of the human brain. As important structures of the human brain such as the human thalamus have dimensions of several centimeters, a large field of view is required. In the present communication, we report an evaluation of grating-based X-ray phase contrast microtomography in the off-axis modus which allows to expand the field of view up to a factor of two but may reduce the image quality. We demonstrate that tomograms with comparable contrast-to-noise values, about 10%, and 50% inferior spatial resolution can be generated with off-axis measurements. As one can reduce the effective pixel size up to a factor of two, the choice of an asymmetrical rotation axis can give rise to an improvement of the spatial resolution by 20%.

  13. Baselines for three-dimensional perception of combined linear and angular self-motion with changing rotational axis.

    PubMed

    Holly, J E

    2000-01-01

    The laws of physics explain many human misperceptions of whole-body passive self-motion. One classic misperception occurs in a rotating chair in the dark: If the chair is decelerated to a stop after a period of counterclockwise rotation, then a subject will typically perceive clockwise rotation. The laws of physics show that, indeed, a clockwise rotation would be perceived even by a perfect processor of angular acceleration information, assuming that the processor is initialized (prior to the deceleration) with a typical subject's initial perception - of no rotation in this case. The motion perceived by a perfect acceleration processor serves as a baseline by which to judge human self-motion perception; this baseline makes a rough prediction and also forms a basis for comparison, with uniquely physiological properties of perception showing up as deviations from the baseline. These same principles, using the motion perceived by a perfect acceleration processor as a baseline, are used in the present paper to investigate complex motions that involve simultaneous linear and angular accelerations with a changing axis of rotation. Baselines - motions that would be perceived by a perfect acceleration processor, given the same initial perception (prior to the motion of interest) as that of a typical subject - are computed for the acceleration and deceleration stages of centrifuge runs in which the human carriage tilts along with the vector resultant of the centripetal and gravity vectors. The computations generate a three-dimensional picture of the motion perceived by a perfect acceleration processor, by simultaneously using all six interacting degrees of freedom (three angular and three linear) and taking into account the non-commutativity of rotations in three dimensions. The resulting three-dimensional baselines predict stronger perceptual effects during deceleration than during acceleration, despite the equal magnitudes (with opposite direction) of forces on the

  14. New paleomagnetic data from Upper Oligocene-Lower Miocene rocks of the Northern Argentine Puna-Southern Bolivian Altiplano: Constraining the age of vertical axis rotations

    NASA Astrophysics Data System (ADS)

    Prezzi, Claudia B.; Caffe, Pablo J.; Iglesia Llanos, María P.; Orgeira, María J.

    2014-08-01

    Along the Central Andes a pattern of vertical axis rotations has been paleomagnetically identified. Such rotations are counterclockwise north of Arica Deflection (∼19° S) and clockwise to the south. Different hypothesis and models have been proposed to explain the Central Andean Rotation Pattern (CARP). However, the origin of the CARP is a subject of ongoing debate. Recently, different authors have proposed the possible existence of a close correlation between the time-space distribution of deformation and the amount of registered vertical axis rotations in the Southern Central Andes. In order to further investigate such relationship, new paleomagnetic studies were carried out in Upper Oligocene-Lower Miocene rocks of the Northern Argentine Puna and the Southern Bolivian Altiplano. Our results indicate that while one of the sampled localities did not undergo significant vertical axis rotations, the other two recorded clockwise vertical axis rotations larger than 30°. These results suggest the occurrence of small-block rotations in the Southern Bolivian Altiplano-Northern Argentine Puna prior to 15 Ma, which would correspond to the local accommodation of the regional deformation field.

  15. 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

  16. Interindividual reproducibility in perioperative rotational alignment of femoral components in knee prosthetic surgery using the transepicondylar axis.

    PubMed

    Jerosch, J; Peuker, E; Philipps, B; Filler, T

    2002-05-01

    Femoral component malalignment is one of the main causes of persisting anterior knee pain after knee replacement. This study examined interindividual reproducibility in perioperative definition of the transepicondylar axis (TEA) as a reference for measuring the rotational alignment of the femoral component. Eight surgeons experienced in knee prosthetic surgery marked on Thiel-embalmed cadaver specimens the reference points that they would normally use to define the TEA during knee replacement. These were digitized by a video system, and all the spots defined by the surgeon were translated into a reference picture, allowing a digital analysis of the distances between all the spots marked. The maximal distance between the spots that the participants had marked as relevant for the TEA was 13.8 mm at the lateral and 22.3 mm at the medial epicondyle. Projecting all spots marked into one picture resulted in an area of 116 mm2 on the lateral and 102 mm2 on the medial epicondyle. The median range of the fault between two different participants was 6.4 mm on the lateral side (range 13.2 mm) and 9.7 mm on the medial (range 21.6 mm). Because the rotational alignment of the femoral component is extremely relevant for successful implantation of total knee prosthesis, the interindividual discrepancy in defining the TEA as reference is rather high. As this reference line is commonly used, the perioperative variance and the resulting rotational discrepancy of the femoral component must be considered.

  17. How to explain a constant subjective vertical at constant high speed rotation about an earth-horizontal axis.

    PubMed

    Mittelstaedt, H; Glasauer, S; Gralla, G; Mittelstaedt, M L

    1989-01-01

    When rotated in darkness about an earth-horizontal axis at speeds above 0.2-0.5 Hz, subjects, instead of feeling rotated, experience a constant (though extrapersonally diverse) position in space and a constant visual vertical (SV). Computer simulation shows that this phenomenon cannot be explained by the extant models of Mayne (1) and Ormsby (2) about the interaction of otoliths and semicircular canals. It follows, however, from a static theory of the SV (3) if, as in the presently proposed dynamic model, the otolith afference is processed by a low-pass filter. At high speed rotation this filter can only be passed by the force-independent, temporally invariant components of the otolith information. Such force-independent components are bound to result from biassed resting discharges, and have previously been shown to affect the SV and the self-adopted horizontal position. The interaction of otoliths and canals proposed by the model does provide a veridical vertical in a working range of angular frequencies and hence a basis for inertial navigation.

  18. Numerical Investigation of Capability of Self-Starting and Self-Rotating of a Vertical Axis Wind Turbine

    NASA Astrophysics Data System (ADS)

    Tsai, Hsieh-Chen; Colonius, Tim

    2015-11-01

    The immersed boundary method is used to simulate the incompressible flow around two-dimensional airfoils at low Reynolds numbers in order to investigate the self-starting and self-rotating capability of a vertical axis wind turbine (VAWT) with NACA 0018 blades. By examining the torque generated by a three-bladed VAWT fixed at various orientations, a stable equilibrium and the optimal starting orientation that produces the largest torque have been observed. When Reynolds number is below a critical value, the VAWT oscillates around a stable equilibrium. However, the VAWT goes into continuous rotation from the optimal orientation when Reynolds number is above this critical value. It is also shown that VAWT with more blades is easier to self-start due to a wilder range of positive starting torques. Moreover, with a proper choice of load model, a VAWT is able to self-rotate and generate a designed averaged power. This project is supported by Caltech FLOWE center/Gordon and Betty Moore Foundation.

  19. 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

  20. Visual rotation axis and body position relative to the gravitational direction: Effects on circular vection.

    PubMed

    Tanahashi, Shigehito; Ujike, Hiroyasu; Ukai, Kazuhiko

    2012-01-01

    The visual-vestibular conflict theory asserts that visual-vestibular conflicts reduce vection and that vection strength is reduced with an increasing discrepancy between actual and expected vestibular activity. Most studies support this theory, although researchers have not always accepted them. To ascertain the conditions under which the theory of the visual-vestibular conflict can be applied, we measured circular vection strength accompanied by manipulation of the visual-otolith conflict by setting the axes of visual global motion (pitch, roll, and yaw) as either earth-horizontal or earth-vertical, using three different body positions (supine, left-lateral recumbent, and sitting upright). When the smaller stimulus was used, roll vection strength was greater with the visual-otolith conflict than without it, which contradicts the visual-vestibular conflict theory. We confirmed this result, as observers were able to distinguish circular vection from an illusory body tilt. Moreover, with observers in an upright position, the strength of yaw vection, which does not involve the visual-otolith conflict, increased and was almost equal to that of roll vection, which involves the visual-otolith conflict. This suggests that if the visual stimulus covers the entire visual field, the strength of circular vection around the earth-vertical axis exceeds that around the earth-horizontal axis, which is a finding consistent with the visual-vestibular conflict theory.

  1. 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.

  2. 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

  3. 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.

  4. 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. PMID:25303496

  5. 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.

  6. Investigation of the rotational flow effects in a pitching airfoil genetically optimized for vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Ragni, Daniele; Vitale, Laura; Ianiro, Andrea; Geurts, Ben; Ferreira, Carlos

    2012-11-01

    In the present study, an airfoil optimized for vertical axis wind turbines applications has been developed with a genetic algorithm, selecting the geometry with maximum (dcl/d α) /cd among airfoils generated with 16 shape functions. The airfoil, operating in the curved trajectory of a vertical axis wind turbine, is usually optimized adopting conformal mappings in the straight path. Recent experimental results have shown disagreement with this approach, due to the forces determined in the curved flow path. To investigate the effects of flow rotation, an aluminum model (c=0.25m) has been manufactured from the optimized shape and further tested in the LST tunnel of the TUDelft at Reynolds number 106. Planar PIV experiments in combination with the PIV based load determination technique have been performed to simultaneously obtain velocity fields and loads. Results including velocity, pressure distributions, lift and drag are initially discussed in a steady airfoil configuration and compared with numerical results. Successively, the model has been unsteadily pitched using a magnetic linear actuator (up to 3 Hz frequency), with a free stream V∞ = 40 m/s corresponding to Re = 0.7 ×106. Phase locked PIV vector fields have been acquired and compared to the steadily obtained results.

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

    NASA Astrophysics Data System (ADS)

    Tian, W.

    2016-07-01

    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, 2004). Since then many technical improvements led to a 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.

  8. Modeling direction discrimination thresholds for yaw rotations around an earth-vertical axis for arbitrary motion profiles.

    PubMed

    Soyka, Florian; Giordano, Paolo Robuffo; Barnett-Cowan, Michael; Bülthoff, Heinrich H

    2012-07-01

    Understanding the dynamics of vestibular perception is important, for example, for improving the realism of motion simulation and virtual reality environments or for diagnosing patients suffering from vestibular problems. Previous research has found a dependence of direction discrimination thresholds for rotational motions on the period length (inverse frequency) of a transient (single cycle) sinusoidal acceleration stimulus. However, self-motion is seldom purely sinusoidal, and up to now, no models have been proposed that take into account non-sinusoidal stimuli for rotational motions. In this work, the influence of both the period length and the specific time course of an inertial stimulus is investigated. Thresholds for three acceleration profile shapes (triangular, sinusoidal, and trapezoidal) were measured for three period lengths (0.3, 1.4, and 6.7 s) in ten participants. A two-alternative forced-choice discrimination task was used where participants had to judge if a yaw rotation around an earth-vertical axis was leftward or rightward. The peak velocity of the stimulus was varied, and the threshold was defined as the stimulus yielding 75 % correct answers. In accordance with previous research, thresholds decreased with shortening period length (from ~2 deg/s for 6.7 s to ~0.8 deg/s for 0.3 s). The peak velocity was the determining factor for discrimination: Different profiles with the same period length have similar velocity thresholds. These measurements were used to fit a novel model based on a description of the firing rate of semi-circular canal neurons. In accordance with previous research, the estimates of the model parameters suggest that velocity storage does not influence perceptual thresholds.

  9. Canine hip dysplasia radiographic screening. Prevalence of rotation of the pelvis along its length axis in 7,012 conventional hip extended radiographs.

    PubMed

    Genevois, J-P; Cachon, T; Fau, D; Carozzo, C; Viguier, E; Collard, F; Remy, D

    2007-01-01

    The prevalence of rotation of the pelvis along its length axis was noted, as was the number of rotations towards the right or left hand side of the dog, on 7,012 conventional hip extended radiographs, which were sent for official screening. 29.8% of the radiographs showed a rotation the pelvis. The rotation was statistically more frequent towards the left hand side of the dog. The number of rejected radiographs for too important pelvis rotation was only 5.2%. The consequences of the pelvis rotation on the Norberg-Olsson angle, on the dorsal femoral head coverage, and in the aspect of cranial acetabular edge have to be taken into account when scoring the dog for hip dysplasia. PMID:18038007

  10. Canine hip dysplasia radiographic screening. Prevalence of rotation of the pelvis along its length axis in 7,012 conventional hip extended radiographs.

    PubMed

    Genevois, J-P; Cachon, T; Fau, D; Carozzo, C; Viguier, E; Collard, F; Remy, D

    2007-01-01

    The prevalence of rotation of the pelvis along its length axis was noted, as was the number of rotations towards the right or left hand side of the dog, on 7,012 conventional hip extended radiographs, which were sent for official screening. 29.8% of the radiographs showed a rotation the pelvis. The rotation was statistically more frequent towards the left hand side of the dog. The number of rejected radiographs for too important pelvis rotation was only 5.2%. The consequences of the pelvis rotation on the Norberg-Olsson angle, on the dorsal femoral head coverage, and in the aspect of cranial acetabular edge have to be taken into account when scoring the dog for hip dysplasia.

  11. 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.

  12. Lack of a threefold rotation axis in α-Fe₂O₃ and α-Cr₂O₃ crystals.

    PubMed

    Stękiel, Michał; Przeniosło, Radosław; Sosnowska, Izabela; Fitch, Andrew; Jasiński, Jacek B; Lussier, Joey A; Bieringer, Mario

    2015-04-01

    The crystal structure of α-Fe2O3 and α-Cr2O3 is usually described with the corundum-type trigonal crystal structure based on the space group R3¯c. There are, however, some observations of the magnetic ordering of both α-Fe2O3 and α-Cr2O3 that are incompatible with the trigonal symmetry. We show experimental evidence based on X-ray powder diffraction and supported by transmission electron microscopy that the symmetry of the crystal structure of both α-Fe2O3 and α-Cr2O3 is monoclinic and it is described with the space group C2/c (derived from R3¯c by removing the threefold rotation axis). The magnetic orderings of α-Fe2O3 and α-Cr2O3 are compatible with the magnetic space groups C2/c and C2/c', respectively. These findings are in agreement with the idea from Curie [(1894), J. Phys. 3, 393-415] that the dissymmetry of the magnetic ordering should be associated with a dissymmetry of the crystal structure. PMID:25827373

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

    PubMed

    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.

  14. 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

  15. Dual-axis rotational coronary angiography can reduce peak skin dose and scattered dose: a phantom study.

    PubMed

    Liu, Huiliang; Jin, Zhigeng; Deng, Yunpeng; Jing, Limin

    2014-07-08

    The purpose of this study was to evaluate peak skin dose received by the patient and scattered dose to the operator during dual-axis rotational coronary angiography (DARCA), and to compare with those of standard coronary angiography (SA). An anthropomorphic phantom was used to simulate a patient undergoing diagnostic coronary angiography. Cine imaging was applied on the phantom for 2 s, 3 s, and 5 s in SA projections to mimic clinical situations with normal vessels, and uncomplicated and complicated coronary lesions. DARCA was performed in two curved trajectories around the phantom. During both SA and DARCA, peak skin dose was measured with thermoluminescent dosimeter arrays and scattered dose with a dosimeter at predefined height (approximately at the level of left eye) at the operator's location. Compared to SA, DARCA was found lower in both peak skin dose (range: 44%-82%, p < 0.001) and scattered dose (range: 40%-70%, p < 0.001). The maximal reductions were observed in the set mimicking complicated lesion examinations (82% reduction for peak skin dose, p < 0.001; 70% reduction for scattered dose, p < 0.001). DARCA reduces both peak skin dose and scattered dose in comparison to SA. The benefi t of radiation dose reduction could be especially signifi cant in complicated lesion examinations due to large reduction in X-ray exposure time. The use of DARCA could, therefore, be recommended in clinical practice to minimize radiation dose.

  16. Analysis of response delay of the attitude in a single-axis rotation INS/GPS system

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    Deflections of the vertical (DOV) are normally ignored in the gravity compensation procedure, which become one of the primary error sources in inertial navigation. In a single-axis rotation INS/GPS system, bias of the gyro and the accelerometer can be ignored, the attitude error is mainly affected by DOV. In this paper, the ideal system assumption is abandoned and the influence of DOV on the attitude is comprehensively discussed, which can be divided into two parts i.e. the direct influence and the indirect influence. The attitude error tracks the DOV along the trajectory belongs to the former. A relatively fixed delay between the attitude error and the DOV belongs to the latter. The delay is essentially induced by the weak observability of the system to the violent DOV. Factors which affect the delay are carefully analyzed. The simulation results show that the delay is mainly affected by accuracies of the inertial sensors and the GPS. It decreases with the GPS accuracy increasing, but increases with the inertial sensor accuracy increasing. The process noise covariance matrix Q plays an important role. With analysis of the characteristics of the delay, influence of the DOV on attitude is studied further, which is necessary for the attitude correction in future.

  17. Dual-Axis Rotational Coronary Angiography: A New Technique for Detecting Graft Coronary Vasculopathy in Pediatric Heart Transplant Recipients

    PubMed Central

    Gudausky, Todd M.; Pelech, Andrew N.; Stendahl, Gail; Tillman, Kathryn; Mattice, Judy; Berger, Stuart; Zangwill, Steven

    2016-01-01

    Annual surveillance coronary angiograpyhy to screen for graft coronary vasculopathy is routine practice after orthotopic heart transplantation. Traditionally, this is performed with direct coronary angiography using static single-plane or biplane angiography. Recently, technological advances have made it possible to perform dual-axis rotational coronary angiography (RA). This technique differs from standard static single-plane or biplane angiography in that a single detector is preprogrammed to swing through a complex 80° arc during a single injection. It has the advantage of providing a perspective of the vessels from a full arc of images rather than from one or two static images per contrast injection. The current study evaluated two coronary angiography techniques used consecutively at a single center to evaluate pediatric heart transplant recipients for graft coronary vasculopathy. A total of 23 patients underwent routine coronary angiography using both biplane static coronary angiography (BiP) and RA techniques at the Children's Hospital of Wisconsin from February 2009 to September 2010. Demographic and procedure data were collected from each procedure and analyzed for significance utilizing a Wilcoxon rank sum test. No significant demographic or procedural differences between the BiP and the RA procedures were noted. Specific measures of radiation dose including fluoroscopy time and dose area product were similar among the imaging techniques. The findings show that RA can be performed safely and reproducibly in pediatric heart transplant recipients. Compared with standard BiP, RA does not increase radiation exposure or contrast use and in our experience has provided superior angiographic imaging for the evaluation of graft coronary vasculopathy. PMID:22956061

  18. Vertical axis windmill

    SciTech Connect

    Zheug, Y.K.

    1984-03-06

    A vertical axis windmill has a blade pivotally connected to a rotatable support structure on an axis passing through its center of gravity which is arranged to lie forward of its aerodynamic center whereby the blade automatically swings outwardly and inwardly when moving on the windward and leeward sides respectively of the axis of rotation of said support means.

  19. [Correlation of fine structures of distributions of amplitudes of a photomultiplier dark current fluctuations with the Earth rotations about its axis].

    PubMed

    Fedorov, M V; Belousov, L V; Voeĭkov, V L; Zenchenko, K I; Zenchenko, T A; Konradov, A A; Shnol', S E

    2001-01-01

    The fine structures of distributions of photomultiplier dark current fluctuations measured in two laboratories 2000 km distant from other: in the international Institute of Biophysics (Neuss, Germany) and in the Moscow State University (Moscow, Russia) were compared. It is shown that similar forms of appropriate histograms are apparently more often realized at both locations at the same local time. This confirms the previous conclusion that the fine structure of distributions correlates with rotation of the Earth about its axis.

  20. Derivation of the coupled equations of motion for a circular ring rotating about an axis in the plane of the ring

    SciTech Connect

    Benedetti, G.A.

    1996-03-01

    The coupled equations of motion for a circular ring or circular ring segment are developed for the case where the ring is rotating about an axis in its plane and subjected to an angular velocity as well as an angular acceleration. Coupling results from bending in and out of the plane of the ring as well as from extension and torsion of the ring. These equations are then applied to special cases to determine the coupled equations of motion for a ring, beam and cable rotating at a constant angular speed. Coupled equations of motion for a non-rotating circular ring or circular ring segment are developed for the cases of extensional motion and inextensional motion. These equations are subsequently linearized and uncoupled for extensional and inextensional motion in the plane of the ring as well as for uncoupled motion out of the plane of the ring. The critical angular speed for lateral dynamic instability is determined for a rotating circular shaft which supports several rotating circular ring segments.

  1. 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.

  2. Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. IV. Effects of Rotational Axis Orientation

    NASA Astrophysics Data System (ADS)

    Boss, Alan P.; Keiser, Sandra A.

    2015-08-01

    Both astronomical observations of the interaction of Type II supernova remnants (SNRs) with dense interstellar clouds as well as cosmochemical studies of the abundances of daughter products of short-lived radioisotopes (SLRIs) formed by supernova nucleosynthesis support the hypothesis that the Solar System's SLRIs may have been derived from a supernova. This paper continues a series devoted to examining whether or not such a shock wave could have triggered the dynamical collapse of a dense, presolar cloud core and simultaneously injected sufficient abundances of SLRIs to explain the cosmochemical evidence. Here, we examine the effects of shock waves striking clouds whose spin axes are oriented perpendicular, rather than parallel, to the direction of propagation of the shock front. The models start with 2.2 {M}⊙ cloud cores and shock speeds of 20 or 40 km s-1. Central protostars and protoplanetary disks form in all models, although with their disk spin axes aligned somewhat randomly. The disks derive most of their angular momentum not from the initial cloud rotation, but from the Rayleigh-Taylor fingers that also inject shock wave SLRIs. Injection efficiencies, fi, the fraction of the incident shock wave material injected into the collapsing cloud core, are ˜0.04-0.1 in these models, similar to when the rotation axis is parallel to the shock propagation direction. Evidently, altering the rotation axis orientation has only a minor effect on the outcome, strengthening the case for this scenario as an explanation for the Solar System's SLRIs.

  3. 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.

  4. 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.

  5. 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.

  6. Vertical axis wind turbine

    SciTech Connect

    Kato, Y.; Seki, K.; Shimizu, Y.

    1981-01-27

    Wind turbines are largely divided into vertical axis wind turbines and propeller (Horizontal axis) wind turbines. The present invention discloses a vertical axis high speed wind turbine provided with a starting and braking control system. This vertical axis wind turbine is formed by having blades of a proper airfoil fitted to respective supporting arms provided radially from a vertical rotary axis by keeping the blade span-wise direction in parallel with the axis and being provided with a low speed control windmill in which the radial position of each operating piece varies with a centrifugal force produced by the rotation of the vertical rotary axis.

  7. Somatosensory motion after-effect following earth-horizontal rotation about the Z-axis: a new illusion.

    PubMed

    Lackner, J R; Graybiel, A

    1977-06-01

    During rotation about the Z-axos while recumbent one is exposed to a changing pattern of pressure cues over the body surface. If the body is only loosely padded in the experimental apparatus, then apparent motion of part of the body surface may be experienced sometime after rotation has been terminated. This somatosensory motion aftereffect of opposite sign is temporarily abolished if one looks at the affected body area, but is again re-experienced when the gaze is shifted elswhere. The similarity of this motion aftereffect to those contingent on vestibular and visual stimulation is discussed.

