Abstract: A method of calibrating the control current startup threshold in a proportionally controlled drive system for a work vehicle is disclosed. To determine a current threshold value for use in the system a control current exhibiting a relatively low value is first applied to the system. Subsequently, the steps of repetitively increasing the control current to a control current start value at which system motion starts and decreasing the control current to a control current stop value at which system motion substantially stops are repetitively conducted. The resultant control current start values and control current stop values are stored in a memory. The stored control current start values and control current stop values are is then averaged to determine a control current threshold value for use in controlling the system.

Abstract: A Stirling engine comprising a casing, a displacer arranged in the casing so as to slide, an expansion chamber and an operation chamber into which, and from which, an operation gas flows with the operation of the displacer, and a power piston that is operated in response to a change in the pressure of the operation gas in the operation chamber, wherein the Stirling engine further comprises a displacer operation means having a moving yoke disposed in the displacer and a pair of electromagnetic solenoids disposed to surround the moving yoke and juxtaposed to each other in the axial direction in the casing; a power piston position detection means for detecting the operation position of the power piston; and a control means for controlling to switch over the excitation of the pair of electromagnetic solenoids of the displacer operation means based on a detection signal from the power piston position detection means.

Abstract: A method and apparatus for preventing the unintended activation of SMA devices by ambient temperatures that exceed the phase transition temperature of the SMA material itself. In one embodiment a passive actuator is coupled to an active actuator, each having identical arrangements of SMA wire, but connected in opposite directions to compensate for temperature drift that is not due to powered heating. A second embodiment consists of a passive SMA wire connected to a latch/release mechanism allowing the actuator itself to move rather than moving the load. In a third embodiment the passive wire is connected to a load coupling, so that the load itself is disconnected from the actuator when the passive wire reaches the phase transition temperature. The passive wire may be made of a lower-temperature wire than the active wires, so that the release action occurs long before the active wire begins to be moved by ambient temperature.

Abstract: The present invention relates to a position indicator for displaying the position of a piston (3) within a cylinder (1) as part of a piston-and-cylinder assembly (1, 3) in a brake system. The provision of a Hall element for a hydraulic generating cylinder is known in the art, with the Hall sensor mounted on the cylinder and a ring magnet mounted on the piston. An object of the invention is to describe a position indicator for a brake system, which has a simple construction and is able to provide signals relating to the position of the brake pedal relatively rapidly. This object is achieved because a Hall element of a Hall sensor (12) is placed in the cylinder wall (1) of the master cylinder, and because a magnetic zone (9) is arranged in the piston-and-cylinder assembly so that the Hall element responds to the piston movement within the cylinder.

Abstract: The invention relates to a channel-shaped connection device for electrical lines, especially signal and ignition lines, of internal combustion engines. At least one support element (2) is provided for preferably pre-assembled electrical lines (3) and components (7) and can be inserted, preferably pushed into receiving elements (4) of the channel-shaped connection device (1).

Abstract: A high-pressure ratio turbocharger of this invention has a two-stage compressor section comprising a first-stage compressor impeller rotatably disposed in a first compressor housing, and a second-stage compressor impeller rotatably disposed in a second compressor housing. The first and second stage compressor impellers are attached to a common shaft, and are positioned within respective compressor housing in a direction facing away from one another. A portion of the second compressor housing is formed from a compressor backplate attached to a turbocharger center housing. A scroll seal is disposed between the first and second compressor housings, and is interposed between the impellers to separate outlet air flow between each respective first and second compressor chamber.

Abstract: Combustion air for use in an engine is normally compressed by a compressor which adds heat during the process of increasing the density of the combustion air. To decrease the heat content of the combustion air, an aftercooler is used. When compressing combustion air to a higher density, the combustion air is compressed by a first compressor section to a first preestablished pressure and temperature and by a second compressor section to a second preestablished pressure and temperature. To decrease the heat content of the highly compressed dense combustion air, a first aftercooler having an air to liquid configuration is used and a second aftercooler having an air to air configuration is used.

