Showing papers on "Rotation published in 1986"

Observation of Berry's topological phase by use of an optical fiber.

Abstract: We report the first experimental verification of Berry's topological phase. The key element in the experiment was a single-mode, helically wound optical fiber, inside which a photon of a given helicity could be adiabatically transported around a closed path in momentum space. The experiment confirmed at the classical level that the angle of rotation of linearly polarized light in this fiber gives a direct measure of Berry's phase. The topological nature of this effect was also verified, i.e., the rotation was found to be independent of deformations of fiber path if the solid angle of the path in momentum space stayed constant.

Anisotropy of the inner core inferred from PKIKP travel times

Abstract: Travel-time residuals of the PKIKP phase observed between 170° and 180° show an axisymmetric pattern of degree 2 with an amplitude of about 2 seconds. The effect at shorter distances is much less pronounced and the entire data set cannot be explained by a physically realistic radial distribution of (isotropic) heterogeneity. We propose that, in addition to the general (isotropic) heterogeneity, the inner core is anisotropic with cylindrical symmetry aligned with the earth's rotation axis. Average P-velocity along this axis is about 1 percent faster than in the equatorial plane.

Intravascular catheter and method

Abstract: An intravascular catheter includes a flexible guide wire mounted for relative rotational and reciprocal movements within a reciprocal and flexible first tube or sheath. A rotary and flexible second tube is mounted for relative reciprocal movement on the first tube and has a rotary inner cutting head secured on an end thereof. The inner cutting head is closely fitted within an outer cutting head that is slidably mounted on the first tube. In carrying out the method of this invention, a blockage in a blood vessel, such as a coronary artery, is located and the outer cutting head engages the blockage to cut the blockage into fragments in response to rotation of the inner cutting head. The fragments are flushed-out from the inner cutting head and are drained through an evacuated annular passage defined between the first and second tubes.

Static earth pressures with various wall movements

Abstract: In this paper the writers first present experimental results obtained for the distribution of the active stresses due to a sand backfill behind a rigid wall rotating about the top. The experimental evidence shows that the stress distribution is nonlinear and that, due to arching, the stress near the top of the wall increases beyond the level of the at‐rest stress. Consequently, the point of application of the lateral thrust is much higher than one‐third from the wall base. Arching effects increase with increasing soil density. Secondly, comparisons of the active earth pressure distributions are made for three different wall movement modes: (1) Rotation about top; (2) rotation about heel; and (3) translation. Total active resultant forces and the points of application of these forces are summarized.

Experimental study of convective structures in rotating fluids

Abstract: We describe a series of laboratory experiments to study convective structures in rotating fluids (distilled water) in ranges of Rayleigh flux number Raf from 106 to 2 × 1011 and of Taylor number Ta from 106 to 1012. An intermediate quasi-stationary ring pattern of convection was found to arise from the interaction of the onset of convection with the fluid spin-up, for which we determined the times of origin and destruction, the distances between the rings, and the diameter of the central ring in terms of Raf and Ta. The ring structure evolves into a vortex grid which can be regular or irregular. In terms of Raf and Ta the regular grid exists in the linear regime, when the number of vortices N is in accord with the linear theory, when , or in the nonlinear regime when N ∝ h−2Ta½Raf−⅙ ∝ where Ω is the angular velocity and h is the fluid depth. In the irregular regime we always have N ∝ Ω. The transition from the regular regime to the irregular one is rather gradual and is determined by the value of the ordinary Rayleigh number, which we found to be greater than the first critical number Ra ∝ Ta2/3 by a factor about 25–40. In the transition region vortex interactions are observed, which start with rotation of two adjacent vortices around a common axis, then the vortices come closer and rotation accelerates, following which the vortices form a double helix and then coalesce into one stronger vortex.Some other qualitative experiments show that if the rotating vessel with the convective fluid is inclined to the horizontal, the vortex grid is formed along the rotation axis in accordance with the Proudman–Taylor theorem.

Collective rotation of molecules driven by the angular momentum of light in a nematic film.

Abstract: It is experimentally demonstrated that a circularly polarized laser beam normally incident on a homeotropically aligned nematic film can induce a collective precession of the molecules in the film if the laser intensity is above the threshold for the Freedericksz transition. The effect is shown to result from a transfer of angular momentum from the laser beam to the medium.

Thermal transfer printer

Abstract: A thermal transfer printer includes a mark disposed on an ink spool of an ink film cassette, reading device for reading the rotation of the ink spool by use of the mark, a calculation device for calculating the used quantity of ink film by use of the rotation data of the spool, and a display portion for displaying the remaining quantity of ink film obtained by the calculation device.

