Abstract: An engine system includes an internal combustion engine, an electrical power system configured to provide electrical power in the engine system, and an electrified air system powered by the electrical power system to selectively increase a flow of intake air and exhaust gas to the engine. The electrified air system further includes an EGR pump operable to recirculate a portion of exhaust gas output from the engine and an electric turbocharger including a turbine, a compressor driven by the turbine via a shaft coupled therebetween, and an electrical machine coupled to the shaft. The electrical machine is configured to operate in a motoring mode to drive the shaft and cause the compressor to output boosted intake air to the engine and operate in a generating mode to transform rotational power from the shaft into electrical power that is provided back into the electrical power system.

Abstract: A conventional gasoline engine is retrofitted and calibrated to operate as a bi-fuel engine using Hydrogen as the second fuel. When operated with Hydrogen, which typically leads to a reduction of engine output power, the engine is preferably operated in a charged mode and in a lean mode with the engine throttle kept in a wide open position during charged and lean mode operation resulting in a more efficient engine with a reduction of engine output power loss.

Abstract: A two-stage turbocharged internal combustion engine comprises a low-pressure stage turbocharger mounted at a first end side of an engine block and a high-pressure stage turbocharger mounted at the same first end side of the engine block. The respective turbochargers are mounted via a mounting structure, Which also accommodates the charge air coolers associated with the turbochargers. In order to obtain a compact arrangement and reduce a length of pipe connections between the different components, the different charge air coolers are mounted to mounting structure such that they overlap in a plan view of the internal combustion engine. Further, flow directions of charge air in the different charge air coolers are opposite to each other.

Abstract: A cooling arrangement for cooling charge air of a supercharged internal combustion engine. In a charge-air line that leads to the internal combustion engine, there are provided a compressor arrangement, which has at least one compressor stage, and an expansion arrangement, which has at least one expansion stage for lowering the pressure level and thus for cooling the charge air. A cooling device is provided between the compressor arrangement and the expansion arrangement. The at least one compressor stage and the at least one expansion stage are connected in series and are respectively connected in terms of drive to an electric motor. The compressor arrangement has at least two compressor stages connected in parallel.

Abstract: Systems are provided for a crankcase ventilation system. In one example, a crankcase ventilation (CCV) system for an engine configured to transmit crankcase gases into a clean side air duct, the clean side air duct comprising a sensor and a crankcase ventilation spigot, wherein the crankcase ventilation spigot is configured to be disposed downstream of the sensor, the crankcase ventilation spigot having an outlet configured to direct crankcase gases emerging from the crankcase ventilation spigot away from the sensor.

Abstract: A reciprocating engine system includes a turbocharger system including a mechanically driven compressor, an electrically driven compressor, and a compressor bypass valve. A control system is programmed for generating control signals for: under nominal full load operating conditions, minimizing gas flow through the compressor bypass valve and compressing gas within the electrically driven compressor to maintain a speed set point or a full load power set point of the reciprocating engine system, under off nominal full load operating conditions wherein an efficiency of the mechanically driven compressor is reduced, compressing gas within the electrically driven compressor to compensate for the reduced efficiency of the mechanically driven compressor and to maintain the speed set point or the full load power set point of the reciprocating engine system, and under partial load operating conditions, partially diverting the gas flow through the compressor bypass valve in response to the reduced load.

Abstract: A method for charge pressure control of an internal combustion engine that is an integral part of a drive train, wherein the drive train comprises at least the internal combustion engine, an intake line, an exhaust gas line, and an exhaust gas turbocharger. The internal combustion engine has at least one intake valve that fluidically connects the intake line to a combustion chamber of the internal combustion engine, and at least one exhaust valve that fluidically connects the combustion chamber to a first section of the exhaust gas line. The exhaust gas line has a first section between the combustion chamber and the exhaust gas turbocharger, and a second section downstream from the exhaust gas turbocharger. The exhaust gas turbocharger and/or a bypass that bypasses the exhaust gas turbocharger are/is adjustable. In the method, an opening point in time of the at least one intake valve and a closing point in time of the at least one exhaust valve are taken into account.