Abstract: A supercharged internal combustion engine is provided having a common exhaust manifold and a common combustion air manifold for all engine cylinders. The engine has a plurality of exhaust-driven superchargers that are staggered as a function of the engine output. Each supercharger is engageable or disengageable with the exhaust manifold via its exhaust-driven turbine. Each supercharger, at an input side of its compressor, has a line connection, via a respective valve mechanism, to the output of a charging fan disposed upstream and in series with the compressor. For an oppositely directed changeover between supply air compressed by the charging fan, and ambient air, all of the valve mechanisms are adjusted as a function of the speed of an associated supercharger and a combustion air operating pressure. A processor having a stored requirements profile is provided for the sole release of the valve mechanism of a given supercharger.

Abstract: A power generation system includes a prime mover subsystem and a Rankine-cycle heat energy utilization subsystem. The waste heat stream from the prime mover subsystem provides sufficient thermal content to power the heat energy utilization subsystem. The heat energy utilization subsystem can include a hermetically sealed scroll device, which can expand the working fluid through a single or dual scroll pair configuration. The heat energy utilization subsystem may also include a load-splitting controller, quick-start features and a capacity control module to facilitate rapid response to variable load conditions, as well as provide stand-alone operational capability. The load-splitting controller may incorporate a fuzzy logic controller to coordinate operation between the two subsystems. Energy generated by the heat energy utilization subsystem can be in the form of heat for various domestic and process needs, or can provide supplemental electric current.

Abstract: A method and apparatus for providing a steam boiler/combuster and gasifier that uses a primary dirty fuel, such as waste materials, or high-polluting fossil fuels, and a secondary low-polluting fuel, such as biomass fuels for co-generation of electricity while reducing harmful emissions. The primary fuel is burned in the combuster to create steam in the steam boiler. The steam turns a steam turbine thereby powering a first generator. The dirty exhaust from the combuster is scrubbed by a gasifier. The secondary fuel and oxygen are added to the dirty exhaust in the gasifier creating gas and ash. The gas powers an engine that turns a second generator and releases a cleaner exhaust.

Abstract: A fluidic apparatus for modulating the rate of fuel flow into the combustor of a gas turbine engine. The apparatus includes a fluidic oscillator device (preferably an astable fluidic oscillator, or “flip-flop”) having a supply inlet connected to a fluid fuel source and a pair of outlets one of which is connected to the combustor. The fluidic device operates to output fluid fuel from the outlets alternately, so modulating fuel flow into the combustor.

Abstract: A gas turbine combustor that controls flow rate of air flowing into a primary combustion zone for controlling a local fuel-air ratio comprises no sliding portion that is liable to cause sticking or biting of components operating in high temperature, thereby providing a simple, reliable and efficient combustor and a combustion control method thereof. The gas turbine combustor comprising a liner provided in a combustor case and a bypass duct provided in the liner and enabling a control of flow rate of air supplied into a primary combustion zone via a swirler by causing a portion of the air to pass through the bypass duct, further comprises a float, made of a magnetic substance, provided in the bypass duct so as to open and close the bypass duct by the position of movement of the float and an electromagnetic coil provided outside of the combustor case corresponding to the position of the float so as to move the float.

Abstract: A fuel injection nozzle has a cylindrical nozzle body having a cavity where fuel passes through. A plurality of hollow spokes, each having an aerofoil cross section, are provided around the nozzle body. Each hollow spoke has four fuel injection holes in total on both side surfaces, i.e., two fuel injection holes on each side surface, to inject the fuel, with a distance from the surface of the nozzle body. The inside of each hollow spoke is hollow. The hollow spoke injects the fuel sent to the hollow nozzle body, from the fuel injection holes through the inside of the hollow spoke.

Abstract: A trapped vortex combustor for gas turbine engines. An annular combustor housing is provided having a plurality of inlet centerbodies disposed along a helical axis. The inlet centerbodies include a leading edge structure, opposing sidewalls, a pressurizable cavity, and a rear wall. Inlet centerbodies cooperate with adjacent structure and an aft bluff body to define a trapped vortex cavity combustion chamber for mixing an inlet fluid and burning fuel to form hot combustion gases. Mixing is enhanced by utilizing struts adjacent to the rear wall to create eddies in the fluid flow, and by injecting fuel and/or air in opposition to swirl created by the bulk fluid flow. Hot combustion gases are utilized in a turbine for extraction of kinetic energy, or in heat exchange equipment for recovery of thermal energy. High combustion efficiencies and less than 10 ppm emissions of oxides of nitrogen and of carbon monoxide are achieved.