  8. The Vallenar Discontinuity and the Maipo Orocline: Regional significance of clockwise vertical-axis rotations in the central Chilean Andes.

    NASA Astrophysics Data System (ADS)

    Arriagada, C.; Roperch, P.; Mpodozis, C.; Charrier, R.; Yanez, G.; Farias, M.

    2009-05-01

    One of the most prominent tectonic features of the Andes is the Central Andean Rotation Pattern (CARP), which is closely related to the Bolivian Orocline and characterized by paleomagnetically determined clockwise rotations in northern Chile and counterclockwise rotations in southern Peru (Arriagada et al., 2008). Along the Chilean margin, between 29°S and 38°S, three prominent curvatures are observed. The Vallenar Discontinuity near ˜29°S corresponds to the southern limit of the Bolivian Orocline. North of 29°S the major structural elements (Paleozoic basement highs and thrusts) are NNE oriented while from 29°S down to 32°S the structures are mainly NS. The central Chilean margin presents also significant bends near Santiago (˜33°S, Maipo Orocline) and in the Arauco region (˜38°S). Near Santiago, the Maipo bend coincides with the subduction of the Juan Fernandez Ridge (JFR). During the last five years we have undertaken new paleomagnetic and structural studies along the forearc of northern and central Chile in order to understand the origin of the bends in the Chilean margin and the consequence of its indentation by the JFR. Clockwise rotations are, consistently large (30°S- 45°) north of the Vallenar discontinuity, but south of the Vallenar discontinuity, the segment between 29°S to 32°S was not subjected to significant clockwise rotation. South of ˜33°S, significant clockwise deflections up to 39° of the declinations are again observed. Rotations occur both in Mesozoic rocks of the Coastal Cordillera and Tertiary rocks of the Main Cordillera. Whereas most of the CARP rotations, involving bending of the Bolivian Orocline and clockwise rotations north of the Vallenar Discontinuity, occurred essentially during the Paleogene, the paleomagnetic rotations obtained in Tertiary formations of central Chile constrain the maximum possible age for the occurrence of rotations of the Maipo Orocline to the Miocene. Neogene shortening in the foreland belt

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Stability of the rotation axis in high-resolution mantle circulation models: Weak polar wander despite strong core heating

    NASA Astrophysics Data System (ADS)

    Schaber, K.; Bunge, H.-P.; Schuberth, B. S. A.; Malservisi, R.; Horbach, A.

    2009-11-01

    Growing evidence points to a substantial heat flow across the core-mantle boundary (CMB), but the rotational stability of strongly bottom heated mantle flow with prominent upwelling plumes is poorly known. Here we calculate polar motion for the past 100 Myr induced in a new class of isochemical high-resolution mantle circulation models (MCMs) with Earth-like convective vigor and up to 12 TW core heat flux. Our MCMs include internal heating and a simple three-layer viscosity profile associated with the lithosphere (1023 Pa s) and the upper (1021 Pa s) and the lower mantle (1023 Pa s), separated at 100 and 650 km depth, respectively. A published mantle mineralogy model in the pyrolite composition, consistent with our assumption of whole mantle flow, allows us to relate thermal to density variations in a thermodynamically self-consistent way. All models yield modest polar motion on the order of 0.5° Myr-1 or less, in accordance with paleomagnetic data and agreeing with a number of studies that demonstrate the stabilizing effect of the rotational bulge. Although a substantially reduced lower mantle viscosity would increase this rate, the good agreement between MCM and seismic mantle heterogeneity lends independent support for our viscosity profile, as otherwise, slabs in the MCM would rapidly sink to depth levels where they are tomographically not observed. In general, there is good agreement between the long-wavelength geoids predicted from our MCMs and recent satellite derived models of Earth's geoid (correlation coefficient of around 0.4), but noticeable differences at intermediate wavelengths, for example, in the western Pacific and in Africa, suggest the use of gravity data to distinguish between competing plate reconstruction models.

  14. Relaxation time of molecular rotation about its long axis in the smectic-A phase of ferroelectricand antiferroelectric liquid crystals as observed by picosecond optical Kerr effect

    NASA Astrophysics Data System (ADS)

    Miyachi, Kouichi; Takanishi, Yoichi; Ishikawa, Ken; Takezoe, Hideo; Fukuda, Atsuo

    1997-02-01

    We have studied the molecular rotational motion about its long axis in ferroelectric chiral smectic-C (Sm-C) and antiferroelectric chiral smectic-Ca (Sm-C*>A) liquid crystals and observed a few tens of picosecond relaxation time. Previously reported results using degenerate four-wave mixing with 25-ps pump pulses [Lalanne et al., Phys. Rev. A 44, 6632 (1991)] claimed to show a critical slowing down in the temperature region more than 0.1 °C above the Sm-A-Sm-C phase transition. Our measurements of the optical Kerr effect with 130-fs pump pulses do not show any critical slowing down in the corresponding temperature region above the phase transition from Sm-A to Sm-C or Sm-C*>A. The result may indicate that the laser-induced molecular reorientation with τ~10-11 s scarcely couples with the tilt angle and the polarization. A possibility has been discussed that a slower rotational motion with τ>~10-10 s plays a primary role for the emergence of ferroelectricity and/or antiferroelectricity.

  15. A conformal mapping technique to correlate the rotating flow around a wing section of vertical axis wind turbine and an equivalent linear flow around a static wing

    NASA Astrophysics Data System (ADS)

    Akimoto, Hiromichi; Hara, Yutaka; Kawamura, Takafumi; Nakamura, Takuju; Lee, Yeon-Seung

    2013-12-01

    In a vertical axis wind turbine (VAWT), turbine blades are subjected to the curved flow field caused by the revolution of turbine. However, performance prediction of VAWT is usually based on the fluid dynamic coefficients obtained in wind tunnel measurements of the two-dimensional static wing. The difference of fluid dynamic coefficients in the curved flow and straight flow deteriorates the accuracy of performance prediction. To find the correlation between the two conditions of curved and straight flow, the authors propose a conformal mapping method on complex plane. It provides bidirectional mapping between the two flow fields. For example, the flow around a symmetric wing in the curved flow is mapped to that around a curved (cambered) wing in the straight flow. Although the shape of mapped wing section is different from the original one, its aerodynamic coefficients show a good correlation to those of the original in the rotating condition. With the proposed method, we can reproduce the local flow field around a rotating blade from the flow data around the mapped static wing in the straight flow condition.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    At ultra-high magnetic field (⩾7 T), 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 7 T, 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.

  17. 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. PMID:27638070

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Rotation at 30 RPM about the Z axis after 6 hours in the 10-deg head-down position - Effect on susceptibility to motion sickness

    NASA Technical Reports Server (NTRS)

    Graybiel, A.; Lackner, J. R.

    1979-01-01

    Intraindividual differences in susceptibility to motion sickness were measured in 14 subjects for two conditions of rotation at 30 rpm in the 10-deg head-down position. In one condition, subjects were in the 10-deg head-down position for 6 h prior to the onset of rotation; in the other condition, the delay was only 15 min. In both conditions, there were changes in vital capacity, indicating a redistribution of movable body fluids. Subjects tended to be less susceptible to motion sickness when they were recumbent for 6 h prior to rotation. These results are counterevidence for the hypothesis that shifts of body fluid are responsible in large part for the motion sickness elicited in orbital space flight.

  4. 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.

  5. 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.

  6. 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

  7. A rotating condenser and off-axis zone plate monochromator for the TXM at the undulator U41 at BESSY II

    NASA Astrophysics Data System (ADS)

    Niemann, B.; Guttmann, P.; Hambach, D.; Schneider, G.; Weiß, D.; Schmahl, G.

    2001-07-01

    The Göttingen transmission X-ray microscope at the low emittance electron storage ring BESSY II uses the concept of dynamical aperture synthesis (Reynolds, DeVelis, Parrent, Thomson (Eds.), The New Physical Optics Notebook, SPIE, 1990, pp. 536-548) for the object illumination. The concept is well suited as a condenser, as it can match any required numerical aperture of the TXM objective. Furthermore, a novel off-axis transmission zone-plate monochromator is included, which can generate a monochromaticity of several thousand in the object illumination.

  8. Unique paleopathology in a pre-Columbian mummy remnant from Southern Peru--severe cervical rotation trauma with subluxation of the axis as cause of death.

    PubMed

    Sokiranski, Roman; Pirsig, Wolfgang; Richter, Hans-Peter; Lösch, Sandra; Struck, Ulrich; Nerlich, Andreas G

    2011-03-01

    We describe the multidisciplinary findings in a pre-Columbian mummy head from Southern Peru (Cahuachi, Nazca civilisation, radiocarbon dating between 120 and 750 AD) of a mature male individual (40-60 years) with the first two vertebrae attached in pathological position. Accordingly, the atlanto-axial transition (C1/C2) was significantly rotated and dislocated at 38° angle associated with a bulging brownish mass that considerably reduced the spinal canal by circa 60%. Using surface microscopy, endoscopy, high-resolution multi-slice computer tomography, paleohistology and immunohistochemistry, we identified an extensive epidural hematoma of the upper cervical spinal canal-extending into the skull cavity-obviously due to a rupture of the left vertebral artery at its transition between atlas and skull base. There were no signs of fractures of the skull or vertebrae. Histological and immunohistochemical examinations clearly identified dura, brain residues and densely packed corpuscular elements that proved to represent fresh epidural hematoma. Subsequent biochemical analysis provided no evidence for pre-mortal cocaine consumption. Stable isotope analysis, however, revealed significant and repeated changes in the nutrition during his last 9 months, suggesting high mobility. Finally, the significant narrowing of the rotational atlanto-axial dislocation and the epidural hematoma probably caused compression of the spinal cord and the medulla oblongata with subsequent respiratory arrest. In conclusion, we suggest that the man died within a short period of time (probably few minutes) in an upright position with the head rotated rapidly to the right side. In paleopathologic literature, trauma to the upper cervical spine has as yet only very rarely been described, and dislocation of the vertebral bodies has not been presented.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. What does physical rotation reveal about mental rotation?

    PubMed

    Gardony, Aaron L; Taylor, Holly A; Brunyé, Tad T

    2014-02-01

    In a classic psychological science experiment, Shepard and Metzler (1971) discovered that the time participants took to judge whether two rotated abstract block figures were identical increased monotonically with the figures' relative angular disparity. They posited that participants rotate mental images to achieve a match and that mental rotation recruits motor processes. This interpretation has become central in the literature, but until now, surprisingly few researchers have compared mental and physical rotation. We had participants rotate virtual Shepard and Metzler figures mentally and physically; response time, accuracy, and real-time rotation data were collected. Results suggest that mental and physical rotation processes overlap and also reveal novel conclusions about physical rotation that have implications for mental rotation. Notably, participants did not rotate figures to achieve a match, but rather until they reached an off-axis canonical difference, and rotational strategies markedly differed for judgments of whether the figures were the same or different.

  16. 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.

  17. 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.

  18. Rotating superfluid turbulence.

    PubMed

    Tsubota, Makoto; Araki, Tsunehiko; Barenghi, Carlo F

    2003-05-23

    Almost all studies of vortex states in helium II have been concerned with either ordered vortex arrays or disordered vortex tangles. This work numerically studies what happens in the presence of both rotation (which induces order) and thermal counterflow (which induces disorder). We find a new statistically steady state in which the vortex tangle is polarized along the rotational axis. Our results are used to interpret an instability that was discovered experimentally by Swanson et al. [Phys. Rev. Lett. 50, 190 (1983)

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Kinesin follows the microtubule's protofilament axis

    PubMed Central

    1993-01-01

    We tested the hypothesis that kinesin moves parallel to the microtubule's protofilament axis. We polymerized microtubules with protofilaments that ran either parallel to the microtubule's long axis or that ran along shallow helical paths around the cylindrical surface of the microtubule. When gliding across a kinesin-coated surface, the former microtubules did not rotate. The latter microtubules, those with supertwisted protofilaments, did rotate; the pitch and handedness of the rotation accorded with the supertwist measured by electron cryo- microscopy. The results show that kinesin follows a path parallel to the protofilaments with high fidelity. This implies that the distance between consecutive kinesin-binding sites along the microtubule must be an integral multiple of 4.1 nm, the tubulin monomer spacing along the protofilament, or a multiple of 8.2 nm, the dimer spacing. PMID:8099076

  9. 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.

  10. Major and minor axis kinematics of 22 ellipticals

    NASA Astrophysics Data System (ADS)

    Franx, Marijn; Illingworth, Garth; Heckman, Timothy

    1989-09-01

    Rotation curves and velocity dispersion profiles have been determined for the major and the minor axes of 22 elliptical galaxies. Rotation was detected in all but one galaxy, even though the sample was biased toward round ellipticals. Minor axis rotation larger than major axis rotation was measured in two galaxies, NGC 4406 and NGC 7507. Roughly 10 percent of ellipticals may show large minor axis velocities relative to those on the major axis. A simple model is used to derive a rotational axis from the observed minor and major axis velocities to a typical accuracy of 6 deg. The rotational and photometric minor axes aligned to better than 10 deg for 60 percent of the sample, implying that the direction of the angular momentum is related to the orientation of the figure of the galaxy. IC 1459 has a kinematically distinct core with its angular momentum opposite to the angular momentum of the outer parts, and NGC 4406 has a core with its angular momentum perpendicular to that of the outer parts.

  11. Vertical Axis Wind Turbine

    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.

  12. Vertical-axis wind turbines -- The current status of an old technology

    SciTech Connect

    Berg, D.E.

    1996-12-31

    Vertical-axis wind turbine technology is not well understood, even though the earliest wind machines rotated about a vertical axis. The operating environment of a vertical-axis wind turbine is quite complex, but detailed analysis capabilities have been developed and verified over the last 30 years. Although vertical-axis technology has not been widely commercialized, it exhibits both advantages and disadvantages compared to horizontal-axis technology, and in some applications, it appears to offer significant advantages.

  13. Paleomagnetic Correlation of Late Miocene-Pliocene Basalt Flows in the Northwestern Basin and Range: Documenting Timing of Faulting, Volcanism and Vertical-axis Rotation in Surprise Valley, Northeastern California

    NASA Astrophysics Data System (ADS)

    Ritzinger, B. T.; Glen, J. M. G.; Egger, A. E.

    2014-12-01

    Examining the temporal and spatial relationship between basaltic volcanism and extensional faulting can help delineate the influence of faulting on the location of source vents and distribution of subsequent lava flows. Young extensional environments offer a unique opportunity to resolve the interdependence of faulting and volcanism as faults have not yet been buried and precise ages can be acquired on volcanic rocks. The Larkspur Hills, located along the northwestern margin of the Basin and Range in northeastern California preserve flow-on-flow basalt sequences exposed in the footwalls of numerous normal faults. The eruption of these 3 to 8 Ma flows was coeval with the development and progression of extensional faulting, but the detailed relationship was not clear. Although several flows have previously been dated using 40Ar/39Ar geochronology, individual flows cannot easily be identified in outcrop or geochemically. Paleomagnetic analyses have allowed us to differentiate individual flows possessing unique remanence directions, and to correlate flow sequences. Nearly 1,300 paleomagnetic core samples from 167 flows were collected within the Larkspur Hills. Generalized magnetostratigraphy and detailed remanent magnetic directions were analyzed in conjunction with the existing geochronology to correlate flows and constrain the relative timing of faulting and volcanism. Results indicate that volcanic activity occurred during four distinct episodes between 3 to 8 Ma, and suggest that contemporaneous faulting likely influenced the distribution of subsequent flows by producing topographic barriers or pathways to the flows. In addition, when compared to the expected reference direction for stable North America, the paleomagnetic data indicate that the region has undergone 11.9 ± 4.5˚ of clockwise rotation. This result agrees favorably with studies that have inferred appreciable rotation of our study area associated with clockwise rotation of the Oregon coastal block.

  14. Global Rotation of Non-Rotating Origin

    NASA Astrophysics Data System (ADS)

    Fukushima, T.

    2001-11-01

    At its 24th General Assembly held at Manchester last year, the IAU has adopted the Celestial Ephemeris Origin (CEO) as a new longitude origin of the celestial coordinate system (Capitaine et al. 2000, IAU 2001). The CEO is the application of Guinot's non-rotating origin (NRO) to the Earth's equator (Guinot 1979, Capitaine et al. 1986, Capitaine 1990). By using the current IAU precession/nutation theory, we integrated the global orbit of CEO. It is a slightly curved zigzag pattern of the amplitude of around 23o moving secularly along the ecliptic. Among its kinematical features, we note that CEO has a large secular component of rotation with respect to the inertial reference frame. The current speed of this global rotation is as large as around -4.15 ''/yr. The negative sign shows that CEO rotates clockwise with respect to the inertial frame when viewed from the north celestial pole. Unfortunately this is a general property of NROs. On the other hand, such secular rotation does not exist for some geometrically-defined longitude origins like K, H, and Σ already discussed in Kovalevsky and McCarthy (1998). We think that the existence of a global secular rotaion means that the CEO, and NROs in general, is not appropriate to be specified as the x-axis of celestial coordinate systems.

  15. 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.

  16. 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.

  17. ScaphoLunate Axis Method.

    PubMed

    Yao, Jeffrey; Zlotolow, Dan A; Lee, Steve K

    2016-03-01

    Background Treating chronic scapholunate ligament injuries without the presence of arthritis remains an unsolved clinical problem facing wrist surgeons. This article highlights a technique for reconstructing the scapholunate ligament using novel fixation, the ScaphoLunate Axis Method (SLAM). Materials and Methods In a preliminary review of the early experience of this technique, 13 patients were evaluated following scapholunate ligament reconstruction utilizing the SLAM technique. Description of Techinque The scapholunate interval is reconstructed utilizing a palmaris longus autograft passed between the scaphoid and lunate along the axis of rotation in the sagittal plane. It is secured in the lunate using a graft anchor and in the scaphoid utilizing an interference screw. The remaining graft is passed dorsally to reconstruct the dorsal scapholunate ligament. Results At an average follow-up of 11 months, the mean postoperative scapholunate gap was 2.1 mm. The mean postoperative scapholunate angle was 59 degrees. The mean postoperative wrist flexion and extension was 45 and 56 degrees, respectively. The mean grip strength was 24.9 kg, or 62% of the contralateral side. The mean pain score (VAS) was 1.7. There was 1 failure with recurrence of the pathologic scapholunate gap and the onset of pain. Conclusion While chronic scapholunate ligament instability remains an unsolved problem facing wrist surgeons, newer techniques are directed toward restoring the normal relationships of the scaphoid and lunate in both the coronal and sagittal planes. The SLAM technique has demonstrated promise in preliminary clinical studies. PMID:26855838

  18. Centration axis in refractive surgery.

    PubMed

    Arba Mosquera, Samuel; Verma, Shwetabh; McAlinden, Colm

    2015-01-01

    The human eye is an asymmetric optical system and the real cornea is not a rotationally symmetrical volume. Each optical element in the eye has its own optical and neural axes. Defining the optimum center for laser ablation is difficult with many available approaches. We explain the various centration approaches (based on these reference axes) in refractive surgery and review their clinical outcomes. The line-of-sight (LOS) (the line joining the entrance pupil center with the fixation point) is often the recommended reference axis for representing wavefront aberrations of the whole eye (derived from the definition of chief ray in geometrical optics); however pupil centration can be unstable and change with the pupil size. The corneal vertex (CV) represents a stable preferable morphologic reference which is the best approximate for alignment to the visual axis. However, the corneal light reflex can be considered as non-constant, but dependent on the direction of gaze of the eye with respect to the light source. A compromise between the pupil and CV centered ablations is seen in the form of an asymmetric offset where the manifest refraction is referenced to the CV while the higher order aberrations are referenced to the pupil center. There is a need for a flexible choice of centration in excimer laser systems to design customized and non-customized treatments optimally. PMID:26605360

  19. Heat transfer in rotating coolant channels

    NASA Astrophysics Data System (ADS)

    Wang, Baoguan; Zheng, Jirui; Ding, Xiaojiang

    The effect of cooling channels' rotation on the local and mean heat transfer is investigated using an experimental simulation of three types of flow in rotating circular tubes: (1) flow parallel to the rotating axis, (2) radially outward flow perpendicular to the rotating axis, and (3) radially inward flow perpendicular to the rotating axis. Theoretical analysis uses the boundary layer model method, in which the flow in a tube is divided into the core and boundary layer zones with different assumptions for each zone, and the equations are solved using the momentum integration method. Experimental results were obtained using a specially designed facility incorporating all three modes of flow. The results confirm that rotation of the flow in a tube can enhance the heat transfer processes whether the flow is parallel or perpendicular to the rotating axis. The incremental increase in heat transfer rate due to rotation was found to be more pronounced at low rotational speeds than at high speeds. The variation of local heat transfer coefficients along axial direction is affected by the inlet and outlet sections and by the ratio of length to diameter.

  20. 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.

  1. 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...

  2. Rotational moulding.

    PubMed

    Crawford, R J; Kearns, M P

    2003-10-01

    Rotational moulding promises designers attractive economics and a low-pressure process. The benefits of rotational moulding are compared here with other manufacturing methods such as injection and blow moulding. PMID:14603714

  3. The immature HPO axis.

    PubMed

    Buttram, V C

    1975-01-01

    One cause or anovulation may be an immature hypothalamic-pituitary-ovarian axis. The fact that initial menstrual cycles are usually irregular and often anovulatory implies that a maturation process is taking place in the HPO axis and that cyclic ovulatory menstruation begins only when adequate maturation occurs. Moreover, the external appearance of the ovary of a severely oligomenorrheic or amenorrheic female frequently is similar to that of a prepubertal female--this is, the ovary appears normal in size of slightly smaller, has a smooth, glistening surface without convolutions, and its capsule-like outer surface reveals few, if any, underlying follicles. A reasonable assumption is that there is inadequate gonadotropin stimulation of these ovaries possibly as a result of an immature HPO axis. The studies by radioimmunoassay of FSH and LH levels in prepubertal and pubertal females offer no statistical data by which to measure the maturity of the HPO axis, although consistently low FSH and LH levels may prove meaningful. Studies of FSH and LH in patients exhibiting gonadal dysgenesis neither support or disprove the immature HPO axis theory, but studies of idiopathic sexual precocity tend to support it. Studies using LH-RF in prepubertal and pubertal females indicate a pattern of response which may give useful information in the area.

  4. Single-beam three-axis atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Huang, Haichao; Dong, Haifeng; Chen, Lin; Gao, Yang

    2016-08-01

    A single-beam atomic magnetometer being operated near zero-field and measuring three-axis fields simultaneously is demonstrated. We produce a rotating field on the x-0-y plane with the frequency of 90 Hz and a modulation field in the z axis at 130 Hz. The rotating field enables a nonzero z axis output when the transverse fields are zeroed using feedback systems. Based on the phase difference of π / 2 , x and y axes fields can be measured using one lock-in amplifier. Magnetic field sensitivities of 300 fT/Hz1/2 in x and y axes and 3 pT/Hz1/2 in the z axis are achieved.

  5. Theoretical three-and four-axis gimbal robot wrists

    NASA Technical Reports Server (NTRS)

    Barker, L. K.; Houck, J. A.