Abstract: An electric compressor motor housing is provided with: a motor housing main body (8), the interior of which is a cylindrical space for internally equipping a motor, and in which a plurality of refrigerant passages are formed around the cylindrical space, in the direction of the motor axis; an inverter accommodating portion (17) provided in an upper portion of the outer periphery of the motor housing main body (8); compressor attachment feet (19) provided in a plurality of locations in upper and lower portions of the outer periphery of the motor housing main body (8); and a refrigerant intake port (16) provided on a side surface toward the rear end of the motor housing main body (8); wherein one or more lines of ribs (24) are provided on the outer peripheral side surface of the motor housing main body (8), protruding outward and extending in the vertical direction.

Abstract: Systems and methods are provided for a waste heat-driven turbocharger system. In one example, a system for use with a power generator having a rotary machine including a combustor and an exhaust passage flowing exhaust gases from the combustor comprises: a heat exchanger positioned in the exhaust passage; and a turbocharger system, comprising: at least one low pressure turbocharger including a low pressure turbine coupled to an outlet of the heat exchanger and a low pressure compressor coupled to an inlet of the heat exchanger; at least one mid-pressure turbocharger including a mid-pressure turbine coupled to the outlet and a mid-pressure compressor coupled to the low pressure compressor; and at least one high pressure turbocharger including a high pressure turbine arranged in series or parallel with the mid-pressure turbine and a high pressure compressor arranged in series with the mid-pressure compressor and coupled to the combustor of the rotary machine.

Abstract: In an exhaust gas purification apparatus for an internal combustion engine which is provided with a supercharger, an exhaust gas purification catalyst, a bypass passage, a wastegate valve, and a flow regulating member for changing a direction of flow of exhaust gas, the exhaust gas purification catalyst and the flow regulating member are arranged in such a manner that when warming up the exhaust gas purification catalyst, bypass exhaust gas goes toward an upstream side end face of the exhaust gas purification catalyst, whereas when the internal combustion engine is operated in a predetermined high load region, the bypass exhaust gas goes toward the flow regulating member. The flow regulating member includes a guide portion that guides the exhaust gas thus impinged in a circumferential direction of an exhaust pipe, and the guide portion is formed with a plurality of through holes.

Abstract: Methods and systems are provided for controlling boost pressure in a staged engine system comprising a turbocharger and an upstream electric supercharger. In one example, a method may include coordinating the operation of the electric supercharger and an electric supercharger bypass valve and to open the electric supercharger bypass valve to reduce the extent and duration of electric supercharger overboost.

Abstract: An electric compressor motor housing is provided with: a motor housing main body (8), the interior of which is a cylindrical space for internally equipping a motor, and in which a plurality of refrigerant passages are formed around the cylindrical space, in the direction of the motor axis; an inverter accommodating portion (17) provided in an upper portion of the outer periphery of the motor housing main body (8); compressor attachment feet (19) provided in a plurality of locations in upper and lower portions of the outer periphery of the motor housing main body (8); and a refrigerant intake port (16) provided on a side surface toward the rear end of the motor housing main body (8); wherein one or more lines of ribs (24) are provided on the outer peripheral side surface of the motor housing main body (8), protruding outward and extending in the vertical direction.

Abstract: The centrifugal compressor includes an hermetic housing; a drive shaft (4); a first and a second compression stage (8, 9) configured to compress a refrigerant, the first and second compression stages (8, 9) respectively including a first and a second impeller (18, 19), the first and second impellers (18, 19) being connected to the drive shaft (4) and being arranged in a back-to-back configuration; a radial annular groove (27) formed between the back-sides (25, 26) of the first and second impellers (18, 19); an inter-stage sealing arrangement (35) provided between the first and second compressor stages (8, 9) and in the radial annular groove (27); a radial bearing arrangement configured to rotatably support the drive shaft (4); and a thrust bearing arrangement configured to limit an axial movement of the drive shaft (4) during operation.