Abstract: The present invention provides a plate-like body connecting method in which functions such that cooling capability is not reduced. There is provided a plate-like body connecting method for connecting at least two plate-like bodies each having passages that extend along at least one of opposite surfaces thereof and between the opposite surfaces, comprising the steps of disposing the plate-like bodies so that edges of the plate-like bodies are abutted with each other; connecting the plate-like bodies along the edges; forming a groove in the one surfaces of the plate-like bodies along the edges; and attaching a closure to and along the groove.

Abstract: Apparatus for maintaining the temperature of a component of a gas turbine engine below a predetermined maximum working temperature comprises a reservoir for a cooling fluid having a boiling point below the working temperature and in which the component is immersed or with which it is in contact. At least two heat exchangers are associated with the reservoir and operable to effect condensation of vaporised cooling fluid and return of same to the reservoir. Preferably the apparatus is a closed system incorporating three heat exchangers respectively adapted to effect heat exchange with engine fuel, compressed air derived from a fan or low pressure compressor of the engine and ambient air. Means may advantageously be provided to ensure return of condensed cooling fluid to the reservoir when the attitude of the reservoir is altered as a result of aircraft manoeuvres.

Abstract: A control strategy for a gas turbine engine which exchanges future lifetime of the engine for present thrust. Gas turbine engines, such as those used in aircraft, sometimes incur damage, as when they ingest birds, or are struck with ballistic objects fired by an enemy. The invention detects the damage, and invokes a control strategy wherein the engine is operated in a more harsh manner, thereby sacrificing a significant part of the remaining lifetime of the engine, in order to obtain thrust currently.

Abstract: A fuel control system for a gas turbine engine includes logic that is used to facilitate enhanced compressor stall margin when the engine is operating in potential icing conditions is described. The fuel control system is coupled to at least one fuel regulator within the engine, and receives input from a plurality of sensors coupled to the engine. More specifically, the system receives input from environmental sensors, as well as inputs representing compressor inlet temperature, compressor discharge pressure, and corrected core engine speed. Furthermore, the fuel control system also receives input from the other engine fuel regulators.

Abstract: A gas turbine engine flanged shaft (120) is provided with a plurality of anti-score plates (6a, 6b) each of which has two openings which are aligned with corresponding apertures on the flange. Bolts (4) pass through the openings and apertures to attach the anti-score plates (6a, 6b) to the flange (2). The anti-score plates (6a, 6b) have different masses to facilitate shaft balancing.

Abstract: An improved efficiency thermoelectric system is disclosed wherein convection is actively facilitated through a thermoelectric array. Thermoelectrics are commonly used for cooling and heating applications. Thermal power is convected through a thermoelectric array toward at least one side of the thermoelectric array, which leads to increased efficiency. Several different configurations are disclosed to provide convective thermal power transport, using a convective medium. In addition, a control system is disclosed which responds to one or more inputs to make adjustments to the thermoelectric system.

Abstract: Equipment for cooling an HTS receive coil (4) in an MRI scanner to a temperature below the transition temperature of the HTS comprises a refrigeration unit such as a Stirling cooler (1) the cold head (2) of which is connected by a non-metallic thermally conductive rod (3) to the receive coil (4).

Abstract: An integrated phase separator for use in an ultra high vacuum system, for example, a molecular beam epitaxy system, is described. The vacuum chamber has a cryogenic panel disposed therein. The cryogenic panel includes a cryogenic shroud region and a phase separator region. Liquid nitrogen is introduced into the cryogenic panel via an inlet line. As the liquid nitrogen warms and vaporizes, nitrogen vapor rises within the shroud. The phase separator region within the cryogenic panel provides a near atmospheric pressure vapor barrier over the liquid nitrogen so that the nitrogen vapor may escape smoothly through the outlet of the panel, without forming gas bursts. Also, the phase separator region is vacuum jacketed to prevent cryogenic shroud surface temperature changes due to variations in liquid nitrogen levels, thereby increasing the cryogenic shroud's pumping stability. In one embodiment, used in molecular beam epitaxy (MBE), the cryopanel is divided into first and second cooling chambers.