    1986-01-01

    In high-performance flight simulations, a four-axis gimbal system allows all possible rotations with acceptable gimbal angle rates while it avoids the so-callled 'gimbal lock' that occurs when gimbal rotational axes are colinear. In this paper, pertinent equations (including quaternions) are assembled for a hypothetical robot wrist, functionally equivalent to this four-axis gimbal system, and also for a true three-axis gimbal robot wrist. These equations are used to simulate the rotation of a robot hand by the robot wrist in response to operator rotational velocity commands to the robot hand. Near gimbal lock (wrist singularity), excessive rotational rates occur. Scaling the rates, which is necessary for the three-gimbal robot wrist to prevent rate limiting, introduces an undesirable time delay in the robot hand rotation with respect to the commanded rotation. However, the merit of the four-gimbal robot wrist is that the fourth gimbal angle keeps the robot wrist away from the singularity so that the robot hand moves exactly as commanded. It appears that in a 'worst-type' maneuver of the robot hand, the fourth gimbal angle can be defined so that none of the gimbal angle rates exceed about twice the commanded rates.

  6. 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.

  7. 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.

  8. 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)

  9. Computer Assisted Mechanical Axis and Kinematic TKA

    PubMed Central

    McEwen, Peter; Mahoharan, Varaguna

    2016-01-01

    Introduction: Total knee arthroplasty (TKA) has traditionally been and largely continues to be aligned mechanically, that being with a neutral coronal plane mechanical tibiofemoral axis and a joint line orientated at 900 to this axis. Femoral component rotation is set by gap balancing or by externally rotating 30 from any of a number femoral reference lines. This produces a rectangular flexion gap and relaxes patellar tracking. Kinematic alignment (KA) is an alternative technique that aims to restore premorbid alignment, joint orientation and ligament tension. The basic premise for this technique is based on evidence that the medial and lateral femoral condyles consistently equate to cylinders of equal or near equal size and that therefore with a fixed radius, cruciate retaining implant, matched distal femoral, posterior femoral and proximal tibial resections, accounting for bone and cartilage already lost will reproduce the premorbid joint line and restore native premorbid kinematics. Femoral rotation is therefore referenced off the prearthritic posterior condylar axis (PCA) that is on average internally rotated to the AP axis. Kinematic alignment therefore has the potential to challenge patellar tracking, increase patellar load and potentially increase patellar complications. Method: Case control study – level of evidence III-2. Between November 2012 and June 2013 the senior author completed 104 consecutive computer assisted (CAS) kinematically aligned total knee arthroplasties (TKA) with a cruciate retaining, fixed bearing, single radius implant. The results of these surgeries were compared with the results of 91 consecutive CAS mechanically aligned TKA done between November 2011 and October 2012 using the same navigation system and implant Implant sizing and positioning as well as gap measurement and ligament balance was done with computer assistance in all cases. Data was collected prospectively and analysed retrospectively. Results: The Oxford Knee Score

  10. 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…

  11. 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.)

  12. 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

  13. Multiple axis reticle

    NASA Astrophysics Data System (ADS)

    Barns, Chris E.; Gunter, William D.

    1990-09-01

    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.

  14. 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.

  15. Synchronisation of tibial rotational alignment with femoral component in total knee arthroplasty.

    PubMed

    Lee, Dong-Hoon; Seo, Jai-Gon; Moon, Young-Wan

    2008-04-01

    The rotational axis of the tibial component in total knee arthroplasty described by Insall is generally accepted, but rotational mismatch between the femoral and the tibial components can occur because the alignment of each component is determined separately. We developed a connecting instrument to synchronise the axis of the tibia to the axis of the femur. We compared the rotational axis of the tibial component using our method and medial one third of tibial tuberosity (Insall's reference) in 70 consecutive TKAs. The rotational axis of the tibial component from the femoro-tibial synchronisation was rotated internally 13.8 degrees +/- 5.8 degrees (range, 2 degrees - 24 degrees ) more than the axis of Insall's reference. Eighty three percent of patellae tracked centrally and the patellae tilt measured 2.2 degrees on average. More attention should be given to the rotational congruency between the femoro-tibial components, because the recent prosthetic design has more conforming articular surfaces.

  16. 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.

  17. Covariant density functional theory for magnetic rotation

    NASA Astrophysics Data System (ADS)

    Peng, J.; Meng, J.; Ring, P.; Zhang, S. Q.

    2008-08-01

    The tilted axis cranking formalism is implemented in relativistic mean field (RMF) theory. It is used for a microscopic description of magnetic rotation in the framework of covariant density functional theory. We assume that the rotational axis is in the xz plane and consider systems with the two symmetries P (space reflection) and PyT (a combination of a reflection in the y direction and time reversal). A computer code based on these symmetries is developed, and first applications are discussed for the nucleus Gd142: the rotational band based on the configuration πh11/22⊗νh11/2-2 is investigated in a fully microscopic and self-consistent way. The results are compared with available data, such as spectra and electromagnetic transition ratios B(M1)/B(E2). The relation between rotational velocity and angular momentum are discussed in detail together with the shears mechanism characteristic of magnetic rotation.

  18. 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.

  19. Effect of Relative Marker Movement on the Calculation of the Foot Torsion Axis Using a Combined Cardan Angle and Helical Axis Approach

    PubMed Central

    Graf, Eveline S.; Wright, Ian C.; Stefanyshyn, Darren J.

    2012-01-01

    The two main movements occurring between the forefoot and rearfoot segment of a human foot are flexion at the metatarsophalangeal joints and torsion in the midfoot. The location of the torsion axis within the foot is currently unknown. The purpose of this study was to develop a method based on Cardan angles and the finite helical axis approach to calculate the torsion axis without the effect of flexion. As the finite helical axis method is susceptible to error due to noise with small helical rotations, a minimal amount of rotation was defined in order to accurately determine the torsion axis location. Using simulation, the location of the axis based on data containing noise was compared to the axis location of data without noise with a one-sample t-test and Fisher's combined probability score. When using only data with helical rotation of seven degrees or more, the location of the torsion axis based on the data with noise was within 0.2 mm of the reference location. Therefore, the proposed method allowed an accurate calculation of the foot torsion axis location. PMID:22666303

  20. 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)

  1. 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.

  2. Control system for a vertical axis windmill

    SciTech Connect

    Brulle, R.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/sup 0/ 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.

  3. Control system for a vertical axis windmill

    SciTech Connect

    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.

  4. Vertical axis wind turbines

    DOEpatents

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

    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.

  5. Guide for rotating sucker rods

    SciTech Connect

    Harrel, R.D.

    1986-11-04

    This patent describes an improved guide for use in a string of sucker rods rotated in a tubing string in a borehole, the sucker rods having threaded male ends, the guide comprising: an elongated upright solid cylindrical coupling body of external diameter less than the internal diameter of tubing in which it is to be used; a pair of spaced apart axle holders positioned in three recess; an axle received in each recess in the coupling body, the axis of each axle being parallel and spaced from the body longitudinal axis; a roller rotatably received on each axle, the periphery of each roller extending exteriorly of the external cylindrical surface of the coupling body; and means to retain each of the holders in the coupling body recess.

  6. Axial breathing mode in rapidly rotating Bose-Einstein condensates and uncertainty of the rotation velocity

    SciTech Connect

    Watanabe, Gentaro

    2007-09-15

    Experiments on the axial breathing mode in a rapidly rotating Bose-Einstein condensate are examined. Assuming a cold cloud without thermal component, we show that errors due to defocus of an imaging camera in addition to an inclination of the rotational axis can lead to a significant underestimate of the rotation rate in the fast rotation limit; within these uncertainties, our theoretical prediction agrees with the experimental data. We also show that, in the fast rotation regime, the Thomas-Fermi theory, which is inapplicable there, underestimates the rotation rate. Underestimation of the rotation rate due to these effects would also partly explain a discrepancy between theory and experiment for the Tkachenko mode frequency in the fast rotation regime.

  7. Semimajor Axis Estimation Strategies

    NASA Technical Reports Server (NTRS)

    How, Jonathan P.; Alfriend, Kyle T.; Breger, Louis; Mitchell, Megan

    2004-01-01

    This paper extends previous analysis on the impact of sensing noise for the navigation and control aspects of formation flying spacecraft. We analyze the use of Carrier-phase Differential GPS (CDGPS) in relative navigation filters, with a particular focus on the filter correlation coefficient. This work was motivated by previous publications which suggested that a "good" navigation filter would have a strong correlation (i.e., coefficient near -1) to reduce the semimajor axis (SMA) error, and therefore, the overall fuel use. However, practical experience with CDGPS-based filters has shown this strong correlation seldom occurs (typical correlations approx. -0.1), even when the estimation accuracies are very good. We derive an analytic estimate of the filter correlation coefficient and demonstrate that, for the process and sensor noises levels expected with CDGPS, the expected value will be very low. It is also demonstrated that this correlation can be improved by increasing the time step of the discrete Kalman filter, but since the balance condition is not satisfied, the SMA error also increases. These observations are verified with several linear simulations. The combination of these simulations and analysis provide new insights on the crucial role of the process noise in determining the semimajor axis knowledge.

  8. Rotation of cometary meteoroids

    NASA Astrophysics Data System (ADS)

    Čapek, D.

    2014-08-01

    Aims: The rotation of meteoroids caused by gas drag during the ejection from a cometary nucleus has not been studied yet. The aim of this study is to estimate the rotational characteristics of meteoroids after their release from a comet during normal activity. Methods: The basic dependence of spin rate on ejection velocity and meteoroid size is determined analytically. A sophisticated numerical model is then applied to meteoroids ejected from the 2P/Encke comet. The meteoroid shapes are approximated by polyhedrons, which have been determined by a 3D laser scanning method of 36 terrestrial rock samples. These samples come from three distinct sets with different origins and characteristics, such as surface roughness or angularity. Two types of gas-meteoroid interactions and three gas ejection models are assumed. The rotational characteristics of ejected meteoroid population are obtained by numerical integration of equations of motion with random initial conditions and random shape selection. Results: It is proved that the results do not depend on a specific set of shape models and that they are applicable to the (unknown) shapes of real meteoroids. A simple relationship between the median of meteoroid spin frequencies bar{f} (Hz), ejection velocities vej (m s-1), and sizes D (m) is determined. For diffuse reflection of gas molecules from meteoroid's surface it reads as bar{f≃ 2× 10-3 v_ej D-0.88}, and for specular reflection of gas molecules from meteoroid's surface it is bar{f≃ 5× 10-3 v_ej D-0.88}. The distribution of spin frequencies is roughly normal on log scale, and it is relatively wide: a 2σ-interval can be described as (0.1, 10)× bar{f}. Most of the meteoroids are non-principal axis rotators. The median angle between angular momentum vector and spin vector is 12°. About 60% of meteoroids rotate in long-axis mode. The distribution of angular momentum vectors is not random. They are concentrated in the perpendicular direction with respect to the gas

  9. 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.

  10. Acoustic streaming flows and sample rotation control

    NASA Astrophysics Data System (ADS)

    Trinh, Eugene

    1998-11-01

    Levitated drops in a gas can be driven into rotation by altering their surrounding convective environment. When these drops are placed in an acoustic resonant chamber, the symmetry characteristics of the steady streaming flows in the vicinity of the drops determine the rotational motion of the freely suspended fluid particles. Using ultrasonic standing waves around 22 kHz and millimeter-size electrostatically levitated drops, we have investigated the correlation between the convective flow characteristics and their rotational behavior. The results show that accurate control of the drop rotation axis and rate can be obtained by carefully modifying the symmetry characteristics of the chamber, and that the dominant mechanism for rotation drive is the drag exerted by the air flow over the drop surface. In addition, we found that the rotational acceleration depends on the drop viscosity, suggesting that this torque is initially strongly influenced by differential flows within the drop itself. [Work sponsored by NASA].

  11. Instabilities in coaxial rotating jets

    NASA Astrophysics Data System (ADS)

    Ivanic, Tanja; Foucault, Eric; Pecheux, Jean; Gilard, Virginie

    2000-12-01

    The aim of this study is the characterization of the cylindrical mixing layer resulting from the interaction of two coaxial swirling jets. The experimental part of this study was performed in a cylindrical water tunnel, permitting an independent rotation of two coaxial jets. The rotations are generated by means of 2×36 blades localized in two swirling chambers. As expected, the evolution of the main instability modes presents certain differences compared to the plane-mixing-layer case. Experimental results obtained by tomography showed the existence of vortex rings and streamwise vortex pairs in the near field region. This method also permitted the observation of the evolution and interaction of different modes. PIV velocity measurements realized in the meridian plans and the plans perpendicular to the jet axis show that rotation distorts the typical top-hat axial velocity profile. The transition of the axial velocity profile from jet-like into wake-like is also observed.

  12. Horizontal axis windmill

    SciTech Connect

    Mundhenke, I.W.

    1984-05-22

    A base frame supports a horizontal shaft having one or more wind driven members secured thereon. Each of the wind driven members includes a shaft of light-weight framing and plurality of elongated longitudinally extending light-weight vanes having wind engaging surfaces. The vanes have a wind driving position on one side of the shaft and a return position of the other, and light-weight wind deflectors disposed at the front of the frame protecting the return position of the vanes from the wind. The wind deflectors are angularly adjustable whereby the deflected wind flowing off the longitudinal edges thereof is selectively directed against the vane surfaces in their driving position. The shaft has an output for operating a selected driven apparatus such as a generator. The base frame is rotatably supported on a pivot for selected adjustment relative to the wind.

  13. 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.

  14. Electrical generation using a vertical-axis wind turbine

    SciTech Connect

    Clark, R.N.

    1982-12-01

    Traditionally, windmills have been of the propeller or multiblade types, both of which have their rotational axis parallel to the flow of the wind. A vertical-axis wind turbine has its rotational axis perpendicular to the flow of wind and requires no orientation to keep the rotor in the windstream. The vertical-axis wind turbine operates on the same principle as an airfoil and produces lift and drag as any airfoil. A newly designed 100-kW vertical-axis wind turbine has been operated for one year at the USDA Conservation and Production Research Laboratory, Bushland, TX. The turbine has an induction generator and supplies power to a sprinkler irrigation system with excess power being sold to the electric utility. The turbine begins producing power at 5.5 m/s windspeed and reaches its rated output of 100-kW at 15 m/s. The unit has obtained a peak efficiency of 48% at a windspeed of 8 m/s or 81% of theoretical maximum. Using 17 years of windspeed data from the National Weather Service, the annual energy output is estimated at 200,000 kWh. The unit has experienced several operational problems during its initial testing. Guy cables were enlarged to provide greater stiffness to reduce blade stress levels, lightning shorted the main contactor, and the brake system required a complete redesign and modification. The turbine was operational about 60% of the time.

  15. Micromachined dual input axis rate gyroscope

    NASA Astrophysics Data System (ADS)

    Juneau, Thor Nelson

    The need for inexpensive yet reliable angular rate sensors in fields ranging from automotive to consumer electronics has motivated prolific micromachined rate gyroscope research. The vast majority of research has focused on single input axis rate gyroscopes based upon either translational resonance, such as tuning forks, or structural mode resonance, such as vibrating rings. However, this work presents a novel, contrasting approach based on angular resonance of a rotating rigid rotor suspended by torsional springs. The inherent symmetry of the circular design allows angular rate measurement about two axes simultaneously, hence the name micromachined dual-axis rate gyroscope. The underlying theory of operation, mechanical structure design optimization, electrical interface circuitry, and signal processing are described in detail. Several operational versions were fabricated using two different fully integrated surface micromachining processes as proof of concept. The heart of the dual-axis rate gyroscope is a ˜2 mum thick polysilicon disk or rotor suspended above the substrate by a four beam suspension. When this rotor in driven into angular oscillation about the axis perpendicular to the substrate, a rotation rate about the two axes parallel to the substrate invokes an out of plane rotor tilting motion due to Coriolis acceleration. This tilting motion is capacitively measured and on board integrated signal processing provides two output voltages proportional to angular rate input about the two axes parallel to the substrate. The design process begins with the derivation of gyroscopic dynamics. The equations suggest that tuning sense mode frequencies to the drive oscillation frequency can vastly increase mechanical sensitivity. Hence the supporting four beam suspension is designed such that electrostatic tuning can match modes despite process variations. The electrostatic tuning range is limited only by rotor collapse to the substrate when tuning-voltage induced

  16. Use of the Humphrey Lens Analyzer for off-axis measurements of spectacle lenses.

    PubMed

    Atchison, D A; Kris, M; Sheedy, J E; Bailey, I L

    1991-04-01

    Automated focimeters can be used to make quick, precise measurements of off-axis power and prismatic effects corresponding to an eye rotating behind a spectacle lens. An automated focimeter, the Humphrey Lens Analyzer, was assessed in this regard. The Humphrey Lens Analyzer can be used to give a valid measure of off-axis power of lenses with low power, but not of lenses with moderate to higher power (greater than 3 D). For 3 D spherical lenses discrepancies of the order of 0.1 D occur at 30 degrees rotation, and 6 D spheres give discrepancies of 0.5 D at the same rotation. Small discrepancies were found for measurements of prism. The Humphrey Lens Analyzer was also used in a mode where the lens being tested is rotated about the center of curvature of its back surface. This is the mode often used to assess aberrations and prism of progressive-addition lenses. In this mode, the instrument provides reasonable accuracy in estimating off-axis power corresponding to eye rotation for lenses with low power, but not for lenses with moderate to higher power (greater than 3 D). However, it provides accurate values of the variation in off-axis surface power for low powered lenses with aspheric front surfaces. There were considerable systematic errors associated with the measurement of prism. A simple raytracing method was developed to predict the results of measurements with the Humphrey Lens Analyzer. Predictions of off-axis power were good when lenses were rotated about a position corresponding to the center-of-rotation of an eye, but were poorer when lenses were rotated about the center of curvature of their back surfaces. Predictions of primatic efforts were good in both situations. A method by which the Humphrey Lens Analyzer should provide an accurate measurement of off-axis powers corresponding to eye rotation behind a spectacle lens is described, but has not been tested. PMID:2052286

  17. 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.

  18. 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.

  19. 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.

  20. 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).

  1. 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.

  2. 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." (CS)

  3. Insights from the rotational braking of solar twins: is the Sun a regular rotator?

    NASA Astrophysics Data System (ADS)

    Dos Santos, Leonardo Augusto; Melendez, Jorge

    2016-06-01

    Although the Sun is widely used as a reference star in astrophysics, it is still unclear how regular it is when compared to other similar stars in regards to some of its physical properties, such as its rotation. We analyze the rotational velocities (limited by the unknown rotation axis inclination angle) of an unprecedented sample of solar twins in order to study how common the Sun is in its rotation. We use high-resolution (R = 115000) spectra obtained with the HARPS spectrograph and ESO’s 3.6 m telescope at La Silla Observatory. The projected rotational velocities for 71 solar twins are estimated through line profile fitting using synthetic spectra. We take into account the macroturbulence velocities in a separate analysis, for they are known to be difficult to disentangle from rotation. Our sample of solar twins include some spectroscopic binaries with enhanced rotational velocities, and we do not find any non-spectroscopic binaries with unusually high rotation velocities. The Sun does not have a peculiar rotation, but the solar twins exhibit rotational velocities that depart from the tried and tested Skumanich’s law. We conclude that the Sun is a regular rotator when compared to solar twins with a similar age, and obtain a rotational braking law that better describes the stars in our sample when compared to previous, often-used scalings.

  4. Modified Denavit-Hartenberg parameters for better location of joint axis systems in robot arms

    NASA Technical Reports Server (NTRS)

    Barker, L. K.

    1986-01-01

    The Denavit-Hartenberg parameters define the relative location of successive joint axis systems in a robot arm. A recent justifiable criticism is that one of these parameters becomes extremely large when two successive joints have near-parallel rotational axes. Geometrically, this parameter then locates a joint axis system at an excessive distance from the robot arm and, computationally, leads to an ill-conditioned transformation matrix. In this paper, a simple modification (which results from constraining a transverse vector between successive joint rotational axes to be normal to one of the rotational axes, instead of both) overcomes this criticism and favorably locates the joint axis system. An example is given for near-parallel rotational axes of the elbow and shoulder joints in a robot arm. The regular and modified parameters are extracted by an algebraic method with simulated measurement data. Unlike the modified parameters, extracted values of the regular parameters are very sensitive to measurement accuracy.

  5. Finite element forced vibration analysis of rotating cyclic structures

    NASA Technical Reports Server (NTRS)

    Elchuri, V.; Smith, G. C. C.

    1981-01-01

    A 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 axes 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 development of this capability is presented.

  6. 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.

  7. Rotation of Axes and the Mean Value Theorem

    ERIC Educational Resources Information Center

    Price, David

    2004-01-01

    This article provides a proof of the Mean Value Theorem by rotating a coordinate system through a specified angle. The use of this approach makes it easy to visualize why the Mean Value Theorem is true. An instructor can use the proof as another illustration of the rotation of axis technique in addition to the standard one of simplifying equations…

  8. Fixed geometry self starting transverse axis wind turbine

    SciTech Connect

    Dereng, V.G.

    1981-04-28

    This invention relates to a fixed geometry self starting wind turbine having a blade rotatable about a vertical axis. The blade is of a wide streamlined cambered airfoil shape and has a forward portion that includes a well rounded leading edge and thickness distribution that is conducive to high lift to drag ratios and having a high drag characteristic in reversed flows. The concave curvature of this camber line of said airfoil is directed to the rotational axis. The wide blade in combination with the well rounded leading edge, camber and airfoil thickness gives the turbine improved self-starting characteristics and causes the turbine to have improved acceleration characteristics through the intermediate speed range and up to full operating speed.

  9. The Wake of a Single Vertical Axis Wind Turbine

    NASA Astrophysics Data System (ADS)

    Barsky, Danielle

    Vertical axis wind turbines (VAWTs) pose various advantages over traditional horizontal axis wind turbines (HAWTs), including their smaller size and footprint, quiet operation, and ability to produce power under a greater variety of wind directions and wind speeds. To determine the optimal spacing of an array of VAWTs for maximum power output, an understanding of the fundamental wake structure of a single VAWT is needed. This study is among the first attempts to experimentally visualize the wake of a VAWT using stereo particle image velocimetry (PIV). A scale VAWT is placed inside a wind tunnel and a motor rotates the scale model at a constant rotational speed. Wake data at several Reynolds numbers and tip speed ratios indicate that vortices are shed by each blade of the spinning VAWT, demonstrating significant differences between the wake of a VAWT and a spinning cylinder.

  10. Axis I and Axis II diagnostic parameters of homicide.

    PubMed

    Yarvis, R M

    1990-01-01

    A series of 100 murderers was examined to discern overall patterns of psychopathology. In addition, demographic and other discriminating factors were used to test the hypothesis that murderers do not constitute a homogenous population and that subgroups will differ diagnostically. DSM-III diagnostic criteria were used to make each diagnosis. The sample was found to be representative of the universe from which it was drawn at least as could be determined by available comparative criteria. Four Axis I (psychoses, substance abuse, dysthymia, no Axis I) and three Axis II (antisocial, borderline, no Axis II) diagnostic categories accounted for more than 80 percent of the study population. The murderers were found to be a heterogenous population, and subgroups based on a combination of assailant's crime pattern, sex, prior criminal history, and relationship to victim manifested different prevailing diagnostic patterns.

  11. 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.

  12. 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.