Abstract: A method of operating a compoundable engine that includes a turbine having a turbine shaft and an intermittent internal combustion engine having an engine shaft. The engine shaft is rotated at a first rotational speed. The turbine is driven by exhaust gases of the intermittent internal combustion engine to rotate the turbine shaft while the engine shaft rotates independently from the turbine shaft. A rotatable load is driven with the turbine shaft. A rotational speed of the engine shaft is increased from the first rotational speed until the turbine shaft reaches a predetermined rotational speed. After the turbine shaft has reached the predetermined rotational speed, the rotational speed of the engine shaft is adjusted until the turbine shaft and the engine shaft are drivingly engageable with each other, and the turbine shaft with the engine shaft are engaged such that both are in driving engagement with the rotatable load.

Abstract: A two-stage air charging system for an internal combustion engine with mixed exhaust gas recirculation includes a high pressure exhaust gas recirculation loop, a low pressure exhaust gas recirculation loop, an air throttle system, a turbo air charging system, and an electric air charging system. A method to control the system includes monitoring desired operating target commands and operating parameters. Feedback control signals are determined based upon the monitored desired operating target commands and the monitored operating parameters. The two-stage air charging system is controlled based on system control commands for each of the high pressure exhaust gas recirculation loop, the low pressure exhaust gas recirculation loop, the air throttle system, the turbo air charging system and the electric air charging system.

Abstract: Embodiments for controlling boost pressure during transient conditions are disclosed. In one example, a method includes, responsive to deactivation of a first turbine of a first turbocharger, deactivating an exhaust valve of a cylinder to flow exhaust gas from the cylinder to a second turbine of a second turbocharger, and adjusting a speed of the second turbocharger via an electric machine coupled to the second turbocharger in a generator mode; and responsive to activation of the first turbine, activating the exhaust valve to flow exhaust gas from the cylinder to the first turbine and the second turbine, and adjusting the speed of the second turbocharger via the electric machine in an auxiliary drive mode.

Abstract: Methods and systems for operating an engine that includes an electrically operated throttle are disclosed. In one example, mitigating actions are taken in response to degradation of the electrically operated throttle so that the engine may be operated in a way that allows a driver to reach a service area.

Abstract: Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, in response to a request to shut down the split exhaust engine system, an intake throttle may be closed and a first valve disposed in a secondary flow passage coupled between the intake manifold, downstream of the intake throttle, and a first exhaust manifold coupled to a first set of exhaust valves, may be opened. As a result, unburned hydrocarbons may be routed to a catalyst disposed in the exhaust passage.

Abstract: Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an intake valve timing, exhaust valve timing of a first set of exhaust valves coupled to the first exhaust manifold, and a position of an exhaust gas recirculation (EGR) valve in an EGR passage may be adjusted in coordination with one another in response to a condition at a compressor. The EGR passage may be coupled between the intake passage, upstream of the compressor, and the first exhaust manifold.

Abstract: A supercharging device for an engine includes an electric supercharger which supercharges intake air, an intercooler which cools intake air discharged from the electric supercharger; and an intake manifold which is disposed substantially horizontally, and is configured to communicate between a downstream end of the intercooler in an intake air flow direction, and intake ports. The downstream end of the intercooler is located on a lower end of the intercooler. The downstream end of the intercooler is disposed substantially at the same height as an upstream end of the intake ports. The electric supercharger is disposed below the intercooler along a surface of the engine on an intake side where the intake ports are opened.

Abstract: Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, a first set of exhaust valves coupled to the first exhaust manifold may be operated at a different timing than a second set of exhaust valves coupled to the second exhaust manifold. Further, a position of a first valve positioned in a first passage coupled between the intake passage and the first exhaust manifold and/or a timing of the first set of exhaust valves may be diagnosed based on an output of a pressure sensor positioned in the first exhaust manifold.

Abstract: Turbine assemblies and related turbocharger systems having direct turbine interfaces are provided. One exemplary turbine assembly includes a first turbine housing having an outlet portion defining a fluid outlet of a first turbine and a second turbine housing having an inlet portion defining a fluid inlet of a second turbine, wherein at least a portion of the outlet portion radially surrounds at least a portion of the inlet portion to provide a direct interface from the fluid outlet of the first turbine to the fluid inlet of the second turbine in an axial direction.