Abstract: Cooling of an enclosed space is effected by means of a cooling system comprising a plurality of cooling units forming ducts having an internal surface on which a layer of liquid is developed, e.g. by means of a wicking material, and through which air from the enclosed space is passed in contact with the liquid layer whereby the liquid is exposed to and evaporates into the air-flow with consequent cooling of the duct wall on which the liquid layer is developed.

Abstract: Heating/defrost constructions of a very low temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: Energy saving in indoor air conditioning is achieved by combining indoor air vertical convection producing means and indoor air conditioning means.

Abstract: An object of the present invention is to improve a heat exchanging capability in an evaporator in a refrigerant cycle system in which a high pressure side is operated at a supercritical pressure. The refrigerant cycle system is a refrigerant cycle system in which a compressor, a gas cooler, an expansion valve and an evaporator are sequentially connected in a cyclic form and a high pressure side is operated at a supercritical pressure, wherein the degree of opening of the expansion valve is adjusted based on the temperature and pressure of a refrigerant at an outlet of the evaporator so as to control the degree of superheat at the outlet of the evaporator. An abstract of the present invention is to make large the degree of superheat at the outlet of the evaporator by means of the expansion valve.

Abstract: A system and method for cooling a room configured to house a plurality of computer systems. A plurality of evaporator units are arranged in parallel and are configured to receive air from the room and to deliver air to the room. The evaporator units are supplied with refrigerant operable to cool the received air in the evaporator units. The air may be controlled in response to temperatures sensed at one or more locations in the room.

Abstract: A system and method for cooling a room configured to house a plurality of computer systems. A heat exchanger unit is configured to receive air from the room and to deliver air to the room. The heat exchanger unit is supplied with cooling fluid operable to cool the received air in the heat exchanger unit. At least one of the temperature of the cooling fluid supplied to the heat exchanger unit and the air delivery to the room may be controlled in response to temperatures sensed at one or more locations in the room.

Abstract: A system and method for cooling a room configured to house a plurality of computer systems. A plurality of evaporator units are arranged in series and are configured to receive air from the room and to deliver air to the room. The evaporator units are supplied with refrigerant operable to cool the received air in the evaporator units. At least one of the temperature of the refrigerant supplied to the evaporator units and the air delivery to the room may be controlled in response to temperatures sensed at one or more locations in the room.

Abstract: An electric compression device has a motor section and a compressor section contained in a housing, an inverter attached to the outer surface of the housing, and a temperature measurement device for measuring a temperature of the inverter. In a stopped state of a refrigeration cycle system, a control unit drives the motor section when the temperature of the inverter, measured by the temperature measurement device, exceeds a predetermined temperature.

Abstract: A transport temperature control apparatus includes a refrigeration circuit and a heat exchanger having an air inlet and an air outlet in fluid communication with a conditioned space. An evaporator coil extends through the heat exchanger between the inlet and air outlet and is fluidly connected to the refrigeration circuit. A divider defines a first portion of the evaporator coil and a second portion of the evaporator coil. A first fan is housed in the heat exchanger and is adjacent the first portion. The first fan has a first operating condition for directing air across the evaporator coil in a first direction and a first non-operating condition. A second fan is housed in the heat exchanger and is adjacent the second portion. The second fan has a second operating condition for directing air across the evaporator coil in a second direction and a second non-operating condition.

Abstract: An air conditioning system for a vehicle includes a compressor driven by a first drive source or a second drive source, or a combination thereof, and an evaporator operationally connected to the compressor via a refrigerant circuit. The system also includes a blower for dispensing air into an interior of the vehicle via the evaporator. The blower is driven by the first drive source or the second drive source, or a combination thereof. Moreover, the system includes a controller for controlling the first drive source and the second drive source. Specifically, when a temperature of air dispensed from the evaporator is greater than a predetermined temperature and a speed of the vehicle is greater than a predetermined speed, the first drive source drives the compressor and the blower.

Abstract: In a heat pump apparatus that having a refrigerating cycle including a compressor 1, a gas cooler 3, a pressure reducing device 5 and an evaporator 7 and is designed so that water can be heated by the gas cooler, refrigerant such as CO2 or the like working in a supercritical area is filled and used at a high-pressure side in the refrigerating cycle and a radiator 21 is equipped between the exit of the gas cooler and the pressure reducing device. The refrigerant temperature at the exit of the radiator is kept to a substantially fixed temperature irrespective of the temperature of hot water to the gas cooler.