  13. Differential rotation in solar convective dynamo simulations

    NASA Astrophysics Data System (ADS)

    Fan, Yuhong; Fang, Fang

    2016-10-01

    We carry out a magneto-hydrodynamic (MHD) simulation of convective dynamo in the rotating solar convective envelope driven by the solar radiative diffusive heat flux. The simulation is similar to that reported in Fan and Fang (2014) but with further reduced viscosity and magnetic diffusion. The resulting convective dynamo produces a large scale mean field that exhibits similar irregular cyclic behavior and polarity reversals, and self-consistently maintains a solar-like differential rotation. The main driver for the solar-like differential rotation (with faster rotating equator) is a net outward transport of angular momentum away from the rotation axis by the Reynolds stress, and we found that this transport is enhanced with reduced viscosity and magnetic diffusion.

  14. 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.

  15. System for controlled acoustic rotation of objects

    NASA Astrophysics Data System (ADS)

    Barmatz, M. B.

    1983-07-01

    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.

  16. 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

  17. 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.

  18. Six-axis inertial sensor using cold-atom interferometry.

    PubMed

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

    2006-07-01

    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.

  19. 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.

  20. 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.

  1. Visual perception of axes of head rotation

    PubMed Central

    Arnoldussen, D. M.; Goossens, J.; van den Berg, A. V.

    2013-01-01

    Registration of ego-motion is important to accurately navigate through space. Movements of the head and eye relative to space are registered through the vestibular system and optical flow, respectively. Here, we address three questions concerning the visual registration of self-rotation. (1) Eye-in-head movements provide a link between the motion signals received by sensors in the moving eye and sensors in the moving head. How are these signals combined into an ego-rotation percept? We combined optic flow of simulated forward and rotational motion of the eye with different levels of eye-in-head rotation for a stationary head. We dissociated simulated gaze rotation and head rotation by different levels of eye-in-head pursuit. We found that perceived rotation matches simulated head- not gaze-rotation. This rejects a model for perceived self-rotation that relies on the rotation of the gaze line. Rather, eye-in-head signals serve to transform the optic flow's rotation information, that specifies rotation of the scene relative to the eye, into a rotation relative to the head. This suggests that transformed visual self-rotation signals may combine with vestibular signals. (2) Do transformed visual self-rotation signals reflect the arrangement of the semi-circular canals (SCC)? Previously, we found sub-regions within MST and V6+ that respond to the speed of the simulated head rotation. Here, we re-analyzed those Blood oxygenated level-dependent (BOLD) signals for the presence of a spatial dissociation related to the axes of visually simulated head rotation, such as have been found in sub-cortical regions of various animals. Contrary, we found a rather uniform BOLD response to simulated rotation along the three SCC axes. (3) We investigated if subject's sensitivity to the direction of the head rotation axis shows SCC axes specifcity. We found that sensitivity to head rotation is rather uniformly distributed, suggesting that in human cortex, visuo-vestibular integration is

  2. 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.

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

    PubMed

    ter Horst, Arjan C; van Lier, Rob; Steenbergen, Bert

    2010-06-01

    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.

  4. Rotation of vertically oriented objects during earthquakes

    NASA Astrophysics Data System (ADS)

    Hinzen, Klaus-G.

    2012-10-01

    Vertically oriented objects, such as tombstones, monuments, columns, and stone lanterns, are often observed to shift and rotate during earthquake ground motion. Such observations are usually limited to the mesoseismal zone. Whether near-field rotational ground motion components are necessary in addition to pure translational movements to explain the observed rotations is an open question. We summarize rotation data from seven earthquakes between 1925 and 2009 and perform analog and numeric rotation testing with vertically oriented objects. The free-rocking motion of a marble block on a sliding table is disturbed by a pulse in the direction orthogonal to the rocking motion. When the impulse is sufficiently strong and occurs at the `right' moment, it induces significant rotation of the block. Numeric experiments of a free-rocking block show that the initiation of vertical block rotation by a cycloidal acceleration pulse applied orthogonal to the rocking axis depends on the amplitude of the pulse and its phase relation to the rocking cycle. Rotation occurs when the pulse acceleration exceeds the threshold necessary to provoke rocking of a resting block, and the rocking block approaches its equilibrium position. Experiments with blocks subjected to full 3D strong motion signals measured during the 2009 L'Aquila earthquake confirm the observations from the tests with analytic ground motions. Significant differences in the rotational behavior of a monolithic block and two stacked blocks exist.

  5. Modal testing of a rotating wind turbine

    SciTech Connect

    Carne, T.G.; Nord, A.R.

    1982-11-01

    A testing technique has been developed to measure the modes of vibration of a rotating vertical-axis wind turbine. This technique has been applied to the Sandia Two-Meter Turbine, where the changes in individual modal frequencies as a function of the rotational speed have been tracked from 0 rpm (parked) to 600 rpm. During rotational testing, the structural response was measured using a combination of strain gages and accelerometers, passing the signals through slip rings. Excitation of the turbine structure was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it was rotating at a set speed. In addition to calculating the real modes of the parked turbine, the modes of the rotating turbine were also determined at several rotational speeds. The modes of the rotating system proved to be complex due to centrifugal and Coriolis effects. The modal data for the parked turbine were used to update a finite-element model. Also, the measured modal parameters for the rotating turbine were compared to the analytical results, thus verifying the analytical procedures used to incorporate the effects of the rotating coordinate system.

  6. 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.

  7. 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

  8. Design and calibration of an elastically guided CMM axis with nanometer repeatability

    NASA Astrophysics Data System (ADS)

    van Seggelen, J. K.; Rosielle, P. C.; Schellekens, P. H.; Spaan, H. A.; Bergmans, R. H.; Kotte, G. J.

    2005-08-01

    This paper focuses on the on the design and calibration of an elastically guided vertical axis that will be applied in a small high precision 3D Coordinate Measuring Machine aiming a volumetric uncertainty of 25 nm. The design part of this paper discusses the principles of this system, the compensation of the stiffness of the vertical axis in the direction of motion, the weight compensation method and the design and performance of the axis precision drive system, a Lorentz actuator. In the metrology part of this paper the calibration methods to determine the linearity as well as motion straightness and axis rotation errors are discussed. Finally first calibration results of this axis show nanometer repeatability of the probing point over the 4 mm stroke of this axis. The causes of the short-term variations with a bandwidth of about +/- 10 nm are under investigation. Error compensation may reduce the residual error of the probing point to the nanometer level.

  9. Computed Tomography Analysis of Postsurgery Femoral Component Rotation Based on a Force Sensing Device Method versus Hypothetical Rotational Alignment Based on Anatomical Landmark Methods: A Pilot Study.

    PubMed

    Kreuzer, Stefan W; Pourmoghaddam, Amir; Leffers, Kevin J; Johnson, Clint W; Dettmer, Marius

    2016-01-01

    Rotation of the femoral component is an important aspect of knee arthroplasty, due to its effects on postsurgery knee kinematics and associated functional outcomes. It is still debated which method for establishing rotational alignment is preferable in orthopedic surgery. We compared force sensing based femoral component rotation with traditional anatomic landmark methods to investigate which method is more accurate in terms of alignment to the true transepicondylar axis. Thirty-one patients underwent computer-navigated total knee arthroplasty for osteoarthritis with femoral rotation established via a force sensor. During surgery, three alternative hypothetical femoral rotational alignments were assessed, based on transepicondylar axis, anterior-posterior axis, or the utilization of a posterior condyles referencing jig. Postoperative computed tomography scans were obtained to investigate rotation characteristics. Significant differences in rotation characteristics were found between rotation according to DKB and other methods (P < 0.05). Soft tissue balancing resulted in smaller deviation from anatomical epicondylar axis than any other method. 77% of operated knees were within a range of ±3° of rotation. Only between 48% and 52% of knees would have been rotated appropriately using the other methods. The current results indicate that force sensors may be valuable for establishing correct femoral rotation. PMID:26881086

  10. 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.

  11. 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

  12. Video- Demonstrations of Stable and Unstable Solid Body Rotation on the International Space Station

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Saturday Morning Science, the science of opportunity series of applied experiments and demonstrations, performed aboard the International Space Station (ISS) by Expedition 6 astronaut Dr. Don Pettit, revealed some remarkable findings. In this video clip, Pettit demonstrates stable and unstable modes for solid body rotation on the ISS. Using a hard cover textbook, he demonstrates that it will rotate stably about the longest and shortest axis, which represent the maximum and minimum movements of Inertia. Trying to rotate the book around an intermediate axis results in an unstable rotation in which the book appears to flip-flop while it rotates.

  13. On graphically representing the confidence region for an unknown rotation in three dimensions

    USGS Publications Warehouse

    Hanna, M.S.; Chang, T.

    1990-01-01

    In assessing the errors involved in reconstructing tectonic plate rotations, it is desirable to have confidence regions for the unknown rotation. This paper presents a method for graphing such confidence regions, which exhibits the dependence of the range of possible angles of rotation on the axis considered. Namely, the minimum and maximum angles of rotation are graphed as functions of axis longitude and latitude. A FORTRAN 77 program SPHEREREGRESS is given which, under a variety of probabilistic models for the data, generates grid matrices which are used to draw contour maps of the minimum and maximum angles of rotation. ?? 1990.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. a Rotating Heat Pipe for Cooling of Superconducting Machines

    NASA Astrophysics Data System (ADS)

    Jankowski, T. A.; Prenger, F. C.; Schmierer, E. N.; Razani, A.

    2008-03-01

    A curved rotating heat pipe for use in superconducting motor and generator applications is introduced here. The heat pipe shown 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. We show that because the heat pipe is a sealed, passive heat transfer device with nearly isothermal operation, the heat pipe concept may be advantageous when considering the overall refrigeration system used with the superconducting machine. High-speed, room temperature test data with this heat pipe geometry indicate that the working fluid in the heat pipe continued to circulate, resulting in heat transfer with a high effective thermal conductivity, with the heat pipe operating under the influence of centrifugal accelerations approaching 400 g.

  19. Vertical axis windmill with multistage feathering of blades and safety storm control

    SciTech Connect

    Stepp, W.J.

    1983-09-27

    A windmill of the vertical axis type is claimed having a plurality of circumferentially and radially outwardly spaced rotatably mounted vanes vertically parallel to the axis shaft wherein means are provided for controlling multistage feathering of the vanes in conjunction with said vanes feathering to rotate on their individual axes in a direction opposite to the direction of rotation of the windmill assembly in increments of 45 degrees twice for each blade before finally feathering a final half rotation completing the rotation of 360 degrees on its individual axis while the windmill makes one revolution, thus repeatedly repositioning the blades to the most optimum resistance angle to the wind as the windmill rotates increasing the power angle to near seventy-five percent of the circle of the windmill rotation, a construction option prevailing to routinely cause all the blades to feather when near a zero angular position to the wind, and having associated therewith a conglomerate of mechanical phenomena to perform said functions and to release all blades in the event of a wind velocity exceeding a safe speed for the structure, bringing the windmill to a stop until the wind velocity recedes to a safe precalculated speed causing the windmill to automatically resume operation, characteristic of the total and complete automatism of this windmill.

  20. Rotationally resolved electronic spectroscopy of 4-aminobenzonitrile

    NASA Astrophysics Data System (ADS)

    Berden, Giel; van Rooy, Jack; Meerts, W. Leo; Zachariasse, Klaas A.

    1997-10-01

    The rotationally resolved fluorescence excitation spectrum of the 0 00 band in the S 1 ← S 0 transition of 4-aminobenzonitrile (ABN) was recorded, at 299 nm, by using laser induced fluorescence in a molecular beam apparatus. This spectrum exhibits pure b-type character, which indicates that the electronic transition moment vector is oriented along the short molecular axis. The rotational constants of the S 0 and S 1 states were determined. In addition, the rotationally resolved fluorescence excitation spectra of two vibronic bands in the S 1 state, at 807 and 816 cm -1, were recorded. The molecular structure of the ABN molecule is discussed by comparing the rotational constants and the inertial defects.

  1. Diurnal and Semidiurnal Variations in Earth Rotation

    NASA Technical Reports Server (NTRS)

    Herring, T.

    1993-01-01

    During the last decade there has been an unprecedented improvement in both the accuracy, the temporal resolution of Earth's rotation measurements. Determination of the position of the Earth's rotation axis both in inertial space and with respect to the crust with accuracies of about 0.3 milliarcseconds (mas) are now routine. In recent years, there has been and emphasis on the determination of short-period (daily and less) variations in Earth rotation. Two space based geodetic systems, very long baseline interferometry (VLBI) and the global positioning system (GPS) have proved to be very successful in this endeavor. Results for the tidally coherent part of the subdaily Earth rotation variations determined from the analysis of VLBI data are discussed. The magnitude of other subdaily variations are also considered.

  2. 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.

  3. Rotator Cuff Tears

    MedlinePlus

    ... doctors because of a rotator cuff problem. A torn rotator cuff will weaken your shoulder. This means ... or more of the rotator cuff tendons is torn, the tendon no longer fully attaches to the ...

  4. Free collapse of a rotating sphere of stars

    NASA Technical Reports Server (NTRS)

    Miller, R. H.

    1978-01-01

    The free-fall collapse of a system of 115,000 stars was studied by means of a three-dimensional simulation on the ILLIAC IV computer. The system started from a spherical shape with uniform density and rigid rotation which balanced the gravitational force in the equatorial plane. The system settled down into a 'hot' prolate 'bar' in about two initial rotation periods. This bar rotates about a short axis and is a long-lived form. Detailed discussion of the development of this system leads to several important dynamical inferences: (1) the first collapse does not become triaxial, and the prolate form follows much later; (2) forms seen in projection along the rotation axis are strikingly similar to forms seen in disk galaxy simulations, notwithstanding an unusual thickness along the rotation axis (this strengthens confidence in disk galaxy simulations); (3) many elliptical galaxies must be prolate objects rotating about a short axis and seen in projection; and (4) collapse models of galaxy formation lead to strongly anisotropic velocity dispersions, which are not in agreement with observation.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Rotation histories of the natural satellites

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    1977-01-01

    Recent advances in the theory of rotation are combined with traditional approaches to study the rotational evolution of the 33 known natural satellites. A calculation similar to that reported by Burns and Safronov (1973) is applied to each satellite to obtain the characteristic time of decay of any wobble motion to smooth rotation about the principal axis of maximum moment of inertia. Stability criteria and capture probabilities are calculated for the 3/2 spin resonance. Results show that only the regular satellites and Iapetus, Hyperion, Triton, and the moon are tidally evolved. Of these, 13 have confirmed synchronous rotation periods; capture probabilities into the 3/2 resonance indicate that none of the remaining 10 should be captured in nonsynchronous, commensurate spin states. For the most part, the irregular satellites retain their original spins except for a relaxation to principal axis rotation. Tidal evolution of the obliquities of the satellites is evaluated in the framework of the generalization of Cassini's laws for the moon. Nearly resonant, forced librations in longitude of 4.8 and 0.5 deg are calculated on the basis of the observed shapes of Phobos and Deimos, respectively.

  10. Transverse pelvic rotation during quiet human stance.

    PubMed

    Günther, Michael; Otto, Daniel; Müller, Otto; Blickhan, Reinhard

    2008-04-01

    The mechanism of two-legged quiet stance is unclear. This study specifically investigated biomechanical parameters characterising the mechanisms of rotation around the longitudinal axis (parallel to gravitational acceleration, i.e. in the transverse plane parallel to the ground). Subjects (10) were examined while standing quietly on two force platforms which measured the transverse component of the ground reaction torque (GRT). In addition, right and left hip kinematics were acquired by tracking markers in the sagittal plane. The pelvic rotation in the transverse plane (pelvic angle) was then calculated from the anterior-posterior coordinates of the hip markers. We verified the hypothesis that the pelvis generally may be coupled to the ground by a rotational stiffness provided by both legs. Thus, we asked whether the transverse GRT component may be proportional to the pelvic angle. This hypothesis was rejected. However, the transverse GRT component could be identified as one rotational stabilising mechanism which drove the higher-frequency (>1 Hz) deflections of the pelvic angle back to its lower-frequency fraction. The respective stiffness coefficient between transverse GRT component and relative displacement between higher- and lower-frequency pelvic angular fraction was about 2.4 Nm/degrees. Implications for the character and the localisation of active control of body rotation around the longitudinal axis are discussed.

  11. 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.

  12. ICPP: Results from Helical Axis Stellarators

    NASA Astrophysics Data System (ADS)

    Blackwell, B. D.

    2000-10-01

    Helical axis stellarators produce magnetic surfaces of high rotational transform and moderate shear solely by means of external currents, with the promise of high β. Several machines with quite different toroidal, helical, and ``bumpy'' Fourier components of magnetic field are now operating. The H-1 Heliac (1m, 1Tesla: Canberra, Australia), an M=3, low aspect ratio flexible heliac has been operated up to 0.5 Tesla with RF heating up to Ti ~ 100eV. Confinement transitions observed in this plasma exhibit many features of improved confinement regimes in tokamaks obtained at much larger power. ECH at 28GHz is being commissioned, and results from a suite of scattering, scalar and vector tomographic and multipoint probe and optical measurements will be presented. The M=4 Flexible Heliac ``TJ-II'' (1.5m, 1.2T: CIEMAT, Madrid) has accumulated a database of ECH plasma (1T) for a variety of configurations, (iota ~ 1.3--2.24) and a comprehensive set of diagnostics. Temperatures up to 2keV were measured by Thomson scattering/ECE. Observations include stored energy dependence, evidence of internal transport barriers, ELM-like bursts of magnetic activity and E×B sheared flows near rational surfaces in the plasma boundary. A new advanced configuration, the helical-axis heliotron, ``Heliotron J'' (1.2m, 1.5T: IAE, Kyoto University), the successor to Heliotron E, uses a ``bumpy'' magnetic component to improve high-energy particle confinement and reduce neoclassical transport. A combination of toroidal and helical coils produces a range of configurations. First plasma was successfully produced on December 1999, by ECH at 53GHz(2ω_ce). Following field mapping and final installation of diagnostics, the full experiment will start July 2000. The Helically Symmetric Experiment, ``HSX'' (Univ. Wisconsin, Madison) employs computer optimized non-planar coils to exploit a quasi-symmetry that minimizes toroidal magnetic field harmonics, confirmed by recent mapping of the drift orbits

  13. Flow augmenters for vertical-axis windmills and turbines

    SciTech Connect

    Evans, F.C.

    1981-03-10

    A windmill is disclosed, the windmill including a vertical shaft mounted for rotation about its longitudinal axis, a number of blades spaced circumferentially around the longitudinal axis, and being disposed generally parallel to the axis of rotation of the vertical shaft, and supporting arms extending radially outwardly from the vertical shaft for supporting the blades. The windmill also includes a first member connected to an upper end of one of the blades and defining a first surface having a leading edge with respect to the direction of movement of the blade and a trailing edge rearward of the leading edge, the leading edge being lower than the trailing edge. The first surface also includes an inside lateral edge and an outer lateral edge spaced radially outwardly from the inside lateral edge, the inside lateral edge being higher than the outer lateral edge. A second member is connected to the lower end of the blade and defines a second surface, the second surface having a leading edge with respect to the direction of movement of the blade and a trailing surface rearward of the second surface leading edge, the second surface leading edge being higher than the trailing edge. The second surface also includes an inside lateral edge and an outer lateral edge spaced radially outwardly from the second surface inside lateral edge, the second surface inside lateral edge being lower than the second surface outside lateral edge.

  14. Fetal and Neonatal HPA Axis.

    PubMed

    Wood, Charles E; Walker, Claire-Dominique

    2015-01-01

    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.

  15. Spin axis behavior of the LAGEOS satellites

    NASA Astrophysics Data System (ADS)

    AndréS, J. I.; Noomen, R.; Bianco, G.; Currie, D. G.; Otsubo, T.

    2004-06-01

    The satellites LAGEOS-I and LAGEOS-II are essential for the scientific study of various (geo)physical phenomena, such as geocenter motion and absolute scale. The high quality of such science products strongly depends on the absolute quality of the SLR observations and that of the orbit description. Therefore all accelerations experienced by the spacecraft need to be modeled as accurately as possible, the thermal radiation forces being one of them. Traditionally, this is done by estimating so-called empirical accelerations. However, the rotational dynamics of LAGEOS-I in particular no longer allows such a simple approach: a full modeling of the spin behavior, the temperature distribution over the spacecraft surface and the resulting net force prove necessary to achieve the best results. As a first step, a new model, Lageos Spin Axis Model (LOSSAM) has been developed. It is unique in its combination of analytical theory and empirical observations. Its mathematics is taken after previous investigators, although flaws have been corrected. LOSSAM describes the full spin behavior of LOSSAM based on the following phenomena: (1) the geomagnetic field, (2) the Earth's gravity field, (3) the satellite center of pressure offset, and (4) the effective difference in reflectivity between the satellite hemispheres. Its accuracy has been demonstrated by an improvement of about a 50% in the RMS residual of the Yarkovsky-Schach effect signal (as shown by [2004]). Such a high-quality model for rotational behavior is indispensable for a proper force modeling, and hence also for the quality of typical LAGEOS science products.

  16. A spin label that binds to myosin heads in muscle fibers with its principal axis parallel to the fiber axis.

    PubMed Central

    Roopnarine, O; Thomas, D D

    1994-01-01

    We have used an indane-dione spin label (2-[-oxyl-2,2,5,5-tetramethyl-3-pyrrolin-3-yl)methenyl]in dane-1,3-dione), designated InVSL, to study the orientation of myosin heads in bundles of chemically skinned rabbit psoas muscle fibers, with electron paramagnetic resonance (EPR) spectroscopy. After reversible preblocking with 5,5'-dithiobis(2-nitro-benzoic acid) (DTNB), we were able to attach most of the spin label covalently and rigidly to either Cys 707 (SH1) or Cys 697 (SH2) on myosin heads. EPR spectra of labeled fibers contained substantial contributions from both oriented and disordered populations of spin labels. Similar spectra were obtained from fibers decorated with InVSL-labeled myosin heads (subfragment 1), indicating that virtually all the spin labels in labeled fibers are on the myosin head. We specifically labeled SH2 with InVSL after reversible preblocking of the SH1 sites with 1-fluoro-2,4-dinitrobenzene (FDNB), resulting in a spectrum that indicated only disordered spin labels. Therefore, the oriented and disordered populations correspond to labels on SH1 and SH2, respectively. The spectrum of SH2-bound labels was subtracted to produce a spectrum corresponding to SH1-bound labels, which was used for further analysis. For this corrected spectrum, the angle between the fiber axis and the principal axis of the spin label was fitted well by a Gaussian distribution centered at theta o = 11 +/- 1 degree, with a full width at half-maximum of delta theta = 15 +/- 2 degrees. The unique orientation of InVSL, with its principal axis almost parallel to the fiber axis, makes it complementary to spin labels previously studied in this system. This label can provide unambiguous information about axial rotations of myosin heads, since any axial rotation of the head must be reflected in the same axial rotation of the principal axis of the probe, thus changing the hyperfine splitting. Therefore, InVSL-labeled fibers have ideal properties needed for further exploration

  17. Computational analysis of vertical axis wind turbine arrays

    NASA Astrophysics Data System (ADS)

    Bremseth, J.; Duraisamy, K.

    2016-03-01

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Stress and the reproductive axis.