Latitude and depth variation of solar rotation

Abstract: Measurements of the frequencies of various modes of trapped acoustic waves provide information about rotation and structure within the Sun. Previous work dealt with observations of wave modes confined near the solar equator, which provided some information about the depth variation of rotation without resolving a possible latitude variation1,2. Recent work extended measurements to modes covering various latitude ranges from which the variation with latitude of solar rotation can be studied3–5. Since these measurements were restricted to modes with spherical harmonic degrees less than 50, they provide averages of rotation over great depth ranges that do not resolve the convective envelope. We now present new results for degrees up to 98 which allow the convective envelope to be isolated. For degrees between 20 and 98 we find no evidence that internal rotation differs significantly with depth or latitude from the rotation of surface magnetic field patterns. Modes covering a wide latitude range have systematically lower frequencies than those confined near the equator, indicating the existence of a structural asymmetry within the Sun.

A model of the nystagmus induced by off vertical axis rotation

Abstract: A three-dimensional model is proposed that accounts for a number of phenomena attributed to the otoliths. It is constructed by extending and modifying a model of vestibular velocity storage. It is proposed that the otolith information about the orientation of the head to gravity changes the time constant of vestibular responses by modulating the gain of the velocity storage feedback loop. It is further proposed that the otolith signals, such as those that generate L-nystagmus (linear acceleration induced nystagmus), are partially coupled to the vestibular system via the velocity storage integrator. The combination of these two hypotheses suggests that a vestibular neural mechanism exists that performs correlation in the mathematical sense which is multiplication followed by integration. The multiplication is performed by the otolith modulation of the velocity storage feedback loop gain and the integration is performed by the velocity storage mechanism itself. Correlation allows calculation of the degree to which two signals are related and in this context provides a simple method of determining head angular velocity from the components of linear acceleration induced by off-vertical axis rotation. Correlation accounts for the otolith supplementation of the VOR and the sustained nystagmus generated by off-vertical axis rotation. The model also predicts the cross-coupling of horizontal and vertical optokinetic after nystagmus that occurs in head-lateral positions and the reported effects of tilt on vestibular responses.

Well pipe stabbing and back-up apparatus

Abstract: Apparatus for use during connection of a length of pipe (14") to the upper end of a drill string (14), preferably in a top drive drilling arrangement, and including a back-up tool (107) for retaining the upper end of the drill string (14) against rotation as the added length of pipe (14") is connected threadedly thereto. This back-up tool (107) is mounted for movement between an active position for engaging and holding the upper end of the drill string (14) and a laterally retracted position. A stabbing unit (121) associated with the back-up tool (107) acts to locate the additional length op pipe (14") while it is connected to the string (14), and is mounted for movement with the back-up tool (107) between the active and inactive positions of the latter, and also for movement relative to the back-up tool (107), in the active position of that tool (107), between an extended position for engaging and holding the additional length of pipe (14") at a location offset laterally with respect to the back-up tool (107) and a stabbing position locating the additional length of pipe (14") in alignment with the back-up tool (107) for connection to the string (14).

Reflex and mechanical contributions to head stabilization in alert cats.

Abstract: Five alert cats were tested for their responses to rotation in a device that allowed rotation of the head on the trunk about a vertical axis passing through the C1-C2 vertebral joint. Electrodes were implanted to record the horizontal and vertical electrooculogram and electromyographic (EMG) activity of the dorsal neck muscles splenius, biventer cervicus, and complexus. Head rotation and torque acting on the head were recorded in the horizontal plane during rotations in the 0.05-5.0 Hz frequency range. Responses were interpreted with reference to a closed-loop dynamic model of the head-neck system. Whole-body rotation (WBR) with no neck movement elicited a vestibulocollic reflex (VCR). Neck muscle EMG lagged the sinusoidal platform rotation by approximately 120 degrees at low frequencies, which represents a 60 degrees lead relative to a perfectly compensatory 180 degrees lag. This phase lead was related to the cumulative eye position of the accompanying horizontal vestibular nystagmus as reported by Vidal et al. Horizontal head torque exhibited a similar low-frequency behavior. At high frequencies, EMG exhibited a progressively increasing phase lead and gain increase typical of a second-order lead system as described in decerebrate cats. Torque, however, showed much less lead and gain increase, presumably because of the low-pass filter properties of the process coupling muscle excitation to torque. Head torque did exhibit a steep increase in gain with frequency and a phase approaching that of platform acceleration at high frequencies when weights were attached to the head to increase its moment of inertia. The same +40 dB/decade gain slope and phase approaching 0 degree was observed during WBR rotation of the anesthetized cat in which head inertia is the only factor contributing to the torque. This dynamic behavior was predicted by the inertial component of the model. In the alert unweighted cat, the inertial torque was smaller than VCR-generated torque at frequencies below 4 Hz. Rotation of the neck with the head held fixed in space (HFS rotation) elicited a cervicocollic reflex (CCR). Neck EMG response was very similar to that observed during WBR, both in dynamic behavior and overall gain. Torque, however, was consistently greater than that generated by WBR and showed a steady increase of 8 dB/decade as frequency rose. The added torque can be attributed to the viscoelastic properties of neck muscles. Driven rotation of the head on the fixed body elicited torques that could be closely approximated by a vector sum of torques observed during WBR and HFS rotations.(ABSTRACT TRUNCATED AT 400 WORDS)

