A device (200) includes a circuit (202) and a driver stage (204) therefor. The circuit includes two sub-circuits (231 and 232). The driver stage includes switcher logic (206) that produces signals that control switching on and off of the sub-circuits. The switcher logic also produces other signals in advance of the signals that control the switching of the sub-circuits. The driver stage includes delay compensations circuits (221 and 222), coupled to the switcher logic and to the circuit, that produce timing signals for the switcher logic. The timing signals are closely aligned with moments that a changing voltage at a node between the sub-circuits passes through threshold voltages. The timing signals compensate for all delays of signals through the device such that a period that both sub-circuits are off is minimized, while ensuring that both sub-circuits are not on at a same time.

A voltage regulator includes an amplifier having a first input coupled to a first reference voltage and a second input coupled to a voltage feedback signal; a multiplexer having a first input coupled to an output of the amplifier, a second input coupled to a voltage clamp signal, and a control input; and a control circuit having a first input coupled to an over current indicator, a second input coupled to a no over voltage indicator, a third input coupled to a timer signal, and an output coupled to the control input of the multiplexer.

A voltage regulator compensation circuit provides power to a dynamic load and includes a power transistor configured to drive the dynamic load, a reference determining transistor configured to establish a voltage reference proportional to a regulated output voltage of the power transistor, and a control circuit coupled to a gate input of both the power transistor and the reference determining transistor. Also included is a comparison engine configured to compare the regulated output voltage and the voltage reference, and a current consuming transistor operatively coupled to an output of the power transistor and configured to provide a varying secondary load. The comparison engine is configured to control the current consuming transistor to increase current draw or decrease current draw from the power transistor based on the difference between the regulated output voltage and the voltage reference.

A charge pump regulator circuit includes a voltage controlled oscillator and a plurality of charge pumps. The voltage controlled oscillator has a plurality of inverter stages connected in series in a ring. A plurality of oscillating signals is generated from outputs of the inverter stages. Each oscillating signal has a frequency or amplitude or both that are variable dependent on a variable drive voltage. Each oscillating signal is phase shifted from a preceding oscillating signal. Each charge pump is connected to a corresponding one of the inverter stages to receive the oscillating signal produced by that inverter stage. Each charge pump outputs a voltage and current. The output of each charge pump is phase shifted from the outputs of other charge pumps. A combination of the currents thus produced is provided at about a voltage level to the load.

A disclosed switching regulator includes a speed-up circuit for speeding up an operation of an error amplifier circuit during the time starting from when a switching element is turned OFF based on an output of an abnormality detection circuit, or starting from a fixed period of time after the switching element is turned OFF based on the output of the abnormality detection circuit, until the next time the switching element is again turned OFF based on an output of a PWM comparison circuit.

In various embodiments a controller for controlling the operation of a switched mode power supply is provided, the controller comprising: a first signal source configured to provide a first set of signals including a set signal and a clear signal, wherein the first set of signals may correspond to a first mode of operation of the switched mode power supply; a second signal source configured to provide a second set of signals including a set signal and a clear signal, wherein the second set of signals may correspond to a second mode of operation of the switched mode power supply; a selecting circuit coupled to the first signal source and to the second signal source, the selecting circuit being configured to select either the first set of signals or the second set of signals; a switching signal generating circuit coupled to the selecting circuit and configured to provide a switching signal to the switched mode power supply based on the set of signals received from the selecting circuit.

A step-down regulator comprising a pseudo constant on time control circuit is disclosed, comprising an on-time generator configured to receive a switching signal provided by the step-down regulator and a control signal provided by the pseudo constant on time control circuit, and generates an on-time signal; a feedback control circuit configured to receive a feedback signal representative of the output voltage of the step-down regulator and generate an output signal; and a logic control circuit coupled to the on-time generator and the feedback control circuit to receive the on-time signal and the output signal and generating the control signal, and a power stage configured to receive an input voltage and the control signal and generate the switching signal.

Systems and methods that provide control circuits having multiple sub-control inputs that control operation of a power electronics device (e.g., a power converter). Each of the multiple sub-control inputs are output from a separate sub-control circuit that includes a feedback circuit having an input tied to a common control node. The common control node is coupled to an input of a controller (e.g., a PWM controller). Outputs of each of the sub-control circuits are coupled to the common control node by a respective switch (e.g., diode, transistor, etc.) so that each of the sub-control circuits may be selectively coupled to the common control node to provide a control signal to a controller. Since components of each of the feedback compensations circuits are biased at a regulation voltage instead of a higher power supply voltage, the control circuit may switch between control modes with minimal delay.