    PubMed

    Toufexis, D; Rivarola, M A; Lara, H; Viau, V

    2014-09-01

    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 example, both testosterone and oestrogen modulate the response of the HPA axis, whereas 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, as well as 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 such as oestrogen receptor (ER)α that govern sexual behaviour, and may be particularly important in determining the sexual strategies utilised 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 into the ovary, which produces a noncyclic 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 increases 5-HT1A receptor expression at postsynaptic sites. These mechanisms could explain the 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 behavioural phenotype that is largely unaffected by oestrogen, a hyporesponsive HPA axis that is hypersensitive to the modulating effects

  2. 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

  3. 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.

  4. Boundary Layer Control of Rotating Convection Systems

    NASA Astrophysics Data System (ADS)

    King, E. M.; Stellmach, S.; Noir, J.; Hansen, U.; Aurnou, J. M.

    2008-12-01

    Rotating convection is ubiquitous in the natural universe, and is likely responsible for planetary processes such magnetic field generation. Rapidly rotating convection is typically organized by the Coriolis force into tall, thin, coherent convection columns which are aligned with the axis of rotation. This organizational effect of rotation is thought to be responsible for the strength and structure of magnetic fields generated by convecting planetary interiors. As thermal forcing is increased, the relative influence of rotation weakens, and fully three-dimensional convection can exist. It has long been assumed that rotational effects will dominate convection dynamics when the ratio of buoyancy to the Coriolis force, the convective Rossby number, Roc, is less than unity. We investigate the influence of rotation on turbulent Rayleigh-Benard convection via a suite of coupled laboratory and numerical experiments over a broad parameter range: Rayleigh number, 10310; Ekman number, 10-6≤ E ≤ ∞; and Prandtl number, 1≤ Pr ≤ 100. In particular, we measure heat transfer (as characterized by the Nusselt number, Nu) as a function of the Rayleigh number for several different Ekman and Prandtl numbers. Two distinct heat transfer scaling regimes are identified: non-rotating style heat transfer, Nu ~ Ra2/7, and quasigeostrophic style heat transfer, Nu~ Ra6/5. The transition between the non-rotating regime and the rotationally dominant regime is described as a function of the Ekman number, E. We show that the regime transition depends not on the global force balance Roc, but on the relative thicknesses of the thermal and Ekman boundary layers. The transition scaling provides a predictive criterion for the applicability of convection models to natural systems such as Earth's core.

  5. 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.

  6. 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. PMID:17174031

  7. 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.

  8. 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

  9. 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.

  10. Downwind rotor horizontal axis wind turbine noise prediction

    NASA Technical Reports Server (NTRS)

    Metzger, F. B.; Klatte, R. J.

    1981-01-01

    NASA and industry are currently cooperating in the conduct of extensive experimental and analytical studies to understand and predict the noise of large, horizontal axis wind turbines. This effort consists of (1) obtaining high quality noise data under well controlled and documented test conditions, (2) establishing the annoyance criteria for impulse noise of the type generated by horizontal axis wind turbines with rotors downwind of the support tower, (3) defining the wake characteristics downwind of the axial location of the plane of rotation, (4) comparing predictions with measurements made by use of wake data, and (5) comparing predictions with annoyance criteria. The status of work by Hamilton Standard in the above areas which was done in support of the cooperative NASA and industry studies is briefly summarized.

  11. 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.

  12. Hypothalamus-Pituitary-Thyroid Axis.

    PubMed

    Ortiga-Carvalho, Tania M; Chiamolera, Maria I; Pazos-Moura, Carmen C; Wondisford, Fredic E

    2016-01-01

    The hypothalamus-pituitary-thyroid (HPT) axis determines the set point of thyroid hormone (TH) production. Hypothalamic thyrotropin-releasing hormone (TRH) stimulates the synthesis and secretion of pituitary thyrotropin (thyroid-stimulating hormone, TSH), which acts at the thyroid to stimulate all steps of TH biosynthesis and secretion. The THs thyroxine (T4) and triiodothyronine (T3) control the secretion of TRH and TSH by negative feedback to maintain physiological levels of the main hormones of the HPT axis. Reduction of circulating TH levels due to primary thyroid failure results in increased TRH and TSH production, whereas the opposite occurs when circulating THs are in excess. Other neural, humoral, and local factors modulate the HPT axis and, in specific situations, determine alterations in the physiological function of the axis. The roles of THs are vital to nervous system development, linear growth, energetic metabolism, and thermogenesis. THs also regulate the hepatic metabolism of nutrients, fluid balance and the cardiovascular system. In cells, TH actions are mediated mainly by nuclear TH receptors (210), which modify gene expression. T3 is the preferred ligand of THR, whereas T4, the serum concentration of which is 100-fold higher than that of T3, undergoes extra-thyroidal conversion to T3. This conversion is catalyzed by 5'-deiodinases (D1 and D2), which are TH-activating enzymes. T4 can also be inactivated by conversion to reverse T3, which has very low affinity for THR, by 5-deiodinase (D3). The regulation of deiodinases, particularly D2, and TH transporters at the cell membrane control T3 availability, which is fundamental for TH action. © 2016 American Physiological Society. Compr Physiol 6:1387-1428, 2016. PMID:27347897

  13. Analysis of centrifugal convection in rotating pipes

    NASA Astrophysics Data System (ADS)

    Shtern, Vladimir; Zimin, Valery; Hussain, Fazle

    2001-08-01

    New exact solutions, obtained for centrifugal convection of a compressible fluid in pipes and annular pipes, explain axially elongated counterflow and energy separation—poorly understood phenomena occurring in vortex devices, e.g., hydrocyclones and Ranque tubes. Centrifugal acceleration (which can be up to 106 times gravity in practical vortex tubes), combined with an axial gradient of temperature (even small), induces an intense flow from the cold end to the hot end along the pipe wall and a backflow near the axis. To account for large density variations in vortex devices, we use the axial temperature gradient as a small parameter instead of the Boussinesq approximation. For weak pipe rotation, the swirl is of solid-body type and solutions are compact: vz/vza=1-4y2+3y4 and (T-Tw)/(Ta-Tw)=(1-y2)3; where y=r/rw, the subscripts w and a denote values of axial velocity vz, temperature T, and radial distance r, at the wall and on the axis. The axial gradient of pressure, being proportional to 3y2-1, has opposite directions near the wall, y=1, and near the axis, y=0; this explains the counterflow. With increasing pipe rotation, the flow starts to converge to the axis. This causes important new effects: (i) the density and swirl velocity maxima occur away from the wall (vortex core formation), (ii) the temperature near the axis becomes lower than near the wall (the Ranque effect), (iii) the axial gradient of temperature drops from the wall to the axis, and (iv) the total axial heat flux (Nu) reaches its maximum Numax≈4000 and then decreases as swirl increases. These features can be exploited for the development of a micro-heat-exchanger, e.g., for cooling computer chips.

  14. 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.

  15. Angle Estimation of Simultaneous Orthogonal Rotations from 3D Gyroscope Measurements

    PubMed Central

    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. PMID:22164090

  16. Flow and heat transfer characteristics of orthogonally rotating channel

    NASA Astrophysics Data System (ADS)

    Tamura, Hiroshi; Ishigaki, Hiroshi

    1991-12-01

    Numerical analysis was conducted to predict the centripetal buoyant effect on flow and heat transfer characteristics in a channel rotating about a perpendicular axis. The conditions were assumed to be laminar, fully developed, and uniform heat flux. Calculation were conducted both for radially outward flow from the rotating axis and radially inward flow. The calculated results indicated that for radially outward flow buoyancy decreases the suction side friction and heat transfer while increasing pressure side friction and heat transfer. This trends were reversed for radially inward flow.

  17. 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.

  18. Finite element analysis and modal testing of a rotating wind turbine

    SciTech Connect

    Carne, T.G.; Lobitz, D.W.; Nord, A.R.; Watson, R.A.

    1982-05-10

    A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, has been developed to compute the mode shapes and frequencies of rotating structures. Special application of this capability has been made to Darrieus, vertical axis wind turbines. In a parallel development effort, a technique for the modal testing of a rotating vertical axis wind turbine has been established to measure modal parameters directly. Results from the predictive and experimental techniques for the modal frequencies and mode shapes are compared over a wide range of rotational speeds.

  19. Finite-element analysis and modal testing of a rotating wind turbine

    SciTech Connect

    Carne, T.G.; Lobitz, D.W.; Nord, A.R.; Watson, R.A.

    1982-10-01

    A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, has been developed to compute the mode shapes and frequencies of rotating structures. Special application of this capability has been made to Darrieus, vertical axis wind turbines. In a parallel development effort, a technique for the modal testing of a rotating vertical axis wind turbine has been established to measure modal parameters directly. Results from the predictive and experimental techniques for the modal frequencies and mode shapes are compared over a wide range of rotational speeds.

  20. 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.

  1. 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.

  2. Effect of rotational symmetry on the optical rotation of using asymmetrical nanostructures

    NASA Astrophysics Data System (ADS)

    Hor, Y. L.; Phua, W. K.; Liu, Y. J.; Wu, S.; Popp, D.; Leong, Eunice S. P.; Mok, K. L.; Teng, J. H.; Robinson, R.; Li, E. P.; Khoo, E. H.

    2013-09-01

    In this paper, we rotate an array of asymmetrical double layer of 4-strips windmill structure to investigate its effect on the chirality and sensitivity detection of biomolecular structures. The structure is made up of silver material with 300nm pitch and 10nm separation between layers. The spectrum shows two resonance modes on 600THz and 900THz with linear polarized light normally incident on the structure. We investigate the CD by rotating one of the layers with respect to the horizontal axis of the other layer by the angle θ. It is observed that the CD spectra at different angles are different. The rotation resulted in larger wavelength shift of the CD spectra. In addition, the CD also increases with the rotating angle given a larger absorption difference between the left and right handed circular polarized light.

  3. Localized waves supported by the rotating waveguide array

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Ye, Fangwei; Kartashov, Yaroslav V.; Vysloukh, Victor A.; Chen, Xianfeng

    2016-09-01

    We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around array center, since rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between centrifugal force (in terms of quasi-particle analogy) and total internal reflection at the interface of the truncated array. The degree of localization of the central and corner modes mediated by rotation increases with rotation frequency. Stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media.

  4. Non-contact measurement of rotation angle with solo camera

    NASA Astrophysics Data System (ADS)

    Gan, Xiaochuan; Sun, Anbin; Ye, Xin; Ma, Liqun

    2015-02-01

    For the purpose to measure a rotation angle around the axis of an object, a non-contact rotation angle measurement method based on solo camera was promoted. The intrinsic parameters of camera were calibrated using chessboard on principle of plane calibration theory. The translation matrix and rotation matrix between the object coordinate and the camera coordinate were calculated according to the relationship between the corners' position on object and their coordinates on image. Then the rotation angle between the measured object and the camera could be resolved from the rotation matrix. A precise angle dividing table (PADT) was chosen as the reference to verify the angle measurement error of this method. Test results indicated that the rotation angle measurement error of this method did not exceed +/- 0.01 degree.

  5. Localized waves supported by the rotating waveguide array.

    PubMed

    Zhang, Xiao; Ye, Fangwei; Kartashov, Yaroslav V; Vysloukh, Victor A; Chen, Xianfeng

    2016-09-01

    We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around an array center, since the rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between the centrifugal force and total internal reflection at the interface of the truncated array. The degree of localization of the central and corner modes mediated by the rotation increases with the rotation frequency. The stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media. PMID:27607984

  6. Localized waves supported by the rotating waveguide array.

    PubMed

    Zhang, Xiao; Ye, Fangwei; Kartashov, Yaroslav V; Vysloukh, Victor A; Chen, Xianfeng

    2016-09-01

    We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around an array center, since the rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between the centrifugal force and total internal reflection at the interface of the truncated array. The degree of localization of the central and corner modes mediated by the rotation increases with the rotation frequency. The stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media.

  7. Modal identification of a rotating-blade system

    SciTech Connect

    Carne, T.G.; Martinez, D.R.; Ibrahim, S.R.

    1983-01-01

    A new testing technique and the Ibrahim time domain (ITD) modal identification algorithm have been combined, resulting in a capability to estimate modal parameters for rotating blade systems. This capability has been evaluated on the Sandia two-meter, vertical-axis wind turbine. Variation in modal frequencies as a function of rotation speed has been experimentally determined from 0 rpm (parked) to 800 rpm. Excitation of the rotating turbine was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it rotated. The structural response was obtained by passing the signals through slip rings. Using the measured free-decay responses as input for the ITD algorithm, the modes of the rotating turbine were determined at seven rotation speeds. The measured modal parameters were compared with analytical results obtained from a finite element analysis and with experimental results obtained from a complex exponential identification algorithm.

  8. Modal identification of a rotating-blade system

    SciTech Connect

    Carne, T.G.; Martinez, D.R.; Ibrahim, S.R.

    1983-04-01

    A new testing technique and the Ibrahim time-domain (ITD) modal identification algorithm have been combined, resulting in a capability to estimate modal parameters for rotating-blade systems. This capability has been evaluated on the Sandia two-meter, vertical-axis wind turbine. Variation in modal frequencies as a function of rotation speed has been experimentally determined from 0 rpm (parked) to 800 rpm. Excitation of the rotating turbine was provided by a scheme which suddenly released a pretensioned cable, thus plucking the turbine as it rotated. The structural response was obtained by passing the signals through slip rings. Using the measured free-decay responses as input data for the ITD algorithm, the modes of the rotating turbine were determined at seven rotation speeds. The measured modal parameters were compared with analytical results obtained from a finite element analysis and with experimental results obtained from a complex exponential identification algorithm.

  9. A highly triaxial N-body system tumbling about is intermediate axis

    NASA Technical Reports Server (NTRS)

    Duncan, Martin J.; Levison, Harold F.

    1989-01-01

    The results are presented of an N-body simulation which shows that it is possible for a highly triaxial self-gravitating system in dynamical equilibrium to exhibit stable figure rotation about its intermediate axis. The system is long-lived, lasting at least 20 half-mass crossing times of the final system. The nature of the simulation is summarized.

  10. Rotational Preference in Gymnastics

    PubMed Central

    Heinen, Thomas; Jeraj, Damian; Vinken, Pia M.; Velentzas, Konstantinos

    2012-01-01

    In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast’s rotational preference. Therefore, we sought to explore relationships in gymnast’s rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362

  11. Rotational preference in gymnastics.

    PubMed

    Heinen, Thomas; Jeraj, Damian; Vinken, Pia M; Velentzas, Konstantinos

    2012-06-01

    In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast's rotational preference. Therefore, we sought to explore relationships in gymnast's rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362

  12. Rotation of methyl radicals in molecular solids.

    PubMed

    Kiljunen, Toni; Popov, Evgeny; Kunttu, Henrik; Eloranta, Jussi

    2010-04-15

    Electron spin resonance (ESR) measurements were carried out to study the rotation of methyl radicals (CH(3)) in solid carbon monoxide, carbon dioxide, and nitrogen matrices. The radicals were produced by dissociating methane by plasma bursts generated by a focused 193 nm ArF excimer laser radiation during the gas condensation on the substrate. The ESR spectra exhibit anisotropic features that persist over the temperature range examined, and in most cases this indicates a restriction of rotation about the C(2) symmetry axis. A nonrotating CH(3) was also observed in a CO(2) matrix. The intensity ratio between the symmetric (A) and antisymmetric (E) nuclear spin states was recorded as a function of temperature for each molecular matrix. The rotational energy levels are modified from their gas phase structure with increasing crystal field strength. An anomalous situation was observed where the A/E ratio extended below the high temperature limit of 1/2. PMID:20141192

  13. 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.

  14. Nonlinear dynamics of a rotating double pendulum

    NASA Astrophysics Data System (ADS)

    Maiti, Soumyabrata; Roy, Jyotirmoy; Mallik, Asok K.; Bhattacharjee, Jayanta K.

    2016-01-01

    Nonlinear dynamics of a double pendulum rotating at a constant speed about a vertical axis passing through the top hinge is investigated. Transitions of oscillations from chaotic to quasiperiodic and back to chaotic again are observed with increasing speed of rotation. With increasing speed, a pair of new stable equilibrium states, different from the normal vertical one, appear and the quasiperiodic oscillations occur. These oscillations are first centered around the origin, but with increasing rotation speed they cover the origin and the new fixed points. At a still higher speed, more than one pair of fixed points appear and the oscillation again turns chaotic. The onset of chaos is explained in terms of internal resonance. Analytical and numerical results confirm the critical values of the speed parameter at various transitions.

  15. 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.

  16. The modulation component of nystagmus during earth-horizontal rotation: relationship with gaze angle.

    PubMed

    Wall, C; Black, F O

    1984-01-01

    Periodic fluctuations in gaze angle and nystagmus slow phase velocity (SPV) were characterized using 6 normal subjects rotated at constant angular velocity about their rostral-caudal body axis with that axis in the horizontal orientation. The periodicity of the fluctuations corresponded to the angular frequency of rotation. The magnitude of the SPV fluctuations was moderately well correlated with those of the gaze fluctuations. Four vector quantities were found to characterize these data fairly completely, yet compactly.

  17. Control system for a vertical-axis windmill

    SciTech Connect

    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.

  18. Design of h-Darrieus vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Parra, Teresa; Vega, Carmen; Gallegos, A.; Uzarraga, N. C.; Castro, F.

    2015-05-01

    Numerical simulation is used to predict the performance of a Vertical Axis Wind Turbine (VAWT) H-Darrieus. The rotor consists of three straight blades with shape of aerofoil of the NACA family attached to a rotating vertical shaft. The influence of the solidity is tested to get design tendencies. The mesh has two fluid volumes: one sliding mesh for the rotor where the rotation velocity is established while the other is the environment of the rotor. Bearing in mind the overall flow is characterized by important secondary flows, the turbulence model selected was realizable k-epsilon with non-equilibrium wall functions. Conservation equations were solved with a Third-Order Muscl scheme using SIMPLE to couple pressure and velocity. During VAWT operation, the performance depends mainly on the relative motion of the rotating blade and has a fundamental period which depends both on the rate of rotation and the number of blades. The transient study is necessary to characterise the hysteresis phenomenon. Hence, more than six revolutions get the periodic behaviour. Instantaneous flows provide insight about wake structure interaction. Time averaged parameters let obtain the characteristic curves of power coefficient.

  19. 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.

  20. 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.

  1. Design, implementation, and control of a six-axis compliant stage

    NASA Astrophysics Data System (ADS)

    Hu, Kaixuan; Kim, Jung H.; Schmiedeler, James; Menq, Chia-Hsiang

    2008-02-01

    This paper presents the development of a new compact six-axis compliant stage employing piezoelectric actuators to achieve six-axis actuation with nanometer resolution. The integration of direct metrology in the object space, based on real-time visual feedback, enables high-precision motion control. In order to achieve greater motion range, the simple and compact decoupled mechanical structure utilizes two-tap displacement amplifiers for in-plane motion and semibridge amplifiers for out-of-plane motion. The kinematic analysis of the stage is presented. Laterally sampled white light interferometry was implemented to measure the out-of-plane motion of the stage, and a measurement model associated with the designed target patterns is developed to estimate the in-plane motion in real time. Together, they form a visual tracking system and are integrated with the six-axis compliant stage to realize precision six-axis real-time visual servo-control. Experimental results demonstrate that the six-axis compliant stage has the motion range of 77.42μm, 67.45μm, 24.56μm, 0.93mrad, 0.95mrad, and 3.10mrad, and the resolution of ±5nm, ±8nm, ±10nm, ±10μrad, ±10μrad, and ±20μrad for x-axis, y-axis, and z-axis translation and rotation, respectively.

  2. 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

  3. Vibration of microgravity environment for rotating fluids in high and low rotating speeds

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Time dependent evolutions of the profile of 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 the sinusoidal function vibration of gravity environment in high and low rotating cylinder speeds. The initial condition of bubble profiles was adopted from the steady-state formulations in which the computer algorithms have been developed by Hung and Leslie (1988), and Hung et al. (1988).

  4. The earth's rotation. [three dimensional rotation about its center of mass

    NASA Technical Reports Server (NTRS)

    Rochester, M. G.

    1975-01-01

    The state-of-the-art technology in the study of the three dimensional rotation of the earth about its center of mass is summarized. A survey of appropriate reference frames and problems involved in defining them is given along with an outline of the accuracy with which the earth's rotation can be measured relative to these frames. The various spectral features of changes in the axis orientation and spin rate of the solid earth and the physical mechanisms known or likely to effect and/or affect them are discussed.

  5. 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

  6. 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.)

  7. Rotator cuff problems

    MedlinePlus

    ... rotator cuff is a group of muscles and tendons that attach to the bones of the shoulder ... Rotator cuff tendinitis refers to irritation of these tendons and inflammation of the bursa (a normally smooth ...

  8. 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.

  9. Mineral lineation produced by 3-D rotation of rigid inclusions in confined viscous simple shear

    NASA Astrophysics Data System (ADS)

    Marques, Fernando O.

    2016-08-01

    The solid-state flow of rocks commonly produces a parallel arrangement of elongate minerals with their longest axes coincident with the direction of flow-a mineral lineation. However, this does not conform to Jeffery's theory of the rotation of rigid ellipsoidal inclusions (REIs) in viscous simple shear, because rigid inclusions rotate continuously with applied shear. In 2-dimensional (2-D) flow, the REI's greatest axis (e1) is already in the shear direction; therefore, the problem is to find mechanisms that can prevent the rotation of the REI about one axis, the vorticity axis. In 3-D flow, the problem is to find a mechanism that can make e1 rotate towards the shear direction, and so generate a mineral lineation by rigid rotation about two axes. 3-D analogue and numerical modelling was used to test the effects of confinement on REI rotation and, for narrow channels (shear zone thickness over inclusion's least axis, Wr < 2), the results show that: (1) the rotational behaviour deviates greatly from Jeffery's model; (2) inclusions with aspect ratio Ar (greatest over least principle axis, e1/e3) > 1 can rotate backwards from an initial orientation w e1 parallel to the shear plane, in great contrast to Jeffery's model; (3) back rotation is limited because inclusions reach a stable equilibrium orientation; (4) most importantly and, in contrast to Jeffery's model and to the 2-D simulations, in 3-D, the confined REI gradually rotated about an axis orthogonal to the shear plane towards an orientation with e1 parallel to the shear direction, thus producing a lineation parallel to the shear direction. The modelling results lead to the conclusion that confined simple shear can be responsible for the mineral alignment (lineation) observed in ductile shear zones.

  10. Using the Quaternions to Compose Rotations. Applications of Linear Algebra to Geometry. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Unit 313.

    ERIC Educational Resources Information Center

    Solomon, Frederick

    This module applies linear algebraic methods to solve the following problem: If an object in a three-dimensional coordinate system is first rotated about a given axis through the origin by a given angle, and then rotated about another axis through the origin by another angle, there is a straightforward way to calculate the combined result of the…

  11. 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…

  12. Characterization of off-axis fishbones

    NASA Astrophysics Data System (ADS)

    Heidbrink, W. W.; Austin, M. E.; Fisher, R. K.; García-Muñoz, M.; Matsunaga, G.; McKee, G. R.; Moyer, R. A.; Muscatello, C. M.; Okabayashi, M.; Pace, D. C.; Shinohara, K.; Solomon, W. M.; Strait, E. J.; Van Zeeland, M. A.; Zhu, Y. B.

