Abstract: A closed-loop hydraulic apparatus 200 for converting wave energy comprises a pump 201 for pumping a fluid through the apparatus 200. The pump 201 includes a body 202 defining a chamber 203, and a piston 207 that partitions the chamber 203 into a working side 208 and a blind side 209. A buoyant actuator is connected to the piston 207. An inlet 64 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the inlet 64 and into the working side 208 of the chamber 203. An outlet 63 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the working side 208 of the chamber 203 to the outlet 63. A hydraulic controller 102 is operable to control the pump 201 by controlling the pressure of the fluid at the inlet 64 and the outlet 63 so as to optimise the output of the pump 201 in response to tidal variations and/or sea state. The pressure of the fluid at the inlet 64 and the outlet 63 is controlled in accordance with a control algorithm.

Abstract: A closed-loop hydraulic apparatus 200 for converting wave energy comprises a pump 201 for pumping a fluid through the apparatus 200. The pump 201 includes a body 202 defining a chamber 203, and a piston 207 that partitions the chamber 203 into a working side 208 and a blind side 209. A buoyant actuator is connected to the piston 207. An inlet 64 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the inlet 64 and into the working side 208 of the chamber 203. An outlet 63 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the working side 208 of the chamber 203 to the outlet 63. A hydraulic controller 102 is operable to control the pump 201 by controlling the pressure of the fluid at the inlet 64 and the outlet 63 so as to optimise the output of the pump 201 in response to tidal variations and/or sea state. The pressure of the fluid at the inlet 64 and the outlet 63 is controlled in accordance with a control algorithm.

Abstract: A comparative pressure monitoring instrument (10) houses a switch (14) having first and second ports (18) and (20), and a high flow impedance 16. The ports (18) and (20) are in fluidal communication with a first pressure source (72) and a second pressure source (82) respectively. The impedance (16) is coupled (i.e. shunted) across the switch ports (18) and (20) and the first and second pressure sources (72, 82). The switch (14) switches between a first state characterised by a pressure differential across the impedance (16) being less than a preset level and a second state characterised by the pressure differential across the impedance (16) being equal to or greater than the preset difference. Any difference in pressure between the sources (72) and (82) will cause an air/gas flow through the impedance (16) and thus a pressure drop across the impedance (16).

Abstract: A differential comparative pressure monitoring system (10) for monitoring the structural integrity of a structure (30) has a pressure source (12); a first fluidic circuit (14), and a reference fluidic circuit (16) which are connected in parallel to the pressure source (12); and a monitoring device (18). The first and reference fluidic circuits (14) and (16) have substantially matched characteristics. The first circuit (14) has a sensor element (20) which is sealed to a surface (28) on the structure (30). The reference circuit (16) is in fluidic isolation from the surface (28) of the structure (30). The monitoring device (18) takes simultaneous measurements of a common fluidic characteristic of the circuits (14) and (16), and produces a signal indicative the integrity of the structure based on a difference between the simultaneously measured common characteristic.

Abstract: A closed-loop hydraulic apparatus 200 for converting wave energy comprises a pump 201 for pumping a fluid through the apparatus 200. The pump 201 includes a body 202 defining a chamber 203, and a piston 207 that partitions the chamber 203 into a working side 208 and a blind side 209. A buoyant actuator is connected to the piston 207. An inlet 64 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the inlet 64 and into the working side 208 of the chamber 203. An outlet 63 is connected to the working side 208 of the chamber 203 so that the fluid is able to flow from the working side 208 of the chamber 203 to the outlet 63. A hydraulic controller 102 is operable to control the pump 201 by controlling the pressure of the fluid at the inlet 64 and the outlet 63 so as to optimise the output of the pump 201 in response to tidal variations and/or sea state. The pressure of the fluid at the inlet 64 and the outlet 63 is controlled in accordance with a control algorithm.

Abstract: A sensor for detecting surface cracks in a component or structure. A preferred embodiment of the device comprises a flat body portion with a central hole through which a main structural bolt passes. The body portion has a throughway providing fluid communication between an exterior port and a substantially hermetically-sealed area on the structural surface being monitored. A crack which develops in the monitored area surrounding the bolt hole will cause venting of the hermetically-sealed area, in turn causing a change in fluid pressure that can be detected and/or measured to warn of the presence of the crack.

Abstract: A laminated sensor comprises a base stratum and a terminal stratum. The base stratum has a first surface that is affixed to a surface of a structure to be monitored. The terminal stratum is affixed to the opposite second surface of the base stratum. A connector is attached to the terminal stratum. The base stratum is provided with first and second channels and that are cut through the thickness of the base stratum. The terminal stratum is provided with holes that extend through the thickness of the terminal stratum. A first pair of the holes are positioned to register with the first channel, while a second pair of the holes are positioned to register with the second channel. A first conduit is formed by the first channel and the holes; while a second conduit is formed by the second channel and the holes. The connector connects with tubes to provide fluid communication between the conduits and a differential pressure monitoring system.

Abstract: A buoyant actuator (10) is used in apparatus (11) for harnessing wave energy in a body of water such as the ocean. The buoyant actuator (10) is deployed within the body of water (12) and is responsive to wave motion in the body of water. The buoyant actuator (10) includes a body (101) incorporating a flow path along which water can flow, and a gate means (115) for controlling flow along the flow path. The gate (115) includes closure elements configured as flaps (221) providing a barrier (222) across the flow path through the body (101). Each flap (221) is moveable into and out of a condition in which it cooperates with the other flaps (221) to provide the barrier (222). A latch mechanism (231) is provided for releasably retaining each flap (221) in the condition providing the barrier (222). The latch mechanism (231) has a magnetic coupling.