A current mirror circuit, receiving an input current and outputting a plurality of mirroring currents, comprising: a first transistor, wherein a control terminal and a first terminal of the first transistor are connected to a first mirroring current of the input current; at least one second transistor, wherein a control terminal and a first terminal of the at least one second transistor are connected to the at least one second mirroring current of the input current; and a plurality of third transistors, outputting the plurality of mirroring currents from first terminals of the plurality of third transistors, wherein control terminals of the plurality of third transistors are connected to control terminals of the first transistor and the at least one second transistor. The first transistor, the at least one second transistor and the plurality of third transistors are identical.

An electronic apparatus includes a switching element which has a control terminal and is driven by controlling voltage of the control terminal, a driving power supply circuit which supplies voltage required for driving the switching element, an on-driving circuit which is connected to the driving power supply circuit and the control terminal of the switching element and is supplied with voltage from the driving power supply circuit, and which applies a constant current to the control terminal of the switching element to charge the control terminal, thereby turning on the switching element, and at least one diode which is connected between the on-driving circuit and the control terminal of the switching element. The on-driving circuit applies a constant current to the control terminal of the switching element through the diode.

A system that manages a supplemental energy source connected to a power grid uses a two stage control strategy to manage power transfers in and out of the power grid as well as in and out of an energy storage system, such as a battery bank. One stage uses a non-linear transfer function to control an output frequency of a DC-to-AC inverter to limit undesired effects of power transients that occur on the grid. A second stage uses control strategy for transferring energy between the energy storage system and an internal DC link based on a relationship between a voltage on a DC link connecting the first and second stages and a DC link reference voltage, the voltage on the DC link, and a voltage at the energy storage system. The control strategy includes rapid charging, over-charging protection, and grid transient stabilization.

A switched mode power supply provides a reduction of switching losses and increased efficiency. The switched mode power supply includes a first switch coupled to an input terminal configured to receive an input voltage, a second switch, an inductor and an output capacitor. The first switch and the second switch are coupled together at a node, the inductor is coupled between the node and an output terminal, and the output capacitor is coupled to the output terminal. The switched mode power supply further includes a transformer coupled between a control input of the first switch and the node and a pulse generator connected to a control input of the second switch. Further, the transformer includes at most two windings, in particular a primary winding and a secondary winding which are not directly connected to each other.

There is provided a DC-DC converter which converts an input voltage into an output voltage for supply to a load, in which an input terminal receives the input voltage, an output terminal outputs the output voltage, power stages each includes: a high side switch, a low side switch and an inductor, the control unit executes a first mode and a second mode wherein the first mode controls the high side switch and the low side switch in each of the power stages so that a ratio of an output current in each of the power stages to a load current flowing through the load becomes a set value and the second mode controls the high side switch and the low side switch in each of the power stages so that duty ratios of the high side switch and the low side switch are equalized among the power stages.

A low-dropout voltage regulator includes a power transistor configured to receive an input voltage and to provide a regulated output voltage at an output voltage node. The power transistor includes a control electrode configured to receive a driver signal. A reference circuit is configured to generate a reference voltage. A feedback network is coupled to the power transistor and is configured to provide a first feedback signal and a second feedback signal. The first feedback signal represents the output voltage and the second feedback signal represents an output voltage gradient. An error amplifier is configured to receive the reference voltage and the first feedback signal representing the output voltage. The error amplifier is configured to generate the driver signal dependent on the reference voltage and the first feedback signal. The error amplifier includes an output stage that is biased with a bias current responsive to the second feedback signal.

A mode controller shifts, along with increase in an electric power in first and second of chopper circuits and, operation modes of the first and the second of the chopper circuits from a first mode to a third mode via a second mode. An operation controller causes, in the first mode, the first of chopper circuit to perform an chopping operation, and the second of chopper circuit to suspend the chopping operation, in the second mode, causes the first and the second of chopper circuits to alternatively perform the chopping operations, and in the third mode causes both of the first and the second of chopper circuits to perform the chopping operations.

A device for accommodating objects, in particular for use in an airplane, comprises at least one panel. The panel has at least one outer edge which is provided with a rim in order to form a shock-absorbing edge. The rim comprises plastic that is integrally molded onto the outer edge of the panel. The device can be an airplane trolley, folding trolley, container or galley.