    2011-08-01

    Repetitive bursting instabilities with strong frequency chirping occur in high-beta, beam-heated plasmas with safety factor q > 1 in the DIII-D tokamak. Although the mode structures differ, in many ways, the off-axis fishbones are similar to the q = 1 fishbones first observed on the Poloidal Divertor Experiment (PDX). The modes are driven by energetic trapped ions at the fast-ion precession frequency. During a burst, the frequency changes most rapidly as the mode reaches its maximum amplitude. Larger amplitude bursts have larger growth rates and frequency chirps. Unlike PDX fishbones, the decay phase is highly variable and is usually shorter than the growth phase. Also, the waveform is highly distorted by higher harmonics during the latter portion of a burst. The radial mode structure alters its shape during the burst. Like PDX fishbones, the modes expel trapped ions in a 'beacon' with a definite phase relationship relative to the mode. Seven types of loss detectors measure the beacon. The losses scale linearly with mode amplitude. The neutron rate changes most rapidly at maximum mode amplitude but, depending on the loss diagnostic, the losses often peak a few cycles later. The non-ambipolar fast-ion losses cause a sudden change in toroidal rotation frequency across the entire plasma. In addition to an overall drop, the neutron signal oscillates in response to the wave. Unlike the beacon of lost particles, which maintains a fixed phase relative to the mode, the phase of the neutron oscillations steadily increases throughout the burst, with the greatest phase slippage occurring in the highly nonlinear phase near maximum mode amplitude.

  13. 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.

  14. 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).

  15. 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

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

    PubMed

    McCall, Brian; Tkaczyk, Tomasz S

    2013-02-11

    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.

  17. 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.

  18. Automated segmentation of the human hippocampus along its longitudinal axis.

    PubMed

    Lerma-Usabiaga, Garikoitz; Iglesias, Juan Eugenio; Insausti, Ricardo; Greve, Douglas N; Paz-Alonso, Pedro M

    2016-09-01

    The human hippocampal formation is a crucial brain structure for memory and cognitive function that is closely related to other subcortical and cortical brain regions. Recent neuroimaging studies have revealed differences along the hippocampal longitudinal axis in terms of structure, connectivity, and function, stressing the importance of improving the reliability of the available segmentation methods that are typically used to divide the hippocampus into its anterior and posterior parts. However, current segmentation conventions present two main sources of variability related to manual operations intended to correct in-scanner head position across subjects and the selection of dividing planes along the longitudinal axis. Here, our aim was twofold: (1) to characterize inter- and intra-rater variability associated with these manual operations and compare manual (landmark based) and automatic (percentage based) hippocampal anterior-posterior segmentation procedures; and (2) to propose and test automated rotation methods based on approximating the hippocampal longitudinal axis to a straight line (estimated with principal component analysis, PCA) or a quadratic Bézier curve (fitted with numerical methods); as well as an automated anterior-posterior hippocampal segmentation procedure based on the percentage-based method. Our results reveal that automated rotation and segmentation procedures, used in combination or independently, minimize inconsistencies generated by the accumulation of manual operations while providing higher statistical power to detect well-known effects. A Matlab-based implementation of these procedures is made publicly available to the research community. Hum Brain Mapp 37:3353-3367, 2016. © 2016 Wiley Periodicals, Inc. PMID:27159325

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Millimetre Wave with Rotational Orbital Angular Momentum.

    PubMed

    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

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. PRIGo: a new multi-axis goniometer for macromolecular crystallography

    PubMed Central

    Waltersperger, Sandro; Olieric, Vincent; Pradervand, Claude; Glettig, Wayne; Salathe, Marco; Fuchs, Martin R.; Curtin, Adrian; Wang, Xiaoqiang; Ebner, Simon; Panepucci, Ezequiel; Weinert, Tobias; Schulze-Briese, Clemens; Wang, Meitian

    2015-01-01

    The Parallel Robotics Inspired Goniometer (PRIGo) is a novel compact and high-precision goniometer providing an alternative to (mini-)kappa, traditional three-circle goniometers and Eulerian cradles used for sample reorientation in macromolecular crystallography. Based on a combination of serial and parallel kinematics, PRIGo emulates an arc. It is mounted on an air-bearing stage for rotation around ω and consists of four linear positioners working synchronously to achieve x, y, z translations and χ rotation (0–90°), followed by a ϕ stage (0–360°) for rotation around the sample holder axis. Owing to the use of piezo linear positioners and active correction, PRIGo features spheres of confusion of <1 µm, <7 µm and <10 µm for ω, χ and ϕ, respectively, and is therefore very well suited for micro-crystallography. PRIGo enables optimal strategies for both native and experimental phasing crystallographic data collection. Herein, PRIGo hardware and software, its calibration, as well as applications in macromolecular crystallography are described. PMID:26134792

  9. A numerical method of tracing a vortical axis along local topological axis line

    NASA Astrophysics Data System (ADS)

    Nakayama, Katsuyuki; Hasegawa, Hideki

    2016-06-01

    A new numerical method is presented to trace or identify a vortical axis in flow, which is based on Galilean invariant flow topology. We focus on the local flow topology specified by the eigenvalues and eigenvectors of the velocity gradient tensor, and extract the axis component from its flow trajectory. Eigen-vortical-axis line is defined from the eigenvector of the real eigenvalue of the velocity gradient tensor where the tensor has the conjugate complex eigenvalues. This numerical method integrates the eigen-vortical-axis line and traces a vortical axis in terms of the invariant flow topology, which enables to investigate the feature of the topology-based vortical axis.

  10. 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

  11. Principles of the prolactin/vasoinhibin axis.

    PubMed

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

    2015-11-15

    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.

  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. Ground effect on the pressure distribution on an ellipsoid of rotation immersed in flow

    NASA Astrophysics Data System (ADS)

    Schmitt, Heiko; Schneider, Gert R.

    The steady three-dimensional laminar flow of an incompressible viscous fluid around an ellipsoid of rotation is investigated analytically, with a focus on the case where (1) the ellipsoid axis of rotation forms an angle (alpha) with an infinite ground plane and (2) the flow direction is parallel to the ground plane and to the vertical projection of the rotation axis on the plane. The problem formulation and the numerical solution method are outlined, and results for alpha = 10 deg are presented in graphs. It is found that, near the ground, the ellipsoid is acted on by an additional force directed toward the ground.

  14. Dynamic Interplay of Coherent Rotations and Domain Wall Motion in Faraday Rotators based on Ferromagnetic Crystals

    NASA Astrophysics Data System (ADS)

    Garzarella, Anthony; Wu, Dong; Shinn, Mannix

    Under small, externally-applied magnetic fields, the Faraday rotation in magneto-optic material containing ferromagnetic domains is driven primarily by two principal mechanisms: domain wall motion and coherent domain rotations. Domain wall motion yields a larger Faraday responsivity but is limited by magnetically induced optical incoherence and by damping effects. Coherent domain rotation yields smaller Faraday rotations, but exhibits a flatter and broader frequency response. The two mechanisms occur along orthogonal principal axes and may be probed independently. However, when probed along an oblique angle to the principal axes, the relationship between the Faraday rotation and the external field changes from linear to tensorial. Although this may lead to more complicated phenomena (e.g. a sensitivity axis that depends on RF frequency), the interplay of domain rotation and domain wall motion can be exploited to improve responsivity or bandwidth. The detailed experimental data can be understood in terms of a quantitative model for the magnitude and direction of the responsivity vector. Applications to magnetic field sensors based on arrayed bismuth doped iron garnet films will be emphasized in this presentation.

  15. 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.

  16. Rotation Rates of the Giant Planets (Invited)

    NASA Astrophysics Data System (ADS)

    Schubert, G.; Helled, R.; Anderson, J. D.

    2009-12-01

    It has been generally believed that a rotation period could be assigned to each of the giant planets. Accepted values of these periods, till now, are 9h 55m 29s, 10h 39m 22s, 17h 14m 24s, and 16h 06m 36s for Jupiter, Saturn, Uranus, and Neptune, respectively. The rotation period of Jupiter is based on the periodic variations in the planet’s kilometric radiation and magnetic field, periodicities that have been unchanged since the Voyager flybys. The association of these periodicities with Jupiter’s internal rotation period is based on the idea that the radio and magnetic phenomena are tied to the planet’s magnetic field lines anchored deep within Jupiter. The periodic variations of the Saturnian Kilometric Radiation (SKR), unlike those of Jupiter, have not been rock solid, however; the periodicity has changed from 10h 39m 22s at the time of Voyager to 10h 45m 45s at the time of Cassini. Clearly, the SKR period does not represent the internal rotation period of Saturn, and it raises the possibility that the rotation periods of the other giant planets are uncertain. In fact, we must seriously reconsider whether the interiors of the giant planets are in solid body rotation with a single period. Even for Jupiter, the 9h 55m 29s rotation period might represent only the rotation of the region in which the magnetic field is generated. The dynamo region could extend from some unknown inner radius out to about 0.9 Jovian radius. The deeper Jovian interior could be rotating with a different period. A recent attempt to model the interior of Jupiter with new equation of state data concluded that the gravitational coefficients of Jupiter could not be fit unless Jupiter’s internal rotation rate was constant on cylinders parallel to the rotation axis (Militzer, B., W.B. Hubbard, J. Vorberger, I. Tamblyn, and S.A. Bonev, A massive core in Jupiter predicted from first-principles simulations, 2008, ApJ, 688, L45-L48 [doi: 10.1086/594364]). For Saturn, two studies of the

  17. Asteroid rotation rates

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.; Harris, A. W.; Murray, C. D.

    1984-01-01

    A trend of increasing mean rotational frequency with increasing diameter is noted in asteroids with diameters greater than 120 km, irrespective of M-, S-, and C-type asteroid subset and family or nonfamily membership. This trend cannot be accounted for by observational selection. For asteroids with diameters smaller than 120 km mean rotational frequency increases with decreasing diameter, but within this group there is a subset with exceptionally long rotational periods. This marked change in the distribution at 120-km diameter could separate primordial asteroids from their collision products. It is also noted that, for asteroids of a given diameter, M asteroids rotate faster than S asteroids, which in turn rotate faster than C asteroids. For all types, family members rotate faster than nonfamily members.

  18. 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.

  19. Multiple imaging axis microscopy improves resolution for thick-sample applications

    NASA Astrophysics Data System (ADS)

    Swoger, Jim; Huisken, Jan; Stelzer, Ernst H. K.

    2003-09-01

    The multiple imaging axis microscope (MIAM) is a wide-field optical microscope that observes a sample simultaneously from multiple directions without requiring the sample to be rotated or tilted. The prototype is capable of high-resolution imaging of the interior of a 300-μm-diameter sample consisting of fluorescent microbeads suspended in an agarose gel. Compared with a single-axis system, the MIAM can achieve a reduction of the axial point-spread function elongation by a factor of 5.8 and a 3.5-fold improvement in volume resolution by simple linear image combination techniques.

  20. 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.

  1. 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. PMID:25807499

  2. 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

  3. The spatial rotator.

    PubMed

    Rasmusson, A; Hahn, U; Larsen, J O; Gundersen, H J G; Jensen, E B Vedel; Nyengaard, J R

    2013-05-01

    This paper presents a new local volume estimator, the spatial rotator, which is based on measurements on a virtual 3D probe, using computer assisted microscopy. The basic design of the probe builds upon the rotator principle which requires only a few manual intersection markings, thus making the spatial rotator fast to use. Since a 3D probe is involved, it is expected that the spatial rotator will be more efficient than the the nucleator and the planar rotator, which are based on measurements in a single plane. An extensive simulation study shows that the spatial rotator may be more efficient than the traditional local volume estimators. Furthermore, the spatial rotator can be seen as a further development of the Cavalieri estimator, which does not require randomization of sectioning or viewing direction. The tissue may thus be sectioned in any arbitrary direction, making it easy to identify the specific tissue region under study. In order to use the spatial rotator in practice, however, it is necessary to be able to identify intersection points between cell boundaries and test rays in a series of parallel focal planes, also at the peripheral parts of the cell boundaries. In cases where over- and underprojection phenomena are not negligible, they should therefore be corrected for if the spatial rotator is to be applied. If such a correction is not possible, it is needed to avoid these phenomena by using microscopy with increased resolution in the focal plane. PMID:23488880

  4. 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.

  5. 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.

  6. 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.

  7. Entropy generation of radial rotation convective channels

    NASA Astrophysics Data System (ADS)

    Alić, Fikret

    2012-03-01

    The exchange of heat between two fluids is established by radial rotating pipe or a channel. The hotter fluid flows through the pipe, while the cold fluid is ambient air. Total length of pipe is made up of multiple sections of different shape and position in relation to the common axis of rotation. In such heat exchanger the hydraulic and thermal irreversibility of the hotter and colder fluid occur. Therefore, the total entropy generated within the radial rotating pipe consists of the total entropy of hotter and colder fluid, taking into account all the hydraulic and thermal irreversibility of both fluids. Finding a mathematical model of the total generated entropy is based on coupled mathematical expressions that combine hydraulic and thermal effects of both fluids with the complex geometry of the radial rotating pipe. Mathematical model follows the each section of the pipe and establishes the function between the sections, so the total generated entropy is different from section to section of the pipe. In one section of the pipe thermal irreversibility may dominate over the hydraulic irreversibility, while in another section of the pipe the situation may be reverse. In this paper, continuous analytic functions that connect sections of pipe in geometric meaning are associated with functions that describe the thermo-hydraulic effects of hotter and colder fluid. In this way, the total generated entropy of the radial rotating pipe is a continuous analytic function of any complex geometry of the rotating pipe. The above method of establishing a relationship between the continuous function of entropy with the complex geometry of the rotating pipe enables indirect monitoring of unnecessary hydraulic and thermal losses of both fluids. Therefore, continuous analytic functions of generated entropy enable analysis of hydraulic and thermal irreversibility of individual sections of pipe, as well as the possibility of improving the thermal-hydraulic performance of the rotating

  8. 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.

  9. Image data rate converter having a drum with a fixed head and a rotatable head

    NASA Technical Reports Server (NTRS)

    Billingsley, F. C. (Inventor)

    1973-01-01

    A data-rate converter is disclosed comprising a rotatable data-storing drum with at least one fixed read/record head and a rotatable read/record head. The latter is rotatable in a circular path about the drum axis of rotation. The drum is positionable in any one of a plurality of axial positions with respect to the heads, so that at least one drum track is aligned with the fixed head in one drum position and with the rotatable head in another drum position. When a track is aligned with the fixed head, data may be recorded therin or read out therefrom at a rate which is a function of drum rotation, while when aligned with the rotatable head, data may be recorded or read out at a rate which is a function of the rates and directions of rotation of both the drum and the head.

  10. Concentrating solar cookers with eccentric axis

    SciTech Connect

    Wang Xiping; Sha Yong Ling; Hou Shugin; Liu Zude

    1992-12-31

    This paper describes the design, development and use of a concentrating solar cooker with eccentric axis in China. For the same power, the older circular parabolic cookers are large in volume and less convenient to operate than the cooker with eccentric axis. Calculations are presented for the design of the cooker and for obtaining an accurate test of its efficiency.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Optical design of a rotating eyepiece telescope

    NASA Astrophysics Data System (ADS)

    Siddique, M.; Nasim, F.; Khan, A. N.; Gul, A.

    2016-08-01

    Flexible eyepiece telescope has been designed and verified. The rotating eyepiece of telescope will facilitate viewing of objects in a remote or out of sight target. Eyepiece arm of telescope can be rotated upto 360o keeping objective and reticule unchanged and ensuring zero deviation in reticule inclination. Main application of this scope is off axis viewing of objects. Image inversion has been carried out by using pair of mirrors and length of telescope is controlled by using relay lenses. The optical design, simulation and image analysis has been carried out by using ZEMAX®. Magnification of telescope is between 10∼⃒12 times with FOV of 60. Experiment has been carried out using uncoated Edmund Optics and optical tool box of Micro Series Kit, NEWPORT.

  16. Bone anatomy and rotational alignment in total knee arthroplasty.

    PubMed

    Uehara, K; Kadoya, Y; Kobayashi, A; Ohashi, H; Yamano, Y

    2002-09-01

    The purpose of the current study was to investigate the bone anatomy in determining the rotational alignment in total knee arthroplasty using computed tomography. Axial images of 109 knees in 83 patients with varus osteoarthritis who had total knee arthroplasty were analyzed. On the images of the distal femur and the proximal tibia, a baseline for the anteroposterior axis of each component was drawn based on the epicondylar axis for the femur and the medial (1/3) of the tibial tuberosity for the tibia. The angle between these two lines was analyzed as the rotational mismatch between the components when they were aligned to the anatomic landmarks of each bone. Fifty-four knees (49.5%) had an angle of 5 degrees or greater and 13 knees (11.9%) had an angle of 10 degrees or greater. There was a tendency to align the tibial component in external rotation relative to the femoral component. The results indicated that the landmarks of each bone were the intrinsic cause of the rotational mismatch in knees with varus osteoarthritis. Surgeons doing total knee arthroplasties should be aware of this and check the rotational mismatch between the components. When it is present, the tibial component should be realigned to match the femoral component rotation to minimize problems caused by the mismatch.

  17. Probable Rotation States of Rocket Bodies in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Ojakangas, G.; Anz-Meador, P.; Cowardin, H.

    2012-09-01

    In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies (RBs). However, rotational dynamics is non-intuitive and misconceptions are common. Determinations of rotation and precession rates from light curves have been published that are inconsistent with the theory presented here. In a state of free precession, the total angular momentum of the object is constant, while kinetic energy decreases due to internal friction, approaching rotation about the axis of maximum inertia. For solid internal friction the timescale is hundreds to thousands of years for quality factors of ~100 and assuming metallic rigidities, but for friction in partially-filled liquid fuel tanks we predict that the preferred rotational state is approached rapidly, within days to months. However, history has shown that theoretical predictions of the timescale have been notoriously inaccurate. In free precession, the 3-1-3 Euler angle rates dphi/dt (precession rate of long axis about fixed angular momentum with cone angle theta) and dpsi/dt (roll rate around long axis) have comparable magnitudes until very close to theta=pi/2, so that otherwise the true rotation period is not simply twice the primary light curve period. Furthermore dtheta/dt, nonzero due to friction, becomes asymptotically smaller as theta=pi/2 is approached, so that theta can linger within several degrees of flat spin for a relatively long time. Such a condition is likely common, and cannot be distinguished from the wobble of a cylinder with a skewed inertia tensor unless the RB has non-axisymmetric reflectivity characteristics. For an RB of known dimensions, a given value of theta fixes the relative values of dpsi/dt and dphi/dt. In forced precession, the angular momentum precesses about a symmetry axis defined by the relevant torque. However, in LEO, only gravity gradient and magnetic eddy current torques are dominant, and these

  18. 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.

  19. Differential Rotation in Solar-like Stars from Global Simulations

    NASA Astrophysics Data System (ADS)

    Guerrero, G.; Smolarkiewicz, P. K.; Kosovichev, A. G.; Mansour, N. N.

    2013-12-01

    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.

  20. Flow through rotating rectangular ducts

    NASA Astrophysics Data System (ADS)

    Nandakumar, K.; Raszillier, H.; Durst, F.

    1991-05-01

    The bifurcation structure of two-dimensional, pressure-driven flows through a rectangular duct that is rotating about an axis perpendicular to its own is examined at a fixed Ekman number (Ek=ν/b2Ω) of 0.01. The solution structure for flow through a square duct (aspect ratio γ=1) is determined for Rossby numbers (Ro=U/bΩ) in the range of 0-5 using a computational scheme based on the arclength continuation method. The structure is much more complicated than reported earlier by Kheshgi and Scriven [Phys. Fluids 28, 2968 (1985)]. The primary branch with two limit points in Rossby number and a hysteresis behavior between the two- and four-cell flow structure that was computed by Kheshgi and Scriven is confirmed. An additional symmetric solution branch, which is disconnected from the primary branch (or rather connected via an asymmetric solution branch), is found. This has a two-cell flow structure at one end, a four-cell flow structure at the other and three limit points are located on the path. Two asymmetric solution branches emanating from symmetry breaking bifurcation points are also found for a square duct. Thus even within a Rossby number range of 0-5 a much richer solutions structure is found with up to five solutions at Ro=5. An eigenvalue calculation indicates that all two-dimensional solutions develop some form of unstable mode by the time Ro is increased to 5.0. In particular, the four-cell solution becomes unstable to asymmetric perturbations as found in a related problem of flow through a curved duct. The paths of the singular points are tracked with respect to variation in the aspect ratio using the fold following algorithm. A transcritical point is found at an aspect ratio of 0.815 and below which the four-cell solution is no longer on the primary branch. When the channel cross section is tilted even slightly (1°) with respect to the axis of rotation, the bifurcation points unfold and the two-cell solution evolves smoothly as Rossby number is

  1. Modeling rapidly rotating stars

    NASA Astrophysics Data System (ADS)

    Rieutord, M.

    2006-06-01

    We review the quest of modeling rapidly rotating stars during the past 40 years and detail the challenges to be taken up by models facing new data from interferometry, seismology, spectroscopy... We then present the progress of the ESTER project aimed at giving a physically self-consistent model for the structure and evolution of rapidly rotating stars.

  2. 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)

  3. CONTROL ROD ROTATING MECHANISM

    DOEpatents

    Baumgarten, A.; Karalis, A.J.

    1961-11-28

    A threaded rotatable shaft is provided which rotates in response to linear movement of a nut, the shaft being surrounded by a pair of bellows members connected to either side of the nut to effectively seal the reactor from leakage and also to store up energy to shut down the reactor in the event of a power failure. (AEC)

  4. Serious rotator cuff injuries.

    PubMed

    Jobe, F W

    1983-07-01

    Usually, serious rotator cuff injuries can be operated upon and a high level of performance can be achieved afer surgery. This is not so for the substantial tears seen in baseball pitchers. However, a damaged rotator cuff can be rehabilitated and can recover from the threatened tear without surgery if detected early enough and given the proper treatment.

  5. 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.

  6. The rotational spectrum of diethyl ketone.

    PubMed

    Nguyen, Ha Vinh Lam; Stahl, Wolfgang

    2011-07-11

    We report on the rotational spectrum of diethyl ketone, C(2)H(5)-C(=O)-C(2)H(5), as observed by Fourier transform microwave spectroscopy under pulsed molecular beam conditions. Almost all lines were split into narrow quartets in a range from 10 kHz up to 2 MHz, arising from the hindered rotation of the two equivalent terminal methyl groups. In a global analysis using the xiam code, which is based on the rho axis method, three rotational constants, five quartic centrifugal distortion constants, the torsional barrier of the terminal methyl groups, and the angles between the principal inertial axes and the internal rotor axes were determined. The methyl torsional barrier was found to be 771.93(27) cm(-1). In total, 199 lines were fitted to a standard deviation of 3.5 kHz. The experimental work was supplemented by quantum chemical calculations. Two-dimensional potential energy surfaces describing the rotation of both ethyl groups against the C=O frame were calculated with the MP2 method as well as the DFT method using the 6-311++G(d,p) basis set and the B3LYP functional, respectively. Combining the experimental and theoretical results, an effective structure with C(2v) symmetry was deduced for the diethyl ketone molecule. Moreover, the torsional barrier of the methyl groups was determined by ab initio methods.