Abstract: An inverter apparatus includes a liquid path in which cooling water flows, and in which the cooling water performs cooling at a cooling part located directly underneath the power circuit part of the inverter apparatus. The liquid path includes a first partial structure part formed between a feed pipe and the cooling part, and having a liquid path cross-sectional profile that is gradually reduced in the short-side direction of the cooling part and that is gradually enlarged in the long-side direction thereof; and a second partial structure part formed between the cooling part and a drain pipe, and having a liquid path cross-sectional profile that is gradually enlarged from the short-side of the cooling part and that is gradually reduced from the long-side thereof.

Abstract: An underfloor cable junction unit for installation in a raised-floor system used as cooling air supply duct for devices arranged on the raised floor and having floor panels with cooling air outlets has a top side. The top side or at least a major part of it is open to enable the passage of cooling air through the top side toward a floor panel with cooling air outlets.

Abstract: The compressor head, internal and/or external discriminator, and manifold design in general utilize ball valves on the suction and discharge of a cylinder head in the recovery of refrigerant liquid and/or vapor. The device facilitates the flashing of liquid refrigerant pumped to the compressor which, in turn, assists to cool the compressor head. The flashing of liquid refrigerant to vapor also deters liquid transfer into the compressor enhancing performance thereof. The vapor passages within the discriminator, cylinder head and/or manifold are sized for receipt of spring actuated ball's to open and/or close the vapor passages during suction and/or discharge of refrigerant vapor or liquid by the compressor.

Abstract: A machine (10) for making products such as iced beverages and the like comprises a tank (11) to contain the product in which cooling means (12) and stirring means (13) are present. The tank comprises a product-dispensing tap (14) having a slidable piston (15) and which is provided with sealing elements (17, 18) to offer a hydraulic outward seal to the tank when the tap is in a closed condition. The piston portion (23) between the sealing elements and in contact with the product in the tank has a reduced section to form regions (19) of free circulation of the product around the piston. The tank may comprise surfaces (20) for conveying the product towards such regions so as to facilitate circulation thereof. Thus the product stagnation that may cause bacteria and pollutant formation is avoided and the cleaning operation with use of sanitising solutions is facilitated.

Abstract: An air conditioning device using a false ceiling (2) and ensuring air diffusion along walls by providing intake of treated air into a volume created by the gap between the ceiling (1), the sealed false ceiling (2) and the walls (3), comprising spacers (4) between the wall and the section (6) fixing on edge the false ceiling, of slight width parallel to the wall and uniformly spaced, the spacers, fixed on the wall or on the section fixing on edge the false ceiling, providing a gap between the wall and the false ceiling, so as to enable air diffusion over the entire periphery of the premises. The device is provided with one or several beads (7) clipped between the section and the wall so as to close the gap in the zones where air diffusion should be blocked.

Abstract: A bimodal refrigeration system for use in refrigerated transport containers or refrigerated warehouses. The present invention includes a refrigerated container having an enclosed cargo chamber for storing refrigerated goods and a mechanical refrigeration unit that produces a chilled forced-air current within the cargo chamber. The cargo chamber is designed to guide the forced-air current in a specified discharge and return path. In accordance with the present invention, a row of thermal storage ducts for retaining endothermic storage material are disposed within the cargo chamber. The thermal storage ducts are longitudinally disposed in parallel with the air flow direction of the specified forced-air discharge and return path to enable maximum convective thermal exchange between the forced-air current and the endothermic storage material without obstructing the specified forced-air discharge and return path.

Abstract: A natural and environmentally friendly cooling system is disclosed. The cooling system includes an insulating enclosure, a block of ice within the insulating enclosure, a primary coil of tubing contacting the block of ice and beneath the block of ice for transferring fluid, a return coil of tubing beneath the block of ice for transferring fluid, and a floor pan for collecting water beneath the primary coil and the return coil. The enclosure can include sloped walls to facilitate freezing of water within the enclosure. Alternatively, the block of ice can be delivered via a service.