An inceptor is provided including a control stick mounted to a seat. The control stick is movable about at least a first axis. A fly-by-wire inceptor control system is housed within a portion of the seat. The inceptor control system is configured to provide input signal indicative of movement of the control stick to a flight control system.

In a method for reducing the impact of a force upon a person seated in a safety seat of a motor vehicle at least a seat unit of the safety seat is restrained at least in part by at least one support strap. The support strap is formed with an extension piece configured to lengthen when exposed to a load as a result of an accident or explosion. A winding unit holds the support strap to shorten an effective length of the support strap and to build up a force to maintain the support strap under tension after the support strap underwent a lengthening in an area of the extension piece as a result of a load caused by a force resulting from an accident or explosion so as to reestablish an effective length of the support strap for lengthening during a subsequent force impact.

An exoatmospheric vehicle uses a control system that includes a thrust system to provide thrust to control flight of the vehicle. A regenerative heat system is used to preheat portions of the thrust system, prior to their use in control of the vehicle. The heat for preheating may be generated by consumption of a fuel of the vehicle, such as a monopropellant fuel. The fuel may be used to power a pump (among other possibilities), to pressurize the fuel for use by thrusters of the thrust system. The preheated portions of the thrust system may include one or more catalytic beds of the thrust system, which may be preheated using exhaust gasses from the pump. The preheating may reduce the response time of the thrusters that have their catalytic beds preheated. Other thrusters of the thrust system may not be preheated at all before operation.

A method and apparatus for lighting a flight deck on an aircraft. A status of the aircraft is identified by a processor unit. The processor unit controls the lighting on the flight deck in response to the status of the aircraft to indicate the status of the aircraft.

A method of creating at least one flight plan of an aircraft includes entering a creation objective which illustrates a type and general characteristics of the flight plan to be created, automatically generating a flight plan outline, automatically generating a targeted request for information relating to missing parameters, entering the requested information relating to the missing parameters, and supplementing automatically the flight plan outline and automatically deleting any discontinuities to create, in a definitive manner, the flight plan.

The invention relates to a de-icing device for an element of a nacelle of a turbojet engine, including at least one heating resistant mat connected to at least one electrical power source (3) and thus defining an assembly (1) of resistant mats, characterized in that the assembly of resistant mats includes one or more subassemblies of resistant mats, each subassembly in turn including one or more resistant mats of the assembly, and each subassembly of resistive mats having a different ohmic value.

A rotor system is disclosed for a reactive drive rotary wing aircraft. Apparatus and methods are disclosed for maintaining the rigidity of the rotor and eliminating play between flight controls and the rotor by mounting swashplate actuators to a flange rigidly secured to the mast. Methods are disclosed for modulating the temperature of oil pumped over one or more of the mast bearing, swashplate bearing, and spindle bearing. The temperature of air passively or actively drawn through rotor may also be modulated to maintain bearing temperature within a predetermined range. Structures for reducing pressure losses and drag on components due to air flow through the rotor are also disclosed. A rotor facilitating thermal management by oil and air flow is also disclosed. Surfaces interfacing between the swashplate and the mast and between control rods and the swashplate or pitch horn may bear a solid lubricant layer.

An unmanned, towable aerovehicle is described and includes a container to hold cargo, an autogyro assembly connected to the container and to provide flight characteristics, and a controller to control operation the autogyro assembly for unmanned flight. The container includes a connection to connect to a powered aircraft to provide forward motive force to power the autogyro assembly. In an example, the autogyro assembly includes a mast extending from the container, a rotatable hub on an end of the mast, and a plurality of blades connected to the hub for rotation to provide lift to the vehicle. In an example, an electrical motor rotates the blades prior to lift off to assist in take off. The electrical motor does not have enough power to sustain flight of the vehicle.

A passively torque-balanced device includes (a) a frame; (b) a drivetrain including a drive actuator mounted to the frame and configured for reciprocating displacement, an input platform configured for displacement by the drive actuator, a plurality of rigid links, including a proximate link and remote links, wherein the rigid links are collectively mounted to the frame, and a plurality of joints joining the rigid links and providing a plurality of non-fully actuated degrees of freedom for displacement of the rigid links, the plurality of joints including a fulcrum joint that is joined both to the input platform and to the proximate rigid link; and (c) at least two end effectors respectively coupled with the remote links and configured for displacement without full actuation.

