Abstract: A pneumatic tire comprises a tread portion provided with sipes, the sipes each having a zigzag configuration at any depth from the top of the sipe to a certain depth, and the zigzag configuration having vertexes Q1 on one side of the zigzag and vertexes Q2 on the other side of the zigzag, wherein as the depth increases from the top of the sipe to said certain depth, the vertexes Q1 shift in the longitudinal direction of the sipe and the direction of the shift is turned at least once such that the vertexes Q1 first shift towards one direction then towards the other direction, thereby describing a zigzag line extending from the top of the sipe to said certain depth and having at least one tuning point, but the vertexes Q2 describe lines which are linear or less zigzag when compared with the zigzag lines described by the vertexes Q1.

Abstract: In a method for allowing a cutter blade to relatively travel along an outer periphery of a semiconductor wafer to cut a protective tape joined to a surface of the semiconductor wafer in conformity with an outer shape of the semiconductor wafer, the cutter blade is allowed to relatively travel along the outer periphery of the semiconductor wafer with a positioning notch provided on the outer periphery thereof. The cutter blade is rotationally turned at the fore half of the notch recessed on the outer periphery of the semiconductor wafer during the relative travel of the cutter blade in such a manner that its blade tip is directed toward the center of the wafer. In contrast, the cutter blade is rotationally turned at the rear half of the notch in such a manner that its blade tip is directed toward the outer periphery of the semiconductor wafer.

Abstract: A fastener module and fabric panel suitable for use with a window covering having a plurality of openable rows is provided. More particularly, the fastener module enables engagement and disengagement of control cords from panels of a window covering.

Abstract: A roll-up door assembly including a flexible curtain made of synthetic rubber or fabric, a curtain winding mechanism and two guide members which extend vertically on opposite sides of the doorway. Side edge sections of the curtain are movable in respective guide members. Each guide has inner and outer wall sections with each wall section having an inwardly projecting, longitudinal rib. The two ribs of each guide form an elongate slot that receives a side edge section of the curtain. Spaced-apart pairs of curtain lock members are mounted on and distributed along each side edge section of the curtain. The lock members of each pair are positioned opposite one another on front and rear surfaces of the curtain respectively. The combined thickness of each pair of lock members and the curtain exceeds the width of the elongate slot.

Abstract: A mounting bracket for a covering for architectural openings such as windows, doors, archways, and the like, includes complementary components on the headrail and the mounting bracket to permit the mounting bracket to be inserted into the headrail and a lock lever is provided with access forwardly of the headrail to lock the headrail in position on the mounting bracket or condition the mounting bracket for release of the headrail from a temporarily secured relationship.

Abstract: A forming method wherein a billet (31, 66, 77, 87, 107, 128, 136, 144, 153, 77B, 77C) comprising a metal-based composite material (27) prepared by mixing an aluminum alloy (22) and a ceramic (15) is subjected to pressure forming to manufacture a formed article, which comprises carrying out the pressure forming by the use of different compression ratios for different portions of the formed article, wherein a compression ratio means the ratio of the height of a billet before the pressure forming to height of the billet after the pressure forming. The above forming method allows the manufacture of a formed article having different volume contents 8Vf) of the ceramic for different portions thereof.

Abstract: An apparatus and method are provided that increase yield and reduce cycle time. In particular, a gate plate for a die casting machine is configured to lessen the waste produced during die casting, resulting in greater yield. Further, the gate plate is configured with tapered sides to produce a draft, leading to less friction during the gate break/pull back sequence. This draft reduces the amount of unpressurized dwell time and subsequently the cycle time for producing the cast part.

Abstract: A method for operating an automated reciprocator for applying lubricant in a die casting system. As a reciprocator is moved between two die halves and a fluid is applied to the dies with the reciprocator, a safety bar is moved ahead of the reciprocator. Any objects in the path of the reciprocator are detected by contact with the safety bar. If the safety bar contacts an object as the reciprocator is moving down, a sensor signals a control system and the reciprocator is stopped.

Abstract: A method of casting a metal ingot with a microstructure that facilitates further working, such as hot and cold rolling. The metal is cast in a direct chill casting mold, or the equivalent, that directs a spray of coolant liquid onto the outer surface of the ingot to achieve rapid cooling. The coolant is removed from the surface at a location where the emerging embryonic ingot is still not completely solid, such that the latent heat of solidification and the sensible heat of the molten core raises the temperature of the adjacent solid shell to a convergence temperature that is above a transition temperature for in-situ homogenization of the metal. A further conventional homogenization step is then not required. The invention also relates to the heat-treatment of such ingots prior to hot working.