Abstract: Turbine assemblies and related turbocharger systems having direct turbine interfaces are provided. One exemplary turbine assembly includes a first turbine housing having an outlet portion defining a fluid outlet of a first turbine and a second turbine housing having an inlet portion defining a fluid inlet of a second turbine, wherein at least a portion of the inlet portion radially surrounds at least a portion of the outlet portion to provide a direct interface from the fluid outlet of the first turbine to the fluid inlet of the second turbine in an axial direction.

Abstract: Methods and systems are provided for turbine temperature control in an engine system having multiple staged charge boosting devices. In one example, compressed air is provided by a turbocharger compressor until an outlet temperature of the compressor reaches a limit.

Abstract: Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, in response to a request to shut down the split exhaust engine system, an intake throttle may be closed and a first valve disposed in a secondary flow passage coupled between the intake manifold, downstream of the intake throttle, and a first exhaust manifold coupled to a first set of exhaust valves, may be opened. As a result, unburned hydrocarbons may be routed to a catalyst disposed in the exhaust passage.

Abstract: Methods and systems are provided for controlling boost pressure in a staged engine system comprising a turbocharger and an upstream electric supercharger. In one example, a method may include coordinating the operation of the electric supercharger and an electric supercharger bypass valve and to open the electric supercharger bypass valve to reduce the extent and duration of electric supercharger overboost.

Abstract: Various methods for operating a wastegate are provided. In one example, a method of controlling a linked valve actuator system comprises adjusting the actuator near an end stop based on a learned uncertainty end stop region, the region based on operating conditions.

Abstract: An air boost system for a two-cycle engine, such as an EMD engine, which operates with a gear-driven turbo-supercharger. The turbo-supercharger is undersized for the engine, such that it is insufficient to provide air flow for a target air-fuel ratio above a pre-determined mid-load threshold. An additional turbocharger is installed in parallel with the turbo-supercharger, such that the intake manifold may receive air intake from only the turbo-supercharger or from both the turbo-supercharger and the turbocharger. In operation, the turbocharger is active only at loads above the predetermined load threshold.

Abstract: A control device for an internal combustion engine is configured to: calculate a target intake air amount and a target charging efficiency based on a target torque; control an opening degree of a throttle valve (6) based on the target intake air amount; calculate a target supercharger downstream pressure based on the target charging efficiency; detect a pressure on an upstream side of a supercharger; calculate a target compressor driving force based on the target intake air amount, the target supercharger downstream pressure, and the supercharger upstream pressure; and calculate a target bypass valve opening degree based on the target compressor driving force, to thereby control an opening degree of a bypass valve (12) provided to a bypass passage for bypassing the supercharger.

Abstract: A control system for a recirculation valve of a turbocharger includes a target boost module, a close request module, and a close delay module. The target boost module determines a target boost for the turbocharger based on a torque request. The close request module selectively generates a close request to close the recirculation valve based on the target boost. The close delay module, in response to the generation of the close request, delays closing of the recirculation valve.

Abstract: A system and method are provided for estimating the operating speed of a turbocharger. A first pressure value corresponds to pressure at or near the air inlet of the compressor, and a second pressure value corresponds to pressure at or near the air outlet of the compressor. A temperature value corresponds to a temperature at or near the air inlet of the compressor, and a flow rate value corresponds to a flow rate of air entering the air inlet of the compressor. The operating speed of the turbocharger is estimated as a function of the first pressure value, the second pressure value, the temperature value and the flow rate value.

Abstract: A method for operating a boosted internal combustion engine is provided. The engine includes a first cylinder in a first cylinder group and a second cylinder in a second cylinder group, each of the first and second cylinders having two activatable outlet openings adjoined by an exhaust line, one of the outlet openings of each of the first and second cylinders coupled to a first turbocharger including a first turbine and one of the outlet openings of each of the cylinders coupled to a second turbocharger including a second turbine, the method comprising: if engine load is less than a threshold load value implementing a first operating mode that includes deactivating the second cylinder, deactivating one of the activatable outlet openings in the first cylinder, and activating one of the activatable outlet opening in the first cylinder.

Abstract: A vehicle includes an internal combustion engine, an air intake coupled to the internal combustion engine and configured to intake air and supply the air to the engine, a temperature controller coupled to the air intake and to the internal combustion engine, and a control system coupled to the air intake, the internal combustion engine, and to the temperature controller. The control system being configured to receive engine operating data and control a temperature of the air via operation of the temperature controller to control an operating condition of the engine.

