Abstract: A ripple-mode controller provides reliable operation in multi-phase power supply circuits, over a variety of operating conditions. Cross-phase blanking allows the controller to preserve the desired phase relationship between the switching pulses its provides to the different output phases, and permits the controller to operate each output phase at nearly 100% duty cycles. Active current sharing compliments blanking operations by adjusting the width of switching pulses the controller provides to one or more of the output phases based on detecting load current imbalances between the different output phases. With active current sharing, the controller prevents one or more output phases from carrying excessive portions of the load current. Further complimenting its operation, the controller may include virtual ripple generation to increase the noise immunity of its ripple-mode regulation.

Abstract: A voltage positioning technique allows a power supply controller to more fully exploit active voltage positioning as a way of maintaining supply voltage within the limits defined for an associated electrical load. The supply voltage is allowed to “droop” as a function of load current. Droop may be implemented in linear proportion to load current, or as a discrete droop function once load current exceeds a given threshold. In either case, the droop circuitry of the supply controller implements a bounding function that establishes an accurately known maximum droop voltage magnitude. This maximum droop voltage limit establishes a reliable lower limit for the supply voltage independent of increasing load current. This accurately set lower bound for the droop voltage enables the controller to more aggressively position the supply voltage at the lower voltage limit of the load, which minimizes voltage overshoot and load power consumption.

Abstract: A voltage positioning technique allows a power supply controller to more fully exploit active voltage positioning as a way of maintaining supply voltage within the limits defined for an associated electrical load. The supply voltage is allowed to “droop” as a function of load current. Droop may be implemented in linear proportion to load current, or as a discrete droop function once load current exceeds a given threshold. In either case, the droop circuitry of the supply controller implements a bounding function that establishes an accurately known maximum droop voltage magnitude. This maximum droop voltage limit establishes a reliable lower limit for the supply voltage independent of increasing load current. This accurately set lower bound for the droop voltage enables the controller to more aggressively position the supply voltage at the lower voltage limit of the load, which minimizes voltage overshoot and load power consumption.

Abstract: A ripple-mode controller provides reliable operation in multi-phase power supply circuits, over a variety of operating conditions. Cross-phase blanking allows the controller to preserve the desired phase relationship between the switching pulses its provides to the different output phases, and permits the controller to operate each output phase at nearly 100% duty cycles. Active current sharing compliments blanking operations by adjusting the width of switching pulses the controller provides to one or more of the output phases based on detecting load current imbalances between the different output phases. With active current sharing, the controller prevents one or more output phases from carrying excessive portions of the load current. Further complimenting its operation, the controller may include virtual ripple generation to increase the noise immunity of its ripple-mode regulation.

Abstract: A system and method provides virtual ripple signal generation for use in voltage regulation applications. Some switch-mode power converters or voltage regulators use output signal ripple to effect voltage regulation. A virtual ripple generator provides this type of voltage regulator with a virtual ripple signal comprising an offset component responsive to actual load voltage, but with a generated AC ripple component of arbitrary magnitude that is independent of actual output signal ripple. Unlike the actual output ripple signal, the generated AC ripple component is not dependent on implementation specifics, such as circuit board layout or output capacitor ESR, and may have its gain set independent of the offset component. The generated AC ripple component is synchronized to the inductor switching actions of the voltage regulator and thus reflects actual inductor phase switching in single and multi-phase regulation applications.

Abstract: A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path.

Abstract: A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path.

Abstract: A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path.

Abstract: A portable fluorescent utility light makes advantageous use of one or more generally U-shaped fluorescent tubes by utilizing a transparent end cap or lens at the opposite end of the device from the electrical contact end. Thus, the present light may transmit light from the sides of the cylindrically shaped unit, and also from the end of the device. The relatively narrow end dimension, in comparison to the relatively long length of the cylinder, enables the device to be inserted into relatively small areas, in the manner of a conventional incandescent flashlight, but providing the additional benefit of light emission from the sides of the tube as well. Additional features may be provided, such as a refracting lens to focus the light emitted from the end of the tube, a variety of interchangeable temporary attachment devices, an internal reflector, and/or remotely locating the transformer or ballast and switch and sealing the unit to preclude explosive hazard from vapor ignition.