Abstract: Low-pressure drop thermal assemblies, systems and methods of making low-pressure drop thermal assemblies for use in high power flux situations. A manifold body is attached to a distributor to form a subassembly. This subassembly is in communication with a substrate surface, which has a semiconductor device in need of thermal management thereon. An enclosed cavity is formed between the target substrate surface and the subassembly, and a seal of the cavity protects critical components residing on the active surface of the semiconductor device. The distributor includes a distributed liquid impingement microjet inlet array isolated from and parallel with a distributed microjet drain array for impinging cooling fluid and removing spent heated fluid in a direction orthogonal to a target surface for maximizing the heat transfer rate, and thereby providing high cooling flux capabilities while enabling low-pressure drops.

Abstract: In an electronic apparatus having a heat-generating element therein, a cooling jacket 100 for transmitting heat generated from the heat-generating element 200 into to a liquid coolant flowing therein, comprises: a cover 130 building up a heat transfer surface to be in contact with a surface of the heat-generating element; a passage 110 for the liquid coolant, which is formed neighboring with the heat transfer surface and wound round in a “S”-like manner within an inside of a main body 120 of the cooling jacket; and an inlet 111 and an outlet 112 attached at both ends of the flow passage of the liquid coolant, and further a dispersion member 150 is disposed in the flow passage, being built up by gathering a plural number of members, each of which has a “U”-like cross-section of an aspect ratio from 10 to 20, thereby diffusing the liquid coolant therein, so as to transfer the heat from the heat-generating element thereto with high efficiency, and thereby enabling to cool down the heat-generating element, fully,

Abstract: A heat sink uses a pump assembly to generate a radial magnetic field. Pipes arranged to house a portion of a first channel and a portion of a second channel are formed in the heat sink. The direction of fluid flow in the first channel and the direction of fluid flow in the second channel is dependent on the radial magnetic field. The radial magnetic field causes fluid in the first channel to flow toward a heat source and fluid in the second channel to flow away from the heat source, thereby resulting in heat transfer between the first and second channels and between the heat sink and the respective first and second channels. The heat sink may also use a heat exchanger assembly that is connected to the heat source, where the heat exchanger assembly is formed of a plurality of channels that each propagate fluid in one of the directions of the first channel and the second channel.

Abstract: A radiator and oil cooler combination for an internal combustion engine includes a concentric type oil cooler in the radiator inlet or outlet tank. A baffle directs coolant flow around the oil cooler. In one embodiment, the baffle is between an inner surface of the outlet radiator tank housing and the outer wall of the oil cooler forming a barrier substantially filling the space therebetween. The baffle is located away from the ends of the oil cooler, intermediate the length thereof, and intermediate the length of the outlet radiator tank containing the tube openings. In another embodiment, the baffle is between and spaced from the oil cooler and the radiator core tube openings. The baffle extends along at least a portion of the length of the outlet radiator tank containing the tube openings and overlaps at least a portion of the length of the oil cooler. In a further embodiment, the baffle is located in the radiator tank near one end of the oil cooler and has an opening spaced from the oil cooler outer wall.

Abstract: The device for exchanging heat according to the invention includes a flow-through device through which a fluid can flow and a fin-like shaped part around which air can flow and which is joined to the one or more flow-through devices wherein the joint allows exchange of heat to occur between the air and the fluid. According to the invention, the joint includes a plurality of recesses positioned along a longitudinal direction of the one or more fin-like shaped parts.

Abstract: A plate-like heat exchanger is provided with a plate-like structure; one or more flow paths respectively including opened ends, the flow paths being formed in an interior of the plate-like structure and running in a first direction; one or more covering members fixed to the plate-like structure, at least one end of the covering members extending to reach any one or more peripheries of the plate-like structure; one or more crossing flow paths defined by the covering members and the plate-like structure, the crossing flow paths being directed to a second direction intersecting the first direction and respectively being linked with the opened ends of the flow paths; and inflow and outflow ports respectively for inflow and outflow of a fluid, the ports respectively being formed at the ends of the covering members at the peripheries of the plate-like structure and linked with the crossing flow paths.

Abstract: A downhole tool is provided that includes a grip assembly for contacting a well formation. The grip assembly includes a gripper body; and a centralizer that is attached to and radially expandable with respect to the gripper body and that has a geometry which is lockable by a locking device. The grip assembly also includes a force amplifier in force transmitting relation with the centralizer, wherein the force amplifier transfers a force in a first direction to a much larger force in a second direction when the centralizer is locked by the locking device.