Excitation of molecular rotation by periodic microwave pulses. A testing ground for Anderson localization

Abstract: We study the excitation of molecular rotation by microwave pulses of duration σ which occur periodically with frequency ω. We analyze the molecular dynamics both classically and quantum mechanically and consider situations where the coupling of the field to the molecule is strong. In both approaches, the angular momentum transmitted to the molecule is confined to a finite band of width ≊1/σ. But, while the classical dynamics displays chaotic features, the quantum treatment distinguishes clearly between two regimes. Resonance excitation occurs when ω is rationally related to the basic rotation frequency ω0. Off resonance (ω/ω0 irrational), the probability to transfer angular momentum to the molecule is small and the underlying mechanism for this effect is analogous to the Anderson model of localization in a one‐dimensional random lattice with a finite number of sites. We show that the conditions required by our analysis can be achieved with, e.g., PbTe or CsI molecules and conventional field strengths and we propose this system as an experimental testing ground for the Anderson localization mechanism.

Round cutting tool for cutters

Abstract: A cutter including a chisel wheel having an axis of rotation about which the wheel is adapted to rotate during a cutting operation; a plurality of cutting tools each including a tool body having a longitudinal axis, a chisel bit and a chisel shank; the chisel wheel carrying chisel holders which freely rotatably mount each cutting tool for rotation about its associated axis, each chisel bit being a separate hard metal body fixed to an end portion of its associated tool body remote from its associated shank, each chisel bit having a cone shaped working section merging toward an apex portion, a plurality of peripherally spaced axially extending grooves formed in the cone-shaped working section which automatically rotate each cutting tool about its longitudinal axis during the operation of the chisel wheel, and each longitudinal axis setting-off with a plane normal to the axis of rotation of the chisel and included angle of up to generally 45° which ensures uniform wear of each chisel bit, particularly its apex portion, during operation of the chisel wheel.

Rotation of the Coronal Magnetic Field

Abstract: The coronal magnetic field rotates differently than the photosphere. The field configuration of the corona can be calculated from the observed photosphpere field using a potential field model. Correlation of the field patterns at different latitudes with a lag near one solar rotation shows much less differential rotation than observed in the photospheric field; however, the peak is very broad and determines the rotation rate rather poorly. Consideration of longer lags reveals a more complex rotational structure and indicates different rotation rates in the Northern and Southern Hemispheres. Spectral analysis of the equatorial dipole component of the coronal field reveals an organization into just a few discrete rotation frequencies which are apparently present simultaneously. Spectral analysis of the field at different latitudes shows that the frequencies are present simultaneously. Spectra analysis of the field at different latitudes shows that the frequencies are present simultaneously, but in different hemispheres, and that the Southern Hemisphere fields rotate more slowly than those in the north in solar cycle 21.

The rotation period of Uranus

Abstract: On 24 January 1986 the spacecraft Voyager 2 transversed the innermost magnetosphere of the planet Uranus, coming as close as 4.2 Uranus radii to the planet. It is pointed out that the magnetic field data provide a direct measure of the rotation period of the planet's interior, where the field is generated. Two period determinations are reported. A combination of the obtained values provides a weighted mean value of P = 17.24 + or - 0.01 h. It is concluded that the 17.24-h rotation period has important consequences for studies of atmospheric dynamics and the internal structure and composition of Uranus. Thus, inferences regarding the internal structure can be drawn from the relationship between the observed planetary oblateness, rotation period, and gravitational moment.

Technique for steering and monitoring the orientation of a powered underground boring device

Abstract: A technique for providing a continuous underground tunnel is disclosed herein. This technique utilizes an elongated boring device including a forward facing, off-axis high pressure fluid jet which is rotated about the elongated axis of the device while the latter is urged forward through the soil, whereby to cause the device to bore a tunnel through the soil as it moves forward. In accordance with one feature of this technique, the boring device is steered by modulating the speed and/or the direction of rotation of its off-axis fluid jet in a way which depends upon the desired direction to be taken by the boring device within the soil. In accordance with another feature of the overall technique, the pitch angle of the boring device, as defined by its elongation axis, is monitored relative to a horizontal ground plane, independent of the roll position of the device. In accordance with still another feature of the technique, the roll angle of the boring device and the position of its off-axis jet are simultaneously monitored whereby to monitor the precise rotational position of the jet relative to its roll position.

