Space shuttle rudder/speedbrake actuation subsystem

The Rudder/Speedbrake (R/SB) Actuation Subsystem for use on the NASA Space Shuttle Orbiter is an electro-hydro-mechanical system which provides the control and positionary capability of the orbiter aero-dynamic primary flight control surface. The system is located in the vehicle's vertical stabilizer. The geared rotary actuators provide a power hinge feature of the split panel rudder. Actuation of both panels in the same direction provides conventional rudder control; actuating the panels differentially provides a speedbrake function intended to control both speed and pitch. The commands may be superimposed on one another. The system consists of one power drive unit which responds to quadredundant avionic signals to generate a rotary output, four geared rotary actuators, which develop rotary position and torque as outputs, and ten torque transmitting drive-shifts

Motion of magnetotactic bacteria swarms in an external field

Magnetotactic bacteria moving on circular orbits form hydrodynamically bound states. When close to a surface and with the tilting of the field in a direction close to the perpendicular to this surface these swarms move perpendicularly to the tilting angle. We describe quantitatively this motion by a continuum model with couple stress arising from the torques produced by the rotary motors of the amphitrichous magnetotactic bacteria. The model not only correctly describes the change of direction of swarm motion while inverting the tangential field but also predicts reasonable value of the torque produced by the rotary motors

Non-backdriveable free wheeling coupling

A rotary coupling for connecting a driven part to a source of rotary force is described. This device transmits rotary force in one direction only and disengages to permit the driven part to free wheel when the input member is stopped and precludes the backdriving of rotary force from output member to input member. The coupling includes an input member having a splined shaft, a coupling member connected to the splined shaft, and a coaxial output member. The coupling member and the output member having complementary sets of axially facing clutch teeth. Guides in the form of helical grooves on the coupling member and spring loaded followers acting with the guides affect the engagement and disengagement of the clutch teeth by moving the coupling member toward and away from output member, the followers and guides themselves disengaging to permit free wheeling of output member when input member is stopped

Numerical modelling of fluid flow and particle transport in a riugh rock fracture during shear

The effects of both translational and rotary shear on particle transport Ander coupled shear-flow test conditions in a single rouge rock fracture were numerically investigated in this thesis. A pair of digitalized surfaces of a 250x250 mm concrete rough fracture replica were numerically manipulated to simulate the translational and rotary shearing processes of the sample, using Finite Element Method (FEM). Different fluid flow situations were cosidered. For the translational shear three different flow patterns-unidirectional, bi-directional and radial-have been taken into account. For rotary shear, only the radial flow patterns have been considered. Furthermore, the effect of the fracture surface roughness on the aperture and transmissivity fields was evaluated using semi-variograms. The results of flow and particle transport simulations show that translational shear yields a channelling effect in the direction perpendicular to shear direction, creating high transmissivity channels through which the particles travelling in this direction can travel fast and without being delayed by bypassing low transmissivity areas. Bi-directional flow patterns show clearly the shortcomings of the conventional shear-flow tests in the laboratory with a unidirectional flow. In radial flow patterns, while translational shear generates an anisotropic particle transport behaviour with faster transport perpendicular to shear direction, rotary shear presents isotropic flow field and particle paths in all directions

Swimming using surface acoustic waves

Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel

Positional and spontaneous nystagmus (8-IML-1)

Nystagmus is an involuntary oscillation of the eyes with a slow eye movement in one direction and a compensatory quick eye movement in the opposite direction to return the eyes to their original position. The slow phase of nystagmus is often generated by asymmetry in the peripheral vestibular system, and generally nystagmus in the horizontal direction dominates although vertical and rotary nystagmus can be seen in certain pathological situations

Evidence of the selection of tidal streams by northern rock sole (Lepidopsetta polyxystra) for transport in the eastern Bering Sea

Depth data from archival tags on northern rock sole (Lepidopsetta polyxystra) were examined to assess whether fish used tidal currents to aid horizontal migration. Two northern rock sole, out of 115 released with archival tags in the eastern Bering Sea, were recovered 314 and 667 days after release. Both fish made periodic excursions away from the bottom during mostly night-time hours, but also during particular phases of the tide cycle. One fish that was captured and released in an area of rotary currents made vertical excursions that were correlated with tidal current direction. To test the hypothesis that the fish made vertical excursions to use tidal currents to aid migration, a hypothetical migratory path was calculated using a tide model to predict the current direction and speed during periods when the fish was off the bottom. This migration included limited movements from July through December, followed by a 200-km southern migration from January through February, then a return northward in March and April. The successful application of tidal current information to predict a horizontal migratory path not only provides evidence of selective tidal stream transport but indicates that vertical excursions were conducted primarily to assist horizontal migration