Abstract: A double pin connector with hydraulic connect and seal assembly having a top portion. The top portion has an upper tubular portion. The upper tubular portion engages an intermediate tubular portion. The intermediate tubular portion has an upper flow path in fluid communication with the first hydraulic connector and a plurality of seals comprising at least one second hydraulic flow path seal.

Abstract: A method is provided for in-situ gasification of coal wherein a network of fractures is formed by providing a substantially vertically disposed borehole and a plurality of substantially horizontally disposed boreholes in fluid communication with the substantially vertically disposed borehole, at least one substantially horizontally disposed boreholes being a fracturing borehole, at least one substantially horizontally disposed boreholes being an injection borehole and at least one substantially horizontally disposed boreholes being an injection borehole. An initial quantity of liquified gas is introduced into the at least one substantially horizontally disposed fracturing borehole whereby the liquified gas vaporizes forms fractures in the formation.

Abstract: A method for lowering the temperature of a portion of a subsurface formation is provided. Preferably, the formation is an oil shale formation. The method includes the step of injecting a cooling fluid under pressure into a wellbore, with the wellbore having been completed at or below a depth of the subsurface formation. In one embodiment the wellbore has an elongated tubular member for receiving the cooling fluid and for conveying it downhole to the subsurface formation. The wellbore also has an expansion valve in fluid communication with the tubular member through which the cooling fluid flows. The method then includes the steps of injecting a cooling fluid under pressure into the wellbore, and expanding the cooling fluid across the first expansion valve. In this way, the temperature of the cooling fluid is reduced. The temperature of the surrounding formation is likewise reduced through thermal conduction and convection. In another embodiment, a partially frozen slurry is used as the cooling fluid.

Abstract: A test plug tool for use in testing a pressure integrity of a pressure control stack mounted to a wellhead, including a joint between a casing and a casing support in the wellhead. The test plug tool includes a test plug of an appropriate diameter used to pressure test the pressure control stack as well as a joint between any one of a surface casing and the wellhead, an intermediate casing and an intermediate casing mandrel, and a production casing and a production casing mandrel. The pressure integrity of the wellhead is ensured at each stage of well drilling and well completion, and safety is improved. Optionally, a backpressure valve permits pressurized fluid that leaks below the test plug tool to flow upwardly through a central bore in a landing tool that is secured to the test plug tool to permit detection of the leak.

Abstract: A method for lowering the temperature of a portion of a subsurface formation is provided. Preferably, the formation is an oil shale formation. The method includes the step of injecting a cooling fluid under pressure into a wellbore, with the wellbore having been completed at or below a depth of the subsurface formation. The wellbore has an elongated tubular member for receiving the cooling fluid and for conveying it downhole to the subsurface formation. The wellbore also has an expansion valve in fluid communication with the tubular member through which the cooling fluid flows. The method then includes the steps of injecting a cooling fluid under pressure into the wellbore, and expanding the cooling fluid across the first expansion valve. In this way, the temperature of the cooling fluid is reduced. The temperature of the surrounding formation is likewise reduced through thermal conduction and convection.

Abstract: A method of localizing the source of a particulate produced with a fluid through a wellbore is provided, the method comprising the steps of: (A) providing marking composition comprising at least one marker that: (i) is capable of binding with a particulate; and (ii) has a detectable property distinguishable from the particulate; (B) introducing the marking composition: (i) through a wellbore; and (ii) into contact with at least a portion of a subterranean formation penetrated by the wellbore; (C) obtaining a fluid produced through the wellbore; and (D) analyzing a particulate produced with the produced fluid for the presence of the marker.

Abstract: The invention provides hydrocarbon recovery processes that may be utilized in heavy oil reservoirs. Horizontal hydrocarbon production wells may be provided below horizontal oxidizing gas injection wells, with distant combustion gas production wells offset from the injection well by a distance that is greater than the hydrocarbon production well offset distance. Oxidizing gases injected into the reservoir through the injection well support in situ combustion, to mobilize hydrocarbons. The process may be adapted for use in a reservoir that has undergone depletion of petroleum in a precedential petroleum recovery process, such as a steam-assisted-gravity-drainage process, leaving a residual oil deposit in the reservoir as well as mobile zone chambers. Processes of the invention may be modulated so that a portion of the residual oil supports in situ combustion, while a larger portion of the residual oil is produced, by channelling combustion gases along the pre-existing mobile zones with the reservoir.

