Provided is a main bearing for a wind turbine, including a stationary ring and a rotating ring to be coupled to a rotor, whereby the main bearing is a fluid film bearing including several bearing units arranged at the stationary ring around the circumference on both sides of the rotating ring, for radially and axially bearing the rotating ring, and further including a load measurement arrangement for determining measurement data which are a measure for the load applied to or resting on at least one of the axial or radial bearing units.

A measuring device for wave energy conversion performance of a comb-typed permeable breakwater with arcuate walls is provided. The measuring device includes four parts: the comb-type permeable breakwater with arcuate walls, a wave height measuring instrument and pressure sensor fixing and adjusting apparatus, a wave height measuring instrument data collecting and processing apparatus and a pressure sensor data collecting and processing apparatus. The comb-typed permeable breakwater includes combined arc-shaped caissons, partition plates, a back plate, a fixing bottom plate and fixing screws. The wave height measuring instrument data collecting and processing apparatus processes data collected by a wave height measuring instrument and outputs for display. The pressure sensor data collecting and processing apparatus analyzes data collected by a pressure sensor and outputs for display. The measuring device has a stable structure, convenient operation and high experimental accuracy.

The present invention pertains to systems and methods for controlling machines that generate electricity using a source of renewable energy, namely gravity. In overview, an electro-magnetic subsystem of the machine harvests the kinetic energy of a buoyant shuttle as it falls through air and into a bi-level tank. The shuttle is then arrested in the bi-level water tank and returned, by virtue of the shuttle's buoyancy, to its start point for a subsequent duty cycle. The return of the shuttle is made possible by a hydro-pneumatic subsystem of the machine that overcomes the potential energy needed to raise and lower the upper water level in the bi-level tank to compensate for a transit of the shuttle through the tank. The hydro-pneumatic subsystem does this by cyclically maintaining the required difference in water levels in the bi-level tank.

A method of controlling the injection of hydraulic fluid into a high pressure diaphragm compressor having a hydraulic system, the method including: measuring a representation of pressure in a high-pressure part of the hydraulic system of the diaphragm compressor, and maintaining a desired pressure in the high-pressure part of the hydraulic system by adding hydraulic fluid to the high-pressure part of the hydraulic system under the control of a controller on the basis of the measuring of pressure.

A hydraulic machine of the Francis-type includes: an impeller with blades; a guide vane assembly with a ring of guide vanes, a vane-free space extending between the impeller and the guide vane assembly; and at least three resonators for suppressing pressure fluctuations, the resonators respectively including a chamber and a tube connector, the tube connector being connected to the chamber, the tube connector including an end that faces away from the chamber and that opens into the vane-free space, the resonators being configured for suppressing the pressure fluctuations occurring during the operation of the hydraulic machine, the resonators being arranged at a uniform distance from each other in a circumferential direction around the impeller, and the resonators being adjusted to a resonant frequency which is one and the same relative to one another.

A compressor assembly for a portable oxygen concentrator includes a first compressor chamber having a first connector, a second compressor chamber having a second connector, and a tube having a first end having a first connection interface configured to connect to the first connector and a second end having a second connection interface configured to connect to the second connector. The first connection interface is shaped to maintain the connection between the first connector and the first connection interface in a fixed orientation and the second connection interface is shaped to maintain the connection between the second connector and the second connection interface in a fixed orientation. One or more of the first connector, the second connector, and the tube are compliant.

A first aspect of the invention provides a method of monitoring the condition of a yaw system of a wind turbine, the wind turbine comprising a rotor, the yaw system arranged to control a yaw rotation of the rotor, the method comprising: providing design data 5 representing an expected relationship between yaw moment and yaw rotation speed; measuring a pair of parameters, the pair of parameters comprising a yaw moment parameter indicative of a yaw moment applied to the yaw system, and a yaw rotation speed parameter indicative of a yaw rotation speed caused by the yaw moment; using the design data to evaluate whether the pair of parameters deviates from the expected 10 relationship; and determining a condition of the yaw system on the basis of the evaluation.

A first aspect of the invention provides a wind turbine blade having a blade shell that defines a suction side, pressure side, leading edge, and a trailing edge of the blade. The blade further comprises a blade heating system comprising one or more heating elements configured to heat the blade in first and second heating areas, wherein the first heating area is closer to the leading edge than the second heating area is, and the heating system is configured to generate heat fluxes in the first and second heating areas such that the heat flux generated in the first heating area is lower than the heat flux generated in the second heating area.

The invention relates to a sensor arrangement for use on a wind turbine. The sensor arrangement comprises a rotor blade-related sensor, which is arranged in/on a rotor blade, and a non-rotor blade-related sensor, wherein the sensor signals, which are associated with the rotor blade-related sensor, are processed by fusion with the sensor signals which are associated with the non-rotor blade-related sensor. The invention also relates to a method for operating a wind turbine.

A hydroelectric power generation system is included in a channel control system. The channel control system includes a command section that outputs a command value of a flow rate or pressure of a fluid, an opening degree control unit that calculates a target opening degree based on the command value, and a motor-operated valve installed in a channel through which the fluid flows. The valve opens and closes in accordance with the target opening degree. The hydroelectric power generation system includes a water turbine disposed in the channel, a generator driven by the water turbine, and a generator control unit that controls at least one of a torque and a number of rotations of the generator based on opening degree information that indicates a measured value of an actual opening degree of the valve or an opening degree estimated.