An integrated aircraft galley structure includes a service module having a plurality of galley inserts including at least one oven and at least one refrigeration unit. The service module is formed with a plurality of bays sized to receive the plurality of galley inserts, along with a human machine interface for controlling all of the galley inserts. The service module further includes a plurality of galley insert modules for controlling each galley insert, and an insert power and control unit for each galley insert for controlling power to said insert. The entire system is controlled by a galley power and control unit for controlling each of the insert galley power and control units, and an AC distribution unit for distributing power to the insert power and control units.

A space efficient lavatory module for commercial aircraft includes an aft facing concave wall recess that provides a greater distance from an upper, forward facing portion of a cabin structure, such as an aircraft passenger seat to avoid having a passenger's head impact the aft facing lavatory or enclosure wall in a sudden aircraft deceleration. The aft facing concave wall recess also provides space for mounting of a protective cushion, in order to reduce a passenger's risk of head trauma in a sudden deceleration, as well as other items, such as a video monitor, a bassinet or infant bed, without inhibiting passenger movement.

According to one embodiment, a windshield attachment device for coupling a windshield to a body includes a fastener portion, a bolt, and an elastomeric load isolator. The fastener portion has an opening therethrough. The bolt is configured to extend through the opening of the fastener portion and couple the fastener portion to the body. The elastomeric load isolator surrounds at least a portion of the fastener portion and separating the fastener portion from the windshield.

Methods and apparatus are presented for spacecraft operation using non-Eigen axis attitude transitions via control momentum gyroscopes (CMGs) to avoid or mitigate singularities by providing a time-varying attitude command vector including a plurality of time-varying attitude command signals or values representing a plurality of spacecraft states and control trajectories as a guidance command input to an attitude controller of the spacecraft without modifying the spacecraft feedback control law.

A device for thermal monitoring a piece of equipment, which is integrated on a craft placed in a forced vacuum environment, an outside part of the equipment projecting outside of a wall of the craft and being subjected to a solar radiation flux, includes an absorbent screen that is suitable for being placed between the outside part of the equipment and the wall of the craft, whereby this absorbent screen has—on at least one portion of its front face, designed to be placed on the side removed from the wall of the craft—an absorptivity αSOLAR that is the largest possible in the field of solar radiation, coupled to a low emissivity εIR in the infrared spectrum. The absorbent screen is made of a very heat-conductive material and has—on at least a portion of its rear face, suitable for being oriented toward the wall of the craft—a high emissivity εIR in the infrared spectrum, typically greater than or equal to 0.7.

A method for simulating the movement behavior of a fluid in a closed moving container is provided. The simulation is based on the determination of the potential movement path of the center of gravity of the volume of the fluid as an elliptical trajectory situated in a disturbance plane having certain semi-axes.

A system and method for mitigating an aircraft incident is provided. The invention includes an aircraft panic component coupled to a terminal component. The aircraft panic component facilitates identification of a panic situation and communicates information associated with the panic situation to the terminal component. The aircraft panic component is further operative to at least partially disable a navigation system and/or operational system of an aircraft. The aircraft can then be sent to a safe zone, navigated remotely and/or a course of action for the aircraft can be determined. A safe zone component is adapted to facilitate identification of a course of action for the aircraft based at least in part upon aircraft positional information, aircraft condition information and/or aircraft resource(s). Further, aircraft navigational information and/or aircraft operational information can be sent via an aircraft communication component to a remote system having a remote communication component and a remote analyzing component facilitating transfer of information related to navigational and/or operational system(s) of the aircraft.

The invention is a projectile, device and system having a roll control device which may be fixed or deployable, for providing torque counter to the spin of the projectile and providing drag on the projectile. The roll control device includes a guidance collar rotatably attached to the projectile located near a front end of the projectile wherein the guidance collar includes one or more guidance collar aero-surfaces shaped to provide torque counter to the spin on the projectile. The guidance collar aero-surfaces may be controlled by a brake and guidance electronics on the projectile. The invention also includes a body collar fixedly attached to the projectile aft of the guidance collar, wherein the body collar includes one or more body collar aero-surfaces and fixed or deployable drag devices. Another embodiment use only a guidance collar aero-surfaces to orient a fixed drag device relative to an Earth inertial reference frame to create asymmetrical drag on the projectile and thereby altering its trajectory.

Systems and methods for activating a down hole tool in a wellbore. A piston is moveable from a first position to a second position for activating the down hole tool. The piston includes a first side exposed to a first chamber, and a second side exposed to a second chamber. A rupture member has a first side exposed to the first chamber and a second side exposed to a third chamber. The rupture member is configured to rupture when a pressure differential between the first chamber and the third chamber reaches a predetermined threshold value, at which point the rupture member allows fluid communication between the first chamber and the third chamber. When the rupture member is intact, the piston is in the first position, and when the rupture member ruptures, the piston moves to the second position and activates the down hole tool.

