A method of estimating a parameter of a fluid flowing in a passage includes: having a plurality of instruments operable to measure one or more fluid properties flowing in the passage, the plurality of instruments being disposed in the passage and arranged within a common measurement plane; assigning a stream tube to each instrument, each stream tube represents a region of space in the common measurement plane within the passage and each stream tube surrounds one of the plurality of instruments, the stream tubes together correspond to the cross-sectional shape and area of the passage in the common measurement plane; measuring the one or more fluid properties using the instruments to obtain one or more measured values for each stream tube; using the measured value(s) for each stream tube to calculate a derived value for each stream tube; and summing the derived values across all of the stream tubes.

An example method includes obtaining a representation of a change in rotational speed of an electric machine; obtaining a representation of an expected change in rotational speed of the electric machine; and determining, based on the obtained representation of the change in rotational speed of the electric machine and the representation of an expected change in rotational speed of the electric machine, whether a disconnect device has failed, wherein, when operating in an engaged state, the disconnect device is configured to couple rotational mechanical energy between the electric machine and a rotating device, and wherein, when operating in a disengaged state, the disconnect device is not configured to couple rotational mechanical energy between the electric machine and the rotating device.

The method can include determining a mass flow rate W of working fluid circulating through the compressor stage, determining a control parameter value associated to the geometrical configuration of the variable geometry element based on the determined value of mass flow rate W; and changing the geometrical configuration of the variable geometry element in accordance with the determined control parameter value.

A rotating machine control device is provided with: an operating terminal for changing a parameter of the rotating machine; a clearance measuring device which measures the amount of clearance between a rotor and a casing; and a control device body. The control device body, in accordance with the amount of clearance measured by means of the clearance measuring device, determines an operating amount for the operating terminal so as to vary the rate of change in the parameter, and outputs the operating amount to the operating terminal.

A system has first and second fuel stores for first and second fuels, an engine, a fuel distribution system, first and second flow rates of the fuel contributing to a total flow rate of fuel; and a controller for controlling the relative fractions of the total flow rate of fuel to the engine according to the required power output of the engine such that the relative fraction of the total flow rate of fuel to the engine represented by the second flow rate increases with increasing required power output of the engine. The fuels are selected such that using only the second fuel results in a lower engine temperature than using only the first fuel, for the same mechanical power and/or the second fuel has a lower specific energy than the first and/or the second fuel produces more water during combustion than the first fuel per unit of fuel energy.

A system comprises first and second first fuel stores, an engine arranged to produce mechanical power, a fuel distribution system arranged to deliver fuel from the first and second fuel stores to the engine, the first fuel delivered at a first mass flow rate, the second fuel delivered at a second mass flow rate, the first and second mass flow rates contributing to a total mass flow rate of fuel to the engine, and a control system arranged to increase the relative fraction of the total mass flow rate of fuel represented by the second mass flow rate during a period of acceleration of the engine, in order to control a surge margin of the engine. The second fuel is selected to have a higher specific energy than the first fuel and to release a greater mass of water per unit mass of fuel than the first fuel.

An engine system comprises a first fuel store, a second fuel store, an engine arranged to produce mechanical power by combustion or oxidation of a fuel in an engine, a fuel distribution system arranged to deliver fuel from the first and second fuel stores to the engine, the first fuel delivered at a first mass flow rate, the second fuel delivered at a second mass flow rate, the first and second mass flow rates contributing to a total mass flow rate of fuel to the engine; and a control system arranged to control the relative fractions of the total mass flow rate of fuel to the engine represented by the first mass flow rate and the second mass flow rate, based on an engine temperature.

The method can include monitoring a current value of a rate of reduction of rotation speed of the shaft; providing a threshold value of a rate of reduction of rotation speed of the shaft; and generating a signal indicative of the shaft shear event when the current value exceeds threshold value.

A chiller system may include a compressor configured to compress a refrigerant by rotation; a condenser configured to condense the refrigerant compressed by the compressor; an expander configured to expand the condensed refrigerant; an evaporator configured to evaporate the expanded refrigerant; a sensor unit including a plurality of temperature sensors, a speed sensor that senses a rotational speed of the compressor, and a current sensor that senses a current of the compressor; and a controller configured to determine whether to enter into a surge detection logic based on a volatility of data sensed by the sensor unit, and configured to perform surge detection.

Systems and methods for providing power to a blade pitch system in a wind turbine are provided. A blade pitch system can include one or more motors configured to pitch one or more blades of a wind turbine and a power source. The power source can include a plurality of energy storage devices coupled in series. The plurality of energy storage devices can be configured to provide power to the one or more motors during a power loss event. The power source can further include at least one bypass current device configured to allow a bypass current to provide power from at least one energy storage device to the one or more motors. The bypass current can be a current that bypasses one or more failed energy storage devices in the plurality of energy storage devices.