Abstract: Methods and systems are provided for estimating exhaust gas recirculation (EGR) flow in an engine including an EGR system. In one example, a method may include operating the EGR system in an open loop feed forward mode based on an intake carbon di oxide sensor output above a threshold engine load and/or when a manifold absolute pressure (MAP) is above a threshold pressure, and operating the EGR system in a closed loop feedback mode based on a differential pressure sensor output when the engine load decreases below the threshold load and/or when the MAP decreases below the threshold pressure.

Abstract: Various systems and methods for controlling dual wastegates via a single wastegate actuator are provided. In one example, a system comprises a first wastegate comprising a first wastegate valve, a second wastegate comprising a second wastegate valve, and a wastegate actuator coupled to each of the first and second wastegate valves to vary openings of the first wastegate valve and the second wastegate valve according to desired boost.

Abstract: A method for controlling air flow through a compressor recirculation passage, comprising: during a first condition: reducing air flow through the compressor recirculation passage based on a margin, the margin based on a rate of air flow at a compressor inlet, a rate of air flow through the compressor recirculation passage, and a rate of EGR flow. In this way, the CRV recirculation flow may be controlled to be less than the amount that could potentially backflow into an air filter disposed in the air intake passage, thus preventing EGR contained in the CRV recirculation flow from fouling the air filter with soot, oil and water.

Abstract: A turbocharged internal combustion engine system includes at least one high pressure turbocharger and at least one low pressure turbocharger arranged in series. A fuel source that provides fuel for gaseous fuel induction operation of the engine is connected to inject fuel between the low pressure compressor of the low pressure turbocharger and the high pressure compressor of the high pressure turbocharger.

Abstract: A combustion engine (E) for a motorcycle includes a crankshaft (26) extending in a widthwise direction of the motorcycle and a supercharger (42) which pressurizes intake air (I). A clutch gear (72) to which a clutch is connected is provided at the right side of the crankshaft (26), and a supercharger gear (80) which drives the supercharger (42) is provided at the left side of the clutch gear (72). The supercharger gear (80) is formed on a crank web (75) disposed such that a journal (68) is located between the clutch gear (72) and the crank web (75).

Abstract: Methods and systems are provided for diagnosing compressor bypass valve degradation. In one example, a method may include indicating degradation of a compressor bypass valve coupled in a compressor bypass based on intake aircharge temperature measured upstream of a compressor inlet via an air charge temperature sensor.

Abstract: Methods and systems are provided for a high-pressure exhaust gas recirculation (EGR) system of a parallel twin-turbocharged internal combustion engine. Using an EGR cooler with a single exhaust inlet and outlet to cool recirculated exhaust gas may increase the complexity and size of the engine package, along with adding unnecessary cost from extra ductwork to decrease the chance of turbocharger boost imbalance. To provide a way to reduce package size without affecting engine performance, an EGR cooler with two exhaust inlets and outlets is used to cool exhaust flows leading from two cylinder banks.

Abstract: A method for supplying vacuum in an engine is disclosed. The method includes controlling a throttle valve positioned upstream of a supercharger arranged in series with and upstream of a turbocharger to draw a fluid from a vacuum line positioned intermediate the throttle valve and a supercharger inlet.

Abstract: An internal combustion engine has at least one cylinder group including a plurality of cylinders and at least one exhaust turbocharger, each cylinder including a plurality of outlet valves for exhaust gas, each outlet valve being assigned an outlet duct which opens into an exhaust manifold and via which the respective exhaust gas, after flowing through the respective outlet valve and outlet duct, can be guided in the direction of an exhaust turbocharger, and first outlet ducts of the cylinders being contoured in the manner of nozzles, and second outlet ducts of the cylinders being contoured in the manner of diffusers.