  7. Rotational motion of Foton M-4

    NASA Astrophysics Data System (ADS)

    Abrashkin, V. I.; Voronov, K. E.; Piyakov, I. V.; Puzin, Yu. Ya.; Sazonov, V. V.; Semkin, N. D.; Chebukov, S. Yu.

    2016-07-01

    The actual controlled rotational motion of the Foton M-4 satellite is reconstructed for the mode of single-axis solar orientation. The reconstruction was carried out using data of onboard measurements of vectors of angular velocity and the strength of the Earth's magnetic field. The reconstruction method is based on the reconstruction of the kinematic equations of the rotational motion of a solid body. According to the method, measurement data of both types collected at a certain time interval are processed together. Measurements of the angular velocity are interpolated by piecewise-linear functions, which are substituted in kinematic differential equations for a quaternion that defines the transition from the satellite instrument coordinate system to the inertial coordinate system. The obtained equations represent the kinematic model of the satellite rotational motion. A solution of these equations that approximates the actual motion is derived from the condition of the best (in the sense of the least squares method) match between the measurement data of the strength vector of the Earth's magnetic field and its calculated values. The described method makes it possible to reconstruct the actual rotational satellite motion using one solution of kinematic equations over time intervals longer than 10 h. The found reconstructions have been used to calculate the residual microaccelerations.

  8. Enclosure rotation on the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Howard, James; Meeks, Robert; Ashby, David; Davison, Warren; Wiese, James; Urban, Jeff; Hansen, Rick; Schuh, Jared

    2012-09-01

    After several years of operation the enclosure rotation system of the LBT is exhibiting wear and other performance issues that may impact operations. This paper reviews the system design and assumptions used, describes the current performance and observed symptoms, and discusses recent improvements made to improve performance and reliability. The rotating enclosure of the LBT is a 2200 ton structure riding on four bogies with a total of 20 wheels. Identified deficiencies include wheel bearing capacities, bogie misalignment, and rail loading. These are partially due to excess enclosure weight, which was supposed to be 1600 tons, but also due to design errors. The most serious problem was the failure of several wheel bearings. The bearings were not designed for field serviceability, so a crash program began to determine how to replace them. This got us back on sky quickly, but a review of the engineering calculations identified an error which led to the use of undersized bearings. A method of installing a larger bearing was found, and these have been installed. One set of bogie wheels are misaligned so severely the structure makes loud popping and banging noises when the direction of building rotation changes. The bogie needs to be rotated about its vertical axis, but there was no provision in the design for this. The circular rail the bogies roll on is wearing faster than expected. The rails are extremely difficult to replace, so the short term plan is to study the problem.

  9. 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.

  10. 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.

  11. 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.

  12. 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. PMID:24978243

  13. 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.

  14. Development of a micro-CMM with five-axis scanning touch probe

    NASA Astrophysics Data System (ADS)

    Chu, Chih-Liang; Chen, Hung-Chi

    2016-01-01

    The purpose of this study is to develop with low cost, high precision, low contact force micro-CMM that has fiveaxis scanning touch probe. In this study, the measurement performance of the proposed system is enhanced through the use of a rigid aluminum double-arch-bridge structure to support the five-axis scanning touch probe. Furthermore, the reliability of the scanning probe mechanism of three degrees of freedom was analyzed and validated. in addition two axis (A-axis and C-axis) was added on the scanning probe. This design can be achieved independent of measurement, and minimize the dynamic error. In terms of software, a PC-Based controller was integrates five-axis motion systems with the measurement system through a five-axis control card and a data acquisition card. It also completed the functional modules of Set, Manual and Measurement. In the measurement system, we used our own developed coordinate measurement software, with the XYZ platforms system, rotating mechanism and scanning probe to achieve complex surface measurements. The micro-CMM has a working volume the micro-CMM has a working volume of 80×80×40 mm3 , and the overall dimensions is 486 × 486 × 448 mm.

  15. 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.

  16. Numerical modeling and preliminary validation of drag-based vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Krysiński, Tomasz; Buliński, Zbigniew; Nowak, Andrzej J.

    2015-03-01

    The main purpose of this article is to verify and validate the mathematical description of the airflow around a wind turbine with vertical axis of rotation, which could be considered as representative for this type of devices. Mathematical modeling of the airflow around wind turbines in particular those with the vertical axis is a problematic matter due to the complex nature of this highly swirled flow. Moreover, it is turbulent flow accompanied by a rotation of the rotor and the dynamic boundary layer separation. In such conditions, the key aspects of the mathematical model are accurate turbulence description, definition of circular motion as well as accompanying effects like centrifugal force or the Coriolis force and parameters of spatial and temporal discretization. The paper presents the impact of the different simulation parameters on the obtained results of the wind turbine simulation. Analysed models have been validated against experimental data published in the literature.

  17. Chaotic Rotation of Nix and Hydra

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.

    2014-05-01

    Disk-integrated photometry of Hydra and Nix from HST during 2010-2012 show large variations, which can be attributed to a combination of the phase function and the rotational light curves of the moons. After dividing out a model phase curve, variations by more than a factor of two remain, indicating that both Nix and Hydra are distinctly irregular in shape. Unexpectedly, Nix and Hydra's variations show no correlation with orbital longitude, as one would expect for bodies in synchronous rotation. In fact, Fourier analysis of the measurements does not reveal any fixed rotation periods compatible with the data. Compounding the mystery, Nix increased in absolute brightness by about 30% between 2010 and 2012, whereas Hydra was stable.I have developed a numeric integrator that tracks the position, velocity, orientation and rotation state of a moon as it orbits the Pluto-Charon "binary planet". The moons are represented by triaxial ellipsoids with arbitrary axial ratios. Pluto and Charon follow circular orbits about their common barycenter. I have run simulations for periods of up to 1000 years and for a variety of axial ratios and starting conditions. If an object is started in synchronous rotation with its long axis pointed toward the system barycenter, then it remains synchronously locked for the duration of the integrations. However, other initial conditions commonly lead to chaotic rotation, with Lyupanov times as brief as 30 days. Moons will sometimes temporarily lock into a nearly fixed rotation state, but commonly break out again within ~ 500 days. Depending on the axial ratios, polar flips are also commonly observed; this polar wander provides a plausible explanation for the year-by-year change in the observed brightness of Nix.Chaotic rotation is rare in the solar system, having previously been noted only for Hyperion and possibly Nereid. However, both photometry and dynamical simulations support the notion that chaotic rotation is a natural state for

  18. "Axis of Universe" Not Seen in Data, Astronomers Say

    NASA Astrophysics Data System (ADS)

    1997-04-01

    A claim that the universe has a preferred direction is not supported by recent observational evidence, according to three astronomers who analyzed data from the Very Large Array (VLA) radio telescope in New Mexico and the W.M. Keck Telescope in Hawaii. John Wardle of Brandeis University, Rick Perley of the National Radio Astronomy Observatory, and Marshall Cohen of the California Institute of Technology responded to an article in the April 21 issue of Physical Review Letters, in which Borge Nodland of the University of Rochester and John Ralston of the University of Kansas claimed to have found that the universe has a distinct axis that affects electromagnetic radiation (light, radio waves, etc.). Nodland and Ralston said that their analysis of previous radio observations of 160 galaxies, made in the 1970s and 1980s, showed that radiation coming from objects had its direction of polarization rotated by different amounts, depending on the direction of the galaxies. The amount of polarization rotation, they said, increases with the distance of the galaxies, and depends on direction, indicating that the universe has an axis along which more rotation occurs. Wardle, Perley and Cohen say that recent, high-quality observations with the VLA and the 10-meter W.M. Keck telescope show "that the radio and optical data directly refute" the contention of Nodland and Ralston. The more-recent data, consisting of polarization images of galaxies and quasars at a variety of distances and in different directions, simply do not show any evidence for Nodland and Ralston's "cosmic corkscrew" effect, the researchers say. Wardle, Perley and Cohen have submitted their results to Physical Review Letters. Galaxies and quasars, and the "jets" of subatomic particles ejected at great speeds by some of these objects, have definite patterns of polarized emission of light and radio waves. These patterns are well-known and established. If the polarization of their light were rotated by some

  19. Laboratory and field testing of commercial rotational seismometers

    USGS Publications Warehouse

    Nigbor, R.L.; Evans, J.R.; Hutt, C.R.

    2009-01-01

    There are a small number of commercially available sensors to measure rotational motion in the frequency and amplitude ranges appropriate for earthquake motions on the ground and in structures. However, the performance of these rotational seismometers has not been rigorously and independently tested and characterized for earthquake monitoring purposes as is done for translational strong- and weak-motion seismometers. Quantities such as sensitivity, frequency response, resolution, and linearity are needed for the understanding of recorded rotational data. To address this need, we, with assistance from colleagues in the United States and Taiwan, have been developing performance test methodologies and equipment for rotational seismometers. In this article the performance testing methodologies are applied to samples of a commonly used commercial rotational seismometer, the eentec model R-1. Several examples were obtained for various test sequences in 2006, 2007, and 2008. Performance testing of these sensors consisted of measuring: (1) sensitivity and frequency response; (2) clip level; (3) self noise and resolution; and (4) cross-axis sensitivity, both rotational and translational. These sensor-specific results will assist in understanding the performance envelope of the R-1 rotational seismometer, and the test methodologies can be applied to other rotational seismometers.

  20. Off-axis reflective optical apparatus

    NASA Technical Reports Server (NTRS)

    Ames, Lawrence L. (Inventor); Leary, David F. (Inventor); Mammini, Paul V. (Inventor)

    2005-01-01

    Embodiments of the present invention are directed to a simple apparatus and a convenient and accurate method of mounting the components to form an off-axis reflective optical apparatus such as a collimator. In one embodiment, an off-axis reflective optical apparatus comprises a mounting block having a ferrule holder support surface and an off-axis reflector support surface which is generally perpendicular to the ferrule holder support surface. An optical reflector is mounted on the off-axis reflector support surface and has a reflected beam centerline. The optical reflector has a conic reflective surface and a conic center. A ferrule holder is mounted on the ferrule holder support surface. The ferrule holder provides a ferrule for coupling to an optical fiber and orienting a fiber tip of the optical fiber along a fiber axis toward the optical reflector. The fiber axis is nonparallel to the reflected beam centerline. Prior to mounting the optical reflector to the off-axis reflector support surface and prior to mounting the ferrule holder to the ferrule holder support surface, the optical reflector is movable on the off-axis reflector surface and the ferrule holder is movable on the ferrule holder support surface to align the conic center of the optical reflector with respect to the fiber tip of the optical fiber, and the apparatus has at least one of the following features: (1) the optical reflector is movable on the off-axis reflector support surface to adjust a focus of the fiber tip with respect to the optical reflector, and (2) the ferrule holder is movable on the ferrule holder support surface to adjust the focus of the fiber tip with respect to the optical reflector.

  1. 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.

  2. Ligament length patterns, strength, and rotational axes of the knee joint.

    PubMed

    Trent, P S; Walker, P S; Wolf, B

    1976-06-01

    Using intact fresh specimens, the cruciate ligament lengths for positions of flexion and internal-external rotation were computed using a non-invasive technique; using photographic methods, the centers of transverse rotation on the tibia and the direction of the flexion axis were also obtained. The anterior cruciate was found to be particularly effective in restraining internal tibial rotation; the ability of the posterior cruciate to restrain external rotation, however, depended strongly on the transverse axis location. Ligament length changes during flexion were found to be small in the absence of rotary torque and anteroposterior forces. The average internal rotation occurring during flexion was 37 degrees, half of which took place during the first 15 degrees of flexion. Ultimate rupture strengths of approximately 60 kh for the cruciates were measured, with stiffnesses of 16 kg/mm.

  3. The wake of a single vertical axis wind turbine

    NASA Astrophysics Data System (ADS)

    Barsky, Danielle A.; Leftwich, Megan C.

    2013-11-01

    The purpose of this study is to measure the wake of a Windspire vertical axis wind turbine (VAWT). In recent years, research on VAWTs has increased due to various potential advantages over the more common horizontal axis wind turbines (HAWTs). Unlike very large HAWTs, moderately sized-and virtually silent-VAWTs can be placed in urban and suburban regions where land space is limited. To date, many VAWT studies have assumed that the turbine has the same aerodynamic structure as a spinning cylinder despite a significant increase in geometric complexity. This experiment attempts to understand the fundamental wake structure of a single VAWT (and compare it to the wake structure of a spinning cylinder). In this experiment, a scaled-down VAWT is placed inside a wind tunnel under a controlled laboratory setting. A motor rotates the scale model at a constant angular speed. Stereo particle image velocimetry (PIV) is used to visualize the wake of the turbine and image processing techniques are used to quantify the velocity and vorticity of the wake.

  4. 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.

  5. 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.

  6. 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.

  7. Ultra-high-vacuum double-axis goniometer for use with an electron spectrometer

    SciTech Connect

    Shleifer, M.; Williams, G.P.

    1981-01-01

    A double-axis goniometer designed for moving and indexing an electon spectrometer for angle-resolved photoemission studies is described. A feature of the design is that the two rotations operate independently and either can be carried out with the analyzer at any position. The goniometer is designed to be installed in a 14'' spool piece which makes it possible to add it to an existing 14'' uhv system.

  8. ROTATING GLOBULAR CLUSTERS

    SciTech Connect

    Bianchini, P.; Varri, A. L.; Bertin, G.; Zocchi, A.

    2013-07-20

    Internal rotation is thought to play a major role in the dynamics of some globular clusters. However, in only a few cases has internal rotation been studied by the quantitative application of realistic and physically justified global models. Here, we present a dynamical analysis of the photometry and three-dimensional kinematics of {omega} Cen, 47 Tuc, and M15, by means of a recently introduced family of self-consistent axisymmetric rotating models. The three clusters, characterized by different relaxation conditions, show evidence of differential rotation and deviations from sphericity. The combination of line-of-sight velocities and proper motions allows us to determine their internal dynamics, predict their morphology, and estimate their dynamical distance. The well-relaxed cluster 47 Tuc is interpreted very well by our model; internal rotation is found to explain the observed morphology. For M15, we provide a global model in good agreement with the data, including the central behavior of the rotation profile and the shape of the ellipticity profile. For the partially relaxed cluster {omega} Cen, the selected model reproduces the complex three-dimensional kinematics; in particular, the observed anisotropy profile, characterized by a transition from isotropy to weakly radial anisotropy and then to tangential anisotropy in the outer parts. The discrepancy found for the steep central gradient in the observed line-of-sight velocity dispersion profile and for the ellipticity profile is ascribed to the condition of only partial relaxation of this cluster and the interplay between rotation and radial anisotropy.

  9. 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.

  10. 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.

  11. Acoustic rotation control

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Croonquist, A. P.; Wang, T. G. (Inventor)

    1983-01-01

    A system is described for acoustically controlled rotation of a levitated object, which avoids deformation of a levitated liquid object. Acoustic waves of the same wavelength are directed along perpendicular directions across the object, and with the relative phases of the acoustic waves repeatedly switched so that one wave alternately leads and lags the other by 90 deg. The amount of torque for rotating the object, and the direction of rotation, are controlled by controlling the proportion of time one wave leads the other and selecting which wave leads the other most of the time.

  12. 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.

  13. 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

  14. 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.

  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. 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.

  17. 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.

  18. Two-dimensional discrete solitons in rotating lattices

    SciTech Connect

    Cuevas, Jesus; Kevrekidis, P. G.

    2007-10-15

    We introduce a two-dimensional discrete nonlinear Schroedinger (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}{ne}0.

  19. 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.

  20. Joint representation of translational and rotational components of optic flow in parietal cortex.

    PubMed

    Sunkara, Adhira; DeAngelis, Gregory C; Angelaki, Dora E

    2016-05-01

    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. 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.

  2. 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.

  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. 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)

  6. 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.

  7. 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.

  8. Robot Grasps Rotating Object

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H.; Tso, Kam S.; Litwin, Todd E.; Hayati, Samad A.; Bon, Bruce B.

    1991-01-01

    Experimental robotic system semiautomatically grasps rotating object, stops rotation, and pulls object to rest in fixture. Based on combination of advanced techniques for sensing and control, constructed to test concepts for robotic recapture of spinning artificial satellites. Potential terrestrial applications for technology developed with help of system includes tracking and grasping of industrial parts on conveyor belts, tracking of vehicles and animals, and soft grasping of moving objects in general.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Rotation sensing using a K-Rb-21Ne comagnetometer

    NASA Astrophysics Data System (ADS)

    Li, Rujie; Fan, Wenfeng; Jiang, Liwei; Duan, Lihong; Quan, Wei; Fang, Jiancheng

    2016-09-01

    We report on the Earth's rotation measurement using a K-Rb-21Ne comagnetometer. The steady-state responses of the nuclear- and electronic-spin polarizations therein have been shown. The light shift arising from the circularly polarized pump laser beam enables the comagnetometer to sense dual-axis rotations. This feasibility has been emphasized and verified by numerical simulation. We believe that this sensor could be used in any application requiring compact size, low cost, and high-precision inertial navigation.

  15. Coulomb motor by rotation of spherical conductors via the electrostatic force

    NASA Astrophysics Data System (ADS)

    Wistrom, Anders O.; Khachatourian, Armik V. M.

    2002-04-01

    Three spherical conductors fixed in space and held at constant potential produces a rotational force that causes the conductors to rotate about their axis. The motor is described by an expression for the moment of force given by Coulomb's law complemented by Gauss' law of the electric potential. The observed rotation is likely to be general and apply to machines of all size scales where the electrostatic force is the dominant operative force. This would include systems ranging in size from molecular to macroscopic and be useful for devices that require rotational motion.

  16. Low-loss ultrabroadband 90 degree optical rotator with collinear input and output beams.

    PubMed

    Appel, Roland K; Dyer, Chris D

    2002-04-01

    An achromatic device to rotate optical polarization by 90 degrees is described. This is based on a series of reflecting surfaces that rotates incoming light about the optical axis and translates it such that the exiting light is collinear. Polarization rotation is achieved by rotation of the optical beam, as opposed to the more common approach of phase retardation by use of birefringent elements. For broadband operation from the UV to the near infrared, the device was constructed by use of total internal reflection in three fused-silica glass components. Losses are minimized with interstitial surfaces designed to be angled close to Brewster's angle. PMID:11936786

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Neogene rotations in the Northeastern Tibetan Plateau: a synthesis of paleomagnetic studies

    NASA Astrophysics Data System (ADS)

    Yan, M.; Fang, X.; Song, C.; Zhang, W.

    2013-12-01

    Paleomagnetism can quantitative determine tectonic rotations around a vertical axis and test geodynamic models concerning the kinematics of the India-Asia collision. However, so far paleomagnetic studies in the northeastern (NE) Tibetan Plateau are still difficult to relate tectonic rotations to regional geodynamics, due to poor age control and some discordant paleomagnetic results on the studied rocks. Recent three magnetostratigraphic based rotation studies around the NE Tibetan Plateau have successfully revealed rotation variations through time, all indicating the existences of multiple rotation patterns during the late Neogene. Given recent large numbers of magnetostratigraphic studies and the possible existence of multiple changes in the sense and magnitude of rotations, the averaging of which possibly have resulted in the discordant paleomagnetic rotations, to better understand the Neogene rotations of the NE Tibetan Plateau, we report here new rotation studies through synthesizing available well dated magnetostratigraphic results of the region. A total of eight basin magnetostratigraphic results are utilized. These are the Kunlun, Qaidam, Jiuquan, Chaka, Guide, Linxia, Tianshui and Liupanshan basins. The analyses of paleomagnetic declination variations through time of these basins indicate that significant rotations have occurred around the NE Tibetan Plateau: although rotations close to the major faults are complicated, (1) within the NE Tibetan Plateau, it indicates an overall pattern of insignificant rotations before 11 Ma, significant clockwise rotations since ~11-8 Ma, with accelerated rotations or switch of rotation patterns since ~5-3 Ma; and the magnitude of clockwise rotations decreases from the west (Qaidam and Guide Basins) of ~30 degree to the east (Linxia and Tianshui Basins) of ~10 degree; (2) outside of the plateau, it in general shows a trend of clockwise rotations before 11 Ma, and significant counterclockwise rotations after that.

  2. Concept and realization of the novel rotating condenser-monochromator at the Göttingen TXM at BESSY II

    NASA Astrophysics Data System (ADS)

    Niemann, B.; Guttmann, P.; Rehbein, S.; Knöchel, C.

    2003-03-01

    The new transmission X-ray microscope (TXM) at BESSY II is the first X-ray microscope working with a rotating condenser-monochromator (RK) for the object illumination [1]. This condenser concept uses a linear monochromator with an off-axis transmission zone plate (OTZ) followed by a pair of rotating mirrors. Details of the design and characteristics are shown.

  3. Joint Evolution of Spinning Supermassive Black Holes and Rotating Nuclei

    NASA Astrophysics Data System (ADS)

    Merritt, David; Vasiliev, Eugene

    2015-01-01

    A rotating supermassive black hole (SBH) interacts with stars in a galactic nucleus via torques due to dragging of inertial frames. If the stars orbit preferentially about an axis that is misaligned with the SBH's spin, the SBH will experience a net torque and its spin vector will precess; individual stellar orbits also precess about the instantaneous SBH spin vector, although at different rates depending on their orbital elements. Solution of the coupled, post-Newtonian equations describing this interaction reveals two evolutionary modes: sustained precession of the SBH; and damped precession, leading to alignment of the SBH spin with the nuclear angular momentum. Beyond a certain radius, stars interact gravitationally with each other in a time shorter than the Lense-Thirring time. Long-term evolution in this case is well described as uniform precession of the SBH about the cluster's rotational axis, with a stochastic contribution due to star-star interactions.

  4. Flow Behavior Around Coupled, Rotating Turbines in Steady Flow

    NASA Astrophysics Data System (ADS)

    Fu, Matthew; Dabiri, John

    2012-11-01

    Counter-rotating vertical axis turbines (VATs) have been shown to yield increased power density in wind farms as compared to typical horizontal axis wind turbine (HAWT) farms. However, the governing physical mechanisms remain poorly understood. Scale model experiments in a free-surface water tunnel were conducted to characterize the effect of parameters such as turbine separation, tip speed ratio, and flow speed on the downstream flow field and the resulting vortex shedding from VATs. The flow field was visualized using particle image velocimetry (PIV) and planar laser induced fluorescence. The results are compared and contrasted with recent studies of counter-rotating circular cylinders to determine if suppression of vortex shedding plays a similarly important role in dictating the overall wake dynamics. This research was made possible through the generosity of Gordon and Betty Moore Foundation and the Caltech SURF Program.

  5. 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.

  6. Stability of unsteady flow in a rotating torus

    NASA Astrophysics Data System (ADS)

    Hewitt, Richard; Hazel, Andrew; Clarke, Richard; Denier, James

    2011-11-01

    We consider the temporal evolution of a viscous incompressible fluid in a torus of finite curvature; a problem first investigated experimentally by Madden and Mullin (1994), herein referred to as MM. The system is initially in a state of rigid-body rotation (about the axis of rotational symmetry) and the container's rotation rate is then changed impulsively. We describe the transient flow that is induced at small values of the Ekman number, over a time scale that is comparable to one complete rotation of the container. We show that (rotationally symmetric) eruptive singularities (of the boundary layer) occur at the inner or outer bend of the pipe for a decrease or an increase in rotation rate respectively. Moreover, there is a ratio of initial-to-final rotation frequencies for which eruptive singularities can occur at both the inner and outer bend simultaneously. We also demonstrate that the flow is susceptible to non-axisymmetric inflectional instabilities. The inflectional instability arises as a consequence of the developing eruption and is shown to be in qualitative agreement with the experimental observations of MM. Detailed quantitative comparisons are made between asymptotic predictions and finite (but small) Ekman number Navier-Stokes computations using a finite-element method.