Abstract: Liquid is distributed substantially uniformly in a liquid-vapour separation column 22 located on an off-shore floating platform using a liquid distributor 24 characterised in that (i) the distance between the two apertures that are furthest apart in the or each secondary distributor is such that the liquid distributor provides, at each angle of tilt, a standard deviation of liquid flow rates through the apertures of the or each secondary distributor that is less than a first predetermined maximum for all angles of tilt; and (ii) the difference in flow rate between the aperture having maximum liquid flow and the aperture having minimum liquid flow in the or each secondary distributor at each angle of tilt is less than a second predetermined maximum for all angles of tilt.

Abstract: The present invention provides a method of producing an oxygen-enriched air stream which includes compressing an air stream, dividing the compressed air stream into a first portion and a second portion, separating the second portion of the air stream to provide an oxygen gas product, introducing the oxygen gas product into the first portion of the compressed air stream to form an oxygen-enriched air stream, and then introducing the oxygen-enriched air stream to the process equipment, which may be by way of example a blast furnace.

Abstract: A multi-function jewelry chain primarily for supporting an upper torso garment, such as bras, bathing suits, bikini tops, halters, strapless dresses, dresses with thin straps, strapless tops, tops with thin straps, and the like. A pair of primary clasps are replaceably attached to a pair of terminal ends of the chain, respectively, and when in place, attach the chain to the upper torso garment without piercing/puncturing or otherwise damaging the upper torso garment.

Abstract: A finger ring having a band for receiving a human finger, a chamber projecting from the top of the band comprising two complementary round hollow members joined by the engagement of circumferential male threads on one member and circumferential female threads on the other member to form a tight seal, one of said members being affixed to said band and the other member being rotatable on said threads and carrying ornamental or decorative effects on its outer surface, a battery and a vibrating motor being snugly received in said chamber, said battery being adapted to power said vibrating motor by making up the male and female threads by manual rotation or twisting of the one said member to bring the vibrating motor into electrical contact with the battery, the rotation or twisting being reversed to turn said vibrating motor off, all without breaking said seal.

Abstract: Wear resistant jewelry apparatus and method of making same wherein articles of jewelry are made from sinterable metal and/or ceramic powder materials compressed into a predetermined configuration and then sintered to form a blank from which a jewelry item may be made and to which softer precious metals, stones, crystals or other materials suitable for use in jewelry may be affixed. Such items of jewelry may have multiple facets and can be fabricated using various disclosed techniques and various combinations of materials.

Abstract: A pendant necklace having a chain having a first end and a second end, a pendant member having a first end and a second end, the pendant member having at least three pendant elements pivotally connected to each other by hinges that permit adjacent elements to pivot about each other in a plane. A pivot stop is associated with each hinge. The first end of the chain is attached to the first end of the pendant member and the second end of the chain is attached to the second end of the pendant member. An attachment means is provided for releasably attaching the first end of the pendant member to the second end of the pendant member. When the first end of the pendant member is attached to the second end of the pendant member, the pendant has a first closed configuration that hangs from the ends of the chain member, e.g., a Star of David, heart or cross.

Abstract: The invention involves providing a plane sheet of glass with recesses by bringing an initially plane sheet of glass, heated to a temperature sufficient for transformation and in partial areas in contact on one side with a negative mould, into engagement on one side with at least one mould cavity of the negative mould whose dimensions correspond to the desired sheet deformation by means of a pressure differential acting upon the sheet, generated by applying a low pressure or partial vacuum and/or gaseous pressure media, such that the respective deformed area/recess of the sheet is surrounded by non-deformed partial areas of the sheet.

Abstract: Methods of melt spinning to make amorphous and ceramic materials

Abstract: Door on a laundry dryer/drum type washing machine including a door frame having a central opening, for opening/closing an opening in a front part of a cabinet for introduction/taking out of laundry, an outer window fixed to a front surface of the door frame, and an inner window fixed to a rear surface of the door frame, wherein the door frame has a front surface curved in left/right directions, and the outer window is curved the same with the door frame, thereby providing a good design of a door and improving washing and drying performance.

Abstract: Anti-theft device for skis comprising a box-like element that can be opened, provided with locking means and in the inside with a groove to house the skis, accessible through an opening of the box-like element. The groove comprises at least a section narrowing point and has a length of at least 150 mm.