Concealed drive coupling for use with modular screw conveyor

Abstract: A method and apparatus for coupling the drive shaft of an integrally molded modular screw conveyor is disclosed. A non-circular elongated drive shaft includes a non-circular axially extending aperture for receiving a first end of a coupling member having a corresponding size and shape such that rotation with respect to the shaft and coupling member is not possible. In addition, both the shaft and the coupling member define aligned recesses for receiving a locking pin so as to also prevent axially movement between the two. An integrally formed screw conveyor module includes an axially extending aperture with a size and cross-sectional shape for slideably receiving the drive shaft such that rotation is prevented between the drive shaft and the module. The locking pin is held in position by sliding the module over the locking pin when it is in place within the shaft and coupling member.

Collisional drift instability in a variable radial electric field

Abstract: The collisional drift instability, which is observed in a weakly ionized argon plasma, is described by a cylindrical two-fluid model which allows for arbitrary density profiles and a sheared E*B rotation of the plasma. The waves are destabilized by a current drawn from a DC biased grid (in the path of the plasma) to ground. Variation of the grid-to-ground current is shown to alter the radial potential profile and thus the E*B rotation of the plasma. A threshold current destabilizes the plasma. Above this threshold, mode frequency is found to increase with current. Predictions of the model demonstrate both rigid body and sheared E*B rotation are destabilizing and that both provide the well known Doppler shift to the real frequency. When three versions of the model are compared, the best agreement with observed real frequency occurs when the radial electric field is included rigorously in the theory. The documented increase in the radial potential gradient with grid-to-ground current is shown to be responsible for the corresponding increase frequency. Through a transition from a stable to an unstable regime of grid operation the observed increase in radial potential gradient is strongly suggested as the destabilizing mechanism at work. The radial wave shape is predicted closely by two versions of the model in which the radial electric field is or is not included, and both provide excellent agreement with experiment.

Torque developed at simulated sliding between sport shoes and an artificial turf

Abstract: Rotation torque is known to be one of many factors affecting the risk of injury in athletics. Experiments were performed to examine the torque and friction on different sport shoes when sliding on an artificial turf. An apparatus was constructed in which it is possible to measure simultaneously the torque and the frictional force developed when a shoe slides on a surface. Measurements were made for 25 different shoes on an artificial turf. The frictional force was independent of the speed in the range 1 to 5 m/s. The torque was dependent on the physical distribution of the texture of the sole and slightly dependent on the frictional force. The results indicate that the physical distribution of the sole at the heel and toe, as well as the material, is of great importance for the torque developed.

Single gyro northfinder

Abstract: Disclosed is a northfinding apparatus having a single rotation rate sensor secured to a platform. The output of the rotation rate sensor is corrected for tilt and tilt rate of the platform. Measurements of the tilt and tilt rate and the rotation rate are combined to provide an azimuth angle of the platform relative to north.

Vibration and Buckling of Rotating, Pretwisted, Preconed Beams Including Coriolis Effects

Abstract: The effects of pretwist, precone, setting angle and Coriolis forces on the vibration and buckling behavior of rotating, torsionally rigid, cantilevered beams were studied. The beam is considered to be clamped on the axis of rotation in one case, and off the axis of rotation in the other. Two methods are employed for the solution of the vibration problem: (1) one based upon a finite-difference approach using second order central differences for solution of the equations of motion, and (2) based upon the minimum of the total potential energy functional with a Ritz type of solution procedure making use of complex forms of shape functions for the dependent variables. The individual and collective effects of pretwist, precone, setting angle, thickness ratio and Coriolis forces on the natural frequencies and the buckling boundaries are presented. It is shown that the inclusion of Coriolis effects is necessary for blades of moderate to large thickness ratios while these effects are not so important for small thickness ratio blades. The possibility of buckling due to centrifugal softening terms for large values of precone and rotation is shown.

Apparatus for producing a force

Abstract: Apparatus for producing a propulsion force comprises a pair of counter-rotating externally geared flywheels which are mounted on shafts for rotation in a housing and are balanced for high speed rotation. Each flywheel carries a mass slideable thereon in a radial slot but constrained to rotate angularly with the flywheel. The mass is constrained to rotate eccentrically of the flywheel by a stationary cam surface surrounding the path of rotation of the mass. The cam surface is provided on a plate slideable relative to the flywheels to adjust the degree of eccentricity of the cam track relative to the flywheel. A vibration isolation unit is connected between the housing of the flywheels and the frame of the device including a pair of airbags positioned between plates so as to communicate only the net unidirectional force from the housing to the chassis.