The well pump flow sleeve assembly provides a method of quickly fitting a flow sleeve to a well pump. The sleeve is made by cutting a pipe normal to the pipe centerline of the pipe surfaces, to a length appropriate for the well pump length. A pump centering bottom cap is inserted into the pipe lower opening and the well pump assembly is then inserted into the pipe upper opening and mates with the bottom cap to align the pump in the sleeve. The pump is now completely within the sleeve with the pump discharge and electrical connection extending through the pipe upper opening. Two flow sleeve cap halves are then fitted around the pump discharge and electrical connection/safety rope to form an upper cap which is inserted into the pipe upper opening. The submersible pump is then ready for service.

Use of two different methods, either each by itself or in combination, to enhance the stiffness, strength, maximum possible use temperature, and environmental resistance of thermoset polymer particles is disclosed. One method is the application of post-polymerization process steps (and especially heat treatment) to advance the curing reaction and to thus obtain a more densely crosslinked polymer network. The other method is the incorporation of nanofillers, resulting in a heterogeneous “nanocomposite” morphology. Nanofiller incorporation and post-polymerization heat treatment can also be combined to obtain the benefits of both methods simultaneously. The present invention relates to the development of thermoset nanocomposite particles. Optional further improvement of the heat resistance and environmental resistance of said particles via post-polymerization heat treatment; processes for the manufacture of said particles; and use of said particles in the construction, drilling, completion and/or fracture stimulation of oil and natural gas wells are described.

Fluid treatment systems and compositions are provided including (a) at least one material including (1) at least one carboxylic acid functional group and (2) at least one sulfur-containing group selected from the group consisting of sulfonyl functional groups, sulfonate functional groups and mixtures thereof; and (b) at least one friction reducing agent selected from the group consisting of guar gums, polyacrylamides, hydratable cellulosic materials, viscoelastic surfactants, and mixtures thereof. The fluid treatment systems and compositions can be used to treat aqueous systems, for example as fracturing fluids for use in fracturing subterranean formations. Methods for inhibiting formation and/or precipitation of metal oxides in an aqueous composition using the fluid treatment systems or compositions also are provided.

Fluid treatment systems and compositions are provided including (a) at least one material including (1) at least one carboxylic acid functional group and (2) at least one sulfur-containing group selected from the group consisting of sulfonyl functional groups, sulfonate functional groups and mixtures thereof; and (b) at least one scale control agent. The fluid treatment systems and compositions can be used to treat aqueous systems, for example as fracturing fluids for treating aqueous compositions found in subterranean formations. Methods for inhibiting formation and/or precipitation of calcium salts in an aqueous composition using the fluid treatment systems or compositions also are provided.

A geological perforating tool (gun) shape charges disposed at an angle that provides an improvement over other known embodiments by accurately securing the charges in the tool to facilitate reliable, reproducible focus of the shaped charges. Charges are disposed on metal strips fitted into slots that are precision cut at predetermined angles in a tool barrel circumference.

A wellbore tubular lift safety system and tubular lifting apparatus for removing tubulars can include a lower section with a lower base plate hole, sliding rods, and a lower gripping member. An upper section can have an upper base plate hole, a saw mounting plate hole, an upper gripping member, and cylinder barrels. The sliding rods can be engaged within the cylinder barrels, and can be moved therein for extending and retracting the upper section. The apparatus can be positioned over the wellbore in a retracted position to align with the tubular. The tubular can be lifted out of the wellbore by gripping the tubular using the gripping members, and extending and retracting the upper section. The apparatus can form lifting holes in the tubular, install lifting members in the lifting holes, saw the tubular, and allow the cut tubular to be lifted via a hoist.

Methods are provided for identifying the location and height of induced subterranean formation fractures and the presence of any associated frac-pack or gravel pack material in the vicinity of the borehole using pulsed neutron capture (PNC) logging tools. The proppant/sand used in the fracturing and packing processes is tagged with a thermal neutron absorbing material. When proppant is present, increases in detected PNC formation and/or borehole component cross-sections, combined with decreases in measured count rates, are used to determine the location of the formation fractures and the presence and percent fill of pack material in the borehole region. Changes in measured formation cross-sections relative to changes in other PNC parameters provide a relative indication of the proppant in fractures compared to that in the borehole region.