  7. Particle Rotation Effects in Rarefied Two-Phase Plume Flows

    NASA Astrophysics Data System (ADS)

    Burt, Jonathan M.; Boyd, Iain D.

    2005-05-01

    We evaluate the effects of solid particle rotation in high-altitude solid rocket exhaust plume flows, through the development and application of methods for the simulation of two phase flows involving small rotating particles and a nonequilibrium gas. Green's functions are derived for the force, moment, and heat transfer rate to a rotating solid sphere within a locally free-molecular gas, and integration over a Maxwellian gas velocity distribution is used to determine the influence of particle rotation on the heat transfer rate at the equilibrium limit. The use of these Green's functions for the determination of particle phase properties through the Direct Simulation Monte Carlo method is discussed, and a procedure is outlined for the stochastic modeling of interphase collisions. As a test case, we consider the nearfield plume flow for a Star-27 solid rocket motor exhausting into a vacuum, and vary particle angular velocities at the nozzle exit plane in order to evaluate the influence of particle rotation on various flow properties. Simulation results show that rotation may lead to slightly higher particle temperatures near the central axis, but for the case considered the effects of particle rotation are generally found to be negligible.

  8. 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

  9. The Inhibition of the Rayleigh-Taylor Instability by Rotation.

    PubMed

    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

  10. Novel rotating field probe for inspection of tubes

    SciTech Connect

    Xin, J.; Tarkleson, E.; Lei, N.; Udpa, L.; Udpa, S. S.

    2012-05-17

    Inspection of steam generator tubes in nuclear power plants is extremely critical for safe operation of the power plant. In the nuclear industry, steam generator tube inspection using eddy current techniques has evolved over the years from a single bobbin coil, to rotating probe coil (RPC) and array probe, in an attempt to improve the speed and reliability of inspection. The RPC probe offers the accurate spatial resolution but involves complex mechanical rotation. This paper presents a novel design of eddy current probes based on rotating fields produced by three identical coils excited by a balanced three-phase supply. The sensor thereby achieves rotating probe functionality by electronic means and eliminates the need for mechanical rotation. The field generated by the probe is largely radial that result in induced currents that flow circularly around the radial axis and rotating around the tube at a synchronous speed effectively producing induced eddy currents that are multidirectional. The probe will consequently be sensitive to cracks of all orientations in the tube wall. The finite element model (FEM) results of the rotating fields and induced currents are presented. A prototype probe is being built to validate simulation results.

  11. The long-term rotation dynamics of neutron stars with differentially rotating unmagnetized core

    NASA Astrophysics Data System (ADS)

    Barsukov, D. P.; Goglichidze, O. A.; Tsygan, A. I.

    2014-10-01

    We consider the pulsar long-term rotation dynamics taking into account the non-rigidity of neutron star rotation. We restrict our attention to the models with two essential assumptions: (1) crust-core interaction occurs via the viscosity (magnetic coupling is not important); (2) neutron star shape is symmetrical over the magnetic axis. The neutron star core is described by linearized quasi-stationary Newtonian hydrodynamical equations in one-fluid and two-fluid (neutron superfluidity) approximations. It is shown that in this case the pulsar inclination angle evolves to 0° or 90° very quickly. Since such fast evolution seems to contradict the observation data, either neutron stars are triaxial or the magnetic field plays the leading role in crust-core coupling.

  12. Quantum Rotational Effects in Nanomagnetic Systems

    NASA Astrophysics Data System (ADS)

    O'Keeffe, Michael F.

    Quantum tunneling of the magnetic moment in a nanomagnet must conserve the total angular momentum. For a nanomagnet embedded in a rigid body, reversal of the magnetic moment will cause the body to rotate as a whole. When embedded in an elastic environment, tunneling of the magnetic moment will cause local elastic twists of the crystal structure. In this thesis, I will present a theoretical study of the interplay between magnetization and rotations in a variety of nanomagnetic systems which have some degree of rotational freedom. We investigate the effect of rotational freedom on the tunnel splitting of a nanomagnet which is free to rotate about its easy axis. Calculating the exact instanton of the coupled equations of motion shows that mechanical freedom of the particle renormalizes the easy axis anisotropy, increasing the tunnel splitting. To understand magnetization dynamics in free particles, we study a quantum mechanical model of a tunneling spin embedded in a rigid rotor. The exact energy levels for a symmetric rotor exhibit first and second order quantum phase transitions between states with different values the magnetic moment. A quantum phase diagram is obtained in which the magnetic moment depends strongly on the moments of inertia. An intrinsic contribution to decoherence of current oscillations of a flux qubit must come from the angular momentum it transfers to the surrounding body. Within exactly solvable models of a qubit embedded in a rigid body and an elastic medium, we show that slow decoherence is permitted if the solid is macroscopically large. The spin-boson model is one of the simplest representations of a two-level system interacting with a quantum harmonic oscillator, yet has eluded a closed-form solution. I investigate some possible approaches to understanding its spectrum. The Landau-Zener dynamics of a tunneling spin coupled to a torsional resonator show that for certain parameter ranges the system exhibits multiple Landau-Zener transitions

  13. Asteroid Ida - 6 Views Showing Rotation

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This composite image shows the asteroid 243 Ida as seen from the Galileo spacecraft during its approach on August 28, 1993. The six views were shuttered through the camera's green filter and show Ida's rotation over a period of about 3 hours 18 minutes. The asteroid makes a complete rotation every 4 hours 38 minutes; therefore, this set of images spans about 3/4 of Ida's rotation period and shows most of Ida's surface. By combining the information in these views with that from the highest resolution images returned from the spacecraft in September 1993, the size and shape of this irregular body can now be determined accurately The asteroid appears to be about 58 kilometers (36 miles) long and about 23 kilometers wide, with a very irregular shape and volume of some 16,000 cubic kilometers. The images are arranged in chronological order from a time 3 hours 51 minutes before closest approach (upper left), through upper right, middle left, middle right lower left and lower right (33 minutes before closest approach). The six images show Ida at the same scale throughout. Ida's rotation axis is roughly vertical in these images, and the rotation causes the right-hand end of Ida to move toward the viewer as time progresses. The first image was taken from a range of about 171,000 km (106,000 miles) and provides an image resolution of about 1,700 meters per pixel (the highest resolution achieved for Ida is about 25 meters per pixel). The second, taken 70 minutes later, is from 119,000 kilometers, followed by 102,000 kilometers, 85,000 kilometers, 50,000 kilometers, and 25,000 kilometers. The features on Ida are less sharp in the earlier views because of the greater distances. Prominent in the middle three views is a deep depression across the short axis of the Asteroid. This feature tends to support the idea that Ida may have originally been formed from two or more separate large objects that collided softly and stuck together. Also visible in the lower left view is an

  14. Constraints on Spin Axis and Thermal Properties of Asteroids in the WISE Catalog

    NASA Astrophysics Data System (ADS)

    MacLennan, Eric M.; Emery, J. P.

    2013-10-01

    It has widely been accepted that dynamical state of asteroids can strongly be influenced by radiation forces (e.g., Yarkovsky and YORP). Determination of an object’s thermal properties and spin state are a critical step towards understanding the effects of these forces. In this respect, observations of thermal flux emitted from the surfaces of asteroids are a powerful tool. The emission of flux is determined by the temperature distribution which is controlled by the thermal inertia, rotation rate, and spin axis orientation. By gathering data at multiple viewing geometries, the temperature distribution can be modeled accurately enough to separate the effects attributed to (some of) these parameters. Over the length of its mission, the Wide-Field Infrared Survey Explorer (WISE) observed many asteroids in two epochs (i.e., on either side of opposition) such that data for both morning and afternoon times were gathered. We have begun a project that employs a Thermophysical Model (TPM) in order to analyze these multi-epoch thermal observations with the goal of deriving the thermal properties and spin axis of a large number of asteroids. Here, we first investigate the validity and limits of our method on objects with a previously determined spin axis. Asteroid (413) Edburga has a published spin axis of λ = 202o, β = - 45o (ecliptic longitude and latitude, respectively) using the lightcurve inversion method. With our technique, we estimate a solution consistent with the previous estimate. Applying our TPM to WISE multi-epoch thermal observations of (155) Scylla (no known spin axis estimate), we also place estimates for the ecliptic longitude and latitude of its spin axis. Analysis of multi-epoch thermal data enables determination of spin axis orientation without knowing the rotation period, in contrast to the lightcurve inversion method. This is due to the coupling of thermal inertia and rotation rate in determining the longitudinal distribution of temperature. Their

  15. Determination of 3D optic axis orientation in cartilage by polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ugryumova, Nadya; Matcher, Stephen J.

    2007-02-01

    Polarization-sensitive optical coherence tomography has been used to solve fast-axis fibre orientation in three dimension space. Previously we have demonstrated that the apparent variations in polar angle orientation of collagen fibers along sagittal ridge of equine third metacarpophalangeal joint exist. A quantitative method based on multiple angles of illumination has been proposed to determine the polar angle of the collagen fibers. This method however ignored the full 3-D structure by assuming that the collagen fibers long-axis lay within the plane of incidence. A new quantitative method based on the theory of light propagation in uniaxial materials is described which avoids this assumption. To test this method we have performed control experiments on a sample of equine tendon (this tissue has well defined c-axis lying along the long-axis of the tendon). Several samples of tendon were cut to achieve a planar surface inclined at -20° to the long axis. Additional 30° rotation provided non-zero azimuthal angle. The surface was then imaged using incident beam angles -40°, -20°, 0, +20°, +40° in two orthogonal planes. Values for both the polar and azimuthal angles were then derived using a numerical optimisation procedure. Results agreed qualitatively with the nominal values but suggested that the accuracy was limited by our method of determining the apparent birefringence.

  16. Determination of 3D optic axis orientation in cartilage by polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ugryumova, Nadya; Bonesi, Marco; Matcher, Stephen J.

    2008-02-01

    Polarization-sensitive optical coherence tomography has been used to solve fast-axis fibre orientation in three dimension space. Previously we have demonstrated that the apparent variations in polar angle orientation of collagen fibers along sagittal ridge of equine third metacarpophalangeal joint exist. A quantitative method based on multiple angles of illumination has been proposed to determine the polar angle of the collagen fibers. This method however ignored the full 3D structure by assuming that the collagen fibers long-axis lay within the plane of incidence. A new quantitative method based on the theory of light propagation in uniaxial materials is described which avoids this assumption. To test this method we have performed control experiments on a sample of equine tendon (this tissue has well defined c-axis lying along the long-axis of the tendon). Several samples of tendon were cut to achieve a planar surface inclined at -20° to the long axis. Additional 30° rotation provided non-zero azimuthal angle. The surface was then imaged using incident beam angles -40°, -20°, 0, +20°, +40° in two orthogonal planes. Values for both the polar and azimuthal angles were then derived using a numerical optimisation procedure. Results agreed qualitatively with the nominal values but suggested that the accuracy was limited by our method of determining the apparent birefringence.

  17. [Development of a computerized three-dimension system for displaying and analyzing mandibular helical axis pathways].

    PubMed

    Chen, Li; Zhang, Hao; Feng, Hailan; Zhang, Fengjun

    2014-12-01

    This paper is aimed to develop a computerized three dimensional system for displaying and analyzing mandibular helical axis pathways. Mandibular movements were recorded using a six-degrees-of-freedom ultrasonic jaw movement recording device. The three-dimensional digital models of the midface and the mandible were reconstructed and segmented from CT skull images. The digital models were then transformed to the coordinate system of mandibular motion data by using an optical measuring system. The system was programmed on the base of the Visualization ToolKit and Open Scene Graphics Library. According to the motion data, transformation matrices were calculated to simulate mandibular movements. Meanwhile, mandibular helical axis pathways were calculated and displayed three dimensionally by means of an eigenvalues method. The following parameters of mandibular helical axis were calculated: the rotation around instantaneous helical axis, the translation along it, its spatial orientation, its position and distance relative to any special reference point. These parameters could be exported to describe comprehensively the whole mandiblular movements. It could be concluded that our system would contribute to the study of mandiblular helical axis pathways. PMID:25868236

  18. 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.

  19. Vega is a rapidly rotating star.

    PubMed

    Peterson, D M; Hummel, C A; Pauls, T A; Armstrong, J T; Benson, J A; Gilbreath, G C; Hindsley, R B; Hutter, D J; Johnston, K J; Mozurkewich, D; Schmitt, H R

    2006-04-13

    Vega, the second brightest star in the northern hemisphere, serves as a primary spectral type standard. Although its spectrum is dominated by broad hydrogen lines, the narrower lines of the heavy elements suggested slow to moderate rotation, giving confidence that the ground-based calibration of its visible spectrum could be safely extrapolated into the ultraviolet and near-infrared (through atmosphere models), where it also serves as the primary photometric calibrator. But there have been problems: the star is too bright compared to its peers and it has unusually shaped absorption line profiles, leading some to suggest that it is a distorted, rapidly rotating star seen pole-on. Here we report optical interferometric observations that show that Vega has the asymmetric brightness distribution of the bright, slightly offset polar axis of a star rotating at 93 per cent of its breakup speed. In addition to explaining the unusual brightness and line shape peculiarities, this result leads to the prediction of an excess of near-infrared emission compared to the visible, in agreement with observations. The large temperature differences predicted across its surface call into question composition determinations, adding uncertainty to Vega's age and opening the possibility that its debris disk could be substantially older than previously thought. PMID:16612375

  20. 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.

  1. Self-gravitational instability of rotating anisotropic heat-conducting plasma

    SciTech Connect

    Prajapati, R. P.; Parihar, A. K.; Chhajlani, R. K.

    2008-01-15

    The self-gravitational instability of rotating anisotropic heat-conducting plasma with modified Chew-Goldberger-Low equations is investigated. The general dispersion relation is obtained using normal mode analysis by constructing the linearized set of equations. This dispersion relation is further reduced for propagation parallel and perpendicular to the direction of magnetic field. These conditions are discussed for axis of rotation along and perpendicular to the magnetic field. It is found that the heat flux vector does not influence the transverse mode of propagation for both cases of rotation and Jeans condition remains unchanged. In case of propagation parallel to the magnetic field with axis of rotation perpendicular to the magnetic field, we get the dispersion relation, which shows the joint effect of rotation and heat flux vector. The two separate modes of propagation are obtained in terms of rotation and heat flux vector for rotation parallel to the magnetic field. It is demonstrated that the Alfven wave and the associated firehose instability are not affected by the presence of heat flux corrections and rotation also. The numerical analysis is performed to show the effect of rotation, pressure anisotropy, and heat flux parameter on the condition of instability in the spiral arms of galaxy. The Jeans condition of gravitational instability is obtained for both the cases of propagation.

  2. 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

  3. 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.

  4. Perception of longitudinal body axis in patients with stroke: a pilot study

    PubMed Central

    Barra, J; Chauvineau, V; Ohlmann, T; Gresty, M; Pérennou, D

    2007-01-01

    Background and aims To investigate the hypothesis that patients with a hemisphere stroke may perceive their longitudinal body axis (LBA) rotated in the frontal plane. This error in an egocentric frame of reference could be detrimental to posture, as tilted LBA would imply an unequal distribution of body mass about the true vertical. Method 26 healthy subjects matched in age with 18 patients living with stroke participated in the study. The 18 patients were tested on average 80 days after a first left (n = 8) or right (n = 10) hemisphere stroke. Participants perceived their LBA by adjustments of the orientation of a luminous rod pivoting around a dorsonavel axis to the subjective direction of LBA. Participants were studied in the supine position to dissociate somaesthetic cues from graviceptive cues. Results Patients with stroke perceived their LBA rotated to the contralesional side in comparison with controls (p = 0.004). For all controls and 10 patients with stroke, the perceived LBA was very close to true LBA (mean (SD) 0.24° (1.31°)). For eight patients with stroke (six right stroke, two left stroke), the perceived LBA was rotated from true body orientation in the direction opposite to the lesioned side (range 3–9.5°, mean 5.2°). These eight patients provided similar estimates by tactile manipulation of the rod (without vision). The rotation of perceived LBA was more pronounced for right‐hemisphere strokes. The magnitudes of perceptual rotations correlated with sensory loss, signs of spatial neglect and the degree of postural and gait disability. Conclusion This is the first study showing that certain patients with a hemisphere stroke perceive their LBA rotated to the contralesional side. The consequences for perceptuomotor coordination have implications for their postural disorders. PMID:16868067

  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. Effects of Mass-Loading Variations and Applied Moments on Motion and Control of a Manned Rotating Space Vehicle

    NASA Technical Reports Server (NTRS)

    Grantham, William D.

    1961-01-01

    An analytical study has been made to determine the effects of mass-loading variations and onboard rotating machinery on a hypothetical earth-satellite space station, rotating to provide an artificial gravity equal to one-fourth of that at the earth's surface. Attempts were also made to damp out or minimize undesirable motions by using mass shifts, constant-rate inertia wheels, or jet-reaction moments. Results obtained indicate that the shifting of masses within the rotating space station could bring about large roll oscillations (plus or minus 100 degrees) or even continuous rolling motions if the craft is rotating about the axis of intermediate moment of inertia. The pitch angles obtained were generally small (less than plus or minus 1 degree). The amplitudes of the roll and pitch oscillations are dependent upon the angle of displacement of the greatest principal axis of inertia from the initial spin axis. In attempting to damp out or minimize undesirable motions, it was found that a constant-rate inertia wheel located on and rotating about the axis about which the craft is rotating (Z-axis) was beneficial in keeping the roll angles relatively small, provided it had a sufficient amount of angular momentum. It was also found that the use of jet-reaction moments was very satisfactory for damping undesirable motions in that the roll oscillations could be damped.

  7. Is the Coupling of C3V Internal Rotation and Normal Vibrations a Tractable Problem?

    NASA Astrophysics Data System (ADS)

    Pearson, John; Groner, Peter; Daly, Adam M.

    2016-06-01

    The solution of a C3V internal rotation problem for the torsional manifold of an isolated vibrational state such as the ground state is well established. However, once an interacting small amplitude vibrational state is involved the path to a solution becomes far less clear and there is little guidance in the literature on how to proceed. The fundamental challenge is that the torsional problem and the internal axis system are unique to each torsional manifold of a specific vibrational state. In an asymmetric top molecule vibrational angular momentum can be rotated away, but this sort of rotation changes the angle between the internal rotation axis and the principle axis when there is an internal rotor. This means that there is an angle between the internal axis systems of each torsional manifold of a vibrational state. The net result is that the coupling between the two states must account for the difference in internal axis angle and will have some significant consequences to the selection rules and interactions. Two cases will be discussed, methanol and ethyl cyanide.

  8. 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

  9. Modular off-axis solar concentrator

    SciTech Connect

    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

    DOEpatents

    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. Effects of solar radiation pressure torque on the rotational motion of an artificial satellite

    NASA Technical Reports Server (NTRS)

    Zanardi, Maria Cecilia F. P. S.; Vilhenademoraes, Rodolpho

    1992-01-01

    The motion of an artificial satellite about its center of mass is studied considering torques due to the gravity gradient and direct solar radiation pressure. A model for direct solar radiation torque is derived for a circular cylindrical satellite. An analytical solution is obtained by the method of variation of the parameters. This solution shows that the angular variables have secular variation but that the modulus of the rotational angular momentum, the projection of rotational angular momentum on the z axis of the moment of inertia and inertial axis z, suffer only periodic variations. Considering a hypothetical artificial satellite, a numerical application is demonstrated.

  12. Self-induced flow and heat transfer in a rotating tube

    SciTech Connect

    Gilham, S.; Ivey, P.C.; Owen, J.M. Cranfield Inst. of Technology, United Kingdom Bath Univ. )

    1993-03-01

    Self-induced flow occurs when a tube, with one end open and the other sealed, is rotated about its axis: fluid flows along the axis towards the sealed end and returns in an annular layer on the cylindrical wall. Numerical solutions of the Navier-Stokes and energy equations have been obtained for laminar flow, and the Reynolds analogy has been used to provide theoretical correlations for the average Nusselt numbers on the end wall of the tube. Heat transfer measurements have been made in a rotating-tube rig, and the measured Nusselt numbers are, in the main, in good agreement with the computed values. 18 refs.

  13. 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.

  14. 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.

  15. 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.

  16. Rotation of Giant Stars

    NASA Astrophysics Data System (ADS)

    Kissin, Yevgeni; Thompson, Christopher

    2015-07-01

    The internal rotation of post-main sequence stars is investigated, in response to the convective pumping of angular momentum toward the stellar core, combined with a tight magnetic coupling between core and envelope. The spin evolution is calculated using model stars of initial mass 1, 1.5, and 5 {M}ȯ , taking into account mass loss on the giant branches. We also include the deposition of orbital angular momentum from a sub-stellar companion, as influenced by tidal drag along with the excitation of orbital eccentricity by a fluctuating gravitational quadrupole moment. A range of angular velocity profiles {{Ω }}(r) is considered in the envelope, extending from solid rotation to constant specific angular momentum. We focus on the backreaction of the Coriolis force, and the threshold for dynamo action in the inner envelope. Quantitative agreement with measurements of core rotation in subgiants and post-He core flash stars by Kepler is obtained with a two-layer angular velocity profile: uniform specific angular momentum where the Coriolis parameter {Co}\\equiv {{Ω }}{τ }{con}≲ 1 (here {τ }{con} is the convective time), and {{Ω }}(r)\\propto {r}-1 where {Co}≳ 1. The inner profile is interpreted in terms of a balance between the Coriolis force and angular pressure gradients driven by radially extended convective plumes. Inward angular momentum pumping reduces the surface rotation of subgiants, and the need for a rejuvenated magnetic wind torque. The co-evolution of internal magnetic fields and rotation is considered in Kissin & Thompson, along with the breaking of the rotational coupling between core and envelope due to heavy mass loss.

  17. 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)

  18. Rotating shielded crane system

    DOEpatents

    Commander, John C.

    1988-01-01

    A rotating, radiation shielded crane system for use in a high radiation test cell, comprises a radiation shielding wall, a cylindrical ceiling made of radiation shielding material and a rotatable crane disposed above the ceiling. The ceiling rests on an annular ledge intergrally attached to the inner surface of the shielding wall. Removable plugs in the ceiling provide access for the crane from the top of the ceiling into the test cell. A seal is provided at the interface between the inner surface of the shielding wall and the ceiling.

  19. Rotating quantum states

    NASA Astrophysics Data System (ADS)

    Ambruş, Victor E.; Winstanley, Elizabeth

    2014-06-01

    We revisit the definition of rotating thermal states for scalar and fermion fields in unbounded Minkowski space-time. For scalar fields such states are ill-defined everywhere, but for fermion fields an appropriate definition of the vacuum gives thermal states regular inside the speed-of-light surface. For a massless fermion field, we derive analytic expressions for the thermal expectation values of the fermion current and stress-energy tensor. These expressions may provide qualitative insights into the behaviour of thermal rotating states on more complex space-time geometries.

  20. 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.