Abstract: A mono-diameter wellbore casing.

Abstract: An apparatus for providing zonal isolation in a wellbore includes a plurality of interlocking sealing elements having anchor elements at the opposing ends. Each anchor element sealingly engages a wellbore tubular whereas the interlocking sealing elements do not engage any portion of wellbore therebetween. In one exemplary application utilizes a wellhead and lubricator positioned over a wellbore under pressure and a conveyance device for conveying equipment into the wellhead. The first anchor, the second anchor and the plurality of interlocking sealing elements are separately conveyed into the wellbore with the conveyance device and sequentially assembled in the wellbore to provide zonal isolation.

Abstract: A system of valves in which the valves operate over a designated pressure interval and are arranged to actuate performance of a sequenced set of events by downhole tools with the application of pressure to said valves.

Abstract: New methods and systems for subterranean fracturing for hydrocarbon wells. A plan of the fracture propagation and in-fracture proppant distribution is used with a real-time model of the status of the fracture dimensions and in-fracture proppant concentration to automatically control flow rates and properties of a fracturing fluid flow stream being used to induce and prop the fracture. Real-time measurements of the status of the fracture are made using surface and/or down-hole sensors. Real-time control over the flow rate and properties of a fracturing fluid flow stream are made by manipulating the fracturing fluid supply equipment. Real-time modifications of the fracturing model are made by comparing fracture sensor measurements of actual fracture dimensions to the predicted dimensions, and then adjusting the model for inaccuracies. Real-time updates to the fracturing plan are made by comparing actual fracture and propping results to desired results, and then adjusting to achieve optimal results.

Abstract: A pipe separator for the separation of fluids, for example the separation of oil, gas and water in connection with the extraction and production of oil and gas from formations beneath the sea bed. The pipe separator includes a pipe-shaped separator body (1) with an inlet and outlet that principally corresponds to a transport pipe (4, 7) to which the pipe separator is connected. The pipe separator further includes a pipe bend or loop (2) arranged in the pipe separator or in connection with its outlet to form a downstream fluid seal in relation to the pipe separator body (1), which is designed to maintain a fluid level in the pipe separator, but which also allows the pipe separator (1) and the loop (2) to be pigged.

Abstract: A subsea petroleum production system for artificial lift, including a pumping module coupled to a flow base, the system being installed downstream of a Wet Christmas Tree (WCT) on the seabed. The pumping module includes at least one submersible centrifugal pump (SCP) inclined with respect to the vertical direction at an inclination of up to 85 degrees from the vertical direction, wherein a flow in said at least one pump is ascending.

Abstract: A pump for pumping liquid from a well having a continuous flexible riser pipe that does not have a coil memory and a flexible actuating rod disposed within the flexible riser pipe. A piston valve unit is disposed at one end of the riser pipe and drivably connected to the actuating, the piston valve unit having an outer diameter that is greater than the inner diameter of the continuous riser pipe.

Abstract: A well jet device operating method comprises running a jet pump into a well, releasing a packer above a productive formation, pumping hydraulic fracturing fluid though a blocking insert in the pump channel, extracting the blocking insert, running flexible pipe into the well through a sealing unit and arranging the lower end thereof at lower formation perforation interval level. The formation is drained, fluid for washing a bottomhole is supplied by the flexible pipe, maintaining the ratio between pipe pressure value and a casing annulus working medium pressure within a range greater than or equal to 0.98. When at least two volumes of hydraulic fracturing fluid is extracted, the pipe fluid supply is stopped. At least 5 minutes after, off the working medium supply to the pump nozzle is shut off, in examining the formation for evaluating the productivity thereof and in bringing the well into operation.

Abstract: A coiled tubing transfer system comprising a carrier having a bed, the bed having a width and the length, the length of the bed being longer than the width of the bed, a reel removably supported on the bed, the reel comprising a spool rotatably journaled in first and second supports, the spool having a core with a diameter and long axis extending between the supports, the long axis having a length greater than the width of the bed, the reel being positionable on the bed in a first position with the long axis of the core extending lengthwise of the bed, the longest dimension of the reel transverse to the long axis of the core being less than the width of the bed and a length of coiled tubing useable in earth borehole operations being wound around the core, the coiled tubing having an outside diameter of from 1? to 9?, the ratio of the diameter of the coiled tubing to the diameter of the core being from 1:20 to 1:70.