Abstract: The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets 11' and 12' providing bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in said electromagnets.

Abstract: The invention, a single element magnetic suspension actuator with bidirectional force capability along a single axis, includes an electromagnet 11 and a nonmagnetic suspended element 12. A permanent magnet 13 mounted on the suspended element 12 interacts with a magnetic field established by the electromagnet 11 to produce bidirectional forces in response to a variable force command voltage V.sub.FC applied to the electromagnet 11. A sensor 14 measures the position of the suspended element 12 on the single axis which is a function of force command voltage V.sub.FC.

Abstract: A device for allowing screen to be unrolled from a roll and applied to an open frame while simultaneously maintaining constant tension across the width of the screen. A roll friction bar is provided which extends closely parallel to the circumferential surface of the roll of screen. The roll friction bar is attached to the roll by insertion into the axial openings typically found in rolls of screen material. The free end of the roll of screen is brought around the roll friction bar, doubled back over the screen still on the roll, and fixedly attached to the open frame. The installer then unwinds a desired amount of screen from the roll. By grasping the roll with one hand, the installer is able to both prevent screen from further unwinding from the roll and maintain constant tension across the width of screen being applied.

Abstract: A differential pair having a current source for providing amplification and slewing currents and a large signal circuit responsive to the differential pair input signals for shunting slewing current from the current source away from the differential pair for low input differential and linearly varying the amount of slewing current to be provided from the current source to the differential pair for higher input differentials.

Abstract: A current cancellation circuit having, and method for producing, a low noise spectral density current for cancelling the DC input bias current of an input signal to an amplifier. The cancellation circuit provides for generating a DC cancelling current having a magnitude K times greater than the magnitude of the input DC bias current and then reducing the same by K times. The resulting cancelling current has a reduced noise current spectral density associated with it, thereby reducing the overall noise current spectral density of the input stage.

Abstract: Apparatus for placement in front of tidal wave action to cause settlement of sand from the water and thus land accretion. The apparatus includes a base section having a flexible barrier section secured thereto and extending upwardly therefrom. Method and apparatus for installing and removing the accretion apparatus are also disclosed and claimed.

Abstract: A machine for removing liquid from an area of ground over which the liquid has spread, comprises a convex hood (11) with a flat tray (12) mounted inside it. A motor driven fan (14) blows a downdraft out of the tray's central aperture (16) across the underside of the tray and into an annular gap (13) between the hood and the tray. The travelling air supports the machine above the ground and also lifts any ground-lying liquid into the annular gap and deposits it in a chamber inside the hood.

Abstract: Disclosed is a structure of flexible tensile members which requires only two arrays of said members for obtaining lateral stiffness of said structure, the ends of each member being attached to contour elements and the members of each array having opposite curvatures for forming an axisymmetric geodesic network which is a section of a surface of revolution. The members of both arrays are prestressed and said network is geometrically arranged to be torque-balanced within said contour elements.

Abstract: An annular momentum control device (AMCD) 11 is operated in a strapped down position on a spacecraft. The signals from the position sensors 18 and 19 at the several AMCD magnetic bearing stations a, b, and c are applied to computers (FIGS. 4 and 5) which compute the angular rate about first and second axes in the plane of the AMCD rim 12 and compute the linear accelerations along the first and second axes and along a third axis perpendicular to the first and second axes.

Abstract: Apparatus for providing accurate pointing of instruments on a carrier vehicle and for providing isolation of the instruments from the vehicle's motion disturbances. The apparatus includes two assemblies, with connecting interfaces, each assembly having a separate function. The first assembly is attached to the carrier vehicle and consists of an azimuth gimbal and an elevation gimbal which provide coarse pointing of the instruments by allowing two rotations of the instruments relative to the carrier vehicle. The second or vernier pointing assembly is made up of magnetic suspension and fine pointing actuators, roll motor segments, and an instrument mounting plate around which a continuous annular rim is attached which provides appropriate magnetic circuits for the actuators and the roll motor segments.