Abstract: A method for detecting separation in a structure that comprises at least two portions or layers affixed together comprises forming a cavity into the structure that passes through an interface formed between the two portions and plumbing the cavity to a monitoring system. A pressure differential is established between the cavity and a reference pressure to which the structure is exposed. A monitoring system monitors for a change in the pressure state of the cavity. Changes in the pressure state are indicative of a separation between the portions or layers.

Abstract: A method of detecting impact damage of a structure having a first surface exposed to potential impacts from an object comprises providing a sensor having a body portion that has a surface provided with an elongated channel. The sensor is fixed to a second surface of the structure such that a conduit is formed by the channel and the surface. The surface is on an opposite side of the structure to the first surface. A pressure differential is established between the conduit and a reference pressure adjacent the conduit. Monitoring is conducted for detecting any change in the differential pressure that may be indicative of a fracture or crack propagating in the second surface.

Abstract: A differential comparative pressure monitoring system (10) for monitoring the structural integrity of a structure or component (30) comprises a pressure source (12); a first fluidic circuit (14), and a reference fluidic circuit (16) which are connected in parallel to the pressure source (12); and a monitoring device (18). The first and reference fluidic circuits (14) and (16) are formed to have substantially matched characteristics. These characteristics include volumetric capacity of each of the circuits, fluid flow rates through the circuits, their temperature characteristics, and diffusion characteristics. The first circuit (14) comprises a sensor element (20) which is sealed to a surface (28) on the structure or component (30) being monitored by the system (10). The reference circuit (16) is in fluidic isolation from the surface (28) of the structure or component (30).

Abstract: A comparative pressure monitoring instrument (10) houses a switch (14) having first and second ports (18) and (20), and a high flow impedance 16. The ports (18) and (20) are in fluidal communication with a first pressure source (72) and a second pressure source (82) respectively. The impedance (16) is coupled (i.e. shunted) across the switch ports (18) and (20) and the first and second pressure sources (72, 82). The switch (14) switches between a first state characterised by a pressure differential across the impedance (16) being less than a preset level and a second state characterised by the pressure differential across the impedance (16) being equal to or greater than the preset difference. Any difference in pressure between the sources (72) and (82) will cause an air/gas flow through the impedance (16) and thus a pressure drop across the impedance (16).

Abstract: A laminated sensor comprises a base stratum and a terminal stratum. The base stratum has a first surface that is affixed to a surface of a structure to be monitored. The terminal stratum is affixed to the opposite second surface of the base stratum. A connector is attached to the terminal stratum. The base stratum is provided with first and second channels and that are cut through the thickness of the base stratum. The terminal stratum is provided with holes that extend through the thickness of the terminal stratum. A first pair of the holes are positioned to register with the first channel, while a second pair of the holes are positioned to register with the second channel. A first conduit is formed by the first channel and the holes; while a second conduit is formed by the second channel and the holes. The connector connects with tubes to provide fluid communication between the conduits and a differential pressure monitoring system.

Abstract: A sensor for detecting surface cracks in a component or structure. A preferred embodiment of the device comprises a flat body portion with a central hole through which a main structural bolt passes. The body portion has a throughway providing fluid communication between an exterior port and a substantially hermetically-sealed area on the structural surface being monitored. A crack which develops in the monitored area surrounding the bolt hole will cause venting of the hermetically-sealed area, in turn causing a change in fluid pressure that can be detected and/or measured to warn of the presence of the crack.

Abstract: A method of manufacturing a sensor 10 for use in a differential pressure monitoring system comprises forming a body portion 12 of the sensor 10 by delivering a molten material to a mould and forming one or more channels 16 in the body portion 12. The channels 16 open onto a first surface 14 of the body portion that, in use, is affixed to a surface of a component to be monitored. The method further comprises forming connectors with the body portion and providing the connectors with a throughway or passage to provide fluid communication with the channels. The connectors, channels and body portion may all be formed concurrently in the moulding process.

Abstract: A method of detecting impact damage of a structure having a first surface exposed to potential impacts from an object comprises providing a sensor having a body portion that has a surface provided with an elongated channel. The sensor is fixed to a second surface of the structure such that a conduit is formed by the channel and the surface. The surface is on an opposite side of the structure to the first surface. A pressure differential is established between the conduit and a reference pressure adjacent the conduit. Monitoring is conducted for detecting any change in the differential pressure that may be indicative of a fracture or crack propagating in the second surface.

Abstract: A method for detecting separation in a structure that comprises at least two portions or layers affixed together comprises forming a cavity into the structure that passes through an interface formed between the two portions and plumbing the cavity to a monitoring system. A pressure differential is established between the cavity and a reference pressure to which the structure is exposed. A monitoring system monitors for a change in the pressure state of the cavity. Changes in the pressure state are indicative of a separation between the portions or layers.

Abstract: A method of monitoring cracking in a component comprises forming a component with a simultaneously formed elongate hole that is internal to the component. A connector having a throughway is attached to the component such that the throughway is in fluid communication with the elongate hole. The elongate hole is connected to a pressure measurement instrument via the connector. A monitoring system then monitors the elongate hole for a change in pressure level.