Abstract: An internal combustion engine has first and second non-deactivatable cylinder banks. Each cylinder bank is assigned exhaust lines which extend from exhaust manifolds. First and second exhaust-gas turbocharger in the exhaust line are assigned to the first and second cylinders, respectively. A first catalytic converter in the first exhaust line contains the first exhaust-gas turbocharger, and is arranged downstream of the first exhaust-gas turbocharger as viewed in the flow direction of the exhaust gas of the first cylinder bank. A second catalytic converter in the second exhaust line contains the second exhaust-gas turbocharger, and is arranged downstream of the second exhaust-gas turbocharger as viewed in the flow direction of the exhaust gas of the second cylinder bank. A flow transfer line is arranged between the first and the second exhaust line, and a first control element, by an exhaust-gas mass flow passing through the flow transfer line can be regulated.

Abstract: A turbocharged internal combustion engine disclosed that may comprise an engine block with a first end side opposing a second end side and a two-stage turbocharged system. The two-stage turbocharged system may comprise a low-pressure turbocharger with a first turbine and a first compressor and a high-pressure turbocharger with a second turbine and a second compressor. A turbine connection may fluidly connect the first turbine and the second turbine and a compressor connection fluidly connects the first compressor and the second compressor. The low-pressure turbocharger is mounted at the first end side of the engine block and the high-pressure turbocharger is mounted at a second end side of the engine block.

Abstract: Provided is a seal air supply system including: a seal air compressor 73 provided separately from an exhaust gas turbine turbocharger 27 to generate compressed air; a seal air supply passage 77 through which the compressed air is supplied to a seal air supply part 79 as seal air of the exhaust gas turbine turbocharger 27; and a surplus air inlet passage 81 bifurcating from the seal air supply passage 77 and guiding surplus air of the seal air to an outlet side of an intake gas compressor 27a of the exhaust gas turbine turbocharger.

Abstract: Various apparatuses and systems are provided for a turbocharger. In one example, the turbocharger system includes a first turbine having an exhaust flow outlet and a second turbine having an exhaust flow inlet. The turbocharger system further includes a transition conduit fluidically coupling the outlet of the first turbine to the inlet of the second turbine, the transition conduit including an expansion region upstream of a first bend, and a bypass which routes exhaust flow around the first turbine, the bypass having an exhaust flow outlet fluidically coupled to the transition conduit downstream of the expansion region.

Abstract: A fluid handling system for a use with an engine is provided. The fluid-handling system may have a first turbine connected to receive a portion of an exhaust flow from the engine, a first compressor driven by the first turbine to pressurize an airflow, and a heat exchanger configured to receive a remaining portion of the exhaust flow from the engine and the airflow from the first compressor. The fluid-handling system may also have a second turbine connected to receive the airflow from the heat exchanger, and a generator driven by the second turbine to generate power.

Abstract: An exhaust system for an engine includes a first exhaust manifold configured to receive exhaust from the engine, a second exhaust manifold configured to receive exhaust from the engine in parallel with the first exhaust manifold, and at least two turbochargers configured to receive exhaust from the first and second exhaust manifolds. The system also includes a first turbocharger valve fluidly connected to one of the at least two turbochargers. The first turbocharger valve is configured to selectively fluidly connect the one of the at least two turbochargers to the first and second exhaust manifolds. The system further includes a recirculation circuit in fluid communication with the first exhaust manifold. The recirculation circuit includes a first recirculation valve configured to regulate passage of exhaust through the recirculation circuit.

Abstract: An engine system may include an electric or mechanical supercharger and an LP-EGR, basically with a turbocharger, an EGR valve, a channel control valve, and a bypass valve, which control the flow rate of external air and exhaust gas, may be integrally operated, and a operation section may be divided into a turbo-lag and low torque section, a mid-load section, and mid/high-load section such that the open amount of EGR valve, channel control valve, and bypass valve may be optimally controlled, such that it may be possible to improve availability for a low-speed/high-load section with turbo-lag reduced, using supercharger and considerably increase the ratio of fuel efficiency improvement in the low-speed/high-load section, using LP-EGR operating with supercharger.

Abstract: A method of controlling airflow of an engine system is provided. The method includes determining a supercharger operating mode and a turbocharger operating mode based on engine load; selectively generating a control signal to a turbocharger based on the turbocharger operating mode; and selectively generating a control signal to a supercharger bypass valve based on the supercharger operating mode.