Abstract: The invention relates to an apparatus for the treatment of horn splits or cracks on the hoof of horses or other hoofed animals. The apparatus according to the invention is characterized by holding parts (1, 1?) for fastening to the longitudinal sides of a horn split or crack so as to be situated one opposite the other on the hoof and is further characterized by devices (3-14) which connect the holding parts (1, 1?) and by which the distance between the holding parts (1, 1?) is adjustable, causing the horn split or crack to be widened or narrowed.

Abstract: A dry sprinkler for a fire protection system. The preferred dry sprinkler has a metallic disc annulus positionable within a passageway to skew a central axis of a face of the metallic disc annulus with respect to a longitudinal axis of the dry sprinkler so that an expected minimum flow rate based on a rated discharge coefficient is provided. The dry sprinkler operates to provide an expected flow rate over a range of start pressures. The expected flow rate is based on a K-factor rating. The dry sprinkler provides an acceptable level of fluid flow rate from the expected flow rate based on the K-factor for a range of start pressures.

Abstract: A percussion mechanism for a repetitively hammering hand power tool, whose striking frequency and striking intensity are controllable independently of one another, has a striker (2), movable axially forward and backward in a guide barrel (1), and a device (5) exerting pressure on the striker (2), as a result of which the striker can be set into a forward motion in the direction of a tool bit (4) that is insertable into the hand power tool. A blocking element (10) is also provided, with which the striker (2) is blockable in its forward motion, and the striking frequency of the striker (2) is adjustable by controlling the blocking time of the blocking element (10).

Abstract: The present invention relates to methods and apparatus for making in situ thermal property determinations utilizing a heat source employed in wellbore stabilization procedures, well drilling, or well perforating, for example. In particular, using a heat source, such as a laser driller, to enable formation temperature measurements. Based on these measurements, thermal properties of the formation may be inferred.

Abstract: The present invention is an air injection collar for use in the drilling industry that is used to reduce the weight of the column of returning drilling mud and debris without causing unnecessary frictional wear on the drill pipe. The invention is a unique sleeve that is coupled to a drill casing that includes an input port for receiving the pressurized air or other fluid from the surface, an annular plenum extending around the drill casing, and a series of openings in the plenum leading to the inside of the drill casing. These openings disperse the pressurized air or other fluid into the upflowing mud around the central drill pipe so that it is not concentrated in one place, especially the center of the casing, where it could cause frictional damage to the drill pipe.

Abstract: Superabrasive elements, methods of fabricating such elements, and applications utilizing such elements. In one embodiment, a superabrasive element includes a mass of polycrystalline diamond including ultra-dispersed diamond grain structures present in an amount greater than zero weight percent and less than about 75 weight percent of the mass of polycrystalline diamond. Various structures and apparatuses that utilize the superabrasive elements, such as polycrystalline diamond compacts (PDCs) and drill bits are disclosed. Methods of manufacture are also disclosed.

Abstract: An equalizer bar for a tracked vehicle is connected to the track roller frames via an arrangement comprising a pin which is swivel ably mounted to the equalizer bar and held rigidly by the track roller frame. The pin is positively held by the track roller frame, for example by channels in which the pin sits such that the side load is at least partially absorbed by the channel walls rather than the fasteners. The fasteners are located such that they experience minimal side load and aid a positive location of the pin in the channels.

Abstract: A system (30) and method for removing heat from a confined space such as from engine compartment or service brake of a motor vehicle where heat is generated by operation of a heat engine (12) that propels the vehicle or application of a friction brake. The system and method do not use engine or electrical power because natural aspiration is used to remove heated air and Curie Temperature of a ferromagnetic material is used to selectively allow and disallow natural aspiration.

Abstract: The dual-pump fluid distribution system of the present invention preferably includes a sump having hydraulic fluid disposed therein. A first pump driven by an electric motor and a second pump driven by an engine are disposed in fluid communication with the sump. A plurality of vehicle systems are disposed in fluid communication with the first and second pumps. The first pump is configured to transfer hydraulic fluid to the vehicle systems when the engine is off. The first and second pumps are both configured to transfer hydraulic fluid to the vehicle systems when the engine speed is at or below a predetermined value. The second pump is configured to transfer hydraulic fluid to the vehicle systems when the engine speed exceeds the predetermined value. Accordingly, the hydraulic pressure needs of the vehicle systems are met for any given engine speed. A corresponding method in accordance with the present invention is similarly provided.