Methods of treating a wellbore in a subterranean formation including providing an oil-external treatment fluid, wherein the oil-external treatment fluid is a 3D-network comprising a chemical interaction between a hydrocarbon fluid, an aqueous fluid, and a surface modification agent; providing proppant particulates; suspending the proppant particulates in the oil-external treatment fluid; and introducing the oil-external treatment fluid comprising the proppant particulates into the wellbore in the subterranean formation.

A method may include determining a first particle size distribution for particulate additives in a first wellbore fluid circulated through a wellbore through an earthen formation, and determining a second particle size distribution for drilled cuttings resulting from drilling of the wellbore. The first and second particle size distributions may then be compared to determine a third particle size distribution for the combined particulate additives and the drilled cuttings. A lost circulation material having a fourth particle size distribution may then be selected based on the third particle size distribution and the selected lost circulation material may be pumped into the wellbore.

An apparatus for use in stage-cementing an oil well in the region of a lost-circulation zone that is proximate an annular space defined by the lower end of an outer casing surrounding an inner casing include a load-bearing annular steel plate of substantial thickness that is positioned on, and maintained stationary relative to the inner casing by supporting and retaining means secured to the inner casing, the outer diameter of the plate being less than the inside diameter of the outer casing so that the plate can be lowered with the inner casing string to the desired location inside of the outer casing and, with a layer of gravel, to provide a seal and support the cement poured into the annulus between the inner and outer casings.

In an embodiment, the cement compositions comprise: (i) hydraulic cement, wherein the hydraulic cement has a ratio of CaO to SiO2 in the range of 2.0 to 4.0; and (ii) a water-soluble metaphosphate in a concentration of at least 2.5% bwoc. In another embodiment, the cement compositions comprise: (i) hydraulic cement, wherein the hydraulic cement has a ratio of CaO to SiO2 of less than 2.0; and (ii) a water-soluble metaphosphate; wherein any alkali nitrate is in a concentration of less than 2% bwoc; and wherein any alkali hydroxide, alkali carbonate, or alkali citrate is in a concentration of less than 0.2% bwoc. Methods of cementing in a well comprising forming either of such cement compositions and introducing it into the well are provided.

Systems and methods for managing umbilical lines and one or more jumpers are provided. An example of a system includes a deployment platform carrying a winch and spool assembly, a tether management assembly, and an integrated electrical and/or hydraulic umbilical line extending between a spool on the winch and spool assembly and the tether management assembly. The winch and spool assembly is configured to deploy and to support the umbilical line. The tether management assembly includes a winch and spool assembly for deploying a flying lead and/or annulus jumper adapted to connect to an emergency disconnect package of a well control package for a well. A set of buoyant modules are connected to or integral with a portion of the umbilical line to be used to form an artificial heave compensation loop.

A tool for actuating a blow out preventer includes one or more connections for receiving hydraulic power from a remotely operated vehicle (“ROV”), a first pump for increasing pressure of an operating fluid for the blowout preventer (“BOP”), a second pump for increasing flow rate of the operating fluid, and a conductor for transporting the operating fluid to the BOP. The tool rapidly increases the pressure and flow rate of the fluid flowing to the BOP, and the BOP may be rapidly closed.

A tensioning apparatus for applying a substantially constant tension to a workover riser (12) includes a first portion (40) adapted to be coupled to a workover riser, a second portion (44) adapted to be coupled to a marine riser (14) and tensioning means (46) for providing relative movement between the first portion and the second portion to, in use, tension the workover riser.

An apparatus and method for the actuation of down-hole tools are provided. The down-hole tool that may be actuated and controlled using the apparatus and method may include a reamer, an adjustable gauge stabilizer, vertical steerable tools, rotary steerable tools, by-pass valves, packers, whipstocks, down hole valves, latch or release mechanisms and/or anchor mechanisms.

Disclosed is a downhole well filter (800) and method of use in a tubing string with a power head (704) for creating reverse flow. The filter assembly includes an inner pipe (820) into which fluid flow is directed. The inner pipe is positioned within a cylindrical screen member (830). The well fluid flows through the screen member and debris from the fluid is deposited in the annulus (832) between the inner pipe and screen member. The screen member has a cap (860) at its upper end to prevent fluid from escaping from the upper end of the screen member. The cap may have a pop off valve (870) so fluid can escape from the screen member when the screen becomes clogged with debris or pressure builds within the screen member.