Abstract: The disclosed seat belt retractor and seat belt apparatus may be used to provide a technology effective for reducing the risk of making a vehicle occupant uncomfortable with regard to the seat belt winding action. A seat belt retractor and seat belt apparatus may comprise an electric motor, a spool capable of winding and unwinding a seat belt for occupant restraint, and a controller configured to perform a control mode in which the electric motor is controlled to rotate in a belt winding direction based on the status of a wearing of the seat belt on a vehicle occupant and the status of a vehicle door corresponding to the seat belt.

Abstract: In an occupant detection or classification system for a motor vehicle, a sensor mat (2) measures the pressure or pressure distribution on a seating surface. A control unit (4) receives the signals from the sensor mat (2) representing an occupancy of the vehicle seat. The temperature of the foam core (1) underlying the seating surface is measured at a location other than in the center of the foam core and, specifically, at the control unit (4).

Abstract: In an industrial vehicle, a controller controls an energizing state of an electromagnetic control valve. The controller is electrically connected to a driver detection switch and a position detection switch. The controller breaks energization of the electromagnetic control valve if the driver detection switch detects that a driver of the vehicle is not seated. The controller energizes or reenergizes the electromagnetic control valve if the driver detection switch detects that the driver is seated and the position detection switch detects that the manipulation position of the direction indication member is a neutral position and then a forward or backward position.

Abstract: The present invention includes a foot-operated accessory pedal located on the floor area of a vehicle interior. The accessory pedal is depressible to activate one of a plurality of vehicle functions. Further included with the present invention is a hand-operated input device operative to assign which of the plurality of vehicle functions the accessory pedal will influence upon selective depressions. Moreover, a display unit is included operative to indicate which of the plurality of vehicle functions the accessory pedal is operative to influence.

Abstract: A vehicle steering control device is provided that suppresses changes in the steering force accompanying the shock transmitted from the road surface during the steering wheel return operation. The vehicle steering device is a steer-by-wire steering device where a steering wheel receiving the steering input which is transmitted electronically to the steering unit which turns steered road wheels of the vehicle. The steering reaction force correction (Gf×F) corresponding to road surface reaction force F is applied to the steering wheel. The device includes a turn/return sensor that senses turn/return of the steering wheel, and during return of steering wheel, road surface reaction force feedback gain Gf is made smaller than the initial turning.

Abstract: The present application relates to a telescopic loader, in particular a reach stacker, having a steering command input device, at least one pick-up to sense the steering angle and a processor unit which is in communication with the steering command input device and with the at least one pick-up and which generates a pre-set signal which can be forwarded to a steering actuator.

Abstract: A dual-sensor stethoscope, or retrofit device for a stethoscope, promotes anti-sepsis and stereoscopy through use of a substantially rigid, generally T-shaped tube for support of dual stethoscope heads. Each head may be rotated away from a body independently for use of a single head or rotated into the same general plane for dual-head stereoscopy. A clinician can create a spatial, three-dimensional (3D) anti-septic barrier and avoid the need to carry multiple stethoscopes. During stereoscopy, the use of a common tube allows the transmission of sound with constructive interference of sound waves. The substantially rigid, generally T-shaped support tube allows a clinician to auscultate with one hand and monitor two locations without transference of pathogens.

Abstract: A device for simulating sound produced by certain equipment, for example a rotor-stator arrangement of a turbomachine, or for generation of opposing sound fields for active sound control, including active sound reduction and active sound amplification, comprises flow obstacles (2) provided in a flow duct (1) flown by a fluid at which vortices (5, 6) are shed at a certain frequency depending on the shape and size of the flow obstacles and the velocity of flow. The quantity and spatial arrangement of the flow obstacles is selected such that a periodically spatially and temporally changing pressure field for the excitation of a sound field (8) of a certain modal content is produced by the entirety of the vortices shed. This sound field reacts synchronizingly on the vortex shedding. The resonant circuit so formed, whose vortex shedding frequency is in the range of the resonant frequency of the sound field to be excited, is the sound source.

Abstract: A safety rail assembly for surrounding a structure protruding from a support surface comprises at least three base units for positioning in a free-standing manner on the support surface, support members each extending substantially vertically from a respective base unit, and barrier members each extending between and supported by a respective pair of successive support members, each base unit comprising a side face which faces inwards of the assembly towards another of the base units or a position between two or more other base units of the assembly, and each side face being of a shape which defines a recess which accommodates part of the protruding structure thereby to restrain lateral movement of the safety rail assembly away from the protruding structure.